直缝埋弧焊管端口扩径变形分析

Deformation analysis for end expanding of longitudinal submerged-arc welded pipe

采用有限元模拟方法,就直缝埋弧焊管端口机械扩径变形过程进行了研究,对直缝埋弧焊管端口机械扩径过程的横断面、纵断面变形特征做了数值模拟。结果表明,沿管材轴向可以将变形状态分为端口变形区、过渡变形区和未变形区,在扩径过程中需要确定合理的扩径长度。端口变形区壁厚减薄,而在管材与模具尾部圆角相切处应变最大,处于相邻两块模具之间的悬空段管材壁厚变化不均匀,切向拉应力最大,壁厚减薄严重,这几处需要防止变形破坏,由此可见变形过程具有十分明显的局部变形特征。对直缝埋弧焊管端口机械扩径的模拟得到了扩径长度、管端壁厚变化等对实际生产有益的结论。

The mechanical end expanding process of the longitudinal submerged-arc welded pipe was studied by means of FEM simulation technology in this paper. The pipe end deformation on both cross section and lengthwise section was also analyzed. Results showed that the deformation could be divided into end deformation zone, transition zone and nondeformation zone in axial direction of the pipe, and a reasonable length of end expanding need to be determined before the expanding process. Pipe thickness in the end deformation zone became thinner and the maximal strain took place in the section where the pipe and die fillet were in tangency. In the section between the two adjacent dies, wall thickness of billet was uneven, tangential tensile stress came up to the maximum and wall thickness reduced seriously. Damage prevention in these locations was necessary. There was an evident feature of local deformation in the pipe end expanding process. Through the simulation of the mechanical end expanding process of the longitudinal submerged-arc welded pipe, some useful conclusions had been obtained, such as appropriate expanding length and the wall thickness changes of the pipe end, which were beneficial to actual production.