金刚石与磨料磨具工程

Performance evaluation of self-propagating high-temperature synthesized diamond grinding head

DUAN Duanzhi, LUO Weidong, XIAO Bing, HAN Linlin, BU Yue

2017, 37(3): 1-5. doi: 10.13394/j.cnki.jgszz.2017.3.0001

Abstract(268)

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Abstract:
To study the influence of self-propagating process on the performance of diamond grinding head, high-frequency induction heating was used to induce self-propagating systhesis of Al, Ti, Cu, Ni and Sn powder and produce the heads.Microstructure of the heads and the bonding interface between diamond and metal matrix were analyzed.Grinding experiments were implemented to study the performance of heads.Resultsshow that high-frequency induction helps to reduce the pre-heating time and reaction time, thus increasing efficiency, and that Ni is a key element without which the reaction could not start.It is also found that diamond grains bond well with metal bonds, and that C and Ti diffuses and aggregates across the interface.In conclusion, the comprehensive processing performance of diamond grinding head is the best when the mass fraction of Al+Ti is 32%.

Effect of processing on toughness index of diamond grains during vacuum brazing

LIU Fan, PAN Bingsuo, XIE Tao, ZHANG Jianwei

2017, 37(3): 6-10. doi: 10.13394/j.cnki.jgszz.2017.3.0002

Abstract(270)

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To reduce the thermal damage when brazing diamond, four solutions are proposed and tested according to the thermal damage mechanism of diamonds.SEM observation and toughness index test are used to analyze those solutions.Resultsshow that reducing oxygen content in the stove has limited effect on improving toughness index (TI) values of diamond, while reducing content of catalyst and coating diamond with Ti-Ni composite layers would increase TI, compared with that of the original process, by more than 15% and 20% separately.It is found that Cu-based solder causes the smallest thermal damage to diamond, whose toughness index remains 91.5% of the original state.

Preparation and drilling properties of dry drilling diamond bit

XU Liang, LIU Yibo, XU Qiang, SHEN Ningning

2017, 37(3): 11-14. doi: 10.13394/j.cnki.jgszz.2017.3.003

Abstract(296)

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Abstract:
The advantages of dry drilling bit are introduced, as well as the status of domestic dry drilling market, and the principle of the bit matrix design.Ultra-fine tungsten copper alloy powder helps to solve the problems of sintering and drilling in experiment.Tungsten copper alloy powder (mass fraction 45%), with metal powder (Cu, Co, Ni, etc.), is used to make experimental bit matrix through the process of granulation, pre-compression, dewaxing, sintering, and welding.Resultsshow that when sintered at 850℃, and 25 MPa for 180 s, the hardness of bit segment is more than HRB110, and the effect of diamond grit protrusion is good.Compared with the drilling bit imported from Korean, the granite drilling efficiency of domestic bit is increased by 7%, while the life is equal with Korean drilling bit, which reflects the good performance of dry drilling.

Effect of Al₂O₃ hollow sphere on properties of resin bond diamond disc in sapphire grinding

SHI Linfeng, HAN Xue, GAO Yongjuan, LIU Quanwei

2017, 37(3): 15-18. doi: 10.13394/j.cnki.jgszz.2017.3.004

Abstract(279)

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Abstract:
To improve the lapping effect of sapphire grinding, Al₂O₃ hollow sphere is added into resin bond diamond grinding disc.Effect of sphere size and volume fraction on strength of the bond and performance of the disc are studied through mechanical test, SEM analysis and actual grinding.Resultsshow that as the size and proportion of sphere increase, the bending strength of the sample decreases, and that when the volume fraction of sphere reaches 30%, sphere size has no obvious effect on the strength.It is also found that efficiency of grinding sapphire is increased through adding Al₂O₃ hollow sphere, and the surface roughness of sapphire is improved.In conclusion, when volume fraction of sphere is 20%, the grinding disc has best comprehensive grinding performance, whose R_a decreases to 0.249μm and the efficiency is increased by 82.6% compared with that of non-sphere grinding discs.

Influence of different CBN grains on grinding performance of resin bonded CBN grinding wheel

LI Kehua, XIONG Huajun, GAO Yongjuan, SHI Linfeng, HAN Xue

2017, 37(3): 19-22,34. doi: 10.13394/j.cnki.jgszz.2017.3.0005

Abstract(335)

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Abstract:
The compressive fracture strength, toughness index (TI) and thermal toughness index (TTI) data of 6kinds of different CBN abrasive grains are studied, and these grains are made into resin bonded CBN grinding wheel, respectively.The grinding ratios of different CBN abrasives on different materials, such as cast iron, high speed steel, stainless steel and nitride stainless steel are researched.Resultsshow that at the same condition of wheel binders and production process, grinding ratios of different CBN abrasive grains show the dramatic differences.Grinding ratios of resin bonded CBN wheels for grinding the cast iron and high speed steel are relatively higher, while its grinding ratios for grinding the stainless steel and nitride stainless steel are lower.It is also found that grinding performances of CBN-B1500and CBN850 abrasive are relatively better for four materials.In conclusion, because of CBN grains in the grinding wheel are fixed by the mechanical insertion force of the resin binder, and so CBN grains with rough surface and moderate compressive fracture strength are better choice.

Influence of line defect in cemented carbide substrate on bonding strength between diamond coating film and substrate

ZHANG Kuilin, CHEN Jun, HUANG Zhuo, JIAN Xiaogang

2017, 37(3): 23-28. doi: 10.13394/j.cnki.jgszz.2017.3.0006

Abstract(306)

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Abstract:
The first principles plane wave pseudopotential method based upon density functional theory (DFT) is used to investigate the bonding strength of diamond coating film on cemented carbide substrate with different line defect ratios.The interface molecular models between diamond coating film and substrate are built with different crystal orientations namely[111],[110]and[100], which are used to study the influence of the line defect ratio in cemented carbide substrate on the bonding strength of boundary and best interfacial bonding strength with three different crystal orientations.Resultsshow that the surface energy of cemented carbide substrate increases at first and then decreases as the line defect ratio in substrate surface grows and that when the line defect ratio ρ is 12.5%, the surface energy reaches to the maximum.It is further found that the optimal bonding energy of diamond coating interface with different crystal orientations have different optimal line defect ratios of substrate.The optimal line defect ratio ρ is 6.25%for diamond crystal of[111]and[110]orientations, but ρ=0for[100]orientation.

Progress on dressing technology of monolayer brazed diamond grinding wheel

DENG Hui, DENG Chaohui

2017, 37(3): 29-34. doi: 10.13394/j.cnki.jgszz.2017.3.0007

Abstract(254)

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Abstract:
The current dressing methods of monolayer brazed diamond grinding wheel and their latest research progress are reviewed, and the problems in the practical application are pointed out.In view of these problems, the development concept of dressing technology of monolayer brazed diamond grinding wheel is proposed, which can provide reference for solving the problem of precision, high efficiency and no damage dressing of monolayer brazed diamond grinding wheel.

Characteristic changes of acoustic emission(AE)signal during high speed deep grinding of cemented carbide PA30

GUO Li, DU Houbin, DENG Yu

2017, 37(3): 35-39. doi: 10.13394/j.cnki.jgszz.2017.3.0008

Abstract(294)

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Abstract:
In acoustic emission (AE) experiment on high speed deep grinding cemented carbide PA30, which is a hard difficult-to-machine material, the root-mean-square characteristic parameters of acoustic emission signal (AE_RMS) and grinding force increase as the workpiece speed and the depth of cut increase, while they decrease as the wheel speed increase.Therefore, the grinding force and the AE_RMS have the same change tendency.The spectrum energy of the acoustic emission signal when high speed deep grinding cemented carbide PA30 is focused on 100~600kHz spectral ranges.The energy and frequency range of the AE signal spectrum are larger than that in low speed shallow grinding.

Analysis on uniformity of particle trajectories in laser wafer polishing

KANG Renke, ZHAO Haiyang, ZHU Xianglong, JIAO Zhenhua

2017, 37(3): 40-45. doi: 10.13394/j.cnki.jgszz.2017.3.0009

Abstract(289)

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Abstract:
To analyze effect of rotation ratio α and swing ratio β on distribution uniformity of grain trajectory during wafer polishing, two models are established, namely relative velocity between wafer and pad, and grain trajectory on wafer surface.Distribution law of relative velocity and particle trajectory density statistics are studied.Resultsshow that when the rotation speeds of wafer and pad are kept consistent, the relative speed is stable.It is also found that the reciprocating motion of wafer following polishing head mainly influences periodicity of relative speed changes and randomness of grain trajectory distribution.In conclusion, when α=1.01 and β=0.2, the homogeneity of grain trajectory distribution on wafer is the best.

Influencing characteristic of submicroscopic chamfering cutting edge on the cutting property of cemented carbide insert

HE Genghuang, LI Lingxiang, ZOU Lingli, CHENG Cheng, LIU Xianli

2017, 37(3): 46-54. doi: 10.13394/j.cnki.jgszz.2017.3.0010

Abstract(255)

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In order to study the action mechanism of micro cutting edge form of carbide insert on the cutting performance, aiming at the problems of tipping and brittle fracture of carbide insert during interrupted cutting, interrupted cutting experiments are carried out using two different grades of cemented carbide indexable inserts under the condition of multiple submicroscopic structures of cutting edge.The three dimensional stress analyzer and high-speed camera are used to data monitoring and collection of impact and cutting force in the cutting process.Then the strengthening effect mechanism of the micro chamfering edge on the cemented carbide insert is researched combining with graphic statistical analysis method with the goal of revealing the influence rule of cutting edge geometry parameters on the blade life, proposing the curvilinear relationship between chamfering edge parameters and feed rate.The results prove that the larger critical angle β_C, chamfer angle β and the smaller chamfering width L should be selected under the condition of large feed rate f.Conversely, the smaller critical angle β_C, chamfer angle β and the larger chamfering width L have better performance under the small feed rate f.The results can provide data and technical support for the strengthening design of cemented carbide indexable insert.

Prediction of subsurface damage of endless diamond wire sawing YAG crystal

LIU Wentao, ZHAO Huiying, LI Bin, ZHAO Lingyu, YU Hechun, FANG Hongjun

2017, 37(3): 55-61,68. doi: 10.13394/j.cnki.jgszz.2017.3.0011

Abstract(295)

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The material performance and the service life of YAG (Y₃Al₅O₁₂) crystal are reduced due to subsurface damage.Based on the classical fracture mechanics model of brittle solids and the formula to calculate median crack depth, it is found out that the median crack is the main factor of subsurface damage (SSD) of brittle material.Through the statistics of the number of diamond grits and the summary of diamond wire cutting parameters, the cutting depth, the normal and tangential forces of single abrasive grain and the cutting projected area was calculated, it is predicted that SSD is closely related to the diamond wire speed v_s, feed speed v_w, cutting material properties, particle size distribution of diamond on electroplated saw wire, and so on.Finally, it is suggested that the model needs further revision through experiments.

Experimental research on ultrasonic cutting honeycomb cores by disc cutter

NIU Jinglu, ZHU Xianglong, KANG Renke, WANG Yidan, DONG Zhigang

2017, 37(3): 62-68. doi: 10.13394/j.cnki.jgszz.2017.3.0012

Abstract(356)

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To improve the quality and efficiency of Nomex honeycomb material, actual experiments are used to test the cutting force during ultrasonic cutting.The influencing factors and changing laws of the force are studied.The surface of honeycomb is observed after cutting.Regression analysis is used to research the cutting forces at different amplitudes and cutting depths.An empirical formula is derived.Resultsshow that there is a index relationship between cutting forces (F_y and F<sub>z) and cutting depth a_p and the amplitude A at bottom edge of blade.It is found that there is within 10% error between actual and simulating forces, and the surface of cutting honeycomb is flat with less veining.

Research on dressing and truing of microarc diamond tool

XIA Zhihui, JIA Lu, ZHANG Xiaofeng, CHU Chong

2017, 37(3): 69-73. doi: 10.13394/j.cnki.jgszz.2017.3.0013

Abstract(309)

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Abstract:
The microarc diamond tool is widely applied in ultra-precision machining.Research on micro arc diamond cutter dressing technology is implemented based on mechanical grinding.Through the analysis of the preparation technology of microarc diamond tool and its difficulty, a new method to dress the microarc diamond tool is designed to solve technical nodi such as locating at both hard and easy directions, breakage of blade tips, and precision dressing of tip arc.Experiments show that a microarc diamond tool with tip radius of 8.2μm is prepared, which is investigated using atomic force microscope and high-magnification optical microscope.It is found that the roughness of the rake face was 1.50 nm and the profile waviness of the tip better than 0.1μm, which is slmiliar to imported high-precision tools.Actual application of ultra-precision cutting microstructure reveals that the tool has good machining effect.

Optimal design of cutting performance of diamond ordered arrangement saw blade

ZHANG Wenzhong, YANG Hong

2017, 37(3): 74-77,80. doi: 10.13394/j.cnki.jgszz.2017.3.0014

Abstract(325)

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The technology of independent research and development on diamond ordered arrangement is used to the produce diamond three-dimensional ordered arrangement saw blade.Then, the cutting performance of the blade is examined by sawing contrast experiment.The results show that diamond three-dimensional ordered arrangement saw blade can improve blade sharpness and the life, farther to improve its cutting performance through the diamond surface treatment.Its sharpness compared with that of traditional saw blade increased by 27.7% and life expectancy increased by 66.6%.

Design and application of new elastic turntable applied for compression moulding

XING Bo, LU Tao, YAN Ning, SHAO Junyong, HAN Xin, LI Hongtao

2017, 37(3): 78-80. doi: 10.13394/j.cnki.jgszz.2017.3.0015

Abstract(244)

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Abstract:
Compression moulding is the key process in the preparation of the abrasive layer of super hard material grinding wheel.A kind of elastic turntable is designed to replace manual operation, improve production efficiency, and stabilize the quality.The composition and working principle of the elastic turntable is introduced in detail.And the effect of application is described as well.The result shows that the mould is simple, easy to operate, and has better promotion value.

Preparation of rapid electroplating diamond wire saw

DAI Xiaonan, HE Weichun, LI Zhengxin, HE Jingyuan

2017, 37(3): 81-87. doi: 10.13394/j.cnki.jgszz.2017.3.0016

Abstract(405)

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Abstract:
In order to improve the efficiency of preparing of diamond wire saw, sanding process is improved by chemical nickel plating on diamond micropowder surface, magnetization steel wire substrate.SEM, EDS and Gauss meter are used to study parameters influence on efficiency and durability.The experimental results show that the magnetic induction of substrate, diamond mass concentration and sanding time for wire saw preparation have important effect on the efficiency and durability.The best process parameters with magnetized substrate are:current density 5 A/dm², magnetic induction of substrate is 0.6 mT, diamond mass concentration 15 g/L, sanding time 30 s, temperature 45℃.Compared with untreated diamond and substrate, the sanding time can be decreased by 1/20 of the original process, thus improving total process by 81%, while wire saw still maintains high durability.

Coarse grinding parameters on sapphire wafer

DONG Yunna

2017, 37(3): 88-90. doi: 10.13394/j.cnki.jgszz.2017.3.0017

Abstract(305)

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Abstract:
Coarse grinding sapphire wafer surface technology is researched by using 61 μm boron carbide, Single factor experiment is used to discuss and test the influence of slurry, lapping pressure and boron carbide content.Resultsshow that the best effect appears when mass fraction of boron carbide is 20% with CM-F series slurry, flow rate 250 mL/min, lapping at 80r/min for 30 min, grinding pressure 2.8×10⁴ Pa, the material removal rate can reach 2.47μm/min, with no visible scratches on the surface.The surface quality improved obviously using the OLYMPUS-MX50observation.

Surface quality of grinding optical glasses using eletroplated diamond wheel

MENG Xinxin, LIN Youxi, REN Zhiying

2017, 37(3): 91-95. doi: 10.13394/j.cnki.jgszz.2017.3.0018

Abstract(375)

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Abstract:
Optical glass is widely applied in aerospace, photoelectricity, space technology, precision engineering and other fields.Requirements on surface quality of optical glass are getting higher and higher.In this paper, grinding optical glasses with large abrasive eletroplated diamond wheel is researched, including the influence of grinding parameters on surface quality of optical glass from two aspects of grinding force and surface morphology.In addition, the research progress of two kinds of machining methods, namely ultrasonic grinding and compression molding, are reviewed and the future development trend of optical glasses processing has been predicted.

2017 Vol. 37, No. 3

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