随焊冲击碾压控制内高压成形管胀裂机理研究

发布时间：2018-10-12 06:58

【摘要】：随着内高压成形工艺的日益发展,该技术已经在工业上得到了广泛地应用。有缝管件在内高压成形前都需要对管坯纵缝进行焊接,而焊接工艺所产生的焊接残余应力和变形必然会对内高压成形过程产生影响。因此本文拟采用随焊冲击碾压的方法来减小焊接残余应力,解决有缝管在内高压成形过程中焊缝胀裂的问题。本课题首先对304不锈钢薄管焊接进行了实验与有限元分析,试验发现:利用随焊冲击碾压机构,选择合适的焊接参数,焊缝的残余拉伸应力能够显著减小。这为后续通过随焊冲击碾压降低应力来控制内高压管胀裂提供了理论依据。针对无缝管、普通有缝管和随焊冲击碾压管,在焊接后进行了内高压成形模拟的对比试验。重点分析了各种管件在内高压成形过程中的应力应变演变行为。研究结果表明:无缝管在胀形区会产生560 MPa的周向拉伸残余应力且该区域壁厚减薄率为4%。有缝管在内高压成形的过程中冲头的挤压作用可以减小焊缝的轴向残余应力,但其在过渡区均匀化焊接残余应力的能力减弱,在过渡区会产生271 MPa的轴向拉伸残余应力,有缝管在过渡区易发生缩颈而破裂失效。而随焊冲击碾压管在过渡区的轴向拉伸残余应力仅为114 MPa。通过对比无缝管、普通有缝焊接管和随焊冲击碾压管在内高压成形后的应力分布,得出了焊接残余应力对内高压成形的影响规律:轴向焊接残余应力是内高压成形过程中的不利因素,使焊接管在内高压成形后的轴向压缩残余应力变成轴向拉伸残余应力,导致焊接管容易胀裂。而利用随焊冲击碾压能减小焊缝的轴向焊接残余应力,可有效缓解内高压管胀裂趋势。
[Abstract]:With the development of inner-high-pressure forming technology, this technology has been widely used in industry. It is necessary to weld the longitudinal seam of the tube blank before forming the welded tube under high pressure. However, the welding residual stress and deformation produced by the welding process will inevitably affect the forming process of the inner high pressure. In this paper, the method of percussion rolling with welding is proposed to reduce the residual stress of welding and to solve the problem of weld expansion and crack in the process of high pressure forming of welded pipe. The experiment and finite element analysis of 304 stainless steel thin pipe welding are carried out. It is found that the residual tensile stress of weld can be significantly reduced by using impact rolling mechanism with welding and selecting appropriate welding parameters. This provides a theoretical basis for controlling the expansion and cracking of the inner high pressure pipe by reducing the stress by impact rolling with welding. For seamless pipe, common slit tube and impact rolling pipe with welding, the simulation experiments of internal high pressure forming were carried out after welding. The stress and strain evolution behavior of various pipe fittings during internal high pressure forming is analyzed. The results show that the seamless tube produces a circumferential tensile residual stress of 560 MPa in the bulging region and the wall thickness thinning rate of the region is 4. The extrusion action of the punch can reduce the axial residual stress of the weld, but its ability to homogenize the residual stress in the transition zone is weakened, and the axial tensile residual stress of 271 MPa will be produced in the transition zone. The slit pipe is prone to necking and failure in the transition zone. However, the axial tensile residual stress of impact rolled pipe with welding is only 114 MPa. in the transition zone. By comparing the stress distribution of seamless pipe, common seam welded pipe and impact roller compacted pipe with welding after high pressure forming, The influence of welding residual stress on internal high pressure forming is obtained. The axial welding residual stress is the unfavorable factor in the process of internal high pressure forming, which makes the axial compression residual stress of welded pipe changed into axial tensile residual stress. The welded pipe is easy to swell and crack. However, the residual stress of axial welding can be reduced by impact rolling with welding, which can effectively alleviate the expanding and cracking tendency of inner high pressure pipe.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG404;TG39

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