Table of Content

25 December 2016, Volume 27 Issue 24

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A Novel Method for Best Fit Design of Slide Guide Device in Hydraulic Press

Gao Mengdi, Liu Zhifeng, Huang Haihong, Li Xinyu

2016, 27(24):  3267-3272. 

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Based on the energy loss analyses of the sliding pair in slide guide device of hydraulic press, a mathematical model of overall efficiency loss was established. Based on the principles of minimum overall efficiency loss, the numerical calculation method of optimum match clearance in guide device was proposed. And the maximum allowable eccentric load on wedge clearance conditions was proposed based on the calculated optimum clearance. In order to ensure guide device between the pillars and slide wouldn't fail due to the excessive wear, the wear check method under extreme conditions was proposed. According to wear check method, the best guide length was calculated based on the principle of minimum overall efficiency loss. The case analyzed and verified the correctness of the method, which may provide theoretical and methodological references for the design of optimum match in guide device.

A Path Planning for Bionic Climbing Robot Based on GPL Model

Zhu Peihua, Wang Wei, Li Xuepeng, Wu Shilin

2016, 27(24):  3273-3278. 

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In order to investigate the path planning problems for bionic climbing robot based on GPL model, a path planning method was proposed. Firstly, the bionic climbing robot based on the GPL model was introduced. And then, the effects of the robot's path on climbing ability were studied by the kinematics and statics analyses of GPL model. The path planning was realized by minimizing the foot force. Finally, the results were validated by ADAMS simulation. The results show that the method may solve the path planning problems for bionic climbing robot based on GPL model, and explain the rationality of movement model for the gecko adopting swing crawling rather than rectilinear creeping.

A New Method for Improving Mechanical Properties of Hydrostatic Guide-way

Shi Enxiu;Guo Pengge;Wang Hailong

2016, 27(24):  3278-3282. 

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Carrying capacity and oil-film stiffness of hydrostatic guide-way are two important technical parameters. In order to meet the requirements of high precision CNC machine tool for hydrosta-tic guide-way, a new type hydrostatic guide-way with high liquid resistance was put forward based on local pressure loss theory. The simulations were done, which showed the effects of the position, width and depth of oil ring at resistive oil edges of the new hydrostatic guide-way on the oil chamber pressure. It is shown from the results that oil chamber pressures of hydrostatic guide-way may be enhanced significantly if the position, width and depth of the oil ring at resistive oil edges are appropriate. It is verified that the carrying capacity and oil-film stiffness of the new type hydrostatic guide-way with high liquid resistance are improved through the experiments.

Study on Electrode Wire Wear during WEDM Processes by PDC

Teng Kai, Sun Tao, Zhao Enlan, He Min

2016, 27(24):  3283-3287,3293. 

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The authors carried out the wire cutting machining experiments of PDC using WEDM, and observed the surface micro morphology of wire electrode with the SEM which might analyze the energy spectrum. The electrode wire wear mechanism of PDC ultra hard material was studied from the microscopic points of view, and the influences of the electrical parameters and the conditions of the washing liquid on the wire wear were discussed. It is found that the attached type high pressure liquid spraying mode, in the processing conditions of high voltage, small pulse width, high peak current, PDC cutting efficiency is as 19.35 mm2/min,the electrode wire wear is as 1.5~2μm (for 104mm2 cutting volume). The cutting efficiency is increased by 51.6% compared with the normal pressure liquid injection method, and the reduction of the wire wear by 15.2%.

Tool Failure Analysis and Cutting Parameter Optimization of Coated Carbides in Precipitation-hardening Stainless Steel High Feed Rate Milling

Yang Sen, Sun Jianfei, Li Haiyan, Han Liping

2016, 27(24):  3288-3293. 

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In dealing with the problems of low efficiency and server tool wear in high feed milling precipitation-hardening stainless steel(05Cr17Ni4Cu4Nb), a series of single factors and orthogonal experiments with coated carbides tool were carried out. An experiential function of tool life was deve-loped based on the experiments by using regression analysis. Tool failure mechanism was analyzed according to tool wear measurements and wear morphology, the cutting force, cutting temperature and tool stress contour were simulated with finite element analysis. Taking full account of cutting efficiency and tool life, the cutting parameters of coated carbides tool in precipitation-hardening stainless steel high feed rate milling were optimized using the tool life-efficiency surface response method by reference to finite element analysis results and the tool life experiential function. The optimal cutting parameters and tool life under this condition were obtained.

Multi-objective Optimization Model for Double-drive Feed System Based on NSGA_Ⅱ Algorithm

Huang Jun, Yuan Juntang, Wang Zhenhua

2016, 27(24):  3294-3300. 

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In order to satisfy lightweight and higher vibration performance requirements of the double drive feed system, a multi objective optimization design method was proposed based on the lightest mass, the best coupling mechanical properties and the higher first order natural frequency of the feed system. The optimization parameters were selected by the sensitivity method. A two order response surface model of the feed system is established by the orthogonal experimental design and the NSGA_Ⅱ algorithm is used as the solution algorithm. The calculation results show that the table mass is reduced by 0.3%, the maximum coupling stress is reduced by 5.9%, and first order natural frequency is increased by 9.32%. Finally, the correctness of double-drive feed system's optimization design method proposed herein was verified by the dynamic experiments.

Theoretical Analyses on Errors of Electronic Helical Guides Influenced by Multi-factors

Wu Zhenyu, Zhao Daxing, Zhong Ruiling

2016, 27(24):  3301-3306. 

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For improving the internal helical gear machining precision of electronic helical guides, this paper analysed the principles about how to cause the errors of spiral line of internal helical gears according to kinematics of the driving chains in a gear shaping machine. Firstly, a mathematical model of additional rotation of the tool was established according to the kinematic relationship of several axles, and an additional rotation coefficient was defined. Then, the mathematical relationships among the errors of spiral line and the errors of additional rotation and main motion were established respectively, and a coefficient Zebra was defined. At last, the mechanism causing the errors of spiral line was analyzed, and the influences of the length of rods and the position of crank and the gap of motion joints on the error of spiral line were concluded.

An Engine Fault Diagnosis Method Based on PCL and SVM

Zhang Yufei, Yao Ziyun, Tang Songlin, Zhu Lina, Zhang Jinjie

2016, 27(24):  3307-3311. 

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A new method was proposed based on PCA and SVM. First of all, the fault characteristics of vibration signals in time domain and frequency features were extracted by wavelet packet decomposition. Then the sensitive characteristics were selected with PCA to achieve dimensionality reduction and to decrease the complexity of data processing. Finally, SVM was used for training and testing of the feature subsets, and realizing the fault separation. Appling this method to typical faults of diesel engine such as misfire, cylinder collision and small head tile wear, the diagnosis accuracy rate is up to 98%, which confirmed the validity of this method.

Design of Probe Structure in CMM System Based on Virtual Light-pen

Zhang Rui, Liu Shugui, Zhang Xin, Wang Youfu

2016, 27(24):  3317-3325. 

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Based on the virtual light-pen, a new type of light-pen structure was built by analyses of the system model's feature. The light-pen adopted in the system had ten control points, and supposed the distance between the front plane where six control points laid and the back plane where other four ones did as DFB. The CMM's main axis could move with high accuracy and stability, then virtual light-pens with different values of DFB were built. The structure model for the virtual light-pen was given in detail. And several experimental results prove that the parameter DFB remarkably affects the stability of the whole system with that DFB's optimal value is as 80mm.

Knowledge Flow Based Engineering Technology Forecasting：a Case of Harmonic Reducer

Liu Huailan, Liao Ling, Zhou Yuan

2016, 27(24):  3317-3325. 

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In the perspective of knowledge flow, the paper constructed a quantitative engineering technology forecasting model by combining the clustering and main path method, based on the literatures and patent data. Taking harmonic reducer as an example, the literatures and patent data of 1980~2009 were applied to make a engineering technology forecasting by the model, and compared the results with the technologies during the 2010~2014. It turns out that the proposed framework is feasible and effective. At last, the engineering technology trends were forecasted for the next five years as follows: all countries of the world will devote themselves to the areas of improving the precision, backlash, transmission efficiency, bearing capacity, reliability and other performance-related technologies, miniaturization and light weight of transmission, as well as optimization of component parts.

A Simulated Annealing Algorithm for Irregular Guillotine Packing Problems

Han Wei, Zhang Zicheng

2016, 27(24):  3326-3331,3354. 

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A layered constructive algorithm was proposed for 2D irregular guillotine bin packing problems. Variant shape weighs were introduced to control the shapes of each evolved block, which indicated the similarity of the resulted shape to rectangle in each iteration. To get better utilization, smaller shape weights were used in early periods to get shapes with higher ratio of utilization, while larger weights were introduced in the last periods to let the shape be similar to rectangle. Based on simulated annealing, a parameter named temperature was introduced to control the change rate weights. The change of shape weights was smaller in early and later periods and larger in middle periods. Based on ESICUP standard test data, several weight adjustment strategies were examined, including fixed weight, linear change and temperature-controlled change, the results show that temperature-controlled change effectively improves the layout effiency and the material rate of layout.

Gear Fault Diagnosis Based on LCD and LME Demodulation Approach

Cui Weicheng, Xu Aiqiang, Li Wei, Meng Fanlei

2016, 27(24):  3332-3337. 

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In order to diagnose the gear fault accurately, according to the amplitude-modulated and frequency-modulated characteristics of the gear fault vibration signals a modle was proposed based on LCD and LME. Firstly，the original vibration signals were disposed by LCD．Secondly, the intrinsic mode components of LCD were envelope demodulated by LME. Finally, the gear faults were diagnosed by the instantaneous frequency spectrum. The analysis of the simulated data shows that the LME mode may get more accurate results of instantaneous amplitude and instantaneous frequency than that of Hilbert mode and empirical AM-FM decomposition mode. The analysis of gear fault data shows that the method based on LCD and LME may realize the fault diagnosis effectively.

Review and Analysis of State Key Laboratory Evaluation in Mechanical Engineering

Wang Guobiao, Song Jianli,

2016, 27(24):  3338-3345. 

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As one of the important links of the state key laboratory（SKL） management, evaluation played an important role in the guidance of the orientation and developing directions, and the construction and operation of the SKLs. It also provided a scientific basis for the strategic decision of relevant national management departments. The development history of the SKL evaluation system, organization and coordination, index system and procedure of the evaluation were reviewed herein. Situations and results of all previous evaluations of the SKL in the field of mechanical engineering were systematically summarized and analyzed.

Research on Piston Variable Clearance Sealing Structure Shape in Hydraulic Cylinders

Gao Yu, Fu Liandong, Zhan Congchang, Zhu Bing

2016, 27(24):  3345-3350. 

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The piston lip was the key point of the variable clearance sealing hydraulic cylinder. Therefore, the changes of clearance mainly reflected on the deformations of the piston lip. The stress function of cantilever beam structure in elastic mechanics was applied in this situation to analyze the deformations of the lip, and the deformation formula was deduced. Meanwhile ANSYS was used to simulate deformations of different lip structures in various working pressures. The characteristics and the influencing factors of variable clearance sealing piston lip deformations were found in the simulations. Compared the inner leakages of variable clearance sealing cylinder from tests with the leakages from calculations of theoretic deformation curves, results show the error is within the allowable ranges, and the simulations are validated to be correct.

Study on Synthesis Method and Solution-region of Approximate Straight-line Linkage with Two Inter-convertible Pivots

Yin Lairong, Huang Juan, Hu Lin, Liu Xin, Zhang Zhiyong

2016, 27(24):  3351-3354. 

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A synthesis method of four-bar approximate straight-line mechanism was presented based on inflection circle pole theorem, which might produce an infinite number of mechanisms. An analytic method was introduced to prove that the synthesized mechanism might make the fixed pivot of side link and its corresponding moving pivot inter-convertible. The two synthesized linkages with two inter-convertible pivots contained the same Ball point and straight-line direction. The other side link remained unchanged. The synthesizing formulas of crank-rock mechanism were derived and the solution domains were plotted. The given examples show that the method is simple and efficient to synthesize crank-rock mechanism, and the synthesized mechanisms have two inter-convertible pivots. This approximate straight-line linkage may provide more choices for practical engineering applications.

Fault Identification Method for Hydraulic Pumps Based on Multi-feature Fusion and Multiple Kernel Learning SVM

Liu Zhiqiang, Jiang Wanlu, Tan Wenzhen, Zhu Yong,

2016, 27(24):  3355-3361. 

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A hydraulic pump fault identification method was put forward based on multiple feature fusion and multiple kernel learning SVM. Firstly, the original signals were processed by the ensemble empirical mode decomposition. Then, the feature vectors of hydraulic pump faults were obtained by using the autoregressive model and the singular value decomposition. Through different types of features mapped by corresponding different kernel functions, the hydraulic pump working conditions and fault types might be finally identified by multiple kernel learning SVM. The experimental results show that the approach improves the accuracy of fault diagnosis significantly.

Bearing Fault Diagnosis Based on multi-EMD, cApEn and GG Clustering Algorithm

Zhang Shuqing1;Li Wei1;Zhang Liguo1，2;Hu Yongtao1;Qian Lei1;Jiang Wanlu1

2016, 27(24):  3362-3367. 

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A new method for rolling bearing fault diagnosis was introduced based on the multi-EMD, cApEn and GG clustering algorithm. The rolling bearing vibration signals were decomposed first by multi-EMD to obtain several intrinsic mode function (IMF) components and a tendency item. Then the first seven IMF components involving the primary feature informations were chosen by the criteria of correlation with the original signals, and the cApEn entropies of each IMF component were composed eigenvectors. Finally, the constructed eigenvectors were put into GG classifier to recognize different fault types. The four kinds of operating states of the machine were presented by means of clustering three-dimensional graph, which instates that the unproportional sampling may be solved by the multi-EMD method and the cluster aliasing of EMD can be further solved.

Dynamic Strain Transfer Laws of Surface Bonded FBGSs

Yi Renhui;Zhou Zude;Liu Mingyao;Ji Dongliang

2016, 27(24):  3362-3367. 

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Firstly, as structure under sinusoidal load for example, a surface bonded FBG dynamic strain transfer model was established through theoretical analysis, and the influencing parameters were determined. Then, the influences of dynamic strain transfer parameters were analysed by using the finite element simulation method. Finally, the results of theory and simulation were verified by experimental analyses. The results of theory and experiments show that the vibration frequency, the length of glue, the thickness of glue and middle layer thickness of glue have major impacts on FBGS dynamic strain transfer rate. The width of glue has minor effects on the transfer rate. When the vibration frequency is far less than the structure natural frequency, the dynamic strain transfer rate remains the same through different frequencies and the experimental value is as 92%. Before the vibration frequency achieves the natural frequency, the transfer rate increases very slowly with the increases of vibration frequencies. When the length of glue is more than 2 times of FBG length, the transfer rate will be obviously better than the rate of shorter, the experimental value is as 92%.

Analyses of AA5083 Tube Warm Bulging Processes under Non-uniform Pressures of Granule Medium

Chen Xiaohua, Zhao Changcai, Dong Guojiang, Yang Zhuoyun, Cao Miaoyan

2016, 27(24):  3368-3375. 

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The influences of friction at the tube/granule interface on the thickness distribution of free bulging region and the bulging limitation were discussed based on uniaxial tensile tests at elevated temperature for AA5083 tube, the pressure-transfer tests and the external friction coefficient tests for granule medium after the force conditions of free bulging region were analyzed under non-uniform internal pressures. The theoretical analyses and tests show that friction at the tube/granule interface is beneficial for preventing the thickness decrease and improving bulging limitation.

Study on Welded Joint Microstructure and Mechanics Properties of High Nitrogen Steels for Laser-arc Hybrid Welding

Wang Lifeng, , Liu Fengde, Liu Shuangyu, Zhang Hong, Liu Weina, Tian Miaolei,

2016, 27(24):  3382-3388. 

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Heat input had a significant effect on microstructure and mechanics properties of welded joint. The joint microstructure, weld nitrogen content, tensile and impacted properties and the micro hardness of joint were studied by laser-arc hybrid welding while the arc and laser energy were different. The results show that the weld microstructure is made up of austenite and a small amount of δ ferrite. The delta ferrite deposited from weld is increased by the increasing heat input. After the current reaches 200A, the dissolution of nitrogen in liquid metal molten pool is close to saturation; and even if the welding current is added, the weld nitrogen content still tends to be constant. When the laser power is increased to 2.0kW, keyhole remains at a stable state in the welding processes, and weld nitrogen content is approximate to constant. Tensile fracture location is in the weld zone. When the welding current is as 200A, the highest average tensile strength reaches 967.58MPa. When laser power is as 1.6kW, the average tensile strength may reach 962.88MPa. The weld impact energy shows a first decrease and then increase with increasing laser power, but the variation tendency is opposite along with increasing current. The variation tendency of impact energy of the weld fusion line is the same as that of the weld zone and changes with the welding parameters. The highest average impact energy of the weld and the weld fusion line are as 47.60J and 62.85J separately. All tensile and impacted fracture mode is of ductile fracture. The micro hardness of weld area is lowest so that the fracture area of tensile test is located at the weld zone.

Research on Variable Parameter Modeling Method for Sprue Die Casting Mould

Dong Yude, Zhu Guanqun, Yang Guanghui, Ling Yueshu, Zhang Changhao

2016, 27(24):  3389-3395. 

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Aiming at the problems which were combined with the cumbersome of repeated generation of geometric characteristics, the complexity of operation and the discrete of design parameters during in the modeling of die casting, this paper proposed a modeling method with variable parameters as the dominant. Based on sprue's feature requirements and practical technology, and through the analyses of sprue's variable parameter characteristics the impacts of sprue's feature on the properties of metal solution were studied. Making UG8.0 as the research platform and combined with CAD technology, the parameterized, systematic and standardized design of die casting mould was realized to develop a variable parameters design system of die casting mold. The centralized processing of the parameters was effectively realized by this system, avoiding the repetitive work of designers, shorting thedevelopment cycle and improving the design accuracy.

Design Optimization of Key Structures in Frontal Crash Based on ESLMG

Chen Tao, Dai Jianglu, Chen Zikai, Li Qiqi, Li Zhuo

2016, 27(24):  3396-3401,3407. 

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In inheritance development processes of existing vehicle models, it was difficult to optimize and redesign the structures efficiently and accurately because of the limitations of structure sizes and general arrangements. A procedure which contained with G1-G2 design regulation, crash load path and an ESLMG was proposed to overcome the disadvantages to improve the performance of key structures in frontal crash. First, the equivalent double step target curve was defined, which was satisfied for the requirements of passenger injury according to G1-G2 regulation and crash loads database was built by collecting and analyzing competing models. Then, frontal crash key structures of original model were determined as optimization objects and the thicknesses of them were optimized using ESLMG after optimizing their shapes. Finally, the optimized structures were input into full vehicle model to verify if its acceleration curve had achieved the optimization target or not. The validity of this procedure was proved with the calculation results of numerical examples.

Applications of Weighted Relative Sensitivity Analyses in Lightweighting of Cab Structures

2016, 27(24):  3402-3407. 

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A credible structure FE model of a cab was built and the model was verified by tests. The sensitivity of the cab components was calculated directly and the weight coefficients of constraint responses were determined through the analytic hierarchy process with consideration to variable margins of the constraint responses. Then a concept of weighted relative sensitivity was put forward and identified the design variables and its optimization directions according to the concept. The thicknesses of cab components were optimized on the promise of no reduction on the main static and dynamic performance of the cab. The objective is realized with the total mass of the cab is reduced by 8.7%, while the main static and dynamic performances are somewhat raised and the overall low-frequency noise levels rise lightly.