【作者】 马立东；

【导师】 刘才；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2010， 博士

【摘要】 冷弯型钢是一种经济的截面轻型薄壁钢材,截至目前,我国共有1000多条冷弯型钢生产线,生产能力达到每年1500万吨,它广泛应用于国民经济的各个领域,而辊弯成型是冷弯型钢成型的最主要的方式,因此,对辊弯成型过程进行系统的理论研究,揭示其成型规律,研究实用的辅助设计软件,指导实际生产设计,具有重大的理论意义和使用价值。辊弯成型属于复杂的板带深加工方法,其复杂性表现在辊弯成型是几何、材料和接触边界等多重非线性的变形过程,而且影响成型过程的因素非常多。因此,辊弯成型技术研究是一个非常复杂的课题,目前,国内外学者对此还没有提出一种非常完善又精确的分析方法。本文首先综述国内外有关冷弯型钢生产现状、成型工艺技术、成型理论、成型过程计算机模拟和CAD技术的研究进展。然后通过有限元法、有限条法、解析法三种方法的对比,系统研究辊弯成型机理。最后介绍了辊弯成型设计的网络化及设计、仿真、知识库的一体化实现模型。借助于大型商业有限元软件ABAQUS/Explicit模拟辊弯成型过程,并将模拟后的结果导入implicit模块,研究材料弹复过程,将计算结果与实验结果进行了对比,得到了一致的结果,证明模型的正确性与可靠性。通过这一过程,熟悉了辊弯成型设计的过程以及轧制工艺流程,得到的结果可以作为后续其他理论的参考。在有限元方法和结构分析的有限条方法的基础上,引入固体力学有限形变理论,系统的研究了网格划分理论,并首次实现了有限条网格的不均分划分,严格的推导了计算列式,并以普通槽钢、外卷边槽钢(冷弯中梁)做了考证,结果吻合较好。由于数值方法的计算成本比较高,对工程师的要求也比较高,本文还提出了一种新的基于机架间平均纵向应变的解析方法,采用以累计弦长为参数的3次样条曲线拟合不同机架上相同位置的点,计算机架间的平均延伸量,进而得到机架间的平均纵向应变。该方法计算速度快,比传统的直线逼近和其他曲线方式逼近的解析法更科学,并将结果与有限元结果进行了比较,趋势相当吻合。以上三种方法,从计算的精度与可靠性看,有限元法优于有限条法,而有限条法优于解析法;从计算的速度上看解析法明显优于有限条法,而有限条法优于有限元法;从对工程师技术要求程度上看,解析法和有限条法相差不大,但明显优于有限元法。本文将多agent理论引入辊弯成型领域,搭建了基于多agent的辊弯成型辅助设计平台体系结构。利用网络化技术,实现了用户的异地产品设计的要求,实现了分布式运算能力。将以上三种分析方法区别的应用于在该多agent系统中,可以更加快速,准确的模拟辊弯成型过程。总之,本文所使用的解析法、有限元法以及不均分有限条法证明是正确和有效的,均能模拟多种冷弯型钢成型的过程。另外,应用多agent技术,将辊弯成型的设计、仿真、知识库有机的,分布式的集成在一起,建立了基于网络的分布式辊弯成型计算机辅助设计仿真系统,在科学分析的基础上,大大降低了工具的制造成本和设计风险,除此之外,使辊弯成型的产品设计变得更加通用,推动我国自有知识产权的商用仿真软件的发展。更多还原

【Abstract】 Cold-formed steel is an economic cross-section of light thin-walled steel and it is widely used in all fields of national economy. Up to now, China has had more than 1,000 cold-formed steel production lines. Its production capacity reaches 15 million tons per year,. Therefore, it has important theoretical significance and practical value to study the cold bending forming process, reveal its forming law, develop practical design software to guide the actual production process.Cold roll forming is a widely used complex method for material deep-processing. It is a highly non-linear deformation process including geometric non-linearity, materials non-linearity and contact, and so on, and there are many factors which can affect the forming process. Therefore, the study of cold roll forming technology is a very complex subject. Up to now, neither domestic nor foreign scholars have yet offered a very complete and precise analysis procedure.This paper first summarizes the current state of cold-formed steel production, forming technology, forming theories, computer simulation of the forming process and CAD technologies in the world. Then by using the finite element method, finite strip method and analytical method, the cold roll forming mechanism has been systematically studied. Finally the networked design and integration of design, simulation and knowledge base for cold roll bending forming process are introduced.The cold roll forming is simulated by the commercial explicit finite element software ABAQUS. The simulation result is then followed by an implicit analysis to study the springback of the formed product. By comparison, good agreement has been achieved between the simulation result and the experiment result, so the computer model is proved to be correct and reliable.Therefore, these results have been used to validate other theories addressed in the paper..Based on the finite element method and the finite strip method of structural analysis, finite deformation theory has been introduced to elastic-plastic large deformation spline finite strip method. Non-uniform finite strip mesh discretization has been realized. The formulations are rigorously derived, and the results are in good agreement based on the analysis of channel steel and channel steel with outer edge (cold-formed beam)As the finite element method and finite strip method are computing intensive and there is a highly requirement for skilled engineers. To improve the simulation efficiency, a new analytical method based on the average longitudinal strain between stands has been presented. In the method, accumulative chord length parametric cubic spline curves were used to fit the longitudinal material passes to compute mean longitudinal strain between stands. The calculating process of the method needs almost no time, and the trend of its prediction found good agreement with finite element analysis..The above three methods, on the side of the calculation accuracy and reliability, the finite element method is superior to the finite strip method, finite strip method is superior to the analytic method; on the side of speed of calculation ,analytical method is superior to the finite strip method, while the finite strip method is better than the finite element method; on the side of technical requirements for engineers , analytical method and finite strip method is pretty much the same, but obviously better than the finite element method The multi-agent theory is introduced to the field of cold roll forming in the paper, the architecture of computer aided design platform of cold roll forming based on multi-agent is presented. The user’s remote product design requirements and the distributed computing requirements are realized by using networked technology. The construction of knowledge base and bringing the actual production of design experience into the system help users to design suitable products more quickly. The above three kinds of analysis methods are applied in the multi-agent system, the simulation of cold-formed molding process can be more rapid and accurate .In short, the analytical method, finite element method and the non-uniform mesh discretization of finite strip method used in this paper are proved to be correct and effective, and they are able to simulate a variety of cold-formed steel forming process. In addition, application of multi-agent technology, cold roll forming design, simulation, knowledge data are integrated organic and distributed, a web-based distributed simulation system of cold roll forming computer-aided design is built, based on scientific analysis, the cost of tool designing is greatly reduced and the design risk is reduced, in addition , cold-formed product design has become more common, promoting the development of china’s own intellectual property rights of commercial simulation software.更多还原