Study On Thermal-mechanical Coupling Dynamic Modeling, Analysis And Optimization Methods For The Feed System Of Gantry Machine Tool

With the booming of China’s aerospace, shipbuilding and marine engineering, large metallurgicalmachinery, energy equipment, automobile industry, etc., the demand of large and complexcomponents is increasing, which contributes to the development of gantry machine tools. As animportant component of gantry machine tool, the dynamic performance of feed system greatlyinfluences the machining accuracy of the gantry machine tool, which has become a research emphasisand difficulty in machine tool design area. The feed system is affected by the thermal-mechanicalcoupling effect from the joint action of heat and force during the working process of gantry machinetool, which leads to deformation and vibration of feed system. Nevertheless, existing methods used inanalyzing and designing of the feed system focus on improving the mechanical performance orthermal performance only, which makes it hard to improve the overall performance of feed system.To solve the above problems, on basis of studying gantry machine tool feed system’sthermal-mechanical coupling mechanism, some new methodologies were proposed in this paper,which are the thermal-mechanical coupling dynamic modeling method, dynamic analysis method andmulti-objective optimization design method for gantry machine tool feed system. The correctness andeffectiveness of the proposed methodologies were verified by comparing the results oftheoretical analysis and experiments on prototype of gantry machine tool’s feed system in a factory.The main research work and achievements are as follows(1) Through considering that the gantry machine tool feed system is affected by joint action ofheat and force during the working process, a dynamic modeling method was proposed, which is basedon the coupling effect of the temperature field and kinetic properties. By exploring thethermal-mechanical coupling mechanism of gantry machine tool feed system, a thermal-mechanicalcoupling dynamic model of the gantry machine tool feed system was established, which was solvedthrough using the central difference method and the matrix iterative method. The correctness of thegantry machine tool feed system’s dynamic modeling method was verified by comparing thetheoretical analysis results with experimental results.(2) Through studying the law of thermal–mechanical coupling effect on gantry machine tool feedsystem’s dynamic performance, and a thermal–mechanical coupling dynamic analysis method wasproposed by combining multi-step finite element simulation with temperature field experiment.According to the method proposed, thermal–mechanical coupling transient and steady-state analysison gantry machine tool feed system were conducted and conclusions obtained are as follows, before the whole feed system reaches thermal balance state, the vibration amplitude of the feed systemincreases with the temperature rising, which leads to the intensifying of vibration. Therefore, in theprocess of gantry machine tool feed system’s analysis and design, the influence ofthermal–mechanical coupling on dynamic performance must be considered.(3) In order to study the dynamic performance of gantry machine tool feed system more fully, aanalysis method of structural parameters affecting the dynamic performance dynamic was proposed,which is based on the thermal-mechanical coupling. During the thermal-mechanical coupling steadystate of gantry machine tool feed system, the above proposed method was introduced to study theimpact law of the various structural parameters on its dynamic performance, and identify thestructural parameters that have great influence on the dynamic performance. The study results showthat the carriage’s mass and anti-vibration performance has great influence on the dynamicperformance of gantry machine tool feed system.(4) A multi-objective optimization design method was proposed through considering the gantrymachine tool feed system’s thermal–mechanical coupling effect and dynamic performance. Themethod uses the orthogonal experimental method and the second-order response surface method toestablish the approximate optimization model. An improved particle swarm algorithm and greyrelational analysis method are taken as the solving method. After using the proposed method toconduct multi-objective optimization design for the feed system’s carriage, the carriage’s massdecreases, thermal–mechanical coupling performance is improved, and the first order naturalfrequencies increase greatly. Finally, the correctness of multi-objective optimization design methodproposed in this paper was verified by the static and dynamic experiments.