Equations for helical gears with pinion circular arc teeth and gear involute teeth

Abstract

In this paper, the theory of gearing and the concept of differential geometry have been applied to derive equations for helical gears with pinion circular arc teeth and gear screw involute teeth. The paper covers: (a) generation of conjugate gear tooth surfaces with localized bearing contact; and (b) derivation of equations for gear tooth surfaces and their unit normals.     

小角度空间交错轴变厚齿轮传动的啮合动态特性研究

为揭示小角度空间交错轴变厚齿轮副的时变啮合特性与非线性动态特性,在精确几何建模的基础上,建立了空间小角度交错轴变厚齿轮传动时变啮合模型,获取其时变啮合刚度与时变传动误差;考虑外部载荷与侧隙变化的影响,采用集中参数法建立了齿轮传动非线性动力学模型,对其系统非线性特征进行了仿真。结果表明外部载荷的增加直接导致了齿轮副啮合刚度、传动误差、动态传动误差和动态啮合力的增加,同时啮合刚度的增加使得系统共振频率增加;侧隙的增加使得系统在轻载下出现与单边、双边冲击耦合的突跳现象,在重载下双边冲击区域变大,动态啮合力增加。     

Errors on ratios of small numbers

Errors on ratios are discussed in the case of binomial and Poisson distributions; tables giving the upper and lower limits of the confidence region for a confidence level of 68.3% are provided for small numbers.     

Failure investigation of a truck diesel engine gear train consisting of crankshaft and camshaft gears

A failure investigation has been conducted on a diesel engine gear train consisting of a drive crankshaft and a driven camshaft gears that were used in a truck. The gears are made from a nitrided 42CrMo steel. Adjacent teeth fracture regions appeared on the gears after a service of 4.2 × 10⁴ km. Fractographic features indicate that multiple origins fatigue fracture was the dominant failure mechanism for the gear teeth. The crankshaft gear fracture first, followed by the camshaft gear. Low hardness in subsurface and core region of the nitrided crankshaft gear makes it difficult for the matrix to support the load by the engaged camshaft gear to lead to initiating the fatigue crack at the root fillet bearing the maximum tensile stress. The crankshaft gear is the component causing trouble for the failed gears train.     

基于双模齿轮的大排量齿轮泵的流场可视化仿真研究

 研究双模组合齿形齿轮泵的流量、压力特性.通过将不同模数的齿轮叠加组合,设计双模数齿形的主、从动齿轮,以增加齿轮啮合过程中的容积变化量,提高齿轮泵的排量,利用Fluent 对齿轮泵内液压流场进行了仿真,得出齿轮泵在启动和稳定工作状态下流场压力分布云图、速度分布云图和速度矢量图,并据此分析了齿轮泵流场的流态.结果表明:同体积下双模齿轮泵的输出流量是普通齿轮泵的16～33倍,该齿轮泵中大齿将流场分成不同压力区,且大齿两侧流体压力差较大,齿顶间隙处液体流动速度较大,说明齿轮泵径向泄漏较为严重,在泵的入口处存在涡流现象,会产生压力冲击,影响齿面的使用寿命．     

Analytical design method for beveloid gears with a small shaft angle and offset

Forschung im Ingenieurwesen - In addition to more sophisticated flank modifications, there is a discernible trend toward special gearing that is reflected in the increased use of beveloid...     

Virtual manufacturing of various types of gears and validation of the technique using rapid prototype

Virtual manufacturing of gears is carried out to illustrate the fairly complicated gear generation process and the associated simultaneous motions being provided to the gear blank and the gear cutter. An attempt has been made to capture the phenomenon of chip formation as well. Generation of various types of gears are shown employing two types of operation, one being use of a gear hobbing cutter having multiple cutting edges. As such validation of the virtual manufacturing technique is always a difficult task. Using rapid prototype technology, a novel approach is proposed to ascertain the efficacy of the virtual manufacturing process being followed. The methodology is quite general and can be used for validation of any other virtual manufacturing process as well.     

Design in small manufacturing companies in Scotland

This paper gives the results of a survey of small manufacturing companies in Scotland with reference to their managers' understanding of and attitudes towards design; their control of the product design/development process; the communication of design objectives within the firm and forward planning for new product development. The survey revealed a generally positive attitude to design in the companies visited and the crucial role of both suppliers and customers in ensuring the success of the design activity.     

Electrical characterization of small area devices for manufacturing

Uniformity of electrical performance is critical for thin film modules. The more uniformly that all areas of the module perform the better the overall efficiency will be. Total module performance tends towards the average of localized performance, skewed slightly lower by the width of localized performance distribution. Measurement of overall module efficiency does not give information about performance uniformity. Use of small area devices (SAD's) defined from the module allow standard electrical measurements including light and dark current-voltage (IV/JV) and quantum efficiency to be performed on a small scale. Data from these measurements allows mapping of electrical performance across the module. The structure of types of SAD's is discussed and some examples of efficiency data from JV measurements as used in the optimization of a thin film module manufacturing line are presented. Also a brief discussion of statistical analysis of the data is included.     

Minimizing gear friction with water-containing gear fluids

Forschung im Ingenieurwesen - Lubricants have a large influence on gear friction and therefore on gearbox losses and heat balance. Synthetic oils can exhibit significantly lower gear...     

计算机辅助铣齿,滚齿,磨齿工艺系统

根据齿轮加工需要，我们开发了该软件。本文介绍了系统的主要内容，详细推导了机床展角公式。     

Fracture analysis of fisheye failures in the tooth root fillet of high-strength gears made out of ultra-clean gear steels

Forschung im Ingenieurwesen - In shot-peened components, failures can be caused by a crack initiation below the surface at a non-metallic inclusion in the steel matrix. This...     

Self-lubricating gears with oil-impregnated sintered materials

This study shows the first results on the operating behavior of self-lubricating gears based on oil-impregnated sintered material. The term self-lubrication is referred to as oil that bleeds from the open-pored sintered gear and providing lubrication to the gear contact. Experiments were carried out at the FZG efficiency gear test rig. Thereby, the pinion was made of open-pored, case-hardened sintered steel and impregnated with oil, and the wheel was made of conventional case-hardened steel. The total loss in torque and the bulk temperatures of the pinion and wheel were measured for various operating conditions defined by load and circumferential speed. The mean coefficient of friction in the gear contact was derived from the torque loss measurements. Results confirm that self-lubricating tribological systems with oil-impregnated sintered materials can be transferred from model test rigs to gears. The mean coefficient of friction shows the order of magnitude of externally lubricated gears. The tooth flanks after test runs show partially noticeable wear. As the heat dissipation of self-lubrication is limited, bulk temperatures and thermal load limits influence operating behavior significantly. Further work will focus on understanding the mechanisms of the lubricant film formation of self-lubricated, highly-loaded EHL contacts and on extending the thermal load limits.     

Performance evaluation of family-based dispatching in small manufacturing cells

In many practical instances, the choice of whether to apply family-based dispatching or not can be decided per machine. The present paper explores the impact of the location of family-based dispatching, load variations between machines and routing of jobs on the flow time effect of family-based dispatching. These factors are explored in small manufacturing cells with and without labour constraints. An industrial case motivates the study. A simulation study is performed to assess the impact of these effects. The results show that shop-floor characteristics such as routing and load variation impact the decision where to locate family-based dispatching in manufacturing cells without labour constraints. By contrast, the effect of family-based dispatching is much less vulnerable to shop-floor characteristics in cells with labour constraints. Since workers are the bottleneck in these cells, it becomes less important at what machine the set-up time involving a worker is reduced. In general, there seems to be a trade-off between the positive effect of applying family-based dispatching at a (bottleneck) machine and the possible negative effect of the more irregular job arrivals at subsequent machines. The results further indicate that family-based dispatching is more advantageous in cells with labour constraints than in cells without labour constraints, when both types of manufacturing cells have comparable machine utilizations.     

基于制造工艺约束的数控插齿机中床身拓扑优化设计

为解决立式数控插齿机中床身的拓扑优化结果在工程上加工制造困难的问题,建立了带有制造工艺约束的拓扑优化模型,采用OptiStruct对中床身进行拓扑优化设计,得到了约束条件含有体积分数及同时含有体积分数和制造工艺的2种拓扑优化结果.对比分析了2种拓扑优化结果,表明基于制造工艺约束的拓扑优化设计的中床身结构有更好的铸造性能...     

Process planning for small batch manufacturing of sheet metal parts

The paper describes process planning for order-based small batch sheet metal part manufacturing. In this domain, general purpose CNC machinery and standard tools are being used. An example of a process planning system is given and some areas of special interest are discussed in more detail. Process planning for sheet bending and tolerance reasoning are important and intricate tasks within process planning, whereas abstractions in design and nesting are important due to their relations with other manufacturing functions. In general, manufacturing functions tend to become increasingly intertwined and traditional boundaries become blurred. Sheet metal industries, customers and suppliers alike, can benefit from this.