图1所示零件,大批量生产时,其坯料皆为冷冲压的冲盂引伸件。若滚丝前,切长至图纸要求尺寸,羟滚丝试制得知,它们内孔尺寸的口部将胀大而形成喇叭口,其内孔螺纹收尾对虚部位,孔壁上将产生半周～1周的光滑凸台。这样,制件的内孔尺寸及光洁度皆无法保证,零件不能使用。为此采取如下工艺措施: Figure 1 shows the parts, high-volume production, the blanks are all cold stamping Chongyu extension pieces. If rolling before, cut to length requirements of the drawings, rolled wire trial production that they will increase the size of the mouth of the mouth to swollen and the formation of a bell mouth, the inner hole thread end of the imaginary part of the hole wall will have a half weeks ~ 1 week smooth boss. In this way, the parts of the hole size and finish are not guaranteed, the parts can not be used. To this end take the following technical measures: