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我厂生产的红旗100、120拖拉机的后桥箱合件,由铸钢件与冲压件焊接而成。它的A面上有12个M16-2螺纹孔,用于变速箱与后桥箱的联接。在长期生产中,这一精度要求始终未能得到保证,致使装机后,后桥箱中央传动室内的齿轮油从此处泄漏,影响整机质量。经分析,我们找出了影响螺纹精度的主要原因:机床主轴(Z35摇臂钻床)、攻丝安全夹头、丝锥夹套、丝锥等的制造允差及安装误差的叠加,致使丝锥刃部的中心线相对机床主轴的中心线的摆差过大(见图1),当攻丝时,丝锥引入底孔便在底孔孔壁的约束下与机床主轴同心,使丝锥与机床主轴联结的工艺装备系统产生一个弹性变形(见图2)。丝锥在这个变形力的作用下对孔壁产生正扩切,使螺纹孔径尺寸
I plant red flag 100,120 tractor box parts after the bridge, made of cast steel and stamping welded together. It has 12 M16-2 threaded holes on side A for transmission and rear axle box connections. In long-term production, this accuracy requirement has not been guaranteed, resulting in installed, the gearbox oil in the central transmission chamber of the rear axle box leaks from here, affecting the overall quality. After analysis, we find the main reasons that affect the thread accuracy: the manufacturing tolerances of machine tool spindle (Z35 radial drilling machine), tapping safety chuck, tap jacket, tap, etc. and the installation error, Centerline relative to the machine tool spindle center line swing is too large (see Figure 1), when tapping, the tap into the bottom of the hole in the bottom hole wall is constrained and machine tool spindle concentric, so that the tap and machine tool spindle coupling process Equipment system to produce a flexible deformation (see Figure 2). Taps under the action of this deformation force on the hole wall has a positive expansion, so that the screw aperture size