The effect of several factors on the formation of subcutaneous blisters in continuous cast billets has been analyzed. Using the Shewhart chart for the studied process, its instability was demonstrated despite the fact that the basic process parameters that directly affect the formation of this defect were kept at a relatively stable level. Therefore, the factors not traditionally considered key when working with this defect were selected for consideration. A unique feature of the study is the restricted sampling used for analysis. The qualitative patterns were obtained, which enable us to assess the direction of effect of the considered factors and, to reduce the formation of this defect in a specific plant.
The results of assessing microwaviness using the Marciniak test are presented. It has been established that after stamping cold-rolled galvanized steel, the microwaviness increases by an average of 0.05 μm. A correlation was found between the Marciniak test and the increase in the level of microwaviness after stamping. It is shown that the Marciniak test can characterize the stamping process and be used to assess the suitability of cold-rolled automotive products for subsequent stamping.
An adaptive control system for warehouse logistics using industrial robots has been developed, providing an optimal arrangement of equipment and a substantial increase in warehousing efficiency through parallel processing of products on two lines. The original control algorithm is based on minimizing the operating cycle time of the equipment in accordance with the developed cycle diagram. The proposed system for modernization of warehouse complexes at metallurgical enterprises makes it possible to reduce the duration of the acceptance–packaging–shipment production cycle and increase the throughput of warehouse logistics.
When sharpening a carbide tool, dust-like waste containing tungsten, molybdenum, cobalt, iron and other metals is generated. The problem of tungsten disposal from these wastes has not yet been resolved, and wastes containing 3.0–8.0
Heating and cooling modes of various grades of insulated elevator pipes (IEPs) were studied during vacuum treatment in a unit with a one-way longitudinal coolant supply. Structurally, the IEPs consists of two virtually independent heat exchange sections, corresponding to the inner and outer composite pipes, separated by a sealed annular space. Calculations were performed for the heating, holding, and cooling of the inner composite pipe over a wide range of unit operating parameters. One-way supply of coolant (air) results in an uneven temperature distribution along the pipe’ length, which changes during heat treatment. This results in disproportionate elongation or contraction of the pipe sections. A more uniform temperature distribution along the length of pipes improves the accuracy of temperature determination and control of their linear dimensions. Heating and cooling graphs are provided for pipes with diameters of 48.26 × 4 and 73 × 5.5 mm. Calculations have shown that, under comparable conditions, the heating time for a 73 × 5.5 mm diameter, 12 m long pipe from 20 to 395°C with an air flow at an initial velocity of 15 m/s and a temperature of 400°C was 152 min, which was 18 min longer than for a 48.26 × 4 mm pipe. Calculations have shown that the magnitude of nonuniformity—the difference in pipe temperature at the inlet and outlet—decreases with an increase in diameter. The magnitude of nonuniformity for an individual pipe depends weakly on the initial air flow velocity at a constant inlet temperature. Multi-stage heating or cooling with varying air temperature at the pipe inlet significantly reduces nonuniformity while simultaneously increasing the heat treatment duration. These results can be useful in the development and design of installations for heat treatment of IEPs during vacuum treatment.
A method for improving the reliability of tractors under Vietnamese operating conditions through determining the residual engine service life is presented. The experimental data have been statistically processed with calculating tractor service life. The engine service life can be determined based on the most important part of the internal combustion engine, namely the crankshaft, taking into account the wear level of the main and peripheral journals. The crankshaft wear parameters are determined in the course of experimental studies with a subsequent statistical processing. A fuzzy neural network, constructed in the MATLAB environment, has been used for to determine the residual service life of the tractor. The value of the residual service life provides the ability to prevent failures, to plan the timing and volume of maintenance and repair, as well as to improve the reliability of the tractor.
The work analyzes and studies the issues related to the selection of optimal epoxy adhesive compositions of Russian Federation production used to fix strain gauges in critical conditions. This article reveals the results of the second stage of tests to study the possibilities of using epoxy adhesive compositions present on the Russian market for their use in tensometry. The main objective of the research was to analyze the errors obtained when measuring deformations read by strain gauges recorded by various epoxy adhesives in order to determine the composition that ensures the minimum measurement error when monitoring the deformations of machine parts. It should be noted that during the tests, foil strain gauges were used, which were fixed to the tested aluminum alloy plate with five brands of various epoxy adhesive compositions. Then the tested plate and all samples were subjected to the same deformation value, which made it possible, by changing the resistance of each of the fixed strain gauges, to estimate what error was introduced by each of the adhesive compositions. Based on the results of the obtained data, it is possible to select the optimal epoxy adhesive composition that provides a minimum level of errors when measuring deformations by strain gauges when operating under critical conditions.
This work examines the potential of 3D modeling and 3D printing technologies to repair lightly loaded plastic parts. The technological capabilities of 3D printing for repairing lightly loaded parts have been analyzed including the stages of 3D scanning, modeling, and material selection. The optimal material for producing a part with the specified performance characteristics has been determined. The stages of repair using 3D modeling and 3D printing have been described.
It is shown that Mg, Ca, and Ba oxides and sulfides in carbon steels cannot serve as crystallization centers for δ-ferrite or austenite microcrystals, since they do not comply with the Dankov–Konobeevskii principle of structural and dimensional correspondence. Nanostructured formations consisting primarily of elementary iron nanocrystals serve as these centers. A thermodynamic calculation of the modification of carbon steels with Mg, Ca, and Ba was performed using the developed technique. The standard enthalpy of the refining reactions of iron nanocrystals from adsorbed oxygen was chosen as the main modification parameter. It is shown that Mg, Ca, and Ba effectively refine iron nanocrystals from adsorbed oxygen in carbon steel melts. Moreover, magnesium is considered to be the most powerful modifying element. As a result, the concentration of crystallization centers of δ-ferrite or austenite microcrystals significantly increases during the crystallization of carbon steels. This facilitates the production of castings with a modified primary structure.
This article reviews and analyzes studies of laboratory and industrial research on asymmetric sheet rolling. The main techniques of asymmetric sheet rolling for manufacturing products with improved properties compared to traditional rolling methods, are presented. It is established that virtually all existing studies on laboratory and industrial testing of asymmetric sheet rolling report improved microstructure, enhanced mechanical properties, and reduced rolling forces. However, when organizing and implementing asymmetric rolling technology on existing rolling mills, attention should be paid to the design features and technical capabilities of the rolling mill drive systems to ensure stable process performance under conditions of different speeds of the upper and lower work rolls, as well as speed alignment when using rolls of different diameters. This is especially true for group drive systems, where a single motor drives both the upper and lower rolls.
Using physical and computational experiments, the causes of wrinkle formation during upsetting simulating the hot rolling of section (bar) steel were examined. The influence of non-uniform development of properties in metal microvolumes due to the distribution of strains and stresses, as well as features of the structure-formation processes, strain hardening and thermal softening, was investigated. It is shown that wrinkle formation requires a high level of property inhomogeneity, which develops not only during the deformation under consideration but also during prior deformation stages and during pauses between deformation steps.
Influence of the properties and composition of iron carbonate (siderite) corrosion product deposits under operating conditions of gas pipelines transporting CO2-containing products was studied. Durability of the resulting film and its spalling (removal) from the steel surface influence the formation of localized defects during carbon dioxide corrosion. Effect of liquid media composition on the formation of stoichiometric and nonstoichiometric siderites, which determine their corrosion protective properties, was analyzed. Degree of substitution of iron ions in siderite (as a result of its isomorphism) with other cations and the effect of alcohol concentration in the corrosive liquid medium on this degree were determined. Based on the analysis of composition of carbon dioxide corrosion products, the effect of test conditions on the following characteristics was determined: disruption of the intensity ratio of the (012) and (104) iron carbonate peaks, shift of its (104) peak from the reference value, and the ratio of its nonstoichiometric modifications formed.
New designs of conveyor-machine trolleys with housings fabricated by welding separate parts from structural steel rolled stock are described, together with their advantages and disadvantages. New shapes of the housings’ load-bearing beams are proposed, featuring internal cavities that allow cold air to be drawn into them by vacuum chambers. Cooling the horizontal flanges and vertical webs of the load-bearing beams with cold air reduced the beams’ thermal heating and decreased the housing deflection.
This work is aimed at developing and industrially testing a comprehensive digital method for certifying the flatness of cold-rolled strips, in order to provide a system for the transition from occasional visual inspection to full-scale, real-time quality monitoring. The methodology provides for the implementation of a continuous measurement unit using a stress meter that generates two-dimensional residual stress distribution maps (a digital twin of the coil), and an intelligent certification unit with automatic signal classification on a three-level scale. In the scope of the system testing, a problematic coil of DC04 grade steel with a defect in the form of a one-sided right-hand wave is analyzed in detail. The developed approach provides a metrologically sound basis for prompt technological decision-making, which serves as a prerequisite for the development of a closed-loop control system. The prospects for a future development of the system consist in the integration thereof into control loops, which opens the potentialities of transition from the passive detection of flatness defects to an active predictive prevention thereof.
A critical analysis of methodological developments for technical systems failure risk analysis technologies is conducted. It is proposed that the existing theoretical foundation for the technical condition of equipment, their reliability, and durability be transformed into digital platforms for collecting and processing databases. The need to evaluate a design based on the level of information content of element interactions is substantiated, specifically the technological capabilities of obtaining sufficient information to monitor the parametric features of the system condition over a specified period of operation within the designated service life and resource limitations in case of its extension. An architectural diagram describing the logical structuring based on the signs of functional failures is developed, based on which algorithms for identifying deviations in system operation with a step-by-step assessment of each system element were developed. A model for information typification of machine assembly and defect detection technology is proposed by creating a component base for technological support tools for repair and restoration work using modular technologies of the logical apparatus for recognizing interaction surfaces.
Simulation of microstructure formation and properties for advanced high-strength hot-rolled dual-phase steels is considered. Such steel grades are traditionally produced using a two-stage sprinkling process on an outlet roller table after hot rolling. Since different manufacturers have different equipment parameters, selecting economically alloyed chemical compositions and verifying the feasibility of achieving required microstructure necessitate rapid solutions, which is worthwhile to perform with the use of mathematical simulation methods and software packages. This paper presents a trial simulation of the conditions for the formation of target microstructural phase components for DP-grade steel as applies to several possible chemical compositions. Calculation stages are described, and conclusions are drawn concerning the applicability of different approaches.
The article describes the development of a machine for the automatic cutting of rubber brake caliper piston seals from a so-called “sleeve” (a hollow cylindrical blank), equipped with an automatic microcontroller-based control system. The authors propose a machine design that comprises a mechanical part (bed, axis guides, etc.) and an electronic part (microcontroller, motor drivers, motors, etc.). The implementation of the developed machine prototype can contribute to the growth of small businesses in the mechanical engineering sector in general, and in the automotive industry in particular. According to preliminary estimates, the economic effect of using this CNC machine will significantly exceed that of existing analogues.
The technological features of the chamber method for processing surfaces of parts with the use of unfixed grinding material are described. Manufacturing methods and ways for improving technological equipment the models of abrasive grains to actualize them, as well as mathematical dependencies that make it possible to predict the process efficiency are considered.
An analysis was made of possible causes of the appearance of surface defects in the form of wrinkles during hot rolling of round steel. Two alternatives are considered: rupture of the surface layer and formation of a fold due to non-uniform metal flow caused by non-uniform properties of the micro-volumes of the deformed metal. By means of full-scale and computer experiments it was shown that wrinkle formation occurs as a result of the gradual transformation of the microrelief that is formed on the metal surface during plastic deformation, with constriction (pinching) of the central part of the trough due to non-uniform deformation of the micro-volumes. There are two main reasons for the non-uniform deformation of micro-volumes: (1) non-uniformity of the initial properties acquired during previous processing; this has a probabilistic character and is caused primarily by the nature of structure-formation processes (strengthening, recovery and recrystallization, chemical composition inhomogeneities, etc.); (2) non-uniformity acquired during deformation, caused by heterogeneity of the deformed state in the considered deformation process; this has a systematic character determined by the geometric and thermo-deformation parameters of the deformation process under consideration.
The presence of mechanical contaminants in well production, as well as the corrosive aggressiveness of produced water, leads to corrosion-mechanical wear of oilfield equipment. To prevent corrosion-mechanical failure of oil production equipment, a comprehensive inhibitor based on fatty acids, Asidol, and technical lecithin was developed. The developed inhibitor not only effectively slows corrosion but also reduces erosive wear between rubbing parts. Laboratory studies showed that the reagent has high inhibiting properties at a concentration of 500 mg/L. The overall corrosion protection reached 94–96
