【作者】 王斌；

【导师】 郑建明；

【作者基本信息】 西安理工大学 ， 机械电子工程， 2009， 硕士

【摘要】 随着板翅式换热器制造工艺的不断发展,特别是一些新的加工技术的渗透,其应用范围越来越广。目前的加工主要有模具挤压、折叶、插翅、精密切割等方法,这些方法存在工艺复杂、掉翅、废品率高、成本高等问题。板式翅片作为强化传热的核心元件,其加工质量和结构的优劣直接影响着传热性能,因此,研究和探索翅片加工的新工艺具有很重要的意义。本文通过滚压工艺对板式翅片实现绿色加工,设计出有利于翅片成形的刀具,并对刀具和工艺参数进行优化。根据滚压过程中金属的流动特点,对以往的A型滚刀进行改进,设计出更加有利于金属流动,促进翅片长高的流线型滚刀。为方便刀具加工,建立了流线型滚刀的数学描述。针对A型滚刀,依据金属塑性成形过程中的体积不变原理,建立起理想状况下,翅片滚压成形的理论计算模型,并推导出成形过程中刀具滚压深度和翅片成形高度之间的函数关系表达式。通过对相同滚压深度时A型滚刀和流线型滚刀滚压面积的对比,引入修正系数k’,得到不同滚齿夹角下流线型滚刀滚压深度和翅片成形高度之间的函数关系,为今后滚压成形的理论研究提供参考。采用Deform-3D有限元软件建立了板式翅片滚压成形的仿真模型,实现了其成形过程的数值模拟；分析了两种不同形式滚压刀具,即斜壁式和直壁式滚刀在滚压过程中的流动速度场,等效应力、等效应变分布等特点。通过点追踪方法,研究了板式翅片滚压成形过程中金属的塑性流动规律；同时对两种刀具在四道次滚压过程中的受力特点进行了分析,为今后刀具的设计和改进提供参考和依据。在这些分析的基础上,得出直壁流线型滚刀是理想的滚压成形刀具。结合数值模拟技术和计算机智能技术,以翅片成形高度最高和垂直滚压力最小为优化目标,对翅片滚压成形过程中的刀具参数(滚齿夹角β)和重要工艺参数(摩擦因子f、滚压深度ap和滚压速度v)进行了优化。先借助神经网络思想,采用正交试验样本,训练BP神经网络,利用训练得到的优化参数和输出目标间的映射关系；再结合多目标遗传算法进行参数优化；最后得到了均匀分布的Pareto最优解集,通过定义满意度函数选出满意解,利用有限元模拟对优化结果进行了验证。利用自行设计安装的滚压设备,进行了纯铝的滚压试验。研究了不同滚压深度时翅片的成形高度,并对翅片不同位置点取样进行硬度分析。实验证明板式翅片滚压成形工艺在生产实践中是可行的,同时对试验中出现的一些问题进行了实际解决。更多还原

【Abstract】 With the development of manufacturing technology for the plate-fins heat exchanger, especially the application of some new manufacturing technology, its application range becomes more and more widely. At present, the manufacturing methods include the extruded, the fold fin, the crimped fin, the skiving and so on. These methods have some problems such as technical complexity, fins falling, high waster rate, high cost and so on. As core element of strengthened heat transfer, its advantage and disadvantage of processing quality and construction have direct influence on the heat transfer performance. Therefore, the research and exploration of new process for fins machining have very important meaning. With the rolling forming processing, plate-fins manufacturing is realized green machining. In this thesis, the tool is designed to be more benefit to fins forming, and tool parameter and process parameter are optimized.According to the characteristics of metal flow in the rolling forming, the previous A-type tool is improved, and the streamline hob that is more favorable for metal flowing and fins heightening is designed. In order to give convenience to tool processing, the mathematical description of streamline tool is established. For the A-type tool, theoretical calculation model of fins rolling forming under ideal conditions is established based on constant volume principle in the process of the metal plastic deformation, and the functional relationship formula between the rolling height and fins forming height is deduced. By comparing the rolling area of A-type tool and steamline tool in the same rolling height, correction coefficient k’is introduced, and the functional relationship about the rolling height and fins forming height of the steamline tool is obtained. It provides reference for the theoretical research of fins rolling forming in future.By using finite element software Deform-3D, the simulation model of plate-fins rolling forming is established, and the numerical simulation of forming process is realized. For two different kinds of tools:the one is vertical wall type, the other is inclined wall type, the flow velocity field, the distribution of equivalent stress and equivalent strain in rolling forming process are analyzed. The metal flow law of plate-fins rolling forming process is studied by using point tracking method. Meanwhile, the analysis on the loading features of the two kinds of tools during the 4 passes rolling forming process is performed, and it provides reference and basis for the design and improvement of tool. Based on these analyses, it is determined that the streamline tool with vertical wall is the suitable tool for rolling forming.Combining the technology of numerical simulation and computer intelligent, the tool parameter (hobbing angleβ) and important process parameter (friction factor f、rolling height ap and rolling velocity v) parameters in the fins rolling forming process is optimized with the highest of fins forming height and the minimum of vertical rolling pressure as the optimization objective. Firstly, by neural network, the neural network is trained using orthogonal experiment samples. Secondly, using the trained mapping relationship between input parameters and output target, the parameter optimization is carried out by connecting with the multi-objective genetic algorithm. Lastly, Pareto optimal solution set is obtained, and by defining satisfaction function, the satisfactory solution is get. The verification for optimization resultsit is made by the finite element simulation.Using self-designed and assembled rolling machine, the pure Aluminum rolling experiment is carried out. The fins forming height under different rolling height is studied. The hardness analysis is performed by sampling in different location point. It shows that the plate-fins rolling forming technique is feasible to production practice, and the problems in the experiments is solved.更多还原