Temperature distribution control in scanned thermal processing of thin circular parts

Scan thermal processing is enabled by guidance of the heat source trajectory during fabrication. For thin, cylindrically symmetric parts, this is performed by their rapid revolution under a radially or axially translated torch, with its power modulated so as to implement a specified thermal distribution as it sweeps the product surface, and thus to generate desirable material features. A new analytical description of the thermal field in thin disk-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 emissivity 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 locations by an infrared pyrometer. The thermal regulator is validated computationally and experimentally.