Method for selecting cylinders

1、 Selection of cylinders

(1) The magnitude of cylinder force

(2) The length of cylinder stroke

(3) The movement speed of the piston (or cylinder)

(4) Selection of installation form

(5) Air consumption of the cylinder

(1) The magnitude of cylinder force：

Determine the thrust and tension on the piston rod based on the required force for the job. When selecting a cylinder based on this, there should be a slight margin for the output force of the cylinder. If the cylinder diameter is selected too small, the output force is not enough, and the cylinder cannot work normally; However, a large cylinder diameter not only makes the equipment bulky and costly, but also increases gas consumption, resulting in energy waste. When designing fixtures, force increasing mechanisms should be used as much as possible to reduce the size of the cylinder.

The following is the calculation formula for the theoretical output of the cylinder:

F: Theoretical output force of cylinder (kgf)

F ': Output force at 85% efficiency (kgf) - (F'=F × 85%)

D: Cylinder diameter (mm)

P: Work pressure (kgf/cm2)

When determining the output force in engineering, one can directly refer to empirical figures 1-1 and 1-2.

Example:What is the theoretical output force of a cylinder with a diameter of 340mm and a working pressure of 3kgf/cm2? What is the output of sprouts?

Connect P and D, find the points on F and F ', and obtain:

F=2800kgf; Ｆ′＝2300kgf

When selecting the cylinder diameter in engineering design, it can be found from experience table 1-1 based on its operating pressure and theoretical thrust or tension.

Example:There is a cylinder with a working pressure of 5kgf/cm2, and its thrust when the cylinder is pushed out is 132kgf (cylinder efficiency is 85%). Question: What is the cylinder diameter to choose?

The theoretical thrust of the cylinder can be calculated as F=F ′/85%=155 (kgf) based on the cylinder's thrust of 132 kgf and efficiency of 85%

Based on the pressure of 5kgf/cm2 and the theoretical thrust of the cylinder, it can be found from Table 1-1 that selecting a cylinder with a diameter of  63 can meet the usage requirements.