薄壁管小弯曲半径数控绕弯成形芯模效用的实验研究

薄壁管数控弯曲中带芯头的柔性芯模是提高薄壁管件成形极限和成形精度的关键因素。文章建立了绕弯过程芯模(包括芯棒和芯头)的理论解析模型,包括了芯模直径d、芯棒伸出量e、芯头个数n、芯头厚度k、芯棒/芯头孔心间距p及芯棒圆角半径r等参数的选取公式的推导,获得了不同弯曲规格下的芯模参数取值范围,验证了解析模型的合理性;实验研究了芯模参数对管材失稳起皱、壁厚减薄和截面畸变的影响规律。通过分段抽芯的工艺方法,完成了38mm×1mm×38mm(1D)高难度不锈钢管件的弯曲。

Experimental study on role of mandrel in thin-walled tube NC bending process with small bending radius

The mandrel(including flexible balls) is the key to improving the forming limit and forming precision in thin-walled tube NC bending process.In the study,one analytical model of mandrel(including mandrel shank and balls) has been developed and reference formulas have been deduced in order to select the mandrel parameters preliminarily.i.e.mandrel diameter d,mandrel extension e,number of balls n,balls thickness k,space length between balls p and nose radius r.The experiment has been carried out to verify the analytical model.Then the influence laws of mandrel parameters on wrinkling insatiability,wall thickness change and cross section distortion degree are investigated by experiment.The stepped retraction method is used to form the high difficult stainless steel tube with 38mm×1mm×38mm(1D).