Design of Online Measurement System for Molten Pool Morphology in Selective Laser Melting (SLM) Process

Abstract

Selective Laser Melting (SLM), as the processing technology with the highest forming accuracy and the best processing quality in additive manufacturing, is widely used in aerospace fields, etc. Laser molten pool is the basic unit of SLM processing, and online monitoring of the laser molten pool morphology can reflect the SLM processing accuracy and process stability in real time. In this paper, an online measurement system for side-axis laser molten pool morphology is developed inside the SLM molding cabin. Temperature isolation and sealing protection is designed for the online measurement system under complex high-temperature environments. It uses high-speed COMS camera and image acquisition card equipped with FPGA chips to collect and transmit the molten pool image information in real time. The software design of the online measurement system includes the development of the camera SDK based on Visual Studio, the design of real-time image processing algorithms, the evaluation of the molten pool, etc., which aims to evaluate the image acquisition, transmission and storage of the molten pool. Through simulation analysis and experimental verification, it is proved that the system can allow on-line measurement of molten pool morphology.