工艺参数对连续变断面圆柱体镦粗变形特征的影响

Effects of processing parameters on deformation characteristics of continuous variable cross-section cylinder in upsetting

采用一种大塑性变形方法-连续变断面循环挤压法,研究材料在镦粗工序时的变形特征及金属流动规律,并就改善镦粗时的鼓形、失稳折叠现象进行理论分析。研究表明,沿着高向(轴向),材料由上向下依次变形,且直径增大幅度和厚度减小幅度均从上到下依次减小,是一种不均匀变形;面积增大是由于金属质点沿径向流动和侧面翻平叠加的结果。而镦粗工序就是利用这种设定的不均匀变形方法的"时空"特点,改善和消除圆柱体镦粗时产生鼓形及失稳折叠的不均匀变形。

Metal materials were deformed by a new severe plastic deformation method of continuous variable cross-section recycled extrusion(CVCE).The deformation characteristics and metal flowing law in upsetting process for the metal specimens were investigated.Based on theory analysis,the reasons for the improvement of the drum-shaped and buckling as well as folding phenomena for the specimens in the upsetting process were discussed.The results show that the materials is deformed gradually from the upper to the lower along the height,and the enhancement amplitude of diameter and the reducing amount of thickness are all decreased gradually from the upper to the lower,which is an inhomogeneous deformation.The reason for increasing area is the combined effects of both the metal particle flowing along the radial and its flipping along the height.The non-uniform deformation characteristics of the contituous variable cross-section cylinder is utilized to improve and eliminate inhomogeneous deformation including the drum-shaped and buckling as well as folding of the metal marerials in the upsetting process.