Improvement of strip guiding and related effects in cold rolling of high-strength steel grades
The work of BFI and EKO has focused on the investigation of flatness degrading effects, i.e. irregular wear and unwanted roll movement during rolling at the first stand of EKO's tandem cold mill. Different models have been developed by BFI to describe the behaviour of rolling stand 1. A universal tool has been created that can be used not only for static contact analysis but also for dynamic modal analysis for all possible rolling parameters. A first measurement campaign has been carried out by EKO and has concluded that the measured roll-position changes lie in an acceptable range, and no unwanted roll movements exist at the neck area. Subsequently two vibration measurement campaigns with a sum-rate of about 100 kHz revealed an 'unusual' behaviour in form of a measured splitting of the acceleration signals, which may be an indication of self-excited vibrations and 'slipping effects' between the work roll and the backup roll. Different root causes of this phenomenon have been pointed out, and measures recommended to reduce the examined wear effect. Arcelor Research and EKO focused on strip guiding in stand 1. The first step was a benchmark within the Arcelor cold rolling mill to see how strip off-centre (SOC) can be characterised. The next step was modelling. Three approaches were developed: turning moment-based, pseudo static-based and physical equations resolution-based. Pilot mill and industrial trials were performed to evaluate sensitivities and validate models. Finally, some recommendations to decrease strip off-centre were suggested. - Increasing strip tension reduces SOC generation. - Slowing down the strip reduces SOC generation. - Limiting the first stand reduction does not have any effect on SOC (when the EMG controller is on). - Use of the tension differential measurement can also be interesting as it is a good image of SOC.
Bibliographic Reference: EUR 23606 EN (2009), 87 pp. Free of charge
Availability: http://bookshop.europa.eu/is-bin/INTERSHOP.enfinity/WFS/EU-Bookshop-Site/en_GB/-/EUR/ViewPublication-Start?PublicationKey=KINA23606 (Catalogue Number: KI-NA-23606-EN-S)
ISBN: ISBN: 978-92-79-10165-6
Record Number: 200910192 / Last updated on: 2009-02-26
Original language: en
Available languages: en