ON-LINE IMAGING PYROMETER FOR LASER DEPOSITION PROCESSING

摘要

An online imaging pyrometer has been developed to monitor the temperature distribution of the melt pool in laser additive manufacturing processes. The imaging pyrometer uses two CCD cameras with "long" and "short" wavelength filters in the near infra-red (NIR) waveband. The intensity ratio is formed and the two-wavelength temperature is determined from a calibration, relating the intensity ratio to the temperature. In the experiment, deposits of tool steel (H13) are formed over a variety of laser power levels, ranging from standard power to about half the initial power level. As the power is lowered, the deposit efficiency is reduced, as are the melt-pool dimensions. Melt pool temperature distributions were measured in the final five of the 10 passes, and their properties are presented and described. Peak temperatures of about 2000℃ are noted for standard power levels and in general lower temperatures are observed at lower power levels.