Introduction to the structure and principle of the cylinder
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2019/08/27
Cylinder consists of a cylinder, end cap, piston, piston rod and seal.
1) Cylinders
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 Ra0.8um. For steel pipe cylinders, the inner surface should also be plated with hard chrome to reduce frictional resistance and wear and prevent rust. In addition to the use of high carbon steel tubes, the cylinder material is also made of high-strength aluminum alloy and brass. Small cylinders are made of stainless steel. Cylinders with magnetic switches or cylinders used in corrosive environments should be made of stainless steel, aluminum or brass.
SMC CM2 cylinder piston uses a combination of sealing ring to achieve two-way sealing, piston and piston rod with riveting link, no nut.
2) End cap
The end cap is provided with inlet and outlet ports, and some also have a buffer mechanism inside the end cap. 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. Nowadays, in order to reduce weight and prevent rust, aluminum alloy die-casting is often used, and micro-cylinders are made of brass.
3)Piston
Piston is a pressurized part of 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
Piston rod is an important part of the cylinder. High carbon steel is usually used, the surface is hard chrome plated, or stainless steel is used to prevent corrosion and improve the wear resistance of the seal.
5) Sealing ring
The component seal at the rotary or reciprocating motion is called a dynamic seal, and the seal of the stationary part is called a static seal.
The connection method between the cylinder and the end cover is mainly as follows:
integral type, riveted type, threaded type, flange type, 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.
Determine the thrust and pull 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.
