金刚石与磨料磨具工程

Comparative experimental study on machining edge of carbide end milling cutter with different tool passivation methods

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0058

Abstract(49)

Abstract:
With the rapid development of manufacturing industry, the tool performance is more and more demanding in processing, and the cutting edge passivation technology is the key to improve the tool performance. In this study, a new tool passivation method, namely starch based abrasive flow passivation method, is proposed, which provides a new method for tool edge passivation. Single factor test method was used to passivate carbide end milling cutter by vertical rotation passivation method and starch based abrasive flow passivation method. The test results show that the radius of the cutting edge of the unpassivated tool is the smallest, and there are many defects, and the edge shape is sharp. The radius of cutting edge obtained by vertical rotating passivation method changes little, but the defect of cutting edge still exists, and the blade shape presents uneven blunt circular shape. After starch-based abrasive flow passivation, the edge radius changed the most, some edge defects were removed, and the edge shape showed a uniform blunt circular shape. Therefore, the starch-based abrasive flow passivation method can not only remove the surface defects of the cutting edge better, but also has higher passivation efficiency and the change rate of the cutting edge radius. Considering the needs of tool production, the starch-based abrasive flow passivation method can significantly improve tool performance, reduce tool wear and improve machining quality.

Study on Physicochemical Properties and Removal Mechanism of SiC Ceramics Processed by Femtosecond Laser

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0088

Abstract(36)

Abstract:
Ultrafast laser processing of hard and brittle materials can effectively suppress processing damage and obtain a balance of processing quality and efficiency. In this paper, a femtosecond laser was used to process silicon carbide ceramics at different energy densities and pulse numbers to investigate the effects of laser parameters on surface morphological features, chemical components and microporous quality, and to analyze the evolution of surface microstructure and material removal processes. The results show that the boiling and melting zones are formed on the surface of silicon carbide ceramics by single-pulse processing, and the threshold energies for the formation of characteristic zones are calculated to be 3.779 J/cm² and 0.86 J/cm², respectively; the removal process of silicon carbide ceramics is the result of photothermal and photochemical effects successively, and the mechanism of action in the central region with higher temperature is the evaporation of the material, while the low temperature region is the thermal decomposition of the material The microporous diameter and ablation depth increase with the increase of energy density and number of pulses. This study further improves the mechanism of femtosecond laser processing of silicon carbide ceramics from the perspective of material physiochemical property changes, and provides a theoretical reference for efficient and precise processing applications of silicon carbide ceramic parts.

Effect of boron concentration and gas pressure on the electrochemical oxidation performance changes of HFCVD diamond films on Ti substrates

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0071

Abstract(31)

Abstract:
The effects of boron concentration and deposition pressure on the microstructure and electrochemical oxidation performance of Ti/BDD electrodes during HFCVD growth were systematically investigated. The surface morphology, composition and electrochemical performance of the electrode were characterized by Scanning electron microscope (SEM), Raman spectroscopy, ultraviolet spectrophotometer, and electrochemical workstation. Tetracycline was used as a simulated pollutant to explore the electrochemical oxidation degradation performance of BDD electrodes prepared with different boron concentration and deposition pressure. With the increase of air pressure, the grain quality of the diamond decreases gradually, but the boron atom doping will improve the grain quality of the diamond. Under the condition of high boron concentration and low pressure, the boron atom concentration on the surface of diamond film is higher, and the electrode with high boron atom concentration has better electrochemical performance, higher degradation efficiency, and lower degradation energy consumption.

Simulation and experimental study on micro-cutting silicon carbide crystal with single grain diamond

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0158

Abstract(52)

Abstract:
In order to improve the brittle fracture and edge breakage of silicon carbide crystal in the micro-cutting process, a finite element simulation model of micro-cutting silicon carbide workpiece with diamond conical abrasive grain was established, and the selection range of micro-cutting depth and speed is determined through the pre-simulation model. Then the orthogonal experiment method is used to analyze the primary and secondary factors on the cutting force. Subsequently, the influence of single micro-cutting parameter on cutting effect is studied. Finally, with the help of Hertzian contact stress, the cutting force and quality of cutting edge were analyzed by scratching the silicon carbide crystal with a diamond tip. The maximum cutting depth is determined to be 1.5 μm by pre-simulation model. The cutting depth B is a significant factor affecting the main cutting force, cutting speed C and conical angle of diamond grain A are non-significant factors, and the optimal scheme of cutting parameters is B₁C₁A₂ (cutting depth 0.5 μm, cutting speed 76 m/s, conical angle of diamond grain 60°). It can improve the cutting stability by controlling the cutting depth, and appropriately improve the cutting speed can improve the cutting efficiency and ensure the cutting quality. The depth of pressing into the workpiece of diamond tip affects the friction coefficient, friction force and cutting force, and the 3D profiles of cutting edges are relatively clear, straight and clean.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0046

Abstract(33)

Abstract:

Effect of component design and optimization on the organization and properties of PcBN composites

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0090

Abstract(44)

Abstract:
　　The polycrystalline cubic boron nitride composites were prepared under high temperature and pressure conditions. The effects of bonding agent ratio and cBN particle size on the composition, microstructure, microhardness, density and abrasive ratios of PcBN composites were investigated by X-ray diffraction (XRD), field scanning electron microscopy (SEM) and energy spectroscopy (EDS). The experimental results showed that the PcBN composites performed better under the sintering conditions of 5.5 GPa, 1400 ℃, and 10 min holding time, with a hardness of up to 22.7 GPa and an abrasion ratio of 149.2 at TiN_0.3: AlN=7: 3. When the particle size combination of cBN in PcBN composites is (0.5~1) μm: (2~5) μm: (5~10) μm = 3: 5: 2, the packing density between particles reaches the highest and the performance is optimal.

Simulation and Experimental Study of Single-crystal Silicon Laser Assisted Cutting Based on SPH Method

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0025

Abstract(22)

Abstract:
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 4500r/min, and the surface roughness Sa of monocrystalline silicon can be less than 1nm.

Effect of Lapping Pressure on Surface quality of polycrystalline diamond （Shandong Institute of Scientific and Technical Information, Jinan , 250101,China ,SUN Guodong）

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0036

Abstract(48)

Abstract:
The diamond layer of polycrystalline diamond (PCD) composite was grinded by a diamond flat grinding disc at high speed. The change of the removal rate of polycrystalline diamond material and the surface quality (surface roughness, surface morphology) of the specimen were analyzed by changing the pressure during grinding. The results show that the increase of grinding pressure will improve the material removal rate of polycrystalline diamond, reduce the surface roughness, increase the surface smooth area, and reduce the pits and gap cracks.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0129

Abstract(27)

Abstract:
In order to reduce the difficulty of cuttings migration in horizontal wells, the problem of bit bagging. Improve the drilling efficiency and service life of PDC drill bit in the process of shale horizontal well drilling. The numerical simulation method and the low Reynolds number k-ԑ turbulence model are used to establish the bottom hole flow field model. The hydraulic structure of the PDC (polycrystalline diamond compact) bit is analyzed under the conditions of different drilling fluid displacement, PDC bit rotation speed and cuttings particle size. The results show that: with the increase of displacement, cuttings efficiency increases gradually. However, in the rotating condition, the mismatch between the drilling fluid displacement and the drill bit speed reduces the drilling fluid scour and cuttings migration efficiency. Appropriate displacement and rotational speed can effectively improve the cuttings migration efficiency and reduce the accumulation of cuttings at the bottom of the well. Under a certain bit rotation speed and drilling fluid displacement, the particle size of cuttings is directly proportional to the cuttings migration efficiency. The research results can provide reference for optimizing the design of PDC bit and drilling construction parameters.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0003

Abstract(34)

Abstract:

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0004

Abstract(44)

Abstract:

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0005

Abstract(29)

Abstract:
Achieving the separation between diamond films and substrate is the precondition and foundation to the application as a self-freestanding form. The separation techniques in widespread use currently, for metal substrate based on stress mechanism and silicon substrate using chemical corrosion process, are considered to be only suitable for the diamond thick films with enough strength. However, However, it is still difficult to achieve complete stripping of the diamond film that with small thickness and relatively low strength. In this paper, Ti, Si and glass carbon substrates were selected to prepare ultra-thin diamond films by microwave plasma chemical vapor deposition (MPCVD) with CH₄/H₂ as the reaction source. The overall morphology, surface morphology, composition and stress state of the prepared diamond films are analyzed by SEM and Raman. The results show that the diamond film grown only on glass carbon substrate can be automatically peeled off to form a complete self-supporting film, and the crystal surface of the film grain is clear, and the film thickness is only 10 μm; Raman spectra reveal that the thin films have strong sharp diamond characteristic peaks, and the calculated residual stress is the lowest. Combined with the surface changes of glass carbon substrate before and after deposition, and the internal structure characterization of self-supported diamond film, it is preliminatively inferred that one-step growth of ultra-thin diamond film and self-supported stripping can be achieved on glass carbon substrate. It is mainly attributed to the continuous etching effect of hydrogen plasma on the film-base interface during the growth process, which weakens the binding force and the low residual stress during the cooling process ensures the structural integrity of ultra-thin diamond film. This work is expected to provide an new effective technique for the one-step growth and stripping of ultra-thin self-supported CVD diamond films.

Prediction of subsurface damage for lapped brittle materials based on Co-training support vector regression

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0006

Abstract(35)

Abstract:
In order to overcome the dilemma of insufficient effective sample data for subsurface microcrack of brittle materials with fixed abrasives and achieve effective prediction of subsurface microcrack depth, a co-training support vector regression algorithm (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 test set were compared. Then the predictive performance of supervised learning PSO-SVR was compared with that of the model. Finally, brittle materials such as glass-ceramics and calcium fluoride, which were not included in the labeled training set, were taken as processing objects for lapping and angular polishing experiments, and four groups of subsurface microcrack depth values were compared with the predicted values of the model. The results show that co-training SVR model with separate partitioning method have smaller convergence value of mean square error. Compared with the PSO-SVR model, the mean square error and mean absolute percentage error of the proposed model are reduced by about 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 model can predict the subsurface microcrack depth accurately and reliably when lapping brittle materials with fixed abrasives.

Study on the growth of diamond on new KTN substrate and its photocatalytic performance

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0007

Abstract(44)

Abstract:
The substrate selection for the diamond growth is important. A single crystal of potassium tantalum niobate was chosen to deposit diamonds by microwave plasma chemical vapor deposition (MPCVD) techniques. The surface morphologies and microstructures of the as-deposited diamonds were characterized by SEM, XRD and Raman spectroscopy. The photocatalytic properties were studied and all samples show good ability to degrade Rhodamine B. The degradation rate increases with the growth time of polycrystalline diamond samples. This research provides a novel substrate for growing polycrystalline diamond, and it has made the exploration of diamond applications in photocatalysis.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0008

Abstract(48)

Abstract:
Aiming at the problem of cutting noise of five different specifications of diamond circular saw blades, the modal analysis and traveling wave vibration analysis were carried out by Workbench software, and the influence of nose-shaped radial grooves, holes and interlayers on the traveling wave vibration of saw blades was studied. The analysis results show that the traveling wave resonance occurs in the conventional saw blades with diameters of 180 mm and 230 mm, resulting in strong noise. Conventional saw blades with a diameter of 115 mm and 350 mm do not exhibit traveling wave resonance. The δ value of 180 mm and 230 mm saw blade is too large, which effectively avoids traveling wave resonance. The δ value of 115 mm and 350 mm saw blade is too small, which leads to poor noise reduction effect. The δ value of 105 mm sandwich saw blade is too large, and the noise reduction effect is good. In this paper, five kinds of design schemes of radial groove, raindrop hole and damping interlayer are proposed. The δ values are 8.13 %, 7.21 %, 6.01 %, 6.39 % and 7.00 %, respectively. The traveling wave resonance is further avoided and the noise reduction effect is better.

Functional surfaces of medical devices based on laser processing: a review

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0010

Abstract(44)

Abstract:
The preparation of functional surfaces is one of the important methods to enhance the therapeutic performance and safety of medical devices. Currently, the fabrication of functional surface microstructures based on laser processing is widely used in the optimization of medical device surface properties. This paper reviews the current research status of functional microstructures for laser processing of medical implantable and surgical devices in terms of cell function regulation, antimicrobial properties, corrosion resistance, frictional properties, and anti-adhesion, etc. It analyzes the advantages and limitations of laser processing of functional surfaces for medical devices and outlooks the development prospects of laser processing technology for functional surfaces for medical devices.

Study on the machining performance of electric antirust grinding

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0011

Abstract(38)

Abstract:
In view of the problems of environmental pollution, harm to human health and increase in production and processing costs caused by the use of grinding fluid in traditional grinding, this paper proposes an electric antirust grinding method using tap water instead of traditional grinding fluid, and uses the self-made electric antirust grinding system to carry out processing performance research. The differences in grinding force, grinding force ratio, grinding specific energy, grinding temperature and surface roughness between electric antirust grinding and dry grinding and wet grinding are compared and analyzed. The results show that the average difference between electric antirust grinding and dry grinding is about 19.2%, and the average difference between electric antirust grinding and wet grinding is about 7.7%. Its processing performance is far better than dry grinding and close to the level of wet grinding. The processing method of electric antirust grinding has certain applicability.

Study on the influence of grinding disc motion on the forming of silicon nitride ceramic balls

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0012

Abstract(42)

Abstract:
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, 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 variation of ball diameter and batch diameter of silicon nitride ceramic balls, and the deflection motion of the lower grinding disc must be reduced during the actual processing.

Development of Multilayer Brazed Diamond Grinding Wheel for Ceramic Precision Grinding

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0020

Abstract(23)

Abstract:
In order to solve the problems of low grinding efficiency and easy blockage and burn of grinding wheel when grinding ceramic materials with traditional resin and electroplated diamond grinding wheel, the feasibility of using brazed diamond technology to prepare multilayer brazed diamond grinding wheel for ceramic grinding is analyzed. Combined with the optimization of filler metal composition, the multi-layer brazed diamond grinding wheel with slotted structure was prepared, and the grinding performance of 99.9% high-purity Al2O3 ceramics was tested. The results show that the resin and electroplated diamond grinding wheels have the problems of low grinding efficiency and insufficient grinding life respectively. The single-layer brazed diamond grinding wheel has high grinding efficiency but limited grinding life. The multi-layer brazed diamond has obvious advantages in grinding life while maintaining high grinding efficiency. In the process of ceramic material grinding, the grinding effect of multilayer brazed diamond grinding wheel is remarkable. Although the exposed height of abrasive particles is limited, the chip removal effect of slotting design is significant, and the surface of grinding wheel is not easy to bond and block ceramic powder.

Research on cylindrical grinding temperature of 18CrNiMo7-6 steel using infrared temperature measurement

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0013

Abstract(32)

Abstract:
In order to study the variation rule of workpiece temperature in cylindrical transverse grinding process, 18CrNiMo7-6 gear steel was selected as workpiece material, and CBN grinding wheel was used as grinding tool. Infrared thermal imaging instrument was used to detect the grinding process temperature. Whether the calibration of emissivity value of thermal radiation is accurate is an important factor affecting infrared temperature measurement. In order to ensure the accurate measurement of temperature, a calibration scheme of thermal emissivity value with an additional air curtain device is proposed. The high-speed airflow generated by the air curtain is used to slow down the entry of external air into the heating furnace, prevent the oxidation of samples in the calibration process, and ensure the accuracy of the emissivity value calibrated under high temperature conditions. According to the test results, the influence of workpiece speed v_w, workpiece grinding depth per revolution f_a, grinding wheel granularity, grinding wheel diameter d_s and grinding width b on the temperature was analyzed. Compared with other parameters, the workpiece grinding depth per revolution f_a was the most significant factor affecting the temperature change, and the relevant empirical formula was obtained, with its own error of 9.27%. The measurement results were compared with those derived from the theory of moving heat source, Rayleigh distribution model and dry grinding heat distribution ratio model, and the deviation was 8.51%.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0022

Abstract(45)

Abstract:
In the diamond powder manufacturing industry, the large stock of fine-grained diamond powder is one of the challenges. In this experiment, aluminum-borosilicate bond was used as the binder, and Si powder and Ti powder were used as additives to adjust the agglomeration effect of diamond abrasives. The bending strength, phase composition and micro-morphology of the samples were analyzed, the results showed that either the binder with Si or Ti additives would made agglomerated diamonds. When the mass content of Si and Ti was 10%, both the ceramic bond samples and the agglomerated diamonds had the highest bending strength, 43.74 MPa. When the content of Si or Ti exceeded 10%, many Si or TiO₂ peaks were found in the sample, and the bending strength decreased sharply. The agglomerated diamond samples with Si had the bigger and more uniform particle size than the samples added with Ti. The particle size of agglomerated diamond samples with Si was 5~10 μm.

Simulation optimization of physical field of diamond particles deposited by multi-piece substrates HFCVD system

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0031

Abstract(50)

Abstract:
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.

Experimental study on Normal Force of cutting sapphire with multi-line swinging reciprocating saw

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0039

Abstract(27)

Abstract:
Multi-line swinging reciprocating wire saw cutting is the main machining method to cut sapphire crystal bars into wafer substrate. The normal force is an important index to reflect the stability of the machining process. In this paper, the normal force Fn generated in the process of cutting sapphire crystal bars by a multi-wire swinging reciprocating wire saw was measured. The variation law of normal force at different positions and cutting depths was tracked. The variation amplitude of normal force Δ Fn was used as an indicator to investigate the influence of various process parameters on the stability of the machining process. The experimental results show that the Fn corresponds clearly with the reciprocating motion of the wire saw and the swinging motion of the workpiece, and the Δ Fn in the front of the wire net is different from the middle and the rear area. Process parameters such as the speed of the wire saw (V_s), maximum swing angle (θ_max), single piece wire consumption (M_d), tensioning force (F_w), and total cutting time (T) have different effects on Δ Fn . The fluctuation degree of Δ Fn is closely related to the wear of wire saw.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0042

Abstract(43)

Abstract:
The effects of bath composition, process conditions and other factors on the internal stress and hardness of Ni-W alloy coating were investigated, and the coating with low internal stress and high hardness was prepared for tribochemical polishing of diamond. The effects of sodium tungstate concentration, complexing agent concentration, solution PH, saccharin sodium concentration on the internal stress, tungsten content, hardness and deposition rate of the coating were investigated by single experiment, and the leveling effect of different additives on the coating roughness was explored. Finally, under the conditions of sodium tungstate 40 g/L, sodium citrate 120 g/L, saccharin sodium 1 g/L, and solution PH of 6, a Ni-W alloy disk with hardness of 713 hv and thickness of 0.7 mm was prepared by using the reverse pulse method and salicylaldehyde as the leveling agent. The polishing disc is used to conduct tribochemical polishing of diamond, and the process conditions are studied. When the speed of the polishing disc is 8000 rpm (linear speed 19.3 m/s), and the pressure is about 4.4 MPa, the polishing effect is good, and the removal rate is 5.56 μ M/min, and the grinding ratio reaches 0.394, and the surface roughness is Ra 3.693 nm. Compared with the cast iron disk, the performance of nickel tungsten alloy disk is much higher.

Experimental study on wear of P110 Steel processed by super hard abrasive core drill under water

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0044

Abstract(23)

Abstract:
P110 steel has good comprehensive mechanical properties and is widely used as casing in oil and gas wells. When using cemented carbide tools for underwater milling and fishing, the wear is serious. In this paper, the wear ratio of drilling P110 steel with three different kinds of super-hard abrasive grains and binders has been experimentally studied, the surface morphology of abrasive grains on the tool surface has been tracked and observed, and the graphitization of diamond abrasive grains has been analyzed. The experimental results show that under the same processing conditions, the end wear of the three different core drills is roughly the same, but the side wear of the core drill using diamond abrasive particles is significantly less than that of the core drill using cubic Boron Nitride abrasive particles. Under the condition of underwater machining, the end face diamond abrasive grains will produce graphitization, but the diamond abrasive grains still maintain a certain cutting ability. The hardness of the bond affects the exposure of abrasive particles, which results in the performance of the tool under different working conditions.

Study of different Pore-marking agent on properties of resin bond diamond wheel of fine grinding cemented carbide ball valve

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0116

Abstract(22)

Abstract:
Abstract：In order to improve the processing of cemented carbide ball valve, a pore forming agent was introduced into the resin diamond grinding wheel. Through the analysis of mechanical properties, he analysis of micromorphology of specimens by SEM , and the analysis of grinding performance, the hardness of hollow glass spherical pore forming agent and resin spherical pore forming agent on the properties of resin diamond grinding wheel was studied. The results show that with the increase of pore forming agent content, the flexural strength of the grinding wheel gradually decreases, and the influence of the two pore forming agents on flexural strength is basically the same. The hardness of the grinding wheel gradually decreases with the increase of the pore forming agent content, but the influence of hollow glass balls on the hardness of the grinding wheel is significantly greater than that of resin balls. Through the grinding performance, it can be seen that the processing of the pore forming agent significantly improves the sharpness of the grinding wheel, and the grinding wheel with a volume fraction of 15% of the hollow glass ball and the grinding wheel with a resin ball volume fraction of 20% have the best comprehensive performance, and the comprehensive performance of the latter is better than the former.

Effect of corrosion on sawing stability of diamond circular saw blade

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0115

Abstract(22)

Abstract:
Abstract：When the rusted diamond circular saw blade works, there will be some problems such as reduced sawing stability. In response to this phenomenon, the models are established through the structural parameters of saw blade with different corrosion degrees, and modal analysis of saw blades with different corrosion degrees are carried out, which took sawing vibration as a reference index of stability and studies the influence of saw blade corrosion on stability, and experiments verify the accuracy of the results. The results show that the vibration modes of the corroded saw blade more 6 orders than those of the original saw blade, and the difference of adjacent natural frequencies reduce 7.08% in the frequency range of 640~1280 Hz. With the increase of corrosion degree, the saw blade is more prone to resonance. The corrosion at the important position has great influence on the sawing stability of the saw blade. The corrosion can be reduced by reducing the surface defects, and the influence on the sawing stability of the saw blade can be reduced. This study provides guidance for the practical use and rust prevention technology of diamond circular saw blades.

Prediction of grinding surface roughness of Al2O3-based insulating coating on bearing surface considering the change of grinding wheel surface morphology

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0118

Abstract(35)

Abstract:
To improve the prediction accuracy of grinding surface roughness of Al2O3-based ceramic insulating coating on bearing surface, a BP neural network prediction model was established which was consistent with the actual machining process. A method for measuring grinding wheel surface and quantifying abrasive particle characteristic parameters was proposed based on the principle of spectral confocal. A neural network prediction model for workpiece surface roughness was established, which took characteristic parameter K of grinding wheel surface, grinding wheel speed ω, workpiece feed speed υ, cutting depth ρ and normal grinding force F as input parameters. The model could directly reflect the time-varying state of grinding wheel surface. Finally, the prediction performance of the network was verified by the known grinding samples and the four groups of unknown test samples after grinding wheel passivation. For the known samples, the roughness predicted by BP network is consistent with the actual roughness, and the network output error is less than ±0.04μm. Further using the network for the grinding wheel after passivation to predict the unknown grinding test samples, the accuracy of the network prediction decreases, and the maximum error percentage is less than 20%. The neural network, which includes the characteristic parameters of abrasive particles on grinding wheel surface, can be used to predict the workpiece roughness of Al2O3-based ceramic insulation coating on bearing surface under the transient state of abrasive wear of grinding wheel, and the network has a certain generalization ability for unknown samples.

Effect Mechanism of Nano-scratch Speed on Removal Behavior of Single Crystal Silicon

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0124

Abstract(25)

Abstract:
As a typical hard and brittle material, single crystal silicon is strongly influenced by strain rate. And different scratching speeds produce different strain rates, which lead to different removal behaviors. Therefore, molecular dynamics was used to study the deformation and removal processes at different scratching speeds from the perspective of strain rate in this paper. The results showed that the scratching force, shear stress and friction coefficient decreased with the increasing scratching speed due to the increase of the strain rate. In contrast, the scratching temperature rose with the increased scratching speed, which was attributed to the elevated adiabatic effect. As the scratching force and friction coefficient decreased during the scratching, the scratching surface profile accuracy and roughness increased with the growing scratching speed. Amorphization and phase transformation were the main occurrence mechanisms for nanoscale deformation of single crystal silicon during scratching. The reduction of shear stress was the main reason why the depth of subsurface damage layer decreased with the rising scratching speed. The increasing scratching temperature induced by increasing scratching speed led to an improvement in the depth of surface amorphous layer.

Energy Consumption Modeling and Parameter Optimization of Tower Combined Diamond Circular Saw Blade

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0128

Abstract(11)

Abstract:
In order to precisely forecast the power of Tower combined diamond circular saw blade during material sawing, a model for sawing power was established using the average thickness of an undeformed chip from a single grinding grain of a solitary saw blade within the combination saw as a medium, and was thereafter refined. A fast but accurate prediction model, requiring only a small number of samples, was presented. Sawing power was measured through a range of parameter combinations via sawing experiments, and model coefficients were obtained through fitting the data using multivariate linear regression techniques. An optimization model was then established, with sawing parameters as optimization variables. The objectives of this model were to minimize the sawing specific energy and to reduce the sawing time. An optimized particle swarm algorithm was adopted to solve the model. The experimental results reveal that the parameter model can completely elucidate the influence of various sawing parameters on sawing power, with the model accurately forecasting the sawing power under different saw blade combinations. The improved particle swarm algorithm displays strong optimization performance, with optimized parameters contributing to significant reductions in sawing power.

Research on cutting burrs in high speed milling of aluminum alloy plane with diamond coated tools

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0130

Abstract(16)

Abstract:
The nano and micro diamond film coated tools was prepared by hot wire CVD method.The surface morphology of the film was characterized by field emission scanning electron microscopy.The prepared CVD diamond coated tools was used to end mill aluminum alloy surface forward and backward at high speed under the condition of dry cutting without lubrication. It studies the characteristics and size of edge burrs during high-speed end milling of aluminum alloy using CVD diamond coated tools. It carries out orthogonal tests on cutting process parameters to explore the cutting parameters and processes with little or no cutting burr when nano-diamonds coated tools are used for high-speed forward milling. The results show that distribution of burrs on the edges of the workpiece is uneven after milling, and the burrs during forward milling are sparse and small in size. Among them, the average height of burrs on the edges during forward milling with nano diamond coated tools is 32.08 μm. Only 46.5% of the forward milling burr height of micrometer diamond coated tools. When nano diamond coated tools are used for high-speed forward milling of flat surfaces, v_c has the greatest impact on edge burrs, followed by v_f, and a_e has the weakest impact. The optimal parameter combination for high-speed milling is a_e=4 mm, v_f=2 000 mm/min, and v_c=400 m/min. The average burr height after milling is 21.29 μm. When the diamond coated tool is used to end mill the aluminum alloy plane, in order to obtain a small burr, the nano diamonds coated tool is selected, the cutting method of forward milling and the corresponding high-speed cutting parameters are adopted.

Experimental evaluation of grinding zirconia ceramics with vein bionic fractal textured diamond grinding wheel

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0131

Abstract(18)

Abstract:
In the traditional grinding process of zirconia ceramics, there are problems such as large grinding force and poor processing quality. According to the excellent performance of the fractal structure of the veins in drag reduction, diversion and heat and mass transfer, the adaptive growth model and fractal angle model of the veins were established, and the bionic fractal textured diamond grinding wheels with three different fractal angles ( 30 °, 45 °, 60 ° ) were designed. The effects of the original grinding wheel and three bionic fractal grinding wheels on the surface roughness, grinding force and grinding force ratio of zirconia ceramics were compared and analyzed. The experimental results show that compared with the original grinding wheel, the normal grinding force of the bionic fractal grinding wheel is effectively reduced by 12.7 % ~ 55.8 %, and the tangential grinding force is effectively reduced by 8.1 % ~ 40.3 %. When the fractal angle is 30 °, the minimum grinding force ratio is 1.4 ~ 3.0 and the minimum surface roughness value is obtained. This indicates that the bionic fractal grinding wheel has better grinding performance than the original grinding wheel, and provides further evidence for the method of constructing bionic fractal textured grinding wheel based on veins.

Application of Diamond Based Materials in Efficient Heat Dissipation and Surface Microchannel Fabrication Technology

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0132

Abstract(57)

Abstract:
With the rise of third-generation semiconductors, electronic devices are developing towards high-power, miniaturization and integration, which causes the heat flux density of chips increasing rapidly. Due to above reasons, heat accumulation has become a critical problem which restricts the improvement of electronic devices performance. Diamond based materials have excellent thermal properties, efficient heat dissipation technology based on these materials has become a key direction to solve the ultra-high heat flux dissipation problem. This article reviews the application of diamond based materials in efficient heat dissipation, and discusses the main methods of fabricating surface micro-channels of diamond heat sink. The development and application of diamond based materials for efficient heat dissipation technology can provide technical support for solving the problem of high heat flux dissipation.

Analysis and optimization of traveling wave of large diamond core drill bit

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0137

Abstract(45)

Abstract:
For the vibration and noise issues that occur during drilling of large diamond core drill bits, modal analysis was conducted using Ansys Workbench finite element software on core drill bits without openings, openings, interlayers, and installation of positioning wheels. Furthermore, the resonance margin/δ of core drill bits was calculated using traveling wave vibration theory to analyze the effect of avoiding traveling wave resonance. Study the influence of openings and interlayers on traveling wave vibration. The results show that when the drilling speed is 186.72 r/min, the δ of the no opening core drill bit is 0, and a backward traveling wave resonance occurs. In the area where there is a large deformation of the inherent mode of traveling wave resonance in the no opening core drill bit, the δ of opening 8 sets of circular holes (3 in each group) and 8 S-shaped holes in the core drill bit is 4.97%, which avoids traveling wave resonance effectively; The δ of the opening and sandwich core drill bit is 5.72%, which has the best effect of avoiding traveling wave resonance. In order to improve the accuracy of machining holes, positioning wheels are installed around the core drill bit, and the impact of the number of positioning wheels on traveling wave vibration is analyzed. Among them, the δ of installing 6 and 12 positioning wheel core drill bits is 4.27% and 4.47%, respectively, to avoid traveling wave resonance. Comparing the δ of 2 to 12 positioning wheel core drill bits and considering installation convenience, the optimal number of positioning wheels for installation is finally determined to be 6.

Preparation of diamond coated floating core and its application in copper pipe production

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0138

Abstract(39)

Abstract:

The Experimental Study on Structured Topological Fish Scale Surface by Micro-Abrasive Jet Machining

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0139

Abstract(26)

Abstract:
Due to the good drag reduction effect of the traveling wave structure on the surface of structured fish scales, it is of great significance to prepare structured fish scale surfaces on hard and brittle materials. In order to prepare structured fish scale surfaces on brittle and difficult-to-process materials, the topological features of fish scale surfaces are first extracted, and a surface model of fish scale units is established. The fish scale model is then used to construct the structured fish scale surface. Next, based on the principle of micro-abrasive air jet processing, the feasibility of air jet processing for topological fish scale experiments and the important process parameters affecting the morphology of the structured fish scale surface are analyzed. Finally, using the single-factor experimental method, the important processing parameters are experimentally analyzed to obtain a better topological fish scale surface unit, and the structured surface is arranged accordingly. The research results show that using micro-abrasive air jet processing, it is possible to process structured topological fish scale surfaces on hard and brittle materials. Different process parameters will change the surface morphology of the processed material, but the topological properties of the fish scale surface remain unchanged.

On-linediscrimination of diamond roller profile state

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0148

Abstract(51)

Abstract:
Diamond roller profile grinding is one of the key technologies for manufacturing diamond rollers. Currently, diamond grinding wheels are commonly used for precision profile grinding of diamond rollers. The surface contour Pv value of the diamond roller is an important indicator for assessing the profile grinding process. In current machining inspections, workers often need to stop the machine, remove the roller, and place it on a contour gauge for measurement, which significantly increases the time and cost of roller production. Therefore, this paper proposes an online detection method based on wavelet packet coefficients and random forest for the vibration signals generated during the longitudinal grinding and trimming process of diamond rollers on a five-axis machining center. The accuracy of the proposed method in state recognition is 92%, indicating its practical application value.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0154

Abstract(36)

Abstract:
To investigate the microscopic influence of ultrasonic vibration on the surface flaws of particle-reinforced titanium matrix composites (PTMCs) during cutting with ultrasonic vibration of PCD tools. A two-dimensional cutting microscopic non-homogeneous model for PTMCs 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. Form of 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.

Analysis of the current status of research on rock-breaking mechanism and performance testing methods of PDC cutters

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0155

Abstract(38)

Abstract:
Polycrystalline Diamond Compact (PDC) drill bit is one of the main rock-breaking tools in drilling engineering. As the cutter of PDC drill bit, its performance indexes such as rock breaking efficiency, wear resistance, thermal stability and impact resistance have a great influence on the use of PDC drill bit, and the related research have attracted much attention in both domestic and foreign countries. This paper summarizes the research progress of experimental devices, testing methods and representative results on rock breaking mechanism and performance testing of PDC cutters in both domestic and foreign countries. According to the way of interaction between PDC cutters and rock, the relevant experiments mainly include five categories: PDC cutter linear cutting experiments, rotary cutting experiments, drop impact experiments, PDC single cutter static pressure experiments, and full-size PDC bit experiments and so on. According to the purpose of the test, it can be divided into two categories: rock breaking mechanism and performance test of PDC cutter. The advantages and disadvantages of these experimental studies are investigated and analyzed in order to provide useful references for the research and optimization of PDC cutters and the overall personalized design of PDC bits.

(a)10%, (b) 20% , (c) 30% , (d)40%.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0170

Abstract(23)

Abstract:

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0171

Abstract(39)

Abstract:
Porous diamond grinding tools are a new-type tools that can provide a space for chip holding and coolant flowing during the grinding process. Selective Laser Melting (SLM), as a typical additive manufacturing technology, is an effective method to fabricated porous diamond tools. However, due to the limitations of spot size and layer by layer fabricating process in SLM process, the designed porous diamond tools are difficult to be manufactured accurately. Therefore, it is necessary to investigate the manufacturing process constraint of feature structures. Based on CuSn20/diamond composites, a series of feature structures such as overhang structures, thin-walled, holes, and sharp angle structures with different fabricating directions and sizes were fabricated by SLM technology. The formability, forming errors, and causes of these structures are analyzed. The results show that the optimal formable length of the overhang structure is 1-2 mm; The minimum formable size of thin wall structures is 0.70 mm; The minimum formable diameter size of hole structures perpendicular to the fabricating direction is 0.20 mm; The optimal forming diameter size for circular hole structures parallel to the fabricating direction is 0.50-3.00 mm; The formable angle of sharp angle structures should be greater than 10 °. The forming error of feature structures is mainly affected by the thermal adsorption of laser on composite powder, the diffusion of laser spot heat affected zone, and the weak support of composite powder. This work provide a certain technical reference for the design and additive manufacturing of complex diamond tools.

Study on Mechanical Properties and Rock Breaking Effect of Ridge-Shaped Cutters

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0172

Abstract(26)

Abstract:
Based on the formation characteristics, the targeted selection of shaped cutters can reduce the probability of PDC cutters failure and increase the rate of penetration (ROP) and footage. In order to comprehensively compare the mechanical properties and rock-breaking effect of ridge-shaped PDC cutters, three kinds of ridge-shaped PDC cutters (165-axe, 135-axe, and triple-edged) were firstly studied for wear resistance and impact resistance, and then granite was selected to conduct single-cutter cutting experiments at three depths of cut (DOC), and simulated drilling experiments of full-size bits under different weight of bit, and compared with round cutter. The results show that: ① The wear resistance of ridge-shaped PDC cutter is better than that of round cutter. ② The impact resistance of 165-axe and three-edged cutter is better than that of round cutter, and 135-axe has poorer impact resistance due to the lack of support at the point of impact. ③ At the same DOC, the tangential force and normal force of ridge cutter are lower than that of round cutter, and the smaller the angle of the ridge is, the smaller the cutting force is. ④ The 135 axe shape has the fastest ROP and is suitable for high WOB, the triple-edged cutter have a faster ROP in the low drilling pressure range (less than 20 kN) and a slower ROP in the high drilling pressure range (more than 20 kN) compared to the 165-axe. The rounded cutter have the slowest ROP and are suitable for lower WOB. The experimental results show that when the ridge angle changes, the support material at the impact point also changes, which affects its impact resistance, and at the same time, the change of the ridge angle will change the stress concentration inside the rock in front of it, which will change the effect of rock breaking. The results of this paper can provide a reference for the optimal design of ridge cutter design, bit cutter placement and drilling parameter selection.

Simulation experimental on material removal mechanism of ITO conductive glass by single abrasive

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0183

Abstract(42)

Abstract:
In order to study the removal mechanism of ITO conductive glass materials, this paper uses single abrasive particle to simulate the cutting process of the materials and establishes a material model for ITO glass. Based on the analysis of the processed surface morphology, stress, and cutting force, the material removal mechanism of ITO glass is analyzed. Then, the influence of cutting parameters on cutting force and residual stress are studied and compared with soda-lime glass. The results show that during the cutting process of abrasive particle, the removal of the material is jointly affected by the ITO film layer, glass substrate, and cohesive contact behavior, leading to failure forms such as delamination, channel cracking, and interlayer fracture. With the feed of the abrasive particle, the cutting force fluctuates within a certain range and exhibits a pattern of growth, stability, and decrease. The cutting force of the abrasive particle is positively correlated with the cutting speed and cutting depth. Compared to the glass substrate, the residual stress on ITO film is larger and fluctuates more dramatically. The presence of the ITO film significantly influences the cutting behavior when the cutting depth is close to the thickness of the ITO film.

Effect of pad and slurry on fixed abrasive polishing of gallium oxide crystal

, Available online , doi: 10.13394/j.cnki.jgszz.2022-0043

Abstract(386)

Abstract:
Gallium oxide crystal is the most representative fourth generation semiconductor material with the advantages of high band gap, high voltage resistance and short absorption cutoff edge, and has broad application prospects. Gallium oxide crystal is prone to micro-cracks, scratches and other surface defects in the polishing process, which is difficult to achieve high-quality surface processing and cannot meet the requirements of the corresponding devices. Moreover, the existing polishing process of gallium oxide crystal is complex and inefficient. Fixed abrasive polishing technology has the advantages of controllable abrasive distribution and depth of cut, and high utilization rate of abrasive grain. Fixed abrasive polishing was used, and the effect of pad and slurry on material removal rate and surface quality were explored in fixed abrasive polishing of gallium oxide crystal. The results show that when the hardness of the polishing pad is moderate II, the abrasive concentration is 100%, and the slurry additive is oxalic acid, material removal rate is 68 nm/min, and the surface roughness Sa value is 3.17 nm in fixed abrasive polishing gallium oxide crystal. Fixed abrasive polishing technology can achieve efficient and high-quality polishing of gallium oxide crystal

Development of CAM system for automatic compound dressing of superabrasive grinding wheels

, Available online , doi: 10.13394/j.cnki.jgszz.2022-0061

Abstract(205)

Abstract:
In the field of superabrasive wheel dressing, multi-process composite dressing has obvious advantages, but there is no research related to the automation system of grinding wheel composite dressing. In order to make the integration of multiple processes in the composite dressing method more systematic and improve the dressing efficiency of shaped grinding wheels, this paper develops a CAM system by self-developed laser-mechanical composite dressing equipment, which can, according to different grinding wheel section shapes, automatically plan the dressing trajectory under multiple processes and dressing strategies, calculate the dressing toolpath with planar three-axis linkage, automatically generate the machining code, and at the same time design a visualisation interface to simulate the machining process. The results of dressing experiments on 150# diamond bronze bonded grinding wheels show that the system can generate machining programs for laser roughing, semi-finishing and mechanical finishing without collision and overcutting of the machine tool, and significantly improve the programming efficiency of the compound dressing method. And the dressing wheel profile error is within 9.1 µm and circular runout error is 6.1 µm.

Study on the Mechanism and Process Magnetorheological Variable Gap Dynamic Pressure Planarization Finishing

, Available online , doi: 10.13394/j.cnki.jgszz.2022-0004

Abstract(276)

Abstract:
In order to improve the polishing efficiency of magnetorheological polishing and realize the high-efficiency, high-quality and ultra smooth planarization of photoelectric wafer, a magnetorheological variable gap dynamic pressure planarization method is proposed. In this paper, the changes of material removal rate and surface roughness of sapphire wafer surface polishing with processing time under different variable gap conditions are studied, and the dynamic pressure flattening mechanism of magnetorheological variable gap is deeply analyzed. The results show that the dynamic change of polishing pressure and the extrusion strengthening effect of MR fluid can be produced by applying axial low-frequency extrusion vibration to MR polishing fluid, and the polishing efficiency and polishing effect can be significantly improved. After 120 min of magnetorheological variable gap dynamic pressure flattening, the surface roughness of sapphire wafer decreased from Ra 7 nm to Ra 0.306 nm, and the material removal rate was 5.519 nm / min. Compared with constant gap magnetorheological polishing, the surface roughness decreased by 49% and the material removal rate increased by 55.1%; By changing the moving speed of variable clearance, the flow field characteristics can be controlled. Choosing the appropriate workpiece pressing speed and workpiece lifting speed is conducive to improve the polishing efficiency and surface quality.

Effect of Fe₃O₄ Characteristics on Properties of Solid-phase Fenton Reaction Lapping Pellets for Single-Crystal SiC

, Available online , doi: 10.13394/j.cnki.jgszz.2022-0008

Abstract(265)

Abstract:
To improve the lapping quality and processing efficiency of single-crystal SiC, solid-state Fenton reaction lapping pellets were prepared. Effects of particle size and concentration of Fe₃O₄solid-phase catalyst on the physical properties (hardness, flexural strength, porosity), catalytic performance, and lapping performance of single-crystal SiC were studied. The results showed that with the increase of Fe₃O₄ particle size, the hardness, flexural strength, porosity, and catalytic performance of the lapping pellets all decreased, the material removal rate (MRR) decreased from 43.12 nm/min to 36.82 nm/min, and the surface roughness (Ra) increased from 1.06 nm to 3.72 nm. As the Fe₃O₄ concentration increased, the hardness and flexural strength of the lapping pellets decreased, and the porosity and catalytic performance increased. Although the material removal rate decreased, the surface roughness (Ra) decreased firstly and then increased. The MRR decreased from 40.14 nm/min to 33.51 nm/min, the surface roughness (Ra) was 3.25 nm, 1.75 nm and 1.88 nm. In this experiment, when the Fe₃O₄ particle size and the concentration was 0.5 µm and 29 wt.%, the processing effect was the best, the MRR and the surface roughness (Ra) was 43.13 nm/min and 1.06 nm.

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