Hydraulik andpmeumatic system
-
Upload
surajkumar-jadhav -
Category
Documents
-
view
226 -
download
0
Transcript of Hydraulik andpmeumatic system
Hydraulic and Pneumatic Systems 1
Hydraulic actuators: cylindersCylinder types:
Single acting: work can be done only in one direction
Piston
Double acting piston:
Piston rod on both sides
Plunger
Work is done in both directions
Telescopic Telescopic Fast moving
Tandem
Fast moving
Hydraulic and Pneumatic Systems 2
Hydraulic cylindersHydraulic cylinder
Hidraulikus munkahengerekRögzítőpálcás kivitel 1.
Hydraulic and Pneumatic Systems 3
Hydraulic cylinders
Hydraulic cylinder Hidraulikus munkahengerekHengeres kivitel 1.
Hengeres építési móddal készült hidraulika henger
Hydraulic and Pneumatic Systems 4
Hydraulic cylinders
Properties:
The cylinders have to be good quality steel with close tolerances.
There have to be good sealing both at the piston rod and at the cylinder.
With time dirt may come in and damage the surfaces. This has to be possibly reduced.
In this case, the leakage will increase all the time.
Hydraulic and Pneumatic Systems 5
Hydraulic cylindersCalculation of cylinders
1maxmaxFFFF FLc FLC FFF
maxmax
22110 pApAFC
1122 pApAFCB
10 A
Qv
2A
QvB
friction forces inertial forcesmaximum loadslow motion, can be often neglected
Backward:
Outward:
Q
A2A1
p1
p2vB
v0
Hydraulic and Pneumatic Systems 6
Hydraulic cylindersCalculation of cylinders
Hydraulic cylinders should be possibly operated in the 3rd region for smooth operation.
If the cylinder is new, the leakage losses are negligibly small so that:
ηc = ηmech
Ff1
v
2 3
1. Stick-slip2. Transition3. Normal behaviour
22112211 ApAp
F
QpQp
Fv LLc
92,085,0max
c
ηc
Δp
outwardsinwards at higher pressures
Hydraulic and Pneumatic Systems 7
Hydraulic cylinders
Checking for buckling
n: safety factor: 1-3,5
lk: buckling length
I1: moment of inertia of the piston rod
E: elasticity modulus of the rod material
1
2
max
1IE
lnF
kL
64
4d
Maximum permissible force:
Hydraulic and Pneumatic Systems 8
Hydraulic cylinders
Cushioning of cylinders:
A hard impact of the piston at the end surfaces has to be inhibited – kinetic energy has to be absorbed.
This is done by increasing the hydraulic resistance at the end of the stroke.
Hydraulic and Pneumatic Systems 9
Rotary hydraulic actuators
Swivel vane rotary actuator:
Limited angle in both directions
Maximum angle always smaller than 360°
The same torque in both directions
Piston rotary actuator:
With rack and gear coupling
Here maximum angle may be larger than 360°Mindkét irányban azonosan működő
hengerrel és fogasléces
meghajtással működtetett
tolódugattyús lengőhajtás
Párhuzamdugattyús
lengőhajtás
Forgódugattyús lengőhajtás
menettel működtetett
meghajtócsappal
Limited angle rotary actuator
Limited angle rotary actuator
Parallel piston rotary
actuator
??? ???
Hydraulic and Pneumatic Systems 10
Big pictures
End of normal presentationBeginning of big pictures
Hydraulic and Pneumatic Systems 11
Hydraulic cylinders
Cylinder types: plunger
smaller force, better efficiency, axial support is necessary but cylinder does not have to be so good quality
Without inner buffer With inner buffer (pilot piston)
Hydraulic and Pneumatic Systems 12
Hydraulic cylinders
Cylinder types: piston, single acting, pressing-cylinder
Spring
inside outside
Hydraulic and Pneumatic Systems 13
Hydraulic cylinders
Cylinder types: piston, single acting, puller
Spring
inside outside
Hydraulic and Pneumatic Systems 14
Hydraulic cylinders
Cylinder types: piston, double acting
Velocity is different
Hydraulic and Pneumatic Systems 15
Hydraulic cylinders
Cylinder types: piston, double acting
Piston rod on both side
Velocity is the same in both directions
Hydraulic and Pneumatic Systems 16
Hydraulic cylinders
Cylinder types: piston, double acting
Piston rod on both side
Velocity is different in the two directions depending on cross section ratio of the rods
Hydraulic and Pneumatic Systems 17
Hydraulic cylinders
Cylinder types: double acting piston, tandem
Hydraulic and Pneumatic Systems 18
Hydraulic cylinders
Cylinder types: single acting, fast moving
Hydraulic and Pneumatic Systems 19
Hydraulic cylinders
Cylinder types: double acting, fast moving
Hydraulic and Pneumatic Systems 20
Hydraulic cylinders
Cylinder types: telescopic, single acting
Large working paths or limited space
Hydraulic and Pneumatic Systems 21
Hydraulic cylinders
Cylinder types: telescopic, double acting
Large working paths or limited space
Hydraulic and Pneumatic Systems 22
Hydraulic cylindersChecking for buckling:
Euler’s cases
Picture
Free buckling length
Manner of end fixing
Note
1. Case
One end freeOne end fixed
Or trunnion at end
mounting style mounting style mounting style
2. Case
Two ends pivoted and guided
3. Case
One end guided and pivoted, other end
fixed
4. Case
Two ends fixed and guided
mounting style
Hydraulic and Pneumatic Systems 23
Hydraulic cylindersCushioning of cylinders:
1. Piston
2. Cushion nose
3. Cylinder cap
4. Stroke volume
5. Cushion orifice
6. Throttle
7. Cushion adjustment screw
8. Mother
9. Non-return valve
10. Gas valve
Hydraulic and Pneumatic Systems 24
Rotary hydraulic actuators
Parallel piston rotary actuator
Hydraulic and Pneumatic Systems 25
Rotary hydraulic actuators
Hydraulic and Pneumatic Systems 26
Rotary hydraulic actuators
Rack-and-pinion piston-type rotary actuator:
Hydraulic and Pneumatic Systems 27
Rotary hydraulic actuatorsLimited angle rotary actuator:
Hydraulic and Pneumatic Systems 28
Rotary hydraulic actuatorsLimited angle rotary actuator:
Hydraulic and Pneumatic Systems 29
Rotary hydraulic actuators
Helix actuator: