In Sheet Metal Forming (SMF) processes, friction does play an important role. This with respect to the increase of product quality demands and the ability of predicting these processes by for instance finite element simulations. The existing simulation models do not contain an adequate friction model. In SMF processes different contact situations can be distinguished. As a result different coefficients of friction are locally present, which influences the forming process.ududExperiments are performed on a testing device by which it is possible to simulate the operational conditions as present in SMF processes. This test rig is a combination of a tensile tester and a friction measuring device, by which it is possible to measure the coefficient of friction as a function of the operational conditions (velocity and contact pressure) and deformation (elastic or plastic) in a well controlled way. Friction is presented in a generalized Stribeck-curve in which the different lubrication regimes can be distinguished, i.e. Boundary Lubrication (BL) and Mixed Lubrication (ML), which are also occurring during SMF processes.ududIn SMF processes the sheet material deforms elastically and plastically and therefore the surface roughness will change and as a consequence will influence the frictional behavior between sheet and tool. In this paper, the influence of plastic deformation on A) the surface microgeometry and B) as a consequence of that on the frictional behavior of the sheet-tool system is studied. With the aid of a 3D-surface interference microscope, the microgeometry of the deformed material has been analyzed. The result of this investigation is that the CLA-roughness due to the deformation first decreases and then increases with increasing deformation. Furthermore, friction is hardly influenced due to the change in surface roughness. No change in the shape and the level of the generalized Stribeck curve is found.
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机译：在钣金成形（SMF）过程中，摩擦确实起着重要作用。关于产品质量要求的提高以及通过例如有限元模拟来预测这些过程的能力。现有的仿真模型没有足够的摩擦模型。在SMF过程中，可以区分不同的联系情况。结果，局部存在不同的摩擦系数，这会影响成形过程。 ud ud在测试设备上进行实验，通过该设备可以模拟SMF过程中存在的操作条件。该测试台是拉力测试仪和摩擦测量设备的组合，通过该设备可以根据井中的工作条件（速度和接触压力）和变形（弹性或塑料）来测量摩擦系数控制方式。摩擦以广义的Stribeck曲线表示，其中可以区分不同的润滑方式，即边界润滑（BL）和混合润滑（ML），它们也在SMF工艺中发生。 ud ud在SMF工艺中，板材变形弹性和塑性，因此表面粗糙度将发生变化，结果将影响板材与工具之间的摩擦性能。本文研究了塑性变形对A）表面微观几何形状和B）塑性变形对板材工具系统摩擦行为的影响。借助于3D表面干涉显微镜，已分析了变形材料的微观几何形状。研究的结果是，由于变形引起的CLA粗糙度首先减小，然后随着变形的增加而增加。此外，由于表面粗糙度的变化，几乎不影响摩擦。没有发现广义斯特里贝克曲线的形状和水平的变化。
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