MATHEMATICAL SIMULATION OF BAR ROLLING WITH REFINED FRICTION COEFFICIENT

A new roll pass design has been proposed in order to implement a square 28x28mm cross-section bar and a round 32mm bar into the production programme of the light section mill in ZDB Group a.s. It considers an input semi-product of a 46mm square cross-section which is acquired by rolling on a 3-high mill of the given section mill. The proposed roll pass design enables to acquire the final shape in four passes. The first two passes are identical for both and the proposed roll grooves are rhombic and square groove. The pre-finish and finish passes then depends on the final shape of the rolled bar. When rolling a round bar, we use a pre-finish oval groove and the final composed of a round groove. However, for rolling a bar of a square cross-section, we use a rhombic groove as the pre-finish and a square one as the finish. The mathematical simulation itself used the Tresca friction coefficient 0.25 for calculations simulating rolling in grooves and conditions similar to those in the light section mill in ZDB Group a.s. Also other parameters accurately describing the rolling conditions of the light section mill were taken over from previous works. The simulation was carried out in commercial software FORGE 2008. The simulation verified suitability of the proposed groove shapes. Comparison of the required rolled stock dimensions with the calculated values reveals that there is no need of any modifications of the proposed groove to be successfully implemented into production. Differences in dimensions are rectifiable by closing or opening of the rolls in the individual grooves.