Function and processing technology of piston rod

Piston rod is a connecting component that supports the piston to do work, and is mostly used in the motion execution components of oil cylinders and cylinders. It is a moving component with frequent movement and high technical requirements. Taking a hydraulic cylinder as an example, it consists of a cylinder barrel, a piston rod (cylinder rod), a piston, and an end cap. The quality of its processing directly affects the life and reliability of the entire product. The machining requirements for piston rods are high, with surface roughness requirements of Ra0.4~0.8um, and strict requirements for coaxiality and wear resistance.

The main function of the piston rod packing ring is to seal the gap between the cylinder seat and the piston rod, which can prevent leakage of the piston rod. Generally, there are three clearances in the piston rod packing, namely, axial clearance: mainly used to ensure that the packing ring can float freely, otherwise the piston rod cannot work normally. Radial clearance: Avoid compressing the packing ring due to the sinking of the piston rod to avoid deformation or damage.

The processing technology of the piston rod is also a very important part, in which the quality of the processing technology will directly affect the quality and service life of the piston rod. Generally, the piston rod is processed by rolling, because using this processing method can improve the corrosion resistance of the piston rod surface, delay the generation and expansion of fatigue cracks, and thereby improve the fatigue strength of the piston rod.

The piston rod is not expected to withstand radial forces from the perspective of design considerations, but due to the limitations of the actual structure, the piston rod of its hydraulic cylinder inevitably bears a significant portion of radial external forces. Therefore, the length of the hydraulic cylinder piston needs to be appropriate, typically 0.7 to 1.0 times the outer diameter of the piston rod. To increase its guiding effect and increase the bearing surface area, thereby reducing wear and extending the service life of the hydraulic cylinder.

The quality of hydraulic pipelines largely depends on the quality of piston rods, so the machining of pistons should have sufficient and accurate geometric tolerances. Generally speaking, the error of the roundness and cylindricity of the piston outer diameter and inner hole should not be greater than half of its dimensional tolerance; The coaxiality tolerance of the outer diameter of the piston rod to the inner hole and sealing groove should be within 0.02mm. Generally, the perpendicularity tolerance of the end of the hydraulic cylinder to the axis of the hydraulic cylinder should be less than 0.04mm/100mm.