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目前,在S195连杆(见附图)的加工过程中,大多数工厂都是按照传统的加工方法,即选择一平面(连杆体两侧平面之一)、一孔(小端孔或大端孔)以及工艺定位面作为基准,以消除六个自由度,实现对工件的定位。这对于形位公差要求不高的加工工序,也是正确的。但是,对于连杆螺孔攻丝工序,选用上述方法定位,因定位精度低,加工误差大,所加工出的螺孔对分开面的垂直度不够稳定,经常出现超差现象,达不到图纸的设计要求。鉴于攻丝垂直度不稳定的现象,笔者通过对几种定位方案的分析比较,认为:必须从连杆本身的形状特点出发,选择连杆体及盖的分开面作为第一定位基
Currently, during the machining of the S195 connecting rod (see the attached drawings), most of the factories follow the conventional processing method of selecting a flat surface (one of the two sides of the connecting rod body), a hole (small end hole or large End hole) and the process of positioning as a benchmark to eliminate six degrees of freedom to achieve the positioning of the workpiece. This is not correct for the shape of tolerance requirements of the processing operations, but also correct. However, for connecting rod tapping process, using the above method of positioning, positioning accuracy is low, the machining error is large, the machined screw hole on the vertical separation of the surface is not stable enough, often over-tolerance phenomenon, not up to the drawings The design requirements. In view of the tapping vertical instability phenomenon, the author through the analysis and comparison of several positioning programs, that: we must start from the shape of the connecting rod itself, choose the connecting rod body and cover the separate surface as the first positioning base