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A configuration space ( C -space) method was developed in a previous study to support the automation of the layout design of cooling systems. The main function of the C -space is to capture all of the feasible geometry of the layout design so that a genetic algorithm (GA) can be used to explore the design space. This paper reports a further extension of the C -space method in two respects. The new method overcomes the previous limitation of the non-variability of the design topology. By capturing useful information generated during the computation of the C -space, the new method enables the GA to explore both the geometry and the topology of the design during the evolutionary process. A new technique is also developed that enables the method to handle user-defined constraints on the layout design. These constraints are captured by additional C -spaces, and a special procedure is developed for computing the C -spaces of cooling systems and generating candidate designs so that the resulting design always satisfies the constraints. Vigorous proof of the validity of the new method is provided, and a case study is presented to demonstrate the capability of the method in generating a practical layout design for a cooling system. Highlights? The geometry and topology of design are explored concurrently and automatically. ? Re-use of design information is implemented. ? User-defined constraints of cooling system are dealt with. ? Vigorous proof of the validity of the new method is provided.

Plastic parts, especially those designed for consumer electronics products, are becoming more compact and freeform in shape. This requires the construction of compact and delicate geometric features in the injection moulds that produce these parts. It is now common practice to employ electric discharge machining (EDM) whenever the conventional machining process fails to machine such delicate features. Although CAD/CAM systems are widely used in mould design and manufacturing, and specific commercial CAD/CAM systems that are customized for injection mould applications are also available, there are still no intelligent CAD tools that address the specific requirements of EDM electrode design. The aim of this research is to develop an intelligent CAD tool that supports EDM electrode design. This CAD tool uses a new technique that recursively splits the EDM region into sub-regions until machinable electrodes can be constructed. The CAD tool has been implemented and integrated into a commercial CAD/CAM system, and 40 different real designs has been used to test its capability in handling a wide variety of geometric shapes. Performance data show that the efficiency of the design process can be improved by at least 50%, with a potential to achieve 85% through improved implementation and further research.

The cooling system of an injection mould is very important to the productivity of the injection moulding process and the quality of the moulded part. Despite the various research efforts that have been directed towards the analysis, optimization, and fabrication of cooling systems, support for the layout design of the cooling system has not been well developed. In the layout design phase, a major concern is the feasibility of building the cooling system inside the mould insert without interfering with the other mould components. This paper reports a configuration space (C-space) method to address this important issue. While a high-dimensional C-space is generally required to deal with a complex system such as a cooling system, the special characteristics of cooling system design are exploited in the present study, and special techniques that allow C-space computation and storage in three-dimensional or lower dimension are developed. This new method is an improvement on the heuristic method developed previously by the authors, because the C-space representation enables an automatic layout design system to conduct a more systematic search among all of the feasible designs. A simple genetic algorithm is implemented and integrated with the C-space representation to automatically generate candidate layout designs. Design examples generated by the genetic algorithm are given to demonstrate the feasibility of the method.

Isoparametric or streamline-like toolpath generation is an important method for CNC surface machining. For a trimmed surface, the generation of such a toolpath is not straightforward because by simply following the isoparametric curves of the parametric surface to generate the toolpath, the resulting toolpath may no longer conform to the trimmed boundary of the surface. Various methods have been proposed to solve this problem. Some methods work well for single surface machining, but may not be feasible for multi-patch surface machining. A new geometric approach to the problem of multi-patch machining is proposed in this paper. The new method works by generating bisectors to partition the region into smaller subregions, and generates the toolpath by offsetting the subregion boundary by using a special offset function. As this new method does not rely on processing on the parametric domain of the surface patches, it can be used for both NURBS and subdivision surfaces. Examples are given to demonstrate the capability of the new method, and to show that the new method compares favorably with existing techniques.

This research extends our previous investigation of the automation of the preliminary design stage to the layout design stage of the cooling system design process. While the functional aspects of the cooling system are considered during the preliminary design stage, the layout design stage addresses both the functionality and manufacturability of the design. A graph structure is devised to capture a given preliminary design and a graph traversal algorithm is developed to generate candidate cooling circuits from the graph structure. Heuristic search is employed to develop the cooling circuits into the layout designs by generation of tentative manufacturing plans. A framework for fuzzy evaluation of the layout designs is developed to rate the various design alternatives generated. An experimental system is implemented to verify the feasibility of the approach, and examples generated from the system are presented to illustrate the major steps of the automatic design process.

Most existing work on the design of cooling systems of plastic injection moulds has been focused on the detailed analysis or the optimization of the cooling system. However, before a cooling system can be analysed or optimized, an initial design has to be developed. We explore a new design synthesis approach to solve this initial design problem. A plastic part with a complex shape is decomposed into simpler shape features. The cooling systems of the individual features are first obtained, they are then combined to form the cooling system of the entire part. Decomposing a complex shape into shape features is a feature recognition problem. A new algorithm for the recognition of features specific to cooling system design is developed. Design examples generated by the design synthesis process are analysed by C-Mold to verify the feasibility of the approach.

Most existing work on mechanical design automation has been focused on single-state design problems. We explore a new method that solves multiple-state design problems. The proposed method uses the configuration space (Cspace) as the basis to represent the behaviours of kinematic pairs, which are the basic building blocks from which more complex design is synthesized. Previous work in Cspace approaches are limited to the retrieval or innovation of a single kinematic pair as the design solution. We extend the Cspace approach to generate design solutions that consists of either a chain or a network of multiple kinematic pairs. An experimental program called ADCS has been implemented to verify the feasibility of the proposed design methodology. Design examples generated by ADCS are used to illustrate the major steps involved in the design synthesis process.