Cnc t 100

CNC TRAIN MASTER LATHE

MODEL : CNC T – 100 (S)

SUBMITTED TO :- SUBMITTED BY :-

Prof. R.K. Mathur Rajeev Kumar Mandal

Prof. O.P. Arora (H.O.D.) Kumar Gaurav

DEPARTMENT OF MECHANICAL ENGINEERING FINAL YEAR (ME)

BHAGWANT UNIVERSITY,AJMER

RAJASTHAN

CAUTION

1. Proper earth connection for CNC system and machine.

User should be ensure proper earth connection to the

equipements.

2. Safety against input supply variation.

The machine operates successfully with an input voltage of three

Phase, 415 Volts +/- 10%, 50 Hz +/- 3% in case of variation in input

supply voltage beyond the range, user is advised to use a suitable

voltage stabilizing device like voltage stabilizer/ isolation

transformer etc.

INDEX

1. INTRODUCTION PAGE NO.

1.1 Develoment in metal cutting machine tools. 4

1.2 An insight to CNC machine. 4

1.3 CNC programming concept. 5

1.4 Need for training in CNC. 6

1.5 Advantages of CNC machines. 6

1.6 Objectives of CNC machine training. 6

1.7 Training method. 7

1.8 Knowledge level of trainee. 7

2. SPECIFICATION AND FEATURES

2.1 Machine specifications. 8

2.2 CNC system features. 9

3. MECHANICAL MACHINES DETAILS

3.1 Bed. 10

3.2 Saddle and cross slide. 10

3.3 Head stock. 10

3.4 Tail stock. 10

3.5 Tool turret. 10

3.6 AC servo motor and drives. 10

4. OPERATING OF THE CNC SYSTEM

4.1 Putting machine in to operation. 11

4.2 Feed ON control ON. 11

4.3 Manual Movements. 11

4.4 Reference Point approach. 12

5. PART PROGRAMMING

5.1 Coordinate system of CNC lathe. 13

5.2 Programming methods. 14

5.3 Preparatory function (G codes). 17

6. TOOL SETTING

6.1 Work piece reference point setting. 18

6.2 Tool used. 18

7. PRACTICAL EXERCISES

7.1 Description of standard cycles. 25

8. Material needed for exercises. Annexture-1

9. Selection of working parameters for cutting in a lathe. Annexture-2

10. Electrical circuit diagrams. 28

1. INTRODUCTION:-

1.1 Development in metal cutting machine tools

The general purpose machine tools like lathe, milling, boring and grinding machine

etc, were being operated manually until 1950 components needed in large numbers

were catered by automats and special purpose machines. There were no machines

available for catering special purpose machines. There were no machine available for

catering to the need of batch production, where the higher productivity of special

purpose machines is combined with the ease for job change over as in general

purpose machine. If the general purpose machines could be operated automatically,

and at higher speed, without the operator actually turning the hand wheels it would

improve the productivity of these machines.

Such an automated machines is numerically controlled machine. Numerical control

was developed in 1952 in USA and is commercially available since 1960s.In the last

two decades rapid development and miniaturization in the field of electronics has

made it possible to build controllers which can effectively control basic machine and

also their peripheral devices reliably.

Production of CNC machine is increasing proportion of CNC machines among the

total metal cutting machine tools also growing rapidly.

1.2 An insight to CNC machines

In manufacturer of part on machine tools, the work piece shape and dimension are

achieved either by moving the tool against a rotating work piece or by moving the

work piece against a rotating tool. The movement of tool/work piece is commanded

manually through the help of hand operated controls through associated kinematics

arrangements. This procedure is to be repeated to every piece produced. The

dimension obtained by the operator setting have to be verified by measurements

and suitable correction made. To produce component of high accuracy the operator

must have high skill.

For complicated components the production cycle time be very large as each

dimension must be measured and controlled. Components having special profiles

which requires two or more slides to be moved simultaneously cannot be without

special profile generation system. These factors are responsible for low production

rates one conventional machines.

In a CNC machine, the slide (axes) movement are controlled by AC servo motors. The

main objective is to be able to reach a particular point accurately at the required

speed. The spindle speed is selectable according to needs of a particular job.

The selection and usage of the right tool for each of the machining operation as to

be repetitively done each work piece by the machine operator on conventional

machine. On NC machine, presenting the correct tool to the work piece is automatic

by automatic indexing (as commanded) of multi-tool turret or automatic tool

changer.

For achieving higher production rates, multiple activities of the machine such as

speed changes, motions of various slides, presentation of the right tool should be

made concurrent activities to the maximum extent. This would call for an ability for

coordination and execution of multiple activities which is beyond the human

capability. Electronics system use in the numerical control system can do this task

with the required speed and precision with the development of the computer and

microprocessors, the logic control functions are achieved through computers. Such

systems are called CNC systems.

1.3 CNC Programming Concepts

CNC machines are controlled by CNC systems through the intermediate drive

elements like motors, hydraulic actuators etc. in order to execute any particular task.

CNC system required are technological like cutting speeds, feeds, dept of cut, type of

tool and geometrical data like size and shope of the work piece to be cut.

The information input to such CNC system is to be in standard format such as

EIA-RS-274B for positioning and contouring control.

The programming format contains the letter code for each word with a special out

number of digits for each numerical information. The letter codes includes the

program the number, preparatory command, direction and distance to be moved

for each axis, co-ordinates of the center of segments of circles for profile contouring,

the feed rate , the tool number, spindle speed and other miscellaneous functions.

The general program format is :

Wkord sequence :

N…G…X…Y..Z..S..T..D…M..

N01G02X4Z8F42M2T6S4

The details of the format used for the machine is explained in the chapter.

5- part programming.

Also refer programming manual of siemens 802s CNC system supplied with machine.

1.4 Need for training in CNC

As explained in sections 2 and 3 CNC machines are fairly complex with many special

functions added to those found on conventional machines to achieve better

productivity through automation . these machines require instruction from the

machine operator in a different medium then the conventional machines. To

facilitate learning of operating CNC machines , it is essential to impart proper

training and operating the machine with the prepared part program.

For preparing the part program, the geometrical information from the part drawing

has to be converted to the program format. To get familiarization in program

preparation, confidence in its correctness and operation of the CNC machine

through th program ‘hand on training ‘ is required.

A full fledged CNC machine suitable for such a machine is very high making it

consequently machine hour rates of such a machine is very high making it

uneconomical for usage for training purpose. Any error by the learner in

programming or operation of the machine will be expensive to correct as these could

damage the machines apart from loss of production time. Trainer machines are built

in such a way that there will be no damage to the machine even during the

execution of faulty program. Thus the familiarly with CNC machining obtained by

training machines will develop the confidence of the learner to a level where he can

take up operation for machines.

1.5 ̀ Advantages of CNC machines:

1. High productivity for small/medium batch quantity manufacture.

2. Requires no special tool setting.

3. High repeatability and accuracy of work pieces.

4. Reduction in rejections

5. Can do complicated jobs not normally possible on conventional machines

6. Reduction in operator fatigue

7. Reduction in skill required for machining operations

8. Ease of product change over

9. Reduction in lead- time for staring production

1.6 Objectives of CNC machine training

1. To understand the operation of CNC control

2. To operate CNC machines based on the theoretical instructions obtained

3. Imparting the ability to write program for different parts, which are difficult to

cut in conventional machines

4. To edit and execute these programs for different parts, which are difficult to cut

in conventional machines

5. To reduce the difficulty for change over to production CNC machines

6. To understand the requirements of other features and peripherals needed for

optimum machining.

1.4 Training method

Following sequential steps are generally to be followed to train person in

CNC machine operation:

1. Understanding specifications, features and functions of the machine

2. Familiarisation with the machine features and control for operation of the

machine

3. Operating the machine through the CNC system

4. Familiarization with part programming methods

5. Took setting and tool selection

6. Practical exercises

1.8 Knowledge level of Trainee

The trainee should have the ability to read simple drawings, do simple arithmetical

calculations. He must be able to select the cutting parameters such as speed, feed

etc. for the machining operations.

The trainee should also be familiar with the use of a PC.

2. SPECIFICATIONS & FEATURES OF CNC T- 100 (S) LATHE

CNC T-100 Train Master Lathe is designed for training of operators, methods

engineers in CNC turning technology, turning operations involving plain turning taper

turning , threading cutting , radius turning can be performed on this lathe.

2.1 Machine Specifications

1. Height of centres. mm 100

2. Distance between centres. mm 310

3. Swing over bed. mm 150

4. Swing over cross slide mm 75

5. Traverse of cross slide mm 75

6. Max. turning Diameter mm 45

7. Max. turning length mm 150

8. Longitudinal traverse mm 180

HEAD STOCK

9. Hole through work spindle mm 16

10. Spindle taper MT

11. Type of drive AC variable

12. Speed range (step less) RPM 50 – 3200

13. Power Kw 0.75

TAIL STOCK

14. ̀ Spindle diameter mm 22

15. Spindle taper MT 1

16. Sleeve stroke mm 35

FEED RATE

17. Type of drive for both axis AC Servo motor

18. Rapid traverse rate mm/min 700

19. Programmable feed rate mm/min 0-0.700

CNC System

20. No. of axis 2

21. Type Siemens 80 2C

22. Weight of the machine (approx.) Kg. 250

23. Tool (Turret model, Pragati make) BTP 40

24. Tools stations Nos. 8

25. Turret indexing position - 8

26. Turning tool shank size mm 12*12

2.2 CNC system Features

Table top model suitable for machining of non ferrous material,

however light cut of 0.2 mm on diameter without coolant can be

taken on mild steel.

Step less AC drive.

Antifriction preloaded high precision spindle bearing.

Precision slide motion through for recirculating ball screw/ nut

arrangement for longitudinal and cross direction.

Number of axes 2.

Incremental and continuous JOG.

Reference point approach.

MDI/SINGLE BLOCK/AUTOMATIC execution.

Axis homing.

Feed hold.

Feed rate over ride 0 to 120%.

Standard G&M codes as per ISO.

Linear and circular interpolation.

Dwell time.

Rapid feed rate 700mm/min.

Thread cutting.

Turning and threading cycles.

Inch/metric mode of input.

Feed programmable in per minutes and per revolution.

Zero off sets.

Tool nose radius compensation.

Full screen editor.

Cursor motions to selected block delete.

Program handling function like dir.del.copy.remane.

Block move, copy and delete.

Graphic simulation.

Block skip.

MPG.

A/C Panel

3. Mechanical Machine Details

The mechanical machine has the following:

1. Bed

2. Saddle and cross slide

3. Head stock

4. Tail stock

5. Tool turret

6. Axes drive system.

7. Spindle drive system.

3.1 BED

Bed is built with projected high quality cast iron and has V and flat

guideways & without side keeper plate. The head stock is mounted

on the left hand side of the bed. The bed is fixed on the base plate.

3.2 SADDLE AND CROSS SLIDE

The saddle is fitted over the bed guide ways using two keeper plates

lined with Turcite. The saddle is moved over the bed using the Z-axis

ball screw nut mechanism. The feed movement is obtained by a Stepper

motor and ball screw. It also houses the ball screw connected to the X

axis stepper motor through a timing belt. The cross slide carries the

tool turret on which the external turning tools and boring tools are mounted.

3.3 HEAD STOCK

The head stock contains the spindle of the machine. The spindle has a

MT2 taper and a adopter flange can be fixed for mounting three or four

jaw chucks.

3.3 TAIL STOCK

The tail stock can be fixed at any point along the bed guide ways using

a keeper plate. The tail stock has a sleeve with MT1 taper and can be

moved in or out using the small hand wheel. This can also be used for

mounting drills and centering bits.

3.5 TOOL TURRET

The auto tool turret having 4 internal and 4 external tools is mounted in

the cross sleeve. The turret is in directional drives in 24V DC motor.

3.6 MOTOR DRIVE

Stepper motor and drive are used in both the axes of siemens make.

Spindle drives with AC servo motor.

4. OPERATION OF THE SYSTEM

In the following pages the main operations are described. The operator is

advised to study earlier chapters regarding the location of the control and

description of the control and be familiar with all controls to prepare for

this section.

To prepare part programme vis manual input mode observe guidelines of

the programming and operating instructions of the CNC system manual

supplied along with this manual.

Refer to appropriate operating manual of the CNC system supplied with the

machine for the specific operation of the system control.

4.1 PUTTING MACHINE INTO OPERATION:

- Keep the emergency push button athe conrrol post pressed This

- latches on its own and will remain closed.

- Switch on the man incoming single phase supply.

- Turn the mains switch at the control post to ON position(1S1).

- Mains ON indication light on control post will be ON.

- The emergency push button is now released and machine is ready for operation.

4.2 Feed ON/Control ON

Preconditions:

- Emergency push button EPM is not pressed. - Light LTO is ON.

START:

- Press control ON push on machine control panel.

- Relay CRI will be ON.

- Message “NOT READY ON CNC SCREEN WILL GO AND AXES

DRIVE WILL BE ENABLES.”

4.3 Manual movement:

a. Job mode

Preconditions:

- Jog mode is selected on CRT

- Control/Feed ON

- Axes drives are healthy.

Note :- TOOL TURRET CAN BE INDEXED BY ONE POSITION BY PRESSING

TURRET INDEX KEY.

Start:

A)

- Select feed rate by feed over-ride switch.

- To move the X-axis slide towards inward,press - X key and

towards operator side,press + X key.

- Rapid jog movement is effective by pressing two keys

simultaneously i.e. rapid movement key alongwith respective jog

movement key.

- To move Z axis slide towards left side, press –Z key and to move

- Towards right side,press +Z key.

B) Incremental mode :

Preconditions `

- Select increment jog mode.

- Select incremental mode on CRT as per requirement i.e. inc 1 or

Inc 10 or inc 100.

- Slide will move 0.001,0.01 and 0.100 mm respectively by selecting

inc1, inc10 and 100.

- Inc 1000 and inc 10000 are not effective.

C) Manual pulse generators MPG

- Select MPG on CRT.

- Manual pulse generator is provided for X and Z axis Slides

depending upon selection and correction factor. Individual

respective slide will move by the selected inc 1 or 10 per pulse

desired direction.

4.4 Reference point approach :

- Control/Feed ON

- Drive for axes are enable i.e. CR1+

- Home mode selected on CRT, X and Z soft keys starts blinking.

- Feed over-ride switch not at zero position.

X-Axis - Select X axis by pressing +X key. - Slide X moves to reference position.

Z-Axis - Select Z axis by pressing +Z key. - Slide Z mode to reference position, now X and Z axes are reference.

TOOL TURRET REFERENCE Press TURRET REFERENCE Key Turret moves to reference position.

PART PROGRAMMING

As explained in chapter 1.3 the part program provides the instructions to the CNC

control the execute the machine operations.The coordinate system of the machine

has been explained is in the chapter.The programming methods program structure

and explanation of each operating codes have also been provided.

5.1 Coordinate system of CNC lathe

The information “move the longitudinal slide in the head stock

direction” is a very long one. besides, in each language, it would be

different that’s why the traverse path movements in machine tools are

described within the coordinate system.

Coordinate system on a NC lathe is shown below.

Z-axis - Axis parallel to the turning axis

X- axis - Axis perpendicular to the turning axis

-Z movement - Movement of the longitudinal slide towards the

direction of the head stock.

+Z movement - Movement of the longitudinal slide away from

the head stock.

-X movement - Movement of the cross slide towards the spindle

axis.

+X movement - Movement of the cross slide away from the spindle

axis.

5.2 Programming methods

There are two method to describe the path of motion in a CNC

machine:

1.Absolute programming method.

2.Incremental programming method.

In absolute programming method,the next point on the work piece is

Taken as a reference or zero point and all the other dimensions are

represented with respect to that point.

In incremental programming method,the next point dimension in each

block is referred with respect to the final point on the previous block.

The system of dimensioning in each method is shown in the

Illustrations.

ABSOLUTE SYSTEM OF DIMENSIONING

INCREMENTAL SYSTEM OF DIMENSIONING

Programming method comparison

Absolute system Incremental system

The path information given to the turning The zero reference point for

Tools is always calculated from a definite each path information is the

Starting point. Current position of the tool

Itself.

Path X Z Path X Z

A -3 0 A -3 0

B -3 -2.5 B 0 2.5

C -2 -2.5 C 1 0

D -2 -4 D 0 -1.5

E 0 -0 E 2 -2

Only point 0 is the reference Point 0,1,2,3,4 are all new

reference point.

Absolute system Incremental system

If you have to change the position of a If you have to change position

Point all other points still remain of one point,all the Following

Unchanged. Ones will have to be changed

As well.

Point 1 has to be changed to point 1 since point 1 was changed, the The

description for point 2 and 3 description for point 2&3 also Changes.

remains unchanged.

Path X Z Path X Z

A -1 -1 A -1 1

B -1 -2.5 B 0 1.5

C 0 -2.5 C 1 0

D -1.5 -0.5 D -1.5 -0.5

E 0 -2.5 E 1 0

Effective until cancelled by G00,G01

5.3 PREPARATORY FUNCTION (G FUNCTION)

G code Table :

G CODE FUNCTION

G00 Positioning (Rapid traverse)

G01 Linear interpolation (Feed)

G02 Circular interpolation CW

G03 Circular interpolation CCW

G04 Dwell time

G9 Non-model exact stop

G17 (Required for center drilling)

G18 Z/X Plane selection

G22 Radius input

G23 Diameter input

G25 Lower spindle speed limit

G26 Upper spindle speed limit

G40 Tool radius compensation off

G41 Tool radius compensation left of cotour

G42 Tool radius compensation right of cotour

G53 Non-model suppression of settable of zero offset

G54 1st settable zero offset

G55 2nd settable zero offset

G56 3rd settable zero offset

G57 4th settable zero offset

G60 Exact positioning

G64 Contineous path mode

G70 Dimensions in inches

G71 Dimensions in metric values

G74 Reference point approach

G75 Fixed point approach

G90 Absolute dimensions

G91 Incremental dimensions

G94 Feed rate F in mm/min.

G95 Feed rate F in mm/rev of spindle

G96 Constant cutting speed for turning on (F in mm/rev,S in m/min)

G97 Constant cutting speed of turning off

G158 Programmable offset

G450 Transition circle

G451 Point of intersection

G500 Settable zero offset off

G601 Exact positioning window fine for G60,G9

G602 Exact positioning window coarse for G60,G9

6. Tool Setting

6.1 Work piece reference point setting

Switch the spindle on set the spindle RPM `

By joggong the X and Z axis bring the tool to the desired position (i.e.

when the tool just scratches the work piece).

Using PRESET mode preset X and Z axis value to zero.

6.2 Tool used on this lathe

Depending upon the operation and configuration of the components

Following tools can be used on the machine.

1. Right hand side tool

2. Left hand side tool

3. Neutral tool

4. External threading tool

5. External grooving tool

6. Parting off tool

7. Internal threading tool

8. Boring tool

The detailed application of the above tools is given in the following

pages.

THE RIGHT HAND SIDE TOOL

Dimensions and applications

Shape turning

Beta(β) Must not be bigger than 50 deg.

Otherwise there will be interference

and rubbing.

Clearance angle C=93 deg. Radius Turning

Longitudinal turning,facing

The depth of cut ‘a’ in the facing should

Not be larger than 0.3 mm.

THE LEFT HAND SIDE TOOL


Shape turning

Γmust be atleast 2 deg. and

β max is equal to 50 deg.

Longitudinal turning facing

The depth of cut ‘a’ within facing should

not exceed 0.3 mm.

THE NEUTRAL TOOL


Longitudinal and angle turning The max. depth of cut ‘a’ when

turning must not be larger than

0.3 mm,with the turning angle

of 70 deg.

Turning of partial radius turning

The angle of the arc must not be

largest than 70 deg.

Max. angle = 70.5 deg.

Clearance angle = 2.5 deg.

EXTERNAL THREADING TOOL

For external threads with pitches from 0.5-1.5 mm index able tips are used.

Plunge Cutting Tool Width of the tips = 1.1 mm Max. depth of cut = 2.1 mm

PARTING – OFF TOOL HSS

INTERNAL THREADING TOOL

Internal threading can be done on jobs with minor thread diameter of 20 mm or

more. Inexorable tips of pitches from 0.5 to 1 mm can be used.

Note : Alternatively, brazed internal threading tools may be used.

INSIDE TURNING TOOL

Inside turning (Boring) can be performed on jobs with internal diameter more

than 16 mm.

Dimensions : Max. clearance angle when turning inwards = 90 deg.

Max. depth of cut (Facing) is 0.3 mm.

7. Practical Exercises

Please refer chapter 9 of programming manual of SIEMENS 802S CNC

System supplied with the machine, containing following standards cycles:

7-1 Drilling, Spot-facing. - LCYC82

7-2 Deep hole drilling - LCYC83

7-3 Tapping with compensation chuck. - LCYC840

7-4 Boring. - LCYC85

7-5 Recess. - LCYC93

7-6 Undercut (Forms E and F to DIN) - LCYC94

7-7 Stock removal with relief cuts. - LCYC95

7-8 Thread cutting. - LCYC97

Annexure – 1

Material needed for training

SL. No.

Description Specification No. off Remarks

1. Raw material A1 rod

IS D734-1975 Dsgn,22588 45*65mm & dia 45*30mm

2

2. Raw material Mild steel

IS 1732-1971 45*65mm

2

3. Chuck 3 Jaw self centering chuck 1

4. Tools Rt. Hand turning tool with inserts 1

Lt. Hand turning tool with inserts 1

Neutral tirning tool with insert 1

Parting off tool 1

External thread cutting tool 1

Internal thread cutting tool 1

Boring tool with inserts 1

5. Standard tools Spanners 7*8,8*10,13*17 Allen key 3,4,5,6

1 set

Annexure – 2

Selection of working parameters for cutting in a lathe

1. Cutting speed (Vs)

Vs (M/min)= ( ) ( ) ⁄

d = Diameter of the work piece

s = Spindle speed (RPM)

Cutting speed to be used in this lathe

For turning : 150 to 200 M/min.

For parting off : 60 to 80 M/min.

2. Calculation of spindle speed

S(Revolution/min)= ( ) ⁄

( )

3. Cutting of feed F

F (mm/min.)= S(Rev/Min.) * F (mm/Rev)

For normally used for turning : 0.02 to 0.1 mm/Rev.

For used for parting off : 0.01 to 0.02 mm/Rev.

10. Electrical circuit diagrams.

Cnc t 100

Engineering

Transcript of Cnc t 100