This application claims priority from Japanese Patent Application No. 2003-286014, filed Aug. 4, 2003, the entire disclosure of which is incorporated herein by reference.
1. Technical Field of the Invention
The present invention relates to an apparatus for manufacturing a band plate that presses edge drop portions at both ends of a plate before rolling, together with a center part of the plate, and leaves edge drops on the plate after rolling.
2. Description of the Related Art
Molten metal for casting is supplied to a pouring basin formed between side dams 53 disposed between both ends of the casting rolls and a top portion of outer peripheries of casting rolls 51, from an opening of a flat-shaped nozzle 52 of a tundish arranged immediately above (top portion of) the two casting rolls 51. Both side dams 53 are disposed to match the width of the slab to be manufactured, and to prevent molten metal from leaking onto the side surfaces of the ends of casting rolls having the same length as the width of the slab.
The continuous casting machine 50 of a double-roll type manufactures a slab with a predetermined approximate width of 1,200 to 2,000 mm. The continuous casting equipment of a double-roll type can operate using simple ancillary equipment in a compact layout compared to other continuous casting apparatus such as caterpillar-type continuous casting equipment.
When a slab material that has been manufactured with double rolls or a single roll is rolled by a rolling mill 56 downstream on the line, the rolling mill is a conventional non-shifting mill, instead of using a rolling mill in which rolls are shifted in the axial direction of the roll. Conventionally, a roll of the rolling mill has a shape of a parabolic or sinusoidal curve, and have diameters larger at the axial center of the roll than at the ends (barrel-shaped rolls). Barrel-shaped rolls are widely used in a conventional rolling mill to compensate for warping of the pressing roll.
However, the aforementioned continuous casting machine 50 of a double-roll type suffers from a heat crown phenomenon at the casting rolls during casting, because of the long casting roll 51. As a result of this heat crown phenomenon, casting conditions vary along the width of the casting roll. In particular, the variation at the width ends of the work roll becomes greater. Therefore, at the position nearer to the width ends of the roll, the distribution of a plate thickness in the lateral (width) direction of a slab varies more largely.
In addition, because side dams 53 are disposed at both ends of the rolls, heat dissipation efficiencies are high at the roll surfaces that are in contact with side dams; along a lateral section of the slab, portions close to the roll width ends are cooled more efficiently than at the center, so the plate thickness changes from the center to the width ends, resulting in a concave or convex shape. As a result, as shown in
The inventors of the present invention have already invented a technique and applied it for a patent. This technique is described in Patent literature 1 correcting the edge drop or up crown described above. Patent literature 1 “Band plate manufacturing apparatus” discloses a continuous casting machine of a double-roll or single-roll type, that continuously casts a slab of a predetermined width with molten metal for casting, supplied from a tundish arranged at an upstream location, and a single finish rolling mill that is disposed downstream of the continuous casting machine, and is provided with a pair of up/down work rolls that can move along the axes thereof in opposite directions. As shown in
[Patent Literature 1]
Japanese Laid-Open Patent publication No. 11503, 2002
As described above, a plate to be rolled by a rolling mill may have a large edge drop. In particular, a strip caster often produces large edge drops, so slabs manufactured therewith must be specially processed.
Furthermore, edge drops produced by a strip caster can often differ at both ends, because molten metal solidifies differently near both side dams. Therefore, a means for controlling edge drops in a way that differs for left and right side portions is required.
Generally, if the edge drops of a raw material is large and the material is rolled so deeply that edge drops are eliminated, the elongation ratio at a center portion, originally free from edge drops, becomes excessively high, resulting in a problem of undulation produced at the center portion. Therefore, as shown typically in
The present invention aims to cope with these requests. That is, an object of the present invention is to provide an apparatus for manufacturing a band plate that can roll respective edge drops together with the center portion, leaving edge drops after rolling, even in a case of large edge drop portions in a plate before rolling and sizes of edge drops that differ between left and right edges of the plate.
According to the present invention, there is provided an apparatus for manufacturing a band plate, comprising a rolling mill that includes: a pair of upper and lower work rolls that roll a slab material having edge drop portions at both ends thereof; and a pair of backup rolls that contact non-rolling side surfaces of the pair of upper and lower work rolls, respectively to prevent the work rolls from being deformed, wherein the work roll comprises a reverse taper portion where a roll diameter gradually increases towards a barrel end portion thereof corresponding to the edge drop portion, the upper and lower work rolls are configured to be shiftable individually in the axial direction thereof, and the backup roll comprises an escape portion whose diameter gradually decreases towards an axial end thereof so as not to contact the reverse taper portion of the work roll, within a shifting range of the work roll.
According to a preferred embodiment of the present invention, the work roll comprises a cylindrical expansion diameter portion outside the reverse taper portion, and the backup roll comprises a cylindrical contraction diameter portion that contacts the expansion diameter portion, outside the escape portion.
Preferably, the apparatus for manufacturing the band plate further comprises a work roll bending mechanism that applies a bending moment to the work roll to finely adjust a crown during rolling.
Preferably, the apparatus for manufacturing the band plate further comprises a strip caster at a downstream side of which the rolling mill is provided.
According to the aforementioned configuration of the present invention, because the work roll is provided with the reverse taper portion, on which roll diameters gradually increase towards the barrel end portion thereof corresponding to the edge drop part, and the upper or lower work roll is composed to be shiftable individually in the axial direction of the roll, even if edge drops at both ends of the slab material differ greatly from each other, the shape of the rolled plate can be maintained under the preferred conditions by separately axially shifting the upper and lower work rolls.
Also, because the backup roll is provided with the escape portion at which roll diameters gradually decrease towards an end of the axis of the roll within the shiftable range of the work roll, so that the backup roll does not come into contact with the reverse taper portion of the work roll, the reverse taper portion of the work roll can be prevented from interfering with the backup roll, so the work roll can be axially shifted with a small resistance.
In addition, the crown can be finely adjusted during rolling, by applying a bending moment to the work roll by means of the work roll bending mechanism etc.
Other objects and advantages of the present invention are revealed as follows, referring to the attached drawings.
Preferred embodiments of the present invention are described below referring to the drawings. In each drawing, common parts and components are identified with the same numbers, while omitting any duplicate descriptions.
The apparatus for manufacturing a band plate of the present invention is preferably provided with a rolling mill 10 arranged downstream from a strip caster. In
The work roll 20, in a pair of upper and lower rolls, is provided with a rolling portion 22 formed in a slim cylinder, and can press a slab material 1 with edge drop portions 2 at both ends thereof. The backup roll 30, in a pair of upper and lower rolls, is shaped to have a backup portion 32 in a small cylinder, and contacts the non-rolling side surface of the work roll 20 in the pair, and can protect the work roll 20 from being bent and deformed. The backup roll 30 is supported by bearings, illustrated as triangles in
In
The upper and lower work rolls 20, as a pair, preferably has the same shape and, as shown in
Both upper and lower work rolls 20 are configured to be shiftable individually in the respective axial directions by means of a roll shifting device, which is not illustrated but is shown by the horizontal arrow marks.
Furthermore, as shown by the arrow marks in the vertical direction of the roll, a work roll bending mechanism (not illustrated) is incorporated at both ends of the work roll 20, whereby the crown of the slab material 1 is finely adjusted during rolling by applying the bending moment.
In
A pair of upper and lower backup rolls 30 preferably have the same shape. As shown in
In this example, the expansion diameter portion 26 of the work roll and the contraction diameter portion 36 of the backup roll are arranged so as not to come into contact with each other. In other words, the expansion diameter portion 26 and the contraction diameter portion 36 are not functionally indispensable, so they can be omitted from the configuration.
In
Rolling conditions of the slab center portion are adjusted by a rolling load applied by backup rolls 30. Conditions for rolling edge drop portions 2 are adjusted by the shifting stroke of the work rolls, as well as the rolling load. In addition, the work roll bending mechanism imposes a bending moment that finely adjusts the crown of slab material 1 during rolling.
In this embodiment, the expansion diameter portion 26 of the work roll and the contraction diameter portion 36 of the backup roll are in contact with each other. Therefore, in this example, expansion and contraction diameter portions 26, 36 functions, differently from the first embodiment. Other configuration details are the same as those in the first embodiment.
In
In
According to the configuration of the present invention, as described above, because the work roll 20 is provided with a reverse taper portion 24 at which diameters gradually increase towards the barrel end part corresponding to edge drop 2, and the upper and lower work rolls are configured such that they can individually be shifted in the axial direction, even if the edge drops at both ends of the slab material differ considerably from each other, the shape of the rolled plate can be maintained in good condition by separately shifting upper and lower work rolls in the axial direction.
Because the backup roll 30 is equipped with the escape portion 32 where diameters gradually decrease towards the axial end so that the roll does not contact the reverse taper portion of the work roll, the reverse taper portion of the work rolls can be prevented from interfering with the backup roll, and the work roll can be shifted axially with a low resistance.
In addition, the crown can be finely adjusted by means of a work roll bending mechanism that applies a bending moment to the work rolls.
The present invention should of course not be limited only to the aforementioned embodiments, but can be modified in various ways provided there are no deviations from the claims of the present invention.
Number | Date | Country | Kind |
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2003-286014 | Aug 2003 | JP | national |
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4781051 | Schultes et al. | Nov 1988 | A |
4864836 | Ochiai | Sep 1989 | A |
5218852 | Watanabe et al. | Jun 1993 | A |
5697244 | Seidel | Dec 1997 | A |
6324881 | Benedetti et al. | Dec 2001 | B1 |
Number | Date | Country |
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2002-011503 | Jan 2002 | JP |
Number | Date | Country | |
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20050044916 A1 | Mar 2005 | US |