Basic requirements and roll forming of piston rod
The piston rod can be processed by rolling during the production process. To a certain extent, the surface layer will have residual compressive stress on the surface, which is helpful for the closure of tiny cracks on the surface, which can hinder the expansion of erosion. Therefore, the corrosion resistance of the surface is improved, and the piston rod can delay the generation or expansion of fatigue cracks, thereby improving the fatigue strength of the cylinder rod.
The piston rod is formed by rolling, and its rolling surface will form a layer of cold work hardening, which can reduce the elastic and plastic deformation of the contact surface of the grinding pair, thereby improving the wear resistance of the surface of the cylinder rod, while avoiding Burns caused by grinding.
After the piston rod is rolled, its surface roughness value is reduced, which can effectively improve the matching properties, and at the same time, reduce the friction damage to the seal ring or seal when the cylinder rod and piston move, and improve the overall service life of the cylinder . The rolling process is a high-quality process measure.
Basic requirements for piston rods
1. The piston rod requires sufficient strength, stiffness and stability to a certain extent.
2. The piston rod has good wear resistance and requires high machining accuracy and surface roughness.
3. Minimize the effects of stress concentration on the structure.
4. Ensure reliable connection and prevent loosening.
5. The design of the piston rod structure should facilitate the disassembly and assembly of the piston.
In general, the blank of the piston rod is suitable to choose 38CrMoAlAn alloy structural steel. After quenching and tempering treatment and surface nitriding, high core strength, excellent wear resistance and fatigue resistance can be obtained. If the piston rod is produced in small batches, in order to effectively improve the production efficiency, free forging should be used to make the blank. However, when using free forging to make blanks, it is necessary to determine the size and shape of the blanks.
Under normal circumstances, if the piston rod is produced in small batches, the cylindrical blank should be selected. However, since different parts have different processing accuracy requirements, it is necessary to set the dimensional tolerance level of forgings to 8-12.
