拼焊板盒形件冲压成形失效及应变路径分析

采用自制液压机和分瓣压边圈模具,通过模拟仿真和实冲试验,变化各工艺参数,研究分析拼焊板方盒件冲压成形的应变路径、焊缝移动和成形极限,以提高其成形性能。研究表明,厚/薄侧压边力的大小和分布对破裂危险点的应变路径和成形裕度有很大的影响,合理的压边力分布可调节失效破裂的位置,减少焊缝移动和提高成形极限深度;凹模圆角半径的增大,对薄侧侧壁圆角处破裂危险点应变路径影响较大,拼焊板盒形件成形极限深度逐渐增大;厚度比较小时,破裂出现在薄侧圆角处,而厚度比较大时,焊缝移动量大,破裂易出现在薄侧焊缝处;板料毛坯形状和尺寸对失效破裂的位置和成形性能影响显著。因此,以薄侧侧壁圆角处和薄侧焊缝位置附近为破裂危险点,通过优化压边力、凹模圆角半径、板料厚度比、板料毛坯形状和尺寸等工艺参数,改变危险点的应变路径,调节失效破裂的位置,减小其焊缝移动量,可有效地提高拼焊板方盒件的冲压成形性能。

Analysis of forming of tailor welded blanks square box based on strain path

For tailor-welded blanks(TWBs) square box,adopted the self-made hydrostatic press and the square box mould with split binder,the forming strain path,the welded-line movement and the forming limit depth were analyzed by the numerical simulation and the stamping experiment with various technological parameters.The results mainly show that the value and distribution of thick/thin blank holder force have significant influence on the forming strain path in the fracture dangerous position and the formability,and the proper distribution of blank holder force can adjust the fracture site,reduce the welded-line movement and increase the formability;that the larger is the corner radius of die,the higher is the formability of TWBs square box;that the fracture occurs to the round angle of thin material for the lower thickness ratio,the fracture appears in the thin material near the welded seam of the box bottom for the greater movement of welded seam of the higher thickness ratio;that the size and shape of TWBs have significant influence on the fracture site and the formability.To sum up,for tailor-welded blanks(TWBs) square box,the thin material near the welded seam of the box bottom and the round angle the side wall in thin material are considered as the fracture dangerous positions,and the technological parameters are optimized which are the value and distribution of thick/thin blank holder force,the corner radius of die,the thickness ratio,the size and shape of TWBs,so that the formability can be increased by altering the forming strain path,adjusting the fracture site and reducing the welded-line movement.