Rolling Power Research Articles

An assessment of thrust vector concepts for twin-engine airplane

Thrust vector nozzles are finding place on modern fighter airplanes because of the benefits they provide and also due to diminishing weight penalty of such nozzles. They offer additional benefits in the case of a twin-engine airplane. Different vectoring configurations such as multi-axis vectoring, single-axis pitch vectoring and single-axis vectoring with canted nozzles have been studied with respect to twin-engine airplane configuration. Modeling and integration of thrust vector nozzles with rigid airplane six-degrees-of-freedom equations of motion have been carried out in this article. Using the integrated model, a comparative study is carried out to summarize the capabilities and limitations of various nozzle configurations with respect to performance of an airplane in velocity vector roll and in Herbst maneuvers. The airplane model used in this work is the F-18/HARV and all simulation results have been produced using a nonlinear dynamic inversion controller developed in Matlab/Simulink environment. Results show that a multi-axis thrust vectoring provides additional benefits as compared to single-axis vectoring with canted nozzles in high angle of attack velocity vector roll and in Herbst maneuvers. The single-axis pitch only vectoring has roll control power and lacks in yaw control power, to execute the velocity vector roll maneuver.

Temperature dependence of wall-plug efficiency of high power laser diodes

Temperature dependence of wall-plug efficiency of high power laser diodes is theoretically analyzed in terms of experimentally measured parameters of the device. This issue has an influence on the available power output and on the degradation mechanism. High power laser diodes have become increasingly important as the output power of such devices continues to rise. The present calculations revealed that the decrease of wall-plug efficiency with temperature could be explained, presumably in terms of excess voltage loss and internal waveguide optical loss. Understanding the dynamic mechanism of the decrease of efficiency can lead to optimum operating conditions of the device. Thermally rolling power runaway is found to be an important factor in the high power laser diodes degradation and eventually to device failure Key words: Laser diodes, high power, wall-plug efficiency, internal loss, waveguide loss.

Optimisation of total roll power using genetic algorithms in a compact strip production plant

The application of optimisation techniques to hot rolling models can lead to the more efficient use of these models. In this work, a genetic algorithm has been used in order to design new hot rolling schedules with lower energy consumption through a reduction in the total roll power. Firstly, mean flow stress has been modelled for several Nb microalloyed steels produced in a compact strip production plant taking into account recrystallisation and precipitation models. The selected mean flow stress model has been validated against the values obtained from the industrial hot rolling forces using the Sims approach. Secondly, the model has been integrated with a genetic optimisation algorithm and new reductions have been proposed in order to decrease the total rolling power, maintaining all the requirements. The reductions achieved can be up to 10%.

Multi-objective optimization for draft scheduling of hot strip mill

A multi-objective optimization model for draft scheduling of hot strip mill was presented, rolling power minimizing, rolling force ratio distribution and good strip shape as the objective functions. A multi-objective differential evolution algorithm based on decomposition (MODE/D). The two-objective and three-objective optimization experiments were performed respectively to demonstrate the optimal solutions of trade-off. The simulation results show that MODE/D can obtain a good Pareto-optimal front, which suggests a series of alternative solutions to draft scheduling. The extreme Pareto solutions are found feasible and the centres of the Pareto fronts give a good compromise. The conflict exists between each two ones of three objectives. The final optimal solution is selected from the Pareto-optimal front by the importance of objectives, and it can achieve a better performance in all objective dimensions than the empirical solutions. Finally, the practical application cases confirm the feasibility of the multi-objective approach, and the optimal solutions can gain a better rolling stability than the empirical solutions, and strip flatness decreases from (0±163) IU to (0±45) IU in industrial production.

Optimization of Pass Schedule in Hot Strip Rolling

Rolling schedule not only determines the rolling process to be going smoothly, but also affects the shape accuracy and structure properties of finished strip. In order to gain good strip crown and flatness, the calculation formulas of the most suitable rolling force and bending force are deduced. By taking relatively equal load of rolling power and good shape as objective functions, the optimization mathematical models of finish rolling schedule are established. By contrast, the rolling schedules after optimization can improve the rolling mill working status and ensure the strip crown and flatness to be good. At the same time, the setting value of bending force is improved and this leaves more space for on-line shape control.

Experimental Investigation on Water Miscible Rolling Lubricant J4

A contrast test was done about the service performance of commercial emulsion II and water miscible rolling lubricant J4 with polyethylene glycol. The test results were given to have analysed them in lubrication, extreme pressure performance, simulating annealing, resistance of putrefy, rust protection etc. From the rolling mill in the lab, at the same depress ratio, the pressure reduce 3.85kN using J4 than using II, and the rolling power reduce 0.04kW using J4 than using II. By four-ball tester, the maximum load PB of J4 is 932N, the friction is 0.0518, and the wear diameter is 0.47mm. Water miscible rolling lubricant J4 is notable in lubrication, extreme pressure performance, annealing, resistance of putrefy and rust protection. The results may offer the reference for further optimization on water miscible rolling lubricant.

Determination of roll power required for rolling of plastic and rubber mixtures

Calculations of the power required for the rolling of a material, whose behavior under load is described by a power law, is analyzed, proceeding from the dissipation power released in the material being reworked as a result of its deformation in the inter-roll gap, and also from the torque required to turn the rolls. It is demonstrated that both approaches are acceptable for a common roll drive, while it is expedient to use a procedure based on calculation of the torque required to turn the rolls when individual drives are employed for the latter.

Development and Application on Simulation System of Plate Rolling

It commences that optimize and design the billet of the medium slab, analyzes various factors that influence plate yield, and proposes the method of the reasonable billet design. Then it anticipates each shift team production plans according to each reasonable combination of the different billet. It is based on the spot production experience of plate, and guarantees the safety of equipments, with attainment of high yield, to optimize design of plate deformation. It imitates calculation the microstructure organization of the medium plate after rolling and cooling by means of researching on the rule of austenite recrystallization. The calculation of the rolling power adopts to consider the variety of the recrystallization in austenite the correction function, improve the accuracy forecast of power and energy. The simulation and calculated results will be showed by means of tabular form or graphic formats.

A finite element-based on-line model for the prediction of roll force and roll power in a round-oval-round pass rolling sequence

This paper presents a precision online model for the prediction of the roll force and roll power in a round–oval (or oval–round) pass rolling sequence, which is most commonly employed in rod and wire mills. The approach uses the concept of ideal rolling, to reduce the number of the dimensionless parameters with which the model is constructed. The prediction accuracy of the proposed model is examined through comparison with the predictions from a finite element model. The prediction accuracy is also examined through comparison with measurements made in POSCO No. 3 wire and rod mill.

3D FE Modeling of Three Rolls Cross Rolling Process of a Rotary Disk Part

Special rolling is also called rotary forming process, which is an advanced manufacture technology of making workpiece generate deformation in a rotary state by continuous local plastic forming. Disk rotary parts with outer stepped cross-section, such as wheels, flanges, valves and so on, are widely used in engineering machinery. Traditionally, this kind of part is manufactured by forging and cutting, which consumes a lot of energy and materials especially to the large size part. In this paper, a new specific rolling technique called three rolls cross rolling is first presented to produce this kind of part, and the principle and characteristics of this technique are described in detail. Then, base on the principle of the three rolls cross rolling, a 3D coupled thermo-mechanical FE model is developed under ABAQUS software environment. As a result, under the simulation and analyses of a real example, the feasibility of this technique is verified, and the evolutional laws of the strain, temperature and rolling force and power parameters during the process are investigated as well. The obtained results provide valuable guidelines for the further investigation on the forming characteristic of the three rolls cross rolling technique.

A Method to Derive Friction and Rolling Power Loss Formulae for Mixed Elastohydrodynamic Lubrication

Prediction of mechanical power losses of gear pairs requires elastohydrodynamic lubrication (EHL) analyses to be carried out at every discrete contact position. This makes gear efficiency models computationally demanding. As a remedy to this problem, a method is proposed in this study to derive EHL-based friction coefficient and rolling power loss formulae to be used in gear efficiency models. This method employs a large number of EHL analyses covering a full matrix of all key contact parameters, namely normal load, rolling and sliding velocities, radii of curvature, lubricant parameters and surface roughness amplitudes, within typical ranges dictated by gear contacts. Linear regression of the results of the EHL analyses yields friction coefficient and rolling power loss formulae suitable for gear efficiency models. In the EHL model, the hydrodynamic fluid and asperity contact zones are treated in a unified manner. The sliding friction is computed as the sum of the viscous shear within the lubricant and the boundary friction at the local asperity contact spots. The rolling power loss induced by fluid pressure gradient is formulated to include the entire contact zone instead of only the inlet region, since the pressure gradient is substantial within the contact for rough surface condition. The proposed method is demonstrated using an example turbine fluid. Typical measured gear surface roughness profiles are used in the analyses. At the end, the results from the regression formulae are compared to actual EHL predictions to assess their accuracy under various contact conditions.

Optimization of Rolling Schedule in Tandem Cold Mill Based on QPSO Algorithm

This paper adopts equal relatively load as objective function, and makes every parameter to meet certain restrictive conditions. SUMT algorithm was used to change constraints to non-binding conditions. QPSO algorithm was applied to optimize objective functions to obtain optimal solution. This algorithm was based on classical particle swarm optimization, which, with the conduct of quantum particle, had effective global search capability, good convergence and stability. As a result, reasonable distribution of tandem cold rolling power and full use of equipment capacity were realized, resulting in the improvement of production efficiency.

New Roll Pass Design to the Bar Rolling Process Using Longitudinal Slitting Passes

: groove-rolling, energy-force parameters, numerical modeling, FEM Abstract. The paper presents the developed new roll pass design and a new method of rolling in slitting passes of bar with longitudinal band, which reduce energy consumption and increase durability of slitting passes compared to the methods used previously. The results of theoretical analysis were verified based on the measurements of rolling power taken during bar rolling according to the multi-strand rolling technology. Forge2007 software was employed in the numerical analysis of the process of rolling with band slitting.

The Influence of Rolling Temperature on the Energy and Force Parameters during Normalizing Rolling of Plain Round Bars

The paper presents results of theoretical and experimental studies on the influence of strip temperature reduction at the final stage of the normalizing rolling process in a continuous bar rolling mill on the energy and force parameters. The studies were carried out for 38 mm-diameter round bars of constructional steel S355J2G3 (St52-3 acc. to DIN). At the first stage, numerical modelling of the rolling process was performed for the conditions of the currently used rolling technology. The aim of this stage of the work was to determine the distribution of strip temperature during the rolling process and of strip temperature after the rolling process. The obtained computation results were compared with the measurement results recorded during the actual rolling process using a thermovision camera. A computer program designed for three-dimensional modelling of metal flow during rolling in passes was used for the determination of the distribution of strip temperature during rolling. The second stage of the studies included modelling of the bar rolling technology modified by applying normalizing rolling after introducing accelerated strip cooling at the final stage of rolling. The aim of this stage of the work was to establish the influence of reduced strip temperature on the change in the values of the energy and force parameters of the process. By comparing the computed values of rolling power with those of the permissible power it was found that these values were lower than the permissible power of the rolling machine’s main drives installed in the Rolling Mill under analysis. Thus, it was demonstrated that it was possible to implement the process of normalizing rolling in the conditions of the Shape Mill under study.

An Analytical Modified Model of Clad Sheet Bonding by Cold Rolling Using Upper Bond Theorem

In this paper, clad sheet bonding by cold rolling was investigated using the upper bond theorem. Plastic deformation behavior of the strip at the roll gap was investigated, unlike previous methods; distinctive angular velocities are used for different zones in roll gap in present model and absolute minimum of rolling power function is achieved. Rolling power, rolling force, and thickness ratio of the rolled product affected by various rolling condition such as flow stress of sheets, initial thickness ratio, roller radius, total thickness reduction, coefficient of friction between rollers and metals and between components layer, roll speed, etc., are discussed. It was found that the theoretical prediction of the thickness ratio of the rolled product, rolling force, and rolling power are in good agreement with the experimental measurement.

Investigation of Single Pass Shape Rolling Using an Upper Bound Method

This paper presents a generalized analytical upper bound method for the study of external shape, pressure, and torque in the single pass rolling of shaped sections. Generalized kinematically admissible velocity fields have been calculated from an assumed deforming geometry, in turn mathematically developed from a new parameterization of curves for the stream line flow of the material. An upper bound on rolling power was established based on the calculated velocity fields. Unknown variables in the velocity field were determined by minimizing rolling power with respect to unknown velocity field variables, yielding an upper limit to the actual power required as well as rolling pressure and torque. As an applied example, the single oval-to-round and rectangle-to-diamond roll passes have been chosen and analyzed. Velocity fields and power relations were obtained for each pass and computer analysis was carried out to analyze and simulate the process of shape rolling. External shape, average roll torque, and rolling pressure data from the analysis were compared with other worker’s analytical solutions, numerical analyses, and experimental data. The results were found to be in good agreement with previous research and the method was shown to be quicker and easier to use.

Three-dimensional analysis of shape rolling using a generalized upper bound approach

A generalized analytical method has been proposed to study external shape and calculate pressure and torque for the process of rolling shaped sections. The proposed method is based on the upper bound analysis. To determine kinematically admissible velocity fields, flow lines have been mathematically formulated using the parameterization of curves. Based on the calculated velocity fields, an upper bound has been found on rolling power. The calculated power has been minimized with respect to unknown variables to yield the value closest to the actual power required. The proposed general method has been applied to certain rolling passes including square-to-oval and round-to-oval. Velocity fields and power relations have been obtained for each process. Computer analysis has been carried out for all the mentioned passes using dimensions and conditions from experiments conducted by other workers. External shape, average roll torque and average rolling pressure results from the analysis have been compared with analytical solutions, numerical analyses and experimental data presented by other workers. It was concluded that the present method gave very good results and was quicker and easier to use.

Procedure and algorithms for the energy-force calculation of cold rolling allowing for the number of neutral sections in the deformation zone

A procedure and algorithms are described for the calculation of the rolling power and the main-drive engine power and torque of a working stand in a cold-rolling mill with regard for the number of neutral sections in the deformation zone, including the case of two neutral sections in the deformation zone. This work is a continuation of our earlier work, where we were the first to consider a deformation zone with two neutral sections and proposed a procedure for the calculation of the contact stresses and rolling forces in it. Taking into account the second neutral section is shown to decrease the engine power calculation error by a factor of 4.5–6.5 (on average from 25 to 4%), which allows one not to use too high safety factors when choosing the power rating of the main drive in a cold-rolling mill.

Energy-force parameters of six-high stands in wide-strip rolling mills

A new procedure is developed to compute the energy-force parameters of six-high stands in which a main drive is transferred through intermediate or backup rolls. The rolling force, power, and torque are calculated, and the forces and moments acting between work, intermediate, and backup rolls are determined with allowance for rolling friction and friction in bearings. The procedure developed can be used to calculate the optimum design parameters of stands of this type that provide the minimum capital outlays and energy consumption.

Mechanical properties prediction for hot rolled products

The improvement of the mechanical properties of the hot rolled products is directly related to the rolling process, concerning the reduction schemes and cooling conditions. These operational parameters influence the steel internal microstructure and therefore mechanical properties. In order to link the mechanical properties of the final product with plant operational conditions there are some intermediate variables that must be solved, like thermal field in the steel section and its microstructure evolution. Recrystallization, grain growth, precipitation and phase change models, which are dependent on steel composition and process variables, are able to predict the microstructure evolution along the rolling process. At the same time, the thermal field prediction can be solved by an appropriate mathematical model that takes into account all related effects such as roll contact, volumetric heat generation during the strip reductions or scale effects, apart from the thermal conduction in the strip thickness. Once these models get solved, it is straight forward to obtain another important data like roll power or roll torque, which are the key for considering roll wear and other economical aspects. The global idea is to get operational plant data and steel composition, and to calculate the prediction of the thermal history of the process, the microstructure during the processing time and the final mechanical properties. An overview of the lay out is presented in figure1.