Forging of helical gears: Upper bound analyses and experiments

In this paper, forging of helical gears has been investigated. The forging process of helical gears has been classified into two types of operations: guiding and clamping. The two types of forging of helical gears have been analyzed by using the upper-bound method. Kinematically admissible velocity fields have been developed in which an involute curve has been introduced to represent the tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters such as module, number of teeth, helix angle and friction factors on the forging of helical gears. Some forging experiments were carried out with commercial aluminum alloy to show the validity of the analysis. Good agreements were found between the predicted values of the forging load and those obtained from the experimental results.     

Precision forging of spur gears with inside relief

Conventional closed-die forgings as applied to the forging of spur gears require high forging pressure. In this paper, a precision forging technology has been developed for the forging of spur gears with alloy steel (SCM415). The technology developed includes two steps in the forging process. Well-shaped products are forged successfully using a lower forging pressure than that of conventional forging. The accuracy of the forged spur gear obtained by the new precision forging technology is set nearly equal to that of a cut spur gear of the fourth and the fifth classes in the Korean industrial standard.     

齿轮精密成形技术的研究

研究了直齿圆柱齿轮的冷精锻过程 ,分析了分流孔形状、成形工艺等因素对齿轮成形的影响。结果显示 ,选择适当的分流孔尺寸可以降低成形载荷 ,但作用不很明显。采用凹模运动方式可调的齿轮精锻法可以同时兼顾齿轮上、下角部的成形 ,利于齿轮的填充 ,降低成形载荷     

高精度直齿圆柱齿轮冷锻成形加工方法的研究

针对真齿圆柱齿轮冷成形难度大的问题,提出了闭式镦挤－－约束孔分流两步成形实用化工艺方案和基于变位理论的齿形凹模修正设计方法,并对１５、４５、２０ＣｒＭｎＴｉ钢质直齿圆柱齿轮冷精锻工艺进行了系统研究。研究结果表明,两步成形法是降低直齿圆柱齿轮冷精锻成形力的有效方法,提出的齿形凹模修正设计方法可获得较高的齿形精度。     

大模数高凸台圆柱直齿轮净成形试验研究

采用浮动凹模-梯形槽约束分流方法,设计了大模数高凸台圆柱直齿轮的闭塞式精密成形模具,对其成形过程进行了三维刚粘塑性有限元数值模拟,并进行了试验研究.结果表明,采用浮动凹模-梯形槽约束分流有利于降低成形力,且能得到良好的充填效果和齿轮外观精度及完整的金属流线.试验结果与有限元数值模拟结果能很好地吻合.     

直齿圆柱齿轮精锻成形工艺及三维有限元模拟

本文在齿轮分流锻造法的基础上 ,提出了闭式模锻———向内分流法两步成形的直齿圆柱齿轮的精锻工艺方案。采用三维刚塑性有限元法模拟了此工艺的成形过程 ,并且和传统的闭式模锻工艺进行了比较分析。从模拟结果可以看出 ,两步成形工艺不仅工作载荷低 ,而且齿形充填良好 ,是适用于直齿圆柱齿轮精锻的有效工艺方案。     

直齿圆柱齿轮精锻成形工艺改进及模拟分析

采用三维有限元方法,分析了中心分流法两步成形直齿圆柱齿轮精锻工艺。模拟了两种齿轮精锻工艺方案,通过对模拟结果的比较分析,得到了相对优化的工艺方案。结果可以看出,只在下模带凸台的工艺方案,使得上端部的齿形无法完全充满。改进后的工艺方案是,使上模带有与下模同样的凸台,从而更好地起到分流的作用,使得齿形充填良好。从本文实例中可以看出,有限元分析方法对提高锻造工艺设计水平具有显著作用。     

铝合金圆柱直齿齿轮精锻成形试验研究

为优化圆柱直齿齿轮的精锻工艺,用挤压成形工艺、浮动凹模及分流原理挤压成形圆柱直齿齿轮零件,并比较成形零件齿形的饱满程度,对实现圆柱直齿齿轮的精密模锻生产有一定的指导作用。     

直齿圆柱齿轮精锻工艺锻靠阶段的上限分析

本文利用上限法， 由有实验依据的上限流动模型， 建立了直齿圆柱齿轮精锻工艺锻靠阶段的动可容速度场， 获得了与实验结果吻合较好的上限解， 并利用该上限解分析了精锻时冲头直径、摩擦条件、凹模型式等因素对变形力的影响。研究结果表明： 采用活动凹模和终锻时开式模锻的精锻工艺方案，所需的单位流动压力约为屈服应力σｓ 的８７５ 倍；在齿根飞边区与上模或活动凹模间的摩擦磨损最严重； 改善模具的润滑条件， 可大幅度地降低变形力。     

Numerical and experimental study on new cold precision forging technique of spur gears

1　INTRODUCTIONGearsarewidelyusedinautomobilesandotherindustryfieldsasthemain partsoftransferringthemovementandenergy .Gearsaremainlymanufac turedbymetalcuttingorbyacombinationofconven tionalhotforgingwithmetalcutting ,whichisexpen siveandrequiresalotofmanufacturingtime .Becausenetshapeornearnetshapemanufacturingprocesseshavebeenpaidattentionstoinindustry ,theprecisioncoldforgingtechniquehasbeendevelopedtobeasanimportantmethodtomanufacturethespurgears .Theprecisionforgingofgearshasalotofa…     

直齿圆柱齿轮精锻力的上限解

利用上限法，由有实验根据的变形流动模式设计了直齿圆柱齿轮精锻终了时的动可容速度场，获得了实验结果吻合较好的上限解，表明所建立的动可容速度场是可行的．     

基于三维有限元模拟的直齿圆柱齿轮精锻新工艺方案设计

通过对中心分流法两步成形直齿圆柱齿轮不同模具形状参数的数值模拟，确定了模具的最佳形状尺寸参数。由数值模拟和试验研究的结果可知,新工艺改善了材料的填充性能，降低了成形载荷，是适用于直齿圆柱齿轮精锻成形的有效工艺方案。     

直齿圆柱齿轮精锻工艺研究

直齿圆柱齿轮精锻工艺正日益受到国内外业界的重视。但由于零件的几何形状复杂,影响因素多,成形难度大,直齿圆柱齿轮精锻成形规律的研究比较薄弱。本文从精锻成形工艺、研究方法、数值模拟研究等几个方面综合论述了直齿圆柱齿轮精锻工艺研究的发展现状与趋势。     

模具结构对齿轮成形性能的影响

研究了直齿圆柱齿轮的冷精锻过程 ,详细分析了模具结构对齿轮成形的影响。结果显示 ,增加适当高度的镶件对大模数、高厚度的圆柱直齿轮齿腔填充比较有利 ,增加芯棒可以降低齿轮成形载荷 ,但单位面积的成形力并未减少 ,且对齿轮的填充性影响不大。     

直齿圆柱齿轮净形成形技术研究

研究了高精度直齿圆柱齿轮净形成形的若干相关技术,提出了钢质直齿圆柱齿轮冷精锻约束分流两步成形工艺,并对净形成形中的凹模修正设计方法、模具材料和结构、软化及润滑等实际应用关键技术问题进行了探索,冷精锻２０ Ｃｒ Ｍｎ Ｔｉ钢直齿圆柱齿轮具有较高精度。     

齿轮温挤精密成形工艺数值模拟

为了降低齿轮的成形力,在研究闭式镦挤成形齿轮法的基础上,提出了一种新的直齿圆柱齿轮温挤径向导流——约束分流两步成形工艺方案,采用三维大变形弹塑性有限元法对以闭式镦挤和以温挤径向导流——约束分流两步成形方式的成形情况进行了数值模拟分析。得到了新工艺成形过程的应力分布图以及载荷——形成曲线。数值分析结果表明：约束分流成形与闭式成形相比可明显降低成形力,有利于金属的流动,保证了齿形充填良好,改善模具受力条件,提高成形工件的质量。     

圆柱从动齿轮坯新型锻模设计

论述了圆柱从动齿轮坯原锻模存在的问题 ,提出了新型锻模结构。使用新型锻模 ,锻件无飞边 ,敷料减少80 % ,显著降低材料消耗和生产成本     

直齿圆柱齿轮精锻技术的发展现状与趋势

文章从理论研究、工艺设计、质量和精度控制研究等几个方面论述了国内外直齿圆柱齿轮精锻技术的现状,并对其研究发展趋势进行了探讨。     

芯轴交换对直齿圆柱齿轮精锻成形的影响

为了降低直齿圆柱齿轮精锻成形载荷并防止终锻载荷急剧上升,在分析了圆柱体镦粗接触面上的压力分布规律的基础上,提出了芯轴交换技术,使坯料在镦挤时始终有自由流动的空间,并设计了实验模具和实验方案,通过Deform-3D对芯轴交换的模拟和实验研究,证明了芯轴交换技术在直齿圆柱齿轮精锻成形中对降低成形载荷的有效性.     

Effects of forging parameters on uniformity in deformation and microstructure of AZ31B straight spur gear

The effects of forging parameters on the deformation and microstructure distributions of as-forged straight spur gears were investigated by finite element (FE) simulation and statistical analysis method. Spur gear forging using the movable cavity die design was investigated by integrating the FE method with the microstructure evolution models for AZ31B magnesium alloys. The required inputs such as flow stress curves and microstructure evolution models, were obtained through the Gleeble thermal mechanical testing and quantitative metallography analysis method. Numerical simulation and experimental examination confirm that both the deformation and microstructure are non-uniformly distributed in the as-forged gears. Decreasing deformation temperature or increasing strain rate is beneficial to obtaining fine-grained microstructure but is harmful to the uniformity in deformation or microstructure. The level of the non-uniformity results from the complex shape of gear and the friction between the billet and dies, which is closely associated with the characteristics of flow stress curve.