What role does the division of processing stages play in precision parts processing
The division of processing stages of precision parts should not be absolute, but should be flexibly controlled according to the quality requirements, structural characteristics and production guidelines of parts.
1. To ensure the processing quality. When the workpiece is rough machined, the removed metal layer is thicker, the cutting force and clamping force are larger, and the cutting temperature is higher, which will cause greater deformation. If the processing stages are not divided, and the rough machining and finish machining are mixed together, the processing errors caused by the above reasons cannot be avoided. According to the processing stage, the processing error caused by rough machining can be corrected by semi finishing and finishing, so as to ensure the processing quality of parts.
2. Use the equipment reasonably. The rough machining allowance is large, the cutting amount is large, and the machine tools with large power, good rigidity, high efficiency but low accuracy can be used. The precision machining has small cutting force and little damage to the machine tool. Use high-precision machine tools. This gives full play to the respective characteristics of the equipment, which can not only improve the processing productivity of precision parts, but also extend the service life of precision equipment.
3. It is convenient to find blank defects in time. Various defects of the blank, such as porosity, sand inclusion and insufficient allowance of the casting, can be found after rough machining to facilitate timely repair or scrapping, so as to avoid further processing and waste.
4. It is convenient to arrange the heat treatment process. For example, after rough machining, stress relief heat treatment is generally arranged to eliminate internal stress. Final heat treatment such as quenching shall be arranged before finishing, and its deformation can be eliminated by finishing.
When the processing quality of precision parts is not high, the rigidity of the workpiece is good, the precision of the blank is high, the machining allowance is small, and the production process is not large, so there is no need to divide the processing stages. For heavy workpieces with good stiffness, because clamping and transportation are time-consuming, all rough machining and finishing are usually completed in one clamping. For the workpieces that are not divided into processing stages, in order to reduce the influence of various deformations during rough machining on the processing quality, after rough machining, loosen the clamping mechanism and keep it for a period of time to make the workpieces completely deformed, then use less after heating, re clamp the clamping force and complete the processing.