It is found that the fracture often occurs on the internal layer metal when the concave die with a cone angle and extrusion die with a mandrel is used to extrude an aluminum-copper clad bimetal tube. A new die structure that has a mandrel with cone angle and a cylindrical concave die is proposed through FEM simulation for extrusion forming of a bimetal lube. The metal tube deformation appearing when the mandrel's cone angle is different is analyzed with Deform-3D software. The cone angle under the extreme condition is analyzed by FEM. The experiment shows that any fracture does nol occur on the aluminum-copper clad bimetal tube and the thickness of tube wall is uniform as cone angle of the mandrel is bigger than 75℃and thickness ratio of internal layer to external layer is 5. 5 : 3. 5. The die structure was designed according to the experiment result.%通过对双金属管材挤压成形的有限元模拟发现:当挤压模凹模带有锥角而芯棒为圆柱体时挤压铜铝双金属管材时常出现内层金属断裂的现象.为了解决这个缺陷通过反向思考提出了芯棒带有锥角而凹模为直筒的特殊的模具结构,并结合有限元软件Deform-3D分析了不同芯棒锥角下金属的变形情况,确定了合适的锥角大小,同时对双金属管材内外管材的厚度比也有限制要求,成功实现了铜铝双金属管件的挤压成形.通过对挤压过程中的芯棒进行强度校核对此挤压模具的结构进行了设计.
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