The requirements of the chrome hardened bar for each part:
1. The surface roughness of the piston rod should be Ra0.4-0.8um.
2. In order to ensure the stability of the processing precision of the piston rod, manual alignment cannot be performed during the whole process.
3. The use of the piston rod needs to bear the alternating load, and the device reciprocates to rub the surface. Therefore, the surface must meet the requirements of high hardness and wear resistance.
4. When selecting the positioning reference, in order to effectively ensure the coaxiality tolerance of the parts and the mutual positional accuracy of each part, all the machining processes can be positioned with two center holes, and the bucket elevator conforms to the principle of standardization.
5. In order to ensure the machining accuracy, when turning the piston rod, the roughing and finishing vehicles should be separated. Moreover, the coarse and fine cars are always used with the tool holder to reduce the deformation of the workpiece during machining, and the center frame should be remembered when machining the threads at both ends.
6. When grinding the outer surface, the workpiece will be easy to make the knife and elastic deformation, thus affecting the accuracy of the piston rod. Therefore, the center hole should be repaired during processing, to ensure the cleaning of the center hole and the tightness between the center hole and the tip, and to ensure good lubrication.
7. When the thread processing is performed, if the machining tolerance of the piston rod is relatively large due to the thread, the centering ability is poor, and the coaxiality of the assembly cannot be guaranteed. When the guide assembly is used, the outer sealing surface should be positioned. If the length of the positioning surface is smaller than the mating length of the thread, the thread should first enter the mating during assembly and then enter the mating from the positioning surface.