Table of Content

25 December 2008, Volume 19 Issue 24

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Static Stiffness Research of a Hybrid Machine Tool Based on the Element Stiffness Matrix

Liu Yue, Wang Jinsong, Wang Liping

2008, 19(24):  2899-2903. 

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This paper addressed the static stiffness of a new heavy hybrid machine tool XNZH2430,which was developed in Tsinghua University based on a 2-DOF translational parallel mechanism.In analysis process, the structure of the machine tool can be represented by a number of nodes and elements.The holistic stiffness matrix of the machine tool was built based on the theory of element stiffness matrix.The stiffness distribution of the machine tool within a certain work space was analyzed.The analysis result indicates that the machine tool has better stiffness performance when the moving platform is close to the symmetric position.When the platform is away from the symmetric position,stiffnesses along the y and z directions are turning worse dramatically.Therefore,the moving platform should stay close to the symmetric position during working process.

Material Removal Mechanism for Abrasive Jet Finishing Restricted by Grinding Wheel

Liu Feng, Gong Yadong, Shan Yuqiao, Cai Guangqi 

2008, 19(24):  2917-2922. 

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The material removal mechanism of Abrasive Jet Finishing（AJF） was investigated based on the size ratio of characteristic abrasive size to the film thickness between grinding wheel
and workpiece.Two-body lapping and three-body erosion mode by a single abrasive and the mode of material removal rate were established. Experiments were performed on a cylindrical grinder MB1332A with a 45 steel workpiece as specimen of which the surface roughness values of Sa=06μm.The micromorphology of machined surface morphology was observed using SEM and the microcosmic geometry parameters were measured with MICROMESVRE2 profilometer. It is found that experimental results match theoretical analyses.The machined surface changed from continuous parallel micro-groove to randomly distributed discontinuous micro-pit and Sa gradually decreased from an initial value of about 06μm down to about 02μm with the increase of machining circles. Furthermore,the isotropy surface and uniformity veins both parallel and perpendicular machining direction are attained by the finishing process to improve greatly the wearable capability of the workpiece.

Design and Research of Embedded Controller of an 4-wheel Differential Drive Automate Guided Vehicle

Song Libo, Li Jinsong, Fei Yanqiong

2008, 19(24):  2903-2977. 

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An AGV of two front passive wheels and two rear differential-driven wheels was designed.The nonholonomic state space equations in the flexible mode was obtained with the Newton method and the matrix analysis method taking the nonholonomic constraints and the friction force of the bearings into account and considering the motion speed and the turning velocity to be as the state parameters.Meanwhile,the motion control equation was designed with the full state feedback pole placement method,and the embedded control system of the DS87C520 controller and the PSD813F2 chips was also developed.The reliability,real-time and robust qualities of the nonholonomic state space, and the embedded control system were approved and validated with the simulation and the experiments.At last,some conclusions were drawn.

ZMP Compensation Optimization of Variable Structure Controller for Biped #br# Robots

Da Lin, Fang Yuefa, Huai Chuangfeng

2008, 19(24):  2908-2911. 

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This paper designed a variable structure trajectory tracking controller for biped walking robot system.The ZMP equation and sensed ZMP information were used in this trajectory generation strategy.The real-time trajectory planner generated the trajectory of the base link in the vertical direction to compensate the required moment for recovering stability and gained modified ZMP trajectory finally.Computer simulation with a 12 DOF biped robot tested the proposed optimization method.The simulations indicate the robusticity and applicability of the method in real implementation.

Mechanism Analysis and Experimental Research on  #br# Novel Linear Ultrasonic Motor with Large Thrust 

Li Yubao, Shi Yunlai, Zhao Chunsheng 

2008, 19(24):  2912-2916. 

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A novel butterfly-shape linear ultrasonic motor was proposed and designed.The idle speed is 0.75m/sec, and the output force is 16N, which is 22 times of the stator weight at the pre-presure of
70N.The maximum efficiency is 42% at the output thrust of 8N and the speed of 0.51m/sec when the mechanical output power is4.08W.It utilized two orthogonal vibration modes.One is symmetrical mode and the other is anti-symmetrical mode and their composited modes.Based on analysis of the vibration modes of the stator,the kinematics model of the stator was build and the elliptical track of the driving tips was deduced.

A New Threshold Based Machine Vision Method for Surface Roughness Inspection

Chen Zixin, Huang Ren, Shi Jinfei, Zhang Zhisheng 

2008, 19(24):  2922-2925. 

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A non-contact surface roughness inspection method based on machine vision was used to assess different cylindrical grinding surfaces from 01μm to 08μm in different ambient light environment. A new method that counts the pixel numbers whose gray value is larger than sum of the Otsu threshold and a given constant was proposed to represent different roughness in surface inspection.This method was compared with the methods based on standard deviation of gray-level distribution proposed by Luk and the gray-level co-occurrence matrix.Results show that variance sum between inspecting values of the proposed method and its corresponding real value is less than half of the other two ways. 

Mobile System of Lunar Rover Based on Half-rotating Mechanism and Its #br# Kinematics

Yu Xiaoliu, Luo Hui, Xia Wei

2008, 19(24):  2926-2929. 

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A new type of mobile system based on half-rotating mechanism was introduced according to the characteristics of the lunar exploration.It was introduced the characteristics and mechanism principles,compared the undulation of one-level half-rotating mechanism to that of two-level half-rotating mechanism, and derived the solution of the forward kinematics of the leg of the lunar rover.The result shows that the undulation of the lunar
rover based on two-level half-rotating mechanism is about 60% lower than that of the lunar rover based on one-level half-rotating mechanism.

Study on Starting Performance for High-torque Low-speed Hydraulic Motors

Xi Jingcui, An Gaocheng, Wang Mingzhi 

2008, 19(24):  2929-2933. 

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The concept of the simulation startup process with micro gliding states for the friction pairs of hydraulic motor was put forwards,the magnitude of theoretical instantaneous torque and the losses of friction
torque were also discussed,which affected startup performance of the hydraulic motor.For the 2SJMD-100 hydraulic motor the quantitative calculation formula,a new and simple experimental method and data with “locking elastic shaft” were given.

Research on Green Manufacturing Pattern Evaluation of Automotive Manufacturing Enterprises

Wang Yongjing, Liu Fei, Wang Qifeng, 

2008, 19(24):  2934-2943. 

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An index system was proposed including the main index of time,quality,cost,service,resource,environment and the sub-index which comprised 25 indexes to evaluate the GM. An evolutionary back-propagation neural network(BPNN) by GA(genetic algorithm) was introduced to evaluate GM.GA was used to optimize hidden layers,learning rate and momentum factor.BPNN was adopted to evaluate the GM. The evaluation result was anlysized at last.

Production Operating Mode of Equipment Integration for  #br# Order-made Large-scale Equipment Manufacturing Systems

Liu Jun, Liu Fei, He Yan

2008, 19(24):  2938-2943. 

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Aiming at the situations in the large equipment manufacturing systems, a production operating mode of equipment integration was proposed. The five-level architecture of the mode was constructed, which consisted of objectives, process execution, information interaction, status analysis, information collection. On the basis of these, the framework of the platform for the information collection and interaction was established, which is one of the key support systems of the mode. The example in the shop floor manufacturing system of metallurgic equipment illustrates the application of the mode.

Study on Sequence Planning of Two Dimensional Multi-station  #br# Assembly Based on Stream of Variation Analysis  #br# 

Wen Zejun, Liu Deshun, Yang Shuyi

2008, 19(24):  2944-2949. 

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Based on the poor quality of present assemble sequence planning aimed at producing time and operating cost, stream of variation analysis method(SOVA) was applied to investigate sequence optimization of two dimensional multi-station assembly in order to improve the assemble quality of products.As study object of two dimensional multi-station assembly process,the variation source of affecting assembly quality was analyzed,a mathematic model of dimensional variation propagation was established,and the concept of “assembly robust degree” was put forward to describe and judge whether the assembly sequence was well.The assembly sequence of four parts on the white body of automotive was given for an example,three kinds of different assembly sequence through using assembly robust degree were analyzed and compared,and the satisfactory assembly effect was obtained.The example and its simulation indicate that the SOVA can be used to analyze and choose assembly sequence scheme.It provides a new method for optimization design of two dimensional multi-station assembly processes.

Research on Variant Design and Parameter Transfer Method for Complicated Products

Wu Qingming, Zong Chi, Zhang Qiang, Yang Wei

2008, 19(24):  2955-2960. 

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To deal with 3-dimensional and finite element variant design and analysis for complicated products,the modeling approach for products and parameter transfer structure were researched,parameter transfer rules adaptive for complicated product variant design were proposed，the affection relationship among parameters for model variant was raveled. The variant design platform for complicated products was introduced, and complicated product variant design and analysis were realized. The variant design platform of sluice gate gantry crane was developed, and as an example, all methods were applied and verified.

Maturity Based Procedure Model for Maturing Parts from Parts to Standard Parts

Mo Rong, Yin Yaqun, Chang Zhiyong, Zhao Jie

2008, 19(24):  2950-2954. 

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To solve the problems of part information dispersed and lacking in the procedure management of standard part growing from part,a maturity-based procedure model for presenting standard part growing from part was proposed.The maturation concept in software was introduced into the model, the maturity grade and growing rules of part were defined.The factors and conditions growing from part to standard part in the growing procedure of part (part-borrowed part-general part-standard part) were put forward.The system architecture for managing the standard part growing procedure was designed and the solution to the implementation was given. The part growing procedure model provides an effective method for standard part growing from part, which can be employed to trace the history information of standard part growing procedure and implement grading from part to standard part.

Dynamics Modeling and Modal Analysis of Square Plansifter Based on Rigid-flexible Coupling

Qiu Ming, Liao Zhenqiang, Jiao Weidong, Fan Lixia

2008, 19(24):  2960-2964,2990. 

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The rigid-flexible coupling dynamics modeling and modal analysis were employed to study the system consisted of square plansifter and flexible suspender. Since the body of plansifter and the eccentric object were considered as rigid body and the suspender as elastic body, the circular equation of steady-state vibration of the plansifter body and the cantilever beam model of suspender were established respectively. The natural frequency of the system and the equivalent bending stiffness of the suspender were deduced. By using FEA, the first 20 modes and the displacement response were obtained from the normal mode analysis and the transient response analysis respectively. It is shown that the dynamics relationship between the body of plansifter and the suspender can be well revealed by the theoretical model, and the real vibration characteristics can be simulated accurately by
FEA whose loads and boundary conditions are based on the theoretical analysis. 

Micro-structures on Friction Unit Working Surfaces and Their  #br# Ultrasonic Combined Electrical Micro-machining 

Zhu Yongwei, Wang Zhanhe, Fan Zhongjun, Yun Naizhang

2008, 19(24):  2965-2971. 

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The friction characteristics of surface with micro-structures were analyzed.Three reasonable micro-pits with the shapes of square, rhombus and cylinder were designed.The micro-protrude electrodes were manufactured by combined electrical discharge machining.The ultrasonic
combined electric micro-machining system was built and the micro-structures were machined by ultrasonic combined electric micro-machining technology.The tests of manufacturing micro-structures were carried and the micro-machining mechanism was analyzed and discussed.The friction tests were carried out.It is verified that friction surfaces with regular profiles micro-structures(pit or protrude) have less friction coefficient and wear.It is very helpful for improving the friction performances and raising working life of important friction units.

New Algorithm SGD of Surface Modification and Its Application in Springback Compensation

Nie Xin, Cheng Aiguo, Shen Danfeng, Zhong Zhihua

2008, 19(24):  2972-2976. 

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The SGD algorithm was presented and applied to the modification of surface in springback compensation.The surface was globally modified based on the original surface.The topology consistency of surface before and after mdification can be ensured and the high-quality and smooth surface was obtained.It is proved to be reasonable in practice and the result indicates that the time and cost can be saved. 

A Tolerance Analysis Method for Feasibility of Assembly #br# 

Xu Xusong, Yang Jiangxin, Cao Yanlong, Liu Yancong

2008, 19(24):  2976-2981. 

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Based on new generation GPS(geometrical product specification and verification),the compostion of geometrical information of assembly was analyzed.The modeling method based on DOF(degree of freedom) analysis and mapping relations between variation zone and SDT(small displacement torsor) were studied.The propagation and accumulation of characteristic geometrical deviation were described using HTM(homogeneous transformation matrix), and the assembly tolerance accumulation model including tolerance information of part and gap information of assembly was established.Then,matrix equation of tolerance loop was put forward.Two simple examples were used to explain the condition of part assembly feasibility and assembly tolerance analysis process.Lastly,an example of engineering analyzing and computing was presented.

Study on Single-cell Contact of High-Temperature Sweating and Self-Lubrication Materials

Xie Fang, Liu Zuomin

2008, 19(24):  2982-2986. 

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A new thick wall of single-cell contact theoretical model was developed with the stress concentration method of isolated hole
in “infinite board”and the characteristic parameters of λ, and the high-temperature sweating and self-lubricating materials were taken as an example to simulate and analyze the intracellular stress distribution of single cell
body within the scope of λ≤0.4 based on the model. The results show that: As the load increasing, the contact radius increases gradually and all of the stress in the contact region become bigger gradually; the maximum of shear stress gradually migrates from the cell surface to the internal cell, while the greatest of y-stress transfers from the contact center to the θ=0 and θ=-π,r=r₂ of the pore; and the maximum of x-stress transfers from the contact center to the θ=-π/2,r=r₂ of the pore;the stress concentration area gradually replaces the contact surface to be the source inducing micro-cracks. The parameters of
λ also has a great influence on the contact stress distribution:
when λ=0.4,the y-stress margin of the pore stress concentration region and the contact region is the largest;while λ=01,the x-stress margin of these two places is the largest; when loads is greater than 1000N and λ=02,the maximum of shear stress is the minimum.

Forward Kinematics Analysis of 2UPS-2RPS Parallel Mechanism Based on Single-opened-chain 

Feng Zhiyou, Zhang Ce, Yang Tingli

2008, 19(24):  2986-2990. 

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A new method of velocity and acceleration analysis for 2UPS-2RPS parallel mechanism based on single-opened-chain was presented.The mathematical models of velocity and acceleration analyses,which
were uniform with one of the position analysis,were established according to the topological structure characteristics and the same course of topological structure decomposition.The velocity and acceleration equations of the mechanism were derived.An numerical example of the velocity and acceleration analysis was given.

Experimental Research of On-line Monitoring Interelectrode  #br# Gap of Electrochemical Machining (ECM) Based on Current #br# 

Lu Yonghua , Zhao Dongbiao , Yun Naizhang, Liu Kai

2008, 19(24):  2999-3002. 

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Arming to on-line monitoring interelectrode gap,turbine rotor blade of aero-engine was acted as research object, and machining current of ECM was acted as research parameter.Machining experiments using three kinds of cathode profile such as plane,slant and blade surface were
implemented,and the plane and slant equations between current and interelectrode gap will be set up based on the principle of least square multi-variables linear iteration method.Furthermore,experimental data of blade machining
were used to check up and modify the acquired equations. At last, the modified equation will be set up.The relation between each parameter in equations was analyzed and such conclusion is drawn:under 15 percent error range,the equation can be used to on-line monitoring the inter-electrode gap of ECM.

Gradual Changing Threshold Selection of Lifting Wavelet Package and Quantizing De-noising Method

Cao Jianjun, Zhang Peilin, Shao Yanzhen, Zhang Yingtang, Ren Guoquan

2008, 19(24):  2991-2994,3023. 

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In order to on-line process engine cylinder head vibration signals of mobile equipment, a de-noising method with gradual changing threshold based on lifting wavelet package transform was proposed. The lifting wavelet package transform based on interpolating subdivision was introduced. The engine cylinder head vibration signal’s time-frequency characteristics were analyzed. To fit in with the features of signal and noise, a strategy of gradual changing threshold selection and quantization was presented. The evaluation criterion of de-noising effect based on separability measurement of feature classes was introduced, and the quantitative evaluation of de-noising effect for the real vibration signals was realized.From the application example,using the strategy of gradual changing threshold selection and quantization,the noise is deleted and the useful information is reserved well in the whole frequency band.Compared with other methods,it owns better de-noising effect and universality.

Analysis of Spectral Entropy Based on DCT and FFT and #br# Its Application to the #br# Condition Detection and Tendency Estimate of Mechanical Transmission System

Shao Renping, Huang Xinna, Hu Junhui

2008, 19(24):  2995-2999. 

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This paper studied and analyzed the vibration signals of gear of a mechanical transmission based on the spectral entropy by using DCT and FFT,the working condition was detected and runing tendency was estimated for the transmission system.The results show that DCT is good at exhibiting the signal features in frequency-domain and is able to distinguish and cluster the different gear signals for mechanical transmission while FFT is clever at analyzing and forecasting the deterioration tendency for gear of mechanical transmission.It
provides an dependable approach to detect working condition and diagnose runing tendency for mechanical transmission and mechanical systems.

A Conceptive Noncircular Planetary Differential for Off-road Vehicles

Jia Jumin, Gao Bo

2008, 19(24):  3003-3005. 

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Integrated with three noncircular gear items,a new noncircular planetary differential was put forward,which may deliver variable proportional torque onto its two output axes.The new conceptive differential may be applied to off-road vehicles and may help to improve passing capacity.The driving theory and the design method of pitch curves were presented,and several case studies were illustrated.

Study on the Structural Improvement Methods for Car Side Impact Safety

Lu Yong, Cao Libo, Wu Jun

2008, 19(24):  3006-3011. 

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In order to improve the side impact safety of a production car which can not meet the need of the side impact occupant protection regulation,the possible reasons for the poor side impact properties of the car were analyzed.Based on the general principles for side structural design and comparison with the side impact deformation results of other similar cars, the improvement measure by changing the structure of B-pillar,decelerated panel of inner wall, anti-collision pole of door and door step was presented.The finite element model of the car was developed and validated. The FEM simulation and passenger injury analysis based on the PSM(prescribed structure motion) method were performed to demonstrate the effectiveness of the measure. The simulation results
show that the intrusion of the door and the passenger injury parameters
are decreased significantly,and so,the side impact safety of the car can be improved.

Bonding Techniques for Fabrication of Thermoplastic Microfluidic Chips

Luo Yi, Wang Xiaodong, Wang Liding

2008, 19(24):  3012-3018. 

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In fabrication of microfluidic chips, bonding of substrate and cover is the procedure for formation of enclosed micro channels, and is one of the key techniques for fabrication of microfluidic chips, directly affects the quality of the fabricated products. Bonding methods and techniques were summarized, and the limitations of fabrication quality, efficiency and suitability for batch production in available bonding methods were analyzed. Finally, recent research on ultrasonic bonding method was introduced, which has high production efficiency and is suitable for batch production.

Research Progresses of High Efficiency and Precision Grinding for Hard to Machine Materials

Deng Zhaohui, Wan Linlin, Zhang Ronghui

2008, 19(24):  3018-3023. 

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According to the characteristics of hard to machine materials, the paper discussed the grinding performance of typical hard to machine material. A comprehensive review on the research progresses of creep grinding and precision grinding for hard to machine materials at home and abroad was presented. The fundamentals of high efficiency deep grinding and its development on the hard to machine materials were induced. It points out that the hard to machine materials can be machined by high efficiency deep grinding technology with high quality and efficiency, and high efficiency deep grinding for hard to machine materials has a wide application prospect. In the end, a prospect of the advanced research in this aspect was made.