Two, hydraulic transmission equipment is usually composed of power, execution, control and auxiliary and other four components. And hydraulic cylinders as a realization of linear reciprocating motion or less than 360. Reciprocating swing movement of the hydraulic mechanism, simple structure, reliable work, but also the hydraulic system is extremely widely used in the main executive element, it is the prime mover in the form of mechanical energy to drive the hydraulic pump to produce liquid pressure energy, and then into a load can be driven directly to reciprocating motion or less than 360.
Third, the classification of hydraulic cylinders and Composition:
Hydraulic cylinder according to the structure of the form, 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 cylinders, high-pressure hydraulic cylinders and low-pressure hydraulic cylinders.
1, cylinder: cylinder is the main body of the hydraulic cylinder parts, it and the cylinder head, piston and other parts constitute a closed cavity to promote the piston movement. Commonly used cylinder structure has 8 categories, usually according to the cylinder and end cover connection form selection. Materials are generally required to have sufficient strength and impact toughness, but also have good welding performance, so the commonly used materials are: 25, 45, ZG200 ~ 400, 1Cr18Ni9 and so on. Cylinder blanks are mostly cold-drawn or hot-drawn 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 be deformed and damaged) → honing or boring rolling (to ensure that the roughness of the inner diameter of the cylinder cylinder, roundness, cylindricity, and straightness, etc., so that the sealing of the piston in the long term reciprocating motion unchanged) → car (to ensure that the cylinder cylinder cylinder full-length and other design dimensions required) → drilling (machining the oil port hole to ensure that the inlet and outlet) → clamp
2, cylinder head: cylinder head installed at both ends of the hydraulic cylinder, and cylinder tube constitutes a tight oil cavity. Usually there are welding, threaded, bolts, card key and tie rod and other types of connection, generally according to the working pressure, the cylinder connection, the use of the environment and other factors to choose.
3, piston rod: piston rod is the main component of the hydraulic cylinder force transfer. Materials generally choose medium carbon steel (such as 45 steel). Cylinder work, the piston rod is subject to thrust, tension or bending moment, etc., solid to ensure its strength is necessary; and the piston rod is often sliding in the guide sleeve, with should be appropriate, too tight, friction, too loose, easy to cause the phenomenon of hysteresis 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-finish turning → quenching → grinding before plating → chrome plating → grinding after plating → finish turning.
4, piston: piston is the main component of the hydraulic energy into mechanical energy, its effective working area directly affects the hydraulic cylinder force and speed of movement. Piston and piston rod connection has a variety of forms, commonly used ring type, sleeve type and nut type. When there is no guide ring, the piston with high-strength cast iron HT200 ~ 300 or ductile cast iron; when there is a guide ring, the piston with high-quality carbon steel 20, 35 and 45.
5, guide sleeve: guide sleeve on the piston rod to play a guiding and supporting role, it requires a high degree of precision, frictional resistance, good wear resistance, can withstand the pressure of the piston rod, bending force and shock vibration. Inside the sealing device to ensure that the cylinder rod cavity sealing, the outside is equipped with a dust ring to prevent impurities, dust and moisture to the sealing device, damage to the seal. The metal guide sleeve is generally used with a small coefficient of friction, good wear resistance of bronze, gray cast iron, ductile iron and oxidized cast iron, etc.; non-metallic guide sleeve can be used polytetrafluoroethylene and polytrifluoroethylene, etc..
6, cushioning device: the piston and piston rod in the hydraulic pressure driven movement has a lot of momentum, when the cylinder into the end cap and the bottom part of the cylinder, it will cause mechanical collision, resulting in a lot of impact pressure and noise. The use of cushioning devices is to avoid such collisions. The operating principle is to make the cylinder barrel low-pressure chamber of the fluid (all or part) through throttling the kinetic energy is converted to thermal energy, thermal energy is brought to the hydraulic cylinder by the circulation of the fluid outside. The structure of the buffer device is divided into constant throttle area buffer device and variable throttle type buffer device two.