Classification and composition of hydraulic cylinders

Hydraulic cylinder according to the form of structure, can be divided into piston cylinder, piston cylinder, swing cylinder and special cylinder four categories; according to the rated pressure is divided into high pressure and ultra-high pressure hydraulic cylinder, medium and high pressure hydraulic cylinder and medium and low pressure hydraulic cylinder .......

1, cylinder barrel: cylinder barrel is the main parts of the hydraulic cylinder, it and cylinder head, piston and other parts constitute a closed cavity, push the piston movement. Commonly used cylinder structure has 8 types, usually according to the cylinder and end cover connection form selection. Materials generally require sufficient strength and impact toughness, welding also has good welding performance, so commonly used materials are: 25, 45, ZG200 ~ 400, 1Cr18Ni9 and so on. Cylinder barrel blanks are mostly cold drawn or hot tied seamless steel tubes, so the process is usually tempering (to ensure the strength of the cylinder, so that it can withstand oil pressure will not deform and damage) → honing or boring rolling (to ensure the cylinder bore roughness, roundness, cylindricity and straightness, etc., so that the piston seal in the long-term reciprocating motion after the same) → car (to ensure that the full length of the cylinder and other design size requirements) → drilling (processing of the oil port hole, to ensure access to (oil circuit) → clamp

2, cylinder cover: cylinder cover installed in both ends of the hydraulic cylinder, and cylinder barrel constitute a tight oil cavity. Usually have welding, thread, bolt, key and tie rod and other connection methods, generally according to the working pressure, the cylinder connection, the use of environmental factors such as choice.

3, piston rod: piston rod is the main component of the hydraulic cylinder to transmit force. Material generally choose medium carbon steel (such as 45 steel). Cylinder work, the piston rod by the thrust, tension or bending moment, solid to ensure its strength is necessary; and the piston rod is often in the guide sleeve sliding, with the appropriate should be too tight, friction, too loose, easy to cause jamming phenomenon and unilateral wear, which requires its surface roughness, straightness and roundness, etc. appropriate. Therefore, the process of piston rod is usually rough turning → tempering → semi-finishing → quenching → pre-plating grinding → chrome plating → post-plating grinding → finishing turning

4, piston: piston is the main component to convert hydraulic energy into mechanical energy, its effective working area directly affects the force and speed of movement of the hydraulic cylinder. Piston and piston rod connection has a variety of forms, commonly used are card ring type, sleeve type and nut type. When there is no guide ring, piston with high strength cast iron HT200 ~ 300 or ductile iron; when there is a guide ring, piston with high quality carbon steel No. 20, No. 35 and No. 45.

5, guide sleeve: guide sleeve on the piston rod to play a guiding and supporting role, it requires high precision, friction resistance, good wear resistance, can withstand the pressure of the piston rod, bending force and shock vibration. Inside is equipped with a sealing device to ensure the cylinder rod cavity seal, the outer side is equipped with a dust ring to prevent impurities, dust and moisture to the sealing device, damage to the seal. Metal guide sleeve is generally used friction coefficient is small, good wear resistance of bronze, gray cast iron, ductile iron and oxidized cast iron, etc.; non-metal guide sleeve can be used polytetrafluoroethylene and polytrifluoroethylene, etc.

6, buffer device: piston and piston rod in the hydraulic pressure of the drive movement has a lot of momentum, when entering the cylinder end cover and the bottom part of the cylinder, will cause mechanical collision, resulting in a large impact pressure and noise. The cushioning device is used to avoid this collision. Its working principle is to make the cylinder low pressure chamber oil (all or part) through the throttling of kinetic energy into heat, heat energy by the circulation of oil to the hydraulic cylinder outside. The structure of the buffer device is divided into two types: constant throttle area buffer device and variable throttle type buffer device.