Steel sheet polishing equipment and method for manufacturing annealed steel sheet

Abstract

To provide steel sheet polishing equipment capable of removing an oxide generated on a steel sheet in continuous annealing equipment before the oxide attaches to a transport roll.SOLUTION: A steel sheet polishing equipment polishes a steel sheet in continuous annealing equipment including a plurality of transport rolls. The steel sheet polishing equipment includes: a first polishing roll that polishes the steel sheet; and a driving device that rotatingly drives the first polishing roll.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a steel plate polishing facility for polishing a steel plate in a continuous annealing facility and a method for manufacturing an annealed steel plate.

Background Art

[0002] In recent years, the demand for high-tensile steel plates has been increasing, and the production ratio of high-tensile steel plates has been rising. It has been shown that high-tensile steel plates can potentially be manufactured into steel plates that are advantageous for strength and processing by adding Si and Mn. On the other hand, when manufacturing high-tensile steel plates in a continuous annealing process, from the perspective of increasing strength, a process of cooling the heated steel plate is necessary. Also, from the perspective of press formability, a tempering process of reheating the cooled steel plate is required.

[0003] The steel plate is subjected to a tempering process, for example, being preheated to about 150°C in a preheating zone, heated to about 800°C in an oxidation-reduction zone, and rapidly cooled to 500°C in a rapid cooling zone. At that time, in a steel plate containing easily oxidizable elements such as Si and Mn, the added elements such as Si and Mn are concentrated on the surface of the steel plate in the reduction zone, and these oxides are generated. The roll deposits formed by these oxides adhering to the conveying rolls cause push marks (surface defects) on the steel plate.

[0004] As a technique for preventing push marks on the steel plate caused by roll deposits, Patent Document 1 discloses a method of preventing push marks by using a wear-resistant coating so that the roll deposit material falls off with wear. Patent Document 2 discloses a method of detecting deposits with an image processing device and removing the deposits on the roll surface with a contact body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Although the techniques disclosed in Patent Documents 1 and 2 can remove roll deposits, in a continuous annealing facility, it has been insufficient to suppress the rapid growth of deposits on the conveying rolls due to steel sheets containing Mn or Si, which are easily oxidizable elements, in a high-temperature environment. The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a polishing facility for a steel sheet capable of removing oxides generated on the steel sheet before they adhere to the conveying rolls within a continuous annealing facility, and a method for manufacturing an annealed steel sheet in which the steel sheet is polished by the polishing facility and the annealed steel sheet is manufactured by the continuous annealing facility. [Means for Solving the Problems]

[0007] The means for solving the above problems are as follows. [1] A polishing facility for a steel sheet that polishes a steel sheet in a continuous annealing facility having a plurality of conveying rolls, the polishing facility for a steel sheet having a first polishing roll that polishes the steel sheet and a driving device that rotationally drives the first polishing roll. [2] The polishing facility for a steel sheet according to [1], wherein the first polishing roll is a brush roll having a plurality of metal wires protruding radially from the peripheral surface. [3] The polishing facility for a steel sheet according to [2], wherein the diameter of the wire is 20 μm or more and 500 μm or less. [4] The polishing facility for a steel sheet according to [2] or [3], wherein the wire is made of tungsten, molybdenum, cobalt, nickel-chromium alloy, or stainless steel. [5] The polishing facility for a steel sheet according to any one of [1] to [4], having a polishing member that contacts the first polishing roll, and the polishing member being a flat plate, a grinding stone, or a second polishing roll. [6] The polishing facility for a steel sheet according to any one of [1] to [5], having a recovery device that recovers the dropped matter from the first polishing roll. [7] A method for manufacturing an annealed steel sheet, which comprises polishing a steel sheet with a polishing facility for a steel sheet according to any one of [1] to [4], and annealing the steel sheet with the continuous annealing facility to manufacture an annealed steel sheet.

Advantages of the Invention

[0008] By using the polishing facility for a steel sheet according to the present invention, deposits such as oxides formed on the steel sheet in the continuous annealing facility can be removed before they adhere to the conveying rolls. As a result, the adhesion of deposits to the conveying rolls is suppressed, so that the growth of deposits adhering to the conveying rolls can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments show a preferred example of the present invention, and the present invention is not limited by these embodiments.

[0011] The polishing equipment for steel plates according to this embodiment is preferably used for polishing the steel plate 10 in the continuous annealing equipment 100. First, the continuous annealing equipment 100 will be described. FIG. 1 is a schematic diagram showing a configuration example of the continuous annealing equipment 100. The continuous annealing equipment 100 includes a heating zone 12, a soaking zone 14, a cooling zone 16, and an overaging zone 18. In addition, the continuous annealing equipment 100 may be provided with equipment for performing surface treatment such as zinc plating as necessary.

[0012] In the heating zone 12, equipment for raising the temperature of the steel plate 10 is provided. In the heating zone 12, a direct-fired or radiant combustion burner is used. In the heating zone 12, the steel plate 10 is heated to a preset temperature of about 600 to 900 °C according to its component composition.

[0013] In the soaking zone 14, equipment for holding the steel plate 10 at a predetermined temperature is provided. The equipment for holding the steel plate 10 at a predetermined temperature is equipment with a heating capacity that compensates for heat dissipation from the furnace body and the like.

[0014] In the cooling zone 16, equipment for cooling the steel plate 10 to a predetermined temperature is provided. As the cooling means in the cooling zone 16, liquid cooling, gas jet cooling, roll cooling, mist cooling (gas-liquid mixed cooling), etc. are used. Liquid cooling is often performed by water cooling (water quench) using water. Water cooling is a cooling means in which the steel plate 10 is immersed in an immersion water tank installed on the downstream side of the soaking zone 14 for cooling. Gas jet cooling is a cooling means in which gas is blown from a nozzle onto the surface of the steel plate 10. Roll cooling is a cooling means in which the steel plate 10 is brought into contact with a water-cooled roll for cooling. Mist cooling is a cooling means in which water is sprayed in a fine mist and the steel plate 10 is cooled by absorbing the heat of vaporization. In mist cooling, the size of the sprayed water droplets is often about 0.1 to 1 mm.

[0015] The overaging zone 18 is a facility for performing an overaging treatment in which the steel sheet 10 is reheated to a temperature of about 300 to 400 °C and held at that temperature for a predetermined time. In such a continuous annealing facility 100, the steel sheet 10 is heated and reduced in the heating zone 12 and the soaking zone 14 in a reducing atmosphere composed of a mixed gas such as hydrogen and nitrogen, cooled in the cooling zone 16, and stress-relieved in the overaging zone 18.

[0016] When the contents of Si and Mn in the steel sheet 10 processed by the continuous annealing facility 100 are 0.3 mass% or more, Si and Mn in the steel sheet 10 are likely to be oxidized and concentrated on the surface layer. Si and Mn are elements effective for improving the mechanical properties of the steel sheet 10, and among Si and Mn, Si is more likely to be oxidized. Therefore, in the case of Si-added steel, while SiO2 is generated on the surface layer of the steel sheet 10, the generation of Mn oxide tends to be suppressed. However, in a steel sheet with a low Si content, Mn is most likely to be concentrated on the surface layer, so Mn oxide of the steel sheet 10 is generated and concentrated on the surface layer.

[0017] There is a high correlation between the concentration of oxides on the surface layer of the steel sheet 10 and the adhesion of the oxides to the conveying rolls. The higher the temperature of the steel sheet 10, the more the concentration of oxides of Si and Mn on the surface layer of the steel sheet 10 is promoted. The oxides of Si and Mn concentrated on the surface layer of the steel sheet 10 adhere to the surface of the conveying rolls. When the oxides of Si and Mn adhering to the surface of the conveying rolls are heated, a sintered body of the oxides is formed and fixed to the surface of the conveying rolls. Since the temperature at which the sintered body is formed is about half of the melting point of the oxides, it becomes remarkable when the surface temperature of the conveying rolls exceeds 700 °C.

[0018] In a vertical continuous annealing facility, since the steel sheet 10 is conveyed by being wound around the conveying rolls, strain corresponding to the roll curvature of the conveying rolls is introduced. In order to reduce the introduction of strain during conveyance, in a vertical continuous annealing facility, conveying rolls with a larger diameter are used compared to a horizontal continuous annealing facility. In a vertical continuous annealing facility, conveying rolls with a diameter of 400 mm or more are preferably used.

[0019] On the one hand, when the diameter of the conveying roll increases, due to thermal expansion, the diameter of the central part in the axial direction of the conveying roll becomes larger than that of both ends, and the difference in the roll circumference between the central part and both ends becomes larger. As a result, a speed difference occurs between the steel plate 10 and the conveying roll depending on the axial position of the conveying roll, and the oxide concentrated on the surface layer of the steel plate 10 easily adheres to the conveying roll due to rubbing between the steel plate 10 and the surface of the conveying roll.

[0020] For the conveying rolls of the continuous annealing facility 100, rolls sprayed with cermet or ceramics are used to reduce the reactivity and adhesion with deposits. However, even when such rolls are used, if the oxide concentrated on the surface layer of the steel plate 10 firmly adheres to the conveying roll, it does not easily fall off from the roll surface, and deposits grow starting from that location, causing pressing flaw defects in the conveyed steel plate 10.

[0021] In order to suppress the occurrence of such pressing flaw defects, a steel plate polishing facility according to this embodiment is provided upstream of the conveying roll in the conveying direction of the steel plate 10. As a result, deposits such as oxides concentrated on the surface layer of the steel plate 10 can be removed by this polishing facility before adhering to the conveying roll, so that the adhesion of deposits to the surface of the conveying roll and the growth of deposits are suppressed, and the occurrence of pressing flaw defects in the steel plate 10 can be suppressed.

[0022] Also, as described above, when the surface temperature of the conveying roll reaches 700°C or higher, oxides adhere to the conveying roll and tend to adhere firmly. Therefore, the steel plate polishing facility according to this embodiment is preferably used for polishing the steel plate 10 conveyed in the heating zone 12 or the soaking zone 14 where the steel plate 10 is heated to 700°C or higher in the continuous annealing facility 100. However, even when it is below 700°C, oxides concentrated adhere to the surface layer of the steel plate 10, so the steel plate polishing facility according to this embodiment may also be applied to the steel plate 10 conveyed at 700°C or lower.

[0023] Figure 2 is a side schematic view showing a configuration example of the steel plate polishing equipment 30 according to the present embodiment. The steel plate polishing equipment 30 according to the present embodiment includes a first polishing roll 32, a flat plate 34, a recovery container 36, and a driving device (not shown) for rotationally driving the first polishing roll 32. The first polishing roll 32 is provided in contact with the steel plate 10 on the upstream side in the conveying direction of the steel plate 10 with respect to the conveying roll 20 on the furnace top side.

[0024] The first polishing roll 32 is preferably provided at a position for polishing the surface of the steel plate 10 and the surface on which the conveying roll 20 provided on the downstream side in the conveying direction of the steel plate 10 in the steel plate polishing equipment 30 contacts the steel plate 10 among the front and back surfaces of the steel plate 10. However, a large number of conveying rolls 20 are provided in the continuous annealing equipment 100, and the surfaces in contact with the steel plate 10 of the conveying rolls 20 alternate. Therefore, the surface of the steel plate 10 polished by the steel plate polishing equipment 30 according to the present embodiment may be either the front surface or the back surface of the steel plate 10.

[0025] The first polishing roll 32 is a brush roll having a plurality of metal wires protruding radially from the roll circumferential surface. By using a brush roll for the first polishing roll 32, even if the deposits removed from the steel plate 10 adhere to the first polishing roll 32, the starting point where the deposits adhere is not the surface but the tip of the wire, and the contact area becomes small, so the adhesive force also becomes small. Therefore, even when the deposits adhere to the first polishing roll 32, since the adhesive force between the polishing roll and the deposits is small, the deposits can be easily removed from the first polishing roll 32.

[0026] The first grinding roll 32 is preferably a barrel-shaped roll (crown roll) in which the diameter of the central portion in the axial direction of the first grinding roll 32 is larger than the diameters of both end portions, and the central portion and both end portions are smoothly connected by a tapered shape or an R shape. FIG. 3 is a schematic side view of the conveying roll 20 used in the heating zone 12 of the continuous annealing facility 100. As shown in FIG. 3, when the conveying roll 20 is used in the heating zone 12 or the soaking zone 14 of the continuous annealing facility 100, the conveying roll 20 thermally expands by contacting the high-temperature steel sheet 10, and a thermal crown is formed on the conveying roll 20. Due to the thermal crown of the conveying roll 20, the conveyed steel sheet 10 also deforms. Therefore, the first grinding roll 32 is preferably a barrel-shaped roll corresponding to the thermal crown shape. Note that the thermal crown shape of the conveying roll 20 can be estimated in advance by analysis using continuous annealing conditions.

[0027] The first grinding roll 32 is rotated by a driving device in the same direction as the steel sheet 10 at the contact position with the steel sheet 10 so that a speed difference occurs between the first grinding roll 32 and the steel sheet 10. In this way, by rotating the first grinding roll 32 in the same direction at the contact position with the steel sheet 10 so that a speed difference occurs, over-grinding of the steel sheet 10 is suppressed, and deposits such as oxides concentrated on the surface layer of the steel sheet 10 can be removed. On the other hand, if the first grinding roll 32 is rotated in the opposite direction at the contact position with the steel sheet 10, it will result in over-grinding and scratches will occur on the steel sheet 10, which is not preferable.

[0028] It is preferable to rotate the first grinding roll 32 so that the speed difference between the steel sheet 10 and the first grinding roll 32 is 0.5 m / min or more and 15 m / min or less. Thereby, while suppressing scratches on the steel sheet 10, deposits such as oxides concentrated on the surface layer can be efficiently removed. On the other hand, if the speed difference between the steel sheet 10 and the first grinding roll is less than 0.5 m / min, the deposits cannot be efficiently removed, which is not preferable. Also, if the speed difference between the steel sheet 10 and the first grinding roll is greater than 15 m / min, the scratches generated on the steel sheet 10 will become prominent, which is not preferable.

[0029] The diameter of the wire of the brush roll is preferably 20 μm or more and 500 μm or less. Thereby, while suppressing an increase in the manufacturing cost of the brush roll and a shortening of the life of the brush roll, it is possible to enhance the detachability of the adherent. On the other hand, if the diameter of the wire is less than 20 μm, it becomes difficult to mass-produce the brush roll, and the manufacturing cost of the brush roll increases, which is not preferable. Further, if the diameter of the wire is less than 20 μm, the wear of the wire becomes fast and the life of the brush roll becomes short, which is not preferable. Also, if the diameter of the wire is larger than 500 μm, the contact area between the adherent and the wire becomes large, and the detachability of the adherent decreases, which is not preferable.

[0030] The wire is preferably made of tungsten, molybdenum, cobalt, nickel-chromium alloy or stainless steel having heat resistance and wear resistance. Thereby, even in a high-temperature environment of 700 ° C. or higher, the steel plate 10 can be polished to remove the adherent.

[0031] For the roll part of the first polishing roll 32, it is preferable to use a metal having excellent heat resistance such as heat-resistant cast steel, chromium alloy or nickel alloy. The roll diameter of the first polishing roll 32 is smaller than the roll diameter of the conveying roll 20 and is preferably 100 mm or more. Thereby, it is possible to suppress a decrease in the roll life of the first polishing roll 32 and deformation due to deflection. Also, the wire density in the first polishing roll 32 is preferably 3 / 5 or more with respect to the roll surface area in which the wire is embedded. By using a high-density brush roll with a high wire density, damage to the wire due to wear is reduced, and the durability of the brush roll is improved.

[0032] The flat plate 34 is a steel or ceramic plate that contacts the first polishing roll 32 and polishes the first polishing roll. By polishing the first polishing roll 32 with the flat plate 34, the adherent removed from the steel plate 10 can be removed when the adherent adheres to the first polishing roll 32. Note that the flat plate 34 is an example of a polishing member that contacts the circumferential surface of the first polishing roll 32, and a grindstone or a polishing roll may be used instead of the flat plate.

[0033] The recovery container 36 is a steel box for recovering the deposits that fall off the first polishing roll 32 (hereinafter referred to as "fallen-off matter"). By providing the recovery container 36, the fallen-off matter from the first polishing roll 32 can be recovered, and it is possible to prevent the fallen-off matter from adhering to the steel plate 10 again or adhering to the continuous annealing facility 100. Note that the recovery container 36 is an example of a recovery device for recovering the fallen-off matter from the first polishing roll 32.

[0034] FIG. 4 is a schematic side view showing another configuration example of the steel plate polishing facility according to the present embodiment. In the steel plate polishing facility 40 shown in FIG. 4, the same components as those in the steel plate polishing facility 30 shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The steel plate polishing facility 40 shown in FIG. 4 is different from the steel plate polishing facility 30 shown in FIG. 2 in that it has a second polishing roll 38 instead of the flat plate 34.

[0035] As shown in FIG. 4, the first polishing roll 32 may be polished using the second polishing roll 38. The second polishing roll 38 is, for example, a roll obtained by performing cermet spraying or ceramic spraying on the peripheral surface of a roll made of heat-resistant cast steel. The second polishing roll 38 is another example of a polishing member that contacts the peripheral surface of the first polishing roll 32.

[0036] The second polishing roll 38 is preferably rotated in a direction opposite to the rotation direction of the first polishing roll 32 at the contact position with the first polishing roll 32. Thereby, the falling off of the deposits adhering to the first polishing roll 32 can be promoted.

[0037] Further, since the brush roll is used for the first polishing roll 32, if there is a peripheral speed difference between the first polishing roll 32 and the second polishing roll 38, it is not necessary to rotate them in opposite directions at the contact position. That is, when there is a peripheral speed difference between the first polishing roll 32 and the second polishing roll 38, the second polishing roll 38 may be rotated in the same direction as the rotation direction of the first polishing roll 32 at the contact position between the first polishing roll 32 and the second polishing roll 38.

[0038] FIG. 5 is a schematic side view showing another configuration example of the steel plate polishing equipment according to the present embodiment. In the steel plate polishing equipment 50 shown in FIG. 5, the same components as those of the steel plate polishing equipment 30 shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The steel plate polishing equipment 50 shown in FIG. 5 is different from the steel plate polishing equipment 30 shown in FIG. 2 in that the steel plate polishing equipment 50 is provided near the conveying roll 20 on the hearth side. As shown in FIG. 5, the steel plate polishing equipment 50 according to the present embodiment can also be provided upstream of the conveying roll 20 for the steel plate 10 provided on the hearth side in the conveying direction of the steel plate 10.

[0039] As described above, since the steel plate polishing equipment according to the present embodiment can be provided in the conveying path of the steel plate 10 in the continuous annealing equipment 100, it is preferable to install a plurality of the steel plate polishing equipment according to the present embodiment in the continuous annealing equipment 100. By installing a plurality of the steel plate polishing equipment according to the present embodiment, the ability to remove the deposits adhering to the steel plate 10 can be enhanced.

[0040] As described above, by using the steel plate polishing equipment according to the present embodiment, deposits such as oxides generated on the steel plate 10 can be removed before adhering to the conveying roll 20, thereby suppressing the adhesion and growth of deposits on the surface of the conveying roll 20. Further, by suppressing the growth of deposits on the conveying roll 20 in this way, the occurrence of pressing flaw defects caused by the deposits on the steel plate 10 can also be suppressed. That is, in the continuous annealing equipment 100, by polishing the steel plate 10 with the steel plate polishing equipment according to the present embodiment, the production of annealed steel plates with suppressed pressing flaw defects can be realized.

[0041] In the present embodiment, an example in which a brush roll is used as the first polishing roll in the steel plate polishing equipment 30, 40, and 50 has been described, but the present invention is not limited thereto. As the first polishing roll, a polishing roll obtained by performing cermet spraying or ceramic spraying on the peripheral surface of a roll made of heat-resistant cast steel may be used. However, as described above, by using a brush roll as the first polishing roll, even if deposits adhere to the brush roll, they can be easily removed. Therefore, the first polishing roll is preferably a brush roll.

[0042] In addition, in this embodiment, although the polishing facilities 30, 40, and 50 for steel plates have been described as having a polishing member and a recovery device, the present invention is not limited to this. As a configuration for solving the problem of removing the deposits on the steel plate 10, the polishing facilities 30, 40, and 50 for steel plates may not have a polishing member and a recovery device. However, as described above, by having a polishing member, the deposits adhering to the first polishing roll can be removed, and by having a recovery device, it is possible to suppress the re - adhesion of the dropped matter from the first polishing roll to the steel plate 10 or the like. Therefore, it is preferable that the polishing facilities 30, 40, and 50 for steel plates have a polishing member and a recovery device.

Example

[0043] [Example 1] Next, Example 1 will be described in which, in the continuous annealing facility 100 shown in FIG. 1, after continuously annealing a steel plate containing 0.3 mass% or more of Si or Mn by 2000 tons or more, the number of deposits of 100 μm or more adhering to the conveying roll was confirmed. The plate thickness of the steel plate continuously annealed in Example 1 is in the range of 0.6 to 1.8 mm, and the plate width is in the range of 800 to 1500 mm. The continuous annealing conditions are as follows.

[0044] Atmospheric temperature: 700 °C or higher Atmospheric gas: 5 vol% hydrogen, 95 vol% nitrogen Dew point: - 35 °C

[0045] After continuous annealing, the conveying roll installed on the furnace top side at the rear stage of the soaking zone where the temperature of the steel plate is the highest in the continuous annealing facility 100 was taken out, and the number of deposits of 100 μm or more adhering to the conveying roll was confirmed with a laser microscope.

[0046] In the inventive example, a polishing facility 30 for the steel plate shown in Fig. 2 was installed on the upstream side of the above-described conveying roll and on the surface side in contact with the conveying roll. As the first polishing roll, a polishing roll or a brush roll obtained by thermally spraying cermet on the peripheral surface of a roll made of heat-resistant cast steel with a roll diameter of 300 mm was used. The wire of the brush roll is made of Ni-Cr alloy, the wire diameter is 300 μm, the length to the wire tip is 15 mm, and the wire density is 3 / 5 in terms of the ratio of the wire embedding area to the roll surface area. Also, the speed difference between the roll rotation speed of the first polishing roll and the steel plate speed is 2 m / min, and the pressing force of the first polishing roll against the steel plate was adjusted to 0.02 kgf / mm. As the polishing member, a flat plate made of ceramic was used. On the other hand, in the comparative example, continuous annealing was carried out without installing the polishing facility 30 for the steel plate. The results of Example 1 are shown in Table 1 below.

[0047]

Table 1

[0048] As shown in Table 1, in Inventive Examples 1-4 where the steel plate was polished with the first polishing roll, the number of deposits of 100 μm or more adhering to the surface of the conveying roll was less than that in the comparative example where the first polishing roll was not used. From this result, it was confirmed that by using the polishing facility for the steel plate according to the present embodiment, deposits on the steel plate can be removed before adhering to the conveying roll, and thereby, it can be suppressed that deposits adhere and grow on the surface of the conveying roll.

[0049] Also, in Inventive Examples 2 and 4 where a brush roll was used as the first polishing roll, the number of deposits of 100 μm or more adhering to the surface of the conveying roll was less than that in Inventive Examples 1 and 3 where a normal polishing roll was used. From this result, it was confirmed that it is preferable to use a brush roll as the first polishing roll, and thereby, the number of deposits adhering to the conveying roll can be further reduced.

[0050] Furthermore, in Invention Examples 1 and 2 where a flat ceramic plate was provided as the polishing member, the number of deposits of 100 μm or more adhering to the surface of the conveying roll was less than that in the corresponding Invention Examples 3 and 4. From this result, it was confirmed that it is preferable to provide a polishing member for polishing the first polishing roll, and thereby the number of deposits adhering to the conveying roll can be further reduced.

[0051] [Example 2] Next, Example 2 in which the influence of the diameter of the wire in the brush roll was confirmed will be described. In Example 2, in a furnace with the furnace temperature controlled at 800°C, a steel plate with a Si content of 1.6% by mass and a Mn content of 0.3% by mass was polished with a small sample of the brush roll, and the adhesion state of the deposits adhering to the brush roll due to the polishing was confirmed. The test conditions for Example 2 are as follows.

[0052] Wire material: Ni-Cr alloy Wire length: 12 mm Sliding time: 30 h Sliding speed: 300 mm / min Surface pressure between the steel plate and the brush roll: 0.001 kg / mm 2 Wire density of the brush roll: 3 / 5 as the ratio of the wire embedding area to the roll surface area

[0053] After polishing the steel plate with the brush roll for 30 hours under the above test conditions, the number of deposits of 30 μm or more adhering to the brush roll and the wear amount of the wire after polishing were measured. The number of deposits of 30 μm or more adhering to the surface of the brush roll was measured by observing the surface of the brush roll with a laser microscope. The wear amount of the wire was measured by measuring the wire length before and after the sliding test, and the difference between these was taken as the wear amount. The results of Example 2 are shown in Table 2 below.

[0054]

Table 2

[0055] As shown in Table 2, when the diameter of the wire of the brush roll is decreased, the wear amount of the wire becomes longer. In particular, when the diameter of the wire becomes less than 20 μm, it was confirmed that the wear amount of the wire becomes significantly longer. From this result, it was confirmed that the diameter of the wire is preferably 20 μm or more, whereby wear of the wire can be suppressed.

[0056] On the other hand, when the diameter of the wire increases, the contact area with the deposit increases, and the adhesion force of the deposit to the surface of the brush roll increases. In particular, when the diameter of the wire becomes larger than 500 μm, the adhesion force of the deposit adhering to the brush roll increases, and the number of deposits of 30 μm or more adhering to the surface of the brush roll becomes significantly larger. From this result, it was confirmed that the diameter of the wire of the brush roll is preferably 500 μm or less, whereby adhesion of the deposit can be suppressed.

Explanation of Signs

[0057] 10 Steel sheet 12 Heating zone 14 Soaking zone 16 Cooling zone 18 Overaging zone 20 Conveyor roll 30 Steel sheet polishing equipment 32 First polishing roll 34 Flat plate 36 Recovery container 38 Second polishing roll 40 Steel sheet polishing equipment 50 Steel sheet polishing equipment 100 Continuous annealing equipment

Claims

1. A steel plate polishing facility for polishing a steel plate in a continuous annealing facility having a plurality of conveying rolls, a first polishing roll for polishing the steel plate, and a driving device for rotationally driving the first polishing roll. The steel plate polishing facility comprises the above components.

2. The steel plate polishing facility according to claim 1, wherein the first polishing roll is a brush roll having a plurality of metal wires protruding radially from the circumferential surface.

3. The steel plate polishing facility according to claim 2, wherein the diameter of the wire is 20 μm or more and 500 μm or less.

4. The steel plate polishing facility according to claim 2 or claim 3, wherein the wire is made of tungsten, molybdenum, cobalt, nickel-chromium alloy or stainless steel.

5. The steel plate polishing facility according to any one of claims 1 to 3, further comprising a polishing member that contacts the first polishing roll, wherein the polishing member is a flat plate, a grinding stone or a second polishing roll.

6. The steel plate polishing facility according to claim 4, further comprising a polishing member that contacts the first polishing roll, wherein the polishing member is a flat plate, a grinding stone or a second polishing roll.

7. The steel plate polishing facility according to any one of claims 1 to 3, further comprising a recovery device for recovering the dropped matter from the first polishing roll.

8. The steel plate polishing facility according to claim 4, further comprising a recovery device for recovering the dropped matter from the first polishing roll.

9. The steel plate polishing facility according to claim 5, further comprising a recovery device for recovering the dropped matter from the first polishing roll.

10. The steel plate polishing facility according to claim 6, further comprising a recovery device for recovering the dropped matter from the first polishing roll.

11. A method for manufacturing an annealed steel plate, comprising polishing a steel plate with the steel plate polishing facility according to any one of claims 1 to 3 and then annealing the steel plate in the continuous annealing facility.

12. A method for manufacturing an annealed steel plate, comprising polishing a steel plate with the steel plate polishing facility according to claim 4 and then annealing the steel plate in the continuous annealing facility.

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