金刚石与磨料磨具工程

Research on grinding force of titanium alloy TC17 with microcrystalline alumina grinding wheel

CAO Ke, DONG Zhigang, KANG Renke, ZHU Xianglong, LIU Jinting

2016, 36(5): 1-7,14. doi: 10.13394/j.cnki.jgszz.2016.5.0001

Abstract(338)

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Abstract:
Grinding experiments were conducted on titanium alloy TC17 with microcrystalline alumina and white alumina grinding wheels separately to study their grinding performance,such as surface quality and grinding force.The results show that surface ground by microcrystalline alumina has better quality,with surface roughness value decreased by 0.14 μm and grinding force decreased by 10%.Single factor tests were conducted to study the influence of grinding parameters on the grinding force of microcrystalline alumina wheels.It is found that the optimal parameters for grinding TC17 are linear speed of the wheel v_s=27 m/s,grinding depth a_p=0.01 mm and workpiece infeed rate v_w=12m/min.In the end,multiple linear regression analysis is carried out on test data of grinding force,and the regression models of normal and tangential forces of grinding are established.

Microwave method coated nanodiamond and its application progress in catalytic area

ZHANG Yan, ZANG Jianbing, TIAN Pengfei, XU Hanqing, HAN Chan, WANG Yanhui

2016, 36(5): 8-14. doi: 10.13394/j.cnki.jgszz.2016.5.0002

Abstract(323)

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Nanodiamond(ND)can be used as catalyst carrier in catalytic area because of its excellent thermal conductivity,thermal stability and specific area.This paper reviews the application of microwave coated ND in fuel cells,focusing on the preparation of platinum catalyst which is carried by TiO₂/ND(GND,graphic nano-diamond)and TiN/ND,and Co-N Co-doped ND non-platinum Co-N-C/ND catalyst.Phase,morphology and composition of above products are studied by using XRD and TEM,and the electrochemical activity of Pt/TiO₂/ND(GND),Pt/TiN/ND and Co-N-C/ND catalyst is tested by electrochemical experiment.Resultsshow that coating ND by using microwave will enhance its performance and widen its application in catalyst area.

Preparation of slurry for photocatalytic assisted chemical mechanical polishing CVD diamond

YUAN Zewei, DU Haiyang, HE Yan, ZHANG Yue

2016, 36(5): 15-20,31. doi: 10.13394/j.cnki.jgszz.2016.5.0003

Abstract(476)

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Abstract:
CVD diamond has been widely applied in various fields.Despite several existing processing methods,many problems,such as low efficiency and poor precision,still arise in actual applications.To avoid the problems of the existing methods for polishing diamond,this study prepares a new type of slurry for polishing diamond using TiO₂ photocatalytic oxidation theory.Firstly,the apparatus is set up according to the mechanism of photocatalytic oxidation.Then,the slurry is characterized with the methyl orange solution and the oxidation-reduction potential(ORP)analyzer.Finally,the CVD diamond is polished with the photocatalytic assisted chemical mechanical polishing method.The results show that P25 TiO₂ photocatalytic shows the best oxidation activity.The effect on catalyst activity is obvious when adding 1 mL of H₂O₂ and 0.2 mL of H₃PO₄ per 100 mL water,and the oxidation ability is the best.The CVD diamond is polished smoothly by using the new slurry.

Chemical mechanical polishing process parameters of 304 stainless steel

LI Qing, CHEN Shaokun, PENG Yanan, QIN Hongquan, FU Sufang, SU Jianxiu

2016, 36(5): 21-25. doi: 10.13394/j.cnki.jgszz.2016.5.0004

Abstract(529)

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Abstract:
When chemical-mechanically polishing 304 stainless steel,the effects of polishing pressure,polishing slurry flow rate,polishing speed and polishing time on the material removal rate and surface roughness are studied for better performance,lower cost and higher efficiency.Experimental results show that the material removal rate reaches 226.56 nm/min and the surface roughness reduces to 6nm at the condition of polishing pressure 13.79 kPa,slurry flow rate 15 mL/min,polishing time 35 min,and polishing speed 60 r/min,which ensures the best surface rough degree and higher material removal rate.

Creep-feed grinding of nickel-based superalloy GH4169 spline using micro-crystalline alumina wheels

HE Jian, YU Jie, DAI Chenwei, DING Wenfeng

2016, 36(5): 26-31. doi: 10.13394/j.cnki.jgszz.2016.5.0005

Abstract(317)

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Abstract:
Nickel-based superalloy GH4169,as a typical difficult-to-cut material,has been widely used in aero-engine components.The micro-crystalline alumina wheel is becoming popular in grinding aeroengine materials due to its excellent performance of self-sharpening.In order to find out the most suitable wheel to manufacture superalloy components,experiments on creep-feed grinding nickel-based superalloy are carried out using SG,5SG and TG abrasive wheels to investigate the influence of abrasive types on grinding force,grinding temperature and surface roughness.The results show that the grinding force and grinding temperature are the smallest when using 5SG abrasive wheel,followed by TG abrasive wheel,then SG abrasive wheel.The surface roughness values are all below 0.3 μm after grinding with the tested wheels.When 5SG abrasive micro-crystalline alumina wheel is chosen to manufacture the superalloy spline specimen,all detected results meet the requirements well.

Surface topography of metal bonded arc grinding wheel after electrical discharge dressing

LIU Zhongde, ZHANG Feihu, WANG Kai, LI Chen, MA Zhaokai

2016, 36(5): 32-37,41. doi: 10.13394/j.cnki.jgszz.2016.5.0006

Abstract(333)

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Abstract:
Due to the efficient process property,metal bonded diamond arc grinding wheel has been employed in the process of the large aperture SiC china gradually. However,the amount of consumption limits its application.To eliminate consumption of the grinding wheel,the paper proposes electrodischarge machining(EDM)to dress metal bonded arc grinding wheels and makes some single factor experiments of voltage,current,pulse frequency for grinding wheel of 50-63 μm grain size.The relationship between different electric factors and grinding wheel surface is inspected by super depth field microscope,as well as the relationship between surface removal quantity and electric factors.It is shown that in condition of voltage 60 V,pulse frequency 25 kHz and multiple channel current,better quality of grinding wheel surface could be achieved.

Fabrication and microstructure analysis of Ti₃AlC₂-CBN composites

LIANG Baoyan, ZHANG Wangxi, FENG Yanxiang, MU Yunchao

2016, 36(5): 38-41. doi: 10.13394/j.cnki.jgszz.2016.5.0007

Abstract(300)

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Abstract:
Ti₃AlC₂-CBN composites are fabricated by spark plasma sintering using Ti₃AlC₂ and CBN powders as raw materials.Effect of CBN size and mass fraction on the phase composition and microstructure of the composites are studied.The results show that the main phases of the sample containing 10wt% CBN are Ti₃AlC₂,CBN and TiC.When CBN mass fraction is higher(20wt%-40wt%),TiC,TiN,AlN and TiB₂ phases are formed.It is also shown that with 10wt% or 20wt% CBN,transition layer with a thickness of about 10 μm is formed on the surface of the CBN,while with 30 wt% or 40wt% CBN,there is no transition layer between CBN and the matrix.Many pores appear in the composite containing 10wt% CBN with a size of about 10 μm,whose main phase is TiC equiaxed grains with 1-2 μm transition layer on the surface of CBN.In conclusion,as CBN content increases or its mass fraction size decreases,CBN reacts more with Ti₃AlC₂,thus producing a thinner transition layer.

Influence of superfinishing parameters on residual stress of bearing raceway

GE Peiqi, BI Wenbo, ZHENG Chuandong

2016, 36(5): 42-45. doi: 10.13394/j.cnki.jgszz.2016.5.0008

Abstract(425)

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Abstract:
The experiments for 7008 Cbearing inner ring superfinishing are carried out with different processing parameters.An X-ray stress analyzer is applied to measure circumferential and axial residual stress at the bottom of the raceway of 7008 Cbearing inner ring.The results show that the residual stress on bearing raceway surface is compressive stress,the average value of which ranges from -266 MPa to -438 MPa.It is also shown that the circumferential residual stress is larger than the axial residual stress.In addition,the force pressed on the oilstone has a significant influence on the residual compressive stress of bearing raceway surface,thus the increase of the former leading to an increase of the latter.

Modeling and simulation of surface form accuracy for aspheric SiC mirror based on reciprocating grinding

ZHANG Feihu, MA Zhaokai, LI Chen, RAO Xiaoshuang

2016, 36(5): 46-49,54. doi: 10.13394/j.cnki.jgszz.2016.5.0009

Abstract(308)

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To study the performance of grinding aspheric SiC mirror with arc-shaped grinding wheel,the model of residual height of aspheric silicon carbide mirror is established based on the reciprocating grinding,and the prediction model of surface form accuracy is simulated and analyzed through the relationship between the residual height and the surface form accuracy.Resultsshow that the surface form accuracy decreases with the increase of cutting arc length and inclination angle,and that the accuracy is improved with the increase of base circle radius or arc radius of grinding wheel.The cutting circular arc length and base circle radius of grinding wheel have great influence on surface form accuracy.

Wear mechanism of the PCBN cutting tools in high speed cutting of hardened bearing steel

DENG Fuming, DENG Wenli, YANG Xuefeng, ZHANG Pan, LIU Ruiping, MA Xiangdong

2016, 36(5): 50-54. doi: 10.13394/j.cnki.jgszz.2016.5.0010

Abstract(353)

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The BZN9000 compacts from D.I.Company in the USA is selected and its high speed cutting experiments are carried out on the GCr15 hardened bearing steel ring by using the CA6140 Alathe.The morphologies and the element contents of rake and flank face of the PCBN tool are observed and analyzed by means of SEM,EDS and WDS respectively.It is found that the main wear forms of the PCBN tool are mechanical wear,adhesive diffusion wear and chemical wear in the high speed cutting process.The main wear form of the rake face is crater wear,where the adhesion diffuse in the cutting edge and the edges of the crater are more serious than that in the bottom of the crater.WDS inspection on the flank face shows that the adhesion diffuse in the points near the cutting edge are more serious than that in other points in the flank face.

Tensile performance and fracture analysis of brazed diamond wire saw

ZHANG Ziyu, XIAO Bing, WANG Bo, WANG Pengfei

2016, 36(5): 55-59. doi: 10.13394/j.cnki.jgszz.2016.5.0011

Abstract(363)

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Abstract:
Diamond grits are brazed on the surface of 0Cr18Ni9 stainless steel wire by using Cu-Sn-Ti pre-alloyed powder as interlayer materials,thus producing diamond wire saw with a diameter of 0.8 mm.Mechanical properties of steel wire and wire saws are obtained by tensile tests,and the crystalline structures of wire cross sections before and after brazing are analyzed.Fracture morphology of the wire is observed by using scanning electron microscope.Then the tensile fracture mechanism is analyzed.Resultsshow that diamond grits are firmly brazed on 0Cr18Ni9 stainless steel surface,forming a wearresistant layer.The tensile strength of brazed wire saws remains over 700 MPa and yield strength 600 MPa with plasticity enhanced largely.Austenite in wire matrix grows and the uniformity of the tissue increases sharply.The tensile fracture mode of heated wire is ductile,and the tensile failure mode of working layer is alloy break and strip from the matrix.

Transverse vibration analysis of diamond saw blade at different speeds

ZHAO Min, LI Xu

2016, 36(5): 60-63. doi: 10.13394/j.cnki.jgszz.2016.5.0012

Abstract(325)

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Abstract:
Diamond circular saw blade has become the most important cutting tool during the stone machining and has been used widely in cutting stones.Because the ratio of diameter to thickness is usually larger than 200,the bending ability of blades is limited.Diamond saw blade could also cause vibration in high speed cutting.Once the frequency is close to other external excitation frequency,resonance will occur and the amplitude will increase rapidly.In order to measure lateral vibration of diamond saw blades,the lateral vibration problems at different speed range is studied by using laser displacement sensor.Through analyzing the curve between the speed and the amplitude,the variation rule between the lateral amplitude and the speed of saw blade is concluded.Resultsshow that amplitude of saw blade will increase with the increase of saw blade revolution and remains small in working revolving range.When revolution of saw blade is out of its working range,the amplitude will increase quickly.As with the saw blades with inner diameter of 100 mm,at revolution of 300 r/min,amplitude of blades with outer diameter(OD)2300 mm is 3.5 times as much as that of blades with OD 800 mm,and amplitude of blades with OD 3600 mm is 7 times as much as that of OD 800 mm blades.

Study on the wheel performance in high feed rate dry grinding rail material

XIE Guizhi, DONG Jiong, SHANG Zhentao, MIAO Tianying, JIN Tan

2016, 36(5): 64-68. doi: 10.13394/j.cnki.jgszz.2016.5.0013

Abstract(299)

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Rail grinding is the main technology to maintain the rail.Compared with normal grinding,rail grinding requires special performance on the grinding wheel.Based on the working condition of rail grinding vehicle,we set a group of parameters and test different grinding wheels to select one to meet the requirements.Research results show that resin bond mixed corundum wheel has good durability and slight adhesions on the wheel surface;high porosity vitrified bond corundum wheel has good comprehensive performance of efficiency and durability;vitrified bond microcrystalline corundum wheel has good self-sharpening performance,high efficiency but poor wear resistance.

Study on three-dimensional ultrasonic-aided grinding force

MA Xinyi

2016, 36(5): 69-74,78. doi: 10.13394/j.cnki.jgszz.2016.5.0014

Abstract(311)

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Abstract:
Study on three-dimensional ultrasonic assisted grinding force has been an empty field in ultrasonic machining area.The three-dimensional ultrasonic assisted grinding force is analyzed by using the macro-mechanics theory,and its mathematics model is established.The grinding force variations at different grinding parameters are evaluated.Verification experiment is conducted.It is found that under certain conditions,the three-dimensional ultrasonic assisted grinding force is almost 20% less than that of two-dimensional ultrasonic assisted grinding.The results also show that the grinding force decreases with the increase of wheel speed,and decreases significantly when wheel speed is more than 3000 r/min,while it increases with the increase of working feed speed and grinding depth,which has good compatibility with the theoretic analysis.

Bending strength of porous metal-bond diamond wheel segment

BAI Yongming, SHANG Jiaming

2016, 36(5): 75-78. doi: 10.13394/j.cnki.jgszz.2016.5.0015

Abstract(350)

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Abstract:
To balance the intensity and porosity of porous metal-bond,different mass fractions of pore formers and brazing fillers,as well as diamonds with different sizes and contents,are made into metalbond segements to test their bending strength.The results show that pore formers will dent the bending strength while brazing fillers consolidate the strength.As with the diamonds,it is found that segments with finer diamonds are difficult to break up.In conclusion,adjusting the ratio of raw materials would satisfy requirements on intensity with optimized porosity.

Research progress on binderless PCD and PCBN materials

ZHANG Taiquan

2016, 36(5): 79-83. doi: 10.13394/j.cnki.jgszz.2016.5.0016

Abstract(339)

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Abstract:
The preparation method,sintering mechanisms,methods for improving their sintering behavior,and their properties for binderless polycrystalline cubic boron nitride(PCBN)and polycrystalline diamond(PCD)materials have been summarized and discussed.The dense binderless PCD and PCBN materials can be successfully sintered at the pressure and temperature of above 7 GPa and 1800℃,but the high-pressure & high-temperature(HPHT)sintering condition and mechanisms of PCD and PCBN will be strongly affected by the different start powers and micro catalyst or dopant.The physical vapor deposition(PVD)and chemical vapor deposition(CVD)are promising methods for preparing binderless PCD material because of the severe sintering condition for HPHT method,but many technical problems must be solved while using PVD and CVD to prepare binderless PCBN material.The binderless PCD and PCBN materials have excellent high temperature properties,especially that the properties of PCD and PCBN with nano-size grains or substructures are higher than those of single crystal.

2016 Vol. 36, No. 5

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