勃良斯克汽车厂研制成一种利用冷态塑性变形获得内螺纹的无切屑丝锥。丝锥(苏联发明证978994)包括前导和校准两部分。丝锥牙顶削平,宽度为b(图1)。牙顶宽度从丝锥的前端到校准部分逐渐扩大。端部牙顶宽b_2=0.08P(螺距),校准部分牙顶宽b_1=0.15P,宽度较小的牙顶有 Bryansk car plant developed into a use of cold plastic deformation of internal thread to obtain the chipless tap. Taps (Soviet invention certificate 978994) includes the pilot and calibration of two parts. Taps top flattened, width b (Figure 1). The width of the crest gradually increases from the tip of the tap to the calibration part. Tip crest width b_2 = 0.08P (pitch), calibration part of the crest width b_1 = 0.15P, the width of the crest is smaller