A study of roll gap adjustment due to roll wear in groove rolling: experiment and modelling

초록

In the tandem groove rolling process, when a certain amount of wear on the work roll exists and the roll speed is not changed, the roll gap, i.e. the section height, should be adjusted to keep a mass balance between stands, i.e. multiply the exit cross-sectional area by the roll speed between stands. To investigate the actual relationship between the amount of wear on the work roll and the subsequent exit cross-sectional area variation, the authors designed wear contours and machined them on the original roll groove, i.e. on the roll groove with no wear. They then performed a pilot hot rolling test using a work roll with a worn-down groove and one with a groove with no wear, and measured the exit cross-sectional area of the workpiece while the roll gap changed. To predict the amount of roll gap adjustment that compensates wear, a model for roll gap adjustment is proposed. In the proposed model, the authors introduced the concept of equivalent roll gap adjustment, which reduces the increased exit cross-sectional area owing to wear up to a base exit cross-sectional area of the workpiece. Results reveal that the exit cross-sectional area calculated by the roll gap adjustment model is in good agreement with the exit cross-sectional area measured. It has been found from the pilot hot rolling test that variation in exit cross-sectional area is almost linearly proportional to roll gap change while the roll gap decreases from a datum roll gap to about half of the datum one.

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