我厂自从用20~#钢分序冷挤压汽车轮胎杯形螺帽以来,杯帽的盲孔攻丝一直成为难以解决的问题。原因是20~#钢经过冷挤后表面硬化,材料的金相组织为难以切削的球状珠光体,攻丝时切屑成带状,缠绕丝攻,难于排除。同时,由于材料韧性大,附着力强,温度高,攻不了几个,丝攻表面就产生积屑瘤,烧结于牙齿之间,使螺纹拉坏。此外,毛牙、花牙情况 Since 20 ~ # steel is used in our factory, the blind hole tapping of the cup cap has been a difficult problem to solve since it was used to cold extrusion the car cup nut. The reason is that after 20 ~ # steel is hardened by cold extrusion, the microstructure of the material is spherical pearlite which is hard to cut. When the tapping is carried out, the chips become ribbons and the winding wire tapping is difficult to eliminate. At the same time, due to the material toughness, strong adhesion, high temperature, attack a few, the surface of the wire tapping on the production of tumor, sintered between the teeth, the thread pull bad. In addition, the hair teeth, flower teeth situation