一、引言 棒料或管料的缩杆工艺是将一根直径为D的圆棒料或圆管料在外力作用下使其通过直径小于D的模孔,使其直径减小为d。图1是自行车把手的成形工序图,图2是把手成形前工序图。把手的中间凸台部分老工艺都是大管套小管焊接而成。如果要使其如图2所示的以整体形式存在,可考虑用三种工艺方法加工:中间部分用橡皮胀形;两端部 I. INTRODUCTION The rod or tube material shrinking rod process is a diameter of the D bar or tube under the action of external force through the diameter of less than D die hole, so that its diameter is reduced to d. FIG. 1 is a molding process diagram of a bicycle handlebar, and FIG. 2 is a process drawing of a handle before molding. The boss of the middle part of the boss of the old process are large tube welded tube. If you want to make it as shown in Figure 2 as a whole form, consider the use of three kinds of processing methods: the middle part with rubber bulging; both ends