Influence of Outer Parts of a Strip on the Deformation and Force Parameters of Thin-Sheet Rolling
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INFLUENCE OF OUTER PARTS OF A STRIP ON THE DEFORMATION AND FORCE PARAMETERS OF THIN-SHEET ROLLING R. L. Shatalov1 and M. A. Kulikov2
UDC 621.771.01
We present the results of experimental investigations of the distribution of deformation indicators and rolling forces along the length of brass (L63) strips in a 150 × 235 two-roll mill equipped with a microcontroller system for high-precision measurements of loads acting upon the rolls. The results of the quantitative analyses of changes in the sizes of strips and rolling forces on stationary and nonstationary sections along the strip length are presented. A significant effect of the outer parts of the strip on the rolling force and the pressure of the metal upon the rolls is established. On the basis of the experimental results, we propose an equation for the evaluation of the influence of the outer parts of the strip on the rolling force and pressure. The equation for the mean pressure of the metal upon the rolls is improved with regard for the influence of the outer parts and the stiffness of the strip on the site of deformation in the process of thin-sheet rolling. It is shown that the proposed equations make it possible to increase the accuracy of evaluation of pressure and determination of rolling forces along the length of thin strips. Keywords: deformation indicators, rolling force, evaluation of the mean pressure, outer parts and the stiffness of the strip, 150 × 235 rolling mill, L63 brass, measurement of rolling forces along the length of the strip, microcontroller system for measuring forces.
The metallurgical and machine-building plants are equipped with sheet mills of various types and purposes in which the deformation of metals along the length is realized under various conditions. In the process of rolling of strips, it is necessary to guarantee not only the production of large amounts of sheet metals but also its high quality along the entire length [1–4]. The presence of contact friction between a strip and the rolls guarantees the possibility of seizure and realization of the steady process of rolling. Independently of the conditions of contact deformation observed in the course of rolling of the end sections of sheets, strips, and bands, we can assume that the neighboring vertical sections of the semifinished rolled metal in the zone of deformation are in the state of pure plastic compression. Then the pressure required for the plastic deformation of the end sections is practically equal to the true yield limit of a sheet or a strip under the conditions of plane deformation at the beginning and at the end of the zone of deformation. In the case of plastic compression of the other vertical sections along the length of the sheet (strip), the compressive stresses or the pressure of the metal upon the roll are higher than in the end parts. In the steady-state period of rolling, in the process of deformation of the middle cross sections, a part of the metal should be shifted toward the entry or toward the exit against the action of friction forces acti
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