【作者】 张华；

【导师】 胡自化；

【作者基本信息】 湘潭大学 ， 材料加工工程， 2009， 硕士

【摘要】 弧面凸轮机构具有负载扭矩大、精度高、体积小、重量轻、传动效率高等优点,在数控机床、包装机械等高速自动化设备上得到广泛应用。弧面凸轮是弧面凸轮分度机构上的重要传动零件,其形状复杂,精度要求高、加工难度大,在目前实际生产中,采用棒料经多道机械切削加工成形,加工余量大,加工的绝大部分时间消耗在粗加工阶段,材料利用率和生产效率低,且由于金属流线被切断而影响零件综合机械性能,工艺成本高,严重制约了该机构的推广。因弧面凸轮结构的复杂性,精加工离不开先进的数控加工技术,唯有在制坯中采用等温挤压工艺,尽可能减少切削加工余量,才能使弧面凸轮在制造成本、生产效率、综合力学性能、使用寿命以及批量生产等各方面取得突破性改善。因此,开展高效、高精弧面凸轮毛坯制造工艺研究显得尤为重要。为此,本文从提高弧面凸轮成形精度、材料利用率及生产效率出发,利用刚粘塑性有限元分析方法深入研究了弧面凸轮等温挤压成形工艺,并利用DEFORM-3D软件进行了三维刚粘塑性有限元分析与优化。具体研究工作如下:1)综述了国内外弧面凸轮制造、精密成形技术及有限元模拟技术的研究现状,提出了弧面凸轮等温挤压成形制坯工艺。2)针对弧面凸轮的形状特点及成形工艺要求,分析了闭塞式模具双向主动加载等温挤压成形工艺。3)采用DEFORM-3D软件对弧面凸轮等温挤压成形进行三维刚粘塑性有限元数值模拟,验证了等温挤压成形弧面凸轮的可行性,为模具设计和设备选用提供可靠依据。4)分析并优化了等温挤压成形的关键工艺参数:挤压温度、凹模形状、挤压速度、润滑及摩擦条件等,为合理选择挤压工艺参数提供了科学依据。综上,本文针对弧面凸轮毛坯制造采用等温挤压成形工艺,利用三维刚粘塑性有限元对成形过程进行了模拟和优化,将使弧面凸轮制造的后序加工余量明显减少,材料利用率和生产效率提高,制造周期缩短,成本降低,零件综合机械性能得到改善。更多还原

【Abstract】 Globoidal cams with load torque, and high precision, small size, light weight, high efficiency drive have been widely used in high-speed automation equipments such as the CNC machine tools and packaging machinery. The Globoidal cam is an important transmission part of Globoidal cam indexing mechanism, the complex shape and high precision caused the processing to be difficult, so in the current practical production of the Globoidal cams the bar is machined to shape by the use of multiple cutting operation, and the allowance for finish is large, the most of processing time is consumed in the rough machining stage, materials utilization and productivity efficency are very lower. As a result, the metal flow lines are cut off and the integrated mechanical properties of the part is impacted on, the high processing cost has seriously hampered the popularization of the mechanism. Due to the complexity of Globoidal cam structure, finishing can not be achieved without CNC machining technology, the isothermal extrusion process can be only applied for preforming in order to to minimize the cutting allowance as posssible, and gain a breakthrough improvement of manufacturing costs, productivity efficiency, comprehensive mechanical properties, service life, and mass production. Therefore, research on high efficiency and high precision preforming process of Globoidal cam appears to be particularly important.Therefore, proceeding from forming precision, material utilization and production efficiency in this paper, the Globoidal cam isothermal extrusion process is studied thoroughly by use of rigid-visco-plastic finite element method and 3D rigid-visco-plastic finite element optimization and analysis is carried out by use of the DEFORM-3D software.The detailed research work is as follows:1) The present situation about the globoidal cam manufacturing technology, precision forming technology and FEM simulation technology have been summarized. And an isothermal extrusion process was introduced for the globoidal cam preform.2) Aiming at the shape features and forming process requirements of the globoidal cam, isothermal extrusion forming process was analyzed with the blocking two-way active load-type mold.3) The isothermal extrusion forming for the globoidal cam was numerically simulated by 3D rigid-visco-plastic FEM of DEFORM-3D software, and verified effectively. The reliable laws was provided for die & mold design and equipment selection.4) The key process parameters of the isothermal extrusion were analyzed and optimized, including extrusion temperature, female die shape, extrusion speed, lubrication and friction conditions etc.. The scientific proof was provided for the preferred extrusion process parameters.In a word, the isothermal extrusion forming process was applied for globoidal cam preform, and was simulated and optimized by 3D rigid-visco-plastic FEM. The research work will enable the sequential allowance to be decreased significantly, the material utilization and productivity to be increased, the manufacturing cycle to be shortened, the cost to be reduced, and the comprehensive mechanical properties to be improved.更多还原