Introduction to Pneumatics

1
Introduction to Pneumatics
Workshop 4
Stennis Space Center January 7,2006
2
Overview Methods of Power
Transmission Pneumatics Systems Pneumatics
Principles Parts Pneumatic Actuators Force
Principles Solenoid Valves Advantages
3
Methods of Power Transmission

• Electrical Motors
• Mechanical power transmission elements
• Fluid Power
• Hydraulics
• Oil, Water, other liquids
• Pneumatics
• Air, other gases

4
Electric Motors

• Motors convert electrical energy to mechanical

Electric motors used in First kit Chipahua/CIM
Motor Window Motor Van Door Motor Fisher-Price/Ma
buchi Motor Globe Motor
5
Mechanical Power transmission elements
Gears Belts Chains Bearings Couplings
6
Mechanical Power transmission using gears
7
Pneumatics Systems
8
Pneumatics Definitions

• Pneumatics is the general term used to describe
  the mechanics of gases
• Pneumatics, derived from the Greek word
  pneumatikos, meaning coming from the wind
• It is the branch of science which treats the
  mechanical properties of air and other elastic
  fluids used to do work

9
Pneumatic Principles
compressor
solenoid valve
cylinder
hose
reservoir tank
10
Pneumatics

• Compressor
• Accumulators
• Actuators

Source of Air Flow Driven by electric motor
Provides the energy to perform the work
Reservoir tank - Energy Storage Devices
Cylinders convert energy in the compressed air
pressure to linear power. Make things move
Linear Rotary
11
Pneumatics

• Connectors
• tubing
• Pressure
• regulators
• Valves
• 2-way
• 3-way
• 4-way

Plumbing- connectors -flexible tube
Pressure control -controls the force of the
actuator
Control direction of flow
12
Compressor Thomas industries

• 12 volt system
• Generates pressure of 120 psi
• Compact
• Vibration isolators

13
Additional Compressor Components

• Relief Valve
• on Compressor
• Protects compressor

Common
Pressure Switch Signals the controller to start
or stop the compressor
Pressure In
NC
NO
14
Accumulators Pneumatic tank

• Up to two
• Store compressed air at 120 psi
• Helps keep the pressure constant
• Smooth out the pressure fluctuation

15
Cylinders
16
Rotary Actuator
17
Fittings and Plugs
18
Flow Controls

• Regulate flow of air into and out of a cylinder
• Used to control speed of a pneumatic cylinder
• If used, attach directly to cylinder (only one
  end needed)

19
Exhaust Valve

• Use to release pressure

20
FittingsConnection and Disconnection
21
Regulators

• Regulators Control Pressure
• Relieving type in the FIRST kit 2 are included
• The use of Regulators assures maximum efficiency
• Allows air from reservoirs to flow to rest of
  pneumatic system
• Limits pressure in valves, cylinders to 60 psi

22
Solenoid Electric Valves
23
Pneumatic Actuators

• Pneumatic Actuators applies force or creates
  motion through the use of a pneumatic system

24
Pneumatic Actuators

• Use Pressurized Air to achieve motion
• Provide power and speed to any actuation system.
• Variety of Actuation mechanisms available
• Arms
• Grippers
• Shifters

25
Arms
26
Grippers
27
Shifters
28
ActuatorsConstruction Operation
Basic Construction
Operation
29
Compressed Air is routed by the valve to extend
or retract the cylinder
30
Actuators

• Most Common types of Linear Actuators
• Double Acting Single Ended Double Ended
• Single Acting
• Spring Return

• All contain
• Cylinder Barrel
• Piston
• Rod
• Seals
• Spring if used

31
Facts about Pneumatics

• Pressure Units of measure
• Lbs per in2 or Force per unit area
• Absolute Pressure 14.7 psia at sea level
• Gauge Pressure measured relative to ambient
• Flow
• cfm cubic foot (feet) per minute Volume per
  unit time
• Scfm Standard cubic foot (feet) per minute

32
Force Principles

• Gauge Pressure works against each square inch of
  piston surface

• The greater the square inch surface of the
  fluid, the less internal pressure will be
  developed.

33
ActuatorsDifferential Areas

• Force Consideration
• Consider the effective area on which the
  pressure acts
• On single ended cylinders there is a
  differential
• Dont forget friction

34
Cylinders

• Force Pressure ? Area
• 2 diameter piston
• Area 3.14 ? 12 3.14 in2
• Pressure 60 psi
• 3.14 in2 ? 60 psi 188 lbs
• Force while extending greater than while
  retracting
• Main decisions Length and diameter
• Diameter based on required force
• Larger diameter more force, but more air

35
Cylinder maximum force

• ¾ Dia Cylinder
• ½ - 10 Throw 26 lb max force
• 1-1/2 Dia Cylinder
• ½-24 Throw 106 lb max force
• 2 Dia Cylinder
• ½-24 Throw 188 lb max force

36
Cylinder Forces

• Force Applied Pressure Cross Sectional Area
• Pressure applied on a flat plate, causes a force!
  
• The bigger the plate, or the higher the pressure,
  the greater the force.
• Less force in than out.
• This is due to a reduced cross section (caused by
  the rod being in the way!)

37
1.5 Bore Cylinder

• Base Dimension 4.38
• Stroke Length ?
• Locking Nut .25
• Clevis Dimension 1.31

Retracted Length 4.38 Stroke .25 1.31
5.94 Stroke
Extended Length 5.94 (2 x Stroke Length)
38
Single Solenoid Valve

• When energized, cylinder goes to one state
• When de-energized, cylinder always returns to
  rest state
• When power is cut at the end of the match,
  cylinder will return to rest state
• Each valve powered by one relay module (only in
  forward)

39
Double Solenoid Valves

• One solenoid pulsed to move cylinder one way,
  other solenoid pulsed to move cylinder the other
  way
• Results unpredictable if both pulsed
• Valve will stay in either state when neither
  solenoid energized
• Can use one relay for each solenoid or one relay
  and two diodes

40
4-way Valves in your kit

• Double Solenoid (detented)SMC
• Single Solenoid (spring offset)SMC

41
4-way Valves in your kit

• Single Solenoid (spring offset)Festo

42
4-way Valves in your kit

• Single SolenoidPoppet (Spring Offset)

43
4-way 5-port ValvesDirectional Control


Solenoid
Spring
44
Why use Pneumatics in 2006? The Advantages

• Complete kit
• All the parts required to build an operating
  system
• Weightequal or lighter than comparable
  alternatives

• Adjustable Force Different bore cylinders change
  the available force
• and
• By adjusting the applied pressure you can
  instantly adjust the force

45
Why use Pneumatics in 2006? The Advantages

• Custom cylinders in just a few days by UPS
• Last minute additionsadd a valve or a cylinder
  quickly

• Durableno burned up motors stall with no
  damage
• Strongfrom 9 lbs to 180 lbs easily adjustable

46
Why use Pneumatics in 2006? The Advantages

• Custom cylinders in just a few days by UPS
• Last minute additionsadd a valve or a cylinder
  quickly

• Multiple cylinders use same compressor
• Strongfrom 9 lbs to 180 lbs easily adjustable

47
Why do we design with pneumatics?

• Simple Pneumatic Cylinders are force vectors.
• Each cylinder represents a force, which will be
  applied over a certain distance.
• Most pneumatic design involves arms or linkages
  of some type.
• Know principles of leverage and torque!

48
Safety
Safety MUST

• always be
  considered
• Relieve the pressure before working on the system
• Be aware of pinch points
• Avoid side-loading increases friction and wear
• Avoid getting grit or metal shavings on the rod
  or in the cylinder
• Use flow controls for safety

Compressed Air is like a coiled spring
49
Interesting Links
Fluid Power Educational Foundationwww.fpef.org Nason Corporation www.nasonptc.com Bosch Rexroth www. bosch-rexroth.comwww.boschrexroth.com
Bimba Manufacturingwww.bimba.com Lord Corp www.lordmpd.com Fluid Power Dist. Assn www.fpda.org
Clippard Instrument Lab.www.clippard.com Monnier, Inc. www.monnier.com Fluid Power Society www.ifps.org
Wika www.ewika.com/WikaSite/GlobalSites.aspx Norgren www.norgren.com Natl Fluid Power Assn www.nfpa.com
Festowww.festo.com Parker www.parker.com SMC Pneumatics www.smcusa.com
50
Q/A

• Any Questions?
• About this lecture?
• About Pneumatics?
• About Design?
• About FIRST?
• About the Game?