VCR and ASR technology for profile and flatness control in hot strip mills

Abstract

The roll contour pattern and variety of work and backup rolls in service and its effect on profile and flatness control performance in 1 700 mm hot strip mill at Wuhan Iron and Steel (Group) Corporation were tested and analyzed by the developed finite element models of different typical roll contours configurations. A rather smooth local work roll contour near strip edges and an increase in rolled length can be obtained by application of long stroke work roll shifting system with conventional work roll contours that is incapable of the crown control. In comparison with the conventional backup and work roll contours configuration, the crown control range by the roll bending force enhances by 12.79% and the roll gap stiffness increases by 25.26% with the developed asymmetry self-compensating work rolls(ASR) and varying contact backup rolls(VCR). A better strip profile and flatness quality, an increase in coil numbers within the rolling campaign and a significant alleviated effect of severe work roll wear contours on performance of edge drop control are achieved by the application of ASR with crown control and wear control ability in downstream stand F5 and VCR in all stands of 1 700 mm hot strip mill.

Analysis of Spalling in Roughing Mill Backup Rolls of Wide and Thin Strip Hot Rolling Process

“…Therefore, backup roll surface fatigue can be prevented or restrained by modifying ground contour and alleviating roll wear. In order to improve contact stress distribution conditions, a new backup roll contour was developed and successfully applied to the roughing mill of 1580 HSM base on varying contact rolling technology . New roll contour of backup rolls shows in Figure .…”

Comprehensive shape control technology for CSP hot strip mills

“…The two most common contours of backup rolls are the conventional and VCR contours. Characterized by a varying contact length capacity, the VCR contour achieves better application effects than the conventional contour [12] . However, because…”

A New Mill Design for the Production of a Strip with Zero Strip Crown

“…To control the strip profile and flatness, various technologies have been developed in recent decades. As shown in Figure , they may be categorized as follows: 1) Multi‐high mill such as a six‐high mill, cluster mill, or Z‐mill; 2) roll crown control such as pair cross mill (PCM); 3) roll bending control such as a work roll bender and backup roll bender; 4) roll shifting control such as continuously variable crown (CVC) or work roll shifting; and 5) multiple control methods such as a six‐high CVC mill and other combinations of the above methods …”

“…As shown in Figure 1, they may be categorized as follows: [1,2] 1) Multi-high mill such as a six-high mill, cluster mill, or Z-mill [3][4][5][6] ; 2) roll crown control such as pair cross mill (PCM) [7][8][9] ; 3) roll bending control such as a work roll bender and backup roll bender [10] ; 4) roll shifting control such as continuously variable crown (CVC) or work roll shifting [11][12][13] ; and 5) multiple control methods such as a six-high CVC mill and other combinations of the above methods. [14][15][16][17][18][19] A question that may be raised is, "Is it possible to produce a strip with flat strip profile, which means a perfectly rectangular cross section, so as to achieve zero strip crown or zero edge drop, and at the same time, to eliminate the flatness problem once and for all?" Unfortunately, this is very difficult to achieve with conventional mills, even with a sound strategy for mill setup and control.…”