浮动凹模对带六边形孔的圆柱直齿轮冷精锻的影响

以带六边形通孔的直齿轮为例,通过有限元仿真软件DEFORM-3D对直齿轮冷精锻的几种浮动凹模工艺进行数值模拟,分析了浮动凹模工艺(凹模和上凸模以相同的速度下行)、浮动凹模配合轴分流工艺和浮动凹模预锻+浮动凹模轴分流终锻两步成形三种工艺的充填情况和载荷大小。研究结果表明,采用浮动凹模工艺锻件的充填情况较好,但是成形载荷较大;采用浮动凹模配合轴分流工艺,不仅齿形充填效果较好,而且能有效地降低成形载荷;采用浮动凹模预锻+浮动凹模轴分流终锻工艺的齿形充填效果较好,能显著地降低成形载荷。     

采用波形端面凸模的齿轮精锻工艺优化

采用数值模拟和物理试验相结合的方法，对直齿轮精锻工艺进行了分析。试验结果既说明此工艺方案可行，也验证了数值模拟的可靠性，为该工艺方案的优化设计奠定了基础。结合正交试验设计方法和数值模拟技术，以分流角、凸模成形角、反向凸模成形角和分流距4个模具设计的关键参数作为设计变量，以成形时所需工作载荷最小为优化目标，对工艺方案进行了优化。最后引入浮动凹模设计的思想，模拟了采用浮动凹模结构的优化方案的成形过程，采用浮动凹模的优化方案与传统方案和优化方案的模拟结果的对比分析发现，采用浮动凹模可以进一步降低工作载荷。     

新型拖拉机齿轮浮动式锻模设计

论述了拖拉机圆柱从动齿轮坯原锻模存在的问题,提出了新型锻模结构,锻模采用浮动模芯和浮动凹模结构,锻件在一个封闭环形模腔中成形,锻件无飞边,敷料减少80%,显著降低了材料消耗和生产成本.     

基于径向分流和浮动凹模耦合法圆柱直齿轮冷锻成形数值模拟研究

利用径向分流和浮动凹模耦合工艺对大模数圆柱直齿轮冷锻成形过程进行数值模拟分析,得到了该齿轮在变形过程中金属的流动规律和变形机理。模拟结果显示采用此工艺成形圆柱直齿轮既可以成形出完整的齿形,又能够显著降低成形力。对生产实践具有指导意义。     

挤压参数及模具结构参数对某大长径比铝合金零件冷挤压流变成形载荷的影响

代号为SD-L的大长径比铝合金零件采用冷挤压成形工艺,其挤压载荷直接与挤压参数相关.采用DEFRORM-3D软件对该零件冷挤压成形过程进行仿真模拟,在不同挤压速度v、摩擦系数f以及凹模拐角处圆角半径R下对该零件冷挤压成形过程进行了数值模拟研究,获得了成形载荷随挤压参数及模具结构参数变化的规律.结果表明:成形载荷峰值随着挤压速度和凹模拐角处圆角半径的增加而减小,摩擦系数的增加则会导致成形载荷峰值增大.     

离合器内齿轮包挤压成形工艺及实验研究

研究了在离合器上使用的圆柱直齿内齿轮的加工工艺,与当前使用的冷挤压法成形工艺的比较表明,该工艺克服了冷挤压成型齿时载荷大,模具凸模磨损严重,使用寿命短的缺陷,解决了直接冷挤压成形内齿轮中的产品质量一致性不够好的问题,得到了齿形饱满,端面平整的内齿轮,而且成形内齿与预挤分开,使带齿模具凸模寿命可得到延长,具有生产实用化的前景。     

直齿轮冷精锻齿端分流参数优化设计

采用数值模拟对直齿轮冷精锻呆用浮动凹模,以及浮动凹模．齿端上下分流两种工艺进行了对比分析。试验结果表明,浮动凹模一齿端上下分流可有效地降低工怍载荷,为该方案进一步优化设计奠定了理论基础。结合正交实验设计方法和数值模拟技术,以上下分流腔高、宽4个模具设计的关键参数作为设计变量,以成形时所需工作载荷最小为优化目标,对浮动凹模一上下齿端分流腔工艺进行了参数优化。     

圆柱斜齿轮冷锻成形工艺研究

针对圆柱斜齿轮冷锻过程中齿腔充填困难、成形载荷大、模具寿命低的特点,提出了局部加载冷锻圆柱斜齿轮新工艺。利用有限元软件对新工艺进行数值模拟,分析了工艺成形过程中速度场、等效应变等规律,并对比分析了闭式、轴分流和局部加载成形工艺的成形载荷。研究结果表明,局部加载成形工艺可以较好地成形圆柱斜齿,改善齿端部分的充填性能,可显著地降低成形载荷,为此类齿轮的冷锻工艺应用与生产实践提供了理论依据。     

内齿轮冷挤压工艺参数分析及模具寿命预测

采用刚粘塑性有限元法对盲孔内齿轮冷挤压成形工艺参数进行了分析,并预测了模具寿命.运用金属塑性成形软件DEFORM-3D,以275减速轴为研究对象,成形载荷为评价指标,就影响成形工艺的模具设计参数、齿轮特征和工艺条件进行分组建模分析.结果表明:凹模芈锥角、模数、齿数对成形载荷影响较大;工艺条件中摩擦系数对载荷的影响最大;而挤压速度对载荷的影响则不显著.最后基于Archard模型预测了模具寿命.分析结果对实际生产具有重要的指导意义.     

直齿圆柱齿轮的半精锻试验研究

本文比较了齿轮精锻工艺与半精锻工艺。分别用塑性泥和铅作模拟材料对直齿圆柱齿轮进行了半精锻试验，测定了精锻的变形载荷和锻件的顶出力，定量描述了锻件的充满程度。试验结果表明，采用浮动凹模设计，可改善模膛的充填性能，降低终锻变形力     

A Study on the Extrusion by a two-step process for manufacturing helical gear

Much research has been carried out in the manufacturing of helical gears by cold forging or by extrusion. Although cold forging is applied to some bevel, spur, and helical gears, problems in connection with the reduction forming load and tool life still make it difficult for these methods to be commercialized. In this study, focusing on reducing a load in forming helical gears, the extrusion of helical gears by two-step process is proposed. This process is composed primarily of extruding a billet to a spur gear and then twisting the previous spur gear extruded to a helical gear. Cylindrical billets of Cr-Mo steel(SCM 415) and aluminium alloy(Al60 series) were used as specimen materials for the experiments. The maximum loads obtained by upper-bound analysis and FEM are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. The newly proposed method can be used as an advanced technique that remarkably reduces the forming load and replaces the conventional forming.     

直齿圆柱齿轮冷精锻实用化工艺研究

以实用化为目标,对１５＾＃钢、４５＾＃钢、２０ＣｒＭｎＴｉ直齿圆柱齿轮冷精锻工艺进行系统研究,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和齿形模修正设计方法。     

Analysis and Optimization on Factors Affecting Forming Quality of Half Axle Gears Warm Precision Forging

Half axle gears is produced by precision forging popularly because of the advantages in minimum machining allowances, lower material consumption and good service properties. But the forming quality of precision forging is difficult to control. Many simulations and analysis of precision forging process were taken by previous researchers. But no concrete method is proposed to evaluate and optimize the forming quality of half axel gears. The primary purpose of this work is improving the forming quality of half axel gears by analyzing and optimizing the affected factors of forming quality. The enclosed-die warm forging process of half axle gears was developed, and a new type of die-set used on double action hydraulic press was brought forward. The main influential factors of precision forming quality were analyzed after the forming process had been simulated by using finite element method(FEM). These factors include die structure, web thickness and web position. A method used to evaluate the forming quality was established, which investigated the maximal forming load, the metal filling rate and the material damage factor. The FEM simulations of half axle gears precision forging were evaluated by this method. The results show that the best forming quality can be achieved when the punches were added with bosses, the web located at the middle plant of the gear, and the web thickness was 30 percent of the inner hole diameter. Verification experiments taking the above optimized parameters were performed on a 7.8 MN double action hydraulic press. The trial products were formed well. And their geometric precision meets the demand. The verification result shows that the optimization of the influential factors, according to the simulations and the evaluation method, can improve the forming quality. The new structure of precision forging die-set and the new evaluation method guarantee a high forming quality of half axel gears.     

齿轮冷精锻工艺预锻模具齿形优化设计

在直齿圆柱齿轮两步成形冷精锻工艺中 ,预锻模具齿形设计对改善材料填充性能 ,降低成形载荷具有重要意义。本文采用正交试验法与数值模拟技术相结合的方法 ,来解决预锻模具型腔优化设计问题。选取了描述预锻模具几何形状的 3个参数作为影响因素 ,以预锻终锻总载荷值为指标 ,通过有限元模拟分析来获得虚拟试验结果 ,最终确定预锻模具型腔几何形状参数的最佳值 ,为提高齿轮精锻成形质量提供有效依据。     

The prediction of maximum forging load and effective stress for different material of bevel gear forging

The manufacture of gears by applying hot or cold bulk forming processes is a quite widespread production method due to its well-known basic advantages such as material and time cost reduction and the increased strength of the teeth. However, the associated process planning and tool design are more complicated. In the precision forging of gears, the workpiece volume, the die design, the power requirement and careful processing are more critical than traditional forging technology. For complete filling up, predicting the power requirement is an important feature of the near net-shape forging process. In this paper, a finite element analysis is utilized to investigate the material properties such as yielding stress, strength coefficient and strain hardening exponent effects on forming load and maximum effective stress. The adductive network was then applied to synthesize the data set obtained from the numerical simulation. The predicted results of the maximum forging load and maximum equivalent stress of bevel gear forging from the prediction model are consistent with the results obtained from FEM simulation quite well. After employing the prediction model one can provide valuable references in prediction of the maximum forging load and maximum equivalent stress of bevel gear forging under a suitable range of material parameters.     

The forging of helical gears (I): Experiments and upper-bound analysis

In this paper, the forging of helical gears has been investigated. A punch and a die are tooth-shaped for the guiding type forging of helical gears. The punch compresses a cylindrical billet placed in a die insert. As a consequence the material of a billet flows into the tooth region. The forging has been analysed by using the upper-bound method. Kinematically admissible velocity fields have been developed, where an involute curve has been introduced to represent tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as modules, numbers of teeth, helix angles and friction factors on the forging of helical gears. Some forging experiments were carried out with commercial aluminium 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.     

准双曲面齿轮冷摆辗加工新方法及其数值模拟

针对目前准双曲面齿轮冷摆辗技术存在模具结构复杂、摆辗力相对较大等问题,提出了一种新型的冷摆辗方法。该方法简化了模具结构,采用局部线接触连续塑性成形。基于刚塑性有限元法基本理论,借助通用三维有限元软件DEFORM-3D对准双曲齿轮摆辗成形全过程进行了三维动态分析,研究了速度场量、接触区以及模具受力的分布和变化规律。研究结果揭示了准双曲面齿轮冷摆辗的变形规律。     

The forging of helical gears (II): comparisons of the forging processes

In this study, the forging processes of helical gears have been investigated wherein they have been classified into two types: the guiding type and the clamping types. These two types of forgings of helical gears have been analyzed by using the upper-bound method. New kinematically admissible velocity fields of the clamping-type forging of helical gears have been proposed, where an involute curve has been introduced to represent the tooth profile of the gear. The proposed velocity fields of the clamping-type forging of helical gears have been applied to the non-symmetric lateral extrusion forging and the result has been compared with the solution proposed by Plancak et al. [J. Mater. Process. Technol. 1992; 34:465–472]. Numerical calculations have been carried out to investigate the effects of various parameters, such as modules, number of teeth, helix angles and friction factors on the clamping-type forging of helical gears. For the forging of helical gears, the results of the upper-bound analysis of the clamping type have been compared with those of the guiding ones. Some experiments of the clamping-type forging were carried out with commercial aluminum alloy to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and the experimental forging load.     

半轴锥齿轮冷摆辗精密成形技术研究

通过对汽车半轴锥齿轮冷摆辗精密成形技术进行研究,重点剖析了半轴锥齿轮毛坯的锻造工艺、冷摆辗成形工艺参数的选择、模具结构设计、金属切削加工和表面最终热处理等一系列关键技术,结果表明,采用冷摆辗精密成形技术的半轴锥齿轮具有精度高、强度高、啮合性能好,齿轮模具寿命长,材料利用率高,生产成本低等优良性能.     

Multi-objective optimization of process parameters for the helical gear precision forging by using Taguchi method

Precision forging of the helical gear is a complex metal forming process under coupled effects with multi-factors. The various process parameters such as deformation temperature, punch velocity and friction conditions affect the forming process differently, thus the optimization design of process parameters is necessary to obtain a good product. In this paper, an optimization method for the helical gear precision forging is proposed based on the finite element method (FEM) and Taguchi method with multi-objective design. The maximum forging force and the die-fill quality are considered as the optimal objectives. The optimal parameters combination is obtained through S/N analysis and the analysis of variance (ANOVA). It is shown that, for helical gears precision forging, the most significant parameters affecting the maximum forging force and the die-fill quality are deformation temperature and friction coefficient. The verified experimental result agrees with the predictive value well, which demonstrates the effectiveness of the proposed optimization method.