Interference-Free Inspection Path Generation for Impeller Blades Using an On-Machine Probe

Inspecting an impeller is a challenging task in manufacturing automation due to its free-form surface and overlapping and twisted blades. Existing inspection method by a Coordinate Measuring Machine is complex and time consuming, because of offline reclamping and manual operation. Automatic on-machine inspection without transferring and reclamping workpiece is a promising technique, and has found an extensive application in recent years. This paper proposes a novel method of interference-free inspection path generation for impeller blades using an on-machine probe. The accessibility cone is defined to search for the approach direction vectors of a probe cylinder, whereby the sizes of both cylinder rod and cylinder disk are considered. Then, the idea of area sweeping minimization is applied to construct an objective function from which required direction vectors of the probe cylinder in a smooth path are easily solved. The generated path can avoid the interference and collision between a moving probe cylinder with the overlapping blades, and guarantee stable speed and acceleration of the rotary motions of the five-axis machine tool. Its effectiveness is verified by the on-machine inspection experiments.