Table of Content

10 October 2011, Volume 22 Issue 19

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Study on Tribological Performances of Laser Textured Surfaces

FU Yong-Hong, SHI Tu-Feng, HUA Xi-Dun, SUN Dong-Cheng, ZHANG Zong-Chao

2011, 22(19):  2269-2274. 

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Using optimized laser processing parameters and the corresponding auxiliary craft measures, die steel samples were textured by a Q switched ling - pumped Nd：YAG laser in the form of slight protuberance similitude of spherical cap with different sizes and distribution of micro-convex. The tribological properties of laser surface textured die steel samples as well as untextured die steel specimen were comparatively investigated on a UMT-Ⅱ trib-meter. Results show that the friction coefficient of laser surface textured samples is obvious larger than that of untextured specimen. It is found that the friction of textured sample with 1300μm span is about 2.25 times over that of an untextured sample. The tribological friction increases with the decrease of span among the micro-convexes. The maximum friction is 0.1192 when the span is 1300μm. The tribological friction is inversely proportional to the diameter of micro-convex but directly proportional to the diameter of micro-convex. The friction decreases with the increase of speed, that is because the hydrodynamic effect increase with the speed increase.

Study on Cutting Chatter Based on Fast Tool-off Milling

SHANG Ai-Min-1, 2, ZHOU Zhi-Xiong-1, XIAO Sai-Lai-1, 2, HUANG Wei-Wu-2, LI Zhong-Hua-2, WANG Hu-Chao-2

2011, 22(19):  2274-2278. 

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In order to improve the limitation of traditional measurements, and better research of milling vibration, an experiment called fast tool-off milling was designed and carried out. In the experiment, the milling chatter frequency calculated by analysing the machined surface was compared to that calculated from the dynamic torque. The results show that fast tool-off milling experiment can absolutely be applied to investigate the chatter in high speed milling. In addition, the effects of cutting parameters on vibration were studied applying the fast tool-off milling.

Gravity Deflection Effects on Online Measuring System of Large-sized Crankshaft Straightening Press

DI Hua-1, ZHANG Hong-Mei-2, ZHONG Hua-Yong-1, DIAO Han-1

2011, 22(19):  2278-2282. 

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Based on the existing state of manual measuring the main shaft neck straightness of crankshaft with the features of long time spending and precision easily influenced by manual work, an online measuring system of large-sized crankshaft straightening press was designed according to the method of least squares to measure the main shaft neck straightness of crankshaft. Considering the influences of gravity on measuring value, a gravity deflection elimination algorithm was proposed through finite element method and the second degree interpolation algorithms. And the experimental results expresses that the maximal errors are less than 0.007mm between the calculation values from elimination algorithm and the values from manual measurement. The online measuring system was applied in YH40-160 straightening press and the time spending is decreased to 4 seconds which is 30 minutes in manual measurement.

Cutting Force Prediction Based on Oblique Cutting Theory in End Milling

LI Bing-Lin, HU Xu-Jin, WANG Hua-Lin, LI Cheng-Gang

2011, 22(19):  2283-2288. 

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A new approach was proposed to predict the cutting forces in end milling. The helical flutes were decomposed a set of differential oblique cutting edges. At every oblique cutting element, the governing equations of stress, strain, strain rate and temperature of chip through the primary shear zone were established using oblique cutting theory. The flow stress was calculated iteratively from the governing equations. Cutting forces were predicted using oblique cutting transformation into end milling. The simulation and experimental results for machining 45 steel were compared, a good agreement is observed for the different cutting conditions. The proposed method can easily be extended to other machining operations such as turning and drilling.

Multi-objective Optimization of Slider in High-speed Horizontal Center Based on 6σ and Goal Driven

CONG Meng-1, HAN Tao-1, DIAO Jiang-1, JIANG Mei-Na-2

2011, 22(19):  2289-2292,2297. 

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In allusion to structural characteristics of slider, a finite element model of slider was built firstly, and then a method which combined 6σ and goal driven was put forward to optimize slider. Parameter sensitivity analysis was carried out based on 6σ, and variables which affected the target variable greatly were chosen to be as the design variables. Total mass, deformation and natural frequency of slider were established as objective functions and then multi-objective optimization was carried out, optimization results can be chosen by the priority set before. Compared to the single objective optimization, better solutions for practical engineering problems can be obtained by multi-objective optimization based on 6σ and goal driven.

Study on Non-conformal Contact Characteristics of Ball Screw

WANG Fu-Ji, YANG Jiang-Yuan, GU Zhen-Yuan, WANG Wei, LEI Xiao-Gong

2011, 22(19):  2293-2297. 

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The contact between balls and screw races or nut races is a kind of typical non-conformal contact and its characteristics will influence greatly on ball screw’s load capacity, transmission efficiency and positioning accuracy. Thus Hertz contact theory was adopted to construct the solution formula of ball screw’s contact stiffness, then ball screw’s contact characteristics in terms of axial load, design parameters and material properties were analyzed, and the contact deformation values of the contact between balls and screw races were obtained through finite element simulation method. The simulation results are close to the theoretic ones, which proves the correctness of the theoretic analyses. The present study offers theoretical support for the design and application of high speed, heavy load and precision ball screws.

Development on Coaxial Feeding Nozzle with Unloading Carrier Gas for Laser Manufacturing

TIAN Feng-Jie

2011, 22(19):  2298-2302. 

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In order to obtain high utilization of powder and improve working performance of coaxial nozzle, a new coaxial feeding nozzle with unloading carrier gas was researched. Gas-solid two-phase flow theory was used to analyze and calculate the powder flow injecting from coaxial nozzle in coaxial powder feeding system with unloading carrier gas. The convergent distribution of powder flow and powder convergent performance (focus distance to nozzle exit and focus radius of powder flow) was studied and the powder feeding tests were made. The results indicate that the convergent performance of nozzle is concerned with the convergent angles, exit radius, exit width of nozzle and the convergent angles are of much effects on it, the convergent performance and powder utilization are improved clearly through adopting a structure with one through shrinkage annulus cavity to directly inject particles separated from carrier gas. The powder flow simple model was also presented and the conclusion will be benefit for coaxial nozzle design and performance improvement. 

Feature Extraction Based on Split-merge in Range Image of LIDAR

MAN Ceng-Guang, XIE Wen-Hua, LOU Pei-Huang, XIAO Hai-Ning

2011, 22(19):  2303-2306. 

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For the environmental perception of mobile robots with light detection and ranging(LIDAR), a method based on split-merge framework was presented herein. In splitting stage, a data set was segmented recursively with the IEPF(iterative end point fit) algorithm. In merging stage, both the EPF(end point fit) method and the total least square method were used to fit a new data set composed of the two adjacent segments. If their fitted errors were less than their thresholds respectively, the two data sets were merged into one. Merging stage was a recursive process for that it didn’t terminate until every two adjacent data sets didn’t satisfy the merging condition mentioned above. Results of comparative experiment show that the method presented reduces the probability of over-segmentation and under-segmentation resulted of the fixed threshold of the IEPF algorithm greatly and achieves good results of linear feature extraction.

Structure and Kinematics Analysis of a Novel 3-RPR Parallel Mechanism

LIU Yan-Bin, HAN Xiu-Yang, GUO Zhi-Jia, GU Xin-Jie

2011, 22(19):  2307-2311. 

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A novel 3-RPR parallel mechanism was proposed, that can realize two-dimensional translations along Y,Z-axis and rotation about X-axis. Based on screw theory, the principles in accordance with which the parallel mechanism realized the above 3-DOF motions were analyzed, the mobility of the parallel mechanism was calculated, and the drive input joints were chosen and discussed, the motion singularity was analyzed and the parameter design conditions were presented to decrease motion singularity. By means of multi-body system kinematics theory, the kinematics equations of the parallel mechanism were set up, the forward and inverse position kinematics solutions were discussed and validated using numerical simulation. Finally, the workspace of the parallel mechanism was analyzed. The 3-RPR parallel mechanism replenishes 2T1R parallel mechanism family, whose three branches are uniform, and structure is semi-symmetric and simpler, and the parallel mechanism can be applied in the fields of industrial assembly robots, posture adjusters, parallel machine tools, work platforms.

Analysis of Morphology of Kerfs of Submerged Abrasive Water Jet

HOU E-Kang, MAO Gui-Ting, YANG Ning

2011, 22(19):  2312-2316. 

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This paper mainly focued on analysing the kerf of submerged abrasive water jet cutting from which a width of the constant region was obversed. The author adopted the Hurst index and R/S analytical method to analyse and get the temporal correlation and random in the formation of the kerf, which randomness increases and correlation deteriorates as the feed rate decreases. 

Wireless Communication Protocol for Remote Intelligent Monitoring of Construction Machinery

JIN Min-1, LUO En-Ze-1, ZHOU Xiang-2

2011, 22(19):  2316-2324. 

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CMTDP, a wireless transparent transfer protocol based on UDP, was proposed for the remote intelligent monitoring system of construction machinery. The architecture of CMTDP was presented. The four key technologies of CMTDP were described, in which the transfer modes were matched online and optimized dynamically with the transmission data types and the transmission channel states. The test results of a practical application on concrete pump verify that CMTDP can satisfy the requirements of construction machinery on data transmission performance, transmission data types, monitoring scale and cost. The test results also show that the implementation of CMTDP does not need the support from the routing node in wireless network.

Synchronous Measurement and Control Mechanism Based on High-speed Fiber Channel Link

CHENG Xin-1, 2, ZHOU Yun-Fei-1, HU Yong-Bing-1, WANG Yao-1

2011, 22(19):  2325-2330. 

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Towards the requirements of nanometer-scaled synchronous motion of stages in lithography device, this paper proposed a synchronous measurement and control mechanism based on fiber channel link to realize strict synchronization of control instructions execution and sensor sampling towards different axes. Dedicated high-speed data transmission channel between each motion controller and relevant measurement and control unit was designed to ensure the real-time control performance. Design of synchronous cycle trig based on internal bus, consensus definition of sensor sampling and actuator timing and precise data transmission model ensured the synchronization performance. Experimental results show that overall outputs delay is less than 0.65μs with synchronization error less than 20ns. Performance of measurement and control mechanism can be improved by improving the fiber channel transmission rate. 

Research on Product Family Configuration Based on Multidimensional Association Rules

LUO Yu-1, 2, GUO Gang-1, XU Jian-Ping-3

2011, 22(19):  2330-2336. 

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A product configuration method based on association rule was introduced aiming at the choice of optional parts in product configuration of large complex products. A component-constraint-rule data warehouse (CCRDW) could be built with the information of product family BOM(bill of material) structure. According to the parameters of customer requirements, a data cube from the data warehouse could be established and by using multidimensional association rule data mining algorithm on the data cube, the appropriate components in materials store would be found. The configuration method of a gear box and its instance was presented. The method has advantages in enhancing the efficiency and reusability of the components.

Study on Control Method of Brushless DC Motors Based on Self-adaptive DRNN

WANG Li-Biao, LI Jun, FAN Jian, LI Tou-Feng

2011, 22(19):  2337-2340,2392. 

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In view of brushless DC motor speed control for highly nonlinear characteristics, a self-adaptive DRNN control system was proposed. The controller consisted of a PI feedback controller and a self-adaptive DRNN feed-forward controller. The PI feedback controller used target speed and actual speed error for input to improve the stability of control system. The feed-forward controller was trained by using feedback controller outputs as learning error to improve transient performance of control system. The simulation and experimental results illustrate that the control system can track the target speed, reduce the torque ripple and improve the current waveform under load disturbances, which has strong robustness. 

Uncertainty Analysis of Flexible Multibody Systems Using Polynomial Chaos Methods

PI Ting, ZHANG Yun-Qing, TUN Jing-Lai

2011, 22(19):  2341-2343,2348. 

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A parametrical uncertainty analysis of flexible multibody systems was presented. The deformations of flexible parts were modeled using ANCF. Polynomial chaos methods were employed to solve ANCF-based flexible multibody systems with random variables. Theoretical analysis and numerical examples were made to compare the accuracy and efficiency of polynomial chaos methods and Monte Carlo simulation method. Results show that polynomial chaos methods are more effective than Monte Carlo simulation to achieve the same accuracy in solving complex flexible multibody systems. 

Theoretical Analysis and Simulation in Rolling Seed Clearing Process of Hole-type Cotton Accurate Device

LI Dun-Wei-1, HU Bin-2, LUO Cuan-2, DIAO Yan-Wei-1

2011, 22(19):  2344-2348. 

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To solve the problems of existing metering device’s complicated structure and fatigue damage of seed-taking equipment, on the basis of the original type hole metering device, a new type of structure of more simple device was design innovatively.Based on the motion process for the analysis,a mathematical model of seed movement mechanism was established and the process of seed movement condition were analyzed in detail.And the seed-clearing process of multi-body dynamics was built based on ADAMS software. Simulation model of clearing dynasty revealed the process of the motion law of seeds. Results show that this seed-taking device can effectively clean off the excess seeds in the whole process with no jam and no hurt seeds. This device, taking reasonable design and mathematical model is correct, lay the foundation for the optimization design and kinematics and dynamics research of this new metering device. This paper provides new ideas and structure for the design and study of hole metering device, and also provides theoretical basis and guidance for the developing of prototype and the test of bench machine.

Research on Turbulence Regulation of Low Viscosity Liquid-solid Two-phase Abrasive Flow and Finishing Technology of Structural Surfaces

SUN Shu-Feng-1, 2, JI Shi-Ming-1, TAN Da-Feng-1

2011, 22(19):  2349-2353. 

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The structural surfaces are not easy to be finished by polishing tools. A new method of precision finishing based on low viscosity liquid-solid two-phase abrasive flow was provided. With this method, flow passage was constructed by restraining modular block and structural surfaces to be machined. Liquid-solid two-phase abrasive flow was made by mixing low viscosity liquid with micro abrasive particles according to a definite volume fraction. When the turbulent abrasive flow passed through the constructed flow passages, the surface of flow passage will be finished gradually by frequent action of micro force and micro-scale machining of the abrasive particles. Disordering of the surface machining vein was easy to be realized under the condition of abrasive flow turbulence, which can improve surface quality. Therefore, contrast researches of pressure, velocity and turbulent kinetic energy of abrasive flow in the flow passage constructed by restraining modular blocks before and after optimization were carried out. The conclusion is that uniform turbulence is easy to be formed after the restraining modular block is optimized. Finishing experiments were carried out on a self-made low viscosity liquid-solid two-phase abrasive flow machining equipment. The experimental results indicate that the uniform surface roughness is obtained after the restraining modular block is optimized. And the surface roughness value reduces from Ra=93.28nm to Ra=42.78nm after 50 hours’ finishing, which proves the feasibility and effectiveness of this method.

Study on Fabrication of Superhydrophobic Surface Substrate Based on ECM

XU Wen-Ji-1, DOU Qiang-Le-1, SUN Jing-1, SONG Jin-Long-1, LONG Gui-Bing-2

2011, 22(19):  2354-2359. 

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A new method of fabrication superhydrophobic surface by means of ECM was developed. The fabrication mechanism was based on the fact that the grain boundaries/dislocations were micro/nano-scale and more likely to be anodic dissolved than that of grain self, so the multi-scale micro/nano-structures surface can be generated by an applied electric field and the chemical solution. The relationship among processing quality, efficiency and conditions was studied in experiments herein.The results show that ECM can be used to fabricate dual-scale micro/nano-structures on aluminum surfaces, and further applied to generate the large size of superhydrophobic surface. The method is easier to control the reaction process than chemical etching meanwhile more economical than other techniques. After modified with low surface energy materials, the surface exhibits superhydrophobic property with water contact angle of 167° and tilt angle less than 3°.

Research on Design Method of Active Disassembly Products and Design Criterion Based on Electro and Heat Stimulation

LIU Zhi-Feng-1, CHENG Huan-Bei-1, LI Xin-Yu-1, DIAO Liu-Xian-1, ZHANG Hong-Chao-1, 2

2011, 22(19):  2359-2364. 

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The paper put forward to active disassembly, multi-step active disassembly methods and design criteria based on electro and heat stimulation. General design method of active disassembly product based on electro and heat stimulation was explained through the case analysis. Finite element analysis results are compared with experimental ones, electro and heat stimulation experiments were compared with the traditional heat stimulation experiments, and then the feasibility of method was proved. Active disassembly method and the design criterion were used in active disassembly design of products, disassembly efficiency for products are improved obviously.

Discussion on Several Problems for Chaotic Metal Transfer in Arc Welding

LV Xiao-Jing, SONG Hai-Feng

2011, 22(19):  2365-2369. 

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The drawback in mathematic model of metal transfer was analyzed, and it was the attention being only paid to droplet movement of different stages in a single transfer period. According to the related chaos theory and the related chaotic movement characteristics in dripping faucet,a establishing chaotic model can reflect better in essence the metal transfer is put forward. The progresses of chaotic research on drop transfer and short circuiting transfer were introduced and the problem was pointed out that an accurate chaotic model is needed urgent to be established at present. The developments in different chaotic control objectives of arc welding in the future were prospected.

Finite Element Analysis of Material Microstructure Effect in Micro-cutting Processes

LONG Ying-Chun, LI Ying

2011, 22(19):  2369-2374. 

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In order to investigate the influences of material microstructure on the size effect in micro cutting,a microstructure-level simulation model was developed to characterize machining behavior of heterogeneous materials. The results show that, for a given material microstructure, the chip morphology changes as the uncut chip thickness changes. When the uncut chip thickness is decreased from hundred microns to few microns, the chip formation changes from continuous to a quasi-shear-extrusion, and the uncut chip thickness is more close to the size of the smallest grain, the extrusion is more obviously; in the stress diagram, the maximum stress appears around the tool edge and the grain boundary.It illustrates that the material microstructure effect is prominence during micro cutting processes.

Research Progresses of Design Methods for Axial Magnetic Coupling Drive Mechanisms

MEI Shun-Ji-1, ZHANG Zhi-Meng-1, 2, XU Qiao-1, 3, DU Xing-1, WANG Zhi-Wei-1, LIU Beng-1

2011, 22(19):  2375-2381. 

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This paper dealt with the research status, limitation and existing problems in the aspect of the design theory and method,dynamic characteristics, computation of magnetic field distribution of the magnetic coupling drive mechanisms. The further research issues and research trend for the axial magnetic coupling drive mechanisms were put forward. It is necessary to research and establish a rather exact digital design and optimization design theory and method based on the magnetic coupling dynamic characteristics, to research and establish a rather fast and exact computation method for the permanent magnetic field with large air gap which can adapt to the demands of optimization design, to deal with theoretic and experimental research on the dynamic characteristics of the mechanisms such as torque angle characteristic, eddy-current loss, stability, dynamic stiffness, vibration performance. 

New Progresses on Magnetorheological Finishing(MRF) Technology

CHEN Feng-Jun, YIN Shao-Hui, TU Jian-Wu, XU Zhi-Jiang

2011, 22(19):  2382-2392. 

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The latest progresses on development and research of MRF in recent years were introduced. The machining mechanism, small and large processing machines and related equipment, machining technology and processing experiment, processing algorithm and model, development technology of magnetorheological fluid were summarized and analyzed in details. Some key technologies and the problems of MRF were discussed, and the future research direction was prospected.