在机械制造中,有些零件上的螺纹孔,是在装配时再划线加工的。划线时,往往用与其相配零件的孔来定位后再划出加工线的,这样划出的螺纹孔加工线,其中心位置不易找得较理想。如采用图1所示“找中心工具”,便能很容易地找到较理想的中心位置。此工具中定位杆1与外套3、中心针5分别为滑动配合,中心针5需要 In machine construction, the threaded holes in some parts are re-scribed during assembly. Marking, often with its matching parts of the hole to locate and then draw the processing line, so drawn thread hole processing line, the center position is not easy to find the ideal. If you use the “find center tool” shown in Figure 1, you can easily find the ideal center. In this tool, the positioning rod 1, the outer sleeve 3 and the center needle 5 are respectively sliding fit and the center needle 5 needs