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Approximate-model Based Estimation Method for Dynamic Response of Forging Processes

Chinese Journal of Mechanical Engineering 2015年第3期28卷 565-572页

作者： LEI Jie LU Xinjiang LI Yibo HUANG Minghui ZOU Wei state key laboratory of high performance complex manufacturing Central South University

Many high-quality forging productions require the large-sized hydraulic press machine（HPM） to have a desirable dynamic response. Since the forging process is complex under the low velocity, its response is difficult to estimate. And this often causes the desirable low-velocity forging condition difficult to obtain. So far little work has been found to estimate the dynamic response of the forging process under low velocity. In this paper, an approximate-model based estimation method is proposed to estimate the dynamic response of the forging process under low velocity. First, an approximate model is developed to represent the forging process of this complex HPM around the low-velocity working point. Under guaranteeing the modeling performance, the model may greatly ease the complexity of the subsequent estimation of the dynamic response because it has a good linear structure. On this basis, the dynamic response is estimated and the conditions for stability, vibration, and creep are derived according to the solution of the velocity. All these analytical results are further verified by both simulations and experiment. In the simulation verification for modeling, the original movement model and the derived approximate model always have the same dynamic responses with very small approximate error. The simulations and experiment finally demonstrate and test the effectiveness of the derived conditions for stability, vibration, and creep, and these conditions will benefit both the prediction of the dynamic response of the forging process and the design of the controller for the high-quality forging. The proposed method is an effective solution to achieve the desirable low-velocity forging condition.

关键词： performance analysis forging process modeling hydraulic press machine

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Effect of nonlinear impact damping with non-integer compliance exponent on gear dynamic characteristics

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Journal of central south university 2014年第10期21卷 3713-3721页

作者：吴丽娟唐进元陈思雨 state key laboratory of high performance complex manufacturing.central south university)

A nonlinear impact damping model of single-degree-of-freedom spur cylindrical gear with backlash and time-varying stiffness was established. Systematic analyses of the dynamic responses were performed. First, the nonlinear damping coefficient was considered as a constant parameter with two types of compliance exponent, meanwhile, dynamic factors were adopted to depict the dynamic characteristics. Second, the bifurcation graphs were plotted, where the damping coefficient was obtained along with the impact velocity and coefficient of restitution. The results show that light and heavy load conditions have an effect on the responses when the compliance exponent is integer. On the contrary, when the compliance exponent is non-integer, the dynamic responses are slightly affected, namely the system is more stable than the former situation.

关键词： spur cylindrical gear nonlinear impact damping backlash non-integer compliance exponent

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Model-based parameter identification of comprehensive friction behaviors for giant forging press

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Journal of central south university 2013年第9期20卷 2359-2365页

作者：李毅波潘晴黄明辉 state key laboratory of high performance complex manufacturing (central south university)

A new experimental apparatus was set up to investigate the actual fi-iction characteristics on the basis of speed control of the serve system.A modified friction model was proposed due to real time varying deformation *** approach to identify the parameters of comprehensive friction behaviors based on the modified model was proposed and applied to the forging *** impacts on parameters which the external load had were also *** results show that friction force decreases with velocity in the low velocity regime whereas the friction force increases with the velocity in the high velocity regime under no external *** is also shown that the Coulomb friction force,the maximum static friction force and the vicious friction coefficient change linearly with the external load taking the velocity at which the magnitude of the steady state friction force becomes minimum as the critical velocity.

关键词： friction forging press modified model LuGre model parameter identification

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Method for Improving Transverse Wall Thickness Precision of Seamless Steel Tube Based on Tube Rotation

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Journal of Iron and Steel Research International 2015年第10期22卷 924-930页

作者： Yong-zheng JIANG Hua-ping TANG state key laboratory of high performance complex manufacturing Central South University

The tube rotation method （TRM） refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass rolling. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the influence mechanism of the TRM, the finite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip flow between two fix places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.

关键词： seamless tube stretch reducing transverse unevenness tube rotation method

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Effect of static transmission error on dynamic responses of spiral bevel gears

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Journal of central south university 2013年第3期20卷 640-647页

作者：唐进元胡泽华吴丽娟陈思雨 state key laboratory of high performance complex manufacturing (Central South University)

The effect of static transmission error on nonlinear dynamic response of the spiral bevel gear system combining with time-varying stiffness and backlash was ***,two different control equations of the spiral bevel gear model were adopted,where the static transmission error was expressed in two patterns as predesigned parabolic function and sine function of transmission *** dynamic response,bifurcation map,time domain response,phase curve and Poincare map were obtained by applying the explicit Runge-Kutta integration routine with variable-step.A comparative study was carried out and some profound phenomena were *** results show that there are many different kinds of tooth rattling phenomena at low *** the increase of speed,the system enters into stable motion without any rattling in the region(0.72,1.64),which indicates that the system with predesigned parabolic function of transmission error has preferable capability at high speed.

关键词： spiral bevel gear static transmission error dynamic response bifurcation

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Integrity of grinding face-gear with worm wheel

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Journal of central south university 2016年第1期23卷 77-85页

作者：唐进元崔伟周恒尹凤 state key laboratory of high performance complex manufacturing (central south university) Changsha 410083 China

Aiming at the issue of the grinding integrity of face-gear with worm wheel, the envelope mathematical model of shaper, worm wheel and face-gear is established based on theories of differential geometry and gear mesh. The judgment of completely grinding the face-gear with the avoidance of singularities is established, and the mathematical expression to show the reason why singularities appear is derived, through the research on the surface contact area and singularity rules of the worm thread surface. The disadvantage of current face-gear grinding method that only part of the working surface of the face-gear can be covered is analyzed and the influence of coefficient of judgment is studied through changing the design parameters.

关键词： face-gear surface contact area singularity of worm integrity of tooth surface

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New method for calculating face gear tooth surface involving worm wheel installation errors

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Journal of central south university 2017年第8期24卷 1767-1778页

作者：崔伟唐进元 state key laboratory of high performance complex manufacturing.central south university) Changsha 410083China

The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive the equation of face gear error tooth surface by assuming the tool surface as the error surface, where actual tool installation position error is introduced into the equation of virtual shaper cutter. Surface equations and 3-D models for the face gear and the worm wheel involving four kinds of tool installation errors are established. When compared, the face gear tooth surface machined in VERICUT software for simulation based on this new method and the one obtained based on real process(grinding face gear by using a theoretical worm wheel with actual position errors) are found to be coincident, which proves the validity and feasibility of this new method. By using mesh planning for the rotating projection plane of the face gear work tooth surface, the deviation values of the tooth surface and the difference surface are acquired, and the influence of four kinds of errors on the face gear tooth surface is analyzed. Accordingly, this work provides a theoretical reference for assembly craft of worm wheel, improvement of face gear machining accuracy and modification of error tooth surface.

关键词： face gear grinding worm wheel installation errors VERICUT error analysis

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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

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Numerical Simulation and Experimental Study of an Ultrasonic Waveguide for Ultrasonic Casting of 35CrMo Steel

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Journal of Iron and Steel Research International 2016年第8期23卷 772-777页

作者： Gen LIANG Chen SHI Ya-jun ZHOU Da-heng MAO College of Mechanical and Electrical Engineering Central South University state key laboratory of high performance complex manufacturing Central South University

To achieve ultrasonic casting of 35 CrMo steel,the waveguide unit for introducing ultrasound into liquid steel was studied numerically and *** structure and length of the ultrasonic waveguide were optimized by modal *** simulation results showed that a T-shaped waveguide unit matched the vibrational system better than an L-shaped *** performance of T-shaped waveguide unit was optimized when the length of the ultrasound radiator was 135 *** performance of the T-shaped waveguide unit was investigated in ultrasonic casting experiments,and the effect of ultrasound on the microstructure of 35 CrMo steel was *** experimental results showed that the T-shaped waveguide was able to successfully introduce ultrasound into the 35 CrMo *** addition,the use of a silicon nitride ceramic radiator avoided high-temperature corrosion in the molten *** microstructure of the treated area was significantly refined and equiaxed grains were *** results represented a novel method for ultrasonic casting of steel.

关键词： waveguide shaped ultrasonic equiaxed nitride refined length molten grains ceramic

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Automated visual position detection and adjustment for optical waveguide chips and optical fiber arrays

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Journal of central south university 2015年第10期22卷 3868-3875页

作者：郑煜开小超段吉安李白冰 state key laboratory of high performance complex manufacturing (central south university) College of Mechanical and Electrical Engineering Central South University

The alignment coupling between optical waveguide chips and optical fiber arrays is the basis of the alignment coupling of planar optical waveguide devices, and the precise position detection with angle and spacing adjustments is one of the key steps of alignment coupling. A methodology for position detection, and angle and spacing adjustment was proposed for optical waveguide chips and optical fiber arrays based on machine vision. The experimental results show angle detection precision levels higher than 0.05°, line detection precision levels higher than 0.1 μm, and detection time less than 2 s. Therefore, the system developed herein meets the precise requirements necessary for position detection, and angle and spacing adjustments for optical waveguide chips and optical fiber arrays.

关键词： planar optical waveguide alignment coupling automated alignment machine vision

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