CLASSIFICATION OF GEAR FAULTS USING HIGHER-ORDER STATISTICS AND SUPPORT VECTOR MACHINES

Gears alternately mesh and detach in driving process, and then workingconditions of gears are alternately changing, so they are easy to be spalled and worn. But becauseof the effect of additive gaussian measurement noises, the signal-to-noises ratio is low; theirfault features are difficult to extract. This study aims to propose an approach of gear faultsclassification, using the cumulants and support vector machines. The cumulants can eliminate theadditive gaussian noises, boost the signal-to-noises ratio. Generalisation of support vectormachines as classifier, which is employed structural risk minimisation principle, is superior tothat of conventional neural networks, which is employed traditional empirical risk minimisationprinciple. Support vector machines as the classifier, and the third and fourth order cumulants asinput, gears faults are successfully recognized. The experimental results show that the method offault classification combining cumulants with support vector machines is very effective.

Virtual System Solution of CNC Machine for Spiral Bevel and Hypoid Gears

A virtual computerized numerical control C CNC） processing system is built for spiral bevel and hypoid gears. The pre-designed process of the solution to locate the way of realization is investigated. A kind of combined programming method and principle of solid modeling are chosen. Multienvironmental programming thought and the inter-connected mechanisms between different environments are applied in the proposed system. The problems of data exchange and compatibility of modules are settled. Environment of the system is founded with object oriented programming thought. AutoCAD is located as the graphic environment. Matlab is used for editing the computation module. Virtual C ＋＋6.0 is the realization environment of the main module. Windows is the platform for realizing the multi-environmental method. Through establishing the virtual system based windows message handling mechanism and the component object model, the application of multienvironmental programming is realized in the manufacture system simulation. The virtual gear product can be achieved in the accomplished software.

VARIABLE INERTIAL DAMPER AND ITS APPLICATION IN ZERO-DRIVE GEAR HOBBING MACHINE

A variable inertial damper, whose viscous damping coefficient can be adjusted by changing the gap between inertia wheel and motor spindle, is designed in servomechanism of zero-drive hobbing machine and is directly attached on the motor spindle. The mathematical model of servo system with inertial damper is built. By using theoretical analysis and system simulation, it is demonstrated that the variable inertial damper with optimal damping coefficient and moment of inertia should lead to no resonance point in wider frequency range of exciting force. Therefore, its application in zero-drive hobbing machine makes this system not only achieve higher system stiffness to overcome load torque fluctuation, but also gain better stability.

Comparative Study of Novel Axial Flux Magnetically Geared and Conventional Axial Flux Permanent Magnet Machines

In this paper,a performance comparison between the novel axial flux magnetically geared machines(AFMG)and the conventional axial flux YASA machine is presented.The AFMG and YASA machines have the same stator construction in which segments are equipped with concentrated windings to form the stator.However,the AFMG machine has two rotors with different pole-pair numbers.Magnetic gear effect can be obtained to increase the torque density.The performance comparisons at no-load and on-load conditions are then studied by 3D-finite element analysis(FEM).Moreover,both machines are prototyped,tested and compared.

YK 7425 GEAR GRINDING MACHINE

This is a newly developed product,CNC gear grinding machine basedon original Y 7125 A large planargear grinding machine, produced by theQinchuan Machine Tool Works. It is chieflyused for grinding the involute tooth profilesof gear-shaping cutters, gear-shaving cuttersand master gears, and is also used for grindinghigh precision spur and helical gears. It issuitable for the departments of the automobiles,tractors, aircraft, machine tools and toolmanufacturing industries.

YKJS5132 Digital-controlled Gear Shaping Machine

The YKJS5132 digitalcontrolled gear shaping machine is made by the Hubei Yichang Yangtze Machine Tool Plant. Its main features are: The major movement adopts a gear shift device for stepless speed readjustment The number of cut stroke can be preset. Crude or fine processing uses automatic gear shift. The feedehain is short and stable. The cycle movement

YM7132A——GEAR GRINDING MACHINE WITH CONICAL GRINDING WHEEL

The YM7132A gear grindingmachine with a conical grindingwheel is used for grindingcylindrical spur and helical involutegears,especially for hardenedprecision gears of small andmedium sizes.

YKJ3180H Economy NC Gear Hobbing Machine

The YKJ3180H Economy NC GearHobbing Machine is a new variety,developed recently by the ChongqingMachine Tools Works to meet clients’demands. Its most prominent feature is its highproduction efficiency ( able to complete awork cycle automatically), high processingprecision (Grade 7 or higher according to theGB 10095) and its cost competitiveness. This product is used in the machinetool and machinery industries at automobiles,tractors, gears and gear box factories. It canbe used for processing spur gears and helicalgears, automatic radial feed wormwheels,tapered gears and crowning gears; so it isespecially applicable in factories usingcrowning gear couplings, such as metallurgy,mining, lifting transport and the chemicalmachinery.

YK7232——GEAR GRINDING MACHINE WITH WORM GRINDING WHEEL

The machine is used for precisiongrinding of hardened cylindricalgears with medium module inbatches for the industries ofaircraft,automobile,machine tool,gear box and various transmissiondevices.

Y9420 Gear Chamfering Machine

Y9420 Gear Chamfering Machine is ahigh efficiency machine tool designedby the Chongqing Machine ToolsWorks to meet market demand. The machineemploys the principle of cool extrusion anduses a special chamfering tool which drivesthe work piece to rotate and achievechamfering. It features no tool tracks and noburr on the ends. Multiple cutters can beused to process cluster gears, and thechamfering can be realized on either oneside of the tooth or on both. It is an idealpiece of equipment for automobiles, machinetools and gears manufacture to chamfer anddeburr disk type gears, spur and helical shaftgears and cluster gears.

Cutting Force Fluctuation Suppression and Error Homogenization of Noncircular Gear Hobbing Based on the Tool Shifting Method

The current research on noncircular hobbing mainly focuses on the linkage model and motion realization.However,the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing process.In this paper,a hobbing machining model with tool-shifting characteristics was proposed to solve the problems of cutting force fluctuation and inconsistency of tooth profile envelope accuracy at different positions of the pitch curve in noncircular gear hobbing.Based on the unit cutting force coefficient method,the undeformed chip volume generated by interrupted cutting was used to characterize the fluctuation trend of the hobbing force.The fluctuation characteristics of the cutting force generated by different hobbing models were compared and analyzed.Using the equivalent gear tooth and hob slotting numbers,an analysis model of the tooth profile envelope error of the noncircular gear was constructed.Subsequently,the tooth profile envelope errors at different positions of the pitch curve were compared and analyzed based on the constructed model.The transmission structure of the electronic gearbox was constructed based on the proposed hobbing model,and the hobbing experiment was conducted based on the selfdeveloped noncircular gear CNC hobbing system.This paper proposes a hobbing method that can effectively suppress the fluctuation of the peak and whole circumference cutting force and reduce the maximum envelope error of the whole circumference gear teeth.

YK7250 Gear Grinding Machine With Worm-Grinding Wheel

The YK7250 gear grinding machine with worm grinding wheel is manufactured by the Qinchuan Machine Tool Group Co., Ltd. in Baoji City, Shaanxi Province.

Stress-Induced Deformation of Thin Copper Substrate in Double-Sided Lapping

Double-sided lapping is an precision machining method capable of obtaining high-precision surface.However,during the lapping process of thin pure copper substrate,the workpiece will be warped due to the influence of residual stress,including the machining stress and initial residual stress,which will deteriorate the flatness of the workpiece and ultimately affect the performance of components.In this study,finite element method(FEM)was adopted to study the effect of residual stress-related on the deformation of pure copper substrate during double-sided lapping.Considering the initial residual stress of the workpiece,the stress caused by the lapping and their distribution characteristics,a prediction model was proposed for simulating workpiece machining deformation in lapping process by measuring the material removal rate of the upper and lower surfaces of the workpiece under the corresponding parameters.The results showed that the primary cause of the warping deformation of the workpiece in the doublesided lapping is the redistribution of initial residual stress caused by uneven material removal on the both surfaces.The finite element simulation results were in good agreement with the experimental results.

Experimental Research on the Surface Quality of Milling Contour Bevel Gears

Contour bevel gears have the advantages of high coincidence,low noise and large bearing capacity,which are widely used in automobile manufacturing,shipbuilding and construction machinery.However,when the surface quality is poor,the effective contact area between the gear mating surfaces decreases,affecting the stability of the fit and thus the transmission accuracy,so it is of great significance to optimize the surface quality of the contour bevel gear.This paper firstly analyzes the formation process of machined surface roughness of contour bevel gears on the basis of generating machining method,and dry milling experiments of contour bevel gears are conducted to analyze the effects of cutting speed and feed rate on the machined surface roughness and surface topography of the workpiece.Then,the surface defects on the machined surface of the workpiece are studied by SEM,and the causes of the surface defects are analyzed by EDS.After that,XRD is used to compare the microscopic grains of the machined surface and the substrate material for diffraction peak analysis,and the effect of cutting parameters on the microhardness of the workpiece machined surface is investigated by work hardening experiment.The research results are of great significance for improving the machining accuracy of contour bevel gears,reducing friction losses and improving transmission efficiency.

Research and Development on NC System of Gear-hobbing Machine based on Zero-programming Technology

By the analysis of roller gear processing technology, combining with gear meshing mechanism and motion relationship, models for rolling gear machining parameter and zero-programming are established. In this paper, the automatic generation technology of NC program for CNC gear machining process has been studied and the zero-programming system architecture of open CNC gear-hobbing machine has been presented. In the design and development of the system, human computer interaction, programming algorithm and the design of each function module have bean done. Application test shows that the expected design requirements have been achieved.

可实现连续分度加工的摆线圆柱齿轮研究

研究了一种可采用连续分度铣削法进行加工的摆线圆柱齿轮。与传统的圆柱齿轮不同,这种齿轮的轮齿沿其轴线方向呈摆线形。该齿轮具有承载能力大、传动平稳、无轴向力等特点;尤其是可采用连续铣削的加工方法,大大提高加工效率。摆线圆柱齿轮可采用圆盘铣刀加工,圆盘铣刀上装有可更换的刀片,同一模数的齿轮只需要一把盘铣刀,通过更换刀片可进行不同模数齿轮的加工。首先,基于齿轮啮合理论推导了摆线圆柱齿轮的数学模型,利用自行开发的计算软件生成离散齿面点,建立三维模型;然后,阐述了圆盘铣刀的几何设计和齿轮的加工原理;最后,从齿轮特性、加工效率和标准化生产3个方面说明了该齿轮的优势。研究为圆柱齿轮的设计和加工提供了新的思路和基础。

FZG齿轮试验机方法在齿轮油上的应用研究

齿轮箱设备所用齿轮油最为关键的性能是承载性能。常规理化测试不足以全面评价齿轮油的承载性能,因此国内外研究机构结合机械设备开发了许多评价齿轮油承载性能的试验方法。研究表明:简单的台架测试方法一般与设备实际工况相关性差,在齿轮试验台上使用指定几何结构的齿轮可以更好地表征齿轮润滑剂的承载性能。文章主要阐述了润滑剂对齿轮不同失效模式的影响,以及如何用适当的测试方法量化,并准确表征润滑剂的承载性能。

数控铣齿比能耗与工件粗糙度预测优化

根据铣齿机床能耗与工件表面粗糙度信息,提出一种结合多元非线性拟合和粒子群算法的预测优化方法,旨在为齿轮铣削提供优选工艺参数。基于数控铣齿机床动力结构建立能耗模型,进而提出铣齿切削比能的概念;开展正交和全析因试验对多工况铣齿机床的功率和表面粗糙度数据进行监测;通过多元非线性拟合函数建立机床切削比能和工件粗糙度的预测模型;将拟合目标函数组代入粒子群算法进行工艺参数的优化。试验结果表明,基于多元非线性拟合的预测模型拟合优度均超过了0.99,采用粒子群算法求解获得的8组解集考虑到了机床节能增效的客观需要。

金属钼圆基片平面研磨及其表面创成机理研究

目的实现金属钼圆基片高效平坦化加工,获得超光滑表面。方法采用游离磨料对钼圆基片进行平面研磨加工,研究磨料种类及研磨盘转速、研磨压力、研磨时间等工艺参数对研磨效果的影响规律,通过材料去除率(MRR)与表面粗糙度(Ra)的建模分析,对比钼材与高硬脆和高塑性材料,揭示其研磨工艺特性、探究其表面创成机理。结果钼圆基片材料去除快慢和表面形貌受各因素作用的综合影响。CeO_(2)磨料适合钼圆基片的研磨加工,材料去除方式为二体、三体摩擦塑性去除;在研磨过程中,MRR随研磨盘转速、研磨压力的递增而先增大后减小,在研磨盘转速为60 r/min、研磨压力为0.026 MPa条件下MRR达到最大;除磨料因素外,其他工艺因素对表面粗糙度的影响较小;MRR和Ra随加工时间的延长而趋于稳定;使用粒径W1 CeO_(2)磨料在研磨盘转速为60 r/min、研磨压力为0.026 MPa下研磨40 min后,表面粗糙度Ra由46 nm降至9.53 nm,MRR达1.16 mg/min。结论采用游离磨料研磨方法在优化工艺条件下可以有效降低表面粗糙度,获得良好表面。

面齿轮在机测量综合预行程误差补偿及齿面匹配方法

在机测量可在加工过程中实时测量,有效提高面齿轮的加工质量及测量效率。考虑面齿轮在机测量预行程误差对齿面精度的影响和齿面匹配精度低的问题,制定了基于蜗杆砂轮磨齿机的在机测量策略,将多种误差影响因素作为输入,测头综合预行程误差作为输出,构建基于PSO-CNN神经网络的综合预行程误差预测模型完成误差补偿。提出齿面精匹配方法,构建六参数优化模型使测量齿面与理论齿面进行匹配得到齿面误差。最后,测量实验结果显示,左齿面精度提高61.33%,右齿面精度提高71.15%,在机测量与克林贝格测量仪测量结果基本一致,满足面齿轮在机测量精度要求。