Estimation of tool orientation contour errors for five-axis machining

Recently, there has been a growth of interest in high-precision machining in multi-axis feed drive systems, which are subject to problems such as friction, cutting force and incompatibility of individual driving axis dynamics. Tracking errors in an individual driving axis during five-axis machining result in tool tip contour error and tool orientation contour error. Based on the conventional definition of the tool orientation contour error, that is, it is the deviation in the normal direction from the desired orientation in spherical coordinates, even if the tool tip and tool orientation contour errors are very small, a mismatch between the tool tip position and tool orientation causes an overcut or undercut when these errors are treated independently. To address this problem of mismatch, this paper presents a new definition of the actual tool orientation contour error. This definition considers synchronization between the tool tip and tool orientation contour errors. In addition, we propose an estimation model for the tool orientation contour error. Experimental results demonstrate that the proposed model provides a better indication of the actual tool orientation contour error than the conventional definition. (C) 2013 Elsevier Ltd. All rights reserved.