Research On Key Technologies For Virtual Injection Molding System

Design of injection products is a complex process. It is very necessary for reducing the production cycle, improving the quality and winning the competition that must be considered about the product design, injection mould design, numerical simulation of injection molding, injection mould processing, and the process of injection molding. In this article, the impact of global economic activities on manufacturing industry and the main supporting technologies of product innovation engineering are summarized. The problem that should be resolved to realized real-time collaboration for virtual design and virtual manufacturing about the injection product under virtual reality are analyzed and summarized systematically. According to the different requirements for product information during different stages of collaboration in whole-product-life-cycle, the idea to realize virtual development of injection product based on virtual reality technique is presented for the first time, and the virtual injection molding environment for research work in this article is established clearly and definitely, which provides basis for the following detailed algorithm research.In this article, based on the techniques of injection molding, virtual design, virtual manufacturing, virtual prototype, the fundamental frame of injection product virtual injection molding development is established through integrating of the technique of CAD based on virtual reality, the technique of Physically-Based Modeling and behavior-based modeling and collision detection technique. This development environment supports the virtual design of the injection product and equipment and simulation of injection molding process.When develops VR-CAD technique for geometric modeling, in according with the requirements on geometric information for geometric modeling in virtual environment, geometric information model is firstly presented. This data model not only can be describing in geometric modeling but also can be applied on the simulation and evaluation in the virtual environment. Based on this data model the virtual reality technique and CAD technique are integrated. Because the triangle model is the main subject when the virtual objects act on each other, so, hierarchical product information model is put forward for virtual design or virtual manufacturing. Conquering the fault which the information about geometric model of virtual object is not complete. Aiming at different service goals, product information is presented. Complete and obvious topological information is dispensable basis for subsequent handling of triangular mesh models and tetrahedral mesh models. For triangular mesh models in STL format, an algorithm is applied in rebuilding its topological structure efficiently. For tetrahedral mesh models, adjacent graph is applied in rebuilding the topological relationship of tetrahedral set. Another then, according to topological relationship the memory capacity of triangular mesh and tetrahedral element is reduced through compressing the storage of triangular and tetrahedral element structure.In this article, the idea to simulate real injection molding in virtual environment is presented firstly, and called virtual injection molding. Based on this idea the hierarchical injection environment information model is presented. Based on this environment model, physical-based modeling is executed for virtual object in virtual injection environment, and optimized method about physically-modeling is presented. Based on the physical properties of virtual object in virtual injection molding environment, in this article, the behavior modeling method is presented firstly. There are virtual machine agent, virtual mould agent, virtual product agent and virtual hand agent in the virtual injection molding environment modeled with multi-agent system. The fundamental structure of agent in virtual injection molding is presented firstly. In virtual injection molding environment modeled with multi-agent system, the state transition mechanism described by an object-oriented Petri net is used as the agent behavior inference method. The variance computations of geometrical shape, physical properties and movement parameters are employed for the behavior computation pattern of the agents. The message processing mechanism is adopted to describe the system behavior. The algorithms for agent behavior inference are presented, and the algorithms for system behavior inference are presented.In virtual injection molding environment, independent virtual objects realize the function of injection molding through activating the messages of collision. To detect the collision between virtual objects accurately and rapidly, a novel continuous collision detection algorithm was presented. The algorithm performed well at each time interval in real-time with the time interval being divided into several sub-intervals. By using continuous overlap detection method for oriented bounding boxes (OBB), a potentially colliding set of sub-intervals was computed. The initial collision times and positions among the virtual objects were calculated by using collision detection method among triangle facets and backtracking method. In order to improve the detection velocity, the method that the field of"Cache"is added on each virtual object to record the information of collision, and compare it with the next collision detection. Based on physics and behavior modeling of virtual objects, in this article, the new method was presented by using the series of Tailor method to calculate the colliding time accurately. To some virtual objects which the property of physics and behavior has been calculated, this method would improve the velocity of collision detection.According to the theoretical studies stated above, the virtual injection molding prototyping system for injection product is developed based on the system of unix. System structure, development process model and function model proposed in this article are verified by development example.