Research On Case Knowledge Acquisition Of Body In White Welding Fixture

Modern product design is based on knowledge.So design reuse has become a research hotspot with knowledge acquisition as the core.For example,the design reuse of welding fixture in automotive body-in-white(BIW)engineering has become an important research field.BIW welding process involves 3000 to 5000 welding spots.There are more than 100 welding stations,and 500 to 800 fixture units.It is a meaningful research topic that how to reuse a large number of car welding fixture parts and components in a new design task.The design of case-based reasoning refers to that the case of reuse design is achieved from the three-dimensional assembly model.The kinematic model and the main parameters of the three-dimensional assembly model are obtained by learning and acquainting the case knowledge.The feature-based fixture case identification algorithm is presented based on the entity identification method,contrasted to the method of identifying the assembly type by using non-physical feature retrieval such as text name.The theory of case identification of typical welding fixture unit is studied with the support of the framework of the fixture case identification based on the physical characteristics.The identification algorithm of kinematic component for one-link fixture unit and two-link fixture unit are proposed.Then the kinematic model extraction algorithm and the case identification algorithm for one-link fixture unit and two-link fixture unit are presented.Finally,the kinematic model extraction algorithm and the case identification algorithm for BIW fixture are verified by the engineering example.As result,the case identification algorithm based on the entity feature will provide a solution for the identification of the parts in the typical fixture case and the identification of the typical fixture type.On this basis,the kinematic model extraction algorithm and the case identification algorithm provides a novel method to acquisite case knowledge for the three-dimensional assembly model.