TORQUING - 1.cdn.edl.io · PDF fileFigure 2. Applying Torque to a Bolt Automated torquing...

LEARNINGACTIVITYPACKETMECHATRONICS

B72001-AA08UEN

TORQUING

B72001-AA08UEN TORQUINGCopyright © 2012 Amatrol, Inc.

2

LEARNING ACTIVITY PACKET 8

TORQUING

INTRODUCTIONTorquing systems automatically apply the appropriate amount of torque to fasteners

such as screws during the assembly process. This LAP reviews different types of torquing systems, their adjustment, and programming.

ITEMS NEEDEDAmatrol Supplied 87-MS6 Mechatronics Torquing Station 870-PS7313-AAU, 870-PS7314-AAU, or 870-PS7315-AAU Mechatronics Learning System for Siemens S7-300 - one per station 72024 Siemens S7-300 Programming Cable 82-900 Siemens Step 7 Programming Software

School Supplied Computer with Windows XP Operating System

Amatrol or School Supplied 41222 Hand Tool Kit or Equivalent

FIRST EDITION, LAP 8, REV. CAmatrol, AMNET, CIMSOFT, MCL, MINI-CIM, IST, ITC, VEST, and Technovate are trademarks or registered trademarks of Amatrol, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies.Copyright © 2012, 2011 by AMATROL, INC.All rights Reserved. No part of this publication may be reproduced, translated, or transmitted in any form or by any means, electronic, optical, mechanical, or magnetic, including but not limited to photographing, photocopying, recording or any information storage and retrieval system, without written permission of the copyright owner.Amatrol,Inc., 2400 Centennial Blvd., Jeffersonville, IN 47131 USA, Ph 812-288-8285, FAX 812-283-1584 www.amatrol.com


3

TABLE OF CONTENTS

SEGMENT 1 STATION OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4OBJECTIVE 1 Describe the operation of an automated torquing systemOBJECTIVE 2 Describe the operation of a non-servo electric slideOBJECTIVE 3 Describe the operation of a screw torque module

SKILL 1 Operate an automated torquing station

SEGMENT 2 COMPONENT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24OBJECTIVE 4 Describe how to adjust DC motor speed

SKILL 2 Adjust DC motor speedOBJECTIVE 5 Describe how to adjust a non-servo electric slide

SKILL 3 Adjust a non-servo electric slide

SEGMENT 3 TORQUE ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40OBJECTIVE 6 Describe how to adjust motor torque using a clutch

SKILL 4 Adjust motor torque using a clutchOBJECTIVE 7 Describe how to adjust motor starter overloads

SKILL 5 Adjust motor starter overloads

SEGMENT 4 MODULE SEQUENCING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58OBJECTIVE 8 Describe a sequence of operation of a non-servo electric slide

SKILL 6 Design a PLC program that sequences a non-servo electric slide OBJECTIVE 9 Describe a sequence of operation of screw torque module

SKILL 7 Design a PLC program that sequences a screw torque module

SEGMENT 5 STATION SEQUENCING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87OBJECTIVE 10 Describe a sequence of operation of an automated torquing station

SKILL 8 Design a PLC program that sequences an automated torquing stationOBJECTIVE 11 Describe the operation of a automated torquing station with manual/ auto/ reset functions

SKILL 9 Design a PLC program that provides manual/ auto/ reset functions for an automated torquing station


4

SEGMENT 1STATION OPERATION

OBJECTIVE 1 DESCRIBE THE OPERATION OF AN AUTOMATED TORQUING SYSTEM

An automated torquing system is used to apply a consistent amount of torque to fasteners on an automated assembly line. Typically the part is clamped into place, the fastener is inserted, and automated tooling torques the fastener to the desired level. The tooling typically consists of a spindle that can be controlled electrically (motor driven), pneumatically, or hydraulically. The amount of torque applied to the fastener is controlled in some manner, either electronically or mechanically. One method is to use a clutch that slips at a predetermined level.

An example of an automated torquing system is an automated bottling line. Bottles are fi lled and the cap placed on them. They then move through a torquing module where the caps are tightened to a pre-determined amount.

Figure 1. Automated Torquing Station


5

Torque is a measure of the turning effort caused by a force acting on a part that rotates. In a Mechatronics system, torque typically refers to the amount of force used to turn a bolt that fastens parts together or to install a lid on a product on an automated assembly line. As shown in fi gure 2, the amount of torque created by a person to turn a bolt with a wrench is caused by applying a force at some distance from the pivot point of the rotating part. In this case, the rotating part is the combi-nation of the wrench and bolt.

Figure 2. Applying Torque to a Bolt

Automated torquing systems are often part of an FMS system. The assembly is usually delivered to and removed from the torquing system via a material handling device such as a robot, conveyor, or electric slide.

DISTANCE

BOLT

WRENCH

TORQUE

PIVOTPOINT

FORCEAPPLIED

F

r

T


6

OBJECTIVE 2 DESCRIBE THE OPERATION OF A NON-SERVO ELECTRIC SLIDE

A non-servo electric slide is just one type of device used to hold and position parts for a torquing station. They are typically powered by a motor to move parts from one position or station to the next and are controlled by a PLC. The parts are usually placed on and removed from the slide by a robot or pick and place unit.

Figure 3 shows the construction of an electric slide. The carriage on which the part rides is attached to the carriage guide, which attaches to the bearing slide. The carriage moves along the slide, as the gears are turned by the synchronous belt and DC motor.

Figure 3. Construction of a Non-Servo Electric Slide

SLIDE DETAIL

BELT/PULLEY DETAIL(CARRIAGE REMOVED)

BELT PULLEY

SYNCHRONOUSBELT

DC MOTOR

ADJUSTABLECLUTCH

DC MOTOR

LIMITSWITCHES

ADJUSTABLECLUTCH

BEARINGSLIDE

CARRIAGE

CARRIAGEGUIDE


7

One way to operate the motor is to use reversing motor starter. This allows it to drive in both the forward and reverse directions at a constant speed. A clutch is used to connect the motor to the belt pulleys or gears. The clutch is designed to slip at a preset torque level and protect the motor when the fi xture drives into the hard stops.

Limit switches are typically placed at the beginning of travel (BOT) and end of travel (EOT) positions to indicate to the PLC that the fi xture is at one of the hard stops and to turn off the motor.

Non-Servo Electric Slide Operation

The electric slide operates under the control of a PLC. When the electric slide is in the BOT position, as shown in fi gure 4, the carriage activates a limit switch to indicate the carriage position to the PLC.

Figure 4. Non-Servo Electric Slide

MOTOR

SLIDE

CARRIAGE

BOTLIMIT SWITCH ON

EOTLIMIT SWITCH OFF


8

A part is placed onto the fi xture on the electric slide either manually or auto-matically by another station or robot.

When all of the initial conditions are satisfi ed (i.e. part present, slide at BOT position, start pushbutton pressed), the PLC turns on an output to energize the motor starter and supply power to the motor. This causes the motor to turn, which drives the synchronous belt, and moves the carriage, as shown in fi gure 5.

Figure 5. Slide Moving in Forward Direction

The electric slide fi xture moves until it reaches the hard stop at the EOT posi-tion. A limit switch is activated to indicate to the PLC that the slide has reached the EOT position. This signal causes the PLC to turn off the output that energized the motor starter, causing the motor to stop.

The part can be removed from the slide and moved to another station for further processing. The PLC turns on an output to energize the reverse motor starter to turn on the motor in the reverse direction after the part has been removed. This causes the slide to move back toward the BOT position. When it reaches this position, the BOT limit switch is activated, causing the PLC to turn off the output that energized the reverse motor starter and stop the motor. The slide is then ready to accept a part from a previous station and start the next cycle.

MOTOR

SLIDE

BOTLIMIT SWITCH OFF

EOTLIMIT SWITCH OFF

PART

CARRIAGE


9

OBJECTIVE 3 DESCRIBE THE OPERATION OF A SCREW TORQUE MODULE

A screw torque module is used to apply torque to a fastener. Typically it contains a clamping device that holds the part and a spindle with tooling that applies torque to the fastener. The spindle can be operated with an electric motor, or driven using pneumatics or hydraulics.

In the example in fi gure 6, the spindle motor is coupled to a clutch to control the amount of torque applied to the fastener. The speed of the motor is controlled using a pulse width modulator (PWM). The PWM amplifi er applies varying amounts of average power to the motor, causing it to speed up or slow down. The parts to be torqued are moved to the torquing module by a slide or traverse axis.

Screw Torque Module Operation

The screw torque module operates under the control of a PLC. When the clamp is in the retracted position it actuates a proximity sensor that indicates the position to the PLC.

Figure 6. Screw Torque Module

CLAMP

CLUTCH

TOOLING SPINDLEMOTOR

PROXIMITYSENSOR

PART

PWM

CYLINDER


10

A part placed onto the fi xture either manually or automatically by another station or robot actuates a second sensor.

When all of the initial conditions are satisfi ed (i.e. part present, at BOT posi-tion, start pushbutton pressed), the PLC turns on an output to extend and clamp the part. After the clamp has extended, a proximity sensor indicates the position to the PLC, which signals that the part has been successfully clamped.

After the part has been clamped, the screw torque module motor is energized by the PLC. This causes the tooling at the end of the screw torque module to tighten the fastener in the part to the torque setting determined by the clutch on the module. After the fastener has been torqued, the clamp is released.

Figure 7. Screw Torque Application

PROXIMITYSENSOR

TOOLINGTIGHTENS

FASTER

MOTORENERGIZED

PARTCLAMPED


11

Once the torquing operation is complete, the PLC turns on an output to turn on the slide’s forward motor starter, causing the motor to turn on and the slide to move in the forward direction. When the slide reaches the EOT position, a limit switch indicates the position to the PLC, causing the PLC to turn off the output to the motor starter and stopping the motor. The part can then be removed and moved to another station for further processing. The PLC then turns on an output to the reverse motor starter. This output causes the motor to turn in the reverse direction and return the slide to the BOT position. The slide is then ready to accept a part from a previous station and start the next cycle.

Figure 8. Powered Slide

POWEREDSLIDE

BOT LIMITSWITCH

EOT LIMITSWITCH

SLIDEMOTOR

REVERSEMOTOR

STARTER

FORWARDMOTOR

STARTER


12

SKILL 1 OPERATE AN AUTOMATED TORQUING STATION

Procedure Overview

In this procedure, you will start up and operate the 87-MS6 Torquing Station of the 870 Mechatronics System.

1. Locate the Torquing station, shown in fi gure 9.

Figure 9. Torquing Station

2. Verify that this station has been separated from the other stations. If it has not, then proceed with Step 3 to separate it from the other stations. If it has, then proceed to Step 4.


13

3. Perform the following substeps to separate the Torquing station from the other stations.

A. Remove the power cord from the wall outlet.

B. Remove the adjoining unit’s power cord.

C. Remove the adjoining unit’s pneumatic hose.

D. Disconnect the 9-pin to 9-pin cable from the other unit(s).

E. Loosen the connecting fasteners that hold the work surfaces together by turning the wing nuts CCW.

F. Push the station away from the other stations to give yourself room to work.

4. Perform the following safety check before you begin working on the station. Make sure that you can answer yes to each item before proceeding.

YES/NO SAFETY CHECKOUT

Remove all obstructions from the work area

Check for signs of damage to the equipment

Wear tight fi tting clothing, roll up long sleeves, remove ties, scarves, jewelry, etc.

Tie up long hair

Remove any robot teach pendants from the work area

Locate the emergency stop button

Ensure that safety glasses are worn by people in the area

Ensure that all people are outside any work envelopes

Figure 10. Mechatronics Safety Check

5. Connect an air supply line to the station’s air manifold quick connect. 6. Plug the station’s electrical power cable into a wall outlet. 7. Perform the following substeps to power up the 87-MS6 station.

A. Place the Mode Selector switch in the Manual position.

B. Remove the lockout/tagout device from the electrical power source.

C. Remove the lockout/tagout device from the pneumatic power source.

D. Turn on the air to the station by shifting the lever on the lockout valve.

E. Set the station’s air supply regulator to 50 psi/345 kPa.

F. Turn the station’s Main Power switch to the On position.


14

8. Perform the following substeps to open the PLC programming software.

A. Make sure that the interface from the personal computer to the PLC is connected.

B. Power up the PC and monitor.

C. Start the SIMATIC Manager. 9. Perform the following substeps to open project Torquing.

A. Click the Open Project/Library button.

The Open Project/Library dialog should open.

B. Locate project Torquing.

The project Torquing is provided on a supplemental disk.

If it is not listed on the dialog, click the Browse button on the dialog to view the projects located in the S7Proj folder.

C. Double-click the Torquing icon to open the project.

D. Select Expand All from View menu to expand the project’s contents.

The option is “Expand All” if using STEP 7 Version 5.2 or “Show All Levels” if using STEP 7 Version 5.3.

10. Perform the following substeps to download the PLC project named Torquing to the PLC.

A. Place the PLC’s Mode Selector switch in the RUN position.

B. Reset the PLC.

C. Download the SIMATIC 300 Station object to the PLC.

Several dialogs will appear during the download. Click the appropriate response to continue downloading the program. The last dialog should ask if you wish to perform a complete (Warm) restart.

D. Click Yes on the dialog to complete a warm restart. 11. Press the Output Power pushbutton to enable the PLC’s outputs. 12. Turn the Mode Selector switch to Reset. This will home all of the actuators. Once these are all reset, the Start

pushbutton light should turn off. 13. Turn the Mode Selector switch back to Manual.


15

14. Load the fi xture with a valve assembly in the orientation shown in fi gure 11.


15. Perform the following substeps to step the station through its sequence of operations using the single step, manual mode.

Observe the system and notify your instructor of anything that does not function properly.

You should observe the following steps. 1. Clamp Extends 2. Close Clamp 3. Turn on Screw Motor for 3 Seconds 4. Release Close Clamp 5. Retract Clamp 6. Slide Extends 7. Slide Stops to Remove Part and Waits for Input 8. Retract Slide 9. Cycle Ends

VALVEASSEMBLY

FIXTURE


16

A. Press and release the Start pushbutton to activate step 1 of the sequence.

After the Start pushbutton has been pressed, the PLC turns on an output signal to energize SOL1 to extend the clamp.

B. Press and release the Start pushbutton to activate step 2 of the sequence.

The PLC outputs a signal to energize SOL2 to close the clamp. The clamp should grasp the part in the fi xture.

C. Press and release the Start pushbutton to activate step 3 of the sequence.

The PLC outputs a signal to energize motor starter M1. This causes the Screw Torque module motor to turn on. This is a timed step, the motor should turn for 3 seconds.

D. Press and release the Start pushbutton to activate step 4 of the sequence.

The PLC removes the output signal to SOL2. This causes the clamp to open.

E. Press and release the Start pushbutton to activate step 5 of the sequence.

The PLC removes the output signal to SOL1. This causes the clamp to retract.

F. Press and release the Start pushbutton to activate step 6 of the sequence.

The PLC sends a signal to motor starter M2. This causes the motor to turn on and move the slide in the forward direction. It should move until it reaches the EOT position and actuates limit switch LS1. This signal causes the PLC to turn off the motor.

G. Press and release the Start pushbutton to activate step 7 of the sequence.

The station should stop. This is programmed into the PLC to allow the part to be removed.

H. Press and release the Start pushbutton to activate step 8 of the sequence.

The PLC sends a signal to motor starter M3. This causes the slide motor to turn on in the reverse direction. The slide should move back to the BOT position, where it actuates limit switch LS1. This signal causes the PLC to turn off the motor.

I. Remove the valve assembly from the fi xture. 16. Turn the Mode Selector switch to Auto. If you successfully single-stepped through the complete sequence and all

of the actuators are back in their home position, the Start pushbutton lamp should be off and you can skip to Step 18. If it is not, perform Step 17 to reset the actuators.


17

17. Perform the following substeps to reset the actuators and put the system in Auto mode.

A. Turn the Mode Selector switch to Reset.

This will move all of the actuators back to their home positions.

B. Turn the Mode Selector switch to Auto.

The Start pushbutton lamp should be off at this time, indicating that the actuators are reset and the station is ready to run an automatic cycle.

18. Place another valve assembly on the fi xture in the orientation shown in fi gure 11.

NOTE

When placing valve assemblies on the fi xture, verify they have not yet been through the torquing process or that the knob is loosened prior to placement.

19. Perform the following substeps to observe the station’s automatic cycle.

A. Press the Start pushbutton to start the automatic cycle.

Observe the station while it performs the torquing operation and then moves the part to the end of the slide. Here the cycle will stop to allow the part to be removed. The Start pushbutton indicator is on solid during the cycle to indicate that the station is operating.

B. Press the Start pushbutton again.

The slide should move back to the home position and the cycle ends. 20. Remove the valve assembly from the fi xture. 21. Perform the following substeps to record the operation of the station when

the Stop pushbutton is pressed. This will show you how the system is programmed to respond to the stop

pushbutton.

A. Place a valve assembly on the fi xture in the correct orientation.

B. Press the Start pushbutton to start the cycle again.

C. During the middle of the cycle, press the Stop pushbutton to stop the system. Record whether the system executes a halt, cycle stop or emer-gency stop.

__________________________________________________________

__________________________________________________________

You should observe that the station fi nishes its current step and stops. This means the Stop pushbutton has been programmed to perform a halt function.


18

D. Observe the operator panel indicators and record their status in the table below.

OPERATOR PANEL INDICATORS

Indicator Status (On/Off/Blinking)

Output Power lamp

Start lamp

Emergency Stop lamp

Figure 12. Operator Panel Indicators

Since this is a halt, the machine can resume operation, so you should observe that Output power remains on and the Start pushbutton is off. It has been programmed to do so when the station is in the auto mode and ready to run its automatic cycle. The Emergency Stop lamp should be off because it is not pressed.

E. Observe the PLC processor’s status indicators and record their status.

PLC PROCESSOR STATUS INDICATORS

Indicator Status (On/Off)

SF

DC5V

FRCE

RUN

STOP

Figure 13. PLC Processor Status Indicators

You should see that the PLC processor’s DC5V and Run indicator lights are on, because the station is halted and ready to resume automatic operation.

F. Observe the PLC I/O modules’ status indicators to see if some of them are on.

You should see various input and output indicators on. Which ones are on will depend on the point in the operation at which the stop button was pushed.


19

22. Press the Start pushbutton to restart the system. It should continue where it left off and fi nish the cycle.

NOTE

If any actuators are manually moved while the system is halted, that station may not resume operation when the start pushbutton is pressed. If this occurs, go to Step 24 and restart the system.

23. Repeat Steps 21 and 22 three times, stopping the cycle with the Stop pushbutton at different times to observe how it reacts.

24. Perform the following substeps to restart the station IF any of the inputs change after the Stop button is pressed, otherwise skip to Step 25.

If any of the inputs were changed, such as a part removed from the gripper, or a cylinder moved physically, the system cannot be restarted with the Start pushbutton. This is because the input signals will no longer match those needed to begin the sequence. This is a protective measure to prevent damage to the system.

A. Remove the valve assembly from the fi xture.

B. Turn the mode selector switch to Reset.


C. Turn the mode selector switch back to Auto.

D. Place a valve assembly on the fi xture in the correct orientation.

E. Press the Start pushbutton to start the automatic cycle.

Observe the system while it goes through the cycle before continuing to the next step.

F. Remove the valve assembly from the fi xture. 25. Perform the following substeps to record the operation of the station when

the Emergency Stop pushbutton is pressed. This step will show you how the system is programmed to respond to the

emergency stop pushbutton.



C. During the middle of the cycle, press the Emergency Stop pushbutton to stop the system.


20




Output Power lamp

Start lamp

Emergency Stop lamp


Since this is an emergency stop, the machine cannot resume operations. You should observe that the Output Power is off, the Start pushbutton lamp is off, and the Emergency Stop lamp is on. The Emergency Stop function does not remove the air supply.

E. Observe the PLC processor’s status indicators and record their status.



SF

DC5V

FRCE

RUN

STOP


You should see the PLC processor’s DC5V and Run indicator lights on.


You should see various input indicators on, but all output indicators are off. This is because the Emergency Stop circuit breaks power to the Output Power contactor, which drops all output power.


21

26. Perform the following substeps to recover from the Emergency Stop.

A. Pull the Emergency Stop button out.

B. Remove the valve assembly from the fi xture.

C. Press the Output Power button to turn the outputs back on.

You should hear the contactor pull in to re-establish the power to the outputs.

D. Turn the Mode Selector switch to Reset.


E. Place a valve assembly on the fi xture in the correct orientation.

F. Turn the Mode Selector switch back to Auto.

G. Press the Start pushbutton to start the automatic cycle.

Observe the system while it goes through the cycle before continuing to the next step.

H. Remove the valve assembly from the fi xture. 27. Perform the following substeps to record the operation of the station when

the station experiences a power loss. This will show you how the station is programmed to respond to a power loss.



C. During the middle of the cycle, turn the Main Power switch to Off to remove power to the system.




Output Power lamp

Start lamp

Emergency Stop lamp


Because this is a power loss, simulated by turning the Main Power switch off, power to everything past the Main Power switch is turned off. You should see that all operator panel indicator lamps and PLC indicators are off, but you will notice that the pneumatic power remains. You should also have seen any cylinders (gripper) complete their strokes because they are pneumatically-operated.


22

E. Observe the PLC processor’s status indicators and record which indica-tors are on.



SF

DC5V

FRCE

RUN

STOP


You should see all indicators off because there is no power to the PLC.


Again, you should see all input and output indicators off because the modules have no power.

28. Perform the following substeps to recover from the power loss.

A. Remove the valve assembly from the fi xture.

B. Place the Mode Selector switch in the Manual position.

C. Turn the station’s Main Power switch to the On position.

D. Press the Output Power pushbutton to enable the PLC’s outputs

You should also hear the contactor located next to the PLC module pull in. The Start pushbutton should be blinking because the station is not ready for operation

E. Turn the Mode Selector switch to Reset.

This will move all of the actuators back to their home positions. It will also turn the vacuum to the gripper off. Once the actuators are reset, the Start pushbutton should turn off.

F. Place a valve assembly on the fi xture in the correct orientation.

G. Turn the Mode Selector switch to Auto.

H. Press the Start pushbutton to restart the operation.

You should see the system start through its sequences.

I. Run the system through two complete cycles to make sure it has recovered correctly, removing and replacing valve assemblies as necessary.

29. Perform the following substeps to shut down the 87-MS6 Torquing station.

A. Close the LAD/STL/FBD Editor.

B. Close the SIMATIC Manager.

C. Turn off the PC and monitor.

D. Turn the 87-MS6’s Main Power switch to Off.

E. Perform a lockout/tagout on the system’s electrical power source.

F. Perform a lockout/tagout on the system’s pneumatic power source.


23

SEGMENT 1 SELF REVIEW

1. Torque is a measure of the turning effort caused by a force acting on a part _________.

2. An automated torquing system is used to apply ________ amounts of torque to fasteners on an automated assembly line.

3. A non-servo electric ______ is used to hold and position parts for processing.

4. The electric slide operates under the control of a ____.

5. A Screw Torque module is used to apply ______ to a fastener.

6. A Screw Torque module typically contains a ________ device that holds the part and a spindle with tooling that applies torque to the fastener.

7. The spindle motor can be coupled to a ______ to control the amount of torque applied to the fastener.

8. The speed of the motor can be controlled using a _____________________ amplifi er.


24

SEGMENT 2COMPONENT ADJUSTMENT

OBJECTIVE 4 DESCRIBE HOW TO ADJUST DC MOTOR SPEED

One advantage of a DC motor is that its speed can be easily varied. The most basic method of controlling DC motor speed is to vary the resistance of a rheostat (variable resistor) that is connected to the motor windings. However, this method is not very energy effi cient. A more effi cient device commonly used is a pulse width modulator (PWM) amplifi er, shown in fi gure 18.

Figure 18. Pulse Width Modulator Amplifi er

One additional advantage of a PWM circuit is that the pulses reach the full supply voltage instead of the reduced amount delivered by a resistive control, and it produces more torque in the motor.


25

Pulse width modulators work by switching the power supplied to the motor on and off rapidly. The DC voltage is converted to a square-wave signal, as shown in fi gure 19, alternating between fully on and zero. This gives the motor a series of power kicks. If the switching frequency is high enough the rotor’s momentum keeps the motor running at a steady speed. Modulating the width of the pulse (the amount of time it is on) adjusts the duty cycle of the signal so the average power can be varied, which varies the motor speed. Depending on the design, this can be accomplished by turning a potentiometer, or by turning a switch on the PWM unit.

Figure 19. Square Wave Signal

Another advantage of a PWM controller over a resistive power controller is higher effi ciency. At a 50% level, the PWM controller will use about 50% of full power, almost all of which is transferred to the load. In contrast, a resistive controller at 50% load power would consume about 71% of full power, 50% of the power goes to the load and the other 21% is wasted heating the series resistor.

The main disadvantage of a PWM controller is that it adds complexity to the motor starter circuits. There is also the possibility that the PWM can generate radio frequency interference that may cause interference with other nearby electronic devices.

12V

0V


26

SKILL 2 ADJUST DC MOTOR SPEED

Procedure Overview

In this procedure, you will use the PWM amplifi er to change the DC motor speed on the 87-MS6 Torquing Station to adjust the speed of the Screw Torque module’s DC motor. This will show you how changing the speed of a PWM-controlled DC motor can be done quickly and easily.

1. Locate the 87-MS6 Torquing station. 2. Verify that this station has been separated from any other stations. If it has not, then separate it from the other stations. If it has, then proceed to

Step 3. 3. Perform the following safety check before you begin working on the module.

Make sure that you can answer yes to each item before proceeding.





Tie up long hair







27

4. Connect an air supply line to the station’s air manifold quick connect. 5 .Plug the station’s power cable into a wall outlet. 6. Perform the following substeps to power up the station.




D. Turn on air to the station by shifting the lever on the lockout valve.


F. Turn the station’s Main Power switch to the On position. 7. Perform the following substeps to open the PLC programming software.







If it is not listed on the dialog, click the Browse button on the dialog to view the projects located in the S7proj folder.


D. Select Expand All from the View menu to expand the project’s contents.




B. Reset the PLC.


Several dialogs will appear during the download. Click the appropriate response to continue downloading the program.

The last dialog should ask if you wish to perform a complete (Warm) restart.

D. Click Yes on the dialog to complete a warm restart. 10. Press the Output Power pushbutton to enable the PLC’s outputs.


28

11. Locate the PWM amplifi er, shown in fi gure 21. It will be used to adjust the speed of the Screw Torque module motor.

Figure 21. Pulse Width Modulator used to Control Screw Motor Speed

TOGGLESWITCH

SPEEDCONTROL

KNOB

PULSEWIDTH

MODULATOR


29

Figure 22 shows the wiring for the pulse width modulator. Lines 1 and 2 carry the incoming power from the interface terminals to the PWM. Lines 3 and 4 carry power from the PWM to the screw torque motor. Lines 5-8 are optional analog connections. Line 9 is the output from the PLC that calls for the screw torque motor to turn on. The toggle switch on the PWM changes the control path so that it can be controlled by either the PLC or by the operator (manual). If operator wishes to control the motor speed using the speed control potentiometer, the toggle switch must be set to Manual.

Figure 22. PWM Diagram

Figure 23. PWM Schematic

12. Perform the following substeps to adjust the speed of the Screw Torque module using the PWM amplifi er.

A. Place a valve assembly in the fi xture in the correct orientation.

B. Place the Mode Selector switch in the Auto position.

1 2 378

9

45

6

0

PLC

MANUALPOWER TO

SCREW MOTOR

+

-INCOMING

24V POWER TO PWM

+

-

ANALOGINPUT

OPTIONS

ANALOGOUTPUTOPTIONS

OUTPUT FROM PLC Q5.2SCREW MOTOR ON

TOGGLESWITCH

SPEED CONTROLPOTENTIOMETER

1234

PLC

98765

MANUAL

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-

PLC DISCRETE OUTPUT 5.2SCREW MOTOR ON

ANALOGOUTPUTOPTIONS

INCOMINGPOWER TO

PWM

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER

SCREWMOTOR

ANALOGINPUT

OPTIONS

TOGGLESWITCH


30

C. Place the toggle switch on the PWM in the Manual position.

This allows the setting to be controlled by the rotary switch on the module.

D. Place the rotary speed control knob shown in fi gure 21, in the 0 position.

E. Press the Start pushbutton to begin an automatic cycle.

F. Observe the speed of the screw torque module motor.

This is the motor controlled by the PWM. The motor should not be turning at all.

G. Place the rotary speed control switch in the 1 position.

H. Loosen the knob/screw assembly on the valve assembly and replace it on the fi xture.

I. Press the Start pushbutton to start an automatic cycle.

J. Observe the speed.

You should notice that the motor spins very slowly.

K. Continue to increase the rotary speed control switch setting and run an automatic cycle after each change, loosening the knob/screw assembly after each cycle.

You should notice that the speed of the screw torque module motor increases when the setting is increased on the PWM.

13. Perform the following substeps to home the station and set Auto mode.


This will home all of the actuators.

B. Leave the toggle switch on the PWM Module in the manual position.

C. Turn the Mode Selector switch back to Auto. 14. Perform the following substeps to run the station through an automatic cycle.

A. Place a valve assembly in the fi xture in the proper orientation.

The valve assembly should have a spring, knob, and screw installed.

B. Press the Start pushbutton to start the automatic cycle.

Observe the system while it goes through a cycle before continuing to the next step.

15. Perform the following substeps to power down the station.

A. Close the SIMATIC Manager.

B. Turn off the PC and monitor.

C. Turn the Main Power switch off.

D. Perform a lockout/tagout on the system’s electrical power source.

E. Perform a lockout/tagout on the system’s pneumatic power source.


31

OBJECTIVE 5 DESCRIBE HOW TO ADJUST A NON-SERVO ELECTRIC SLIDE

A non-servo electric slide typically uses hard stops, either adjustable or non-adjustable, and limit switches for positioning, as shown in fi gure 24. The carriage is positioned by the motor turning the gears and driving the synchronous belt to move the carriage along the length of the slide. The carriage stops when it reaches the hard stop at either end of the slide. A limit switch is typically positioned so that it actuates as the carriage reaches a hard stop, sending a signal to the PLC to stop the motor and sequence another step. A clutch can be used on the motor’s output. It is designed to slip if the motor is still turning after the fi xture has driven into a hard stop.

Figure 24. Hard Stops and Limit Switches

If the limit switch is not adjusted properly, it will either send a signal to the PLC before the hard stop is reached, which will cause the slide to be out of posi-tion, or it will not actuate, causing the motor to continue to turn after the slide has reached the hard stop.

MOTOR

LIMIT SWITCH LIMIT SWITCH

CARRIAGE

CLUTCH

NON-ADJUSTABLEHARD STOP

NON-ADJUSTABLEHARD STOP


32

To change the amount of travel of an electric slide, the limit switches must be adjusted. One way to adjust the electric slide travel is to adjust the limit switches. The limit switches are adjusted using the following steps.

Step 1: Turn off power - All power should be removed from the machine and the PLC turned off or placed in STOP mode. Alternatively, the PLC’s output power can be turned off (preventing any machine motion) and the PLC placed into STOP mode.

Step 2: Move the actuator to the desired position - Manually move the actu-ator to the position where the switch should be activated.

Step 3: Loosen the limit switch or actuator arm - The limit switch or adjust-able arm is usually held in place with a screw or bolt. They are sometimes mounted on a rail using screws, as shown in fi gure 25. Loosen the limit switch by either loosening the bolt or screws.

Figure 25. Limit Switch Mounted on a Rail

LOOSENLIMIT SWITCH


33

Step 4: Position the limit switch or actuator arm - The limit switch is posi-tioned by either moving it within the limits of the attachment holes, or by sliding it along a rail. Moving the arm depends on the type of limit switch actuator. Initially, the switch or arm should be positioned so that the limit switch actuator is just starting to move. This positions the switch actuator in its pretravel area. Monitor the PLC’s input status indicator while continuing to slide the switch or actuator arm until a “snap” is heard. The snap indicates the internal contacts have closed. The PLC’s input status indicator should turn on, indicating that the switch contacts have closed. This is the fi nal position of the limit switch.

Figure 26. Positioning the Limit Switch

Step 5: Tighten the limit switch - Tighten the limit switch by tightening the bolts or screws loosened in Step 3.

Step 6: Check the setting using the PLC status indicators - Manually operate the limit switch actuator arm while viewing the limit switch’s status indicator on the PLC input module or while monitoring the terminals with a multimeter. The status indicator should turn on (or turn off, depending on if the switch is wired N.O. or N.C.) just as the actuator reaches the hard stop. If monitoring the limit switch terminals, they should change states. If the switch actuates too early, repeat the procedure until the adjustment is correct. This step requires power to the PLC.

METALTAB

ACTUATORARM


34

SKILL 3 ADJUST A NON-SERVO ELECTRIC SLIDE

Procedure Overview

In this procedure, you will adjust the limit switches that are used to indicate fi xture position to the PLC. This will familiarize you with adjusting the limit switches on a non-servo electric slide.








Tie up long hair






4. Connect an air supply line to the station’s air manifold quick connect. 5. Plug the station’s power cable into a wall outlet. 6. Perform the following substeps to power up the station.






35















B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart. 10. Make sure that the Output Power to the PLC is turned off. You can verify this by checking the Output Power indicator lamp to see that

it is off.


36

11. Perform the following substeps to adjust the limit switches on the non-servo electric slide.

The slide has non-adjustable hard stops, shown in fi gure 28. The only way to adjust the positioning of the fi xture at either end of slide travel is to adjust the limit switches. They send a signal to the PLC to turn off the motor after either the BOT or EOT position has been reached.

Figure 28. Limit Switches and Hard Stops

A. Place the PLC’s Mode Selector switch in the STOP position.

This will prevent any actuators from being turned on during the adjustment.

B. Locate the two limit switches, shown in fi gure 24, on the non-servo elec-tric slide.

C. Position the slide fi xture against the hard stop at the BOT position.

D. Mark the position of the BOT switch with tape or a marker.

E. Loosen the screws that attach the limit switch bracket to the rail.

F. Move the switch an inch or so toward the middle of the slide.

This will change the limit switch location, which will also change the homing location.

G. Tighten the limit switch attachment screws.

H. Place the PLC’s Mode Selector switch in the RUN position.

CARRIAGE SLIDE

HARDSTOP

LIMITSWITCH

LIMITSWITCH

HARDSTOP


37

12. Perform the following substeps to test the adjustment.

A. Press the Output Power pushbutton to enable the PLC’s outputs.

B. Manually position the fi xture so that it is located in the middle of the slide.

C. Turn the Mode Selector switch to Reset.

This will home all of the actuators. You should notice that the fi xture has not stopped in front of the clamp and Screw Torque module. This is because the limit switch has been adjusted to turn on too early.

As soon as the limit switch actuates, the motor turns off. 13. Turn the Main Power switch to the Off position. 14. Readjust the limit switch so that it will not actuate when the carriage has

reached the hard stop at the BOT position. To do this, move it to the left of the original adjustment.

15. Turn the Main Power switch to the On position. 16. Press the Output Power pushbutton to enable the PLC’s outputs. 17. Perform the following substeps to home the station.


This will home all of the actuators. You should notice that the fi xture hits the hard stop, but the motor does not turn off. The clutch should slip to prevent the motor from burning out.

18. Turn the Main Power switch to the Off position. 19. Readjust the limit switch to the original position. 20. Turn the Main Power switch to the On position. 21. Press the Output Power pushbutton to enable the PLC’s outputs. 22. Perform the following substeps to home the station.

A. Use the slide’s manual overrides to position the carriage in the middle of the slide.

B. Turn the Mode Selector switch to Reset.

This will home all of the actuators. You should notice that the fi xture hits the hard stop and actuates the limit switch. The motor should turn off.

23. Perform the following substeps to run the station through an automatic cycle. A successful automatic cycle will let you know that the limit switch and

the non-servo electric slide’s travel at the BOT position has been adjusted properly.

A. Place a valve assembly in the fi xture in the correct orientation.

The valve assembly should have a spring, knob, and screw installed.




38








39


1. The major advantage of a DC motor is that its speed can be easily ________.

2. At 50% level a PWM will use about 50% of ______.

3. A pulse width modulator (PWM) amplifi er is a device that may be used as an effi cient ____ motor speed controller.

4. A PWM circuit can produce more _______ in a motor because the pulses reach full supply voltage.

5. PWM’s work by switching the power supplied to the motor _______ rapidly.

6. A non-servo electric slide typically uses hard stops and ______________ for positioning.

7. The ________ stops when it reaches the non-adjustable hard stop at either end of the slide.

8. A limit switch is typically positioned so that it _________ as the slide reaches the hard stop, sending a signal to the PLC to stop the motor and sequence another step.


40

SEGMENT 3TORQUE ADJUSTMENT

OBJECTIVE 6 DESCRIBE HOW TO ADJUST MOTOR TORQUE USING A CLUTCH

A clutch is a mechanical device that uses mechanical, magnetic, hydraulic, pneumatic or friction connections to engage or disengage two rotating members. A common example is the friction clutch located between an automobile engine and manual transmission. The motor rotates and applies its rotational energy to the clutch, which supplies rotational energy to the drive shaft. In automation applica-tions, the clutch is usually placed between a motor and a driven member and is designed to slip at a preset torque level to protect the motor from burning out if excessive loads are encountered. One application is a screw torque module, as shown in fi gure 29.

Figure 29. Clutch Application

The screw torque module uses an electric motor to tighten the fastener after the tooling has been inserted into the fastener. The motor and tooling turn the fastener until the preset clutch torque level has been reached. When the torque level has been reached, the clutch slips, stopping the movement of the tooling on the end of the screw torque module.

ADJUSTABLEKNOBTOOLING

(DRIVEN MEMBER)

CLUTCH STOPS TURNINGONCE PRESET TOQUE

LEVEL IS REACHED

DC MOTOR

FASTENER

MOTORTURNS


41

The torque level at which the clutch slips is controlled by compressing the springs with the adjusting nut. Turning the nut counterclockwise causes less force to be applied to the springs, reducing the amount of torque required for the clutch to slip. Turning the nut clockwise causes more force to be applied to the springs, increasing the amount of torque required for the clutch to slip.

Figure 30. Adjusting Torque

LESS FORCEAPPLIED TO THE

SPRINGS

TURN ADJUSTMENTKNOB CCW

MORE FORCEAPPLIED TO THE

SPRINGS

TURN ADJUSTMENTKNOB CW

INCREASE TORQUE

DECREASE TORQUE


42

SKILL 4 ADJUST MOTOR TORQUE USING A CLUTCH

Procedure Overview

In this procedure, you will adjust the clutch on the screw torque module to apply different amounts of torque to the valve assembly screw. This will familiarize you with adjusting the torque level of a clutch.








Tie up long hair






4. Connect an air supply line to the station’s air manifold quick connect. 5. Plug the station’s power cable into a wall outlet.


43

6. Perform the following substeps to power up the station.



















B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart. 10. Make sure that the Output Power to the PLC is turned off.


44

11. Perform the following substeps to set up the force table to test the clutch assembly in the next step.

A. Go online with the processor and monitor the project.

B. Select Display Force Values from the PLC menu.

An Empty Force Values table should open.

C. Select the Address column of the table.

D. Enter Q5.2 into the address column.

E. Press Enter.

The address should be entered into the address column and BOOL entered into the Display Format Column. The cursor should move to the next row’s address column.

F. Select row 1’s Force Value column by clicking on it.

Do not enter anything in this box at this time. You will force the value in the next step.

12. Perform the following substeps to reduce the torque setting on the screw torque module’s clutch.

A. Locate the screw torque module clutch assembly shown in fi gure 32.

Figure 32. Clutch Assembly and Motor

B. Turn the knurled adjustment knob, shown in fi gure 32, counterclockwise (looking at the rear of the clutch assembly) fi ve turns. You should be able to see that the tension on the springs is being reduced as you turn the knob. This is visible by the increase in the gap between the adjustment nut and the rest of the clutch components.

CLUTCH

ADJUSTMENTKNOB


45

C. Manually place a pre-assembled valve assembly in the fi xture and place the screw head against the Phillips head bit.

You will hold the valve body in place while the motor is turning.

D. Push the Output Power button to enable the PLC’s outputs.

E. Go back to the PC and, while someone is holding the valve assembly in place, enter true in the Force Value column for output Q5.2 and press Enter.

F. Right-click in row 1’s Force Value column to display the shortcut menu.

G. Select Force from the shortcut menu.

H. Click Yes on the dialog to force the input on.

This should force the screw motor on. It will stay on until you change the force value in the table. A red F should also appear in row 1’s Identifi ca-tion column to indicate that a force is active.

The torque setting should be very low. The screw motor should turn and slip at this low torque level.

I. Once the screw motor turns and slips turn the force off by changing the true value in row 1’s Force Value column to false.

J. Press Enter.

K. Right click in row 1’s Force Value column to display the shortcut menu.

L. Select Force from the shortcut menu.

The Force dialog should appear.

M. Click Yes on the dialog to force the input off.

A red F should appear in the row’s Identifi cation column to indicate that the force is active.

N. Remove the valve assembly and test the tightness of the screw using a Phillips head screw driver.

You should be able to easily turn the screw in the assembly.


46

13. Perform the following substeps to increase the torque setting on the screw torque module’s clutch.

A. Turn the knurled adjustment knob clockwise (looking at the rear of the clutch assembly) two turns. You should be able to see that the tension on the springs is being increased as you turn the knob.

B. Manually place a pre-assembled valve in the fi xture and place it against the Phillips head bit.

You will hold it in place while the motor is turning.

C. Force output Q5.2 on as in Step 12.

The torque setting should be higher than in the last step. The screw motor should turn and slip at a higher torque level.

D. Force output Q5.2 off as in Step 12.

E. Remove the valve assembly and test the tightness of the screw using a Phillips head screw driver.

You should still be able to turn the screw, but it may not be as easy as it was with the last setting.

14. Perform the following substeps to increase the torque setting on the screw torque module’s clutch.

A. Turn the knurled adjustment knob counterclockwise (looking at the rear of the clutch assembly) three more turns. This should place it close to the original setting.

B. Manually place a pre-assembled valve in the fi xture and place it against the Phillips head bit.

You will hold it in place while the motor is turning.

C. Force output Q5.2 on as in Step 12.

The torque setting should be lower than in the last step. The screw motor should turn and slip at a higher torque level.

D. Force output Q5.2 off as in Step 12.

E. Remove the valve assembly and test the tightness of the screw using a Phillips head screw driver.

You may or may not be able to turn the screw as it should be rather tight. 15. Perform the following substeps to delete the force on output Q5.2.

A. Make sure the variable table is displayed on the monitor.

B. Right-click in row 1’s Force Value column to display the shortcut menu again.

C. Select Delete Force from the shortcut menu.

The Delete Force dialog should appear.

D. Click YES on the dialog to delete the force.

The force should be removed. The red F should disappear from row 1’s Identifi cation column.


47

16. Perform the following substeps to close the Force Values table.

A. Close the Force Values table by clicking the X in the top right hand corner of the variable table window.

A dialog should appear asking if you wish to save the variable table.

B. Click No on the dialog to close the variable table without saving it. 17. Click the Monitor button on the LAD/STL/FBD Editor’s toolbar to go

offl ine. 18. Perform the following substeps to run the station through an automatic cycle.

A. Place pre-assembled valve in the fi xture.

The valve body should have a spring, knob, and screw installed.



C. Remove the valve assembly from the station. 19. Perform the following substeps to power down the station.







48

OBJECTIVE 7 DESCRIBE HOW TO ADJUST MOTOR STARTER OVERLOADS

An overload protection device is used to sense when a motor is being loaded beyond its safe operating limits. The overload device should be sized to disconnect the motor from its power source before the motor is damaged. Overload relays are also included in magnetic motor starters as an additional protective device.

Figure 33. Overload Protection Device

When the motor starter’s overload device reaches its trip point, the overload relay’s set of N.C. contact open. The overload relay contacts are wired into the control circuit in a manner that will de-energize the starter coil. When the starter coil is de-energized, the motor starter line contacts open, which disconnects the motor from the power source.


49

Figure 34 shows the operation of a thermal overload circuit with a motor starter. In this example, during normal operations, the current passes through the normally closed contact in the overload to the motor starter coil. The N.O. contact in the overload blocks a signal to the PLC.

Figure 34. Thermal Overload Operation

+

-

L3

L1 L2 L3

T1 T2 T3

98 9795 96

OL

L1 L2

MOTOR STARTER SIGNAL FROM PLC

POSITIVE TO COIL

NEGATIVE TO MOTOR

N.C. CONTACT

N.O. CONTACT(BLOCKED

SIGNAL)

OVERLOAD SIGNAL TO PLC

NEGATIVE TO COIL

POSITIVE TO MOTOR REARVIEW OFSLIDE MOTOR

MOTORSTARTER

+

+ -

4.7 SLIDE REV.

1.7 OVERCURRENT

A1 A2


50

If the motor current exceeds the trip setting, the normally closed contact in the overload will open (trip) and power will not be passed on to the motor starter as shown in fi gure 35. In this instance, the normally open contact in the motor starter will close, sending a signal back to the PLC that the overload has tripped. Once the heat from the excessive current has dissipated, the overload can be reset (manually) and will operate normally.

Figure 35. Thermal Overload Operation

+

-

L3

L1 L2 L3

T1 T2 T3

98 9795 96

OL

L1 L2

MOTOR STARTER SIGNAL FROM PLC

POSITIVE TO COIL

NEGATIVE TO MOTOR

N.C. CONTACT(BLOCKED)

N.O. CONTACT(BLOCKED

SIGNAL)

OVERLOAD SIGNAL TO PLC

NEGATIVE TO COIL

POSITIVE TO MOTOR REARVIEW OFSLIDE MOTOR

MOTORSTARTER

+

+ -

4.7 SLIDE REV.

1.7 OVERCURRENT

A1 A2


51

Some overload devices are adjustable. An adjustable overload typically has a small dial that can be turned with a small screwdriver to change the trip point setting.

Figure 36. Reset Button and Trip Current Adjustment Dial

TRIPCURRENT

SET TO1.6A

ADJUSTMENTDIAL

RESET


52

SKILL 5 ADJUST MOTOR STARTER OVERLOADS

Procedure Overview

In this procedure, you will adjust the thermal overload on the motor starters for the non-servo electrice slide. This will familiarize you with adjusting the overload on a motor starter.








Tie up long hair






4. Connect an air supply line to the station’s air manifold quick connect. 5. Plug the station’s power cable into a wall outlet.


53

6. Perform the following substeps to power up the station.












The project Torquing Station is provided on a supplemental disk.







B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart. 10. Press the Output Power pushbutton to enable the PLC’s outputs.


54

11. Perform the following substeps to adjust the thermal overload setting.

A. Locate the overload relay next to motor starter M2, shown in fi gure 38.

This relay is used for both motor starters.

Figure 38. Motor Starter Overload Location

B. Record the overload setting in the space provided.

Setting ____________________________________________________

C. Using a small screwdriver, set the trip point (setting) to the lowest value.

THERMALOVERLOAD

RELAY

OVERLOAD SETTING

OVERLOADRESET

BUTTON


55

12. Perform the following substeps to adjust the clutch so that it does not slip when the fi xture is driven into the BOT stop.

Figure 39. Motor Clutch Adjustment Knob

A. Turn the knurled adjustment knob clockwise (looking at the rear of the clutch assembly) four or fi ve turns. You should be able to see that the tension on the springs is being increased as you turn the knob.

B. Press and hold motor starter M2’s manual override.

The torque setting should be high enough that the motor does not slip when the fi xture hits the stops.

If the clutch still slips, repeat substep A to increase the torque setting.

If the clutch does not slip, continue to hold the motor starter manual over-ride until the thermal overloads trip.

You should hear it trip and I1.7 should turn on.

C. Verify that PLC input I1.7 is on. This is the thermal overload input.

Because this is a fault, if you tried to operate the system using the program, it would not run.

D. Press the Reset button on the thermal overload, shown in fi gure 38.

MOTOR CLUTCHADJUSTMENT

KNOB


56

13. Readjust the thermal overload trip point to the original setting. 14. Readjust the clutch by turning the knurled adjustment knob counterclockwise

the same number of times you turned it clockwise. 15. Perform the following substeps to home the station.

A. Manually position the fi xture in the middle of the slide.

B. Turn the Mode Selector switch to Reset.

This will home all of the actuators. You should notice that the fi xture hits the hard stop and actuates the limit switch. The motor should turn off.

16. Perform the following substeps to run the station through an automatic cycle.

A. Place pre-assembled valve in the fi xture.

The valve body should have a spring, knob, and screw installed.










57


1. A clutch is a mechanical device that uses mechanical, magnetic, hydraulic, pneumatic or friction connections to engage or disengage two _________ members.

2. A screw torque module uses a slip clutch between the _______ and the driven member.

3. The torque level at which the clutch slips is controlled by ____________ the springs with the adjusting nut.

4. An __________ protection device is used to sense when a motor is being loaded beyond its safe operating limits.

5. When the overload in a manual motor starter trips the overload relay’s set of ________ open, disconnecting the motor from its power source.

6. An adjustable overload typically has a small _____ that can be turned with a small screwdriver to change the trip point setting.


58

SEGMENT 4MODULE SEQUENCING

OBJECTIVE 8 DESCRIBE A SEQUENCE OF OPERATION OF A NON-SERVO ELECTRIC SLIDE

A typical non-servo electric slide, shown in fi gure 40, includes a carriage mounted on a belt-driven electric slide that transports parts from one end of the slide to the other. It is driven by a motor with a reversible motor starter, which includes a thermal overload to protect the motor if the clutch is misadjusted or faulty. In this example, the slide includes two limit switches to indicate the end-of-travel positions.

Figure 40. Non-Servo Electric Slide Construction

MOTOR

LIMIT SWITCH LIMIT SWITCHCLUTCH

CARRIAGE

ELECTRICSLIDE

REVERSEMOTOR

STARTER

THERMALOVERLOAD

FORWARDMOTOR STARTER


59

An electric slide is generally controlled by a PLC, but could also be controlled by robotic I/O. In either case, the sequence will be similar to that shown in the following table.

NON-SERVO ELECTRIC SLIDE SEQUENCE

STEP INPUT OUTPUT

1 PLC Receives Slide Start Input (S1 on)

Slide Extends (M2 on)

2 Slide Extended (LS2 on) Cycle Stops


Retract Slide (M3 on)

4 Slide Retracted (LS1 on) Cycle Ends

Figure 41. Non-Servo Electric Slide Sequence


60

Initial Conditions

The electric slide must be in some pre-determined state before any sequence may take place. Many times this will be a state in which the carriage is in the BOT position (LS1 actuated). If this condition is not present, the non-servo electric slide will not operate and the PLC controlling the slide may even provide an alarm light or message to the operator, indicating that operator intervention is necessary.

Figure 42. Initial Condition

MOTOROFF

BOT LIMITSWITCH LS1 ON

24 VDC

GND

M2

M2

SLIDE MOTOR

M3

M3

OL

CLUTCHFORWARD

REVERSE

CARRIAGE

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH


61

Step 1: PLC Receives Slide Start Input, Slide Extends

In this step, the PLC controlling the slide receives an input to start the sequence. The input may be from another workstation, an operator, or another station. After receiving the input signal, the PLC energizes motor starter M2. This causes the motor to turn in the forward direction, towards the EOT position.

Figure 43. Step 1: PLC Reaches Slide Start Input, Slide Extends

MOTORON

BOT LIMITSWITCH LS1 ON

24 VDC

GND

M2

M2

SLIDEMOTOR

M3

M3

OL

CARRIAGE

FORWARD

REVERSE

SLIDE BEGINSTO EXTEND

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH


62

Step 2: Slide Extended, Cycle Stops

When the carriage has reached the EOT position, limit switch LS2 actuates to indicate to the PLC that the EOT position has been reached. The limit switch signal causes the PLC to turn off the signal to the motor starter, stopping the motor. After the slide has extended to the EOT position, it stops until it receives another input signal. This is to allow time for the part to be removed and also prevents the slide from moving when the part is being removed.

Figure 44. Step 2: Slide Extended, Cycle Stops

MOTOROFF

EOT LIMIT SWITCH

LS2 ON

24 VDC

GND

M2

M2

SLIDEMOTOR

M3

M3

OL

CARRIAGE

LIMITSWITCH

LS1

REV

LIMITSWITCH

LS2

FWD

FORWARD

REVERSE

LS1OFF

CLUTCH


63

Step 3: Receive Input Signal, Retract Slide

After the input signal is received, the PLC outputs a signal to energize motor starter M3. This causes the motor to turn in the reverse direction, causing the fi xture to move away from the EOT position and back toward the BOT position.

Figure 45. Step 3: Receive Input Signal, Retract Slide

MOTORON

SLIDE BEGINSTO RETRACT

24 VDC

GND

M2

M2

SCREW MOTOR

M3

M3

OL

CLUTCH

CARRIAGE

FORWARD

REVERSE

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH


64

Step 4: Slide Retracted, Cycle Ends

After the carriage has reached the stop at the BOT position, limit switch LS1 is actuated, indicating to the PLC that the fi xture has reached the BOT position. This causes the PLC to remove the output to motor starter M3, de-energizing the motor starter and turning off the motor. This is the home position for the non-servo electric slide.

Figure 46. Step 4: Slide Retracted, Cycle Ends

MOTOROFF

LS2OFF

24 VDC

GND

M2

M2

SLIDEMOTOR

M3

M3

OL

CLUTCH

CARRIAGE

FORWARD

REVERSE

CARRIAGEHOMED

LS1ON

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH


65

This sequence just described is summarized by sequence diagram in fi gure 47.


Step Input Action Output Action

INPUTS OUTPUTS

Sta

rt P

B

Sto

p P

B

LS1

LS2

The

rmal

O.L

.

Act

ive

Lam

p

M2

Slid

e F

WD

M3

Slid

e R

EV

0 Start Condition 0 1 1 0 0 0 0 0

1 Receive Start Input Slide Extends 1/0 1 1

2 Slide Extended Cycle Stops 0 1 0 0

3 Receive Start Input Retract Slide 1/0 1 1

4 Slide Retracted Cycle Ends 1 0 0 0

End Condition 0 1 1 0 0 0 0 0

Figure 47. Sequence Diagram


66

SKILL 6 DESIGN A PLC PROGRAM THAT SEQUENCES A NON-SERVO ELECTRIC SLIDE

Procedure Overview

In this procedure, you will design and test a PLC program that controls the non-servo electric slide on the 87-MS6 Torquing Station.

1. Design a ladder logic routine given the following information. The general sequence, I/O diagram, and power diagram are as follows: General Sequence

1) Pressing the Start pushbutton (PB1) causes the fi xture to move toward the EOT position.

2) Once the slide has fully extended, actuating LS2, it stops.

3) Pressing the Start pushbutton again causes the slide to retract towards the BOT position.

4) When the slide has fully retracted, actuating LS1, the process will stop. Special Conditions

• The Start pushbutton should be off, indicating that the station is ready, when the slide is in its home position (at the BOT position with LS1 actuated).• Program logic should start the non-servo electric slide sequence from its home position.


67

Figure 48. I/O Diagram

Figure 49. Power Diagram

I/O DIAGRAM

I0.0

Q4.6I0.1

START INPUT

I1.4

LS1

SLIDE FWD

SLIDE BOT

STOP

I1.5

LS2

SLIDE EOT

INPUTS OUTPUTS

PB2

PB1

M2

Q4.7 SLIDE REV M3

I1.7

THERMALOVERLOAD

Q4.0ACTIVE LAMP

REVERSE

M1

M1

M2

M2

FORWARD

CARRIAGE

CLUTCH

24 VDC

GND

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH

OL


68



INPUTS OUTPUTS

Sta

rt P

B (

I0.0

)

Sto

p P

B (

I0.1

)

LS1

(I1.

4)

LS2

(I1.

5)

The

rmal

O.L

(I1

.7).

Act

ive

Lam

p (Q

4.0)

M2

(Q4.

6) S

lide

FW

D

M3

(Q4.

7) S

lide

RE

V

0 Start Condition 0 1 1 0 0 0 0 0

1 Receive Start Input Slide Extends 1/0 1 1




End Condition 0 1 1 0 0 0 0 0





C. Start the SIMATIC Manager. 3. Perform the following substeps to create a project.

A. Create a Project named L8S6XXX where XXX represents your initials.

B. Create an S7 Station object for the station and confi gure its hardware.

C. Open Organizational Block OB1.

D. Enter the program that you developed in Step 1 into Organizational Block OB1.

E. Save OB1. 4. If the 87-MS6 Torquing station is connected to another station, separate the

stations. If the 87-MS6 Torquing station is already disconnected, continue to Step 5.


69






Tie up long hair






6. Connect an air supply line to the station’s air manifold quick connect. 7. Plug the station’s power cable into a power outlet. 8. Perform the following substeps to power up the 87-MS6 Torquing station.

A. Remove the lockout/tagout device from the electrical power source.

B. Remove the lockout/tagout device from the pneumatic power source.

C. Turn on the air to the station by shifting the lever on the lockout value.

D. Set the station’s air supply regulator to 50 psi/ 345 kPa.

E. Turn the station’s Main Power Switch to the On position. 9. Perform the following substeps to download the project to the PLC.

A. Place the Mode Selector Switch in the RUN position.

B. Reset the PLC.


Several dialogs will appear during the download.

Click the appropriate response to continue downloading the program. The last dialog should ask if you wish to perform a complete (Warm) restart.

D. Click Yes on the dialog to complete a warm restart. 10. Go online with the processor and monitor the OB1 Block. 11. Press the Output Power pushbutton to enable the PLC’s outputs.


70

12. Perform the following substeps to test the PLC program. At this time, the Start pushbutton lamp should be off.

A. Press the Start pushbutton momentarily.• The slide’s fi xture should move away from the BOT position and move toward the EOT position.• After the fi xture reaches the EOT position, LS2 should actuate, causing the motor to stop. The fi xture should remain in the EOT position.

B. Press the Start pushbutton again.• The reverse motor starter should turn on, and the fi xture should begin to move toward the BOT position. • After the fi xture reaches the BOT position, LS1 should actuate, causing the motor starter to de-energize, stopping the motor.

C. Press the Start pushbutton again.

The cycle should repeat. 13. Print out a copy of the ladder logic program and place it in your portfolio. It

will be used in your assessment. 14. Perform the following substeps to shut down the 87-MS6 Torquing station.




D. Turn the 87-MS6’s main power switch to Off.




71

OBJECTIVE 9 DESCRIBE A SEQUENCE OF OPERATION OF SCREW TORQUE MODULE

An example of a typical screw torque module is shown in fi gure 52. This unit includes a screw motor, which is a DC motor controlled by a motor starter. It also has a clamp module, that contains a pneumatic slide and a gripper. The slide and gripper are controlled by two single-acting solenoids.

In this example, when the PLC receives a signal that a part is in place, SOL1 is energized and extends the clamp and the part toward the screwdriver bit in the screw torque tool. When magnetic reed switch MR2 is on, indicating the clamp is extended, SOL2 is then energized to close the clamp on the part to hold it stationary during the torquing operation. Once the clamp is closed, inductive sensor IND1 is turned on indicating the clamp is closed on the part. The screw motor is then turned on and held on for three seconds to allow the operation to complete. After the three seconds is up, the screw motor turns off and SOL2 is de-energized so the clamp opens. Once the clamp opens, SOL1 is turned off, the clamp retracts, and the cycle is complete.

Figure 52. Screw Torque Module Construction

CLAMP

SINGLE-ACTINGSOLENOID

(SOL1)

CLAMP EXTENDCYLINDER

(PNEUMATIC SLIDE)

ADJUSTABLECLUTCH

SCREWDRIVER

BITSCREWTORQUE

TOOLSCREWMOTOR

PROXIMITYSENSOR

(IND1)

CLAMPCYLINDER

PART

SINGLE-ACTINGSOLENOID

(SOL2)

PWM AMPLIFIER

MR1 MR2


72

The sequence of a screw clamp module is similar to the one shown in the table.

SCREW TORQUE MODULE SEQUENCE

STEP INPUT OUTPUT

1 PLC Receives Start Input (S1 on) Clamp Extends (SOL1 on)

2 Clamp Extended (MR2 on) Close Clamp (SOL2 on)

3 Clamp Closed (IND1 on) Turn on Screw Motor for Three Sec-onds (Dwell Timer Starts)

4 Screw Motor on for Three Seconds (Timer Done)

Release Close Clamp

5 Clamp Closed Deactivated Retract Clamp

6 Clamp Retracted (MR1 on) Cycle Ends

Figure 53. Screw Torque Module Sequence


73

Initial ConditionsThe screw torque module must be in some pre-determined state before any

sequence may take place. Many times this will be a state in which the clamp is retracted and opened, and the motor starter is not energized. If these conditions are not present, the screw torque module will not operate and the PLC controlling the module may even provide an alarm light or message to the operator, indicating that operator intervention is necessary.

Figure 54. Initial Condition

MR1 ON CLAMPRETRACTED

PART

SCREW MOTOROFF

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-

PLC DISCRETE OUTPUT 5.2SCREW MOTORON

ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


74

Step 1: PLC Receives Start Input, Clamp Extends

In this step, the PLC controlling the slide receives an input to start the sequence. The input may be from another workstation, an operator, or another station. After receiving the input signal, the PLC energizes SOL1. This causes the clamp cylinder to extend, turning MR1 off.

Figure 55. Step 1: PLC Receives Start Input, Clamp Extends

CLAMPBEGINS

TO EXTEND

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


75

Step 2: Clamp Extended, Close Clamp

After the clamp has extended, magnetic reed switch MR2 energizes, indicating to the PLC that the clamp has extended. This causes the PLC to energize SOL2, which causes the clamp to close. The clamp has an inductive sensor (IND1) that energizes when a part is gripped.

Figure 56. Step 2: Clamp Extended, Close Clamp

MR2 ON

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

MR1 OFFCLAMP

EXTENDED

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER

CLAMPBEGINS TO CLOSE


76

Step 3: Clamp Closed, Turn on Screw Motor for Three Seconds

After inductive sensor IND1 has energized, indicating that the clamp has closed, the screw motor is turned on for three seconds. This allows enough time for the tooling to tighten the fastener.

Figure 57. Step 3: Clamp Closed, Turn on Screw Motor for Three Seconds

IND1 ON

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

CLAMPCLOSED

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


77

Step 4: Screw Motor on for Three Seconds, Release Close Clamp

The screw motor is stopped after the three second timer has expired. After the screw motor has stopped, the PLC removes the signal from SOL2. This causes the clamp to open and IND1 to turn off.

Figure 58. Step 4: Screw Motor on for Three Seconds, Release Close Clamp

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

BIT TURNS TOTORQUE SCREW

SCREWMOTOR ON

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER

CLAMPBEGINS TO OPEN


78

Step 5: Clamp Close Deactivated, Retract Clamp

After the clamp has opened, the PLC removes the signal from SOL1. The causes the clamp to retract. The signal from magnetic reed switch MR2 will de-energize as the clamp begins to retract. The signal from magnetic reed switch MR1 will energize when the clamp has fully retracted.

Figure 59. Step 5: Clamp Closed Deactivated, Retract Clamp

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER

CLAMPBEGINS TO RETRACT

CLAMP OPEN


79

Step 6: Clamp Retracted, Cycle Ends

After MR1 has energized, the cycle is complete and the actuators are in the homed position.

Figure 60. Step 6: Clamp Retracted, Cycle Complete

MR1 ON CLAMPRETRACTED

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

MR2 OFF

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


80

This sequence just described is summarized by sequence diagram in fi gure 61.



INPUTS OUTPUTS

Sta

rt P

B

Sto

p P

B

MR

1 C

lam

p R

etra

cted

MR

2 C

lam

p E

xten

ded

IND

1 C

lam

p C

lose

d

Act

ive

Lam

p

SO

L1 C

lam

p E

xten

ded

M1

Scr

ew M

otor

On

SO

L2 C

lam

p C

lose

T1

Inte

rnal

Tim

er B

it

0 Start Condition 0 1 1 0 0 0 0 0 0

1 Receive Start Input Clamp Extends 1/0 1 1

2 Clamp Extended Close Clamp 0 1 1

3 Clamp Closed Turn on Screw Motor for 3 Seconds 1 1

4 Screw Motor on for Three Seconds Release Close Clamp 0 0 1

5 Clamp Closed Deactivated Retract Clamp 0 0 0

6 Clamp Retracted Cycle Ends 1 0 0

End Condition 0 1 1 0 0 0 0 0 0 0



81

SKILL 7 DESIGN A PLC PROGRAM THAT SEQUENCES A SCREW TORQUE MODULE

Procedure Overview

In this procedure, you will design and test a PLC program that controls the screw torque module on the 87-MS6 Torquing Station.


1) Pressing the Start pushbutton (PB1) causes the clamp to extend towards the valve body.

2) After the clamp has fully extended, it closes around the knob body.

3) After the clamp has closed, the screw motor is turned on for three seconds.

4) After the screw motor has turned off, the clamp is released.

5) After the clamp has released, the clamp is retracted.

6) After the clamp has retracted, the process is complete. Special Conditions

• Pressing the Stop pushbutton at any time will cause the screw torque module to stop (or halt) at the end of its current step. Pressing the Start pushbutton will resume the sequence.• The Start pushbutton should be off, indicating that the station is ready, when the screw torque module is in its home position (clamp retracted).• Program logic should start the screw torque module sequence from its home position.• If the clamp closed signal turns on and then off as the clamp closes, a part is not present and the clamp should be reset.


82



I/O DIAGRAM

I0.0

Q4.5

I0.1

START INPUT

I1.2

MR1

CLAMP EXTENDSOL 1

CLAMPRETRACTED

STOP

I1.3

MR2CLAMP

EXTENDED

INPUTS OUTPUTS

PB2

PB1

Q5.2

SCREW MOTOR ON

M1

Q5.3

CLAMP CLOSESOL 2

I1.6

IND1CLAMP

CLOSED

Q4.0ACTIVE LAMP

SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


83



INPUTS OUTPUTS

Sta

rt P

B (

I0.0

)

Sto

p P

B (

I0.1

)

MR

1 (I

1.2)

Cla

mp

Ret

ract

ed

MR

2 (I

1.3)

Cla

mp

Ext

ende

d

IND

1 (I

1.6)

Cla

mp

Clo

sed

Act

ive

Lam

p (Q

4.0)

SO

L1 (

Q4.

5) C

lam

p E

xten

ded

M1

(Q5.

2) S

crew

Mot

or O

n

SO

L2 (

Q5.

3) C

lam

p C

lose

T1

Inte

rnal

Tim

er B

it

0 Start Condition 0 1 1 0 0 0 0 0 0



3 Clamp Closed Turn on Screw Motor for 3 Seconds 1 1

4 Screw Motor on for Three Seconds Release Close Clamp 0 0 1


6 Clamp Retracted Cycle Ends 1 0 0

End Condition 0 1 1 0 0 0 0 0 0 0










E. Save OB1. 4. If the 87-MS6 Torquing station is connected to other stations, separate the



84






Tie up long hair










D. Set the station’s air supply regulator to 50 psi/345 kPa.



B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart. 10. Go online with the processor and monitor the OB1 Block.


85

11. Place an assembled valve into the fi xture. The valve should be oriented as shown in fi gure 66.

Figure 66. Valve Body Orientation

12. Press the Output Power pushbutton to enable the PLC’s outputs. 13. Perform the following substeps to test the PLC program. At this time, the Start pushbutton lamp should be off.

A. Press the Start pushbutton momentarily.

The clamp should extend toward the valve body.

After the clamp has fully extended, it should close around the valve body.

After the clamp has closed, the screw motor should turn on for three seconds, applying torque to the screw. As the screw motor is applying torque, the clutch on the screw motor should slip.

After the screw motor has turned off, the clamp is released, releasing the valve body.

After the clamp has released, it should begin to retract.

After the clamp has retracted, the process is complete.

B. Manually remove the valve body from the fi xture. 14. Print out a copy of the ladder logic program and place it in your portfolio. It

will be used in your assessment. 15. Perform the following substeps to shut down the 87-MS6 Torquing station.







VAVLEASSEMBLY

FIXTURE


86


1. The non-servo electric slide is generally controlled by a ____ but could also be controlled by robotic I/O.

2. The electric slide must be in some ____________ state before any sequence may take place.

3. A typical non-servo electric slide is driven by a motor with a reversible motor starter that includes a _______ to protect the motor.

4. A Screw Torque module can contain a clamp ________ that contains a pneumatic slide and a gripper.

5. The slide and gripper are controlled by two ___________ solenoids, SOL1 and SOL2.

6. Magnetic reed switches MR1 and MR2 are used to __________ if the clamp is retracted (MR1) or extended (MR2).


87

SEGMENT 5STATION SEQUENCING

OBJECTIVE 10 DESCRIBE A SEQUENCE OF OPERATION OF AN AUTOMATED TORQUING STATION

An automated torquing system is used to apply consistent torque to fasteners on an automated assembly line. A typical automated torquing system includes an electrically driven spindle, a clamping mechanism, and a material handling device such as a powered slide.

An example of an automated torquing system is shown in fi gure 67. This system is designed to tighten a screw and knob assembly in a part. The clamping module holds the knob stationary while the automated tooling turns the screw for a predetermined amount of time, threading it further into the knob. Once the timer is done, the clamping module releases the knob and retracts. A powered slide then shuttles the part to the end of travel location, where the part is removed from the carriage.

Figure 67. Torquing Station Construction

CLAMPINGMODULE

PART

CARRIAGE

CLUTCH

ELECTRICMOTOR

AUTOMATEDTOOLING

POWEREDSLIDE

BOT LIMITSWITCH

(LS1) EOT LIMITSWITCH

(LS2)

SLIDEMOTOR

M3 M2

IND1

MR3

MR2

SOL1 SOL2


88

The Torquing station will typically have a sequence similar to that shown in the table below.

STEP INPUT OUTPUT


Extend Clamp (SOL1 on)

2 Clamp Extended (MR2 on) Close Clamp (SOL2 on)

3 Clamp Closed (IND1 on) Turn on Screw Motor for 3 Seconds (Dwell Timer Starts)

4 Screw Motor on for Three Seconds (Timer Done)

Release Close Clamp

5 Clamp Closed Deactivated Retract Clamp

6 Clamp Retracted (MR1 on) Slide Extends (M2 on)

7 Slide Extended (LS2 on) Cycle Stops


Retract Slide (M3 on)

9 Slide Retracted (LS1 on) Cycle Ends

Figure 68. Torquing Station Sequence


89

SKILL 8 DESIGN A PLC PROGRAM THAT SEQUENCES AN AUTOMATED TORQUING STATION

Procedure Overview

In this procedure, you will design and test a PLC program to control the 87-MS6 Torquing Station.



2) After the clamp has fully extended, it closes around the knob.




6) After the clamp has retracted, the slide moves toward the EOT position.

7) Once the slide has fully extended, actuating LS2, it stops to allow a part to be manually removed.

8) Pressing the start pushbutton again causes, the slide to retract towards the BOT position.

9) When the slide has fully retracted, actuating LS1, the process is complete. Special Conditions

• Pressing the Stop pushbutton at any time will cause the screw torque module to stop (or halt) at the end of its current step. Pressing the Start pushbutton will resume the sequence.• The Start pushbutton should be off, indicating that the station is ready, when the screw torque module is in its home position (clamp retracted).• Program logic should start the screw torque module sequence from its home position.


90


I/O DIAGRAM

I0.1

I1.4

STOP

SLIDE BOT

I1.5

I1.2

I1.3

INPUTS

SLIDE EOT

CLAMP RETRACTED

CLAMPEXTENDED

I0.0

START INPUT

PB2

PB1

LS1

LS2

MR1

MR2

I1.6

CLAMP CLOSED

IND1

Q4.6

Q4.7

Q4.5

Q5.3

Q5.2

OUTPUTS

SLIDE FWDM2

SLIDE REVM3

CLAMPEXTEND

CLAMPCLOSE

SCREW MOTOR ON

SOL1

SOL2

I1.7

OL

M2

M3

M1

THERMALOVERLOAD

Q4.0ACTIVE LAMP

SOL1


91


SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

24 VDC

GND

M2

M2

SLIDE MOTOR

M3

M3

OL

CLUTCH

FORWARD

REVERSE

CARRIAGE

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


92

AUTOMATED TORQUING STATION SEQUENCE


INPUTS OUTPUTS

Sta

rt P

B (

I0.0

)

Sto

p P

B (

I0.1

)

MR

1 (I

1.2)

Cla

mp

Ret

ract

ed

MR

2 (I

1.3)

Cla

mp

Ext

ende

d

IND

1 (I

1.6)

Cla

mp

Clo

sed

Slid

e B

OT

(I1

.4)

Slid

e E

OT

(I1

.5)

The

rmal

O.L

. (I1

.7)

Act

ive

Lam

p (Q

4.0)

M2

(Q4.

6) S

lide

FW

D C

ont.

M3

(Q4.

7) S

lide

RE

V C

ont.

SO

L1 (

Q4.

5) C

lam

p E

xten

ded

M1

(Q5.

2) S

crew

Mot

or O

n

SO

L2 (

Q5.

3) C

lam

p C

lose

T1

Inte

rnal

Tim

er B

it

0 Start Condition 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0



3 Clamp Closed Turn on Screw Motor for 3 Seconds

1 1

4 Screw Motor on for Three Seconds

Release Close Clamp 0 0 1


6 Clamp Retracted Slide Extends 1 0 1 0




End Condition 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0










E. Save OB1. 4. If the 87-MS6 Torquing station is connected to other stations, separate the



93






Tie up long hair










D. Set the station’s air supply regulator to 50 psi/ 345 kPa.



B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart.


94

10. Go online with the processor and monitor the OB1 Block. 11. Place an assembled valve body into the fi xture. The valve body should be oriented as shown in fi gure 73.


VAVLEASSEMBLY

FIXTURE


95

12. Press the Output Power pushbutton to enable the PLC’s outputs. 13. Perform the following substeps to test the PLC program. At this time, the Start pushbutton lamp should be off.

A. Press the Start pushbutton momentarily.• The clamp should extend toward the valve body.• After the clamp has fully extended, it should close around the knob.• After the clamp has closed, the screw motor should turn on for three seconds, applying torque to the screw. As the screw motor is applying torque, the clutch on the screw motor should slip.• After the screw motor has turned off, the clamp is released, releasing the valve body.• After the clamp has released, it should retract.• The slide’s fi xture should move away from the BOT position and move toward the EOT position.• After the fi xture reaches the EOT position, LS2 should actuate, causing the motor to stop.

B. Press the Start pushbutton momentarily.• The reverse motor starter should turn on, and the fi xture should begin to move toward the BOT position. • After the fi xture reaches the BOT position, LS1 should actuate, causing the motor starter to de-energize, stopping the motor.

C. Press the Start pushbutton again.

The cycle should repeat.

D. Manually remove the valve body from the fi xture.

E. Press the Start pushbutton momentarily.

The clamp should extend. The clamp should close, attempting to clamp the valve body. After the clamp has detected that a part is not present (input I2.0 turns on as the clamp is closing, and then turns off), the clamp should retract.

14. Print out a copy of the ladder logic program and place it in your portfolio. It will be used in your assessment.









96

OBJECTIVE 11 DESCRIBE THE OPERATION OF A AUTOMATED TORQUING STATION WITH MANUAL/ AUTO/ RESET FUNCTIONS

Torquing stations, like most other machines and stations, are usually programmed to provide two or three different operating modes depending upon the needs of the application. The three most common modes are automatic (or Auto), manual, and reset.

Automatic

Selecting the automatic mode causes the PLC program to enable the machine’s automatic operation. After the machine is homed and the automatic mode is selected, pressing a start pushbutton causes the station to perform its sequence auto-matically. Depending upon the machine and process being controlled, the station may perform the sequence once (single-cycle) or continuously (continuous-cycle).

Manual

Selecting the manual mode causes the PLC program to enable the machine’s manual functions. Placing a machine in manual mode enables the user to move the machine’s actuators independently on an “as needed” basis, or to “step” through the machine’s sequence.

Reset

Selecting Reset causes the PLC to reset the machine’s actuators and program logic to some initial or starting condition (i.e. home position). This is usually a preparatory step before placing the machine into Automatic Mode. This is usually done in program logic by enabling a function or function block containing the reset operations while disabling functions and/or function blocks supporting the machine’s other operating modes.

To reset a torquing station, as with other types of stations, the PLC is normally designed to return all actuators to their start positions when the mode selector switch is placed in the Reset position. For a non-servo electric slide, the slide should be fully retracted to the beginning of travel (BOT) position. For a torque clamp module, the clamp should be fully retracted and opened.


97

Figure 74. Station Actuators in Reset Position

The most basic way to program a reset function is to turn all output devices on or off at the same time to return all actuators to their start positions. In some cases, certain actuators may interfere with each other, so some reset functions must be programmed to perform a reset sequence of returning the actuators to their start positions in a certain order. For a Torquing station, one such sequence might be to retract the non-servo electric slide fi rst, and then retract and open the clamp on the clamp torque module.

CLAMPSRETRACTEDAND OPEN

SLIDECARRIAGE

HOMED


98

SKILL 9 DESIGN A PLC PROGRAM THAT PROVIDES MANUAL/ AUTO/RESET FUNCTIONS FOR AN AUTOMATED TORQUING STATION

Procedure Overview

In this procedure, you will modify PLC program L8S8XXX to add the manual, auto, and reset functions.

1. Modify project L8S8XXX to provide the manual, auto, and reset functions to the program.

The general sequence, I/O diagram, and power diagram are as follows: General Sequence (Auto Mode)


2) After the clamp has fully extended, it closes around the knob body.




6) After the clamp has retracted, the slide moves toward the EOT position.

7) Once the slide has fully extended, actuating LS2, it stops to allow a part to be removed.

8) Pressing the start pushbutton again causes the slide to retract towards the BOT position.

9) When the slide has fully retracted, actuating LS1, the process is complete. Special Conditions (Auto Mode)

• Pressing the Stop pushbutton at any time will cause the torquing station to stop (or halt) at the end of its current step. Pressing the Start pushbutton will resume the sequence.• The start button should turn off, indicating that the station is ready, when the slide and screw torque module are both in the home positions.• Program logic should start the screw torque module sequence from its home position.• Assembled valve bodies need to be manually installed into the carriage’s fi xture at the start of a sequence and removed from the fi xture at the end of the sequence (during the three second delay while the slide is at the EOT position).


99

(Manual Mode)• Pressing the Start pushbutton while the selector switch is in the Manual posi-tion causes the pick and place station to step through its sequence, one step at a time.

(Reset)• Turning the selector switch to the Reset position causes the pick and place station to reset its actuators in the following sequence.• Clamp Opens• Clamp Retracts• Slide Returns to BOT position


I/O DIAGRAM

I0.0

Q4.5

I0.1

START INPUT

I1.2

MR1

CLAMP EXTEND

CLAMPRETRACTED

STOP

I1.3

MR2CLAMP

EXTENDED

INPUTS OUTPUTS

PB2

PB1

Q4.6

SLIDE FWDM2

M2

I1.6

IND1CLAMP

CLOSED

I1.0

RESETPB1

I1.1

AUTO

I1.4

LS1

SLIDE BOT

I1.5

LS2

SLIDE EOT

SOL 1

Q4.7

SLIDE REVM3

M3

Q5.2

SCREW MOTOR ONM1

M1

Q5.3CLAMP CLOSE

SOL 2

I1.7

OLTHERMAL

OVERLOAD

ACTIVE LAMPQ4.0


100


SOL1

FROMSOURCE

SOL2

MR1 MR2

CLAMP EXTEND

CLAMP CLOSE

IND1

24 VDC

GND

M2

M2

SLIDE MOTOR

M3

M3

OL

CLUTCH

FORWARD

REVERSE

CARRIAGE

LIMITSWITCH

REV FWD

LS1 LS2

LIMITSWITCH

9

8

7

6

5

PWM AMPLIFIER

1

2

3

4

24 VDC

0 VDC

+

-


ANALOGOPTIONS

INCOMINGPOWER TO

PLC

PWM CONTROL

PLCMANUAL +5V

SPEEDCONTROL

+5V DC/DCCONVERTER


101

AUTOMATED TORQUING STATION SEQUENCE


INPUTS OUTPUTS

Sta

rt P

B (

I0.0

)

Sto

p P

B (

I0.1

)

MR

1 (I

1.2)

Cla

mp

Ret

ract

ed

MR

2 (I

1.3)

Cla

mp

Ext

ende

d

IND

1 (I

1.6)

Cla

mp

Clo

sed

Slid

e B

OT

(I1

.4)

Slid

e E

OT

(I1

.5)

The

rmal

O.L

. (I1

.7)

Act

ive

Lam

p (Q

4.0)

M2

(Q4.

6) S

lide

FW

D C

ont.

M3

(Q4.

7) S

lide

RE

V C

ont.

SO

L1 (

Q4.

5) C

lam

p E

xten

ded

M1

(Q5.

2) S

crew

Mot

or O

n

SO

L2 (

Q5.

3) C

lam

p C

lose

T1

Inte

rnal

Tim

er B

it

0 Start Condition 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0



3 Clamp Closed Turn on Screw Motor for 3 Seconds

1 1

4 Screw Motor on for Three Seconds

Release Close Clamp 0 0 1


6 Clamp Retracted Slide Extends 1 0 1 0




End Condition 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0






A. Open Project L8S8XXX that was developed in a previous skill.

B. Save the project as L8S9XXX where XXX represents your initials.

C. Enter the program that you developed in Step 1 into Organizational Block OB1.

D. Save the project. 4. If the 87-MS6 Torquing station is connected to another station, separate the



102






Tie up long hair










D. Set the station’s air supply regulator to 50 psi/345 kPa.



B. Reset the PLC.




D. Click Yes on the dialog to complete a warm restart.


103

10. Go online with the processor and monitor the OB1 Block. 11. Place an assembled valve body into the fi xture. The valve body should be oriented as shown in fi gure 79.


12. Press the Output Power pushbutton to enable the PLC’s outputs.

VAVLEASSEMBLY

FIXTURE


104

13. Perform the following substeps to test the auto portion of the PLC program. At this time, the Start pushbutton lamp should be off.

A. Turn the Mode Selector switch to the Reset position to return the Torquing station to its home position.

The Torquing station should begin homing in the following order:• Clamp Opens• Clamp Retracts• Slide Returns to BOT position

After the station is homed, the Start pushbutton light should turn off indi-cating that the station is in its homed position.

B. Turn the Mode Selector switch to the Auto position.

C. Press the Start pushbutton momentarily.• The clamp should extend toward the valve body.• After the clamp has fully extended, it should close around the knob.• After the clamp has closed, the screw motor should turn on for three seconds, applying torque to the screw. As the screw motor is applying torque, the clutch on the screw motor should slip.• After the screw motor has turned off, the clamp is released, releasing the valve body.• After the clamp has released, it should retract.• The slide’s fi xture should move away from the BOT position and move toward the EOT position.• After the fi xture reaches the EOT position, LS2 should actuate, causing the motor to stop and the fi xture to stop in this position.

D. Press the Start pushbutton momentarily.• The reverse motor starter should turn on, and the fi xture should begin to move toward the BOT position. • After the fi xture reaches the BOT position, LS1 should actuate, causing the motor starter to de-energize, stopping the motor.

E. Press the Start pushbutton again.

The cycle should repeat.

F. Manually remove the valve body from the fi xture.

G. Press the Start pushbutton momentarily.

The clamp should extend. The clamp should close, attempting to clamp the valve body. After the clamp has detected that a part is not present (input I2.0 turns on as the clamp is closing, and then turns off), the clamp should retract.


105

14. Perform the following substeps to test the operation of the PLC program in Manual mode.

A. Turn the Mode Selector switch to the Manual position.

B. Press and release the Start pushbutton.

The clamp should extend.

C. Press and release the Start pushbutton.

The clamp should close and grasp the knob of the assembly in the fi xture.

D. Press and release the Start pushbutton.

The Screw Torque module motor should turn on for three seconds.

E. Press and release the Start pushbutton.

The clamp should open.

F. Press and release the Start pushbutton.

The clamp should retract.

G. Press and release the Start pushbutton.

The fi xture should move until it reaches the EOT position, actuating LS2. The PLC should turn the motor off.

H. Press and release the Start pushbutton.

This causes the slide motor to turn on in the reverse direction. The slide should move back to the BOT position, where it actuates limit switch LS1. This signal causes the PLC to turn off the motor.

15. Print out a copy of the ladder logic program and place it in your portfolio. It will be used in your assessment.









106


1. An automated torquing system is used to apply ________ amounts of torque to fasteners on an automated assembly line.

2. Automated torquing systems typically include an electrically driven _________, a clamping device, and a material handling device.

3. Automatic mode causes the PLC program to enable the_____ automatic operation.

4. Placing a machine in manual mode enables the user to move machine’s actuators to _____ through the sequence.

5. Reset causes the PLC to reset the machine’s actuators and program logic to some _____ condition.

TORQUING - 1.cdn.edl.io · PDF fileFigure 2. Applying Torque to a Bolt Automated torquing...

Documents

Transcript of TORQUING - 1.cdn.edl.io · PDF fileFigure 2. Applying Torque to a Bolt Automated torquing...