Accurate identification and compensation of geometric errors of 5-axis CNC machine tools using double ball bar

Abstract

Five-axis CNC machine tools are widely used in manufacturing of parts with free-form surfaces. Geometric errors of machine tools have significant effects on the quality of manufactured parts. This research focuses on development of a new method to accurately identify geometric errors of 5-axis CNC machines, especially the errors due to rotary axes, using the magnetic double ball bar. A theoretical model for identification of geometric errors is provided. In this model, both position-independent errors and position-dependent errors are considered as the error sources. This model is simplified by identification and removal of the correlated and insignificant error sources of the machine. Insignificant error sources are identified using the sensitivity analysis technique. Simulation results reveal that the simplified error identification model can result in more accurate estimations of the error parameters. Experiments on a 5-axis CNC machine tool also demonstrate significant reduction in the volumetric error after error compensation.

Tool path re-planning in free-form surface machining for compensation of process-related errors

“…These errors at each CC point of the finishing process are shown in Figure 10(b) and (c). On the other hand, the geometric errors of the machine tool were identified using the method developed by Lasemi, Xue, and Gu (2012). These errors calculated at each CC point of the finishing tool paths in x, y and z directions are illustrated in Figure 10(d)-(f ).…”

“…machine-related errors) are identified offline through a double ball bar (DBB) method developed in our previous research (Lasemi, Xue, and Gu 2012). The predicted process-related errors and the geometric errors are compensated through re-planning of the finishing tool paths using the mirror approach.…”

“…In a 3-axis CNC machine tool, 21 errors (i.e. 6 errors for each axis and 3 squareness errors between axes) are considered (Lasemi, Xue, and Gu 2012). Volumetric errors can be measured using the magnetic DBB.…”

“…Volumetric errors can be measured using the magnetic DBB. Measurement of the volumetric errors of the 3-axis machine tool using DBB is carried out by circular tests in XY, YZ and XZ planes (Lasemi, Xue, and Gu 2012). Based on the kinematic relationship between positions of axes and nominal position of the cutter relative to the workpiece, geometric errors of each machine axis can be identified.…”

Geometric Error Measurement and Identification for Rotational Axes of a Five-Axis CNC Machine Tool

“…Furthermore, analysing the influence of error sources on the end effector is another way to solve the geometric error source identification problem. Lasemi et al [17] and Ni et al [18] and [19] divided error sources into position-independent and positiondependent errors according to the difference in the effects of geometric error sources on the end effector by a DBB method. The identification model was established, and the geometric errors were identified by sensitivity analysis.…”