Development On Modular Fixture Design System Based On RBR And Multilayer-case-base

As an important process equipment in aero-engine manufacturing system,the modular fixture could shorten preparation cycle of machinery production.The complexity of machining process for aero-engine parts results in the complexity of modular fixture structure.On the other hand,frequent changes during the developing stage of aero-engine leads to repeated assembly work for modular fixtures in job site.Computer-Aided Fixture Design can realize virtual assembly of modular fixture in computing environment,which has the problem of the low degree of standardization.Combined design features of modular fixture,the modular fixture cases were divided in a hierarchy in this paper.A modular fixture design method was presented based on RBR and CBD.What's more,a related CAFD system was developed to simplify procedure and increase assembled efficiency of modular fixture design.The achievements and innovation of this research are as follows:(1)A reasoning model of fixture plan based on rules was constructed.The location and clamp information of modular fixtures can be obtained by RBR based on the construction of clamping plan rule library.(2)The geometric modeling is finished by part family table method.A multilayer case base was created including product-layer,component-layer and part-layer,storing all the 3D models and related information,which can meet demand of system logic design.(3)A 17 digits coding system was developed to express the characteristics of the modular fixture product-layer case's index well.Part of system incoming information was from RBR module.The index information of modular fixture case can be expressed by the generated code in the round.(4)K-nearest neighbor technique was used to retrieve modular fixture case.Modular fixture rapid assemble was realized based on component-layer and part-layer case base,and the assembling design of modular fixtures is achieved.(5)The modular fixture design system based on RBR and multi-case-base was developed on NX UG with C++ and NX Open API.