Effects of Prestressing of the Ring Gear in Interference Fit on Flexural Fatigue Strength of Tooth Root

When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ring gear is in the preliminary stage, and the distribution rule of the prestressing and the influence of each parameter on the interference prestressing have not been derived. In this paper, based on the method of calculating the prestressing of the thick cylinder in interference fit, the ring gear is found to be equivalent to a thick cylinder, and the distribution rule of prestressing of the ring gear in the interference fit is inferred. Then, by modeling and analyzing the gearbox body and ring gear in the interference fit using ABAQUS, the distribution rule of prestressing the ring gear in the interference fit is obtained through a numerical simulation. Finally, the prestressing of the ring gear in the interference fit is measured using X-ray di raction, and the distribution rule of prestressing of the ring gear in the interference fit is obtained through analysis. Compared with the distribution rule of prestressing in theory, numerical simulation, and experiment, the theoretical distribution rule of prestressing is amended through a statistical method, and a more accurate formula of prestressing is obtained. Through the calculation of the stress and bending moment in the dangerous section of the ring gear through prestressing, the formula for checking the tooth root flexural fatigue strength in the interference fit prestressing is inferred. This research proposes a tooth root bending strength conditional formula for the inner ring gear of the interference fit, which serves as a guide for the design and production of the actual interference joint inner ring gear.

METHOD FOR PRECISE CALCULATION OF ROOT STRESS OF SPIRAL BEVEL GEARS

A method for precise calculation of tooth root stress of spiral bevel gears is presentedand developed. On the basis of the machine settings analysis, tooth geometry anaysis and loadedtooth contact analysis, by using the tooth surface distribution load from tooth load analysis, thecalculation model is established and the root stress is calculated by means of finite element meth-od. The method mentioned is verified by a tested gears example.

齿廓修形在降低齿轮箱啮合噪声中的应用

本研究旨在解决齿轮箱在啮合过程中由负载齿轮产生的啸叫问题。为解决这个问题,利用牛顿运动定律,建立一个齿轮副啮合的一维振动模型。在不改变齿轮基本参数的前提下,分别对齿轮齿顶和齿根进行修形。通过对比多种不同齿廓修形量的方案,计算齿廓修形量对齿轮强度及性能参数的影响,并根据齿廓修形量、修形长度和齿形公差绘制齿轮齿形检测的“K”形图。通过齿轮箱台架试验评估所提出的解决方案的有效性,证明齿轮啮合噪声的显著降低,从根源上改善齿轮啸叫现象。研究结果表明,齿廓修形是降低齿轮箱中齿轮啮合噪声的有效方法。

重载齿轮箱提高抗冲击载荷方法

主要探讨如何在有限的空间内提高重载齿轮箱的传动性能,延长齿轮箱的服役寿命。在不改变啮合齿轮副的传动特性情况下,经过齿根喷丸强化增加齿根许用弯曲应力值,通过改变齿轮副顶隙系数的情况下,降低齿轮弯曲应力值这两种方法提高齿轮抗冲击强度23%左右,极大提高重载齿轮箱齿轮副抗冲击载荷能力。

裂纹故障下的行星轮系唯象建模及其故障诊断

故障机制是故障诊断的基础,动态建模是研究故障机制的重要手段。现有的行星轮系动态建模主要包括动力学建模和唯象建模两方面。动力学建模难度大,且更多关注单个零部件的动力学特性;唯象建模则从宏观层面对系统特性进行描述。因此,建立行星轮系振动唯象模型,对行星轮系故障机制研究大有裨益。齿根裂纹是行星轮系中常见的故障类型之一。为此,建立了行星轮系正常与裂纹故障下的振动唯象模型,基于冲击动力学理论,计算了轮齿进入啮合时的啮合冲击力及其对动载因数的影响;在此基础上,建立了考虑啮合冲击影响的行星轮系振动唯象模型,得到了正常、太阳轮裂纹、行星轮裂纹等不同健康状态下的振动唯象模型响应;采用均方根、峭度等统计指标对模型响应进行分析,对比了各项统计指标在反映裂纹故障状态时的敏感性。结果表明,峭度可以作为有效反映行星轮系裂纹故障的指标之一。

行星齿轮变速器的动力学特性分析及设计

针对增速传动与减速传动下齿轮啮合特性存在差异的现象,建立了一套同时满足增减速载荷需求、不同侧隙的设计方法。选取经典的NGW行星齿轮系为对象,采用集中参数法和有限元相结合方式对不同转矩、侧隙下的齿根应力进行计算,对比分析增速传动和减速传动下各齿轮的弯曲应力。结果表明:受负载影响,太阳轮、行星轮的应力变化呈正相关、齿圈与二者应力变化呈负相关。增速设计时,行星轮系启动瞬间齿圈啮入冲击力最大,变形最大;随转矩增大,啮入冲击力增大趋势减缓。侧隙影响系统啮合状态,合适的侧隙能提高行星轮均载稳定性。为增、减速下参考侧隙的行星齿轮设计提供了数据参考,有利于优化设计。

裂纹故障下细高齿齿轮齿根动应变研究

为探究裂纹故障对细高齿齿轮齿根动应变的影响规律,采用集中质量法建立齿轮系统动力学模型,将故障下的时变啮合刚度作为输入,对系统动力学方程进行求解得到不同裂纹深度下的齿轮副动态啮合力。利用有限元法建立含裂纹故障齿轮结构动力学分析模型,结合轮齿承载接触分析确定裂纹故障下的齿间载荷分配关系,采用瞬态分析得到齿根应变时域历程,并对不同裂纹深度下的齿根动应变进行分析。仿真结果表明,当从动轮发生裂纹故障后,其齿根动应变故障特征主要表现为啮合区内齿根应变数值的变化,主动轮齿根动应变故障特征主要表现为齿根应变时域历程中出现周期性冲击及幅值衰减,在1.5 mm裂纹深度下主动轮齿根应变峰值因子相对变化量达到12.72%。

莲藕采摘收集清洗一体机的设计

【目的】解决莲藕采摘工作环境恶劣、效率低、成本高的问题,提高莲藕种植经济效益。【方法】在研究机械结构传动原理的基础上,设计了莲藕采摘收集清洗一体机。该一体机由冲刷装置、采集装置、传送装置、清洗装置组成,冲刷装置可以喷射高压水流冲刷莲藕,达到泥藕分离的效果;采集装置对漂浮在水面上的莲藕进行收集;传送装置通过传送带将莲藕传送到滚筒之中;清洗装置通过滚筒正反旋转外加滚筒内壁的细软毛刷实现对莲藕的清洗。【结果】该机构各个装置配合情况良好,系统结构稳定,可靠性高,无干涉现象,可一次性完成对莲藕的采摘、收集、清洗工作,节约了人力、物力,取得了良好的采收效果。【结论】该莲藕采摘收集清洗一体机能在提高莲藕采摘的工作效率的同时保证莲藕的优良品质,增加农户的收入,还能减少对土地的破坏,保护生态环境。

基于数值仿真的电动汽车高速齿轮轮辐结构优化设计

随着电动汽车对电驱动系统噪声、振动与声振粗糙度(Noise·Vibration·Harshness,NVH)性能的要求越来越高,对电驱动传动系统齿轮设计提出了更高的要求。基于数值仿真的方法对电驱动传动系统平行轴式减速器大齿轮轮辐结构进行了优化设计。从齿轮模态、齿根应力、传动误差和制造误差敏感性4个方面分析对比了简单板式、圆减重孔板式、长减重孔板式、加强筋板式和交错板式5种大齿轮轮辐结构设计。结果表明,交错板式轮辐结构在齿轮模态、齿根应力、传动误差和制造误差敏感性4个方面都具有优势,尤其在齿轮模态频率方面,相比其他4种方案有显著提升。采用所提方法优化设计的交错板式轮辐结构,在同等质量条件下相比常见的圆减重孔板式结构,齿轮1阶模态频率提高72%,传动误差降低18%,可有效避免大齿轮共振引起的高速齿轮啸叫问题。

Analysis of Stresses and Deflection of Sun Gear by Theoretical and ANSYS Method

Gearing is one of the most critical components in mechanical power transmission systems. This article examines the various stresses and deflection developed in sun gear tooth of planetary gearbox which is used in Grabbing Crane. Article includes checking sun gear wear stresses and bending stresses using IS 4460 equations. Also calculate various forces acting on gear tooth. In this study, perform the calculation for sun gear tooth to calculate bending, shear, wear & deflection using theoretical method. 3D model is created of circular root fillet & trochoidal root fillet of gear tooth for simulation using ProE Wildfire 3. In Pro-E, the geometry is saved as a file and then it is transferred from Pro-E to ANSYS 10 in IGES format. The results of the 3 D analyses from ANSYS are compared with the theoretical values. Comparison of ANSYS results in circular root fillet & trochoidal root fillet also carry out.

Profile Modification for Increasing the Tooth Strength in Spur Gear Using CAD

This paper examines the tooth failure in spur gears. Corrective measures are taken to avoid tooth damage by introducing profile modification in root fillet. In general, spur gear with less than 17 numbers of teeth had the problem of undercutting during gear manufacturing process which minimizes the strength of gear at root. In this study, a novel design method, namely circular root fillet instead of the standard trochoidal root fillet is introduced in spur gear and analyzed using ANSYS version 11.0 software. The strength of these modified teeth is studied in comparison with the standard design. The analysis demonstrates that the novel design exhibit higher bending strength over the standard trochoidal root fillet gear. The result reveals that the circular root fillet design is particularly suitable for lesser number of teeth in pinion and where as the trochoidal root fillet gear is more opt for higher number of teeth.

Investigation of the Effects of Profile Shift in Helical Gear Mechanisms with Analytical and Numerical Methods

In this paper, the effects of profile shift in cylindrical helical gear mechanisms have been investigated with numerical and analytical calculations. The mathematical model for computer simulation of gears has been designed and the numerical calculations have been carried out. Analytical calculations have been made with an excel program which was designed at different profile shift coefficients for a selected mechanism. Analytical calculations of the same mechanism have been verified by using ANSYS 14.5. The results of analytical and numerical solutions have been compared to profile shift coefficients.

根切齿轮齿根过渡曲线图解分析与计算

依据齿轮参数和几何尺寸,基于范成法加工齿轮原理,建立了根切齿轮齿根过渡曲线和轮齿渐开线的参数方程,准确绘制出根切齿轮齿形图;并用Matlab软件编制程序,精确计算了齿根最小弦齿厚和最大根切半径。为建立根切轮齿的有限元模型、量化分析根切齿轮齿根弯曲疲劳强度与变位系数的关系、确定根切齿轮的最佳变位系数、研究根切齿轮在工业生产中应用的可行性等提供了可靠依据。

考虑裂纹与磨损故障的齿轮传动系统动态特性分析

针对齿轮系统中同时出现裂纹与磨损故障时实现复合故障诊断较为困难的问题,提出了考虑齿廓磨损和齿根裂纹故障的齿轮传动系统动态特性分析模型。首先,基于Archard公式,建立齿轮传动系统磨损数值仿真模型,求解不同磨损周期下的齿廓磨损量;然后,通过势能法建立裂纹及磨损作用下的单齿啮合刚度计算模型,在双齿接触区考虑啮合齿对磨损量间的关系,结合变形协调,建立双齿啮合刚度计算模型;最后,采用集中质量法建立齿轮系统4自由度动力学模型,以含故障的时变啮合刚度为输入,使用Newmark-β法对动态响应进行求解,获得不同程度裂纹与磨损作用下的齿轮动态特性。实验结果表明:该模型能够较好反应复合故障中磨损与裂纹特征;与未考虑磨损后双齿区实际变形的裂纹与磨损复合故障模型相比,该复合故障模型双齿区刚度计算准确性提高了约22%,所提模型可为含磨损与裂纹的齿轮传动系统故障诊断提供有效的动力学补充。

航空齿轮激光冲击强化残余应力场仿真计算研究

对高强度航空齿轮齿根激光冲击强化数值仿真计算进行研究,提出激光冲击压力的数值计算方法,建立考虑激光入射角度的航空齿轮单齿的激光冲击强化有限元模型。仿真计算齿根处表层齿宽方向残余应力平均值为–603.97 MPa,与试验测得的齿轮齿根处表层齿宽方向残余应力数据平均值相差0.15%。通过仿真试验,揭示了齿轮齿根区域残余应力分布与激光脉冲能量、搭接率以及光斑半径之间的关联规律。结果表明,同深度层、齿宽方向残余压应力平均值大于齿廓方向残余压应力平均值。提高激光脉冲能量或搭接率均可提高表层残余压应力平均值,但提高激光光斑半径会降低表层残余压应力平均值;提高激光搭接率可以有效降低表层残余应力分布中的应力起伏现象,但过高的搭接率会大幅降低强化工艺效率,实际搭接率不应超过0.8。

成形磨齿齿根假性磨削台阶研究

给出了齿轮磨齿齿根假性磨削台阶的判定,分析了齿根假性磨削台阶产生的原因和消除假性磨削台阶的措施,同时明确了齿轮磨齿工艺应注意的参数。采取措施后减少了齿根假性磨削台阶的出现,保证了一次加工合格率,避免了返修,节省了加工时间,提高了生产效率。

基于纳米压痕技术的齿根渗碳层力学特征表征

18Cr2Ni4WA齿轮齿根的渗碳层具有不同于基体的力学特性,准确表征其力学特性对于研究齿轮齿根的裂纹萌生和疲劳性能至关重要。将纳米压痕技术作为渗碳层局部力学特性表征的试验手段,针对渗碳层开展纳米压痕试验,结合有限元仿真,根据不同本构参数组合下的载荷–位移曲线的曲率、残余深度、塑性功与总功之比3项参数预测的综合误差,确定18Cr2Ni4WA齿轮齿根渗碳层的本构参数。试验验证结果表明,由纳米压痕试验得到的载荷–位移曲线能够可靠地反映渗碳层的力学行为。

EXPERIMENTAL STUDY ON LUBRICATION BEHAVIOR OF DOUBLE ENVELOPING HOUK GLASSWOKM GEARING

The lubrication behavior of double enveloping hourglass worm gearing is studied experimently. The effects of rotational speed of the worm and load on the formation of the fluid film between engagement tooth surfaces are investigated in detail. and working angle of this worm gearing is also analyzed. Some beneficial results are obtained。

硬齿面齿轮齿根裂纹扩展特性与剩余寿命研究

为了研究齿根裂纹对硬齿面齿轮疲劳寿命的影响,以某渐开线硬齿面齿轮为研究对象,基于断裂力学方法和疲劳裂纹扩展理论,分析研究了齿轮齿根疲劳裂纹扩展机制;建立了考虑载荷大小、初始裂纹大小以及初始裂纹位置等因素影响的硬齿面齿轮齿根裂纹扩展剩余寿命分析模型,研究了齿根裂纹不同扩展阶段的应力强度因子演变规律与裂纹扩展机制;根据某渐开线硬齿面齿轮副弯曲疲劳试验数据,对所建计算模型进行了分析与验证,证明了模型的准确性。结果表明,与Ⅱ型裂纹、Ⅲ型裂纹相比,Ⅰ型裂纹应力强度因子最大,从齿面到裂纹深度方向,其值逐渐减小;随载荷、裂纹长度、裂纹宽度以及初始裂纹距齿宽中心位置的距离等因素的增大,裂纹扩展剩余寿命都随之减小。

齿轨列车地面齿条齿根的优化分析

文章简述立式齿轨系统的特征和坡度适用范围,针对立式齿轨系统中的Von Roll齿条,对比传统的齿条齿形,设计带齿根沉切圆弧的齿条齿形。并对2种齿形在不同齿根圆弧半径和齿轮齿条啮合高度情况下进行静态啮合仿真,获得齿条根部的拉、压应力曲线,针对设置齿根沉切圆弧和未设置齿根沉切圆弧齿条运用中出现的3种齿形参数情况,分析其动态啮合应力和动态啮合加速度情况。给出齿条设计中齿根圆弧半径大小和设置齿根沉切圆弧处理建议,可用于指导齿轨列车地面齿条的设计。