Performance improvement method for Nylon 6 spur gears

Plastic gears made of Nylon 6 are especially susceptible to failure due to extreme heat accumulation in the single tooth mesh area, which results in damage that consequently shortens gear teeth life and causes transmission errors. In this experimental study, the teeth width of plastic spur gears made of Nylon 6 were modified and investigated. The values of load sharing, F/b, in single and double tooth meshing areas were leveled by widening the single tooth zone along the meshing area, and the performances of both modified and unmodified gears were studied experimentally under three different loadings. It was observed that modified Nylon 6 gears exhibit lower tooth temperatures, which results in a decrease in wear rate as compared to unmodified gears. Consequently, teeth width modification helps to increase Nylon 6 gear performance.     

Identification of Single and Multiple Teeth Damage in a Gear Transmission System

Abstract

The main objective of this article is to identify single and multiple gear teeth damage based on vibration signatures analysis of experimental results and their comparison with those by numerical simulations. In this study, vibration signals are experimentally acquired for the case with no tooth damage to cases with multiple teeth damage using the controllable wear/damage gear sets in the 75-HP gear test rig. Vibration signatures for cases similar to the experimental studies are numerically simulated based on a two-spool rotor-bearing model connected by a set of meshing gears. The effects of the wear on the gear tooth surface are numerically represented by the phase change in the gear teeth mesh stiffness during both gear mesh engagement and disengagement. Results from both experimental studies and numerical simulations are examined and compared in the time domain, the frequency domain, and the joint time-frequency domain using the Wigner-Ville distribution (WVD). Based on results of this comparative study, general conclusions are drawn concerning the identification of single and multiple gear teeth damage and their effects in affecting the global dynamics of the gear transmission system.     

An investigation on the influence of modification parameters on transmission characteristics of planetary gear system

A new gear tooth modification model of planetary gear system was established by considering the characteristics of tooth longitudinal crowning modification and tooth profile modification. Using this model, the influences of modification parameters on the time-varying mesh stiffness, transmission error, contact spots and dynamic response of the planetary gear system were analyzed through numerical analysis. The results show that tooth profile modification can effectively restrain the mesh stiffness sudden variation in the single and double tooth alternation of both the internal and external mesh pairs, and significantly decrease the transmission error fluctuation. However, longitudinal crowning modification has no marked influence on mesh stiffness sudden variation or transmission error fluctuation. The tooth profile modification can significantly reduce the sudden variation of tooth surface load during gear mesh course. Longitudinal crowning modification can make the tooth surface load evenly distributed in tooth width direction. When the external meshing pairs are modified at the tooth profile individually, the magnitude values of main response resonance peaks of internal meshing pairs have a great reduction, but those values of external meshing pairs change slightly. In the case of tooth profile modification of the internal meshing pairs, the phenomenon is reversed. By contrast with tooth profile modification, longitudinal crowning modification has little influence on the resonance peaks of internal and external meshing pairs.

     

修形直齿轮的啮合干涉与啮合间隙

修形直齿轮因误差因素在齿对的啮入和啮出位置会出现啮合干涉或啮合间隙。本文利用齿对的啮合变形与齿廓法向修形量、齿廓误差的关系,推导了啮合齿对在啮合线的啮入和啮出位置所存在的几何干涉或啮合间隙,得到了啮合重合度小于2和3的齿轮副啮合齿对的最大干涉量或间隙量的计算表达式,为分析修形直齿轮的啮合状态和修正齿轮修形参数奠定了基础。     

Producing gear teeth with high form accuracy and fine surface finish using water-lubricated chemical reactions

A new method was investigated for high-accuracy fine finishing of gear teeth surfaces using a water-lubricated tribo-chemical technique. A pair of shaved gears with rather low surface roughness was rotated in water lubricant for 30 min so that the gear tooth surface contacting the mating tooth was ‘worn’ to a mirror surface and ideal tooth profile, due to the mechano-chemical mild erosion of the contact area. The wear rate was 2.0 μm per 20,000 meshings, corresponding to a wear of one atomic radius thickness per meshing. Oxidation of the steel surface by water molecules is proposed as the dominant wear process. Operation noise from the gear pair rotation was drastically reduced to lower than about 10–15 dB compared to conventionally machined gear surfaces (30 dB in average), as a result of the wear of the tooth surface to form a best-fit profile. The noise increased with further processing of the gear pair. Thus, there is an appropriate number of rotations for suitable surface wear treatment. This new and simple procedure for surface treatment assures saving in energy, and does not require expensive honing techniques or high-accuracy grinding tools.The wear mechanisms used in this process are discussed along with the application of the technique to other processes for precision finishing.     

含误差的直齿轮的齿廓修形

依据齿轮传动载荷与轮齿变形的关系,推导出定载荷条件下,修形直齿轮静态传动误差与齿对综合修形参数的关系表达式。提出含制造误差修形齿轮修形参数的确定原则:理论设计修形齿轮的最大综合修形量应能消除含误差齿廓轮齿在啮入和啮出位置产生的几何干涉,理论设计修形齿轮的静态传动误差应保持最小的变化。给出了合制造误差修形直齿轮修形参数的计算公式,阐述了相应的确定方法。系统动态响应计算表明该方法所获得的修形齿轮具有良好的减振效果。     

直线-圆弧齿廓内齿轮副啮合效率分析

经过齿形优化,用圆弧齿廓替代与直线齿廓内齿轮啮合的共轭外齿轮齿廓,利于解决内外齿轮硬齿面加工问题.就其啮合性能,提出了直线-圆弧齿廓内齿轮副啮合性能之一的重合度和啮合效率的计算公式,并进行了算例比较.结果表明,直线-圆弧齿廓内齿轮副的重合度小于同模数同齿数的渐开线齿廓内齿轮副;在仅探讨几何参数和啮合参数影响的情况下,直线-圆弧齿廓内齿轮副的啮合效率明显高于渐开线齿廓内齿轮副.     

渐开线直齿轮修形的有限元分析与研究

针对不同修形曲线对齿轮修形产生不同效果的问题,首先推导出了渐开线参数方程和修形曲线的齿廓参数方程,然后应用Pro/E建立了标准渐开线直齿轮与修形齿轮的三维模型,最后利用ANSYS Workbench的瞬态动力学模块对其进行了有限元分析;通过仿真得出了渐开线直齿轮和修形齿轮在啮合过程中的齿面接触应力的变化曲线.研究结果表明,在齿轮传动时的单双齿啮合交替时及啮入/啮出时,Walker修形曲线较直线修形曲线具有更好的修形效果,但同时两种修形曲线都导致了齿轮重合度的降低,增加了单齿啮合区,为修形齿轮的设计提供了数值实验依据.     

考虑磨损的直齿轮啮合刚度计算与分析

基于能量法和Archard磨损模型,提出了一种考虑磨损的齿轮啮合刚度数值计算方法.根据展成法原理,建立了精确的齿廓曲线方程.利用能量法计算齿轮单齿啮合刚度,并通过分段1阶傅里叶级数拟合获得齿轮总啮合刚度.以Archard磨损模型为基础,计算得到齿面法向磨损量与啮合点处压力角的关系.计算分析了不同磨损量对齿轮啮合刚度的影...     

基于热弹变形的圆柱齿轮理想修形曲线

提出一种求解圆柱齿轮理想修形曲线的方法，应用耦合热弹接触有限元技术，分析轮齿在齿间载荷分配、齿面压力分布、轮齿弹性变形、齿面摩擦、轮齿温度场、轮齿制造误差因素作用下齿轮传动的啮合刚度，尽可能真实地模拟运转过程中啮合轮齿的形态，确定轮齿的刚度变化规律，通过数值拟合寻求最佳修形参数，在此基础上，得到圆柱齿轮理想修形曲线。     

Study on development of polyamide gears for improvement of load-carrying capacity

In polyamide based gears, thermal damage of the gear tooth surfaces occurs during gear meshing due to accumulated heat in the tooth body. In the experimental study reported in this paper, polyamide gear teeth have been modified in order to distribute the generated heat on the tooth surface by means of drilled cooling holes at different locations on the gear tooth body. The main aims of this paper were to study the effect of cooling holes on the accumulated heat on the tooth surface and on the measured wear. It was shown that the drilled cooling holes on the tooth body decreased the tooth surface temperature and led to an increase in the load carry capacity and improved wear resistance. Geometrically modified gears have showed an improved service life and a decreased surface temperature.     

一种新型弦线转子泵

根据弦线转子副理论齿廓不满足互为共轭条件,但可始终在连心线上保持接触的特点,提出用理论齿廓的等距曲线作为实际齿廓,即采用滚子隔离的新型弦线转子泵,保证了每一瞬时只有一对轮齿接触,从根本上消除困油现象,而且使接触面之间的摩擦由滑动摩擦变为滚动摩擦,大大减小了摩擦力。推导出理论瞬时流量近似计算公式,同时利用“数形结合”的方法,说明该新型弦线转子泵瞬时流量近似恒定。通过分析液压力和转子啮合对弦线转子产生的径向力,并结合径向力的合成,得出可以通过选择合理的转子宽度和齿顶圆直径、缩小压油腔尺寸、液压平衡法三种方法有效的减小转子泵径向力,为日后推广该泵进入实用提供一定的理论参考。     

齿轮弯曲强度有限元精确分析方法研究

通过计算轮齿弹性共轭接触迹,确定齿轮在啮合过程中各个位置的压力角、齿廓接触长度以及接触位置等参数。并对ANSYS进行二次开发,制作了一个精确计算齿轮弯曲强度有限元分析的软件。运用此软件对相同参数的渐开线齿轮与点线啮合齿轮进行弯曲强度的有限元精确计算,得出点线啮合齿轮比渐开线齿轮弯曲强度提高11.7%的结论。     

RV减速器摆线轮磨损量的数值计算与分析

基于Archard磨损模型和Hertz接触理论为理论基础,将摆线轮齿廓啮合区域离散化,建立了摆线轮磨损的计算模型;根据该计算模型分析了各啮合点处滑动系数、磨损率、磨损量与啮合相位角之间的关系,并进行曲线拟合。结果表明,建立的数值计算方法可以实现对不同修形方法、不同尺寸、不同工况条件下摆线针轮齿廓磨损量的定量计算。     

活齿端面谐波齿轮啮合副受力状态的理论研究

活齿端面谐波齿轮是一种新型的空间活齿传动机构,不仅可以保留现有谐波齿轮传动的所有优点,而且可以大幅度地提高所传递的功率。文中首次分析了活齿端面谐波齿轮啮合副的啮合状态和法向力,研究了活齿前端与端面齿轮啮合副的啮合总面积的变化规律,并推导出了啮合副比压的计算公式,为这种新型传动装置的强度设计提供了可靠的依据。     

Investigation of the Thermal Behaviour of Non‐metallic Curved‐Face‐Width Spur Gears

This paper describes a curved‐face‐width spur gear, specially designed for manufacture from non‐metallic materials. The benefits of this gear are the higher contact ratio, bending and Hertzian contact resistance, and greater tooth stiffness compared to standard spur gears. A modified geometry is proposed for the gear tooth, the height of which varies along the gear face width. Due to the reduction in tooth height, in sections away from the gear centre, lower sliding friction is expected, with consequences for the gear's thermal behaviour. The complex gear geometry makes the design of a die difficult; therefore the gears were cut on a milling machine, using a special kinematic generation process and related equipment. The tooth flank profile, an involute or near involute in sections away from the gear half‐width plane, as well as the flank surface quality determined by the single‐cutter tool used for gear manufacture, influence the meshing condition, and can be detrimental to the thermal behaviour of the gear. Experimental tests were carried out to examine the influence of load and speed on the temperature of the curved‐face‐width spur gears with modified geometry. The measured temperature of the non‐standard gear is further compared with the predicted temperature of plastic standard spur gears of the same specification.     

齿面磨损对齿轮系统动态特性的影响

为研究齿面磨损对齿轮系统动态特性的影响,综合考虑齿轮齿侧间隙、传输误差、齿面磨损,采用集中参数法建立齿轮平移-扭转非线性动力学模型,分析齿轮的转速、运行次数对含有齿面磨损的齿轮传动系统动态特性的影响。结果表明:在啮合区域内,齿根处的齿面磨损量呈减小趋势,在节点处理论磨损量为零,齿顶处的齿面磨损呈增加趋势,齿面磨损量减小趋势大于增加趋势,整个过程中齿面磨损会造成啮合刚度的减小;存在齿面磨损时,过大或过小的转速都会使齿轮系统的振幅波动变大,幅值减小;当转速一定时,含有齿面磨损的系统随着运行次数的增加,振幅幅值会逐渐减小,传动的波动会加剧。     

A NEW,NON-LINEAR,ADAPTIVE, BLIND SOURCE SEPARATION APPROACH TO GEAR TOOTH FAILURE DETECTION AND ANALYSIS

Past condition monitoring techniques of gearboxes have utilised many different approaches such as time-series averaging, amplitude and phase demodulation, time–frequency distribution and wavelet analysis. Only recently have statistical approaches taken a hold in gear tooth failure detection. Non-linear adaptive algorithms for independent component analysis (ICA) have been shown to separate unknown, statistically independent sources that have been mixed in dynamic systems. This paper proposes the application of an information maximisation based blind source separation algorithm (a type of ICA) to gear vibration measurements. It is shown that the individual gear and pinion vibrations cannot be separated using the blind separation algorithm, but the learning curve of the updated parameter can be used to detect impulsive and random changes in the data. It is shown that the algorithm is capable of tracking the higher-order statistics of the meshing signature using a single measure. This results in a detection scheme that is shown to find localised damage in a single tooth failure, two adjacent teeth failures, two non-adjacent teeth failures and multiple adjacent teeth failures. This method does not need a priori information about the loading, speed or type of gear measured.     

直齿圆柱齿轮表面微凸起磨损的时变热效应弹流润滑分析

以渐开线直齿圆柱齿轮为研究对象,建立考虑表面微凸起的润滑模型,给出相应的膜厚方程.在以往表面粗糙度的研究基础上,对两齿面的表面微凸起在不同磨损程度下的热解进行数值分析.结果表明:齿面上的微凸起会明显影响齿轮间的润滑效果,会对齿轮齿面造成比微点蚀更大的损伤;对于两个表面均存在微凸起的齿面,齿面的磨合磨损主要发生于主动轮上时,相比发生在从动轮上,会减缓对齿轮啮合过程中压力冲击的影响,会使油膜的中心压力、膜厚等变化趋于平缓.