激光复合织构焊管轧辊成形性能的数值模拟与试验研究

发布时间：2019-01-06 18:05

【摘要】：在板料成形过程中,板料与模具及界面组成的摩擦副的摩擦行为对模具成形性能具有重要影响。辊弯成形属于典型的带状板料成形,带钢与轧辊表面不同区域的摩擦条件存在差异,因此轧辊表面不同区域的摩擦对成形的影响各不相同。理论上轧辊表面存在最优的摩擦特性分布,能够使摩擦条件有利于带钢成形,提高成形件的质量。本文以焊管轧辊为研究对象,通过数值模拟与试验结合的方法,分析带钢与轧辊表面不同接触区域的摩擦对带钢变形的影响规律。在此基础上,通过激光复合织构技术在轧辊表面不同区域进行微织构主动设计制造,期望降低成形过程中带钢边缘纵向塑性应变,提高带钢边缘变形稳定性,以减小成形“鼓包“的几率。首先,本文对焊管的辊弯成形过程进行了初步的理论分析。在此基础上,利用ABAQUS对焊管的辊弯成形过程进行了模拟仿真,揭示了轧辊表面不同区域的摩擦对带钢变形的影响规律,针对带钢边缘纵向变形过大引起的“褶皱”缺陷,以带钢边缘单元等效塑性应变量为优化对象,利用响应曲面法建立边缘等效塑性应变回归方程。据此,对轧辊表面不同区域摩擦系数进行了优化设计,获得了优化的摩擦系数组合。模拟结果表明边缘等效塑性应变得以降低,验证了轧辊表面摩擦对成形的影响具有区域性,验证了在轧辊表面进行激光复合织构来控制带钢边缘纵向塑性应变的可行性。其次,本文利用长脉宽光纤激光系统在轧辊材料上进行了激光复合织构工艺探究研究。通过激光毛化工艺试验,揭示了激光功率和脉宽对毛化形貌尺寸的影响规律,此外,对毛化点材料的硬度和耐磨性进行了验证,结果表明毛化点区域材料的硬度和耐磨性均显著提高。通过激光微造型工艺试验揭示了激光脉宽和功率两个工艺参数对凹腔直径和深度的影响规律,并在此基础上确定了优化的工艺参数范围。最后,根据摩擦系数优化设计方案,对轧辊主影响区进行激光增摩、耐磨毛化处理和激光减摩微造型,实现了对轧辊表面摩擦特性的主动设计与制造。然后,进行了辊弯成形对比试验,验证了激光复合织构的技术效果,试验结果与模拟大致吻合,边缘纵向塑性变形更加均匀,带钢织构侧相对于未织构侧的残余应力有所减小,带钢成形后边缘直线度也有所提高。试验结果表明在轧辊表面实施激光复合织构,能够优化轧辊表面摩擦特性,有效改善带钢辊弯成形工艺。
[Abstract]:In the process of sheet metal forming, the friction behavior of the friction pair composed of sheet metal, die and interface has an important influence on the forming property of die. Roll bending is a typical strip sheet forming, and the friction conditions of different regions between strip steel and roll surface are different, so the influence of friction on forming is different in different regions of roll surface. Theoretically there is an optimal distribution of friction characteristics on the surface of the roll which can make the friction conditions favorable to the strip forming and improve the quality of the forming parts. In this paper, the effects of friction on strip deformation in different contact regions between strip and roll surface are analyzed by means of numerical simulation and test. On this basis, the laser composite texture technology is used to design and manufacture the microtexture in different regions of the roll surface, in order to reduce the longitudinal plastic strain of the strip edge and improve the stability of the strip edge deformation during the forming process. To reduce the forming "drum" probability. Firstly, the roll forming process of welded pipe is analyzed theoretically. On this basis, the roll bending forming process of welded pipe is simulated by ABAQUS, and the influence of friction on strip deformation in different regions of roll surface is revealed, and the "fold" defect caused by excessive longitudinal deformation of strip edge is pointed out. Taking the strip edge element equivalent plastic strain as the optimization object, the response surface method is used to establish the marginal equivalent plastic strain regression equation. Based on this, the friction coefficient of different regions of the roll surface is optimized and the optimized friction coefficient combination is obtained. The simulation results show that the edge equivalent plasticity should be reduced, the influence of friction on the forming is regional, and the feasibility of laser composite texture on the roll surface to control the longitudinal plastic strain of strip edge is verified. Secondly, the laser composite texture technology on roll material is studied by using long pulse width fiber laser system. The influence of laser power and pulse width on the size of the textured surface was revealed by the experiments of laser texturing. In addition, the hardness and wear resistance of the textured point materials were verified. The results show that the hardness and wear resistance of the materials at the point of wool are significantly improved. The influence of laser pulse width and power on the diameter and depth of the cavity is revealed by laser micromolding process test, and the optimized range of process parameters is determined on the basis of the experiment. Finally, according to the optimum design scheme of friction coefficient, the friction characteristics of roller surface are designed and manufactured by laser friction enhancement, abrasion resistance and micro-modeling. Then, a comparative experiment of roll bending forming is carried out to verify the technical effect of laser composite texture. The experimental results are in good agreement with the simulation, the longitudinal plastic deformation of the edge is more uniform, and the residual stress of the strip texture side relative to the unwoven side is reduced. The straightness of the edge of the strip is also improved after forming. The experimental results show that the application of laser composite texture on the roll surface can optimize the friction characteristics of the roll surface and effectively improve the roll bending forming process.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG333.17;TG665

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