【作者】 王会凤；

【导师】 周雄辉；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2008， 博士

【摘要】 随着世界经济一体化和制造全球化的发展,制造业市场竞争将更加激烈,用户需求趋于多样化和个性化,产品更新周期不断加快,从而促进了快速设计与制造技术的发展。如快速原型制造、分割制造等先进制造技术不断涌现,并迅速应用于制造业中。在一定条件下,由于加工资源、加工成本和加工时间等限制,复杂的产品或模型不能作为一个整体进行加工,需要将其分割成更小、更简单的块分别加工,再将各个块组合以得到所需的零件或模型,该项技术称为分割制造技术。分割制造技术可解决待加工零件/模型因结构复杂、体积过大(超出材料尺寸或机床加工范围)等造成的整体加工困难、材料利用率低等问题,已成为近年来学术界和产业界关注的热点。该技术具有降低加工设备要求、提高生产率,缩短新产品的设计与试制周期,降低开发费用等优点,应用十分广泛,不但可用于各种复杂零件或其原型件的加工,还可用于快速模具设计与制造。现有研究中通常将模型的所有组成面作为研究对象,或者将整体模型三角面片化,以面片作为研究对象,这样的处理会降低计算效率和计算精度。结合近年来特征领域所取得的进展,本文首次在分割制造技术中引入特征的概念,以特征作为研究对象,无论是分割面的获取还是约束条件的生成都是面向特征的,这不但可以在很大程度上减少计算量,提高计算精度,同时有利于后续制造过程中CAD/CAM的集成。可加工性分析是一个贯穿于整个分割过程中的重要部分,是判断分割与否的决定性因素。当模型不具有可加工性时,需要对其进行分割;在分割的过程中,各个分割块也要递归进行可加工性分析,直至所有的分割块都具有可加工性。本文以可视性分析代替可加工性分析,提出基于特征的全局可视性分析算法。该算法应用VMap可视性分析方法获得各个特征的局部可视性,并对具有局部可视性的特征进一步分析,将局部可视性分析扩大到全局可视性的范围,使可加工性分析结果更加符合生产的需要。为了获得最佳分割方案,本文首次提出分割方案多目标优化算法。首先在保证可加工性的前提下,充分考虑影响生产成本的各种因素,建立包括分割块数量、材料利用率(切削体积大小)、加工特征数和分割面积(组合面积)的目标函数,以及用于分割过程中的可加工性约束条件;然后采用遗传算法实现最优分割方案的获取;最后提出合并算法,通过冗余分割块的合并,进一步减少分割方案中分割块数量、加工特征数量以及分割面积。同时,对新兴的多块模具设计进行了探讨,并实现了自动多块模具设计。基于上述关键技术研究,利用VC++和UG/OPEN API,在UG NX平台上实现了复杂模型分割方案优选系统的开发。通过典型的零件分割和多块复杂模具设计实例验证了系统的合理性和有效性。更多还原

【Abstract】 With the development of world economic integration and manufacture globalization, competition of manufacture market is more intensive than ever. Requirements of customers are tending to diversification and individuation and the life span of a product tends to be shorter than before. All these promote the development of rapid design and rapid manufacture. More and more advanced manufacture technologies, such as rapid prototyping and partitioning manufacture, spring up and are applied speedily.Subjecting to manufacturing resource, cost and lead time constraints, sometimes,a complex product or model can not be machined as a whole, and need to be partitioned into a number of smaller and simpler manufacturable pieces. After manufactured,the individual pieces can be assembled to get the original product or model. That technology is called partitioning manufacture technology. It can reduce requirements for process equipment, shorten the periodicity of design/trial manufacture and decrease development cost, and it also can be used in industry widely, not only in various complex parts or its prototype processing but also in the automation of mold design and manufacture.In previous researches, all composed faces of the model are taken as the research objectives or triangle facets modeling is built first and triangle facets are treated as objectives. These methods will result in low computational efficiency and for triangle facets modeling is approximate model, it will cause low precision. Considering the achievement of feature technology during last decades, features are introduced into partitioning manufacture as the objective investigated for the first time and it can avoid the above shortages. At the same time, features introduction is propitious to CAD/CAM integration.Machinability analysis is an important part across partitioning process and is the crucial factor to decide whether to execute partitioning. In this paper, visibility analysis is instead of machinability analysis and a global visibility analysis algorithm is proposed. Firstly, local visibility is obtained using VMap ; and then each feature with local visibility will be analysis further. Global analysis result can fit for production equipment.For the first time, a multi-objective optimal algorithm is proposed to get the optimum partitioning scheme. In the algorithm partitioning pieces number, material utilization, machining features and partitioning area are considered synchronously to build objective function. Genetic algorithm is taken to implement the multi-objective optimal. In this paper, a combination algorithm is introduced to reduce the partitioning pieces number, machining features and partitioning area further. Combination of redundancy partitioning piece is propitious to optimal partitioning schemes. At the same time, an emerging multi-piece mold design is investigate and automatic mold design is realized in this paper.Based on the above key technologies research, using Visual C++6.0 and UG/OPEN API on the platform of UG NX, a prototype system of intelligent CAPP and integration with CAD/CAM in mold digital manufacturing is developed. Two typical parts of plastic mold are used to validate the feasibility and validity.更多还原