Principles and stages of precision metal parts processing

u200bThe principle of precision metal parts processing, the focus of pure basic level consideration is how to reduce errors and improve accuracy, so the basic principles for selecting the essential surface are: First: the principle of benchmark coincidence. The design basis as much as possible should be selected as the positioning basis. Especially in the completion, to ensure the accuracy, we should pay more attention to this principle. This can avoid causing position error and reference deviation; second: the principle of unified reference. Various surface treatments of a unified positioning reference surface should be selected to ensure the position accuracy between the surfaces as much as possible; sometimes the principle of common reference is also followed and repeated processing; third: the principle of self-reference. Some small machining allowances and a unified finishing process ensure the processing quality and productivity, and the precision machined surface itself serves as a basic level. We divide mechanical processing into the following four stages: First, face first, hole second. For parts such as box body, bracket and connecting rod, the plane should be processed first and then the hole should be processed. In this way, the holes can be positioned on the plane to ensure the position accuracy of the plane and the holes, and it is convenient to process the holes on the plane. 2. Machining the reference surface first. During the machining process, the surface as the positioning reference should be processed first, so as to provide a precise reference for the subsequent processing as soon as possible. Called 'benchmark first.' 3. Finishing processing of the main surface (such as grinding, honing, fine grinding\rolling processing, etc.) should be carried out in the process route stage. The surface finish after processing is above Ra0.9um, and slight collisions will damage it. The surface, in Japan, Germany and other countries, must be protected with flannel after finishing. Never touch the workpiece directly with your hands or other objects, so as to prevent the finishing surface from being affected by the transfer and installation between processes. damage. 4. Dividing the processing stages Surfaces with high processing quality requirements are divided into processing stages, which can generally be divided into three stages: rough machining, semi-finishing and finishing. Mainly to ensure the processing quality; facilitate the rational use of equipment; facilitate the arrangement of the heat treatment process; and facilitate the discovery of blank defects.