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Challenges in determination of microscopic degree of cleanliness in ultra-clean gear steels

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Journal of Iron and Steel Research(International) 2022年第10期29卷 1583-1600页

作者： D.Fuchs T.Tobie K.Stahl gear Research Center(FZG) Technical University of Munich85748 GarchingGermany

Shot-peened,case-hardened gears can fail in the tooth root due to crack initiation below the surface of the steel matrix.Here,the crack is initiated at a non-metallic inclusion in the center of a so-called fisheye.This failure type can lead to a reduced endurance fatigue limit of the gears.It is for this reason that,over the last decade,much effort has been invested by steel manufacturers to reduce the non-metallic inclusion content of gear steels so as to mitigate or even completely prevent such crack initiation.These ultra-clean gear steels were achieved by various measures in the steel production process.However,as a result,the remaining non-metallic inclusions are inhomogeneously distributed in the steel volume in terms of both size and location.However,due to the inhomogeneity of ultra-clean steels,the question arose if the values derived according to the standards are still representative of ultra-clean steel batches.The results show that the standards can still be applied,but more effort must be applied.To determine the degree of cleanliness,six microsections are currently evaluated according to steel test specification(SEP)1571,method K.It is shown that an examination of 24 microsections starting from size class 0 seems beneficial to get more reliable and comparable results of the degree of cleanliness of these ultra-clean gear steels.In addition,it is shown that a high degree of cleanliness has been achieved for all steel batches investigated with the measures taken in the steel production process.

关键词： Degree of cleanliness Non-metallic inclusion Evaluation of inclusion SEP 1571 DIN 50602 Ultrasonic immersion testing Ultra-clean gear steel gear

Machinery fault diagnostic method based on numerical simulation driving partial transfer learning

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Science China(Technological Sciences) 2023年第12期66卷 3462-3474页

作者： LOU YunXia KUMAR Anil XIANG JiaWei College of Mechanical and Electrical Engineering Wenzhou UniversityWenzhou 325035China

Artificial intelligence(AI),which has recently gained popularity,is being extensively employed in modern fault diagnostic research to preserve the reliability and productivity of machines.The effectiveness of AI is influenced by the quality of the labeled training data.However,in engineering scenarios,available data on mechanical equipment are scarce,and collecting massive amounts of well-annotated fault data to train AI models is expensive and difficult.In response to the inadequacy of training samples,a numerical simulation-based partial transfer learning method for machinery fault diagnosis is proposed.First,a suitable simulation model of critical components in a mechanical system is developed using the finite element method(FEM),and numerical simulation is performed to acquire FEM simulation samples containing different fault types.Second,several synthetic simulation samples are generated to form complete source domain training samples using a generative adversarial network.Subsequently,the partial transfer learning network is trained to extract shared fault characteristics between the simulation and measured samples in the case of class imbalance.Finally,the resulting model is used to diagnose unknown samples from real-world mechanical systems in operation.The proposed method is tested on actual fault samples of bearings and gears obtained from a public dataset and experimental test rig available in our laboratory,achieving average classification accuracy of 99.54%and 99.64%,respectively.Comparison investigations reveal that the proposed method has superior classification and generalization ability when detecting faults in real mechanical systems.

关键词： finite element method generative adversarial network fault diagnosis partial transfer learning bearing gear

Theoretical analysis of nonlinear vibration characteristics of gear pair with shafts

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Theoretical & Applied Mechanics Letters 2022年第2期12卷 85-91页

作者： Tatsuhito Aihara Kensho Sakamoto Department of Mechanical Engineering Faculty of Science and EngineeringHosei University3-7-2 KajinochoKoganei-shiTokyoJapan

The circumferential vibration of a gear pair is a parametric excitation caused by nonlinear tooth stiffness,which fluctuates with meshing.In addition,the vibration characteristics of the gear pair become complicated owing to the tooth profile error and backlash.It is considered that the circumferential vibration of the gear pair is affected by the torsional vibration of the shafts.It is important to understand quantitatively the vibration characteristics of the gear system considering the shafts.Therefore,the purpose of this research was to clarify the nonlinear vibration characteristics of a gear pair considering the influence of the shafts using theoretical methods.To achieve this objective,calculations were performed using equations of motion in which the circumferential vibration of the gear pair and the torsional vibration of the shafts were coupled.The nonlinear tooth stiffness was represented by a sine wave.The influence of tooth separation was considered by defining a nonlinear function using backlash and the tooth profile error.For the numerical calculations,both stable and unstable periodic solutions were obtained by using the shooting method.The effect of the shafts on the gear system vibration were clarified by comparing the results in the cases in which the shaft was not considered,one shaft was considered,and both shafts were considered.

关键词： Nonlinear Vibration gear Chaos Shaft Tooth separation

A Fast Multi-tasking Solution: NMF-Theoretic Co-clustering for gear Fault Diagnosis under Variable Working Conditions

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 182-196页

作者： Fei Shen Chao Chen Jiawen Xu Ruqiang Yan School of Instrument Science and Engineering Southeast UniversityNanjing 210096China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

Most gear fault diagnosis(GFD)approaches su er from ine ciency when facing with multiple varying working conditions at the same time.In this paper,a non-negative matrix factorization(NMF)-theoretic co-clustering strategy is proposed specially to classify more than one task at the same time using the high dimension matrix,aiming to o er a fast multi-tasking solution.The short-time Fourier transform(STFT)is first used to obtain the time-frequency features from the gear vibration signal.Then,the optimal clustering numbers are estimated using the Bayesian information criterion(BIC)theory,which possesses the simultaneous assessment capability,compared with traditional validity indexes.Subsequently,the classical/modified NMF-based co-clustering methods are carried out to obtain the classification results in both row and column tasks.Finally,the parameters involved in BIC and NMF algorithms are determined using the gradient ascent(GA)strategy in order to achieve reliable diagnostic results.The Spectra Quest’s Drivetrain Dynamics Simulator gear data sets were analyzed to verify the e ectiveness of the proposed approach.

关键词： gear fault diagnosis Non-negative matrix factorization Co-clustering Varying working conditions

Dynamics of rolling mill drive system considering arc tooth gear dynamic characteristics

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Journal of Iron and Steel Research(International) 2019年第9期26卷 953-961页

作者： Ming Zhang Yan Peng Jian-liang Sun Hao-ran Li College of Mechanical and Equipment Engineering Hebei University of EngineeringHandan 056038HebeiChina National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004HebeiChina

The arc tooth gear spindle (ATGS) is the key structure of the drive system of hot finishing rolling mills. To investigate the dynamic characteristics of ATGS of the drive system of hot finishing rolling mills, a dynamic mechanical model of ATGS was established. The influences of dynamic displacement and dynamic torque on dynamic load (meshing force, additional torque and friction torque) were studied during the non-steady-state operation of ATGS. On this basis, a dynamic model of rolling mill drive system was established considering the arc tooth gear dynamic characteristics. The dynamic response of the drive system was simulated and analyzed. The results showed that the nonlinear characteristics of ATGS were obvious;the meshing force (PX and PZ) could restrain the increase in dynamic displacement, which reflected the positive stiffness of ATGS;there was a coupling among the vertical, horizontal and torsional directions in the drive system model considering the dynamic characteristics of the arc tooth gear;the vibration intensity of ATGS in the horizontal direction is greater than that in the vertical direction when the self-excited torsional vibration happens;the greater the axial inclination angle was, the more complex the vibration mode was, and the lower the stability of the drive system was.

关键词： Rolling mill Drive system Arc tooth gear Coupling model Dynamic characteristics

Dynamic characteristics of the planetary gear train excited by time-varying meshing stiffness in the wind turbine

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International Journal of Minerals,Metallurgy and Materials 2018年第9期25卷 1104-1112页

作者： Rui-ming Wang Zhi-ying Gao Wen-rui Wang Yang Xue De-yi Fu State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems China Electric Power Research Institute School of Mechanical Engineering University of Science and Technology Beijing

Wind power has attracted increasing attention as a renewable and clean energy. gear fault frequently occurs under extreme environment and complex loads. The time-varying meshing stiffness is one of the main excitations. This study proposes a 5 degree-of-freedom torsional vibration model for the planetary gear system. The influence of some parameters(e.g., contact ratio and phase difference) is discussed under different conditions of a single teeth pair and double pairs of teeth. The impact load caused by the teeth face fault, ramped load induced by the complex wind conditions, and the harmonic excitation are investigated. The analysis of the time-varying meshing stiffness and the dynamic meshing force shows that the dynamic design under different loads can be made to avoid resonance, can provide the basis for the gear fault location of a wind turbine, and distinguish the fault characteristics from the vibration signals.

关键词： wind turbine planetary gear time-varying meshing stiffness dynamic characteristics

Tribological behavior of coated spur gear pairs with tooth surface roughness

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Friction 2019年第2期7卷 117-128页

作者： Huaiju LIU Heli LIU Caichao ZHU Peitang WEI Jinyuan TANG State Key Laboratory of Mechanical Transmissions Chongqing University State Key Laboratory of High Performance Complex Manufacturing Central South University

Coating is an effective way to reduce friction and wear and to improve the contact-fatigue lives of gear components, which further guarantees a longer service life and better reliability of industrial machinery. The fact that the influence coefficient linking the tractions and stress components could not be expressed explicitly increases the difficulty of coated solids contact analysis. The complicated tribological behavior between tooth surfaces influenced by lubrication and surface roughness further adds difficulty to the coated gear pair contact problems. A numerical elastohydrodynamic lubricated(EHL) contact model of a coated gear pair is proposed by considering the coupled effects of gear kinematics, coating properties, lubrication, and surface roughness. The frequency response function and the discrete convolute, fast Fourier transformation(DC-FFT) method are combined to calculate the surface deformation and the subsurface stress fields at each meshing position along the line of action(LOA). The Ree-Eyring fluid is assumed to incorporate the non-Newtonian effect, which is represented in the generalized Reynolds equation. Influences of the ratio between the Young's modulus of the coating and the substrate on the contact performance, such as pressure, film thickness, tooth friction coefficient, and subsurface stress field, are studied. The effect of the root mean square(RMS) value of the tooth surface roughness is studied by introducing the roughness data, deterministically measured by an optical profiler.

关键词： coating gear elastohydrodynamic lubrication (EHL) surface roughness

Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission gear Train

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 148-161页

作者： Xiong Zhao Jun Ye Mengyan Chu Li Dai Jianneng Chen Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Key Laboratory of Zhejiang Transplanting Equipment Technology Zhejiang Sci-Tech UniversityHangzhou 310018China

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

关键词： Asymmetric transmission Scallion transplanting High-order gear Non-circular gear Planetary gear train

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

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Chinese Journal of Mechanical Engineering 2019年第4期32卷 85-93页

作者： Shiping Yang Yixing Ji Yulin Mo Tianyu Xia School of Mechanical Engineering Xiangtan University

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.

关键词： Interference fit Ring gear Prestressing,Tooth root flexural fatigue strength X-ray diffraction (XRD)