Experimental investigation of the effect of lead errors on helical gear and bearing vibration transmission characteristics

The characteristics of gear meshing vibration undesgo change as the vibration is transmitted from the gear to the housing. Therefore, vibration transmission characteristics of helical gear systems must be understood before the effective methods of reducing gear noise can be found. In this work, using a helical gear with different lead errors, the gear vibration in the rotational direction and the bearing vibration are measured. The frequency characteristics of gear and bearing vibration are investigated and a comparson is also provided.     

Lubrication in helical gears

In this paper, a method to determine elastohydrodynamic film thickness in helical gears is developed by combining the Dowson-Higginson elastohydrodynamic lubrication (EHL) formulation with helical gear geometry and kinematics. Comparisons are made with traditional gear film thickness models. This analysis is then used to characterise the film thickness and lambda ratio in an automotive planetary gearset. Methods to measure surface roughness in fine-pitch gears are described.     

Influence of manufacturing errors on the dynamic behavior of planetary gears

Planetary gears are widely used in the transmissions of helicopters, automobiles, aircraft engines, etc. They have substantial advantages such as compactness and a large torque-to-weight ratio. In this work, a plane model of a planetary gear was investigated. The energetic Lagrange formulation was used to recover the equations of motion of the system. A modal analysis was performed, and the influence of gyroscopic effect in particular was scrutinized. The dynamic response was computed by an iterative spectral method. The excitation is induced by time-varying the gearmesh stiffness. The cases of a healthy planetary gear and one with the presence of eccentricity and profile error were compared. The influence on the transmission ratio was also studied.     

工况参数对船用斜齿轮动态性能的影响

以某型船用单级斜齿轮传动为研究对象,针对其工况复杂多变的特点,基于Abaqus/Explicit显式动态分析方法,建立了斜齿轮副有限元模型.对额定工况下齿根动应力进行了仿真,重点讨论了负载扭矩和主动轮转速等工况参数对齿根最大动应力的影响.结果表明：斜齿轮齿根最大动应力随着扭矩和转速的增大而接近线性增加,且不同齿面的齿根动应力的增加速率不同.研究结果对船用斜齿轮副的优化设计具有一定参考价值.     

Local fault detection in helical gears via vibration and acoustic signals using EMD based statistical parameter analysis

Gear is a vital transmission element, finding numerous applications in small, medium and large machinery. Excessive loads, speeds and improper operating conditions may cause defects on their bearing surfaces, thereby triggering abnormal vibrations in whole machine structures. This paper describes the implementation of empirical mode decomposition (EMD) method for monitoring simulated faults using vibration and acoustic signals in a two stage helical gearbox. By using EMD method, a complicated signal can be decomposed into a number of intrinsic mode functions (IMF) based on the local characteristic time scale of the signal. Vibration and acoustic signals are decomposed to extract higher order statistical parameters. Results demonstrate the effectiveness of EMD based statistical parameters to diagnose severity of local faults on helical gear tooth. Kurtosis values from EMD and that obtained from vibration and acoustic signals are compared to demonstrate the superiority of EMD based technique.     

Static/dynamic contact FEA and experimental study for tooth profile modification of helical gears

With the development of high-performance computers, the contact finite element analysis (FEA) method has become more and more popular for studying both the static and dynamic behaviors of gear drives. In this paper, a precise tooth profile modification (TPM) approach of the helical gear pairs is presented first. The type and amount of the TPM are accurately determined by the static contact FEA results. Then dynamic contact simulations for the helical gear pairs with and without TPM are, respectively, carried out to evaluate the effect of the presented TPM approach on vibration reduction. No additional assumptions and simplifications are required for the static and dynamic contact analysis models. Vibration comparison experiments are also carried out on an open power flow test rig. Both the simulated and experimental results show that the presented precise TPM of helical gears is effective on vibration reduction around the working load, and the dynamic contact simulation is effective in estimating the effect of the TPM on vibration reduction in the designing stage.     

船舶斜齿轮动力学分析和修形研究

针对齿轮啮合受到时变负载影响,引起齿面疲劳损失和冲击的问题,对齿轮动力学性能和修形进行了研究,首先利用ADAMS建立了刚柔耦合模型;然后基于不同修行方法,得到了修形前后的时变载荷曲线;最后应用ANSYS Workbench软件对多耦合齿轮传动系统进行模态分析,并利用瞬态动力学模块得到了修形前后齿轮啮合动态应力变化曲线。研究结果表明,在斜齿轮三齿和两齿交替啮合过程中,抛物线长修形传动性能优于圆弧短修形,可为齿轮动力学分析提供有效依据。     

Minimizing vibration in cylindrical spur gears

Recommendations are made for minimizing the excitation of vibrations in cylindrical spur gears. Mathematical simulation confirms their effectiveness.     

Transient meshing performance of gears with different modification coefficients and helical angles using explicit dynamic FEA

The gearbox, as the main part of power transmission of many mechanical systems, plays a critical role for the performance of the system. The transient meshing performance of the gears is dependent on their structural parameters like modification coefficient and helical angle among others. In this paper, the effects of modification coefficients and helical angles on the transient meshing performance of the gears are investigated using the method of explicit dynamic finite element analysis (FEA) in an energy point of view. The relationships between the transient meshing performance and modification coefficient or helical angle of gears are obtained by explicit dynamic simulation. The simulation results demonstrate that explicit dynamic FEA can be used for choosing these structural parameters in the design and manufacture of gears to enhance their transient meshing performance.     

粉末冶金斜齿轮系统振动频率响应分析

利用有限元法建立包含齿轮副、传动轴、轴承和箱体的齿轮系统完整的动力学模型。使用有限元分析软件 MSC.Nastran计算了在齿轮动态激励下粉末冶金斜齿轮系统的振动响应,并与38CrMoAl刚性齿轮系统进行比较。     

Load-related dynamic behaviors of a helical gear pair with tooth flank errors

This study focused on the effects of tooth manufacturing errors (MEs) on the dynamic behaviors of a helical geared system. The composite mesh error is introduced and calculated, which is taken as error excitation in the dynamic model. A combined finite element method (FEM) and analytical contact model is used to investigate the interaction of mesh stiffness and MEs. The dynamic model is developed based on the finite element method and its effectiveness has been verified. By introducing stiffness excitation and error excitation, the effects of mesh stiffness and MEs can be easily distinguished in the total excitation. The influence degrees of these two factors are obtained at different torque levels by simulating the quasi-static and dynamic responses of the system. The results show that the composite mesh error will have great changes under light load conditions, and larger dynamic factors as well as decreased resonance speed will be brought. The excitation produced by manufacturing errors is dominate in the total vibration excitation in a light loading, while the excitation produced by mesh stiffness is becoming the dominating one in a heavy loading.     

The large displacements and dynamic stability of springs using helical finite elements

The differential equations of Wittrick are extended to allow large displacements of the helix and consistent geometric stiffness matrices are presented. In an earlier paper the author has dealt with the linear treatment of spring dynamics but here an investigation of static and dynamic stability and non-linear wave propagation is offered. The performance of the method is measured by comparison with previously published work.     

AutoCAD下的斜齿圆柱齿轮三维模型系统的开发方法

介绍了在AutoCAD2000环境下，用Autolisp语言编程在计算机上建立斜齿圆柱齿轮三维模型的方法，它操作简便，造型精确，可大大提高设计效率。     

斜齿圆柱齿轮啮合刚度的一种简化计算

从直齿轮和斜齿轮数学模型的相似性方面入手,提出一种在已知直齿轮啮合刚度的基础上,确定相应斜齿轮啮合刚度的方法。     

Reduction of vibration in helical gearing

A method of mathematical modeling of the excitation of vibrations in the gear mesh of double helical gear and ways to reduce vibration in helical gearing are proposed.     

直齿锥齿轮齿形误差分析

直齿锥齿轮的齿形误差就是在齿形展开角范围内的基圆弧长最大误差,也就是渐开线上曲率半径误差,可据此得出齿形误差修正量的定量计算公式。