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2023, Volume 43,  Issue 6

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Experimental study on chemical-assisted magnetic compound fluid polishing of TA1 pure titanium capillary tube
XUE Yufeng, ZHANG Wentao, WU Hanqiang, SUN Xu, ZHENG Yangke, WU Yongbo
2023, 43(6): 657-667. doi: 10.13394/j.cnki.jgszz.2023.0213
Abstract(135) HTML (51) PDF 3157KB(24)
Abstract:
It is important to precisely polish the inner surface of medical-grade TA1 pure titanium capillary tubes in order to reduce sample residue and enhance capillary pipetting precision, ultimately improving the accuracy and reliability of in vitro diagnostic equipment. To address the subpar inner surface quality of TA1 capillary tubes and the challenges associated with titanium material polishing, a novel chemically-assisted magnetic compound fluid polishing method was proposed. This method combines oxidation and mechanical removal to efficiently and precisely polish the inner surface of the tubes. Experimental studies were carried out to examine the effects of iron powder mass, hydrogen peroxide concentration and malic acid concentration on both the material removal rate and the inner surface roughness, with the aim of determining the optimal polishing parameters. The study involved the examination of surface morphology and elemental changes on the inner surface of capillary tubes both before and after polishing. This analysis aimed to assess the overall impact of the polishing technique on the inner surface of pure titanium capillary tubes. The results indicated that following a 90-minute polishing process under the specified conditions of 2 mg of iron powder, a hydrogen peroxide concentration of 7.2% and a malic acid concentration of 6%, the surface roughness of the TA1 capillary tube decreased from Ra 675 nm to Ra 75 nm. In the well-polished area devoid of initial dents, the surface roughness reached Ra 19.5 nm, with a material removal depth of up to 28 μm. Furthermore, the original surface scratches were effectively eliminated, both the depth and width of dents were significantly reduced, and no additional elements were introduced during the polishing process.
Statistics and analysis of China’s superhard industry in the first half of 2023
SUN Zhaoda, LI Zhihong, LI Lijuan, ZHANG Beibei, MA Ning
2023, 43(6): 668-671. doi: 10.13394/j.cnki.jgszz.2023.1005
Abstract(116) HTML (60) PDF 1426KB(29)
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The development of China’s superhard industry in the first half of 2023 is analyzed according to statistical data, as well as the import & export data of customs and the national macroeconomic indicators. It is found that the industry falls short of development expectations due to the structural adjustment of the manufacturing industry. The main indicators, including the total industrial output value, the sales revenue, the total profit and the export delivery, all in a negative growth, especially the total profit who decreases 39.5% year-on-year. Against the backdrop of relative weak global markets, the export destinations are increasingly concentrated due to the rapid development of emerging economies. For example, the markets in the Middle East and Russia hava shown higher vitality. It is suggested that the companies take active decisions and explore emerging markets for breakthroughs in products and vitality in development.
Surface defects in ultrasonic vibration assisted cutting of TiCp/TC4 with PCD tool
HUAN Haixiang, LUO Tao, XU Wenqiang, ZHU Chilei
2023, 43(6): 672-683. doi: 10.13394/j.cnki.jgszz.2023.0154
Abstract(183) HTML (74) PDF 10016KB(13)
Abstract:
To investigate the microscopic influence of ultrasonic vibration on the surface flaws of particle-reinforced titanium matrix composites TiCp/TC4 during cutting with ultrasonic vibration of PCD tools. A two-dimensional cutting microscopic non-homogeneous model for TiCp/TC4 was established using ABAQUS/Explicit finite element software, and different volume fractions of the multi-particle cutting simulation were performed to analyze the changing rule of cutting speed on cutting temperature using a combination of simulation and experimental methods, to elaborate the particle force crushing process of PTMCs during the cutting process, and to discuss the defect manifestation. The results show that ultrasonic vibration cutting, the cutting temperature is always lower, the surface defects are mostly particle cut off and particle protrusion, and ultrasonic vibration can effectively block the stress between the particle and the substrate continues to transfer, so that the stress is prioritized in the transmission between the particles, reducing substrate deformation, prompting the particles to break first, and improving the surface. The experimental results were validated to be consistent with the simulation results.
Study on lapping performance of agglomerated diamond abrasive
FANG Weisong, YAN Qiusheng, PAN Jisheng, LU Jiabin, CHEN Haiyang
2023, 43(6): 684-692. doi: 10.13394/j.cnki.jgszz.2022.0218
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Abstract:
A new lapping process is proposed for high efficiency and low surface roughness lapping of hard-brittle materials such as sapphire, which sinters single crystal diamond abrasive (average grain size 3 μm) with vitrified bond into agglomerated abrasives (average grain size 30 μm). The lapping performance of agglomerate abrasives was studied through machining sapphire substrate with comparison to those using 3 μm or 30 μm single crystal diamond abrasive. The results show that the agglomerated has higher material removal rate (MRR), which is 1.127 μm/min after 15 min machining under the same conditions. It is also found that the agglomerated abrasive performs stable during the machining, the MRR of which is 0.483 μm/min after 120 min lapping, decreasing 57.14% from that after 15 min lapping, while the MRR of 3 μm single crystal diamond decreases for 78.02%. The roughness of surfaces lapped by agglomerated abrasive or 3 μm single crystal diamond is similar, which is Ra 9.45 nm or Ra 8.75 nm, respectively. Both are far lower than the Ra 246 nm of 30 μm single crystal diamond abrasive. The mechanism that agglomerated abrasive can achieve low lapping surface roughness and high MRR can be summarized as follows: it has the characteristics of multiple cutting edges which effectively improve the contacts between abrasive and sapphire surface and enhance the MRR; at the same time, it has the ability of self-sharpening, which ensures that the blunt abrasive falls off during the lapping and that new abrasives are put into process, thus ensuring the stability of the process.
Experiment on surface integrity of soda-lime glass with single abrasive particle variable cutting depth scratching
CHEN Mengkai, TENG Qi
2023, 43(6): 693-697. doi: 10.13394/j.cnki.jgszz.2022.0079
Abstract(98) HTML (45) PDF 2425KB(13)
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Due to the high hardness, the high brittleness and other characteristics, the hard and brittle materials represented by glass were prone to damage such as pits, brittle breakage and surface/subsurface cracks during processing, which seriously affected the performance and surface integrity. The effect of velocity variation on the crack formation and propagation and surface integrity of sodium-calcium glass during single abrasive grinding was studied. The results show that the single grain variable cutting depth scratching experiment can realize three stages of scratching, ploughing and cutting in the grinding process, and with the increase of scratching speed, the critical depth of brittle-plastic transformation of sodium-calcium glass increases, and the scratch morphology and scratch edge smoothness increase.
Depositing diamond film on high Co content cemented carbide using CrSiN film as an interlayer
PAN Qiuli, ZHANG Rongliang
2023, 43(6): 698-703. doi: 10.13394/j.cnki.jgszz.2023.0004
Abstract(164) HTML (50) PDF 3074KB(13)
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In order to solve the problem that it is difficult to grow diamond films with high binding force on the surface of high cobalt cemented carbide, the Cr/CrSiN film was used as the transition layer, and the nanocrystalline diamond films (NCD), the submicrocrystalline diamond films (SMCD) and the microcrystalline diamond films (MCD) were deposited on the cemented carbide by hot filament chemical vapor deposition method, and their binding forces were studied. The results show that the Cr/CrSiN transition layer can be used to deposit diamond films with excellent bonding strength on the surface of high cobalt cemented carbide. NCD has the best binding force, followed by SMCD, and MCD has the worst binding force. When the grain size of the diamond film increases, the bonding forces of the diamond film weaken due to the poor toughness of the diamond films and severe carbonization of the transition layer. When the crystal size of the diamond film increases, the binding force of the diamond film becomes weak due to the poor toughness of the diamond film and serious carbonization of the transition layer.
Prediction of subsurface microcrack depth of brittle materials based on co-training SVR
REN Chuang, SHENG Xin, NIU Fengli, ZHU Yongwei
2023, 43(6): 704-711. doi: 10.13394/j.cnki.jgszz.2023.0006
Abstract(141) HTML (55) PDF 2096KB(15)
Abstract:
In order to overcome the dilemma of insufficient effective sample number for subsurface microcrack depth in the lapping of brittle materials with fixed abrasives and achieve accurate prediction, a co-training SVR was used to construct the prediction model. The effects of different labeled training set partitioning methods on the mean square error of the test set were compared. Then the predictive performance of supervised learning PSO-SVR model was compared with that of the model. Finally, brittle materials such as microcrystalline glass and calcium fluoride, which were not included in the labeled training set, were taken as processing objects for lapping and angular polishing experiments to examine crack depth values. The examined subsurface microcrack depths of four groups were compared with the predicted values of the co-training SVR model. The results show that the co-training SVR model under the separate partitioning method has a smaller mean square error. Compared with the PSO-SVR model, the mean square error and the mean absolute percentage error of the co-training SVR model are reduced by 9% and 17%, respectively. The prediction error of the model for the four groups of verification experiments is between 1.2% and 13.8%. The above results show that the co-training SVR model can predict the subsurface microcrack depth accurately when lapping brittle materials with fixed abrasives.
Process parameters optimization of zirconia ceramics polishing with magnetic compound fluid slurry
ZHANG Zelin, ZHOU Hongming, FENG Ming, ZHANG Xianglei, CHEN Zhuojie
2023, 43(6): 712-719. doi: 10.13394/j.cnki.jgszz.2023.0003
Abstract(136) HTML (54) PDF 3169KB(10)
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In order to improve the surface quality of zirconia ceramic workpieces, the magnetic compound fluid polishing tool were utilized. This was done to lessen the material's surface roughness, minimize surface and subsurface damage. With a focus on the effects of magnet speed, processing gap, and abrasive particle size in the polishing fluid on surface roughness and material removal rate, a 3-factor, 3-level orthogonal test was created using Taguchi's method. The weights of each factor on the two evaluation indices were then analyzed using ANOVA. The best process parameter combination for surface roughness was 300 r/min for the magnet speed, 0.5 mm for the processing gap, and 1.25 μm for the abrasive particle size; the best process parameter combination for material removal rate was 400 r/min for the magnet speed, 0.5 mm for the processing gap, and 2 μm for the abrasive particle size. With these processing parameters, the surface roughness can reach up to 4.5 nm, and the material removal rate can reach up to 0.117 μm/min. The optimization effect is significant. The polishing prediction model was developed using a BP neural network that has been genetic algorithm optimized. The prediction error was 3.948 4%.
Simulation and experiment of ultrasonic-assisted grinding process for natural diamond
PEI Leigang, SHI Guangfeng, CHEN Jiazeng, YAO Dong, YANG Yongming, LI Junye
2023, 43(6): 720-726. doi: 10.13394/j.cnki.jgszz.2023.0060
Abstract(113) HTML (47) PDF 2999KB(14)
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To improve the surface quality of natural diamond grinding, the ultrasonic vibration was introduced for composite grinding, and an inelastic collision theory model was established to calculate the amplitude of ultrasonic vibration. The effects of ultrasonic amplitude, grinding speed and grinding grain size on the material removal of natural diamond (100) crystal surface were studied, and the optimal process parameters were sought. The results show that the ultrasonic amplitude ranges from 3.1 to 8.7 μm in the direction of easy grinding of natural diamond (110) crystal surface and 2.9 to 9.1 μm in the direction of easy grinding of natural diamond (100) crystal surface. The optimal process combination parameters of natural diamond (100) crystal surface grinding obtained by orthogonal experiment are ultrasonic amplitude of 6.0 μm, grinding disk speed of 2 800 r/min, diamond grinding grain size code of M3/6. The surface roughness Ra of diamond (100) crystal surface after ultrasonic assisted grinding is 16.21 nm, which is 63.83% lower than that of traditional mechanical grinding. Ultrasonic assisted grinding of natural diamonds can achieve better surface quality than traditional mechanical grinding.
Simulation and experimental study of single-crystal silicon laser assisted cutting based on SPH method
HUANG Fenping, SHU Xiayun, XU Weijing, CHANG Xuefeng
2023, 43(6): 727-734. doi: 10.13394/j.cnki.jgszz.2023.0025
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Fine cracks are easy to occur in the processing of monocrystalline silicon, which affects the surface processing quality. Laser assisted machining (LAM) can soften the substitute machining area, effectively reduce the cutting force, extend the tool life and improve the surface quality. In this paper, a thermo mechanical coupled smooth particle model is established to simulate the laser assisted turning process of single crystal silicon. Under different temperature conditions, crack propagation damage and cutting stress are explored. The influence of speed and cutting depth on surface roughness. Finally, the accuracy of simulation results is verified by laser assisted cutting experiments. The results show that increasing the temperature is beneficial to the plastic cutting of monocrystalline silicon. With the increase of the cutting zone temperature, the tool stress gradually decreases. The tool stress at 300 ℃ is about 50% lower than that at room temperature, and the surface processing quality is significantly improved. At 600 ℃, the chip is a plastic flow sawtooth line, and the plasticity is greatly improved. During cutting, a smaller cutting depth shall be selected, the rotating speed shall be lower than 4 500 r/min, and the surface roughness Sa of monocrystalline silicon can be less than 1 nm.
Simulation optimization of physical field of diamond particles deposited by multi-piece substrates HFCVD system
YANG Haixia, FU Mingjiang, LUO Jian, ZHANG Tao
2023, 43(6): 735-742. doi: 10.13394/j.cnki.jgszz.2023.0031
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Hot filament CVD method, which is used to synthesize high efficiency and high quality superhard abrasives, has become a research hotspot. Based on a new multi-piece grid substrate, which can increase the single deposition yield of micro-powder, and FLUENT, the fluid simulation software, the traditional model is optimized with unchanged number of single outlet and stable total intake flow but the single inlet is split into five equally sized inlet. The number and the arrangement of inlets that affect the process uniformity are simulated. The physical field of gas in the HFCVD system is compared and analyzed. Results show that the four optimized models all perform improved uniformity of substrate temperature and flow rate, which is conducive to the uniform growth of diamond single crystal particles, but the effect of diamond deposition rate is not significant. Further analysis on the temperature field of the optimized model indicates that the temperature difference of the system is the lowest with five inlets located in the middle top and a single outlet in the middle bottom of the reaction chamber, which satisfies the condition of uniform growth of diamond single crystal particles on multi-piece silicon substrate. Finally, CVD single crystal diamond particles are deposited to verify the reliability of the simulation.
Effect of SiC content on properties of copper matrix composites
CAI Jianing, FAN Zimin, LE Chen, LI Xin, TANG Mingqiang, ZHAO Fang
2023, 43(6): 743-749. doi: 10.13394/j.cnki.jgszz.2022.0183
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SiC/Cu composites were prepared by hot-pressing powder metallurgy with Al and Mg elements, and the effect of SiC volume percentage on the properties of SiC/Cu composites was studied. X-ray diffraction, Archimedes drainage method, three-point bending method and scanning electron microscope were used to analyze the phase composition, relative density, mechanical properties and micro-morphology of the composite samples, and the thermal conductivity and thermal expansion coefficient were measured. The thermal expansion coefficient of the composite was predicted by ROM mixing law and Turner model. Experimental results show that AlCuMg phase is formed in the matrix of the sample, and the strength is greatly increased, and the mixed fracture is the main type of the sample. The SiC particles are uniformly dispersed in the matrix when the SiC content is low. The density, bending strength, thermal conductivity and thermal expansion coefficient of SiC/Cu composites are 98.81%, 478 MPa, 254.76 W/(m·K) and 11.84 × 10−6/K respectively when the SiC content is 35%. When the content of SiC increases, the agglomeration of SiC particles is serious, and the density, bending strength, thermal conductivity and thermal expansion coefficient of the composites decrease. Its hardness increases at first and then decreases, and reaches the maximum value of 110 HRB when the SiC content is 45%. The Turner model is the closest to the measured values of composites.
Study on the influence of grinding disc motion on the forming of silicon nitride ceramic balls
GE Ziqiang, LI Songhua, WU Yuhou, SUN Jian, TIAN Junxing, XIA Zhongxian
2023, 43(6): 750-759. doi: 10.13394/j.cnki.jgszz.2023.0012
Abstract(179) HTML (55) PDF 4149KB(9)
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In order to improve the processing accuracy of silicon nitride ceramic balls and to investigate the mechanism of forming ceramic balls by flexible support grinding method, a new cone-type flexible support grinding method with controlled deflection motion of grinding disc is proposed. Based on the new grinding method, a simulation model is established to deeply analyze the influence of the deflection motion of the grinding disc on the grinding trajectory and force state of the silicon nitride ceramic balls. Orthogonal experiments were conducted on a new cone-type flexible support grinding platform built to further analyze the effect of grinding disc motion characteristics on ball formation. Simulation and experimental results show that under the flexible support grinding method, As the increases of grinding disc deflection angle, the standard deviation of ball trajectory uniformity decreased from 43.58 to 35.49, the maximum contact force increased to 4 times the initial value, the average ball diameter variation increased from 1.466 μm to 2.382 μm, and the batch diameter variation increased from 4.98 μm to 10.27 μm. The lower grinding disc deflection motion is beneficial to optimize the grinding trajectory, but increases the unevenness of the ball force, which is not conducive to improving the average ball diameter variation and batch diameter variation of silicon nitride ceramic balls. In the actual process, the angle of deflection of the grinding disc must be controlled to within 0.02°.
Study on chip formation in grinding nickel-based single-crystal superalloy DD5
YU Guihua, ZHU Tao, CAI Ming, AN Zhixin, WANG Chengjing, LUO Shubao
2023, 43(6): 760-771. doi: 10.13394/j.cnki.jgszz.2022.0169
Abstract(81) HTML (30) PDF 5184KB(11)
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According to the significant anisotropy of nickel-based single-crystal superalloy, a three-dimensional single abrasive grinding model based on the Hill model was developed. In this work, the change in the actual grinding thickness (ag) of the abrasive is taken into account in establishing the model. In addition, a combination of theoretical research and experimental research is used. The surface morphology and chip morphology of DD5 were first studied. Then, the evolution of chip morphology and the change in grinding force were investigated. Finally, the influence of grinding speed (vs) on chip morphology and chip segmentation frequency (fc) was studied. The research shows that serrated chips can easily occur when machining DD5 within the range of grinding parameters. The grinding force increased steadily and was accompanied by inevitable periodic fluctuations corresponding to serrated chips. As the grinding speed increased, the abrasive could enter the cutting stage more quickly, and its critical chip thickness (acr) eventually decreased from 0.225 μm to 0.158 μm. The percentage of the cutting phase increased from 85% to 89.5%. However, the critical scratch thickness was not significantly influenced by the change in grinding speed. The grinding speed and thickness substantially influence the morphology and segmentation frequency of DD5 chips. Specifically, as the grinding speed continues to increase, the DD5 chip morphology changes from a densely stacked unit nodal shape with serrated subsections to a continuous type of serrated shape and finally develops into a strip-shaped chip. At different grinding speeds, the chip segmentation frequency of DD5 decreases with increasing grinding depth.
Particle action behavior on the tooth surface of straight cylindrical gears by spindle finishing
FAN Yu, LI Wenhui, YANG Shengqiang, LI Xiuhong, YANG Yingbo, FENG Lidong
2023, 43(6): 772-781. doi: 10.13394/j.cnki.jgszz.2023.0002
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The objective of this study is to explore the mechanism of action at the contact interface between gears and particles in spindle barrel finishing, using the Discrete Element Method (DEM) for simulation. The motion of the particles in the vicinity of the gear and the contact particles on the tooth surface is first described. Then the effects of gear embedment depth, gear and roller speed on relative particle motion velocity and tooth contact force are investigated. Finally, the simulation results are verified by experiments. The results show that the action of spindle barrel finishing on the gear tooth face is cyclical in nature. Contact force on the upper and lower tooth surfaces of the gear is not uniform, and the contact force on the upper tooth surface is 1.5 to 1.8 times that on the lower tooth surface. Increasing the gear embedment depth mainly affects the contact force between the particles and the tooth surface. A 75% increase in embedment depth leads to a 76% rise in tooth surface contact force. Similarly, increasing the gear and drum speed mainly affects the relative movement speed between particles and the tooth surface. A 150% increase in gear and drum speed results in a 148% increase in the relative movement speed of particles in contact with the tooth surface. Increasing the embedment depth of the gear can reduce the processing variability of the gear tooth surface along the axial direction. After increasing the embedment depth from 80 mm to 140 mm, the roughness of the upper and lower tooth surfaces along the axial direction decreases from 17% and 36% to 62% and 55%, respectively. However, the processing variability along the tooth profile direction does not change significantly by changing the speed and embedment depth.
Quick review of topic reports on 22nd Chinese Conference of Abrasive Technology
2023, 43(6): 782-783. doi: 10.13394/j.cnki.jgszz.2023.0241
Abstract(75) HTML (39) PDF 319KB(10)
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