Temperature field regulation in thermal cutting for layered manufacturing

A general thermal modeling and control methodology for thermal processing o f layered materials for rapid prototyping technologies is established in th is article. An analytical multivariable model of lumped temperature outputs generated by heat inputs on a surface grid is developed, based on Green's function and state-space descriptions. The few independent parameters neede d in such a linearized formulation are experimentally identified and their time-variability reflects the heat transfer nonlinearities and process dist urbances. A robust controller with thermal feedback is designed by pole pla cement methods, to obtain a specified dynamic temperature field yielding th e desired material structure and properties. The regulated thermal processi ng is optimized in real time by proper heat source power modulation and tor ch guidance through a simulated annealing strategy. Its performance is rest ed on both the computer model and a laboratory station, using robotically g uided plasma-arc cutting and infrared thermal sensing, in regulating the se nsitized zone during blanking of an elementary contour pattern on stainless steel.