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棒材同轴复合时芯材与加工工具不接触,其横截面形状及尺寸精度控制难度大,采用方-椭圆孔型轧制时芯材圆度严重超公差。在建立覆材和芯材变形抗力模型的基础上,利用三维弹塑性热力耦合有限元方法对同轴复合棒材热轧变形过程进行数值模拟。分析了轧制孔型、覆材及芯材外形对轧制后芯材变形和形状的影响,用工业试验对模拟计算结果进行验证。结果表明:轧辊孔型设计对芯材不圆度的影响最明显,覆材及芯材外形是次要影响因素。这是因为方-椭圆孔型系统会导致最终轧件在横截面上的非对称等效累积应变分布,以及导致轧后芯材严重不圆。减少K4孔的轧件压下量,增加K3孔轧件压下量,可以改善方-椭圆孔型中轧件变形的对称性,减少芯材不圆度。
Coaxial composite rod core materials and processing tools do not touch, the cross-sectional shape and dimensional accuracy of control difficult, the use of square - oval-shaped core roundness severe over tolerance. Based on the model of cladding material and core material deformation resistance, the three-dimensional elastic-plastic FEM was used to simulate the hot-rolling deformation of the composite rod. The influence of rolling pass, cladding material and core shape on the deformation and shape of core material after rolling was analyzed. The simulation results were verified by the industrial test. The results show that the influence of roller hole design on the out-of-roundness of the core is the most obvious, and the overlay and the core shape are the secondary factors. This is because the square-oval hole system results in an asymmetric cumulative cumulative strain distribution of the final rolled product in the cross-section and a serious non-roundness of the core material after rolling. Reducing the rolling reduction of K4 hole and increasing the reduction of K3 hole rolling can improve the symmetry of the rolling deformation in the square-oval hole and reduce the non-circularity of the core.