金刚石与磨料磨具工程

Kinematic model of normal-trach grinding for spherical parts

LIU Wei, DENG Chaohui, WAN Linlin

2016, 36(4): 1-5,23. doi: 10.13394/j.cnki.jgszz.2016.4.0001

Abstract(284)

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Abstract:
According to current requirements of efficient and precision machining for spherical parts which are made with difficult-to-machine materials and used in aerospace,high-speed rail and other industrial fields,the machining principle and method for spherical parts are introduced briefly.Three traditional spherical grinding methods are analyzed for their advantages and disadvantages.Then a new spherical grinding method is proposed based on the principle of grinding wheel normal tracking to improve the efficient precision machining for spherical parts and take full advantage of multi-axis grinding machine.It is divided to cylindrical-like grinding and plane-like point grinding according to motion decomposition.In view of geometry contact length between grinding wheel and workpiece and grinding wheel cutting path,the geometry and kinematic model is analyzed,so as to provide guidance for further study.

Chemical-mechanical grinding of K9 optical glass using atomized liquid

DAI Hengzhen, YOU Yanhong, DAI Zhihong, JIN Zhuji

2016, 36(4): 6-12. doi: 10.13394/j.cnki.jgszz.2016.4.0002

Abstract(320)

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Abstract:
According to the physical and chemical properties of K9 optical glass,based on the dry chemical-mechanical grinding(CMG),NaHCO₃ liquid is prepared using ultrasonic atomization to grind K9 optical glass.The optimal CeO₂ abrasives under the atomized environment are developed after grinding tests.In addition,the influence of workpiece speed,abrasive speed and pH value of atomized liquid on the surface roughness and material removal rate of K9 optical glass are compared using orthogonal tests.Resultsshow that liquid pH affects the surface roughness of K9 optical glass most,followed by abrasive speed and workpiece speed.The strongest impact on the material removal rate of K9 optical glass comes from liquid pH,while the workpiece speed ranks second and abrasive speed last.The wet CMG with appropriate amount of atomized liquid could improve the processing quality and speed without dust pollution from dry CMG,which is suitable for K9 optical glass precision finishing.

Research on sub-surface crack depth in surface grinding for optical glass K9 based on grinding speed

CHEN Jiang, ZHANG Feihu

2016, 36(4): 13-17. doi: 10.13394/j.cnki.jgszz.2016.4.0003

Abstract(318)

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Abstract:
According to the collaborative analysis of grinding parameters,the surface grinding experiment for optical glass is carried out based on the single factor of grinding speed while the abrasive paths are kept consistent.The damage depth of sub-surface crack layer is detected by specimen angle polishing and SEM,which shows that damage depth of the sub-surface crack layer decreases with the increase of the grinding speed.When the grinding speed increases from 500 r/min to 2500 r/min,the average value of the maximum subsurface crack layer depth drops to about 25 μm.The results of grinding experiment for optical glass show that grinding speed is an important factor to the damage depth of the sub-surface in grinding process,which has important influence on the formation of sub-surface crack.

Multi-objective genetic optimization on matrix structure of ultra-high speed grinding wheel

WANG Xuezhi, SUN Xue, SHI Ying, ZHAI Yanchun, YU Tianbiao, WANG Wanshan

2016, 36(4): 18-23. doi: 10.13394/j.cnki.jgszz.2016.4.0004

Abstract(292)

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Abstract:
In order to control expanding deformation in ultra-high speed grinding and reduce the rotation stress,the matrix of grinding wheel is optimized.Based on the analysis of cross section of the matrix,the parameterized model of grinding wheel matrix is established by straight line and spline curve and thus the multi-objective genetic optimization of grinding wheel matrix is realized.The results show that under grinding speed of 250 m/s,expansion deformation and equivalent stress of the optimized grinding wheel matrix respectively decrease to 30.827 μm and 94.97 MPa.Comparing with the original grinding wheel they are respectively reduced by 25.67% and 6.44%.

Research on surface topography reconstruction and distribution of undeformed chip thickness of monolayer brazed CBN wheels

DING Chen, DING Wenfeng, DAI Chenwei, XU Jiuhua

2016, 36(4): 24-28. doi: 10.13394/j.cnki.jgszz.2016.4.0005

Abstract(292)

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Abstract:
In order to better understand the grinding mechanism and predict the grinding results for the further work,the actual distribution characteristics of undeformed chip thickness of monolayer brazed CBN wheel are investigated based on surface topography reconstruction.The results show that,grain height does not distribute normally,which requires Johnson transformation to reconstruct the surface topography of the whole CBN wheel.Moreover,grinding parameters and wheel wear have a great impact on the distribution of the undeformed chip thickness.

Effect of Cu-Ce alloy on property of Fe-based metal bond

CHEN Jinshen, ZHI Hongmei, FAN Xueqin, ZHAO Zhiwei

2016, 36(4): 29-33. doi: 10.13394/j.cnki.jgszz.2016.4.0006

Abstract(303)

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Abstract:
To further enhance the property of Fe-based metal bond,Cu-Ce alloy,Fe,Sn and Cu are used to prepare different types of metal bond by hot pressing,thus studying the effect of Cu-Ce alloy on property of the bond.The results show that density and impact strength of the bond increase as the content of Cu-Ce alloy increases,while the bending strength and Rockwell hardness increase and then decrease.It is concluded that HRB reaches its top value when the mass fraction of Cu-Ce alloy is 8%,and that the bending strength increases to its maximum,namely 518.12 MPa when Cu-Ce mass fraction is 6%.It is also found that adding Cu-Sn alloy reduces mechanical property of Fe-based metal bond.

CFD simulation of diamond bit's bottomhole flow field

PAN Xiaoyi, QIN Jianxin, XIE Delong, LIN Feng, LUO Wenlai, XIAO Leyin, CHEN Chao, PENG Shaobo, CHEN Jiarong

2016, 36(4): 34-38. doi: 10.13394/j.cnki.jgszz.2016.4.0007

Abstract(358)

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Abstract:
Based on the theory of computational fluid dynamics(CFD),the bottomhole flow field of the ϕ75/ϕ49 mm diamond bits is simulated using the RNG k-ε model.Meanwhile,the effects of bottomhole pressure,flow velocity,shear strain and the eddy of water gap on the crown surface are analyzed.The diamond arrangement is optimized in the insufficient cooling location and serious erosion area.The simulation results show that the pressure distribution gradient on the ϕ75/ϕ49 mm diamond bit's crown surface declines from the inner edge to the outside edge.Because of the eddies in the water gap,the medium flow nephogram and the shear force vector nephogram show a distorted convex form.

Effect of carbon dioxide on growth of diamond films

CHEN Yi, WANG Jianhua, LIU Fan, WENG Jun, WU Xiao

2016, 36(4): 39-43. doi: 10.13394/j.cnki.jgszz.2016.4.0008

Abstract(369)

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Abstract:
Diamond films are deposited on Si substrate with H₂/CH₄/CO₂ as source using microwave plasma chemical vapor deposition method.The effect of microwave power and CO₂ on the growth of diamond films is analyzed.The quality,surface morphology and grain orientation of diamond film are systematically characterized by Raman spectroscopy,scanning electron microscopy(SEM)and X-ray diffraction(XRD).The results show that an appropriate increase of microwave power could promote the diamond grain growth and increase the(100)orientation.It's also shown that adding an appropriate amount of CO₂ could improve the quality and growth rate of diamond films,and maintain surface morphology.However,with the increase of CO₂ content,the diamond surface morphology changes greatly and the quality and growth rate of diamond films increases firstly and then decreases.

Research on grinding temperature of particle-reinforced titanium matrix composites in creep-feed deep grinding

SHEN Long, DING Wenfeng, LI Zheng, XIAO Hong, WANG Xunyang

2016, 36(4): 44-48. doi: 10.13394/j.cnki.jgszz.2016.4.0009

Abstract(234)

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Abstract:
Particle-reinforced titanium matrix composites(PTMCs)have high specific strength,high hardness and high temperature durability,which shows great application potentials as an important structural material in aviation and aerospace industries.Creep-feed deep grinding experiments are carried out on particle-reinforced titanium matrix composite to study the grinding performance in terms of grinding temperature and surface.The heat distribution proportion in the workpiece is discussed using finite element method.The results show that grinding burn is likely to occur when the depth of cutting reaches 0.6 mm,and that grinding induced crack could be presented by a severe grinding burn.Moreover,the surface topography becomes worse with increasing depth of cutting.

Optimizing diamond drill bit formula using uniform design

XU Qiang, LIU Yibo, XU Liang, YANG Zhiwei

2016, 36(4): 49-53. doi: 10.13394/j.cnki.jgszz.2016.4.0010

Abstract(358)

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Abstract:
The diamond bit matrix formulas are designed by uniform design with constraints to study the effects of diamond bit matrix formula on sharpness and life.Nonlinear regression analysis of experimental data is performed in SPSS to obtain the relationship between the performance and the component.At the same time,the sequence of influence factors and the significance are revealed using t test.Finally,the optimized formula is obtained through excel programming.The results show that the established Scheffe regression equation has a good fit to the experimental results.The content of Co element has a significant influence on the sharpness and life of diamond bit.The uniform design of the formula can reach desired result with less tests.

Effect of power output on morphology of electroplating diamond wire

GAO Wei, CENG Jun, LI Hongyu, WANG Dongxue

2016, 36(4): 54-57. doi: 10.13394/j.cnki.jgszz.2016.4.0011

Abstract(367)

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Abstract:
The effect of power output form on the morphology of diamond wire is studied.In the experiment,ϕ0.18 mm copper plating high carbon steel wire is used as the baseline,while the size of diamond particle is 30-40 μm,surface of which has been chemically plated with nickel phosphorus alloy at weight increase of 30%.The output forms of the power are DC output,single pulse output and double pulse output.The aggregation of diamond particles on the wire is reduced gradually when the duty ratio reduces from 0.8 to 0.2,while the optimum duty ratio is 0.6.The aggregation phenomenon of diamond particles is gradually reduced when the opening ratio of the positive pulse of double pulse output reduces from 8 to 2,while the optimum opening ratio is 6and diamond particles are well distributed.Theoretical analysis shows that the negative pulse of the double pulse output has desorption effect on the agglomeration diamond,so it can effectively restrain the agglomeration phenomenon.At the same time,too strong desorption effect will reduce the amount of sand.

Effect of sintering temperature on microstructure and property of CuZnSn13 powder sintered body

MIAO Jinqi, SUN Weiyun, HUO Fangfang, ZHAI Deming, LIU Shengxin

2016, 36(4): 58-62. doi: 10.13394/j.cnki.jgszz.2016.4.0012

Abstract(247)

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Abstract:
The copper-zinc-tin alloys with 13% tin(mass fraction)are produced using atomized prealloyed powders of copper-zinc-tin and mechanically mixed elemental powders of copper,zinc and tin at different hot pressing temperatures,respectively.The microstructures of sintered bodies are analyzed using scanning electron microscopy and X-ray diffraction.The Rockwell hardness and bending strength are tested with hardness tester and universal testing machine.The relative density is tested in drainage method.The results show that the two sintered bodies have similar phase compositions under the same sintering condition.However,compared with that sintered using mixed elemental powder,the one sintered using pre-alloyed powder has more solid solution phases,a small amount of hard and brittle phases of Cu₆Sn₅ and Cu₆₁Zn₃₉ and much more homogeneous and finer microstructures.The density,Rock well hardness and bending strength of the two sintered bodies have a general uptrend with the increasing of sintering temperature,whereas the changes of the above properties of pre-alloyed powder sintered bodies are not obvious.

Study on shape of noise-reduction holes on diamond circular saw blade based on FEM/BEM

YU Jiawei, ZHANG Jinsheng, WANG Zhi, YE Luhao, GE Jianyu, GAO Lijun

2016, 36(4): 63-67,74. doi: 10.13394/j.cnki.jgszz.2016.4.0013

Abstract(306)

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Abstract:
To study the parameters of noise-reduction holes,ϕ960 mm diamond saw blades are selected as examples.Finite element method(FEM)and boundary element method(BEM)are used to analyze the vibration condition of the blades with different noise-reduction holes.The vibration response of FEM are used as the boundary condition of BEM model to calculate the characteristics of sound field and compare the results of saw blades with different noise-reduction holes.The results show that blades with circular holes perform better at low frequency,that those with triangular holes perform better in middle frequency and that those with pentagonal holes perform better at high frequency.It is concluded that blades with pentagonal holes are better considering the entire frequency segment,whose reasonable rotation speed should be 346-378 r/min and 430-456 r/min.

Application status and development trend of nanodiamond in the field of functional materials

LI Min, LI Zhengxin, HUI Ming, HUANG Jihong

2016, 36(4): 68-74. doi: 10.13394/j.cnki.jgszz.2016.4.0014

Abstract(425)

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Abstract:
The characteristics,preparation methods and applications of nanodiamond are reviewed in this paper,focusing on the application in biomedical field.The prospect of nanodiamond is expected.

Influence of fixing agent on quality of brazed diamond tools

YANG Hedan, LIU Yibo

2016, 36(4): 75-78. doi: 10.13394/j.cnki.jgszz.2016.4.0015

Abstract(253)

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Abstract:
To study the influence of fixing agent on quality of brazed diamond tools,three agents namely SZ,NH and GY are made into testing samples.Their surfaces are observed and actual cutting & drilling experiments are implemented.Resultsshow that GY agent leaves least residual carbide with best appearance,while NH agent ranks second and SZ agent performs worst.As with the blades and bits made with these three agents,those made with GY agent have longest work life and fastest speed,followed by those made with NH agent and those made with SZ agent lists in the bottom.

Experimental study on process of grinding Al₂O₃ ceramic with resin bond diamond grinding wheel

LIU Jie, CAO Jianfeng, SUN Zhengbin, LIU Meng

2016, 36(4): 79-83. doi: 10.13394/j.cnki.jgszz.2016.4.0016

Abstract(364)

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Abstract:
To enhance the grinding performance on Al₂O₃ ceramics,resin bond diamond grinding wheels are prepared to conduct grinding tests,the grain sizes of which are 125 to 150 μm and 38 to 45 μm respectively.Surface roughness,material removal mode and material removal proportion are studied as the grinding parameters change and the microstructure of alumina ceramics after grinding is observed and analyzed.The results show that the surface roughness of alumina ceramics can reach R_a 0.418 μm and the material removal proportion can reach 95%.When grain size 38 to 45 μm,with cutting depth no more than 2 μm and workpiece speed 0.15 m/min,the material removal mechanism changes from plastic removal to brittle removal.In conclusion,optimized grinding parameters consist of two parts,namely coarse grinding(grain size 125 to 150 μm,cutting depth 4 μm)and polishing(grain size 38 to 45 μm),which could satisfy both requirements on efficiency and precision.

Influence of distrbuting process on rotation strength of grinding wheel

WANG Xuetao, ZHANG Ziping, BIAN Huaying

2016, 36(4): 84-87. doi: 10.13394/j.cnki.jgszz.2016.4.0017

Abstract(337)

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Abstract:
According to the theory of maximum stress,the mechanism of ascending rotary strength derived from the increasing density of grinding wheel is analyzed.And the effects of following factors on the density of abrasives are discussed,such as the forming pressure,drying and sintering and the friction between the forming materials and the mould.Based on the practical production,it is shown that under certain conditions,the tensile strength of the grinding wheel can be improved by increasing the density of the grinding wheel.When the repose angle θ of the distribution process,meets to 0<θ≤θ₀,the tensile strength of the grinding wheel can be effectively improved.

2016 Vol. 36, No. 4

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