Papers by Keyword: Rolling Force

Abstract: The formulation and solution of the problem of double-T section rolling in universal groove using the variational principle of minimum total power with aim to determine integral forming and energy-power parameters are presented. Geometrical model of the deformation zone and the kinematically admissible velocity field were constructed accurate within two unknowns: forward slip coefficient ν, flange spread (pulling-down) . The comparison of the calculated values with the experimental data obtained on a laboratory mill 200 confirmed that the variational principle of minimum total power has sufficient accuracy for analysis of double-T section rolling in universal groove. The mean statistical error of torque calculation is 12.3 % while load calculation is 18.7 %.

Abstract: The mathematical model of hot-rolled coil rolling at the Steckel mill (Ferriera Valsider SpA) has been thoroughly investigated in the paper. There has been made a verification of the developed model to use it for the rolling technology design. The influence of the stand stiffness has also been taken into account. When simulating rolling temperature conditions, an average error was within the range from 8.27 to 9.11% at the mill 3170 and from 0.003% to-0.92% at the mill 1780. When simulating rolling force, an average error was within the range from 0.5% to 5.7% at the mill 3170 and from-4.89 to 6.59% at the mill 1780. The equation has been obtained, and the comparison of calculated stands stiffness has been made at the mill 3170 and 1780.There has been determined influence on the actual measurement of the pre-treatment temperature for the feed processing by descaler, which results in significant errors compared to the calculation results.

Abstract: Based on application the physical constraint equations of state of stress and strain of the metal for the isotropic medium, we get expressions for components of stress tensor. The new theoretical method for calculation of contact pressures and rolling force during rolling of double-T section in a universal beam groove was developed. Reliability of the method is confirmed by the results of experimental verification for conditions of rolling of H-beam No 35B1, 40K2 and 45B2 from steel 15CrSiNiCu on the universal beam mill of "NTMK". The average calculation error is 6.4%. The new method is recommended for calculation pass design and technological modes of H-beam rolling on rail-beam and section mills, equipped with universal stands.

Abstract: A new solution Karman’s equation with the Mises plasticity condition is proposed for determining contact stresses in the slip zones for hot strip rolling. Replacement of the precise plasticity condition by an approximate condition in terms of primary stress leads to a substantial decrease in the length of slip zones and to increase of the rolling force. It was shown that, even at high frictional coefficients, the length of slip zones forms a significant part of the length of deformation region. On the basis of the obtained solutions the techniques for plotting curves of the normal contact stresses, determining the length of the slip zones, the neutral position of the cross section and rolling force refined.

Abstract: Тhere has been developed technology, and pilot batch of hot rolling coils (6×1500 mm, steel grade S355MC) has been produced using thermo-mechanical controlled process (TMCP) for the wide-strip rolling mill 1700. The integrated technology for TMCP coil production (steel grade S355MC) has been firstly developed for the rolling mill 1700 in accordance with EN 10149-2. Air cooling for coils to 450°C after coiling has been firstly used in the developed technology, which provides for decrease in air scale and improvement of surface quality for the customers. It is possible to manufacture rolled products up to 6×1500 mm (steel grade S355MC) in accordance with EN 10149-2 using the existing equipment without exceeding the existing process constraints during its operation and without upgrading. It is possible to further master the rolled products, which are manufactured according to the TMCP technology.

Abstract: In this work the developing manufacturing technology for 4mm thick plates produced of 220mm thick continuous cast slabs instead of 150mm thick slabs for mill 3200 (Metinvest Trametal SpA) is shown. The technology has been developed with the mathematical model of the rolling process. Тhe rolling technology for manufacturing of plates (4×3125×16000mm) from slabs (217×1355×780mm) has been developed. The developed technology makes it possible to reach the final rolling temperature of 826oС, which provides a good opportunity to use it for plate production in keeping with the hot, normalizing, controlled rolling technology or TMCP, and does not limit the existing grade mix. It is possible to use for production of 220mm thick slabs instead of 150mm thick slabs.

Abstract: A three dimensional (3D) surface profiler, an X-ray residue stress tester, a potentiodynamic polarization approach and a damp heat test were employed to investigate the relationship between the rolling force (RF) and the corrosion resistance of interstitial-free (IF) auto sheet steels. The results show that the change of rolling force induces the variance of the surface topography and surface residue stress of IF steel. With the increasing RF, the corrosion resistance of IF steel in damp heat test can be enhanced, and the corresponding corrosion current density declines. Further, it is proved that the tensile stress on the surface can accelerate the corrosion rate of IF steel. As the compressive stress and the valley proportion on the surface increase, IF steel samples present a better corrosion resistance, because the compressive stress could retard the diffusion of corrosion media and the valley position possesses a lower electrochemical activity.

Abstract: The method of determination of the force of counter flexure of the working rolls was designed, ensuring improvement of the degree of flatness of cold rolled strips with due regard to the influence of unevenness of distribution of inter-rolls linear load. On the basis of the analysis of numerical realization of this method an essential influence of the width of the rolled strips upon the optimal value of the force of counter flexure was found out. Also, it was suggested to approximate the connection between increments of the force of counter flexure with linear equations, the application of which is promote to improvement efficiency of systems of automatic adjustment of shape and profile at rolling of sheets. For the condition of 4-stand cold rolling mill the values of transmission coefficients depending on widths of rolled strips were determined.

Abstract: Due to the influence of rolling force fluctuations, tube size changes and material uniformity and other factors, vibration and other phenomenon inevitably occur in the rolling process of tandem rolling mill. This vibration has a great impact on the dynamic stability of the mill and rolling reduction, and will significantly reduce the dimensional accuracy and surface quality of seamless steel pipe. In this paper, the non-linear finite element software ABAQUS is used to simulate the rolling process of seamless steel pipe. First, rolling force of the first frame with the maximum rolling force of PQF rolling mill is calculated. The reliability of rolling force calculated by the finite element method is verified by the test experiment. The dynamic response analysis of the roll is carried out to obtain the dynamic response curve of the roll in the rolling state and to provide technical support for the rolling schedule with the calculated rolling force being the load.

Abstract: Due to the problems that the rolling force of seamless steel tube during tandem rolling process is affected by many factors, the calculation is complex and the accuracy is not enough. In order to improve the rolling force calculation accuracy of the tandem rolling mill, analyze the metal flow, stress distribution rules and cross section deformation characteristics during the rolling process of seamless steel tube, calculation of the rolling force was divided into the reduced-diameter area and the reduction of wall area, and a new calculation method was proposed, which concerns the rolling force in reduced-diameter area related to the material yield stress, friction coefficient and the crushing stress of the tube, while the rolling force in the reduction of wall area is only related to the material yield stress and the friction coefficient. The results show that the calculated rolling force is in agreement with the measured values with errors less than ±10%. The model satisfies the actual conditions and is applicable to engineering application.