In the process design, the accuracy and efficiency are mainly considered. Generally, the principle of surface before hole, benchmark before others, roughness before refinement is followed. The machining center in a clamping, as far as possible to complete all machining surface processing. When machining holes with high position accuracy, special attention should be paid to the arrangement of hole processing sequence. If the arrangement is not proper, the reverse clearance of transmission pair may be brought in, which will directly affect the position accuracy. For example, when arranging the hole series processing sequence of the parts shown in Fig. 5.6A, if the machining is carried out according to the route shown in Fig. 5.6b, since the positioning direction of the hole 5.6 is opposite to that of the hole 1.2.3.4 in the Y direction, the reverse clearance in the Y direction will increase the error, thus affecting the position accuracy of the 5.6 hole and other holes. According to the route shown in Fig. 5.6c, the introduction of reverse clearance can be avoided.
A /) part drawing B /) processing route 1
c) Processing route 2
Figure boring processing route
In the process of machining, in order to reduce the number of tool changes, the centralized process of cutting tools can be adopted, that is, the corresponding parts of parts are processed with the same tool, and then the second tool is replaced to continue processing. However, for the hole system with high precision requirements, this method can not be adopted because of repeated positioning error when the parts are determined by the rotation of worktable.
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