中机身蒙皮骨架变曲率截面桁条滚弯精确成形工艺研究

Research on Roll Bending Precision Forming Technology of Variable Curvature Section of Middle Fuselage Skin Frame

为解决C919国产大飞机蒙皮骨架非对称截面桁条的精确成形难题,基于2形及L形型材的2099–T3和T83铝锂合金性能测试评价,获得材料的本构模型和回弹规律。同时提出一种分段式等曲率渐近滚弯新工艺,结合滚弯成形理论分析计算,建立等曲率四轴滚弯有限元模型,并分析了两种型材的滚弯回弹及曲率半径影响因素,模拟结果确定了非对称截面型材的合理滚弯成形工艺参数为:型材与滚轮摩擦系数为0.10~0.12,型材和滚轮之间间隙为0.2 mm,2形型材和L形型材滚弯的左右滚轮极限抬升高度分别为43 mm和30 mm。最终采用分段等曲率渐近滚弯的方法,通过MC4P431IAS数控滚弯机成功生产出合格的变曲率型材,最大间隙值为0.76 mm,成功验证了变曲率滚弯成形方案的可行性和准确性。目前,该研究成果已成功应用于C919中机身蒙皮骨架长桁的滚弯成形生产中。

In order to solve the problem of accurate forming of asymmetric cross-section truss strip of skin frame of C919 domestic large aircraft,the constitutive model and springback law of materials were obtained based on the performance test and evaluation of 2099–T3 and T83 Al–Li alloys with 2–shaped profile and L–shaped profile.At the same time,a new piecewise constant curvature progressive roll bending process is proposed.Combined with the theoretical analysis and calculation of roll bending forming,the finite element model of constant curvature four-axis roll bending is established,and the influence factors of roll bending springback and curvature radius of two types of profiles are analyzed.The simulation results determine the reasonable roll bending process parameters of asymmetric cross-section profiles as follows:the friction coefficient between profile and roller is 0.10–0.12,the clearance between profile and roller is 0.2 mm,and the limit lifting heights of left and right rollers of 2–shaped profile and L–shaped profile are 43 mm and 30 mm,respectively.Finally,the qualified variable curvature profile parts were successfully produced by the MC4P431IAS CNC roll bending machine using the method of piecewise equal curvature asymptotic roll bending,and the roll bending process test verification of variable curvature profile was completed.The maximum clearance value is only 0.76 mm,which successfully verifies the feasibility and accuracy of the variable curvature rolling forming scheme.At present,the research results have been successfully applied to the roll bending production of fuselage skin skeleton truss in large aircraft of C919.