Grinding Quality Research Articles

Automatic recognition of grinding quality of titanium alloy based on the convolutional neural network

Automatic recognition of grinding quality of titanium alloy based on the convolutional neural network

Vibration modal analysis of adaptive grinding and polishing tools

Abstract Adaptive grinding and polishing tools have a compact structure, fast response, and stable performance, and they can improve the efficiency of polishing and grinding large welded parts. The vibration frequency of the AGP600 adaptive grinding and polishing tool is abnormal after switching from the blade grinding head to the nylon grinding head, and the vibration is noticeable when the rotational speed is more significant than 4, 000 r/min, which seriously affects the quality of grinding. To analyze the cause of its vibration, this paper adopts HyperWorks to analyze the modal frequency of AGP600, carries out the vibration modal test, and analyses the reasons for the different vibration harmonic frequencies of AGP600. Finally, improvement measures for AGP600 are proposed, through which the vibration of AGP600 grinding tools can be reduced.

Effects of Harvest Time on Grinding Quality, Appearance Quality and Physical and Chemical Quality of Japonica Rice.

Harvest time is very important to rice due to its high correlation to rice yield, eating quality, etc.; however, the impact of harvest time on quality is still unclear. In this study, Nangeng 5718, a japonica rice planted in three regions in Jiangsu Province of China, was used to analyze and compare the milling quality, appearance quality, and physicochemical quality of japonica rice at different harvest times. The results showed that the 1000-grain weight of Nangeng 5718 exhibited no significant change at different harvest times (p > 0.05). The brown rice rate and rice yield at different harvest times were 82.3-85.4% and 66.3-76.1%, respectively. Harvest time had no significant effect on the brown of rice (p > 0.05). However, Nangeng 5718 planted in Nanjing had the highest rice yield at 50 days after heading, which was significantly different from that of rice harvested 65 days after heading (p < 0.05). Nangeng 5718 planted in Huai'an had the highest rice yield at 55 days after heading, which was significantly different from that of rice harvested 60 days after heading (p < 0.05). Harvest time had little effect on the length, width, and thickness of rice. The immature grain rate showed a decreasing trend with the increase in maturity. There were little differences in the protein content of Nangeng 5718 at different harvest times. Nangeng 5718 planted in Nanjing had the highest protein content at 50 days after heading. There was a significant difference between the rice harvested and the rice harvested 60 days after heading (p < 0.05). There were no significant differences between the other two regions (p > 0.05). The accumulated temperature in Nanjing was relatively high, and the RVA curve and RVA eigenvalues of rice varied greatly. The setback value of rice harvested at 50 days was significantly lower than that at 55 days and 60 days (p < 0.05). Rice has good gelatinizing properties. Therefore, timely harvesting and appropriate accumulated temperature could increase 1000-grain weight and rice yield, reduce the immature grain rate, and improve the gelatinization characteristics. Overall, the quality of Nangeng 5718 reached a good level when it was harvested 50 days after heading, with the accumulated temperature reaching 1051 °C. In fact, the harvest time should be chosen flexibly according to the weather conditions. Nangeng 5718 planted in Nanjing should be harvested earlier than 50 days, and rice from Huai'an and Lianyungang was of better quality when the harvest time was 50 days.

Understanding the machining mechanism in ultrasonic vibration-assisted nanogrinding of GaN

As a typical difficult-to-machine material, gallium nitride (GaN) crystals have the merits of excellent chemical stability and large bandwidth, which can be used in fields of space optical components, photoelectric devices, and electronic communication. The smooth surface of GaN is the basis of these applications. Grinding of GaN has thus drawn increasing attention. Furthermore, vibration-assisted nanogrinding has the potential to reduce grinding forces compared with conventional nanogrinding. In this study, ultrasonic-vibration-assisted nanogrinding of GaN with a single grit is conducted based on molecular dynamic (MD) simulations. The plastic deformation mechanism of GaN single crystals as well as the influence of grinding parameters, such as vibration period and amplitude, on the grinding outcomes are investigated. The MD simulations reveal that plastic deformation of GaN in the vibration-assisted nanogrinding process is dominated by amorphous transformation, dislocation, stacking faults, lattice distortion, and formation of nanocrystals. Furthermore, amorphous GaN atoms are mainly induced in front of the grit and at either side of the grinded groove. In the grinding process, the periodic fluctuation of grinding force components, which include the normal, tangential, and horizontal forces, are stable. A smaller grinding force is obtained when grinding with a small vibration period. Moreover, a small vibration period and large vibration amplitude lead to improved grinding efficiency, suppressing the grinding force and subsurface damage, and improving the grinding quality. The findings in this study facilitate an understanding of the plastic deformation mechanism of GaN single crystals and also provide guidance for parameter optimization during vibration-assisted nanogrinding.

Grinding quality evaluation and removal mechanism of resin-coated SiC and 2.5D-C-SiCs surface strategies

The paper proposes a strategy to enhance the processing quality of SiC and 2.5D-C-SiCs by coating epoxy resins on the material surface and edges, and then using resin-bonded diamond grinding tools for grinding. Epoxy resin acts as a protective layer that can absorb impacts during grinding, reduce damage, and thus improve the processing quality of the surface and edges. The experimental results show that resin coatings can effectively improve the surface quality of SiC and 2.5D-C-SiCs. By adjusting the RT and RE, processing parameters can be further optimized to achieve the best surface quality. This study provides new ideas and methods for enhancing the surface quality of SiC and 2.5D-C-SiCs materials, with important application prospects and practical significance.

Research on Cloud-Edge-Device Collaborative Intelligent Monitoring System of Grinding Wheel Wear State for High-Speed Cylindrical Grinding of Bearing Rings

Aiming at the problems of grinding wheel wear during high-speed cylindrical grinding, communication delays, and slow response during data acquisition, processing, and system operation, an intelligent online monitoring technology frame for CNC manufacturing units is proposed, incorporating a real-time-perception grinding mechanism and a cloud-edge device. Based on the grinding data and grinding wheel wear mechanism, a monitoring model using multi-sensor information fusion is constructed to assess the grinding wheel wear state. In addition, edge data acquisition and online monitoring software have been developed to improve the speed of data transmission and processing. Finally, based on the proposed framework, a cloud-edge device collaborative intelligent monitoring system for assessing grinding wheel wear during high-speed cylindrical grinding of bearing rings is constructed. It improves the grinding quality and efficiency, reduces the grinding cost, and incorporates remote control functionality.

A comprehensive investigation into the mechanism of belt wear influencing heat partition ratio through force and temperature analysis during robotic belt grinding Inconel 718

Robotic belt grinding serves as a pivotal method for achieving precision machining in re-manufacturing of aeroengine components made of Inconel 718. During grinding, the heat partition ratio (Rw) significantly influences the quality of the machined workpiece, which is affected by many grinding parameters. Belt wear, which is an unavoidable phenomenon during grinding, can substantially impact Rw. However, previous research works have paid little attention to the effect of belt wear. In this study, the variation of Rw with belt wear is comprehensively investigated by observing heat generation and heat input. Firstly, the belt wear behaviors are qualitatively and quantitatively described. Then, the impact mechanism of belt wear on force-related characteristics is analyzed to clarify the change rule of heat generation. Following this, the variations of temperature-related characteristics during belt wear are examined. Meanwhile, the heat input is obtained by the combination of finite element analysis and the inverse heat method. Finally, a rapid growth followed by a gradual decrease pattern of Rw with belt wear is derived and analyzed. The findings in this paper lay a crucial foundation for controlling the grinding quality during robotic belt grinding Inconel 718.

Thermal management in grinding of superalloys – A critical review

PurposeThis paper is supposed to provide a critical review of current research progress on thermal management in grinding of superalloys, and future directions and challenges. By understanding the current progress and identifying the developing directions, thermal management can be achieved in the grinding of superalloys to significantly improve the grinding quality and efficiency.Design/methodology/approachThe relevant literature is collected from Web of Science, Scopus, CNKI, Google scholar, etc. A total of 185 literature is analyzed, and the findings in the literature are systematically summarized. In this case, the current development and future trends of thermal management in grinding of superalloys can be concluded.FindingsThe recent developments in grinding superalloys, demands, challenges and solutions are analyzed. The theoretical basis of thermal management in grinding, the grinding heat partition analysis, is also summarized. The novel methods and technologies for thermal management are developed and reviewed, i.e. new grinding technologies and parameter optimization, super abrasive grinding wheel technologies, improved lubrication, highly efficient coolant delivery and enhanced heat transfer by passive thermal devices. Finally, the future trends and challenges are identified.Originality/valueSuperalloys have excellent physical and mechanical properties, e.g. high thermal stability, and good high-temperature strength. The superalloys have been broadly applied in the aerospace, energy and automobile industries. Grinding is one of the most important precision machining technologies for superalloy parts. Owing to the mechanical and physical properties of superalloys, during grinding processes, forces are large and a massive heat is generated. Consequently, the improvement of grinding quality and efficiency is limited. It is important to conduct thermal management in the grinding of superalloys to decrease grinding forces and heat generation. The grinding heat is also dissipated in time by enhanced heat transfer methods. Therefore, it is necessary and valuable to holistically review the current situation of thermal management in grinding of superalloys and also provide the development trends and challenges.

Grinding performance of MgF2 ceramics using biomimetic shark fin grinding wheels with different structure parameters

In the field of precision machining, with the popularity of brittle and hard materials such as infrared windows, it has become difficult for conventional diamond grinding wheels to effectively perform high-quality machining. The structuring of traditional diamond grinding wheels using a pulsed laser is a key technology to effectively improve the grinding quality of grinding wheels. In this paper, three new shark fin diamond grinding wheels (SFSGW) with different slot widths are designed based on the excellent drag-reducing and channelizing properties of shark dorsal fins. The grinding performance of traditional grinding wheels (USGW) and SFSGW on magnesium fluoride ceramics was compared. The effects of SFSGW on the surface quality, surface roughness and wheel damage of the workpiece were investigated. The results showed that the surface roughness of ceramics after grinding by SFSGW was reduced by 22.15 % compared with USGW, and the surface quality was better. Proper construction increases the material removal rate of the wheel and improves the wear resistance and service life of the wheel.

Study on the grinding surface quality of CNTs/2009AL composite material based on minimum quantity lubrication

Carbon nanotube aluminum matrix (CNTs/AL) composites are ideal lightweight and high-strength materials due to their excellent properties. However, the research on CNTs/AL composites only stays in the simulation and preparation stages, and no grinding research has been carried out. Revealing the grinding mechanism of CNTs/AL composites has far-reaching significance for the development of high-end equipment industries such as aerospace. Taking CNTs/2009AL composites as the research object, a minimum quantity lubrication (MQL) flat grinding platform was built for comparing the surface quality and defects of dry grinding and MQL grinding. The experimental results show that grinding wheel velocity was the grinding parameter that had the greatest influence on surface roughness in dry grinding and MQL grinding. The subsurface defects of dry grinding mainly included microcracks, burrs, pits, coatings, cavities, etc., and the rebound phenomenon of agglomerated carbon nanotubes. The subsurface defects of MQL grinding were only burrs and pits. The surface coating phenomenon of dry grinding increased with the increase in grinding wheel velocity, and the surface quality was improved. MQL grinding could significantly reduce grinding heat, reduce friction, and make the machined surface smoother. In dry grinding and MQL grinding, the subsurface damage depth decreased obviously with the increase in grinding wheel velocity. When the grinding wheel velocity was 30 m/s, the minimum subsurface damage depth of dry grinding and MQL grinding was 40.091 and 26.906 μm, respectively. Mastering the grinding mechanism of grinding CNTs/AL composites and the influence of grinding parameters on surface quality provides a basis for the selection of parameters and methods in grinding in industry. MQL grinding of CNTs/AL composites reduces the formation of many surface defects and improves the surface quality of the workpiece. It is an efficient, clean, and environmentally friendly processing method.

A green and precision compound machining method for glass micro components – Ultrasonic assisted electrochemical discharge grinding with multi-hole tube electrode

Glass is a widely used material in key fields such as Micro-Electro-Mechanical Systems (MEMS) due to its excellent properties. The existing non-traditional glass machining methods have problems such as high pollution, difficult operation, and poor sustainability, this article utilizes the effective combination of electrochemical discharge machining and grinding (named electrochemical discharge grinding, ECDG), by using NaHCO3 solution as electrolyte to achieve green machining. Utilizing ultrasonic vibration and multi-hole tube electrode to achieve precise and stable machining. Modeling and simulation analysis were conducted on the material removal rate and grinding force during the machining process, which profoundly revealed the joint improvement mechanism of spark discharge and ultrasonic vibration on grinding quality. First, a single factor experiment was used to preliminarily determine the machining threshold. Second, the Plackett-Burman experiment was used to screen key machining parameters. Then, Box-Behnken experiment was conducted on key machining parameters, and multi-objective and multi-factor optimization was performed to obtain the optimal combination of machining parameters. Compared with normal ECDG with cylindrical grinding electrode, the overcut is reduced by 8.3 %, the edge damage is reduced by 17.5 % and the surface roughness value is reduced by 70.6 %. Finally, by using the optimized combination of machining parameters, high-quality and stable machining of typical microchannel structures was achieved. The milling depth of the microchannel is 400 µm. The machining width is 1175 ± 5 µm. The surface roughness of the measurement area is 0.375 µm. The green, high-quality and stable machining of micro glass micro components further demonstrates the potential application of this compound technology.

Study of the influence of ore water saturation on its losses in the process of release in laboratory conditions depending on changes in the fractional composition

Purpose is to highlight the main results of the conducted experiments on the introduction of saturated water (watered) ore into laboratory conditions and to monitor the changes in losses as a result of the correction of the fractional composition, which simulates the improvement of the grinding quality. The methods. Methodology of the model experiment. Thecalculation of the obtained data by statistical and mathematical methods. Results. Presentation of the layout, initial conditions, and coverage of the sequence of the experiment, the creation of summary tables with the results and the construction of graphs are the result of a study to determine the level of water-saturated ore losses. Experiments have shown that as a result of the release of ore saturated with water, the loss of ore increases depending on its saturation by 5%, 5.5%, 6%, 7%, and the possibility of stable release becomes difficult. It was established that the release of ore at its saturation of 9% is impossible for laboratory conditions. Ore losses under these parameters range from 18.57% to 31.3%. As a result of the simulation of improving the quality of grinding, due to the correction of the fractional composition, it was possible to reduce the maximum losses of the mineral from 31.3% to 28.54%. Scientific novelty. Additional regularities of the process of release of water-saturated ores are established. It was determined that changing the fractional composition reduces the level of losses during the release of water-saturated ores. A change in such parameters as the release angle and the height of the formation of ridges due to the saturation of the ore with water and the correlation of the fractional composition was revealed. The theory of ore release gained further development. Practical significance. The method of releasing water-saturated ores in laboratory conditions has been improved. The creation of a methodology for calculating the level of losses during the development of deposits of water-rich iron ores makes it possible to use resource-saving technologies of hydro fracturing as an alternative to the classic drilling-explosive method of destroying a rock mass, or predicting the level of losses in the event of a sudden ingress of water into the treatment space.

Investigation on grinding temperature characteristics of CF/PEEK and material removal mechanism under temperature treatments

Carbon fiber reinforced thermoplastic (CFRTP) composites grinding temperatures could even exceed the glass transition temperature (Tg) of the material due to heat accumulation, combined with the unknown material removal mechanism, resulting in machining defects. To investigate the grinding temperature distribution and maximum temperatures of carbon fiber-reinforced poly-ether-ether-ketone (CF/PEEK) composites, as a typical kind of CFRTP, an analytical temperature model considering the anisotropy was proposed based on the moving heat source theory, verified by the experimental results measured by the infrared camera. Further, the material removal mechanism under temperature treatments (below and above Tg) was also studied. In high temperatures (above Tg), there were many defects on surfaces after grinding, including resin smearing, severe deflection, fiber distortion, and grinding wheel clogging. Therefore, to reduce the grinding temperature below Tg, the vortex tube cooling-assisted grinding method was proposed in the research. The proposed method could reduce the grinding temperature in the grinding area, suppress resin smearing, improve the surface quality, enhance the elastic modulus and nano-hardness of the workpiece, and reduce the clogging of grinding wheels. This study provided a better understanding of the CF/PEEK grinding temperature characteristics and suggested a method to improve the grinding quality.

Surface topography prediction of slider races using formed grinding wheel shape and material removal mechanism

Compared with the roughness, the three-dimensional (3D) topography parameters, surface microstructure geometric characteristics and other information can more fully evaluate the grinding quality of the slider raceway surface. In this paper, based on the 3D topography model of the abrasive particle distribution on the surface of the formed grinding wheel, the material removal mechanism between the abrasive particle and the raceway surface is analyzed. With the undeformed chip thickness distribution model as the intermediate variable, the 3D topography model of the slider raceway surface is established, and the model verification is carried out from the roughness and the geometric characteristics of the surface microstructure, respectively. At the same time, the surface microstructure is extracted from the topography model, and the effects of different grinding process parameters on the geometric characteristics such as the height to width ratio, depth to width ratio and distribution density of groove, convex peak and peak valley structures are studied. Results are shown that AS,TH increase from [0.05 0.6 μm] to [0.25 0.8 μm] and FGH grows from [0.11 1.05 μm] to [0.5 1.61 μm] when the grinding depth rises from 1 μm to 4 μm. AS, TH are firstly decreased from [0.17 0.61 μm] to [0.08 0.52 μm] and then increased to [0.26 0.78 μm], and the FGH declines from [0.34 1.01 μm] to [0.16 0.86 μm] and then increases to [0.51 1.38 μm] with the feeding speed is in [25, 28 m/min]. In addition, in the range of grinding wheel linear velocity [28, 34 m/s], the AS,TH decreases from [0.19 0.81 μm] to [0.1 0.55 μm] and the FGH decreases from [0.55 1.6 μm] to [0.2 1.1 μm]. This can prepare for the subsequent research on the impact of the topography characteristics on the friction coefficient and wear amount of the slider raceway surface.

Research on control strategy of abrasive belt type rail grinding for corrugation repair process

The rail corrugation will lead to noise pollution and abnormal vibration in the railway operation process which greatly influences the safety, comfort, and stability of the train operation. However, although the advantages of abrasive belt rail grinding in repairing rail diseases have been verified, there is still no relative grinding control strategy for rail corrugation repair process due to its characteristics of regionality and no grinding benchmark. Therefore, this paper analyzed the difference between the grinding process of rail corrugation and ideal rail surface, and established material removal model for repairing of rail corrugation. By comparing the average valid value of moving wave amplitude and the improvement degree of rail corrugation, the most suitable grinding control strategies for repairing different types of corrugation diseases were obtained, which can further improve the grinding quality and efficiency of abrasive belt rail grinding in repairing rail corrugation.

Process Optimization of Robotic Grinding to Guarantee Material Removal Accuracy and Surface Quality Simultaneously

Abstract Simultaneously guaranteeing material removal accuracy and surface quality of robotic grinding is crucial. However, existing studies of robotic grinding process optimization have mainly focused on a single indicator that solely considers contour error or surface roughness, while studies that simultaneously investigate the impact of contact force, spindle speed, feed rate, inclination angle, and path space on the material removal profile (MRP) and the surface roughness are lacking. This paper proposes a hybrid optimization method that considers dimensional accuracy and surface quality constraints. First, an MRP model that considers the coupling influence of the contact force, spindle speed, feed rate, and inclination angle is presented. Then, a surface roughness model that considers the inclination angle is established. Finally, the contact force, feed rate, inclination angle, and path space are simultaneously optimized to satisfy the hybrid constraints of MRP accuracy and surface roughness. The proposed method ensures maximum grinding efficiency while satisfying dimensional accuracy and surface quality constraints. The proposed method is verified on an industrial robotics grinding system with a pneumatic force-controlled actuator. The results show that the proposed method has higher profile accuracy and lower surface roughness than traditional methods.

Damage evolution and removal behaviors of GaN crystals involved in double-grits grinding

Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride (GaN) single crystals is an active and challenging research area. In this study, molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals; and the grinding force, coefficient of friction, stress distribution, plastic damage behaviors, and abrasive damage were systematically investigated. The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction. The grinding force, grinding induced stress, subsurface damage depth, and abrasive wear increase as the transverse interacted distance increases. However, there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length. Appropriate interacted distances between abrasives can decrease grinding force, coefficient of friction, grinding induced stress, subsurface damage depth, and abrasive wear during the grinding process. The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results, i.e. amorphous atoms, high-pressure phase transition, dislocations, stacking faults, and lattice distortions. The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.

Theoretical study of the process of grain materials grinding in agriculture machinery

This paper outlines the findings of theoretical investigations into the grain materials grinding process in agriculture, focusing on the particle breakdown occurring at the moving edge of the rotor groove relative to the fixed edge of the stator. The choice of grinding methods is influenced by the processed feed, its intended purpose, the adopted feed preparation technology, and the specific farm animals involved. The study highlights the significant variations in the grinding process due to differences in dimensional characteristics and strength properties of grain materials, which impact the selection of working chamber parameters and operating modes. The paper introduces a hexagonal rotary crusher design and technological scheme, which offers the flexibility to adjust the amplitude-frequency characteristics of the working elements, energy of the process, and grinding quality within a wide range. Further research on the system dynamics requires experimental studies of grain material grinders utilizing diverse destruction methods. This study aims to advance understanding of the grain materials grinding process and optimize feed processing techniques for improved livestock productivity and product quality.

Improving the design of the lining of the ball mill used to improve the quality of grinding

This article discusses the traditional ball mill lining used and the improved ball mill lining. Experimental data of the proposed and previous linings are presented. The economic effect of using a new improved ball mill lining design is shown. Also, based on the dimensions of the ores, their mechanical properties, the material and construction of the detail were selected first. It is recommended to use high-manganese steel alloy, if corrosion occurs due to friction, and chromium – molybdenum steel alloy as the material of the detail. As a result of changing the design of the part in the proposed technology, it can be seen that the ore crushing process has improved. As a result of the good ore grinding process, it became easier to extract metals and alloys from the crushed ore. In order to obtain research results, several studies were conducted using traditional and improved technology. Thanks to this technology, the economic efficiency of the production enterprise has increased due to the improvement of ore crushing, the increase of the service life of the part, the saving of resource energy, and the reduction of the time required for technical repairs.

Research on the path extraction method of shoe upper grinding based on 3D vision

Shoe upper grinding is a crucial step in the shoe manufacturing process, impacting both the bonding quality between the sole and the upper and the overall appearance of the shoe. Presently, many shoe companies rely on manual or semi-automated grinding methods for shoe uppers, resulting in low production efficiency and subpar grinding quality. This study proposes a 3D vision-based shoe upper grinding path extraction method for guiding a robotic arm to polish the shoe upper and address this issue. Initially, the RGB-D camera was used to obtain the point cloud data of the shoe surface, which was then preprocessed using point cloud filtering, smoothing and registration methods. Second, by combining RGB images with 3D point clouds, we propose a point-cloud region of interest (ROI) extraction method based on RGB information to obtain the feature point cloud of the shoe upper grinding line. Finally, we slice the feature point cloud of the shoe upper grinding line, extract the grinding points using an intersection algorithm, and fit them with a non-uniform rational B-spline curve (NURBS) to obtain the shoe’s upper grinding path. The research demonstrates that this method can effectively extract the shoe upper grinding trajectory curve, significantly reduce the time required to obtain the shoe upper grinding trajectory, and achieve good accuracy, with promising application prospects.