The structural principle of the cylinder

- Aug 04, 2018 -

The cylinder is composed of a cylinder, an end cap, a piston, a piston rod and a seal.

1) Cylinder

The inner diameter of the cylinder represents the output force of the cylinder. The piston should make a smooth reciprocating sliding in the cylinder, and the surface roughness of the inner surface of the cylinder should reach Ra0.8μm.

The SMC and CM2 cylinder pistons adopt a combined sealing ring to realize two-way sealing, and the piston and the piston rod are linked by pressing and riveting without using a nut.

2) End cap

The end cover is provided with an intake and exhaust port, and some also have a buffer mechanism in the end cover. A seal ring and a dust seal are provided on the rod side end cover to prevent air leakage from the piston rod and prevent external dust from entering the cylinder. A guide sleeve is arranged on the rod side end cover to improve the guiding precision of the cylinder, to bear a small amount of lateral load on the piston rod, to reduce the amount of downward bending when the piston rod is extended, and to prolong the service life of the cylinder. Guide sleeves typically use sintered oil-containing alloys, forward-lead copper castings. End caps used to be malleable cast iron. In order to reduce weight and prevent rust, aluminum alloy die-casting is often used, and micro-cylinders are made of brass.

3) Piston

The piston is a stressed part in the cylinder. In order to prevent the left and right chambers of the piston from suffocating each other, a piston sealing ring is provided. The wear ring on the piston improves the guiding of the cylinder, reduces the wear of the piston seal and reduces the frictional resistance. The wear ring length is made of polyurethane, polytetrafluoroethylene, cloth synthetic resin and the like. The width of the piston is determined by the size of the seal and the length of the necessary sliding portion. The sliding part is too short to cause early wear and seizure. The piston is made of aluminum alloy and cast iron, and the piston of the small cylinder is made of brass.

4) Piston rod

The piston rod is the most important part of the cylinder. It is usually made of high carbon steel, hard chrome plated, or stainless steel to prevent corrosion and improve the wear resistance of the seal.

5) Seal ring

The seal of the part at the rotary or reciprocating motion is called a dynamic seal, and the seal of the stationary part is called a static seal.

There are mainly the following methods for connecting the cylinder tube to the end cover:

Integral, riveted, threaded, flanged, and tie rod type.

6) When the cylinder is working, it is necessary to lubricate the piston by the oil mist in the compressed air. There are also a small number of lubrication-free cylinders.