Error Field Of Gantry Machine Tool Based On The Multi-body System Theory

With the continuous improvement of machining accuracy requirements, the research of machineerror is also increasing in depth. As important parts of the machine error, the study of geometric errorsand thermal errors has become an important way to improve the machining accuracy. This paper is tostudy factors and variation of the error in the gantry machine motion space. The main work is asfollows:Analysis the motion transmission of machine tool and develop its topological structure. Use rigidkinematics and homogeneous coordinate transformation matrix variation to describe the movement ofthe machine and the change rule of coordinate values. At last, develop a comprehensive error modelfor machine geometric errors and thermal errors based on multi-body system theory in the cuttingpoint.Parameter identification of geometric error.Analysis the current multi-line methods which arewidely used for geometric error parameter identification, choose9-line method to identify thegeometric error parameters. Aimed at the ignorance of angular deviation in9-line method, this paperproposes two solutions: deal with the straightness data using a least squares, and introduce anirregular condition that the sum of total errors is zero. In addition, software is developed based onMatlab GUI to achieve geometric error parameter identification, fitting and geometric errorcalculation rapidly.Thermal error model in the motion space of machine tool.Analysis of the structural of the gantryof the machine, and according to the existed ball screw feed system temperature field simulationresults, an assumption is proposed: the heat of each feeding system isn’t interactive. Reduce thethermal error model parameter identification based on the error model of the moving body.Use alinear regression method for the fitting of thermal error parameters and establish the model of thermalerror. Experimental results show that the thermal error model can predict thermal errors with thechange of space variation and temperature field.