Finite element analysis of prestressed die set in cold forging

An application-oriented finite-element approach to forging die structural analysis is presented in this paper. The die set structural analysis problem is formulated as a contact problem with both shrink fit and preloaded clamping considered, solved iteratively by a varying penalty method. The loading condition is extracted automatically from forging simulation. A predicted solution is compared with analytical one and two application examples are given, which show the applicability of the approach.     

The effect of shrink fitting ratios on tool life in bolt forming processes

Increasing the service life of cold forging dies with respect to fatigue is a key issue in the highly competitive tool manufacturing market. In industry, achieving a lower level of stress in a die insert is known to be preferable when deciding the amount of shrink fit for a stress ring. However, it was found that stress amplitude is a more significant factor in increasing the cold forging tool life with respect to high cycle fatigue. With higher shrink fitting ratios, undesirable pre-stresses were induced in the tool insert, resulting in an increased stress amplitude between the forging/extrusion and unloading/ejection stages in a bolt forming process that lowered the high cycle fatigue life of the die insert. In the present investigation, the effect of the shrink fitting ratio on the level of die stresses, including the pre-stressing due to shrink fitting, was numerically investigated for a two-stage hexagonal bolt forming and gear extrusion operation. The study shows that optimum values of the shrink fitting ratios tended to increase the high cycle fatigue life based on the level of the stress amplitude in the die insert.     

行星齿轮精锻工艺分析与试验研究

根据齿轮精度检验的指标,提出了精度控制需要注意的问题,并针对每个问题提出解决办法。在系统分析热精锻和冷锻成形过程中齿形、齿面、弹性变形及模具寿命等问题的基础上,确定了热精锻-冷精整工艺流程,完成了精锻件及热精锻模的设计。对不同坯料尺寸和镦粗比的热精锻工艺过程进行了试验研究,分析了坯料和镦粗比对齿形充满的影响。研究结果表明,采用直径小于分锥角小端直径的坯料,选定镦粗比1．5进行热锻成形,锻造的热精锻齿轮齿形、齿顶充满效果较好,冷精整后的齿形饱满准确,在对氧化铁皮进行彻底清理后,锻件表面质量良好。     

新型圆柱齿轮精锻模

提出了圆柱齿轮新型精锻模和挤压模结构 ,论述了齿轮精锻模齿形设计和加工方法。用新型精锻模在摩擦压力机上一次锻击 ,使圆柱齿轮完全成型 ,锻件无飞边。齿轮锻件经过退火和表面清理 ,用新型挤压模在液压机上挤压精整 ,显著提高了精锻齿轮精度和精锻模寿命     

从动螺伞齿轮精锻工艺与试验

精锻方法成形螺伞齿轮与机加工齿轮相比具有力学性能好、寿命长、材料利用率高等优点.本文开发了一种采用“镦粗—预锻—冲孔—终锻”流程成形从动螺伞齿轮的热精锻工艺方案,针对该工艺方案设计了中心分流的闭式精锻模具,利用有限元分析软件Deform-3D进行工艺流程数值模拟,得出填充情况、成形载荷、齿廓纤维流向等重要信息.在1000 t离合器式螺旋压力机上试制出直径为165mm的螺伞齿轮锻件,验证了工艺方案的可行性及有限元模拟的正确性,为螺伞齿轮精锻成形批量生产提供了借鉴.     

摩托车齿坯闭式温精锻模具及工艺

介绍了摩托车齿温精锻工艺及模具,针对精锻用模具在成形过程中的失效形式,经过对模具等效应力场的数值分析,给出了一种新的镶块模具结构,使其模具寿命大幅度提高,降低了摩托车齿坯的锻造成本。     

汽车差速器半轴齿轮新型锻模设计

论述了精锻汽车差速器半轴齿轮原模具结构存在的问题,改进了锻造工艺和锻件设计,设计了新型粗锻模和精压模.新型粗锻模的齿模设在上模,半轴凹模设在下模,坯料定位准确迅速,可实现无飞边粗锻;齿模与热锻件接触时间短,模具温升小,模具寿命高.新型精压模的上模设有顶件装置,锻件半轴的拔模斜度小,锻件半轴的金属敷料少.新型模具可显著提高模具寿命和生产效率,降低材耗和生产成本.     

精锻齿轮模具失效分析及对策

通过对精锻齿轮模具的失效分析，指出了影响模具使用寿命的主要因素，并选用４种典型齿轮进行精锻试验，推荐了两种适用于精锻齿轮用的模具钢及其热处理工艺。     

摆动辗压成形工艺CAD系统的研制

由于摆动辗压工艺比其它塑性成形工艺更为复杂,其工艺设计的难度和工作量也较大.摆动辗压成形工艺CAD的研制主要是提高摆辗工艺的设计效率和精度.以节油器内花键套为对象,建立了预制坯的体积计算模型及其结构设计模型,确立了摆动模的设计模型和凹模的力学分析模型,给出了摆辗工艺参数和力能参数的设计模型.在此基础上对摆辗成形工艺CAD系统进行了结构分析和功能分析,实现了预制坯、摆辗模具和摆辗参数的计算机辅助设计,设计效率可以提高60%以上,废品率降低25%以上,并结合实例得到了满意的设计结果.     

铁路货车钩尾框精密辊锻过程数值模拟

铁路货车钩尾框锻件为异形长轴类锻件,目前采用自由锻工艺制坯,效率低,质量差,大型自动辊锻机精密辊锻是一种优质高效的先进制坯工艺,用于钩尾框制坯有望取得良好的技术经济效益.以刚塑性有限元法为基础,利用Deform-3D软件对铁路货车钩尾框精密辊锻过程进行三维有限元模拟,揭示了钩尾框辊锻变形过程中金属的流动规律,分析了辊锻成形过程中各道次辊锻过程中模具受载荷情况,以及各道次辊锻过程中的辊锻力矩,为钩尾框精密辊锻工艺及模具设计提供了有效的参考依据.     

基于数值模拟的直齿圆柱齿轮精锻模具设计

基于三维有限元数值模拟分析，确定了直齿圆柱齿轮精锻新工艺成形的最佳方案，并设计了可同时实现预锻分流区一分流终锻新工艺和传统闭式镦挤工艺的实验模具。     

结构参数对弧齿锥齿轮精锻成形的影响分析

采用三维有限元数值模拟方法,研究了模数、齿数、螺旋角、压力角等主要结构参数对弧齿锥齿轮精锻成形过程的影响.结果表明,在齿轮其他结构参数不变的情况下,成形载荷及齿根等效应力随模数、齿数的增加而增加,而螺旋角和压力角的变化对成形载荷及齿根等效应力的影响较小.模拟结果可为弧齿锥齿轮精密成形工艺和模具设计提供依据.     

Design of forging dies for forming flashless ring gear blanks using finite element methods

In the forging industry today, advanced mathematical techniques such as finite element methods (FEM) are beginning to revolutionize the conventional trial-and-error methods for die design and forging process development. Cost reduction programs are being implemented to enable the forging industry to remain competitive in today’s market. Material reduction or weight savings in the quantity of metal required to make the forged part is proving to be a significant factor contributing to cost reduction. Production of ring gear blanks without producing flash reduces the input weight of metal needed to make the gear blank, thus providing cost savings on the forged part. The following paper discusses different approaches currently used to make flashless ring gear blanks. The paper also describes the application of the rigid-viscoplastic finite element code “ALPID,” developed by Battelle Labs, Ohio, in developing a hot forging process to produce flashless ring gear blanks. The metal flow simulations, using ALPID, provide a tool to design and develop die cavities for defect-free closed die forging processes for making flashless ring gear blanks. The forming loads from these simulations are then applied to the forging die and the stresses on the die analyzed using another FEM based stress analysis package (“IDEAS,” developed by SDRC, Ohio) to verify the die design for strength in the given application. Thus, finite element methods were applied in different aspects of forging die design.     

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。     

Investigation of the cold orbital forging process of an AlMgSi alloy bevel gear

Orbital forging is a metal forming process in which one of the dies performs a complex rocking motion. It ensures reduction in required load and allows for the cold forming of a workpiece. One of the mechanical parts formed by means of this technology is a bevel gear. However, a numerical analysis of orbital forging bevel gears is very difficult to perform due to the complex rocking motion of the die, which is confirmed by numerous works investigating the orbital forging process. In the present work, investigation results of the cold orbital forging of aluminum alloy bevel gears are presented. In contrast to other works devoted to the process, this study proposes a new procedure for forming bevel gears and the workpiece used has a shape which is different from the previously applied ones. The obtained results apply to both theoretical and technological aspects of orbital forging. The FEM simulation results have been successfully verified in laboratory conditions using the industrial PXW-100A press.     

基于SolidWorks的直齿圆柱齿轮精锻模设计

结合直齿圆柱齿轮精锻模的设计．介绍了利用SolidWorks软件完成模具设计的基本方法和一般步骤，并对所设计的直齿圆柱齿轮精锻模工作过程和特点进行了分析。     

回转体锻模CAD研究

通过一精锻件模具库软件的开发 ,对锻造工艺和回转体锻模的CAD开发进行了一些尝试。开发成果表明 ,通过对一典型锻件锻造工艺和锻模CAD的开发 ,可缩短锻造工艺和模具的设计周期 ,规范模具库的管理 ,有利于锻模的标准化和系列化     

Analysis of void closure in open-die forging

Void closure studies have been conducted numerically and experimentally for open-die forging processes. The plane-strain FEM analysis was compared with bite forging experiments in order to determine how well the plane-strain approximation predicted the material flow in open-die forging. In addition physical modeling with plasticine was used to compare the measured and calculated deformation of the internal defect. The FEM analysis was in good agreement with the experimental results. Correlations for the computed effective strain and hydrostatic stress to the void closure were then calculated. Simulations of a solid cylinder side pressed with flat dies, V-shaped dies, and FML dies were done to determine the effectiveness of these dies at consolidating internal porosity based on the calculated strain and hydrostatic stress at the center of the billet. The V-shaped dies were found to be the most effective among those investigated. However, the press load for the V-shaped dies was also the highest.     

叶片精锻三维有限元反向模拟脱模准则的确定

叶片精锻过程的预成形设计是提高叶片锻件质量和降低产品成本的一个极其重要的方面,基于有限元法的反向模拟技术能够从叶片终锻件形状反演出预成形毛坯形状。为此,本文介绍了有限元反向模拟的基本步骤,综述了确定反向模拟中边界节点脱模准则的方法。针对叶片精锻三维有限元反向模拟过程,提出用跟踪拟合修正的方法来确定边界节点脱模的时间序列,确定了反向模拟的脱模准则。将所确定的脱模准则应用到叶片精锻三维有限元反向模拟程序中,可得到合理的叶片预成形毛坯形状。     

螺旋伞齿轮闭式精锻模设计

介绍了螺旋伞齿轮闭式精锻新型模具结构,该模具采用浮动凹模和浮动模芯结构,锻件在2个凹模和2个模芯形成的封闭模腔中成形,生产的锻件无飞边。工艺试验表明:新型模具可显著降低锻压变形力、材料消耗和生产成本,提高了模具寿命和生产效率。