Thermal Error Analysis And Experimental Research For The Feed Drive System Of Boring And Milling Center

With the development of manufacturing,the numerical control machine tools become high speed and high precision.International scholars had done a lot of research on the processing error of machine tool,and proposed many effective methods.With the improvement of manufacturing level,the geometric error had little impact on machining precision for precision machine tools,then the influence of processing error that was produced by the thermal deformation of machine tool feed system become important,so the far-reaching of the thermal characteristics of feed system become more significance.The object of thesis is doing some research about the thermal characteristics of feed system of TX1600G boring and milling machining cente.Feed system is driven by ball screw nut pair and linear guide,so it could change movement form.Ball screw pair are key components in feed system of CNC machining center,and that will effect transmission and positioning accuracy.The thermal deformation of key components have seriously affect on the machining accuracy.The main task of this thesis is as follows:First of all,according to related literature,The development trend and present situation of thermal characteristics at home and abroad were summarized.Taking TX1600G CNC boring and milling machining center as the research object,the research significance of thesis was expounded.Secondly,the thermal boundary conditions of the ball screw was determined,with the heat transfer and finite element theory.The three-dimensional entity model of ball screw pair was established.With the help of hot-structure analysis by ANSYS,the temperature field model and the thermal deformation of ball screw could be obtained.The mobile thermal was loaded on ball screw pair to simulation the change of the temperature field in this thesis,and the steady state time was determined.The influence of different feed,convection coefficient,hollow screw speed,coolant flow of feed was studied to find the reason how to effect the temperature field and thermal deformation,and the effective measures was summarized to reduce thermal deformation.Again,the temperature and thermal error measurement experiment scheme was drawed up,with temperature sensor and laser interfermeter,then the feed temperature and the thermal deformation of feed system could be obtained.The relationship between the temperature field and thermal deformation in a certain condition was acquired.Simulation results and the experiment results was compared to prove the reliability and correctness of the simulation results.Finally,with simulation results and experiment results,the temperature measurement points were arranged.The temperature measuring point of the best grouping scheme was determined by fuzzy clustering method,with maximum correlation between temperature and the thermal error,the final key temperature measuring point was selected and thermal error model was build.The thermal error compensation model of ball screw was established by mult-variable linear return analysis.The study of this thesis showed that the thermal error compensation technology is more important to improve the machining accuracy and precision.