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Zhai D.,Tsinghua University | Zhang H.,Tsinghua University | Zhao T.,Tsinghua University | Zhu L.,TONTEC Technology Investment Group Co.
2011 International Conference on Consumer Electronics, Communications and Networks, CECNet 2011 - Proceedings

The machine tool accuracy is comprehensively affected by geometric, thermal, and cutting force-induced errors. A key step in accuracy design and error compensation is error origins analysis. The object of this study is a MCH63 Precision Horizontal Machining Center. Based on the volumetric error model and using the measurement of error origins, the effects of geometric, thermal, and cutting force-induced errors on the volumetric error components are compared. The results can be used to theoretically direct the accuracy design of different error sources and provide experimental data support for error compensation. © 2011 IEEE. Source

Liang R.-J.,Nanjing University of Aeronautics and Astronautics | Ye W.-H.,Nanjing University of Aeronautics and Astronautics | Luo W.,Nanjing University of Aeronautics and Astronautics | Yu H.,TONTEC Technology Investment Group Co. | Yang Q.,TONTEC Technology Investment Group Co.
Journal of Harbin Institute of Technology (New Series)

The grouping and optimization approach to identify the key thermal points on machine tools is studied. To solve the difficulty in grouping because of the high correlated variables from distinct groups, the variables grouping technique is improved. Temperature variables are sorted according to their relativities with the thermal errors. The representative temperature variables are determined by analyzing the variable correlation in sort order and removing the other variables in the same group. Considering the diverse effect of importing the different variables on thermal error model, the method of variable combination optimization is improved. Regression models made up of different combination of representative temperature variables are evaluated by the index of both the determined coefficient and the average residual squares to select the combination of the temperature variables. For the machine tools with complicated structures which need more initial temperature measuring points the improvement is demanded. The improved approach is applied to a precision horizontal machining center to identify the key thermal points. Experimental results show that the proposed approach is capable of avoiding the high correlation among the different groups' variables, effectively reducing the number of the key thermal points without depressing the prediction accuracy of the thermal error model for machine tools. Source

Chu X.,Nanjing University of Aeronautics and Astronautics | Ye W.,Nanjing University of Aeronautics and Astronautics | Yu H.,TONTEC Technology Investment Group Co. | Guan Z.,TONTEC Technology Investment Group Co.
Zhongguo Jixie Gongcheng/China Mechanical Engineering

A multi-level fuzzy comprehensive evaluation model and performance index system of on-line measurement system was established based on the theory of fuzzy. On the basis of test data, fuzzy evaluation matrix was obtained by using normal distribution fuzzification method, and the weight coefficient of each index was determined reasonably. Finally, the fuzzy theory was used to obtain evaluation results of all layers. Taking an on-line measurement system as instance, the feasibility of the evaluation method was demonstrated. Results show that the overall performance of this on-machine measurement system is good, with accuracy margin, and can be used to inspect parts on machine tools. Source

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