STRESS STATE STUDY DURING ROLLING IN A BOX CALIBER WITH A CHILLED SURFACE

S. Yershov, Wu. Kaiming

Abstract


The article deals with the influence of the uneven distribution of the temperature field of the billet on the stress state of the strip when rolling in a box-shaped caliber for the production of pipe billets. Until recently, in the study of deformed and stressed state there were problems ones related to the accounting accuracy of the non-uniformity of deformation in the caliber itself, which when rolling in box-shaped calibers is significant due to the fact that the studied deformation zone has signs of a high zone. In addition, the shape of the caliber imposes its own imprint on the flow of the metal. It leads to the fact that in reality the deformation zone is much more complicated than it is represented. Therefore, a complex variation of the velocity field is formed during rolling along the length of the deformation zone consequently; a complex stress field is formed. The situation is even more complicated when trying to account for the influence of temperature fields on the metal flow and stress state. The studies were carried out for the modes and deformation schemes existing in production line. The finite element method for approximation of metal flow velocity fields and the variation principle of continuum mechanics were used as a mathematical apparatus. The occurrence of the zone of tensile transverse stresses is shown in the part of the strip under the horizontal contact surface. The reason for the occurrence of this zone is that when the length is reduced of a part of the strip heavily crimp by sides of the caliber, it tends to widen. Naturally, metal particles tend to flow not towards the vertical axis of symmetry of the caliber, but in the opposite direction. In addition, the central part of the strip tends to broaden itself. This leads to compressive transverse stresses at the side parts and tensile stresses at the contact center part. It is shown that from the point of view of defect formation, the most severe stress state pattern arises in places corresponding to the horizontal part of the contact surface of the strip after the strip leaves the rolls and the zone of the lateral surface located slightly below the corners of the workpiece.


Keywords


temperature field; stress; caliber; defect

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References


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DOI: https://doi.org/10.31319/2519-2884.tm.2020.3

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Copyright (c) 2020 S. Yershov, Wu. Kaiming

ISSN (print) 2519-2884

ISSN (online) 2617-8389