润滑条件对不锈钢管材推弯成形质量的影响

Influence of lubrication condition on forming quality of push-bending stainless steel tubes

基于MSC.MARC有限元软件建立了推弯成形有限元模型,采用实验与数值模拟相结合的方法研究了不锈钢管材推弯成形工艺过程。结果表明:在管材内、外侧壁厚与应力分布规律方面,有限元模拟和实验研究的结果一致,且外侧脊线的残余压应力随所处位置角度的增加而先增加后减小,在一定位置又再次增加,验证了模型的可靠性。通过研究不同摩擦系数与润滑条件下管材内、外侧壁厚与椭圆度的变化规律,得到润滑条件对推弯成形质量的影响。研究表明,在一定范围内,管材外侧壁的壁厚减薄量随着摩擦系数的增加而减小,但是内侧壁壁厚增厚则随着摩擦系数的增加而加剧,管材端面椭圆度随摩擦系数的增加而略有减小。在大弯曲半径推弯时,良好的润滑条件有利于减轻内侧壁增厚问题且能获得更好的成形质量。

The finite element model of push-bending for stainless steel tubes was set up based on software MSC. MARC,and its process was studied by combining experiment with finite element（ FE）. The results show that the experiment results are consistent with the simulation results both in the wall thickness and the stress distribution,and the residual compressive stress at the extrados of tube increases firstly,then decreases with increase of the angle of location,subsequently increases again at a certain location,so the reliability of established FE-model is verified. Furthermore,the influences of lubrication on the push-bending quality were obtained by research on the regulation of wall thickness and the ovality under different friction coefficients and lubricating conditions. The research results also show that the exterior wall thickness thinning rate decreases with increase of the friction coefficient at a certain degree,but the interior wall thickness thickening rate increases,and the ovality of the tube end face decreases slightly. However,when the tubes are push-bent at a large radius,a good lubricating condition can reduce the wall thickening problem at the intrados and ensure a better forming quality.