Method of scanning thin surfaces in repairing gas turbine blades

Abstract

Improving the efficiency of weld overlay repair of gas turbine blades by developing and implementing a method of scanning complex curved surfaces of gas turbine blades directly on the machine is the aim of this work. The paper proposes an approach to scanning a blade with a computer vision system mounted near the nozzle on the same machine that is used for direct metal deposition. The computer vision system consists of a triangulation laser sensor and a camera. The proposed algorithm is adaptive to the mechanical condition of the equipment used for scanning and metal deposition. The scans obtained from the machine vision system have precision better than 0.05mm in 67.56% of cases, and precision better than 0.1mm in 95.75% of cases. That accuracy, with a laser spot of 0.5 to 1.0mm, is sufficient for further use of the scans in repairing gas turbine blades. The proposed approach makes it possible to speed up the preparation of technological programs for direct metal deposition by 10 times compared to the manual scanning method.