Optimizing the Glass Clamping of a Pyrolytic Oven

The aim of this study was to find the best quality glass-clamping system, through parametric model optimization, for a new pyrolytic self-cleaning oven by Indesit. Like all pyrolytic self-cleaning ovens the pyrolysis process causes the oxidization of spills and dirt in the oven at temperatures of 450°to 500°C reducing them to ashes. This process produces a high thermal gradient which considerably deforms the glass and can cause ruptures. The door structure of a pyrolytic oven is made of a triple-glass system, each one separated by an air wall in order to guarantee rapid heat dissipation and to respect the safety regulations that limit external glass temperature to 60°C.

The Object of this Engineering Simulation Study

The model provided by Indesit is made of a 3D door model of the oven with the actual glass-clamping system. The door is composed by a 3 glass system, mounted on a specific structure that keeps them parallel and separated in order to allow the passage of the air cooling flow. This model was simplified in order to obtain a complete glass-clamp system to reproduce the real door-clamping solution.

The material provided had some elements, such as, chamfer and a non-functional fillet that were  deleted in order to obtain a simplified model that would be easier to analyze. Constraints characteristics and glass geometry were maintained in order to produce an opportunely approximated model.

The Engineering Simulation

RSM metamodelThe study included the following activities:

  • creation of a 3D Parametric FEM model using ANSYS
  • the definition of the thermal conditions on interior glass, according to experimental temperatures. This was done by building metamodels using modeFRONTIER
  • creation of the complete workflow in modeFRONTIER with ANSYS integrated in the workflow
  • clamping system optimization by an automated routine defined within modeFRONTIER
  • data analysis and selection of the optimal design given the objectives

With the aim of finding an optimal layout of the constraint system that minimizes stresses on the internal glass, the model was parameterized through a series of instructions that allowed modeFRONTIER to manage the geometry and make changes such as to the reciprocal distance and width of the glasses. modeFRONTIER was used to modify the model geometry on each run and to drive the input variables towards the most promising configurations. The results were considered with respect to stress and deformation on the model caused by the thermal gradient applied.

The Results

The optimization results in this study met expectations. An appreciable 30 to 40% decrease in stresses was registered with respect to the original configuration, solving the problem of potential glass breakage. Also, the deformations of the optimized configuration were greater than the original ones, which indicated that the design selected provides room for a better movement of the glass.

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Mauro Cola,
Manager R&D Coolking Appliances
Merloni Elettrodomestici