Piston rod: key points in selecting the core transmission components of hydraulic cylinders and cylinders
The piston rod is a transmission component that connects the piston and external mechanisms. It mainly bears tensile pressure and bending stress. It is widely used in hydraulic cylinders, cylinders and various linear motion mechanisms. The quality of the piston rod directly determines the working performance and service life of the hydraulic or pneumatic system. It is one of the key basic parts in the field of machinery manufacturing. A high-quality piston rod requires high strength, high wear resistance, good guidance and reliable seal compatibility.
From a material perspective, piston rods are usually made of high-quality carbon structural steel or alloy structural steel, such as No. 45 steel, 40Cr, 27SiMn, etc. For heavy loads or special working conditions, carburized steel, nitrided steel or stainless steel materials will also be used. Raw materials must undergo strict non-destructive testing to ensure that there are no internal defects such as cracks and slag inclusions. The heat treatment process is a key link in determining the performance of the piston rod. Quenching and tempering treatment is usually used to obtain good comprehensive mechanical properties. The surface is subjected to induction quenching, carburizing quenching or nitriding treatment to obtain a high-hardness wear-resistant layer as needed.
The surface treatment process of the piston rod has a significant impact on its service life. Common surface treatment methods include high-frequency quenching, carburizing, nitriding, hard chromium plating and QPQ treatment. Hard chromium plating is the most widely used method. The chromium layer has high hardness, good wear resistance and low friction coefficient, and can effectively protect the substrate from wear and corrosion. QPQ treatment has better overall performance, improving surface hardness while also improving corrosion resistance and fatigue strength. In addition, for use environments with special anti-corrosion requirements, stainless steel materials or special anti-corrosion coatings will be used.
The dimensional accuracy and geometric tolerance requirements of the piston rod are very strict. The straightness of the rod body is directly related to the sealing performance and service life of the cylinder or hydraulic cylinder, and is usually required to be in the range of 0.05-0.1mm/m. The surface roughness of the rod body is also an important indicator. After fine grinding and polishing, the surface roughness Ra value should reach 0.1-0.4μm. The end connection threads need to be machined according to the corresponding accuracy level and accurately matched with the relevant mating parts.