Rolling Operation Research Articles

Optimizing production of hot forging process with waste control and die life improvement

The aim of this research work is to optimizing production of hot forging and its defects by applying some process controlling and product controlling methods. In this research with help to control technologies the forging defects which are classified with three different way to carry, surface defects, inspection defects and also waste controlling analyses are carried out. The effects of die life on forging process are analyzed in the addition to control in process defects by adding of one new operation (Hot padding). To minimize the forging waste in formation of flash by statistical analysis is also covered in this paper. To control in process defects with die life improvement process with regular repairing operations such as resink, stress relieving, gauzing operation to control in process crack with rolling operation corrective action are also covered in this paper.

The Hot Ductility, Microstructures, Mechanical Properties and Corrosion Resistance in an Advanced Boron-Containing Complex Phase Steel Heat-Treated Using the Quenching and Partitioning (Q&P) Process

The objective of this research work is to obtain the hot ductility behavior, and the structural, microstructural and mechanical characteristics of one of the latest generation of AHSS steels, a complex phase (CP) steel microalloyed with boron (0.006 wt.%), processed by hot and cold rolling operations and heat-treated using two different quenching and partitioning (Q&P) treatments, a one-step partitioning (quenching to 420 °C) and the other a two-step partitioning (quenching to 420 °C and reheated to 600 °C). The results show that boron has a marked effect on the solidification process of the CP steel, refining the austenitic grain size. Due to its refinement, the boron-containing steel had better ductility throughout the temperature range examined (700–900 °C), i.e., the hot ductility trough. Thus, the minimum percentage of reduction in area (%RA) value occurring at 800 °C was 43% for the boron-free steel, compared with 58% for the boron-containing steel. Hence, cracking would not be a problem when straightening the strand on continuous casting. The benefit of boron addition on the room temperature properties was found to be very marked for the higher temperature two-step partitioning treatment, giving a yield stress of 1200 MPa, a UTS (ultimate tensile strength) of 1590 MPa and a total elongation above 11%. The final Q&P microstructure, in both one- and two-step partitioning conditions, consisted of retained austenite (RA-γ), martensite and ferrite islands in a bainitic matrix. Furthermore, the boron treated steel on quenching produced a greater amount of RA-γ, which accounted for its better room temperature ductility and produced a martensitic matrix rather than a bainitic one, giving it greater strength. The addition of boron improved the corrosion resistance of this type of third generation AHSS steel.

Finite Element Analysis of Large Plastic Deformation Process of Pure Molybdenum Plate during Hot Rolling

The rare molybdenum resources are being increasingly used in heavy industries. In this study, the common unidirectional and cross hot rolling operations, for pure molybdenum plates, were numerically simulated by using MSC. Marc software. An elastic–plastic finite element model was employed, together with the updated Lagrange method, to predict stress and strain fields in the workpiece. The results showed that there was a typical three-dimensional additional compressive stress (σy> σz > σx) in the deformation zone, while strain could be divided into uniaxial compressive strain and biaxial tensile strain (εy > εx > εz). Tensile stress σx increased with the accumulation of reduction and the decrease in friction coefficient at the edge of the width spread. More importantly, the interlaced deformation caused by cross-commutations, which were helpful in repairing the severe anisotropy created by unidirectional hot rolling. The evolution of the temperature field of pure molybdenum plate was investigated. The surface quenching depth of the pure molybdenum plate was about 1/6 H under different initial temperatures and reductions. In addition, the fundamental reason for the nonuniform distribution of stress and strain fields was the joint influence of rolling stress, contact friction, and external resistance. By comparing the theoretical simulation value of the model with the experimental verification data, we found that the model was aligning well with the actual engineering.

Methodology to evaluate the impact of autonomy range for a battery train: application to the French railway network

Rail transport is the most virtuous mode of transportation but there are still 2500 rolling stocks that run on diesel. To contribute to France's objective of being carbon neutral by 2050, SNCF, the French national operator, has launched the AGC BEMU project to retrofit 5 dual-mode diesel-catenary trains into dual-mode catenary-battery trains, which will run on specific lines from 2024. In order to increase the relevance of battery-powered trains and promote their spreading, an economic optimum must be found between rolling stock, infrastructure, and operation. This paper presents the results of the analysis, using an innovative approach, of the relevance of battery-powered trains in France as a function of autonomy range. It highlights the existing territorial differences in France, which mainly depend on the electrification of the network and the railway operation.

Fractional order adaptive MRAC controller design for high-accuracy position control of an industrial robot arm

Most of conventional feedback controllers become inefficient in hard industrial environments like in steel industry, because of uncertainties in the plant model, or process dynamics variation due to nonlinear actuators, and changes in the character of the disturbances. This paper proposes an adaptive control design based on fractional order model reference adaptive control (FOMRAC) strategy in order to deal with an uncertain horizontal positioning control of an unloading machine in a rotary hearth furnace for hot rolling operation. The proposed FOMRAC scheme uses the MIT rule as an adaptive mechanism with two main modifications comparatively to the conventional MRAC: the reference model is an adequate fractional order system and the parameter adjustment rule contains a fractional order integrator. Stability analysis of the proposed control scheme is performed using the Lyapunov stability theorem. Numerical simulations are presented to show the effectiveness of the proposed fractional adaptive schemes applied to an industrial robot arm loading round steel blocks from inside a rotary hearth furnace. After comparison with the conventional MRAC, it is shown that the performances of FOMRAC are superior to classical control schemes.

Features of design cold pilger mill tools for zirconium alloy tubes production

Method of design rolling tools’ grooves for manufacturing of zirconium alloy tubes is considered. The proposed methodology allows to clarify range different parameters calculated in design rolling tools. The described method will ensure compliance with current technical specifications and reduce the likelihood of defects during cold pilgering. The calculation algorithm for determination design parameters is implemented on the example of the intermediate rolling operation ∅65,0×11,9 mm ∅ → ∅32,2×5,3 mm.

Method of cutting metal ingot with changing direction of deformation

The paper considers the priority problem of cutting an ingot with a changing direction of rolling which can be presented as a priority problem of packaging with incompatible categories and dynamically changing bin sizes. This problem is a NP-complete optimization problem which is often found in the production of metalwork. Priorities reflect the “importance” of manufacturing elements for production and incompatible categories show that elements of different thicknesses cannot be made from the same bin. In addition, we use guillotine restrictions to take into account the specifics of production. The problem of cutting the ingot is characterized by the fact that the bin sizes are not known in advance. Thus, the task is to find the optimal bin sizes, the sequence of actions and the placement of elements in these bins. We propose a sequential tree metaheuristic to solve this problem. It is a deterministic method. This method is based on sequential metaheuristic which was proposed by the authors earlier. The proposed method also has the ideas of dividing a set of elements into groups and subgroups by thickness and priorities, as well as their sequential packing. However, it differs from previous one in that it uses a tree to represent options for rolling operations. The best subtree from the point of view of any criterion, formed as a path from the root to one of the nodes, will be the solution. The ability to find several better solutions with the same value of the criterion is another advantage of the proposed method. Such a situation may arise, for example, for a square ingot. In this case, two solutions are possible with accuracy up to 90 degrees rotation of the workpieces. The priority heuristic is used as a heuristic to solve the packaging subproblem. The results of computational experiments are based on test cases which were compiled specially. Test instances differ in the number and characteristics of elements, categories, priorities. The results show that the metaheuristic proposed by the authors solves the problem effectively.

Investigation the structure and properties of deformed semi-finished products produced from chips of Al–Mg alloys system alloyed with scandium

The article presents the results of studies that make it possible to solve the problem of processing secondary waste from expensive aluminum alloys without irretrievable loss of metal. For this purpose, tasks were set and solved for the development of technological schemes for obtaining longish deformed semi-finished products from chip waste of Al–Mg alloys 01570 and 1580 alloyed with scandium using methods of powder metallurgy and metal forming. For their experimental verification, the operations of chip briquetting, combined rolling-extrusion (continuous extrusion), sectional rolling, hot extrusion and drawing in combination with heat treatment were applied. According to these schemes, semi-finished products in the form of rods and wires were obtained. Structure and mechanical properties were investigated. It has been revealed that when hot-extruded rods are obtained from chip briquettes of alloy 01570 on a vertical hydraulic press, even with significant degrees of deformation during extrusion, the margin of plastic properties is small and makes it possible to obtain a wire with a diameter of only 4.2 mm after drawing. The processing of briquettes from 1580 alloy chips using the combined rolling-extrusion method makes it possible to obtain after cold deformation a wire with a diameter of up to 3 mm. At the same time, the influence of the annealing process on the structure and properties of deformed semi-finished products from the investigated alloys was studied. It is shown that due to the low plasticity of the investigated material cold working of the rods must be carried out with small degrees of deformation, alternating it with intermediate annealing according to the proposed regime. An analysis of the physical and mechanical properties of the wire obtained using combined processing showed that its strength and plastic properties are comparable to the properties of the wire obtained from a cast billet, and the structure is characterized by a high degree of elaboration and compactness. Thus, as a result of the research, technological schemes have been developed and processing parameters have been determined for the production of rods and wire from graded chip waste of alloys 01570 and 1580 using compaction, discrete and continuous extrusion, as well as cold drawing.

Enhanced mechanical behaviour and grain characteristics of aluminium matrix composites by cold rolling and reinforcement addition (Rice husk ash and Coal fly ash)

Aluminium matrix composites significantly benefit the manufacturing sector due to the high strength-to-weight ratio. However, grain refinement was one of the major problems faced by the research community and also as-cast AA6063 contained eutectic silicon with sharp, long elongated laths that consequently reduces strength and limit their applications. So, the prime novelty of this research work is to refine the grains by performing the cold rolling operation in AA6063 and incorporating rice husk ash and coal fly ash in the AA6063 matrix to break those eutectic laths which attributes to the enhancement of the mechanical properties. Rice husk ash and coal fly ash were chosen because they are economical, possess low density and are available in enormous quantities as solid waste by-products. They contain a substantial concentration of SiO2 and serve as a viable reinforcement for improving the mechanical properties of aluminium composites. In this research, the grain characteristics along with the mechanical properties of aluminium composites reinforced with rice husk ash and coal fly ash, produced by the stir casting technique were investigated. The reinforcements were added in varying concentrations (1.5 and 3.0 wt.%). Six specimens were fabricated of which five were cold rolled. Image J and Origin software was used in evaluating the average grain size of the fabricated alloys and their composites. The results were discussed with the help of grain size distribution and profile plots. Structural and composition studies were done using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction spectroscopy. Hardness and tensile tests were performed on the fabricated composites. The outcome of this research reveals, AA6063-3 wt.% rice husk ash composite has improved hardness (84HV) and tensile strength (156 MPa). Moreover, the average grain size of 10.52 µm was the main reason for the attainment of enhanced mechanical properties.

Modelling and optimising hybrid process of wire arc additive manufacturing and high-pressure rolling

Hybrid process of wire arc additive manufacturing (WAAM) and high-pressure rolling can build large-scale components with low detrimental residual stress (RS) and distortion. We developed an efficient coupled process model for a steel wall to simulate the interaction between WAAM deposition and rolling. The predicted RS distributions and wall dimensions agree well with experimental results. Cyclic variation of longitudinal tensile RS occurs during WAAM deposition and inter-layer rolling in clamped condition. The influence depth of deposition and rolling is characterised by the number of the underlying layers that are plastically deformed after each process cycle. For the inter-layer rolling with a flat roller, the rolling has smaller influence depth than the deposition; consequently, the rolling does not eliminate but rather contains the regeneration of WAAM tensile RS after thermal cycles. Rolling with a slotted roller introduces more tensile plastic strain and thereby more effectively reduces WAAM tensile RS and unclamping distortion. Compared to the inter-layer rolling, stacked-four-layer rolling has larger influence depth and hence achieves similar RS mitigation efficacy with fewer rolling operations, while post-build rolling has lower efficacy due to insufficient penetration. Therefore, stacked-layers rolling with slotted roller is recommended for an optimal hybrid process of WAAM and rolling.

Influence of cast iron vacuuming on the level of mechanical characteristics of the material of the working layer of double-layer chromium-nickel rolls

The object of research is chromium-nickel cast iron of the working layer of two-layer sheet-rolling rolls of the LPKhNd design. At present, chromium-nickel cast iron is widely used for the manufacture of rolls for sheet and section rolling mills. One of the ways to improve the operational properties of products made of chromium-nickel cast iron is the refining of molten metal by vacuum. The existing problem is that information on the effect of vacuuming on the performance of chromium-nickel iron is very limited. Rolls with the most characteristic concentration of alloying elements for LPKhNd performance were selected for the study. When evaluating the properties of vacuumed cast iron and cast iron by traditional technology, the level of strength, hardness, as well as special properties were determined, the study of which is caused by the peculiarities of the operation of rolling rolls (thermal wear resistance and crack resistance). It has been established that there is no significant difference in the structures of rolls made of vacuumed and non-vacuumed cast iron. The structure of the rolls consists of martensite, bainite and carbides. With an increase in the content of graphite-forming elements (C, Si, Ni), graphite inclusions appear in the structure, and with their decrease, individual troostite colonies appear. The physical and mechanical properties of vacuumed and non-vacuumed cast iron are on the same level. The crack resistance of the chilled zone of vacuum cast iron is 12.35 % higher than that of cast iron of the traditional production method, and the transition zone is 11.96 %. The thermal endurance of the chilled zone of the roll material increased by 14.95 % as a result of vacuuming of the molten metal, and the transition zone – by 14.56 %. An increase in crack resistance and heat resistance can help reduce the chipping of the working layer of chromium-nickel rolls of sheet mills during operation and increase their resource indicators. The obtained results of research indicate a positive effect of vacuuming on individual indicators (crack resistance and heat resistance) of the working layer of the forming tools of sheet rolling mills.

Analysis of structural transformations occurring during thermal hardening of building reinforcing steel produced at Baku Steel Company LLC

For the production of building reinforcing steel, special charge components were used, consisting of steel waste, cast iron shavings and about 20 % of NVG pellets. Steel was smelted in a 60-ton electric arc furnace. The pouring of liquid steel was carried out on a continuous casting machine. Heat treatment was carried out immediately after the rolling operation to improve the physical and mechanical properties of the construction reinforcing steels melted in the electric arc furnace from the charge material using metal waste. It is recommended that these steels be made of low-carbon (C≤0.25 %) and low-alloy steels in order to have a sufficiently high technology and good weldability. However, in order to meet the requirements of construction standards, these steels must have high structural integrity and physical and mechanical properties. It was found that these requirements can be solved only by heat treatment immediately after the rolling operation of the armature. In this case, the effect can be obtained by reinforcing heat treatment of the fittings by hardening due to the rolling temperature. Therefore, in order to further improve the properties during thermomechanical treatment (TMT), the hardening was carried out directly (immediately) after the deformation in the roll. Immediately after the spread, the physical and mechanical properties, as well as the fluidity and strength properties of the construction low-carbon reinforcement steels met the requirements of the standard by conducting HTMT. Increased strength and technological properties of reinforcing steel are achieved after hardening by dispersion hardening at high-temperature tempering, which is carried out at a temperature of more than 580 °C

Dynamic investigation and alleviative measures for the skidding phenomenon of lubricated rolling bearing under light load

The skidding phenomenon occurs during the operation of rolling bearing under the light load owing to the design error, which will intensify the surface damage and lead to noise and abnormal vibration. In this study, a skidding dynamics model of lubricated rolling bearing is established considering the interactions between the roller and races, as well as the cage. The effect of lubricant on the dynamic characteristics of the rolling bearing is characterized as the lubricating oil stiffness, central film thickness, time-varying friction coefficient between the roller and race, passing flow resistances of rollers, and resistance torques. In addition, the nonlinear contact and structure deformations of rollers are formulated. For mitigating the skidding phenomenon of the roller under light load, the effect of roller number, inside radius of the hollow roller, density and viscosity of the lubricant, interference fit, and radial load are analyzed. The results indicate that the skidding phenomenon of the roller is induced by the lesser tangential roller-race friction forces and larger passing flow resistances of rollers. It is helpful to intensify the interactions at the roller-race interface or/and decrease the running resistance by reducing the roller number, decreasing the lubricant density, or choosing the correct viscosity of the lubricant. Besides, the effect of interference fit and increasing radial load is significant on the premise of not changing the design parameters of the rolling bearing.

A Cryptographic Test of Randomness, Entropy, and Brute Force Attack on the Modified Playfair Algorithm with the Novel Dynamic Matrix

One critical concern in designing a cryptographic algorithm is its randomness. The randomness test examines the quality of random numbers generated by cryptographic algorithms. In this paper, the National Institute of Standards and Technology (NIST) Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications was instrumental in assessing the security of the modified Playfair algorithm with the novel Multidimensional Element-in-Grid Sequencer (MEGS). Moreover, this study determines the level of security of the MEGS-based Playfair algorithm against brute force attacks. Simulation results revealed that the modified cryptographic algorithm could execute the encryption process with randomly generated ciphertext despite having repetitive letters in the plaintext, as evident in the frequency (monobit) test, frequency within a block test, and runs test with p-values > 0.01. Further, the MEGS-based Playfair algorithm was highly resistant against attacks based on the results of the entropy test and the brute force attack analysis. Since the character keyspace of the modified algorithm is 256, attempts to break the ciphertext would cost a large amount of financial and computational resources. The use of a 16x16 dynamic matrix with matrix rotation, matrix shifting, matrix rolling, and crossover operations enhanced the performance of the Playfair algorithm, improving its resilience to attacks. Keywords—Brute force attack, MEGS-based Playfair algorithm, modified Playfair algorithm, NIST statistical test, randomness test

Unplanned Disruption Analysis and Impact Modeling in Urban Railway Systems

Unplanned disruptions bring challenges to urban railway system operations because of their impacts on safety, operation efficiency, and service quality. Identifying the contributing factors of operation delays and affected areas under unplanned disruptions is critical for agencies to make effective and informed management decisions. Despite its importance, few studies have been reported on unplanned disruption analysis in urban railway systems or they have been limited in their analysis and modeling because of the lack of disruption data. This paper collects a complete set of unplanned disruption data for 7 years in Hong Kong and explores important factors affecting operation delays and affected areas. Quantile regression (QR) models are developed to explore the causes of operation delays under unplanned disruptions. The significant factors include the time of day, weather condition, signal control system (moving/fixed block), line types (urban/suburban), line operation direction, disruption location (underground/ground/elevated), the number of affected stations, and disruption types (e.g., tracing, locomotive and rolling stock, passengers, and operation). A binary logit model is developed to explore the variables contributing to the affected areas (single or multiple stations). The results show that the affected area is significantly influenced by the signal control system, line types, line operation direction, disruption location, terminal/departure station involved or not, transfer station involved or not, and disruption types. The findings provide useful insights into unplanned disruptions and support the development of engineering and policy countermeasures to prevent and mitigate unplanned disruption effects on operations and services.

Production of transverse magnetic field annealed brass band and how the production process influences the mechanical properties, as well as their correlation and compliance

This paper examines the effect of the thickness h, the deformation reached during the last cold rolling operation ε and the final normalized annealing mode v on the mechanical properties of brass band. The paper looks at the correlation between the ultimate strength σв, elongation and hardness HV in terms of their meeting the specification. The production of L68 brass band involved semi-continuous casting, hot rolling to the thickness of 6 mm and cold rolling to h = ~0.56–0.96 mm with intermediate annealing at H = 1.5–2.7 mm ensuring the deformation ε within 62 to 72%. The intermediate and final continuous annealing lines are equipped with three-phase TFIH (Transverse Flux Induction Heating) units. An intermediate annealing mode has been established that ensures the grain size of 40–80 μm. The strip travel speed was varied as follows during final annealing: ν = 30–46 m/min. The authors determined the stochastic dependences of the properties on ν , h and ε, as well as the annealing modes that are necessary to achieve each property. Actual correlations HV(σв), δ(σв) within the specified ranges were considered versus the properties of the band produced by deformation. It was established that the cold rolling process, together with the heat treatment mode, has an effect on the properties of annealed band and, vice versa, on the heat treatment mode that is necessary to achieve the required properties. With hardness being the same, the induction heat annealed brass band has a higher ultimate strength в than the band produced by normalized final deformation. As a result, the linear relationship σв = f(HV) of the rolled band produced by normalized final annealing is shifted in relation to the optimum position of such relationship within the specified limits adopted in the period when the rolled band was exclusively produced by final deformation. Consequently, the final annealing mode ranges that are necessary for achieving certain properties within the specified ranges, do not match, thus making the task of having the resulting properties hit the above ranges more challenging. Thus, it is proposed to use online control and annealing control to eliminate rejects, and to use the annealing mode-required property relationships obtained from the given data for setting up the initial process mode.

EVALUATION OF DEFORMABILITY OF MATERIAL OF PREPARATIONS IN DIRECT AND REVERSE EXTRACTION BY ROLLING STAMPING METHOD

The article presents the results of development and research of various technological schemes of the process of stamping by rolling cylindrical and conical rolls to obtain complex profile workpieces. It is shown that the achievement of significant dimensions of the various elements of the workpiece is possible by providing a directed flow of metal by changing the relative position of the roll and the workpiece. The most effective rolling operations are landing, settling, unloading, reverse and direct extrusion. The paper focuses on the analysis of operations of reverse and direct extrusion to obtain complex profile blanks with developed, including thin-walled elements. Since the technological capabilities depend on the deformability of the material, the analysis of the stress-strain state of the workpieces was performed using the method of grids, hardness measurement and microstructural analysis. The main result of the analysis was the construction of ways to deform the particles of the workpiece material in the coordinates "deformation intensity - stress index". Zones of blanks that are deformed in the conditions of "rigid" stress state are established, therefore for these zones the deformability of metals was assessed using the criteria of phenomenological theory. In addition, the assessment of deformability was also performed for areas with the maximum degree of deformation of the material. The manufacture of thin-walled elements of the workpiece, using the operation of reverse extrusion, is accompanied by the appearance of significant contact stresses. To prevent the roll from being pushed out of the workpiece and forming elements with a constant thickness, support rollers should be provided. In the case of direct extrusion, the increase in contact stresses requires the application of additional measures to increase the strength of the tool.

Experimental Investigation on Slip Conditions during Thread Rolling with Flat Dies

Rolling operations with flat dies allow the highly efficient production of cylindrical parts in large quantities. [1] Latest trends towards shorter lifecycle times and increasing product complexity [2] strengthen the need for an efficient design process of flat die rolling operations. Finite element modelling plays a major role in establishing an efficient design process. Precise modelling of the friction conditions during rolling operations with flat dies is still posing a challenge today. [3] The present work aims to experimentally identifying the limits of rolling of an axisymmetric part, using flat dies. By gradually increasing the stroke rate, the process limits caused by excessive slippage are determined for six different tribological systems. The workpiece rotation and tool movement is measured optically by using a digital camera system. Large differences in slippage are observed, depending on the tribological system. While systems with polymer based lubricants show excessive slippage at low stroke rates, systems using oil or no lubricant bear higher stroke rates before process limits are reached. Furthermore the optical measurements reveal that slip may also occur without complete process failure leading to the assumption that the process limit of excessive slippage in rolling operations is rather fluent than binary. Based on this experimental data, future investigations will focus on methods to predict these process limits through FEM using advanced friction modelling and tribometer tests.

Development of three-dimensional simulation model of rolling operation in railway wheel manufacturing process

Development of three-dimensional simulation model of rolling operation in railway wheel manufacturing process

Influence of rolling on the properties of protective coatings obtained by the low-temperature gas-dynamic method

The method of obtaining anticorrosive protective coatings by a low-temperature gas-dynamic method from a powder material is a promising area of research for use in various areas of the national economy, including for restoring equipment that has used up its service life. The paper describes the deformation of a material particle upon impact with a substrate during the interaction of a heterogeneous flow with the substrate during the formation of a coating. Upon impact, the particle penetrates into the substrate, the process of deformation of the particle is accompanied by its compression and spreading over the surface. Then the defining mechanical process is the process of spreading, as a result, the formation of pores and discontinuities in the coating. In this paper, we study stainless steel coatings obtained on a sheet of cold-rolled steel 20 by a lowtemperature gas-dynamic method. The appearance of several types of corrosion occurring in the formed coating due to the presence of pores due to the use of powder materials is shown; the influence of the choice of powder material for coating on the protective properties of the resulting coating, a theoretical and practical study of the use of an additional cold pressing operation after coating formation to improve its protective and anticorrosive properties is presented, and own data on the effect of the cold pressing operation after coating formation on the porosity and corrosion properties of the coating obtained from stainless steel powder are presented. Thus, the paper substantiates a method for correcting the properties of protective coatings obtained by the low-temperature gas-dynamic method, using an additional cold rolling operation.