金刚石与磨料磨具工程

2021, 41(3): 1-4.

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Precision grinding technology of diamond abrasive tools based on grinding method

CUI Zhongming, FENG Changcai, ZHUANG Zhaopeng, WANG Xing, HE Qingshan

2021, 41(3): 5-11. doi: 10.13394/j.cnki.jgszz.2021.3.0001

Abstract(387)

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In this experiment, the technology of grinding diamond abrasive tool with complex profile by grinding method is studied. The typical complex diamond tools are grinded by the method of combination of shape and surface with the optical image grinder. The grinding mechanism is analyzed by theoretical analysis, experiment and microscopic observation of the grinding surface. The influence of the basic grinding process on the grinding efficiency and precision is studied and the relevant laws are determined. The results show that the mechanism of grinding removal is that the surface of diamond is slightly broken by the high stress produced by the local contact points in the contact surface of abrasive particles, so the precision grinding technology based on grinding method has the advantages of high efficiency and precision; the main influence factors of the dressing effect are the grinding depth, grinding speed, grinding wheel, etc.; the precision of single element profile grinding can be improved In order to achieve 0.002 5 mm, angle within 5′, the overall profile accuracy can reach within 0.005 mm, and the surface roughness of grinding workpiece by cut in grinding feed mode after dressing can be less than 0.120 μm.

ECD truing/dressing and cutting edge truncation of diamond grinding wheel and its processing of hard and brittle materials

KANG Xijun, TAMAKI Junichi, AKIHIKO Kubo, QIU Yirui, HUANG Peng

2021, 41(3): 12-18. doi: 10.13394/j.cnki.jgszz.2021.3.0002

Abstract(400)

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In order to study the effect of metal-bonded diamond grinding wheel cutting edge truncation on the surface morphology of hard and brittle materials, the cutting edge of SD600 metal-bonded diamond grinding wheel was first protruded from the metal bond matrix by means of electric contact discharge (ECD) truing and dressing method, then the different cutting edge heights of diamond grains on the surface of the grinding wheel were truncated by cutting edge truncation way. Finally, the hard and the brittle materials for optical equipment, such as borosilicate glass, quartz glass, quartz crystal and sapphire, were plunge ground with the finished grinding wheel. The results show that the improvement of the roughness of the hard and the brittle materials depends on the types of materials. The maximum roughness R_y of borosilicate glass, quartz glass, quartz crystal and sapphire is reduced by 44%, 34%, 30% and 26% respectively compared with that before grinding wheel ECD truing and dressing, and the quartz crystal material most can be realized ductile grinding.

Study on synthesis of polycrystalline cubic boron nitride from hexagonal boron nitride by direct phase transition

WANG Yongkai, WEI Xing, WANG Dapeng, WEI Chaoyang, LIU Hongwei, LU Cuilian, ZHANG Xiangfa

2021, 41(3): 19-22. doi: 10.13394/j.cnki.jgszz.2021.3.0003

Abstract(514)

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Polycrystalline cubic boron nitride was synthesized by direct phase transition at 9~15 GPa and 1 500~2 100 ℃ using hexagonal boron nitride as initial material. The microstructure and mechanical properties of polycrystalline cubic boron nitride bulk materials were characterized by X-ray diffractometer, scanning electron microscope and Vickers hardness tester. The results show that the pure phase polycrystalline cubic boron nitride can be prepared under suitable temperature and pressure with the minimum grain size about 70 nm and the maximum more than 10 μm. At the same temperature, the grain size of polycrystalline cubic boron nitride bulk decreases with the increase of synthesis pressure, and the hardness increases with the increase of synthesis pressure with the highest hardness 64.45 GPa.

Research progress and prospect of polycrystalline diamond

ZOU Qin, XIANG Gangqiang, WANG Yao, LI Yanguo, YIN Yuhang, LI Jing

2021, 41(3): 23-32. doi: 10.13394/j.cnki.jgszz.2021.3.0004

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Polycrystalline diamond (PCD) is sintered under high pressure and high temperature conditions with diamond as the skeleton material and binder as the bonding material. Due to its excellent hardness and good wear resistance, PCD is widely used in cutting tools, drawing die and other fields. In this paper, the binder types, the preparation methods and the factors affecting PCD performance were summarized. The binding mechanism, the advantages and the disadvantages of three types of PCD, namely metal binder, ceramic binder and cermet binder, were introduced respectively. The differences between the preparation methods were compared. Cermet PCD, which combined the good performance of metal PCD and ceramic PCD, had become an important research direction.

Grinding structured grooved surface with grinding wheel wound by diamond wire saw

TANG Chengzhi, LYU Yushan, LI Xingshan, JIANG Kunliang, QI Yongchao

2021, 41(3): 33-39. doi: 10.13394/j.cnki.jgszz.2021.3.0005

Abstract(315)

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To obtain structured surface with micro grooves, a new type of the grinding wheel closely wound by diamond wire saw was designed as well as a method to grind grooved structure with corresponding grinding wheel. Thus, the geometrical and mathematical models of the grinding wheel and the kinematical trajectory equation of the abrasive particles are established. The generating mechanism of grooves and the influences of the grinding parameters on the grooves morphology are analyzed. The feasibility of the structured wheel in grinding grooves are verified by simulation and experiments, as well as the grooves under different parameters. The results show that the grinding wheel could grind structured surface with grooves, and that the sizes and arrangements of grooves are changed with grinding parameters.

Research progress of 3D printing diamond tools

ZHANG Yunhe, HUANG Jingluan, SONG Yunyun, LU Jing, LI Caihong

2021, 41(3): 40-47. doi: 10.13394/j.cnki.jgszz.2021.3.0006

Abstract(463)

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As a rapid prototyping method, 3D printing technology provides convenience for the preparation of diamond tools with complex structure, which is one of the development direction of integrated diamond tools in the future. This paper introduces the basic principles of SLS, SLM, SLA, DIW and other 3D printing technologies used to prepare diamond tools, and their research progress in the preparation of diamond tools. The characteristics of 3D printing diamond tools with different binders are analyzed, and the future development of diamond tools is prospected.

Research on preparation of vitrified bond lapping plates and lapping sapphire performance

LU Jiabin, NIE Xiaowei, YAN Qiusheng, CHEN Haiyang

2021, 41(3): 48-54. doi: 10.13394/j.cnki.jgszz.2021.3.0007

Abstract(444)

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To improve the lapping efficiency and processing quality of the sapphire substrate, two lapping plates composed of vitrified bond diamond lapping pellets with different hardness were developed, and the lapping process experiment was carried out on the sapphire substrate to evaluate its lapping performance. The results showed that as the processing time increases, the material removal rate (R_MRR) and surface roughness (R_a) of two lapping plates both gradually decreased and finally stabilized. With the increase of the rotation of the plate speed, the material removal rate of the two plates first increased and then decreased, when the rotation speed of the plate was 60 r/min, the maximum material removal rates were 1.81 μm/min and 1.27 μm/min, respectively, but the surface roughness continued to decrease. As the lapping pressure increased, the material removal rate of the two plates continued to increase, when the lapping pressure was 34.5 kPa, the maximum of material removal rate reached 2.03 μm/min and 1.49 μm/min, respectively, the minimum of surface roughness were 0.165 μm and 0.141 μm, respectively. Comparing the wear performance of the two lapping plates with different hardnesses, it can be found that the higher the hardness of the lapping plate, the higher the material removal efficiency and the higher the grinding loss ratio of the plate, but the surface roughness of the workpiece was higher.

Study on crack initiation scratching depth of monocrystalline silicon

CHEN Zibin, GE Mengran, BI Wenbo, ZHANG Chenzheng, GE Peiqi

2021, 41(3): 55-59. doi: 10.13394/j.cnki.jgszz.2021.3.0008

Abstract(654)

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As a typical brittle material, the key to achieve the plastic domain processing of monocrystalline silicon is to make the cutting depth less than the crack initiation cutting depth. In this experiment, the fracture strength theory is used to establish a method to calculate the initiation scratching depth of radial crack, median crack and lateral crack for monocrystalline silicon scratching processing. The crack initiation scratching depth and scratch depth are calculated. The experimental device for high-speed scratching monocrystalline silicon with a Berkovich indenter is designed, and the scratch depth of the radial crack initiation is measured in the scratching experiment. The calculated values of the scratch depth at radial crack initiation are in good agreement with the experimental measurements.

Study on mechanism and process of cutting silicon carbide ceramics with diamond wire saw

CHEN Yongbiao, ZHANG Songhui, ZHANG Xiaohong, YUCHI Guangzhi, DUAN Jia, JIANG Ruyi, ZHOU Yingying

2021, 41(3): 60-67. doi: 10.13394/j.cnki.jgszz.2021.3.0009

Abstract(433)

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Through the single factor experiment design of cutting SiC ceramics with diamond wire saw, the influences of technological parameters such as the linear speed, the feed speed and the ratio R of feed speed to linear speed on the surface quality of SiC ceramics were studied. The surface morphology and surface roughness were observed and measured by ultra depth of field three-dimensional microscope and precision roughness profiler. The results show that when the linear speed is increased from 0.4 m/s to 1.3 m/s, the surface morphology of SiC ceramics is obviously improved, and the surface roughness in the feed direction and in the wire saw direction is reduced by 20.35% and 10.45%, respectively. When the feed speed is increased from 6 μm/s to 24 μm/s, the surface morphology has changed from better to worse, and the surface roughness in the feed direction and in the wire saw direction is increased by 12.07% and 3.91%, respectively. When the feed speed and the linear speed are increased, while the ratio R of the two is fixed at 2×10^-5, the surface quality of SiC ceramics is basically maintained at the same level.

Effect of reinforced fiber on cutting swing of ultra-thin and ultra-hard resin grinding wheel

DU Xiaoxu, LI Dashui, LI Caihong, ZHAO Jinwei, DIAO Yinyan, WANG Siliang, WU Leitao, LEI Laigui, HAO Suye

2021, 41(3): 68-73. doi: 10.13394/j.cnki.jgszz.2021.3.0010

Abstract(360)

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Aiming at the big swing amplitude of ultra thin resin integrated cutting wheel the effect of adding carbon fibre, glass fibre and their mixture on the mechanical and cutting performance of the cutters was studied by cutting experiment, and the mechanism that affect the amplitude was studied and analyzed. Results show that the addition of carbon fiber is beneficial to improve the bending strength of grinding wheel, and the addition of glass fiber is beneficial to reduce the cutting resistance of grinding wheel. The combination of carbon fiber and glass fiber can effectively reduce the cutting swing amplitude of grinding wheel. When adding 15% carbon fibre (φ7.6 μm, length of 100 μm) and 5% glass fibre (φ15 μm, length of 120 μm), the amplitude can be effectively decreased to 0.006 7 mm, which satisfies the production requirement.

Research on high efficiency lapping process of cylindrical roller based on consolidated diamond abrasive tool

LEI Yang, YANG Xiaoguang, FENG Kaiping, ZHOU Zhaozhong, YUAN Julong

2021, 41(3): 74-81. doi: 10.13394/j.cnki.jgszz.2021.3.0011

Abstract(399)

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To solve the problem of low efficiency in the high precision grinding process of cylindrical roller, on the basis of double plane eccentric disc polishing method, the lapping method of cylindrical roller based on diamond consolidated abrasive tool is proposed.In order to study the influences of different diamond powder size code, ratio of sand to binder and slurry viscosity on the surface roughness, the material removal rate, the average roundness error and the batch diameter variation of cylindrical roller, the ultra precision lapping of cylindrical roller was carried out by using self-made diamond pellets attached to the upper and lower plates. The results show that the material removal rate and the surface roughness of cylindrical roller increase with the increase of diamond powder size code. If the ratio of sand to binder of diamond pellet is too large or too small, the material removal rate of cylindrical roller will decreases, and then the surface roughness will be affected. The proper viscosity of the lapping fluid can improve the lubrication performance and prevent large particles from scratching the surface of the workpiece. When the size code of diamond powder is M2/4, the pellet ratio of sand to binder is 1.6, and the viscosity of the lapping liquid is 5.380 mPa·s, the material removal rate of cylindrical roller is 1.70 μm/min, the surface roughness R_a decreases from 0.081 μm to 0.025 μm, the average roundness error decreases from 1.085 μm to 0.553 μm, the batch diameter variation R_DWL decreases from 6 μm to 2 μm, and the lapping efficiency and precision of cylindrical roller are significantly improved.

Experimental study on high efficiency grinding process of 5G copper clad laminate composites

GAO Hang, YANG Yong, XU Qihao, WANG Jiale, WANG Yong

2021, 41(3): 82-88. doi: 10.13394/j.cnki.jgszz.2021.3.0012

Abstract(266)

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To solve the problem of burr defects in existing punching 5G copper clad laminate (CCL) composites, a new process of grinding with sintered diamond slotted slice wheel is proposed. Based on the analysis and design of slotted wheel structure parameters, the sintered diamond slotted slice wheel is developed. The influence of different process parameters on the burr of up and low copper layer and the temperature change of grinding zone is studied. The experimental results show that the unit Z-direction grinding force increases with the increase of grinding speed, decreases with the increase of feed speed, and increases first and then decreases with the increase of grinding wheel cutting angle. The trend of burr flash height is opposite to the unit Z grinding force. The grinding temperature increases with the increase of the grinding speed, increases with the increase of the feed speed, and increases first and then decreases with the increase of the cutting angle of the grinding wheel. The optimal parameters for grinding 5G CCL are grinding speed 34.56 m/s, feed speed 1 200 mm/min and cutting angle 22.0°. Under this parameter, the height of burr flash is less than 300 μm, and the temperature of grinding zone is lower.

Particle size distribution characteristics of electrostatic minimum quantity lubrication and grinding surface quality evaluation

JIA Dongzhou, ZHANG Naiqing, LIU Bo, ZHOU Zongming, WANG Xuping, ZHANG Yanbin, MAO Cong, LI Changhe

2021, 41(3): 89-95. doi: 10.13394/j.cnki.jgszz.2021.3.0013

Abstract(547)

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A new method of gas assisted electrostatic atomization minimum quantity lubrication is proposed to solve the problems of low effective utilization rate and threat to the environment and human health due to the low degree of particle size refinement and easy flying of micro droplets atomized by high pressure gas. The contrast test of atomization performance under different working conditions is carried out, and the surface quality of nickel base alloy grinding is evaluated. The atomization test results show that the atomization performance of charged liquid is significantly improved, and the percentage concentration of suspended inhalable small droplets (PM₁₀) is reduced while the average size and distribution span of droplets are reduced. And the higher the voltage is, the lower the mass concentration of PM₁₀ is. When the voltage reaches 35 kV, the atomization effect is the optimal, the average volume particle size and distribution span are reduced by 27.343% and 41.456% respectively, and the mass concentration of PM₁₀ is reduced by 5.065 percentage points. The results of grinding test show that the surface quality of the electrostatic minimum quantity lubrication is better than that of the minimum quantity lubrication by pneumatic atomization, and when the voltage is 35 kV, the surface roughness R_a and R_Sm are 0.377 μm and 0.084 mm, the surface quality of dry grinding workpiece is very poor, there are a lot of adhesion and peeling phenomenon, even a large area of surface material tearing, so dry grinding is not suitable for high temperature nickel base alloy processing.

2021 Vol. 41, No. 3

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