U形管是聚变堆实验中比较重要的一类管件,但其整体成形难度比较大,研究了U形管的一半,即矩形截面L形管件的冷推弯成形.为了防止管坯起皱,在推弯过程中,使用了3种不同的柔性芯棒形式:低熔点合金、轴承滚珠、聚氨酯橡胶.实验结果表明,采用低熔点合金芯棒,在管坯表面润滑、尾部焊接封口的情况下,可获得截面畸变小、尺寸符合、内表面品质良好的矩形截面L形弯管.聚氨酯橡胶作为芯棒的弯管弯头部分出现了内凹现象,轴承滚珠作为芯棒的弯管虽然外表面品质良好,但内表面却出现了很多压痕.%U-shape tubes are necessary for fusion experimental reactor. However, it is difficult to form this kind of the tubes. Thus we research on the push-bending process for L-shape tube of rectangular section which is the half of the U-shape tube. Three kinds of mandrel: low melting poinalloy.ball bearings and urethane are used in the push bending process to prevent the blank from wrink ling. The experimental results indicate that the low melting point alloy mandrel is adopted in the case of the blank surface lubrication and tube end welding to obtain low section distortion, suitable geometry and good quality internal surface and when the urethane mandrel is used, wrinkling occurs at the tube elbow, and the bearing balls mandrel can be used to obtain good quality in the geome try, but indentation occurs on the internal surface.
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