Different contact surface parameters and operating characteristics are observed during the deep drawing process. It is not possible to find a formulation that can be used for all lubrication regimes. Therefore, several friction models have been developed in order to overcome this problem. In this study, a math program is developed which combines Wilson&rsquo / s and Khonsari&rsquo / s friction models in a new model in order to increase accuracy and efficiency in friction calculations. By comparing the results of both friction models, the film thickness ratio of 0.035 is introduced for 0.15 &mu / m standard deviation of surface summits. Below the ratio of 0.035, Khonsari&rsquo / s model gives more accurate results since asperity friction is dominant and the model is based on asperity contact. Above the ratio of 0.035, Wilson&rsquo / s model gives more accurate results since hydrodynamic friction is dominant and the model is based on lubricant flow.
In this study, a finite element program is used to simulate 50 mm cylindrical and 50.5x50.5 mm square shallow drawing processes which are performed in single stage. The final cup depths are selected as 18 mm and 23 mm for square and cylindrical cup drawing respectively. The FEM model and the program codes developed are verified by the previous studies in literature. After verification, the simulation results of the cylindrical and square cup drawing are input to a math program which calculates local friction coefficients using the combined friction model. Finally, the combined friction model and the results are further discussed.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613686/index.pdf |
| Date | 01 September 2011 |
| Creators | Baspinar, Murat |
| Contributors | Akkok, Metin |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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