Research On Sensor Placement Optimization And New Temperature Measurement System Of CNC Machine Tools

The main research theme of this dissertation is sensor placement optimization and temperature measurement system in thermal error compensation of machine tools. Based on fully understanding and deeply analyzing the current status of the research and application of the thermal error compensation technique for CNC machine tools, some new theories and techniques are studied, some new methods are used to make the optimization of the sensor location in the thermal error modeling. We also developed an embedded numerical temperature measurement system for measuring the temperature field of machine tools.In chapter 1, the background and the significance of the research are stated. The research history and present status of the thermal error modeling and the sensor location optimization are also provided. Then the development and application of temperature measure technology and temperature sensor are introduced. The main content of the dissertation is presented.In chapter 2, analysis the thermal dynamic process of machine tools .The temperature model, the thermal deformation model and the thermal error of CNC machine tools are studied by the FEA method and the model analysis method. The problems on the thermal deformation model are solved by studying and analyzing the similarity between the vibration model and the thermal model. Establish the base for the future research of sensor location optimization in thermal error modeling.In chapter 3, by analyzing the dynamic characteristics of the temperature field and thermal deformation in the spindle model, an optimized sensor location is found where the thermal deformation is linear and synchronized with the change of temperature. Proposed the research method of the sensor location optimized and which is helpful to improve the efficiency of the sensor location selection.In chapter 4, mainly talk about the development of embedded numerical temperature measurement system. Firstly of all is to introduce the general design for our system. We introduce the main parts of the system at the basis of an analysis to the system function. A general framework model is given. Then, the hardware design of the system is presented. We introduce S3C44BOX and the detail characteristics of DS18B20. Last is the software design, base on analyze the module functions of the software, we match the time sequence of DS18B20 and make it communicate with the master.In chapter 5, synthesizes experiment of Temperature-Thermal Error is introduced. Use the sensor location optimization method to place temperature on CK6140 CNC lathe. The temperature field of the lathe is measured by using the temperature system that we developed of 16 sensors and the thermal error is measured by using laser CCD displacement sensor. By analysis the temperature variable and thermal error variable a thermal error models are given. At last, we only use 4sensor without the great loss of the accuracy of the models.In chapter 6, the study contents and conclusion of the dissertation have been summarized, and point out the exception of the future research.