Wheel Grain Research Articles

Моделирование взаимосвязи силы резания с глубиной резания и объемами снимаемого металла единичными зернами при плоском шлифовании

Introduction. The model for calculating the cutting force is the basis of the modules of CAM-systems related both to the predicting processing errors on metal-cutting machines for specified grinding conditions, and to the optimizing all parameters of the technological mode (parameters of cutting modes, cutting tools, etc.). However, due to the lack of an adequate model for calculating the cutting force presented in engineering form, such modules have not yet been developed not only for flat grinding operations, but also for all other types of metalworking. It is challenging to obtain an adequate cutting force model for flat grinding operations because it is necessary to establish the interrelation between the machine parameters of the macrocutting modes (feed, cutting speed) of the grinding wheel with the parameters of the microcutting modes — the sets of cutting grains of the wheel associated with the plastic deformation of the metal in the shear zone, microvolumes of the metal being removed and the geometry of the cutting part of the abrasive grains. The purpose of this work is to develop a force model establishing the interrelation of the cutting force with the cutting depth and the volumes of the metal being removed by single grains and the wheel as a whole on the basis of the integration of microvolumes and microforces when metal being removed by the wheel grains. Research methods. The subject of the research is the mathematical modeling of the interrelation between the cutting force and cutting modes with the parameters of microcutting by a group of single grains, based on the equality of work when metal being removed of the same volume. The methodological basis of the research is the connection between the work (energy) spent on the plastic deformation of metal by a single grain, the intensity of stresses, the intensity of deformation rates and the volume of the metal being removed by the wheel as a whole, established by S.N. Korchak. Results and discussion. The result of the study is an analytical model that reliably and adequately establishes the interrelation between the cutting force and the cutting depth, cutting modes, wheel characteristics, physical and mechanical properties of the processing material, and other main technological parameters. The field of application of the results is the possibility of using the cutting force calculation model, presented in this paper, as a basis for the development of a module for a CAM-system (a digital twin of the machining), which would allow to perform the calculation and design of optimal technological parameters of the flat grinding operation, as well as cutting modes testing according to the criterion of processing accuracy of a parts batch, considering the influence of various variable factors and real processing conditions within the manufacturing process.

Numerical study of nozzle erosion in a hybrid rocket motor with wagon wheel fuel grain

Nozzle erosion directly affects the design quality of hybrid rocket motors, and it is a critical issue that restricts the practical application of hybrid rocket motors. In this paper, coupled numerical simulations of combustion flow field and thermochemical erosion of a graphite nozzle in a hybrid rocket motor with multi-port wagon wheel fuel grain are carried out. The results indicate that distributions of temperature, species and erosion rate in the flow field of hybrid rocket motor with wagon wheel grain show symmetrical characteristics related to the grain shape. The erosion rate decreases at first and then increases at the convergent section of throat insert, and it reaches the maximum value at the transition arc between convergent section and straight section of the throat. The maximum erosion rates at the central hole (position A) and outer edge of wheel holes (position B) are 0.0625 mm/s and 0.0902 mm/s, respectively. The erosion rate increases slowly in the straight section of the throat and it decreases gradually in the divergent section. Circumferentially inhomogeneous ablation occurs in the throat, and the erosion rate at the front end of throat straight section varies from 0.0484 mm/s to 0.0809 mm/s. The main oxidizing species causing thermochemical erosion are H2O and OH. At position A in the front end of throat straight section, erosion rates caused by H2O and OH are 66.50% and 30.48%, respectively. With the increase of oxidizer mass flow rate, the combustion chamber pressure increases linearly, and the erosion rate at position A in the front end of throat straight section gradually increases, but the growth rate decreases.

Application of the Coupled Eulerian Lagrangian method to the prediction of single‐grain cutting forces in grinding

AbstractContinuous technological advancements in the field of grinding technology and improved grinding tools have contributed to the development of high performance grinding processes. One example of such a process is internal traverse grinding (ITG) with electroplated cBN grinding wheels, where the tool consists of a conical roughing zone and a cylindrical finishing zone. Since the tool is fed in axial direction into a revolving workpiece, spindle deflections induced by varying process forces can lead to contour errors along the bore. Numerical simulations are a valuable tool to overcome the challenges associated with such high performance processes. Whenever spindle deflections need to be considered, accurate prediction of the process forces is paramount. Finite Element (FE) simulations have been widely used for the prediction of forces in cutting processes such as turning and milling, where only a small number of active cutting edges is considered, and where the geometry of these cutting edges is clearly defined. Grinding tools, on the other hand, contain a large number of grains with varying geometric characteristics. We recently proposed a multi‐scale simulation system for the simulation of ITG processes, where a geometric kinematic grinding simulation, based on a database of digitalised grains of a real grinding wheel, was used to determine the grain engagements [1]. The process forces were obtained from summation of the contributions of all active grains at any given time, based on a force model on the individual grain level. The force model takes the material removal rate and an approximation of the rake angle into account, and was calibrated via finite element simulations.In recent years, the Coupled Eulerian Lagrangian method (CEL), which is part of the commercial finite element software Abaqus, has been applied to simulate various cutting processes. No remeshing is necessary in this framework, and separation of chips from the workpiece can be modelled without element deletion. The application of CEL to the simulation of single grain cutting is therefore a promising approach to further improve the force model included in the process simulation of ITG. In this work, the kinematics of ITG are incorporated into a single grain cutting simulation, and the suitability of the CEL method for the problem is evaluated with a focus on the chip formation, separation and self‐contact between the chip and the workpiece.

The effect of heat flow from friction forces on the surface of the billets

In modern mechanical engineering, technical ceramics is finding increasing use. It has unique anti-corrosion properties and resistance to high temperatures. In most cases, the processing modes and characteristics of abrasive (diamond) wheels are selected experimentally, since there is no modeling of processing processes in the public domain. The article presents an experimental study of the surface of dissimilar materials under the influence of heat flow from the friction force of grinding wheel grains. The comparison of calculated indicators and the results of laboratory studies is given. It is concluded that the heat flow from the friction forces of the grains on the material does not cause the destruction of the polished surface. It is also shown that the flow density due to varying modes of grinding

On the issue of wearing mechanism of abrasive wheels during rails grinding

Issues related to the study and theoretical description of the mechanism of wear of abrasive grains on a grinding tool used in the machining of railway rails are reviewed in the article. Abrasive wheels often do not cope with the task of removing surface defects that partially remain on the treated surface. In this case, the rail-grinding train is forced to make several passes (3 …4 passes). This leads to a decrease in the productivity of the rail grinding process. It is noted that it is possible to achieve an increase in the productivity of grinding the rails by controlling the pressing force of the wheels to the machined surface of the rail head. It is shown that the role of the destruction of the wheel grains in the grinding of the working profile, and, consequently, the profile of the rail head remains undisclosed. These unresolved issues of the mechanisms of abrasive wheels wearing during rails grinding require their own special studies. The process of formation of the individual grain wearing surface during grinding is described. It is noted that the mechanism of wearing of abrasive wheels is predictable. In this work, theoretical studies are carried out and the process of wearing of the abrasive grain is idealized, as well as mathematical simulation of the process of wearing of an individual particle is carried out on the basis of the analysis. The size of the areas of grain wearing and the intensity of its growth is the most important factor that characterizes the wearing of the tool caused by the destruction and loss of grains from the bond.

Effect of the Granularity of Cubic Boron Nitride Vitrified Grinding Wheels on the Planar Technical Blades Sharpening Process.

The most widely used method for shaping technical blades is grinding with abrasive tools made of cubic boron nitride (cBN) grains and vitrified bond. The goal of this work was to determine the effect of grinding wheel grain size (cBN grain number according to FEPA standards: B126, B181 and B251), kinematics (grinding with the circumference, face and conical surface of the wheel) and feed rate (vf = 100; 150; 200 mm/min) on the effects of the grinding process evaluated by the cutting force of the blade after machining F, blade surface texture parameters (Sa, St, Smvr, Str, Sdq, Sdr and Sbi) as well as blade surface morphology. An analysis of output quantities showed that grinding wheels made of B181 cBN grains are most favorable for shaping planar technical blades of X39Cr13 steel in the grinding process.

ОСОБЕННОСТИ ПРОЦЕССА ОБРАБОТКИ СТАТИЧЕСКИ УПЛОТНЕННЫМИ АБРАЗИВНЫМИ СРЕДАМИ ДЕТАЛЕЙ ТИПА ТЕЛ ВРАЩЕНИЯ

The study objective is to find out an analytical dependence that correlates the operating parameters and the conditions of the finishing abrasive treatment with the roughness of the working surfaces of the parts, taking into account the shape factor of the manufactured parts.
 The tasks to which the paper is devoted include theoretical and experimental studies of the effect of the treated surface roughness on the technological modes and conditions of surface treatment of complex-profile parts in the medium of statically compacted loose abrasive, as well as in the development of a methodology for determining rational modes and conditions taking into account the shape factor of the machined parts and determining the achievable range of surface roughness.
 Research methods: theoretical studies are conducted on the basis of the main provisions of mechanical engineering technology, grinding theory, theoretical mechanics, theory of elasticity and plasticity. Experimental studies are carried out according to standard methods in production and laboratory conditions using certified instrumentation. The data obtained are processed using computer technology and presented in the form of empirical dependencies, convenient for practical use.
 The novelty of the work is in finding mathematical dependencies for calculating the pressure of a statically compacted abrasive layer on the surface of the parts being machined, taking into account the shape factor.
 Conclusions: Based on the calculated theoretical dependencies and experimental studies, it is shown that the work of micro-cutting with the microrelief of abrasive grains is approximately 1.5...2 times higher than the work of micro-cutting with the tops of abrasive grains of the grinding wheel. This allows to conclude that the machining of parts with a statically compacted loose abrasive, compared with grinding with a conventional grinding wheel, is a less energy-consuming process of removing material from the surfaces of the machined parts.
 The paper presents peculiarities of finishing parts with statically compacted abrasive media. The ratio of friction work and micro-cutting of the machining is shown. The nature of the contact interaction of abrasive grains with the treated surface is considered for the first time, taking into account the shape factor, and the rational range of final roughness is defined.
 The role of cutting elements of particles affecting the quality and productivity of machining is determined.

Diffusion of technologies: a longitudinal analysis of the Brazilian agricultural machinery sector

The importance of adopting technology innovations, mainly in food production contributing to food safety, is significant. This study aims to analyze the diffusion of agricultural production technologies in Brazil, mainly the use of wheel tractors, grain and sugarcane harvesters by producers. A quantitative approach is used to understand the market-level factors that influence the adoption of technologies. A supply response is estimated based on the Bass diffusion model. Data were collected from the National Association of Vehicle Manufacturers (Anfavea), which includes Brazilian monthly sales information for wheel tractors, grain and sugarcane harvesters. For each agricultural machine, 700 months of sales records were collected. The imitator’s coefficients were higher than innovators for all types of machines studied. The data showed that, for wheel tractors and grain harvesters, the diffusion curve presented S format (S-curves). However, sugarcane harvesters had a different pattern of diffusion. The distribution of the investigated technologies in Brazil was an imitation process; the market saturation was observed for wheel tractors and grain harvesters. This study helps to comprehend the supply response of agricultural machinery and presents suggestions for the diffusion of agricultural production technologies in Brazil. The experience has shown that several factors can constrain technology adoption, such as lack of credit, limited access to information and inputs, and inadequate infrastructure.

Effects of grain size and protrusion height on the surface integrity generation in the nanogrinding of 6H-SiC

The size and protrusion height of abrasive grains of a grinding wheel are not uniform, which can greatly influence the surface integrity generation of a ground component. The purpose of this paper is to explore such effects on the deformation and material removal mechanisms of 6H-SiC subjected to nanogrinding with the aid of molecular dynamics simulations. It was found that a nanogrinding process can fall into one or more of the following regimes with respect to material removal, i.e., no-wear, adhering, ploughing and cutting regimes, depending on both the depth of grain cut and size of abrasive grains. The plastic deformation in 6H-SiC starts with surface amorphization under the grinding stresses, followed by the activation of partial and perfect dislocations in the shuffle set of the material’s basal plane.

Hybrid rocket propulsion technology for space transportation revisited - propellant solutions and challenges

This paper presents the status of developments worldwide regarding use of hybrid rocket motors for space transportation. Historical roots are presented and reasons for revisiting hybrid technology after a few decades of limited interest are examined. Modern developments in sounding rockets, reusable suborbital systems and launch vehicles are discussed with particular focus on propellant technology. Various propellant combinations include use of liquid oxygen, hydrogen peroxide, nitrous oxide and nitrous oxide-oxygen mixtures as oxidizers. Different fuels are considered, taking into account performance, as well as inter alia obtainable regression rates. Results of preliminary calculations for vehicles using different propellant combinations are presented and analysed. This is compared with proposed configurations of hybrid rockets worldwide. Unresolved problems and several unknowns are pointed out, including hybrid rocket motor scalability issues, large motor combustion instabilities, combustion efficiency of metalized fuels, propellant volumetric performance and mass of fuel residuals in case of wagon wheel grain geometry. It is discussed whether new-space hybrid launch vehicles, while typically with limited stage reusability, may be cost-competitive in regard to other chemical rocket propulsion system developments. The paper is summarized with a list of potential future advances and technical opportunities. The main purpose of the conducted research is to provide a comparison between different hybrid propulsion technologies available, or currently under development, worldwide.

The Prospects of Abrasive Treatment of Tough-To-Machine Materials

Abstract In current conditions, great attention is paid to the quality of parts, which is in many ways determined by finishing operations of mechanical treatment, with surface grinding being the most widespread. Grinding process efficiency, abrasive tool wear intensity, machined surface quality and other features of grinding process depend on properties of the environment, where the cutting process takes place. Forced changing of conditions of this environment is one of the ways to control and optimize the grinding process, which can be reached due to finding new technological decisions. One of the most promising directions to solve this problem is the process of face grinding with discontinuous grinding tool and supply of cooling fluid or air in the cutting zone directly. Carried analysis of features of face grinding has shown that heat density can be decreased by the usage by grooved wheels with vortex air cooling or by supply of cooling-lubricant technological fluid. Obtained dependences of temperature field of part surface during grinding establish the influence of the length of working shoulders and grooves, vortex tubes number, outflow rate, temperature and flow rate of cold vortex flow of air. These data provide conscious control over the process of discontinuous face grinding by changing wheel grain size and grinding speed.

Effect of abrasive grain position patterns on the deformation of 6H-silicon carbide subjected to nano-grinding

A surface machined by nano-grinding is the result of the coupled activities of nano-cutting, nano-extrusion and nano-rubbing by multiple abrasive grains of a grinding wheel. With the aid of large-scale molecular dynamics simulations, this paper used a two-grain model to explore the influence of grain position patterns on the deformation of single crystal 6H-SiC. It was found that regardless of the space location arrangement of the abrasive grains (grain position pattern) and the gap magnitude between the abrasive grains (grain gap), the plastic deformation of 6H-SiC is signified by a thin amorphous layer in the immediate subsurface and dislocations in the deeper subsurface beneath the amorphous layer. However, the defective deformation details, including dislocation distribution and thickness of amorphous layer, vary with the grain position pattern and grain gap due to the different stress and temperature distributions generated during nano-grinding. In addition, under the consecutive pattern below a critical grain gap, both the average forces and surface profiles vary significantly with the grain gap. Under the simultaneous pattern, however, the average forces are mostly constant and the profile grooves are in parallel with each other. The investigation concludes that to achieve a high surface integrity with minimal subsurface damage in 6H-SiC, it is important to use grinding wheels of specific grain position patterns.

Parametric study of solid propellant slotted grain

One of the goals in solid rocket motor design is to have as large volumetric loading as possible keeping the basic requirements unaffected. Slotted grain can achieve this goal as it has the advantages of sliver-free and no stress-concentration regions that occur in other internal burning grains as star grain and wagon wheel grain. It has the disadvantage of exposing the motor wall to hot gases. In this paper, the geometry of slotted grain is discussed and the effect of design parameters (e.g., number of slots, dimensions of the slot, etc.) of slotted grain on grain burn back is explained. Also, a comparison between results and experimental data is performed.

Analysis of cutting forces during grinding of titanium alloy and corrosion-resistant steel by diamond, electrocorundum and cubic borine nitrid wheels

The object of research is the process of circular and surface grinding of titanium alloy and corrosion-resistant steel, namely, the cutting forces arising from mechanical processing. One of the most problematic areas in work is the selection of the required grinding modes, material and grinding wheel grain size. In the course of the experiment, we used samples of VT8 titanium alloy and 12Х18N9T steel, on which the grinding process was studied with wheels made of various materials (electrocorundum, cubic boron nitride (CBN), diamond). The values of the cutting forces Py and Pz were obtained in the latitude of permissible modes, which are most often used in circular and flat grinding, and can reach maximum values, respectively, Py=27 N, Pz=15.5 N. The data were obtained at a low wheel speed from electrocorundum, about 15 m/s and grain size 8. By reducing the grain size of the wheel, we get the effect of increasing the energy consumption of the grinding process, due to the increase in the values of the cutting forces. If we compare the cutting forces arising from grinding with different wheels, then the following can be noted. Compared to electrocorundum wheels, when using CBN wheels, the cutting forces are reduced by 20–25 %, and when grinding with diamond wheels (despite the high wear of the diamond wheel), the effect of cutting forces is reduced by 25–30 %. This is due to the fact that cutting conditions are the most favorable for diamond and CBN grains, which makes it possible to use more intense cutting conditions. The results of the study allow predicting the performance of the grinding wheel, reducing the energy consumption of production, and also adjusting the processing mode of the part to obtain the necessary quality indicators of the surface layer and the geometric dimensions of the part.

WITHDRAWN: Experimental investigation and optimization of surface grinding on EN31AM steel using Taguchi and ANN

Grinding is the machining processes; it is used to enhance the dimensional accuracy and surface quality of workpiece. The surface grinding process is affected by the different process parameters such as grinding wheel speed, material removal rate (MRR), number of passes, grinding wheel grain size, work piece speed, material hardness and depth of cut respectively. The feed and speed are the important factors because by increasing these factors will directly impacts on surface roughness (SR). Even though, the SR is reduced by improving the MRR. Surface grinding is the major process in metals cutting applications; it is widely used in finishing operations of cutting machining processes. SR and MRR are the significant output responses in the manufacturing relating to quality and quantity. In this article, an experimental investigation of surface grinding of EN31AM steel is studied to minimize the SR and maximize MRR for the optimization of grinding process parameters. In addition, artificial neural network (ANN) and Taguchi also employed for optimizing the input process parameters such as depth of cut, feed, and speed.

Simulation of internal material loads caused by multiple contacts in grinding with predominantly mechanical impact

Grinding processes and their mechanical impact on the workpiece material are mainly characterized by multiple contacts between the workpiece surface and the single abrasive grains of the grinding wheel. The numerical modeling approach presented in this work is capable of calculating internal material loads, e.g., stresses and strains during machining, for multiple contacts of abrasive grains utilizing the CEL-method. Different numbers of repeated consecutive contacts as well as varying machining parameters such as depth of cut ae and cutting speed vc are applied. The effect of different grain shapes is investigated by utilizing spherical, flat and pyramidal grains with comparable sizes. Thereby, the surface contact area is varied. The results reveal an effect of grain shape and depth of cut as well as a saturation effect of the corresponding material modifications, e.g., shown in the source stress and plastic strain depth curves, which is reached after a certain number of contacts with specific impact intensities on the workpiece surface including the particular material removal. The approach can be applied to show principle correlations between internal material loads and material modifications in grinding processes focusing on the mechanical impact on the surface integrity.

Modeling of regularities of change in profile sizes and wear areas of abrasive wheel grains during grinding

In the article the results of studies of the current state of the working surface of the abrasive tool, which is de-termined by the shape of the cutting edges, their number, distribution, shape of the tool, the presence of cutting edges and in the pores of the circle of particles of the processed material are presented. Form the cutting edges, their “sharpness” significantly affect the performance of the treatment process, the magnitude of the cutting force and the grinding temperature. Experimental studies were conducted to assess the adequacy of the obtained dependencies. As an indenter, we used cones made of alloy steel, high-speed steel and hard alloy with a vertex shape in the form of a paraboloid of rotation. In the process, in the plane of the vector cutting speed appears pad wear, which continually increases in a plane perpendicular to the velocity vector, form the top of the grain remains close to the form of a paraboloid, but the radius increases continuously. Comparison of calculated and experimental data shows that their deviations from each other do not exceed 9%, which allows us to recommend the obtained dependencies for practical application.

Cutting ability of abrasive grains in the processing of billets of plastic materials with the applying of ultrasonic vibrations

The research was carried out in order to identify the relationship between the intensity of sticking of the workpiece material particles on the abrasive grains (AZ) of the grinding wheel with the physical and mechanical properties of the grains and ultrasonic vibrations (UZK) used in the processing process. Numerical simulation of local temperatures during micro-cutting (scratching) of samples made of 3X3M3F steel with abrasive grains made of various materials, including with the imposition of a narrow band. The deformation of the bulk and the stresses resulting from this deformation acting on the connection of the bulk with grains from materials with different coefficients of linear expansion are calculated. It was found that with increasing difference in the coefficients of linear expansion of the materials of the billet and AZ, the stresses that contribute to the separation of the adhesive from the surface of the AZ increase. In the course of experimental studies, samples were micro-cut with single abrasive grains. We controlled the salting coefficient equal to the ratio of the area of nalip to the area of the blunting site at the gas station and the wear of grain. It was found that AZ from Elbor wear out and become salted to a lesser extent when grinding with the imposition of a narrow-gauge blank.

The wheels for final processing of parts

Microrelief characteristics of elastic abrasive wheel and parameters of its interaction with processed surface are studied (depth of penetration and quantity of penetrated grains). The received equitations of mathematical expectation of average depth of penetration of cutting logs and number of grains of elastic wheel being in contact allow to generate mathematical models of material removal and formation of parameters of roughness of the processed surface.

Desain dan Analisis Geometri Propellant Grain Configuration pada Roket Padat

This article examine mathematical model of propellant grain configuration to obtain the appropriate burning area in sonda rocket. Sonda roket is experimental rocket that created by Pustekroket LAPAN to support research on space sector with altitude as the target of assessment. Burning area for hollow grain, wagon wheel grain, star grain are analysed analytically through mathematical modelling. Than the results are compared by manual calculation using SolidWork. The results show that burning area of three types of grain did not show a significant difference between these two methods.