在弯曲过程中,冲压力超过了金属的弹性极限,但并未超过其强度极限。因此,当上下模吻合时,即冲程位于下止点时,工件材料还存有一些固有弹性。由于这一原因,凸模(随冲床滑块)上升后,弯曲工件上材料受压缩的一面便略为伸长,而受拉伸的一面则略为收缩。这一伸一缩,便形成了工件恢复到其原来形状的趋势,使得弯曲角稍为弹 In the bending process, the punch force exceeds the elastic limit of the metal, but does not exceed its strength limit. Therefore, when the upper and lower mold coincide, that is, the stroke at the bottom dead center, the workpiece material also has some inherent elasticity. For this reason, as the punch (with the punch press) rises, the material being compressed on the bent workpiece is slightly elongated while the stretched side slightly contracts. This stretch reduces the tendency of the workpiece to return to its original shape, making the bending angle a little easier