In the flow of machining of non-standard parts, the basis is the most important. The processing of precision mechanical parts is also the same. The fine reference is always processed first, and then the other surface is processed with the fine reference.
For the box parts, the main hole is generally used as the rough reference machining plane, and the plane is the fine reference machining hole; for the shaft parts, the outer circle is generally used as the rough reference machining center hole, and the center hole is used as the fine reference processing. Outside surfaces, end faces, and other surfaces. If there are several fine references, the machining of the base surface and the main surface should be arranged in accordance with the order of the reference conversion and the principle of progressively improving the machining accuracy.
For workpieces such as cabinets, brackets, and connecting rods, the plane post-processing holes should be machined first. Because the contour of the plane is flat and the area is large, the first machining plane and then the machining hole are positioned in a plane, which can not only guarantee a stable and reliable positioning reference for the hole during processing, but also help ensure the position accuracy requirement between the hole and the plane.
A part usually consists of multiple surfaces, and the processing of each surface generally needs to be performed in stages. When arranging the processing sequence of precision mechanical parts, the rough machining of each surface shall be arranged first, semi-finishing shall be arranged in sequence in the middle according to needs, and the final finishing and finishing shall be arranged. For workpieces with high precision requirements, in order to reduce the influence of rough machining on the finishing process, rough and finish machining should not be performed continuously, but should be performed in stages and at appropriate intervals.
The general principle of the processing and cutting procedures for non-standard parts is: the previous work must be ready for the work behind, lay a good foundation, and provide good service. Non-standard parts processing specific working principles can be divided into four aspects:
The main surfaces of parts are generally surfaces with high processing accuracy or surface quality requirements. Their quality of processing has a great influence on the quality of the entire part, and their processing procedures are often numerous. Therefore, the main surface should be arranged first. Then other surface finishes are appropriately arranged to intersperse between them. The assembly base surface, work surface, etc. are generally regarded as main surfaces, and key grooves, light holes and screw holes for fastening, etc. are regarded as secondary surfaces.