Mill Line Research Articles

Influence of Operating Modes of High-Temperature Thermomechanical Processing on Mechanical Properties of Reinforcing Bars

The strenghening thermomechanical treatment represens the combined processing treatment – a combination of plastic deformation and hardening in one technological process. Year after year, it is more widely applied in industry.Purpose of research. The study of strenghening thermomechanical treatment operating modes influence on the formation of mechanical properties of steel, which is a very important scientific problem associated with obtaining materials with a given set of mechanical features.Methods. High-temperature thermomechanical treatment was conducted under the conditions in which the processes of recrystallization of deformed austenite were partially or completely supressed, and the process of polygonization got the most development, with the goal of forming a developed substructure of austenite inherited by martensite during subsequent quenching.The paper investigated the change in the properties of high-strength reinforcement under heating (tempering) with different intensity. High-temperature thermomechanical treatment was carried out by including a hardening device in the technological line of the mill No. 280 LLC “Tulachermet-steel”. The studies were carried out on two modes of mill No. 280 operation. Low-carbon reinforcing steels St3 and ST5 were accepted as the studied steels.Results. It has been experimentally established that the maximum cooling capacity of the existing hardening device is manifested when three working sections with a water pressure of about 13 in each section are turned on. In this case, high-temperature thermomechanical treatment should be carried out at the maximum cooling rate in the strengthning device in accordance with the specified strength class, i.e., include the least number of working sections. Intensive cooling mode contributes to the formation of a homogeneous structure in the reinforcement with a high mechanical complex. It was found that during high-temperature thermomechanical treatment it is advisable to withstand the deformation temperature in the range of 1000...1050 ℃ to guarantee the production of reinforcement of a given class. It has been shown that the inclusion of a strengthening device in the mill line directly behind the flying shears, and not behind the finishing stand of the mill leads not only to the trouble-free operation of shears, but also to an increase in the post-deformation aging between the end of deformation and the beginning of bar hardening to a value close to the optimal, responsible for the formation of a polygonal substructure in austenite, the inheritance of which by martensite provides high mechanical properties of steel after high-temperature thermomechanical treatment.Conclusion. These results can be applied to create resource-saving material treatment processes.

Повышение срока эксплуатации литых броней из высокомарганцевой стали мельницы полусамоизмельчения

At the processing plants of the mining industry, a significant part of the total processing costs (from 45 to 65%) is spent on crushing and grinding operations, including mill lining. The efficiency of grinding equipment in the conditions of abrasive impact of ore and a continuous operation requires periodic replacement of a worn-out lining. The costs for its purchase, delivery and installation during a year amount to tens of millions of rubles, and the equipment downtime associated with the replacement of the lining reduces the volume of finished products by hundreds of millions of rubles per year. The practical efficiency of imported mill liners is not always confirmed by the expected positive result of their actual operation, and an increase in the equipment utilization coefficient (EUC), but their use definitely requires significant financial costs and entails risks in an unstable political and financial situation. Therefore, the task of increasing the service life of the mill liners is urgent. The paper presents a suggested and implemented solution to increase the lifetime of 110G13L steel lining for the wet semi-autogenous grinding mill (SAG mill-70х23). It includes monitoring of the actual liner operation and a mathematical simulation of the ore and ball trajectory in the mill, reveals zones of intensive wear, defects of liner castings and developed new structures of the lining elements. Applying the simulation software package, the authors studied the existing casting technologies, found reasons for defects and developed the casting technology for a new design of liners excluding defects. The paper contains industrial tests of the liners of a new design manufactured according to the developed technologies.

Математическая моделирование температурных режимов листовых станов с печными моталками

The most important task in the development of technology for the sheet rolling process is to determine the temperature of the strip in the technological line of the mill. This article proposes a model of the temperature conditions of strip rolling on a mill with furnace coilers. The mathematical model takes into account the temperature changes in the deformation zone during rolling and transportation of the strip in the mill line, in heating devices - furnace of the coilers of the Steckel mill. It is possible to determine the change in temperature of the strip on coils and the surface of strip wind up in roll when the coiler furnaces. The mathematical model can be used for engineering calculations, as well as a tool for the scientific analysis of technological processes of sheet rolling.

C. Wright Mills and the Cuban Revolution: An Exercise in the Art of Sociological Imagination

C. Wright Mills and the Cuban Revolution: An Exercise in the Art of Sociological Imagination

Performance of fresh market tomato (Solanum lycopersicum Mill) lines as influenced by pruning

Tomato production in the Philippines is dominated by conventional farmers who do not practice pruning. Currently, rampant occurrence of diseases almost wiped out the industry and availability of resistant seeds became a problem however several studies reported that pruning lessened diseases and enhanced yield. The study aimed to evaluate the effect of pruning on the performance of different fresh market tomato genotypes. The experiment was laid out in factorial design using Randomized Complete Block Design with pruning as Factor A and tomato genotypes as Factor B with Harabas (Harabas Rescuer 746) as control. Pruning obtained thicker stem and 18% higher fruit set, reduced Tomato Yellow Leaf Curl Virus and increased tomato yield by producing a higher number of marketable fruits. AVTO 1173 produced the heaviest and largest fruits with the least TYLCV. Pruning is a beneficial practice that farmers could adopt, along with AVTO 1173 as a substitute for the Harabas, check variety. Additional trials of AVTO 1173 should be conducted in different locations to further verify its adaptability and performance in other situations.

Analysis of Efficiency of Roll Pass Design Options for Roughing Stands of Section Rolling Mill

The analysis of two roll pass design options of ten roughing stands atOJSC “MMK” 370 rolling mill has been performed. The usage of a new form of the roll grooves will allow achieving higher durability of the rolls. Lesser rolls consumption will allow saving up to 800K rubles annually. More uniform load distribution by the stands will reduce the possibility of main mill lines equipment breakdowns due to the jumps of rolling torque in the most loaded non-equiaxial stands. Better contact conditions and higher billet stability at the input into equiaxial grooves will reduce the amount of metal clogging. Moreover, a changed strain diagram – with higher roll pass design efficiency factor – will increase the roll out of foundry production defects.

Study of the Life of Replaceable Inserts During High-Speed Steel and Wear-Resistant Cast Iron Machining

Comparative analysis is provided for hard-alloy inserts from different producer firms based on studying their durability during machining mill linings, and also pump wheels and casings.

A three-dimensional mathematical model to predict air-cooling flow and temperature distribution of wire loops in the Stelmor air-cooling system

Controlling the forced air cooling conditions in the Stelmor conveyor line is important for improving the microstructure and mechanical properties of steel wire rods. A three-dimensional mathematical model incorporating the turbulent flow of the cooling air and heat transfer of the wire rods was developed to predict the cooling process in the Stelmor air-cooling line of wire rolling mills. The distribution of cooling air from the plenum chamber and the forced convective heat transfer coefficient for the wire loops were simulated at the different locations over the conveyor. The temperature profiles and cooling curves of the wire loops in Stelmor conveyor lines were also calculated by considering the convective heat transfer, radiative heat transfer as well as the latent heat during transformation. The calculated temperature results using this model agreed well with the available measured results in the industrial tests. Thus, it was demonstrated that this model can be useful for studying the air-cooling process and predicting the temperature profile and microstructure evolution of the wire rods.

Production Capacity and Workstations Load in the Animal Feed Production Process

Abstract Production capacity is the amount of production with the determined assortment structure possible to achieve by a particular production unit in a determined time at the optimal use of production factors and at maintaining the products quality corresponding to standards. The objective of the paper was to determine the production power and output of particular workstations which constitute an assembly line of dry animal feed. The scope of research covered an assembly line in the establishment which produces dry feed for pet animals. Based on information and documentation obtained from the company manager and on the work schedule determined for particular workstations, the operation time of a machine, human work time (operation of a machine) and operation time of the entire station with its working surface was determined. Research showed that workstations which constituted the assembly line of dry animal feed were loaded within 76 to 86%. The lowest loading was reported in the mill and LP02 assembly line and it was respectively 76 and 78%. Whereas loading of the remaining devices was comparable and was at the level within 84 to 86%.

Mathematical Model of Plates and Strips Rolling for Calculation of Energy Power Parameters and Dynamic Loads

Presents the results of studies of innovative materials in the field of metallurgy. The article describes mathematical models for calculating energy-parameters of hot rolling plates and strips using a more correct evaluation of external friction, which is necessary for precisely determining the values of the dynamic loads in the drive’s line of rolling mills stands. The results can be used for designing rolling mills drive lines’ mechanical facilities.

Research on dynamics of energy-intensive mill lining with mechanical activation of silicon powder

Research on dynamics of energy-intensive mill lining with mechanical activation of silicon powder

Research and application of multiple constrained hot strip mill scheduling problem based on HPSA

This paper proposes a new algorithm combining particle swarm optimization (PSO) and simulated annealing (SA) to solve hot strip mill scheduling problem which is formulated as a multi-objective optimization problem with multi-constraints which process schedule constraints, production means constraints, and energy consumption constraints into account. The constraints in hot mill processes are analyzed in three aspects—process schedule, product means, and energy consumption. According to actual experience, Hybrid Vehicle Routing Problem (HVRP) model is established to solve the scheduling problem which is a combination of variable fleet vehicle routing problem, prize collection vehicle routing, and capacitated vehicle routing problem. In this new algorithm, the PSO algorithm is redefined and modified by introducing metropolis criterion of SA twice, which is used to update two extremes of particle swarm, including the individual optimal solution and the global optimal solution to improve the convergence precision and the convergence rate. The proposed method has been applied in a hot mill line to verify its availability and feasibility by comparing the manual scheduling result.

Accelerated Cooling After Controlled Rolling During Heavy Plate Pipe Steel Manufacture in 3600 Mill at the Azovstal Metallurgical Combine

Contemporary controlled rolling technology with accelerated cooling is assimilated at the Azovstal Metallurgical Combine, used in production of plate intended for manufacturing gas and oil pipelines of considerable diameter. General characteristics are provided for the SMS-Demag accelerated controlled cooling unit in the plate workshop within the 3600 mill line. Mechanical properties are tested and the microstructure is examined. Batches of pipe steels of various grades satisfy test specifications and are estimated as favorable according to results for pipes manufactured from them.

Manufacturing technology for cast inserts of new wear-resistant alloys for combined mill linings

The efficiency of combined use of elastomers (rubbers) and wear-resistant steels and cast iron for mining and metallurgical equipment is studied: mill lining, hydrocyclones, modular screens, conveyor belt grids, crushers, etc. Rubber absorbs impact loads, dampens them, and thereby prevents breakage of high-hardness wear-resistant steels and cast iron. It is established by research that combination within the structure of chromium-manganese alloys of the transition class (1.6–2.2% C) types 200G4Kh5L, 200G5Kh2L (200G5Kh2TFL) with a sufficient amount of hard carbide phases and a ductile austenite-pearlite matrix provides high indices for impact-abrasive and impact-abrasive-corrosion resistance. Inserts of combined rubber and metal linings of metals of the transition class type are effective.

The Research Progress of High Efficiency Energy-Saving Grinding Equipment

This paper explains some deficiencies of grinding equipment in our country at present,introduces the angular screw lining plate and trench lining plate from mill lining plate ,also their application effects; and introduces the static and dynamic pressure bearing and the center drive energy-saving mode from the transmission part, on the basis of which take a brief introduction of a new device and its application status, then the development trend in the future is prospected.

MELHORIA DO PROCESSO DE REAQUECIMENTO DE PLACAS NA USIMINAS POR MEIO DE SIMULAÇÃO MATEMÁTICA

Basic characteristics and application examples of the mathematical simulator for reheating process in walking-beam type furnaces, that has been developed and applied to Usiminas plate mill line at Ipatinga, are shown in this paper. This is a bi-dimensional mathematical model solved by the finite volume method, validated by temperature measurements inside the slab during heating and coded as a visual tool. Among these applications, the following can be highlighted: (i) determination of suitable furnace zone temperatures and residence times for processing steels by accelerated cooling technology; (ii) determination of slab average temperature at discharging as well as at each zone exit, supplying data to be fed to the automation system at the comissioning stage; (iii) analyses of slab thermal distribution through the reheating process, enabling operational optimization.

Integrated approach to maintaining the temperature regime on continuous hot-strip mills

The hereditary nature of structural and textural changes that take place in metal during its continuous hot rolling makes it necessary to adopt an integrated approach to control of the main parameter of the rolling operation – the temperature of the metal as it is being rolled. It is shown that a systems approach needs to be taken to maintaining the prescribed temperature regime on all sections of the mill line, from the heating of the metal prior to rolling to cooling of the finished product as it is dispatched to the next production line.

Technical diagnosis and diagnostic modeling of mechanisms in the main line of a rolling mill

Results are presented from vibrational diagnosis and diagnostic modeling of mechanisms in the main line of rolling mills. It is shown that defects found in these mechanisms affect fluctuations in the thickness of rolled strip in the longitudinal direction.

Development of thermal strengthening technology for reinforcing bar at the West Siberian metallurgical combine

Stages are considered for the development of thermal strengthening technology in different classes of reinforcing bar at the West Siberian Metallurgical Combine. The structural evolution of devices for thermal strengthening of reinforcement 10–50 mm in diameter in a bar rolling mill line, and also production developments for optimizing interrupted hardening regimes are analyzed. Results of metallographic and electron-microscope studies of the structural composition formed in a bar cross section are used to demonstrate thermal strengthening of A500S class reinforcement No. 32 from steel 18G2S. The effect of induced cooling regimes on the strength of reinforcing bar and individual layers of a structural composite is analyzed. It is established that the main contribution to strength improvement is made by hardened structures of the surface layer. Continuous improvement of thermal strengthening technology and devices makes it possible to increase production efficiency for reinforcing bar due to a reduction in alloying used for the steels.

Speed simulation of continuous pipe rolling

Continuous pipe rolling on a floating or static man� drel is a complex process, conducted in a continuous mill with interacting cells. Therefore, changing the parameters in any section of the continuous mill mod� ifies the parameters throughout the mill line. This is primarily the result of change in the intercell tension of the pipe, which is determined by the rolling speed. As we know, the intercell tension in continuous rolling has a significant influence on the pipe quality. On the one hand, relatively high intercell tension reduces the eccentric discrepancy in the pipe’s wall thickness; on the other, it affects the mean wall thick� ness and, with fluctuations in the course of rolling, it may create longitudinal differences in wall thickness. In addition, increase in intercell tension facilitates pipe capture by the mandrel, especially in the case of