ORIGINAL
DESCRIPTION
MANUFACTURING METHOD AND MANUFACTURING APPARATUS
OF HOT-ROLLED STEEL SHEET
Technical Field
[OOOl] The present invention relates to a manufacturing
method and a manufacturing apparatus of a hot-rolled sheet. It
particularly relates to a manufacturing method and a
manufacturing apparatus of a hot-rolled sheet focusing on
temperature control of a material to be rolled by a finishing
mill.
Background Art
[0002] A hot-rolled steel sheet is manufactured in the
followingway: a slabheatedinaheatingfurnaceis roughlyrolled
in a roughing mill to become a roughly rolled material
(hereinafter sometimes referredtoas a "roughbar"); thereafter,
the rough bar, which has been transported to a finishing mill
by a transporting table, is rolled into a predetermined size in
the finishing mill; then after going through a cooling process
in which it is cooled in predetermined conditions, it is finally
coiled by a coiler.
[0003] Among the hot-rolled steel sheets manufactured in
this manner, a steel sheet for automobiles, structural materials
and the like is required to have excellent mechanical properties
such as strength, workability, and toughness. In order to
enhance these mechanical properties comprehensively, it is

IP We claim:
1. A manufacturing method of a hot-rolled steel sheet wherein
in manufacturing a hot-rolled steel sheet using a heating device_
which heats a material to be rolled, a descaling device disposed
on a more downstream side in a transporting direction of the
material to be rolled than the heating device, a row of finishing
mills disposed on a more downstream side in the transporting
direction of the material to be rolled than the descaling device,
a cooling device disposed in the row of finishing mills, and a
rapid cooling device disposed immediately after the row of
finishing mills, the operations of the heating device, cooling
device and rapid cooling device are controlled, thereby
controlling a temperature Tl of the material to be rolled which
is on an entry side of the row of finishing mills, a temperature
T2 of the material to be rolled which is on an entry side of a
final stand in the row of finishing mills, and a temperature T3
of the material to be rolled which is on an exit side of the rapid
cooling device.
2. The manufacturing method of a hot-rolled steel sheet
according to claim 1, wherein a temperature of the material to
be rolled is increased to 1100°C or more by using the heating
device.
3. The manufacturing method of a hot-rolled steel sheet
according to claim 1 or 2, wherein an induction heating device
and/or a gas burning furnace are included in the heating device.
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