金刚石与磨料磨具工程

Study on the influence of orderly arrangement on grinding force in diamond roller dressing process

, Available online , doi: 10.13394/j.cnki.jgszz.2024.0004

Abstract(31)

Abstract:
The diamond roller plays a crucial role in the formation and dressing of grinding wheels, with its abrasive wear being a significant factor that affects both the roller's lifespan and the quality of dressing. Effective arrangement of abrasive particles can help reduce this wear. However, current research primarily focuses on studying the impact of abrasive layout on single-layer grinding wheels, which limits its applicability to abrasive accumulation grinding wheels. This paper investigates how the arrangement of abrasive grains influences the process of dressing a grinding wheel. By employing finite element simulation and experimental verification during the forming and dressing processes using three types of roller arrangements (dislocation, array, and phyllotactic pattern), we evaluate their effects on grinding force as our main indicator. Our findings reveal that during the wheel dressing process, regular particle arrangement significantly impacts grinding force; specifically, array arrangement results in higher forces compared to dislocation arrangement while phyllotactic pattern yields lower forces. Furthermore, when compared to dislocation and array arrangements, phyllotactic pattern arrangement effectively reduces abrasion on the roller surface while enhancing both dressing performance and service life.

, Available online , doi: 10.13394/j.cnki.jgszz.2024.0013

Abstract(45)

Abstract:
The grinding process of hardened mold steel can result in variations in grinding forces due to changes in machining depth, leading to unstable machining conditions. Therefore, utilizing single-point grinding with large-grain diamond, based on the analysis of the surface morphology characteristics of the machining surface, the dynamic properties and stability of the grinding process are investigated. The aim is to explore the mechanism of the effect of process parameters on machining efficiency and surface quality, with the goal of achieving high-efficiency and high-quality grinding. Firstly, the single-point diamond grinding system is dynamically modeled, and then the grinding vibration signals are measured using an accelerometer for modal analysis of the working system. The natural frequency and damping ratio of the machining system are solved. Next, based on the characterization data of surface waviness and roughness, a digital clustering analysis is performed to correlate the feed depth and wheel speed with the stable machining state. This is matched with the stability lobes diagram of grinding to fit the stiffness of the machining system and the coefficient of grinding force. Thus, a real-time controllable grinding process stability is established by controlling the feed depth and wheel speed. Finally, the grinding experiments on mold steel are conducted to validate and analyze the machining efficiency and quality. The results demonstrate that the modal analysis of the grinding process, along with the clustering matching of the surface morphology characteristics, can effectively map the machining process parameters within the stable domain of the grinding process. Within the stable domain of grinding, using a higher material removal rate can reduce the average surface waviness from 1.203 μm to 0.635 μm, and the average surface roughness from 0.267 μm to 0.143 μm. Moreover, under the same material removal amount, the average surface roughness of stable domain grinding can be reduced by 74% compared to unstable domain grinding. Therefore, by adjusting the feed depth and wheel speed in real-time based on the characterized stable domain of grinding during the machining process, it is possible to simultaneously improve the machining quality and efficiency.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0272

Abstract(104)

Abstract:
As a crucial area of aircraft engine blades, the precision of the blade edge directly affects the aerodynamic performance of the blades. Reducing the surface roughness and improving the contour of the blade edge are crucial for enhancing the engine's service life. Therefore, this study designed and developed resin-bonded diamond polishing wheels, investigating the polishing process of blade edges based on a robotic platform. Orthogonal experimental design was employed to explore the impact of four main process parameters (spindle speed, feed rate, processing pressure, abrasive particle size) on the surface roughness and contour of the blade edge. The experiments determined the optimal combination of process parameters: spindle speed at 800 r/min, feed rate at 6 mm/min, processing pressure at 4 N, and abrasive particle size ranged between 10 to 14 μm. With this parameter combination, the polishing effect on the workpiece was significantly improved. The surface morphology was enhanced, the surface roughness of the blade edge decreased from the initial 1.165 μm to 0.243 μm, and the contour reduced from the initial 0.048 mm to 0.016 mm, meeting the usage requirements.

Preparation and propertiesof intermetallic-bonded diamond grindingwheel for thinning silicon carbide wafers

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0250

Abstract(130)

Abstract:
Compared with silicon based materials, silicon carbide has become an ideal substrate material for chip manufacturing due to its good thermal conductivity, breakdown electric field strength, and high bandgap width. However, the Mohs hardness of silicon carbide wafers is as high as 9.5. Realizing the grinding process of silicon carbide single crystal wafers, reducing grinding costs, and improving the processing quality of silicon carbide wafers has become an urgent problem to be solved in the semiconductor industry. This article uses Cu₃Sn and Cu₆Sn₅ intermetallic compounds as bond to prepare rough and fine grinding diamond wheels for silicon carbide wafers. The experimental research results show that this diamond grinding wheel is suitable for grinding SiC single crystal wafers, the wear ratio of the prepared 2000# diamond rough grinding wheel for grinding 6-inch silicon carbide wafers is 1: 5, the surface roughness of the silicon carbide wafer is 11nm; The wear ratio of the 12000# diamond fine grinding wheel is 1: 0.6, the surface roughness is 2.076 nm, and the TTV is less than 3 µm. The grinding performance is good and can meet the needs of industrial production.

Numerical simulation investigations into the effect of machining parameters on the cutting process for ZrO2 ceramics

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0188

Abstract(108)

Abstract:
The three-dimensional cutting process of ZrO₂ ceramics was simulated using the finite element simulation method. By studying the chip removal mechanism, dynamic changes and distribution of stress, and changes in cutting force of workpiece materials, it was found that with the increase of machining depth, the stress on the workpiece gradually increases, and the stress layer on the tool surface also gradually expands and increases towards the front and back cutting surfaces. In addition, the cutting force will gradually increase. The stress and cutting force fluctuate with the increase of cutting speed, but there is no obvious change on the whole. The radius of edge circle will affect the formation of crack at the initial stage of cutting, With the increase of the radius of the cutting edge, the crack length at the front of the cutting tool will become shorter, but the effect of cutting force is not obvious. When cutting with negative rake angle of cutting tool, it will not cause cracks in the ceramics and obtain better machining quality. The maximum cutting force increases rapidly when the tool rake angle is 0°. With the increase of tool rake angle, the change of cutting force is not obvious.

Simulation study of cutting fluid flow field in kerf of fine diameter diamond wire saw

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0235

Abstract(265)

Abstract:
Diamond wire saw is widely used in the field of chip processing of hard and brittle materials such as monocrystalline silicon and sapphire. With the large size of the chip and the fine line of the sawing wire, the kerf is more and more "deep and narrow" in the sawing process, and the cutting fluid plays a full role in the sawing process, which has a great impact on the quality of the slice. Based on the numerical simulation of computational fluid dynamics, the cutting fluid flow field in the kerf of diamond wire saw was analyzed and studied by establishing the CFD kerf model. The simulation analysis found that: in the small size kerf, with the increase of wire speed to more than 25m/s, the cutting fluid can more fully enter the kerf, after the sawing wire and the workpiece contact area and non-contact area filled with liquid, the fluid pressure in the contact area is about 0.179MPa, the fluid pressure in the non-contact area is about 0.159MPa; The reduction of the viscosity and surface tension of the cutting fluid in a certain range is conducive to ensuring the relative saturation and stability of the cutting fluid in the kerf, and the pressure distribution of the cutting fluid in the kerf is more stable.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0267

Abstract(113)

Abstract:
The NVH problem of electric vehicles requires a revolution in gear precision machining technology. Abrasive flow machining is one of the effective methods for polishing complex surfaces such as gears, and fixture design is a crucial part of the abrasive flow machining process. In the process of optimizing the design of abrasive flow fixtures, the selection of physical models contradicts the accuracy of simulation results and the computational expense of simulation. Different viscosity media were selected, and simulation experiments were conducted using different viscosity models and flow models. The fluid pressure distribution, velocity vector, wall shear, and streamline distribution cloud maps reflecting machining uniformity were analyzed to explore the steady-state simulation results of abrasive flow in the slit model. It was found that the distribution trend of simulation results from different physical models has strong similarity, which can achieve consistency in the processing area streamline in the simulation results, proving the feasibility of replacing complex physical models with simple physical models for fixture optimization simulation. By applying simulation results and using the simplest Newtonian fluid - water as the medium, and utilizing the streamline distribution in the machining area, the design optimization of the gear shaft abrasive flow fixture was carried out, achieving the removal of gear “ghost frequencies” after abrasive flow machining.

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0164

Abstract(434)

Abstract:
In this paper, A variety of non-stoichiometric (Ti, Nb)C_x PCD tool binders were prepared by mechanical alloying (MA) of TiC and transition metal Nb. The phase composition of the sintered composite was detected by X-ray diffractometer (XRD), and the composite was treated and analyzed by jade software. The fracture morphology of the composites was observed by scanning electron microscope (SEM), and the hardness and fracture toughness of the composites were measured by Vickers hardness tester. The results show that in the range of 1300 ℃ to 1700 ℃, the higher the sintering temperature, the higher the degree of solid solution of TiC and Nb. Under the same sintering temperature, the hardness of (Ti, Nb)C_x composite gradually increases with the increase of metal Nb proportion. Under the same metal Nb proportion, the higher the temperature, the higher the degree of solid solution of Nb and TiC. Among them, the mechanical properties of composite material (Ti, Nb) C_0.5 are the best, and the best hardness of (Ti, Nb) C_0.5 composite material is 23.0 GPa and the fracture toughness is 7.20 MPa·m^1/2 at 1600 ℃.

Research Status of Thermal Damage Inhibition Technology for Diamond

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0166

Abstract(246)

Abstract:
The thermal damage of the diamond during the preparation process of diamond tools mainly included diamond graphitization, diamond breakage and cracking, and chemical erosion of diamonds. In response to the thermal damage of the diamond, this article introduced the current suppression technologies for diamond thermal damage from three aspects: surface coating of diamonds, adjustment of matrix material properties, and optimization of forming technology. The article also provided prospects for future research directions to provide reference and guidance for the preparation of high-performance diamond tools.

Numerical simulation and experimental study on the uniformity of MPCVD diamond coatings

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0211

Abstract(215)

Abstract:
Based on the microwave plasma module of COMSOL Multiphysics, a numerical model of hydrogen plasma inside a MPCVD reactor was built to investigate the effect of the addition of an annular molybdenum holder at the outer side of the substrate and different Δh (the height difference between molybdenum holder and the substrate) on the distribution of plasma at the surface of the substrate. The uniformity of the plasma distribution was quantitatively analyzed by using the coefficient of variation, and the surface morphology of the diamond coating was analyzed by using SEM. The results show that when Δh = 0 mm, the uniformity of plasma distribution is optimal, and the coating morphology is significantly improved compared with that without molybdenum holder. When Δh < 0 mm, the uniformity of plasma distribution increases with the increase of Δh; when Δh >0 mm, the uniformity decreases.

Simulation and experimentalanalysis of composite chamfering of superhard cutting toolsbased on edge grinding technology

, Available online , doi: 10.13394/j.cnki.jgszz.2023.0223

Abstract(140)

Abstract:
In order to improve the phenomenon of chip accumulation during the processing of arc edge chamfered PCD turning tools, reduce tool wear during processing, and improve their processing performance, a secondary chamfering treatment is carried out on the basis of arc edge chamfered turning tools to form a composite chamfering structure. In CATIA software, based on the actual process of grinding PCD chamfered cutting tools using the grinding machine CORBENR RG9, a three-dimensional model of the cylindrical back face composite chamfered turning tool is established. Then, the Deform V11.0 software is used for 3D cutting simulation analysis of the PCD composite chamfered turning tool.And based on the simulation analysis results, a comparative analysis was conducted on the cutting experiments of PCD composite chamfer turning tool and PCD first-order chamfer turning tool.The results show that when the cutting depth is smaller than the first order chamfer width, the second order chamfer width should be greater than the cutting depth; When the cutting depth is close to the first order chamfer width, the second order chamfer width should be smaller than the cutting depth. When the cutting depth is small and does not exceed the second order chamfer area, choose a larger second order chamfer angle; When the cutting depth is large, choose a smaller second order chamfer angle.At the same cutting depth, the cutting temperature of PCD composite chamfer turning tool is lower than that of PCD first-order chamfer turning tool. When the cutting depth is 0.14mm, as the cutting time increases, the surface roughness of the parts processed with PCD composite chamfered turning tools is smaller than that of PCD first order chamfered turning tools; Comparing the tool wear morphology after 30 minutes of processing, it was found that the PCD composite chamfered turning tool had less wear.

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(215)

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(184)

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(158)

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(254)

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(171)

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(154)

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.

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(220)

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(117)

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.

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

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

Abstract(186)

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.

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(180)

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.

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(141)

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(150)

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(150)

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(118)

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(160)

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(155)

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(169)

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(209)

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(155)

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(139)

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(144)

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(185)

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.

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

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

Abstract(126)

Abstract:

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

Abstract(161)

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(158)

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(167)

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(541)

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(331)

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(427)

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(373)

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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