Thermal Modal Analysis And Experiment Research Of CNC Machine Tool

According to the modern dynamic theory,the modal parameters of the machine tool structure are fixed.However,in recent years,scholars at home and abroad have found that the modal parameters of CNC machine tools will change with the change of operating temperature.The dynamic characteristics of the machine tool structure system,the thermal characteristics of each part of the machine tool and the surface quality of the workpiece will have obvious influence.However,the research on the mechanism of the influence of temperature variation on the dynamic characteristics of the machine tool is still not fully understood.This paper through the NC machine tool components of response and response analysis,combined with the static analysis method and table tapping operation modal empty running self excitation method,explore the modal parameters of CNC machine tools under the influence of the temperature evolution.Then using ODS modal analysis method solve the main vibration mode of machine tool structure.According to the change degree of the main vibration mode in the temperature,the thermal sensitive part of the numerical control machine tool is determined.The relationship between the temperature change and the modal response characteristics of the whole structure is established,and the effect of temperature variation on the dynamic characteristics of the machine tool is revealed.The main contents of this paper are as follows:First of all,based on the simplified method of general structural dynamics,the thermal system of the CNC machine tool is simplified as a linear time variant system.Feasibility of real time verification of synchronous acquisition of acceleration signal and temperature signal.The working condition of the machine tool heating is selected by the hammering method and the working table empty running method.At the same time,the change of the modal parameters under the response of the whole NC machine tool is explored.Secondly,after the study of the whole machine,taking into account the different positions of the thermal load may not be the same.Therefore,the acquisition of the response signal components XYZ three direction sum up for analysis.Because of the different thermal loads,the modal parameters of the limit positions vary greatly from that of the whole machine.Finally,based on the above results,it is found that the response analysis of response or component.The modal parameters of the machine are changed with the temperature,but there is no rule to follow.Using ODS modal analysis method to determine the main vibration mode of CNC machine tools,and then according to the change of the main vibration mode,the distribution of thermal sensitive parts of the machine tool is analyzed.