Measurement and Modeling of Rotary Table geometric errors in CNC 4-axis Machine Tool

Error compensation using software methods is an effective and low-cost solution for increasing machining accuracy in CNC machine tools. In research, the main goals are to develop a method for measuring geometric error, modeling and geometric error compensation for the Rotary table of a 4-axis machine tools by implementing Homogeneous Transformation Matrix (HTM) method. After designing parametric-error model, empirical data is experimentally obtained, required for calculating unknown parameters of the model. Then, data measurement tests were carried out by a BallBar Measurement mechanism according to ISO 230-7 standard on the four-axis CNC milling machine. BallBar mechanism can measure the movement deviations of a constant radius circular path for different directions.After substituting experimental data in the proposed error model, by using matrix and computational relations the complete error model of the process is achieved. Finally, geometric errors for different angles of the rotary table are extracted from the error model and presented. Among achievements of this research, the new error model and the method of verification could be mentioned. Based on the validated model, compensations on the tool path can be carried out in order to reach higher accuracy. In addition, the error compensation method used for equipment installation,and the type of movement selected for BallBar mechanism on the 4-axis machine tool, will elevate the precision and accuracy of results. From the innovative outcomes of the present study, optimum error model and its validation to investigate the consistency of the results in both empirical and theoretical approaches is absolutely worth mentioning.