METHOD FOR PIERCE-ROLLING SEAMLESS METALLIC TUBE AND PIERCE-ROLLING APPARATUS

摘要

PROBLEM TO BE SOLVED: To reduce the defective ratio of a hollow stock tube and to improve the yield by predicting the fusing damage of the tip part of a plug based on the measured result of a measuring means of a billet progressing velocity and a measuring means of a piercing time and judging whether the plug can successively be used or not. ;SOLUTION: The billet progressing velosity (v) measured with the billet progressing velocity measuring means 6 and the piercing time (t) measured with the piercing time measuring means 9 are inputted into a calculating means 8. In the calculating means 8, the temp. at the tip part of the plug just after applying the pierce-rolling is obtd. by using a formula and calculating with a finite element method. In the case, the obtd. surface temp. at the tip part of the plug is higher than the m.p. of a surface scale of the plug as a calculation object, the tip part of the plug is fusing-damaged, and the plug is considered to be reached to the service life and a command to exchange into the new one is transferred. In the case the surface temp. at the tip part of the plug is lower than the m.p. of the surface scale of the plug, the temp. at the tip part of the plug is predicted by using the temp. thereof and calculating with the finite element method. Then, the calculating means judges whether the plug can successively be used or not.;COPYRIGHT: (C)1997,JPO