Draining device during passing of metal plate, hot rolling facility, and method for manufacturing hot rolled steel strip

Abstract

To provide a technique effectively removing scattered water in a space above a metal plate and water droplets on a top surface of the metal plate during plate passing to be excellent in property of plate passing.SOLUTION: A device of draining metal plate during plate passing comprises: a plurality of first blowers 6 installed between a fluid jet type draining appliance 4 and an inspection device 8 in which the first blower blows air flow from a direction opposite to the plate passing direction of the metal plate 1 to the top surface of the metal plate over the whole width direction of the metal plate 1; a first frame in which the first blower 6 is fixed on an upper part of a rolling line; second blowers 7 installed between the first blower 6 and the inspection device 8 in which the second blower blows air flow from a direction approximately orthogonal to the plate passing direction PL of the metal plate 1; a second frame in which the second blowers 7 are respectively fixed at both end parts in a width direction of the rolling line; fixtures which respectively fix the first blower 6 and the second blower 7 to the first frame and the second frame; and a power source board which has a function displaying use state of the first blower 6 and the second blower 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the water drainage technology during the passage of a metal plate. In particular, it relates to a device for effectively eliminating water droplets that cause false detection by a defect detection device in a hot rolling line, removing the water scattered in the space above the hot-rolled metal plate during passage and the water droplets on the upper surface of the hot-rolled metal plate, a hot rolling facility having such a device, and further to a method for manufacturing a hot-rolled steel strip using such a device.

Background Art

[0002] In the hot rolling of metal plates, especially steel plates, in recent years, devices for online defect detection of hot-rolled and cooled steel plates have been installed and are in operation.

[0003] To cool the steel plate after hot rolling, a large amount of water is required. Therefore, a large amount of water remains on the steel plate, and it cannot be defect-detected as it is. Therefore, to remove the remaining water, there is a device that injects high-pressure fluid in the direction opposite to the advancing direction of the plate passing line. For example, Patent Document 1 discloses a technique of blowing high-pressure fluid from above to remove the water on the surface. Patent Document 2 discloses a water drainage technique using a water drainage roll or an inclined water flow. Patent Document 3 discloses means such as injecting higher-pressure air from a direction substantially orthogonal to the plate passing line.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above prior art has the following problems. That is, the technologies described in Patent Documents 1 to 3 focus on removing cooling water on the steel plate and do not address the removal of water scattered in the air above the steel plate. In addition, the influence of blowing air on the passing property of the steel plate is sometimes unclear, and the flow rate and blowing angle of the air flow could not be set. Moreover, special equipment for supplying high-pressure fluid was required. Furthermore, pressure loss occurred in the piping during the transportation of the high-pressure fluid, resulting in the need for excessive equipment.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a device that effectively removes water scattered in the space above the metal plate and water droplets on the upper surface of the metal plate during the passage of the metal plate and has excellent passing properties. In addition, an object is to provide a hot rolling facility having the device and a method for manufacturing a hot-rolled steel strip using the device.

Means for Solving the Problems

[0007] The water draining device for a metal plate according to the present invention that advantageously solves the above problems is a water draining device for a metal plate that is passed through a rolling line, sequentially water-cooled and drained by a water cooling facility and a fluid injection type water draining facility installed in parallel with the water cooling facility after finish rolling, then subjected to a predetermined inspection by a surface inspection device, and then wound by a winder. The water draining device is characterized by including a plurality of first blowers installed between the fluid injection type water draining facility and the inspection device, blowing air from above across the entire width direction of the metal plate in a direction opposite to the passing direction of the metal plate; a first pedestal for fixing the first blower above the rolling line; a second blower installed between the first blower and the inspection device, blowing air in a direction substantially orthogonal to the passing direction of the metal plate; a second pedestal for fixing the second blower at the width direction end of the rolling line; fixing jigs for fixing the first blower and the second blower to the first pedestal and the second pedestal respectively; and a power panel having a function of displaying the usage status of the first blower and the second blower.

[0008] Note that the water draining device for the metal plate passing through the present invention is (a) the air flow blown from the first blower has a flow velocity of 20 m / s or more, (b) the first blower is arranged such that the blower arranged on the end side of the metal plate is downstream in the metal plate passing direction from the blower on the central side, (c) the first blower is arranged such that the central axis of the air flow has an inclination angle within the range of 10° or more and 20° or less upstream in the metal plate passing direction with respect to the vertical direction, (d) the second blower is arranged such that the air flows blown from both ends in the width direction of the metal plate do not interfere with each other, etc. can be considered as more preferable solution means.

[0009] The hot rolling facility according to the present invention that advantageously solves the above problems is a hot rolling facility in which a metal plate is passed through a rolling line, and after finish rolling, it is sequentially water-cooled and drained by a water cooling facility and a fluid injection type water draining facility installed in parallel with the water cooling facility, and then after undergoing a predetermined inspection by a surface inspection device, it is wound by a winder, and is characterized by having a water draining device for the metal plate passing through according to any of the above.

[0010] The method for manufacturing a hot rolled steel strip according to the present invention that advantageously solves the above problems is a method for manufacturing a hot rolled steel strip by passing a hot rolled steel strip, water-cooling it after finish rolling, injecting a fluid to drain the surface of the steel strip, then performing a surface inspection, and then winding it with a winder. When manufacturing the hot rolled steel strip, before the surface inspection, water droplets on the steel strip are removed using the water draining device for the metal plate passing through according to any of the above.

Effects of the Invention

[0011] According to the metal plate water drainage device, hot rolling equipment, and hot rolled steel strip manufacturing method of the present invention during plate passing, it is possible to prevent water droplets scattered above the steel plate, which is a metal plate, from reflecting into the surface inspection device, i.e., the defect detection device. The frequency of false detection in defect inspection is significantly reduced, and the fatigue detection accuracy in online can be greatly improved. As a result, the load of the visual inspection work of the steel plate performed by the operator according to the defect omission and defect detection results can be significantly reduced. In addition, the compressor for injecting high-pressure air used conventionally becomes unnecessary, and the effect that the operation cost is significantly reduced can also be obtained. Furthermore, by blowing the air flow onto the steel plate at an appropriate angle and flow rate, not only can water droplets be removed, but also a hot rolled steel strip can be manufactured without sacrificing the plate passing property.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be specifically described. In addition, the following embodiments illustrate facilities and methods for embodying the technical idea of the present invention, and do not specify the configuration to be the following. That is, the technical idea of the present invention can be variously modified within the technical scope described in the claims.

[0014] FIG. 1 is a schematic diagram of a water draining device for a metal plate during continuous passing according to an embodiment of the present invention. FIG. 1(a) shows a top view. FIG. 1(b) shows a front view seen from the operator side.

[0015] In the example of FIG. 1, a water draining device installed between a water cooling facility 3 and a flaw detection device 8 which is a surface inspection device after the hot rolling line will be described. In hot rolling for manufacturing a steel plate 1 as a metal plate, during the period from water cooling the steel plate 1 after finish rolling to winding it up by a coiler 10, a flaw detection device 8 for detecting flaws on the surface of the hot rolled steel plate may be installed online and flaw inspection may be performed. A pinch roll 9 for adjusting the tension of the steel plate is arranged immediately before the coiler 10.

[0016] For example, in the facility of FIG. 1, the steel plate 1 passed through the hot rolling line is cooled by cooling water injected from a cooling facility 3 after being rolled by a finish rolling mill 2. At this time, if even a part of the cooling water poured from the cooling facility 3 on the outlet side of the finish rolling mill 2 onto the steel plate 1 remains as water droplets on the upper surface of the steel plate 1, the water droplets may be misdetected as flaws, leading to a decrease in flaw detection accuracy.

[0017] For example, in the prior art described in Patent Document 3, a water jet type water draining facility 4 that injects high-pressure water obliquely upstream from both ends in the width direction of the steel plate 1 is provided. Thereby, it is said that the stagnant water on the steel plate is removed. Further, high-pressure air injection is performed by an air nozzle group substantially orthogonal to the passing direction of the steel plate to remove the water droplets remaining on the upper surface of the steel plate 1 outside the steel plate surface.

[0018] However, in the online flaw detection device 8, false detection by water droplets cannot be sufficiently prevented. When the inventors investigated this in detail, it was found that when the passing speed of the steel plate 1 is high, that is, when the rotational peripheral speed of the conveying roller 5 is fast, the cooling water is wound up by the rotation of the conveying roller 5. And it was found that a phenomenon occurs in which the wound-up cooling water scatters into the space above the steel plate 1, and this scattered water may reach the flaw detection device 8 in a floating state in the space.

[0019] The conventional draining device is designed for the water droplets remaining on the upper surface of the steel plate 1 after removing the cooling water staying on the upper surface of the steel plate 1 by water injection. For the water droplets scattered and floating in the space above the steel plate 1, the injection area of the air was too narrow for the air to hit, and the effect of removing the scattered water floating in the space could not be obtained.

[0020] Therefore, in the present embodiment, in order to obtain an air flow in a wide range, a large blower as shown in FIG. 1 is arranged.

[0021] First, the first blower 6 is installed above the steel plate 1 between the water injection type draining facility 4 and the flaw detection device 8. The first blower 6 is provided, for example, with a gantry on the rolling line and is detachably attached above the rolling line with a fixing jig. Then, from the direction opposite to the passing direction PL of the steel plate 1, an air flow is blown toward the surface of the steel plate 1 so as to blow it down. In order to surely drop the water droplets in the space above the steel plate 1, the first blower 6 generates an air flow having a width covering the entire width direction of the steel plate. When the width of the air flow is insufficient with one blower, a plurality of blowers are used.

[0022] When the first blower 6 is composed of a plurality of blowers, it is preferable to arrange the blower arranged on the end side of the steel plate 1 downstream in the passing direction of the metal plate than the blower on the center side. The scattered water can be blown down to the steel plate side and blown out to the outside in the width direction of the steel plate 1. When installing a plurality of blowers, if they are arranged side by side in the width direction, a gap is formed between the blowers when viewed from the passing direction PL, and a region with a slow air flow velocity is generated, and there is a concern that the scattered water may slip through. On the contrary, if the blower arranged on the end side of the steel plate 1 is arranged upstream in the passing direction of the metal plate than the blower on the center side, the scattered water that has been blown down will be collected in the center, and there is a possibility that it will remain on the upper surface of the steel plate 1 as water droplets.

[0023] The height of the space where the scattered water exists depends on the peripheral speed of the conveying roller 5, that is, the passing speed of the steel plate 1. In the case of a passing speed of 20 m / s (1200 m / min), it is about 2 m. Therefore, it is preferable for the first blower 6 to blow down from a higher height. The first blower 6 is preferably a blower defined in JIS B 0132:2005 and is preferably a fan capable of generating an air flow with a wind speed of 20 m / s or more. It is more preferable to set it to 25 m / s or more. It can remove scattered water droplets with a diameter of about 3 mm. Since a compressor is required to exceed a wind speed of 100 m / s, it is preferable to set 100 m / s as the upper limit. More preferably, the wind speed is 30 m / s or less. For example, a circular blower with a diameter of 500 to 1000 mm can be used.

[0024] Also, the inclination angle of the first blower 6 is an angle that inclines from the vertical direction to the upstream side of the passing direction PL, and it is preferably 10° or more and 20° or less. From the viewpoint of removing water droplets, an effect can be obtained by setting it to 10° or more and less than 45°. On the other hand, the tip of the hot-rolled steel strip often deforms into a sickle shape as shown in FIG. 4. Depending on the angle and flow velocity of the air flow, there is a risk that the tip will lift up and hinder the passing property. If the inclination angle of the first blower 6 exceeds 20°, there is a concern about hindering the passing property due to the lifting of the steel plate tip, so it is preferably 20° or less.

[0025] The second blower 7 is installed above the widthwise end of the steel plate 1 between the first blower 6 and the flaw detection device 8 in the plate passing direction PL. The second blower 7 is, for example, height-adjustable and detachably attached with a fixing jig to pedestals erected on both sides in the width direction of the press line. The direction of the air flow of the second blower 7 blows in a direction substantially orthogonal to the plate passing direction PL. In the present invention, the direction orthogonal to the plate passing direction PL is allowed to be a direction within 90° ± 10° with respect to the plate passing direction PL. The second blower 7 has a function of efficiently removing the scattered water that the first blower has blown off onto the upper surface of the steel plate 1 from one end to the other end in the width direction of the steel plate 1. In that regard, it is preferable that the second blower 7 has a depression angle looking down on the steel plate 1 of 15° or less. Preferably, the depression angle is more than 0° and 10° or less. Also, when water intrusion is observed on the lower surface of the steel plate 1, it is preferable to install it so that the air flow also hits the lower surface.

[0026] The second blower 7 is preferably installed on both sides of the steel plate 1. It is preferable to shift the central axes of the air flows of the respective blowers in a top view so that the air flows do not interfere with each other. Also, it is preferable to direct the central axis of the air flow to be near the center in the width direction of the steel plate 1. The second blower 7 is preferably a blower defined in JIS B 0132:2005 and is a fan capable of generating an air flow with a wind speed of 20 m / s or more. More preferably, it is 25 m / s or more. It can remove water droplets with a diameter of about 3 mm. Since a compressor is required to exceed a wind speed of 100 m / s, it is preferable to set 100 m / s as the upper limit. More preferably, the wind speed is 30 m / s or less.

[0027] In this embodiment, there is a switchboard having a function of displaying the usage status of the first blower and the second blower. It may be a lamp indicating the energized state, or a display or gauge for displaying the rotational speed of the blower. The blower determined to have a problem can be replaced by removing the fixing jig.

Example

[0028] (Example 1) In the hot rolling equipment of FIG. 1, the possibility of removing scattered water was examined by fluid analysis with the arrangement of the first blower 6 and the second blower 7 shown in FIG. 2(a). Simcenter STAR-CCM+ was used as the fluid analysis software. The width of the steel plate 1 was set to 1.5 m, and the passing speed was set to 20 m / s. Both the first blower 6 and the second blower 7 were circular with a diameter of 700 mm, and the air flow FA had a wind speed of 20 m / s. The central axis of the air flow of the first blower 6 was inclined 25° from the vertical direction to the upstream side of the passing direction PL of the steel plate 1. The depression angle of the second blower 7 was set to 10°. It was set as the initial condition at the entrance of the calculation space that the scattered water FD was moving in the passing direction at 5 m / s. The fluid analysis results are shown in FIG. 2(b).

[0029] In this embodiment, the air flow from the first blower 6 is blown down over the entire width direction of the steel plate 1. And the central axis of the air flow FA intersects the steel plate 1 on the upstream side of the passing direction PL of the steel plate 1 with the central side in the width direction being upstream of the end side in the width direction. In this embodiment, there is no trajectory of the scattered water FD passing through to the downstream on the steel plate 1 within the calculation space, and all of them can be removed to the outside of the side of the steel plate 1.

[0030] (Example 2) The blowers as shown in FIGS. 3(a) to (e) were arranged, and numerical analysis was performed under the same conditions as in Example 1, and the results are shown in Table 1. The amount of remaining water droplets was calculated as the ratio flowing out from the flaw detection device from the streamline of the scattered water. FIG. 3(a) shows the first blowers arranged side by side in the width direction. FIGS. 3(b) and (d) show the first blowers arranged to be convex on the upstream side. FIGS. 3(c) and (e) show the first blowers arranged to be convex on the downstream side. FIGS. 3(a) to (c) show the second blower arranged on the downstream side of the first blower. FIGS. 3(d) and (e) show the second blower arranged on the upstream side of the first blower. It can be seen that the water droplets remaining on the steel plate in the arrangement of FIG. 3(b) become zero, which is excellent.

[0031]

Table 1

[0032] (Example 3) Figure 4 is a schematic diagram showing the result of calculating, using fluid analysis software Simcenter STAR-CCM+, the pressure distribution exerted by the airflow blown down from the first blower with the configuration shown in Figure 1 on the tip of the steel plate 1. The steel plate 1 is moving on the conveying roll 5 at a conveying speed of 20 m / s in the plate passing direction PL. The steel plate 1 is made of SPHC with a plate thickness of 1.2 mm and a plate width of 0.7 m, and the maximum height of the sickle-shaped (the state where the foremost end of the steel plate warps upward during plate passing and becomes S-shaped like the head of a snake) is set at 1 m from the upper end of the conveying roll 5. The first blower has an inclination angle of 15° and an airflow velocity of 25 m / s. The force P1 pressing the steel plate 1 applied to the sickle-shaped front end of the steel plate was 84 N and had an inclination of 15 to 30° from vertically downward. Its vertical component P 1V was 74 to 81 N. On the other hand, the lifting force P2 applied to the rear part of the sickle was 84 N and had an inclination of 50 to 70° from vertically upward. Its vertical component P 2V was 28 to 54 N. Therefore, from the relationship of P 1V >P 2V , it can be seen that the tip of the steel plate 1 does not lift up and there is no problem with the plate passing property.

[0033] (Example 4) By changing the blowing-down angle of the first blower and performing numerical analysis under the same conditions as in Example 3, the results are shown in Table 2. Table 2 describes the presence or absence of scattered water passing as an evaluation of the water droplet removal property. It can be seen that when the blowing-down angle is 15°, there is no passing of scattered water, no lifting of the tip, and it is comprehensively excellent.

[0034]

Table 2

[0035] (Example 5) In the conventional example described in Patent Document 3, there was false detection by water droplets in several percent of coils of steel grades that require strict surface inspection, and it was necessary to perform visual observation on a separate line. In contrast, when blowing an airflow of 20 m / s from the first blower at an inclination angle of 15° with the apparatus arrangement shown in Figure 1, there was no false detection by water droplets in 99.8% of coils of the same steel grade, and excellent effects were obtained.

Industrial Applicability

[0036] According to the metal sheet drainage device during sheet passing, the hot rolling equipment, and the method for manufacturing a hot rolled steel strip of the present invention, it is possible to prevent water droplets scattered above the metal sheet from being erroneously detected by the optical inspection device, and visual inspection can be omitted. In addition, it contributes to the improvement of productivity such as no lifting of the tip of the steel sheet and excellent sheet passing property. Since no compressor is used, it also leads to a reduction in equipment costs. Therefore, it is industrially useful.

Explanation of Signs

[0037] 1 Steel sheet (metal sheet, hot rolled steel strip) 2 Finishing rolling mill 3 Cooling equipment (water spraying equipment) 4 Water injection type drainage equipment (fluid injection type drainage equipment) 5 Conveyor roller 6 First fan (air blower) 7 Second fan (air blower) 8 Defect detection device (inspection device) 9 Pinch roll 10 Reel PL Pass line (sheet passing direction of metal sheet) FD Scattered water FA Airflow

Claims

1. A water draining device for a metal plate that is passed through a rolling line, sequentially water-cooled and drained by a water-cooling facility and a fluid injection type water draining facility installed in parallel with the water-cooling facility after finish rolling, then subjected to a predetermined inspection by a surface inspection device, and then wound up by a winder, comprising: A plurality of first blowers are installed between the fluid injection type water draining facility and the inspection device, and blow airflows with a wind speed of 20 m / s or more from above across the entire width direction of the metal plate as viewed from the passing direction of the metal plate in a direction opposite to the passing direction of the metal plate; A first pedestal for fixing the first blower above the rolling line; A second blower installed between the first blower and the inspection device, and blowing air in a direction substantially orthogonal to the passing direction of the metal plate; A second pedestal for fixing the second blower to an end portion in the width direction of the rolling line; Fixing jigs for fixing the first blower and the second blower to the first pedestal and the second pedestal respectively; A power panel having a function of displaying the usage status of the first blower and the second blower; and having, When there are a plurality of the first blowers, the blowers arranged on the end side of the metal plate are arranged downstream in the passing direction of the metal plate from the blowers on the central side; The inclination angle of the first blower is an angle inclined upstream in the passing direction of the metal plate from the vertical direction, and is 10° or more and 20° or less; The usage status is the energization state of the blower or the rotation speed of the blower. A water draining device for a metal plate during passing.

2. The water draining device for a metal plate during passing according to claim 1, wherein a plurality of the second blowers are arranged on both end sides in the width direction of the metal plate, and the airflows blown from the respective blowers are arranged so as not to interfere with each other.

3. A hot rolling facility in which a metal plate is passed through a rolling line, sequentially water-cooled and drained by a water-cooling facility and a fluid injection type water draining facility installed in parallel with the water-cooling facility after finish rolling, then subjected to a predetermined inspection by a surface inspection device, and then wound up by a winder, comprising: A hot rolling facility having the water draining device for a metal plate during passing according to claim 1 or 2.

4. In the production of a hot-rolled steel strip, the hot-rolled steel strip is passed through, water-cooled after finish rolling, fluid is sprayed to drain the steel strip surface, then surface inspection is carried out, and then it is wound by a winder. Before the surface inspection, the water-draining device for passing a metal plate according to claim 1 or claim 2 is used to remove water droplets on the steel strip. A method for producing a hot-rolled steel strip.

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