DETERMINE THE SIZE pneumatic cylinder

By: arya

Factors that determine the cylinder size is determined by the magnitude of the force received by the cylinder and the length of steps to be performed by the cylinder to move the load.

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where: F = effective piston force (Newton)
p = working pressure (bar / Pa / psi)
d = piston diameter (cm)
R = friction (Newton) was taken 30-20% of the calculated force

Friction is determined by the lubrication, back pressure, the shape of the seal and so forth. Effective piston style means a lot in planning the cylinder. In calculating the effective piston force, frictional resistance must be taken into account. In normal operating conditions the limit pressure 400-800 kPa or 4-8 bar.
For single-cylinder drive, then apply:

F = A. p - (Rf + Rr)

For the double-cylinder drive, then apply:
F = A. p - Rr: to advance
F = A '. p - Rr: to resign

Description: Rf = force versus spring
Rr = friction
A = sectional area of the cylinder without piston rod
A '= area of cross section of cylinder with piston rod
EXAMPLE 2.1:
If the cylinder has a diameter (D) 50 mm diameter piston dsan (d) 12 mm, having a frictional force (Rr), an average of 10% and 600 kPa applied pressure.
Determine the sectional area of cylinder piston rod with and without (A and A ') and how much force F that can be generated (steps forward and steps backward).

Completion:
Sectional area of the cylinder without piston rod:
A = Â¼ phi x D '= 0.785 x 5 = 19.625 cm
Sectional area of cylinder with piston rod
A n = (D - d) x 0.785 = (25-1.44) = 18.50 cm
Theoretical piston style in a step forward:
F = A xp = 19.626 x 10 x 6 x 10 N / m = 1177.50 N
Style Rr taken (on average 10%) = 117.75 N
So that the effective piston force on a step forward:
F = A xp - Rr = 19.625 x 10 x 6 x 10 N / m - 117.75 N = 1060 N
Theoretical piston style in step backwards:
F = A 'x p = 18.50 x 10 m x 6 10 N / m = 1110 N
Friction is taken Rr (average 10%) = 111N
Effective piston style in step backwards:
F = A 'xp - Rr = 18.5 x 10 x 6 x 10 N / m - 111N = 999N.

a. Buckling load
Given load on the piston rod should not exceed the maximum allowable price. This is related to stride length and diameter of the piston rod. The amount of the allowable buckling force (FK) is as follows:
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Description:
Fk =is permitted buckling force (N)
E = modulus of elasticity (N/mm2)
J = moment of inertia (cm)
L = length of effective measures (cm) = 2x stride length
S = safety factor (taken 5)

b. Stride length
Pneumatic cylinder stride length should not exceed 2000 mm. With a large diameter cylinder and the long stroke, large air consumption makes pneumatic equipment to be wasteful.
With a big step, mechanical stress on the piston rod and the bearing guide is too big. To avoid bending, then a large diameter piston rod length selected for a big step. Then if the length is enlarged so that the distance between the bearing increases and enlarged piston rods.

c. Piston speed
Piston speed depending on the prevailing air pressure, pipe length, cross-sectional area at the end of the control and also working part of the average flow through the end of the control section. Also influenced by the position of end pads. When there is movement from the end position of pads, aids the flow through the valve block (thortte relief valve), so that the piston speed can be derived. The average piston speed standard cylinder approximately 0.1 to 1.5 m / sec. With a special cylinder (cylinder impact), the speed can reach 10 m / sec. Piston speed can be adjusted by using the valve.

d. Air Consumption
To obtain information on the number of indoor air usage is as follows:
For a single drive cylinder:
Q = 0.785 x D x h x n
For double drive cylinder:
Q = (0.785 x D x h + 0.785 (D - d) x h) n x pk

Description:
Q = volume of air every centimeter step (liters)
D = piston diameter (mm)
h = length of step (mm)
n = number of steps per minute
pk = compression ratio (liters / min)
For specific operating pressure, certain piston diameter and a specific step number takanan air consumption can be calculated by comparing the compression

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