C618K和111C是两种性能、规格基本相同的小型普通车床,由于使用时间较长,主轴箱前轴承孔与轴承外环的配合已经松劲,且圆度超差一般都在0.03mm左右;同时,原设计刀架的最小纵向进刀量为0.15mm/r,大大高于现行同类普通车床设计值,精加工时走刀量太大,致使该车床所加工的零件几何精度和表面粗糙度都不能满足生产工艺要求。对于主轴箱前 C618K and 111C are two kinds of small size general lathes of the same performance and specifications. Due to the long service life, the cooperation between the bearing holes in the front of the spindle box and the outer race of the bearing has become loose and the roundness tolerance is generally around 0.03mm; meanwhile, The original design of the minimum longitudinal tool holder into the 0.15mm / r, much higher than the current design of similar general lathe, finishing the amount of walking too much, resulting in the lathe machining parts geometry and surface roughness can not Meet the production process requirements. For the headstock front