金刚石与磨料磨具工程

Application and development of special machining technology in remanufacturing field

NIU Ziyuan, CHEN Yan, ZHANG Zequn, HAN Bing

2021, 41(5): 1-8. doi: 10.13394/j.cnki.jgszz.2021.5.0001

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Special machining technology can accomplish many machining tasks which cannot be accomplished by traditional machining technology.In recent years, it has been more widely used in the field of remanufacturing.Remanufacturing refers to the reprocessing of waste parts to make up for defects and reuse.This technology is conducive to reducing manufacturing cost, shortening manufacturing cycle and saving resources.Firstly, the process flow of remanufacturing is introduced in this paper.Then, the characteristics of special processing technologies such as magnetic grinding technology, welding technology, thermal spraying technology and laser cladding technology and their applications in the field of remanufacturing are introduced, respectively.Finally, the development of remanufacturing technology is prospected.

Application of brazed coating diamond in remanufacturing of shield cutters

WU Qilong, ZHANG Lei, SUN Huawei, SUN Zhipeng, JIA Lianhui, FU Yucan, ZHU Chenying

2021, 41(5): 9-13. doi: 10.13394/j.cnki.jgszz.2021.5.0002

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The diamond wear-resistant composite coating was prepared on the surfacing layer by induction brazing.The abrasive wear experiment was carried out on the coating, and the microstructure and wear scar characteristics of the brazing coating interface were characterized by stereomicroscope, scanning electron microscope, energy spectrum analysis and wear mass loss.The results show that the diamond composite coating is well formed, the diamond is dispersed in the composite coating, the brazing reaction interface about 5 μm is formed between the solder and the surfacing layer, and a good metallurgical bond is achieved.Under the same wear test conditions, the mass loss of the surfacing layer is 0.601 2 g, and the mass loss of the brazed diamond remanufactured specimen is 0.087 1 g, which is about 14.5% of the mass loss of the surfacing layer.

Effect of particle size of nano-diamond on wear and corrosion resistance of electroless Ni-P composite coatings

XIANG Chunyan, ZHANG Fenglin, WANG Jian, TANG Hongqun

2021, 41(5): 14-20. doi: 10.13394/j.cnki.jgszz.2021.5.0003

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To improve the wear resistance and corrosion resistance of coatings, the Ni-P-D composite coatings which contained various size of nano-diamond particles were prepared by electroless plating.The effects of nano-diamond size on microstructure, mechanical properties, friction characteristics, abrasive wear performance and corrosion resistance of Ni-P coatings were investigated by SEM, XRD, tribological and abrasive wear testing as well as electrochemical experiment.It is discovered that the Ni-P-D composite coatings containing nano-diamond particles with thickness of about 30 μm and well bonding to the steel substrate could be obtained.Ni-P-D composite coating containing 50 nm diamond particles has the highest hardness, the best friction wear resistance and abrasive wear resistance.With the decrease of nano-diamond particle's size, the coefficient of friction decreases, and the corrosion resistance of Ni-P-D composite coating increases.Ni-P-D composite coating containing 5 nm diamond particles has the lowest coefficient of friction and strongest corrosion resistance.

Preparation and characterization of diamond single crystals in Fe-B-C system under high pressure and high temperature

XU Yang, ZHANG Zhuangfei, HUANG Guofeng

2021, 41(5): 21-25. doi: 10.13394/j.cnki.jgszz.2021.5.0004

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High quality boron-doped diamond single crystal was synthesized by using low value pure iron powder as catalyst using a China-type cubic high-pressure apparatus.It is found that the synthetic conditions(temperature and pressure)of diamond increases with the increase of boron addition.The crystal color changes from light yellow to black, and the crystal is mainly in octahedral form.Scanning electron microscopy(SEM)is used to analyze the morphology of boron-doped diamond.It is found that there are round pits in micron size on the {111} crystal surface.According to Raman spectroscopy, the characteristic peak of diamond is blue shifted, and the crystal quality decreases with the increase of half peak width.The strong 2 800 cm^-1 B-C bond absorption peak of Ⅱ b-type diamond can be found by infrared spectrum.In the pure iron catalyst system, the suitable boron addition amount is 0.2%~0.8%, and the quality boron-doped diamond can be synthesized by optimizing preparation technology.

Properties of N-doped graphitized nano diamond electrode materials for supercapacitors

ZHANG Jinhui, LI Jing, YU Jianyuan, ZHANG Xianghong

2021, 41(5): 26-31. doi: 10.13394/j.cnki.jgszz.2021.5.0005

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The mixture of melamine and graphitized nano diamond(GND)was used to prepare super capacitor materials with high energy density and high cycle performance.The raw material was treated at high temperature in nitrogen atmosphere to prepare the core-shell nanocomposites of N-doped graphene(N-GND).Raman spectroscopy and X-ray diffraction analysis showed that the addition of N atoms into the graphite layer increased the defects in the graphite layer to a certain extent without changing its crystal structure.TEM analysis showed that N-doping caused the curl shape of graphite layer around GND.The electrochemical performance of N-GND electrode was tested.Results showed that the specific capacitance of the electrode was 206.7 F/g at 5 mV/s.In the constant-current charge-discharge test of symmetrical two-electrode system, the specific capacitance of N-GND was 198.7 F/g at 0.4 A/g.The specific capacitance attenuated only 4.23% even after 2 000 cycles of CV, indicating excellent cyclic stability of the electrode at 50 mV/s.N-GND, as the electrode material of a new supercapacitor, had good conductivity due to its graphene shell and high thermal and chemical stability for the GND core.It could also avoid the stacking problem of traditional graphene and construct controllable mesoporous channels.In addition, N-doping would improve the capacitance performance.

Investigation of weak corrosion inhibitor for copper chemical mechanical polishing

XU Hao, SONG Enmin, BIAN Da, ZHAO Yongwu

2021, 41(5): 32-39. doi: 10.13394/j.cnki.jgszz.2021.5.0006

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This study uses electrochemical, contact angle, chemical mechanical polishing and other experiments to study the effect of a new environmentally friendly potential copper corrosion inhibitor polyvinyl pyrrolidone(PVP). Experiment results show that PVP has a multi-purpose effect in copper chemical mechanical polishing. That mixing it with another environmentally friendly weak corrosion inhibitor TAZ ensures the flattening effect and environmental protection properties, and can achieve large removal of low pressure in industrial production. When the roughness is 2.28 nm, the removal rate can reach to 1 291 nm/min.

Study on properties of low temperature vitrified bond modified by aluminum powder

WANG Yanming, HOU Yonggai, XIA Xuefeng, LI Wenfeng, HOU Chao, PENG Jin, ZOU Wenjun

2021, 41(5): 40-45. doi: 10.13394/j.cnki.jgszz.2021.5.0007

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To meliorate the properties of low temperature vitrified bond, aluminum powder was added into the vitrified bond by using powder metallurgy method and the metal-ceramic bond was sintered by vacuum hot pressing sintering furnace.The mechanical properties and microstructure of the vitrified bond modified by aluminum powder were investigated.The results show that the average flexural strength and impact strength of the vitrified bond with mass fraction of 20% aluminum powder are significantly improved to 116.32 MPa and 13.01 kJ/m², which are 42% and 414% higher than those of low temperature vitrified bond without aluminum powder, respectively.The addition of aluminum powder has no obvious effect on the density of the vitrified bond.As the mass fraction of aluminum powder increases, the hardness of the vitrified bond generally decreases.Aluminum powder particles can exist in the form of metallic aluminum and show good dispersibility in the low temperature vitrified bond, which can improve the toughness.In the metal-ceramic bond, elements diffusion occurs at the interface between the metal phase and low-temperature vitrified bond, forming a transition zone.And the metal phase and low temperature vitrified bond are inlaid with respect to each other, and possess excellent combination.

Research on surface integrity of GH4169 machined by ultrasonic assisted grinding

HAN Lu, KANG Renke, ZHANG Yuan, DONG Zhigang, BAO Yan

2021, 41(5): 46-51. doi: 10.13394/j.cnki.jgszz.2021.5.0008

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Experiments of GH4169 ultrasonic assisted grinding and conventional grinding were carried out to study the effects of ultrasonic vibration and grinding parameters on microhardness, residual stress and microstructure for the purpose of studying the effect of ultrasonic assisted grinding on the surface integrity of GH4169.The results show that work hardening and residual compressive stress are produced in the surface layer after grinding, and the grain refinement layer is formed.Compared with conventional grinding, ultrasonic assisted grinding can increase the microhardness of the surface layer, as well as the residual compressive stress and the thickness of grain refinement layer.With the increase of grinding wheel speed, the maximum microhardness first decreases and then increases, meanwhile, the residual compressive stress and the thickness of grain refinement layer increase.With the increase of grinding depth, the maximum microhardness, the residual compressive stress and the thickness of grain refinement layer all increase.The change trend of dislocation density is consistent with that of microhardness.

Dynamic characteristics of high speed grinding process of CFRP wheel and steel based wheel

YANG Huaiwen, FENG Wei, ZHU Jianhui, SHI Chaoyu, LIU Baoguo, WU Xiaolei, DING Hao

2021, 41(5): 52-58. doi: 10.13394/j.cnki.jgszz.2021.5.0009

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To explore the influence of CFRP grinding wheel and steel substrate grinding wheel on the dynamic characteristics of high-speed grinding process, a vibration test platform was built on the CNC camshaft grinding machine, and the dynamic characteristics of grinding process were carried out.The vibration signal changes of two kinds of grinding wheel under different linear speeds and different feed speeds were compared.The surface roughness of workpiece after grinding was measured.The results show that the natural frequencies of the spindle system of CFRP grinding wheel are lower than those of the spindle system of steel matrix grinding wheel, and the dominant frequencies excited in the grinding process are in the high frequency region.With the increase of the linear speed of the grinding wheel, the surface roughness of the GCr15 workpiece fluctuates.The grinding surface roughness of the CFRP based grinding wheel is obviously smaller, which is 30%~35% less than that of the steel based grinding wheel.Before and after chatter, the surface roughness of CFRP grinding wheel changed from 0.089 μm to 0.091 μm, increasing by 2.2%.The surface roughness of steel grinding wheel changed from 0.135 μm to 0.146 μm, increasing by 8.2%.When the line speed is confirmed in a range, with the increase of feed speeds, the surface roughnesses of CFRP grinding wheel and steel substrate grinding wheel both increase, increasing by 2.4% and 2.9%, respectively.However, compared to the influence of line speed on surfaceness, the feed speed has relatively small influence on surface roughness.

Grinding force and surface roughness of alumina ceramics ground by brazed micro powder diamond wheel

LI Quancheng, SHEN Jianyun, HUANG Guoqin

2021, 41(5): 59-64. doi: 10.13394/j.cnki.jgszz.2021.5.0010

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Under different grinding depths, wheel speeds and feed rates, the grinding force and surface roughness of the workpiece during grinding alumina ceramics with brazed micro powder diamond wheel were studied, and the processing parameters of low grinding force and low surface roughness of the workpiece were selected.The results show that the alumina ceramic is mainly removed by brittle fracture in the grinding process;with the increase of grinding depths and feed speeds, the forces in feed direction and grinding depth direction and the surface roughness of workpiece increase; with the increase of grinding wheel speeds, the forces in feed direction and cutting depth direction and the surface roughness of workpiece decrease.The process parameters of low grinding force and low surface roughness are obtained in this study.The low grinding force would be obtained with grinding depth 1.0 μm, feed speed 12 mm/min, and wheel speed 24 000 r/min.The low surface roughness after precision maching would be obtained with grinding depth 1.0 μm, feed speed 1 mm/min and wheel speed of 20 000 r/min.For low grinding force, the grinding forces in X direction and Z direction are 0.15 N and 0.72 N, respectively.After precision machining, the surface roughness of alumina ceramics can reach 0.438 μm.

Model analysis and experiment of contact pressure in belt grinding

WANG Yajie, HUANG Yun

2021, 41(5): 65-69. doi: 10.13394/j.cnki.jgszz.2021.5.0011

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To verify the accuracy of Hertz contact model in belt grinding, a contact finite element model of abrasive belt grinding is established by using ABAQUS software.The influence of several factors on the contact pressure and the contact parameters are analyzed, namely the thickness ratio, the rubber hardness, the contact pressure and the curvature radius of workpiece.The rationality of the model is proved by contact experiment between the rubber contact wheel and the planar or curved workpiece.The results of analysis and test show that the contact state of abrasive belt grinding is basically in accordance with Hertz contact theory, ignoring the less influential factors.When the cylindrical contact wheel is in contact with the curved workpiece, the contact stress distribution is semi ellipsoidal, which is verified by the finite element analysis and the test results.When the thickness ratio is 20% and the Shore hardness of rubber is 70 HS, the mechanical properties of the rubber contact wheel have the least error with the Hertz contact theory.

Cutting performance of diamond coated tools for machining graphite

CHEN Shoufeng, WANG Chengyong, ZHENG Lijuan, ZHOU Yuhai, YU Xinwei, LI Wenhong

2021, 41(5): 70-76. doi: 10.13394/j.cnki.jgszz.2021.5.0012

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To compare the cutting performance of different types of diamond coated tools, a variety of tools with different diamond coated materials were selected for the machining of graphite materials, and WC cemented carbide tool and TiAlN coated tools were used for comparison.The cutting life, coating morphology, surface quality and cutting force of different diamond coated tools were analyzed.The results show that the coating morphologies of diamond coated tools are mainly nanocrystalline and microcrystalline.The cutting life of diamond coated tools is more than ten times that of cemented carbide and TiAlN coated tools.The cutting life of several different types of diamond coated tools has little difference.However, the refinement of diamond coated surface grains can reduce surface roughness and the cutting force.Coating falling off is the main wear form of diamond tools.

Preparation and properties of nickel-boron-diamond ultrathin dicing blades

ZHANG Lan, SONG Wentao, LI Na, MA Huizhong

2021, 41(5): 77-83. doi: 10.13394/j.cnki.jgszz.2021.5.0013

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Diverse concentrations of trimethylamine borane(TMAB)were added into the nickel sulfamate electrolyte.The Ni-B-diamond dicing blades with different boron content were prepared by composite electrodeposition under the state of spinning the cathode.The influence of different concentrations of TMAB on the crystal structure, the hardness, and the wear resistance of the dicing blades were explored.The results show that the diamond on the dicing blades prepared under the spinning state of the cathode is distributed uniformly.With the increase of TMAB mass concentration, the grain size is decreased, the hardness and the wear resistance is improved.When the TMAB mass concentration is 3.0 g/L, the minimum grain size of the substrate metal is 6.84 nm, the maximum hardness is 2 453.6 HV, the minimum wear is 1.7×10^-2mm³,and the minimum wear width is 665.4 μm.The Ni-B-diamond cutting disc with a thickness of 28.3 μm is used to cut the N-type single crystal silicon wafer with a crystal plane of(111).The groove width of the silicon wafer is 35.3 μm, the ratio of groove width to knife thickness is 1.25, and the maximum chipping size is 3.1 μm.

Optimization of grinding process parameters of diamond thin circular saw blade substrate

QIU Luyi, WANG Qiuyan, BAI Shuowei, JU Junwei, LIN Runze

2021, 41(5): 84-88. doi: 10.13394/j.cnki.jgszz.2021.5.0014

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Aiming at the surface quality control of diamond thin circular saw blade substrate grinding, the orthogonal experiment of circular saw blade substrate grinding was carried out on the NC horizontal axis circular table surface grinder.The effects of grinding process parameters on the end jump, the flatness and the thickness difference of the same blade were studied.The results show that the rotation speed of the grinding wheel has the most significant effect on the end jump.Increasing the rotation speed of the grinding wheel is beneficial to reduce the end jump.The rotation speed of the worktable has the most significant effect on the flatness and the thickness difference of the same blade.Increasing the rotation speed of the worktable is beneficial to obtain a smooth and clean surface.The optimized grinding process parameter combination is that the grinding wheel speed is 1 500 r/min, the feed speed is 3 000 mm/min, the worktable speed is 250 r/min and the magnetic force is 90%.After grinding the matrix of diamond circular saw blade under this parameters, the end jump, the flatness and the thickness difference of the same blade after grinding are 0.08, 0.02 and 0.004 mm respectively, which are far less than 0.12, 0.08 and 0.020 mm specified in the standard, and there are no obvious grinding damage defects.

Cutting edge trimming of high speed steel milling cutter based on shear thickening fluid

WANG Minghai, ZHANG Jingbo, LONG Zhikai, WANG Ben, LIU Biao, CI Yanhai

2021, 41(5): 89-94. doi: 10.13394/j.cnki.jgszz.2021.5.0015

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To study the effect of shear thickening polishing fluid on the cutting edge of milling cutter, a four-edge high speed steel flat end milling cutter was taken as the research object, and the high speed steel cutter was trimmed.The cutting edge radius of the milling cutter was measured and the cutting edge morphology of the milling cutter was observed.The experimental results showed that the cutting edge radius decreased after trimming, but the cutting edge radius decreased to different degrees due to the different initial states.The maximum change was 7.5 μm, and the minimum change was 0.4 μm.In the trimming experiment, only the cutting edge of the milling cutter was trimmed.The front and back face of the milling cutter did not change obviously.The grinding marks were not removed.Abrasive particle size had a certain influence on the trimming effect.After trimming, the average cutting radius of a, b and c three silicon carbide STF experimental groups decreased by 4.6 μm, 3.6 μm and 1.9 μm, respectively.The larger the grinding particle size was, the more obvious the change of milling cutter edge radius was.

Path planning for blade polishing with fixed abrasive tool base on robotic platform

LIU Jidong, XU Chengyu, ZHU Yongwei

2021, 41(5): 95-101. doi: 10.13394/j.cnki.jgszz.2021.5.0016

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The 6R robotic and the fixed abrasive polishing technology were combined to develop a robotic-based fixed abrasive polishing system.The constant chord-height error method and the improved constant residual-height method were used for planning blade polishing path.Based on the secondary development of the software UG, path planning algorithm was realized and the data of cutter points was extracted.Combining with the inverse kinematics algorithm of robot and polishing process parameters, the off-line programming of polishing path was realized, and the blade polishing test was verified on the constant pressure polishing test platform of robot consolidated abrasive grinding head.The main results show that the average surface roughness of the blade is 0.240 μm, the standard deviation of the roughness is 0.039 μm, and the polishing pressure error is ±0.7 N. The high consistency of surface quality of blade was obtained by applying the robotic-based consolidated abrasive grinding head.

2021 Vol. 41, No. 5

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