Mathematical model of a resistive oven for thermoforming polypropylene sheets

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Lidia Castro-Cepeda
José Cortés-Llanganate


A mathematical model of a resistive oven for the production of thermoformed sheets is developed in this paper; such oven is located in a production plant in the city of Riobamba. The objective of the research is to achieve temperature stability and that the plates have a homogeneous dimension when going through the thermoforming process, to guarantee customer satisfaction. For this purpose, the physical variables that govern the heat transfer phenomena, namely radiation, convection and conduction, are analyzed, to obtain a mathematical model that predicts the temperature profile of the oven in the thermoforming process, from which a controller is designed using various control techniques that are efficiently coupled to the system. A theoretical study of the physical phenomena and of the mathematical equations that represent them is proposed in the first stage of the research. Then, they are solved through computational techniques using Simulink to obtain the temperature profile. Finally, this model is validated by comparing it with those obtained in previous works through statistical techniques, and a new controller that guarantees minimum temperature variability is proposed. As a result of the simulation, a variation of ±1 mm in the width of the plate is achieved.