Thermal Error Analysis And Experimental Research Of Screw Feeding System Of High Speed Drilling And Milling Machining Center

The machine tool industry is an important component of the equipment manufacturing industry,and high-end machine tool products are the embodiment of the country’s comprehensive national strength.With the vigorous development of precision machining technology,the thermal error of CNC machine tools has been paid more and more attention as the main error affecting the machining accuracy of machine tools.The thermal error of the machine tool is mainly caused by the combination of the feed axis system and the thermal deformation of the structural casting,where the thermal deformation of the screw is caused by motion,and the thermal deformation of the casting is caused by heat transfer.In thesis,by analyzing the main reasons for the thermal error of CNC machine tools,taking the Z-axis feed system of the drilling and milling machining center as the research object,and according to the energy conservation principle,a thermal error model of the machine tool based on internal data is established.The influence factors of thermal error are verified by experiments,and the model can reduce the influence of thermal error on machining accuracy.The thermal error model based on internal data is mainly suitable for places with obvious changes in ambient temperature,and has certain limitations.The thermal deformation of the structural casting is included in the influencing factors of the thermal error of the feed system,and the thermal-solid coupling simulation analysis of the feed system is carried out.Finally,the thermal error model of the Z-axis feed system is constructed.The content is as follows:(1)The influence of thermal deformation of structural castings on the thermal error modeling of the feed system.When the Z-axis screw rotates at a high speed,a large amount of heat is generated by friction with the bearing at the head and tail ends of the screw,and part of the heat is transferred to the structural casting,causing thermal deformation,and ultimately causing thermal errors in the machine tool.The temperature field and deformation field of the feed system are studied by simulating the actual installation method of the screw,and the generation and dissipation of heat are calculated to establish the finite element boundary parameters of the feed system.(2)Incorporate the thermal deformation of structural castings into the influencing factors of the thermal error of the machine tool,and then build a thermal error model.The analysis of the thermal deformation of the structural casting and the installation position of the screw shows that the influence of the casting deformation on the positioning error of the machine tool cannot be ignored.The thermal-solid coupling simulation of the Z-axis feed system and the structural casting is carried out,and an error model based on the thermal deformation of the screw is constructed according to the simulation results of the thermal extension of the Z-axis screw.(3)The thermal error model test of the feed system.A temperature sensor and a laser interferometer are used to measure the temperature and positioning accuracy of the feed system respectively,and the obtained experimental data are compared with the simulation results,which verifies that the thermal error model is more accurate.There are 54 figures,15 tables,and 52 references.