Development of Tool Path Interpolation Method for Five-Axis Controlled Swarf Machining Considering Machining Errors Caused by Changes in Tool Axis Vectors

Trajectory errors in five-axis controlled machining are generally reduced by interpolation methods such as linearization and tool center point (TCP) control. These methods insert interpolation points along the trajectory of the command point at the tool tip and calculate the tool axis vectors at each interpolation point by linear interpolation of two rotation axes, without referencing the machining surface. However, in swarf machining, where the side of a straight tool is in linear contact with the workpiece, the tool axis vectors must be determined with reference to the machining surface. Conventional interpolation methods do not guarantee the tool side's trajectory, resulting in insufficient machining accuracy. This study proposes a high-precision tool path interpolation method for five-axis controlled swarf machining on ruled surfaces using a straight tool. The proposed method interpolates both the command point and the tool axis vector by referencing the trajectories of two points at either end of the line where the tool contacts the workpiece, thus achieving a highly accurate tool path. To evaluate the effectiveness of the proposed method, machining simulation and actual machining experiments were conducted and compared with conventional linearization and TCP control methods. As a result, the conventional methods caused a maximum overcut of 34μm and undercut of 32μm in areas where the rotary axes commands changed significantly and were far from the command point located at the tool tip. In contrast, the proposed method achieved good machining accuracy within the specified tolerance limits.