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     

齿轮冷精锻成形工艺的研究

研究了直齿圆柱齿轮的冷精锻过程，分析了毛坯形状、模具结构等因素对齿轮成形的影响。结果显示：大模数、高厚度的圆柱直齿轮室温精锻成形的关键是齿腔的完全充满，改变毛坯的形状对齿轮的填充性影响不大，通过改进模具结构可以在适当的变形力下，保证齿腔的填充。     

带运动可控式凹模的直齿轮精锻成形研究

为了改善直齿圆柱齿轮冷精锻成形时齿形上下角部充填情况,本文在对精锻成形阻力分析的基础上,提出了一种新的齿形凹模运动可控的直齿圆柱齿形精锻成形装置,通过弹性元件和定位销实现了精锻成形过程中齿形凹模不动、齿形凹模随冲头一起运动、齿形凹模先不动而后再运动以及齿形凹模先运动而后不动等多种运动方式。有限元模拟和实验研究表明:通过控制齿形凹模的运动方式,形成齿形凹模对成形角部充填的积极摩擦,有利于促进齿腔角部充填。     

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.     

浮动凹模对直齿圆柱齿轮精锻成形影响的研究

通过对直齿圆柱齿轮精锻成形充填阻力的分析,揭示了其上下角部难以充满的原因.改变浮动凹模的运动方式,可以改变变形区应力的分布情况,从而改变上下角部的充填情况.利用DEFORM-3D软件对上述结论进行了验证,证明了浮动凹模对角部充填的有效性.     

三种模具形式下直齿轮温锻精密成形研究

选取固定凹模柱塞模式、固定凹模约束分流模式和浮动凹模约束分流模式3种不同模具方案,对直齿轮温锻成形过程进行数值模拟。分析3种模式下齿轮的成形效果、等效应变分布和成形载荷等信息,确定了改善充填性和降低工作载荷的最佳工艺方案。对最优的方案进行工艺实验验证,实验结果与模拟结果基本吻合,从而为直齿轮温锻成形工艺的实用化提供了一定的理论依据。     

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。     

局部镦粗对直齿圆柱齿轮精锻成形的影响

为了减少直齿圆柱齿轮精锻成形力,通过对圆柱体镦粗时接触面上的压强分布规律的分析,发现毛坯中心的压强最大。这样,采用局部镦粗成形,载荷可相应降低。为此,设计了用于直齿圆柱齿轮精锻成形的局部镦粗实验方案,并通过DEFORM-3D对不同方案进行了模拟,验证了局部镦粗对直齿圆柱齿轮精锻成形的有效性。     

变形热对齿轮冷锻精度影响的数值模拟研究

在有、无变形热产生的条件下,采用刚塑性热力耦合有限元法,对冷精锻直齿圆柱齿轮成形过程进行了模拟,并且完成了直齿轮冷锻模具弹性变形和工件弹性回复的模拟。由模拟结果可知:变形热的产生及热量传导能对齿轮精度产生很大的影响;由于在不同温度下材料的膨胀系数以及弹性模量不同,在有变形热的条件下,成形力有所降低,模具弹性变形和工件弹性回复量增大。     

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。     

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

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

基于均衡思想高凸台圆柱直齿轮冷锻成形

利用浮动凹模和梯形槽分流法成形大模数高凸台圆柱直齿轮,存在上下凸台成形不同步,载荷偏大的问题.基于均衡思想,提出了改进的模具结构.通过在下模上增设一直径15 mm的半球台,对流入下凸台的金属进行约束.利用三维有限元仿真软件数值模拟齿轮成形过程,通过对材料变形的应变场、应力场、行程载荷曲线等规律的分析,确定改进后的模具结构,有利于均衡成形并降低成形压力.物理实验验证了仿真分析的结果.     

齿轮精密成形精整毛坯设计

根据被整形工件的大小,提出优化的冷整形量,据此来确定冷整形前坯料的大小和温热成形时模具的参数。     

精密齿轮快速高效模锻成形工艺研究

文章以铸态AZ91镁合金为成形材料,采用可进行一锻两件成形及自动脱模的实验装置,对带轮毂的精细直齿轮进行了成形实验,分析了不同加载条件(恒压下速度和恒加载速度并保压)对坯料的充型过程及充型效果的影响。在成形温度300℃、加载速度0.1kN/s、保压总载荷26kN、保压时间150s的工艺条件下,获得了充型良好、轮廓清晰的AZ91镁合金精密直齿轮零件。所研制的一锻两件自动脱模成形装置可以实现精密齿轮的快速高效模锻成形。     

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.     

A study on the forging of external spur gears: upper-bound analyses and experiments

In this study, the forging processes of spur gears have been investigated. The forging processes of spur gears have been classified into two types of operations, guiding one and clamping one in this investigation. Two types of forging have been analyzed by using upper bound method. The relative average punch pressure have been calculated and compared with each others for various modules and numbers of teeth on the forging of spur gears. The forging experiments were carried out with a commercial aluminum alloy. The predicted forging loads obtained by the present upper bound methods are shown to approximate to the experimental results at final filling-up stage. The forged parts obtained through the guiding type forging were compared with those obtained through the clamping type forging.     

直齿圆柱齿轮开放成形数值模拟

为了降低齿轮精密成形力,在对闭式镦挤成形齿轮分析的基础上,提出了直齿圆柱齿轮开放成形新方法,即开放式温镦挤-冷推挤复合成形工艺。用三维刚塑性有限元对闭式镦挤和开放成形两种直齿圆柱齿轮成形方法进行了数值模拟分析。结果表明,开放成形与闭式成形相比,可明显降低成形力,改善模具受力条件,提高成形工件的质量。并根据模拟所得载荷-行程曲线,计算出开放镦挤齿形变位系数为0.2时,成形力所作功最小,为“开放镦挤”齿轮凹模的设计提供了依据。     

Investigation into nitrided spur gears

The cold forging method has been widely used in industry to produce machine parts. In general, gears are produced by shaping or hobbing. One of the shaping techniques is precision forging, which has several advantages over hobbing. In the present study, cold forging of spur gears from Ti-6A1-4V material is introduced. To improve the surface properties of the resulting gears, plasma nitriding was carried out. Nuclear reaction analysis was carried out to obtain the nitrogen concentration, while the micro-PIXE technique was used to determine the elemental distribution in the matrix after forging and nitriding processes. Scanning electron microscopy and x-ray powder diffraction were used to investigate the metallurgical changes and formation of nitride components in the surface region. Microhardness and friction tests were carried out to measure the hardness depth profile and friction coefficient at the surface. Finally, scoring failure tests were conducted to determine the rotational speed at which the gears failed. Three distinct regions were obtained in the nitride region, and at the initial stages of the scoring tests, failure in surface roughness was observed in the vicinity of the tip of the gear tooth. This occurred at a particular rotational speed and work input.     

直齿圆柱齿轮冷挤压可控运动凹模成形工艺

为降低直齿圆柱齿轮冷挤压成形载荷和改善齿形角隅部分充填性,在分析直齿圆柱齿轮成形过程中金属流动特性基础上,提出了采用可控运动凹模的成形工艺。利用Deform-3D软件对此成形工艺过程中的金属流动规律、成形载荷、成形缺陷进行了数值模拟分析,并对该工艺进行了优化。分析结果表明,当凹模速度为冲头速度的1/2时,成形过程中齿形充填均匀、齿形角隅部分充填饱满,成形载荷最小,较传统单向挤压成形载荷降低了约20%。对优化后的成形工艺进行了成形试验研究,试验成形齿轮齿形饱满,无塌角缺陷,试验结果与模拟结果基本吻合。