Flat Grinding Research Articles

Linear regression dependencies for determination of the roughness parameters of machined surfaces. Part 1. Turning, face milling, surface grinding, polishing

A scientific justification is given for choosing the minimum number of surface roughness parameters for different cutting methods: turning, face milling, flat grinding and polishing. Keywords:surface, cutting, roughness, correlation, regression dependencies zov20@mail.ru

THE TEMPERATURE FIELD THAT OCCURS IN THE CUTTING ZONE WHEN GRINDING WORKPIECES AND ITS EFFECT ON THE QUALITY OF THE METAL OF THE SURFACE LAYER

The issues related to the temperature in the contact zone during flat grinding of materials, the propagation of heat flow in the contacting bodies, the influence of processing modes on the intensity of the thermal pulses that occur, as well as the effect of COL on the temperature decrease in the cutting zone are considered. The results of theoretical calculations of the temperature in the cutting zone during flat grinding of steels and their comparison with experimental results are presented.

THE TEMPERATURE FIELD THAT OCCURS IN THE CUTTING ZONE WHEN GRINDING WORKPIECES AND ITS EFFECT ON THE QUALITY OF THE METAL OF THE SURFACE LAYER

The issues related to the temperature in the contact zone during flat grinding of materials, the propagation of heat flow in the contacting bodies, the influence of processing modes on the intensity of the thermal pulses that occur, as well as the effect of COL on the temperature decrease in the cutting zone are considered. The results of theoretical calculations of the temperature in the cutting zone during flat grinding of steels and their comparison with experimental results are presented.

Analysis of Roughness, the Material Removal Rate, and the Acoustic Emission Signal Obtained in Flat Grinding Processes

Analysis of Roughness, the Material Removal Rate, and the Acoustic Emission Signal Obtained in Flat Grinding Processes

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.

Indian Time: Temporality, Gender, Mobility

Indian Time: Temporality, Gender, Mobility

ИССЛЕДОВАНИЕ ОСТАТОЧНЫХ НАПРЯЖЕНИЙ ПРИ ПЛОСКОМ ШЛИФОВАНИИ ПРЕРЫВИСТЫМ АБРАЗИВНЫМ КРУГОМ

A technique for investigating residual stresses during flat grinding with an intermittent abrasive wheel is given. As a result of the study, it was found that tangential residual tensile stresses are formed in the direction of the cutting speed. Axial residual compression stresses are formed in the direction perpendicular to the cutting speed. It is shown that during grinding, residual stresses in the parts are formed from the action of force and thermal fields.

Automation for feed motion of flat grinding machine improve accuracy and productivity machine

In the manufacturing industry, the suface for high quality and gloss are often processed by semi – finishing and finishing on the grinding machine after roughing or heat treatment. To improve machining accuracy, to increase labour productivity and product quality, it depends very much on the opertiong status and accuracy of the machine. Therefore, the article has introduced the solution for automation feed motion on a flat grinding machine base on mechanical system of machine, that can automatically control the machining process and integrated of programming to process gringding details with complex frofiles, improve the accuracy of the machine. The research results are carried out on the active real flat grinding products, high quality surface grinding, reducing pocessing time and improving effect opertating of the machine.

Algorithm of Determination of Optimal Conditions for Low-Rigidity Prismatic Workpieces Flat Grinding

The flat grinding of low-rigidity prismatic workpieces side surfaces is investigated. Algorithm of determination of optimal conditions for low-rigidity prismatic workpieces flat grinding has been developed. The optimization of parameters in the range of allowable values is carried out with the view of ensuring the maximum process efficiency. Mathematical models for determination of maximum elastic deformation of prismatic workpieces when fixing and machining are presented.

A Note on the Change in the Surface Quality Characteristics during Flat Grinding of Titanium Intermetallic with Shape Memory Effect

Ti-based intermetallic compounds are characterized by low machinability, therefore, to obtain accurate dimensions and shape of the surface grinding and Wire EDM are used. The unique properties of NiTi intermetallic alloys are largely influenced by structural phase transformations and variations in microhardness caused by processing accompanied by thermal phenomena. Having an understanding of the physics of the process, it is possible to counteract negative effects, which helps to preserve thermomechanical properties of the final NiTi products. Accumulation of knowledge about the quality of processing with various abrasive tools is part of the larger research presented in this article. Samples of titanium nickelide with a temperature Af=+25 0С were abraded with ordinary and high porosity SiC wheels. The article studied phase transformations using X-ray diffraction analysis and microhardness. The experimental data were processed using mathematical statistics. X-ray diffraction patterns and microhardness analysis showed that a significant effect on the structural transformation and corresponding increase in microhardness is exerted by grinding with green SiC wheels with normal porosity caused by an increased thermal effect on the surface. Simultaneously, the impact of Wire EDM process on microhardness in preparing workpieces for grinding was evaluated. It was established that grinding of Ti-based intermetallic compounds with memory effect should be performed by SiC wheels with an open structure of high porosity.

ASPECTS REGARDING THE CUTTING CAPACITY OF DIAMOND DISCS USED IN THE FLAT GRINDING OF HARD GRANITE AND BASALT MINERAL MATERIALS

The paper presents how to determine the partial and global cutting capacity (CC) based on technological evaluation criteria (sustainability, specific energy consumption, cutting forces, roughness) and technical economic criteria (grinding productivity and cost). The theoretical-experimental model that allows the determination of the global CC for diamond discs takes into account the specific features of these super abrasive tools and the cutting process for flat grinding of hard mineral materials granite and basalt. Also, are presented the characteristics of diamond discs, the experimental stand and the factorial plans used in the experimental part.

АНАЛИТИЧЕСКОЕ ИССЛЕДОВАНИЕ СИЛ ШЛИФОВАНИЯ ПРИ НАЛОЖЕНИИ УЛЬТРАЗВУКОВЫХ КОЛЕБАНИЙ С ВЫСОКОЙ АМПЛИТУДОЙ

An analytical study of the grinding forces under the superposition of ultrasonic vibrations (UV) with an amplitude providing intermittent contact of the abrasive grains of the circle with the workpiece, was performed. The grinding force was defined as the sum of the forces from the individual grains of the circle located on different sections of their trajectory relative to the treated surface of the workpiece. When the grain is moved in the contact zone of the circle with the workpiece, its operating mode changes and depends on the phase of vibrations. Moving relative to the workpiece, the grain performs plastic deformation and micro-cutting, on part of the trajectory it can come out of contact with the workpiece. The sequence of implementation of these modes depends on the phase of the UV. The components of the grinding force were calculated as the arithmetic mean of their values determined at different vibration phases. The coordinates of the points on the grain movement trajectory corresponding to the change in its operating mode were determined numerically. Numerical simulation of forces using the obtained dependences and experimental study were performed for flat grinding of 12H18N10T steel blanks by the periphery of the circle. The frequency of the superimposed UV is 18.6 kHz; the amplitude of the oscillations in the direction coinciding with the axis of the grinding wheel is 10 microns. To impose vibrations on the workpiece in the course of experimental studies, a device was used in which the workpiece is one of the links of the vibration system. It is established that the difference between the calculated and experimental values of the components of the grinding force is 8 ... 15%. With the imposition of a UV, grinding force is lower by 20 ... 21% than with out their use.

ტექნიკური კერამიკის ფილების ბრტყელი ზედაპირებისა და პერიმეტრის ალმასური ხეხვის სპეციალური ჩარხი

In developed countries, material scientists are working intensively to create high-strength (metallic) technical ceramics. If such a material is created, it will be possible to manufacture such parts of power units (transmissions) of cars as shafts, turbines, etc. In the future, the latest composite ceramic materials with unique properties will gradually replace metals in the production of machine parts. Special device for diamond grinding of articles from composite, non-metallic, brittle materials (technical ceramics on the base of SiC, Al2O3; polycrystalline diamond, composite – Si + SiC + diamond etc.) is a universal flat grinding machine that enables to grind with high productivity both supporting main surfaces and lateral side surfaces – perimeter of an article of prismatic shape. It is also possible to grind substrates of other configurations – round, oval, etc. Grinding depending on sizes of articles can be done of both single and group of articles. The grinding takes place by the means of spring feeding of the article by pneumatic system that enables to prevent breakage of articles from brittle non-metallic materials in process of machining and obtain maximum high quality of the machined surface.

Peculiarities of the Grinding Process of a Gear Hob Helical Rake Face

Abstract This paper presents a study regarding the gear hob’s rake face grinding possibilities and its consequences. A simple theoretical lined surface is considered. The mathematical model of the reciprocate meshing of surfaces was applied. It was proven that the proposed form of the rake face cannot be obtained because an undercut of inacceptable extent occurs. It is also proven and sustained by CAD modeling that using a simplified, flat grinding disk, the undercut is avoided, but the phenomenon of transection appears.

Повышение эффективности плоского глубинного шлифования

There is considered a possibility of effectiveness increase of machinery billet flat deep grinding at the expense of high-speed machining use and also grinding on an automatic cycle of grinding mode changes. The application of high-speed deep grinding, for instance, slots or profiles of turbine blade locks allows rejecting their preliminary milling, carrying out single position machining on one machine which increases machining accuracy and its capacity.

Cutting forces when grinding parts from martensite aging steels with highporous abrasive, borazon and diamond wheels

Object of research. The article investigates the cutting forces when grinding martensitic-aging steels with highly porous grinding wheels.
 The problem to be solved is the regularities of the change in the magnitude of the cutting forces when grinding maraging steels with highly porous CBN wheels.
 Main scientific results. The studies were performed on martensiticaging steel H8K18M14. As a result of the experiments, it was found that when grinding wheels made of materials such as electrocorundum, CBN (borazon) and diamond, a significant role is played by the values of the cutting force, which increase during processing.
 During the experiment it was found out: the cutting forces Py and Pz in the width of the allowable modes, which are most often used in circular and flat grinding, can reach the following values: with the structure of the wheel 26 come to values from 2.714N to 30.721 and with the structure of the wheel 40 come to values from 2.49N to 28.185N.
 Reducing the grain size of the wheel, let’s obtain the effect of increasing the energy costs of the grinding process, by increasing the magnitude of the cutting forces.
 If to compare the cutting forces that occur when grinding different wheels, it is possible to note the following: in comparison with electrocorundum wheels when using wheels with KNB cutting forces are reduced by 20-25 %, and when grinding with diamond wheels, the effect of cutting forces is reduced by 25 - 30 %. When grinding with highly porous wheels, the cutting force is 15-20 % higher than when grinding with wheels of normal porosity.
 The area of practical use of research results-grinding technology for maraging steels.
 Innovative technological product – relationship between processing modes and the magnitude of cutting forces when grinding maraging steels.
 Scope of application of an innovative technological product-mechanical engineering technology

ELASTIC DEFORMATIONS DURING FLAT GRINDING OF LOW-RIGIDITY PRISMATIC WORKPIECES

The flat grinding of low-rigidity prismatic workpieces side surfaces is investigated. Mathematical models of the maximum elastic deformation of prismatic workpieces during fixing and machining have been developed. Contact deformations of the surfaces of the workpiece and the machine table are taken into account. An experimental verification of the developed models was carried out.

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.

Study of Metal, Silicon Carbide Crystals and Ceramic Bond Transfer to the Surface of Titanium Alloy during Grinding

The high adhesive activity of titanium alloys in interaction with abrasive materials is the main cause of poor grinding treatment. The most common abrasive material for grinding titanium alloys is silicon carbide. Silicon carbide wheels operate primarily in self-sharpening mode. Wear of the abrasive tool in the self-sharpening mode occurs as a result of brittle destruction of the fret. The purpose of the study was to determine experimentally the crystalline wear products of an abrasive tool, made of silicon carbide, on the treated surface during grinding of a titanium alloy. Samples of VT9 titanium alloy were processed by flat mortise grinding by a wheel of silicon carbide with the use of VOLTES coolant and the characteristic of the abrasive tool - 64CF80L7V. The treated surface was examined on the electron microscope Versa 3D Dual Beam. The condition of the treated surface testifies to the intensive adhesive interaction of the titanium alloy with the abrasive tool. The thickness of the metal deposits reaches 3 microns. As a result of morphological analysis, objects are identified on the treated surface, the appearance of which allows us to attribute them to crystals. The chemical composition of the selected objects was determined by a microprobe analysis in a microscope camera. On the basis of the conducted researches, a presence on the grinded surface of silicon carbide crystals of various sizes and a ceramic ligament is established.

ВЫБОР МАРКИ СПЛАВА, ПОКРЫТИЯ И ГЕОМЕТРИЧЕСКИХ ПАРАМЕТРОВ РЕЖУЩЕЙ ПЛАСТИНЫ ДЛЯ ТОРЦЕВОГО ФРЕЗЕРОВАНИЯ ВЫСОКОУГЛЕРОДИСТОЙ ЗАКАЛЁННОЙ СТАЛИ 95Х18-Ш

The application of hardened steel parts for the purpose of wear-resistance increase becomes increasing spread in different branches of mechanical engineering. In view of high hardness of the work surface of parts, finishing is carried out by flat grinding. 
 During the hardened steel grinding there are formed burns, cracks, admixtures of abrasive particles in the work surface which are inadmissible defects in a surface layer of critical parts mounted in the fuel unit of an aviation engine. 
 The analysis of literature and company experience has shown that after thermal treatment instead of finishing is necessary to use surface finishing by a face milling method, but there are no sufficient recommendations for tool choice and cutting modes to date. Jointly with the educational department there are carried out theoretical researches of cutters for the face milling of the “selector housing” mass-produced parts consisting of corrosion-resistant 95H18-Sh steel with the hardness of 59÷61 HRC. In the paper there is considered a chemical composition of 95H18-Sh steel, a method for manufacturing a cast, its physical, mechanical and chemical properties. 
 Taking into account data obtained for the face-milling cutter installation on the frame there was chosen Sandvik Coromant material for the replaceable cutting insert the base of which consists of hard alloy 1010 with PVD coating. 
 Later on there was carried out selection of basic geometrical parameters and characteristics of a cutting plate and also a micro-geometry of a major cutting edge and a tip. Mass-produced replaceable through-away plates with R245-12 T3 M-PM number of 1010 hard alloy and PVD coating were obtained from the catalog of Sandvik Coromant company. At the end of the work a conclusion was drawn that the application of face milling will allow ensuring the requirements to the design documentation of the product, decreasing thermal and power stress of the process, increasing productivity, surface quality and excluding the necessity in abrasion, and the investigation results are applicable to the fulfillment of the complete factor experiment and computation of a simulator with the definition of the impact of variable factors upon a response function.