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SiC ceramics are typically hard and brittle materials. Serious surface/subsurface damage occurs during the grinding process due to the poor self-sharpening ability of monocrystalline diamond grits. Nevertheless, recent findings have demonstrated that porous diamond grits can achieve high-efficiency and low-damage machining. However, research on the removal mechanism of porous diamond grit while grinding SiC ceramic materials is still in the bottleneck stage. A discrete element simulation model of the porous diamond grit while grinding SiC ceramics was established to optimize the grinding parameters (e.g., grinding wheel speed, undeformed chip thickness) and pore parameters (e.g., cutting edge density) of the porous diamond grit. The influence of these above parameters on the removal and damage of SiC ceramics was explored from a microscopic perspective, comparing with monocrystalline diamond grit. The results show that porous diamond grits cause less damage to SiC ceramics and have better grinding performance than monocrystalline diamond grits. In addition, the optimal cutting edge density and undeformed chip thickness should be controlled at 1–3 and 1–2 um, respectively, and the grinding wheel speed should be greater than 80 m/s. The research results lay a scientific foundation for the efficient and low-damage grinding of hard and brittle materials represented by SiC ceramics, exhibiting theoretical significance and practical value. [ABSTRACT FROM AUTHOR]

The ordered grinding wheel can achieve reasonable control of abrasive grain arrangement and grain distance, thus improving the chip space of the grinding wheel and reducing abrasive grain redundancy. In this paper, the design method of the ordered diamond grinding wheel is explored. The grinding model of the ordered diamond grinding wheel was established, and grinding experiments were conducted to verify the accuracy of the model. The results show that the model can reflect the influence law of each arrangement parameter on the surface roughness, but the model needs to consider more situations to interpret the actual grinding process more accurately. It is found that the surface roughness increases with the increase of the grain distance and decreases with the increase of the grain distribution angle. When the grain distribution angle is π/4, the abrasive grain rows may be horizontally aligned along the circumferential direction, resulting in a significant reduction in the number of effective abrasive grains and a significant increase in surface roughness. An ordered diamond grinding wheel was prepared for grinding experiments, and it was found that the surface roughness of the ground titanium alloy was higher than the simulation result. The results of this study provide theoretical guidance and reference for the design and preparation of the ordered grinding wheel. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC)-bonded diamond materials, comprising approximately 50% diamond by volume, represent innovative composites with exceptional mechanical and thermal properties, including high hardness, wear and corrosion resistance, and elevated thermal conductivity. Despite these advantageous properties, the machining of these composites presents formidable challenges due to their extremely high hardness. Grinding with diamond tools is commonly employed among the limited viable machining methods. However, the efficiency of this process is hindered by high grinding forces, elevated temperatures, and significantly high tool wear. Additionally, the surface integrity, form, and dimensional accuracy of the workpiece are compromised by the effects of tool wear and high cutting forces. To address these technological constraints in the grinding of SiC-bonded diamond materials, a laser-assisted grinding process has been developed. Ultra-short pulsed laser radiations were effectively utilized to induce material ablation with controlled structural damages, enhancing the productivity and efficiency of the grinding process through reduced grinding forces, temperatures, and tool wear. Furthermore, this study investigated the influence of grinding tools' specifications, design variations, and parameters on key aspects such as grinding forces, surface quality, and tool wear. Substantial reductions of up to 70% in tangential grinding forces, 83% in normal grinding forces, and a modest improvement in surface roughness achieved. The surface integrity analysis revealed a damage-free ground surface when utilizing laser assistance. Furthermore, there was a substantial enhancement in the grinding ratio (G-ratio), achieving an increase of up to 247%, concurrently with a noteworthy improvement in the actual removal depth, reaching up to 99%, when compared to conventional grinding processes. Compared to the utilized segmented metal bonded diamond grinding wheel, the vitrified bonded diamond grinding wheel induced lower grinding forces and higher actual removal rates. [ABSTRACT FROM AUTHOR]

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The drive at the center of gravity (DCG) concept-based twin-ball-screw drive mechanism (TBSDM) is vital in automated factories for its robustness and reliability. However, changes in the worktable mass or position result in changes in the center of gravity (CG), significantly affecting the system's dynamic properties. In this regard, this paper introduces a novel analytical model using improved receptance coupling to analyze vibrations in four modes. A mathematical framework for the twin TBSDM is generated, and the effect of changing the worktable position–mass on each mode is examined. The applicability of the proposed method is verified based on dynamic experiments that were carried out on a TBSDM of a CNC grinding wheel machine tool. After thoroughly analyzing the experimental and theoretical results, it is revealed that changing the worktable position primarily influences the rotational and axial vibrations of the twin ball screw (TBS). Furthermore, changes in the worktable mass significantly affect the coupling vibration among the TBSs and rotors or bearings. Moreover, in terms of performance, the variances between the theoretical and experimental natural frequencies are consistently below 5%. Thus, the proposed method is promising for the improvement of the modeling and analysis of the TBSDM. [ABSTRACT FROM AUTHOR]

Grinding tools can be used for over 90% of their lifetime, but most practical production tools are replaced between 50 and 80%. Accurate tool condition monitoring, which can monitor the quality of grinding tools, can improve product quality and reduce costs. The transfer learning technique can solve the data distribution and data deficiency issues of deep learning methods, enabling precise tool condition prediction in a grinding system. However, selecting the optimal pre-trained model is crucial for enhancing transfer learning performance due to the relationship between the source and target domains and the negative transfer problem. To address this issue, an encoding metric-based model selection technique was developed that accurately reflects the time series similarity between the remaining useful life (RUL) of the grinding tool and the encoding value and features between the pre-trained model and target data. Encoding metrics that reflect the critical characteristics of transfer learning, such as the target label, data, and pre-trained model, were computed to assess the pre-trained models directly. The target RUL and the extracted encoding values from the target input data and pre-trained models were compared using measurements and correlation to evaluate how closely they matched. The encoding selection method demonstrated superiority over the current source selection criteria, with encoding-based root mean square error (RMSE), mean absolute error, and dynamic time warping showing a high association with the approach (over a Pearson correlation coefficient of 0.66). Furthermore, the method was independent of the quantity and quality of the sources, making it robust for various datasets. The experimental dataset was used to validate the pre-trained model's encoding RMSE selection method, and the method was verified with a strong correlation (Pearson correlation coefficient of 0.79). In conclusion, the proposed encoding metric-based model selection technique can improve both the efficiency and intelligence of the machining process in terms of both quantity (exchange periods) and quality of grinding tools. Accurate tool condition monitoring enabled by this technique can lead to enhanced product quality and reduced costs. [ABSTRACT FROM AUTHOR]

The grinding process of transmission gear with worm grinding wheel usually relies on the manual parameter setting by experienced engineers, but the reliability and validity are quite hard to control due to many grinding factors that affect the surface quality (e.g. structure, size, and materials of gear, heat treatment process, surface accuracy requirements). Therefore, it is necessary to set up a decision system for assisting engineers with designing the process plan efficiently and reasonably. A modified model of the revision method based on the radial basis function (RBF) neural network and case-based reasoning (CBR) considering evaluation index was proposed in this paper. A similar case retrieval mainly relies on the soft likelihood function considering a compound evaluation index model, where the score value of each new case execution test is converted into the corresponding index to achieve effective case storage. Process solutions for similar cases that perform better will be recommended from the case database by means of CBR. These candidates can be revised systematically based on a self-learning model. A modified RBF neural network trained by the existing cases will apply the learned experience to revise solution in part or in whole, which utilizes a self-filtering attribute method based on the correlation coefficient matrix so as to gain the primary attributes. In the case of the grinding gear with worm grinding wheel, the applicability of this technology was demonstrated. A decision-making system applying this method was developed by using.Net framework4.0 and SQL Server. Consequently, the technique can quickly generate a feasible process plan for specific gear. [ABSTRACT FROM AUTHOR]

In the study, the authors investigated the effects of picosecond laser ablation on the surface topographies of MONEL® alloy 400, used in the manufacturing of marine equipment components (such as pumps, valves, fixtures and fasteners). The experimental methodology involved preparing the material through grinding, polishing, and cleaning before subjecting it to picosecond laser ablation using specific parameters. The laser processing was carried out to create square ablated cavities on the alloy surface. The impact of the laser treatment on the surface condition of the alloy was assessed through profilometry analysis. The results provide insights into the surface topographies of the laser-treated MONEL® alloy 400 samples, offering valuable information for potential applications in marine industries [ABSTRACT FROM AUTHOR]

With the increased use of polymeric products and, consequently, steel molds, the growth in grinding applications and the use of lubricoolant fluids is inevitable. As a result, studying different process configurations is of great interest to both the industry and society in general, by making it more economical and sustainable. This work focuses on evaluating the application of different lubricooling methods (conventional, MQL, and MQL + WCJ), cutting tools (green silicon carbide, black silicon carbide, and alumina), and cutting speeds (0.25 mm/min, 0.5 mm/min, and 0.75 mm/min) in the grinding of VP50IM. The goal is to identify the combination with the lowest cost and CO2 production, while assessing its performance through output parameters such as surface roughness, roundness error, G ratio, grinding power, cost analysis, and CO2 emission. Furthermore, SEM images were taken to analyze the machined surface of the workpiece. Based on this data, it was determined that the conventional method still achieved the highest machining efficiency, even though it was more expensive and more polluting. However, the MQL + WCJ technique significantly reduced costs, up to 45%, and CO2 emissions by 67.5%, even though it presented slightly lower performance compared to the conventional method. On the other hand, the MQL system obtained the worst results due to its deficiency in wheel cleaning and heat removal from the cutting zone. It was also observed that increasing the process speed reduces costs and gas emissions, but directly affects performance since machining intensity increases, resulting in lower quality. Finally, the tool with the best heat conduction capacity, green silicon carbide, led to the best process performance, while the alumina tool, with lower thermal conductivity, achieved the poorest results. [ABSTRACT FROM AUTHOR]

Ultrasonic-assisted grinding (UAG) can effectively reduce the grinding force and improve the machining quality of carbon fiber-reinforced ceramic matrix composites (C/SiC) due to its excellent machining performance. Many researches have shown that the machining performance of UAG is closely related to the kinematic trajectory characteristics of the abrasive grains, so the surface morphology of diamond grinding wheels with various process preparations has an important influence on the grinding quality. In this paper, to investigate the performance of UAG of C/SiC composites with diamond grinding wheels prepared by different processes, UAG experiments were carried out on C/SiC composites using diamond grinding wheels prepared by brazing and electroplating processes. The trajectories of the abrasive grains and the maximum undeformed chip thicknesses with different abrasive grain protrusion heights were analyzed and the impact of the two diamond grinding wheels and the grain mesh size on the grinding force, surface roughness, and surface morphology were comparatively investigated. The results indicated that the grinding force and surface roughness obtained by brazed grinding wheels were reduced by 13 ~ 36.05% and 5.95 ~ 19.3% compared with electroplated diamond wheels at 240#, respectively. The brazed grinding wheels could improve the grinding surface morphology to a certain extent. However, the surface roughness value fluctuated with the increase of abrasive grain size. Additionally, the protrusion height of the abrasive grain of the brazed diamond wheels is more favorable for the UAG effect and the grinding wheels are less prone to clogging. [ABSTRACT FROM AUTHOR]

The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers' offerings indicates that new technical solutions are being developed to integrate two or more technological operations. However, these examples have numerous limitations and are mostly not suitable for machining surfaces with complex shapes. An example of such solutions is the use of a dual-tool grinding head, which integrates the process of rough grinding with a ceramic grinding wheel and finish grinding with a flexible grinding wheel. Unfortunately, it has the disadvantage of being limited by the angular shape of the ceramic grinding wheel, making it unable to adapt to the complex geometries of the shaped surfaces being ground. The need to overcome this limitation became the motivation for the research work described in this article. By means of experimental research, it was verified what effect the radial outline on the periphery of a ceramic grinding wheel realized by rough grinding would have on the surface roughness parameters obtained in the process of grinding shaped surfaces. For this purpose, grinding processes using a ceramic wheel with a conical and radial outline were compared. The result of the study was a summary of the surface roughness parameters Sa, St, Sq, Spk, Str, and Sds obtained after two-stage machining (rough and finish grinding). The obtained analysis results showed that changing the axial outline of the ceramic grinding wheel makes it possible to significantly expand the range of applications of the dual-tool head without negatively affecting the quality of the machined surface. Thus, such an improvement will make it possible to increase the applicability of the head by grinding shaped surfaces with a radial profile of curvature. [ABSTRACT FROM AUTHOR]

The forming grinding process is a crucial method for helical flute grinding of the end mill and screw tap, and the grinding wheel profile is the key to ensure the precision of the helical flute, which is constrained by the grinding wheel posture. However, the existing methods have some deficiencies such as the invalidity or uneven wear problems. In this paper, an optimized calculation method of the grinding wheel profile for the forming grinding of the helical flute is proposed, including the suitable grinding posture correspondingly. Firstly, the parametric models of the helical cutting edge and the helical flute surface are established. Secondly, the contact condition between the grinding wheel and the flute is deduced to calculate the grinding wheel profile by the envelop theory. Thirdly, an optimization method for grinding wheel profile is proposed, which could predict of the solution interval, avoid the profile intersection, and improve wear resistance. Finally, the method was verified by a series of simulations and experiments, and the results show that the method could meet the grinding precision requirements and expand the application range of forming grinding technology in helical flute. [ABSTRACT FROM AUTHOR]

Due to its high melting point, tungsten carbide is perfect for mold-core usage during glass molding processes (GMP) such as those needed for manufacturing aspheric lenses. However, its extreme hardness makes it exceedingly difficult to machine. To overcome this problem, a BDD (boron-doped diamond) end-grinding-milling tool with dual-negative rake angle is designed and applied in this study to effectively mill a tungsten-carbide substrate. The first negative rake angle, with cutting edge across the tool's centerline, prevents squashing during cutting between tool point and mold-core surface. This suppresses brittle fracturing by cutting material under pressure-cutting force in the machining area. Further, when preparing the cutting tool, micro w-EDM was used to create micro-protrusion abrasives on the plane of the first negative rake angle that feature a different second negative rake angle, providing pressure in all directions during material removal. This feature ensured cutting occurred under a non-tensile-stress regime, which avoided microcracks and subsurface damage. Experiments have shown that the developed end-grinding-milling tool was successful in creating micro-flutes and an aspheric lens mold-core array. Surface roughness was nano-scale and there were no burrs nor chipping along mold edges, indicating the designed BDD end-grinding-milling tool is good for grinding-milling of superhard materials. [ABSTRACT FROM AUTHOR]

Segmented grinding wheels, with active abrasive regions and passive slots, have been reported as a promising choice for controlling the grinding force via an intermittent cutting scheme. With an appropriate selection of feed and other operating variables, segmented grinding could mark its merits of improved thermal performance and grinding efficiency, typically in difficult-to-machine aerospace materials. However, the formation of a boundary layer around a rotating grinding wheel is always a barrier to effective cutting fluid delivery in the grinding zone. This article attempts to investigate the boundary layer characteristics of segmented grinding wheels, typically with a comparison of 8-segmented and 32-segmented grinding wheels with a non-porous electroplated structure and its comparison with traditional porous grinding wheel configuration. The regression model proposed in this article can predict boundary layer thickness and tangential air velocity in the grinding zone during the rotation of the wheel. A closer look at flow aspects has been covered using computational fluid flow modeling/simulation, followed by experimental assessments through particle image velocimetry and shadowgraphs. The influence of segmentation and its configuration (typically the number of segments) have been illustrated through a case study of wet grinding on Ti6Al4V. [ABSTRACT FROM AUTHOR]

In silicon carbide processing, the surface and subsurface damage caused by fixed abrasive grinding significantly affects the allowance of the next polishing process. A novel grinding wheel with a soft and hard composite structure was fabricated for the ultra-precision processing of SiC substrates, and the grinding performance of the grinding wheel was assessed in this study. Different types of gels, heating temperatures, and composition ratios were used to fabricate the grinding wheel. The grinding performance of the grinding wheel was investigated based on the surface integrity and subsurface damage of SiC substrates. The results showed that the grinding wheel with a soft and hard composite structure was successfully fabricated using freeze-dried gel with a heating temperature of 110 °C, and the component ratio of resin to gel was 4:6. A smooth SiC substrate surface with almost no cracks was obtained after processing with the grinding wheel. The abrasive exposure height was controlled by manipulating the type and ratio of the gel. Furthermore, the cutting depth in nanoscale could be achieved by controlling the abrasive exposure height. Therefore, the fabrication and application of the grinding wheels with soft and hard composite structures is important for the ultra-precision processing of large-size SiC substrates. [ABSTRACT FROM AUTHOR]

Modular hobs are tools with very complex geometry. Regardless of the material of the gear wheels, they determine the accuracy of the gears made in the hobbing machining process. Gears are made of various, often innovative materials depending on the requirements. Sometimes, the materials are characterised by very high hardness (over 65 HRC). The mathematical basis for describing the faces of a hob presented in the article allows for modifying the rack profile shaping the gear wheel's teeth. The model's universality makes it possible to perform numerical simulations of the influence of individual parameters of the hob creation process (geometry of the grinding wheels and their setting in the shaping process) on the profile of the rake and flank surfaces. The cutting edge (rack edge) is the locus of points belonging to both of these surfaces and thus directly impacts the accuracy of the gear wheel that is shaped in the hobbing process. The article summarises the authors' long-term cooperation with the industry, resulting in a series of articles devoted to hobs. The issues presented in the article are significant to the machinery industry and hob manufacturers. [ABSTRACT FROM AUTHOR]

To analyze the mechanical performance of the arc end tooth connection structure, the optimization of electronic sensors based on the connection structure of double rotors with circular arc end teeth was studied. By designing and optimizing the structural dimensions of the arc end tooth, the relative position of the grinding wheel and the workpiece was determined, and the optimal electromagnetic actuator size, as well as the number and installation position of the optimized sensors, were obtained. The experimental results showed that the relative error of the rigid vibration mode of the arc end tooth double rotor connection structure was controlled within 10 %. At high speeds, the electromagnetic actuator had a significant control effect on the vibration of the centrifugal machine shaft. It diminished the vibration amplitudes in the X and Y directions by 37.6 % and 30.2 %, respectively. By optimizing the double rotor connection structure with circular end teeth and electronic sensors, effective control of the relative error of rigid vibration modes has been achieved, leading to significant reduction of the centrifugal shaft's vibration at high speeds. In addition, the sensor layout was optimized to enable real-time equipment vibration monitoring, ensuring equipment safety and stability. These achievements not only enhance the mechanical performance of the rotor system, but also provide important guarantees for the stability of the mechanical system. [ABSTRACT FROM AUTHOR]

Due to the characteristics of thin-walled curved surface, wall thickness variations, and cantilevered machining fixtures, the mechanical state of the different contact positions of aircraft engine blades varies significantly during the grinding process. The different contact interactions between the contact wheel and the blade lead to changes in material removal efficiency and surface quality. To achieve contact state control during the blade grinding process, a novel flexible abrasive belt grinding device was designed and developed, taking into account the compliance of the rubber wheel. The significant effect of compliance parameters on the grinding contact state was verified through simulation. The grinding contact pressure distribution and normal contact force at different positions in the blade width and length directions were studied, and a prediction model for the maximum contact pressure and normal contact force was established based on back propagation neural networks. The results showed that with the increase in contact wheel compliance, the effective contact range increased; the pressure distribution gradually became uniform, and showed a double-elliptical distribution. The maximum contact pressure was significantly reduced, with a reduction of up to 46.00%. As the grinding contact position moved towards the weak rigidity area of the blade, the contact pressure distribution became more uniform. The normal contact force was significantly reduced, with a maximum reduction of 68.49%. The mean average percentage error (MAPE) of the prediction model was small, verifying the effectiveness of the model. The research results of this manuscript laid a foundation for achieving consistent control of the blade grinding material removal rate through contact wheel compliance adjustment. [ABSTRACT FROM AUTHOR]

Monitoring the condition of the grinding wheel in real-time during the grinding process is crucial as it directly impacts the precision and quality of the workpiece. Deep learning technology plays a vital role in analyzing the changes in sensor signals and identifying grinding wheel wear during the grinding process. Therefore, this paper innovatively proposes a grinding wheel wear recognition method based on Variational Mode Decomposition (VMD) denoising and Aquila Optimizer—Convolutional Neural Network—Long Short-Term Memory (AO-CNN-LSTM). The paper utilizes Acoustic Emission (AE) signals generated during grinding to identify the condition of the grinding wheel. To address noise interference, the study introduces the VMD algorithm for denoising the sample dataset, enhancing the effectiveness of neural network training. Subsequently, the dataset is fed into the designed Convolutional Neural Network—Long Short-Term Memory (CNN-LSTM) structure with AO-optimized parameters. Experimental results demonstrate that this method achieves high accuracy and performance. [ABSTRACT FROM AUTHOR]

The influence of damping and friction performance of grinding wheels on precision grinding was explored for the first time. GO hybrid PU-modified PF copolymers were prepared by in situ synthesis and adopted as a matrix for fabricating grinding wheels. FT-IR, DSC, TG, and mechanical property tests showed the optimal modification when PU content was 10 wt% and GO addition was 0.1 wt%. Damping properties were investigated by DMA, and tribological characteristics were measured by sliding friction and wear experiments. The worn surfaces and fracture morphologies of GO hybrid PU–PF copolymers were observed by SEM. Distribution of components on the worn surfaces was explored by Raman mapping and EDS. The research results revealed that the PU component tended to be dispersed around the edges of corundum abrasives acting as a buffer layer of abrasive particles, which could provide micro-damping characteristics for abrasives, making the grinding force more stable during precision machining and facilitating a smoother surface quality of the workpiece. [ABSTRACT FROM AUTHOR]

Thin-walled bearings are widely used owing to the advantages of their light structure, high hardness, and strong load-carrying capacity. However, thin-walled bearings are often prone to deformation during the machining process, which can seriously affect the performance of the bearings. In addition, the machining deformation and quality of bearings are difficult to balance. To address the above issues, this paper investigates the effects of the machining parameters on the machining deformation, surface quality, and machining efficiency of a thin-walled bearing during the roughing stage. The dynamic balance between deformation inhibition and high quality in rough grinding was studied, and the optimal parameters for thin-walled bearing outer ring grinding were obtained. The deformation mechanism of thin-walled bearings caused by grinding was revealed through simulation and experimental analysis. The results show that the machining deformation and quality reach a balance when the workpiece speed is 55 r/min, the grinding wheel rotational speed is 2000 r/min, and the feed rate is 0.1 mm/min. Deformation increases with the increase in workpiece speed and grinding wheel speed. At the same time, the surface roughness increases with the increase in the workpiece speed, but the increase in the wheel speed will improve the surface roughness. As the workpiece speed increases, the surface topography shows a more pronounced stockpile of material, which is ameliorated by an increase in grinding wheel speed. As the rotational speed of the workpiece increases, the number of abrasive grains involved in the process per unit of time decreases, and the surface removal of the workpiece is less effective, while the increase in the rotational speed of the grinding wheel has the opposite effect. The grinding deformation of thin-walled bearings is mainly induced by machining heat and stress. As the rotational speed increases, the heat flux in the grinding zone increases. More heat flux flows into the surface of the workpiece, causing an increase in thermal stresses on the inner surface of the bearing collar, leading to greater deformation. The temperature in the grinding area can be reduced during machining, realizing a reduction in deformation. The research content contributes to the balance between high quality and low distortion in machining processes. [ABSTRACT FROM AUTHOR]

Measuring and extracting abrasive grains on the entire surface of monolayer brazing grinding wheels to analyze the distribution of abrasive grains are of great significance to grinding research and grinding wheel manufacture. It is not easy to carry out the work with traditional methods. In this paper, a linear CCD is used to acquire the entire grinding wheel surface image, and an improved encoder–decoder network based on Efficientnet, ASPP, and Skip Connections is designed to promote the accuracy and speed of abrasive grains prediction. Based on dataset creation, transfer learning, and hyper-parameter testing, 91.21% abrasive grain semantic segmentation accuracy was finally obtained. If we focus on whether the abrasive grains are recognized without considering semantic errors, an accuracy rate of 99.6% is obtained. The method can provide basic data for grinding mechanism research and abrasive tool manufacturing. [ABSTRACT FROM AUTHOR]

A method for dressing the worm wheel for grinding face gear with arbitrary modification amount by double cone dressing wheel is proposed. In order to ensure the machining accuracy and balance the machining time, the iteration method of tangent's deviation is proposed and the nominal residual mean error is defined. In order to improve the versatility of the scheme, a double cone dressing wheel and a universal worm grinding machine are used to carry out the research. Considering the complex space position transition, the principle of virtual phase transition is proposed to achieve the equivalent replacement of the motion of the double cone dressing wheel by the motion of the crown worm wheel, which consists of the principle of virtual tool setting and the principle of rotating virtual center distance. Finally, a simulation experiments is carried out on the dressing process of the modification crown worm wheel. The result shows that this method can effectively realize the modification dressing process of the crown worm wheel for grinding face gear. [ABSTRACT FROM AUTHOR]

Creep-feed grinding of high-strength steel is prone to excessive wheel wear and thermal damage defects, which seriously affects the service performance of parts. To solve the above-mentioned issue, a creep-feed grinding test was carried out on high-strength steel using SG and CBN abrasive wheels. The grindability of high-strength steel was scrutinized in terms of grinding force, machining temperature and grinding specific energy. Moreover, the effects of operation parameters and grinder performances on the surface integrity of the workpiece such as surface morphology, roughness, residual stress and hardness were rigorously studied. The results indicate that, when the instantaneous high temperature in the grinding area reaches above the phase transition temperature of the steel, the local organization of the surface layer changes, leading to thermal damage defects in the components. The outstanding hardness and thermal conductivity of CBN abrasives are more productive in suppressing grinding burns than the high self-sharpening properties of SG grits and a more favorable machining response is achieved. The effects of thermal damage on the surface integrity of high-strength steel grinding are mainly in the form of oxidative discoloration, coating texture, hardness reduction and residual tensile stresses. Within the parameter range of this experiment, CBN grinding wheel reduces grinding specific energy by about 33% compared to SG grinding wheel and can control surface roughness below 0.8 µm. The weight of oxygen element in the burn-out workpiece accounts for 21%, and the thickness of the metamorphic layer is about 40 µm. The essential means of achieving burn-free grinding of high-strength steels is to reduce heat generation and enhance heat evacuation. The results obtained can provide technical guidance for high-quality processing of high-strength steel and precision manufacturing of high-end components. [ABSTRACT FROM AUTHOR]

Titanium alloys have many excellent characteristics, and they are widely used in aerospace, biomedicine, and precision engineering. Meanwhile, titanium alloys are difficult to machine and passivate readily. Electrochemical grinding (ECG) is an ideal technology for the efficient–precise machining of titanium alloys. In the ECG process of titanium alloys, the common approach of applying high voltage and active electrolytes to achieve high efficiency of material removal will lead to serious stray corrosion, and the time utilized for the subsequent finishing will be extended greatly. Therefore, the application of ECG in the field of high efficiency and precision machining of titanium alloys is limited. In order to address the aforementioned issues, the present study proposed an efficient–precise continuous ECG (E-P-C-ECG) process for Ti–6Al–4V applying high-pulsed voltage with an optimized duty cycle and low DC voltage in the efficient ECG stage and precise ECG stage, respectively, without changing the grinding wheel. According to the result of the passivation properties tests, the ideal electrolyte was selected. Optimization of the process parameters was implemented experimentally to improve the processing efficiency and precision of ECG of Ti–6Al–4V. Utilizing the process advantages of the proposed process, a thin-walled structure of Ti–6Al–4V was obtained with high efficiency and precision. Compared to the conventional mechanical grinding process, the compressive residual stress of the machined surface and the processing time were reduced by 90.5% and 63.3% respectively, and both the surface roughness and tool wear were obviously improved. [ABSTRACT FROM AUTHOR]

The grinding process has been evolving, in recent years, from a mere surface finishing operation to a high stock removal process. The current research work is focused on the development of new-generation single-layer diamond wheels that can accomplish the demanding high material removal rate (MRR) requirements with longer tool life without any wheel dressing. With the use of a novel coordinate-controlled grit patterning technique, single-layer brazed diamond wheels were fabricated with uniform and precise distribution of the abrasive particles, which enables the wheels to accommodate higher chip load without loading and to simultaneously possess stronger joint strength. The indigenously developed grinding wheel was tested under aggressive grinding conditions to machine Al-SiCP composite blocks up to a depth of 2.5 mm under a flood cooling environment. Grinding forces, real-time spindle power consumption, chip morphology, and post-grinding wheel morphology were investigated during the deep grinding experiments to evaluate the suitability of such wheels in stringent grinding conditions. Experiments were conducted up to a maximum uncut chip thickness of 5.4 μm and maximum specific MRR of 20.83 mm2/s. Specific grinding energy, as low as 10.8 J/mm3, was obtained at the grinding condition with an aggressiveness number of 19.04. The in-house developed patterned diamond grinding wheel could successfully grind the soft, sticky, and abrasive Al-SiCP composites without any trace of wheel loading or significant grit failures. In the end, the indigenously developed patterned grinding wheel was compared against a commercially procured competent single-layer grinding wheel while grinding the same Al-SiCP composite in high-pressure cooling conditions. [ABSTRACT FROM AUTHOR]

CVD rotary dressers are commonly used in the grinding process to dress wheels. To ensure the accuracy in profile of the dressed wheel, the CVD rotary dresser must achieve micron-level accuracy. However, CVD diamond is hard and brittle, making it difficult to achieve high-accuracy machining. In light of this, a graded grinding method is proposed in this paper to achieve precision machining of the CVD rotary dresser. The normal residual error is determined by measuring the distance between the actual profile curve and the target profile curve. Then, graded grinding is performed according to the normal residual error. In the grinding process, it is proposed that the grinding path can be planned according to the real-time profile of the grinding wheel. As revealed by the experiments conducted on a CVD rotary dresser for the NILES ZP 12 gear grinder, the profile accuracy (peak to valley, PV) of the CVD rotary dresser is improved from 14.79 to 1.57 μ m after grinding. The fluctuation of the arc radii of CVD diamonds in different phases along the circumference is reduced from 11.7 to 1.9 μ m. [ABSTRACT FROM AUTHOR]

Maraging steels are a family of Fe-Ni-Co-Mo alloys, and Ti addition to promote precipitation hardening with Ni and Mo. By adjusting the chemical composition and aging parameters maraging steels may be produced in classes of resistance from 200 to 400 ksi of ultimate tensile strength. As a concept, these alloys must present a combination of high strength and fracture toughness and are, for this reason, used in the manufacture of components and parts that must withstand large loads. Although maraging steels have good machinability as solution treated, the literature is scarce in studies on grinding machining processes of this type of steel with conventional grinding wheels. This work aims to analyze the results of residual stresses and surface finishing of maraging 350 steel machined by surface grinding process using a conventional sol-gel grinding wheel. Subsequently, the roughness of the machined surfaces was analyzed and residual stresses were measured by x-ray diffraction, using the sin2ψ method. The feed speeds increase in the range of 11-17 m/min contributed to a decrease in the magnitude of compressive residual stresses in the surfaces. The feed speeds and infeed did not exert a significant influence on the roughness results. [ABSTRACT FROM AUTHOR]

To enhance the surface quality of metal 3D-printed components, magnetic abrasive finishing (MAF) technology was employed for post-processing polishing. Experimental investigation employing response surface methodology was conducted to explore the impact of processing gap, rotational speed of the magnetic field, auxiliary vibration, and magnetic abrasive particle (MAP) size on the quality enhancement of internal surfaces. A regression model correlating roughness with crucial process parameters was established, followed by parameter optimization. Ultimately, the internal surface finishing of waveguides with blind cavities was achieved, and the finishing quality was comprehensively evaluated. Results indicate that under optimal process conditions, the roughness of the specimens decreased from Ra 2.5 μm to Ra 0.65 μm, reflecting a reduction rate of 74%. Following sequential rough and fine processing, the roughnesses of the cavity bottom, side wall, and convex surface inside the waveguide reduced to 0.59 μm, 0.61 μm, and 1.9 μm, respectively, from the original Ra above 12 μm. The findings of this study provide valuable technical insights into the surface finishing of metal 3D-printed components. [ABSTRACT FROM AUTHOR]

Magnetic elastic abrasive particles possess magnetism, low elasticity, and excellent grinding performance. Utilizing a double magnetic disk magnetic force tool for passivation can significantly enhance the efficiency and quality of passivation. Firstly, a mathematical model for the impact depth and volume on the tool is established. Secondly, using the simulation software ABAQUS, a simulation model is constructed to investigate the influence of grit size, quantity of abrasives, impact angle, disk rotation speed, and tool rotation speed on stress, energy, impact depth, and impact volume. Furthermore, the feasibility of the simulation and the reliability of the mathematical model are verified. [ABSTRACT FROM AUTHOR]

In the article, the authors present the concept of a mathematical model used to study the influence of the properties of the base materials used to produce an innovative abrasive wheel background on the operating characteristics of the final tool. This model will be used to verify various material and construction solutions. The article also covers the outcomes of research that confirm the developed model’s effectiveness in relation to the operation of lamellar grinding discs, as per their intended technological goal. The experiments involved surface grinding with grinding wheels constructed on chosen backgrounds. A dedicated research stand was designed to measure the temperature in the grinding zone without direct contact, using both new and used grinding discs. The tests incorporated various load levels applied by the grinding disc on the workpiece, as well as different working angles of the grinding disc. [ABSTRACT FROM AUTHOR]

The current network for the dual-task grinding wheel defect semantic segmentation lacks high-precision lightweight designs, making it challenging to balance lightweighting and segmentation accuracy, thus severely limiting its practical application in grinding wheel production lines. Additionally, recent approaches for addressing the natural class imbalance in defect segmentation fail to leverage the inexhaustible unannotated raw data on the production line, posing huge data wastage. Targeting these two issues, firstly, by discovering the similarity between Coordinate Attention (CA) and ASPP, this study has introduced a novel lightweight CA-ASP module to the DeeplabV3+, which is 45.3% smaller in parameter size and 53.2% lower in FLOPs compared to the ASPP, while achieving better segmentation precision. Secondly, we have innovatively leveraged the Masked Autoencoder (MAE) to address imbalance. By developing a new Hybrid MAE and applying it to self-supervised pretraining on tremendous unannotated data, we have significantly uplifted the network's semantic understanding on the minority classes, which leads to further rises in both the overall accuracy and accuracy of the minorities without additional computational growth. Lastly, transfer learning has been deployed to fully utilize the highly related dual tasks. Experimental results demonstrate that the proposed methods with a real-time latency of 9.512 ms obtain a superior segmentation accuracy on the mIoU score over the compared real-time state-of-the-art methods, excelling in managing the imbalance and ensuring stability on the complicated scenes across the dual tasks. [ABSTRACT FROM AUTHOR]

Grinding technology exerts an enormous effect on the surface quality of double helical gears, which are subject to stringent requirements in the aviation industry. This study presents a novel gear-gap-space-borrowing grinding method that diverges from existing techniques. Unlike conventional approaches, this method mitigates the design–manufacturing conflict by exploiting the opposing gear gap space. By borrowing space, the grinding wheel's size can be enlarged to enhance machinability, diminish the width of the undercut, and align with the lightweight design imperative of double helical gears. The relationship between the grinding wheel diameter and the design parameters of double helical gears is analytically established, leading to the formulation of design rules. These rules facilitate the rapid selection of appropriate grinding wheel sizes for the space-borrowing method. Additionally, through geometric modeling and experimental validation, the optimal gear undercut width and the maximum wheel diameter are determined. The validity and accuracy of the proposed method are verified by simulations and experimental investigations. The study quantitatively evaluates the benefits of this method, including the expansion of the grinding wheel size, the reduction in double helical gear weight, and enhancements in processing efficiency and quality, providing a comprehensive comparison and discussion of these improvements. [ABSTRACT FROM AUTHOR]

Electric spark dressing is an effective dressing method for metal-bonded diamond grinding wheel that offers high precision, high efficiency, and low cost. This study focused on the influence of discharge voltage, discharge current, and power pulse width on the surface morphology of the grinding wheel. The electric spark dressing experiments on metal-bonded grinding wheel and the grinding experiments of SiC ceramics were carried out, using a single-factor method. The surface morphology of the grinding wheel and the surface roughness of the workpiece were analyzed after removing a certain volume of SiC ceramics. It was found that larger electrical parameters could improve the dressing efficiency, and they could also cause adverse effects on the grinding wheel surface such as abrasive shedding, looseness, and bond melting recasting. In the early stage of grinding wheel, surface damage was serious, and grinding workpiece surface roughness was poor. These findings can serve as a practical reference for the selection of electric spark dressing for metal bond diamond grinding wheels. [ABSTRACT FROM AUTHOR]

To achieve high efficiency and low damage processing of ZrO2 ceramic ball valves, a method for the cup-shaped composite grinding wheel of ultrasonic vibration grinding system was proposed. Based on Mindlin's thick plate theory and cylinder longitudinal vibration theory, a cup-shaped composite grinding wheel including the stepped rod and cup tool head was designed. The theoretical error is within 4%. The influence of the length of the small end of the stepped rod and the diameter of the grinding wheel on the resonance frequency and ultrasonic amplitude was explored by the finite element method (FEM), and the structural parameters of the cup-shaped composite grinding wheel were optimized. The prototype verified that the error between the resonant frequency and the design frequency of the two kinds of cup-shaped composite grinding wheels after matching with the transducer was within 2%, and the maximum amplitude stable output was up to 8 μm. The ultrasonic grinding experiment of the ZrO2 ceramic ball valves was carried out. The results showed that ultrasonic grinding reduced the maximum height difference of the workpiece surface, reduced by 28% compared with conventional grinding (CG). The surface roughness was reduced to meet the actual processing requirements. The edges of the workpiece appeared serrated structure and micro-crushing phenomenon compared with CG, which may involve from low stiffness and suitable grinding parameters, especially the rotation speed limit of the fourth axis used for the workpiece rotation. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted dry grinding has been focused on to alleviate the cutting fluids' negative impact on environment, avoid the unnecessary waste, and reduce the manufacturing costs. However, this technology has not been used for grinding gear. In order to explore its effect, this study proposes a two-dimensional (i.e., 2D or elliptical) ultrasonic vibration-assisted dry grinding gear. In this method, the form grinding wheel was designed to vibrate along the longitudinal and radial directions based on the thin disc theory. The 2D vibration can be realized under a single excitation. Then, the grain kinematics and the characteristics of grinding force and surface roughness during elliptical ultrasonic vibration-assisted dry gear grinding (EUVADGG) were theoretically substantiated. Finally, the gear grinding experiment under EUVADGG and conventional gear grinding (CGG) was conducted to verify the analytical model. It has been analytical and experimentally shown that by superimposing the two two-dimensional ultrasonic vibrations, the tangential and normal grinding forces can be reduced approximately 40 and 30%, respectively. The surface roughness of gear teeth under various rolling angles can be assessed theoretically and experimentally, and it can be reduced by up to 25.6%. These findings strongly indicate that EUVADGG can achieve a lower grinding force and higher surface quality, and provide a valuable reference for grinding gear. [ABSTRACT FROM AUTHOR]

Ultra-precision machining for large-sagittal aspheric optical elements has become one of the research hotspots in the world's processing and manufacturing field in recent years. This paper mainly studies the processing of large-sagittal MgF2 aspheric optical components, analyzes the grinding tracks of two different grinding methods, and seeks the best grinding method. Experimental research was carried out on three milling modes in the rigid grinding process. In the processing method of pressed milling, the rotational speed of the workpiece has the most significant effect on the surface roughness. The surface roughness Ra can be reduced by reducing the grain size of the grinding wheel and adjusting the processing parameters. Through the cylindrical milling method, the surface roughness Ra measured with the D46 grinding wheel in the direction of rotation can reach the minimum, which is 0.7–0.8 μm. In the fine grinding stage, the circumferential grinding and endface grinding models are established, and the simulation analysis and experimental verification of the trajectory of the abrasive particles in the two grinding methods are carried out. The comparison shows that with endface grinding, the surface of the component is removed evenly in both directions. When the grain size is 28 μm, the surface roughness Ra∥ and Ra⊥ of face grinding are the smallest. Among them, Ra∥ is 0.0458 μm, and Ra⊥ is 0.0369 μm. This study is of great significance in improving the machining efficiency and accuracy of large-sagittal aspheric optical elements. [ABSTRACT FROM AUTHOR]

Metal-bonded grinding wheels offer particular benefits for the grinding of difficult-to-machine materials. Such wheels have superior dimensional and thermal stability, and more quickly dissipate the grinding heat. To in-process dress the metal-bonded diamond wheels of complex contours with the high-precision, wire electrical discharge dressing (WEDD) was used to remove the excess metal material on the surface. A prototype CNC machine tool based on the WEDD method was developed. Some novel designs were proposed to improve the dressing precision and performance. An air spindle with sub-micron runout was used to clamp the metal-bonded diamond wheels, which aims to decrease the runout of the dressed wheels. A specially designed wire guide was used to limit and minimize the positional fluctuations of wire electrodes. To dress the complex shape grinding wheel, the C-axis was designed to adjust the angle of the wire guide relative to the wheel to be dressed, which avoided motion interference between them. In addition, a high-low-voltage power supply was developed. By using the high ignition voltage, it is possible to form the discharge channel under a large gap, and thus the grinding wheel with the large diamond grain of the size 75~90 μm could be dressed. WEDD of a metal-bonded diamond grinding wheel was performed on the developed prototype machine tool. The experimental results demonstrated that the developed prototype could realize the dressing of the grinding wheel with a runout of less than 2 μm. The grinding experiments showed that a better grinding surface with Ra less than 0.8 μm was obtained. [ABSTRACT FROM AUTHOR]

A grinding wheel with orderly-micro-grooves is a new type of structured grinding wheel for grinding narrow-deep slots. It can improve the carrying capacity of the coolant in the grinding zone effectively. The wear and evolution of grains directly determine the sharpness of the grinding wheel, and this affects the grinding performance in terms of efficiency, surface integrity, and tool life. In order to design the grinding wheel for minimized wear in its use, this study elucidates the wear behaviors of the grinding wheel with orderly-micro-grooves in grinding narrow-deep slots. Through the comparative experiments of the grinding narrow-deep slot, the impacts of micro-grooves on the wear behaviors of the grinding wheel are evaluated, and the wear behavior of the grains on the cut-in edge, cut-out edge, cylindrical surface, and side surface is observed, respectively. The analysis of the grinding ratio, grinding force, and force ratio further verifies the analysis of the wear mechanism and the grinding performance. It is found that (1) the macro-fracture of grain on the cut-in edge occurred due to the large cutting thickness increasing the load of the grain; (2) the debonding phenomenon reduces the anchoring force of the grain, and this tends to pull out the grain on the cut-out edge; (3) due to the adhesion action of the micro-welds, the main failure behavior of the grain on the cylindrical surface is chip adhesion, and the bridge adhesion appears at the small inter-grain space; (4) grains on the side surface are less engaged in removing workpiece materials, the cutting depths of the grains in the middle and inner zones are ignorable, and attrition wears and micro-fractures occur on the grains on the side surface. The grinding force and force ratio variation further verifies that the grinding wheel with orderly-micro-grooves can achieve self-sharpening to maintain excellent grinding performance. [ABSTRACT FROM AUTHOR]

To improve the surface quality of GCr15 bearing ring grinding and to address the problem of difficult selection of dressing parameters in the grinding wheel dressing process, a study was conducted on the optimal selection of parameters when dressing white alumina (WA) grinding wheel with ultrasonic-assisted diamond roller using response surface methodology (RSM) and genetic algorithm (GA). Firstly, we analyzed the action characteristics of the dressing parameters during ultrasonic-assisted roller dressing (UARD). Secondly, the Box–Behnken method was utilized to design the UARD experiments for the WA wheel. On the basis of experimental data, a prediction model for the surface roughness (Ra) of bearing ring grinding was developed. The influence law of dressing parameters (dressing speed ratio qd, crossfeed velocity vfd, dressing depth ad, ultrasonic amplitude AL) and their interactions on Ra was qualitatively analyzed using RSM. Moreover, it was found that the dressing speed ratio (qd) and the ultrasonic amplitude (AL) were the main influencing factors on Ra. According to the optimization model of dressing parameters established by the improved genetic algorithm (IGA), we have obtained the optimal combination of dressing parameters: qd = 0.4718, vfd = 50.001 mm/min, ad = 42 μm, and AL=1.29 μm. A surface roughness of Ra = 0.4175 m was attained by grinding GCr15 bearing ring with WA wheel dressed with the optimal dressing parameters. Its surface quality was significantly enhanced, and its surface roughness was reduced by 9.77~52.68% when compared to prior optimization. Finally, the results of the validation experiments show a certain level of accuracy and reliability in both the surface roughness prediction model and the dressing parameter optimization model. The study results show that the dressing parameter optimization method can effectively improve the grinding quality of bearing rings and is of value for engineering applications. [ABSTRACT FROM AUTHOR]

Profile grinding of titanium alloys are now utilized for aero-engine structural components. However, owing to its low thermal conductivity, the grinding contact zone generates an intense deal of heat, resulting in burns on the surface of the workpiece. At the same time, titanium alloys are prone to abrasive adhesion at high temperatures, which aggravates the wear of the grinding wheel. A novel grinding wheel named profile rotating heat pipe-grinding wheel (PRHP-GW) was created to improve heat transfer in the grinding contact zone. Therefore, it is expected to achieve efficient heat exchange. The kind of working medium in the rotating heat pipe (RHP) is the key factor that might seriously influence the heat transmission capacity of the RHP-GW. In this article, the numerical simulation is applied to investigate the heat transfer characteristics of PRHP-GW from the perspective of different grinding heat flux, rotating speed and grinding wheel types (normal grinding wheel without RHP, PRHP-GW filled with deionized water, and PRHP-GW filled with diamond nanofluid). The results demonstrate that the heat transfer capacity of PRHP-GW is superior to that of the normal grinding wheel. In addition, the heat transfer performance of PRHP-GW filled with diamond nanofluid is better than the case filled with deionized water. [ABSTRACT FROM AUTHOR]

As the working interface of tapered roller bearing, the raceway surface quality directly affects the working performance and service life of bearings. In order to improve the surface quality of tapered roller bearing inner raceway grinding, improve the processing efficiency, and optimize the processing parameters, this paper conducted a study on the surface roughness of the inner raceway of the outer ring of tapered roller bearings during grinding, and established a prediction model for the grinding surface roughness. Firstly, the surface topography of grinding wheel was defined by using grinding wheel parameters. Secondly, the surface roughness prediction model of bearing raceway grinding was established based on the conversion relationship between bearing raceway grinding and surface grinding and the motion trajectory of particles on grinding wheel surface. Finally, the accuracy and rationality of the model were verified by using the current industrial process parameters of grinding bearing raceway through the grinding experiments. Based on the experimental and simulation results of grinding surface roughness, the influence law of grinding wheel linear speed, workpiece speed, and grinding depth on surface roughness was explored, and the surface roughness under high grinding wheel linear speed was predicted. The research results provide a theoretical basis for optimizing surface quality of tapered roller bearing outer ring inner raceway grinding. It is found that the surface roughness decreases with the increase of grinding wheel linear speed and the decrease of workpiece speed and grinding depth. The surface roughness at high linear speed of grinding wheel is predicted. The results show that when the workpiece speed is 300 rpm and the grinding depth is 0.3 μm, the surface roughness decreases from 0.259 to 0.208 μm as the grinding wheel linear speed increases from 60 to 100 m s−1, which can provide theoretical guidance for further improving the surface quality. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration–assisted grinding is an effective method for improving the surface quality of brittle and hard materials. The grinding force is one of the key factors affecting the surface quality of the machined surface, and this has been investigated both experimentally and theoretically. However, the influence of process parameters on grinding forces during longitudinal ultrasonic vibration-assisted grinding (LUVAG) of alumina ceramics has not been studied in depth. To investigate the effects of various parameters on the grinding forces of LUVAG of alumina ceramics, the kinematic theory of LUVAG was combined with the effective cutting trajectory of transient single-grain abrasives and the effective removal of transient material to develop a LUVAG alumina ceramic grinding force model and a LUVAG endface grinding force model. The experimental results showed that the grinding depth (ap) and table speed (vw) were positively correlated with the tangential grinding force (Ft) and the normal grinding force (Fn) (when vw increased from 400 to 1000 mm/min, Ft increased by about 10 to 15% and Fn increased by 30 to 45%; when ap increased from 5μm to 20μm, Ft increased by 20 to 30%, Fn increases by 25 to 30%). The ultrasonic amplitude (A) is negatively correlated with the grinding force (when A increases from 4 to 12μm, Ft decreases by 5 to 10% and Fn decreases by 25 to 30%). The grinding wheel speed (vs) was positively correlated with Ft but negatively correlated with Fn (when the grinding wheel speed increased from 1400 to 3500r/min, Ft increased by 20 to 36% and Fn decreased by 30 to 46%). According to the range analysis, Ft is the minimum when ap=5μm, vs =1400 r/min, A=12μm, vw=600 mm/min, and Fn is the minimum when ap =5μm, vs =3500 r/min, vw =600 mm/min, A=12μm. The results of the theoretical model calculations show that the predicted values of the grinding forces for the given parameters are in general agreement with the experimental results. The maximum relative mean error between the theoretical and experimental results was 12.3%, while the overall relative mean error was 4.94%. At the same time, it was demonstrated that the model can assist orthogonal experiments for factor selection and scheme optimization, which has important practical application value. [ABSTRACT FROM AUTHOR]

GCr15SiMn is a kind of bearing steel material with good physical and mechanical properties, which is broadly used in aerospace, automotive, and other advanced manufacturing fields. However, the harsh environment of the ordinary grinding (OG) process, including high grinding forces, high grinding temperatures, fast grinding wheel wear, and severe chip sticking, has led to the GCr15SiMn material being unable to be widely adopted. This paper introduces ultrasonic vibration grinding (UVG) technology to improve its machined surface quality. First, the formation mechanism of the two grinding methods was analyzed theoretically, and surface morphology of ultrasonic vibration grinding and ordinary grinding processing was analyzed by numerical simulation, while the effects of different processing variables on surface roughness were investigated experimentally. The results show that the simulated morphology is consistent with the experimental morphology. The grinding marks of UVG are wavy, wide, and shallow, and OGs are horizontal, with narrow and deep grooves. Also it was found that ultrasonic vibration grinding could improve the quality of the surface with lower roughness than normal grinding, and the surface roughness was reduced by more than 27%. The feed rate and spindle speed had significant effects on the surface roughness, accounting for 44.37% and 33.66%, respectively. [ABSTRACT FROM AUTHOR]

Ultra-high strength steel has a wide application of gear transmission systems in the aerospace field, owing to its high hardness, good impact toughness, fracture toughness, etc. Grinding is the important method to guarantee the final quality of ultra-high strength gears. However, the service life of grinding wheels is seriously shortened due on the numerous reinforced particles inside the hardened layer on gear surface, deteriorating the ground quality eventually. In order to resolve this issue, ultrasonic vibration-assisted grinding (UVAG) technology is applied, and then comparative trials are conducted between UVAG and conventional grinding (CG) during ultra-high strength steel machining. Here, the grinding performance, such as the variation of grinding force and temperature under two grinding modes, and the variation of tool wear morphology with the increase of grinding step are analyzed. Subsequently, the grinding surface quality of UVAG process is discussed in view of ground surface roughness and surface morphology. Results show that the CG possesses a rapid increase in grinding forces and temperature, and eventually, surface quality deteriorates gradually, whereas they have been improved in UVAG. In the range of experimental parameters, the force Fn and temperature of grinding maximum decreased by 35.5 and 39.2%, respectively, compared with CG. Moreover, due to the self-sharpening of abrasive grains, the UVAG process produces a finer ground surface quality. The research provides technical support for high quality and efficient machining of ultra-high strength aviation transmission gear. [ABSTRACT FROM AUTHOR]