金刚石与磨料磨具工程

Research on grinding of biological tissue

WU Maozhong, WANG Chengyong, ZHENG Lijuan, CHEN Zhihua, LIU Zhihua

2022, 42(2): 137-149. doi: 10.13394/j.cnki.jgszz.2021.0123

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Grinding of biological tissue is essentially using fine abrasive grains to remove soft and hard tissues in a small amount and multiple times to ensure the precision and safety of the operation. However, as an energy-intensive processing method, grinding may produce excessive heat and force during processing, which will directly act on the human body, causing damages to surrounding tissues and affecting the effect of surgery. This paper introduces the research of consolidation abrasive processing of biological tissues such as bone tissue grinding, skin grinding, dental grinding and vascular calcification tissue grinding. In the end, main directions for further developing are put forward.

Design and function of cold trap in the process of preparing diamond films by DC arc plasma jet chemical vapor deposition

CHEN Liangxian, SHAO Siwu, LIU Peng, AN Kang, ZHENG Yuting, HUANG Yabo, BAI Mingjie, ZHANG Jianjun, LIU Jinlong, WEI Junjun, LI Chengming

2022, 42(2): 150-155. doi: 10.13394/j.cnki.jgszz.2021.0113

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Firstly, this experiment introduces the principle of the DC arc jet method, the design of the gas circulation system and its advantages and disadvantages. Secondly, the design of the cold trap system and its working principle are introduced in detail. Finally, Raman spectroscopy and Fourier transform infrared spectroscopy are used to compare the quality of the diamond films prepared before and after adding the cold trap system. The results show that the cold trap system can effectively filter the oil vapor in the circulating gas lines and avoid the incorporation of impurities in diamond films. After adding the cold trap system, the impurity in the diamond wafer is reduced, and the half width of the diamond Raman peak is reduced to 6.76 cm⁻¹, which is closed to Ib type single crystal diamond. In addition, the crystal quality and the optical transmittance of the free-standing diamond wafer is significantly improved, and the transmittance at the wavelength of 10.6 μm reaches 68.4%.

Preparation of polycrystalline diamond films by MPCVD at high plasma power density

HE Zhongwen, MA Zhibin

2022, 42(2): 156-161. doi: 10.13394/J.cnki.jgszz.2021.0121

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Through the self-made MPCVD dual-substrate platform equipment, the microwave power was 1 400 W and the pressure was medium to high, the plasma power density was 357.5～807.4 W/cm³, the substrate temperature was 850 ± 30 ℃, the volume fraction of CH₄ was 1.0%～1.5% and the deposition rate was 1～8 μm/h, the polycrystalline diamond film of different quality was deposited on the silicon substrate with a diameter of 11.5 mm. The hydrogen atoms and the C-containing groups in the plasma, the morphology and the quality of polycrystalline films were characterized by spectrometer, optical microscope and Raman spectrometer. The results show that with the increases of plasma power density, the strength of hydrogen atom group and active C-containing group in plasma ellipsoid increase, the growth rate and the purity of diamond film are greatly improved. When the air pressure is 21 kPa, the plasma power density is 807.4 W/cm³, the substrate temperature is 850 ± 30 ℃, the growth time is 150 h, the CH₄ volume fraction is 1.0% and the hydrogen flow rate is 200 mL/min, the growth rate of the diamond film reaches 5 μm/h, the thickness of the diamond film reaches 752.0 μm, the FWHM of the diamond Raman peak is 6.48 cm⁻¹, and the quality of the grown diamond film is good.

A review of preparing binderless PcBN at high temperature and high pressure

WANG Chuqi, KOU Zili

2022, 42(2): 162-168. doi: 10.13394/j.cnki.jgszz.2021.0409

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Polycrytalline cubic boron nitride, PcBN for short, has the advantages of large size, isotropy and no cleavage plane so that it is widely used. Commercial PcBNs are generally sintered with binders to reduce sintering conditions to pressures ranging from 5.5 to 7.7 GPa and temperatures of 1600 to 2300 K. However, binders reduce the performance of the product, Vickers hardness ranging from 22 to 45 GPa for example. Based on the fact that the material itself is the best binder, pure phase PcBNs were prepared by four different initial materials, the sintering behavior and the properties of which were introduced and evaluated. In conclusion, the pure phase PcBN material with good performance can be prepared by using cBN as the initial material and adopting related processes.

Research on Cr coating layer inhibiting oxidation of diamond in diamond/Al-borosilicate glass composites

ZHANG Xianghong, WANG Yanhui, ZANG Jianbing, ZHANG Jinhui

2022, 42(2): 169-173. doi: 10.13394/j.cnki.jgszz.2021.0924

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The inhibiting effect of Cr coating on diamond oxidation in diamond/Al-borosilicate glass composites was studied. Coated diamonds with different Cr layer thickness was sintered with Al-borosilicate glass at the same process. The samples were tested and observed for volume expansion rate, bending strength and section morphology. The single particle compressive strength of sintered diamonds and the composition at the interface were analyzed. Results show that Cr coatings could protect the diamond through both isolation and consumption of oxygen, which effectively inhibits the oxidation of diamonds. Meanwhile, the thickness of coating layer has significant influence on diamond oxidation. If the coating is too thin, it could not continuously protect the diamond during high temperature sintering. If the coating is too thick, there would be cracks and flake spalling on it due to the thermal stress mismatch, exposing the diamond to oxygen environment and failing to protect. For 140/170 diamond, the optimum coating thickness is 1.58 μm.

Effect of sodium dodecyl benzene sulfonate on vitrified bond and dispersion of diamond

LIU Yibo, KONG Shuaifei, LI Zhengxin, XU Qiang, CHEN Chunhui

2022, 42(2): 174-179. doi: 10.13394/j.cnki.jgszz.2021.0111

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Vitrified bonds and the mixed powders of diamond and vitrified bonds are prepared by sol-gel and corresponding bulk composites are fabricated. The effect of mass fraction of dispersant (sodium dodecyl benzene sulfonate) ranged from 0 to 4.02% on property of vitrified bond is studied, including composition phase of vitrified bond, refractoriness, bending strength and thermal expansion coefficient. The dispersibility of M2.5/5 diamond dispersed in the mixed powders is investigated. The result reveals that when the mass fraction of dispersant was 1.34%, refractoriness of 700 ℃, bending strength of 45 MPa and coefficient of thermal expansion of 4.3×10⁻⁶ ℃⁻¹ have no change compared with that without addition of dispersant. Besides, with the dispersant increasing from 1.34% to 4.02% the refractoriness of vitrified bond prepared by sol-gel technique decreases to 600 ℃ and bending strength decreases to 28 MPa. The thermal expansion coefficient of vitrified bond increases to 7.5×10⁻⁶ ℃⁻¹. The research demonstrates that the addition of 1.34% dispersant can realize uniform dispersion of M2.5/5 diamond powder in vitrified bond /diamond composites without causing change in properties of the composites.

Effect of iron-base amorphous powder on diamond tool matrix

LI Mingfeng, FANG Xiaohong, DUAN Longchen, TAN Songcheng

2022, 42(2): 180-185. doi: 10.13394/j.cnki.jgszz.2021.0115

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The Fe-based amorphous powders with different mass fractions of 0, 5%, 10% and 15% were added to the matrix of Fe-based prealloyed powder. After the matrix sample was made by hot pressing sintering, the Rockwell hardness, the flexural strength and the wear rate were tested. For the sample without powder, its Rockwell hardness, flexural strength and wear rate are 104.6 HRB, 610 MPa and 3.3 respectively. For the sample adding 10% amorphous powder, its Rockwell hardness and flexural strength increase to 107.7 HRB and 965 MPa, which are 3.0% and 58.2% higher than the corresponding values of the original matrix respectively. The wear rate decreases to 0.9, which is 72.7% lower than the corresponding value of the original matrix. For the sample adding 15% amorphous powder, its Rockwell hardness and flexural strength increase to 110.0 HRB and 790 MPa, which are 5.2% and 29.5% higher than the corresponding values of the original matrix respectively. The wear rate decreases to 0.6, which is 81.8% lower than the corresponding value of the original matrix. Therefore, the addition of Fe-based amorphous powder can significantly improve the mechanical properties and the wear resistance of matrix samples. In addition, the DSC and the XRD tests of Fe-based amorphous powder show that at 500~700 ℃, the Fe-based amorphous powder will produce the process of crystalline phase transformation. The B element is integrated into NiSi phase to convert into NiSiB phase, and the Si element is integrated into CrFe phase to form SiCrFe phase, which can improve the matrix structure and properties.

Surface morphology characterization of fixed abrasive lapping pad based on deep learning

HU Weidong, WANG Zhankui, Dong Yanhui, ZHANG Zhao, ZHU Yongwei

2022, 42(2): 186-192. doi: 10.13394/j.cnki.jgszz.2021.0096

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The surface morphology of fixed abrasive (FA) lapping pad is closely related to its processing performance. In order to understand the surface morphology of the FA lapping pad better, particularly diamonds, pores, and pits resulting from diamond falling off, a deep learning-based method for characterizing its surface morphology was proposed. First, the Leica DVM6 digital microscope and its supporting software were adopted to obtain the surface images of the FA lapping pad; then python3+OpenCV were chosen to preprocess the images, and the labeling software Labelme was used to label the images for subsequent training and testing data set; finally, the Mask R-CNN model was built using the deep learning framework Tensorflow. The results show that the Mask R-CNN model can effectively segment and recognize multiple targets in the surface image of a single fixed abrasive pad, and the average accuracy of the main evaluation indicators reaches 78.9%, reaching the mainstream level of image recognition.

Study on grinding force in grinding titanium alloy with diamond grinding wheel

FENG Ru

2022, 42(2): 193-200. doi: 10.13394/j.cnki.jgszz.2021.0120

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To solve the problems of low elastic modulus and large elastic deformation when grinding titanium alloy with diamond grinding wheel, the force of grinding wheel was analyzed theoretically. Based on the chip separation criterion and the material friction properties, the cutting force model of titanium alloy grinding was established, and the cutting force state of a single abrasive particle was simulated by finite element method. The grinding experiment of titanium alloy was designed to study the influences of process parameters on the grinding forces of grinding wheel. The results show that the grinding force decreases with the increase of grinding speed. When the feed rate and the grinding depth increase, the grinding forces increase. When the grinding process parameters are changed, the change trend of tangential and normal grinding forces of the grinding wheel is roughly the same, and the ratio of the tangential and the normal force is 0.29～0.37. The variation trend of the theoretical value of grinding force is basically consistent with the experimental value, and the average value of the relative error between the two is within 5%, which verifies the correctness of the theoretical model of grinding force.

Influence of grinding lubrication methods on surface integrity of nickel-based single crystal superalloy

SUN Yongjie, ZHU Tao, CAI Ming, ZHANG Yuxuan, FAN Chenrui, AN Zhixin

2022, 42(2): 201-207. doi: 10.13394/j.cnki.jgszz.2021.0114

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To improve the grinding surface quality of nickel-based single crystal superalloy DD5, the influence of three grinding methods (dry, conventional flood, minimal quantity lubrication) on their surface integrity was investigated using single factor experiment. The results show that under different cooling conditions, the grinding surface roughness of nickel-based single crystal superalloy DD5 is MQL, conventional flood and dry grinding from low to high. When the linear speed of the grinding wheel is small, the grinding surface quality is poor, and there are deep scratches and grooves; when the linear speed of the grinding wheel is large, the grinding surface quality is good, the grinding marks are small and evenly distributed. When the depth from the grinding surface is 5~15 μm, the subsurface microhardness of DD5 decreases sharply with the increase of depth. When the depth from the grinding surface is 20~150 μm, the subsurface microhardness of DD5 tends to balance and fluctuates around 540 HV.

Flatness prediction of single pendulum polishing based on microelement material removal model

LI Kaixuan, LI Jun, XIONG Guanghui, WU Cheng, YU Ningbin, GAO Xiujuan

2022, 42(2): 208-215. doi: 10.13394/j.cnki.jgszz.2021.0116

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A microelement material removal model was proposed to explore the influence of single pendulum parameters on the polishing flatness of workpiece. Based on the coupling of velocity and pressure distribution, the model could predict the polishing flatness. Starting from the material removal of single abrasive particle, the model of material removal height of each microelement on the workpiece surface in unit time was established. The velocity of workpiece relative to polishing pad and pressure distribution of workpiece surface was coupled and inserted into the model. According to the initial surface shape of workpiece, the height value of microelement was extracted, and the flatness of the workpiece after polishing was calculated combined with the thickness of microelement material removal. Experiments were carried out to validate the flatness prediction method. The results show that the change trend of the surface shape after simulated polishing is same as actual polishing, and the absolute deviation of flatness PV₂₀ is less than 12.0%. The flatness prediction is reliable.

Optimization of process parameters for finishing the bottom surface of inner groove by magnetic grinding

CHEN Fayu, SUN Yuli, WANG Liaoyuan, ZHANG Peng, SHENG Yi, NISHIKAWA Naohiro

2022, 42(2): 216-222. doi: 10.13394/j.cnki.jgszz.2021.0122

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To improve the efficiency and effect of magnetic grinding the bottom surface of inner groove and seek a solution of finishing inner groove of the special-shaped waveguide, the orthogonal test was used to investigate the effect of three major process parameters, namely steel grit size, process gap and magnetic pole rotating speed, on the surface roughness reduction rate ΔR_a. Meanwhile, the process parameters were analyzed and optimized by the range analysis method and the variance analysis method. The best process parameters were confirmed: steel ball diameter of 1.0 mm, process gap of 1 mm, and magnetic pole rotation speed of 800 r/min. It demonstrated that after 30 minutes of processing, many protrusions on the surface were removed and the surface morphology was improved. The roughness value R_a was reduced from the initial 11.059 μm to 1.513 μm with the maximum reduction of 86.3%, significantly improving the surface quality.

Effect of Fe₃O₄ characteristics on properties of solid-phase Fenton reaction lapping pellets for single-crystal SiC

LU Jiabin, CAO Jiyang, DENG Jiayun, YAN Qiusheng, HU Da

2022, 42(2): 223-232. doi: 10.13394/j.cnki.jgszz.2022.0008

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To improve the lapping quality and processing efficiency of single-crystal SiC, solid-state Fenton reaction lapping pellets were prepared. Effects of characteristics of Fe₃O₄ (particle size and mass fraction) solid-phase catalyst on hardness, flexural strength, porosity, catalytic performance, and lapping performance of single-crystal SiC were studied. The results show that with the increase of Fe₃O₄ particle size, the hardness and flexural strength decrease, porosity increases, catalytic performance decreases, the material removal rate M_MRRdecreases from 43.12 nm/min to 36.82 nm/min, and the surface roughness R_aincreases from 1.06 nm to 3.72 nm. As the Fe₃O₄ mass fraction increases, the hardness and flexural strength of the lapping pellets decrease, and the porosity and catalytic performance increase. The M_MRR decreases from 40.14 nm/min to 33.51 nm/min, the surface roughness R_a is 3.25 nm, 1.75 nm and 1.88 nm, respectively.

On-line discrimination of radial runout state during diamond roller trimming

FU Tingbin, ZHU Zhenwei, ZHANG Rui, ZHAO Huadong

2022, 42(2): 233-239. doi: 10.13394/j.cnki.jgszz.2021.0119

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The performance of diamond roller when dressing grinding wheel was affected by its radial runout, but the intelligent degree of judging its radial runout state was low. Therefore, an on-line detection method based on wavelet decomposition and SVM was proposed for the grinding acoustic emission signal of radial runout under the trimming state of diamond roller. The grinding acoustic emission signal was transformed and decomposed by wavelet transform, and the three characteristic parameters of wavelet decomposition coefficients were extracted, which were effective value, variance value and energy spectrum coefficient. The results show that the accuracies of combining the three feature parameters into SVM for state recognition are more than 96.0%. When the three characteristic parameters are input at the same time, the accuracy is the highest, reaching 98.3%. The detection method has practical application value.

Analysis and optimization of traveling wave resonance of diamond circular saw blade

ZHAO Lei, ZHANG Dechen, YAN Chunbao, LEI Zhongxing, CHENG Libin

2022, 42(2): 240-247. doi: 10.13394/j.cnki.jgszz.2021.0112

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To solve the resonance and the noise problems of diamond circular saw blades during operation, the workbench software was used to analyze the traveling wave resonance and the static force of the idling circular saw blade with the diameter of 600 mm, and the effects of openings and interlayers in the circular saw blade matrix on its traveling wave resonance were studied. The results show that the reasonable openings in the matrix of circular saw blade can avoid traveling wave resonance, and the circular saw blade with raindrop holes has the best vibration reduction effect, the maximum value of δ is 4.36%, which is much larger than 0.09% and 0.91% of non-perforated and circular streamlined holes. The interlayer of circular saw blade with raindrop holes is further optimized, its δ value is 7.58%, which is nearly twice that before the interlayer, and it is not easy to cause traveling wave resonance. At the same time, the deformation and stress of the optimized circular saw blade become larger, but far less than its allowable stress value, indicating that its strength and stiffness meet the service requirements and will not cause fatigue failure.

Design and simulation analysis of rust removal grinding block on inner wall of elbow at constant pressure

LI Dengchao, ZHANG Pingkuan, LI Shunshun

2022, 42(2): 248-254. doi: 10.13394/j.cnki.jgszz.2021.0118

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To remove the embroidery layer on the inner wall of the elbow before coating, three kinds of grinding blocks, namely Block A, Block B and Block C, were designed to act on the 100-mm-diameter elbow. The removal result of the embroidery layer on the inner wall of the elbow bend was analyzed by using the grinding block for rust removal simulation. Firstly, the sizes of three kinds of grinding blocks were obtained by theoretical calculation. The radius and the center angle of concave arc of the block were 65.130~74.556 mm and 6.97°~7.98°, while those of convex arc were 145.522~147.618 mm and 6.06°~6.15°. The abrasive material on the grinding block was white corundum. Then, Solidworks and Creo were used for modeling and imported into Abaqus for simulation analysis. In the simulation process, it is necessary to ensure that the pressure of the grinding block on the inner wall of the elbow bend is constant and equal. Results show that when the grinding on the inner wall of the elbow by the grinding block B is stable, the range of the concave-arc grinding depth is 0.045 0～0.053 0 mm, whose average value is 0.049 8 mm and arithmetic average deviation is 0.001 6 mm. The arithmetic mean deviation of convex arc grinding depth with 38% abrasive rate is 2.2 × 10⁻⁴ mm. After data analysis, grinding stability of Block B is better than that of other two grinding blocks. It can be concluded that the rust removal effect of Block B is the best.

Quick review of topic reports on the 16th China-Japan International Conference on Ultra-Precision Machining Process

2022, 42(2): 255-256.

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2022 Vol. 42, No. 2

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