JP3265249B2 - Descaling device and hot rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a descaling device used in a hot rolling plant , and the descaling device .
The present invention relates to a hot rolling method using an apparatus .

[0002]

2. Description of the Related Art Generally, in hot rolling, a steel sheet temperature is 700.
In order to perform rolling at a temperature of from 1 to 1100 ° C, the material to be rolled is heated to about 1000 to 1300 ° C in a heating furnace. For this reason, an oxide scale is generated on the surface of the material to be rolled, and when rolling is performed in a state where the oxide scale is on the surface of the material to be rolled, the oxide scale bites into the surface of the steel sheet, causing scale flaws. .

To prevent this, high-pressure water is sprayed on the surface of the steel sheet immediately before rolling to remove oxide scale. This process is called descaling. Generally, as shown in FIGS. 6 and 7, a descaling device that performs a descaling process includes descaling headers 2 arranged on the upper side and the lower side of the conveyed steel sheet 1 respectively. Is provided with a plurality of nozzles 3 along the width direction of the steel plate 1. Each nozzle 3 has a steel plate 1
And has an injection angle α that faces in the opposite direction to the steel sheet transport direction P, that is, the high-pressure water 4 is received and injected in the transport direction P.

Then, high-pressure water 4 is injected from each nozzle 3 toward the surface of the steel sheet 1 by blast injection, and an oxide scale on the surface of the steel sheet 1 is removed by an impact when the high-pressure water 4 collides.

At this time, high-pressure water 4
The high-pressure water 4 sprayed from each nozzle 3 is sprayed in the width direction of the steel plate 1 so that a predetermined spray width A is sprayed.
And the high-pressure water 4 injected from the adjacent nozzles 3 has a portion that overlaps in the width direction of the steel plate 1 (hereinafter, referred to as a spray wrap portion R). Is set to

Here, in the spray wrap portion R, the impact force applied to the surface of the steel sheet 1 is reduced due to the mutual interference between the high-pressure waters 4 injected from the adjacent nozzles 3 and the descaling ability is reduced. The oxide scale generated on the steel types (common steel, low-carbon steel, ultra-low-carbon steel, etc.) occupying the majority has good peelability, so that the oxide scale on the surface of the steel sheet 1 passing through the spray wrap portion R also has the high pressure sprayed as described above. Water 4
Is removed without any problem.

However, in steel sheet 1 of a steel type in which the content of Si or Ni is as high as 0.2 to 2.0% by weight in total or in total, oxide scale with poor releasability is generated. With the nozzle arrangement in the apparatus, the oxide scale passing through the spray wrap R interfering with the injected high-pressure water 4 cannot be sufficiently removed. As a result, the oxide scale remains on the surface of the steel sheet 1 having passed through the spray wrap portion R, and the remaining oxide scale causes
After rolling, scale flaws 20 called red scales are generated as shown in FIG.

The scale flaws 20 (red scale) can be removed by washing with an acid in a pickling process. However, the steel sheet 1 having scale flaws has a large surface roughness after pickling.
Because it does not look good, it is a second-class product.

Further, in the steel type high content of Si and Ni, for example as in steels for the frame of the track, there are those obtained good fatigue properties, the increase in the surface roughness is fatigue strength It is not desirable from the viewpoint of securing

On the other hand, as shown in FIG. 9, the direction of the injection angle of the adjacent nozzles 3 is alternately changed and arranged, that is, the injection of the high-pressure water by the adjacent nozzles 3 is alternately received and injected. It is conceivable that the nozzle 3 is installed such that the high-pressure water 4 does not interfere with the spray wrap portion R, which is the overlap portion of the high-pressure water 4 as viewed from the steel sheet transport direction P.

Prior to this improvement, an injection experiment was performed with a single nozzle 3, and the descaling capability of the high-pressure water 4 ejected from the nozzle 3 when the nozzle 3 was tilted in the direction of conveying the steel sheet to perform additional injection. When high pressure water 4 was applied to steel sheet 1 as a so-called blow-up,
Despite a slight reduction in impact, it has been confirmed that the descaling ability is sufficiently secured.

In the following description, the high-pressure water 4 which is tilted in the steel sheet transport direction P (injection angle is negative) and is subsequently injected is referred to as an outlet spray 4b, and is tilted in the opposite direction to the steel sheet transport direction P. (The injection angle is positive) The high-pressure water 4 injected and injected is referred to as an incoming spray 4a.

[0013]

However, when the arrangement of the nozzles 3 shown in FIG. 9 is adopted, the frequency of occurrence of red scale after rolling is somewhat suppressed, but in reality, the occurrence of red scale is completely eliminated. There is a problem that it has not yet been possible to suppress the

The present invention has been made in view of such a problem, and it is a hot rolling method that can remove oxide scale to such an extent that it does not develop into a red scale after rolling even if the scale is difficult to peel. It is an object of the present invention to provide a de-scaling device in the facility.

[0015]

In order to solve the above-mentioned problems, a descaling device according to the present invention has a plurality of nozzles arranged in a width direction of a conveyed steel sheet. Each of the nozzles has a predetermined spray angle in the steel sheet transport direction and has a predetermined spray width spread in the steel sheet width direction, and in a descaling device that sprays high-pressure water on the steel sheet surface, the plurality of nozzles arranged as above,
The injection angles of the adjacent nozzles are alternately inverted in the opposite direction by reversing the positive and negative directions, and, while overlapping the high-pressure water from the adjacent nozzles when viewed from the steel sheet transport direction,
The spray width direction of each nozzle is inclined by a predetermined twist angle from the steel sheet width direction.

In the present invention, since the injection angles of the adjacent nozzles are alternately reversed to be positive and negative, and the jetting direction and the jetting direction are different from each other, the jetting angles overlap each other when viewed from the sheet conveying direction. Even if there is a portion, there is no interference at the spray wrap portion of the high-pressure water, and a decrease in descaling ability at the spray wrap portion is avoided.

At this time, the present inventors have simply adopted a nozzle arrangement in which the injection angle of the high-pressure water is alternately inverted as described above (see FIG. 10). After examining the cause of the remaining scale,
It has been found that the red scale is generated only on the upper surface of the steel plate, and that the scale residue corresponding to the generation site is generated as the trajectory 21 of the pattern of the outlet spray 4b on the upper surface of the steel plate. Further, a predetermined amount of stagnant water 22 is present on the surface of the steel plate located between the inlet-side spray 4a and the outlet-side spray 4b (hereinafter, referred to as a stagnant space). It has been found that the impact force of the spray 4b is weakened, so that the scale remains.

That is, a part of the high-pressure water 4 sprayed on the steel plate 1 is reflected and travels toward the above-mentioned staying space. In the stagnation space position, the water reflected by the outlet spray 4b is directed to the opposite side to the steel sheet transport direction, and the inlet spray Since the water reflected at 4a goes in the steel sheet transport direction (the arrow S in FIG. 10 indicates the traveling direction of the reflected water), a predetermined amount or more of the stagnant water 22 is always drawn to the stagnant space. This is because the water 22 is retained and the water 22 sequentially moves to the position of the outlet spray 4b as the steel sheet 1 advances.

In the present invention, a predetermined twist angle is provided to the spray width of the high-pressure water sprayed from each nozzle in order to remove the adverse effect of the staying water, that is, in the direction of the spray width and the plate width direction. By providing the angle, it is possible to give water reflected in the staying space a component force in the width direction of the steel sheet. By appropriately aligning the directions of the torsion angles, the reflected water can easily flow toward the end portion in the width direction of the plate, and as a result, the water that becomes the stagnant water flows to the end portion in the width direction of the plate and exists. The retained water that escapes easily escapes to the end portion in the plate width direction. As a result, the amount of stagnant water moving to the position of the outlet-side spray is reduced, and the impact force of the outlet-side spray is easily transmitted directly to the steel plate.

Further, according to the present invention, the plurality of arranged nozzles are divided into two in the plate width direction at a predetermined position in the steel plate width direction as a boundary, and the torsion angle of each nozzle is determined for each division. The twist directions are aligned, and the spray width by the adjacent nozzles is set so as to be substantially C-shaped at the end in the width direction of the steel sheet in plan view.

According to the present invention, the high-pressure water is divided into two parts in the sheet width direction with a predetermined position in the sheet width direction as a boundary, and the accumulated water flows toward the end in the sheet width direction for each section. The direction of the spread in the steel sheet width direction is set.

That is, by aligning the direction of the spray width for each section so as to face the widthwise end of the steel sheet, for each section, the water that has collided with the steel sheet and reflected toward the stagnation space. All of the water has a component force in the same direction toward the steel sheet width direction end, and the water easily flows to the steel sheet width direction end.

Next, a second aspect of the present invention is the first aspect.
In the configuration described in the above, the torsion angle is 5 to 5 in absolute value.
The angle is set in a range of 15 degrees (-15 to -5 degrees, 5 to 15 degrees).

FIG. 5 shows the relationship between the twist angle θ (referred to as an absolute value) and the scale remaining state on the outlet spray side. That is, when the passing speed of the steel sheet is increased, the oxide scale tends to be unable to be removed. This is mainly because when the passing speed is high, the steel plate comes to the spray position on the delivery side before the retained water escapes in the width direction of the plate. Generally, the red scale generating material is a thick material of high tensile steel, and the threading speed of the high tensile steel is 0.5 to 1.0 m / s.
ec. For this reason, it can be seen from FIG. 5 that if the torsion angle θ is set to an absolute value of 5 degrees or more from the width direction of the steel sheet, the oxide scale can be completely removed even on the outlet spray side in the target steel type. .

For this reason, the lower limit of the absolute value of the torsion angle θ is set to 5 degrees. Also, the larger the torsion angle θ is,
While drainage of accumulated water in the plate width direction becomes better, since the projected spray width of the steel sheet width direction by the high-pressure water which is each injection is reduced, the amount of water increases the need to install additional number of nozzles is used in descaling occurs And is disadvantageous in energy efficiency. Based on this, the upper limit of the absolute value of the torsion angle is set to 1
5 degrees. Next, the invention described in claim 3 is the above contractor.
The descaling device according to claim 1 or claim 2 is used.
Characterized by performing descaling of the steel sheet surface
A hot rolling method is provided.

[0026]

Next, embodiments of the present invention will be described with reference to the drawings. The descaling apparatus according to the present embodiment is provided in a hot rolling facility, and as shown in FIG. 1, headers 2 are respectively arranged on upper and lower sides of a steel sheet 1 to be conveyed, and high-pressure water is supplied to each header 2. High-pressure water is supplied from the device 5.

Each header 2 is, as shown in FIG.
The header 2 is provided with a plurality of nozzles 3 arranged along the steel sheet width direction W.

The axis of each of the nozzles 3 arranged in this manner is such that adjacent nozzles 3 alternately incline in the opposite direction by inverting the injection angle α with each other, and if the injection from one nozzle 3 is started, the other will be injected. The injection from the nozzles 3 is set alternately so as to be a follow-up injection.

The high-pressure water 4 injected from each nozzle 3
Is sprayed with a predetermined spray width A in the plate width direction W, and when viewed from the steel plate conveyance direction P, the high-pressure water 4 sprayed from the adjacent nozzles 3 overlaps each other in the plate width direction. (In FIG. 2, δ is an overlap portion).

At this time, the nozzle 3 arranged on the upper side
As shown in FIGS. 2 and 3, for example, by giving a twist angle of 10 degrees in absolute value, the direction H of each spray width A is obtained.
Is set to be inclined from the sheet width direction W in the direction Q along the sheet conveying direction, for example, with a twist angle θ of θ = 10 degrees in absolute value.

In the present embodiment, the nozzle is divided into two parts in the plate width direction with the center D in the plate width direction W as a boundary, and the direction of the torsion at the above-mentioned torsion angle θ of each nozzle is aligned for each section. By setting the spray width A by the matching nozzle so that the end side in the width direction of the steel sheet is broad in a substantially C shape in a plan view, the retained water flows in opposite directions T with respect to the center portion D in the width direction W of the plate. It is easy to flow.

When the descaling device having the above-described configuration is used, the high-pressure water 4 injected from each nozzle 3 collides with the steel plate 1 and is reflected on the nozzle 3 side (the side on which the retained water is formed). As shown in FIG. 4, when the steel sheet 1 collides with the steel sheet 1, it flows in a direction B perpendicular to the direction H of the spray width A, and the flow has a direction inclined in the steel sheet width direction W. It becomes easier to flow to the end on the closer side of 1a and 1b, respectively, and it becomes easier for retained water to escape in the steel sheet width direction W.

As a result, the amount of water staying between the outlet spray 4b and the inlet spray 4a is greatly reduced.
As a result, the discharge side spray 4b greatly reduces the adverse effect of the retained water, and directly collides with the surface of the steel sheet 1 to remove the oxide scale on the surface of the steel sheet 1 by impact.

Here, the torsion angles θ of the high-pressure water 4 injected from the respective nozzles need not be all the same, but are set as absolute values within the range of 5 to 15 degrees individually from the width direction W of the plate. do it.

Further, according to the present invention, the central portion D in the plate width direction W
Although the retained water is allowed to escape to both sides with the boundary as a boundary, for example, the one end in the width direction of the steel sheet is set to a predetermined position in the width direction of the steel sheet, and the twist is caused to flow all toward the other end side in the width direction of the steel sheet. The corners may be aligned.

[0036]

As it has been described in the foregoing, in descaling device of the present invention, because of the so elusive the accumulated water in the steel plate width direction, is as impact force delivery side spray over propagates to ensure steel In addition, even if it is an oxide scale that is difficult to peel, it is possible to reliably remove the oxide scale, and there is an effect that generation of red scale can be prevented even for a steel sheet of a steel type that generates a scale that hardly peels. .

[Brief description of the drawings]

FIG. 1 is a side view showing a descaling device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a descaling device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a direction (twist angle) of a spray width of high-pressure water injected from each nozzle according to the embodiment of the present invention.

FIG. 4 is a diagram showing a direction in which water reflected and colliding with a steel plate according to the embodiment of the present invention flows.

FIG. 5 is a diagram showing the relationship between the inclination of the sprayed high-pressure water in the spreading direction and the steel sheet passing speed.

FIG. 6 is a side view showing a conventional descaling device.

FIG. 7 is a front view showing a conventional descaling device.

FIG. 8 is a diagram showing the occurrence of scale flaws (red scale).

FIG. 9 is a perspective view showing a conventional descaling device.

FIG. 10 is a diagram for explaining a problem of a conventional descaling device.

[Explanation of symbols]

 P Transport direction D Border boundary H Spray width direction α Spray angle θ Twist angle 1 Steel plate 2 Header 3 Nozzle 4 Injected high-pressure water

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-174137 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 45/08

Claims (3)

(57) [Claims] 1. A plurality of nozzles are arranged along a width direction of a steel sheet to be conveyed, and each nozzle has a predetermined spray angle in the steel sheet conveyance direction and a predetermined spray width spread in the steel sheet width direction. In a descaling apparatus for injecting high-pressure water onto the surface of a steel sheet, the spray angles of the adjacent nozzles are alternately inverted in the positive and negative directions of the adjacent nozzles and alternately inclined in opposite directions, and viewed from the sheet conveying direction. The high-pressure water from the adjacent nozzles overlap each other, and the direction of the spray width by each nozzle is inclined by a predetermined twist angle from the steel plate width direction.
At the specified position in the board width direction and
Every minute, the twist direction of the above-mentioned twist angle of each nozzle is aligned.
The spray width by the adjacent nozzle is the width of the steel plate in plan view.
A descaling device, characterized in that the opposite end is set to have a substantially U-shape . 2. The descaling device according to claim 1, wherein the twist angle is set in a range of 5 to 15 degrees in absolute value. 3. The desk according to claim 1 or 2, wherein
Descale the steel plate surface using a kelling machine
A hot rolling method.