Surface Layer Of Parts Research Articles

Hardening technology designing of parts by dynamic surface plastic deformation methods

Calculation dependences are proposed, which allow substantiating the quality parameters of the surface layer of parts hardened by dynamic methods of surface plastic deformation from the standpoint of the energy approach. An algorithm for designing a hardening treatment technology has been developed based on the energy assessment of the quality parameters of the surface layer and the fatigue life of parts operating under cyclic loads.

Influence of oblique geometry of cutting inserts of finishing face mills on cutting forces

The feasibility of using face milling for the final formation of the parts surface layer is confirmed by a large number of scientific works. At the same time, there are significant advantages of technological processes using face mills for oblique cutting, equipped with superhard materials, with a spiral-stepped arrangement of cutting inserts. This work is devoted to the study of the influence of the inclination angle of the oblique face mill cutting edge on the cutting forces when processing the workpiece flat surface made of gray cast iron and carbon tool steel using the Deform-3D program. The influence of the cutting edge inclination in the range from 0 to -45º on the smoothness of penetration of the face mill inserts into the workpiece is discussed.

The selection and development of tribological coating

The strategy and methodology for selecting of optimal surface treatment for a given tribological application are the main objectives of study. The classification of main methods of coating processes and surface modification is given. The scheme of development of operation technology of surface treatment and coating deposition is proposed. The main initial data: the structure of tribological system (TrS); individual properties of TrS parts; lubricant properties; method of lubrication of TrS parts; properties of sur­rounding environment; external influences on TrS; technological limitations on TrS parts treatment; managerial and economical limitations. The selection of surface technology method is including the next successive steps: the preliminary analysis of TrS part interaction; development of models of friction and wear process of TrS parts; the choice of rational values of parameters of surface layers of TrS parts; the choice of rational composition and structure parameters of surface layers of TrS parts; the choice of rational technological route and methods of surface treatment of TrS parts; the experimental examination of surface strengthened materials and TrS and correction of surface treatment technology

Devising criteria for the authenticity of historical cold weapons based on X-ray fluorescence analysis of their surface

This paper reports the results of studying the chemical composition of the surface of 4 objects of cold weapons of the 19th and early 20th centuries, made of iron – bayonet knives and sabers. This makes it possible to establish the signs of authenticity of cold weapon samples made of iron in that chronological period. An authentic procedure has been proposed for examining the chemical composition of the surface of historical objects of cold weapons by rubbing the samples with cotton wool swabs and their subsequent investigation. This makes it possible to explore objects of cold weapons, whose size is large, as well as simplify the very procedure for studying objects of historical and cultural value. Using the X-ray fluorescent chemical analyzer Expert Mobile, chemical elements were found at the surface of samples of cold weapons made of iron. The presence of such elements is the result of the process of re-crystallization and self-purification of metal during a long history of its life. Elements found in almost every rubbing sample were identified: calcium, ferrum, zinc, cuprum, and chlorine. The studies of cold weapons samples testify to the heterogeneity of the composition of patina formations on their surface, which confirms the authenticity of ancient objects. In addition, the studies have shown a difference in the chemical composition of surface layers of different parts of individual samples of antique cold weapons, which may indicate different times or different technology for their manufacture. The fluorescence spectra of the obtained rubbing of individual samples of cold weapons were compared with "pure" material, which made it possible to identify elements removed from the surface of objects. The study results are important indicators to confirm the authenticity of cultural monuments and the technology of their manufacture in the past.

Effect of Wave Thermal Deformation Hardening on the Microhardness of the Surface Layer of Steel Parts

Preliminary experimental studies of the possibility of increasing the microhardness of the surface layer of the material by the method of wave thermodeformational hardening on the example of austenitic steel class 12X18H10T are carried out. Comparative studies on the hardening of the material with and without heating were also carried out. The possibility of a significant increase in the maximum microhardness in the range from 25 to 50% at a depth of up to 0.6 mm, depending on the hardening mode, in comparison with the deformation treatment in the “cold” state is established. The area of technological modes providing the maximum increase of microhardness in the surface layer is revealed, in particular, the temperature of the treated surface should be in the range from 200°C to 400°C. At the same time, the achieved microhardness values exceed the initial one by 1.8…2.2 times, depending on the processing modes. It is also found that when choosing rational processing modes, the combined wave thermal strain hardening can significantly increase the hardening depth to 4.2 mm of the surface layer compared to the initial state. To establish the possibility of improving the performance of combined processing requires additional research.

Determination of the endurance limit of the surface layer of a part after processing with a blade tool

The dependences of the quality indicators of the surface layer of parts on the fatigue strength are analyzed. The dependences are given, taking into account both the quality indicators of the surface layer of the part after processing with the blade tool, and the parameters of the processing mode. Keywords: surface layer, surface roughness, residual stresses, work-hardening depth, endurance limit, blade tool processing. technology@rsatu.ru

Повышение эффективности поверхностно-термического упрочнения деталей машин в условиях совмещения обрабатывающих технологий, интегрируемых на единой станочной базе

Introduction. In the manufacturing industry, there is a particular interest in the development of a new type of technological equipment, which makes it possible to implement methods for modifying the parts surface layers by processing it with concentrated energy sources. The combination of two processing technologies (mechanical and surface-thermal operations) in the conditions of integrated equipment makes it possible to neutralize the disadvantages of monotechnologies and obtain new effects that are unattainable when using technologies separately. The use of hybrid machine tools in conjunction with the developed technological recommendations will allow achieving a multiple increase in the technical and economic efficiency of production, resource and energy saving, which in turn will contribute to an increase in the competitiveness of products and the renewal of the technological paradigm. Purpose of work: increasing productivity and reducing energy consumption during surface-thermal hardening of machine parts by exposure to concentrated energy sources under conditions of integrated processing. Theory and methods: studies of the possible structural composition and layout of hybrid equipment during the integration of mechanical and surface-thermal processes are carried out taking into account the main provisions of structural synthesis and the components of metalworking systems. Theoretical studies are carried out using the basic provisions of system analysis, geometric theory of surface formation, design of metalworking machines, finite-element method, mathematical and computer simulation. Mathematical simulation of thermal fields and structural-phase transformations in the case of HEH HFC is carried out in the ANSYS and SYSWELD software packages, using numerical methods for solving the differential equations of unsteady thermal conductivity (Fourier's equation), carbon diffusion (Fick's second law), and elastoplastic behavior of the material. The verification of the simulation results is carried out by conducting field experiments using: optical and scanning microscopy; mechanical and X-ray methods for determining residual stresses. In the study, Uone JD520 and Form Talysurf Series 2 profilograph-profilometers are used to simultaneously measure shape deviations, waviness and surface roughness. Surface topography is assessed using a Zygo New View 7300 laser profilograph-profilometer. The microhardness of the hardened surface layer of parts is evaluated on a Wolpert Group 402MVD device. Results and discussion. An original method of structural-kinematic analysis for pre-design research of hybrid metalworking equipment is presented. Methodological recommendations are developed for the modernization of metal-cutting machine tools, the implementation of which will allow the implementation of high-energy heating by high-frequency currents (HEH HFC) on a standard machine-tool system and ensure the formation of high-tech technological equipment with expanded functionality. A unified integral parameter of the temperature-time effect on a structural material is proposed when the modes of hardening by concentrated heating sources are assigned, which guarantee the required set of quality indicators of the surface layer of machine parts, while ensuring energy efficiency and processing productivity in general. It is experimentally confirmed that the introduction into production of the proposed hybrid machine tool in conjunction with the developed recommendations for the purpose of the HEH HFC modes in the conditions of integral processing of a “Plunger bushing” type part in relation to the factory technology allows increasing the productivity of surface hardening by 3.5 ... 4.1 times, and reduce energy consumption by 9.5 ... 11.3 times.

Современные аспекты автоматизации научных исследований качества поверхности деталей машин с использованием методов машинного обучения

A procedure is shown for the analysis of material structure in the parts surface layer manufactured through ion-plasma sputtering allowing the allocation and estimate automatically layers according to dislocation uniformity. A procedure is offered for the assessment of surface roughness on the basis of probabilistic-statistic classification of Talyrond trace allowing the definition and estimate automatically the peculiarities of a surface profile.

Комплексные металлофизические исследования конструкционных сталей после двухкомпонентного диффузионного упрочнения на основе бора

The studies of the structure, phase composition and microhardness of 45; 40X13 and (25...30) CMT steels during hardening in mixtures containing boron, boron and silicon, as well as boron, silicon and aluminum, are presented. Boration was carried out at a temperature of 890°C for 3 hours. The results of the study show that as a result of boration, the layer thickness is greater than in the case of borosiliconizing and boro-alumino-siliconizing, however, the needles of the boride phases are sharper. By obtaining diffusive layers that differ in structure with different phase ratios FeB, Fe2 B, Fe3 Si, it is possible to significantly influence the resistance to brittle failure of the surface layers of parts that are operated under real conditions in friction pairs under periodic or constant shock effects. So, if the wear process proceeds without ever manifesting dynamic effects, then it is possible to recommend the use of the boration process – both for small-sized parts with CTR in powder mixtures using unpressurized containers, and large-sized parts - in coatings that are applied only to the wearing surfaces of the parts. If the wear occurs under conditions of a relatively low level of periodically manifested shock effects, it is possible to use the borosiliconizing process at (800...900)°C. English version of the article is available at URL: https://panor.ru/articles/complex-metal-physical-studies-of-structural-steels-after-twocomponent-boron-based-diffusion-hardening/69778.html

PROCESSES AND TECHNOLOGIES OF COLD GAS DYNAMIC SPRAYING OF AGRICULTURAL EQUIPMENT

The article is devoted to the technology of cold gas-dynamic spraying - a relatively new technology for creating functional coatings in which narrowed-expanding nozzles (De Laval nozzles) are used, in which solid powders are sprayed at or close to supersonic speed in the direction of the substrate, where they plastically deform and adhere. Cold gas dynamic spraying is an innovative process that has received widespread scientific interest and industrial applications in the automotive, aerospace and biotechnology industries in recent years. Spraying various powder materials in this way provides protection against corrosion and can increase the mechanical strength and wear resistance of details. With that method it is possible to create functional coatings with different thermal conductivities and electrical conductivities, which can be used as insulation materials, conducting and isolation surface layers of parts, coatings for controlling gaps, restoring and repairing details. The article discusses modern developments in the field of experimental analysis of technologies and processes of cold gas-dynamic spraying, the systems of cold gas-dynamic spraying and coating formation are determined and the parameters and principles of the process are described. The installation for spraying surfaces developed at VNAU is presented and researches and the analysis of possibility of use of a method of a cold gas-dynamic spraying for restoration of details of autotractor equipment of agricultural purpose are carried out.

Plasma electrolytic oxidation technology for producing protective coatings of aluminum alloys

Today, the technology of hardening the surface layers of parts and the creation of protective coatings on the surface with high physical, mechanical and chemical properties is particularly effective. The article reviews the most promising innovative technologies for surface hardening of aluminum alloys – plasma electrolytic oxidation (PEO). Possible conditions and mechanisms for the formation of protective coatings on the surface of aluminum alloys are considered. The influence of the main parameters of PEO processing (electrical parameters, composition and concentration of electrolyte, the influence of alloying elements) on the structure and properties of oxide-ceramic coatings has been studied. The qualitative characteristics of the surface layer of samples and finished products made of aluminum alloys have shown the effectiveness of the PEO technology, which makes it possible to obtain ceramic coatings with high hardness, strength, increased wear and corrosion resistance. Possible areas of application of high-performance technologies for the deposition of protective PEO coatings on the surface of products made of aluminum alloys are proposed.

ОБЕСПЕЧЕНИЕ КАЧЕСТВЕННЫХ ПОКАЗАТЕЛЕЙ ДЕТАЛЕЙ, ОБРАБОТАННЫХ ИМПРЕГНИРОВАННЫМ АБРАЗИВНЫМ ИНСТРУМЕНТОМ

The work purpose: the accuracy investigation of parts machined with chromium diiodine grinding disks, and also roughness and structural state of surface layer material in parts after working with the impregnated tool; the investigation data are a part of the scientific work which has been started since 2012. 
 The investigation methods: the accuracy and quality of machining parts with the impregnated grinding tool were analyzed; there was carried out a generalization of the data obtained regarding quality parameter changes in the surface layer of parts during working having an influence upon their operation characteristics. 
 The investigation results and novelty: the impregnation method including additional mechanical oscillation at the moment of tool impregnation; the investigation results of accuracy and effectiveness of the mentioned method of working; the investigations of roughness parameters and distribution of residual stresses in the surface layer of parts. 
 Conclusions: at present in the Russian industry there are widely used methods and technologies of import substitution, industry needs low cost and efficient methods of working; thereupon there are urgent different investigations in the field of updating technology for metal grinding with the estimate of their effectiveness and qualitative characteristics of parts when using tools offered.

INFLUENCE OF THE GEOMETRIC CHARACTERISTICS OF THE DISCONTINUOUS PROFILE WORKING SURFACES OF ABRASIVE WHEELS FOR PRECISION AND TEMPERATURE WHEN GRINDING

Grinding is the most common finishing method for hardened steel parts. Grinding is accompanied by a large heat release in the cutting area, under the influence of which structural changes appear in the thin surface of the processed parts, tensile stress and even microcracks, which significantly reduce the operational reliability of machines that include these parts. The use of abrasive wheels with an intermittent working surface makes it possible to reduce the temperature in the area of contact of abrasive grains with the material of the workpiece and, as a consequence, stabilize the quality of the surface layer of the workpieces. High-frequency vibrations in the elastic system of the machine, accompanying the work of an intermittent wheel, are a positive factor that reduces the energy consumption of the grinding process. However, under certain conditions of dynamic interaction of the tool with the workpiece, parametric resonance may occur, which worsens the geometric and physical-mechanical parameters of the quality of the surface layer of the processed part. The aim of the work is to realize the possibility of predicting the quality parameters of the surface layer of parts during intermittent grinding by studying the influence of the design features of the macrotopography of the working surface of abrasive wheels and processing modes on the nature of the dynamic interaction of the tool with the workpiece and the heat stress in the cutting area. It was found that the parametric vibrations of the elastic system of the machine tool can be shifted to a more stable area, due to an increase in the number of interruptions of the working surface of the abrasive wheel with a constant ratio of the length of the protrusions and depressions. The increase in the number of breaks on the wheel also contributes to a decrease in temperature in the cutting area. It was found that to maintain the stable operation of the elastic system of the machine, it is necessary to reduce the number of cavities on the grinding wheel with an increase in the cutting speed. However, both of these actions are accompanied by an increase in the heat stress of the grinding process. It has been experimentally established that for ordinary (pendulum) grinding, it is possible to achieve an increase in processing productivity by increasing the speed of the longitudinal movement of the table.

Wear Model of Sliding Rough Surfaces

Purpose of research.To develop a wear model that takes into account the quality parameters of the surface layer and friction conditions, which will allow, through controlled technological action, providing the required wear intensity of friction surfaces.Methods.Electromechanical processing, in particular, can provide the required intensity of friction surfaces wear being carried out in finishing and strengthening modes.An increase in wear resistance, endurance limit and other operational properties, and at the same time a change in the physical, mechanical and geometric parameters of the surface layer of parts is achieved by a combination of thermal and force influences on the surface of the processed part. To achieve this effect, an original installation has been developed, which includes a device for machining based on a universal machine with a set of necessary tools and devices for fixing a workpiece and supplying coolant and electric current of high power and low voltage, as well as an industrial electric current converter and control units for processing modes, switching devices and computers.Results.An approach to the representation of the nature of friction and wear has been proposed. Based on the proposed wear model, which takes into account the quality parameters of the surface layer and friction conditions, it is possible to provide the required wear intensity of friction surfaces through controlled technological action.The developed wear model, which takes into account the quality parameters of the surface layer and friction conditions, makes it possible to provide the required wear intensity of friction surfaces through controlled technological action.Conclusion.The calculated data obtained with the help of the developed model and the data obtained experimentally will find practical application in creating resource-saving processes for processing metal alloys and composite materials.

Modeling and optimization of the elastic rolling process in order to increase the wear resistance of the surface layer of high-precision thin-walled parts of ship machinery and mechanisms

Ways of improving elastic rolling to ensure the required hardness of the resulting surface layer are considered. Analytical dependences of the hardness of the surface layer of the processed part on the determining factors are given. Keywords: process, elastic rolling, microhardness, parameters, planning, experiment, multifactority, technique. aydin.qafarov@hotmail.com

Influence of Factors Involved in the Elastic Rolling Process on Residual Stresses in the Surface Layer of Equipment Parts

The article presents the results of studies into the influence of various factors involved in a new elastic rolling process on residual stresses in the surface layer of high-precision non-rigid thin-walled parts. Modeling and optimization of the process are carried out to ensure maximum compressive residual stresses in the surface layers of equipment parts.

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.

MODELING OF THE GRINDING PROCESS BY MICRO-CUTTING SINGLE ABRASIVE GRAINS. PART 3. FORMATION OF RIS-GROOVES

When grinding on the processed surface of the workpieces of machine parts, a set of RIS-grooves is formed from the action of the vertices of the cutting abrasive grains of the circle. These risks mainly determine the roughness parameters of the treated surface and its physical and mechanical properties. The article presents the results of research of the micro-cutting process of different steels with different abrasive grains in a wide range of cutting speeds. It is shown that increasing the cutting speed during grinding has a positive effect on improving the metal quality of the surface layer of parts.

Повышение эксплуатационных свойств деталей машин электромеханической обработкой

A technological method for parts electro-mechanical treatment is considered. There are presented investigation results of electro-mechanical treatment impact upon quality parameters of parts surface layer, physical-mechanical and operation properties.

Integral criterion of the state of physical parameters of the surface layer of machine parts

Exoelectronic emission, which is used as a non-destructive method for monitoring the parameters of the surface layer of parts, and the level of exoemission current from the machined surface, that is a complex criterion for the physical and chemical state of the metal have been studied. Correlations between the main parameters of the surface layer and exoemission are found.