Bulletin PNRPU. Mechanical engineering, materials science

The paper presents the results of research into Coefficients of Thermal Expansion (CTE) anisotropy discovered in multilayer metal material produced by hot pack rolling based on 1008 and AISI 304 steels. It has been established that the material comprised of interleaving layers of the two steel types features abnormally low CTE in the direction normal to the rolling plane (ND) with regular TEC values in the plane of the plate material along RD and TD directions. A hypothesis has been proposed to ex- plainthe phenomenon by an interrelation between normal and tangent stresses generated in the interlayer boundaries within the material resulting from substantial difference in the CTEs of the steel types comprising the multilayer material. The hypothesis is confirmed by the substantial effect of compression stresses, normal to the rolling plane ND, generated from the higher CTE steel (AISI 304) on the other component of the multilayer material (1008) that experiences α→γ transformation during heating. It is shown that the value α→γ transformation recorded during 1008 steel heating increases manifold when the steel is a part of the multilayer composition. At the same time 1008 layers experience equally strong, yet tensile stress in directions RD and TD. This results in virtually complete compression compensation in the multilayer material induced by α→γ transformation, which is well marked on the dilatometric curves along the specified directions.

The hypocycloidal model of reliability forming for machinery products is developed. This model allows to provide phased forming, development and keeping of required level of reliability, durability, maintainability and storability for machinery products. The full cycle of reliability forming process includes six stages: pre-project stage, project and design stage, pre-production stage, production stage, post-production stage and operational stage. There are specific questions that are to be decided on every peculiar stage, what is necessary for creating and keeping the required reliability level and to pass from the previous stage to the next one. Based on component parts of this model the appropriate sectors for forming and conservation of required reliability level are highlighted; the stages of manufacturing and operational heredity are described, and the evolution of the model illustrating a repeated cycle of reliability forming process in dynamic is represented. This is how the hypocycloidal model is interconnected with the law of technics progressive evolution, showing that the general feature of them both is a necessity to eliminate all revealed defects of a product. In accordance with mentioned above, the graphical representation of technic object’s evolution is provided as a chain of hypocycloids, which have every cycle of six stages repeated on a new and higher level. Accordingly, it determines a renewed content, which will meet the requirements of a given time period. Taking into account a destination and structure (composition) of technical objects, the process of its technical operation can be represented as a sequential change of various states placed in time dependence. In application to equipment used for oil and gas well drilling, including considerable amount of its states and transitions, the cascade graph of technical operation process for these objects is provided. The represented graph includes mounting the object at a site of operating point; bringing it into condition of operational readiness; usage as intended; periodic execution of performance diagnostics; technical maintenance await condition; scheduled and unscheduled current repairs; unit-based servicing and major repairs. Besides, for particular types of equipment the next features have also been taken into consideration: dismantling and subsequent disassembly at operating point; transportation; preparing for installation at new location or placing the unites or the entire installation into reserve; their storage and delivery into any operational state at another location. As an example, the samples of according trajectories selected from states and translations graph are represented. The amount of probable trajectories through the cascade graph and their concrete selection are highly dependent on a problem statement. Based on the obtained graphs the proposed techniques provides implementation of work on improvement of reliability level continuously, from a product-analog to a new product.

The aim of the work is to obtain an empirical model for calculating the value of the spark gap in the electrical discharge machining of 38X2H2MA steel. Due to the fact that the discharge machining is a non-contact method, when the tool electrode is inserted into the workpiece between the end faces and the side surfaces of the tool electrode and the cavity formed, respectively, the end and side clearances are formed. The main factors affecting the size of the gaps are processing modes and material of the electrodes. The actual task is to predict the size of the spark gap when processing chromium-containing steels, depending on the modes of copy-piercing erosion processing. To obtain the empirical model, the method of factor cladding of the experiment with subsequent regression analysis was used in the work. The criterion for optimality of a plan in orthogonal central compositional planning is the orthogonality of the columns of the planning matrix. For the experiment, the following factors are selected: I - current strength (A), Ton - pulse time (μs), Tau - pulse fill factor (%). According to the carried out experiment and the subsequent regression analysis, a model is obtained for calculating the size of the lateral gap. On the basis of the obtained data, it becomes possible to predict the correction value when processing steel 38X2H2MA. The analysis of the model showed that the size of the gap is affected not only by the factors themselves, but also by their totality. A geometric representation of the law of variation of the lateral clearance value is presented depending on the erosion control modes. The received data allow to make adjustments of the electrode-tool dimensions in order to provide the given parameters of processing accuracy.

The paper presents the basic requirements for gyroscopes. The advantages of solid-state wave gyroscopes are compared with other designs. Particular attention is paid to solid-state wave gyroscopes with a rod sensitive element. The design of the entire product, the structure of its basic elements, the principle of operation of the proposed gyroscope and the method for determining the angular velocity are considered. Factors influencing the technical characteristics of a solid-state wave gyro with a rod sensitive element are established. The substantiation of the choice of constructive factors that are most significant for solid-state wave giroscope is given. The research was conducted in five stages using the ANSYS package. At the first stage of the work, the influence of a number of constructive factors of the sensitive element on such technical characteristics of the resonator as the frequency of natural oscillations, the amplitude of the deviations of the resonator leg, and the stress-strain state of the structural elements are considered. The resonator material and its properties remain unchanged during the research. At the second stage, the influence of the height of the disk on the natural frequencies of the resonator is investigated. The results of the research and the graph of the linear dependence of the natural frequency of the resonator on the ratio of disk height to the diameter of the rod are presented. At the third stage of the investigation, the effect of the waveform of the disc surface on the technical characteristics of the product was determined. The nonlinear dependences of the natural frequency and the amplitude of the displacements of the resonator leg on the number of waves on the disk are determined. In the fourth stage, the influence of the position of the wave on the disk on the technical characteristics of the resonator is established. At the fifth stage, the deviation of the technical characteristics of the resonator from the error in the manufacture of the disc is established. The results of calculations and the obtained geometrical dependences of technical parameters on the design of the sensetive element are presented. The rationale for the choice of combinations of geometric parameters is given. At the end of the article, it is concluded that by changing the rigidity of the disk, it is possible to increase the deviation of the resonator leg and thereby reduce the effect of manufacturing errors on the technical characteristics of the instrument as a whole. The list of literature consists of eight sources.

Rapid wear of the lining is an urgent problem in the electrolytic process for producing magnesium. Increased liner life by 3-4 times, and as a consequence increase the competitiveness of primary magnesium production ensured the modernization of magnesium electrolytic cells by replacing the standard lining on castings from mica crystalline material - fluorophlogopite. The aim of the work is defined as a detailed presentation of the functional and technological scheme and the process of obtaining products from fluorinephlogopite. Potassium fluorophlogopite (KMg3[Si3AlO10]F2) has a glass-ceramic structure, the proportion of the glassy phase is 5-8%, the crystalline part is plate-aggregates to 5 mm length and 0.1 mm in thickness. Based on the literature and practical experience to offer the most optimal functional and technological scheme of production fluorophlogopite products. At its core production fluorophlogopite product technology represents a symbiosis of technology ore-thermal processing of mineral raw materials and foundry. The proximity to the ore-thermal technology is reflected in the processing charge for silicate melt electro thermal process foundry approaches used directly for the development of technology for fluorophlogopite castings. The developed technology includes the following main stages: preparation of raw materials and the preparation of the charge; melting of the charge and the preparation fluorophlogopite melt; production, preparation and assembly of the molds; melt discharging from the furnace into a ladle and casting molds; solidification of castings and removing them from the molds; heat treatment of castings; cleaning, casting processing and quality control; cleaning of exhaust gases; storage of finished products. The technological process can be adapted if necessary in view of the vast resource base of the Perm Region and in terms of the organization of “flexible” technologies.

In electron beam welding, oscillation of the electron beam is popular used as technological tool for avoiding defects. The major forms of the electron beam deflection are straight line along the joint (longitude oscillation), straight line cross the joint (cross oscillation), circle, X -shape oscillation. The other good method for avoiding defects is a welding in penetration through mode. However, the necessary of dynamically stabilization in real time have been for this mode. It is due to stochastic character of the thermo physic processes in zone of electron beam and workpiece metal interaction. Oscillation of the electron beam can reduces of backside crown nonuniformity along the joint. The aim of this work is determination of the influence of electron beam oscillation on the weld root in electron beam welding. It must be noted that it was done in context of decreasing backside crown nonuniformity along the joint. In addition to aforementioned oscillation trajectory of the electron beam, the oscillation on two straight line along the joint is researched too. The cylindrical details of austenitic stainless steel are used as experimental workpieces for welding. Outside diameter of the details is 160 mm, and wall thickness is 10 mm. The penetration depth in welding process was stabilized by the condition that the level of X -ray signal from workpiece backside for each welding pass is constant. The longitudinal-section was executed after implementation of the experimental welding passes. In electron beam welding with longitudinal oscillation or without oscillation of the electron beam occurs significant formation of the penetration peaks in the root part. It should also be noted that X-shape or circle scanning by electron beam leads to some features of the root part formation, as described in the article.

The technological process of manufacturing high-precision products of machine and instrument is a multiparameter process, for which the necessary means of automatic control with dynamic control of quality parameters of products, the processing of measurement data and making control decisions on the adjustment of the technological regime and the possibility for adjustment of the machine, characterized by unlimited accumulated amount of heterogeneous data and knowledge engineering professionals what determines the process of intellectualization of monitoring systems with the integration of information resources into the unified information space of an enterprise in accordance with the concept CALS-technologies. Analysis of the methods and technology of intellectualization of monitoring technology systems based on automated machine modules showed the need to expand on the previously established monitoring framework by introducing intelligent technologies of neural networks, expert and hybrid intelligent systems in order to improve the efficiency of machine building production and quality of precision products. The application of a systematic, integrated approach to complex aspects of adaptation to the conditions of integrated production in the study of the process of monitoring and diagnosing the status of automated machine modules in a modern consideration of the level of technical means and requirements allows us to develop and justify structural complex model that allows to solve the issues of product quality control and production efficiency with the use of intelligent technologies, aimed at solving problems of development of domestic machine tool and improve the quality management system of products. Testing in the framework of the monitoring system in varying degrees, the considered subsystems and methodological foundations of the conducted at leading machine-building enterprises of Saratov.