Table of Content

25 May 2013, Volume 24 Issue 10

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Research on Fault Diagnosis for Rotating Machinery Based on Semi-soft Wavelet Threshold and EMD

MENG Zong, LI Pan-Pan

2013, 24(10):  1279-1283. 

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A de-noising method was proposed based on combined  semi-soft wavelet threshold and EMD.Firstly,the semi-soft wavelet threshold method was applied to reduce the random noise.At the same time,it could
reduce the decomposition layers and end effect of the EMD.Then,EMD was performed properly on de-noising post-processing aiming at de-nosing and preserving useful  information.The simulation and experimental results show that this method can  extract fault features of the rotating machinery effectively so as to realize the fault diagnosis.

Molecular Dynamics Simulation in Vacancy Defect Monocrystal Silicon Nanometric Grinding

GUO Xiao-Guang, ZHANG Liang, JIN Zhu-Ji, GUO Dong-Meng

2013, 24(10):  1284-1288,1295. 

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Based on the first principles,a molecular dynamics model of  the grinding process of vacancy defect monocrystal silicon was built and verified.The instantaneous distribution of atoms,the temperature,the grinding force,and the potential energy in atomic scale were analyzed.Then the micro-scale mechanism of the grinding process was  explained,and the chip formation process and the machined surface formation mechanism were described.The impact of vacancy on processing process and surface quality  was analyzed and the effect of vacancy was also investigated during the simulation process.

Joint Torque Distribution of a Six-legged Wall-climbing Robot with Negative Pressure Adsorption Sucker

WEI Wu-1, LI Jin-Long-1, LIN Hui-Xin-2

2013, 24(10):  1289-1295. 

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This paper  focused on the joint torque distribution problem of  a six-legged wall-climbing robot with negative pressure adsorption sucker.A torque distribution method was proposed based on energy consumption optimization.The robot's dynamics models were derived on the basis of establishing the sucker overturning moment constraints,and the conversion between joint torque and the foot contact force,was completed,employing the Moor-Penrose inverse matrix method and the simple hill-climbing algorithm.These algorithms were implemented to calculate the relationship between the total energy consumption and the pose of the robot during various movement patterns.This was represented as the rotation angle of each joint,under the optimal goal of total energy consumption.The proposed method can adapt to various movement patterns effectively as well as improve the robot's environmental adaptability.Simulation results indicate that the proposed method is simple,effective,convenient in use,and  can identify the minimum energy consumption pose of the horizontally standing mode effectively,as well as,determine the most secure pose of the vertically standing mode after the setting of the horizontal security indicators.

Research on Reliability Modeling Technology for Machining Process of CNC Machine Tools Based on Task

WANG Guo-Jiang-1, ZHANG Gen-Bao-2, HONG Chao-1, CHEN Jia-Yan-1

2013, 24(10):  1296-1302. 

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Based on analysis of the limitation of existing research on reliability modelling of CNC machine,meta-task was introduced into this area,and the concept of meta-task was discussed,The model of task decompose of structures was founded,the GO methodology was used to establish meta-task reliability dynamic model,the relation between the meta-task and meta-task group was analysed,the Markov
theory was used to establish meta-task group reliability dynamic model.The task-based
reliability model was fully established.Taking a certain type of machining center made in China as an
example,which shows that the method is useable and correct and provides a practical solution for reliability modeling of CNC machine tools.

Study on Performance Reliability of Steel Ball Bearing Based on CrCN Composite Coatings

GU Gui-Xi-1, CHANG Jia-Dong-1, LI Yan-2, YUAN Qi-Long-2

2013, 24(10):  1302-1305. 

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Using the magnetron sputtering ion plating technique,CrCN composite coatings was prepared on the steel ball substrate of bearing 6204.The surface quality of CrCN composite coatings were detected by scanning electron microscopy and atomic force microscopy scanning.The performance reliability of coated steel ball bearing and uncoated steel ball bearing were tested and the comparative analyses were carried out.Results indicate that the CrCN composite coatings has very excellent surface quality(Ra=7.526nm).And compared to the uncoated steel ball bearing,the coated bearing reduces the vibration value,improves the reliability of the bearing performance life.The failure forms of coated bearing are the coatings wear failure.

An Approach to Tool Path Generation for Side Milling of Compound Surfaces in Aircraft Structural Part

FU Gao-Jie, LIAO Wen-He, LI Ying-Guang

2013, 24(10):  1306-1311. 

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This paper developed a new method to address the problem of automatic side milling tool path generation of compound surfaces in aircraft structural part.This method featured controllable precision,stable rotation of the axis and no interference.Specifically,the fitting accuracy become controllable by the iterative fitting algorithm,the tool axis rotated stably by the angle interpolation approach,and the interferences were reduced through local fine adjustments.The experimental and simulation results show that the surface fitting approach is accurate and efficient,and the tool path algorithm acquires high machining quality of
the parts in the simulation cuts.A system developed based on the approach herein is applied in an aviation manufacturing enterprise.

Experimental Study on Golf-ball Formation in Wire Bonding by Using High-speed Video Record

XIANG Kang, HAN Lei, WANG Fu-Liang, LI Jun-Hui

2013, 24(10):  1311-1314. 

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High-speed camera system was used to record image sequences of gold rail melting to form FAB(free air ball) under different EFO(electronic flame-off) parameters.The image was processed  through the MATLAB software to get the diameter of FABs and the distance between ball center and centerline of gold tail.The experimental results include:the distances are of instability and have large difference under the big EFO current (I=60mA) or smaller default ball diameter(D=1.6mil) or other conditions.
At the same time, it is easy to appear golf-ball in these conditions and influence wire bonding quality seriously.

Prediction Algorithm for Rotational Speed of  Workpiece's Revolving Shaft with Numerical Control Double Surface Grinder

WANG Hong-1, 2, DAI Yu-Xin-1, 3, HU Jun-1, 4, HU Shi-Xiong-4

2013, 24(10):  1315-1319. 

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The grinding precision of double surface grinder is low with conventional method of constant rotation speed, and a predictive method was
presented for the speed of the grinder's carrying workpiece disk herein.The mathematical model of the bi-planar grinding was established according to the grinding principle of constant removal rate and the geometrical relationship of grinding wheel and carrying workpiece disk,and the varying speed control method and its formula of the disk were proposed.The grinding wheel's tool orthogonal rake was adjusted by calculating the position marginal differential value on horizontal direction and vertical direction of the upper grinding wheel and the lower grinding wheel. The experimental results of packing ring's grinding with the Rexroth MTX's
numerical control system(YTDM 580CNC/CBN) based on this proposed method show
that he error of workpiece is as≤1.5μm,its depth of parallelism is as ≤3μm,and its roughness of surface is  as ≤0.2μm.

A Compound Fault Diagnosis Method for Gearbox Based on Order Tracking and Cyclostationary Demodulation

LI Rong, XU De-Ge, CHEN Xiang-Min, LIU Jian

2013, 24(10):  1320-1327. 

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Aiming at the problem of extracting fault characteristics from gearbox with compound faults under the conditions of changing rotating speed, a compound fault diagnosis method for gearbox based on order tracking and cyclostationary demodulation was proposed.In the proposed method,the rotating speed was estimated from original vibration signals by chirplet path pursuit algorithm.In order to transform the time domain non-stationary signals to the angular domain cyclostationary signals,the even angle resampling
was carried out to the original signals according to the obtained rotating speed.The angular domain cyclostationary signals were  analyzed  by cyclostationary demodulation method,and the compound fault diagnosis of gearbox was executed according to the slice demodulation spectrum of fault characteristic order.The results obtained by  analysis of the algorithm simulation and application examples to the gearbox with compound faults consisted of gear local fault and bearing local fault under the condition of changing rotating speed,show that the proposed method can extract fault characteristic effectively from gearbox with compound faults.

Pressure  Angle Values Based on Shaving Modification Terms

CA An-Jiang, ZHANG Zhen-Jun, RUAN Xiao-Guang

2013, 24(10):  1327-1330. 

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According to the numerical calculation of the meshing angle the derivation of the meshing angle of transcendental equation was studied and the application of  Stephenson-Newton iterative method and Newton iterative method was put forward for the numerical calculation of the meshing angle,then more accurate meshing angle values were obtained，the elimination of shaving  “the flank concave” effect of  the process was carried out.Two methods of numerical calculation of meshing angle were analyzed through the error tolerance,iteration times and  the optimal solution value,Stephenson-Newtonian iterative method was compared with Newton iterative method,and can avoid differentiable numerical calculation inadequacy,with the advantages such as fast convergence,fewer iteration times,solving stability,optimal numerical solution etc..

Position and Orientation Workspace Atlas of a 6-UPS Parallel Machine Tool

CHEN Xiao-Gang-1, 2, SUN Yu-1, LIU Yuan-Wei-2, TUN Hai-Bing-2

2013, 24(10):  1331-1335,1339. 

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To estimate the manufacturing ability of a 6-UPS cross links parallel machine tool BJ-04-02(A),workspace calculation was completed using numerical method,and corresponding atlas were pictured.Considering constrains of link length,revolving angle and interference,translational position space of
cutter-platform was calculated under conditions that  axes of motional coordinate system and inertial frame always were parallel respectively.Contour graphs of some discrete layers were
extracted and maximal inscribed sphere,cylinder and block were calculated for above position space.
The concept of orientation ability angle was redefined.For each point in above position
space,orientation ability angle was calculated.The workspaces corresponding to different orientation ability angles were provided.The calculation results show that:when orientation ability angle is 20°, the volume ratio of workspace to machine tool for BJ-04-02(A) is approximately one twenty-fifth of Mikron five axis machine tool UCP800.

Study on Dynamic Characteristics of Cu/CuNi Thin-film Thermocouple Based on Theory and Experiment

YANG Li-Gong, DIAO Yuan-Shen, CHEN Hao-Fan, SUN Jin-Xiang

2013, 24(10):  1336-1339. 

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For the characteristic of rapid response, thin-film thermocouples were always utilized to measure transient temperatures. The theoretical analysis of dynamic characteristics plays a significant role in the research of thin-film thermocouples. As the target medium was fluid, one-dimensional and unsteady heat transfer model for Cu/CuNi thin-film thermocouple was introduced herein with the boundary conditions of heat convection which was fabricated by means of magnetron sputtering with thickness of 1μm. After dynamic calibration was carried out by means of quickly throwing method, the response time of the thin-film thermocouple was obtained as 7.89ms, which was close to the theoretical calculation value of 4.28ms. From the results of experimental and theoretical analysis, it can be seen that the heat transfer model is reliable, which lays the foundation for theoretical analysis on improving dynamic characteristics of thin-film thermocouple.

Bending Vibration Analysis of Combined Ring-beam  Vibration of  a Piezoelectric Motor

GENG Ji-Chun, HU Li-Zhong

2013, 24(10):  1340-1344. 

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Two solution methods of a beam for a combined ring-beam free vibration were  proposed.Using two methods,the natural frequency equation and modal functions for  a combined ring-beam were deduced respectively.Comparing beam vibration mode solutions by the two algorithms,the similar modes were found and extracted from two algorithms.Through a practical example,the natural frequency relative errors of similar modes by two kinds of algorithm were obtained.Changing the combined ring-beam structural parameters,the effect of parameters on similar mode natural frequency relative error by two kinds of algorithm was analysed and the causes of errors were discoved and two algorithm applicable scopes were identified.

Preliminary Development and Application of Cloud-computing Based Cloud-manufacturing

FANG Shui-Liang, FU Wei

2013, 24(10):  1345-1349. 

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With the requirements of wide-area sharing of various kinds of manufacturing related software,a prototype of cloud manufacturing platform was developed for the purpose of software resource management and sharing,which was mainly based on the technologies of cloud computing-virtualization and SaaS,etc.A cluster of virtual machines,which can be dynamically managed,was established on VI3 infrastructure. Similar to the structure of  Google file system(GFS),large amounts of software resources were organized and well-managed.Upon the .Net structure,and with PowerShell technology,a remote invocation of the application software was realized for the web-based remote user.Finally,for the design of motor product,the process of remote use of an electromagnetic-software  was demonstrated based on the cloud manufacturing platform.

Study on Hierarchical Service Composition in Cloud Manufacturing

LIU Wei-Ning, MA Gang, LIU Bei

2013, 24(10):  1349-1356. 

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To cope with the quality of service(QoS) bottleneck and evaluation deviation of composite services path in cloud manufacturing(CMfg) system due to ignoring the hierarchical characteristics of the manufacturing processes,a mathematical model and a solution algorithm were proposed and studied.Initially,
the hierarchical manufacturing cloud services composition(H-MCSC) model was formulated based on the hierarchical manufacturing implementation processes.Then,a simulated annealing algorithm was developed based on the analysis and properties of the H-MCSC model.Within the algorithm,a  pruning strategy based on sub-paths QoS constraints was designed to improve the efficiency of the algorithm.Simulation experimental results prove  the validity of the model and algorithm.

Research on Aligning Measured Data of Blank Parts to Nominal CAD Models under Machining Allowance Constraint

WANG Xin, ZHANG Li-Yan, LI Huan, TAN Gao-Shan

2013, 24(10):  1357-1361,1380. 

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In order to reject the unqualified blank parts before machining and avoid lack of allowance resulting from poor localization during machining, the measured data of blank parts must be aligned to the nominal CAD models under the machining allowance constraint.A 2-step algorithm was proposed to solve this alignment problem.Firstly,registration without considering any constraints was performed by the ICP(iterative closest point) algorithm.If the registration results meet the machining allowance requirements,the algorithm terminated;otherwise,the further registration considering allowance constraint was performed.Experimental results show that the proposed method is very appropriate for aligning the measured data of blanks to the nominal CAD models with the machining allowance guaranteed.

Research on NURBS Curve Interpolation Algorithm Based on Moving-average of Position Invariance

SONG Fang-1, HAO Shuang-Hui-2, HAO Meng-Hui-2

2013, 24(10):  1362-1368. 

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Due to solve the shortcomings of the speed and position altering of the interpolation points near the extreme point and the junction point by filtering technology,the inference of moving-average of the position invariance was derived based on moving-average technology.By means of  this inference,the shortcomings can be solved.And the method was scalable.It can achieve the acceleration of continuous,and jerk very easily and displacement for time of more-order differentiability of continuous.Thus the proposed algorithm can reduce the machining vibration.Finally,the implementation and experimental results were given in detail.The experimental results show the effectiveness and feasibility.

Metal Surface Damage Diagnosis Based on Electrostatic Sensing

XU Yi-Ming, ZUO Hong-Fu, DAN Zhi-Juan, XU Jun-Jun

2013, 24(10):  1369-1374,1419. 

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Diagnosis technology and method based on electrostatic sensing for metal surface damage were proposed. Mechanism of electrostatic in metal contact damage and electrostatic sensing model were produced. Feasibility of this technology was analyzed based on wavelet transform, reconstruction and STFT(short-time Fourier transform) analysis. Damage was located by using sensor array and an algorithm. Quantitative recognition of contact damages were achieved by using support vector machine neural networks and factor analysis. So diagnosis technology and method based on electrostatic are capable of locating and quantitating the contact damage.

Study on Cam Profile's Expression Method and Its Applications Based on NURBS Curves

2013, 24(10):  1375-1380. 

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In order to make different cam profiles have a unified expression form,and to ensure the fairness of  the cam profile,a method to approximate cam contour curve by using NURBS curves was put forward,and with the least square method a target function of NURBS curves was constructured,then the expression model of cam profile based on NURBS curves was established.After using the model to express the cam
profile of the conjugate cam used in the walking-type rice transplanter's seedling-pushing mechanism,more uniform variation of the cam contour curve can be obtained after fitting.Compared with traditional fitting methods,it can be found that fitting method based on NURBS curves has smaller error and needs less points.All these aspects indicate that the cam profile's expression method based on NURBS curves has
obvious advantages.

Study on Deflection of a Variable Cross Sectional Flexible Component under Arbitrary Loads

LIU Qiang-Ling

2013, 24(10):  1381-1384. 

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The deflection of a variable cross sectional flexible component under arbitrary loads was analysed.The variable cross section and the nonlinear were considered,a second order nonlinear differential
equation about deflection of the variable cross sectional  compliant component under arbitrary loads was established.The discrete numerical calculation method and Taylor's expansions were used to solve the nonlinear differential equation.The variable cross sectional flexible components under different loads were analysed with the analysis method obtained from this paper and the finite element method simultaneously,the two results were obtained and contrasted,so the correctness of the analysis method and the differential equation were proved.

Method and Implementation of Substructure FRF Synthesis Considering Connection Property

WANG Wei, HU Xu-Jin, LING Ling

2013, 24(10):  1385-1389. 

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On the basis of FRF substructuring method,parameterized connection property between substructures was taken into account,which made connection parts independent of the connected substructure system.The general treatment of rigid connection property and flexible connection property was realized.At the same time,the hybrid modeling of test substructure and theoretical substructure was realized and the corresponding hybrid modeling solution system was developed.The numerical calculations show that this method can deal with flexible connections among substructures and is still effective when stimulation test data of substructure is polluted by random errors.

Offset Modeling  and Analysis of  Strain Neutral  Surfaces for Straightening a Thin-walled Tube

ZHANG Zi-Jian-1, YANG Hui-Lin-1, TIAN Yong-Li-2

2013, 24(10):  1390-1395. 

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In order to reveal the deformation mechanism of a thin-walled tube straightening,a new stress-strain model in the straightening deformation zone was found based on the elastic-plastic theory of a thin-walled member.Then,a offset model of the strain neutral surfaces was established subsequently,which was  proved to be approximatively accurate by FEA analysis.Analyzing the change trend of the model,it is found that the offset value decreases with the increase of relative reverse bending radius,and it also increased with the increase of plastic deformation capacity of the metal,it is also found that how to use this
model in different situations.This research can provide the theoretical basis for studying  the deformation process and the straightening mechanism of a thin-walled tube straightening deeply.

Experimental  Research on Deep Drawing of Cup Shell by Granules Flexible Cavity Forming

JIA Dun-Ting-1, 2, DIAO Zhi-Yong-1, HUANG Qian-Ying-1, WANG Chang-Wei-3, ZHANG Chun-Xiang-2

2013, 24(10):  1395-1398. 

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A test die was designed and the deep drawing technology was researched for granules soft cavity forming based on analyzing the technological characteristics.The cup shells were formed with good qualities.The wall thickness for any part of formed cup shell are thinning and thinning amount increases with the height increasing of  the cup shell.Compared with common rigid die forming the forming limit of cup shell can be improved.The observation and analysis of the surface microstructure for cup shell indicate that crack defect can be prevented effectively in round area when the parts are formed by granules flexible cavity forming technology.

Research on Recovery Control of Wrecker Based on VAPID

LV Cheng-Xu-1, 2, ZHANG Wei-Gong-1, LI Xu-1

2013, 24(10):  1399-1403. 

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To realize the recovery automatically,research on the recovery control process of wrecker was approached.First,the recovery strategy was proposed,and the recovery model was built.Then,a hydraulic circuit
model of wrecker's recovery system was built in AMESim.Furthermore,the  VAPID and the conventional PID controller were used to the recovery control respectively.Performances were analyzed in MATLAB/Simulink software.Simulation results show that the VAPID controller can accomplish the recovery automatically and stably with faster step response speed and less overshoot than that of the conventional PID controller.

Research on Matching Design of Multi-axle Hydraulic Assisted Steering System

WANG Yun-Chao-1, ZHANG Xiao-Jiang-2, ZHOU Mei-1, ZHENG Dong-Jiang-1

2013, 24(10):  1404-1407. 

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Steering linkage deformation or crack was prevalent in multi-axle hydraulic assisted steering system.Based on a semi-empirical formula of tire static steering resistance moment,a mechanism-hydraulic co-simulation model of a multi-axle steering vehicle was built by ADAMS and AMESim software and the correctness was verified by experimental tests.Taking the minimum force of steering linkage as optimization objective,the matching relationship between hydraulic steering system and tire steering resistance moment was optimized.The research shows that the matching relationship has obvious effect on the steering linkage force.The steering linkage force is reduced significantly by matching optimization.

Progresses on Wear-resistant Coating and Tribological Performance of Piston Ring

LI Hui, SUN Ri-Chao, WEI Qi, LI Zhuo-Xin

2013, 24(10):  1408-1412. 

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Piston ring suffers from severe wear conditions and therefore coating technology was widely applied on the surface of piston ring in industry.This paper summarized the recent development on technologies and relevant materials of the wear-resistant coatings on piston ring.The wear mechanism was also analyzed and the progresses on the tribological tester were finally discussed.

Study on  Key Techniques of  Wear Monitoring and Fault Diagnosis for Marine Diesel Engines:a  Review

YAN Xin-Beng-1, LI Zhi-Xiong-1, ZHANG Ru-Lei-2, YUAN Cheng-Qing-1, BANG Zhong-Xiao-3

2013, 24(10):  1413-1419. 

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To ensure  the reliable operation of marine diesel engines,a marine diesel engine fault diagnosis system was developed based on the information fusion of multi-dimensional sensors.In the light of the application of the proposed diagnosis system,the key issues on the wear condition monitoring and fault diagnosis for marine diesel engines were discussed from view  point of  the coupling of tribologic and dynamic information.Lastly,existing problems and future research directions were reported.