机电产品中约有60％以上的零件带有内螺纹,近一半以上为有色金属制件。其螺纹精度常为三级,规格大多在M12以下。内螺纹加工,习惯上采用切削丝锥攻制,但存在着一定的缺陷:如制件金属纤维被切断,使螺纹强度降低;螺孔内有残留切屑,丝锥易拆断和寿命低等。国外早在60年代已使用挤压丝锥,我厂近几年来,对M4、M5、M6、M8和M10等挤压丝锥作了工艺试验,初步取得了一些经验,现介绍如下: 一、挤压丝锥结构内螺纹挤压成形原理和零件挤压成形原理相类似。挤压用丝锥除工作部份l_3与切削丝锥不同外,其它部份基本相同(见图1)。 About 60% of mechanical and electrical products with internal thread, nearly half of the non-ferrous metal parts. The thread accuracy often three levels, most of the specifications below M12. Thread processing, the habit of cutting tapping tapping, but there are some shortcomings: If the pieces of metal fibers are cut off, so that the thread strength is reduced; there are residual chips in the screw hole, taps easy to break and low life expectancy. Foreign as early as the 60s have been using extrusion tap, I plant in recent years, the M4, M5, M6, M8 and M10 extrusion tap made a technical test, initially made some experience, are as follows: First, the extrusion Taps internal thread extrusion forming principle and parts extrusion molding process is similar. Extruded tap except for the working part l_3 and cutting tap different, the other parts are basically the same (see Figure 1).