Rolling Mode Research Articles

Investigation of cold rolling modes of 1580 alloy by the method of computer simulation

A computer model was developed and a study of the cold rolling modes of 1580 alloy sheets was carried out. The model provided for the achievement of the maximum total degree of reduction in cold rolling of 60% in the minimum number of passes, the rolling force should not exceed 90% of the maximum allowable for the rolling mill, and the Cockcroft-Latham criterion was not reach value 1, so that cracks do not occur along the edges of the rolled products. The simulation results were tested on a billet cut from a large-sized ingot cast at an industrial enterprise by the method of semi-continuous casting. Hot rolling was carried out on a two-roll mill with a roll diameter of 330 mm and a barrel length of 520 mm. For cold rolling a two-roll mill with a roll diameter of 200 mm and a barrel length of 400 mm was used. Based on the simulation results, cold rolling was carried out, as a result of which a 2-mm-thick strip without cracks along the edges was obtained from a hot-rolled billet 5-mm-thick in 8 passes. At the same time in all passes, the rolling force values did not exceed 90% of the allowable for the rolling mill, and the Cockcroft-Latham criterion was less than 1. Thus, it is shown that computer modeling allows to optimize the rolling route of thin sheets of alloy 1580 and to carry out cold rolling with a total reduction rate of 60% for a minimum number of passes to obtain high-quality sheet semi-finished products.

Melt Electrospinning Writing of Magnetic Microrobots.

The magnetic microrobots actuated by an external magnetic field can access distant, enclosed, and small spaces under fuel‐free conditions, which is apromising technology for manipulation and delivery under microenvironment; however, the complicated fabrication method limits their applications. Herein, three techniques including melt electrospinning writing (MEW), micromolding, and skiving process are combined to successfully mass‐produce tadpole‐like magnetic polycaprolactone/Fe3O4 (PCL/Fe3O4) microrobot. Importantly, the tadpole‐like microrobots under an external magnetic field can achieve two locomotions: rolling mode and propulsion mode. The rolling motion can approach the working destination quickly with a speed of ≈2 mm s−1. The propulsion motion (0−340 µm s−1) can handle a microcargo. Such a simple and cost‐effective production method shows a great potential for scale‐up fabrication of advanced shape‐design, mass‐production, and multifunctionality microrobot.

Formation of quality indicators for flat surfaces of machine parts when running them with a reinforcing roller

The forming of parameters of quality of parts flat surfaces during their rolling by strengthening roller is studied and it is shown that for each value of rolling force there are extremely achievable indicators of quality of the surface layer. It has been established that the spread of quality indicators values on the strengthened surface of the part is stabilized and becomes minimal after three passes of the roller. The functional dependence of the roughness parameter value of the part flat surface on it’s previous value and rolling mode is obtained, which allows solving a number of technological problem.

Comparative Study of Superelastic Ti–Zr–Nb and Commercial VT6 Alloy Billets by QForm Simulation

A comparative simulation of hot radial shear rolling (RSR) of billets made of a superelastic Ti–Zr–Nb and a commercial VT6 alloy was performed using the QForm finite element modeling program. Rolling in 48 modes with a variable feed angle and elongation ratio at 4 levels and initial rolling temperature at 3 levels was investigated for each alloy. The Ti–Zr–Nb alloy rheology during hot deformation was determined experimentally by hot upset forging and imported into the QForm program. The presence of maxima on the flow curves at the initial stage of deformation, which are absent in the VT6 alloy, is revealed. Simulation results are presented in the form of fields of the stiffness coefficient, strain rate intensity, cumulative strain degree in the maximum reduction section depending on the rolling mode. General regularities of the Ti–Zr–Nb and VT6 behavior in RSR are similar. The gradient of the fields studied decreases, and the roll pressure and torque increase with an increase in the feed angle and elongation ratio. The initial rolling temperature does not significantly affect the deformation pattern, but it significantly affects the roll pressure and torque. At the same time, the experimental alloy demonstrated the greater tendency to localize deforming forces in the near-contact zone and to increase the gradient of stress-strain state parameters over the billet section. The study of the tightening shape and depth of rolled billet ends showed that the Ti–Zr–Nb alloy has a 3.5–9.6% greater tightening depth. It is shown that experimental alloy rolling requires 1.6–2.4 times higher roll pressure and torque as compared to the commercial alloy.

КОМП'ЮТЕРНА СИСТЕМА МОНІТОРИНГУ ЗАЛИШКОВОГО РЕСУРСУ ОБЛАДНАННЯ ШИРОКОШТАБОВОГО СТАНА

The purpose of the work is to develop a computer system for calculating and optimizing the hot rolling modes of the headquarters, forecasting and increasing the residual life of rolling mill equipment. It is shown that in recent years there has been a steady increase in the production of hot-rolled staffs of high-strength steels and especially thin staffs. Mastering the production of such strips leads to an increase in the load on the equipment of rolling mills. The result is increased wear of equipment elements and their premature failure. The Institute of Ferrous Metallurgy of the National Academy of Sciences of Ukraine has developed a computer system for online monitoring of the residual resource of the wide strip hot rolling mill. The main functions of the computer system are: adaptation of models of power parameters of the rolling process; verification of models according to the actual assortment; calculations of power parameters according to adapted models; optimization of rolling modes to ensure the allowable values of power parameters of rolling and the target temperature of completion of rolling, the maximum productivity of the mill; calculations of the number of load cycles of elements in the equipment of the mill; estimation of the residual resource of the equipment taking into account its initial values. The following schematization methods were chosen for the design of the residual resource forecasting system: for dynamic loads - the method of allocation of complete cycles, for static loads - the method of extremes. All objects of the drive line which are diagnosed are divided into three classes: details which can be both separately, and as a part of knots or units; units that can be both separately and as part of units; units consisting of parts and assemblies. The calculation of the residual resource is performed only for details. The residual life of the node or unit is determined by the part that is part of it and has the smallest residual life. The developed computer system was tested on one of the existing hot strip mills. To do this, the transfer of source data contained in industrial databases to the developed computer system for monitoring the residual resource was established. The test showed a fairly high reliability of forecasting the power parameters of the rolling headquarters and the assessment of the residual life of the equipment and the drive line of the rolls of the working stands.

Effect of Rolling Mode on Grain Growth of Electrodeposited Nanocrystalline Nickel

The electrodeposited nanocrystalline nickel samples were deformed by conventional unidirectional rolling, cross rolling and pack rolling, respectively. The effect of rolling mode on grain growth behavior was investigated by x-ray line profile analysis, transmission electron microscopy observation and microhardness measurement. Quantitative analysis indicated that rolling deformation induced grain growth is associated with grain rotation as well as dislocation activity, no matter what the rolling mode we use. Based on grain rotation induced grain growth, cross rolling induced grain growth is the most obvious, followed by conventional unidirectional rolling and pack rolling.

Modeling the parameters of free and driving wheel rolling modes taking into account the asymmetry of the normal reaction diagram

A method for determining the power and kinematic parameters of a tire and a wheel for free and driving modes of rolling is given. The displacement of the center of normal reactions of the road support surface was taken into account. The amount of displacement is presented as a linear function of the longitudinal force coefficient. The analytical description of the dependence reflects the relationship between the longitudinal force coefficient and the asymmetry coefficient of the diagram of normal reactions of the bearing surface and determines the displacement of the center of normal reactions towards the front edge of the contact area of the tire. The calculated asymmetry of the epure of relative normal reactions can be obtained by choosing the appropriate value of the asymmetry coefficient in the range from 1 to 0. Based on a numerical example, a graphical-analytical display of the force and kinematic parameters of rolling of a wheel with a 15.5-R38 model F-2A tractor tire is presented when using the epure of relative normal reactions described by a parabolic dependence of the fourth degree. The longitudinal force coefficient is determined taking into account the formation of the resulting longitudinal reaction by two components - in the slip section and in the rest section of the tire contact pad elements. It was found that the maximum value of the longitudinal force coefficient for an asymmetric epure of relative normal reactions is observed with a larger value of the wheel slip coefficient compared to a symmetric epure, but remains practically unchanged for both compared diagrams of relative normal reactions. The presented method for determining the power and kinematic parameters, taking into account the asymmetry of the epure of normal reactions of the supporting surface, can find practical application in the selection and substantiation of rational modes of operation of wheel propellers of tractor transport and technological units in various road conditions.

Управління швидкісними режимами прокатки на товстолистових станах

Control of speed modes on heavy-plate mills is one of the factors that determine the efficiency of the rolling process. The choice of speed controls influences the mill productivity, geometric dimensions of the rolled product (longitudinal thickness variations) and compliance with the set temperature mode which determine the mechanical properties of the rolled product, etc. The article considers the limitations in the choice of speed controls which can be divided into two groups: limitations of the capabilities of rolling engines and technological limitations. The first group is determined by the allowable engine under the conditions of reliable current switching on the collector and the maximum allowable engine speed. Technological limitations of speed controls are considered in the paper as well. The speed of grasp is limited to the maximum un-der the condition of metal grasp without skew, blows and dynamic torque overloads in spindles and maintenance of constant grasp without slipping, as well as the possibility of prevention of emergencies. Steady (maximum) rolling speed can be limited to the maximum by the conditions of rolling stability and prevention of sticking of metal to the rolls. The rate of metal release from the rolls is usually chosen in the way so that the pause stipulated by the braking of the sheet on the roller conveyor and its subsequent return to the rolling mill would not exceed the operating time of the pressure mechanism. In some cases, the release rate can be determined by other technological operations. The maximum acceleration of the main drive of the horizontal mill is limited by the conditions of slipping of the working roll towards the sup-port roll. The paper also considers rational speed graphs of rolling on heavy-plate mills. They are the most common type of high-speed rolling graphs on heavy-plate mills. The listed above solutions for the control of high-speed rolling modes can be used in the development of APCS of heavy-plate mills rolling.

Determining the deformed state in the process of rolling conical shells with a flange

Obtaining conical shells by forging is an important and relevant task in energy and heavy engineering. Existing processes of their manufacture come down to simplifying the configuration of such billets. The result is the increased material’s consumption while the internal fiber is cut during machining, which also leads to a decrease in mechanical properties. A new forging technique necessitated a study into the shape change of the billet and the distribution of deformations in the process of rolling. A finite-element method was used to investigate the process of rolling out the step hollow billets. Based on the study results, the forging’s taper was established, obtained during the forging process. A research procedure involving the finite-element method was devised to study the operation of conical shells’ rolling, which made it possible to determine a change in the shape and size of a hollow forging when rolled out by a step tool. A parameter has been proposed to quantify the formation of taper in the process of rolling a billet with a flange. Based on the study results, a step-wise distribution of the intensity of logarithmic deformities in the body of a forging was established when conical shells were rolled out. It was found that the step deformation leads to an increase in the uneven distribution of deformations on the part of the protrusion and ledge. Maximum deformations of 1.0...1.2 occur at the inner and outer surfaces of the step billet’s protrusion. Dependences of the shape change in a step billet for the investigated ratios of sizes and rolling modes have been established. It was found that the maximum taper is obtained at a deformation degree of 15 %. It was determined that the degree of compression in the ledge and protrusion is leveled after 3 deformation runs of the step billet

Metal structure prediction in cross-wedge rolling processes

A method of computer prediction of the size of metal grains, their disorientation, grain boundaries and dislocation density, depending on the modes of cross-wedge rolling, is considered. The regularities of the formation of the parameters of the metal structure depending on the stress state are revealed by methods of computer simulation. The stress state is described by two parameters: the average stress and the parameter of the third invariant of the stress deviator. The effect of the stress state in the deformation zone on the metal structure parameters was determined for the first time. The new method allows improvement of the quality of products by computer optimization of rolling modes. The results of determining the metal structure and parameters of the stress-strain state in the deformation zone during hot rolling of the water pump shaft of steel 45 are presented. The verification and analysis of the data of virtual experiments on the formation of the structure of structural steels in the processes of cross-wedge rolling are carried out. To analyze the output data of the simulation, the parameters for predicting the calculation of grain boundaries and grain size were used. The created computer model for predicting the characteristics of metal structures, depending on the modes of plastic deformation, provides, at minimal cost and without carrying out field experiments, finding the optimal thermodynamic and stress-strain modes of plastic flow of metal, which guarantee the highest operational properties of the products obtained.

Modeling and experimental investigation of the dynamics of a spherical Transforming Roving Rolling Explorer (TRREx) prototype

This paper examines a biologically inspired, transforming mars rover concept known as the Transforming Roving Rolling Explorer (TRREx). The rover is designed to operate in two modes: the ‘roving’ and ‘rolling’ modes. The roving mode is similar to many traditional wheeled rover designs and is useful for exploring relatively flat terrains. The rolling mode is intended to enable the rover to travel down steep slopes, such as those found in ravines and crater walls. In the rolling mode, the vehicle folds itself into a sphere and propels itself by shifting its center of mass. It does this by opening and closing the eight panels which form the surface of the sphere. The evaluation of this rolling mode is the primary focus of this paper. To that end, a spherical prototype TRREx has been designed, constructed, and tested. In addition, a mathematical model of the vehicle’s rolling mode dynamics has been created. The performance of the physical prototype has been compared to simulation results and the qualitative agreement between the experimental and simulated results indicate that the mathematical model created for the vehicle’s rolling mode dynamics captures the essential behavior of the vehicle. The mathematical simulation was then used to explore the TRREx parameter design space in order to analyze the effect of changing various system parameters. A path tracking simulation is also included as a case study to highlight the ability of a TRREx vehicle to traverse a desired path.

MATHEMATICAL MODELING OF THE TEMPERATURE FIELD OF WARM ROLLING MILLS ROLLS THAT HAVE AN INTERNAL HEATING SOURCE

Recently, a fairly common method of expanding the range of finished steel products is to obtain metal products with given, sometimes unique properties due to the use of warm rolling modes in the temperature range before recrystallization. There are two approaches to implementation of warm rolling process. The first one involves non-invasive heating of the strip before the deformation zone. The second approach prefers additional heating of sheets or strips directly in the deformation zone due to the contact heat exchange with the working rolls preheated to certain temperatures. From the point of view of reconstruction of the existing equipment, convenience and speed of regulation of heating temperature, stability of work and, finally, efficiency and environmental friendliness, the most reasonable is to use internal heating of working rolls. The implementation of this approach is also effective in terms of minimizing oxidative processes. It should be noted that the rolls in such a scheme plays a significant role in the formation of the resulting temperature field of the strip, and, therefore, significantly affect the final properties of the products. The paper presents a mathematical mo-dele of the temperature field of the working rolls of warm rolling mills with an internal heating point. Numerical implementation of the model is carried out on the basis of superposition approach, which provides for the breakdown of the roll cross-section into ij-nodes in the period of time. The results showed significant heterogeneity of temperature distribution both in radius and outer surface, as well as the presence of maximum at the exit from the deformation zone and minimum in the section before it.

Comparative study of superelastic Ti–Zr–Nb and commercial VT6 alloy billets by QForm simulation

A comparative simulation of hot radial shear rolling (RSR) of billets made of a superelastic Ti–Zr–Nb and a commercial VT6 alloy was performed using the QForm finite element modeling program. Rolling in 48 modes with a variable feed angle and elongation ratio at 4 levels and initial rolling temperature at 3 levels was investigated for each alloy. The Ti–Zr–Nb alloy rheology during hot deformation was determined experimentally by hot upset forging and imported into the QForm program. The presence of maxima on the flow curves at the initial stage of deformation, which are absent in the VT6 alloy, is revealed. Simulation results are presented in the form of fields of the stiffness coefficient, strain rate intensity, cumulative strain degree in the maximum reduction section depending on the rolling mode. General regularities of the Ti–Zr–Nb and VT6 behavior in RSR are similar. The gradient of the fields studied decreases, and the roll pressure and torque increase with an increase in the feed angle and elongation ratio. The initial rolling temperature does not significantly affect the deformation pattern, but it significantly affects the roll pressure and torque. At the same time, the experimental alloy demonstrated the greater tendency to localize deforming forces in the near-contact zone and to increase the gradient of stress-strain state parameters over the billet section. The study of the tightening shape and depth of rolled billet ends showed that the Ti–Zr–Nb alloy has a 3.5–9.6 % greater tightening depth. It is shown that experimental alloy rolling requires 1.6–2.4 times higher roll pressure and torque as compared to the commercial alloy.

Decoupled rolling, sliding and sticking of a viscoplastic drop on a superhydrophobic surface

Abstract

Laser reprogramming magnetic anisotropy in soft composites for reconfigurable 3D shaping

Responsive soft materials capable of exhibiting various three-dimensional (3D) shapes under the same stimulus are desirable for promising applications including adaptive and reconfigurable soft robots. Here, we report a laser rewritable magnetic composite film, whose responsive shape-morphing behaviors induced by a magnetic field can be digitally and repeatedly reprogrammed by a facile method of direct laser writing. The composite film is made from an elastomer and magnetic particles encapsulated by a phase change polymer. Once the phase change polymer is temporarily melted by transient laser heating, the orientation of the magnetic particles can be re-aligned upon change of a programming magnetic field. By the digital laser writing on selective areas, magnetic anisotropies can be encoded in the composite film and then reprogrammed by repeating the same procedure, thus leading to multimodal 3D shaping under the same actuation magnetic field. Furthermore, we demonstrated their functional applications in assembling multistate 3D structures driven by the magnetic force-induced buckling, fabricating multistate electrical switches for electronics, and constructing reconfigurable magnetic soft robots with locomotion modes of peristalsis, crawling, and rolling.

A pendulum hybrid generator for water wave energy harvesting and hydrophone-based wireless sensing

The environmental monitoring system is of great significance in marine scientific research and exploration. However, battery-operated sensors in such a system limit its working time and make maintenance difficult. Harvesting water wave energy to power these sensors becomes a promising way to overcome challenges. Herein, a pendulum type hybrid generator to scavenge wave energy and power the hydrophone is presented. The proposed pendulum structure can harvest random water wave energy from arbitrary directions sensitively. The combination of a freely rolling mode triboelectric nanogenerator (TENG) and a magnetic sphere based electromagnetic generator (EMG) provides complementary advantages and harvests wave energy in a wide frequency range. The hybrid generator is demonstrated to drive 177 LEDs and power an electronic device. At a wave driving frequency of 1.4 Hz, the output power of the EMG and TENG is 6.7 mW and 8.01 µW, respectively. A capacitor can be charged to 26 V by the hybridized generator within 200 seconds at the frequency of 1.8 Hz. The new type of hydrophone-based system realizes sustainable wireless sensing of acoustic signals and positioning information and has important application value for long-term synchronous ocean monitoring.

Influence of rolling modes and the level of accumulated deformation on the mechanical and plastic properties of stainless austenitic steel AISI 304L

The paper presents the results of studies of rolling modes (direct, reverse, cross ones) at 500°C for samples of stainless steel AISI 304L and their influence on mechanical and plastic properties of the material. The stress-strain state was investigated using a numerical simulation program and the deformation parameters of processing were established. The mechanical properties were studied by microhardness measuring and tensile testing methods. The results of the experiment were analyzed and discussed, and conclusions were drawn. The regularities of the effect of strength parameters depending on the modes of processing and accumulated deformation during rolling have been established.

Influence of Rolling and Annealing Modes on Properties of Sheet Semifinished Products Made of Wrought Aluminum Alloy 1580

This article analyzes the processability and properties of sheet products made of a large grade 1580 alloy ingot with a lower scandium content in the range of its specifications. The processability of the ingot upon hot and cold rolling are estimated and the influence of percent reduction and annealing modes on properties of cold-rolled semifinished products from the alloy under consideration are analyzed. The experiments are performed with a commercial large ingot with a cross section of 500 × 2100 mm made of 1580 alloy with scandium content of 0.067 wt %. The experimental procedure is comprised of several steps of rolling and thermal treatment of sheet semifinished products at various stages of the developed mode of metal deformation and tests of mechanical properties of the respective samples using an LFM 400 kN universal testing machine. In order to perform experiments, a template with the sizes of 60 × 500 × 900 mm is cut out of the ingot and then billets for rolling are produced with sizes of 50 × 180 × 300 mm, which are exposed to homogenized two-stage annealing predeveloped for this alloy. As a consequence of the hot rolling of annealed billets at 450°C and the cumulative percent reduction of e∑ = 84–90%, sheet semifinished products are obtained with a thickness of 5–8 mm. Then, after their annealing at t = 320°C for 6 h, by means of cold rolling, thin semifinished sheets with a thickness from 2 to 6 mm are produced. Their mechanical properties in deformed and annealed states are analyzed, demonstrating that, upon cold rolling to e∑ = 38%, the strength properties of 1580 alloy increase to σ0.2 = 380 MPa; then, the growth intensity decelerates and, at e∑ = 60%, this variable is 400 MPa. The influence of annealing at t = 250–350°C on the mechanical properties of sheet semifinished products is also analyzed. It is detected that it decreases the strength properties and increases plasticity; the maximum offset yield stress corresponds to the annealing temperature of 250–275° at sufficiently high plasticity. It is established that, in terms of the strength properties, the sheet semifinished products made of 1580 alloy with lower scandium content are superior to those made of similar AW-5083 (United States) alloy without the addition of scandium by 10–15%, and the plasticity properties are 40–60% higher.

Study of the Manufacturability of Production and Properties of Welding Wire from Alloy 1580

The results of studies on the production of welding wires with a diameter of 2.5 and 3.3 mm from alloy 1580 are presented. To compare the manufacturability of the processing, various methods were used to obtain billets for drawing with a diameter of 8-12 mm: the traditional method of direct hot extruding (discrete); combined rolling-extruding method; and ingotless rolling-extruding method (continuous). The developed modes of bar rolling, drawing and annealing made it possible to obtain prototypes of wire in laboratory and industrial conditions. It was found that alloy 1580 is highly manufacturable both with the traditional method of pressure treatment (extruding) and with combined rolling-extruding methods. It was revealed that the application of all methods makes it possible to obtain billets with the level of mechanical properties necessary for further multi-operation processing. Based on the results of research obtained in laboratory conditions, rational drawing modes for industrial wire production have been developed. As a result of bay drawing, pilot batches of welding wire with a diameter of 3.26 and 2.47 mm from alloy 1580 were obtained, which was successfully used for welding sheet metal.

Influence of Pulling Modes and Temperature of Coiling Cold-Rolled Strips

The formative patterns of gaps between turns of cold-rolled strips in rolls and the ways these gaps affect the stress-and-strain state (SSS) of these rolls are disclosed. The effects of surface roughness, temperature, physical mechanical properties, strain degree, and hardening of cold-rolled steel on the interturn gaps in and the roll’s SSS are analyzed in detail. Possibilities of affecting the roll’s SSS by adjusting the cold-rolling temperature of fine strips and tinplate are exposed. Recommendations on choosing thermal-speed modes of strip rolling and coiling are presented.