The gearbox housing is a key component of the tractor gearbox, and the quality of its processing will directly affect the product's performance. (1) The shape of the part is irregular, the positioning surface is small, and 8 holes are outside the part positioning surface, wherein the 7 and 8 holes are three-layer wall through holes. (2) Processing size and accuracy requirements: 18-hole dimensional accuracy is IT7, coaxiality requires 16 holes for a0.04, 78 holes for a0.025, roundness requirement is 0.01, 911 hole size accuracy is IT7, coaxiality The requirement is a0.015.
Process analysis of parts:
1) The coarse and semi-finishing processes are combined into one, and the machining accuracy is difficult to guarantee. Due to the large machining allowance of the blank hole of the part (single margin of 58mm), if a single tool is used on a machine tool to complete the rough and semi-precision machining, the shape error of the hole is large, in order to eliminate the shape error. For the influence of finishing, the finishing process must leave a large machining allowance (about 11.2 mm on one side), which leads to a large cutting allowance in the fine boring process, and it is difficult to ensure the machining accuracy.
2) It is difficult to ensure the coaxiality of the faces on both sides of the same axis by using double-faced boring. Due to the small hole spacing of the parts, the size of the mast is limited, and the production cycle is 2.5min/piece. It is not possible to use single-sided ventilation to meet the product requirements. It must be processed by double-sided boring, and the guide is usually double-sided. , fixture, tool design, it is difficult to ensure the coaxiality of the hole system.
3) The coaxiality of the fork hole (911 hole) is required to be a0.015mm, which is difficult to achieve. Since the coaxiality requirement of the fork hole is a0.015mm, if the hole is machined, since the hole pitch is only 26.25, the spindle spindle is difficult to arrange, and it is difficult to achieve machining accuracy by ordinary drilling, expanding and hinge processes. Special tools must be used on the tool, fixture drill and spindle design to ensure machining accuracy.
Structural design of the machine tool: According to the characteristics of the machined parts, in order to achieve the processing accuracy requirements, taking into account the economic benefits and productivity, after repeated argumentation, analysis and calculation, horizontal double-sided multi-axis drilling, expansion, hinge, nesting The overall design of the combined machine tool, using two machine tools to complete the entire processing content.
(Finish)
