Study On Knowledge Based Design Technologies Of Injection Mold

This paper is based on the Key Industry Research program of the Science and Technology Bureau of Ningbo City, which name is "Knowledge Engineering based Injection Mold Rapid Design System" . To design plastic injection mold, the idea of knowledge engineering and database reasoning technology are applied. The main target is to establish a rapid design system for injection mold under the uniform product data management environment, and to make the best of reusing the design knowledge in the company scale. The main tasks of research are as following:1. Under the circumstances of plastic material's diversity and the difficulty of material selection, the material data classification method and the relation of material property and the plastic part are studied, and the general database which including material property, melt plastic flow behavior, plastic configuration and pigmentation libraries is set up. "Material property -plastic structure factor" mapping mechanism is created according to the material property influence on the plastic product. The mapping tool can automatically solve the mutual influence and requirement between material property and plastic structure factor. The general inquiry navigator is developed to search the associated information of the material selected, and export the selected information to several formats for share. The results indicate that this system can solve the problem of multipurpose plastic material selection fairly well.2. Plastic's Structure has great impact on the molding process and preventing the product's disfigurement, and so as to reduce the cost and increase the efficiency. The plastic's manufacturing process is considered, such as concavo-convex profile, taper, wall thickness, reinforce plate, hole design method, etc. The user can get help when he is designing the plastic, so that he can work out perfect product.3. The injection mold case similarity based on the nearest-neighbor is studied and the dissimilitude is discussed also to exalt the result validity for the case reasoning. To consider the difference of the technology in different period of time, and to reduce the match time complexity when searching the large scale case base, the case filtering mechanism is imported to limit the searching range. Thus only the needed cases are matched and computing efficiency is improved maximally. To adjust the selected case to match the aim, two aspects are offered. The first one is to modify the parts' information offline based-on the standard parts library; the other one is to adjust theassembly structure by "match relationship register". Finally, a new method of obtaining and reusing the designing cases is given, which the design process is recorded online and reused whenever needed. All these methods help to design mold automatically.4. Rapid modeling technique in plastic mold design process is studied. With the parameterized modeling technique, the modeling-parameter-driven part design method is studied. The single inheritance structure method is proposed to describe the parts parameters, and the multilevel data storage structure is proposed as the way to store the parts parameters, so that the plane 2D table (or complicated tree-like table) is simplified as liner data structure. Each record of this data structure contains only one parameter which includes control relation. So the serial and standardized parts design system is established, which can be dynamically expanded. The uniform assembly mold base design technology is proposed, which can be used to realize mold base change design with the same mold base seed assembly with the help of redundancy control parameters. With the help of all these methods and techniques, the capability of automatic mold design is improved and as a whole the design technology is improved too.5. PLM based integration in enterprise is very important, and it has brought great change in product design and management process. Take the plastic mold design process as the example, plastic material performance database and structure feature data are integrated into the PDM system. Mold design technology such as the CBR, model parameter driven parts library, uniform assembly model, are controlled by the PDM environment. The integration and encapsulation method of many kinds of software tools used in enterprise is analyzed and XML-based data transfer and share is also discussed. The synthesis control methods of enterprise data security are based on rules, objects, workflow and projects, so that all the data are controlled properly in the whole enterprise.