Temperature distribution control in scanned thermal processing of thin circular parts

Scan thermal processing is enabled by guidance of the heat source trajector y during fabrication. For thin, cylindrically symmetric parts, this is perf ormed by their rapid revolution under a radially or axially translated torc h, with its power modulated so as to implement a specified thermal distribu tion as it sweeps the product surface, and thus to generate desirable mater ial features. A new analytical description of the thermal field in thin dis k-shaped parts, based on superposition of Green's functions, was developed for off-line analysis. A multivariable linearized model with least-squares identification of its varying parameters was also derived for real-time emi ssivity compensation and prediction of delayed temperature data. This model is embedded to a thermal distribution control scheme, driving the scanned torch motion and power by a new real-time simulated annealing optimization strategy, using temperature feedback from randomly sampled surface location s by an infrared pyrometer. The thermal regulator is validated computationa lly and experimentally.