金刚石与磨料磨具工程

Research progress of remanufacturing technology

LIU Wenhao, CHEN Yan, ZHOU Rui, XU Liang, HAN Bing

2021, 41(4): 1-7. doi: 10.13394/j.cnki.jgszz.2021.4.0001

Abstract(484)

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Abstract:
Remanufacturing technology is the core step in the production of remanufactured products. It is of great significance to ensure the quality of remanufactured products and reduce production costs. In this paper, the development and application status of remanufacturing technology are summarized. According to the damage forms of parts, remanufacturing technology is divided into surface failure oriented remanufacturing technology and structural damage oriented remanufacturing technology. A variety of typical remanufacturing technologies are classified and listed. Their processing principles are introduced, and the application in remanufacturing parts is illustrated and reviewed. Finally, the existing problems of remanufacturing technology are summarized, and the development trend of remanufacturing technology in the future is prospected.

Application and development trend of aero-engine blade remanufacturing technology

LI Wenhui, WEN Xuejie, LI Xiuhong, YANG Shengqiang

2021, 41(4): 8-18. doi: 10.13394/j.cnki.jgszz.2021.4.0002

Abstract(752)

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Abstract:
The typical aero-engine defects such as damage and attachment defects, the application of additive remanufacturing and subtractive remanufacturing in the field of aero-engine blade remanufacturing and theirs effects are studied in this review. Taking the remanufacturing effect and cost of blades as evaluation indexing, the principles, advantages and disadvantages of additive remanufacturing technologies such as laser cladding and welding, and subtractive remanufacturing technologies such as water-based liquid cleaning and mechanical and physical methods are summarized, and the development trend of aero-engine blade remanufacturing is expounded.

Reviews on high energy fluid jet cleaning technologies with emphasis on applications in remanufacturing

LI Bo, ZHENG Wenguang, HUANG Jun, GAO Hang, WANG Xuanping

2021, 41(4): 19-24. doi: 10.13394/j.cnki.jgszz.2021.4.0003

Abstract(495)

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Abstract:
Remanufacturing cleaning is an extremely important part in the remanufacturing process. With the expansion of remanufacturing to the field of high-end equipments and pursuing the goal of green manufacturing, high requirements for remanufacturing cleaning have been put forwards, such as low pollution emissions, environmental friendliness and in-place cleaning without residue. The high energy beam jet cleaning methods represented by high-pressure waterjet, wet ice blasting, and dry ice blasting have the characteristics of low foreign objects, low pollution emission and low processing damages, meeting the requirements of green remanufacturing cleaning. This article will review the latest technological progress of these three typical high-energy beam jet cleaning technologies in terms of jet cleaning mechanism, cleaning key technology processes, and typical application scenarios.

Preparation and thermal conductivity of vertically aligned graphene nanodiamonds laminated composites

YANG Chenguang, CHENG Xiaozhe, MU Yunchao, LIANG Baoyan, XU Yan

2021, 41(4): 25-30. doi: 10.13394/j.cnki.jgszz.2021.4.0004

Abstract(416)

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Vertically aligned graphene (VAG)/nanodiamonds (NDs) laminated composites were prepared by a series of treatments, including electrochemical exfoliation, adsorption, vacuum filtration and cold pression to study the influence of the mass percentage of NDs (0, 0.6%, 1.0%, 4.0%, 7.0%, 10.0% and 20.0%) on the thermal conductivity of the composites. The phase composition, the surface groups, the microstructure of composites were analyzed by XRD, Raman spectroscopy, FT-IR spectrometer, HRTEM and FE-SEM. The results show that the as-produced composites have a vertically aligned layer structure, and that the thermal conductivity of composites with 0.6% NDs reaches a maximum of 5.911 W/(m·K), which is 53.6% higher than that of graphene without NDs.

Properties of graphene/nano diamond composite electrode

ZHANG Jinhui, LI Jing, YU Jianyuan

2021, 41(4): 31-35. doi: 10.13394/j.cnki.jgszz.2021.4.0005

Abstract(471)

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Abstract:
Composite electrode of graphitized nano diamond (GND) and graphene was prepared to satisfy the requirements of super capacitor on higher energy density, higher power density and longer service life. GND was prepared by vacuum heat treating nano diamond (ND). Graphene/GND composite electrodes with different mass ratios were prepared by ultrasonic mixing method. The electrochemical performance of the electrodes was tested and their structures were analyzed. Resluts show that when the mass ratio is 4∶1, the prepared grahpene/GND composite electrode exhibited a good characteristic of double layer capacitor, whose voltammetric curve is almost rectangular and the shape remains nearly stable as scanning speed changes. When the scanning speed is 2 mV/s and the solution is 0.5 mol/L K₂SO₄, the electrode has a high specific capacitance of 103.3 F/g which decays no more than 0.95% after 1000 scanning cycles, showing excellent cycling stability. TEM result indicates that graphene layers are formed on the surface of nano diamonds after heat treatment and that the surface of graphene is restricted by the diamond structure. The graphene layer spacing gradually increases from the inside to the outside and improves the conductivity of the electrode. The SEM analysis concludes that GND is uniformly adhered to the surface of the graphene, forming blocks between graphene sheets and preventing messy graphene stack, which is good for the diffusion of electrolyte and increases the specific capacitance of composite material and its electrochemical performance.

Design and application of linear pressure relief mechanism in the synthesis process of cubic press

WANG Benliang, XIONG Shasha, FENG Xiaopeng, LIU Minggang, YUE Haijiao, HUA Shujie

2021, 41(4): 36-44. doi: 10.13394/j.cnki.jgszz.2021.4.0006

Abstract(383)

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Abstract:
To solve the problems of instability and slow speed of ultra-high pressure relief in the synthesis process of cubic press, the pressure relief mechanism is designed and optimized automatically and linearly. Based on the hydraulic control theory, the working model, the control model and the linear pressure relief model of the cubic press are established by using AMESim software. Four kinds of different pressure relief process curves are compiled. Based on the classical PID(proportion integral differential) control theory, the linear pressure relief model is simulated and calculated. Taking the half cone angle of the valve core and the diameter of the throttle orifice of the valve seat as variables, the linear pressure relief scheme meeting the process requirements is obtained. The actual test of the designed linear pressure relief mechanism shows that the absolute value of the pressure deviation between the actual pressure curve and the set pressure curve is less than or eaqual to 0.01 MPa, which meets the expected design requirements.

Microstructure and properties of diamond edging wheel made after adding Zn powder to iron-based matrix

SUN Weiyun, SUN Changhong, KANG Jie, YU Qi, DING Ziyang, LIU Shengxin

2021, 41(4): 45-52. doi: 10.13394/j.cnki.jgszz.2021.4.0007

Abstract(304)

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Abstract:
The effects of adding Zn powder, different mass fractions of which were 0, 0.7%, 2.1%, 3.5% and 4.9%, on the performances of the iron-based matrix of the diamond edging wheel were studied, namely the hot-pressed sintering structures, the phase compositions and the mechanical properties. On this basis, the properties of three kinds of diamond segments made by adding 0, 2.1%, 3.5% mass fraction of Zn powder and the diamond with a concentration of 24% in iron-based matrix, and the grinding performances of the corresponding three kinds of diamond edging wheels were studied. The results show that with the same sintering process, the area and the morphology of white, dark gray and gray structures in the iron-based matrix with and without Zn powder are obviously changed. The addition of Zn powder with mass fraction of 2.1% is helpful to the diffusion of some substances in the matrix, and the new phase Cu_0.61Zn_0.39 appears in addition to the phases of γ-Fe, (Cu, Sn), and (γ-Fe,Ni), Cu₄₁Sn₁₁ solid solutions, as well as Fe₄Cu₃ and Ni₄Sn intermetallic compounds. With the increase of Zn powder mass fraction, the relative density, the hardness and the wear of the iron-based matrix decrease, but the decline are not obvious. The bending strength of the iron-based matrix increases first and then decreases compared with that without Zn powder, and increases by 16.1% when the mass fraction of Zn powder is 2.1%, reaching the maximum value of 983.2 MPa. However, if the mass fraction of Zn powder is too high, the loss of material will appear when the matrix is hot pressed. After adding diamond to the iron-based matrix with or without Zn powder, the bending strengths of the fabricated segments decrease compared with that without diamond, but the decrease of the matrix with Zn powder are small and the holding force coefficients are larger, which indirectly indicate that the holding forces of the matrix to diamond are higher. When the diamond edging wheel made of iron-based matrix with 2.1% mass fraction of Zn powder is used to grind the edge of infiltrated ceramic brick, compared with the edging wheel made of no Zn powder and 3.5% mass fraction of Zn powder, its sharpness is moderate and its service life is the longest.

Effect of bond strength and different coatings on protrusion height of diamond tools

ZHU Zhendong, ZHANG Zuodong, LI Xiaolong, XIAO Changjiang, LI Zhengxin

2021, 41(4): 53-57. doi: 10.13394/j.cnki.jgszz.2021.4.0008

Abstract(387)

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The effects of uncoated diamond, Ti-coated and Ni-coated diamond with different bond strength on the protrusion height of diamond tool was studied through L₉(3⁴) orthogonal experiments. The SEM 3D reconstruction method was used to measure the protrusion height of diamond particles. The protrusion height of different diamonds particles were compared and analyzed. The results show that the protrusion height of diamond particles can be measured conveniently and quickly by using SEM 3D reconstruction method, the protrusion height is 221.26~321.68 μm; and the coating on the diamond surface and bond strength of diamond bits have both apparent effect on the protrusion height of diamonds particles. Moreover, the protrusion height of Ti-coated diamond is higher than that of Ni-coated diamond, and both of them are larger than that of uncoated diamond.

Experimental research on design and performance of curved grinding wheels with orderly arrangement of abrasive grains

LI Ruihao, SHI Guanghui, HUANG Hui

2021, 41(4): 58-63. doi: 10.13394/j.cnki.jgszz.2021.4.0009

Abstract(464)

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A method to design orderly arranged grains on the surface of curved grinding wheels is proposed. Two types of curved grinding wheels with orderly and disordered arrangement of grinding grains are prepared. The grinding experiments are carried out to compare the performance of curved wheels from grinding force, grinding wheel wear and shape error of the workpiece. The results show that the grinding force of the curved grinding wheel with ordered grain arrangement is less than that of the curved grinding wheel with disordered grain arrangement during the whole grinding process. The abrasive wear consistency and shape accuracy of the machined workpiece of the curved grinding wheel with ordered grain arrangement are better than that of the curved grinding wheel with disordered grain arrangement during the whole grinding process. The orderly design of the abrasive grains on the surface of the curved grinding wheel can effectively improve the performance of the curved grinding wheel.

Comparative study on machining behavior of brazed CBN wheel and vitrified CBN wheel during grinding powder metallurgy superalloy

ZHANG Xi, LI Benkai, DING Wenfeng

2021, 41(4): 64-71. doi: 10.13394/j.cnki.jgszz.2021.4.0010

Abstract(441)

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Abstract:
The comparative grinding test of FGH96 powder metallurgy superalloy was carried out with brazed CBN wheel and ceramic CBN wheel. The grinding performance of CBN wheel was evaluated from the dimensions of grinding force and temperature, surface roughness and wheel wear.The results showed that the grinding force of brazed CBN wheel was close to or lower than that of ceramic CBN wheel, the grinding temperature of brazed CBN wheel was similar to that of ceramic CBN wheel at lower feed speed (≤360 mm/min), and the grinding temperature of ceramic CBN wheel was significantly higher than that of brazed CBN wheel at higher feed speed (≥ 540 mm/min). Under normal grinding conditions, the surface roughness of brazed CBN grinding wheel was lower than that of ceramic CBN grinding wheel, and the surface roughness R_a was lower than 0.800 μm, the average surface roughness R_a was 0.508 μm and 0.529 μm. Material adhesion and abrasion wear occurred in the abrasive grains on the working face of brazed CBN abrasive wheel, and the grinding surface appears material smeared. While for that of vitrified CBN abrasive wheel, in addition to wear, adhesion and grinding wheel blockage, the grinding surface was easy to form deep grooves due to grain breakage and falling off, which reduced the machined surface quality. Generally, the grinding performance of brazed CBN abrasive wheel on FGH96 was better than that of vitrified CBN abrasive wheel.

Study on creep-feed deep grinding of K444 nickel-based superalloy with corundum grinding wheel

LIU Shuang, LI Min, DING Wenfeng, XU Jiuhua

2021, 41(4): 72-81. doi: 10.13394/j.cnki.jgszz.2021.4.0011

Abstract(423)

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Abstract:
To evaluate the grindability of nickel-based superalloy K444, brown alumina and white alumina abrasive wheels were used in this work. The grinding force, specific grinding energy, tool wear, the ground surface morphology and roughness were compared and analyzed. The results showed that brown alumina abrasive wheel had smaller grinding force, lower ground surface roughness compared with white alumina abrasive wheel. The ground surface roughness R_aafter grinding with brown alumina abrasive wheel was 0.20~0.45 μm, it was easier for brown alumina abrasive wheel to obtain a smooth ground surface. The sensitivity analysis of superalloy surface roughness showed that these two kinds of alumina abrasive wheels were the most sensitive to the depth of cut a_p, followed by the workpiece speed v_w, and the least sensitive to the wheel speed v_s. The wear of brown alumina abrasive wheel was lower than white alumina abrasive wheel. When the material removal rate R_MRR was between 0.3 mm³/(mm·s) and 1.0 mm³/(mm·s), the wear ratio of the two grinding wheels was between 1.36 and 1.40.

Two-objective process optimization for grinding of outer ring of silicon nitride ceramic bearing

XIE Tianshu

2021, 41(4): 82-91. doi: 10.13394/j.cnki.jgszz.2021.4.0012

Abstract(383)

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Abstract:
The machining quality of ceramic bearing rings plays an important role on the rotation accuracy and service performance of the bearing. Firstly, based on a large number of cylindrical grinding experiments, the unitary model of surface roughness with respect to process parameters and the unitary model of raceway roundness with respect to process parameters were established by the least square method. Secondly, on the basis of the unary model, the particle swarm optimization(PSO) algorithm was used to establish a multi-element model of surface roughness with respect to process parameters and a multi-element model of raceway roundness with respect to process parameters. Finally, the surface roughness and raceway roundness are optimized by PSO algorithm. So as to explore the optimal processing parameters of bearing outer ring. The results show that the relative error between the predicted value of the multiple composite model of the surface roughness with respect to the process parameters and the actual processing value is between 5.83% and 8.99%. The relative error between the predicted value of the multivariate composite model of the raceway roundness with respect to the process parameters and the actual processing value is between 4.62% and 8.01%. The process parameters obtained by the dual objective function optimization are the grinding wheel speed of 56.0 m/s, the feed rate of 0.012 mm/min, and the workpiece rotation speed of 215 r/min. Research shows that the multivariate model can predict the actual processing conditions more accurately. The roughness and roundness values under the optimal process parameters are 0.130 μm and 2.20 μm, respectively. Compared with other parameters, it can simultaneously ensure that the roughness and roundness are small.

Study on material removal mechanism of 6H-SiC single crystal wafer based on different nano-scratch order

GAO Wei, ZHANG Yinxia, HUANG Pengju

2021, 41(4): 92-97. doi: 10.13394/j.cnki.jgszz.2021.4.0013

Abstract(437)

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Abstract:
The (0001) surface of 6H-SiC single crystal were scratched with different intervals and different orders by micro-nano mechanical test system. The cross section profile curve of the scratch, the scratch depth, the friction force and the surface morphology on the wafer surface were analyzed by friction sensor, super depth-of-field microscope system and 3D topography instrument. The material removal process under different intervals and different orders in the process of single crystal wafer scratching were studied. The results show that when the static load is 100 mN, the cross section profile and the average friction force of the single crystal surface are affected by different scratch intervals. With the increase of scratch interval, the depth difference between two scratches decreases gradually, and the average friction of scratch 2 gradually decreases and approches that of scratch 1. When the scratch interval is 14 μm, the maximum scratch depth is -183.4 nm and the average friction force is 18.8 mN. The scratch order has a significant effect on the surface morphology and the material removal. When the static load is 90 mN, the scratch interval is 6 μm and 8 μm, the surface material accumulation of non-sequential scratche is less, the wafer surface roughness value is lower, and its surface quality is better. When the scratch interval is 6 μm, the material on the end surface of sequential-scratches is seriously broken under uniform dynamic load of 0~180 mN, while non-sequential scratches can reduce the crack degree of wafer scratches to a certain extent. The maximum friction force in sequential-scratches is 76.8 mN, which is greater than 63.3 mN in non-sequential scratches. Non-sequential scratches are more helpful to realize the plastic processing of SiC wafer and improve its surface processing quality.

Test and analysis of key parameters of phenolic resin for stainless steel grinding belt

XING Bo, ZHAO Jinzhui, SONG Yunyun, FENG Keming, CHEN Xuebin, REN Guanqing, FENG Bingqiang, AN Kunhua

2021, 41(4): 98-103. doi: 10.13394/j.cnki.jgszz.2021.4.0014

Abstract(413)

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To solve the problem that the basic physical and chemical indexes of phenolic resin for stainless steel grinding belt was difficult to fully characterize the grinding performance of the belt, four phenolic resins with the same basic parameters were selected as the research objects. The thermogravimetric(TG) and the impact strength of the phenolic resin were analyzed, the peel strengths and the grinding performances of four belts prepared with four phenolic resins were tested under the same process conditions, the correlation between phenolic resins and abrasive belt grinding performances were explored . The results show that when the basic parameters such as solid content, viscosity, water solubility and pH value of phenolic resins are basically the same, the maximum values of the grinding ratio, the grinding efficiency and the workpiece surface roughness of the four abrasive belts differ by 31.8%, 27.2% and 27.6% respectively. The TG, the impact strength of phenolic resins and the peel strength of the belts made of phenolic resins are positively related to the grinding performance of the belts. The main failure modes of abrasive belts grinding stainless steel are abrasive wear, abrasive particles adhere to debris and debris seriously blocking the chip space.

2021 Vol. 41, No. 4

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