| Under the condition of the high speed and high precision machining,the influence of thermal deformation on machining accuracy of precision and ultra precision machine tools is increasing.However,due to the complexity of machine tool structure and processing environment,the thermal error could not be measured in machine working space,and even the thermal deformation error of machine tool structure could not be measured directly in any direction.How to quickly and accurately get the key parts of the machine tools thermal deformation is particularly important.A method of structural thermal deformation orthogonal coupling modeling was proposed in this paper.Based on CAE thermal analysis,the modeling method was applied to the thermal deformation error modeling of the precision horizontal machining center.Furthermore,the thermal error model of the working space in the horizontal machining center was deduced by using multi body theory.The main contents of this paper are as follows:Based on systematically studying the bending deformation law of cantilever beam and simply supported beam structure under the action of force load and thermal load,a method of structural thermal deformation orthogonal coupling modeling was proposed.In this method,a mapping model between the length direction and its orthogonal direction of the basic beam structure was established under the action of thermal load.By analyzing the thermal deformation of precision horizontal machining center,the thermal deformation law of machine tool structure under different thermal conditions was studied.Based on the method of structural thermal deformation orthogonal coupling modeling,the thermal deformation model of three linear motion axes of the machine tool was established by the thermal deformation simulation analysis results of the bed,column and moving column.And the thermal deformation of the guiderails obtained by the thermal deformation simulation of the machine tool structure was used to verify the credibility of the thermal deformation of the machine tool guiderails obtained by the model.At the same time,the influence rule of the change of measuring point on the precision of the model was analyzed.Based on the thermal deformation model of the guiderails obtained by the orthogonal coupling modeling method,the thermal error model of the working space of the horizontal machining center was established by using the multi body theory,considering the positional correlation of the thermal deformation error of the guiderails.The results of this paper provide a new idea for the thermal deformation error modeling.Through this method,the thermal error of the working space can be obtained by measuring the thermal deformation of the machine tool structure under the working condition.It is of great significance to evaluate and improve the thermal characteristics of the machine tool during operation and to control and compensate the thermal deformation error of machine tool. |
