轻便车把制成如图1所示的形状。横管材料为B2—3高频焊接钢管。目前国内大多数自行车厂均用外径为φ25的管坯,在缩管设备上将两端分别缩径(图2)。此工艺钢材消耗大,生产效率低,缩管后仍须进行调直、割长短和表面质量检验等工艺,废品率也较高。为了寻求一个比较理想的工艺方法,我们作了几种工艺方案的探索。试验证明,气 Lightweight handlebar shape as shown in Figure 1. Horizontal tube material is B2-3 high frequency welded steel pipe. At present, most bicycle manufacturers in China use the tube with an outer diameter of φ25, and reduce the diameter of both ends respectively in a shrink tube apparatus (FIG. 2). This process is expensive steel, low production efficiency, still need to be straightened after shrinking, cutting length and surface quality inspection process, the rejection rate is also higher. In order to seek a more ideal process, we made several technological solutions. Test proved that gas