Rolling Power Research Articles

Modeling and analysis of deformation characteristics for the two-layered metal clad plate produced by asymmetric rolling

Accurate prediction of deformation behavior of metal plate in deformation zone is the key point for rolling cladding process. At present, there is a lack of accurate analytical model about the deformation of metal plate in deformation zone. Therefore, an analytical model of the deformation characteristics in deformation zone for the two-layered metal clad plate produced by asymmetric rolling is established according to the practical requirements. Firstly, the stream function field model of the clad plate in the deformation zone is founded by using the stream function method. Based on the stream function field, the velocity field model of the clad plate in the deformation zone is established, and the precision of the velocity field model is demonstrated by the comparison between the finite element and the model analytical results. Based on upper bound theory, the layer thickness of the clad plate after rolling and the ratio of deformation power, friction power and shear power to the total power were calculated by minimizing the total rolling power. Finally, based on the thickness of clad plate after rolling and velocity field model, an analytical model is established to calculate the equivalent strain of the clad plate in the deformation zone. The accuracy of the analytical model is tested by the rolling cladding experiments and the finite element simulations. The results indicate that the analytical model has high precision and which makes it useful to predict the deformation behavior in the clad plate rolling process.

Analysis of Mechanical Parameters in Multi-Pass Asymmetrical Rolling of Strip by Slab Method.

Mechanical parameters, time consumption and energy consumption are important considerations in the application of a certain rolling process. This study aims to investigate characteristics of the roll force, roll torque, roll power, rolling time and total work in multi-pass asymmetrical rolling of strip. Mathematic models were built using the slab method to calculate parameters in the asymmetrical rolling process, and the characteristics of these parameters were analyzed on the basis of simulation results. Mechanical parameters are affected by the change of deformation region type. When the speed ratio is less than the critical speed ratio, the roll force, absolute values of roll torque and roll power are found to increase with the increase in the speed ratio. After the speed ratio reaches the critical speed ratio, the roll force, roll torque and lower roll power keep constant, but the upper roll power continues increasing. The upper roll torque and upper roll power required by asymmetrical rolling are much greater than that by symmetrical rolling, which indicates that stronger drive shafts and more powerful drive motors are required by asymmetrical rolling. Compared with symmetrical rolling, asymmetrical rolling requires less roll force to obtain the same thickness reduction, especially for thin and hard strips. Rolling time can be saved at the cost of more energy consumption by using asymmetrical rolling with the same roll force to attain the same final thickness. The results and conclusions of this study can provide a reference for mill design and application of asymmetrical rolling in strip manufacturing.

The effects of loadshedding on small and medium enterprises in the Collins Chabane local municipality

South Africa is at present experiencing electricity shortages resulting in loadshedding. Loadshedding is the action from an electricity supplier (Eskom) of rolling power cuts that intend to lessen the load on the power supply system when Eskom is not able to supply a high electricity demand. Loadshedding remains one of the country's most critical challenges and has affected day-to-day business activities leading to some small businesses closing their operations. In developing economies, small businesses play a significant role in the wellbeing of rural dwellers and are a major tool for local economic development. At present, there is limited evidence in the literature pointing out the small and medium-sized enterprises (SMEs) in Collins Chabane Local Municipality (CCLM) in terms of the effects of loadshedding but there is literature describing similar issues in other geographical areas. The exploration of the effects of loadshedding on SMEs in the Collins Chabane Local Municipality was crucial to empower small SMEs, cover scholarly gaps, contribute to policy development, and participate in academic discourse. The study uses a mixed-methods approach, adopting a triangulation research design. The sample consisted of 125 members of the target population, which included the SME owners/managers and officials from the Collins Chabane Local Municipality such as the Local Economic Development (LED) manager, Electricity manager, and a technician. The sample was selected using purposive, snowball non-probability sampling, and cluster probability sampling. A total of 100 respondents were selected for the quantitative study, while 25 participants were selected for the qualitative study. Therefore, 100 respondents completed questionnaires and 25 respondents participated in the face-to-face semi-structured interviews. The quantitative data were analysed using the statistical package for the social sciences (SPSS), while the qualitative data were analysed using the thematic method of analysis. According to the quantitative findings, loadshedding costs small and medium-sized businesses in the Collins Chabane Local Municipality an average of 61% of their total revenue. Additionally, 59% of these companies had to lay off their employees because they were unable to pay their wages. The Chi-square results demonstrate that loadshedding has been experienced uniformly by everyone, irrespective of their demographic and business demographic status. Therefore, demographics have no significant influence on the experience of loadshedding. The qualitative results reveal that the losses associated with the effects of loadshedding on SMEs’ production are untenable. There is an urgent need to alleviate the effects of loadshedding on SMEs. An alternative source of power is a requirement for small businesses in the Collins Chabane Local Municipality. It is for this reason that the South African government should grant small businesses a subsidy for the purchase of alternative sources of energy such as strong generators and solar panels to support them during periods of loadshedding. In addition, the South African government should encourage and capacitate small businesses in the Collins Chabane Local Municipality to participate in producing and supplying renewable energy by funding them, and further, foster cooperation among small businesses and companies that are successful in the production of renewable energy. This will assist in adding electricity generation capacity to the national grid and help eliminate electricity instability.

Reduced Slit Rolling Power in Rebar Steel Production

The rolling process of rebar steel production is one of the well established manufacturing processes; however, it should be subjected to revision and redesign for productivity enhancement and power reduction throughout the slit rolling process. In this work, slitting passes are extensively reviewed and modified for the attainment of better rolling stability and reduction in power consumption. The study has been applied for grade B400B-R Egyptian rebar steel, which is equivalent to steel grade ASTM A615M, Grade 40. Traditionally, the rolled strip in the rolling pass is edged before implementing a slitting pass using grooved rolls; this produces a single barreled strip. This single barrel form causes instability in the next slitting stand on the pressing by the slitting roll knife. Multiple industrial trials are attempted to achieve the deformation of the edging stand using a grooveless roll. As a result, a double barreled slab is produced. In parallel, finite element simulations of the edging pass are performed using grooved and grooveless rolls, and similar slab geometry with single and double barreled form are produced. In addition, further finite element simulations of the slitting stand are execute using idealized single barreled strips. The power calculated by the FE simulations of the single barreled strip is (245 kW), which is in acceptable agreement with the experimental observations in the industrial process (216 kW). This result validates the FE modeling parameters such as material model and boundary conditions. The FE modeling is extended to the slit rolling stand of a double barreled strip, which was previously produced by the grooveless edging rolls. It is found that the power consumption is (165 kW) 12% lower than the power consumed (185 kW) for slitting the single barreled strip.

Influence of emulsols type on energy-power consumption and surface contamination at DC01 steel cold rolling on the continuous four-stand mill

The article presents the results of experimental and industrial tests of physical and chemical parameters of the experimental emulsol "Quakerol". According to the physicochemical parameters the experimental emulsol "Quakerol" differs from the used emulsol "Universal-1TS" by higher lubricating properties. Operating modes of stand and coiler electric motors of tandem mill at rolling of melts from experimental emulsol "Quakerol" lubricated with emulsol "Quakerol" and serial emulsol "Universal-1ТС" lubricated with conservation oil "OK-2" at LPTs were analyzed. The results of analysis of loads at rolling of strips with 0.68×1000 mm cross-section from pre-rolled sheet with thickness of 3.0 mm showed that the values of average total loads on stand motors and coiler of four-stand mill 1680 were higher when using experimental emulsol "Quakerol". The comparative analysis of experimentally obtained data on influence of technological conditions of cold-rolled coils production at four-stand continuous tandem mill 1680 with using emulsols "Quakerol" and "Universal-1TS" on rolling power parameters, power consumption and contamination of DC01 flat carbon steel surface is presented. Multiple regression equations were obtained to describe power consumption during rolling using different emulsions, the values of cross-sectional area were taken as a varying factor. Specific power consumption and average total load on stands and coiler motors during rolling with the use of emulsion prepared from experimental emulsion "Quakerol" and emulsion prepared from standard emulsion "Universal-1TS" were estimated. The reasons of higher specific power consumption during LCL operation with the experimental emulsion were analyzed. A quantitative assessment of contamination of the surface of steel samples using the experimental emulsion "Quakerol", oil "OK-2" and standard emulsion "Universal-1TS" is given. The necessity of further tests to determine the optimal concentration of emulsion from "Quakerol" to ensure the reduction of energy costs per ton of cold rolled steel has been substantiated.
 The practical significance of the work lies in the development of methods for analysis of lubricants with regard to the prospects of using "Quakerol" emulsion instead of "Universal-1TS" emulsion in order to improve the quality and increase the productivity of the cold-rolling shop

Using feed-forward perceptron Artificial Neural Network (ANN) model to determine the rolling force, power and slip of the tandem cold rolling

In this paper, an Artificial Neural Network (ANN) is used to investigate the influence of rolling parameters such as thickness reduction, inter-strand tension, rolling speed and friction on the rolling force, rolling power, and slip of tandem cold rolling. For this reason, the rolling power was derived for 195 various experiments through a series of observation tests. The network is trained and tested using real data collected from a practical tandem rolling line. The best topology of the ANN is determined by Broyden–Fletcher–Goldfarb–Shanno (BFGS) training algorithm and error, and nine neurons in the hidden layer had the best performance. The average of the training, testing, and validating correlation coefficients data sets are mentioned 0.947, 0.924, and 0.943, respectively. The obtained results show MSE value 4.2 × 10−4 for predicting slip. In addition, the effect of friction and angular velocity condition on the cold rolling critical slip phenomena are investigated. The results show that ANNs can accurately predict the cold rolling parameters considered in this study.

Analysis of 3D plastic deformation in vertical rolling based on global weighted velocity field

Energy method is an essential theoretical approach to analyze plastic forming, which is widely used in rolling process. An analysis model for vertical rolling process is established according to energy theory. By using global weighted method firstly, the 3D continuous velocity field, strain rate field and the corresponding power functional are proposed. The unknown variables are calculated numerically based on the principle of minimum energy. Then, deformation parameters and rolling force are determined. The analysis on specific examples shows that the theoretical prediction value of weighted model is in good agreement with experimental results. Moreover, the effects of several shape and rolling parameters on rolling force, rolling power and edge deformation are studied. Both the width reduction rate and initial slab thickness have significant influences on dog-bone size and rolling force. A wider slab slightly increases the nonuniformity of dog-bone deformation. And the increase of vertical roller radius can weaken the edge deformation.

Meeting Corporate Renewable Power Targets

Several corporations have committed to procuring a percentage of their electricity demand from renewable sources by a future date. Long-term financial contracts with renewable generators based on a fixed strike price, known as virtual power purchase agreements (VPPAs), are popular to meet such a target. We formulate rolling power purchases using a portfolio of VPPAs as a Markov decision process, accounting for uncertainty in generator availability and in the prices of electricity, renewable energy certificates, and VPPAs. Obtaining an optimal procurement policy is intractable. We consider forecast-based reoptimization heuristics consistent with practice that limit the sourcing of different VPPA types and the timing of new agreements. We extend these heuristics and introduce an information-relaxation based reoptimization heuristic, both of which allow for full sourcing and timing flexibilities. The latter heuristic also accounts for future uncertainties when making a decision. We assess the value of decision flexibility in rolling power purchases to meet a renewable target by numerically comparing the aforementioned policies and variants thereof on realistic instances involving a novel strike price stochastic process calibrated to data. Policies with full timing flexibility and no sourcing flexibility reduce procurement costs significantly compared with one with neither type of flexibility. Introducing sourcing flexibility in the former policies results in further significant cost reduction, thus providing support for using VPPA portfolios that are both dynamic and heterogeneous. Computing near-optimal portfolios of this nature entails using our information-relaxation based reoptimization heuristic because portfolios constructed via forecast-based reoptimization exhibit higher suboptimality. This paper was accepted by Ilia Tsetlin, behavioral economics and decision analysis. Supplemental Material: The online appendix is available at https://doi.org/10.1287/mnsc.2022.4354 .

Effect of Ultrasonic Rolling on Properties of GCr15 Bearing Steel

The effects of ultrasonic rolling processing on the properties of GCr15 bearing steel were studied in this paper. The specimens were treated with different values of preload in ultrasonic rolling processing. The surface roughness, microhardness and rolling contact fatigue life of the specimens before and after ultrasonic rolling processing were analysed and compared. The index of power density was firstly introduced and combined with ultrasonic rolling parameters. The results show that the qualities of surface roughness and microhardness are improved after ultrasonic rolling treatment, and the friction coefficient is reduced. However, when the ultrasonic rolling power density exceeds 11.24 Gw/cm2, the grain sizes of the specimens becomes larger, which leads to the increase of the internal stress, resulting in the initiation and propagation of crack. The propagation mode of fatigue cracks changes from transcrystalline to intergranular after ultrasonic rolling treatment, reducing the performances of wear resistance and rolling contact fatigue.

Numerical Simulation of the Hot Rolling Process of Steel Beams.

The complete rolling schedule (25 passes) of steel beams in a mill was simulated to predict the final beam length, geometry of the cross-section, effective stress, effective plastic strain and rolling power for two cases; the first case corresponds to the hot rolling process assuming a constant temperature of 1200 . The simulation of the second case considered the real beam temperature at each pass to compare the results with in-plant measurements and validate the numerical model. Then, the results of both cases were compared to determine the critical passes of the process with high peaks of required power, coinciding with the reports at the mill. These critical passes share the same conditions, high percentage of reduction in cross-sectional area and low beam temperature. Additionally, a potential reduction of passes in the process was proposed identifying passes with low required power, minimal reduction in area of cross-section and essentially unchanged geometry. Therefore, it is reasonable to state that using the present research methodology, it is possible to have a better control of the process allowing innovation in the production of profiles with more complex geometries and new materials.

Influence of Lubricants and Contact Pressure Models on the Rolling Power along Thin Aluminum Stripes

Influence of Lubricants and Contact Pressure Models on the Rolling Power along Thin Aluminum Stripes

A Novel Wolfrom-Based Gearbox for Robotic Actuators

In many robotic applications, high torque density and highly efficient actuators are required to handle the high torque motion without hampering mobility through excessive weight and footprint. Traditionally, engineers designing actuators for these types of applications use high-speed electrical motors in combination with high-ratio speed reducers such as harmonic and cycloid drives or lever arms in order to achieve the required torques. However, these systems are not ideal since they suffer from one or more of the following limitations: high cost, load hysteresis, nonlinear behavior, and torque ripple. An alternative to achieving the required torque increase is using an interesting type of compound planetary gear trains (C-PGTs). In this article, a novel type of such a C-PGT, based on the Wolfrom topology, is presented. An extra degree of freedom is created, which can be used to increase the performance of the overall gearbox, i.e., increase its efficiency, reduce its inertia, increase its torque capability, etc. This modified Wolfrom is discussed in detail by deriving a general framework for the design of such a transmission system. This framework consists of listing the specific fitting conditions for such a Wolfrom planetary gear train, the derivation of an efficiency model based on the Rolling Power concept, and a load analysis to determine the weakest gearing element. Finally, a prototype is built to demonstrate the design framework and the feasibility of the Wolfrom variant. Additionally, the trend of the efficiency model is confirmed.

Tribological Behaviors and Lubrication Mechanism of Water-based MoO3 Nanofluid during Cold Rolling Process

The MoO3 nanofluid was prepared by mixing deionized water with MoO3 nanoparticles and some other organic additives. The tribological behaviors of prepared MoO3 nanofluid in various nanoparticle concentrations were tested by four-ball tribotester. The results obtained therein revealed that the dispersion of the nano-MoO3 in water was conducive to the reduction of friction coefficients and wear volume, and the increase in the load-bearing capacity, especially the optimal concentration of additive was 0.4 wt.%. To investigate the lubrication mechanism of water-based MoO3 nanofluid under steel cold rolling condition, cold rolling lubrication performance of 0.4 wt.% MoO3 in water-based fluid was evaluated using a four-high rolling mill. The rolling outputs such as rolling force, rolling power and reduction were used as measurands for determining the process efficiency. Erosion corrosion was found to happen during steel cold rolling process, MoO3 was transformed to MoO2 and iron was oxidized to iron hydroxide. A lubricating film composed of MoO3, MoO2 and Fe(OH)3 was considered to form on strip surfaces due to chemisorption and deposition of MoO3.

Analysis of pipe piercing on PRP 70-270 with FEM modeling

The article analyzes the piercing and rolling process of seamless pipes on PRP 70-270 of JSC “VMP” in terms of power parameters, piercing time and geometric sizes of pipes. The research results were compared with the results of computer simulation on software package QFORM 3D. For simulation, the deformation zones were designed for piercing a mold tube with dimensions of 203×16.5 mm in one pass on a mandrel with diameter of 162 mm and in two passes of piercing and rolling-off on mandrels with diameter of 76 and 162 mm, respectively. From the obtained data on the power parameters, it was found that from the point of view of energy consumption, piercing in one pass seems more appropriate. However, when piercing in one pass, wear resistance of the mandrels sharply decreases, since the contact time between the tool and the hot metal increases. This leads to a decrease in quality of the pipes’ inner surface, more frequent replacement of the tool and increased downtime of the equipment. During simulation, the selected parameter of the friction factor has a significant impact on the value of power parameters (torque and power consumption) and piercing time. The dependences of changing power parameters and piercing time on the friction factor during piercing in a two-roll mill with guards are obtained. With increase of the friction factor, piercing time decreases and torque and rolling power increase. The simulation results are correlated with results of experimental rolling. With a correctly chosen value of the friction factor, power parameters and geometry of the mold tube can be quite accurately predicted by computer modeling.

STUDY OF THE EFFECT OF FRICTION ON THE POWER PARAMETERS OF ROLLING WITH ONE DRIVE ROLL

The influence of friction conditions in the deformation cell is studied, taking into account the differences of the distribution of contact stresses on the drive and non-drive rolls, on the normal pressure and rolling force. The research methodology involved the development of a mathematical model of the process and conducting a numerical experiment. The rolling process model is based on the numerical solution of the Karman`s equation using the Coulomb friction law and boundary conditions appropriate of the rolling process with a single drive roll. When conducting a numerical experiment, the coefficient of friction in the deformation cell was changed at four levels in the range from 0.15 to 0.30. The coefficient of friction in the journal bearings non-drive rolls was varied at three levels. From the analysis of the obtained distributions of contact stresses along the length of the deformation cell by the drive and non-drive rolls, it was found that with decreasing the coefficient of friction in the deformation cell, the normal pressure decreases proportionally, as well as the difference between the pressure on the drive and non-drive rolls. The occurrence of longitudinal tensile stresses with a coefficient of friction in the deformation cell of 0.25 and more is noted. The coefficient of friction in the non-drive roller bearings, for the entire range of values taken, does not have a significant effect on the contact stresses, pressure and rolling power. The presence of tensile stresses when rolling with one drive roll leads to a decrease in the average pressure and rolling power within 8-10%. Therefore, rolling with one drive roller can be used to reduce energy costs. In addition, the presence of tensile stresses, at certain values of the coefficient of friction in the deformation cell, accordingly affects the mechanical and technological properties of the rolled products, but this feature of the process requires additional study.

Research on the Buoy-rolling Type Power Generation Device Driven by Wave Energy

Marine energy is inexhaustible form of energy. The utilization of wave energy depends on a certain number of energy conversion devices, but most of the aforementioned devices require a high level of the coastal environment and sea conditions, so it is difficult to popularize them on a large scale. In view of this research situation, this paper introduces a wave-driven buoy rolling power device, which has compact structure and convenient installation. The device is distinguished by superior structural strength and low energy transmission loss. Built on the analysis of the working principle of the device, the power calculation is performed and the strength of the key components is checked by the finite element method. Through simulation analysis, the feasibility of the device design is verified.

Multi-parameter deep-perception and many-objective autonomous-control of rolling schedule on high speed cold tandem mill

High-speed cold tandem rolling process control system consists of complex mechanical and electrical equipments. The coupling association of these equipments makes multi-objective rolling process complicated to be predicted and controlled. In order to achieve higher prediction precision, a multi-parameter depth perception model is established based on a deep belief network. To get higher control precision in real time, a multi-objective rolling optimization method is introduced, which is supported by many-objective evolutionary algorithm. Five objectives are selected as rolling schedule optimization objective: equal relative power margin, slippage prevent, good flatness, total energy consumption and energy consumption per ton. Simulation results show that many-objective evolutionary algorithm based on decomposition and Gaussian mixture model achieves a set of balance solutions on these objectives. The proposed method could not only predict rolling force and rolling power in real time, but also give the solutions for many-objective reduction schedule.

Correlations between the Hysteresis Parameters Determining the Rolling Resistance in Rubber Composites

Abstract Recently, the research on low rolling resistance tires attracted interest for its reduction of petrol consumption, which is related to the hysteresis loss of rubber composites. Here, four common methods representing the hysteresis loss of rubber composites in lab were contrasted to explore the potential connections between them. The results indicated that tan δ obtained by DMA showed good positive linearity with that obtained by RPA without distinguishing the rubber species and filler types, also for the positive relation between tan δ and hysteresis loop area (HLA). The rolling power loss (L) captured by the rolling resistance testing machine appeared to have a positive correlation with tan δ from DMA or RPA in NR composites, while a negative connection showed up in SBR composites. Further, considering the influence of strain on rolling energy loss, the 100% modulus was introduced leading to a good positive quadratic equation connection between tan δ/100% modulus and L in all common rubber composites.

Multi-Objective Optimization of Rolling Schedule for Five-Stand Tandem Cold Mill

The optimization of rolling schedule is the main content of tandem cold rolling which will affect the quality of products directly. A rolling schedule with the objectives of minimum energy consumption, relative power margin and slippage preventing is established. First, in order to make the rolling schedule more accurate in the calculation process, a mathematical model combines with deep neural network is proposed to calculate the rolling force. Second, a multi-objective particle swarm optimizer with dynamic opposition-based learning is proposed to optimize the rolling schedule. It has a new particle learning strategy to update the moving position of particles. Moreover, opposition-based learning is proposed to make the particles jump out of local optima. Finally, the experiments are carried out based on the field data. Simulation results demonstrate that the accuracy of the rolling force is greatly improved. The proposed algorithm has a promising performance on both diversity and convergence. At the same time, the optimized rolling schedule can well balance the rolling power and prevent slipping between five stands comparing with the original rolling schedule.

Meeting Corporate Renewable Power Targets

Several corporations have committed to procuring a percentage of their electricity demand from renewable sources by a future date. Long-term financial contracts with renewable generators based on a fixed strike price, known as virtual power purchase agreements (VPPAs), are popular to meet such a target. We formulate rolling power purchases using a portfolio of VPPAs as a Markov decision process (MDP), accounting for uncertainty in generator availability and in the prices of electricity, renewable energy certificates, and VPPAs. Obtaining an optimal procurement policy is intractable. We consider forecast-based reoptimization heuristics consistent with practice that limit the sourcing of different VPPA types and the timing of new agreements. We extend these heuristics and introduce an information-relaxation based reoptimization heuristic, both of which allow for full sourcing and timing flexibilities. The latter heuristic also accounts for future uncertainties when making a decision. We assess the value of decision flexibility in rolling power purchases to meet a renewable target by numerically comparing the aforementioned policies and variants thereof on realistic instances involving a novel strike price stochastic process calibrated to data. Policies with full timing flexibility and no sourcing flexibility reduce procurement costs significantly compared to one with neither type of flexibility. Introducing sourcing flexibility in the former policies results in further significant cost reduction, thus providing support for using VPPA portfolios that are both dynamic and heterogeneous. Computing near-optimal portfolios of this nature entails using our information-relaxation based reoptimization heuristic because portfolios constructed via forecast-based reoptimization exhibit higher suboptimality.