四辊预弯与连续滚弯成形的机理与试验分析

Theoretical and experimental analysis of four-roll pre-bending and continuous bending

为提高预弯段的成形精度,建立了侧辊位移量与预弯段成形半径的四辊预弯数值模型。采用有限元软件分析了滚弯变形区应力应变场的演变规律、轧辊与板材间的摩擦力对滚弯成形的影响,以及多道次滚弯成形后,板材表面塑性应变场的变化规律。四辊多道次滚弯试验表明,四辊预弯数值模型和有限元模型的成形半径比试验结果小,误差分别为11.2%和6.3%;板材与轧辊间的摩擦力是导致预弯段成形半径小于连续滚弯段成形半径的重要原因;多道次滚弯加工后,预弯段成形半径相对于连续滚弯段成形半径的误差,由单道次滚弯加工时的7.3%降至1.7%,预弯段的成形精度得到有效提高。

In this study,a four-roll pre-bending numerical model was build to improve the forming accuracy of the pre-bending section of plate after four-roll bending forming.The influence of friction between roll and plate,and the stress and strain in the deformation zone during the roll-bending process were analyzed by using FE simulation.The distribution of plastic strain on the upper surface of plate after multi-pass roll-bending was investigated.The experimental verification of the typical plates for the four-roll bending was conducted.The results show that the formative radius error is 6.3%for FE model and 11.2%for the prebending numerical model,respectively.One of the main reasons for the over bending of pre-bending section is the friction between roll and plate.Compared with single-pass roll-bending,the formative radius error of pre-bending section relative to the continuous bending section is reduced from 6.1%to 1.7% after the multi-pass roll-bending.The forming accuracy of the prebending section is effectively improved.