China Mechanical Engineering

Machinery Fault Detection Based on a Small Sphere and Large Margin Approach

HAO Teng-Fei, CHEN Guan

2012, 23(15): 1765-1770.

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In machinery fault detection, normal examples are much more than fault examples and the training examples are highly imbalanced. Aiming at this problem, a small sphere and large margin approach was used for machinery fault detection and a machinery fault detection method for imbalanced examples was put forward. The proposed method can use both of many normal examples and few fault examples to train. It constructed a hypersphere that contained normal examples in the feature space by training, such that the volume of this sphere was as small as possible, while at the same time the margin between the surface of this sphere and the fault examples was as large as possible. This method was applied to fault detection of rolling element bearings and comparisons were conducted with support vector machine and support vector data description. Experimental results validate its effectiveness in the machinery fault detection where the training examples are highly imbalanced.

Feature Extraction of Pulsed Eddy Current Signals on Metal Thickness Measurement

ZHOU De-Jiang-1, 2, LI Yong-3, ZHANG Qiu-Ju-1, YOU Li-Hua-1

2012, 23(15): 1771-1773,1778.

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This paper introduced the current research states of PEC thickness testing. The main purpose of this paper is to improve the properties of the PEC sensor, the sensitivity and linearity of current features for metal thickness measurement were evaluated in both of time and frequency domain using PEC nondestructive testing (NDT). Experimental study was conducted with aluminum slabs in different thicknesses. Based on the comparative study of the feature extraction techniques, the most suitable feature was discussed. 

#br# Error Analysis and Compensation for Touch Trigger Probe of On-machine Measurement System

WANG Li-Cheng, HUANG Shen-Da, DING Han

2012, 23(15): 1774-1778.

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On the basis of analysis on the errors from touch trigger probe of OMM, a method to correct the offset of probe was given, and the actual effective radius of probe was calibrated by means of a calibration ball. Oriented to practical measurement task, a new probe radius compensation method based on on-line calibration and bilinear interpolation techniques was presented. The verification experiments of radius compensation show that the accuracy by this method, compared to the method provided by the commercial software, can be much improved.

Detection and Characteristic Analysis for Mass Center Orbit of Bearing Cage

HUANG Di-Shan

2012, 23(15): 1779-1784.

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Taking a cage bearing as the experimental object,a detecting method of mass center orbit of the cage was studied and the time domain analysis was explored.Through signal processing on the radial vibration and signal synthesis,the mass center orbit of cage was investigated by use of two laser sensors perpendicularly installed on the bearing radial plane.Meanwhile,the effects of axial loading on the mass center orbit of cage was analyzed,the characteristics of time variation and box dimension were observed and the impact of filtering and deform of the cage on measurement results were discussed.The investigation results show that the experimental investigation is significant to quality assurance for a ball bearing.

#br# Analysis of Influences of Angular Vibration on MTF in Optical Imaging Systems

LI Yu-Long, HE Zhong-Bei, BAI Hong-Bai, LI Dong-Wei

2012, 23(15): 1784-1788.

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This paper analyzed the influences of angular vibration on MTF in optical imaging systems. First, according to the characteristics of angular vibration, angular vibration was decomposed into linear vibration relative to the focal plane, and the relation between angular vibration and the linear vibration was established. Second, principle with the product of each individual MTF was the total MTF, the influences of angular vibration on MTF in optical imaging systems were derived. Finally, the various sources of angular vibration frequency were analyzed with practical engineering, and the methods reducing the angular vibration effects on image quality of the optical system were proposed. 

Wear Compensation of Grinding Wheel for Inclined-axis Grinding Small Aspherical Surface

LIU Lin-Qi-1, 2

2012, 23(15): 1789-1792.

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Contrasting to the common ultra-precision grinding mode, an inclined-axis grinding method was proposed. The changing regularity and testing mode of the wear amount of grinding wheel were analyzed for grinding micro aspherical surface. The influences of radius error of grinding wheel on the shape accuracy of the workpiece were studied. Through the wear error compensation grinding experiments of aspherical mold, the form accuracy of small aspherical mold with diameter in 6mm is improved from PV 1929nm to PV 359nm.

Research on Aerostatic Probe for Magnetic Flux Leakage Testing for Steel Pipe in High Testing Speed

JIANG Xian-Xiang-1, 2, KANG Yi-Hua-2, WU Jian-Bei-2

2012, 23(15): 1792-1795.

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In order to solve the problems caused by high magnetic flux leakage testing speed for steel pipes,an aerostatic probe was proposed and the relationship among the static characteristics and structure parameters was analyzed.Finally,an aerostatic probe for steel pipe with diameter of 130mm was designed.The novel probe is especially suitable for high testing speed for that the friction between the probe and the steel pipe is avoided by the air-film.

An Inside Singularity Elimination Method for Parallel Mechanisms Based on Non-instantaneous Branch Link Configuration Design

LIU Yan-Bin, LI Zhi-Song, HAN Jian-Hai

2012, 23(15): 1796-1802.

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Constraint singularity configuration, drive singularity configuration and branch singularity configuration were systematically discussed based on the screw theory, and it was emphasized that the constraint singularity configurations and drive singularity configurations existing within the workspace created the most severe effects on performance of the parallel mechanisms. And then, an inside singularity elimination method for parallel mechanisms based on non-instantaneous branch link configuration design was presented. Finally, the 3-RRR, 4-RPTR and 3-RRRT parallel mechanisms were taken as examples for systematically expatiating design course of the inside singularity elimination method. The results show that except for the configuration under which motion platform superposes base plane, the other inside singularity configurations can be eliminated entirely. The research fruit can provide a reference for the solution to the key problems on redundant actuation method.

A Study of Diesel Cylinder Head Cooling Using Nano-flow Coolant with Jet-flow Method

ZHENG Wei-1, 2, ZHANG Zhen-Dong-1

2012, 23(15): 1802-1807.

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To improve the thermal performance of a diesel engine cylinder head, this paper presented a method that multi-metal nano-flow coolant as a new cooling fluid, using jet flow technology to improve heat transfer coefficient at the cylinder head intake and exhaust valves nose. After tests,it is found that, with the same jet flow parameters, the different volume share multi-metal nano flow has more heat transfer coefficient than that of traditional coolant, but the effects of the volume fraction increase are limited. The same volume share multi-metal nano flow shows different heat transfer performance because the impact of different jet angles and jet distances.At the same time, its own viscosity increases will cause more drive power cost. Heat transfer coefficient of multi-nano-flow is better than that of traditional coolant in cylinder head nose.

#br# Investigation of Nonlinear Dynamic Characteristics for Servo System of a Hydraulic Excavator Arm

LI Bei, YAN Jun, CENG Yong-Hua, GUO Gang

2012, 23(15): 1807-1810.

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In order to analyze the joint-servo control system for an excavator arm,and improve its control property,a nonlinear model for the system based on theoretic analyses was constructed.The nonlinearities included dead band of the electro-hydraulic proportional valve,asymmetry dynamic characteristics of the valve-controlled asymmetric cylinder,nonlinear friction force of the cylinder,nonlinear spring force of the cylinder,and nonlinear dynamic model of the excavator arm.The nonlinear characteristics of the system were verified by experiments.Experimental results demonstrate all the nonlinear characteristics has bad influences on the dynamic response of the system,thus it provides a theoretic reference for the controller design.

Genetic Algorithm for Job Shop Earliness and Tardiness Scheduling Problems with Deadlines

LI Hai-Ning, SUN Shu-Dong

2012, 23(15): 1811-1818.

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This paper studied a job shop scheduling problem with due dates and deadlines in the presence of tardiness and earliness penalties.In order to solve this problem,an enhanced genetic algorithm(EGA) was introduced herein.EGA utilized an operation-based scheme to represent schedules as chromosomes.After the initial population of chromosomes was randomly generated,each chromosome was processed through a three-stage decoder,to reduce the total earliness and tardiness penalties with meeting deadline constraint of jobs, in which the active decoding, chromosome repair and reverse rescheduling was operated in turn.The proposed algorithm was tested on 180 job shop scheduling problems of varying sizes and its performance was discussed.

Service-oriented Unified Manufacturing Resource Modeling Based on Meta-model

HUI Wen, LI Dong-Bei, TONG Yi-Fei

2012, 23(15): 1818-1824.

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In order to solve the manufacturing resource integration problems of multi-application system in the networked environment,a service-oriented manufacturing resource was constructed based on meta-model.Context meta-class was introduced in the meta-model which was abstracted form basic data,business process and application extension.An information model was impressed based on meta-concept,meta-attribution and meta-relation.Then the mechanism of expanding meta-model was analyzed and the unified manufacturing resource information framework was presented.Furthermore,it is found an extensible,integrated and service-oriented digital manufacturing resource management platform is built by related information technology of service-oriented. 

High-speed Adaptive Interpolation Algorithm Based on NURBS Fitting for Micro Sections

CHEN Bin-1, JI Dang-Jin-1, FAN Liu-Qun-1, 2, SHU Zhi-Gao-1, 2

2012, 23(15): 1825-1829.

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In order to actualize the high speed and high quality machining, and improve the micro-segment processing, which had the faults of too large capacity of the NC files and frequent acceleration/deceleration controlling in the machining process,a high-speed adaptive NURBS fitting method was developed to actualize the smoothing milling, which was under the constraints of least square approximation algorithm and weight factors of data points. The new fitting algorithm was a high-speed adaptive interpolation algorithm based on NURBS fitting for micro sections. The key of the new algorithm was to fit the micro sections into a new tool path made of NURBS. And then, the new tool path can be interpolated easily by the NURBS interpolation algorithm. Under this method, the machining with micro sections of tool path will be smooth and efficient.

#br# Research on Elastic Contact of Finite Element Model of Bolted Connection

XU Zi-Wen-1, NA Jing-Xin-1, ZHANG Zhi-Yuan-2, WANG Tong-1

2012, 23(15): 1830-1832,1839.

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Utilizing rigid-beam element to simulate the structure of bolted connection cannot calculate the local stress of bolted connection. Therefore, an elastic contact based bolted model (GAP element was introduce to define the elastic contact and friction condition of bolted components) was proposed according to the structure and characteristic of bolted connection. Finally, a test was designed to verify the validity of the proposed method.

Structural Feature Extraction from Point Clouds Based on Multi-scale Tensor Decomposition

LIN Hong-Ban, LIU Ban, ZHANG Yu-Cun

2012, 23(15): 1833-1839.

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To solve the conflicts between the ability of weak feature extraction and noise resistency of traditional algorithms, a new feature extraction algorithm was proposed based on multi-scale tensor decomposition. Firstly, feature saliency encoding was defined based on the singular value decomposition of tensor matrix. Secondly, normal(tangential) consistent measure was constructed and used to determine the maxmuim scale combined with Romanovskii criterion. The reliability of the feature reconizing algorithm is improved. Finaly, the feature lines were constructed using minimal spanning forest. Expremental results reveal the weak feature extraction and noise resistency abilities of the method.

Finite Element Simulation for Structure Property of TRT Volute

LI Ji-Gong-1, CHAO Li-Ning-1, XU Jin-2, ZHANG Min-1

2012, 23(15): 1840-1843.

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Stress and deformation of a welded TRT volute by static load and water pressure were stimulated initially with the method of elastic-plastic finite element method. The results show that the function of the whole volute's stress value in the static load is not big. The greatest stress is 19.1MPa and in terms of constraint place the maximum equivalent stress is mainly concentrated. The maximum displacement is 0.0776mm in the whole volute and, it appears in lower shell in supporting pole.In water pressure test, the whole volute stress value is all between 40 to 85MPa, only local small-scale is reached 382MPa. Under the action of water pressure, maximum overall displacement of the whole cabinet appears on export baffle, and the value is 1.511mm. Deformation in the volute is not remarkable.

Attribute Recognition Theoretical Evaluation Model of Strip Steel Quality and Its Applications

DONG De-Wei, YA Yun-Hui, SONG Ke-Chen, BANG Yi-Shu

2012, 23(15): 1844-1847,1854.

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Aiming at features of strip steel's quality evaluation problem with multi-attributes and multi-indexes, a strip quality comprehensive evaluation attribute recognition model was proposed. Based on the basic concepts of attribute recognition theory, for example, attribute set, attribute measure and ordered partition class, a quality level attribute set was established and the attribute measure of single index and comprehensive attribute measure were calculated. Confidence criterion and grading criterion were as discriminant criteria,the quality level of strip steel was evaluated according to confidence criterion, the quality differences of the same level of strip steel were distinguished according to grading criterion. Experimental results show that the performance of this new method is accurate and effective.

#br# Experiment Study for Oil-line Debris Electrostatic Monitoring of Brass

CHEN Zhi-Xiong-1, 2, ZUO Hong-Fu-1, DAN Zhi-Juan-1, ZHANG Ying-1, CA Jing-1, SUN Jian-Zhong-1

2012, 23(15): 1848-1854.

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In order to deeply understand the condition monitoring capability of the non-ferromagnetic metal materials such as brass alloy, an oil-line debris electrostatic sensor was used to investigate the method of electrostatic monitoring for brass. The charging mechanism of oil lubricated bearing steel-brass friction pair metallic debris was researched and an electrostatic monitoring system was designed. Three types of experiments were carried out. The first one was the particles injection of three sizes bearing steel balls and brass balls single particle through the sensor and double particles through the sensor. The second was the sliding contact of the same load and different speeds friction and wear on modified pin-on-disc tribometer, then the friction coefficient, oil-line debris electrostatic signals, electrostatic signal root mean square (RMS) were obtained and the correlation was analyzed. The results show: the oil-line debris electrostatic sensor has better consistency of test results; the electrostatic monitoring capability of non-ferromagnetic metal materials such as brass is better than that of ferromagnetic metal materials such as bearing steel; the friction coefficient has a strong correlation with the electrostatic signals, during the stage of wear the electrostatic signal shows pulse and increases in the RMS of signal.

Research on Design Methods of LCD Active Disassembly Structure Based on Smart Materials

SONG Shou-Hu, LI Dong-Xu, LI Xin-Yu, CHENG Huan-Bei

2012, 23(15): 1855-1860.

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Shape memory materials were used as active disassembly unit of LCD frame and LCD frame was redesigned by using the method of ADSM. Active disassembly design principles of LCD frame were proposed. A mechanical analysis model of active disassembly unit was established. The layout position of active disassembly unit in the frame was simulated by ABAQUS,and optimal size and layout position of the active disassembly structure were determined. At last, the size, layout position and disassembly effect of active disassembly structure of LCD frame were verified by experiments. A theoretical reference is provided for the design of LCD active disassembly structure.

Periodic Deformation Based on Ridge Curves for Parametric Surfaces

LIU You-Ta, WANG Zhi-Guo, ZHOU Lai-Shui, WANG Xiao-Beng

2012, 23(15): 1860-1864.

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In order to obtain ideal modeling effects of parametric surfaces, a new polynomial extension factor was constructed. The new extension factor had excellence of the existed extension factors, and can achieve its maximum in the region. In the extended technique for free-form deformation of parametric surfaces, the original surface can be deformed by the ridge curves. Then the periodic deformation of a surface can be achieved by the ridge curves. Experiments show that the method is simple, intuitive and easy to control, and desired deformations can be achieved easily. It can be used in many fields such as geometric modeling, computer animation and CAD/CAM.

Research on Properties of Powder Pressure Transmission Medium in Hot State Internal High Pressure Forming

JIN Cheng-Zhu, TIE Ge

2012, 23(15): 1865-1867.

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In order to study the pressure transmission properties of composite powder between fine silicon powder and hexagonal boron nitride, this paper made use of mechanical press to apply force to the different mass ratio of composite powder under different temperature. Meanwhile, the inner wall pressure distribution was measured by high temperature resistant pressure sensor. The results prove that when the hexagonal boron nitride comes to 2% of the composite powder, the effects of pressure transmission property are the best. At the same time, it is found that temperature is not an obvious factor to influence the pressure transmission properties, and the properties will be steady with high temperature conditions. With 40Cr steel pipe fittings, the hot state internal high pressure forming experiment was explored where the composite powder was used as pressure transmission medium under 500℃. The experiment produces satisfied internal pressure forming parts.

Research on Treatment of Diamond Surface by Film Deposition and Induction Brazing

MA Ba-Jiang, CA Chi, XU Qiang-Xian

2012, 23(15): 1868-1822.

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Diamond grits were deposited by hot filament chemical vapor deposition (HFCVD) and they were used to fabricate the brazed diamond tools by induction brazing. The gas ratio (H2/CH4) used was 100∶1.5(standard cubic-centimetres per minute), the total gas pressure was maintained at about 2.0 kPa, and the substrate temperature was heated to 700℃ for 45 minutes during HFCVD. As a result, amorphous carbon film is deposited on the diamond surface. The diamond edges exposed out of the filler alloy keeps good sharpness after induction brazing of HFCVD deposited diamond. Chromium-carbides with uniform porosity and irregular shapes were formed on the diamond grits immersed into the brazing filler alloy. The liquid brazing filler metal filled in porosity can enhance the bonding strength between the brazing filler metal and the diamond grits. The heavy-load grinding tests of the brazed diamond wheels fabricated by three kinds of diamond grits show that there is a low percentage of pullout from matrix and whole grain fracture for the deposited diamond grits brazed by induction heating. 

Evaluation and Correction Control Strategy of Assistant Torque for EPS with Interference of Active Steering

WEI Jian-Wei-1, 2, WEI Min-Xiang-1, LI Yu-Fang-1

2012, 23(15): 1873-1876.

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To solve mutations of steering wheel torque with the interference of active steering, feed-forward assist force correction strategy for assist motor was presented. To verify the performance of the proposed control programs, step simulation tests of steering wheel torque with the interference of active steering were carried out. In view of the evaluation methods of transient characteristics for step response, evaluation indexes for correction control programs were introduced. Simulation and evaluation results of the performance of the two control programs indicate that the correction control program based on the output of torque sensor can achieve better steering feeling than that based on two-degree-of-freedom vehicle model.

#br# Research on Economical Gearshift Schedule for a Four-wheel Drive Hybrid Electric Vehicle

DIAO Chi-Guo, DU Jian, GU Jia-Ding, TU Zhuo-Beng

2012, 23(15): 1877-1884.

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The economical gearshift strategy for a four-wheel drive hybrid electric vehicle (HEV) was designed, which considered the influences of power battery as well as the characteristics of integrated starter/generator(ISG) motor and in-wheel motors. By calculating the equivalent consumption rate of engine and motors at any time, the vehicle was driven with the gear position which resulted in lowest synthesized equivalent fuel consumption rate in order to optimize fuel economy performance of the HEV. The new economical gearshift schedules for all kinds of working modes of HEV were simulated and analyzed in the MATLAB/Simulink software. Real vehicle test was carried out and the validity and feasibility of the economical gearshift schedules was proved.

Study on Electric Vehicle Control Based on Fuzzy Vector and Flux-weakening Theory

CHENG Bo-1, 2, XIE Min-1, 2, LI Xue-1, CAO Bing-Gang-2

2012, 23(15): 1884-1889.

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Based on the vector control algorithm of IPMSM used in electric vehicle (EV), a fuzzy-PI controller was designed and embedded in the vector control simulation system. The fuzzy control rules suitable to the motor control system were made by referring to experts experience and motor response curve. A double-condition was made that considering both of speed and duty cycle to judge whether the flux-weakening control was necessary. The strategy that directed axis current equals to zero under the turning speed and flux-weakening control above that was utilized. The simulation of fuzzy-PI vector control was completed and compared with PI vector control. Finally, by the experiments of IPMSM, it is proved that the response performance and running stability of motor are improved and the controllable speed range is widened. The algorithm herein will enhance the driving performance of EV. 

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