Research On Statistical Process Control In NC Machining

As the developing of modern manufacturing, there will be higher requierment for part machining quality. But, such factors as machine tools, tool, and conditions cause machining accuracy of part not meeting dimension requirement in large batch NC machining. The problems of dimensional accuracy of machined part usually occur after being checked. This checking strategy is post check and waste products can't avoid, so it's uneconomic. In order to change accuracy control from passive post check into active in-course beforehand prevention, systemic research on how to introduce inner statistical process control (SPC) into NC system to control part machining accuracy is carried out in this thesis. The main works are as follows:(1)The background of Statistical Process Control (SPC) and its development is analyzed in detail. Then the research in this thesis is proposed basing on problems existing in NC machining accuracy.(2)The analysis of user's needs is introduced in the thesis and functional configuration is designed. Environment and operating platform needed for development is analyzed also. Then feasibility of introducing SPC into NC system is studied.(3)The whole process of development and realization, including interface design, menu generation, control charts realization, is described. And economical Control over part machining accuracy employing SPC is realized on HNC-21T lathe NC system of Huazhong CNC. Also, turning motor shaft is presented as an example to verify the feasibility of achievement reached in this thesis. Finally, an applied example of this system is given, and an error analysis of its results is are next carried out.Finally, the work has been done is generalized, and further improvement required in the future is given according to problems occurred during the course of development.