AUTOMATIC IN-PROCESS CONTROL OF LASER METAL-WIRE DEPOSITION BASED ON SENSOR FEEDBACK

摘要

This paper describes a laser metal deposition system that is based on robotized laser welding and wire filler material. The system has been found suitable for the manufacture of simple but large shapes with high metallurgical requirements such as bosses or flanges found on aero engine components. Several benefits have been identified with the usage of wire filler compared to powderized feedstock, such as better process efficiency, higher deposition rates, and cleaner working environment. The wire based deposition process is however sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is described for automatic in-process control of the deposition. The goal is to obtain a flat surface for each deposited layer in order to ensure stable deposition. The deviations in the layer height are compensated by controlling the wire feed rate. The system is tested through deposition of small cylindrical bosses and the results show that the proposed control approach is suitable for automatic deposition of such structures. The material considered in this paper is Ti-6Al-4V deposited on plates of same material. The paper presents the equipment and the control strategy and discusses practical issues regarding the sensor used.