A regression-tree multilayer-perceptron hybrid strategy for the prediction of ore crushing-plate lifetimes

Highly tensile manganese steel is in great demand owing to its high tensile strength under shock loads. All workpieces are produced through casting, because it is highly difficult to machine. The probabilistic aspects of its casting, its variable composition, and the different casting techniques must all be considered for the optimisation of its mechanical properties. A hybrid strategy is therefore proposed which combines decision trees and artificial neural networks (ANNs) for accurate and reliable prediction models for ore crushing plate lifetimes. The strategic blend of these two high-accuracy prediction models is used to generate simple decision trees which can reveal the main dataset features, thereby facilitating decision-making. Following a complexity analysis of a dataset with 450 different plates, the best model consisted of 9 different multilayer perceptrons, the inputs of which were only the Fe and Mn plate compositions. The model recorded a low root mean square error (RMSE) of only 0.0614 h for the lifetime of the plate: a very accurate result considering their varied lifetimes of between 746 and 6902 h in the dataset. Finally, the use of these models under real industrial conditions is presented in a heat map, namely a 2D representation of the main manufacturing process inputs with a colour scale which shows the predicted output, i.e. the expected lifetime of the manufactured plates. Thus, the hybrid strategy extracts core training dataset information in high-accuracy prediction models. This novel strategy merges the different capabilities of two families of machine-learning algorithms. It provides a high-accuracy industrial tool for the prediction of the full lifetime of highly tensile manganese steel plates. The results yielded a precision prediction of (RMSE of 0.061 h) for the full lifetime of (light, medium, and heavy) crusher plates manufactured with the three (experimental, classic, and highly efficient (new)) casting methods.Government of theRussian Federation, Russia (contractNo02.A03.21.0011), by theproject TIN2015-67534-P of the Ministerio de Economía Competi-tividad of the Spanish Government, Spain, and the projectBU085P17 of the Junta de Castilla y León (both projects co-financed through European-Union FEDER funds) and by the Conse-jería de Educación of the Junta de Castilla y León and the EuropeanSocial Fund with the EDU/1100/2017 pre-doctoral fellowship

MANAGING THE PROCESS OF THE CASTING STRUCTURE FORMING WITH PULSED ELECTROMAGNETIC FIELD

The results of experimental studies of the AK7ч alumunium alloy solidification in the electromagnetic field produced by a pulse generator of the FID-technology are presented. The scheme of the experimental set, the photos of microstructures of the alloy, the results of physical and mechanical tests termometring of the alloy crystallization and X-ray analysis are adduced

Impact of fire on the stability of tunnels

The purpose of this thesis is to study the influence of fire on the stability of tunnels. During the last few years a number of fires have taken place in tunnels. For example, the fires in the Channel and the Tauern tunnels took several human lives and caused significant damage to the tunnel structures. This thesis is a review of research on the influence of fire on the rock and rock reinforcement performed during the last 40 years. High temperature results in changes of the thermal, mechanical and physical properties of rock and rock reinforcement (shotcrete, bolts, concrete lining). During a fire damage to rock and concrete structures occur due to spalling. Failure and collapse of tunnels have occurred as a result of high temperatures. Spalling in concrete can be avoided by adding steel or polypropylene fibres. Some tests studied in this thesis investigate their influence on the fire resistance of concrete. Some methods for to estimating the decrease of the strength of concrete due to fire are presented. It is necessary to perform a more detailed investigation of the fire resistance of different types of rock, because rocks with low fire resistance should be additionally supported or protected. The influence of grouting on the fire resistance of rock should also be more investigated.Validerat; 20101217 (root

Experimental Determination and Calculation of the Wire Drawing Force in Monolithic Dies on Straight-Line Drawing Machines

In this article, a mathematical model has been developed for calculating the energy-power parameters of the drawing process in monolithic dies on straight-line drawing machines, and its adequacy has been validated in experimental wire drawing on a laboratory automated drawing machine. The program allows us to calculate drawing stress, drawing force, tensile strength and yield strength of the alloy after wire drawing, safety factor, and drawing power. The developed mathematical model differs in that it allows us to evaluate the uniformity of deformation over the wire section, depending on the technological parameters of the deformation zone, namely, the semi-angular die, the coefficient of friction and the degree of deformation. To select the technological parameters of the deformation zone, which ensure uniform deformation over the wire cross-section, a nomogram was compiled. The equations of hardening during nickel NP2 wire drawing are obtained. The calculation of energy-power parameters of drawing nickel NP2 (Ni 99.6) wire ∅1.8 mm from ∅4.94 mm wire rod is given. Experimental studies have been carried out to determine the energy-power parameters of nickel wire drawing on a laboratory drawing machine with an installed ring strain gauge to determine the drawing force. A change in the friction coefficient by 0.02 when drawing nickel wire leads to an increase in stress and drawing force by 20%. To improve the accuracy of the developed mathematical model, it is shown that in the future, it would be necessary to conduct experimental studies on a laboratory drawing machine to determine the effect on the energy-power parameters of the drawing process of the values of technological parameters entered into the program as constant real values, such as the friction coefficient, die half-angle, drawing speed, and back tension

Developing Digital Observer of Angular Gaps in Rolling Stand Mechatronic System

Algorithms for monitoring the rolling mill mechatronic system state should be developed on the basis of modern digital technologies. Developing digital shadows (observers) of system state parameters in the periodic measurement mode is promising. This study relevance is defined by frequent emergency breakdowns of rolling stand mechanical transmissions. Most breakdowns are caused by worn end clutches (heads) of countershafts (spindles) transmitting rotation from the motor to the rolls. This is caused by elastic oscillations due to closing angular gaps when the metal enters the stand. The spindle joint angular gap increases over time with the mill operation. Therefore, it is an important diagnostic parameter that allows for an estimation of the transmission serviceability. In this regard, the problem of monitoring the angular gaps in the rolling stand mechatronic systems is relevant. The paper considers developing an observer of angular gaps in the spindle joints of the ‘electric drive-stand’ mechatronic system of the plate Mill 5000 of Magnitogorsk Iron and Steel Works PJSC (MMK PJSC). The monitored signal (angular gap) is calculated with the mathematical processing of the motor’s physical parameters (speed and electromagnetic torque), measured at a given frequency. The gap is determined indirectly by integrating the speed during its closing. To achieve this, the speed is controlled according to the triangular tachogram at no load. The stand’s electromechanical system modes have been studied using mathematical simulation. The observer’s practical use expediency has been reasoned. The structure of the observer-based angular gap monitoring information system is given. The system has been full-scale tested on Mill 5000, which has confirmed the developed algorithm efficiency. The study’s contribution is a justified and implemented concept of a relatively simple technical solution that can be commercially implemented without extra costs. The angular gap calculation algorithm does not involve complex mathematical techniques and can be implemented in industrial rolling mill controllers. Monitoring is automated without human involvement, which eliminates the human factor. The solution has a specific practical focus and is recommended for implementation at operating rolling mills

Experimental Determination and Calculation of the Wire Drawing Force in Monolithic Dies on Straight-Line Drawing Machines

In this article, a mathematical model has been developed for calculating the energy-power parameters of the drawing process in monolithic dies on straight-line drawing machines, and its adequacy has been validated in experimental wire drawing on a laboratory automated drawing machine. The program allows us to calculate drawing stress, drawing force, tensile strength and yield strength of the alloy after wire drawing, safety factor, and drawing power. The developed mathematical model differs in that it allows us to evaluate the uniformity of deformation over the wire section, depending on the technological parameters of the deformation zone, namely, the semi-angular die, the coefficient of friction and the degree of deformation. To select the technological parameters of the deformation zone, which ensure uniform deformation over the wire cross-section, a nomogram was compiled. The equations of hardening during nickel NP2 wire drawing are obtained. The calculation of energy-power parameters of drawing nickel NP2 (Ni 99.6) wire ∅1.8 mm from ∅4.94 mm wire rod is given. Experimental studies have been carried out to determine the energy-power parameters of nickel wire drawing on a laboratory drawing machine with an installed ring strain gauge to determine the drawing force. A change in the friction coefficient by 0.02 when drawing nickel wire leads to an increase in stress and drawing force by 20%. To improve the accuracy of the developed mathematical model, it is shown that in the future, it would be necessary to conduct experimental studies on a laboratory drawing machine to determine the effect on the energy-power parameters of the drawing process of the values of technological parameters entered into the program as constant real values, such as the friction coefficient, die half-angle, drawing speed, and back tension

Developing Digital Observer of Angular Gaps in Rolling Stand Mechatronic System

Algorithms for monitoring the rolling mill mechatronic system state should be developed on the basis of modern digital technologies. Developing digital shadows (observers) of system state parameters in the periodic measurement mode is promising. This study relevance is defined by frequent emergency breakdowns of rolling stand mechanical transmissions. Most breakdowns are caused by worn end clutches (heads) of countershafts (spindles) transmitting rotation from the motor to the rolls. This is caused by elastic oscillations due to closing angular gaps when the metal enters the stand. The spindle joint angular gap increases over time with the mill operation. Therefore, it is an important diagnostic parameter that allows for an estimation of the transmission serviceability. In this regard, the problem of monitoring the angular gaps in the rolling stand mechatronic systems is relevant. The paper considers developing an observer of angular gaps in the spindle joints of the ‘electric drive-stand’ mechatronic system of the plate Mill 5000 of Magnitogorsk Iron and Steel Works PJSC (MMK PJSC). The monitored signal (angular gap) is calculated with the mathematical processing of the motor’s physical parameters (speed and electromagnetic torque), measured at a given frequency. The gap is determined indirectly by integrating the speed during its closing. To achieve this, the speed is controlled according to the triangular tachogram at no load. The stand’s electromechanical system modes have been studied using mathematical simulation. The observer’s practical use expediency has been reasoned. The structure of the observer-based angular gap monitoring information system is given. The system has been full-scale tested on Mill 5000, which has confirmed the developed algorithm efficiency. The study’s contribution is a justified and implemented concept of a relatively simple technical solution that can be commercially implemented without extra costs. The angular gap calculation algorithm does not involve complex mathematical techniques and can be implemented in industrial rolling mill controllers. Monitoring is automated without human involvement, which eliminates the human factor. The solution has a specific practical focus and is recommended for implementation at operating rolling mills

Effect of the Ti6Al4V Alloy Track Trajectories on Mechanical Properties in Direct Metal Deposition

The TiAl6V4 alloy is widely used in selective laser melting and direct laser melting. In turn, works devoted to the issue of how the track stacking scheme affects the value of mechanical properties is not enough. The influence of the Ti6Al4V alloy track trajectories on the microstructure and mechanical properties during direct laser deposition is studied in this article for the first time. The results were obtained on the influence of «parallel» and «perpendicular» technique of laying tracks in direct laser synthesis. All studied samples have a microstructure typical of the hardened two-phase condition titanium. Here, it is shown that the method of laying tracks and the direction of load application during compression testing relative to the location of the tracks leads to a change in the ultimate strength of the Ti-6Al-4V alloy from 1794 to 1910 MPa. The plasticity of the Ti-6Al-4V alloy obtained by direct laser alloying can vary from 21.3 to 33.0% depending on the direction of laying the tracks and the direction of the compression test. The hardness of alloys varies in the range from 409 to 511 HV and depends on the method of laying the tracks and the direction of hardness measurements