In-situ observation of lubricant flow on laser textured die surface in sheet metal forming
In-situ observation of lubricant flow on laser textured die surface in sheet metal forming
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金属板材成形中激光纹理模具表面润滑剂流动的现场观察
DOI：
10.1016/j.proeng.2017.10.983
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Yang Ming
中科院分区：
文献类型：
--
作者：
Vorholt Jochen;Shimizu Tetsuhide;Kobayashi Hiroyuki;Heinrich Lukas;Flosky Hendrik;Vollertsen Frank;Yang Ming
为了观察金属板料成形过程中的接触界面，研制了采用透明石英玻璃模具和高速摄像的在线观察系统。为了将成形过程中微观织构组织的尺寸参数与摩擦学性能关联起来，对厚度为0.1 mm的不锈钢薄板在拉深过程中进行了现场观察。比较了不同韧窝结构在不同接触状态下的摩擦学行为。利用飞秒/皮秒激光加工技术，获得了直径分别为10、50、100微米的凹陷结构阵列。结果表明，凹坑直径分别为10和50µm的凹模表现出润滑剂从一个凹坑结构向另一个凹坑结构的流动转移，在凹坑内部似乎产生了流体动压，而当凹坑直径为100µm时，润滑剂供应较少。然而，对于凹坑直径为10微米的毛化模具，由于成形过程中产生的磨屑覆盖了凹陷结构，因此具有比50微米凹陷更大的熨平力。根据不同接触状态下的实验结果，结合现场观测结果，讨论了流体动压的产生原理、磨屑的微捕集作用以及微库对润滑剂保持性的影响。
In the present study, to observe the contact interface during sheet metal forming process, in-situ observation system using transparent silica glass dies and high speed recording camera was developed. To correlate the dimensional parameters of micro-textured structures and tribological properties during the forming operation, in-situ observation during ironing process of stainless steel sheet with a thickness of 0.1 mm was performed. Tribological behavior was compared between the different dimple structures under different contact state. Dimple structure arrays with diameters of 10, 50, 100 µm were achieved by using femto-/pico-second laser processing. As results, the textured die with dimple diameters of 10 and 50 µm showed the lubricant flow transferred from one to the other dimple structures, in which hydrodynamic pressure seems to generate inside the dimples, while that of 100 µm indicated the less supply of lubricant. However, for the textured die with a dimple diameter of 10 µm demonstrated higher ironing force than that of 50 µm, due to the coverage of dimple structures by generated wear debris during the forming process. Based on these experimental findings between different contact states, the principle in generation of hydrodynamic pressure, the function of micro-trap for wear debris and the micro-reservoirs effect for lubricant retention depending on the size of dimple structures were discussed by correlating with the in-situ observation results.