A method of ultrasonic detection for sculptured surface not accurately fixtured

The small rigid displacement exists between each complex curved scanning workpiece which has the same shape but is not accurately fixtured. It´s a repeated and time-consuming job to generate the scanning path. To solve this problem, a new method was proposed. The first workpiece surface was sampled and the initial surface model was generated by surface reconstruction. Then, the profiling measurement was used to get a more accurate CAD model as the template. In the case of the next scanning part model was known but its localization was unknown, an improved workpiece localization algorithm using the geometric properties of curved surface for points matching was applied to get the transformation relations between the workpiece and template. Using these relations, it was easy to generate the scanning path quickly by the template. Simulation and experiment results indicate that after getting some reasonable measurement points of the scanning part, this method can provide accurate scanning path efficiently , the repeated processes of getting CAD model can be avoided, the testing time of each workpiece can be saved greatly.