Determine the thrust and tension on the piston rod based on the amount of force required for the job. Therefore, when selecting the cylinder, the output force of the cylinder should be slightly margined. If the cylinder diameter is small, the output force is not enough, the cylinder can not work normally; but the cylinder diameter is too large, which not only makes the equipment cumbersome, high cost, but also increases the gas consumption, resulting in waste of energy. When designing the fixture, 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: cylinder theoretical output force (kgf)
F': output force (kgf) at an efficiency of 85%--(F'=F×85%)
D: cylinder bore (mm)
P: working pressure (kgf/Cm2)
Example: When the working pressure is 3kgf/cm2 for a cylinder with a diameter of 340mm, what is the theoretical output force? What is the bud output force?
Connect P and D to find the points on F and F'.
The cylinder bore diameter is selected during engineering design and can be found from the experience table 1-1 according to the pressure of its use and the theoretical thrust or tension.
Example: A cylinder has a working pressure of 5kgf/cm2, and its thrust is 132kgf when the cylinder is pushed out (the cylinder efficiency is 85%). Q: How large is the cylinder bore?
According to the thrust of the cylinder 132kgf and the efficiency of the cylinder 85%, the theoretical thrust of the cylinder can be calculated as F=F'/85%=155(kgf)
By using the theoretical pressure of 5kgf/cm2 and the cylinder, it is found that the cylinder with the cylinder diameter of ?63 can meet the requirements.