Influence of Die Surface Topography and Lubrication on the Product Quality during Indirect Extrusion of Copper-Clad Aluminum Rods
Influence of Die Surface Topography and Lubrication on the Product Quality during Indirect Extrusion of Copper-Clad Aluminum Rods
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DOI：
10.3390/met10070888
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发表时间：
2020-07-01
期刊：
影响因子：
2.9
通讯作者：
Mueller, Soeren
中科院分区：
文献类型：
--
作者：
Kuhnke, Stefan;Gensch, Felix;Mueller, Soeren
铜包铝杆通常采用静液挤压法制造，因为在直接和间接挤压过程中，铜套断裂是难以避免的。在本研究中，采用不同的模具表面形貌与润滑条件，以改善铜包铝杆间接挤压时的材料流动。因此，圆锥模具与不同的粗糙度（抛光和喷砂）和表面形状（细和粗槽）进行了测试。此外，蜡石墨基润滑剂以及类石墨碳（GLC）涂层的模具圆锥表面的影响进行了研究。复合坯料由铝EN AW-1080 A芯和铜CW 004 A套管制成，其等效铜横截面为总坯料横截面的0.24。对于所有试验，选择14.8：1的挤出比和2 α = 90度的锥形模具角。使用330摄氏度的容器和室温的坯料和工具进行非等温挤出试验，以降低流动应力比σ（Cu）/σ（Al）。分析了挤压复合材料棒材的完整性、表面质量、界面完整性和等效铜截面。此外，对套筒-模具接触表面进行目视检查。结果表明，GLC涂层被证明是不合适的，由于缺乏润滑，这会导致累积的套筒断裂和挤压棒上的纵向凹槽。喷砂模具表面和蜡-石墨基润滑剂的组合实现了最佳结果，观察到均匀的材料流动而没有套筒断裂。
Copper-clad aluminum rods are usually fabricated using hydrostatic extrusion, since during direct and indirect extrusion fracture of the copper sleeve is difficult to avoid. In this study, different die surface topographies and lubrication conditions were applied to improve the material flow during indirect extrusion of copper-clad aluminum rods. Thus, conic dies with different roughness (polished and sandblasted) and surfaces shapes (fine and coarse grooves) were tested. Additionally, the effects of a wax-graphite-based lubricant as well as a graphite-like carbon (GLC) coating of the die conic surfaces were investigated. The composite billets were made of aluminum EN AW-1080A cores and copper CW004A sleeves with an equivalent copper cross section of 0.24 of the total billet cross section. For all trials, an extrusion ratio of 14.8:1 and a conic die angle of 2 alpha = 90 degrees were chosen. Non-isothermal extrusion trials were carried out using a container at 330 degrees C and billet and tools at room temperature to reduce the flow stress ratio sigma(Cu)/sigma(Al). The extruded composite rods' integrity, surface quality, interface integrity, and equivalent copper cross section were analyzed. In addition, a visual inspection of the sleeve-die contact surface was performed. The results showed that the GLC coating proved to be unsuitable due to a lack of lubrication, which causes accumulated sleeve fractures and longitudinal grooves on the extruded rods. The best results were achieved with the combination of the sandblasted die surface and the wax-graphite-based lubricant, observing a uniform material flow without sleeve fractures.