金刚石与磨料磨具工程

Simulation study on high-speed grinding with single CBN grain

ZHANG Jingqiang, WANG Qi, GUO Jianye, WANG Yunjiang

2017, 37(4): 1-5. doi: 10.13394/j.cnki.jgszz.2017.4.0001

Abstract(327)

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Abstract:
In order to investigate the micromechanism of high/ultrahigh speed grinding process with single CBN grain, the mechanism of CBN abrasive grinding high-speed steel SHK-9under different process parameters was studied by using Lagrangian/Euler fluid-solid coupling method with random shaped CBN abrasive as the analysis model.Result shows that the tangential grinding force of CBN abrasive grains sized 124 to 150 μm is maximized at cutting depth of 20 μm or 30 μm, cutting speed of 120m/s, but it is minimized at cutting depth of 40 μm.With reduced grain size of CBN abrasive, the grinding force decreases obviously, while abrasive grains can form narrower scratches on the surface of the workpiece.Therefore, the appropriate grinding depth combined with proper grain size can improve the grinding surface quality.

Influence of grit size and arranging distance on workpiece integrity when grinding CFRP with brazed diamond milling tool

YAN Chaoren, CHEN Yan, ZHENG Kai, LIANG Yuhong

2017, 37(4): 6-10,21. doi: 10.13394/j.cnki.jgszz.2017.4.0002

Abstract(476)

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Abstract:
The low interlaminar adhension and anisotropy of carbon fiber reinforced plastics (CFRP) could result in serious machining defects such as delamination, burrs, tearing, and other problems such as short tool life.On the idea of "grinding instead of cutting", delamination can be improved by using brazed diamond cutting tool whose grits are orderly arranged.In order to manufacture appropriate brazed diamond tool which is suitable for CFRP edge grinding, five kinds of tools with different grit size and varied arranging distance are prepared and the influences of tool structure changes on grinding forces and surface integrity when edging machining CFRP are investigated comparatively.The results show that under the same grain arrangement and the machining parameters, increasing grit size has few influence on grinding force but leads to a worse surface quality.In addition, decreasing grit arranging distance contributes to the improvement of machining quality and the grinding force increases firstly then decreases under the conditions of commonly grain size and machining parameters.

Diamond grits are ordely arranged through dispensing method thus improving bit performance

ZHANG Dingyuan

2017, 37(4): 11-14. doi: 10.13394/j.cnki.jgszz.2017.4.0003

Abstract(366)

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Abstract:
To orderly arrange diamond grits in impregnated diamond bits, dispensing is applied in preliminary experiments on arranging diamond grits.Matlab2016A image analysis tech provides a quantitative evaluation scheme of grit positioning accuracy.Then a single layer electroplated diamond bit with orderly arranged grits is prepared to compare its performance with that of common bits in actual drilling.Resultsshow that dispensing helps to orderly arrange diamond grits, whose deviation ratio over the design scheme is less than 10%, and that grit-arranged bit performs 30%increase in efficience and 85%in bit life than common bits.In conclusion, dispensing method is reliable to orderly arrange diamond grits in a bit, who has significant advantage over common bits.

Discrete element simulation study on the friction and wear between matrix of diamond saw blade and marble

ZHANG Cong, TAN Yuanqiang, JIANG Shengqiang, GUO Hua

2017, 37(4): 15-21. doi: 10.13394/j.cnki.jgszz.2017.4.0004

Abstract(250)

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Abstract:
A discrete element model of friction and wear between diamond saw blade matrix and marble is established.The parameters of the matrix model are verified by indentation test, and the dynamic variation law of abrasion loss is simulated under different loads in the course of wear between the matrix and the marble.The results show that the abrasion loss of matrix increases as loads increase, then gradually stabilizes, and that the wear rate increases first and then decreases.The simulation of discrete element is in better agreement with the experimental results, which proves that the discrete element simulation method is feasible for simulating wear.

Diamond bit used in drilling reinforced concrete structure

YE Hongyu, YANG Zhan, TAN Songcheng, XIE Tao, ZOU Shengshu

2017, 37(4): 22-26. doi: 10.13394/j.cnki.jgszz.2017.4.0005

Abstract(337)

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Abstract:
Due to reinforce concrete's high strength grade and embedded rebar, it is difficult to obtain an efficient drilling result during the repair and renovation constructions.Besides diamond bit cutters are usually broken during the drilling process, thus leading to diamond bit's short service life.To solve those problems, regulating bit matrix property, optimizing diamond bit structure, as well as adding grinding types are employed within this study.Soft-medium hardness matrix and cubic boron nitride which improves the cutting performance of abrasive particles on the diamond bit workface are used to increased the drilling rate.Optimized bit structures, including diagonal water gap and asymmetric cutters are employed for ensuring a steady drilling process.It can avoid the suddenly full-face encounter between bit cutters and the rebar, which may produce huge transient impact load and cause cutters breaking.Test results indicate that, the average drilling rate and total service life of ϕ75 mm diamond bit are 1.12 m/h and 28 m respectively under the optimized drilling parameters (i.e., the drilling pressure of 6.5 MPa, linear velocity of 2.1m/s and coolant flow of 25 L/min) and there is no cutters broken during the drilling test.Consequently, the diamond bit design methods in this study are proved to be correct, and the diamond bits manufactured following those methods and technologies can satisfy the requirements of construction.

Study on key preparation technology of diamond core drill bit for sapphire

XU Liang, LIU Yibo, XU Qiang

2017, 37(4): 27-30,37. doi: 10.13394/j.cnki.jgszz.2017.4.0006

Abstract(367)

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Abstract:
Diamond core drill bit for sapphire is different from the conventional engineering drill bit, it requires good sharpness, long life, small radial jumping, good surface quality of sapphire bar, so the higher requirement is proposed for the preparation and testing of drill bit.This paper focuses on the important testing indicators of the segment, the drill pipe, the matrix design and the finished drill bit, and elaborates the key details on the preparation of segment, the welding of bit and the subsequent processing.We prepared a 4-inch (internal diameter ϕ103 mm) diamond drill bit for drilling sapphire crystal, the efficiency is increased by 12% than the Taiwanese company's drill bit with the same specifications, the life is about 95% of Taiwanese company's drill bit, and the defective rate of sapphire bar is less than 0.5%, which satisfies the requirement of customers.

Preparation technology and properties of Ni-diamond composite coating

XU Yang, SUN Yuli, TANG Suyang, ZUO Dunwen, YAN Xiaotong

2017, 37(4): 31-37. doi: 10.13394/j.cnki.jgszz.2017.4.0007

Abstract(353)

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Abstract:
In order to study the composite electrodeposition process of diamond consolidated abrasive grinding discs, the preparation technology and properties of Ni-diamond composite coating are studied in this paper.The influences of diamond concentration, current density, temperature and deposition time on the quality of composite coating are studied by scanning electron microscopy, microhardness tester and friction and wear tester.A series of preferred Ni-diamond composite electrodeposition process parameters are obtained:diamond concentration 40g/L, current density 3A/dm², temperature 50℃, deposition time 90 min.The surface of Ni-diamond composite coating is flat, the diamond powder has a uniform deposition, and the wear resistance of the composite coating is obviously improved compared with the traditional nickel layer.

Study on mechanical properties of diamond wire saw under ultrasonic tension

ZHANG Liaoyuan, SU Junjin, LIU Xiaodong, GUAN Huiyu, LIU Wei

2017, 37(4): 38-43. doi: 10.13394/j.cnki.jgszz.2017.4.0008

Abstract(415)

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Abstract:
Mechanical properties of diamond wire saw under the action of ultrasonic vibration were studied.The vibration system and connection device were self-designed, and the uniaxial tensile tests were carried out for different diameters of diamond wire saw by use of the ultrasonic vibration system in an attempt to find the changes in mechanical properties of diamond wire saw under different frequencies and different amplitudes.Diamond wire saw crack growth mechanism and softening mechanism under the condition of ultrasonic tension were studied.Wire saw fracture morphology were analyzed using electron metallographic microscope with or without ultrasonic vibration.Resultsshowed that the alternating stresses of wire saw were generated under the action of ultrasonic vibration, and that there appeared micro-cracks, which rapidly expanded and teared.High frequency vibration produced localized high temperature and accelerated diffusion process, which eventually developed into a macro defect.When the ultrasonic stretching frequency was loaded to 20 kHz, the crack growth rate could reach 10^-9~10^-8 mm/cycle.

Diamond particle content of Cu-diamond composite coating

GAO Long, LIU Jituo, YAN Zepeng, ZHANG Yingjiu

2017, 37(4): 44-47. doi: 10.13394/j.cnki.jgszz.2017.4.0009

Abstract(372)

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Abstract:
Diamond particle content is the key to the performance of diamond composite coating.Selecting different volume fractions of alkyl bromide as the additives, we studied the effect of additive volume fraction on the composite amount of diamond particles and selected the optimum fraction of the addictive.We also studied the influences of current density and diamond particle mass concentration on the amount of diamond particles.The results showed that the composite amount of diamond particles increased first and then decreased with the increase of additive volume fraction with the optimum additive fraction of 0.8mL/L, and that the composite amount of diamond particles increased continuously when controlling the mass concetration of diamond particles in the range of 2.5~40g/L.Current density had an obvious effect on the compound amount of diamond particles, which increasing rapidly and then decreasing slowly with the increase of current density.

Application of spray welding technology in steel body PDC bit's surface hardening

XU Jianfei, ZOU Deyong

2017, 37(4): 48-52. doi: 10.13394/j.cnki.jgszz.2017.4.0010

Abstract(349)

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Abstract:
In order to solve the problems of steel body PDC bit, including the lower hardness, poor wear resistance, poor drilling fluid erosion ability of the bit's body, the preferred mothod for steel body PDC bit surface hardening and preferred material for surface cladding were obtained by means of theoretical analysis and laboratory experiment, and established the flame spray welding technology using for cladding hardening on the bit surface.The results of field test show that the steel surface hardening layer with the cladding materials which are composed of Ni60 and WC of mass fraction 25%-30% has good quality, its abrasion resistance and erosion resistance can satisfy drilling requirements.

Application of fine powder in metal bonded grinding wheels

LI Guowei, HAN Xin, WANG Dongdong, NIU Junkai

2017, 37(4): 53-55,61. doi: 10.13394/j.cnki.jgszz.2017.4.0011

Abstract(334)

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Abstract:
In order to explore the effect of fine powder on the performance of metal bonded grinding wheel, the fine powder and ordinary powder with different ratios were mixed homogeneously and were made into matrix body-blocks by hot pressure sintering method.Moreover, superabrasive were added to the above mixed powder and were made into metal bonded superabrasives.By employing the sclerometer, the bending test machine, the scanning electron microscopy, the cutting machine and so on, we tested the hardness of metal bond matrix, the bending strength, the fracture morphology and the cutting performance respectively.The results show that fine powder is favorable to raise the bending strength of metal bond matix and the maximum increase is 20%, and that it also increases the wear resistance of superabrasives, with radius abrasion reduced by 25.7% at the same conditions.

Application of acoustic emission in the breaking signal recognition of grinding wheel rotation test

WANG Yongfeng, ZHENG Peng, LIU Hongjun, CHEN Xiaoqiang, WANG Jiangtao

2017, 37(4): 56-61. doi: 10.13394/j.cnki.jgszz.2017.4.0012

Abstract(328)

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Abstract:
Acoustic emission (AE) technology, a new method to detect the breaking signal of grinding wheel rotation test is introduced.The time and frequency domain of the signals are studied by collecting the AE signals of background, idling, no-load, loading.Comparison the characteristic AE signals of grinding wheel after crushing and crushing before, we find that the characteristic voltage value of time domain signal increases by 2.5times, the peak value of the energy spectrum increases by 4times, the RMS value increases by 1.17 times and a high frequency voltage signal is obtained by means of fast Flourier transform (FFT) of the frequency domain.The results show that the acoustic emission technology is more suitable for the field of grinding wheel breaking test, which is superior to the commonly used vibration method, volume method and photoelectric method.

Experimental study on surface topography and tensile ultimate load of diamond wire saw during life cycle in machining sapphire

NI Yongming, LI Zhen, LI Guohe

2017, 37(4): 62-66. doi: 10.13394/j.cnki.jgszz.2017.4.0013

Abstract(340)

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Abstract:
In order to optimize the process parameters for slicing sapphire wafer through multi-wire sawing with diamond wire saw, the diamond wire samples of the different stages are obtained by machining tests.The surface morphology of these samples are observed through scanning electron microscopy, while the tensile ultimate load of the samples are tested by tensile testing machine and the fracture morphology is analyzed.The experimental results show that the diamond particles in the life cycle experience the process of cladding worn, baring, cracking and falling off.The diamond particle cracking is the main cause of falling.During life cycle, the tensile limit of the wire does not decrease with wire wear and falling of diamond particles.Furthermore, the fracture image of fracture test samples are divided into three zones:the crack propagation zone, transient breaking zone and the plating zone.The separating can be observed between the plating zone and the steel wire.On the basis of the analysis results, the optimization method of process parameter is given.

Application progress on the vacuum plating of nanodiamond and related materials

ZHANG Yan, ZANG Jianbing, XU Hanqing, HAN Chan, CHEN Libei, WANG Yanhui

2017, 37(4): 67-72. doi: 10.13394/j.cnki.jgszz.2017.4.0014

Abstract(376)

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Abstract:
It is over reviewed that nano diamond, nano silicon carbide, silicon nitride whisker and carbon nanotubes were surface modified with titanium or manganese metal power by using vacuum plating method and applied in new energy.Especially, the titanium coated nanodiamond, nano silicon carbide and silicon nitride whiskers were used as platinum catalyst support material in the application of direct methanol fuel cell, as well as the carbon nanotubes coated with manganese were used in supercapacitors.

Research and development of cutting or grinding specific energy database system for key components of typical machine tools

YIN Hui, DENG Chaohui, ZHANG Hua, FU Yahui, YAN Can

2017, 37(4): 73-78,85. doi: 10.13394/j.cnki.jgszz.2017.4.0015

Abstract(343)

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Abstract:
Based on the existing energy consumption research, and according to the empirical relation between the material removal power and the no-load power and machining power of the machine tools, an empirical calculation model for cutting or grinding specific energy is established.The feasibility and correctness of the empirical calculation model are verified by the theoretical model of cutting or grinding specific energy based on cutting or grinding force and its experiment.A cutting or grinding specific energy database system for key components of typical machine tools through measurement and calculation values of cutting or grinding specific energy based on empirical calculation model is designed and researched, which includes the basic architecture, basic database, analysis module of cutting or grinding specific energy and makes it systematized and standardized.Users can quickly implement the functions of adding, deleting, modifying and searching the required data at the software operating interface.

Progress and application of non-woven polishing materials

ZHAO Shuo, ZOU Wenjun, PENG Jin, SONG Xudong

2017, 37(4): 79-85. doi: 10.13394/j.cnki.jgszz.2017.4.0016

Abstract(365)

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Abstract:
The research status and preparation methods of non-woven polishing materials are introduced.The advantages and disadvantages of various preparation methods are analyzed.Then, the effects of fiber type, binder type, abrasive type and processing parameters on material properties and processing quality are described.Finally, it points out the problems in the current research of nonwoven polishing materials and puts forward the development direction in the future.

Improvement of sintering press performance using newly electro-hydraulic control system of servo pump

HAN Ruifeng, YANG Xiaopeng, ZHAO Zhipu, LI Haishen, HU Bingtao

2017, 37(4): 86-89. doi: 10.13394/j.cnki.jgszz.2017.4.0017

Abstract(250)

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Abstract:
According to detailed analyses of principles of the servo pump system and electric control and PLC (programmable logic controller) servo motor control, the existing sintering press is improved by using the servo pump system to replace the control system of the electro-hydraulic proportional value.After the improvements which are widely accepted by customer, it shows that the pressure control precision of servo hydraulic system in sintering press is ±0.1 MPa, the noise is reduced from 65 dB to 45 dB, and the tank temperature is lowered to 12.5℃than without improvement.It is also found that the hydraulic components life are extended, equipment maintenance cost is lowered and the stability of sintering press is improved.

2017 Vol. 37, No. 4

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