METHOD FOR ESTIMATING GENERATION AMOUNT OF SCALE LOSS OF BILLET

PURPOSE:To quantitatively predict a scale loss and to improve the control accuracy of the thickness of the hot billet of a blank material for a seamless pipe by estimating the weight of the scale formed on the surface of the billet in accordance with the surface area, weight and in-furnace residence time of the billet. CONSTITUTION:The weight 11 of the billet before heating is measured by a weighing machine 1 and the time 12, 13 when the billet is charged into a heating furnace 2 and is ejected therefrom is measured. The actually measured values 14, 15 of the billet emitted from a mandrel mill 3 are measured by an outside diameter gage 4 and a length gage 5 and the actual value 16 of the product weight is determined by a product weighing machine 6. A scale loss estimating computer 7 is inputted with size data 17 from a host computer and is inputted with the respective measured values mentioned above. The computer computes the in-furnace residence time from the time 12, 13 and estimates the amt. of the scale loss from this in-furnace residence time and weight 11. The computer 7 utilizes the actually measured values 14, 15 and the actual value 16 for adjusting the parameters for estimating the amt. of the scale loss and determines a correction value 18 of the mill set-up by utilizing the estimated scale loss, thereby corrects the mill set-up of the mill 3.