Research And Application Of Thermal Deformation Model Of Machine Tool Based On Internal Data

In 3C,mold and other industries,small drilling and tapping centers can consecutively complete a variety of processes in a fast-paced manner,shortening the production cycle.But the machining characteristics of high-speed,high-frequency tool-changing operations and high-speed spindle brings large thermal deformation problem at the same time,especially the screw of Z-axis and spindle.In order to solve the above problems,this paper takes the small drill center TD-500 A as the research object,and studies the thermal deformation prediction models of screw and spindle based on the ambient temperature and internal data.The method of using temperature sensors to establish predictive model has a high cost;the other method of using a tool-checking instrument to correct the tool length during processing reduces the machining efficiency;making the thermal deformation of the machine tool is in a balanced state results in the waste of resource.For the Z-axis screw,according to the principle of energy conservation,a multiple linear regression model was established based on the internal data of the machining process and the ambient temperature,and compared with the feed-forward neural network model.By analyzing of the screw installation method,a thermal deformation model related to the screw position was established.Finally,experiments were designed to calibrate and verify the model.The results showed that the multiple linear regression model related to the screw position reduced the thermal deformation from 0.08 mm to 0.01 mm.For the spindle,this paper first studied the relationship between the thermal deformation of the spindle and the working mode and load current,determined the source and dissipation of heat by analyzing the structure of the spindle system,and then according to the principle of energy conservation and the derivation of the heat transfer,based on the environment temperature and internal data,a thermal deformation prediction model of the spindle was established.Finally,experiments were designed to calibrate and verify the model.The results showed that the thermal deformation of the spindle is reduced from 0.08 mm to 0.02 mm.Finally,experiments verified that the Z-direction thermal deformation of CNC machine tools is a superposition of the thermal deformation of the Z-axis screw and the spindle.Thus,the Z-direction thermal deformation of the machine tool is predicted using the screw and spindle model established above.Results showed that the model reduced the thermal deformation in the Z direction from 0.11 mm to 0.02 mm in the case of simultaneous movement of the Z-axis and the spindle.