JP5672664B2 - Steel plate descaling method and apparatus - Google Patents

Description

  The present invention relates to a steel sheet descaling method and apparatus.

  As a technique for removing the hot rolled material, that is, the slab before rolling and the scale of the rolled material being rolled, a technique for removing scale by injecting high pressure water onto the surface of the hot steel plate (rolled material) Many scaling techniques have been proposed.

  Here, a conventional high-pressure water descaling apparatus will be described with reference to FIG.

  FIG. 3A shows the relationship between the rolled material 10 and the high-pressure water header 11 in a cross section perpendicular to the rolling line, and the injection region of the high-pressure water (spray water) 14 on the surface of the rolled material 10, that is, the spray water 14 is rolled. The surface (the lower figure of Fig.3 (a)) formed by colliding with the material 10 is shown.

  In general, an apparatus for injecting high-pressure water 14 onto the hot-rolled material 10 (high-pressure water descaling apparatus) includes several tens of descaling nozzles 12 (hereinafter also simply referred to as nozzles) as shown in FIG. The descaling nozzle header 11 (hereinafter also simply referred to as “header”) is installed in the width direction of the rolled material 10 and the scale is removed by injecting high pressure water 14 (for example, injection pressure: 10 to 50 MPa) from the nozzle 12. It is.

In this device, the injection region of the spray water 14 jetted from each nozzle 12 is inclined with a twist Ri angular β of approximately 15 ° with respect to the width direction of the rolled material 10, both end portions of the spray water 14 It does not overlap with the spray region of the spray water 14 sprayed from the nozzles 12 on both sides. The reason why the spray regions of the nozzles 12 do not overlap is to prevent the spray water 14 from interfering with each other in the air and reducing the collision pressure against the rolled material 10.

  On the other hand, the injection region of each nozzle 12 has a region (overlap region) that overlaps in the plate width direction (hereinafter simply referred to as the width direction) of the rolled material 10 as shown in the figure. This is because the idea is to eliminate the region where the spray water 14 does not collide with the rolled material 10 in the width direction. In addition, the width direction length (overlap width) of an overlap area | region is about 0-30 mm normally.

  Moreover, FIG.3 (b) shows the relationship between the rolling material 10 and the header 11 in a cross section parallel to a rolling line. As shown in the figure, the direction of the nozzle 12 is provided so as to be inclined with respect to the traveling direction of the rolled material 10, and the angle of attack α is usually from a perpendicular line dropped from the nozzle 12 to the rolled material 10. It is about 10-15 degrees.

  This is because the scale peeled off by the spray water 14 colliding with the rolled material 10 is caused to flow obliquely and laterally together with the spray water 14 so as to flow down laterally from the surface of the rolled material 10. The perpendicular distance is the nozzle height H.

  However, in recent years, in order to improve the material of the steel sheet, particularly in the case of a steel sheet to which an element such as Si is added, the scale has become difficult to peel off. When observing the situation where these detachable scales remain, in many cases, a plurality of streak scales extending in the direction of the rolling line remain in the width direction, and such scale residue has a conventional descaling effect. It shows that it is non-uniform in the width direction.

  Actually, in the normal nozzle arrangement shown in FIG. 3, the spray water 14 is sprayed and the distribution state of the spray water 14 is examined. As a result, the spray sprayed from the nozzle 12 is shown in FIG. The water 14 (left outer edge line 14a and right outer edge line 14b) collides with the steel sheet (rolled material) 10 and then extends along the surface of the rolled material 10 with a spray angle θ spread in the direction of the angle of attack of the nozzle 12. It was found that the water flowed as lateral flow water 15 (left outer edge line 15a, right outer edge line 15b). At that time, the cross-flow water 15 by the spray water 14 sprayed from the nozzle 12B (in FIG. 4, the nozzle is located on the downstream side in the rolling material traveling direction in the overlap region), the adjacent nozzle 12A (in FIG. 4, It was recognized that the injection region flowed across the injection region of the nozzle) located in the overlap region and upstream of the rolling material traveling direction.

  Therefore, in such a region where the cross-flow water 15 exists, it is considered that the collision pressure of the spray water 14 on the surface of the rolled material 10 decreases, and the descaling action is uneven in the width direction. It was.

  Here, in FIG. 4, a region in which the lateral flow water 15 from the adjacent nozzle 12B passes through and interferes with the spray water 14 from the nozzle 12A among the ejection regions of the nozzle 12A is called an interference region, and the width direction of the interference region Is called the interference area width. That is, the area from the point R where the left outer edge line 15a of the cross-flowing water 15 from the nozzle 12B passes through the injection region of the nozzle 12A to the right end P of the injection region of the nozzle 12A is an interference region, and the width between R and P The direction length is the interference area width. Further, the area from the left end Q of the injection area of the nozzle 12B to the right end P of the injection area of the nozzle 12A is the overlap area, and the length in the width direction between Q and P is the overlap width.

  And since an overlap area | region is covered by the injection area | region of the nozzle 12B among interference areas, it does not affect the descaling capability directly. On the other hand, since the area other than the overlap area is directly affected by the interference of the cross-flow water 15 by the nozzle 12B and affects the descaling capability by the nozzle 12A, this is called an interference influence area, and the length in the width direction is the interference influence area. We will call it width. That is, the area from the point R to the left end Q of the ejection area of the nozzle 12B is the interference influence area, and the width direction length between R and Q is the interference influence area width.

  3A and 4, reference numeral 13 denotes an axis of the nozzle 12, and the horizontal direction component of the axis 13 (line projected on the surface of the rolled material 10) is the rolling material traveling direction (longitudinal direction of the rolled material). The angle is referred to as the swing angle γ. Usually, the swing angle γ is 0 °.

  Conventionally, when the primary scale such as slab extracted from the heating furnace is descaled online by HSB (Hydraulic Scale Breaker), and when the secondary scale of the steel sheet during hot rolling is descaled, each nozzle It has been considered that the collision pressure of the spray water on the surface of the rolled steel sheet can be uniformly distributed in the width direction of the rolled material by providing the overlap region by overlapping the high pressure spray water from As an example, in Patent Document 1, when a hot-rolled steel sheet is rolled using a reversible hot rolling mill, in the method of manufacturing a hot-rolled steel sheet that is rolled multiple times while descaling and cooling the steel sheet, For scaling, high-pressure jet water ejected from a plurality of nozzles toward a hot-rolled steel plate is distributed almost uniformly in the plate width direction with a collision pressure of a certain value or more.

  Further, in Patent Document 2, adjacent descaling nozzles are arranged with the injection direction alternately changed from upstream and downstream with respect to the line traveling direction, and the position where the injection water from the adjacent nozzle collides with the steel plate. The distance between the water films is 0 mm or more and 100 mm or less, the incident angle of the spray water film from the front nozzle to the steel sheet is between 0 ° and 4 °, and the incident angle of the spray water film from the rear nozzle is from 0 ° to −4 A descaling device intended to be in the range of ° is described.

  Patent Document 3 describes that nozzles are arranged at intervals of a distance obtained from a predetermined mathematical formula for the high-pressure water impingement part.

  Further, in Patent Document 4, in a descaling apparatus including a plurality of rows of descaling headers, the nozzles in the first row are arranged at intervals at which cross-flow water does not interfere, the angle of attack, the twist angle, and the nozzle height, and two rows. It is described that the nozzles of the eyes are arranged shifted in the width direction by a predetermined pitch.

  Further, Patent Document 5 describes a method of eliminating scale peeling unevenness by differently distributing the flow rate in the width direction of high-pressure water ejected from a nozzle at the end, the center, and the other end. .

JP-A-6-285534 Japanese Patent No. 3844279 JP 2000-176533 A Japanese Patent No. 3331860 JP 2006-247714 A

Materials and Processes, Vol. 5, 1992, p. 1510

  However, the method described in Patent Document 1 has a problem for the following reason. Since the descaling nozzle is generally a flat spray type in which the spray water spreads in a fan shape, the high-pressure water sprayed from the nozzle flows on the surface of the steel plate while spreading even after colliding with the steel plate, so-called cross-flow water shown in FIG. Will occur. This cross-flow water interferes with the injection region from the adjacent nozzle, and a portion with a small collision pressure is generated in the length in the width direction. As a result, the scale is left behind.

  And since the method of patent document 2 can achieve scale peeling nonuniformity reduction, since there is no interference by cross-flow water, when such a descaling nozzle was arrange | positioned in the immediate vicinity of the rolling roll, it was made to peel with high pressure water. There is a problem that the scale flows to the side of the rolling roll, and scale biting occurs.

  Moreover, although the method described in Patent Document 3 is said to have a scale peeling action even on a portion where there is a gap, it is considered that the scale is considered to be limited to a steel type that is easily peeled off, and a steel type that is difficult to scale off. In the case of, there is still a problem that the scale is left behind.

  Furthermore, as described above, the descaling device described in Patent Document 4 requires that the descaling header is left in one row and the descaling header is left in two rows or more. It cannot be used around rolling mills that cannot be taken. In addition, since the descaling headers are arranged in a plurality of rows, there is a problem in that the cost increases such as an increase in the amount of high-pressure water and an increase in power, and a temperature decrease due to an increase in the amount of water increases. Moreover, although there is a description in the same document that the crossflow water does not interfere, there is no specific explanation and it is difficult to implement.

  And in patent document 5, although the description about the flow volume of the high pressure water injected from a nozzle was made, even if it changed flow volume distribution with the actual nozzle, the scale nonuniformity might arise. It seems that simply using a nozzle with a flow distribution is not sufficient.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steel sheet descaling method and apparatus that can solve the above-mentioned problems in the prior art and that can be appropriately descaled without generation of scale residue.

  In order to solve the above problems, the present invention has the following features.

[1] In a descaling method for a steel sheet, in which high pressure water is injected from a plurality of descaling nozzles arranged in a descaling header extending in the width direction of the steel sheet,
While having a predetermined angle of attack and a twist angle, and arranging the descaling nozzle so that the injection regions from adjacent descaling nozzles have a predetermined overlap width in the steel sheet width direction,
The interference area width where the cross-flow water after being injected on the steel sheet surface interferes with the injection area of the adjacent descaling nozzle is within the range of the overlap width between the injection areas of the adjacent descaling nozzles. A method for descaling a steel sheet, wherein high pressure water is jetted from a descaling nozzle.

  [2] As a descaling nozzle, a nozzle having an asymmetric high-pressure water injection flow rate is used, and the injection flow rate on the longer injection distance to the steel plate is larger than the injection flow rate on the shorter injection distance to the steel plate. The method for descaling a steel sheet according to [1], wherein the descaling method is performed.

[3] In a steel plate descaling apparatus in which a plurality of descaling nozzles for injecting high-pressure water is disposed on a descaling header provided in the width direction of the steel plate,
The descaling nozzle has a predetermined angle of attack and a twist angle, and the descaling nozzle is disposed so that the injection regions from adjacent descaling nozzles have a predetermined overlap width in the steel plate width direction,
The interference area width where the cross-flow water after being injected on the steel sheet surface interferes with the injection area of the adjacent descaling nozzle is within the range of the overlap width between the injection areas of the adjacent descaling nozzles. A descaling device for a steel sheet, wherein the horizontal component of the axis of the descaling nozzle is installed at an angle with respect to the traveling direction of the steel sheet.

  [4] As a descaling nozzle, a nozzle having an asymmetric high-pressure water injection flow rate is used, and the injection flow rate on the longer injection distance to the steel plate is larger than the injection flow rate on the shorter injection distance to the steel plate. As described above, the descaling nozzle is installed in a descaling header, and the steel sheet descaling apparatus according to [3] above.

  In the present invention, the angle of attack and the twist angle are not particularly limited, and a commonly used predetermined value may be used. For example, the angle of attack may be about 5 ° to 15 °, and the twist angle may be about 5 ° to 15 °.

  According to the present invention, even if a steel plate (rolled material) to which an element such as Si is added and the scale is difficult to peel off, no scale remains over the entire width of the steel plate (rolled material), and the quality of the product is improved. .

It is a partial top view in one embodiment of the present invention. It is a partial front view in one embodiment of the present invention. It is the partial front view and partial side view in the conventional descaling apparatus. It is a partial top view in the conventional descaling apparatus. It is an example of the erosion test result of the aluminum plate in a prior art example. It is an example of the erosion test result of the aluminum plate in the example of the present invention.

  As described above, the remaining scale remaining in the steel plate width direction with a plurality of streak scales extending in the steel plate traveling direction is generated by the interference of the water flow that flows across the injection region of the adjacent nozzle as the cross-flow water. Therefore, the present invention has been completed for the purpose of reducing the interference caused by the lateral water flow and uniformly peeling the scale in the entire width direction.

  That is, the present invention is such that the interference influence region shown in FIG. 4 is eliminated, in other words, the interference region fits within the overlap region (interference region width ≦ overlap region width). is there.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a partial plan view of this embodiment, and FIG. 2 is a partial front view of this embodiment. Each corresponds to FIG. 4 and FIG. 3A in the prior art described above.

  As shown in FIG. 1 and FIG. 2, this embodiment adjusts the swing angle γ of the nozzle 12 (the angle formed by the horizontal component of the axis 13 of the nozzle 12 and the rolling material traveling direction), and the interference area width = over. Thus, the width of the wrapping area is set, thereby eliminating the interference influence area. In other words, the position in the width direction at point R in FIG. 4 (the point where the left outer edge line 15a of the cross-flowing water 15 from the nozzle 12B passes through the injection region of the nozzle 12A) and the point Q (the left end of the injection region of the nozzle 12B). The positions in the width direction are made to coincide.

  Specifically, the horizontal component of the left outer edge line 14a of the spray water 14 (the left outer edge line 15a of the cross-flow water 15) is adjusted to be parallel to the rolling material traveling direction by adjusting the oscillation angle γ of the nozzle 12. I have to.

  In this way, in this embodiment, the cross-flow water 15 from the nozzle 12B eliminates the interference influence region that directly affects the descaling capability of the nozzle 12A, so that the descaling action is uneven in the width direction. Is prevented. As a result, it is possible to suppress the generation of the remaining scale over the entire width of the steel plate (rolled material) 10.

  In order to confirm the effect of the above embodiment, the present inventors have a good correlation between the descaling property of the high-pressure water descaling device in the actual line and the erosion test result of the plate by the high-pressure water in the laboratory. In the laboratory, the conventional nozzle arrangement (conventional example) shown in FIGS. 3 and 4 and the nozzle arrangement of this embodiment (invention example) An erosion test was conducted. Here, erosion means that the surface of a lead plate or an aluminum plate is removed.

FIG. 5 (conventional example) and FIG. 6 (invention example) show the results of erosion of a pure aluminum plate having a plate thickness of 6 mm using two nozzles. Conditions at this time, the spray angle θ is 49 ° of the nozzle 12, water is 58l / min of high-pressure water, the injection pressure of the high-pressure water 15 MPa, the nozzle height H is 86 mm, the angle of attack α is 10 °, twist Ri corner β was 5 ° and the nozzle pitch was 76 mm.

  In the conventional example, the swing angle γ is 0 ° and the interference affected area width exceeds 5 mm. In the present invention example, the swing angle γ is 5 ° and the interference affected area width is 0 mm. I tried to become.

  As shown in the photograph of the actual product in FIG. 5 (b) and the drawing depicting it in FIG. 5 (a), in the conventional example, there is a portion that is not eroded in the width direction, but the actual product is shown in FIG. 6 (b). As shown in the photograph of FIG. 6 (a), there is no portion that is not eroded in the width direction in the example of the present invention.

  Thus, the effect of the above embodiment in which the interference area width = the overlap area width was confirmed.

  The effect of the above embodiment is obtained by eliminating the interference influence area shown in FIG. 4. If the interference area falls within the overlap area (interference area width ≦ overlap area width), A similar effect can be obtained. That is, in some cases, the swing angle γ may be increased so that the interference area width <the overlap area width.

  However, if the swing angle γ is 10 ° or more, the left and right spray distances of the spray water 14 until reaching the steel plate 10 are deviated, and a difference occurs in the descaling ability in the width direction. It is preferable to make it below °.

  In the present invention, it is preferable that the interference-affected region is not strictly present, that is, the interference region width ≦ the overlap region width, but this is not strictly required. The flow rate is slightly small in the vicinity of the width direction end of the spray water 14, that is, in the vicinity of the left outer edge line 15 a of the cross-flow water 15, and the scale is peeled off in the width direction by the shearing force of the descaling water (high pressure water) 14. It has been confirmed that when the interference-affected area width is 5 mm or less, there is no remaining scale. That is, it can be said that there is substantially no interference-affected region and the interference region width is within the overlap width range. Therefore, the swing angle γ may be adjusted so that the interference-affected region width is 5 mm or less.

  Further, when the swing angle γ is applied, the left and right spray distances of the spray water 14 until reaching the steel plate 10 are different, so that the collision force to the steel plate 10 is weakened on the long spray distance side, and the spray distance is short. On the other hand, the descaling ability tends to be inferior. Therefore, for example, when the descaling nozzle described in Patent Document 5 is used, the injection flow rate in the width direction of the spray water 14 is asymmetrical, the flow rate with a shorter injection distance is reduced, and the flow rate with a longer injection distance is increased. Since the collision force when reaching the steel plate 10 is made uniform, it is more preferable. Making the width direction injection flow rate asymmetrical can also be achieved by changing the shape of the nozzle 12.

  The present invention was applied to a thick steel plate production line based on the results of the plate erosion test with high-pressure water in the laboratory.

In the thick steel plate production line, the descaling headers installed on the front surface and the rear surface of the thick plate rolling machine have the descaling nozzle 12 obliquely oriented with respect to the traveling direction of the steel plate 10 as shown in FIGS. In addition, the spray region is arranged so that the end portions overlap in the width direction, that is, the spray angle θ of the nozzle 12 is 49 °, the amount of water of the high-pressure water 14 is 58 l / min, the spray pressure of the high-pressure water 14 is 15 MPa, nozzle height H is 76 mm, the angle of attack α is 10 °, twist Ri angle β is 5 °, the nozzle pitch is 76 mm, the overlap width is a 15 mm.

  Then, the 250 mm thick slab is heated to 1200 ° C., the scale is once removed with the HSB on the heating furnace exit side, the scale is removed with a descaling device installed in the immediate vicinity of the rolling mill, and 15 passes with the thick plate rolling mill. The thickness was 30 mm and the plate width was 300 mm. In addition, about 0.16% of Si is added to this steel material, and the scale is a steel type that is relatively difficult to peel off. Only in a total of 13 passes out of 15 passes, high-pressure water was jetted from the descaling nozzle on the steel sheet (rolled material) entry side to separate the scale.

  At that time, as Example 1 of the present invention, as shown in FIGS. 1 and 2, the swing angle γ was set to 5 °, and the interference-affected region width was set to 0 mm. As a result, in Example 1 of the present invention, there was almost no scale residue, and there were no other problems.

  When the collision pressure of the high-pressure water at this time was measured off-line with a pressure sensor, all the collision pressures were equal to or higher than the collision pressure for scale peeling, although there was a pressure distribution in the width direction.

  Further, as Example 2 of the present invention, in addition to the conditions of Example 1 of the present invention, a nozzle having an asymmetric left-right injection flow rate was used. The width direction injection flow rate of this nozzle was about 1.5 times the flow rate on the short flow rate side. As a result, the collision pressure was almost uniform in the width direction, and there was no remaining scale.

  On the other hand, as Comparative Example 1, as shown in FIGS. 3 and 4, a conventional nozzle arrangement with a swing angle γ of 0 ° was performed. As a result, scale residue occurred and the appearance was poor.

  Further, as Comparative Example 2, the nozzles described in Patent Document 2 were alternately arranged. As a result, no scale residue was observed, but scale biting occurred in the rolling mill, and the scale was pushed in like a rib, resulting in poor appearance.

  Furthermore, as Comparative Example 3, a descaling nozzle having a flow rate changed in the width direction described in Patent Document 5 was used, and the oscillation angle γ was 0 °. As a result, in the interference-affected region, scale residue occurred and the appearance was poor.

10 Steel plate (rolled material)
11 Descaling header (header)
12 Descaling nozzle (nozzle)
12A Left nozzle 12B Right nozzle 13 Nozzle axis 14 Spray water (high pressure water)
14a Outer edge line on the left side of spray water 14b Outer edge line on the right side of spray water 15 Cross-flow water 15a Outer edge line on the left side of cross-flow water 15b Outer edge line on the right side of cross-flow water

Claims (4)

In the steel sheet descaling method in which high pressure water is injected from a plurality of descaling nozzles arranged in a descaling header extending in the width direction of the steel plate,
The descaling nozzle is arranged so that the injection regions of high pressure water that have a predetermined angle of attack and twist angle and are injected from adjacent descaling nozzles have a predetermined overlap width in the steel plate width direction. ,
In the overlap region where the injection region overlaps in the steel plate width direction on the traveling steel plate surface, the lateral flow water after the high pressure water is injected from the descaling nozzle located on the downstream side in the steel plate advance direction is the steel plate. The interference area width, which is the length in the width direction of the interference area that passes through the surface and interferes with the ejection area of the adjacent descaling nozzle, is in the same range as the overlap width of the ejection areas of the adjacent descaling nozzles. so that, the descaling method of the steel sheet, wherein the horizontal component of the one side of the outer edge lines of the high-pressure water jetting high-pressure water from the descaling nozzle in parallel to the steel sheet traveling direction such.   As a descaling nozzle, a nozzle with an asymmetric high-pressure water injection flow rate is used so that the injection flow rate on the longer injection distance to the steel plate is larger than the injection flow rate on the shorter injection distance to the steel plate. The method for descaling a steel sheet according to claim 1. In a steel plate descaling apparatus in which a plurality of descaling nozzles for injecting high-pressure water is disposed on a descaling header provided in the width direction of the steel plate,
The descaling nozzle has a predetermined angle of attack and a twist angle, and the descaling nozzles are arranged such that the injection regions of high pressure water injected from adjacent descaling nozzles have a predetermined overlap width in the steel plate width direction. And
In the overlap region where the injection region overlaps in the steel plate width direction on the traveling steel plate surface, the lateral flow water after the high pressure water is injected from the descaling nozzle located on the downstream side in the steel plate advance direction is the steel plate. The interference area width, which is the length in the width direction of the interference area that passes through the surface and interferes with the ejection area of the adjacent descaling nozzle, is in the same range as the overlap width of the ejection areas of the adjacent descaling nozzles. in such so that, that the horizontal component of the horizontal component of the one side of the outer edge lines of the high-pressure water is in parallel with the steel plate traveling direction axis of the descaling nozzle is installed at an steel traveling direction and angle A steel sheet descaling device.   As a descaling nozzle, a high-pressure water injection flow rate is asymmetric in the width direction, and the injection flow rate on the side where the injection distance to the steel plate is long is larger than the injection flow rate on the side where the injection distance to the steel plate is short. The steel plate descaling apparatus according to claim 3, wherein the descaling nozzle is installed in the descaling header.