Experimental study for roll gap adjustment due to roll wear in single-stand rolling and multi-stand rolling test

초록

To investigate a correlation between the amount of wear and roll gap (pass height) adjustment, we performed a single-stand reversible pilot groove rolling test as well as rolling test in an actual rod mill. In case of the pilot rolling test, we designed wear contour (profile) and machined it on the original roll groove (i.e., roll groove with no wear) to make the roll groove worn down. For the actual rod mill test, we developed a measuring device which can detect the actual wear profile. To determine the amount of roll gap adiustment, we propose a model for equivalent roll gap decrement which reduces the increased exit cross sectional area due to wear. We applied the proposed model to multi-stand rolling (roughing train of POSCO No. 2 Rod Mill) as well as single-stand reversible rolling. The wear profile of rolls worn down at each stand in mill yard was measured at different roll tonnage. The pilot hot rolling test shows that variation of exit cross sectional area is almost linearly proportional to roll gap change while the roll gap decreases from reference roll gap (6.5mm) to 3.5mm. In an actual rod mill which has consecutive rolling system, relationship between tonnage (total amount of tons that the produced rod weighs) and roll gap change at a stand is dependent on the rolling type (oval-to-round or round-to-oval) together with the cross sectional shape of incoming workpiece.

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