JP3614834B2 - Hot rolling equipment and hot rolling method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention according to the claims relates to a hot rolling facility and a hot rolling method for rolling a plate such as a steel plate including a rough rolling step.
[0002]
[Prior art]
In the hot rolling of a steel plate, a heated slab (continuous cast piece) having a thickness of about 200 to 300 mm is rolled to a thickness of several tens of mm with a roughing mill, and then passed through a finishing mill. Generally, it is a plate having a thickness of several mm. Rough rolling mills include those having one or a small number of reversible (reverse) rolling mills and those having about three or more continuous (one-way) rolling mills. When a reversible roughing mill is provided, there are advantages that the occupied space is small and the equipment cost is low, and when many continuous rolling mills are arranged, there is an advantage that the production capacity is high. In addition, about the finishing mill on the downstream side, usually, 6 or more rolling mills are arranged in tandem.
[0003]
Generally, means for reducing the width are arranged before and after the rough rolling mill. This is because it is difficult to freely set the width in units of slabs, and thus it is necessary to adjust the plate width at the stage of rough rolling in order to match the width of the steel plate as a product with demand. In general, the width reduction is performed by a vertical roll having an axis oriented vertically. Specific means include VSB (Vertical Scale Breaker) and sizing mill for strong reduction (high width reduction ability), and attached to the front or rear surface of the horizontal roll of the roughing mill. There is a so-called edger or the like that corrects (edging) the width return.
[0004]
In the case of strong pressure reduction, deformation called “dogbone” is prone to occur in the vicinity of both sides (both ends in the width direction) of the plate (slab) in the thickness direction. A groove called a caliber that constrains both the upper and lower surfaces of the plate at the same time in the former means in order to suppress the deformation height by propagating such deformation along with the rolling force to near the center of the plate width. A roll (Caliber roll) having s is used as a vertical roll. On the other hand, in the edger, a flat roll that does not have such a caliber (that is, does not restrain the upper and lower surfaces of the slab) is used as a vertical roll.
An example in which the caliber roll is a vertical roll is described in, for example, Japanese Utility Model Publication No. 58-111102.
[0005]
[Problems to be solved by the invention]
The above-mentioned two kinds of means for reducing the width of the plate have both advantages and disadvantages. That is, with a normal edger in which the flat roll is a vertical roll, it is impossible to appropriately reduce (strongly) the plate. Therefore, the dimensional range in which the width can be reduced is limited. As a result, in order to meet the various dimensional demands of products, it is necessary to prepare slabs with a wide variety of widths. Aggregation cannot proceed sufficiently. On the other hand, in a VSB or sizing mill in which a caliber roll is a vertical roll, a plate having a thickness reduced by horizontal reduction may not be appropriately reduced in width. In other words, when reducing the width of a plate that is thinner than the slab, wrinkles may occur due to the one-side contact phenomenon in which only one of the upper and lower surfaces of the plate contacts the caliber, or the seam w Is likely to occur.
[0006]
If two types of vertical rolls, a flat roll and a caliber roll, are both arranged before and after the roughing mill, it is naturally preferable in terms of function, but the equipment cost is considerably high, and it is large for the arrangement. Space is occupied. In particular, when a reversible roughing mill is installed, the cost and space advantages of reducing the number of stands of the roughing mill by reversible are substantially lost by using two types of vertical rolls. It can be broken. Further, if the flat roll and the caliber roll can be appropriately exchanged and used, the cost and space problems are solved, but the replacement work takes time, which is not preferable in terms of production efficiency.
[0007]
The claimed invention provides a hot rolling facility and a hot rolling method capable of utilizing the advantages of both a flat roll and a caliber roll so as not to incur any disadvantages in terms of equipment cost, space and production efficiency. It is something to try.
[0008]
[Means for Solving the Problems]
The hot rolling facility according to claim 1 is a hot rolling facility including a pair of vertical rolls as a width reduction means of a plate (steel plate or other metal plate) on a reversible roughing mill (front or rear surface thereof). There are
a) For vertical rollsThe bottom width is equal to the unrolled slab thicknessA caliber part that can make a large reduction (of the plate width) by contacting the upper and lower sides (that is, the front and back) of the plate during width reduction and propagating the dogbone to the center of the plate width,It has a wider bottom than the caliber partA flat part that performs light reduction (of the plate width) without contacting any of the upper and lower surfaces of the plate during width reduction is formed at different positions in the longitudinal direction,
b) The vertical roll is arranged so that it can be shifted in the longitudinal direction.about,
c) And when making multiple passes of the plate, the first pass among the multiple passes uses the caliber portion of the vertical roll to reduce the width, and in the latter pass, the vertical roll is elongated. Shifting in the direction and using the flat part to be able to perform width reduction
It is characterized by.
[0009]
According to such a hot rolling facility, an appropriate width reduction can be performed on the plate by using either the caliber portion or the flat portion of the vertical roll. That is, if the plate is squeezed from both sides (both ends in the width direction) by, for example, caliber portions in the pair of vertical rolls, the plate can be greatly squeezed while propagating dogbone deformation to the center portion of the plate width. As a result, it is possible to reduce the width in a large dimensional range at the beginning of rough rolling of the slab, and it is also possible to proceed with a substantial aggregation of the slab width dimensions as necessary. On the other hand, when the vertical roll is shifted in the longitudinal direction and the flat portion is pressed against both sides of the plate, the width return correction (edging) or the like during horizontal reduction can be performed as a general edger. Since there is no caliber in the flat part where the upper and lower surfaces of the plate come into contact, deep seam wrinkles (that is, not only near both ends of the plate width, but near the center of the plate where the thickness has been reduced due to the progress of rough rolling. It is possible to perform preferable edging without causing seam 疵).
[0010]
The rough rolling mill is of a reversible type and requires a small number of stands, and there is only one set of vertical rolls attached to the rough rolling mill (that is, the above-described two types of vertical rolls are arranged. Therefore, it can be said that this hot rolling facility is a low-cost facility in which rough rolling mills and related equipment are arranged in a compact manner. In addition, in order to switch between the use of the caliber part and the use of the flat part, it is not necessary to replace the vertical roll, and it is only necessary to shift the roll in the longitudinal direction. There is no inconvenience in terms of ease and production efficiency. If the number of stands of the rough rolling mill is small, it is possible to easily correct the plate shape by rolling such as fine adjustment of the roll gap, and there is also an advantage that the operation is easily stabilized.
The above c) Therefore, this hot rolling equipment is also preferable in that rough rolling of the plate can be efficiently and appropriately performed.
[0011]
The hot rolling facility according to claim 2 is characterized in that a finishing rolling mill including a very small diameter roll mill or a different diameter roll mill is arranged on the downstream side of the rough rolling mill. The ultra-small diameter roll mill referred to here refers to a rolling mill in which both of the pair of work rolls have a diameter less than 600 mm, and the different diameter roll mill does not have the same diameter for the pair of work rolls. An equivalent roll diameter (average roll diameter) of the roll is less than 600 mm in diameter.
[0012]
The hot rolling facility according to this claim in which such a finishing mill is arranged can make the overall facility combining the rough rolling mill and the finishing mill extremely compact. This is because the arrangement of the rough rolling mill and the vertical roll attached thereto is compact as described above, and the finishing rolling mill can also be configured to be compact with a short equipment length. The reason why the finishing mill can be made compact is as follows.
-An extremely small diameter roll mill or a different diameter roll mill arranged in a finishing mill has a small equivalent roll diameter or both (a pair of) work roll diameters, and therefore can perform rolling with a high rolling reduction even with a low rolling load. If rolling with a high rolling reduction can be performed in each mill, the number of stands of the finishing mill can be reduced (for example, 6 or less). If the number of stands can be reduced, the finishing mill naturally becomes compact with a short equipment length.
・ If the number of stands of the finishing mill is reduced, the temperature drop width of the plate until the rolling at the final stand is completed becomes smaller. If the temperature drop width is reduced, the rolling speed can be reduced, and therefore the distance that the plate is fed during the time required for cooling is shortened. This means that the length of the cooling table can be shortened, so that the total length of the line (equipment) is naturally shortened. If the rolling speed can be reduced, there is an advantage that the operation can be stabilized and the product quality can be improved.
[0013]
If the equipment can be made compact as described above, the equipment cost can be considerably reduced, and the equipment suitable for producing a relatively small amount of plates at a low cost is hot enough to meet the recent market scale. It becomes rolling equipment. The easy handling with respect to the vertical rolls of the roughing mill and the ease of maintaining the operation stability in the roughing mill and the finishing mill are also advantages suitable for small-volume production type businesses.
[0014]
The hot rolling facility described in claim 3 is further characterized in that means (including one for increasing the temperature) for suppressing the temperature drop of the plate is arranged between the rough rolling mill and the finish rolling mill. As such means, there are a coil box for winding and unwinding a plate, a sheet bar heater for heating the leading end and tail end of the plate with a burner, or a tunnel furnace.
[0015]
According to such hot rolling equipment, the above-described advantages such as downsizing and cost reduction of the equipment and stabilization of operation become more remarkable. The reason is as follows. That is,
・ By placing a means to suppress the temperature drop of the plate between the rough rolling mill and the finish rolling mill, the finish rolling after the rough rolling is performed while the plate temperature is high without increasing the rolling speed. be able to. If the rolling speed can be further reduced in this way, the distance required for cooling is shortened as described above, and the length of the cooling table and thus the total length of the line are shortened. In addition, if the rolling speed is reduced, the advantages of stabilizing the operation and improving the product quality are also generated.
[0016]
The hot rolling method according to claim 4 is a hot rolling method that uses the hot rolling equipment according to any one of claims 1 to 3, and causes a reversible rough rolling mill to pass a plurality of plates ( In other words, when rough rolling the plate)
1) In the first one of the plurality of passes (not necessarily including the first pass, but in the first half), the caliber portion of the vertical roll is used to reduce the width,
2) In the later pass (not necessarily including the last pass, but in the latter half of the pass), the vertical roll is shifted in the longitudinal direction and the width is reduced using the flat part. And
[0017]
If such a method is taken, rough rolling of a board can be performed efficiently and appropriately. That is, while the plate is thick at the beginning of rough rolling (for example, it is almost not reduced from the thickness of the slab), by using the caliber portion as in 1) above, the dog bone deformation is near the center of the plate width. The plate width is reduced by effectively rolling down the plate while propagating to the surface, and when the plate thickness is reduced due to the horizontal reduction by rough rolling, the flat part is used as described in 2) above and the deep seam It is possible to perform edging that does not occur (correction of width return by horizontal reduction). In other words, this hot rolling method has the effect that it is possible to produce a plate with excellent quality while maintaining sufficient productivity, and to proceed with the aggregation of slab width dimensions.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the invention is shown in FIGS. FIG. 1 is a conceptual diagram showing a procedure for reducing the width of the plate A by the vertical rolls 11 and 12. FIG. 2 is a front view of the edger 10 including the vertical rolls 11 and 12 of FIG. 1 (a view taken along arrow II-II in FIG. 3). 3 is an overall layout diagram (FIG. 3 (a) is a side view and FIG. 3 (b) is a plan view) showing a hot rolling facility including the edger 10 of FIG.
[0019]
The hot rolling facility shown in FIG. 3 is a facility that rolls a plate (steel plate) A using the rough rolling mill 1 and the finish rolling mill 2. A heating furnace 3, a roughing mill 1, a finishing mill 2, and a winder 7 are arranged in this order on a substantially linear line to constitute a main portion. After heating the slab (plate A) to about 1200 ° C. in the heating furnace 3, the slab is made into a sheet bar (plate A) having a thickness of about 30 mm by the rough rolling mill 1, and further the thickness is 1 by the finish rolling mill 2. It is stretched to a hot-rolled steel sheet (plate A) of ˜several mm, and is wound in a coil shape by a winder 7. As the rough rolling mill 1, only one stand of a quadruple reverse type (reversible type) is arranged, and as the finishing mill 2, a quadruple rolling mill 6 stands are arranged in tandem. A centering guide 4 and an edger 10 for the plate A are arranged on the front surface (upstream side) of the rough rolling mill 1, and the width of the plate A is measured on the rear surface (downstream side) of the rough rolling mill 1. A width gauge 5 was placed. Also regarding the finishing mill 2, the light reduction edger 21 is disposed on the front surface, and the width gauge 6 is disposed on the rear surface.
[0020]
In this hot rolling facility, the following edger 10 is attached to the rough rolling mill 1 so that the width reduction of the plate A in the rough rolling process can be efficiently performed under a space-saving condition.
[0021]
First, the overall configuration of the edger 10 is as shown in FIG. That is, a pair of vertical rolls 11 and 12 for reducing the width are arranged, and the rotation driving means 13, the reduction means 15 and the shift means 17 are connected to the rolls 11 and 12, respectively.
[0022]
Each rotation driving means 13 is for rotating each of the vertical rolls 11 and 12, and includes a motor 13a, a speed reducer 13b, a universal joint 13c, and the like attached to the edger housing 10a. The driving force output from the motor 13a through the speed reducer 13b is transmitted to the vertical roll 11 or 12 via a universal joint 13c whose length can be changed by a spline shaft (not shown).
[0023]
Each of the rolling-down means 15 is for moving the vertical rolls 11 and 12 in the horizontal direction (that is, the direction in which the rolls are pressed toward and away from each other). Each reduction means 15 includes a motor 15a, a speed reducer 15b, a screw jack 15c, a hydraulic cylinder 15d for balancing, and the like. By changing to, the rolls 11 and 12 are moved in the horizontal direction. Each of the rolls 11 and 12 is incorporated in a cassette frame 15e that holds an outer portion of a bearing (not shown), and the cassette frame 15e is connected to the moving end of the screw jack 15c so as to be supported in a horizontally movable manner. . Two screw jacks 15c are connected in parallel to the upper and lower portions of each cassette frame 15e, and two hydraulic cylinders 15d are connected to the cassette frame 15e between the two. . By always applying a thrust to the cylinder 15d from the edger housing 10a, the vertical rolls 11 and 12 are not caused to have horizontal play due to backlash in the screw jack 15c. To do.
[0024]
Each shift means 17 is a mechanism for changing the position of each of the vertical rolls 11 and 12 supported in the cassette frame 15e in the longitudinal direction (the axial length direction of the rolls 11 and 12). A downward projecting portion 17a is integrally formed on the cassette frame 15e, and a hydraulic (fluid pressure) cylinder 17b is incorporated in the cassette frame 15e so that the upward extending and contracting end is connected to the lower end of the roll 11 or 12. By extending and contracting the hydraulic cylinder 17b, the rolls 11 and 12 can be shifted in the axial direction. The rolls 11 and 12 are connected to the rotation drive means 13 via the universal joint 13c with a spline shaft as described above. Even if it is shifted vertically, it can be rotated without any trouble.
[0025]
Since each of the vertical rolls 11 and 12 is incorporated into the cassette frame 15e so as to be easily separated, it is easy to take out only the rolls 11 and 12 from the edger 10 for the purpose of replacement or the like. A roll 11 (12) indicated by a virtual line in the vicinity of the center in FIG. 2 represents a state where the roll 11 (12) is extracted upward from the cassette frame 15e and is lifted by a crane (not shown). When taking out the roll 11 or 12 in this way, the universal joint 13c may be lifted by the moving mechanism 13d including a hydraulic cylinder.
[0026]
As shown in FIG. 1, caliber portions 11a and 12a and flat portions 11b and 12b are formed in the vertical rolls 11 and 12 at different positions in the axial length direction.
[0027]
The caliber portion 11a in the roll 11 has a relatively short interval in the axial length direction (an interval close to the thickness of the plate A at the beginning of rough rolling), and a flange (鍔) 11x including a curved surface portion (a portion with a rounded shape). -It is a part which has 11y on both sides, and the caliber part 12a in the roll 12 is also a part which has the similar flanges 12x and 12y on both sides. In the illustrated example, the width d of the bottom portion (interval of the base portion such as the flanges 11x and 11y) and the top portion (the outermost peripheral portion on the facing inner surface of the flanges 11x and 11y) in each caliber portion 11a and 12a. The width D is d≈H ≦ D with respect to the unrolled slab thickness H (that is, the width d and the slab thickness H are substantially equal to each other although there may be a difference within about ± 10 mm, and the width D is more than that). Using these caliber portions 11a and 12a, when the plate A immediately before the start of the rough rolling or immediately after the start (and therefore the thickness has not changed much from the slab) is reduced in width, both side edges (both ends in the width direction) of the plate A The upper and lower surfaces (that is, the front and back surfaces) in the vicinity of the portion 11) are in contact with the flanges 11x and 11y and 12x and 12y.
[0028]
On the other hand, the flat portions 11b and 12b in each of the vertical rolls 11 and 12 are formed so that the bottom, which is a flat cylindrical surface, is wider than the caliber portions 11a and 12a, and the top and bottom (front and back) of the plate A including the unrolled slab. It is the part which did not restrain any side of. In this example, there are flanges 11y or 12y of the caliber parts 11a and 12a at the upper part of the flat parts 11b and 12b, and there are similar flanges at the lower part, but the gap between them is more than the thickness of the slab. The upper and lower surfaces of A are not restrained.
[0029]
When both the vertical rolls 11 and 12 are shifted in the axial length direction using the shift means 17 described with reference to FIG. 2, the caliber portions 11a and 12a are moved as shown in FIGS. 1 (a) and 1 (b). Any one of the flat portions 11b and 12b can be adjusted to the height of the pass line a through which the plate A passes. When the caliber portions 11a and 12a are aligned with the pass line a as shown in FIG. 1 (a), the caliber portions 11a and 12a propagate the dogbone deformation to the center portion of the plate width, greatly reducing the plate A, The width can be greatly reduced. On the other hand, when the flat portions 11b and 12b are aligned with the pass line a as shown in FIG. 1 (b), the rolls 11 and 12 are not brought into contact with any of the upper and lower surfaces of the plate A, and the deep seam is formed. Appropriate edging without wrinkles can be performed.
[0030]
Utilizing such characteristics of the edger 10, in the hot rolling facility of FIG. 3, the roughing mill 1 is operated in the following manner, for example. That is,
In the rough rolling mill 1 (horizontal roll), the plate A is reciprocated four times to perform a total of nine passes.
In the even-numbered path among the 9 paths (that is, the path that is sent in the direction in which the plate A is returned), the horizontal roll is performed without performing the width reduction by the edger 10 (that is, the empty path between the vertical rolls 11 and 12 is widened). Only perform horizontal pressure reduction.
In the odd-numbered pass, the width reduction by the edger 10 is performed together with the horizontal reduction. In the first and third passes at the beginning, as shown in FIG. Large reduction is performed using the caliber portions 11a and 12a.
After the third pass is finished and before the fourth pass, the vertical rolls 11 and 12 are shifted in the axial length direction using the shift means 17 of FIG. 7. In the ninth pass, the width return due to the horizontal reduction is corrected by edging using the flat portions 11b and 12b as shown in FIG.
When the ninth pass is completed, the shift unit 17 is activated again, and the axial length direction positions of the vertical rolls 11 and 12 are returned to the original positions. In addition, about the board A which passed the rough rolling mill 1 by the odd-numbered path | pass, the width meter 5 is made to measure the width | variety, and it is supposed that a measurement result will be reflected in the width reduction of the next time or after that.
[0031]
Since the single edger 10 that can be used in two ways, large reduction and edging, is combined with one stand type reverse roughing mill 1 as shown in FIG. 3, the hot rolling equipment shown in FIG. It can be said that it is compact and advantageous in terms of equipment cost. The fact that the rough rolling mill 1 has only one stand naturally means that the length occupied by the rough rolling mill on the line is short and the equipment cost is low. Moreover, in the rough rolling mill 1 having only one stand, unlike a multi-stand one, it is possible to immediately identify a rough rolling mill that requires fine adjustment such as a roll gap, and it is very easy to correct the bending of the plate, the end shape, and the like. Since it can be performed, there is also an advantage that it is easy to stabilize the operation. In other words, the hot rolling equipment shown in the figure is not an arrangement of a large number of continuous type rough rolling mills, so its production capacity is limited, but it is extremely desirable for smooth production of a relatively small amount of plates at low cost. It can be said.
[0032]
In addition to this hot rolling facility, the following configuration is adopted in order to reduce the size and cost of the facility and to realize operational ease, production stability and quality improvement. That is,
B) In the finish rolling mill 2 arranged on the downstream side of the rough rolling mill, so-called different diameter roll mills 23 are arranged on the subsequent three stands. Among the roll rolls 23 with different diameters, the diameter of the upper one of the work rolls in contact with the plate A is 480 mm, the diameter of the lower one is 600 mm, and the average equivalent roll diameter is 540 mm. In particular, only the large work roll on the lower side is rotationally driven, while the upper work roll on the small side is made to be a non-driven rotatable type so that a shearing force is applied to the plate A. Due to the small work roll (its equivalent roll diameter) and the application of a shearing force to the plate A, these three stands can perform rolling with a high rolling reduction even at a relatively low rolling load. If rolling with a high rolling reduction is possible, the number of stands of the finish rolling mill 2 can be reduced, and the rolling speed can be reduced for that purpose, shortening the equipment length and stabilizing the operation at the same time. Realized.
[0033]
B) A CVC mill 22 is disposed as the preceding three stands of the finishing mill 2 described above. The CVC mill refers to a rolling mill including a roll (CVC roll) whose outer diameter is continuously changed in the axial length direction and arranged so as to be movable in the axial length direction. If the CVC mill 22 is arranged in this manner, the crown (shape) of the plate A such as a thermal crown can be effectively controlled based on the inherent ability to change the roll gap shape, and the quality of the plate A is improved. In addition, it is possible to stabilize the threading plate in the downstream roll mill 23 having a different diameter. In addition, even when a pair of cross rolls that are arranged in a cross shape that is closest to the center near the center instead of parallel to each other and that can adjust the mutual positional relationship instead of the above-described CVC mill, Similar effects can be obtained.
[0034]
Although not used in the illustrated example,
C) Between the roughing mill 1 (of the width meter 5) and the finishing mill 2 (of the edger 21), a means for preventing the temperature drop of the plate (or raising the temperature somewhat), such as a coil box, is provided. It is good to arrange. The coil box suppresses the temperature drop by winding the roughly rolled plate A (sheet bar) once in a coil shape. Thus, if the temperature drop of the plate A is suppressed, the finish rolling can be smoothly carried out while the plate temperature is high even at a low rolling speed. If the rolling speed can be reduced, the length of the cooling table is shortened, the total length of the hot rolling equipment is shortened, and it is advantageous for stabilizing the operation and improving the product quality.
[0035]
【The invention's effect】
According to the hot rolling facility described in claim 1, appropriate width reduction can be applied to the plate by properly using the caliber portion and the flat portion of the vertical roll. That is, it is possible to greatly reduce the plate while propagating the dogbone deformation to the center portion of the plate width, and it is possible to perform preferable edging without causing deep seam wrinkles on the plate that has undergone rough rolling. Advantages of this equipment include that the equipment is compact and can be configured at low cost, that it is easy to handle vertical rolls and that production efficiency is not bad, and that it is easy to stabilize operations.
[0036]
The hot rolling facility according to claim 2 can make the entire combination of the rough rolling mill and the finish rolling mill into a very compact and low-cost facility. Along with the ease of handling vertical rolls and the ease of maintaining operational stability, etc., it is suitable for the recent market as equipment suitable for producing a relatively small amount of plates at low cost. Become.
[0037]
With the hot rolling facility according to the third aspect, the above-mentioned advantages such as downsizing and cost reduction of the facility and stabilization of operation become more remarkable.
[0038]
According to the hot rolling method of the fourth aspect, rough rolling of the plate can be performed efficiently and appropriately. That is, it is possible to produce high-quality plates while maintaining sufficient productivity, and it is possible to proceed with the consolidation of slab width dimensions.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention, and is a conceptual diagram showing a procedure for width-pressing a plate A by vertical rolls 11 and 12; FIG. 1 (a) shows a state in which the plate A is reduced in width by the caliber portion, and FIG. 1 (b) shows a state in which the plate A is reduced in width by the flat portion.
2 is a front view of the edger 10 including the vertical rolls 11 and 12 of FIG. 1, and is a view taken along arrow II-II in FIG.
3 is an overall layout diagram of a hot rolling facility including the edger 10 of FIG. FIG. 3A is a side view of the facility, and FIG. 3B is a plan view.
[Explanation of symbols]
1 Rough rolling mill
2 Finishing mill
10 Edger
11.12 Vertical roll
11a, 12a Caliber part
11b · 12b flat part
17 Shift means
23 Different diameter roll mill
A plate (steel plate)

Claims (4)

It is a hot rolling facility including a pair of vertical rolls as means for reducing the width of the plate in the reversible rough rolling mill,
The vertical roll has a caliber portion for large reduction that contacts the upper and lower surfaces of the plate when the width is reduced and the width of the bottom is equal to the unrolled slab thickness, and a bottom wider than the caliber portion. Have flat portions for light pressure lowering that do not contact any of the upper and lower surfaces of the plate at different positions in the longitudinal direction, and are arranged to be shiftable in the longitudinal direction,
And, when the plate is subjected to a plurality of passes, width reduction is performed using the caliber portion in the vertical roll in the first pass among the multiple passes, and the vertical roll is elongated in the later pass. Be able to shift in the direction and use the flat part to reduce the width
Hot rolling equipment characterized by The hot rolling facility according to claim 1, further comprising a finishing mill including a very small diameter roll mill or a different diameter roll mill on the downstream side of the rough rolling mill. The hot rolling facility according to claim 1 or 2, further comprising means for suppressing a temperature drop of the plate between the rough rolling mill and the finish rolling mill. A hot rolling method using the hot rolling equipment according to any one of claims 1 to 3,
When the reversible roughing mill passes a plurality of passes, the first pass among the passes uses the caliber portion in the vertical roll to reduce the width, and the latter pass passes the vertical pass. A hot rolling method characterized in that a die roll is shifted in the longitudinal direction and width reduction is performed using a flat portion.

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