The Research On Error Modeling And Compensation Of Large-Scale Five-Axis Linkage Machine Tool

Error compensation is an effective way to improve machining accuracy. The error modeling is the antecedent condition of error identification and compensation. This paper first established the error model of large-scale five-axis machine tools by applying the theory of multi-body system. And then the method of mechanical error identification was investigated. The position error detection is the compulsory project of mechanical error identification. So this paper also have studied on the method of position error detection and compensation, and made the experiment of machine tool. The main findings and conclusions are as follows:(1)The article analyzed the error sources that affected the machining accuracy and the theory of multi-body system kinematics. The moving parts of the machine are equivalent to the typical body of multi-body system. Using homogeneous coordinate’s transformation matrix to describe the relative motion between the bodies. Machine tool is divided into two branches, tool and work piece branches. According to the tool tip position and the being machined point location on the work pieces should be in the same position, making the link of machine tool cutters and work piece branches. The common error model of machine tool was established according the difference of the position vector of tool tip in tool branch and theoretical cutting position in work piece branch of coordinate system of machine body.(2)Error modeling of the large-scale five-axis machine tool in the subject was established. The3-D modeling of the machine tool was established by software Pro/E and the model of axonometric was imported to AutoCAD, in order to describe the overall layout of the machine tool. The movement relationships of gantry, Sliding saddle, Z-sleeves, C-axis part, B-axis, and other parts were analyzed. Establishing the body coordinate system, abstracting a topological structure of the machine tool, using homogeneous coordinates transformation of matrix to descript the adjacent movement, and building the error modeling of the large-scale five-axis machine tool. (3)The error identification theory of translational axis and rotary shaft of machine tool was investigated. The method of error identification of machine tool was been put forward. The position error detection is the compulsory project of mechanical error identification. The principle of laser interferometer to detect positioning errors and straightness errors of machine translation axis and principle of the laser tracker to detect positioning error of machine tool rotary axis were analyzed.(4)Machine tool positioning error compensation method was studied. The main reasons of the machine tool positioning error were analyzed, and the positioning accuracy evaluation criteria were introduced. Common positioning error type of the machine tool and the related method of positioning error compensation were analyzed. The positioning error compensation principle and parameter setting problem about positioning error compensation in Siemens SINUMERIK840Dpl CNC system were analyzed.(5) Y-axis and B-axis position error detection and compensation experiment of machine tool was made and have made deeper analysis of results of former and later compensation experiment. The results showed that the position accuracy of machine have met the design requirements through error compensation.