U.S. patent application number 16/755077 was filed with the patent office on 2021-12-02 for method for producing hat-shaped steel sheet pile.
This patent application is currently assigned to NIPPON STEEL CORPORATION. The applicant listed for this patent is NIPPON STEEL CORPORATION. Invention is credited to Naoto KATAOKA, Hiroshi YAMASHITA.
Application Number | 20210370369 16/755077 |
Document ID | / |
Family ID | 1000005828246 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210370369 |
Kind Code |
A1 |
YAMASHITA; Hiroshi ; et
al. |
December 2, 2021 |
METHOD FOR PRODUCING HAT-SHAPED STEEL SHEET PILE
Abstract
To suppress a material amount deficiency in arm parts which
occurs at a rough shaping stage to produce a hat-shaped steel sheet
pile product in a good shape when a large-size hat-shaped steel
sheet pile is produced using a raw material in a rectangular
cross-sectional shape (slab). A production method for producing a
hat-shaped steel sheet pile by reducing a rectangular
cross-sectional raw material, includes: edging rolling of
performing reduction in a width direction on the rectangular
cross-sectional raw material; and a first forming rolling of
performing reduction in which a cross section of a material to be
rolled after the edging rolling is formed into a substantially
hat-shaped cross-sectional shape, wherein in the edging rolling,
reduction in which a thickness of end parts in the width direction
of the material to be rolled is increased using an edging caliber
being a restraining caliber having a caliber bottom width T3 larger
than a thickness T1 of the rectangular cross-sectional raw material
to form into a dog-bone shape is performed.
Inventors: |
YAMASHITA; Hiroshi; (Tokyo,
JP) ; KATAOKA; Naoto; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON STEEL CORPORATION |
Tokyo |
|
KR |
|
|
Assignee: |
NIPPON STEEL CORPORATION
Tokyo
JP
|
Family ID: |
1000005828246 |
Appl. No.: |
16/755077 |
Filed: |
August 8, 2019 |
PCT Filed: |
August 8, 2019 |
PCT NO: |
PCT/JP2019/031445 |
371 Date: |
April 9, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21B 2261/046 20130101;
B21B 2205/00 20130101; B21B 1/082 20130101 |
International
Class: |
B21B 1/082 20060101
B21B001/082 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2018 |
JP |
2018-149325 |
Claims
1. A production method for producing a hat-shaped steel sheet pile
by reducing a rectangular cross-sectional raw material, the
production method comprising: edging rolling of performing
reduction in a width direction on the rectangular cross-sectional
raw material; and a first forming rolling of performing reduction
in which a cross section of a material to be rolled after the
edging rolling is formed into a substantially hat-shaped
cross-sectional shape, wherein in the edging rolling, reduction in
which a thickness of end parts in the width direction of the
material to be rolled is increased using an edging caliber being a
restraining caliber having a caliber bottom width T3 larger than a
thickness T1 of the rectangular cross-sectional raw material to
form into a dog-bone shape is performed.
2. The production method for the hat-shaped steel sheet pile
according to claim 1, wherein in the edging rolling, a range Wa in
which a thickness is increased in the width direction of the
rectangular cross-sectional raw material is set as a range
corresponding to a part or a whole of a width Wb of a portion
corresponding to an arm of the material to be rolled in the first
forming rolling.
3. The production method for the hat-shaped steel sheet pile
according to claim 2, wherein in the edging rolling, the range Wa
in which a thickness is increased in the width direction of the
rectangular cross-sectional raw material is defined by a portion
having a thickness larger than the caliber bottom width T3 of the
edging caliber, and wherein a relation between the range Wa in
which a thickness is increased in the width direction of the
rectangular cross-sectional raw material and the width Wb of the
portion corresponding to the arm of the material to be rolled in
the first forming rolling satisfies Wa.ltoreq.Wb.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2018-149325,
filed in Japan on Aug. 8, 2018, the entire contents of which are
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a production method for
producing a hat-shaped steel sheet pile from a rectangular
cross-sectional raw material.
BACKGROUND ART
[0003] Conventionally, production of a steel sheet pile having
joints at both ends of a hat shape, a U shape, or the like is
performed by a caliber rolling method. Known as a general process
of the caliber rolling method is first heating a raw material to a
predetermined temperature in a heating furnace and sequentially
rolling the raw material by a rough rolling mill, an intermediate
rolling mill, and a finish rolling mill including calibers.
[0004] According to the above-described general caliber rolling
method, a domestically produced steel sheet pile product can be
produced from a raw material in a rectangular cross-section in
status quo. Concretely, for example, a hat-shaped steel sheet pile
product called a 10H product having a cross-section second moment
per 1 m of a wall width of 1.0 (10.sup.4 cm.sup.4/m) and a
hat-shaped steel sheet pile product called a 25H product having a
cross-section second moment per 1 m of a wall width of 2.5
(10.sup.4 cm.sup.4/m) are produced by the conventionally known
general caliber rolling method.
[0005] As a technique of producing a steel sheet pile from a
rectangular cross-sectional raw material or a raw material similar
thereto, various technologies have been conceived. For example,
Patent Document 1 discloses a technique of using a beam blank
material for H-shaped steel to produce a U-shaped steel sheet pile.
Further, for example, Patent Document 2 discloses a technique of
using a rectangular slab as a raw material to form the raw material
into a suitable shape (predetermined width and thickness) with a
box caliber, thereby stabilizing biting at a subsequent process.
Besides, for example, Patent Document 3 discloses a technique of
increasing caliber restraining force by using a rectangular slab as
a raw material and using a deformed box caliber on the raw material
to prevent biting-out, improve a centering property, and the
like.
[0006] Besides, for example, Patent Document 4 discloses a
technique of performing such width reduction as forms a local bulge
on a slab surface in order to form a protruding ridge on a joint of
a steel sheet pile in producing a steel sheet pile having a large
effective width. Further, for example, Patent Document 5 discloses
a technique of suppressing a shape defect at an end part of a
material to be rolled in production of a steel sheet pile.
PRIOR ART DOCUMENT
Patent Document
[0007] [Patent Document 1] Japanese Laid-open Patent Publication
No. H10-192905
[0008] [Patent Document 2] Japanese Laid-open Patent Publication
No. H09-182901
[0009] [Patent Document 3] Japanese Laid-open Patent Publication
No. H10-113707
[0010] [Patent Document 4] Japanese Laid-open Patent Publication
No. 2005-144497
[0011] [Patent Document 5] International Publication Pamphlet No.
WO 2018/139521 A1
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0012] In recent years, accompanying an increase in size of
building structures or use for offshore structures, production of a
hat-shaped steel sheet pile product with a size larger as compared
with conventional ones is required, and in particular, a product
having the full width and height larger as compared with those of
the conventional ones is desired. According to studies of the
present inventors, it has been found that there are various
problems when such a large-size hat-shaped steel sheet pile is
produced from a rectangular cross-sectional raw material
(hereinafter, also called a slab).
[0013] For example, when the large-size hat-shaped steel sheet pile
is produced, the rectangular cross-sectional raw material is also
required to increase its size, and when such a large-size
rectangular cross-sectional raw material is formed, the increase in
size of the raw material causes a problem such as a material amount
deficiency in a part of a cross section of the material to be
rolled, resulting in that there is a possibility of failing to
produce a product in a desired shape. Concretely, an amount of
deformation at a time of bending deformation increases, or a
bending moment arm being a starting point of the bending
deformation extends to make the bending deformation superior to
shear deformation, and thus there is the possibility of causing the
material amount deficiency (metal deficiency) in a part of the
cross section of the material to be rolled. In particular, metal in
end surface parts of the rectangular cross-sectional raw material
is drawn into a middle part thereof, resulting in that there is a
possibility that metal in portions being arm parts of the
hat-shaped steel sheet pile later is deficient.
[0014] Note that the "large-size hat-shaped steel sheet pile" in
this description means, for example, a steel sheet pile product
having dimensions exceeding product dimensions of 900 mm in
effective width and 300 mm in effective height (so-called 25H
product).
[0015] Regarding such problems, because the technique described in
the above Patent Document 1 targets the U-shaped steel sheet pile
having no arm part, and adopts a configuration to deform portions
in each of which a thickness is increased in a dog-bone shape into
flange parts, there is no reference to the metal deficiency in the
portions being the arm parts. Besides, the technique described in
the above Patent Document 1, to begin with, does not adopt a
technical idea such that a steel sheet pile is produced using a raw
material in a rectangular cross-sectional shape (slab), and thus
there is no room for occurrence of the problem such as the material
amount deficiency in the end surface parts of the rectangular
cross-sectional raw material as described above.
[0016] Besides, because the technique described in the above Patent
Document 2 is a technique according to production of a U-shaped
steel sheet pile having no arm part despite performing such shaping
as to match a material to be rolled with a shape of an upper roll
to stabilize the biting in a caliber, there is no reference to the
problem such as the material amount deficiency in the end surface
parts of the rectangular cross-sectional raw material as described
above at a time of the biting, and the problem is not even
suggested.
[0017] Besides, the technique described in the above Patent
Document 3 points at an improvement in rolling stability such as
the improvement in the centering property by increasing restraining
force with caliber contact in the box caliber being surface
contact. However, also in the above Patent Document 3, there is no
reference to the problem such as the material amount deficiency in
the end surface parts of the rectangular cross-sectional raw
material.
[0018] Besides, the technique described in the above Patent
Document 4 discloses the effect of performing such width reduction
as forms the local bulge on the slab surface in order to form the
protruding ridge on the joint of the steel sheet pile in producing
the steel sheet pile having a large effective width. However, the
technique of the above Patent Document 4 aims at forming the
protruding ridge, and there is no reference to the problem such as
the material amount deficiency in the end surface parts of the
rectangular cross-sectional raw material as described above, and
the problem is not even suggested.
[0019] Further, the technique described in the above Patent
Document 5 discloses a technique of suppressing the shape defect of
a bite end part at a rough rolling step in production of the steel
sheet pile to improve productivity. Patent Document 5 refers to
bulging deformation of a slab in edging rolling, and gives an
explanation that the bulging deformation is a factor that
facilitates the shape defect at the bite end part, and naturally,
there is no reference to the problem regarding the material amount
deficiency in the end surface parts of the rectangular
cross-sectional raw material and means for solving the problem.
[0020] In view of the above circumstance, an object of the present
invention is to provide a technique which makes it possible to
suppress a material amount deficiency in arm parts which occurs at
a rough shaping stage to produce a hat-shaped steel sheet pile
product in a good shape when a large-size hat-shaped steel sheet
pile is produced using a raw material in a rectangular
cross-sectional shape (slab).
Means for Solving the Problems
[0021] To achieve the above object, according to the present
invention, there is provided a production method for producing a
hat-shaped steel sheet pile by reducing a rectangular
cross-sectional raw material, the production method including:
edging rolling of performing reduction in a width direction on the
rectangular cross-sectional raw material; and a first forming
rolling of performing reduction in which a cross section of a
material to be rolled after the edging rolling is formed into a
substantially hat-shaped cross-sectional shape, wherein in the
edging rolling, reduction in which a thickness of end parts in the
width direction of the material to be rolled is increased using an
edging caliber being a restraining caliber having a caliber bottom
width T3 larger than a thickness T1 of the rectangular
cross-sectional raw material to form into a dog-bone shape is
performed.
[0022] In the edging rolling, a range Wa in which a thickness is
increased in the width direction of the rectangular cross-sectional
raw material may be set as a range corresponding to a part or a
whole of a width Wb of a portion corresponding to an arm of the
material to be rolled in the first forming rolling.
[0023] In the edging rolling, the range Wa in which a thickness is
increased in the width direction of the rectangular cross-sectional
raw material may be defined by a portion having a thickness larger
than the caliber bottom width T3 of the edging caliber, and a
relation between the range Wa in which a thickness is increased in
the width direction of the rectangular cross-sectional raw material
and the width Wb of the portion corresponding to the arm of the
material to be rolled in the first forming rolling may satisfy
Wa.ltoreq.Wb.
Effect of the Invention
[0024] According to the present invention, it is possible to
suppress a material amount deficiency in arm parts which occurs at
a rough shaping stage to produce a hat-shaped steel sheet pile
product in a good shape when a large-size hat-shaped steel sheet
pile is produced using a raw material in a rectangular
cross-sectional shape (slab).
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 A schematic explanatory view of a rolling line
according to an embodiment of the present invention.
[0026] FIG. 2 A schematic explanatory view of the caliber shape of
a first caliber.
[0027] FIG. 3 A schematic explanatory view of the caliber shape of
a second caliber.
[0028] FIG. 4 A schematic explanatory view of the caliber shape of
a third caliber.
[0029] FIG. 5 A schematic explanatory view of the caliber shape of
a fourth caliber.
[0030] FIG. 6 A schematic explanatory view of the caliber shape of
a fifth caliber.
[0031] FIG. 7 A schematic explanatory view of the caliber shape of
a sixth caliber.
[0032] FIG. 8 A schematic explanatory view illustrating a depressed
height H with respect to a raw material and a bending deformation
moment arm L in the second caliber (first forming caliber).
[0033] FIG. 9 Schematic explanatory views illustrating conditions
of reduction of the raw material in the second caliber (first
forming caliber).
[0034] FIG. 10 Partially enlarged views of FIG. 9.
[0035] FIG. 11 A chart obtained by converting changes of a full
width of upper surface t1 and a full width maximum t2 of the raw
material into numerals by FEM analysis when rolling and shaping of
the raw material in the second caliber (first forming caliber) is
performed in a plurality of passes.
[0036] FIG. 12 Schematic views when edging rolling is performed on
the raw material to increase a thickness of end parts in a width
direction.
[0037] FIG. 13 Schematic explanatory views comparing a cross
section in the rolling and shaping in the second caliber (first
forming caliber) when the thickness of the end part in the width
direction of the raw material in the edging rolling according to
the present invention is increased, and, a cross section in the
rolling and shaping in the second caliber (first forming caliber)
when the raw material has a conventional rectangular cross-section
as it is.
[0038] FIG. 14 A schematic view comparing cross-sectional shapes of
materials to be rolled at a time of completion of the rolling and
shaping in the second caliber (first forming caliber).
[0039] FIG. 15 A chart obtained by converting changes of full
widths of upper surfaces t1 and full width maximums t2 of raw
materials into numerals by FEM analysis when the rolling and
shaping of the raw materials in the second caliber K2 (first
forming caliber) is performed in a plurality of passes after the
edging rolling is performed on slabs each having a width larger
than a width of the second caliber (first forming caliber) to
increase a thickness of end parts in a width direction of the raw
material.
[0040] FIG. 16 An explanatory view regarding biting-out.
Embodiments for Carrying Out the Invention
[0041] Hereinafter, an embodiment of the present invention will be
explained referring to the drawings. Note that, in this description
and the drawings, the same codes are given to components having
substantially the same functional configurations to omit duplicated
explanation. Note that the explanation will be made illustrating a
case of rolling and shaping a hat-shaped steel sheet pile in an
upward open state (so-called U-shaped posture) regarding production
of a steel sheet pile product in this embodiment.
[0042] Besides, in this embodiment, a material having a rectangular
cross-section (so-called slab) is called a raw material B and a
material to be rolled made by reducing the raw material B into a
substantially hat-shaped cross-sectional shape is called a material
to be rolled A for convenience of explanation. More specifically,
steel materials in the substantially hat-shaped cross-sectional
shape to be passed on a rolling line S are generically called a
material to be rolled A, and portions of the material to be rolled
A are described by different names mentioned below. Here, in this
description, in the raw material B in the rectangular
cross-section, a long side direction of the rectangular
cross-section is set as a width direction, and a short side
direction thereof is set as a thickness direction. Besides, the
material to be rolled A is composed of a web corresponding part 3
corresponding to a web of a hat-shaped steel sheet pile product,
flange corresponding parts 4, 5 connected to both end parts of the
web corresponding part 3 respectively, arm corresponding parts 6, 7
formed at tip ends of the flange corresponding parts 4, 5
respectively, and joint corresponding parts 8, 9 formed at tip ends
of the arm corresponding parts 6, 7.
[0043] (Outline of Production Line)
[0044] FIG. 1 is an explanatory view of the rolling line S for
producing the hat-shaped steel sheet pile being a rolling facility
according to the embodiment of the present invention, and rolling
mills provided on the rolling line S. As illustrated in FIG. 1, on
the rolling line S, a rough rolling mill (BD) 11, an intermediate
rolling mill (R) 12, and a finish rolling mill (F) 14 are arranged
in order. The rolling line S is composed of a plurality of lines S1
to S3, in which the line S1 and the line S2 are adjacent to each
other and the line S2 and the line S3 are adjacent to each other.
The lines S1 to S3 are coupled in series to partially overlap each
other, and configured such that the material to be rolled A is
translated from S1 to S2 or S2 to S3 in a width direction thereof
to thereby proceed on the rolling line S.
[0045] Further, as illustrated in FIG. 1, the rough rolling mill 11
is arranged on the line S1, the intermediate rolling mill 12 is
arranged on the line S2, and the finish rolling mill 14 is arranged
on the third line S3. The lines S1 to S3 are configured to be
capable of performing rolling with different materials to be rolled
A placed thereon respectively, and to be capable of performing
rolling of a plurality of materials to be rolled A simultaneously
in parallel on the rolling line S.
[0046] On the rolling line S illustrated in FIG. 1, a raw material
having a rectangular cross-sectional shape (the raw material B, the
later material to be rolled A) heated in a not-illustrated heating
furnace is sequentially rolled in the rough rolling mill 11 to the
finish rolling mill 14 to form into a hat-shaped steel sheet pile
being a final product. In other words, a rough rolling step, an
intermediate rolling step, and a finish rolling step are performed
in this order on the raw material B (the material to be rolled A)
to thereby produce a final product.
[0047] (Outline of Each Caliber Configuration)
[0048] Hereinafter, configurations of calibers engraved in the
rough rolling mill 11, the intermediate rolling mill 12, and the
finish rolling mill 14 arranged on the rolling line S (hereinafter,
a plurality of rolling mills are also sometimes described in an
abbreviation manner such as the rough rolling mill 11 to the finish
rolling mill 14) will be briefly explained referring to the
drawings in order from the upstream of the rolling line S. Note
that since the above-described rough rolling mill 11, intermediate
rolling mill 12, and finish rolling mill 14 are conventionally
generally used facilities excluding detailed shapes and
configurations of the calibers, attention is focused on explanation
of the configurations of the calibers but explanation of the
detailed facility configurations and so on of the rolling mills is
omitted in the following explanation in this description.
[0049] Further, calibers explained below referring to FIG. 2 to
FIG. 7 are engraved in the rolling mills of the rough rolling mill
11 to the finish rolling mill 14, and which rolling mill each of
the calibers explained below is engraved in can be appropriately
changed usually depending on the conditions such as a facility
status, product dimensions, and so on in consideration of the
productivity (efficiency and yields) and workability. Hence, the
calibers are called a first caliber K1 to a sixth caliber K6 in
this embodiment, and the calibers will be explained as those which
may be engraved in order from the upstream side of the rolling line
S. Note that the shapes of the raw material B and the material to
be rolled A which are to be reduced and shaped in the calibers are
illustrated by a one-dotted chain line for reference in FIG. 3 to
FIG. 9.
[0050] However, the configurations of the first caliber K1 to the
sixth caliber K6 according to this embodiment explained below are
not limited to the illustrated forms, but, for example, the
increased/decreased arrangement of correction calibers for various
calibers can be appropriately changed according to the conditions
such as a facility status, product dimensions, and so on. Note that
in the first caliber K1 to the sixth caliber K6 explained below,
rolling and shaping of the material to be rolled is desired to be
the shaping in one pass for each of the calibers, but, particularly
at the rough rolling step, due to constraint of a biting property
and a load characteristic, may be performed in reverse rolling
(reversing rolling) in a plurality of passes, and the number of
passes can be arbitrarily set according to characteristics of the
rolling mills, or the like.
[0051] FIG. 2 is a schematic explanatory view of the caliber shape
of the first caliber K1. As illustrated in FIG. 2, the first
caliber K1 is a box caliber composed of an upper caliber roll 20a
and a lower caliber roll 20b, and caliber bottoms of the box
caliber are in predetermined tapered shapes. The first caliber K1
imparts the tapered shapes to short side parts at end parts in the
width direction of the raw material B in a rectangular
cross-sectional shape and performs light reduction (so-called
edging rolling) in the width direction in a state where the
not-illustrated raw material B in a rectangular cross-sectional
shape is made to stand up (a state of setting the width direction
of a steel sheet pile in the vertical direction) in order to make a
uniform width dimension in the longitudinal direction. The light
reduction here is performed at a reduction amount of the degree to
which dimension variations of the raw material B during casting, or
the like are corrected. Note that the reason why the tapered shapes
are imparted to the end parts in the width direction of the raw
material B in a rectangular cross-sectional shape is to cause the
raw material B to preferably bites into the caliber shape of the
later-described second caliber K2, and to stably perform desired
reduction. In other words, the "tapered shape" here means such a
shape of a caliber bottom surface as can impart a gentle-slop shape
to the end parts in the width direction of the not-illustrated raw
material B through the light reduction. The first caliber K1
illustrated in FIG. 2 is a caliber that performs so-called edging
rolling, and the first caliber K1 is called an "edging
caliber".
[0052] Besides, FIG. 3 is a schematic explanatory view of the
caliber shape of the second caliber K2. As illustrated in FIG. 3,
the second caliber K2 is composed of an upper caliber roll 30a as a
projection roll and a lower caliber roll 30b as a groove roll. The
second caliber K2 performs reduction on the whole raw material B
(the later material to be rolled A) in a rectangular
cross-sectional shape subjected to the edging rolling in the above
first caliber K1. Here, the raw material B is in a state of being
made to stand up in the reduction in the above first caliber K1,
and the raw material B is thereafter rotated 90.degree. or
270.degree. and subjected to reduction in the second caliber K2 in
a state where the width direction of the raw material B is set in
the horizontal direction (a state of setting the width direction of
the steel sheet pile in the horizontal direction), whereby rolling
and shaping is performed to form a cross section from the
rectangular cross-sectional shape into the substantially hat-shaped
cross-sectional shape. Note that in this description, the second
caliber K2 is also called a "first forming caliber" which performs
a first forming rolling. The substantially hat-shaped
cross-sectional shape here means a cross-sectional shape made by
performing reduction to such a degree that the raw material B has
clear boundaries of a portion corresponding to a web (web
corresponding part 3), portions corresponding to flanges (flange
corresponding parts 4, 5), and portions corresponding to arms (arm
corresponding parts 6, 7), and does not always mean the
cross-sectional shape shaped up to fine shapes such as joint shapes
and so on.
[0053] The upper caliber roll 30a is composed of a web facing part
32 facing the upper surface of the web corresponding part 3 of the
raw material B, flange facing parts 34, 35 facing the upper
surfaces of the flange corresponding parts 4, 5, and arm facing
parts 37, 38 facing the upper surfaces of the arm corresponding
parts 6, 7.
[0054] On the other hand, the lower caliber roll 30b is composed of
a web facing part 42 facing the lower surface of the web
corresponding part 3 of the raw material B, flange facing parts 44,
45 facing the lower surfaces of the flange corresponding parts 4,
5, and arm facing parts 47, 48 facing the lower surfaces of the arm
corresponding parts 6, 7.
[0055] Further, FIG. 4 is a schematic explanatory view of the
caliber shape of the third caliber K3. As illustrated in FIG. 4,
the third caliber K3 is composed of an upper caliber roll 50a as a
projection roll and a lower caliber roll 50b as a groove roll. The
third caliber K3 performs further reduction on the material to be
rolled A subjected to the shaping in the second caliber K2 to
roughly form the joint shapes together, and performs, on the whole
material to be rolled A, reduction to form the cross-sectional
shape from the substantially hat-shaped cross-section shape into
the substantially hat-shaped cross-sectional shape formed with
joint parts. In this description, the third caliber K3 is also
called a "second forming caliber" which performs a second forming
rolling.
[0056] The upper caliber roll 50a is composed of a web facing part
52 facing the upper surface of the web corresponding part 3 of the
material to be rolled A, flange facing parts 54, 55 facing the
upper surfaces of the flange corresponding parts 4, 5, and arm
facing parts 57, 58 facing the upper surfaces of the arm
corresponding parts 6, 7.
[0057] Further, the lower caliber roll 50b is composed of a web
facing part 62 facing the lower surface of the web corresponding
part 3 of the material to be rolled A, flange facing parts 64, 65
facing the lower surfaces of the flange corresponding parts 4, 5,
and arm facing parts 67, 68 facing the lower surfaces of the arm
corresponding parts 6, 7.
[0058] FIG. 5 is a schematic explanatory view of the caliber shape
of the fourth caliber K4. As illustrated in FIG. 5, the fourth
caliber K4 is composed of an upper caliber roll 70a as a projection
roll and a lower caliber roll 70b as a groove roll. The fourth
caliber K4 performs further forming of the joint shapes and
performs thickness reduction and forming (thickness drawing
rolling) on the whole material to be rolled A, which is formed into
a shape closer to the hat-shaped steel sheet pile product.
[0059] FIG. 6 is a schematic explanatory view of the caliber shape
of the fifth caliber K5. As illustrated in FIG. 6, the fifth
caliber K5 is composed of an upper caliber roll 100a as a
projection roll and a lower caliber roll 100b as a groove roll. The
fifth caliber K5 reduces a plate thickness to a thickness
corresponding to that of a final product and performs rolling which
decides a substantial plate thickness of the product. Besides, also
regarding shapes of joint corresponding parts 8, 9 (hereinafter,
joint shapes), rolling which decides a plate thickness of the joint
is performed, and this almost decides a final product shape
including the joint shapes. In more detail, the fifth caliber K5
performs the plate-thickness decision on the joint shapes, and the
later-described sixth caliber K6 performs bending forming of the
joint corresponding parts 8, 9. Note that the fifth caliber K5 is
smaller in thickness reduction amount than the fourth caliber K4
which actively performs the thickness reduction of the whole
material to be rolled A.
[0060] FIG. 7 is a schematic explanatory view of the caliber shape
of the sixth caliber K6. As illustrated in FIG. 7, the sixth
caliber K6 is composed of an upper caliber roll 110a as a
projection roll and a lower caliber roll 110b as a groove roll, and
the sixth caliber K6 performs bending forming of the joint
corresponding parts 8, 9 of the material to be rolled A and shaping
of the whole material to be rolled A by light reduction rolling.
Specifically, joint forming of bending the whole joint
corresponding parts 8, 9 into the joint shapes of the product is
performed. Thus, the sixth caliber K6 forms the material to be
rolled A up to the shape of the hat-shaped steel sheet pile
product.
[0061] The caliber shapes and functions of the first caliber K1 to
the sixth caliber K6 have been explained above referring to FIG. 2
to FIG. 7. As described above, the caliber rolling method for the
hat-shaped steel sheet pile includes the rough rolling step, the
intermediate rolling step, and the finish rolling step and, for
example, the rough rolling step and the intermediate rolling step
are performed in sequence in the calibers of the first caliber K1
to the fifth caliber K5, and the finish rolling step is performed
in the sixth caliber K6. Here, all of the caliber shapes of the
fourth caliber K4 to the sixth caliber K6 are in the substantially
hat-shaped cross-sectional shape, and engraved in shapes closer to
the product shape as they are calibers at later stages. In other
words, the shape of the sixth caliber K6 where the finish rolling
being the final step is performed is in the hat-shaped steel sheet
pile product shape.
[0062] Note that the rough rolling mill (BD) 11, the intermediate
rolling mill (R) 12, and the finish rolling mill (F) 14 are
arranged in order on the rolling line S in this embodiment, and the
above-described first caliber K1 to sixth caliber K6 are
dispersedly engraved in an arbitrary configuration in the rolling
mills. One example can be a configuration in which the first
caliber K1 to the third caliber K3 are engraved in the rough
rolling mill 11, the fourth caliber K4 and the fifth caliber K5 are
engraved in the intermediate rolling mill 12, and the sixth caliber
K6 is engraved in the finish rolling mill 14. However, the caliber
configuration in the present invention is not limited to such a
configuration.
[0063] (Problems at Rough Rolling Step)
[0064] The present inventors found problems as explained below
regarding the rolling and shaping in the first forming caliber
corresponding to the second caliber K2 in this embodiment at the
rough rolling step in producing a hat-shaped steel sheet pile
product having a larger size than conventional ones from the raw
material B in the rectangular cross-sectional shape, and earnestly
carried out studies on a technique for solving the problems.
[0065] Note that conventionally produced hat-shaped steel sheet
pile products were, for example, each a product equal to or less
than a size of a product called a so-called 25H product such as 900
mm in effective width.times.300 mm in effective height. In contrast
with this, the present inventors point at production of a product
with such a size as exceeds 900 mm in effective width.times.300 mm
in effective height as the large-size hat-shaped steel sheet pile
product. In producing the product with such a size, the problems as
explained below are very remarkable, and important as problems that
need to be solved.
[0066] First, because a height of a final product extends with an
increase in size of the product, a rolling height in the second
caliber K2 (first forming caliber) extends. In other words, in the
rolling and shaping in the second caliber K2 (first forming
caliber), a depressed height H with respect to the raw material B
extends to increase a bending deformation amount of the raw
material B.
[0067] Second, because a width of the final product extends with
the increase in size of the product, a bending deformation moment
arm L in the rolling and shaping in the second caliber K2 (first
forming caliber) extends. Therefore, deformation in the rolling and
shaping becomes deformation such that bending deformation is
superior to shear deformation.
[0068] FIG. 8 is a schematic explanatory view illustrating a
depressed height H with respect to the raw material B and a bending
deformation moment arm L in the second caliber K2 (first forming
caliber). The depressed height H illustrated in FIG. 8 indicates an
amount to be reduced in a case of performing the rolling and
shaping which forms a shape of the raw material B into a
substantially hat-shaped cross-sectional shape in the second
caliber K2 (first forming caliber), and there is a tendency that
the larger a height of a final hat-shaped steel sheet pile product
is, the more the depressed height H also extends.
[0069] Further, the bending deformation moment arm L illustrated in
FIG. 8 is a moment arm in performing bending deformation in order
to form a flange corresponding portion when a cross-sectional shape
of the raw material B is formed from the rectangular
cross-sectional shape into the substantially hat-shaped
cross-sectional shape in the second caliber K2 (first forming
caliber), and there is a tendency that the larger a width of the
final hat-shaped steel sheet pile product is, the more the bending
deformation moment arm L also extends.
[0070] FIG. 9 are schematic explanatory views illustrating
conditions of reduction of the raw material B in the second caliber
K2 (first forming caliber), and the conditions of reduction are
illustrated in stages of (a) to (c). Further, the cross section of
the raw material B is illustrated by a one-dotted chain line, and
FIGS. 10(a) to (c) illustrate partially enlarged views of FIG. 9
(dotted line portions in FIG. 9). As illustrated in FIG. 9, the
rolling and shaping in the second caliber K2 (first forming
caliber) can be indicated by being divided mainly into three
stages. As illustrated in FIGS. 9(a) to (b), at a first stage,
forming is performed in a state of bringing only a circumferential
surface of a maximum diameter of the upper caliber roll 30a into
contact with the raw material B, and the first stage is a stage
preceding a start of thickness reduction of portions B1
corresponding to flanges of the raw material. At the first stage,
the raw material B is not subjected to the thickness reduction,
namely, the raw material B is only formed to be bent.
[0071] As illustrated in FIG. 9(b), a second stage indicates a
condition from the start of the thickness reduction of the portions
B1 corresponding to the flanges of the raw material to a stage
preceding a start of thickness reduction of portions B2
corresponding to the arms of the raw material and a portion B3
corresponding to the web of the raw material, after the end of the
above-described first stage. At the second stage, before the
reduction of the portions B2 corresponding to the arms, the
thickness reduction of only the portions B1 corresponding to the
flanges of the raw material is started.
[0072] As illustrated in FIG. 9(c), a third stage indicates a stage
of performing the thickness reduction of the whole raw material B
(B1 to B3) (reduction of the whole surface) after the end of the
above-described second stage.
[0073] In the rolling and shaping of being performed by being
divided into the above-described first stage to third stage, the
first stage is configured to only form the raw material B to be
bent without being subjected to the thickness reduction, and at
that time, to bring the circumferential surface of the upper
caliber roll 30a into contact with the vicinity of the middle part
of the raw material B (the portion B3 corresponding to the web) and
not to bring the circumferential surface of the upper caliber roll
30a into contact with the other upper surface portion of the raw
material B. In other words, at the first stage, the whole raw
material B is formed in an unrestrained state, and the upper
surface of the vicinity of the middle part thereof is pressed
downward by the upper caliber roll 30a, to thus cause a drawing
effect from the portions B2 corresponding to the arms of the raw
material toward the portions B1 corresponding to the flanges and
the portion B3 corresponding to the web. This decreases a material
amount of the portions B2 corresponding to the arms of the raw
material, resulting in that a phenomenon such as a material amount
deficiency in the sections B2 is seen. This causes gap parts 121,
122 in the vicinity of both end parts of the second caliber K2
(first forming caliber) as illustrated in FIG. 9(b). Such gap parts
121, 122 also remain at the third stage illustrated in FIG. 9(c),
and it is found that rolling and shaping at a later stage is
adversely affected.
[0074] FIG. 11(a) is a chart obtained by converting changes of a
full width of upper surface t1 and a full width maximum t2 of the
raw material B into numerals by FEM analysis when rolling and
shaping of the raw material B in the second caliber 2K (first
forming caliber) is performed in a plurality of passes. Further,
FIG. 11(b) is an explanatory view of "full width of upper surface",
"full width maximum", and "web gap". Note that the chart
illustrated in FIG. 11(a) is the one when the rolling and shaping
in the second caliber K2 (first forming caliber) is performed in a
pass schedule described in Table 1 presented below by using a slab
raw material with cross-sectional dimensions of 1930 mm.times.300
mm. Here, as illustrated in FIG. 11(b), the "full width of upper
surface t1" of the raw material B in the rolling and shaping is
defined as a value of a full width decided in contact with the
upper caliber roll 30a, and the "full width maximum t2" is defined
as a value of a full width decided in contact with the lower
caliber roll 30b.
TABLE-US-00001 TABLE 1 PASS WEB GAP 1 584 2 509 3 434 4 359 5 336 6
314 7 291 8 269 9 246 10 224 11 201 12 179 13 161 14 144 15 128 16
111
[0075] As a premise, it is said to be in an ideal deformed state
that the numeric values of the full width of upper surface t1 and
the full width maximum t2 have no difference and always coincide
with each other. However, as illustrated in FIG. 11(a), with
progress of the rolling and shaping passes in the second caliber K2
(first forming caliber), in particular, the full width of upper
surface t1 varies greatly, and for example, a thickness deficiency
occurs in a range of the degree of about 50 mm from an end part in
the final pass (the 16th pass in Table 1). This is attributed to
the fact that the material amount of the portions B2 corresponding
to the arms decreases accompanying the rolling and shaping
(forming) to cause the material amount deficiency as described
above referring to FIGS. 9, 10.
[0076] Further, in the pass schedule presented in Table 1, in
particular, a variation range (decrease range) is large during the
passes up to a start of the thickness reduction of the portions B1
corresponding to the flanges (the first to fourth passes). This is
because the first pass to the fourth pass are at the stage where
the raw material B is not subjected to the thickness reduction but
subjected to the bending deformation in addition to the shear
deformation.
[0077] On the other hand, in an eighth and subsequent passes of the
pass schedule presented in Table 1, widening occurs due to the
thickness reduction of the portions B2 corresponding to the arms of
the raw material, and the full width of upper surface t1 turns to
an increase, but the rolling and shaping in the second caliber K2
(first forming caliber) is ended without completely eliminating the
material amount deficiency also in the final pass.
[0078] (Edging Rolling for Solving Problems and Operation and
Effect Thereof)
[0079] As explained above referring to FIGS. 9 to 11, in producing
the large-size hat-shaped steel sheet pile product, there occurs
the material amount deficiency of the portions B2 corresponding to
the arms in the rolling and shaping in the second caliber K2 (first
forming caliber), and as a result, there is a possibility of
causing a shape defect of a product accompanying the material
amount deficiency in arm parts of the product.
[0080] Thus, the present inventors earnestly carried out studies,
and obtained findings that can eliminate the material amount
deficiency of the portions B2 corresponding to the arms by rolling
and shaping the raw material B in a dog-bone shape after edging
rolling and shaping in the second caliber K2 (first forming
caliber), after using a rectangular cross-sectional raw material
(slab) having a width larger than a caliber width of the second
caliber K2 (first forming caliber) and performing rolling and
shaping under predetermined conditions in the edging caliber (the
first caliber K1 in this embodiment) being at a preceding stage of
the second caliber K2 (first forming caliber). Hereinafter, the
findings will be explained referring to the drawings and so on.
[0081] Note that the "dog-bone shape" in this description means a
state where a thickness of both-side end parts in the width
direction is deformed into a larger shape relative to a middle part
in the width direction as compared with a rectangular
cross-section, and means a rectangular cross-sectional raw
material, what is called, deformed into a double bulging shape.
[0082] FIG. 12 are schematic views when the edging rolling is
performed on the raw material B having a width larger than that of
the second caliber K2 (first forming caliber) to increase the
thickness of end parts in the width direction (upper and lower both
end parts in the drawing) in the edging caliber. FIG. 12(a)
illustrates a cross section of a material to be rolled (raw
material B) in the dog-bone shape, what is called, deformed into a
double bulging shape, and FIG. 12(b) is the one obtained by
enlarging a part of the cross section. Concretely, as shown in the
illustrations, a slab thickness is indicated with T1, and a
restraining caliber such that a width of a caliber bottom surface
(caliber bottom width) T3 is larger than the slab thickness T1
(namely, T1<T3) is used as the edging caliber with respect to
the raw material B having a width larger than a width of the second
caliber K2 (first forming caliber). Then, in the edging caliber, by
performing such edging rolling as makes a maximum thickness of the
end parts in the width direction of the raw material B to be T2, it
is possible to suppress the material amount deficiency of the
portions B2 corresponding to the arms in the second caliber K2
(first forming caliber). Here, as illustrated in FIG. 12(b), the
maximum thickness T2 of the raw material B after the edging rolling
is set to be a value larger than those of both the slab thickness
T1 and the caliber bottom width T3 (T1<T3<T2).
[0083] Besides, in the width direction (vertical direction in FIG.
12) of the raw material B, when a range in which the thickness is
increased more than the slab thickness T1 is defined as Wa, the
material amount deficiency of the portions B2 corresponding to the
arms in the second caliber K2 (first forming caliber) is suppressed
by the edging rolling, while, from the viewpoint of prevention of
metal extrusion (so-called "biting-out") from the caliber due to a
material amount excess, the above-described range Wa is preferably
set as a range corresponding to a part or the whole of a width Wb
(illustrated in FIG. 13) of the portion B2 corresponding to the arm
of the raw material in the second caliber K2 (first forming
caliber). In other words, the relation of Wa.ltoreq.Wb is
preferably satisfied. This is attributed to the fact that, when the
rolling and shaping in the second caliber K2 (first forming
caliber) is considered to be divided into the three stages, it is
found that the drawing effect occurs from the portions B2
corresponding to the arms of the raw material toward the portions
B1 corresponding to the flanges and the portion B3 corresponding to
the web at the first stage, in particular, it is found that the
material amount of the portions B2 corresponding to the arms of the
raw material decreases to cause the phenomenon such as a material
amount deficiency in the sections B2 at the first stage, as
described above referring to FIGS. 9, 10.
[0084] Note that in a case of measuring or defining the above
values such as T1, T2, T3 and the ranges such as Wa, Wb, it is only
necessary to, at each corner part having a predetermined curvature
of a caliber circumferential surface of the first caliber K1 or the
second caliber K2, measure or define the dimensions using, as a
reference, an intersection point when virtual lines are drawn on
both-side portions of the corner part. For example, as illustrated
in FIG. 12(b), in a case of defining the caliber bottom width T3 of
the edging caliber, or in a case of measuring the range Wa to
increase the thickness, it is only necessary to use, as a
reference, P1 being an intersection point of extending virtual
lines on a side surface and a bottom surface of the edging
caliber.
[0085] Here, when such edging rolling as makes a maximum thickness
of the end parts in the width direction to be T2 (>T1) is
performed on the raw material B having the slab thickness of T1 and
having a width larger than that of the second caliber K2 (first
forming caliber), T2 and T1 preferably have a predetermined
relationship. It is desired that the preferable relationship
between T2 and T1 is preferably decided based on changes in the
full width of upper surface t1 and the full width maximum t2 of the
raw material B described later referring to FIG. 15.
[0086] FIG. 13 are schematic explanatory views comparing a cross
section in the rolling and shaping in the second caliber K2 (first
forming caliber) when the thickness of the end part in the width
direction of the raw material in the edging rolling according to
the present invention is increased, and, a cross section in the
rolling and shaping in the second caliber K2 (first forming
caliber) when the raw material has a conventional rectangular
cross-section as it is, (a) is the cross section in application of
the present invention, and (b) is the cross section in application
of the conventional rectangular cross-section. Note that FIG. 13
are the cross sections in each starting the thickness reduction of
the portion B1 corresponding to the flange of the raw material, (a)
and (b) illustrate a state of having the same roll gap, and only a
part of each of the cross sections is enlarged for convenience of
explanation.
[0087] As illustrated in FIG. 13(b), in the rolling and shaping of
the conventional rectangular cross-section in the second caliber K2
(first forming caliber), the reduction of the portion B2
corresponding to the arm is not started at the stage of starting
the reduction of the portion B1 corresponding to the flange. On the
other hand, as illustrated in FIG. 13(a), in the rolling and
shaping in the second caliber K2 (first forming caliber) in the
application of the present invention, the reduction of the portion
B2 corresponding to the arm is started at almost the same timing as
the stage of starting the reduction of the portion B1 corresponding
to the flange, and the full width of upper surface t1 turns to an
increase due to the thickness reduction of the arm in subsequent
deformation.
[0088] FIG. 14 is a schematic view comparing cross-sectional shapes
of the materials to be rolled at a time of completion of the
rolling and shaping in the second caliber K2 (first forming
caliber), a hatching portion indicates the cross section in the
application of the present invention, and a solid line indicated in
a section surrounded by a dotted line indicates a portion deficient
in the material amount in the conventional cross section, and in
particular, the vicinity of the portions B2 corresponding to the
arms of the materials to be rolled is enlarged to be illustrated.
As illustrated in FIG. 14, after applying the present invention and
increasing the thickness of the end part in the width direction of
the raw material in the edging rolling, by performing the rolling
and shaping in the second caliber K2 (first forming caliber), it is
found that the material amount deficiency of the portion B2
corresponding to the arm is suppressed and eliminated (refer to a
dotted-line surrounded portion in FIG. 14).
[0089] Further, FIG. 15 is a chart obtained by converting changes
of full widths of upper surfaces t1 and full width maximums t2 of
raw materials B into numerals by FEM analysis when the rolling and
shaping of the raw materials B in the second caliber K2 (first
forming caliber) is performed in a plurality of passes after
performing the edging rolling on slabs each having a width larger
than a width of the second caliber K2 (first forming caliber) to
increase the thickness of end parts in the width direction of the
raw material. Note that FIG. 15 illustrates graphs each of when the
rolling and shaping in the second caliber K2 (first forming
caliber) is performed after performing the edging rolling on the
slab having a width 100 mm larger than a width of the second
caliber K2 (first forming caliber) (namely, 2030 mm.times.300 mm
raw material), and, when the rolling and shaping in the second
caliber K2 (first forming caliber) is performed after performing
the edging rolling on the slab having a width 50 mm larger than a
width of the second caliber K2 (first forming caliber) (namely,
1980 mm.times.300 mm raw material), and also illustrates graphs
(similar to graphs in FIG. 11) in the case of no application of the
present invention (conventional method) together for reference
purposes. Besides, the pass schedule of the rolling and shaping is
the pass schedule described in the above-described Table 1.
[0090] As illustrated in FIG. 15, it is perceived that when the
rolling and shaping in the second caliber K2 (first forming
caliber) is performed after extending the width of each of the
slabs to be used and increasing the thickness of the portions
corresponding to the arms in bulging by the edging rolling, the
increase in the thickness of the portions corresponding to the arms
brings deformation which promotes drawing of metal to flange sides
in the passes at a preceding stage (for example, the first pass to
the fifth pass), but as described above referring to FIG. 13 and so
on, there is a tendency that a rise (recovery) of the full width of
upper surface t1 in the passes at a later stage (for example, the
sixth and subsequent passes) is remarkable because the reduction
start of the portions corresponding to the arms is accelerated. In
particular, when the rolling and shaping in the second caliber K2
(first forming caliber) is performed after performing the edging
rolling on the slab having a width 100 mm larger than a width of
the second caliber K2 (first forming caliber), it is found that the
full width of upper surface t1 rises up to a value coinciding with
a value of the full width maximum t2 in the final pass, to realize
the recover of the material amount deficiency.
[0091] FIG. 15 describes the schedule in which the rolling and
shaping is performed in the total 16 passes (refer to Table 1), and
an ideal deformed state in the final pass (the 16th pass) is a
deformation such that the full width of upper surface t1 and the
full width maximum t2 coincide with each other (refer to the
hatching portion in FIG. 14).
[0092] When a slab width is too large and a reduction amount in the
edging rolling is too much, metal extrudes from the caliber,
so-call "biting-out" occurs, as in FIG. 16, which has a possibility
of leading to a defect such as a product flaw (refer to a dotted
line portion in FIG. 16). Under the condition that the slab having
a width 100 mm larger than a width of the second caliber K2 (first
forming caliber) illustrated in FIG. 15 is used, the material
amount is excessive because the full width maximum t2< the full
width of upper surface t1 is obtained in the final pass. On the
other hand, under the condition that the slab having a width 50 mm
larger than the width of the second caliber K2 (first forming
caliber) illustrated in FIG. 15 is used, the full width maximum
t2> the full width of upper surface t1 is obtained in the final
pass, resulting in the material amount deficiency. It is found from
the results of the studies as above that a dimension condition of
an appropriate slab for realizing the ideal deformed state is a
condition that a width of the slab is larger than the width of the
second caliber K2 (first forming caliber) by more than 50 mm and
less than 100 mm.
[0093] Note that it is only necessary for the width of the second
caliber K2 (first forming caliber) to be calculated based on
product dimensions (particularly a product width) of the final
hat-shaped steel sheet pile product, for example, to be defined as
a width length obtained by adding a thickness portion of a joint
part and a bent portion of the joint part to the product width.
[0094] As explained above referring to FIG. 12 to FIG. 16, by
adopting the method of performing the rolling and shaping of the
raw material B in the second caliber K2 (first forming caliber)
after performing the edging rolling on the slab having a width
larger than a width of the second caliber K2 (first forming
caliber) to increase the thickness of the end parts in the width
direction of the raw material, there is solved the problem that in
producing the large-size hat-shaped steel sheet pile product, the
material amount deficiency of the portions B2 corresponding to the
arms occurs in the rolling and shaping in the second caliber K2
(first forming caliber), resulting in causing the shape defect of
the product accompanying the material amount deficiency in the arm
parts of the product. In other words, it becomes possible to stably
produce a hat-shaped steel sheet pile product in a good shape.
[0095] In that case, when the thickness of the end parts in the
width direction of the raw material is increased in the edging
rolling, the range Wa in which the thickness is increased is
preferably smaller than the width Wb of the portion B2
corresponding to the arm of the raw material in the second caliber
K2 (first forming caliber). It is found that the material amount
deficiency in the arm parts of the product can be sufficiently
eliminated by satisfying the relation of Wa.ltoreq.Wb.
[0096] One example of the embodiment of the present invention has
been described above, but the present invention is not limited to
the illustrated embodiment. It should be understood that various
changes and modifications are readily apparent to those skilled in
the art within the scope of the spirit as set forth in claims, and
those should also be covered by the technical scope of the present
invention.
[0097] In the above-described embodiment, as the configurations of
the calibers engraved in the rolling mills, there is cited a
configuration in which the first caliber K1 to the third caliber K3
are engraved in the rough rolling mill 11, the fourth caliber K4
and the fifth caliber K5 are engraved in the intermediate rolling
mill 12, and the sixth caliber K6 is engraved in the finish rolling
mill 14, but the engraving of the calibers in the respective
rolling mills in the present invention can be arbitrarily
decided.
INDUSTRIAL APPLICABILITY
[0098] The present invention is applicable to a production method
for producing a hat-shaped steel sheet pile from a rectangular
cross-sectional raw material.
EXPLANATION OF CODES
[0099] 3 . . . web corresponding part
[0100] 4, 5 . . . flange corresponding part
[0101] 6, 7 . . . arm corresponding part
[0102] 8, 9 . . . joint corresponding part
[0103] 11 . . . rough rolling mill
[0104] 12 . . . intermediate rolling mill
[0105] 14 . . . finish rolling mill
[0106] 32, 42 . . . web facing part (of second caliber)
[0107] 34, 35, 44, 45 . . . flange facing part (of second
caliber)
[0108] 37, 38, 47, 48 . . . arm facing part (of second caliber)
[0109] A . . . material to be rolled
[0110] B . . . raw material
[0111] K1 to K6 . . . first caliber to sixth caliber
[0112] S (S1 to S3) . . . rolling line
* * * * *