JP2007319928A - Masking apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a masking apparatus which can prevent occurrence of unevenness of temperature in the strip width direction without fail by preventing overcooling in strip edge portions more effectively than ever, while suppressing deformation and wear in a slit section of nozzle or the masking apparatus itself, in a slit jet nozzle type cooling apparatus used for controlled cooling of a steel strip after hot rolling. <P>SOLUTION: The masking apparatus, which is used to intercept water stream sprayed toward the edge portions of the steel strip 1 separately from the water stream spouted through the slit jet nozzle 2, has box-type main bodies 5. In the front side of the main bodies 5, contacting with a slit section 3 at the tip of the slit jet nozzle 2 pointing to the width edge portions of the strip 1, slit type inlets 6 to conduct the water stream spouted from the slit section 3 into the main bodies 5 are arranged. In the side faces on the width edge sides of main bodies 5, outlets 7 to discharge the water stream conducted into the main bodies 5 are prepared, while the main bodies 5 are made movable back and forth in the strip width direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a masking device used in a slit jet nozzle type cooling device for cooling a thick steel plate after hot rolling.

  In the manufacturing process of thick steel plates, on-line controlled cooling technology for forcibly cooling a thick steel plate immediately after hot rolling (hereinafter also simply referred to as “steel plate”) by online water cooling is widely applied. According to such on-line controlled cooling technology, high strength and high toughness can be imparted to the steel sheet, and cost reduction effects such as reduction of alloy elements added to the steel and omission of heat treatment can be obtained.

  However, in general, a hot-rolled thick steel plate is not necessarily uniform in temperature distribution, plate shape, surface properties, etc., so temperature unevenness is likely to occur during cooling, resulting in deformation, residual stress, etc. in the steel plate after cooling. This causes problems such as delays in delivery due to correction, loss of yield due to cut-off of defective parts, and operational problems.

  As a cooling device that minimizes such a problem, a cooling device that injects high-pressure, large-flow cooling water from a slit jet nozzle installed obliquely downward at a position close to the steel plate with respect to the upper and lower surfaces of the steel plate. It has come to be used.

  Usually, a steel plate immediately after hot rolling has a temperature distribution in which the temperature at both ends of the plate width is lower than the temperature at the center portion of the plate width. In order to correct such temperature distribution, the cooling capacity is controlled so that the cooling effect on both ends of the sheet width becomes smaller than the cooling effect on the center part during cooling, and both ends of the sheet width generated in the hot rolling stage are controlled. It is necessary to reduce the supercooled part of the part. For this reason, the following proposals have been made as means for reducing the supercooled portions at both ends of the plate width with respect to the slit jet nozzle type cooling device.

  For example, by pressing a shield that can move in the plate width direction that can shield the slit portion to the slit portion at the tip of the slit jet nozzle with a pressing mechanism, the water flow that is sprayed to the plate width end portion is blocked, thereby A masking device that attempts to prevent overcooling of a part has been disclosed (see Patent Document 1).

  In addition, by providing a streamlined water flow control body that can move in the plate width direction at a fixed distance downstream from the slit jet nozzle, the water flow flowing to the plate width end is restricted, thereby supercooling the plate width end. A masking device that attempts to prevent this is disclosed (see Patent Document 2).

  On the other hand, it is not a slit jet nozzle method, but in a cooling device that cools the steel sheet by dropping a laminar water film from the slit lamina nozzle onto the upper surface of the steel sheet after hot rolling, masking both ends of the water film flow In addition to blocking (masking) with scissors, a water film guide hanging from the bottom of the top of the masking scissors is provided to prevent contraction of the water film flow, thereby preventing uneven temperature distribution in the plate width direction. A masking device is disclosed (see Patent Document 3).

  However, in the masking device described in Patent Document 1, an attempt is made to ensure the sealing performance between the slit portion of the nozzle and the shield using a pressing mechanism, but forcibly pressing and blocking a high-pressure water flow, Since the shield itself is deformed by water pressure, or the slit portion of the nozzle is worn by the scale in the cooling water or is thermally deformed by radiant heat from the steel plate, there is a problem in maintenance.

  Further, in the masking device described in Patent Document 2, since the water flow control body is only provided at a position away from the nozzle without directly masking the plate width end portion, the plate width end portion is provided. In addition, it is inevitable that high-pressure cooling water directly collides. And since the cooling ability in a high-pressure water flow is mainly due to a collision, this masking device cannot sufficiently obtain the effect of preventing overcooling of the plate width end.

In addition, in the slit lamina type cooling device described in Patent Document 3, since a relatively low pressure and small flow rate of cooling water is used, the masking trough is installed away from the nozzle as shown in FIG. Even so, there will be no problems such as water bounce and overflow. However, because the slit jet nozzle method uses much higher pressure and cooling water than the slit lamina nozzle method, if the masking trough is installed away from the nozzle as described above, problems such as water flow rebound and overflow will occur. Therefore, it is impossible to simply apply this configuration.
Japanese Patent Laid-Open No. 6-285531 JP-A-10-216824 JP-A-5-138229

  Therefore, the present invention provides a slit jet nozzle type cooling device used for controlled cooling of a steel plate after hot rolling, while suppressing deformation and wear of the slit portion of the nozzle and the masking device itself, and the plate width end portion of the steel plate. An object of the present invention is to provide a masking device that can reliably prevent the occurrence of temperature unevenness in the plate width direction by more effectively preventing overcooling of the plate.

According to the first aspect of the present invention, the slit jet nozzle that blows a water flow from the upstream side of the pass line toward the downstream side on at least one of the upper and lower surfaces of the steel sheet after hot rolling is a sheet width direction of the steel sheet. A steel plate accelerated cooling device provided in the masking device used for blocking a water flow sprayed from a slit jet nozzle to a plate width end portion of the steel plate, and having a box structure body A slit-like introduction that abuts the slit portion at the tip of the slit jet nozzle directed to the plate width end portion of the steel plate on the front surface of the main body and introduces a water flow ejected from the slit portion into the main body. And a discharge port for discharging the water flow introduced into the main body. A masking device characterized by comprising a mechanism that can advance and retreat in the width direction.

  According to a second aspect of the present invention, in the masking apparatus according to the first aspect, the main body is formed such that its cross-sectional area in the pass line direction gradually increases from the central portion to the end portion of the plate width. It is.

  According to the masking device of the present invention, a high-pressure water flow from the slit portion of the slit jet nozzle toward the plate width end is passed through the main body from the inlet of the masking device and discharged from the discharge port to the outside of the plate width end. As a result, a high-pressure water flow does not directly collide with the plate width end portion, and overcooling of the plate width end portion can be more effectively prevented. As a result, temperature unevenness does not occur in the width direction of the plate, deformation and residual stress are prevented from occurring in the cooled steel plate, omission of correction work, improvement of product yield, reduction of operational troubles. Many industrial advantageous effects are brought about.

  Further, according to the masking device according to the present invention, instead of forcibly pressing and blocking the high-pressure water flow toward the plate width end as in the invention described in Patent Document 1 above, Since the discharge is performed to the outside, deformation and wear of the slit portion of the nozzle and the shielding plate itself can be suppressed, and the maintenance cost can be reduced.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

Embodiment
FIG. 1 is a perspective view showing an outline of an accelerated cooling apparatus using a masking apparatus according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view taken along line AA in FIG.

  As shown in FIG. 1, the accelerated cooling apparatus has a slit jet nozzle 2 installed in the plate width direction of the steel plate 1 above the pass line, and on the upper surface of the steel plate 1 after hot rolling, upstream of the pass line. It is comprised so that a water flow may be sprayed toward the downstream from the side.

  The masking device 4 has a box-shaped main body 5, and a slit-like introduction port 6 is provided on the front surface of the main body 5, and heads toward the plate width end portion of the slit portion 3 at the tip of the slit jet nozzle 2. The water flow that abuts against the portion and is ejected from the portion is introduced into the main body 5. Further, as shown in FIG. 2, it is preferable that the lower end portion 6a of the inlet port 6 is extended obliquely upward to the front, and is formed so as to be in close contact with the lower end surface 3a of the slit portion 3 from below. It can be introduced into the main body 5 with almost no leakage.

  Moreover, the discharge port 7 is provided in the plate width end side surface of the main body 5 of the box structure, and the water flow introduced into the main body 5 is configured to be discharged to the outer side of the width end of the steel plate 1. . As shown in FIG. 1, the discharge port 7 preferably has a structure in which the side surface of the main body 5 on the side of the plate width end portion is fully opened. Thereby, it is prevented that the pressure of the high-pressure water flow is excessively applied to the masking device 4, and damage to the slit portion 3 and the masking device 4 can be more reliably prevented.

  The slit-like inlet 6 of the masking device 4 is brought into contact with a part of the slit portion 3 of the slit jet nozzle 2, but the width of the slit portion 3 that comes into contact changes depending on the width of the steel plate to be cooled. Therefore, it is formed long with a margin. For this reason, the portion on the side of the plate width end portion of the inlet 6 may come off the slit portion 3. Therefore, the water flow introduced into the main body 5 from the portion in contact with the slit portion 3 in the introduction port 6 may leak out from the portion out of the slit portion 3 in the introduction port 6. Since it is sufficiently outside the plate width, no water is applied to the end of the steel plate 1 and there is no problem.

  Further, the masking device 4 (main body 5) is configured to be able to advance and retreat in the plate width direction according to the change in the plate width of the steel plate 1 to be cooled. As shown in FIG. 1, the masking device 4 is arranged at both ends of the plate width, 11 is a drive device for moving the masking device 4 in the plate width direction, and the connection between the masking device 4 and the drive device 11 is as follows. The screw screw 8 passed in the plate width direction is employed.

  The connection between the masking device 4 (main body 5) and the driving device 11 will be described in more detail. The screw screw 8 is passed in the plate width direction in the vicinity of the vicinity of the tip of the slit jet nozzle 2, and the female screw portion formed on the upper portion of the main body 5 of the masking device 4 is screwed together. The screw screw 8 is rotated by a motor 11 via a gear box 9 and a speed reducer 10, and the masking device 4 (main body 5) disposed at both ends of the plate width by the rotation of the screw screw 8 has a line center as a symmetry axis. It is configured to always move symmetrically. The position of the masking device 4 (main body 5) can be set by a PLG (pulse logic generator) 12.

  Moreover, as shown in FIG. 1, it is preferable that the main body 5 is formed so that the cross-sectional area in the pass line direction gradually increases from the central part to the end part of the plate width. As a result, the pressure of the high-pressure water flow decreases when passing through the main body 5 and is smoothly discharged from the discharge port 7. As shown in FIG. 1, the structure in which the cross-sectional area in the pass line direction gradually increases from the central part to the end of the plate width is a trapezoidal shape in which the horizontal cross section of the main body 5 extends from the central part to the end of the plate width. The rear surface of the box structure main body 5 may be slanted (that is, the end side protrudes rearward from the plate width central side). In addition, by making the rear surface of the main body 5 slant in this manner, the angle change in the direction of the water flow blown from the slit portion 3 becomes smaller than when the rear surface of the main body 5 is parallel to the front surface, and the masking device 4 is reduced, and damage to the apparatus can be prevented more reliably. If the angle at which the rear surface of the main body 5 is inclined is too small, a sufficient pressure reduction effect cannot be obtained, and if it is too large, the apparatus becomes excessively large. Recommended.

(Modification)
In the above embodiment, the example in which the masking device according to the present invention is applied to the acceleration cooling device in which the slit jet nozzle is provided only on the upper surface side of the steel plate is shown. However, the acceleration in which the slit jet nozzle is provided only on the lower surface side of the steel plate. Naturally, the present invention can also be applied to a cooling device, and further to an accelerated cooling device provided with slit jet nozzles on both the upper and lower surfaces of a steel plate.

  Moreover, in the said embodiment, although the example which used the screw screw was shown as a mechanism which enables a masking apparatus to advance / retreat to a board width direction, it is not limited to this, For example, you may use a wire.

  In the accelerated cooling device in which the slit jet nozzles 2 are provided on both the upper and lower surfaces of the steel plate 1 after hot rolling, each slit jet nozzle 2 has 200 mm portions at both ends of the plate width of the slit portion 3. In order to mask the above, the following various masking apparatuses 4 were attached, and the steel sheet after hot rolling with a plate width of 2.5 m, a length of 15 m, and a thickness of 50 mm was passed at a speed of 12 m / min for cooling.

(Comparative Example 1)
As a result of trial use of the masking device 4 in which a flat plate was attached to the slit portion 3 (see FIG. 3), the flat plate was bent in a short time after the high-pressure water flow started, and a large amount of water leaked. Since there is no way for water to escape, it is considered that the flat plate was deformed because it could not withstand the pressure of high-pressure water.

(Comparative Example 2)
As the masking device 104, a T-shaped cross-section in which another short plate was welded to the flat plate at a substantially right angle, and the short plate portion inserted into and pasted into the slit portion 3 (see FIG. 4) was tried. As a result, although the flat plate did not bend, there was water leakage and the temperature distribution in the width direction of the plate was greatly deteriorated. Although the strength of the masking device itself has been improved by having a T-shaped cross section, the slit width is reduced due to wear of the slit portion 3 on the scale in the cooling water or deformation due to radiant heat from the steel sheet due to long-term use. It is considered that it is not uniform in the longitudinal direction, and it is virtually impossible to complete the seal even if the short plate is inserted into the slit portion 3.

(Invention Example 1)
As the masking device 4, the main body 5 has a box structure, a slit-like introduction port 6 is provided on the front surface, a discharge port 7 is provided on the side surface on the plate width end side, and only the central portion on the rear plate width side is horizontal. What was formed in the R shape in the cross section (refer FIG. 5) was tried. As a result, a slight water leak occurred, and the temperature distribution in the plate width direction was slightly deteriorated, but was within an allowable range. Although the slight water leakage occurred in this way, the direction of the water flow can be smoothly changed in the R-shaped portion, but the plate width end side of the rear surface is formed in parallel with the front surface. This is presumably because the cross-sectional area of the channel did not increase, and the effect of reducing the pressure could not be sufficiently obtained.

(Invention Example 2)
The masking device 4 is changed to a structure in which the rear surface of the main body is inclined by 5 ° (that is, the end side protrudes backward from the center side of the plate width) in the first invention example (see FIG. 1). Tried. As a result, no water leak occurred. In addition, as shown in FIG. 6, when no masking device is used (prior art), the temperature difference between the center portion and the end portion of the plate width immediately after hot rolling is maintained almost as it is during cooling. When this masking device is used (invention), the temperature difference disappears in a short time after the start of cooling, and a very uniform temperature distribution is obtained until the cooling is completed. It was. The data in FIG. 6 is for both the prior art and the present invention, cooling with a slit jet nozzle only for 5 seconds after the start of cooling, and subsequently for 20 seconds, a normal pipe lamina nozzle on the upper surface side of the steel plate and a normal spray nozzle on the lower surface side of the steel plate It was obtained by cooling with

It is a perspective view showing the outline of the acceleration cooling device using the masking device concerning an embodiment. FIG. 2 is a partial cross-sectional view taken along line AA in FIG. 1. It is a longitudinal cross-sectional view which shows the masking apparatus of the comparative example 1. It is a longitudinal cross-sectional view which shows the masking apparatus of the comparative example 2. It is a horizontal sectional view of the inlet level showing the masking device of Invention Example 1. It is a graph which shows the relationship between the cooling time and steel plate temperature at the time of the cooling by the accelerated cooling apparatus of the steel plate after hot rolling.

Explanation of symbols

1: Steel plate 2: Slit jet nozzle 3: Slit portion 3a: Lower end surface 4: Masking device 5: Main body 6: Inlet 6a: Lower end 7: Discharge port 8: Screw screw 9: Gear box 10: Reducer 11: Drive Equipment (motor)
12: PLG

Claims (2)

Accelerated cooling of the steel sheet, in which a slit jet nozzle that blows a water flow from the upstream side of the pass line toward the downstream side is provided on at least one of the upper and lower surfaces of the steel sheet after hot rolling. In the apparatus, a masking device used for blocking a water flow sprayed on a plate width end portion of the steel plate out of the water flow ejected from the slit jet nozzle,
It has a box structure main body, and a front surface of the main body is brought into contact with a slit portion at the tip of the slit jet nozzle directed to the plate width end portion of the steel plate, and a water flow ejected from the slit portion is introduced into the main body. A slit-like introduction port is provided, and a discharge port for discharging the water flow introduced into the main body is provided on the side surface on the plate width end side of the main body, and the main body can be advanced and retracted in the plate width direction. A masking device comprising a mechanism for performing the above operation.   2. The masking device according to claim 1, wherein the main body is formed such that a cross-sectional area in a pass line direction gradually increases from a central portion to an end portion of the plate width.

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