Table of Content

10 July 2011, Volume 22 Issue 13

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Approach to Mechanism Modeling of Fixture Location Error Analyses

TUN Yu-Guang, LI Chun-Guang

2011, 22(13):  1513-1518. 

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Workpiece-fixture system was represented by mechanism model, where fixture was the frame of the mechanism, the contact pairs between workpiece and locators constructed the kinematic pairs between side links and mechanism frame. The dimensional lines between location datum and location contact point become the side links, the dimensional lines between process datum and location datum become middle links or mechanism structure, and the process dimensional lines between workpiece surface and process datum were the objective links of the mechanism. By calculating the length and angle variation of objective links, the location errors of process system were obtained. The rules mapping from contact pairs to mechanism components were established. By analyzing the position relations between machining surface and process datum and the position relations between process datum and location datum, the rules controlling the conversion from dimension relations to equivalent mechanism components were explored. According to the mapping rules mentioned above, an equivalent mechanism model was established automatically, and the automatic solution of location error can be realized by means of the accuracy analysis methods of mechanism.

Research on Diamond Tool Wear in Ultra-precision Cutting of CaF2 Crystals

CHEN Gao-Feng, WANG Jian-Min, DAI Yi-Fan, ZHENG Zi-Wen, JIAO Fei-Fei

2011, 22(13):  1519-1522,1526. 

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In order to study the diamond tool wear and its effects on the cutting process in ultra-precision cutting of CaF2,the long distance cutting experiments of CaF2 crystals were carried out.The effects of cutting distance on the micrograph of tool damage were observed systematically,the tool damage mechanism was analyzed, the relation between tool damage and cutting model was discussed through analyzing

the influences of tool damage on the micrograph of machined surface and cutting force. The research findings show that: the tool damage model in ultra-precision cutting of

CaF2 crystals are grooving damage and notch breakage, the development of the tool damage followed with cutting distance is that the tool damage is extended from the grooving damage in flank face to notch breakage in rake face, and the cutting mode is also changed from the ductile mode cutting to brittle mode cutting. The research results supply the technological support for nano-scale ductile mode cutting of large-size CaF2 crystals. 

Development of a Robot Manipulator Grisp

SHU Yang-Yuan, NI Feng-Lei

2011, 22(13):  1523-1526. 

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In some special case, the robot should be requested to capture the floating aim in large range. So a special end manipulator was developed. The designed configuration could help the manipulator to limit the aim in 6-DOF. By study of the grip, the different motion tracks could be founded. In the capture experiments, it can be found that the fast close can eliminate the space which the aim can move. And the most grip space and results can be obtained by using the correct control.

Finite Element Analysis for Slider in High-speed NC Center Based on Assembly

CONG Meng-1, HAN Tao-1, DIAO Jiang-1, LI Xiao-Jing-2

2011, 22(13):  1527-1531. 

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In order to assure the accuracy and dynamic characteristics, slider of high-speed NC center must be analyzed by FEA to verify the reasonability of original design and made preparation for optimization. According to the structure of slider, a more reasonable boundary condition using combination was carried out and using the conception of assembly to simplify the model and then static and dynamic analyses were carried out based on the assembly. By comparison, the correctness of finite element model based on assembly is proved to be more efficient. 

Study on Hydrostatic Support of Inner Gear in Inner Mesh Gear Pumps

ZHANG Jian-Zhuo, LI Kang-Kang

2011, 22(13):  1532-1537. 

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The forming mechanism of inner mesh gear pumps' agglutination failure was studied herein.Then the force of inner gear during the process of operation was analyzed.The formula of the component force at the x,y direction which resulted from the hydraulic pressure and meshing force was deduced.The angle of swinging centerline and the average resultant force which was swinging between two angles in one cycle were obtained by MATLAB software.Based on the analysis results,the central position and the angle range of the hydrostatic support's channel were computed. The prototype experimental results show that there is no agglutination when the hydraulic pressure reaches 20MPa and the rotating speed of the main shaft reaches 1500r/min.

Study on Calculation of Transmission Efficiency about the Micro-segment Gear

CHEN Ai, DIAO Han, HUANG Kang

2011, 22(13):  1537-1539. 

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In order to research the transmission performance of micro-segment gear and get its transmission efficiency, a formula of claculating transmission efficiency of the micro-segment gear was deduced according to the method——friction work theory, which was used to calculate the involute gears' efficiency. Then the influence of parameters on the calculation resuslts of transmission efficiency was studied. At the same time, the constrast calculation results of the micro segment gears and the involute gears with the same parameters were gived. The results show that micro-segment gears' transmission efficiency is higher than that of the involute gears' and the calculation results of micro-segment gears' transmission efficiency are little influenced by gear parameters.

Type Synthesis of Forging Manipulators Based on Screw Theory

HU Yuan-Dou, TAO Jian-Chao, DIAO Yong-Sheng

2011, 22(13):  1540-1545. 

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In order to further improve decoupling performance of forging manipulators, two kinds of hybrid serial-parallel forging manipulators were configurated. Lifting motion of forging manipulator Ⅰ was realized by the parallel 4R mechanism, motions of pitching, yawing, left-and-right translation, back-and-forward translation and redundant lateral translation were realized by a 5-DOF parallel mechanism; lifting and pitching motions of forging manipulator Ⅱ were realized by a serial kinematic chain composed of revolute joint R and the parallel 4R mechanism, motions of yawing, left-and-right translation, back-and-forward translation and redundant lateral translation were realized by 4-DOF parallel mechanism. Then, 5-DOF parallel mechanism and 4-DOF parallel mechanism were synthesized by using the constraint-synthesis method based on screw theory. In concequence, several overconstrained and non-overconstrained 5-DOF parallel mechanisms are obtained, and several overconstrained 4-DOF parallel mechanisms and non-overconstrained 4-DOF parallel mechanisms are also obtained. 

Vertical Stiffness Model of Linear Motion Guide Considering Flexibility of Carriage

CHEN Ding, HUANG Ji-Bai

2011, 22(13):  1546-1550. 

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Based on the Hertzian contact theory and elastic beam theory, a theoretical model of the vertical stiffness of preloaded linear motion guide considering the flexibility of the carriage was established. By comparing the calculated vertical rigidity of the linear motion guide with the measured results proposed in a literature, the effectiveness of the proposed theoretical model was verified. The validation of the side face deformations were verified through FEA. With relative errors less than 3.5%, the calculated outward carriage deformations match the FEA results well. Clearly, the theoretical model can deal with the vertical stiffness of preloaded linear motion guide more accurately compared with the present models.

Study on Rolled Pieces Internal Part Quality Improvement during Three-roll Cross Wedge Rolling by Non-uniform Temperature Field

CHOU Beng, WANG Jian, XIAO Hong

2011, 22(13):  1550-1554. 

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Due to center-pressure method can improve internal quality of a round cross-section bar during stretching, through numerical simulation, the influences of stress and strain of internal part of rolled piece were discussed. It is proved that the method can reduce the internal part of rolled piece tensile stress, increase the hydrostatics stress, reinforce the deformation ability and make the quality of rolled pieces improved. And more, an experiment was carried out to verify the feasibility of non-uniform temperature field method to enhance the possibility of internal quality of rolled pieces.

Theoretical Investigation of Torsional Effect of a Rectangular Piezoelectric Quartz Disc and Verification

SHU Ming-Yi-1, TUN Xiao-Ling-2, GAO Chang-Yin-3

2011, 22(13):  1555-1558. 

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The torsional effect of a rectangular disc was investigated herein. By using the theory of anisotropic elasticity, piezoelectricity and the Maxwell electromagnetism, the torsional stress and the distribution of surface charge densities of a piezoelectric quartz disc were calculated. Then, by FEM the polarization electric field intensity and potential were simulated, and the simulation results show the distributions of the potential and the electric field intensity in the quartz disc are both antisymmetric with respect to the x axis. Finally, experimental results show that the torsional effect is existed and the bound charges are linear with the torque applied. Undoubtedly, the research will provide the basis for the torque measuring technique.

Acoustic Modes in Annular Duct with Uniform Mean Flow and Their Applications

LIU Tie-Xin-1, 2, HUANG Ji-Bai-1

2011, 22(13):  1558-1563. 

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The sound wave propagation in annular duct with mean flow can be used to validate calculation results of computational aeroacoustics and to approximately investigate the mechanism of acoustic wave propagation in complex geometries. The dispersion relation of acoustic modes in annular duct with mean flow was deduced from the governing equation, Euler equation,and the methods to find solutions to the dispersion relation equation were presented. The way to compute sound power in the duct with mean flow was also included.And then sound wave propagation at the inlet of a jet engine was

 simulated by prescribing a single acoustic mode. 

Determination of Functional Relationship Measures in Product Planning Based on Competitive Evaluations

LI Yan-Lai-1, LUO Xin-Gang-1, HAN Yi-2, TAO Jian-Meng-3

2011, 22(13):  1564-1570. 

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Determination of FRMs between CRs and engineering characteristics ECs is a crucial step in constructing house of quality (HOQ). Because the multiple attribute decision making characteristic of the FRMs, an integrated approach for determining the FRMs was proposed by exploiting competitive evaluations. Firstly, to acquire the competitive evaluations of CRs and ECs, the products of a company and its competitors were evaluated; secondly, according to these competitive evaluations, a model for determining the importance ratings of ECs corresponding to every CR was built by using multiple attribute decision making(MADM) method, and this model was resolved by using Lagrange function; lastly, by introducing a concept of type gene of a functional relationship, the FRMs between CRs and ECs were determined. A case study of product development of a singular-vat washing machine in a company was provided to illustrate the application of the presented approach. 

Configurable Structure and Implementation Technique for Embedded Flexible CNC Systems

CAO Jian-Fu

2011, 22(13):  1570-1575. 

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High-performance CNC systems were developed traditionally by the custom made pattern, the CNC soft-hardware was not shared with this pattern, its developing period was long and the developing cost was high. In order to solve the rapid configration problem of embedded CNC system, this paper proposed and implemented a type of embedded flexible CNC system based on components,and discussed the logic of hardware and presented the high-speed motion control protocol and implementation methods. The software system was implemented with a configuration structure on components, which consisted of three parts: embedded flexible development platform, function component library and model algorithm library, the paper presented the standard interface definitions.A series of CNC system developed by this flexible CNC platform was already been applied in industry, it shows that system developing period is reduced.

Research and Implementation of Disassembly Sequence Planning Algorithm in Virtual Assembly

MI Xiao-Zhen, JUAN Xiao-Yang, ZHOU Shao-Ze

2011, 22(13):  1576-1579. 

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In order to solve the combinatorial optimization problem of disassembly sequence planning, an ant colony algorithm-based approach was presented. A multi-objective mathematical model was established which was expressed by matrixes and contained geometric constraints, stability constraints and disassembly tool constraints. Interference matrix was used to analyze the feasible disassembly direction, support matrix was used to analyze the stability, and disassembly tool lists were used to analyze the tools used during operations. In order to find the optimal disassembly sequence more quickly, redirection factor, tool change factor and stability factor were added to the state-transition rule. Local and global pheromone were updated after operations so as to avoid a local optimal solution, to accumulate pheromone according to the quality of solutions and to guide ant colony in searching the approximate/optimal solutions quickly. Finally, the disassembly sequence of CRH3 bogie wheels was used as a case research to show the feasibility of the algorithm.

Flutter Analysis of Ceramic/Metal Non-conservative FGM Skew Plate

RUAN Miao-1, 2, WANG Zhong-Min-1, WANG Yan-1

2011, 22(13):  1580-1584. 

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This paper investigated the flutter of a ceramic/metal non-conservative FGM skew thin plate. Based on the thin plate theory, the material properties were assumed to vary continuously through their thickness according to a power-law distribution of the volume fractions of the plate constituents, and the differential equations of motion of the non-conservative FGM skew thin plate were established in oblique coordinate system. The dimensionless complex frequencies of the non-conservative FGM skew thin plate with four edges clamped were calculated by the differential quadrature method. The effects of the gradient index, skew angle and aspect ratio on the stability of the non-conservation FGM skew thin plate were analyzed. Results show that the critical flutter load decreases with the increase of the gradient index or the skew angle, the critical flutter load increases with the increase of the aspect ratio.

Research on a Feed-rate Planning Algorithm for Continuous Jerk

TUN Ji-Chun, ZHOU Hui-Cheng, TANG Xiao-Qi, CHEN Ji-Gong, LIN Wen-Feng

2011, 22(13):  1584-1587. 

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Aimming at mostly S-shaped feed-rate planning, constant jerk as a jump will cause the compact and vibration of machine tool, this paper presented a blended feed-rate planning algorithm based on continuous jerk. The machining trajectory was segmented firstly, then feed-rate planning with continuous jerk was implemented according to the length, feed-rate of the start and the end of each segment, the period was equal respectively.The expression was the same for jerk, acceleration and feed-rate for increasing acceleration and reducing acceleration phase. Increasing deceleration and reducing deceleration phase, in addition analytical expression is simple which is computed efficiently, and meet real-time requirements. The simulation results show this algorithm is feasible.

Study on Roughess Sensitivity of Genreal Profiles for Wind Turbine Airfoils

WANG Xu-Dong-1, CHEN Jin-2, WANG Li-Cun-1, CHENG Jiang-Chao-2

2011, 22(13):  1588-1590,1596. 

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Based on the boundary layer theory, a separation model of the wind turbine airfoils was presented. The transformation of pressure and velocity field on the airfoil surface were discussed. Compared with the traditional inverse design method, one direct and integral method for airfoil design was presented. Using the function equation of general wind turbine airfoil profile, an integrated mathematical model was presented. The roughess sensitivity of the general wind airfoil was calculated. The relation between the separation position, different Re number and aerodynamic performance were investigated for the general wind airfoils. The results provide enough theoretical support for the design of good performance and low roughess sensitivity. The design method and theory for wind turbine airfoils are developed.

Fuzzy Wavelet Neural Network Control for Coordinated Motion of a Free-floating Dual-arm Space Robot

HUANG De-Feng, CHEN Li

2011, 22(13):  1591-1596. 

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The dynamic control problem for coordinated motion of a free-floating dual-arm space robot system was discussed. According to the momentum conservation law, the dynamic equations of dual-arm space robot system were established through Lagrange equation of the second kind. Based on the above results, a fuzzy wavelet based neural network scheme was designed for dual-arm space robot system with unknown system parameters. The scheme achieves the coordinated motion of the base attitude and the joint angle in joint space. The control scheme needs neither to parameterize the dynamic equations of the system linearly, nor knows any system parameters. Further more, its network parameters are updating on-line by back propagation algorithm so that fuzzy neural network has strong ability of self-learning and self-adapting.Thus time-consuming off-line training process is not required. Simulation results of a planar dual-arm space robot system confirms that the proposed control scheme is effective and feasible.

Working Space and Motion Characteristics Analysis for a Novel Planar Parallel Manipulator with Three Driving Sliders

CHEN Hui-Beng-1, WANG Wei-1, DENG Jia-Ming-1, JIA Min-Zhou-2, MA Zheng-Hua-1, YANG Ting-Li-1

2011, 22(13):  1597-1601. 

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A novel practical planar parallel mechanism with three slides driving on the two guide rails was proposed and designed,and the positive and negative solutions were deduced. The working spaces analysis for the end-effector was conducted when it was in given position and orientations. The simulation of motion regulations and characteristics of actuator of the mechanism were also completed when it was in given orientation. A virtual prototype was also set up, which is useful for real-time control and industrial applications of this 3-DOF parallel manipulator.

Study on Influences of Grain Boundary and Grain on Machining Performance of Micro-EDM

LI Jian-Zhong, CHEN Fei-Hu, YAN Guo-Jiang, TU Jie-Yuan

2011, 22(13):  1601-1604. 

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In micro EDM, in order to select reasonable machining parameters to compensate the tool wear and to improve the quality of machined micro feature, a statistical analysis was used to study the influences of grain and grain boundary of the workpiece material on the material removal rate, tool wear ratio and the discharge gap by drilling micro holes in grain and grain boundary of the alloy. Due to the material characteristic difference between grain and grain boundary, such as composition, melting point, thermal conductivity and mechanical properties, the results vary. When the size of a machined feature is smaller than the grain size of the materials, the machining performance of grain and the grain boundary are different. Therefore, it is necessary to take micro structure of workpiece material into account when the tool wear is compensated. 

State-of-the-art of Research on Manufacturing Execution System Based on Bibliometrics

SHANG Hong-Chao, TUN Ying-Jing, LU Jian-Sha

2011, 22(13):  1605-1611. 

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The purpose of this paper is to explore the research status of MES by employing bibliometric analysis. The data for the study were obtained from core journals of China journal net database and engineering village(EI) from 1990 to 2009. Statistical analysis of citation number and word frequency was made on the data. The results reveal the most representative authors and journals by examining the citation number. Word frequency analysis presents that some relevant information technology contributing to the achievement of MES is developed increasingly at home. And the research abroad is entered a more mature stage, emphasizing on the analysis and decision making of problems by applying the results of MES.

Effects of Ultrasonic Action on Compression Performance of 6061 Aluminium Alloy

SHU Zheng-Jiang, ZHANG Xi-Fu

2011, 22(13):  1612-1614,1633. 

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Ultrasonic action in metal forming processing can reduce the forming load significantly; improve metal deformability and processing quality. The main factors effecting the reduction of forming load are the stress superposition, temperature increases and the change in the friction condition of contact interface. The effects of ultrasonic action on the compression performance of 6061 aluminum alloy were studied. By adjusting the main process parameters, such as coefficient of friction at the contact interface and ultrasonic amplitude etc. and based on ABAQUS implicit integration algorithm, the investigation on the influence law of stress-strain relationship under superimposing ultrasonic vibrations by different parameters was processed. The study indicates that ultrasonic action can reduce the interfacial friction and soften 6061 aluminum material during ultrasonic compression.

Study on Effects of Process Parameters on Laser Seal Welding for Ultra Thin Titanium Shell

NI Xian-Qing-1, ZHOU Zheng-An-1, WEN Xiong-Wei-2

2011, 22(13):  1615-1619. 

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Due to the effects of manufacture techniques on specimen and heat distortion during welding, seal welding for ultra thin titanium shell is quite difficult. An Nd: YAG pulse laser system was used to seal 0.3mm thick medical titanium implant herein. The effects of process parameters including pulse wave shape, laser power, welding speed, defocusing amount, and shielding gas were investigated. Besides, tests of micro-hardness and micro-structure analyses on overlapped weld joint were discussed. Finally, parts of the welded specimens were analyzed by helium mass spectrum leakage detector. The experimental results show that flat wave shape is optimum choice for seal welding, reasonable collocation of laser power and welding speed guarantees the welding quality, and the weld bead color is good when the shielding gas flow rate is at 15 L/minute. The welding specification for sealing ultra thin titanium shell was confirmed through a serial of technique experiments. It provides reference for engineering applications and optimization of the seal welding further.

Decision of Yielding Strength and Fatigue Crack Source of Hard Gears

HAN Cun-Cang, LIN Shi-Lan

2011, 22(13):  1620-1623. 

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This paper analyzed the decision factors of fatigue crack sources of hard gears, and produced a test for their practical production, according to the value of part yielding strength, and took active gear with curved teeth of tractor gear box for example. Through the analysis of shearing stress on the gear surface and the transformation between hardness and strength, the distribution of shearing stress and shearing hardness in the depth direction of gear surface can be obtained. The producing area of fatigue crack source is 0.4~0.45mm under the surface. Simultaneously, this paper analyzed the forms of fatigue crack and mechanism of transformation, and tested by observation and analyses of quantity of fatigue gears. The results demonstrate that this decision method which is based on the stress/hardness can decide the forms of fatigue failure and the source of fatigue crack intuitively and directly.

Research on Shape Control Model for DSR Skin Mill

LIU Zhi-Liang-1, LI Wen-Jiang-1, WANG Yang-Jie-2

2011, 22(13):  1624-1628. 

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A theoretical model for shape control characteristics of DSR skin mill was established and a deformation model of DSR skin rolls system was established through analytical method. The model was calculated based on influence function method, combining the particular principle of DSR roll and the distribution of the hollow roller and the special structure of briquette. On this basis, combining the specificity of skin rolling,a metal deformation model was established. With coupling of the two theoretical models, the whole shape analysis model was established. Then the model of computing processes and procedures were prepared for the research of shape control about DSR skin mill.

Knuckle Fatigue Prediction Based on Stress Field Intensity Approach under Random Excitation

HUANG Hai-Bei, CHEN Xing-Xin, WENG Qing-Feng

2011, 22(13):  1629-1633. 

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The fatigue life of a steering knuckle was predicted using finite element method, multi-body dynamics and stress field intensity approach. Six-component forces of all steering knuckle joints were obtained in time history by multi-body suspension system dynamic simulation. Then the most easily fatigue damage region was confirmed. The stress fields were then calculated at each step and the numbers of each stress field value were counted by rain flow method. The fatigue life was then calculated by stress field intensity approach. The results show that the connected region between wishbone and rib is the most easily damaged region and the fatigue life is 2.4×107 time.

Investigation on Active Suspension Mixed H₂/H_∞ Robust Control Based on NSGA_2 and LMI

HUANG Dong-Qing, JU Fu-Shun, FENG Bei

2011, 22(13):  1634-1637. 

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For practical application, this paper presented a fuzzy static output feedback controller design approach for vehicle electro-hydraulic active suspensions. Takagi-Sugeno(T-S) fuzzy modeling was applied for approximating the dynamic nonlinear active suspension model.Three main performance requirements should be considered in designing suspension, ride comfort, handing stability and suspension deflection, this paper took the vertical acceleration of the car body as H₂ performance, and suspension deflection and tyre deflection as the H_∞ performance.NSGA_2 was atilized for searching the feedback gain matrix, the H₂ and H_∞ norm were acquired via solving LMI. The comparison of the simulation results between active suspension and passive suspension in MATLAB/simulink shows that the three main performances of active suspension are better.