Research On Incremental Discovery Of Knowledge For Injection Mould Repair

The quality of the plastic parts was depended on the injection mould. The plastic parts with complicated molding surface and structure, most of them were customized, and mould tests of the injection moulds were hard to be successful with the general designing and manufacture principles, so the mould repairs were inevitable in practice. In the process of the mould repair, the mould repair engineer should formulate the reasonable mould repair scheme with the traditional mould designing knowledge, manufacturing knowledge and the experience knowledge which accumulated in the mould repair practicing. The experience knowledge was accumulated and improved by constant practicing and accepting lessons. So many mould enterprises began to collect related historical records which were documented in the form of "problems and solutions" to form electronic mould repair schemes" which was helpful to the engineers find the similar mould repair schemes by searching the similar problem when a new mould repair project was formulated. But with the increasing number of cases, more and more schemes can be referenced and many similar problems have different solutions, so the engineers will be puzzled in lots of cases. The only way to resolve the questions was that the inherent disciplines should be concluded from the history projects and the true " experience knowledge" asset will be obtained. There are three kinds of difficulty to obtain the experience knowledge. Firltly. there are complicated semantic relationships among the different values of the mould repair schemes attributes. How to establish the complex related model for different characteristic parameters of mould repair schemes and how to extract the new are very difficulty. Secondly, the mould repair experience knowledge was variety and uncertainty which led to that the inherent disciplines from the mould repair schemes will be concluded. Lastly, practical application demanded the mould knowledge management system possessed the compacity of inducing rules from the knowledge database constantly. The new mould repair case can affect the original data decision table, and the system should extract the new rules and induce new knowledge from the mould repair cases, so how to use the new mould repair information and establish the sustainable learning mechanism was another difficulty.According to the difficulty, the main studies of the paper had been conducted as following.(1) The establishment of the mould repair knowledge ontology based on the nets structure and the representation of the mould repair scheme based on SWRL (sematic web rule language)By contrast with the model that only using the hierarchy relations among the concepts discribing the experience knowledge, the new mould repair experience knowledge representation model based on description logic was built, and not only the hierarchy relations but also the complex user-defined relations among the concepts were took into account. The nets mould repair knowledge ontology was established. Then the complex semantic relationships among the concepts of the mould repair experience knowledge were described completely. The mould repair schemes were built by SWRL which can use directly the concepts (classes) and the relations between the concepts of OWL, which can carry out that the mould repair schemes can be structured. So the problem that the mould repair schemes can’t be recognized by the computer was solved.(2) The establishment of the algorithm for the similar calculating between the concepts based on the ontology sematic nets model and the construction of the "sematie coordinate". By contrast with the method of similar calculating based on the hierarchy relationships model, a new semantic similarity computation algorithm based on the ontology semantic nets model was built, in which the user-defined relationships among the concepts and the subclass relationships were both involved. A series of "center concepts" which were used to act the "semantic expression coordinate" of the concepts were obtained by the new algorithm. The mould repair scheme was the mapping point from every concept semantic value. It can resolve the problem that lots of rules with limit application were generated when the many different values were concluded. So the number of the concepts for rule induction was reduced by using the method, and the concise degree and the application ranges of the rules were improved.(3) The mould repair scheme incremental updating algorithm based on the rough setA rules incremental updating algorithm based on rough set was built and applied to the repairing knowledge discovery of injection mould.. Firstly, the discernibility matrix was improved, and the incremental updating algorithm for finding the core and attribution reduction based on discernibility matrix were built. Secondly, according to the heavy computation of disjunction and conjunction in the process of attribution reduction, the distinct difference matrix was adopted which can reduced the calculation complexity. Lastly, the complete mould repair rule set was obtained by calculating the rule’s accuracy and the coverage, setting the threshold value, and inducing the rules.(4)The design and implementation of the mould repairing knowledge management system based on incremental updatingThe system was designed to carry out the functions such as semantic editing of the mould repair knowledge domain ontology, maintenance of the semantic coordinate and mould repair schemes knowledge, clustering of the mould repair schemes, incremental updating of the mould repair schemes.Through the above research work, the problems how to express the complex sementic relations among the values of mould repair schemes attributes, how to obtain the typical mould repair scheme, and how to incremental update constantly were solved. The methods and conclusions drawn from the paper will provide an efficient way to discover mould repair knowledge in mould manufacture enterprises.