JPH08300011A - Method and device for executing edging press of hot slab - Google Patents

Abstract

PURPOSE: To suppress the movement of side faces of an edged slab to the surface and back faces of a hot rolled steel sheet and to reduce seam flaws by restraining the hot slab on the inlet and outlet sides in the line direction of a press die with pinch rolls and edging the slab by the use of convex dies whose cross-sectional projecting shape is circular-arcuate. CONSTITUTION: The slab 6 is restrained with inlet-side pinch rolls 2, 3 and outlet-side pinch rolls 4, 5, so torsion and lifting at the time of edging are prevented and stability is hightened. Thickening of the slab due to the amount of edging is calculated in an edging controlling part 11 and position control is executed so that the lower rolls 4a, 5a of the outlet-side pinch rolls 4, 5 are lowered by a half of the thickening of the slab. In addition to this, by screwing down the upper rolls 4b, 5b at a fixed pressure, the balance of the slab 6 before and after the convex dies 1 is held. Then, the seam flaws which are generated when stainless steel is hot-rolled are drastically reduced and the yield of product is improved by increasing trim width in the edge parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a width reduction pressing method and apparatus capable of reducing continuous edge defects during width reduction of a hot slab extracted from a heating furnace in a hot rolling line.

[0002]

2. Description of the Related Art Hot rolled products are produced by heating a slab in a heating furnace and hot rolling with a rough rolling machine or a finish rolling machine to obtain a thickness of 1.0 to
It is manufactured by making a 25.4 mm strip, winding it on a coil, cooling it, and then treating it in various conditioning lines.
The slab width in the hot rolling is determined according to the coil width. The relationship between the slab width and the coil width is generally associated with the edger ability and the width accuracy. In terms of process operation, it is desirable to consolidate the slab size, and in particular because of the need for consolidating continuous casting lots, the width reduction capacity of the edger tends to be enhanced.

The edger of the slab is classified into a width rolling method using a vertical rolling roll and a sizing press method in which a width reduction is performed by a width reduction press. In the sizing press, a pair of dies having an inclined portion and a parallel portion that are expanded and inclined toward the entrance side of the slab are arranged facing each other on a hydraulic cylinder attached to a fixed portion or a crankshaft driven by a motor. The slab is continuously or intermittently passed between the slabs, and the molds are moved toward and away from each other without restraining the upper and lower sides of the slab to perform width reduction to a predetermined width. These sizing presses have excellent width reduction ability compared to width rolling with vertical rolling rolls, can reduce the fish tail at the front and rear edges of the rolled material generated after hot rolling, and have a good yield, as well as dogbone The cross-sectional shape is less likely to be concentrated in the vicinity of the edge portion, and good flatness of the rolled material is easily obtained.

On the other hand, when the stainless steel slab is hot-rolled, linear flaws 72 called seam flaws are generated over the entire length of the material 71, as shown in FIG. This defect 72
The slab edge E of the slab 73 serves as a scratch starting point (origin generation by edge cooling and segregation of the slab), and the scratch occurs because the material moves from the edge 74 of the material 71 to the center of the front and back surfaces every time horizontal rolling is stacked. . This seam flaw is observed as a linear streak inward about 15 to 20 mm from the edge of the hot-rolled steel strip over the entire length of the product on both the front and back surfaces.
The unevenness of the seam flaw is not a problem in practical use, but there is a complaint from the customer regarding the appearance. Therefore, at present, the edge portion is trimmed to deal with it, and the product yield is reduced accordingly. This seam flaw tends to occur even when a sizing press using a flat die is used, or under the condition where neither the sizing press nor the edger roll is used at all.

As a measure for suppressing the seam flaw, a method of rolling only the ridge portion of the rolled material with a vertical roll or applying a rolling reduction of 5 to 15 mm only to the ridge and the center portion of the side surface of the rolled material (Japanese Patent Laid-Open No. 2000-242242) Japanese Laid-Open Patent Publication No. 53-28542), a method of forming a slab in a concave shape in which the short sides facing each other in the cross section are inwardly depressed (Japanese Patent Laid-Open No. 58-13850).
No. 2) has been proposed. Then, a width rolling roll (Japanese Patent Publication No. 50-14632) provided with a convex caliber that rolls down and dents the central portions of both side surfaces of the slab is proposed.

Further, the slab pressing surface of the die has a depth composed of a flat surface which engages with the slab side surface and an inclined surface having a caliber angle of 8 to 45 ° which engages with the upper and lower corners of the slab side edge. A die having a caliber groove of 5 to 20 mm (Japanese Patent Application Laid-Open No. 63-192503), a plurality of slab entry side inclined portions and one parallel portion subsequent thereto are provided as inclined portions and parallel portions of the press surface, A mold for rotating and using the press surface (JP-A-1-218707), and a mold in which a small inclined portion and a large inclined portion are sequentially formed on at least one of parallel portions of the die (JP-A-3-81005). Gazette), a die in which a plurality of protrusions extending in the pass line direction of the plate material are provided on the inclined surface and the parallel surface of the die at predetermined intervals in the die thickness direction (Japanese Utility Model Publication No. 3-70801), Make the mold convex and constrain the upper and lower surfaces of the slab. How to press the sides to the concave (126th Japan Iron and Steel Institute lecture tournament 討 51) it has been proposed to.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The techniques disclosed in Japanese Laid-Open Patent Publication No. 542, Japanese Patent Laid-Open No. 58-138502 and Japanese Patent Publication No. 50-14632 have the drawbacks that the slab width cannot be changed significantly and that high width accuracy cannot be secured over the entire length. are doing. In addition, since this technology uses caliber rolls to suppress dogbones, not only is it necessary to add vertical rolls or increase passage equipment for a significant change in slab width, but also to slabs with different thicknesses. It was difficult to deal with.

The mold disclosed in Japanese Patent Laid-Open No. 63-192503 is provided with a caliber groove on the pressure lower surface of the slab to prevent a sharp corner shape from occurring in the slab corner at the time of width reduction. It prevents supercooling to prevent surface defects such as cracks, and the effect of preventing seam defects is not sufficient. Furthermore, the disk-shaped mold disclosed in Japanese Patent Application Laid-Open No. 1-218707 has a problem that the radius is determined due to equipment restrictions, and it cannot be applied if the mold holding method is changed. Can not be applied to equipment. Furthermore, when the die having the protrusion disclosed in Japanese Utility Model Laid-Open No. 3-70801 is subjected to width reduction, the effect of improving the seam flaw is large, but the seam flaw level fluctuation between the front and back sides due to the deviation between the die convex portion and the slab side surface center. Cannot be ignored, and it was necessary to adjust the height position of the convex portion according to the slab thickness. When a convex mold is used, the slab is often twisted or buckled by an unbalanced vertical load, and once twisting or buckling occurs, the centering deviation gradually increases. However, even in this case, the seam flaw improvement effect was hindered, which was a problem.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to suppress the movement of the slab side face subjected to width reduction to the front and back surfaces of the hot-rolled steel sheet, to reduce seam flaws, and also when the slab thickness is different. (EN) A method and an apparatus for applying a width reduction pressing of a hot slab that can be applied.

[0010]

Means for Solving the Problems The present inventors have conducted various tests and studies to achieve the above object. As a result, by restraining the hot slab with pinch rolls on the inlet and outlet sides of the press die in the line direction, twisting and lifting of the slab are prevented, and stability is improved. 1/2 of slab thickness increase by pressing
It is possible to balance the slabs before and after the mold by lowering only, and use a convex mold whose cross-sectional convex shape is arcuate or has rounded corners, and use the convex mold center of the convex mold. By accurately abutting the part on the center of the slab side face, the slab side face can be shaped into a curved recess and plastically deforms during hot rolling, but the amount by which the curved recess widens outward than the corner There is little, it works to return the metal flow of the slab edge, which is the starting point of seam flaws, to the edge of the hot-rolled steel strip, and the seam flaws of the conventional 15-20
It was found that the distance from the edge of the hot-rolled steel strip of the front and back seam flaws can be made uniform while improving from 3 mm to 3 to 6 mm, and reached the present invention.

That is, according to the present invention, while the hot slab is continuously or intermittently run, a press die having an inclined portion and a parallel portion provided on both sides in the width direction of the slab is moved close to or away from each other to a predetermined distance. In the width reduction pressing method of the hot slab that performs width reduction to the width, the hot slab is constrained by the pinch roll on the inlet and outlet sides of the press die in the line direction, and the convex cross-sectional shape is rounded at the arc shape or convex corners. It is a width reduction pressing method for a hot slab characterized by performing a width reduction using a convex mold having the above.

Further, according to the present invention, while the hot slab is continuously or intermittently run, a press die having an inclined portion and a parallel portion provided on both sides in the width direction of the slab is provided close to each other.
In a width reduction press device for a hot slab that separates and performs width reduction to a predetermined width, pinch rolls respectively disposed on the inlet and outlet sides of the press die in the line direction and the outlet side lower rolls of the pinch rolls are subjected to width reduction. The width of the slab was reduced by 1/2 and the width reduction control unit that positions the center of the convex part of the convex mold having the arc shape in the cross section or the rounded corners of the convex part at the center of the slab side was combined. It is a width reduction press device for hot slabs characterized by the above.

[0013]

In the present invention, the hot slab is restrained by the pinch rolls on the inlet and outlet sides in the line direction of the press die to prevent the slab from being twisted and lifted, and the stability is enhanced. By lowering the lower roll of the roll by 1/2 of the thickness increase of the slab by pressing, the slab before and after the mold is balanced, and the central part of the convex part of the convex mold is brought into proper contact with the central part of the slab side surface. The height of the slab edge becomes the starting point of the seam flaw by performing the overall height adjustment and reducing the width using a convex mold with a convex cross-sectional shape having an arcuate shape or rounded corners. To return to the edge of the hot-rolled steel strip, and the seam flaw is 3 to 6 mm from the conventional 15 to 20 mm.
Can be improved to a degree.

Further, in the width reduction press device of the present invention, the hot slab is constrained by the pinch rolls on the inlet and outlet sides of the press die in the line direction, by the pinch rolls respectively disposed on the inlet and outlet sides of the press die in the line direction. The slab can be prevented from twisting and rising. In addition, by providing the width reduction controller, the output side lower roll of the pinch roll can be automatically lowered by 1/2 of the slab thickness increase due to the width reduction. By pressing down with, it is possible to balance the slab before and after the mold, and the center of the convex part of the convex mold can be located at the center of the side of the slab according to the slab thickness. The distance from the edge of the steel strip can be made uniform. Further, the press die of the width reduction press is a convex die having a circular arc-shaped cross section or a rounded corner of the convex portion, thereby preventing internal folding of the edge and passing through the plate due to edge cracking. Sexual inhibition can be prevented.

In the present invention, the pinch rolls arranged before and after the press die may be one set or a plurality of sets, but it is effective to set two sets. Further, as the width reduction control unit of the present invention, the press reduction amount is divided by the slab width based on the slab width, the slab thickness, the width reduction amount, and the like input from a higher-level computer such as a higher-order hot rolling control unit. The slab thickening is calculated according to the press reduction rate obtained by
There is no particular limitation as long as it has a leveling function of being able to lower the lower roll of the pinch roll on the exit side by 2 and can lower the upper roll on the exit side of the pinch roll at a constant pressure in accordance therewith. As a mechanism for lowering the lower roll of the pinch roll on the delivery side, a system of temporarily lowering the hydraulic servo mechanism to outside the control range and raising it by automatic pressure control or an automatic pressure control system by an electric motor may be used. Accuracy and response speed are poor, which is disadvantageous to the stability of equipment. Furthermore, the width reduction control unit of the present invention is based on the slab width, the slab thickness, and the press reduction amount input from a higher-level computer such as a higher-order hot rolling control unit, and the center of the convex portion of the convex die and the slab side surface. There is no particular limitation as long as the level difference from the center can be calculated and the position of the press die can be adjusted so that the level difference becomes zero.

In the present invention, the height h of the arc-shaped or corner-rounded convex portion formed on the convex mold varies depending on the operating conditions such as the pressing amount and the slab thickness, but a preferable range is 10 to 10. When the width is 20 mm, if it is too large, the side surface of the slab is turned over during width reduction pressing, causing a fold defect in the edge of the hot rolled coil. Further, if the height h of the convex portion is too small, the above effect cannot be exhibited. Further, in the present invention, the height difference in the slab longitudinal direction of the convex portion formed in the mold means that the convex and concave portions are gently curved before and after the convex portion or the corners are rounded to reduce the convex portion. This allows the side surface of the slab to be smoothly shaped into a concave portion having an arc shape or a rounded corner when a width reduction press is performed.

Proximity of the pair of convex molds in the present invention,
The separation mechanism is not particularly limited, but for example,
A driving force is transmitted through a screw shaft screwed to a shaft portion of a worm wheel that meshes with a worm gear that is rotated by a drive device, and a position adjusting block is provided so as to approach and separate from a slab, Attach a reduction cylinder with the rod facing the slab to the block, attach a convex mold to the rod tip of the reduction cylinder via a slide, and drive the worm gear according to the width of the slab to rotate the worm wheel After adjusting the distance between the blocks by moving the shaft back and forth, the compression cylinder is expanded and contracted to move the convex mold closer to and away from the cylinder to perform the width reduction of the slab, or a crankshaft that is rotated by a drive device. The eccentric cam is fixed, the base of the rod is externally fitted through the eccentric cam bearing, the mold is attached to the tip of the rod, and it rotates with the crankshaft. By that the eccentric cam, moved back and forth a rod, proximity a convex mold, it can be exemplified crank-type or the like which is moved away performing width reduction of the slab.

[0018]

【Example】

Embodiment 1 Details of the width reduction pressing apparatus of the present invention will be described below with reference to FIGS. 1 to 4 showing an embodiment. FIG. 1 is a perspective view showing a schematic configuration of a width reduction press device of the present invention, and FIG.
Is an explanatory view of a method of adjusting the lower roll level of the pinch roll on the die exit side, FIG. 3 shows a die of the width reduction press device of the present invention, and FIG. 3 (a) is a convex portion having rounded corners. FIG. 4B is a perspective view of a die having a sectional shape, FIG. 4B is a perspective view of a die having a trapezoidal to arcuate convex sectional shape, and FIG. 4 is a hot rolled steel sheet manufactured from a slab after width reduction of the present invention. It is an image figure of the seam flaw reduction which occurs in an edge. In FIG. 1, 1 is a convex mold of a press machine provided facing each other, 2 and 3 are two pairs of entry side pinch rolls provided immediately before the convex mold 1, and 4 and 5 are convex molds 1. With two pairs of exit side pinch rolls installed immediately after
When the slab 6 is width-reduced by the convex molds 1 and 1 of the pressing device, the convex mold 1 of the pressing device 1 is constrained by the inlet side pinch rolls 2 and 3 and the outlet side pinch rolls 4 and 5,
1 is configured to reduce the width.

As shown in FIG. 3, the convex mold 1 of the above-mentioned pressing apparatus has an inclined portion 7 and a parallel portion 8, and the inclined portion 7 and the parallel portion 8 have the following shapes, as shown in FIG. As shown in FIG. 3B, a convex portion 9 whose cross-sectional shape has rounded corners or a convex portion 10 having an arc-shaped cross-sectional shape is formed.
The convex molds 1 and 1 are close to a slab 6 not shown,
It is installed in a proximity / separation mechanism that is fixed to a block for position adjustment that is separated. 11 is a width reduction control unit,
Reference numeral 12 is a host computer 12 such as a hot rolling control unit. The width reduction control unit 11 is a host computer 1 such as a hot rolling control unit.
Based on the data such as the slab thickness, slab width, and slab width reduction input from 2, the distance between the blocks for position adjustment is adjusted to adjust the distance between the convex molds 1 and 1, and the convex mold. The vertical position of the block for position adjustment is controlled so that the center of the convex portion 9 or 10 of the mold 1 contacts the center of the side surface of the slab 6, and the slab thickening is calculated by the width reduction amount.
Position control is performed to lower the lower rolls 4a, 5a of the delivery side pinch rolls 4, 5 by a half of the slab thickness increase, and in accordance with this, the upper rolls 4b, 5b are rolled down at a constant pressure. .

With the above construction, the slab 6 is constrained by the inlet side pinch rolls 2 and 3 and the outlet side pinch rolls 4 and 5, so that the slab 6 is twisted during width reduction.
Lifting is prevented and stability is improved. further,
The width reduction control unit 11 calculates the slab thickness increase based on the width reduction amount, controls the position of the lower rolls 4a, 5a of the exit-side pinch rolls 4 and 5 so as to lower the slab thickness by half, and In addition, the upper rolls 4b and 5b are pressed down at a constant pressure, whereby the balance of the slab 6 before and after the convex mold 1 is maintained. Furthermore, the width reduction control unit 11
Is controlled so that the center of the convex portion 9 or 10 of the convex mold 1 abuts on the center of the side surface of the slab 6, so that the center of the convex portion 9 or 10 of the convex mold 1 is located at the center of the side surface of the slab 6. Contact each other, and the width reduction of the slab 6 is performed with a predetermined width reduction amount.

As shown in FIG. 4, by the width reduction by the convex mold 1, a concave portion having an arc shape or a rounded corner is formed on the side surface of the slab 6. The slab 6 that has been reduced in width is
When horizontally rolled by the rough rolling mill, the slab edge E moves to the side surface by the metal flow, and when further horizontally rolled by the finishing mill, the slab edge E moves to the front and back surfaces of the hot rolled steel sheet 13 by the metal flow. However, the seam width, which is located near the edge of the hot-rolled steel sheet 13 and indicates the distance from the edge 14 of the hot-rolled steel sheet 13 to the seam flaw, can be improved from the conventional 12 to 20 mm to about 3 to 6 mm. At the same time, by making the side surface recess of the slab 6 a circular arc shape or a recess having a rounded corner, it is possible to prevent the slab edge E from being internally folded. Also,
In the convex die 1 of the present invention, the width reduction control unit 11 controls the position of the center of the convex portion 9 or 10 so as to contact the center of the side surface of the slab 6, so that the hot-rolled steel sheet 13 has a uniform seam width level. Can be converted.

Example 2 SUS304 stainless steel having a thickness of 200 mm and a width of 12
A hot slab of 00 mm, with a convex height of 30 mm, R200
Using a width reduction press device for a convex die having an arc-shaped convex portion of mm, the width reduction amount is 20 to 350 mm while the slab is constrained by two pairs of pinch rolls arranged before and after the die.
(10 to 175 mm on one side) and width reduction, and then normal hot rolling to obtain a plate thickness of 3.2 mm and a plate width of 90.
Various hot rolled steel strips of 0 to 1230 mm were manufactured. For each of the various hot-rolled steel strips obtained, the seam width, which is the distance from the edge of the hot-rolled steel strip of the seam flaw, was measured using a scale. The result is shown in FIG. 5 together with the case where width reduction was not performed. As shown in FIG. 5, the seam width sharply decreases with an increase in the width reduction amount up to the width reduction amount of 50 mm, and when the width reduction amount is 100 mm or more, the seam width is 16 mm compared to the case without the width reduction amount. However, it is reduced to 1/4 of 4 mm or less.

For comparison, a hot slab extracted from a heating furnace of SUS304 stainless steel having a thickness of 200 mm and a width of 1200 mm was used, and the height of the convex portion was 30 mm and the height of R200 m was 200 mm.
Using the width reduction press device for the arc-shaped convex die having the arc-shaped convex portions of m, without using two pairs of pinch rolls arranged before and after the die, the width reduction amount of 150 mm (one side 75 m
After width reduction in m), a hot-rolled steel strip having a plate thickness of 3.2 mm and a plate width of 1100 mm was manufactured by ordinary hot rolling.
The distance from the obtained hot rolled steel strip tip and the width of the seam flaw from the hot rolled steel strip edge were measured using a scale. The result is that the slab is restrained by two pairs of pinch rolls arranged before and after the mold, and the width reduction amount is 150 mm (one side is 75 m).
FIG. 6 shows a case where a hot-rolled steel strip having a plate thickness of 3.2 mm and a plate width of 1100 mm was manufactured by the ordinary hot rolling after the width reduction in m) and a case where the width reduction was not performed.

As shown in FIG. 6, in the case of A in which the slab was restrained by the pinch rolls while the width was reduced by the method of the present invention, the seam width from the front end to the rear end of the hot-rolled steel strip was constant at 4 mm. In the case of B, which was width-reduced without restraining the slab, the seam width at the tip of the hot-rolled steel strip was almost the same as that of the method of the present invention, but it is considered that twisting occurred as the distance from the tip of the hot-rolled steel strip increased. An increase in seam width was seen. In the case of C with zero width reduction, the seam width was constant at 16 mm over the entire length.

[0025]

As described above, according to the present invention,
The seam width produced when hot-rolling stainless steel can be significantly reduced, and the product width can be improved by reducing the trim width of the edge portion.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a width reduction pressing device of the present invention. It is an image figure of the seam flaw reduction which occurs in the edge of the hot-rolled steel plate manufactured from the slab after width reduction of this invention.

FIG. 2 is an explanatory diagram of a method of adjusting a lower roll level of a pinch roll on the die exit side.

3A and 3B show a die of a width reduction pressing apparatus of the present invention, wherein FIG. 3A is a perspective view of a die having a convex cross-section with rounded corners, and FIG. It is a perspective view of the metal mold which changed the shape from a trapezoid to an arc.

FIG. 4 is an image diagram of mitigation of seam flaws generated at the edge of the hot-rolled steel sheet manufactured from the slab after width reduction according to the present invention.

FIG. 5 is a graph showing the relationship between press width reduction amount and seam width in Example 2.

FIG. 6 is a graph showing the relationship between the length from the tip of the product and the seam width between the method of the present invention and the comparative example in Example 2.

FIG. 7 is an image view of a seam flaw generated at an edge of a hot-rolled steel sheet manufactured from a slab subjected to width reduction with a flat die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Convex mold 2, 3 Entry side pinch roll 4, 5 Ejection side pinch roll 4a, 5a Lower roll 6,73 Slab 7 Inclined part 8 Parallel part 9, 10 Convex part 11 Width reduction control part 12 Upper computer 13 Hot rolling Steel plate 14,74 Edge 71 Material 72 Defect E Slab edge

Claims (2)

[Claims] 1. A hot pressing slab is continuously or intermittently run, and pressing dies having inclined portions and parallel portions which are provided on both sides in the width direction of the slab are made to approach and separate from each other to have a predetermined width. In the width reduction pressing method of the hot slab that performs the reduction, the hot slab is constrained by the pinch rolls on the inlet side and the outlet side in the line direction of the press die, and the convex cross-section has an arc shape or a convex shape with rounded corners. A width reduction pressing method for a hot slab characterized by performing width reduction using a die. 2. A hot pressing slab is continuously or intermittently run, and pressing dies having an inclined portion and a parallel portion, which are provided on both sides of the slab width direction so as to face each other, are moved close to or away from each other to have a predetermined width. In a width reduction press device for a hot slab that performs reduction, a pinch roll respectively disposed on the inlet and outlet sides of the press die in the line direction and an outlet side lower roll of the pinch roll are ½ of the slab thickness increase by width reduction. A hot work characterized by a combination with a width reduction control unit that lowers the convex shape of the convex mold of which the convex shape of the cross section is an arc shape or has a rounded corner of the convex shape and positions the center of the convex portion of the convex mold at the center of the side surface of the slab. Slab width reduction press machine.