基于规则推理和多层实例库的组合夹具设计系统开发

发布时间：2018-08-28 07:41

【摘要】：作为航空发动机制造系统中的一种重要工艺装备,组合夹具缩短了产品生产的准备周期。但是航空发动机零件的机加工艺较为复杂,导致相应的组合夹具具有一定的结构复杂性。另一方面,航空发动机研制初期设计更改频繁,技术人员经常需要在工作现场对组合夹具进行反复组装。计算机辅助夹具设计技术的应用使得用户能够在计算机环境中对夹具进行虚拟装配,但仍然存在规范化程度低等问题。基于此,本文结合组合夹具结构的特点,对组合夹具实例进行了层次型划分,并根据规则推理和基于实例的设计技术,提出了一种基于规则推理和多层实例库的夹具组装设计方法,并开发出一套相应的组合夹具设计系统,旨在提高组合夹具虚拟环境下的组装效率。本文的主要工作和研究内容如下:(1)提出了基于规则的装夹方案推理模型,在建立了工件装夹方案规则库的基础上,利用规则推理获取组合夹具定位及夹紧信息。(2)采用零件族表法进行几何建模,构建了组合夹具“产品-组件-元件”多层实例库,实现了对实例三维模型及相关信息的存储,满足了系统设计的逻辑需求。(3)为了更好地表达组合夹具产品级实例的索引特征,开发了一套17位编码系统。该系统的一部分输入信息来源于规则推理模块,其生成的代码能够较为全面地描述实例索引信息。(4)采用最近相邻策略对组合夹具产品级实例进行检索,在组件级和元件级实例库的基础上,实现了对功能组件及元件的快速装配,以完成组合夹具产品的组装设计。(5)应用C++和NX Open API开发工具,在NX UG平台的基础上开发了基于规则推理和多层实例库的组合夹具设计系统。
[Abstract]:As an important process equipment in aero-engine manufacturing system, modular fixture shortens the preparation period of production. However, the machining process of aeroengine parts is more complex, resulting in the corresponding modular fixture has a certain structural complexity. On the other hand, the design changes frequently in the initial stage of aero-engine development, and technicians often need to assemble the modular fixture repeatedly in the work site. The application of computer aided fixture design (CAD) technology enables the user to assemble the fixture in the computer environment, but there are still some problems such as low standardization and so on. Based on this, combined with the characteristics of modular fixture structure, this paper divided the modular fixture cases into hierarchical types, and based on the rule reasoning and case-based design technology, A fixture assembly design method based on rule-based reasoning and multi-layer case library is proposed, and a corresponding modular fixture design system is developed to improve the assembly efficiency in virtual environment of modular fixture. The main work and research contents of this paper are as follows: (1) A rule-based reasoning model of clamping scheme is proposed, and the rule base of workpiece clamping scheme is established. The location and clamping information of modular fixture is obtained by rule reasoning. (2) geometric modeling is carried out by using part family table method, and the multi-layer case library of "product-component-component" of modular fixture is constructed, which realizes the storage of 3D model and related information of the case. (3) in order to better express the index features of modular fixture product level examples, a 17-bit coding system is developed. Part of the input information of the system comes from the rule reasoning module, and the generated code can describe the case index information more comprehensively. (4) the product level case of the modular fixture is retrieved by using the nearest neighbor strategy. On the basis of component level and component level instance library, the rapid assembly of functional components and components is realized to complete the assembly design of modular fixture products. (5) C and NX Open API development tools are used. Based on the NX UG platform, a modular fixture design system based on rule reasoning and multi-tier case library is developed.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG754

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