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Quantification of cooling channel heat transfer in low pressure die casting Moayedinia, Sara

Abstract

The focus of this project is to develop a methodology to quantitatively describe the heat transfer in the cooling channels of the low-pressure die casting process, which is the dominant commercial technology for the production of aluminum automotive wheels, and to successfully implement the methodology in a numerical model of the casting process. Towards this goal, an algorithm capable of calculating heat transfer coefficient (HTC) based on process parameters and surface temperature within the cooling channel is developed. The algorithm was implemented in the form of a user-defined subroutine in a 3-D thermal model of the Low Pressure Die Casting (LPDC) process developed in the commercial finite element analysis package in ABAQUS. The cooling channel HTC’s are often input into thermal models as an average constant value derived based on trial-and-error. The trial-and-error process to obtain the HTCs in the cooling channel involves, prescribing a trial set of HTC values and comparing the results of the casting simulation with thermocouple measurements. The trial cooling channel HTCs are then adjusted until a reasonable fit to the temperature measurements are achieved. The trial-and-error process is generally time consuming and does not accurately describe the physical phenomenon occurring in the cooling channel during casting. The constant cooling channel HTCs obtained through the trial-and-error process are tuned to a given set of operating conditions, compromising the utility and generality of the model. To provide data necessary for model validation, casting plant trials were performed at Canadian Autoparts Toyota Inc. in Delta, British Columbia. The trials included temperature measurements at pre-determined locations within the top, side and bottom dies. The validity of HTC calculations have been assessed by comparing the predicted temperature history of the subroutine-based model with the measured thermocouple data collected during the casting cycle and also comparing the model predictions with the base-case model with constant cooling channel HTC.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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