Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Reexamination Certificate
2001-04-19
2002-09-17
Tolan, Ed (Department: 3725)
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
C072S011500, C072S203000, C072S365200
Reexamination Certificate
active
06449996
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hot rolling method for metal blocks, and more particularly, relates to a metal block hot rolling method for joining several to several tens of metal blocks, such as sheet bars, slabs, billets, or blooms, and subjecting the metal blocks to continuous rolling.
BACKGROUND ART
In a conventional metal block hot rolling line, metal blocks to be rolled are individually subjected to heating, rough-rolling, and finish-rolling, and are finished as hot-rolled strips having a desired thickness. In such a batch rolling method, however, the line is inevitably stopped due to poor biting of rolled materials. Moreover, the yield is significantly decreased due to odd shapes of the leading end and the tail end of the rolled materials.
For this reason, an endless rolling method has been recently adopted in which the tail end and the leading end of metal blocks to be rolled are coupled (hereinafter referred to as “joined”) in advance of finish-rolling, and the metal blocks are continuously supplied to a hot rolling line so as to be rolled.
In such endless rolling, since the poor biting and the odd shapes described above occur only at the leading end of the first and the tail end of the last of a plurality of joined subsequent metal blocks, such can be greatly reduced. Since the poor biting and odd shapes become more likely to arise as the thickness of the finish-rolled strips decreases, there used to be such problems in the conventional batch rolling method, and the producible thickness of rolled strips used to have a lower limit. In endless rolling, however, a thick metal strip is rolled first, next the thickness of the finish-rolled strip is changed during rolling after the leading end of the thick strip threads through a finish-rolling unit, and then the subsequent thin metal strips are rolled, so it can produce thinner gage rolled products than before.
As a hot rolling system that can perform the above-described endless rolling, for example, Japanese Unexamined Patent Publication No. 7-241601 discloses a hot rolling line in which arranged, in order along the line on the outlet side of a heating furnace
20
, are a rough-rolling unit
22
composed of, for example, three stands R
1
to R
3
, a winding and rewinding device
70
, a leveler
72
, a centering guide
74
, a joining crop shear
30
, a movable joining unit (welder)
40
moving in synchronization with the feeding of metal blocks, a crop shear
24
, a finish-rolling unit
26
composed of, for example, seven stands F
1
to F
7
, and, for example, two coilers
28
for alternately coiling, as shown in FIG.
2
.
Japanese Unexamined Patent Publication No. 7-1007 discloses an example of a movable joining unit, in which plural lifting table rollers
66
to be supplied with balanced oil pressure from hydraulic oil pipes connected uniquely are pressed down by guides
45
A and
45
B mounted on a joining unit
40
and are raised by the balanced oil pressure to the initial metal block supporting height in accordance with the traveling of the joining unit, as shown in
FIG. 3
, thereby preventing the table rollers and the joining unit from colliding with each other.
Japanese Unexamined Patent Publication No. 11-169926 discloses a method in which, in order to prevent operating trouble or defective coils due to inaccurate setting change and delay of setting change, by promptly and accurately changing the settings when endless rolling for joining and rolling a preceding metal block and a succeeding metal block is changed to batch rolling for rolling a preceding metal block and a succeeding metal block without joining, both rolling conditions of endless rolling and conditions of batch rolling are predetermined when slabs are subjected to endless rolling, and operating conditions at each point in a hot rolling line are calculated for both endless rolling and batch rolling.
However, measures to be taken when trouble arises in an actual joining operation in such a continuous hot rolling line have not been hitherto specifically disclosed. If there are no measures to be taken in case of trouble, serious trouble may arise.
In general, materials (a preceding metal block
10
and a succeeding metal block
12
) are pushed upward from below by loopers
16
during finish rolling, as shown in
FIG. 4
, in order to apply tension to the materials between the stands. For example, if the unjoined materials are supplied to the finish-rolling unit
26
with a false determination that the materials have been joined, since the loopers
16
between the stands are keeping the materials in an upward position, as shown in
FIG. 7
, the leading end of the succeeding metal block is flipped up by the looper
16
, is not bitten by the next stand, and jams between the stands. Thereby, the rolling operation cannot be continued, and the operation of the line is stopped.
Similarly, in a case in which although a joint
11
between the tail end
10
B of the preceding metal block and the leading end of the succeeding metal block
12
A is incomplete and has an insufficient strength, as shown in
FIG. 5
, it is subjected to finish rolling with a false determination that the joint is complete, as shown in
FIG. 6
, the joint
11
may be broken by tensile force, the leading end of the succeeding metal block
12
A is flipped up by the looper
16
, is not bitten by the next stand, and jams between the stands, as shown in FIG.
7
. Due to this, the rolling operation cannot be continued, and the operation of the line is stopped. Numeral
14
in
FIG. 6
denotes burrs produced by joining.
There are three basic trouble cases, as follows:
(1) It is impossible to start joining metal blocks.
(2) Joining results in failure due to trouble during the joining operation.
(3) Although a joint is formed, it has low strength and is incomplete.
The present invention has been made to overcome the above-described conventional problems, and an object of the present invention is how to deal with the above three trouble cases.
DISCLOSURE OF INVENTION
This invention solves the above problems by a hot rolling method for metal blocks using a hot rolling system for joining the leading end of a succeeding metal block and the tail end of a preceding metal block on the inlet side of a finish-rolling mill and for finish-rolling the succeeding metal block and the preceding metal block continuously. In this method, it is determined before, during, and after the joining operation whether or not the succeeding metal block can be finish-rolled in succession to the preceding metal block. When it is determined that the succeeding metal block cannot be finish-rolled in succession to the preceding metal block, the joining operation is aborted or a joint is cut, and rolling operations (operations concerned with all the devices placed downstream from a joining unit, such as finish rolling, coiling, and run-out cooling) are performed in downstream devices including the joining unit under the conditions set for batch rolling. FIGS.
37
(
a
) and
37
(
b
) show the positional relationship among a preceding metal block
10
, a succeeding metal block
12
, a subsequent metal block
13
, and a cut joint, when the joining operation is aborted, and when the joint is cut, respectively (Invention 1).
Regarding the succeeding metal block that is not joined or is incompletely joined, if the devices (the joining unit and a treatment unit such as a deburring device) concerned with joining remain in a joining state, the leading end of the succeeding metal block that is not joined or that the incomplete joint resulted in being broken during traveling, after the joining operation is aborted, is at a risk of sticking in the interior of the devices concerned with joining and making it impossible for the leading end of the succeeding metal block to be threaded therethrough. Accordingly, the devices are brought into a state that allows the leading end of the succeeding metal block to be threaded therethrough, and the leading end of the succeeding metal block is then threaded through the devices concerne
Hirabayashi Takeshi
Isoyama Shigeru
Nikaido Hideyuki
Yamasaki Takahiro
Kawasaki Steel Corporation
Oliff & Berridg,e PLC
Tolan Ed
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