Kawasaki Steel Corporation

Toshio Imae

Hideyuki Nikaido

Katsuhiro Takebayashi

Kunio Isobe

Yoshikiyo Tamai

Hiromu Oka

Koichi Uemura

Method of continuously hot rolling steel pieces

A method for continuously hot-rolling steel pieces, includes butt-joining the rear end of the preceding steel piece and the leading end of the succeeding steel piece, then finish-rolling the butt-joined steel pieces by supplying a continuous hot rolling facility provided with a plurality of stands having a bending function of a work roll. The method involves estimating the variation of the rolling force occurring during rolling the joint of the steel pieces at the non-stationary zone caused by said joint, calculating the changing bending force of the work roll during rolling the joint of the steel pieces from the estimated variation of the rolling force, and determining the pattern for changing the bending force taking account of said changing force, and rolling the joint of the steel pieces by regulating the bending force in response to said pattern over at least one stand, while tracking down the joint of the steel piece immediately after joining.

Hot-rolling method of steel piece joint during continuous hot-rolling

A mandrel mill for rolling seamless steel tubes includes a plurality of roll stands each having a pair of rolls defining a roll groove therebetween, an axis of the rolls of each roll stand being orthogonal to the axis of the rolls of the adjacent roll stands. The mandrel mill further includes a mandrel bar disposed in the roll grooves configured by the roll stands. The ratio between the radius of curvature of a groove bottom of the groove and a distance between the groove bottom of the roll groove of the first stand ranges from 0.46 to 0.54, and that of the second stand ranges from 0.48 to 0.52.

Method of producing seamless steel tube by using mandrel mill

A mandrel mill for rolling a tubing in a pass between a mandrel bar and a plurality of serially arranged roll stands. Each roll stand has a plurality of pairs of grooved rolls whose grooves are paired to define a part of the pass. The grooves of the rolls of a first roll stand define a hole having a circumference of not more than 1.12 times the outer circumference of a tubing at the exit of the final roll stand. The grooves of the second-stand rolls define a hole having a circumference of not more than 1.06 times that outer circumference, and those of the third-stand rolls define a hole having a circumference of not more than 1.02 times that outer circumference. Thus, the mandrel mill is capable of preventing stripping miss even when the billet is of a high-alloy steel.

Mandrel mill capable of preventing stripping miss

Growing community of inventors

Chiba, Japan

Toshio Imae