1.Proposal of the problem The standard nut produced by the FAW Group Company's Jilin Standard Parts Factory uses the shank nut tap shown in Figure 1 for the internal thread processing. For the nut processing of small-diameter fine teeth, there is always a tapping torque during the machining process. The phenomenon of twisting of the large and tapped shank has been improved, and the welding technology has been improved to ensure the welding quality. However, the tap still only processes more than 200 pieces and wears or sticks, resulting in the nut "chain candied haw", which makes the instantaneous torque too large, and the tap bending handle is twisted or broken. Recently, due to the slight decrease in the hardness of raw materials cold piers, this phenomenon has become more serious, affecting the normal production.
