我厂几年来,生产了2万多只液压支架油缸,但制造中出现了一些废品,主要是油缸内孔精度超差,光洁度低,有麻点等。已经报废处理几百只,仅料价即300～400元/只。损失不小,为提高成品率,对缸筒进行了冷拔(修复)工艺,达到良好的效果,情况如下。一、材料冷拔(收缩)试验为了要达到冷拔(收缩)的精度,用图1所示坯料(材料40Cr)。 Over the past few years, our factory has produced more than 20000 hydraulic support cylinders, but there are some wastes during the manufacturing process, mainly due to the poor precision of the inner hole of the cylinder, poor finish and pitting. Has been scrapped to deal with hundreds, only the price that 300 ~ 400 yuan / only. Loss is not small, in order to improve the yield, the cylinder was cold drawn (repair) process, to achieve good results, the following is the case. First, the material cold drawing (shrinking) test In order to achieve cold drawing (shrinking) accuracy, shown in Figure 1 blank (material 40Cr).