Intelligent CAD for plastic injection mould cooling system design

: a graph searching technique and configuaration space methods

Abstract

Although CAD/CAM systems are widely used in the design of injection moulds, they are mainly limited to providing geometric modeling tools that capture the geometric shapes of the components and the mould assembly. Commercially available, specialized stand-alone or add-on software packages only provide geometric modeling tools for the interactive design of the various components or sub-systems of the mould structure. Very little research has been published on intelligent CAD tools that can play a more active role in the design process. This research focuses on the design automation of the plastic injection mould cooling system. The cooling system is one of the most important systems in a plastic injection mould. As the cooling phase generally accounts for about two-thirds of the total cycle time of the injection moulding process, efficient cooling increases the overall productivity of that process. The cooling system also ensures product quality by providing uniform cooling across the entire part to prevent differential shrinkage, internal stresses, part warpage, and mould release problems. This research concentrates on the automation of the layout design process. In the layout design, the individual cooling circuits and cooling elements specified in the preliminary design are connected to form a complete cooling system. In addition to the functional requirement of the system, the manufacturability and the feasibility of the physical realization of the cooling system in the mould structure have to be considered. To develop a technique that automatically determines the best location for each channel of the cooling circuit to optimize cooling performance and avoid interference with the other components in the mould structure is the major challenge of this research. The major contribution of this study is that it establishes a set of techniques for automating the layout design process for various types of cooling systems. An heuristic graph-searching method is developed to automate the design of systems with single cooling circuits, and a novel configuration space technique is developed for systems with multiple cooling circuits and those with user-defined constraints. The theory behind the configuration space method is thoroughly investigated, and vigorous proofs of the related theorems and lemmas are presented. Experiential systems are implemented using C++ and interfaced to a commercial CAD system. Experimental data is presented to demonstrate the effectiveness of the method, and case studies demonstrate its ability to generate practical cooling system designs. Keywords : Design automation; Automatic design synthesis; Plastic injection mould; Cooling system design; Configuration space method.

Date of Award	2 Oct 2009
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Chung Lun Eric LI (Supervisor)