JP5509648B2 - Method and apparatus for draining hot-rolled steel sheet during threading - Google Patents

Description

  The present invention relates to a method for draining hot-rolled steel sheets during passage, and particularly to a method and apparatus for removing water droplets on the upper surface of a hot-rolled steel sheet during passage in a hot rolling line.

The following techniques are known as methods for removing water droplets on the upper surface of a hot-rolled steel sheet during sheet passing in a hot rolling line.
In Patent Document 1, a cooling apparatus for hot-rolled steel that cools hot-rolled steel delivered from a finish rolling mill by injecting a cooling liquid from a plurality of cooling banks toward the hot-rolled steel between the plurality of cooling banks. Thus, there is disclosed a technique in which a draining nozzle for ejecting high-pressure fluid is provided, and the direction in which the high-pressure fluid is ejected from this nozzle is arranged in a direction in which the downstream side is not affected by the cooling liquid upstream from the nozzle.

Patent Document 2 discloses a technique in which water and air are mixed and sprayed from a draining nozzle during the hot run cooling of a hot thin plate continuous rolling line, and the cooling water staying on the steel plate is drained.
In Patent Document 3, the cooling water staying on the steel sheet conveyed from the line table is provided with a water supply header across the line table above the line table in the draining spray device, and high pressure water is supplied to the water supply header. A technique is disclosed in which a plurality of side spray nozzles that sprays onto a steel plate from the line table toward the outside in the direction perpendicular to the line are arranged.

  Patent Document 4 discloses two types of fluid ejection nozzles having different ejection widths in the steel plate width direction, and fluid ejection nozzles having a wider ejection width such that the ejection direction is directed to one edge side of the steel plate. A plurality of nozzles are arranged so as to be located upstream in the injection direction, and by injecting fluid from the plurality of fluid injection nozzles onto the upper surface of the steel plate, one of the upper surfaces of the steel plate is accompanied by the fluid ejected from the stagnant water on the upper surface of the steel plate. A technique for discharging from one edge to the other is disclosed.

  In Patent Document 5, in order to remove the cooling water staying on the upper surface of the stopped steel sheet from the upper surface of the steel sheet, a simultaneous water draining nozzle disposed on one side of the rolling line and perpendicular to the rolling line and also provided with the cooling device The technique which removes the stagnant water of the steel plate upper surface on a rolling line is disclosed by the group.

Japanese Patent Publication No.59-13573 JP-A-9-141322 Japanese Patent Laid-Open No. 11-123439 Japanese Patent Laid-Open No. 11-138207 JP 2003-33809 A

  In a hot rolling line, a flaw detection device for detecting wrinkles (various defective parts) in the surface of a hot-rolled steel sheet may be installed between the finish rolling mill and the winder to perform flaw inspection. . At this time, if the cooling water poured into the steel sheet from the cooling equipment on the exit side of the finishing mill remains as water droplets in the steel sheet surface, the remaining water droplets are erroneously detected as soot, and soot is detected. This leads to a decrease in accuracy. In addition, in the case of a wrinkle inspection device that observes the lower surface of the steel sheet from below the transport roll, problems such as water collecting in the observation window occur, leading to a decrease in wrinkle detection accuracy and a load of cleaning work for device maintenance. Will increase.

  However, all of the conventional draining means listed in the background art eliminate the stagnant water in the steel sheet surface from the viewpoint of ensuring the mechanical properties of the hot-rolled steel sheet product. Since it is insufficient, draining is performed by water jetting, so that some water droplets remain in the steel plate surface. That is, the conventional water injection type draining means cannot detect the wrinkles in the surface of the hot-rolled steel sheet before winding with high accuracy on-line.

The present invention provides a method and apparatus for draining a hot-rolled steel sheet when passing through the hot-rolled steel sheet, which solves the above-described problems and enables highly accurate online detection of wrinkles in the surface of the hot-rolled steel sheet before winding. Is as follows.
(Claim 1)
After being passed through a hot rolling line, the finish rolling mill, the cooling equipment, and the water-jet type draining equipment attached to the cooling equipment are successively finish-rolled, cooled and drained, and then subjected to a hull inspection with a hull detector, and then wound. A water draining method for a high-temperature steel sheet wound up by a take-up machine, the air wind direction from the air nozzle group installed on one side in the line width direction between the water-jet type water draining equipment and the soot detector to the upper surface of the steel sheet Injecting air substantially perpendicular to the plate passing direction at the same time and removing water droplets in the upper surface of the steel plate outside the same surface , the air discharge pressure of the air nozzle group and the section length of the installation section are expressed by the following formula (1) A method of draining hot-rolled steel sheet during threading, characterized in that it is obtained from (3) .

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(Claim 2 )
After finishing rolling, cooling and draining sequentially in the hot rolling line, finishing mill, cooling equipment and water injection type draining equipment attached to the cooling equipment, and then undergoing soot inspection with the soot detection device, A water draining device for a high temperature steel sheet wound up by a winder, wherein the air wind direction is a plate passing direction from one side in a line width direction between the water jetting water draining equipment and the wrinkle detecting device to the steel sheet upper surface. When you simultaneously injecting air substantially perpendicular, the water droplets in the steel plate top surface have a air nozzle group to be removed out of the surface, the section length of the discharge pressure and installation intervals of the air of the air nozzle group satisfies the following formula (1) A draining device for hot-rolled steel sheet passing through, which is obtained from (3) .

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  According to the present invention, it is possible to detect wrinkles with high accuracy in the on-line wrinkle inspection in the hot-rolled steel sheet surface before winding, and the false detection frequency is greatly reduced. The load of checking the wrinkles while rewinding the steel plate in the process is greatly reduced.

Schematic plan view showing an example of an air nozzle group according to the present invention Schematic showing the in-line arrangement of the air nozzle group according to the present invention ((a) plan view, (b) side view) Graph showing an example of purge execution status

  For example, as shown in FIG. 1, an air nozzle group 9 according to the present invention includes a nozzle 1 connected with an air pipe 2 in parallel, and the air pipe 2 is connected to each air pipe 2 via a common header pipe 3. 4 is configured to supply air. For example, as shown in FIG. 2, the air nozzle group 9 is disposed on one side in the line width direction between the water jetting draining equipment 8 and the soot detection device 10 in the hot rolling line. In order to efficiently remove (purge) water droplets on the upper surface of the steel plate 5 from one end in the steel plate width direction to the outside of the other end, the air jetted from the plurality of nozzles 1 Almost orthogonal (for example, crossing within a crossing angle of about 90 ° ± 3 °) and sprayed all at once. Further, it is preferable that the air wind direction has an inclination angle as small as possible (for example, more than 0 ° and about 3 ° or less) with respect to the upper surface of the steel plate 5.

  In FIG. 2, a steel plate 5 passed through a hot rolling line is rolled by a finishing mill 6 and then cooled by cooling water poured by a cooling facility 7. Although most of the cooling water (stagnating water) that has been poured and drifted on the plate surface is eliminated by the water-jet draining equipment 8 on the exit side of the cooling equipment 7, some water droplets remain. Conventionally, since it passes through the wrinkle detection device 10 in this state, there are not a few cases where a water droplet is erroneously detected as a wrinkle, and the wrinkle detection accuracy in the online wrinkle inspection is poor. However, in the present invention, the air nozzle group 9 installed between the water jetting drainer 8 and the soot detection device 10 ejects air in the air wind direction onto the upper surface of the steel sheet, so that water droplets are almost completely discharged. The soot detection accuracy in the online soot inspection is greatly improved. The steel plate 5 exiting the wrinkle detection device 10 passes through a pinch roll 11 and is wound up by a winder 12.

In designing the air nozzle group, it is preferable to determine the specifications using the following three equations.
The wind speed of the air discharged from the nozzle can be obtained by equation (1).

  The distance in the line width direction from the purge starting point at the position where the water droplet drifting at the nozzle side end of the steel plate reaches after t seconds is obtained by the equation (2).

  Further, the distance in the line length direction from the purge starting point at the position where the water droplet drifting at the nozzle side end of the steel plate reaches after t seconds can be obtained by Equation (3).

The air discharge pressure is determined from P _j , and the section length in which the air nozzle group is arranged is determined from the X value.
Water drop removal with a minimum air volume can be realized by designing the equipment of the draining device for draining plate according to the present invention using the solution obtained by simultaneous equations (1), (2), and (3).
The present invention (both method and apparatus) is a thick plate rolling line instead of a hot rolling line, and is cooled by a cooling bed instead of being wound by a winder. It can be applied to on-line wrinkle detection of a thick steel plate which is a kind of hot-rolled steel plate. By such application, it is possible to improve the reliability of on-line wrinkle detection of thick steel plates.

  In the Example, the air nozzle group 9 was installed in the form shown in FIG. 2 in the hot rolling line, and the water purge of water droplets was performed. The maximum line speed of this line is 1060 mpm (= 17.7 m / sec), and the line width is 3 m. FIG. 3 is a graph showing the purge execution status. In the same figure, along with the calculation curves according to the above-described formulas (1), (2), and (3), the values for which water droplets were sufficiently removed by the air purge experiment were plotted. The calculated curve is in good agreement with the experimental values. The correction coefficients of the nozzle used at this time are α = 7.2651 and β = 0.3143. In the present embodiment, the false detection rate of flaws (number of erroneously detected coils / number of coils subjected to on-line flaw inspection) was significantly reduced to about 1/14 compared to before installation of the air nozzle group.

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Air piping 3 Header pipe 4 Air piping 5 Steel plate 6 Finishing rolling mill 7 Cooling equipment 8 Water injection type draining equipment 9 Air nozzle group
10 Sputum detection device
11 Pinch roll
12 Winder

Claims (2)

After being passed through a hot rolling line, the finish rolling mill, the cooling equipment, and the water-jet type draining equipment attached to the cooling equipment are successively finish-rolled, cooled and drained, and then subjected to a hull inspection with a hull detector, and then wound. A water draining method for a high-temperature steel sheet wound up by a take-up machine, the air wind direction from the air nozzle group installed on one side in the line width direction between the water-jet type water draining equipment and the soot detector to the upper surface of the steel sheet Injecting air substantially perpendicular to the plate passing direction at the same time and removing water droplets in the upper surface of the steel plate outside the same surface , the air discharge pressure of the air nozzle group and the section length of the installation section are expressed by the following formula (1) A method of draining hot-rolled steel sheet during threading, characterized in that it is obtained from (3) .
Record

Here, V: wind speed on the steel sheet (purge air wind speed) [m / sec], Pj: injection pressure [MPa], L: line width direction distance from nozzle [m], α, β: correction determined by nozzle type coefficient.

Here, Y: line width direction distance [m] from the purge starting point, l: line width direction distance [m] between the nozzle and the steel plate end (nozzle side).

Here, X: line length direction distance from the purge starting point [m], V _r : line speed [m / sec].
After finishing rolling, cooling and draining sequentially in the hot rolling line, finishing mill, cooling equipment and water injection type draining equipment attached to the cooling equipment, and then undergoing soot inspection with the soot detection device, A water draining device for a high temperature steel sheet wound up by a winder, wherein the air wind direction is a plate passing direction from one side in a line width direction between the water jetting water draining equipment and the wrinkle detecting device to the steel sheet upper surface. When you simultaneously injecting air substantially perpendicular, the water droplets in the steel plate top surface have a air nozzle group to be removed out of the surface, the section length of the discharge pressure and installation intervals of the air of the air nozzle group satisfies the following formula (1) A draining device for hot-rolled steel sheet passing through, which is obtained from (3) .
Record

Here, V: wind speed on the steel sheet (purge air wind speed) [m / sec], Pj: injection pressure [MPa], L: line width direction distance from nozzle [m], α, β: correction determined by nozzle type coefficient.

Here, Y: line width direction distance [m] from the purge starting point, l: line width direction distance [m] between the nozzle and the steel plate end (nozzle side).

Here, X: line length direction distance from the purge starting point [m], V _r : line speed [m / sec].

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