JP5482375B2 - Descaling device - Google Patents

Description

  The present invention relates to a descaling apparatus for performing descaling by jetting a jet fluid such as high-pressure water during conveyance to a metal body before rolling. In addition, unrolled materials, such as a slab, and rough-rolled materials (rough bar etc.) are also contained in the metal body before rolling. In short, any metal body that needs to be rolled in the process after the descaling process may be used.

For example, as described in Patent Document 1, descaling is performed by spraying high-pressure water from a spray nozzle of a descaling apparatus onto a steel plate.
At this time, Patent Document 1 describes that the angle of attack of the injection nozzle is set in a range of 0 to 10 degrees.

Japanese Patent Application Laid-Open No. 11-266739 Japanese Utility Model Publication No. 60-66611

The jetted high-pressure water collides with the surface of the steel material, and then a part of the high-pressure water rebounds to become rebound water. As described above, when the angle of attack of the injection nozzle is small, a part of the rebound water may collide with a descaling device such as the injection nozzle or the header.
Here, when trying to improve the descaling efficiency, the collision pressure of the jet water will be increased, but the pressure of the rebound water that collides with the header or the like is increased accordingly, This can cause damage to the headers where the splashed water collides. That is, it leads to the lifetime reduction of the header etc. which comprise a descaling apparatus.

Patent Document 2 describes a shielding plate similar to the protector of the present invention, but the angle of attack of the nozzle is 0 degrees, and the nozzle injection axis and the center of the hole are coaxial. The effect of the present invention is not achieved.
The present invention has been made paying attention to the above points, and has an object to improve the descaling efficiency and suppress the life reduction of the descaling apparatus.

In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is a descaling device including an injection nozzle that injects an injection fluid toward a metal plate being conveyed,
The angle of attack of the spray nozzle with respect to the metal plate being conveyed is set to 1 degree or more,
A protector is provided between the metal plate and the injection nozzle to prevent rebound water from the metal plate from returning to the injection nozzle side,
For the protector, open a protector hole for allowing the jet fluid to pass from the jet nozzle toward the metal plate,
In the direction along the moving direction of the metal plate, the distance from the position of the injection port of the injection nozzle to the upstream end position of the metal plate in the protector hole is 30 mm or less.

Next, in the invention described in claim 2, with respect to the configuration described in claim 1, the angle of attack of the injection nozzle is set to 1 degree or more and 6 degrees or less,
In a direction along the moving direction of the metal plate, the distance from the position of the injection port of the injection nozzle to the upstream side end position of the metal plate of the protector hole is set to 15 mm or more and 30 mm or less. is there.

  Next, the invention described in claim 3 is directed to the structure described in claim 1 or claim 2, when the center of the protector hole is viewed from the direction orthogonal to the moving direction of the metal plate, And the cross-sectional shape of the protector hole is a circular shape or an elliptical shape having a major axis in the conveying direction of the metal plate.

  ADVANTAGE OF THE INVENTION According to this invention, the lifetime reduction of a descaling apparatus can be suppressed, improving descaling efficiency.

It is a schematic diagram which shows the arrangement position of the descaling apparatus which concerns on embodiment based on this invention. It is a schematic diagram which shows arrangement | positioning of an injection nozzle. It is a side view which shows the protector which concerns on embodiment based on this invention. It is a top view which shows the protector hole which concerns on embodiment based on this invention. It is a figure explaining (psi) '.

Next, embodiments according to the present invention will be described with reference to the drawings.
In this embodiment, the steel plate 1 before hot rolling will be described as an example of the metal plate.
That is, as shown in FIG. 1, the headers 2 of the descaling devices are arranged at substantially symmetrical positions in the vertical direction across the steel plate 1 conveyed along the pass line PL. Each header 2 is arranged with its axis directed in the width direction of the steel plate 1, and the header 2 is provided with a plurality of injection nozzles 3 along the axial direction.

Each injection nozzle 3 can inject high-pressure water as an injection fluid toward the steel plate 1. As shown in FIG. 2, which is a schematic diagram, each of the injection nozzles 3 is set with an attack angle θ, a twist angle ψ, and a spread angle φ.
The angle of attack θ of each injection nozzle 3 is set, for example, in the range of 1 to 11 degrees, preferably 1 to 6 degrees. In order to improve descaling efficiency, the angle of attack θ is preferably small. The angle of attack θ is an inclination angle obtained by positively taking the angle inclined to the upstream side of the steel plate 1 with respect to the injection port 3a of the injection nozzle 3 with the direction orthogonal to the conveying direction of the steel plate 1 being 0 degrees.

A plate-like protector 4 is interposed between the header 2 and the injection nozzle 3 and the steel plate 1 as shown in FIG. The protector 4 has a size that prevents at least the rebound water from the steel plate 1 from returning to the injection nozzle 3 side. The protector 4 may be supported by a support member (not shown) that supports the header 2 and the like.
As shown in FIG. 4, a plurality of protector holes 5 for allowing the spray fluid to pass from each spray nozzle 3 toward the steel plate 1 are opened in the protector 4 corresponding to the spray nozzle 3. In the present embodiment, each protector hole 5 has a circular cross section, and the center of the protector hole 5 coincides with or substantially coincides with the position of the injection port 3a of the injection nozzle 3 when viewed from the direction orthogonal to the moving direction of the steel plate 1. I am letting. In FIG. 4, the arrangement direction of the holes 5 is a direction along the axial direction of the header 2.

Moreover, the diameter Dp of each protector hole 5 is set to 30 mm or more and 60 mm or less. In order to allow the water jetted from the spray nozzle 3 to pass with an angle of attack θ of 1 degree or more, 30 mm or more is considered necessary, so it was set to 30 mm or more. Moreover, it can prevent that bounce water passes the protector hole 5 by setting to 60 mm or less as mentioned later.
By the said structure, in the direction along the moving direction of the steel plate 1, the distance from the position of the injection port 3a of the said injection nozzle 3 to the metal plate upstream edge part position of the said protector hole 5 is set to 30 mm or less. Is possible.

  The opening cross section of the protector hole 5 does not need to be circular, and may be an elliptical shape having a major axis in a direction along the moving direction of the steel plate 1 or a polygonal hole. In addition, the cross section of each protector hole 5 is necessarily circular, and the center of the protector hole 5 coincides with or substantially coincides with the position of the injection port 3a of the injection nozzle 3 when viewed from the direction orthogonal to the moving direction of the steel plate 1. There is no need.

However, it is preferable that the protector holes 5 of the adjacent injection nozzles 3 are not in communication. This is to suppress as much as possible the rebound water from the spray water of the adjacent spray nozzle 3 from passing.
With this configuration, the angle of attack θ of the injection nozzle 3 can be lowered to improve the descaling efficiency, and the header 2 and the like can be protected from the splashed water. As a result, the life reduction of the descaling apparatus can be suppressed.

(Description of the above specifications)
When the angle of attack θ is examined, the water jetted from one jet nozzle 3 is jetted with a predetermined angle range along the conveying direction of the steel sheet 1 with the angle of attack θ interposed therebetween.

Adjacent water jets interfere with each other after colliding with the steel sheet 1 and have the disadvantage of weakening the collision force. On the other hand, the inventors of the present application have examined that the collision force reduction in the interference area can be avoided as the angle of attack θ is reduced.
Further, the jet water rebounds due to the collision with the steel plate 1, but the minimum reflection angle of the rebound water is equal to the incident angle. For this reason, there is a possibility that the water bounces back and contacts the header 2 or the like as the angle of attack θ approaches zero.

Here, the equipment restrictions (conditions) in reducing the angle of attack θ will be discussed with reference to FIG.
It is an equipment condition for lowering the angle of attack θ that the rebound water of the jet water after colliding with the steel plate 1 does not enter the protector hole 5. That is, the jet water has a width as described above, and the jet stream line located on the most downstream side in the jet width must not enter the protector hole 5.

Here, the condition that the rebound water by the jet stream line located on the most downstream side in the jet width does not enter the hole of the protector 4 is the following equation (1).
Y> Z (1)
Here, Y is the distance from the center of the header 2 to the position where the bounce water by the jet stream line located on the most downstream side in the jet width contacts the protector 4. Z is a distance from the center of the header 2 to the upstream end position of the steel plate 1 in the protector hole 5.

  And from the geometrical arrangement shown in FIG. 3, Y and Z can be expressed by the following equations.

here,
R: radius of the header 2 (mm)
r _n: nozzle projection amount from the header 2 (mm)
L: Nozzle level from pass level PL (mm)
t: Plate thickness of the steel plate 1 (mm)
θ: angle of attack (rad)
φ: Nozzle 3 spray spread angle (rad)
ψ: Nozzle twist angle (rad) when viewed in a plane
Dp: diameter of the protector hole 5

Here, the center of the protector hole 5 is set at the same position as the injection port 3 a of the nozzle 3 when viewed from the direction orthogonal to the conveying direction of the steel plate 1.
Substituting Equation (2) and Equation (3) into Equation (1) yields Equation (4) below.

Further, φ ′ is obtained with reference to FIG.
From FIG. 5, φ ′ can be calculated as follows.

  And from the formulas (5) and (6), φ ′ can be expressed by the following formula.

  The smaller the angle of attack θ, the better. However, in order to prevent the splashed water from the steel plate 1 from entering the protector hole 5 and damaging the header 2, the angle of attack θ is determined by the above equations (4) and (7). Need to be satisfied.

Here, the general specifications of the descaling apparatus are as follows.
L = 100-300mm
R = 50-130mm
r _n = 75 to 150 mm
t = 30-55mm
φ = 34 to 50 degrees ψ = 10 to 15 degrees Here, when the nozzle level L is low, the steel plate 1 collides with the nozzle, but when it is high, the collision pressure decreases. It is set from this viewpoint. The radius R of the header 2 depends on the descaling water pressure and the amount of water. Nozzle projection amount r _n from the header 2 is determined by the specifications of the nozzle 3.

When the diameter Dp of the protector hole 5 satisfying the expressions (4) and (7) was determined within the range of the general specifications as described above, the diameter Dp was in the range of 30 mm to 60 mm.
Here, the protector 4 level hp was set to (L-20) or less in consideration of a margin of 20 mm as the protrusion amount of the nozzle 3 from the header 2.

  Further, the angle of attack θ is preferably close to 0 degrees in order to improve descaling efficiency. Considering this, the angle of attack θ is set to be small and from 1 degree to 6 degrees as the angle at which the rebound water may collide with the header 2. When the angle of attack θ is 0 degree, the water bounces back to the protector hole 5 and the water returns, so the lower limit value of the angle of attack θ is set to 1 degree.

  Further, since the protector hole 5 has a circular cross section and the protector hole 5 is aligned with the center of the nozzle 3 injection port 3a in plan view, the extreme end position on the upstream side from the center of the nozzle 3 injection port 3a in plan view. , (Dp / 2). Therefore, what is necessary is just to set so that the upstream edge part position in the protector hole 5 may become the range of (30/2)-(60/2) from the center of the nozzle 3 injection port 3a, ie, 15 mm or more and 30 mm or less.

  If the protector hole 5 is set as described above, even if the angle of attack θ is a small angle such as 1 degree or more and 6 degrees or less and the descaling efficiency is improved, the header 2 and the like are prevented from being damaged by the splashing water. The angle of attack θ may be set larger than 6 degrees.

  That is, in the above-mentioned use range, by providing the protector 4 with the protector hole 5 diameter Dp of φ30 to 60 mm and the protector 4 level hp ≦ L-20, it is possible to protect the splashed water from rebounding. It is possible to reliably reduce the angle θ.

The experiment was conducted under the following conditions.
In addition, it is a case where the nozzle 3 is arrange | positioned up and down with respect to the pass line PL of the steel plate 1. FIG.
Descaling pressure: 500 kgf / cm ²
Header water volume (descaling water volume): 5.9 m ³ / min
Adjacent nozzle pitch: 65 mm
Number of nozzles: 27 on top, 27 on bottom,
Header width: 1755mm
Nozzle level: Top 166 min, Bottom 111 mm (pass level reference)
Nozzle protrusion amount: 77.6 mm, header: 127 mm (φ254 / 2)
Material conditions Steel plate thickness: 30 mm to 55 mm, plate passing speed: about 40 m / min
Spray water spread angle: 34 degrees, Nozzle 3 twist angle: 10 degrees Protector hole 5 Upper: 60 mm, Lower: 30 mm, The center of the protector hole 5 is made to coincide with the center of the nozzle 3 injection port 3a.
Brochure level hp Top: 141mm, Bottom: 60mm
The experiment was conducted at an attack angle θ of 15 degrees, 11 degrees, and 5 degrees.

(result)
At any angle of attack θ, the header 2 was not damaged by the splashed water.
In addition, the collision pressure at each angle of attack θ was obtained. The result is shown.
Angle of attack θ = 15 degrees: Impact pressure = 2.8 MPa
Angle of attack θ = 11 degrees: Impact pressure = 3.5 MPa
Angle of attack θ = 5 degrees: Impact pressure = 4.7 MPa
Thus, it was found that the collision pressure can be increased without changing the injection pressure by reducing the angle of attack θ.

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Header 3 Injection nozzle 3a Injection port 4 Protector 5 Protector hole Dp Protector hole diameter hp Brochure level L Nozzle level PL Pass line θ Attack angle

Claims (3)

In a descaling device having an injection nozzle for injecting an injection fluid toward a metal plate being conveyed,
The angle of attack of the spray nozzle with respect to the metal plate being conveyed is set to 1 degree or more,
A protector is provided between the metal plate and the injection nozzle to prevent rebound water from the metal plate from returning to the injection nozzle side,
For the protector, open a protector hole for allowing the jet fluid to pass from the jet nozzle toward the metal plate,
A descaling apparatus characterized in that, in a direction along the moving direction of the metal plate, a distance from the position of the injection port of the injection nozzle to the position of the upstream end portion of the protector hole on the metal plate is set to 30 mm or less. The angle of attack of the injection nozzle is set to 1 to 6 degrees,
The distance from the position of the injection port of the injection nozzle to the metal plate upstream side end position of the protector hole in the direction along the moving direction of the metal plate is set to 15 mm or more and 30 mm or less. 1. A descaling apparatus according to 1.   When the center of the protector hole is viewed from the direction orthogonal to the moving direction of the metal plate, it matches or substantially matches the position of the injection port of the injection nozzle, and the cross-sectional shape of the protector hole is circular or has a long diameter in the conveying direction of the metal plate The descaling apparatus according to claim 1, wherein the descaling apparatus has an elliptical shape directed toward the surface.

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