Loading path design of thin-walled aluminum alloy T-shaped tube hydroforming process based on the control of limit pressure
Loading path design of thin-walled aluminum alloy T-shaped tube hydroforming process based on the control of limit pressure
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DOI：
10.1007/s00170-020-05526-0
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发表时间：
2020-06-16
影响因子：
3.4
通讯作者：
Wei, Liming
中科院分区：
文献类型：
--
作者：
Wang, Lei;Xu, Xuefeng;Wei, Liming
由于压力控制精度的影响，管材在液压成形过程中的实际压力往往大于设计压力，从而导致管材断裂。设计了基于极限压力控制的T形管液压成形加载路径。首先，在T形管无进给液压成形过程中，通过提高内压直到管破裂的极限压力P(Max)，建立了预测瞬时压力的理论模型。其次，利用溢流阀设定溢流压力，通过手动操作液压成形机的进给量和最大进给量来确定管材鼓包高度(Max)和最大进给量D(Max)；最后，在T形管液压成形实验中，分别设置最大压力(Max)、最大进给量和溢流压力(等于内压)，采用梯形生长法和线性生长法设计了内压和进给量的加载路径。结果表明，通过溢流阀的作用，得到的极限压力P(Max)可以避免管道的超压，抑制管道的断裂。同时，通过实验验证了预测模型计算UPP(Max)的准确性：所建立模型的理论预测值与实验真实值基本一致。与直线加载路径成形的T形管相比，阶梯加载路径成形的T形管壁厚分布更均匀，没有起皱和断裂，成形的支管高度接近h(Max)。同时发现，在差动润滑管坯下，获得合适加载路径的时间明显减少，梯形方式的配置更简单、更高效。
Due to the influence of pressure control precision, the actual pressure in hydroforming process for the tube is usually greater than the design pressure, which causes the fracture of tube. The loading path of T-shaped tube hydroforming process was designed based on the control of limit pressure. First, the limit pressure of tubeP(max)was obtained by improving the internal pressure until the tube cracked in the T-shaped tube hydroforming process without the feeding and a theoretical model for predicting instantaneous pressure is developed. Second, the tube bulge heightH(max)and the maximum feedingD(max)were explored through manual operation of feeding and pressure in hydroforming machine, in which the overflow pressure is set toP(max)by using an overflow valve; finally, the loading path of internal pressure and feeding was designed using the ladder growth and linear growth in T-shaped tube hydroforming experiment in which the maximum pressure, the maximum feeding, and the overflow pressure (equal to internal pressure) were set toP(max),D-max, andP(max), respectively. The results show that the obtained limit pressureP(max)can avoid the overpressure of the tube and restrain the fracture of the tube through the action of the overflow valve. Meanwhile, the accuracy of the prediction model to figure upP(max)was verified through experiments: the theoretical prediction value of the established model was consistent with the experimental true value. Compared with the T-shaped tube formed by linear loading path, the wall thickness of the formed T-shaped tube by ladder loading path is more evenly distributed without wrinkles and fractures and the height of the formed branch tube close toH(max). At the same time, it is found that under the differential lubrication tube blank, the time of obtaining a suitable loading path is significantly reduced, and the collocation of ladder mode is simpler and more efficient.