【作者】 张勇；

【导师】 周杰；

【作者基本信息】 重庆大学 ， 材料加工工程， 2003， 硕士

【摘要】 闭塞式精锻工艺属于金属塑性加工的先进工艺，齿轮精锻就是通过精密锻造直接获得完整齿形，且齿面不需或仅需少许精加工即可使用的齿轮制造技术。它有效地改善了齿轮的组织和性能。精锻使金属三向受压，晶粒及组织变细，致密度提高，微观缺陷减少；精锻还使金属流线沿齿形连续均匀分布，提高了齿轮的机械性能。且精锻齿轮的齿形精度能达到精密级公差、余量标准，工件只需少量精加工就可进行热处理，提高了生产效率及材料利用率，降低了生产成本，大大提高了齿轮制造的市场竞争能力。近年来，随着计算机技术的飞速发展，闭塞式精锻技术也取得了巨大的进步。本课题以半轴齿轮为例，先利用模具CAD技术对半轴齿轮进行三维实体建模，然后应用FEM模拟技术等对半轴齿轮的成形过程进行数值模拟仿真。分析了金属在成形过程中各种场变量的变化，预测金属流动趋势，并就不同的凸、凹模结构及形状尺寸、连皮厚度、连皮相对于齿轮端面距离等对半轴齿轮的成形载荷、金属流动情况（或充填性）以及模具寿命等的影响规律进行了研究，确定了最优的凸、凹模结构、连皮厚度以及连皮相对于齿轮端面的距离等工艺参数。并根据优化出来的结果设计出了一套合理的温精锻工艺和基于800吨双动液压机的模具。最后利用优化结果进行了实验，并将数值模拟结果与实验结果进行比较，得出了以下主要结论：改进凹模结构，在齿模大端尖顶处设置尖角，成形时该尖角可以起到容纳多余金属的作用，并确保齿廓面的完全成形；改进凸模结构，在凸模下端与顶杆上端加一大小、形状适当的凸台，可对毛坯产生一定的径向力，便于金属分流，更有效的改善了齿形的充填条件；合理的连皮厚度和连皮位置对齿形的充填也起着重要的作用，当连皮厚度t=0.3d，h=0.5H时，齿形的充满情况最好；锻件上小于φ25的孔，只要模具结构合理，锻出来更有利于齿形的充满。通过本课题的研究，将精密锻造理论，数值模拟仿真技术以及模具CAD/CAM技术结合起来，达到了提高生产效率、缩短产品开发周期、提高模具寿命、降低能耗和生产成本等目的。本课题的研究成果可以为其他锥齿轮的生产以及相关的模具设计提供理论和实践依据。更多还原

【Abstract】 Enclosed-die forging process is one of the advanced processes in the field of metal forming. Full tooth of gear can be obtained through precision forging process, and the tooth need no or little precision machining only. The structure and performance of gear can be improved effectively through this process. The process can make material depressed stress in three directions. So it can attenuate crystal grains, improve the density and decrease microcosmic defects. It can also make metallic fibre streamline of teeth more continuous and symmetrical, and lead to the improvement of mechanical performance of gear. The precision of gear shape can come to a very high level。The workpiece needs only a little of machining before heat treatment. The process increases productivity rate and use ratio of materials, decreases the cost of production. Therefore the competing ability of gears is improved greatly.During recent years, with the rapid development of computer technology, the technology of enclosed-die forging has achieved great progresses. In this research a kind of half axle gear was introduced, whose model was made by the CAD technology. The forming process of the half axle gear was simulated by FEM software. The transformations of the fields during the process of metal forming were investigated, the tendency of metallic flow was forecasted，and the rules how various items affect the forming load, metallic flow, the life of dies were discovered. The factors include the different structures of male and female die, web thickness, the distance between web and big-end face of gear, etc. And the most suitable die structure，web thickness and distance were made certain. A proper warm forging process and a die-set based on 800-ton double action hydraulic press were designed according to the result of FEM simulation. Finally some experiments were made. Contrasting the simulation result with the experiment result some conclusions were made: modifying die structure (setting a tip at the big-end of gear to hold unwanted material) can ensure the complete forming of the tooth; modifying male die structure (adding a dummy on the bottom of male die to produce a radial force helping to divide material flow) can improve the filling ability in the area of teeth; proper web thickness and wed position play an important role in the forming of gear (the proper values are t=0.3d and h=0.5H); If a hole with diameter less than 25mm on the gear should be forged by proper die structure, it even helps to metallic flow in the area of teeth.<WP=6>The theory of precision forging, technology of FEM simulation and mould CAD/CAM are integrated through this research, which helps to shorten developing period, prolong life-span of die, and cut down the cost, etc. The progeny of the research can provide accordance for other bevel gears’ producing.更多还原