Optical sensor to monitor and control temperature and build height of the laser direct-casting process

摘要

A nonintrusive optical sensor system is applied to real-time process control of the recently developed laser direct-casting process, in which a stream of metal powder is introduced into the beam of a high-power (500-W) cw laser to fabricate complex three-dimensional structures. The sensor system allows two critical parameters, temperature and build height, associated with this process to be monitored and controlled continuously. We achieved a height-sensing resolution of ± 0.25 mm and temperature control with a resolution of ±10℃ at a typical working temperature of 1500 ℃with an evident improvement in process quality, especially for complex workpieces comprising relatively high, thin walls at which the conductive heat transfer varies substantially as the process proceeds. # 1998 Optical Society of America OCIS codes: 140.3390, 060.2370, 120.6780.