Evaluation of dynamic behavior of rotary axis in five-axis machining center (Behavior around motion direction changes)

Abstract

Several methods of evaluating the motion accuracy of the rotary axes of five-axis machining centers have been proposed in past studies. Because it is known that particular motion errors exist near motion direction changing points, it is important to evaluate the behavior of the rotary axes near these points. However, the influence of the motion error of the translational axes is included in conventional evaluation results because the translational axes reverse at the motion direction changing points about the rotary axes. In this study, a measurement system for evaluating the dynamic characteristics of the rotary axes near the motion direction changing points about these axes, excluding the influence of the translational axes, was developed. The measurement tests were also conducted using this measurement system for evaluating the dynamic characteristics of the tilt axis near the motion direction changing points about this axis. In addition, an actual machining test was conducted to evaluate the influence of the motion errors of the tilt axis near the motion direction changing points. As a result, it was confirmed that the behavior of the tilt axis near the motion direction changing points can be evaluated by using the proposed measurement method. It was also confirmed that the influence of the motion error on the machined surface is related to the size and shape of the tool and the geometric relationship between the motion error and the machined surface. It was also confirmed that the machined shape does not always contain defects when motion errors exist depending on the relationship between the motion error and the machined surface.

Keywords

• five-axis machining center
• rotary axis
• dynamic behavior
• motion direction changes
• machined surface