The Study of the Effect of Pre-Existing Residual Stress in Rough Hard Turning on New Residual Stress in Dry SuperfinishHard Turning

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9612022 Liu Hard turning is an attractive alternative to the conventional precision machining practice of forming, turning, hardening, grinding and superfinishing, because several process steps can be eliminated. However, achieving this attractive result has been limited by lack of knowledge and the risk of thermal damage and residual stresses. This project's objectives are to understand and model: how pre-existing residual stresses affect subsequent residual stresses and chip formation, and how cutting conditions and the ratio of feed to depth of cut affect residual stresses. This investigation will involve both mathematical modeling and experiment. An experimental design matrix, replicated twice, will be used to assess the effects of 3 levels of flank wear, 2 feeds, two depths of cut, 2 cutting speeds and 2 tool nose radii. X-ray diffraction will be used to measure residual stress, and the experimental method of Tay et. al. used to determine temperature distributions. This will be complemented by a modeling effort using the finite element method to predict residual stresses based on a thermal-mechanical model of machining. Success in this project potentially eliminates lengthy and costly operations like finish grinding and superfinishing, in the production of precision components like bearings. This means higher productivity while maintaining quality.