Post on 05-Oct-2015
description
Pneumatics is the branch of mechanics that deals with the mechanical application of gasses. Applications include creating linear actuations through the use of cylinders, creating suction to pick up objects, and even creating rotary motion with certain devices.
What are pneumatics
Mechanisms which use air pressure to apply mechanical force and displacement (work)
The pneumatic devices we use are basically binary actuators either retracted or extended
Retracted Cylinder
Extended Cylinder
What are pneumatics good for?
Mechanisms requiring (2) discrete states
Gear shifters
Gripper articulation
Lifters
Brakes
and a significant force or displacement
Strengths
Simple
Easy to control
Can apply a lot of force from a small, light package
Force is limited by air pressure and cylinder diameter
No adverse consequence if cylinder is stopped (no stalled motors) or reversed compressed air is a spring
In Industry
Pneumatic actuators are extensively used by the Chemical Process Industry due to their intrinsic safety and their ability to fail safe (w/ spring return)
2-position pneumatic
actuator driving a
4-way ball valve
pneumatically driven flow control valves (butterfly type)
C-Rio Computer that controls all devices on robot.
Digital sidecar Provides extra digital and analog inputs and outputs For the C-Rio.
Compressor Provides compressed air for robot Relief valve Relieves pressure over 120 psi for safety.
Manual relief valve Allows for manual relief of pressure when robot is not in use.
Storage tank Up to 4 are used on the robot to store air until it is needed. Depending on their size, less may be used
Pressure sensor Used to tell when the compressor should turn off.
Pressure gauge Gives a visual indication of pressure in the system
Pressure regulator Prevents dangerous pressure levels from being put into the system. Lowers pressure from 120 psi to 60 psi
Brass Fittings Connect Pneumatic tubing to devices such as compressors, tanks, and pistons NOTE: Teflon tape is used to insure a tight connection between threaded fittings. Always leave the first few threads of the fitting free of tape to make it easier to begin tightening the fitting.
Pneumatic piston/ rotary actuator Extends and retracts to move another component of the robot
Solenoid Controls whether a piston is extended or retracted.
How it works
Piston
Cylinder
Seals
NPTF Air Port (Extension)
NPTF Air Port (Retraction)
Rod
Force = Area (in2) x D Pressure (lbf/in2)
Extension Area = Cylinder CS Area Subtract Rod CS Area for Retraction
Typically, pressure is applied to one port while the other is vented to atmosphere - so DP is regulated gauge pressure (60 psi max)
More works We may specify
Cylinder Diameter sets Force @ a pressure
Stroke Length
Mounting Options
Rod Material
Rod Extensions
Spring Return
.
Stroke
Length
Cylinder Specs (Bimba DXP/DX/DP)
Air Pressure (gauge): 60 lbf/in2
Length (in)
Nominal Cyl ID Rod OD Extend Retract Extend Retract Base per inch Base
3/4" 0.750 0.250 0.44 0.39 27 24 0.21 0.03 3.75
7/8" 0.875 0.250 0.60 0.55 36 33 0.32 0.03 3.56
1-1/16" 1.063 0.313 0.89 0.81 53 49 0.33 0.05 3.84
1-1/4" 1.250 0.438 1.23 1.08 74 65 0.71 0.08 4.72
1-1/2" 1.500 0.438 1.77 1.62 106 97 0.73 0.08 4.38
1-3/4" 1.750 0.500 2.41 2.21 144 133 1.64 0.11 5.75
2" 2.000 0.500 3.14 2.95 188 177 1.62 0.15 5.62
2-1/2" 2.500 0.500 4.91 4.71 295 283 2.27 0.17 5.62
3" 3.000 0.625 7.07 6.76 424 406 3.87 0.26 6.50
Dimension (in) Area (in2) Force (lbf) Mass (lbm)
The pneumatic system I (the investment)
Motor
Compressor
Pressure
Switch
Pressure Safety Valve H
igh-P
ress
ure
Air S
tora
ge
Hig
h-P
ress
ure
Air S
tora
ge
Pressure
Gauge
Pressure
Gauge
Pressure Vent Valve
Pressure
Regulator
Hig
h P
ress
ure
Low
Pre
ssure
Users
Controller Spike
The pneumatic system II (the solenoid valve)
Air Supply (Pressure)
Vent B
Vent A
Port A
Port B
A B
V P V
State A
A B
V P V
State B
All ports NPTF
The pneumatic system III (device control)
Spike Controller
Air Pressure
A restrictor valve in Vent B slows extension speed without affecting retraction speed
flexible tubing
State A Extends rod State B Retracts rod
The pneumatic system III (device control)
Spike Controller
Air Pressure
A restrictor valve in Vent B slows extension speed without affecting retraction speed
flexible tubing
State A Extends rod State B Retracts rod
If you are using pairs of cylinders which are activated together, they can be driven by common solenoids
Plumbing Tubing Fittings
Tee - SMC KQT07-00
Male Elbow - SMC KQL07-34S
Male Connector - SMC KQH07-34S
Restrictor Elbow - SMC NAS2201F-N01-07S
Something outside the box
Team 386 (2006) a better vacuum
Team 386 used suction to lift ringers, but was underwhelmed by the vacuum developed by venturi
Team 386 (2006) a better vacuum
Retracting the smaller cylinder
Team 386 used suction to lift ringers, but was underwhelmed by the vacuum developed by venturi
Team 386 (2006) a better vacuum
Retracting the smaller cylinder
Generates a high vacuum on the larger cylinder
Team 386 (2006) a better vacuum
Retracting the smaller cylinder
Generates a high vacuum on the larger cylinder
Separate cylinder sets were used for each suction cup, providing redundancy
Team 386 (2006) a better vacuum
Extending the smaller cylinder
Breaks the vacuum
Separate cylinder sets were used for each suction cup, providing redundancy Extending the small cylinders released the vacuum and dropped the ringer
Pneumatics has applications in just about every industry. From manufacturing, automobile repair, and Dentistry, to robotics, prosthetics, and rollercoasters.