Different articles "Materials working by pressure" of various directions of processes and machines of materials forming, prepared by the faculty, scientific employees, post-graduate students, competitors, experts are placed in this collection. The collection is intended for scientific and engineering workers, post-graduate students and students. Articles reviewed by members of the editorial board. Materials of the issue are printed in the original language.
Донбаська державна машинобудівна академія (ДДМА), м. Краматорськ
Development of a model for accounting for steel softening for modeling multi-transition hot stamping processes
Markov O., Molodetsky V., Zinsky V., Aldokhin M., Musorin A. Development of a model for accounting for steel softening for modeling multi-transition hot stamping processes. Technological processes of multi-transition hot die forging require optimization of technological modes to reduce the force parameters of deformation processes. This is due to a decrease in energy costs during the serial production of large-sized stampings weighing from 20 to 100 kg. The force parameters of multi-transition stamping processes can be reduced by accurately determining the level of stresses that arise in the workpiece during its deformation. Stamping of large-sized forgings in mass production is an expensive process, therefore technological processes require finite element modeling and analysis of the stress state of the workpiece metal and force deformation modes at each transition. This modeling requires an accurate determination of the stress state of the workpiece during stamping. Based on an analysis of the recent literature, it was determined that the main method for modeling the stamping of large-sized forgings was carried out using the finite element method (FEM). Mainly attention was paid to changing the shape of the workpiece during stamping using new methods and the influence of the shape of the deforming tool on the distribution of deformations in the body of the workpiece. Known software packages for simulating hot stamping processes based on FEM cannot take into account the processes of material hardening that occurs during high-temperature deformation. This is due to the lack of models connecting strain rates and stress components to take into account softening processes. Taking into account the relaxation of internal stresses will allow us to establish the corrected state of the workpiece metal and the power characteristics of stamping operations. The article presents that when calculating stamping operations, one should take into account not only the processes of steel hardening, but also the softening of the material that occurs in the processes of hot multi-transition stamping. Based on Maxwell's elastic-viscous model, the relationship between the strain rate tensor and stress was determined. This model can take into account the relaxation of internal stresses. The established analytical model was tested experimentally on S-60 steel at hot stamping temperatures. It has been proven that the installed model reproduces the rheology of steel during hot stamping by 90...95%. The established analytical connection between stress tensors and strain rates made it possible to carry out direct numerical calculations of multi-junction stamping processes without additional iterative MSE procedures. This made it possible to more accurately take into account the actual characteristics of steel, which significantly reduced the number of iterations and, accordingly, the modeling time.
Copyright (c) 2024 Materials Working by Pressure
Simulation of the force regime for lateral extrusion in a die with rounded areas
Levchenko V., Aliieva L., Abhari P., Titov A., Chepelenko O. Simulation of the force regime for lateral extrusion in a die with rounded areas. A triangular curvilinear kinematic module for simulating the force mode of the lateral extrusion process by the upper bound method was developed, which allowed to estimate the influence of the geometric parameters of the profiled dies on the deformation pressure. In the paper, the properties and possibilities of the triangular curvilinear module for the analysis of the process of transverse lateral extrusion of the ledge in a die with a rounded transition area were considered. It was found that the curvilinear module does not have the property of inversion. To determine the reduced die opening pressure at the transition edge of the die for the curvilinear module, the approach of implementation of the half-die virtual movement and obtaining the function, applying equation of the power balance on the kinematically possible movement speeds was used. The technique of developing a velocity hodograph and obtaining calculation formulas for both deformation pressures and opening pressures of dies with rounded sections is described. Graphical analysis of the dependences of reduced deformation pressures and die opening pressures showed that the parameter – the relative thickness of the process h/Rm, which characterizes the degree of metal compression on the transitional rounded edge of the die, has the greatest influence on the pressure level. The optimization parameter was the angle β, which corresponded to the position of the velocity break line at the exit from the deformation zone. For engineering calculations of power modes, simplified formulas, that adequately describe the influence of technological parameters, were proposed. Recommendations for calculating force parameters of extrusion with using the proposed triangular curvilinear module can be applied for the design of extrusion processes of both parts with ledges and hollow products with tools having rounded shape-forming surfaces.
Copyright (c) 2024 Materials working by pressure
Simulation of the process of transverse-forward extrusion with expansion
Levchenko V. M., Aliiev I. S., Chepelenko O. Yu., Kartamyshev D. O., Malii O. G. Simulation of the process of transverse-forward extrusion with expansion Combined extrusion methods are a competitive solution for the production of complex-profiled and hollow parts in optimal power mode. By simulation of the combined transverse-forward extrusion process with using the energy method of kinematic modules, calculated correlations were obtained and an assessment of the influence of technological parameters on the deformation pressure was given. The possibility of considering the process of combined extrusion as sequentially composed one of two plane modules with the addition of normalized pressures of transverse and forward extrusion with expansion has been confirmed. For the transverse extrusion module the correlations obtained by the upper bound method and showing results close to experimental data and similar solutions for problems of plane upsetting (final stage of die forming) and differing in two types of discontinuous velocity field were used. For a rectangular module of forward extrusion with expansion, a discontinuous velocity field was constructed and the correlation for calculating the pressure components on the velocity discontinuity lines was obtained. It has been found that there is an optimal value for the angle of the triangular module in the range of 42–45°, according to which it is recommended to tilt the semi-die wall. A graphical analysis of the dependence of the normalized combined extrusion pressure has allowed to identify that the relative parameters have the greatest influence on the pressure level: the height of the transverse extrusion deformation zone h/R0 and the thickness of the ledge h/s, which characterize the degree of metal deformation. The correlations that make it possible to evaluate the influence of the relative wall thickness of a hollow product h/s on the normalized deformation pressure were experimentally confirmed on workpieces made of aluminum alloy AA1135.
Mathematical modelling of the stress-strain state during drawing of cored wire with a metal core
Gribkov E., Malyhin S., Berezshna O. Mathematical modelling of the stress-strain state during drawing of cored wire with a metal core On the basis of the joint recurrent solution of the finite-difference form of the condition of static equilibrium of the selected elementary volume and the condition of plasticity of the powder medium, a numerical mathematical model of the stress-strain state was developed, which takes into account the real nature of the distributions of geometric parameters, mechanical properties and contact friction conditions during drawing of a powder wire with a metal core. Within the framework of the considered mathematical model of the stress-strain state during drawing of cored wire, it was assumed that the current values of the speed of movement of the powder material, its mechanical properties and normal axial stresses within each individual cross-section remain constant along the entire length of the deformation focus, changes in diameters, contact stresses are linear, and quantitative estimates of tangential stresses on the contact surface of the powder and monometallic components correspond to Amonton's law Under the condition of statistical equilibrium of the separated i-th elementary volume of the powder material, taking into account the piecewise linear approximation, taking into account the condition of plasticity for powder materials under axisymmetric loading and the influence of the value of the relative density on the values of the coefficients that take into account the specifics of the deformation of the powder composite, calculations of the ratio of plastic deformation rates, principal stresses and the ratio of the degree of deformation were obtained. Calculations of the relative density of the powder material within each individual i-th elementary volume were also obtained. The obtained dependences of the relative density of the powder core depending on the diameter of the metal core, reduction and tension of the powder wire, which make it possible to find rational values of these technological parameters when designing the technological modes of drawing.
Simulation of free deformation of a tubular blank under the condition of electro hydraulic loading
Naryzhnyi O., Taranenko M. Simulation of free deformation of a tubular blank under the condition of electro hydraulic loading The article is devoted to the study of the process of forming the pipe billet in conditions of electrohydraulic discharge. Such processes are widely used in the manufacture of the ends of pipeline systems in the aircraft, engine and automotive industries, in the manufacture of reconfigured transport systems for moving bulk materials (grain, flour, etc.), for sealing heat exchanger joints, etc. These processes are characterized by a high degree of plastic deformation of the workpiece during one technological transition, as well as complex kinetics of formation with the participation of liquid and vapor plasma parts of the technological system. There is a significant need for the development of research methods for such systems and processes using, in particular, mathematical modeling. Existing mathematical models of forming processes do not take into account the phenomenon of thinning of the thin-layer workpiece, which is the third main deformation. The purpose of the work is to improve and clarify the mechanical-mathematical model of the free distribution of the pipe billet under electrohydraulic loading by using the finite-element approximation of the theory of shells taking into account thinning, as well as to study the regularities and features of the mechanical processes of the movement of the elements of the technological system and the stress-strain state of the billet with taking into account this improvement. The structural diagram of the model of the technological system, dimensions, properties of the material, conditions of violation of the technical process, conditions of mechanical interaction of system elements, method of improving the model are given. The results of modeling mechanical processes in the technological system and the stress-strain state of the workpiece using an improved mathematical model are presented. Improvement of the model is appropriate and corresponds to the results of experiments. In general, the model is adequate, the method has sufficient accuracy, the thinning has a heterogeneous character and varies in the range of 1.2...14%, the obtained process efficiency corresponds to the experimental data. To increase the efficiency of the technological process, it is desirable to dispose of the final reserve of internal energy of the steam-gas cavity, for example, by reloading. In the future, the improved model can be used to study indentation in the matrix, sealing of joints and analysis of reloading with a new discharge.
Research of the method of rolling projectile from tubular workpiece
Markov O., Shevtsov S., Aldokhin M., Panov V., Rovenskyi S. Research of the method of rolling projectile from tubular workpiece The work is aimed at solving the current technical and scientific problem regarding the improvement of the technological processes of the production of blanks for parts such as artillery shells based on the application of the operation of tangential rolling with a friction tool, which makes it possible to manufacture hollow parts with a bottom. The finite element method was used to simulate the technological process of rolling the bottom with a friction tool, which made it possible to determine the rational shape and dimensions of the rolled pipe blanks and their preheating temperature. Recommendations have been developed for the design of energy-saving technological processes of rolling parts such as sleeves, which allow to set the wall thickness of the pipe billet before rolling, the heating temperature of hollow billets, as well as the amount of relative feed of the billet to the friction tool. The established recommendations were verified by experimental studies on steel blanks. According to the research results, it was established that the rolling of spherical bottoms should be implemented for pipe blanks with a relative wall thickness (D/s), which is in the range of 15...20. The homologous heating temperature of the hollow billet was 0.8, and the relative feed of the pipe billet into the friction tool was 0.9. Approbation of the determined ratios in laboratory conditions proved that there are established recommendations for changing the shape and size of spherical bottoms in the process of tangential rolling with a friction tool. The laws of shape change of the workpiece revealed in the work expanded the technological possibilities of the process of tangential rolling of bottoms and made it possible to establish the possibilities of the researched process. The results of macrostructural studies on steel products confirmed the results of finite element modeling on the effect of tangential rolling of the spherical bottom on support in the axial zone. Based on the results of research, it was established that this method can be used for products that have a bottom with an axial hole (artillery shells, hydraulic cylinders, etc.). Axial defects in this case will be removed when drilling an axial hole.
Evaluation of the deformity of the blanket in the process of combined extrusion of a knife for a branch cutter
Sivak R., Naliazhnyi V., Chuchin O., Kosarev V. Evaluation of the deformity of the blanket in the process of combined extrusion of a knife for a branch cutter It is suggested to use a two-stage combined extrusion process to obtain a blank for the branch chopper knife. Knives are one of the main working elements of the branch shredder, which work under the conditions of impact and repeatedly changing loads, intensive wear, etc. Therefore, at present, the knife production process includes a number of technological machining operations. These include a number of metal cutting operations and heat treatment. In addition, the production of knives requires alloy steel of high value. The article proposes a radical change in the approach to obtaining blanks for chopper knives. For this, it is proposed to use an innovative method of combined extrusion, which includes the process of equal-channel extrusion and precipitation. This will reduce the number of operations related to cutting and replace expensive alloy steel with cheaper grades of structural steel without deteriorating the performance characteristics of the product. To assess the deformability of the workpiece, a tensor model of damage accumulation was used, in which the dependence of plasticity on the stress state scheme was determined by the surface of limit deformations, and the load history by trajectories in the space of three dimensionless indicators. The deformed state was determined using a fixed spatial and particle-related material system of a deformable body. The stress state was determined using the anisotropically strengthened body model.
Influence of the cone punch angle on the flanging of holes in a profiled sheet billet
Kaliuzhnyi O., Kaliuzhnyi V., Chuchin O. Influence of the cone punch angle on the flanging of holes in a profiled sheet billet In this article, the influence of the cone punch angle on the processes of axisymmetric flanging of holes in a profiled aluminum sheet billet AL-3003 COLD was studied using the finite element method and DEFORM software. The profiled billet was obtained by forming a hole by extrusion with punching of a bridge and has a maximum thickness near the hole with a subsequent linear decrease in thickness to the original one at the radius of the die. The use of a profiled billet results in a flange with a constant wall thickness along the length equal to the thickness of the original billet. An elastic-plastic model of metal was used for modeling. The dependence of the forces of flanging and punching on their displacement was determined. A punch with an angle at the top of the cone of 40o provides the minimum flanging force. For such a punch, the distributions of stress components in the deformed workpiece at the maximum flanging force and the distributions of the final deformation components in the flange are determined. The shape and dimensions of the flange after flanging and punch removal are shown. Based on the modeling data, a stamp with a set of tools for conducting experimental studies on the manufacture of a profiled billet and flanging was designed and manufactured. The experimental results showed good agreement with the modeling data in terms of extrusion forces, flanging and flange dimensions. At the same time, the flange has an advantage in strength due to the improvement of the macrostructure when the hole is formed by extrusion. The possibility of a significant increase in the height of the cylindrical part was obtained due to the subsequent implementation of stretching with thinning.
Hole flanging at the bottom of the hollow semi-finished product after deep drawing
Kaliuzhnyi O., Kaliuzhnyi V., Levchenko V. Hole flanging at the bottom of the hollow semi-finished product after deep drawing In the article the research results obtained using the finite element method and the DEFORM program in simulation the process of axisymmetric flanging with forming a flange along the contour of the hole in the bottom part of a circular hollow semi-finished product drawn from a sheet workpiece from AISI-1010COLD steel are presented. Thinning and deformations in the bottom part after drawing were considered. An elastic-plastic model of the metal was used. The influence of the die radius on the flanging parameters is analyzed. An analysis of the shape forming by flanging and punch removing from the flange was carried out. The dependence of the flanging and punch removing forces vs the punch stroke was determined. It was shown that reducing the radius of the die leads to an increasing the flanging force, which reaches a maximum at different punch strokes. The shape and dimensions of the flanges are determined with consideration of the elastic deformation. It was found that during flanging, the flange wall is curved and thinned. Warping, thinning, and elastic deformation of the wall increase with decreasing die radius. The distributions of stress components at the maximum value of the flanging force were obtained. It was shown that during flanging, tensile tangential stresses have the highest values. The distributions of the components for the final deformations and the degree of plasticity resource usage in the deformed flange metal were determined. It was found that the radius of the die has an insignificant effect on the deformed state during flanging, and the plasticity resource is practically exhausted in the inner and outer layers of the metal in the area of the flange wall ends. The working of the metal structure by cold plastic deformation in the flanges was estimated by the value of the effective strain. Based on the simulation data, the dies for flanging were designed and manufactured. The experiments on flanging were performed on a hydraulic press. The results of the experiments showed accordance with the calculated data.
Theoretical and experimental investigation on the process of separating rolled pipes using an eccentric torsion scheme
Karnaukh S. Theoretical and experimental investigation on the process of separating rolled pipes using an eccentric torsion scheme The work presents the results of theoretical and experimental studies of the energy-power parameters of the separation process, the geometric accuracy of pipe-part blanks using the «eccentric twisting» method. A mathematical model of a device with a «crank-circular» mechanism for cutting pipes by «eccentric twisting» has been developed. The technological process of cutting pipes by «eccentric twisting» was simulated using the DEFORM software package. To verify the results of theoretical calculations, experimental studies of pipe separation were conducted on an original design installation. The cut tubular work-piece have satisfactory geometric accuracy. The obtained results of experimental studies are in good agreement with the theoretical data calculated using the proposed mathematical model and the specialized program DEFORM. The maximum differences between the cutting torque values obtained theoretically and experimentally do not exceed 6%. The theoretical results were slightly underestimated due to the need for more accurate frictional accounting in rotating pairs, as well as some discrepancy in the mechanical properties of the material of experimental samples with the material from the base steels of the DEFORM program. For the industrial implementation of research results, a design of an installation with a wedge-hinged drive with a concave wedge in combination with a «crank-circular» mechanism for separating pipes by the «eccentric torsion» scheme is proposed. The wedge-hinged mechanism with a concave wedge has large support surfaces, a small height of the links in the direction of the working force, which provides less elastic deformation and machine dynamics and increases the utilization coefficient of forging and pressing equipment. At the same time, the developed support area of the connecting rod in the slider of the «crank-circular» mechanism reduces the specific forces in this support and contributes to the damping of vibrations, which, combined with a small deformation zone, leads to high dynamic stability and absence of rocking on the foundation.
Linear and non-linear models in damage summation theory
Mykhalevych V., Dobraniuk Yu., Тiutiunnyk O., Kolisnyk M. Linear and non-linear models in damage summation theory In the article, against the background of a brief and fragmentary review of the development of the theory of deformability in the works of domestic scientists, the concepts of linear and nonlinear principles of damage summation in their connection with the corresponding scalar and tensor models are considered. The criterion relations resulting from these models are studied for the description of the ultimate plastic deformations in the processes of steady and unsteady deformation. On the example of a two-stage process, which in each stage is a stationary process, i.e. characterized by a constant value of the stress state index, the regularities of changes of the ultimate deformations in relative coordinates are demonstrated, which reflect the dependence of the residual on the plasticity resource used. The advantages of presenting the criterion relations in these coordinates are substantiated, which consist in universality of comparisons and better reflection of changes, trends, and convenient consideration of data scales. The fundamental qualitative and quantitative difference between the criterion relations derived from models based on linear and nonlinear principles of damage aggregation in relation to the two-stage deformation process is demonstrated. In particular, it was found that when using the plasticity resource of 0.5 in the first stage, the estimated residual life according to the nonlinear criterion relation is 0.84 for the tensile-torsion process and 0.06 for the torsion-tension process, while according to the linear criterion, the residual life is 0.5 in both cases. The analysis of the model of V.A. Ogorodnikov shows its advantages and disadvantages, which have not been sufficiently considered in the literature. It is shown for which classes of transient deformations the specified model, which reflects the nonlinear principle of damage summation, becomes identical with the simplest linear model. Thus, the recommendations concerning the limits of application of various damage summation models are clarified.
Aspects of artificial intelligence implementation in the technological support of the life cycle of machine-building products
Kovalevskyy S., Sydiuk D., Kovalevska O. Aspects of artificial intelligence implementation in the technological support of the life cycle of machine-building products. The article is dedicated to the analysis of the implementation of artificial intelligence (AI) in the technological support of the life cycle of manufacturing products. Key aspects of AI application for increasing the efficiency of all stages of the life cycle of manufacturing objects – from design to disposal – are described. Special attention is given to the use of advanced technologies for automation, predictive maintenance, and diagnostics of the condition of production objects. Mechanical processing by pressure and cutting is considered as important stages of the production process, where AI application ensures adaptive control of parameters such as pressure, temperature, cutting speed, and deformation force, which helps to minimize tool wear, improve processing accuracy, and ensure stable product quality. A conceptual structural scheme for integrating AI into production control processes and the maintenance of functional surfaces of parts has been developed. It includes the collection and processing of data, the prediction of the condition of production objects, and their operational recovery in case of wear or damage detection. The use of AI technologies allows timely identification of issues arising at the stages of equipment operation, ensuring its uninterrupted work and reducing downtime. AI integration into product recycling processes is also important, optimizing material processing and reducing the negative environmental impact. The article separately addresses predictive maintenance issues, where, through data analysis from sensors and detectors using AI, wear and failure of parts can be predicted. The creation of digital twins of production objects enables real-time monitoring of their functional condition, improving equipment efficiency and reducing maintenance costs. The article demonstrates that the implementation of AI at all stages of the life cycle of production objects is a critical factor in enhancing their reliability, durability, and competitiveness. The obtained results show that the use of AI significantly increases production efficiency, reduces maintenance and repair costs, improves product quality, and ensures environmental sustainability in modern manufacturing. AI plays a crucial role in providing adaptive approaches to managing production processes, allowing high productivity to be achieved with minimal costs.
Testing emulsions for cold rolling for soot-formation at coil annealing
Kukhar V., Spichak O., Pashynskyi V., Malii Kh. Testing emulsions for cold rolling for soot-formation at coil annealing Cold rolling with emulsions allows for lower rolling forces, higher crimping and lower final bar thicknesses, greater rolling stability and better surface finish after rolling. However, the subsequent stages associated with cold-rolled coil annealing operations can present unexpected unpleasant "surprises" in the form of sooty surface defects. In addition to uneven application and poor emulsion rinsing prior to annealing, soot formation is significantly affected by the composition of emulsions (components included in the emulsion formula) and their physical and chemical properties. The paper analyzes the causes of surface defects of the "soot" type after annealing coils rolled with emulsions and substantiates the need to reduce soot formation and burning by formulating requirements for the physical and chemical properties of lubricating and cooling fluids. A methodology for testing the tendency of emulsols to soot formation after annealing in coils, which is the first stage of a multistage study, has been developed. The methodology consisted of applying concentrated emulsion to witness samples, which were annealed together with the coils under the same temperature and time conditions and furnace environment. The physicochemical characteristics of lubricating and cooling liquids were analyzed and 54 emulsions of different brands and manufacturers were tested during cold rolling. A scoring system for assessing the intensity of soot formation by visual observation is proposed, and the values of soot formation scores after annealing of the experimental samples are determined. The calculated regression equations were obtained that relate the soot and burn formation rates to such physicochemical properties as emulsol density at 20 °C, kinematic viscosity at 50 °C, and saponification number. A stable dependence of the hydrogen pH value for a 3% aqueous emulsion prepared with hard water of 4.6 mg-eq/dm3 on the indicated physicochemical properties of emulsols was shown. Based on the results of the research, 28 emulsions were recommended for use in the conditions of PJSC "ZAPORIZHSTAL" and requirements for their main physical and chemical parameters were formulated.
Mathematical modeling of technological modes for straightening sheets and plates on a press
Gribkov E., Kassov V., Vasylieva L. Mathematical modeling of technological modes for straightening sheets and plates on a press The work is devoted to the actual problem of determining rational technological modes and design parameters of equipment when editing letters on the press based on skimmed-element modeling in the ESS system. The goal of the work is to develop a mathematical model of the process of straightening sheets and plates on a press, taking into account changes in the physical and mechanical characteristics of the material and its implementation by the finite element method, which will make it possible to obtain fields of changes in the integral characteristics of the process and predict the stress-strain state of the material for subsequent automation. -tified design of technological parameters of equipment operation and increasing the efficiency of engineering calculations at the stage of technology development. Mathematical modeling of straightening processes is presented taking into account the basic principles of plasticity theory, which makes it possible to predict with sufficiently high accuracy the distribution of the stress-strain state in each grid node of the finite element model along the deformation cell. A technique has been developed for numerically solving the problem of plastic deformation based on the finite element method using the capabilities of Abaqus CAE. The numerical model of the deformation process is based on flow theory, and the workpiece material is considered as an incompressible elastic-plastic body, and the speed of movement of the upper punch and the stationary fixation of the lower punches were chosen as limiting conditions. The use of the presented finite element modeling of the technological parameters of the sheet-straightening process when performing engineering calculations will ensure increased accuracy in predicting technological settings and the efficiency of designing sheet-leveling equipment, and, consequently, improved product quality. Also presented, the simulation results can be used directly in the press control system and increase its productivity by reducing the time for sheet processing.
Modelling of the stress-strain state during levelling sheets on sheet straightening machines with tension
Pozhidaev A.V., Gribkov E.P., Berezshna O.V. Modelling of the stress-strain state during levelling sheets on sheet straightening machines with tension The development of metallurgical products is moving towards the creation of increasingly stronger grades of steel, which in turn requires the development of new processing technologies and equipment for metal rolling. Tension levelling through alternating bending is particularly relevant for thin sheet metal, where conventional multi-roll machines do not achieve the desired results to meet the continuously increasing quality demands of consumers. To address this issue, various approaches exist, such as numerical and finite element modeling methods, each with their own advantages and limitations. A review of existing sheet levelling models has shown that the effect of stretching is not accounted for in them. Therefore, this study investigates the effect of tension magnitude during levelling on a levelling machine and its impact on the stress-strain state of the levelled sheet metal. The aim of this work is to study the stress-strain state of sheet metal during tension levelling with alternating bending. The research on tension levelling with alternating bending was conducted using finite element modeling software in the Abaqus CAE environment. A finite element model of the sheet levelling process with tension was proposed. The effect of sheet tension level on the stress-strain state of the sheet was analyzed. During experimental modeling, equivalent strains across the sheet section were compared during levelling in a roll levelling machine, both without tension and under varying degrees of tension. It was found that increased tension raises the strain level on the third roll. The proposed finite element model can be used to determine the optimal settings for the working rolls of the levelling machine. The study concludes with an obtained relationship between sheet deformation and tension during sheet metal levelling.
Study of the influence of tube rolling parameters on the working conditions of the pqf mill mandrel
Kondratiev А., Samsonenko A., Bobukh O., Kuzmina O., Reviakin D., Spector S. Study of the influence of tube rolling parameters on the working conditions of the pqf mill mandrel The work is devoted to the analysis of the process of seamless steel pipes production by hot rolling at continuous rolling mill with three-roll cages, namely the PQF. The scheme of rolling pipes on held mandrels in three-roll continuous mills is given. The influence of pipe rolling parameters at the PQF mill on the working conditions of the technological tool - the mandrel - is investigated. It is shown that the working conditions of the mandrel in the process of rolling on the PQF mill depend significantly on four main factors: the rolling forces acting on the rolls and on the mandrel; friction conditions on the contact surfaces of the pipe with the mandrel; time of the mandrel and billet contact in the deformation zone; speed of sliding metal of the pipe relative to the mandrel. The study is carried out using finite element simulation in the QForm UK program using the method of a full factorial experiment 23. A model of the deformation for a steel cylindrical workpiece with an initial diameter of 200 mm and a length of 800 mm in the first two cages of the five-roll mill was created; the plan of the experiment is given. The input factors are determined - the thickness of the pipe wall, the coefficient of friction, the speed of movement of the mandrel. Normal stress in the center of deformation, friction force, elongation coefficient, speed of the pipe at the exit from the cage, specific friction forces were selected as output factors (response functions). The results of calculations were processed to obtain regression coefficients. According to the results of the study, it was concluded that the influence of input factors on the target functions for the first and second cages of the mill differ: if for the first cage, the influence of each of them has approximately the same effect on the force of friction, then in the second cage the friction coefficient and speed of mandrel show the greatest influence.
impact energy control, angular velocity, moment of inertia, mass, screw press, slider mass, linear speed of the slider
Оbdul V., Matiukhin A., Shirokobokov V., Ben A., Lenok A., Epishkin O. Methods of impact energy control in screw presses The design of a screw press with a clutch with the control of impact energy both in a series and during transitions is developed. Analysis of existing control methods shows that the technological requirements for these systems are not always met. In turn, the analysis of screw press designs and their technological application shows that the problem of output parameter adjustability must be solved simultaneously with the design improvements of the presses themselves. The proposed design of the press with impact energy control practically eliminates these shortcomings, since it is a closed-loop system with rigid feedback on the angular velocity of the flywheel masses using a thyristor-motor drive. It is shown that the determination of the installed power of the electric motor depends on the ratio of the maximum value of the energy stored in the main drive of the press to the minimum value and the ratio of the moments of inertia of the driving and driven masses and the frequency of the press strokes. The installed power of the main electric motor will be determined by the most severe mode of operation during the period of signal development when switching from the minimum energy accumulated by the masses to the maximum, or during the period of switching on the friction clutch for the working stroke of the press, i.e. this mode is determined by the range of impact energy control, the number of strokes of the press slider and the ratio of the moments of inertia of the driving and driven masses mounted on the screw spindle. The use of rigid feedback on the angular velocity of the masses makes it possible to reduce the duration of the transient process and, consequently, the duration of the straight stroke of the press slider. The existing methods of impact energy control on screw presses are analyzed.
Research of a new design of the installation with a wedge-hinged mechanism with a rotary knife for separating shaped rolled products
Karnaukh S., Chosta N. Research of a new design of the installation with a wedge-hinged mechanism with a rotary knife for separating shaped rolled products Roll separation operations differ from other operations of processing materials by pressure in that, for their implementation, it is necessary to ensure the maximum force of separation at the beginning of the work cycle. On the basis of literature and patent searches, an improved design of the wedge-hinged mechanism with a concave wedge with a rotary knife was developed, which, according to the graph of the deformation force, is as close as possible to the typical force graph characteristic of separation processes. The wedge-hinged mechanism has fewer friction surfaces. It is more technological in manufacturing compared to the well-known wedge-hinged mechanism with a concave wedge. On the basis of the proposed mathematical model of the new design of the installation with a wedge-hinged mechanism for separating profiled rolled products of a complex configuration and modeling analysis using the DEFORM software complex, a method of selecting geometric parameters during the design of such mechanisms that provide optimal cutting modes has been developed. Recommendations have been developed for choosing the value of the hinge center coordinate, which should be equal to half the radius of the concave wedge. As this parameter increases, the amount of force, and separation moment increases. With the approach of the hinge to the concave surface of the wedge, with the same values of the displacement of the wedge, the magnitude of the angle of rotation and the displacement of the movable knife decrease. Recommendations are given regarding the orientation of the roll supply to the cutting zone. The analysis of the obtained data allows us to conclude that the power parameters of the separation process practically do not depend on the orientation of the shaped P-shaped profile of the rolled product during complex rotational-translational motion. The simulation results prove that the use of a new design installation provides a reduction in the energy parameters of the separation process in comparison with known designs of modern equipment. The use of the installation ensures an increase in the quality of cut blanks.
Design of a radius matrix for drawing high cartridge cases
Markov O., Zinsky V., Rovenskyi S., Molodetsky V. Design of a radius matrix for drawing high cartridge cases The paper examines the technical process of drawing high sleeves through a radius matrix. Research is aimed at solving an important and urgent scientific and technical problem of improving the technical process of broaching through a radius matrix using a mandrel when stamping hollow forgings such as sleeves and tall glasses. The developed method increases the service life of drawing matrices. The finite element method (FEM) was used to simulate the method of pulling tall sleeves through a radius matrix with different rounding radii. According to the simulation results, the optimal shape and dimensions of the radius matrix for drawing were developed. Recommendations for the development of radius matrices have been established. These recommendations consist in the appointment of the optimal radius of the working surface of the extension matrix. The received recommendations were experimentally verified in production conditions. It was established that the drawing of high sleeves through the matrix should be carried out at a relative radius of the working surface of the matrix R/d = 3. As a result, the intensity of stresses and average stresses on the working surface of the matrix were reduced by 8...15 %, and the normal pressures were reduced by 10...15 %. The total force and the radial component of that force have been reduced to 50%. According to the research results, it was determined that the surface of the matrix heats up to 700...800 ℃, and the radius R/d=3 reduces the size of this zone by 1.5.... 2.0 times. Verification of the obtained results was carried out in industrial conditions. It was established that the drawing force for the radius R/d=3 is below 20%, and the stability of the matrix has increased by 20%. Thus, it is recommended to use radius matrices with R/d = 3 for pulling sleeves.
Study of the mechanism of magnetostrictive and magnetodispersive hardening of punches made of high-speed steel after processing in pulsed magnetic fields
Kindenko М. Study of the mechanism of magnetostrictive and magnetodispersive hardening of punches made of high-speed steel after processing in pulsed magnetic fields The presented work is devoted to the study of issues related to the study of the mechanisms of magnetostriction and magnetic dispersion hardening of the working part of punches made of high-speed steel P6M5 and P6M5K5 for stability after magnetic pulse processing, which is a combination of electromagnetic and thermodynamic methods of controlling the non-equilibrium structure substances. High-speed steel, like any solid body, has an elastic internal field due to the real dislocation structure. When a magnetic field is applied to a material, an elastic field caused by magnetostrictive deformation is superimposed on this own elastic field. In general, the result of magnetic processing is considered as a manifestation of aftereffects in materials that are at the boundaries of the stability of their properties and are exposed to the action of an external force field. It was noted that as a result of the pulsed magnetic field, the physical and mechanical properties of high-speed steel change and the tool material becomes more uniform in structure. Applying magnetic processing, it is possible to significantly reduce the excessive energy of the material associated with the concentration of internal and surface stresses in the tool, and reduce the probability of its breakage to a minimum. Magnetic pulse processing is a complex effect on the material of magnetostrictive processes and mechanical deformations, thermal and electromagnetic eddy currents localized in places of magnetic flux concentrations. It is shown that as a result of magnetic treatment, high-speed steel undergoes volume strengthening, dispersion hardening, becomes more homogeneous in structure and improves its physical and mechanical properties. The pulsed magnetic field, interacting with the material of the tool, changes its thermal and electromagnetic properties, improves the structure and operational characteristics, which is the basis of the magnetic strengthening technology. It was established that the root cause of the improvement of the operational characteristics of the tool subjected to magnetic treatment is the change in the properties of the tool material. This happens due to the magnetostrictive strengthening of high-speed steel, which is expressed in an increase in its heat resistance.
Improving the quality of melted metal during the restoration of the working surface of the press tool
Grin O., Zharikov S. Improving the quality of melted metal during the restoration of the working surface of the press tool The analysis of literature data showed that the reliability and efficiency of forging and press production depends on the stability of the deforming tool, the improvement of which is of great technical and economic importance. One of the ways to increase stability is strengthening and restorative surfacing of the working tool with self-shielded flux-cored wire (SFW). One of the disadvantages of SFW is the formation of pores and non-metallic inclusions caused by nitrogen in the deposited metal, the amount of which depends on the effectiveness of the protection of the liquid metal. Gas saturation and the quality of the deposited metal are affected by the gas slag-forming part of the flux-cored wire core. Therefore, an urgent issue is the study of the influence of SFW components on nitrogen and nitride saturation of the molten metal. The saturation of the molten metal with gases occurs both in drops and in the welding bath. When studying the influence of the sheath steel grade on the gas saturation of the deposited metal and the content of non-metallic inclusions, it was found that for SFW sheaths made of 08кп, 08пс, 09Г2 steels, the minimum number of non-metallic inclusions is formed when using a wire with a 09Г2 sheath, while also establishing a minimum solubility of gases in the deposited metal. The analysis of the effect of the gas-slag-forming component of the flux-cored wire on the nitrogen content in the welded metal showed that the ratio of the components: fluorspar CaF2, rutile concentrate TiO2, marble CaCO3 significantly affects the solubility of nitrogen in the weld metal. Based on the results of our research, a mathematical model was obtained that can be used in the optimization of the gas slag-forming part of self-shielded flux cored wires, during the melting of which slags of the main character of the CaO - CaF2 - TiO2 system are formed.deforming tool, self-shielded powder wire, non-metallic inclusions, gas saturation of deposited metal, the gas slag-forming component of the flux-cored wire.
Influence of heat treatment on mechanical properties and microstructure of pre-eutectoid steel for hot pressure treatment
Dyachenko Yu., Fedorov M., Liutyi R. Influence of heat treatment on mechanical properties and microstructure of pre-eutectoid steel for hot pressure treatment. The process of formation of austenitic structure at continuous heating of pre-eutectoid steel for combustible treatment with pressure with initial ferrite-perlite structure is considered. The choice of optimal quenching temperature depending on the required level of mechanical properties in finished products is substantiated. The method of trial quenching to study the process of formation of austenitic structure, metallographic method of microstructure detection research and chemical etching were used. Determination of strength and impact toughness of low-carbon steel after quenching in water from temperatures 700...900°C. Has been carried out. It is shown that during heating of low-carbon steel recrystallisation of the initial ferrite-perlit e structure occurs in the interval Aс1 – Aс3 in two stages. The first stage consists in the formation of austenite grains inside the previously located pearlite grains. It occurs immediately after the temperature Aс1 is reached. The second stage consists of crushing of primary ferrite grains by nucleation of austenite grains in them and crushing of ferrite grains by penetration of austenite grains formed at the first stage of recrystallisation. Recrystallisation is completed when the primary ferrite grains disappear completely. To obtain a high complex of mechanical properties with the maximum level of impact toughness steel should be quenched from the temperature Ac3 - 10oC; with the maximum level of strength properties, respectively, with Ac3 + 10oC. The obtained data can be used for thermal treatment of pre-eutectoid steels, which will significantly increase its stability under conditions of variable and multiple heating and cooling of the working layer under hot pressure treatment.
Phosphate binders for the manufacture of casting molds in technologies for casting die tool blanks
Fedorov M., Liutyi R., Dyachenko Yu., Kocheshkov A., Liuta D. Phosphate binders for the manufacture of casting molds in technologies for casting die tool blanks Casting technologies for the production of die tool parts have significant advantages over the use of forgings, rolled bars or powder parts. The steels used for die inserts, dies, punches and other parts generally have satisfactory casting properties and produce precision castings. However, the choice of casting method remains a pressing issue today, since die casting technologies are expensive, energy- and material-intensive. The production of such parts is small-scale, while leading foundry technologies are designed for large series or mass production. An important task is to create technological conditions for the production of work pieces from alloy steels using a minimum amount of materials, which, in turn, are accessible and cheap. Compared to the special casting methods that are used now, casting in one-time molds allows us to solve this problem. At the same time, a new question arises - the creation of effective molding materials suitable for this technology and oriented to the conditions of small-scale production, that is, high-quality and easy-to-use core mixtures. The article presents the results of a study of the processes of formation of binders in systems of orthophosphoric acid with metal sulfates such as MgSO4·7H2O, MnSO4·5H2O, FeSO4·7H2O, CoSO4·7H2O и Al2(SO4)3·18H2O. It has been experimentally established that all of these sulfates, when heated in the range from 150 °C to 300 °C, enter into a chemical interaction with orthophosphoric acid, resulting in hardening of mixtures based on them. Systems with iron and aluminum sulfates have the best performance as binders for core mixtures. For them, the optimal ratios of sulfate and acid, heating temperature and the required binder content in the mixture have been established. Various methods for preparing mixtures have been studied and the feasibility of pre-mixing metal sulfates with orthophosphoric acid to obtain a solution or dry composition has been established. Laboratory tests consisted of using mixtures for casting high-alloy chrome-aluminum steel. The castings do not have burn marks or other surface defects, and therefore the developed core mixtures are potentially suitable for casting alloy steels, including die steels.
Continuous improvement: Kaizen in the materials processing industry
Podlesny S. V. Continuous improvement: Kaizen in the materials processing industry The study examines current issues related to the implementation of the Kaizen concept in the materials processing industry, based on continuous improvement. Theoretical and practical issues of using the Kaizen concept are considered in order to improve all aspects of the functioning of materials processing enterprises, solve many production issues and problems, improve the quality of products and services, increase competitiveness, efficient use of resources, increase efficiency and effectiveness, reduce costs and achieve gradual improvements in various aspects of production. Kaizen has become a universal method aimed at continuous improvement in accordance with the requirements of the modern competitive environment. Three sets of Kaizen principles and the benefits that its use provides in the materials processing industry are discussed. The application of Kaizen principles solves the problems of optimizing production processes, standardization, establishing standard operating procedures and best practices, and involving all employees of the enterprise in improvement processes. It is recommended to implement changes using Kaizen using the PDCA approach. A list of principles of the Kaizen philosophy is given that should guide the implementation of changes. The Kaizen philosophy emphasizes the importance of the participation of all employees in the process of continuous improvement. Kaizen methodology, as a systematic approach to continuous improvement, actively uses standardization, data to make decisions and identify areas for improvement. Examples of the possible use of Kaizen to improve individual elements of production are given. It has been shown that Kaizen can be successfully combined with other approaches and technologies, such as 5S, Kanban, Value Stream Mapping, Six Sigma, DMAIC, and digital technologies.