用对研法提高粉末冶金齿轮的精度

采用对研法研磨粉末冶金齿轮，消除烧结、热处理齿部变形，提高齿轮转动精度。     

粉末冶金零件加工研究进展

介绍了国内外粉末冶金烧结件加工的研究现状,对工艺参数优化、刀具磨损、已加工表面质量进行了详细分析,阐述了改善粉末冶金烧结件可加工性的措施:表面浸渗、添加易切削剂。分析了粉末冶金生坯加工时工艺参数对已加工表面质量的影响、生坯强度的提高以及生坯加工后的烧结件的力学性能。     

齿轮齿根部最佳过渡圆角的计算

研究齿轮齿根部过渡曲线的确定方法 ,给出了最佳过渡圆角的计算方法 ,为齿轮设计和加工时过渡圆角的确定提供了依据。     

粉末冶金铁基齿轮零件的光饰工艺

由于采用粉末冶金工艺制造机械零件具有一系列的优点,其应用范围正日益扩大,已广泛应用于家用电器、日用机械、食品机械、电动工具等各种机械中。粉末冶金齿轮是用模具压制成形,经烧结后,通过整形、浸油以提高精度、光洁度和耐磨性。烧结的齿轮由于阴模与模冲间的间隙多少都有一些毛刺和尖角,甚至由于表面粘有一些铁粉而使表面粗糙,这在齿轮的生产中都是难以避免的,影响到产品的美观、质量和精度。如用手工处理,不但效率低,而且效果较差。我们经过近几年在校办企业生产中对粉末冶金小齿轮进行了整批去毛刺和光饰加工,取得了良好效果。现对所使用的设备和工艺作一简要介绍。     

大功率发动机高性能粉末冶金油泵齿轮研究

通过对大功率发动机油泵齿轮使用状况的分析，进行了油泵齿轮的弯曲强度、接触疲劳强度和有限元分析计算；研制了高性能粉末冶金温压齿轮材料，与原采用的合金钢材料进行了摩擦磨损对比研究；采用粉末冶金温压旋转模模壁润滑方式压制了机油泵斜齿轮，与合金钢齿轮加工工艺、材料利用率和制造成本加以比较。进行了齿轮的轮齿折断试验、部件可靠性试验、整机耐久性试验，结果表明，在发动机全寿命周期内，所研制的粉末冶金温压斜齿轮耐磨性好、强度高，油泵供油量下降少，满足发动机各种工况的使用要求。     

用对研法提高粉末冶金齿轮的精度

采用对研法研磨粉末冶金齿轮 ,消除烧结、热处理齿部变形 ,提高齿轮传动精度。     

齿轮齿根过渡圆角的计算方法及控制的研究

齿根过渡曲线的曲率半径大小,影响渐开线起始圆直径和齿根强度.本文定量分析了齿轮齿根部最大过渡圆角的设计计算方法,采用欧拉一萨瓦里共轭齿面曲率的关系,从理论上建立了齿条型刀具的刀尖圆角与被切齿轮齿根圆角的对应关系,为齿轮设计和加工提供了理论依据.从工艺的角度,研究了粗切滚刀的刀尖圆角的设计及选用原则,以及磨削齿条的刀尖圆角与渐开线起始圆的相互关系.本文的研究对合理设计齿根圆角、合理设计和选用齿轮滚刀、精确修整齿轮磨削砂轮、保证渐开线起始圆直径,都具有实际应用价值.     

基于神经网络的齿轮根切特性仿真研究

根据齿轮加工的范成原理,采用共轭齿面曲率的关系,建立齿条型刀具齿顶圆角与齿轮齿根圆角的对应关系;运用神经网络的非线性映射特性建立齿轮模数和齿数与根切量的关系模型,仿真出齿轮齿数与根切量,齿轮模数与根切量的关系曲线。仿真曲线能直观的反映齿数和模数对根切量的影响情况,为齿轮设计和加工提供了理论数据。     

大模数整体粉末冶金高速刚滚刀应用研究

影响齿轮加工质量的因素很多,齿轮滚刀是齿轮加工的关键刀具之一,齿轮滚刀本身的性能、齿轮滚刀切削三要素对被加工的齿轮质量影响最直接,本文主要探讨了粉末冶金高速刚齿轮滚刀切削三要素对齿轮加工的齿面质量的影响.     

小齿轮自由研磨新工艺

奥－贝氏体球墨铸铁齿轮加工后,在齿轮的端面上很容易留下毛刺,去除这些毛刺常常需要二次加工;同时齿轮的锐棱需要整修,齿槽也需要光饰。粉末冶金小齿轮经过压制成型和烧结后,在其表面也会留下毛刺和尖角,有时齿轮表面由于粘有铁粉而使齿面变得粗糙;因此有必要对它们进行研磨抛光。由此我们进行了齿轮油浸自由研磨光饰抛光工艺的试验,通过试验证明此工艺可以一次完成齿轮表面去毛刺、去锐棱和光饰表面。此工艺不仅适用于小齿轮的光饰,也可用于其它零件的光饰,具有广泛的适用性,是一种高效的工艺加工方法。加工原理加工前,首先在…     

齿条型刀具基本齿廓的改进

为提高外啮合渐开线圆柱齿轮的齿根弯曲强度 ,针对齿条型刀具提出了减小刀具齿顶高并同时加大其齿顶过渡圆弧半径的改进方案。确定了在保证齿轮工作时不发生过渡曲线干涉且不改变齿轮有效齿面的前提下刀具的最小齿顶高系数 ,并建议在齿轮刀具标准中增加刀具齿顶高系数系列。     

齿根过渡圆角处应力的分析计算

分别用传统的材料力学的方法计算了在齿轮设计过程中，轮齿齿根处弯曲应力和在同样的条件下，用有限元方法分析了不同齿根过渡圆角齿形的齿根剖面上各点以及过渡圆角处各节点的应力值。此结果和方法为选择正确的应力集中系数，得到适合于各种具体场合的优化齿形以及进一步进行齿根过渡圆角的优化设计提供可靠的帮助。     

Antiwear performance of modern industrial gear oils

Thermally refined gears were tested under the effects of various modern industrial gear oils, viscosity 1SO VG 220. The wear of the gears was measured for each oil, including tooth surface roughness and the tooth fillet strain of the pinion. It is concluded that graphite additivated gear oil shows excellent wear resistance and surface roughness over sulphur-phosphorus and organic Mo compound added oils, as well as less iron oxide.     

Effect of surface treatments on the strength of carburized gears

This paper deals with effects of surface treatment on the bending fatigue strength of SCM415 carburized spur gears. The test gears are treated by the combination of shot peening, chemical polishing and electropolishing after carburization. The fatigue tests demonstrate that the strength is sensitive to the surface condition of tooth fillet and the removal of the nonmartensitic layer caused by decarburization is considerably effective in enhancing the strength. In the first part of this paper, the influence of surface treatments such as shot peening, chemical polishing and electropolishing on the strength enbancement for carburized gears are summarized and discussed. In the second part, the crack lengths are calculated from the fatigue test results for the carburized and surface-treated gears, and the effect of surface treatments is discussed from the view point of fracture mechanics.     

新型环面渐开线齿轮齿面生成和几何特性研究

环面渐开线齿轮是一种对安装误差不敏感,无须修形就具有良好啮合性能,并且加工便捷的新型齿轮。根据环面渐开线齿轮的加工原理,从产形齿条的齿面方程出发,推导了凸环面渐开线齿轮和凹环面渐开线齿轮的完整齿面方程;利用MATLAB编程计算出环面渐开线齿轮齿面上点的三维坐标值,生成了精确齿面,并在Pro/E中建立了齿轮的实体模型;基于齿面数学模型,通过计算仿真对环面渐开线齿轮的根切与尖化现象进行了分析,获得了环面渐开线齿轮的根切界限曲线、尖化初始点以及不发生根切与尖化现象的最大齿宽;根据已生成的齿面进行有安装误差条件下的齿轮接触分析,证明了环面渐开线齿轮对安装误差不敏感。       

齿根磨削台阶的分析与研究

精度较高的硬齿磨削齿轮获得了广泛的应用,但由于设计、刀具特别是热处理变形等原因,使得磨出的渐开线齿廓与齿根圆角不能光滑卸接,往往在齿根部位产生“接刀棱”或“磨削台阶”,据了解在生产中确实存在这类问题。本文通过对典型齿形“磨削台阶”的有限元计算和光弹性试验,对齿根“台阶”部位应力分布情况进行了分析和讨论,提出了相对圆角系数和相对应力集中系数的概念,以期控制台阶所引起的应力集中程度,使这类齿轮能在一定条件下可靠工作。文中对“台阶”和“接刀棱”处的应力分布情况进行了对比,并对如何使用带“台阶”的齿轮等问题进行了讨论。     

A study on the forging of spur gears

In this paper, the forging of spur gears have been analysed by using the upper-bound method. The tooth profile of the gear consists of an involute curve and a circular arc shaped fillet. A kinematically admissible velocity field is newly proposed. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, addendum modification coefficient and friction factor on the forging of spur gears. Some forging experiments were carried out with Al-2024 to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and those obtained from the experimental results.     

基于椭圆的渐开线齿轮齿根过渡曲线研究

渐开线齿轮齿根过渡曲线是影响齿根弯曲应力的重要因素.为提高齿轮的弯曲强度,提出了采用椭圆曲线代替延伸渐开线的等距曲线,基于坐标转换原理,求出椭圆曲线方程.并采用30°切线法求出椭圆过渡曲线齿形系数和应力集中系数,与标准刀具加工的齿根曲线进行比较,结果表明采用椭圆过渡曲线可以使弯曲应力降低15％.根据齿形法线法,反求出获得该椭圆曲线的滚刀刀顶曲线,为滚刀刀顶设计和实际加工提供了理论依据.     

Optimization of asymmetric spur gear drives to improve the bending load capacity

In a given size of symmetric involute gear designed through conventional approach, as the load carrying capacity is restricted at the higher pressure angle due to tipping formation, the use of the asymmetric toothed gear to improve the fillet capacity in bending is examined in this study. Non-standard asymmetric rack cutters with required pressure angles and module are developed to generate the required pinion and gear of a drive with asymmetric involute surfaces and trochoidal fillet profiles. The respective profiles thus generated are optimized for balanced fillet stresses that are equal and possibly the lowest also. For this study of optimization, several non-standard asymmetric rack cutters are designed to accommodate different combinations in the values of pressure angle, top land thickness ratio, profile shift, speed ratio and the asymmetric factors. However for any drive with a given center distance and a speed ratio, only two non-standard asymmetric rack cutters, one for the pinion and other for the gear are used to generate a required numbers of pinion and gear with different cutter shift values for the purpose of optimization. The influence of these parameters on the maximum fillet stress has been analyzed to suggest the optimum values of these parameters that improve the fillet capacity in bending. The optimization of the asymmetric spur gear drive is carried out using an iterative procedure on the calculated maximum fillet stresses through FEM for different rack cutter shifts and finally the optimum values of rack cutter shifts are suggested for the given center distance and the speed ratio of an asymmetric gear drive. Comparisons have also been made successfully with the results of the AGMA and the ISO codes for symmetric gears to justify the results of the finite element method pertaining to this study.     

多层模板粉末压制设备的研制

为了生产密度均匀、无裂纹的多台面粉末冶金零件，设计和制造了用于成形多台面复杂粉末冶金零件的多层模板粉末压制设备，并根据压制工艺要求设计了适用于该压制设备的控制系统。采用集成油缸驱动多层模架，多层模冲均能单独控制，可满足多台面复杂粉末冶金零件压坯的压制动作要求，改善了压坯的密度均匀性，避免产生裂纹。