Table of Content

10 July 2016, Volume 27 Issue 13

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Research on Flow Pressure Compound Position Control of Open Circuit Hydraulic Pump-controlled Forging Press System

Ai Chao, Liu Yanjiao, Song Yu, Kong Xiangdong,

2016, 27(13):  1705-1709,1715. 

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Aiming at the problems such as fast forging lag by the pipe lines of open circuit hydraulic pump-controlled forging press system, the mathematical models of main pump, master cylinder and pipe line were developed for the response lag under the forging processes, and the corresponding transfer functions were derived. On the basis of mathematical models, the feed-forward compensation control was proposed based on flow and pressure compound control. The system could achieve position control at no load and pressure compensation position control at on load, therefore the system controlled the pressure characteristics comprehensively. Based on 0.6MN hydraulic forging press experimental platform, the simulation and experiments show that the method brings a good effect on the problems such as slow rise of pressure and insufficient degree of forging of the open circuit hydraulic pump-controlled forging press system at on load.

Analyses of Mechanics Property of Pressure Balance Devices of Piston Type Underwater Force Sensor

Chen Enwei, Yang Li, Cao Yongyou, Lu Yimin, Liu Zhengshi, Wang Yong

2016, 27(13):  1710-1715. 

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Based on the condensability of liquid, the underwater force sensor with pressure balance of piston was investigated and the relationship among the working-depth of equipment, the volume change of the compensator fluid of piston and the pressure difference between inside and outside of equipment were deduced. The calculation method was also put forward. The static and dynamic analyses of the force sensor by MATLAB provided reference for design and calculation of piston used for pressure balance. The relationship between the creeping phenomenon of piston used for oil-filled deep-sea pressure sensor and the relevant parameters of O-shaped ring was analyzed. The results show that reducing the O-shaped ring cross-sectional diameter, the rate of pre-compression, the friction coefficient and the piston quality help to improve the creeping characteristics. The design principles of the structure of pressure balance device of piston were summarized.

Optimal Design Method for Bezier Ultrasonic Horn Based on Multi-objective Genetic Algorithm

Ji Huawei, Zhao Shuangshuang, Hu Xiaoping

2016, 27(13):  1716-1721. 

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In order to design high performance ultrasonic horn that was used to manufacture honeycomb composite material, a new approach was put forward to design ultrasonic horn based on multi-objective genetic algorithm. By using structural parameters of the ultrasonic horn as design variables, the resonant frequency and amplification factor as optimization goals, an optimization mathematical model of the Bezier ultrasonic horn was established. To get the parameters for calculating fitness function, a finite model and dynamics analysis of ultrasonic horn were carried out by calling ANSYS software from genetic algorithms, and the Pareto-optimal solution set was obtained by genetic algorithm, then, the most suitable parameters of ultrasonic horn were chosen for horn design. At last, the performance test of ultrasonic horn and trial cut experiment of honeycomb composite material show that amplification factor of optimized ultrasonic horn is as 7.66, it is 29 percent higher, and the working frequency is closer to design frequency than un-optimized ultrasonic horn. Simulation and experimental results confirm the reliability and validity of the proposed design method.

Multi-structural Parameter Modeling and Structure Design of a Rotating DF System

Pang Junzhong, Pan Jie, Chang Doudou

2016, 27(13):  1721-1725. 

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Aiming at the problems of the difficult chip removal and low efficiency in deep hole machining, a DF drilling system integrated with rotatable cutting tool was designed. Based on the fluid mechanics theory, a multi-structural parameter mathematical modeling on DF system of deep hole machine was established. The variations of chip sucking effects versus the main structure parameters were revealed and the optimal parameter combination was obtained. Then, the rotating DF system structures were improved and its parameters were optimized. The results serve as references of the optimization design on the chip conveyor of the deep-hole machine tool.

Kinematics Analysis of an 6-DOF Industrial Robot and Its 3D Visualization Simulation

Gao Yi, Ma Guoqing, Yu Zhenglin, Cao Guohua

2016, 27(13):  1726-1731. 

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For configurational characteristics of Motoman-HP20 robot, the D-H coordinate transformation method was adopted to establish the kinematics coordinate system, the robot was decomposed into position structure and pose structure, complete generalized coordinates of position vector and Euler angle were obtained. Pose separation method was used to analyse the robot inverse kinematics solution for critical angle. The 3D visual simulation environment was built, and the kinematics of the proposed algorithm was proved to be correct. The simulation platform of robot movement of each part could be observed visually.

Kinematics Analysis and Simulation for Four Wheel Drive All Wheel Differential Steering Mobile Welding Robots

Mao Zhiwei, Wu Xun, Zhou Shaoling, Li Xiangchun, Deng Fanling

2016, 27(13):  1731-1734. 

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In order to raise the stabilization,load capacity of mobile welding robots and to reduce the control complexity,a four wheel drive all wheel differential steering mobile welding robot mechanism was proposed.The differential steering principles of this mechanism were introduced and  proved this mechanism had no sideslip.The differential steering deviation model was built with nonholonomic constraint method.Based on this model,a numerical simulation analysis of straight-arc-straight trajectory was presented.As results,the rotation angle deviation is as 0.002 137° and the deviation of rotation center is under 0.012mm.The simulation results indicate that the model satisfies the position accuracy requirements.

Experimental Study of EDM Pulse Generator for Small Hole Machining

Zhang Haifeng, Wang Lifeng, Liu Jianyong

2016, 27(13):  1735-1739,1789. 

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For the problems of the low energy utilization of conventional pulse generator, the resistors overheating and huge cooling equipments, a kind of EDM pulse generator was presented herein,which cancelled the current limiting resistors. The pulse generator was made up of a PWM controller, a DC/DC converter, a machining pulse sequence generator and so on. It could automatically adjusting the output voltages, and the no load voltages, pulse width and pulse interval were adjustable in a wide range. The bulky frequency transformer was cancelled in the pulse generator. The experimental curves of the electrode wear rate, small holes ovality and one-side discharge gaps were obtained by the multiple small hole machining experiments. The experimental curves were closely related to the stability of the pulse generator. These data show that the pulse generator has good stability and reliability.

Experimental Study of Micro-wire Electrical Discharge Machining in Gas

Zhang Kai, Wang Biao, Yang Fuhe, Li Chuanhuai

2016, 27(13):  1740-1742. 

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Micro-wire electrical discharge machining using gas as processing medium,might be used to process hard-cutting materials and complex parts,featured with low stress and no burr.The effects of slot width and roughness of specimens influenced by open circuit voltage,electrode capacitance,air pressure and relative electrode feed-rate were researched.Experimental results show that air pressure,relative electrode feed-rate and electrode capacitance have obvious effects on slot width and roughness.The change of open circuit voltage has little to do with processing results.

Workspace Analysis of a Novel Feeding Manipulator

Zhang Zhonglei, Jin Zhenlin, Zhang Jinzhu

2016, 27(13):  1743-1747. 

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A novel feeding manipulator used in stamping production line was designed herein. This manipulator was successively formed by arm, forearm and end-picking device. Configuration of the arm was 6-PSS parallel mechanism. The forearm was also known as extended arm and the configuration was linear moving mechanism.The workspace of the manipulator was drawn. The influence rules between geometrical parameters of the manipulator and workspace volume were revealed. A set of reasonable geometrical parameters was selected based on feeding requirements among two presses, and the virtual prototype of this manipulator was presented. The features of the manipulator are of fast speed of lateral movement, large work space, etc, which can be used to convey workpieces on punching lines or other feed applications of modern industries.


Drilling Sequence Planning Based on Screw Motion of End Lever of a Tunneling Rig Manipulator

Wang Hengsheng, Chen Weifeng, Wang Siyuan

2016, 27(13):  1748-1754. 

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One of the problems in the development of computerized tunneling rig is to make a drilling sequence according to a drill pattern design, which is the focus of this work. ACO  algorithm was used to get a satisfactory sequence for a drill pattern,where  the objective function was based on the trajectory length of screw motion of the end effector transported from one hole position to the next by the manipulator. The formulas were derived for the calculation of the screw motion parameters of the end effector with dual quaternion expressions. Simulations verify the algorithm of screw motion of the interpolation of the trajectory and the trajectory calculated is smooth and continuous. It turns out to be a practical drilling sequence resulting from the ACO algorithm for a prescribed drill pattern with two   manipulators (right and left) of a 64-hole tunneling design.

A Novel Method to Quick Acquire Efficiency Characteristics for Three-phase Induction Motors

Gao Mengdi, Liu Zhifeng, Wang Yong

2016, 27(13):  1755-1759. 

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A variety of losses in the energy conversion process of the motors was taken into account, based on the power loss analysis and the loss model in d-q coordinate of the three-phase induction motors, a general model of load ratio and efficiency for motors was established. Only three groups of tests were needed to carry out in the same test conditions with varying load ratio, and based on the developed model, the efficiency characteristic curves would be obtained. Based on the experimental system for the efficiency test of motors, a comparison between the traditional point by point testing results and the proposed testing results was performed to determine the correctness and accuracy of the developed efficiency model. The results show that the developed efficiency models are in good agreement with the experiments and the maximum absolute deviations are within 1%.

Acoustic Emission Behavior of 12MnNiVR Steel under Stretching

Li Guanghai, Jiao Jinping, Wang Xinjian, He Cunfu, Wu Bin

2016, 27(13):  1760-1766. 

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Several methods of characteristic parameter analyses were introduced to analyze AE signals in stretching process of 12MnNiVR steel used in large atmospheric tank. These parameters included signal amplitudes, counts, hits and energy. Furthermore, the stretching process at different stages of a typical AE signal waveforms were also analyzed including time-domain waveform, spectrum, Hilbert time-frequency distribution etc. The results show that the characteristic parameters and waveform analysis of AE signals may reflect the different characteristics of the tensile deformation stages. AE technique can be used to characterize material stretching processes.

A New Surface Filtering Technology Based on Multi-resolution Singular Value Decomposition

Wu Fen, Huang Meifa, Chen Leilei, Wu Changlin

2016, 27(13):  1766-1772. 

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Recently, the way used to extract the surface evaluation reference existed some issues such as boundary effect，no multi-scale and the selection of wavelet basis function．Aimming at above problems，a theory called 1D multi-resolution singular value decomposition (MSVD) was introduced and a 2D MSVD was deduced．And a surface filtering method based on MSVD was provided according to the above theory．The filtering effectiveness has a good consistency with the existing surface filtering technology and this surface filtering is suitable to surface engineering evaluation．

Analyses for Lower and Upper Bounds of Sobol Total Sensitivity Index Based on Derivative

Song Shufang, Zhou Tong, Lü Zhenzhou

2016, 27(13):  1773-1779. 

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A main sensitivity index Si was set as the lower bound of Stoti and the new upper bound of Stoti was built based on the derivative. On the basis of functional analysis and Euler-Lagrange equation, the new upper bound of Stoti based derivative was analyzed for different variable distribution types, such as uniform, normal, exponential, triangular, Beta distribution etc. The derived process and formulas were presented in detail. Several numerical and engineering examples were used to verify the precision and efficiency of the presented bounds, which may provide the accurate bounds of Stoti.

Design of Fine Pitch BGA Solder Joint Pad Based on Solder Joint Shape Analyses

Chen Yilong, Jia Jianyuan, Fu Hongzhi, Zhu Zhaofei

2016, 27(13):  1779-1782. 

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The influences of solder joint shape on the solder joint height were studied to find the optimal matching relations of the volume, the pitch and the pad of BGA solder joint to increase solder yield. The Young-Laplace equation with the constraint of the volume was solved based on the Runge-Kutta method. The influences of the solder joint volume and diameter of pad on the solder joint height range were simulated. The results show that the whole solder joint height range shifts left or right with the changing solder joint volume. The influences of the pad diameter on the maximum height of the solder joint are of more obvious. The warping adapting to the package might be obtained by changing solder joint volume and pad diameter at the same time.Based on the standard of a 0.4mm pitch of BGA package of ZTE, the optimal matching relations of the solder joint volume and the diameter of the pad were analyzed with the 0.35mm pitch and 0.3mm pitch respectively.


Gearbox Fault Feature Reduction Based on Neighborhood Attribute Importance and PCA

Gu Yingkui, Pan Gaoping, Zhu Fanlong, Cheng Zixin

2016, 27(13):  1783-1789. 

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A gearbox fault feature reduction method was proposed to reduce the feature dimension and improve the accuracy of diagnosis based on neighborhood attribute importance and PCA. The SVM and BP neural network were used to analyze the diagnosis accuracy. The 36 features of different crack gears in gearbox were selected based on time-domain, frequency-domain and Hilbert transform. A forward-greedy numerical attribute reduction algorithm was established to select the optimal features based on neighborhood model. The 9 features with higher attribute importance were selected as the feature set. The principal components which had more than 95% cumulative contribution rate were extracted from the optimal feature set and input into the SVM and BP neural network classifier for identification. The results of the above method were compared with the PCA method without the optimal feature selections. Results show that the feature dimension may be reduced, the operating status of the gearbox may be indicated and the gear crack levels will be identified by using the proposed feature fusion method. Compared with the fusion method without the optimal feature selections, the diagnosis accuracy of the optimal feature selection is higher and the training time is shorter.


Study on Dynamic Performance of Time Grating Displacement Sensor

Yang Jisen, Zhang Jing, Jiang Zhongwei, Li Xiaoyu

2016, 27(13):  1790-1795. 

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In order to solve the dynamic measuring problem of time grating angular displacement sensor, through introducing motion unit module, a dynamic electromagnetic simulation model was established based on the static state electromagnetic simulation of time grating displacement sensor.The relationship among amplitude, frequency of the induced electromotive force and the speed of the rotor as well as magnetic field distribution was analyzed when time grating displacement sensor functions under its dynamic conditions. It is also predicted that the maximum speed is approximately 8r/min theoretically when the time grating displacement sensor is running with 400Hz excitation frequency. The experimental results show that the error of the time grating displacement sensor is as ±1.4″ under the speed of 0～8r/min and when the rotary speed of the time grating displacement sensor exceeds 8r/min, the error of the time grating displacement sensor begins to deteriorate. The error of the time grating displacement sensor is as ±8.2″ at the speed of 10r/min.

Fault Diagnosis of Gears Based on Adaptive Stochastic Resonance and Sparse Code Shrinkage Algorithm

Li Jimeng, Zhang Jinfeng, Zhang Yungang, Yue Ning

2016, 27(13):  1796-1801,1809. 

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Aiming at the impact feature extraction problem of gear faults under strong background noises, a gear fault diagnosis method was proposed based on adaptive stochastic resonance and sparse code shrinkage algorithm. In order to achieve the effective extraction of periodic impact features, correlated kurtosis was adopted as the measurement index of stochastic resonance, which was used to construct the fitness function of genetic algorithm. According to the maximum of fitness function, the optimal stochastic resonance system parameters could be selected, so as to achieve the adaptive extraction of the periodic impact features from the vibration signals submerged by strong noises. Then, sparse code shrinkage algorithm was applied to further reduce the noises from the detection results of stochastic resonance, thereby the impact features were highlighted to improve the identification accuracy of gear faults. The experimental and engineering application results indicate that the proposed method can realize the enhancement and extraction of impact features of gear faults, which will provide a basis for gear fault diagnosis.

Adjustment Method for Machining Errors of Machine Tool Based on Poor Information Fusion Technology

Xia Xintao, Zhu Wenhuan, Chen Shizhong

2016, 27(13):  1802-1809. 

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Based on fusing membership function method, maximum membership degree method, rolling mean method, arithmetic mean value method and bootstrap method, a poor information fusion technology was proposed to realize adjustment for machining errors of machine tool. The output small sample data in machine tool trial processing were fused using the poor information fusion technology to obtain estimated true value of the parts, and the machining errors of machine tool could be adjusted to make the machined parts meet quality requirements. Then the output small sample reliable data was obtained in machine tool adjusted well processing, and the estimated interval of the reliable data could be predicted using the fuzzy set theory under the given confidence levels. The results of simulation and experiments show that the poor information fusion technology can realize the error adjustment of machine tool, and the adjusted machine tool is reliable, and the feasibility of utilizing the information fusion technology to adjust machine tool was verified.


Research on Forming Quality of Overhanging Structure by Selective Laser Melting

Wu Genli, Liu Tingting, Zhang Changdong, Liao Wenhe

2016, 27(13):  1810-1815. 

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In order to reduce forming errors and improve the ability of forming complex structures by SLM, the impacts of inclinable angle, scanning strategy and supporting structure for forming quality of overhanging structure by SLM were studied herein, where the Ti6Al4V metal powder was used and an overhanging structural model with different angles was designed. Results show that the smaller the inclinable angle, the bigger the width errors of draping the edge lines (>80μm) and surface roughness (>20μm), and the more serious of warp and deformation; the overall forming quality of random scanning strategy within island-type is poorer than that of orthogonal scanning strategy within Z-type, but the influences on different overhanging structures are not the same. A reference was provided for SLM forming overhang feature structures, combining the QM-Meltpool monitoring system, and the impact analyses of inclinable angle and scanning strategy were completed based on the perspective of meltpool.

Research on Weldability of Weldox700E High Strength Steel

Zhang Sa, Wang Pan, Zhuang Yuan

2016, 27(13):  1815-1819. 

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The welding performance of the Sweden Vivitar Weldox700E high strength steel was analyzed. The microstructure and physical properties of the materials were systematically tested, and the microstructure of the heat affected zone and the problem of decline in toughness were analyzed. The results show that Weldox700E steel has good weldability, and there is a linear correlation between the organizational structure and the impact toughness, which provides a theoretical guidance for enterprises to determine the relation among organizational structure and physical properties in the welding process evaluation.

Design and Motion Planning of Vertical Seam Welding Device Based on Rotating Arc

Fan Yu, Zhang Hua, Ye Yanhui, Le Jian

2016, 27(13):  1820-1822,1828. 

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A vertical seam welding robot mechanism was designed based on rotating arc, an industrial computer and a motion control card were used to control. Horizontal and vertical slider were controlled by a stepping motor respectively, and drove with ball screws. A vertical motor with brake was used to prevent the decline of vertical slide block. It might increase the accuracy of the slider, and improve welding tracking quality. The rotation of welding torch was controlled by a step motor, to realise welding gesture adjustment in welding process, and the upper and lower corner might be welded,and the flexibility and the performance were improved. Welding processes are more stable, the appearance of welding seam is excellent.

Analysis and Experiment of Metal-polymer Composite Microscopic Structure Molding

Li Xiping, Gong Ningning, Wang Bin, Yang Can

2016, 27(13):  1823-1828. 

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Based on the forming technology for the metal-polymer composite parts, a method to manufacture these products was proposed. By improving the temperature, microscopic structure of the metal surface, and the viscosity, pressure and other characteristics of the polymer melt, the metal-polymer composite parts might be directly manufactured by injection method. Three different methods were presented to form different kinds of microscopic structures on metal surface and the characteristics of the structures were also obtained. A temperature control system used to control the temperature of the metal sheet was established in the laboratory. By using the control system and the manufactured injection mold, the metal-polymer composite parts were molded. Experimental results show that the interface bonding strength between the metal and polymer is much higher than the strength of the injected polymer itself. Results obtained herein may promote this new engineering applications of the polymer resin injection bonding with the metal alloy technology.

Optimal Fixture System Design of Auto Bodies Oriented to Assembly System Reliability Analysis

Liu Yinhua, Ji Feixiang, Ye Xialiang

2016, 27(13):  1829-1833. 

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In order to describe the gradual decline characteristics of multi-station body assembly system, a reliability model of assembly system for the dimensional quality and fixture system components were established. Combined with the fixture design stability parameter constraints, system reliability of body in white assembly system was proposed oriented multi-station welding process scheme of fixture layout optimization method. Under the given fixture layout, the production cost function of the locating pin was constructed, and the optimization model of the wearing rate of the multi-station fixture was put forward and the distribution was optimized. At last, a body side assembly case was used to illustrate the proposed method, and results show both of the reliability decline process and lifetime of the optimized fixture system are improved.

Effects of Injection Parameters on Performance at Low Loads of a Spark-ignited Direct Injection Heavy-oil Engine

Bei Taixue, Wei Minxiang, Liu Rui, Ji Haocheng, Chang Cheng

2016, 27(13):  1829-1833. 

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An experimental study on the influences of fuel injection parameters on the engine performance was carried out on a two-stroke engine with low pressure air assisted injection technology, and the effects of inject end time and excess air ratio on engine power, fuel economy and emission performance were studied under the conditions of middle speed under small load. Test results show that at the 10% throttle opening condition, with the end of the inject advance, the power first increases, then decreases, and the fuel consumption first decreases, then increases, and the HC and CO emissions are reduced. When mixed gas is diluted, the power increases, the fuel consumption is reduced, and the HC and CO emissions are reduced significantly. At the 20% throttle opening condition, with the end of the inject advances, the power increases, the fuel consumption decreases, HC emissions have a small decrease, and CO emissions have a small increase. When mixed gas is diluted, the fuel consumption is reduced, the HC and CO emissions are reduced greatly, and the maximum power appears in the stoichiomtric ratio.

Thermal Analysis on In-wheel Motor under Whole Electric Vehicle Driving Conditions

Jiang Congxi, Zhao Lanping, Du Xuzhi, Yang Zhigang

2016, 27(13):  1839-1845. 

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A CFD simulation performed on an in-wheel motor for electric vehicle was analyzed under various driving conditions and the temperature rising property of the out-rotor in-wheel motor was calculated. The cooling performance was studied related to the oncoming velocity and the conduction coefficient of the motor axle. Results show that under high-load driving conditions, the in-wheel motor is subjected to a large temperature rise only with incoming flow cooling method and can help lower the motor temperature by installing the cooling fins or using water-cooled devices. The high-temperature thermal radiation from the brake disc doesn't tend to deteriorate the motor temperature rise during the repetitive braking condition. The oncoming velocity shows a great influence on the motor temperature rise, while the conduction coefficient of motor axle exercises a relatively light effect on the motor temperature rise.