Machine Science 2024 - Number II
Author: Viktor GUZEEV, Nizami YUSUBOV, Heyran ABBASOVA, Ramil DADASHOV
Email: [email protected], [email protected]
Abstract: The productivity of machining in the production of machine parts is determined by the time spent on shaping surfaces according to the drawing and the number of machining stages required to achieve the specified accuracy of the part from workpieces of varying accuracy. Due to the well-known property of the technological system related to the technological inheritance of errors from the workpiece to the part, the refinement of the workpiece dimensions is carried out in several stages. The required number of machining (refining) stages for the workpiece depends both on the characteristics of the technological system itself and on the degree of variation in the workpiece's input parameters and its machining conditions. In addition, since the process of reducing the workpiece error depends on the dispersion of its dimensions, the required number of machining stages to achieve the specified accuracy is primarily determined by the change in the dimension of the dynamic setup at each stage. At the same time, the dimension itself is typically adjusted by changing the static setup. The dimension of the dynamic setup arises due to the elastic displacements of the elements of the technological system under the influence of cutting forces. The greater the difference between the dynamic setup dimension and the setup dimension (static setup dimension), the larger the error in the resulting dimension. Errors caused by fluctuations in the dynamic setup dimensions are difficult to compensate for, as they depend on many parameters: the strength properties of the material being machined, cutting conditions, cutting tool parameters and its wear, the rigidity of the technological system, and others. The article presents an approach to finding combinations of technological process parameters that ensure the shortest production time for parts and the specified accuracy. For parametric optimization, the identified patterns of the influence of the main technological process parameters on the refinement coefficient of the workpiece dimensions at each machining stage are discussed.
Keywords: machining stages, cutting conditions, turning, properties of the material being machined
Author: Natalia MOKROVA, Viktor ARTEMYEV, Anar HAJIYEV
Email: [email protected], [email protected]
Abstract: This paper presents a detailed analysis of a reversible thyristor feed drive for industrial metalworking systems, oriented for application in machine tools with position or contour numerical control, as well as in copying and milling machines. The drive under consideration is based on a three-phase zero-reversing scheme, providing a wide dynamic speed control range of the executive motor speed not less than 10000 revolutions, which allows effectively adapting to changes in technological parameters and various production modes. The application of proportional-integral speed and current regulators in the control loop contributes to the accuracy, stability and speed of the system under various mechanical loads and transient modes. The paper offers a comprehensive consideration of structural features, principles of operation and performance characteristics of reversible thyristor feed drive with PI controllers. The obtained results allow to optimize the drive operation in conditions of high precision machining, to expand the functional capabilities of the machine tool equipment, to reduce the influence of external disturbances and to increase the reliability of the industrial system as a whole. The basis of the hardware configuration of the drive consists of thyristor block (BT), control unit (CU), stabilized power supply of control circuits, as well as synchronization transformer, interacting by means of functional blocks: regulator block (RB), phase shifting device (PSD), logic block (BL), stabilized power supply block (SPB) and correction block (BC). The described functional structure simplifies the procedure of initial setting of the drive, tightening the interaction of the system elements and reducing the risk of uneven operation modes. It is possible to use both conventional electric motors with normal inertia-torque ratio and motors with increased torque overload capacity or reduced inertia. An important feature of the proposed solution is a built-in system of protection of power keys against short circuits by using high-speed maximum protection automatics (MPA), which contributes to increased reliability of operation and reduces the risk of failure of expensive elements. Additional stability of thyristor switching process is achieved by using transistor electronic keys, whose operation is synchronized with the supply network due to a special transformer winding, providing fast and accurate transition between positive and negative half-periods.
Keywords: dynamic programming, mathematical model, object control, system behavior
Author: Isa KHALILOV, Savalan KERIMOV, Semaye BAGIROVA
Email: [email protected], [email protected], [email protected]
Abstract: The article considers the first problem of dynamics. With a known law of motion of a five-link flat mechanism, which also includes a higher kinematic pair, unknown forces are determined. The reaction forces in kinematic pairs and the balancing force applied to the input link of the mechanism are determined by the graphoanalytical method.
Keywords: kinetostatics, degree of freedom, reaction forces, Assur group, kinematic pair
Author: Nizami YUSUBOV, Heyran ABBASOVA
Email: [email protected], [email protected]
Abstract: Features and challenges of multi-tool turning operations are proposed: equipment for multi-tool turning; the level of utilization of the technological potential of multi-tool machining in mechanical engineering; achievable machining accuracy; statistics on machining parts with predominant dimensions; statistics on multi-tool configurations; dimensional-accuracy theory of multi-tool machining. Therefore, the objectives of developing a design theory for multi-tool machining, considering the capabilities of modern CNC machines, are substantiated. The article provides information on the development of matrix models for machining error in multi-tool setups with spatially arranged tools, taking into account the simultaneous effect of all cutting forces from all tools in the setup and the elastic deformations of the technological system in all coordinate directions. It is noted that these models were developed both for dimensional distortion models and scatter field models. The developed full-factorial dimensional distortion model for a dual-carriage setup allows consideration not only of planar-parallel movements of technological subsystems but also their angular displacements around reference points. The theoretical solutions obtained were tested and refined directly in the practice of machine-building plants across various industries. The results of this refinement included various methodological and regulatory recommendations, as well as the development of a methodology for determining the comprehensive compliance characteristics of the technological system — the coordinate compliance matrix and the angular compliance matrix.
Keywords: multi-tool machining, matrix accuracy models, CNC metal-cutting machines, automatic and semi-automatic lathes, operation concentration, achievable machining accuracy, multi-tool machining accuracy theory, comprehensive compliance characteristics of the technological system
Author: Arif MAMEDOV, Agil BABAYEV, Mukhtar HUSEYNOV, Beture MUSURZAYEVA, Nizami ISMAILOV, Anatolii VERKHOVLIUK
Email: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
Abstract: The article analyzes the current situation and upcoming tasks of the Azerbaijan metallurgical industry. The activities of enterprises producing metal products in the country are assessed. It is noted that for the dynamic development of the metallurgical industry, a deep study of the mineral resource base existing in the territory of the Republic of Azerbaijan is required and it should be put into operation. In the near future, for the accelerated development of the metallurgical industry of the country, there is a mineral resource base, energy reserves, material and technical base, engineering and scientific and pedagogical potential. The tasks arising from the orders of the President of the country, stimulating the development of the metallurgical industry are shown and promising directions in this area are presented. The need to use local resources for the accelerated development of the metallurgical industry is noted. The industrial capacities of operating companies and plants are assessed, new goals are presented for them. At the same time, the article notes the acceleration of gold mining in the country and shows the ways of using their locations, liberated from the occupation of the Karabakh region. In recent years, in contact with the development of the non-oil sector, the order of the President of the country on the establishment of a steel production complex in Azerbaijan will determine the concept of sustainable development of the metallurgical industry. The article also provides information showing the dynamics of growth in the production of steel pipes, construction reinforcement and other products of ferrous metallurgy. A diagram is presented in the aspect of the prospective development of the ferrous metallurgy industry in Azerbaijan. The indicators of import and export in the Republic of Azerbaijan for ferrous metallurgy in 2002-2022 are given. It is noted that the metallurgical industry of the country will experience a new stage of development and in order to achieve new successes in this area, the development and implementation of innovative technologies are of great importance.
Keywords: metallurgy, steel, ferroalloy, mineral resource deposits, new intentions
DOI: https://doi.org/10.61413/FBID1194
Author: Jamaladdin ASLANOV, Tarlan FARAJOV
Email: [email protected], [email protected]
Abstract: Centrifugal flash gas compressors are mechanisms that convert the kinetic energy of gas into pressure energy, playing a crucial role in compressing and transporting associated gases in the oil and gas industry. These compressors operate on the principle of centrifugal force and are widely used in key industrial sectors. They are considered essential equipment for compressing and transporting gases in fields such as the oil and gas industry, chemical production, power generation, and cooling systems. Capable of handling high flow rates and large volumes, centrifugal compressors use impellers to increase the gas velocity, while the diffuser converts this velocity into pressure. As a result, gas compression occurs within the compressor, ensuring the continuous operation of industrial processes. Although centrifugal compressors offer high performance and durability, they can fail under certain conditions due to various reasons. Failures and breakdowns can lead to serious production issues, significant financial losses, and even safety risks. Let’s now examine the causes of these compressor failures.
Keywords: compressor, failures, wear, abrasion, corrosion, surge, dry gas seal, buffer gas
Author: Sarvan AZIZ
Email: [email protected]
Abstract: The article analyzes general aspects of the flat grinding process, analyzes the main features, provides a technological solution to the issues of surface and surface layer formation, dimensional and shape accuracy. The main input parameters affecting quality are machine parameters, processing methods, grinding wheel and abrasive grain characteristics, cutting mode elements, etc. The degree of influence of factors, as well as strength and hardness indicators obtained from the physical and mechanical properties of the part material, in general, is analyzed and the pattern of quality formation is determined. Similarities and differences in operations performed on the side and periphery of the grinding wheel during flat grinding, as well as functional dependencies of productivity and quality indicators are determined. It is determined that to select optimal processing modes for flat grinding operations, it is considered necessary to control process parameters, use machines controlled by a modern digital program, and modernize other process equipment in terms of increasing quality. In the article, the general aspects of the flat grinding process are analyzed, the main features are analyzed, the technological solution of the issues of surface and surface layer quality formation, size and shape accuracy is given.
Keywords: grinding, abrasive grain, hardness, roughness. dimensional accuracy, productivity
Author: Alexey GRIGORIEV, Beyali AHMEDOV, Viktor ARTEMYEV, Huseyin KAYA
Email: [email protected], [email protected], [email protected], [email protected]
Abstract: This paper presents a detailed analysis of the dynamics of an automatic temperature control system using an electronic model based on a cascade representation of control objects in the form of aperiodic links. The system under consideration includes several stages of signal conversion an actuator, whose inertial link determines the rate of temperature change; and a thermocouple, which has its own inertia, affecting the accuracy and delay of the feedback signal. To stabilise the temperature, a proportional controller is provided, which ensures the adjustment of the control action depending on the deviation of the actual temperature from the set temperature. The authors of the paper consistently derive a high-order differential equation describing the dynamic behaviour of the entire system. It is based on the physical parameters of time constants and gain coefficients responsible for the inertia of the links and the relationships between them. By substituting specific numerical values for time constants and coefficients as well as for the given initial conditions initial temperature deviation and its derivatives, the final equation of motion is formed, which allows to evaluate the nature of the transient process. The nature of transient processes arising at sudden change of system parameters or at initial deviation of temperature from the desired level is determined. The analysis of the obtained equation and its solutions makes it possible to predict the monotonicity and oscillation of the transient process, to estimate the maximum temperature deviations and the time of reaching the steady-state mode.
Keywords: control algorithms, simulation system dynamics, digital modeling, feedback management, optimization
Author: Matanat MEHRABOVA, Kamal GULMAMMEDOV, Sevinj SAFAROVA
Email: [email protected], [email protected], [email protected]
Abstract: One of the promising areas in polymer science is the development of methods for obtaining and studying polymer composites and nanocomposites. An important advantage of composites is their higher functionality and electrical stability compared to polymer analogues. The functioning of composite structures as an active element is associated, in particular, with charge formation phenomena. Therefore, in the development of new dielectric composites, researcher’s attention mainly focuses on their production and study of dielectric properties under effect of various factors (temperature, frequency). These studies can serve as a basis for selecting components of compositions for obtaining elements with predetermined parameters and assessing the possibility of their use as a dielectric. Analysis of literature data shows that fillers impart increased thermal and electrical conductivity, new magnetic properties to polymer materials, improve mechanical and electrical strength, etc. In the work presented the results of a study of surface microrelief and X-ray phase analysis of high pressure polyethylene with Na+-montmorillonite filler (HPPE+x wt% Nа+-MMT) composites, the results of the study on the temperature dependences of dielectric permittivity and the tangent of the dielectric loss angle. It was found that with an increase in the filler content, the degree of crystallinity of the composites decreases, dielectric permittivity increases, and dielectric losses decrease. The results of the X-ray phase analysis of the composites show that with an increase in the filler content of Na+MMT, the degree of crystallinity of the composites decreases from 50.5% (for 10 wt.%) to 62.1% (for 5 wt.%).
Keywords: High pressure polyethylene, bentonite montmorillonite, surface microrelief, X-ray phase analysis, dielectric properties
