Numerical infrared heating of semi transparent thermoplastic using ray tracing method
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Thermoforming process include a heating stage of the thermoplastic specimen by infrared heaters. The knowledge of the temperature distribution on the surface and through the thickness of the preform is important to make good prediction of thickness and properties of the manufactured part. Currently in industry, the fitting of the process parameters is given by experience and it is expensive. Our objective is to provide tools that are able to simulate the heat transfers between the infrared heaters and the specimen in order to reduce the fitting cost and to control the qualities of the end product. We use the optical method called ” ray tracing ” (RTM) to simulate the radiative transfer. First, we compare the RTM with the shape factor method on a simple example: the heating of a square sheet by one infrared lamp. Then, we show the 3D heating stage of a rectangular specimen. In that case, we use 6 lamps to simulate an infrared oven. The RTM allows to compute a source term in the transient heat balance equation. We can use commercial codes to solve the heat balance equation.
KeywordsHeat transfer Ray Tracing Thermoforming
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