一、前言承受轴向压缩的管材,当应力超过比例极限时,会产生纵向弯曲。若其细长比大,则管子象立柱那样产生横向挠曲纵弯曲变形;而当细长比小时,则产生局部纵向弯曲变形。当低碳钢,铜合金及铝合金等管材的径壁比在50以下时,则细长比小的管材会产生轴向对称的胀形成形。因此,利用这种纵向弯曲变形,能容易地实现胀形成形。但是,必须注意到这只适用于纵弯曲弧长成形;而非纵弯曲段的 First, the forehead Axial compression of the pipe, when the stress exceeds the limit, it will have a longitudinal bend. If the slenderness ratio is large, the tube will produce lateral flexural longitudinal bending deformation like a column, while when the slenderness ratio is small, local longitudinal bending deformation will occur. When the wall ratio of low carbon steel, copper alloy and aluminum alloy pipe is below 50, then the pipe with small slenderness will produce axial symmetrical bulging shape. Therefore, with such longitudinal bending deformation, bulge forming can be easily achieved. However, it must be noted that this applies only to the shape of the curved longitudinal arc; rather than the longitudinal curved section