Steel sheet transport equipment and method for manufacturing annealed steel sheet

Abstract

To provide steel sheet transport equipment capable of inhibiting growth of an attached matter attached to a transport roll.SOLUTION: Steel sheet transport equipment transports a steel sheet in continuous annealing equipment. The steel sheet transport equipment includes: a transport roll that transports a steel sheet; and a polishing member that polishes the transport roll. The transport roll is a brush roll including a plurality of metallic wires projecting from a peripheral surface in a radial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

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

[0003] The steel sheet is subjected to a tempering process, for example, preheated to about 150°C in a preheating zone, heated to about 800°C in an oxidation-reduction zone, and quenched to 500°C in a quenching zone. At that time, in a steel sheet 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 sheet 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 sheet.

[0004] As a technique for preventing push marks on the steel sheet 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

Problems to be Solved by the Invention

[0006] Although the techniques disclosed in Patent Documents 1 and 2 can remove roll deposits, in a continuous annealing facility, it is insufficient to suppress the rapid growth of deposits on the conveying rolls by 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 steel sheet conveying facility capable of suppressing the growth of deposits adhering to the conveying rolls, conveying a steel sheet by the conveying facility, and a method for manufacturing an annealed steel sheet for manufacturing an annealed steel sheet by annealing the steel sheet in a continuous annealing facility.

Means for Solving the Problems

[0007] The means for solving the above problems are as follows. [1] A steel sheet conveying facility for conveying a steel sheet in a continuous annealing facility, comprising a conveying roll for conveying the steel sheet and a polishing member for polishing the conveying roll, wherein the conveying roll is a brush roll having a plurality of metal wires protruding radially from the peripheral surface. [2] The steel sheet conveying facility according to [1], wherein the diameter of the wire is 20 μm or more and 500 μm or less. [3] The steel sheet conveying facility according to [1] or [2], wherein the length of the wire is 1 mm or more and 30 mm or less. [4] The steel sheet conveying facility according to any one of [1] to [3], wherein the wire is made of tungsten, molybdenum, cobalt, nickel-chromium alloy or stainless steel. [5] The steel sheet conveying facility according to any one of [1] to [4], wherein the polishing member is a flat plate, a grindstone or a polishing roll. [6] The steel sheet conveying facility according to any one of [1] to [5], further comprising a recovery device for recovering the dropped matter from the conveying roll. [7] A method for manufacturing an annealed steel sheet, comprising conveying a steel sheet by the steel sheet conveying facility according to any one of [1] to [3] and annealing the steel sheet in the continuous annealing facility to manufacture an annealed steel sheet.

Advantages of the Invention

[0008] In the steel plate conveying equipment according to the present invention, by using a brush roll for the conveying roll that conveys the steel plate, the contact area between the adhering matter and the conveying roll is reduced, and the adhesion force is decreased. Therefore, by using a brush roll for the conveying roll, even if oxides adhere, they can be easily removed, and the growth of the adhering matter adhering to the conveying roll can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes 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 in any way.

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

[0012] The heating zone 12 is provided with equipment for heating the steel plate 10. 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] The soaking zone 14 is provided with equipment for maintaining the steel plate 10 at a predetermined temperature. The equipment for maintaining the steel plate 10 at a predetermined temperature is equipment with a heating capacity sufficient to supplement heat dissipation from the furnace body and the like.

[0014] The cooling zone 16 is provided with equipment for cooling the steel plate 10 to a predetermined temperature. As 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 post-aging zone 18 is equipment for performing a post-aging treatment in which the steel plate 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 plate 10 is heated and reduced in the heating zone 12 and the soaking zone 14 in a reducing atmosphere composed of a mixed gas of hydrogen, nitrogen, etc., cooled in the cooling zone 16, and tempered in the post-aging zone 18.

[0016] When the Si and Mn contents of the steel sheet 10 processed by the continuous annealing equipment 100 are 0.3% by mass or more, the Si and Mn in the steel sheet 10 are easily 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 easily 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] The concentration of oxides on the surface layer of the steel sheet 10 and the adhesion of the oxides to the conveying rolls are highly correlated with the temperature of the steel sheet 10. 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 roll. When the oxides of Si and Mn adhering to the surface of the conveying roll are heated, a sintered body of the oxides is formed and adheres to the surface of the conveying roll. Since the temperature at which the sintered body is formed is about half of the melting point of the oxide, it becomes prominent when the surface temperature of the conveying roll reaches 700 °C or higher.

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

[0019] On the other 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 the diameters of both ends, and the difference in roll circumference between the central part and both ends becomes larger. As a result, a speed difference occurs between the steel sheet 10 and the conveying roll depending on the axial position of the conveying roll, and the oxides concentrated on the surface layer of the steel sheet 10 are likely to adhere to the conveying roll due to the rubbing between the steel sheet 10 and the surface of the conveying roll.

[0020] For the conveying rolls of the continuous annealing equipment 100, rolls sprayed with cermet or ceramics are used to reduce the reactivity and adhesion with deposits. However, even if such rolls are used, if the oxides concentrated on the surface layer of the steel sheet 10 firmly adhere to the conveying rolls, they will not easily fall off from the roll surface, and deposits will grow starting from that location, causing push mark defects on the conveyed steel sheet 10.

[0021] To suppress the occurrence of such push mark defects, in the steel sheet conveying equipment according to this embodiment, a brush roll having a plurality of metal wires protruding radially from the circumferential surface of the roll is used for the conveying roll. By using the brush roll, even if the oxides concentrated on the surface layer of the steel sheet 10 adhere to the surface of the conveying roll, the starting point of the adhesion of the deposits is not the surface but the tip of the wire, and the contact area is small, so the adhesion force is also small. Therefore, the deposits adhering to the brush roll can easily fall off. For example, the deposits can be made to fall off by a slight speed difference or impact when passing the steel sheet, and the growth of the deposits can be suppressed. In this way, by using the brush roll for the conveying roll, the growth of deposits on the surface of the conveying roll can be suppressed, and thereby the occurrence of push mark defects on the steel sheet 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 are likely to adhere firmly. Therefore, the steel sheet conveying equipment according to this embodiment is preferably used for conveying the steel sheet 10 in the heating zone 12 or the soaking zone 14 where the steel sheet 10 is heated to 700°C or higher in the continuous annealing equipment 100. However, even if it is below 700°C, deposits adhere to the conveying roll, so the steel sheet conveying equipment according to this embodiment may also be applied to the steel sheet 10 conveyed below 700°C.

[0023] FIG. 2 is a schematic side view showing a configuration example of a steel sheet conveying facility 20 according to the present embodiment. The steel sheet conveying facility 20 according to the present embodiment includes a conveying roll 22, a polishing roll 24, and a recovery container 26. The conveying roll 22 is a brush roll having a plurality of metal wires protruding radially from the roll circumferential surface. Note that, as the driving device for rotationally driving the conveying roll 22, a driving device for rotationally driving a conveying roll other than a conventional brush roll can be used as it is.

[0024] The diameter of the plurality of metal wires protruding radially from the roll circumferential surface is preferably 20 μm or more and 500 μm or less. Thereby, it is possible to enhance the detachability of the adherends while suppressing an increase in the manufacturing cost of the brush roll and a shortening of the life of the brush roll. 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 adherend and the wire becomes large, and the detachability of the adherend decreases, which is not preferable.

[0025] The length to the tip of the plurality of metal wires protruding radially from the roll circumferential surface is preferably 1 mm or more and 30 mm or less. Thereby, it is possible to suppress a shortening of the life of the brush roll and to stably convey the steel sheet 10. On the other hand, if the length of the wire is less than 1 mm, the life of the brush roll becomes short due to the wear of the wire, which is not preferable. Also, if the length of the wire is longer than 30 mm, the wire is deformed due to a decrease in the density of the tip portion, and the conveyance of the steel sheet 10 becomes unstable, which is not preferable.

[0026] 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 conveying roll can be polished to remove adherends.

[0027] It is preferable to use a metal with excellent heat resistance such as heat-resistant cast steel, chromium alloy, or nickel alloy for the roll portion of the brush roll. Further, the wire density in the brush roll 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.

[0028] The polishing roll 24 is, for example, a roll obtained by applying cermet spraying or ceramic spraying to the peripheral surface of a roll made of heat-resistant cast steel. The polishing roll 24 is provided in contact with the peripheral surface of the conveying roll 22 to remove the deposits adhering to the conveying roll 22. The polishing roll 24 is preferably rotated in a direction opposite to the rotation direction of the conveying roll 22 at the contact position with the conveying roll 22. Thereby, the dropping of the deposits from the conveying roll 22 can be promoted. Note that the polishing roll 24 is an example of a polishing member for polishing the conveying roll 22. As the polishing member, instead of the polishing roll 24, a flat plate or a grindstone made of steel or ceramic having the same width dimension as the conveying roll 22 may be used. When a flat plate is used as the polishing member, the mounting angle of the flat plate is preferably an acute angle smaller than 90° with respect to the roll surface of the conveying roll 22. Thereby, an increase and fluctuation in the torque load of the conveying roll can be suppressed without hindering the rotation of the conveying roll 22.

[0029] Note that if there is a peripheral speed difference between the polishing roll 24 and the conveying roll 22, it is not necessary to rotate the polishing roll 24 in the opposite direction to the conveying roll 22 at the contact position. That is, when there is a peripheral speed difference between the polishing roll 24 and the conveying roll 22, the polishing roll 24 may be rotated in the same direction as the rotation direction of the conveying roll 22 at the contact position with the conveying roll 22. The peripheral speed difference between the polishing roll 24 and the conveying roll 22 may be 1 m / min or more and 1000 m / min or less. Thereby, the deposits adhering to the surface of the conveying roll 22 can be removed by the polishing roll 24.

[0030] The polishing roll 24 preferably has a control configuration (not shown) capable of controlling the pressing force against the conveying roll 22 based on its rotational load. By having such a control configuration, excessive wear of the wire due to contact with the conveying roll 22 can be avoided, and an appropriate external force can be applied to the conveying roll 22 for removing the adhered matter. Further, when it is necessary to remove the adhered matter, the polishing roll 24 is brought into contact with the conveying roll 22, and when it is not necessary to remove the adhered matter, the pressing force of the polishing roll 24 is set to 0, that is, the polishing roll 24 may not be brought into contact with the conveying roll 22. Thereby, the wear of the wire in the brush roll can be further reduced, and the life of the brush roll can be extended.

[0031] As the polishing roll 24, it is preferable to use a roll having a roll diameter smaller than that of the conveying roll 20 and a roll diameter of 100 mm or more. Thereby, a decrease in the roll life of the first polishing roll 32 and deformation due to deflection can be suppressed. Further, as the polishing roll 24, it is preferable to use a roll having an axial length shorter than that of the conveying roll 22 in the axial direction of the conveying roll 22. By moving the polishing roll 24 having an axial length shorter than that of the conveying roll 22 in the axial direction of the conveying roll 22 to polish the conveying roll 22, the conveying roll 22 can be polished uniformly in the width direction along the crown shape of the conveying roll 22 deformed by thermal crown. Furthermore, it is more preferable that the polishing roll 24 is a barrel-shaped roll (crown roll) in which the diameter of the central portion in the axial direction 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. By using a barrel-shaped roll, one-sided contact with the conveying roll 22 is suppressed, and the conveying roll 22 can be polished uniformly in the width direction.

[0032] The recovery container 26 is a steel box for recovering the adhered matter (hereinafter referred to as "dropped matter") that drops off from the conveying roll 22. By providing the recovery container 26, the dropped matter from the conveying roll 22 can be recovered, and it can be suppressed that the dropped matter adheres to the steel plate 10 again or adheres to the continuous annealing facility 100. Note that the recovery container 36 is an example of a recovery device for recovering the dropped matter from the conveying roll 22.

[0033] Figure 3 is a side schematic view showing another configuration example of the steel plate conveying equipment according to the present embodiment. In the steel plate conveying equipment 30 shown in Figure 3, the same components as those in the steel plate conveying equipment 20 shown in Figure 2 are denoted by the same reference numerals, and the description thereof is omitted. The steel plate conveying equipment 30 shown in Figure 3 is different from the steel plate conveying equipment 20 shown in Figure 2 in that it has a brush roll as the polishing roll 32 and has a steel flat plate 34 for polishing the brush roll.

[0034] As shown in Figure 3, a brush roll having a plurality of metal wires on the roll surface may be used as the polishing roll 32 for polishing the conveying roll 22. Thereby, even if the deposits adhering to the conveying roll 22 adhere to the polishing roll 32, the adhesion force between the polishing roll and the deposits becomes low, so that the deposits can be easily removed from the polishing roll 32. Further, by providing the flat plate 34 for polishing the polishing roll 32, the deposits can be easily removed from the polishing roll 32.

[0035] Figure 4 is a side schematic view showing another configuration example of the steel plate conveying equipment according to the present embodiment. In the steel plate conveying equipment 40 shown in Figure 4, the same components as those in the steel plate conveying equipment 20 shown in Figure 2 are denoted by the same reference numerals, and the description thereof is omitted. The steel plate conveying equipment 40 shown in Figure 4 is different from the steel plate conveying equipment 20 shown in Figure 2 in that the conveying roll 22 is provided on the hearth side and has a dust collecting device 42 and does not have the recovery container 26.

[0036] Since the self-weight of the steel plate 10 does not act on the conveying roll 22 on the hearth side, the surface pressure by the steel plate 10 becomes small. For this reason, the growth of the deposits adhering to the conveying roll 22 is less than that in the configuration shown in Figure 2. However, even in the configuration shown in Figure 4, deposits adhere to the conveying roll, and since the deposits grow starting from the deposits, by using the steel plate conveying equipment 40 according to the present embodiment, the deposits adhering to the roll surface can be easily removed, and as a result, the growth of the deposits on the surface of the conveying roll 22 can be suppressed.

[0037] In the configuration shown in FIG. 4, unlike the configuration shown in FIG. 2, there is no space to collect the dropped objects that have fallen due to gravity. Therefore, it is preferable to provide a dust collector 42 instead of the collection container 26. By providing the dust collector 42 in this way, it is possible to suppress the reattachment of the dropped objects from the conveying roll 22 to the steel sheet 10 or the conveying roll 22. Note that the dust collector 42 is another example of a recovery device that recovers the dropped objects from the conveying roll 22.

[0038] As described above, by using the steel sheet conveying equipment according to the present embodiment, the deposits adhering to the surface of the conveying roll can be easily removed, thereby suppressing the growth of deposits on the surface of the conveying roll 22. Further, by suppressing the growth of deposits on the conveying roll 22 in this way, it is also possible to suppress the occurrence of pressing flaw defects on the steel sheet 10 caused by the deposits. That is, in the continuous annealing equipment 100, by conveying the steel sheet 10 with the steel sheet conveying equipment according to the present embodiment, it becomes possible to manufacture an annealed steel sheet with suppressed pressing flaw defects.

[0039] In the present embodiment, an example in which the steel sheet conveying equipment 20, 30, and 40 has a recovery device has been described, but the present invention is not limited to this. As a configuration for solving the problem of easily removing the deposits adhering to the conveying roll 22 and suppressing the growth of the deposits, the steel sheet conveying equipment 20, 30, and 40 may not have a recovery device. However, as described above, since having a recovery device suppresses the reattachment of the dropped objects from the conveying roll and the first polishing roll to the steel sheet 10 or the conveying roll 22, it is preferable that the steel sheet conveying equipment 20, 30, and 40 has a recovery device.

Example

[0040] [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 sheet containing 0.3 mass% or more of Si or Mn for 2000 tons or more, the number of deposits of 100 μm or more adhering to the conveying rolls was confirmed. In Example 1, the thickness of the continuously annealed steel sheet was in the range of 0.6 to 1.8 mm, and the sheet width was in the range of 800 to 1500 mm. The continuous annealing conditions are as follows.

[0041] Atmosphere temperature: 700 °C or higher Atmosphere gas: 5 vol% hydrogen, 95 vol% nitrogen Dew point: -35 °C

[0042] 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 sheet is the highest in the continuous annealing facility 100 was taken out, and the number of deposits adhering to the conveying roll was confirmed.

[0043] In the inventive example, a brush roll was used for the conveying roll. The diameter of the brush roll was 800 mm, the material of the wire was a Ni-Cr alloy, the diameter of the wire was 10 μm, the length to the wire tip was 15 mm, and the wire density was 3 / 5 of the ratio of the wire embedding area to the roll surface area. Further, when using a polishing member for polishing the conveying roll, a polishing roll obtained by spraying cermet on the peripheral surface of a roll made of heat-resistant cast steel was used as the polishing member. By bringing the polishing roll into contact with the brush roll at a predetermined peripheral speed difference, the deposits adhering to the brush roll were removed. The pressing force of the polishing roll against the brush roll was adjusted to 0.02 kgf / mm. Also, the removed deposits (fallen-off materials) were collected in a collection container. After continuous annealing, the brush roll was taken out, and the number of deposits of 100 μm or more on the surface of the brush roll was confirmed with a laser microscope.

[0044] On the other hand, in the comparative example, a conveying roll obtained by spraying a cermet or ceramics on the peripheral surface of a heat-resistant cast steel roll was used. The diameter of the conveying roll was 800 mm. Further, when a polishing member for polishing the conveying roll was used, a polishing roll obtained by spraying a cermet on the peripheral surface of a heat-resistant cast steel roll was used as the polishing member. The polishing roll was brought into contact with the conveying roll at the same pressing force as in the inventive example at a predetermined peripheral speed difference to remove the deposits adhering to the conveying roll. Further, the removed deposits (detached materials) were collected in a recovery container. After continuous annealing, the conveying roll was taken out, and the number of deposits of 100 μm or more on the surface of the conveying roll was confirmed with a laser microscope. The results of Example 1 are shown in Table 1 below.

[0045]

Table 1

[0046] In Table 1, the peripheral speed difference “>160 - 500” means that the peripheral speed difference varied within the range of 160 to 500 m / min. This variation in the peripheral speed difference is due to the variation in the peripheral speed of the conveying roll due to the variation in the line speed, but on average it was about 300 m / min. As shown in Table 1, in Inventive Examples 1 - 5 using a brush roll for the conveying roll, regardless of the presence or absence of a polishing member, the number of deposits of 100 μm or more adhering to the surface of the conveying roll after continuous annealing was less than that in Comparative Examples 1 - 4 using a conventional conveying roll as a comparative example. Further, by using a polishing roll as a polishing member and bringing the polishing roll into contact with the conveying roll under the condition that the peripheral speed difference is 1 m / min or more, the number of deposits adhering to the conveying roll was greatly reduced.

[0047] On the other hand, in Comparative Examples 1-4 using conventional conveying rolls, even when the polishing roll was brought into contact with the conveying roll at a peripheral speed difference of 160 m / min or more to remove the deposits, the number of deposits was larger than in any of Invention Examples 1-5. From these results, it was confirmed that by using the steel sheet conveying equipment according to the present embodiment, the deposits adhering to the surface of the conveying roll can be easily removed, and thereby the growth of deposits on the surface of the conveying roll 22 can be suppressed. Further, since the number of deposits adhering to the surface of the conveying roll can be reduced in this way, it can be seen that by conveying the steel sheet with the steel sheet conveying equipment according to the present embodiment in the continuous annealing equipment, it is possible to manufacture a high-quality annealed steel sheet with few pressing flaw defects.

[0048] [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, a small sample of a steel sheet having a Si content of 1.6 mass% and a Mn content of 0.3 mass% and a brush roll was slid in a furnace in which the furnace temperature was controlled at 800°C, and the adhesion state of the deposits adhering to the brush roll during the conveyance of the steel sheet was confirmed. The test conditions for Example 2 are as follows.

[0049] Wire material: Ni-Cr alloy Wire length: 12 mm Sliding time: 30 h Sliding speed: 300 mm / min Surface pressure between the steel sheet and the brush roll: 0.001 kg / mm 2 Wire density of the brush roll: 3 / 5 in terms of the ratio of the wire embedding area to the roll surface area

[0050] After sliding the steel sheet on 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 sliding 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 lengths 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.

[0051]

Table 2

[0052] As shown in Table 2, when the diameter of the wire of the brush roll was decreased, the wear amount of the wire became longer. In particular, when the diameter of the wire became less than 20 μm, it was confirmed that the wear amount of the wire became 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.

[0053] On the other hand, when the diameter of the wire increased, the contact area with the deposit became larger, and the adhesion force of the deposit to the brush roll surface became larger. In particular, when the diameter of the wire became larger than 500 μm, the adhesion force of the deposit adhering to the brush roll became larger, and the number of deposits of 30 μm or more adhering to the brush roll surface became 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.

[0054] [Example 3] Next, Example 3 will be described in which the length from the roll surface of the brush roll to the wire tip in the radial direction was changed under the same conditions as in Example 1, and the meandering behavior of the steel sheet was confirmed. The diameter of the brush roll is 800 mm. The wire material is a high Ni-Cr alloy, the wire diameter is 50 μm, and the length from the roll surface to the wire tip in the roll radial direction was changed to 20, 30, and 40 mm. The amount of meandering of the steel sheet was confirmed at the steering roll position that controls the meandering of the steel sheet on the soaking zone exit side.

[0055] As a result of checking the amount of waviness of the steel plate, the average amount of waviness of the steel plate when the length of the wire of the brush roll was 20 and 30 mm was 32 and 35 mm respectively, while the average amount of waviness of the steel plate when the length of the wire was 40 mm was 59 mm, and the amount of waviness of the steel plate deteriorated significantly. From this result, it was confirmed that the length of the wire of the brush roll is preferably 30 mm or less, and by this, the conveyance of the steel plate is stabilized and the waviness of the steel plate can be suppressed.

Explanation of Signs

[0056] 10 Steel plate 12 Heating zone 14 soaking zone 16 Cooling zone 18 Overaging zone 20 Steel plate conveying equipment 22 Conveying roll 24 Grinding roll 26 Recovery container 30 Steel plate conveying equipment 32 Grinding roll 34 Flat plate 40 Steel plate conveying equipment 42 Dust collector 100 Continuous annealing equipment

Claims

1. A steel plate conveying facility for conveying a steel plate in a continuous annealing facility, comprising: a conveying roll for conveying the steel plate; a polishing member for polishing the conveying roll; and having wherein the conveying roll is a brush roll having a plurality of metal wires protruding radially from the circumferential surface, the steel plate conveying facility.

2. The steel plate conveying facility according to claim 1, wherein the diameter of the wire is 20 μm or more and 500 μm or less.

3. The steel plate conveying facility according to claim 1 or claim 2, wherein the length of the wire is 1 mm or more and 30 mm or less.

4. The steel plate conveying facility according to claim 1 or claim 2, wherein the wire is made of tungsten, molybdenum, cobalt, nickel-chromium alloy or stainless steel.

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

6. The steel plate conveying facility according to claim 1 or claim 2, wherein the polishing member is a flat plate, a grinding stone or a polishing roll.

7. The steel plate conveying facility according to claim 3, wherein the polishing member is a flat plate, a grinding stone or a polishing roll.

8. The steel plate conveying facility according to claim 4, wherein the polishing member is a flat plate, a grinding stone or a polishing roll.

9. The steel plate conveying facility according to claim 1 or claim 2, further comprising a recovery device for recovering the dropped objects from the conveying roll.

10. The steel plate conveying facility according to claim 3, further comprising a recovery device for recovering the dropped objects from the conveying roll.

11. The steel plate conveying facility according to claim 4, further comprising a recovery device for recovering the dropped objects from the conveying roll.

12. The steel plate conveying facility according to claim 5, further comprising a recovery device for recovering the dropped objects from the conveying roll.

13. A method for manufacturing an annealed steel plate, comprising conveying a steel plate with the steel plate conveying facility according to claim 1 or claim 2, and annealing the steel plate with the continuous annealing facility to manufacture an annealed steel plate.

14. A method for manufacturing an annealed steel plate, comprising conveying a steel plate with the steel plate conveying facility according to claim 3, and annealing the steel plate with the continuous annealing facility to manufacture an annealed steel plate.

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