This presentation was made at CAASE18, The Conference on Advancing Analysis & Simulation in Engineering. CAASE18 brought together the leading visionaries, developers, and practitioners of CAE-related technologies in an open forum, to share experiences, discuss relevant trends, discover common themes, and explore future issues.
With the development of additive manufacturing technology conformal cooling application has been gaining popularity in die casting manufacturing process, because the conformal cooling can make significant improvements to both quality and productivity, and plus cost reduction. However, there is no existing effective and efficient methodology for the conformal cooling design for die casting manufacturing process, which can take the thermal stress into account to maximize the cooling efficiency of the conformal cooling. A full thermal-mechanical structural stress analysis of the conformal cooling line in the die casting manufacturing process is very complex and time consuming, which requires both CFD/FEA expertise and deep die casting process knowledge. As a result, most design practices in die casting industry are based on experience-guess-trial approach, which results in either not fully maximizing the cooling efficiency or cracking the insert prematurely. In order to take full advantage of conformal cooling line there is an urgent need for a simplified efficient methodology to analyze the thermal stress of conformal cooling line in die casting manufacturing process.
This paper presents a simplified modeling approach to analyze the thermal stress associated with conformal cooling line in die casting die by introducing a standard thermal load from molten metal on a hot zone and using local substructure to reduce the modeling scale and numerical complexity. The standard thermal load is a conservative estimate based on the fact that the solidification time of a hot zone is normally longer than the time required for the local insert in the vicinity of the cooling line to achieve quasi-steady thermal equilibrium, the temperature range of molten metal is narrow at the early solidification phase due to the latent heat effect and the maximum thermal hoop stress of a cooling hole can be achieved as a steady state thermal condition is met. The local substructure model is assigned with proper thermal and mechanical boundary conditions and can be considered as a sub-structural FEA model, which is based on the knowledge gained from the whole die casting die assembly FEA. Numerical results of the simplified modeling were compared with the results of the full complete die assembly stress analysis. The difference between these two types of analyses is minimal and acceptable both in the magnitude of the maximum thermal stress and the stress distribution of the cooling line in the die insert.
With this simplified approach thermal stress analysis of conformal cooling line can be done with simple FEA software that has basic steady-state thermal and static structural analysis functions. It makes a large number of numerical investigations possible, allowing exploration of the thermal stress trend associated with cooling line design parameters and gaining a better understanding of cooling line possible failure mechanisms in different scenarios. This approach provides design engineers the ability to evaluate initial design parameters quickly and increase first design success rate.
|Date||6th June 2018|
|Organisation||Ryobi Die Casting, USA|