Title of the invention: Coil skid and steel plate manufacturing method
Technical field
[0001]
The present invention relates to a coil skid and a method of manufacturing a steel sheet by cooling a hot-rolled coil on the coil skid.
Background technology
[0002]
In the case of high-strength steel sheets such as thin high-tensile steel sheets (especially ultra-high-tensile steel sheets such as TRIP steel), after the hot-rolled steel sheet is wound by a coiler, the hot-rolled coil is extracted from the coiler by a coil car and transported to the coil skid in the coil storage area. , naturally cooling. During the cooling in the coil car or coil storage, uneven cooling occurs due to the skid on which the hot-rolled coil is placed (hereinafter referred to as "coil skid"). This uneven cooling occurs when the cooling rate of the contact portion of the outer circumference of the coil with the skid becomes faster than other portions due to heat extraction from the skid that is in contact with the outer circumference of the coil, and the hardness of the contact portion increases. get higher As a result, temperature unevenness (hardness unevenness) occurs in the longitudinal direction of the cold-rolled original sheet (hot-rolled steel sheet) in the outer peripheral portion of the coil. Due to this hardness unevenness, gauge hunting (thickness variation) occurs in cold rolling, and countermeasures have become an urgent need from the viewpoint of equipment maintenance, operational stability, and quality.
[0003]
As a technique for preventing the occurrence of gauge hunting in such cold rolling, for example, Patent Document 1 discloses heating the contact portion of the coil car with the hot-rolled coil to locally transform the outer circumference of the hot-rolled coil into martensite. It is disclosed that the hardness variation of the hot-rolled coil is prevented by suppressing the . It is also described that the effect of preventing fluctuations in the hardness of the hot-rolled coil can be further enhanced by insulating the contact portion of the coil skid of the coil storage site with the hot-rolled coil.
[0004]
Further, for example, in Patent Document 2, when a coil box is used after winding a hot-rolled steel sheet, a hot-rolled coil is accommodated inside a holding container surrounded by a heat insulating material, and hot-rolled coils are placed on the heat insulating material. It is disclosed to provide a steel holding member for holding the coil, the holding member having a mass of 10% or less of the mass of the hot rolled coil.
prior art documents
patent literature
[0005]
Patent Document 1: JP-A-2004-001019
Patent Document 2: JP 2015-167992 A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0006]
However, in the technique of Patent Document 1, the contact portion of the coil car with the hot-rolled coil is heated, resulting in an increase in cost. In this case, martensitic transformation can be suppressed, but it is desired to further reduce the subtle difference in cooling rate. In addition, as a method of insulating the contact portion of the coil skid with the hot-rolled coil, it is disclosed to lay a heat-insulating material between the coil skid and the hot-rolled coil. may adhere to the
[0007]
In the technique of Patent Document 2, since there is only one layer of heat insulating material under the steel holding member, there is a problem that the heat insulating material is deformed due to insufficient strength of the heat insulating material. Moreover, as shown in FIGS. 1 and 2 of Patent Document 2, when the outer peripheral portion of the hot-rolled coil and the heat insulating material are in contact with each other, the heat insulating material may adhere to the coil.
[0008]
The present invention has been made in view of the above circumstances, and by preventing the uneven cooling of the outer peripheral portion of the hot-rolled coil due to the coil skid while ensuring the strength of the coil skid, the hot-rolled coil resulting from this uneven cooling is prevented. An object of the present invention is to suppress uneven hardness in the longitudinal direction.
Means to solve problems
[0009]
The present invention for solving the above problems is a coil skid on which a hot-rolled coil obtained by winding a hot-rolled steel sheet is placed, wherein a metal plate and a heat insulating material are alternately laminated in at least two layers, and the metal plate and the heat insulating material are laminated alternately. It is characterized in that the plate is in contact with the hot-rolled coil.
[0010]
According to the present invention, it is possible to prevent uneven cooling of the outer peripheral portion of the hot-rolled coil due to the coil skid while ensuring the strength of the coil skid itself (and thus the coil storage space, coil car, and coil box where the coil skid is provided). . Therefore, it is possible to suppress the hardness unevenness in the longitudinal direction of the hot-rolled coil resulting from this uneven cooling, and furthermore, in the case of cold rolling, it is possible to suppress the gauge hunting in the cold rolling of the steel sheet caused by the hardness unevenness. It becomes possible.
[0011]
The total thickness of the heat insulating material may be 100 mm or more.
[0012]
The thickness of each of the heat insulating materials may be 70 mm or less.
[0013]
According to another aspect of the present invention, after winding a hot-rolled steel sheet into a coil, the wound hot-rolled coil is transported to a coil storage place by a coil car, and the hot-rolled coil is transported in either or both of the coil car and the coil storage place. A steel sheet manufacturing method for cooling a coil is characterized in that the coil skid is provided in one or both of the coil car and the coil storage area.
[0014]
Either or both of the coil car and the coil storage place may be provided with a coil box for accommodating the hot-rolled coil therein, and the coil skid may be provided in the coil box.
[0015]
According to the present invention, it is possible to prevent uneven cooling of the outer peripheral portion of the hot-rolled coil due to the coil skid while ensuring the strength of the coil skid itself (and thus the coil storage space, coil car, and coil box where the coil skid is provided). . Therefore, it is possible to suppress the hardness unevenness in the longitudinal direction of the hot-rolled coil caused by the uneven cooling.
[0016]
A coiling temperature of the hot-rolled steel sheet may be 400°C to 750°C.
[0017]
After cooling the hot-rolled coil, it may be cold-rolled. Even in the case of cold rolling, it is possible to suppress gauge hunting in cold rolling of the steel sheet caused by the hardness unevenness.
Effect of the invention
[0018]
According to the present invention, uneven cooling of the outer peripheral portion of the hot-rolled coil due to the coil skid is prevented while securing the strength of the coil skid, thereby suppressing hardness unevenness in the longitudinal direction of the hot-rolled coil resulting from the uneven cooling. becomes possible.
Brief description of the drawing
[0019]
1 is an explanatory diagram showing an outline of the configuration of a coil skid according to an embodiment of the present invention; FIG.
2 is a graph showing an example of temperature change in the thickness direction of the heat insulating material when a steel plate at room temperature is brought into contact with the lower surface of the heat insulating material.
MODE FOR CARRYING OUT THE INVENTION
[0020]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.
[0021]
In the embodiment of the present invention, based on the above-described problems, the hardness unevenness in the longitudinal direction of the hot-rolled coil is suppressed, and when cold rolling is performed, the gauge in the cold rolling of the steel sheet caused by the hardness unevenness. In order to suppress hunting, as a means for preventing uneven cooling of the outer peripheral portion of the hot-rolled coil due to the coil skid, a coil skid in which at least two layers of metal plates and heat insulating materials are alternately laminated is adopted. . Also, the metal plate is in contact with the hot-rolled coil, that is, the surface of the coil skid on the side that contacts the hot-rolled coil is composed of the metal plate. By adopting such a coil skid, it is possible to achieve both the strength of the coil skid and the heat insulating effect for the hot-rolled coil. Hereinafter, the coil skid according to this embodiment will be described in detail.
[0022]
(coil skid)
FIG. 1 is an explanatory diagram showing the outline of the configuration of the coil skid 10 according to this embodiment. The coil skid 10 is provided for placing the hot-rolled coil 1 in, for example, a coil storage place, a coil car, a coil box, or the like.
[0023]
As shown in FIG. 1, a coil skid 10 according to the present embodiment is a coil mounting table for mounting a hot-rolled coil 1 after winding a hot-rolled steel sheet by a coiler or the like. 12 each have a structure in which at least two or more layers are alternately laminated (that is, a laminated structure of at least four layers). Here, in the present embodiment, at least two layers of the metal plate 11 and the heat insulating material 12 are alternately laminated. It is a configuration necessary to achieve both On the other hand, even if the total thickness of the metal plate 11 and the total thickness of the heat insulating material 12 are the same as when two or more layers are laminated, when the metal plate 11 and the heat insulating material 12 are laminated one by one, , the strength of the coil skid 10 is insufficient, causing inconvenience such as denting of the metal plate 11, for example.
[0024]
As the metal plate 11, for example, an iron plate (steel plate), a stainless steel plate, a copper plate, a titanium plate, an aluminum plate, etc. (preferably an iron plate (steel plate) and a stainless steel plate) can be used. In addition, as the heat insulating material 12, for example, inorganic materials such as glass wool, rock wool, and ceramic fibers, and composite plates of inorganic materials and resins (preferably iron plates (steel plates) and stainless steel plates) can be used. The material is not particularly limited as long as it has a heat insulating effect capable of suppressing heat extraction from the coil skid 10 from the rolled coil 1 . Here, the heat insulating material means a material having a thermal conductivity of 0.3 W/m/K or less at 800° C. or less.
[0025]
In addition, in this embodiment, the metal plate 11 located on the outermost layer of the coil skid 10 (that is, the side that contacts the hot-rolled coil 1 ) is in contact with the hot-rolled coil 1 . If the heat insulating material 12 is located in the outermost layer of the coil skid 10 and contacts the hot-rolled coil 1, the heat insulating material 12 may adhere to the outer peripheral portion of the hot-rolled coil 1 as described above. In addition, since a material having relatively low hardness such as glass wool is used as the heat insulating material 12, the strength thereof is insufficient, causing inconveniences such as the surface of the coil skid 10 to be dented.
[0026]
According to the coil skid 10 according to the present embodiment as described above, the strength of the coil skid 10 itself (and the coil storage place, the coil car, and the coil box where the coil skid 10 is provided) is secured, and the hot rolling by the coil skid 10 is performed. Uneven cooling of the outer peripheral portion of the coil 1 can be prevented. Therefore, the hardness unevenness in the longitudinal direction of the hot-rolled coil 1 resulting from this uneven cooling should be suppressed, and furthermore, when cold rolling is performed, the gauge hunting in the cold rolling of the steel sheet caused by the hardness unevenness should be suppressed. becomes possible.
[0027]
Here, it is preferable that the total thickness of the heat insulating material 12 is 100 mm or more. In particular, in the case of a high-strength steel sheet (high tensile strength steel) having a hot-rolled steel sheet winding temperature of 400° C. to 750° C. and a tensile strength (product strength) of 700 MPa or more, the total thickness of the heat insulating material 12 is It is preferably 100 mm or more. The reason why the total thickness of the heat insulating material 12 is preferably 100 mm or more will be described below with reference to FIG. The total thickness of the heat insulating material 12 is the sum of the average thicknesses of the heat insulating materials 12 existing in two or more layers. For example, the thickness of the heat insulating material 12 closer to the hot-rolled coil 1 shown in FIG. means distance. The average thickness means the arithmetic mean of the thicknesses of five randomly selected locations (wherein the area assumed to be in contact with the hot-rolled coil 1 is the area to be measured).
[0028]
FIG. 2 is a graph showing an example of temperature change in the thickness direction of the heat insulating material when a steel plate at room temperature is brought into contact with the lower surface of the heat insulating material.
[0029]
In order to examine the preferable range of the total thickness of the heat insulating material 12, first, as an example, the components are mass %, C: 0.2%, Si: 0.1%, Mn: 2.0%, P: 0 A slab for a 1.2 GPa grade cold-rolled steel sheet containing 0.005% S and 0.001% S was heated to 1200° C. in a heating furnace and hot-rolled to a thickness of 2.5 mm. After hot rolling, a plurality of hot-rolled coils wound at 720° C. using a coiler were prepared.
[0030]
Then, these hot-rolled coils were cooled to room temperature in a coil storage place having a normal iron coil skid, and cold-rolled to a sheet thickness of 1.19 mm. Hot-rolled steel sheet and cold-rolled steel sheet at that time Gauge hunting, which did not occur in hot rolling, occurred in cold rolling. It was confirmed that the cycle of gauge hunting that can be confirmed only in the thickness distribution in the longitudinal direction of the cold-rolled steel sheet corresponds to one turn of the hot-rolled coil. Uneven hardness occurs in the longitudinal direction of the hot-rolled coil due to uneven cooling of the outer peripheral portion of the hot-rolled coil by the coil skid, and gauge hunting occurs in the cold-rolled steel sheet due to the uneven hardness.
[0031]
Investigating the relationship between the CCT (Continuous Cooling Transformation) diagram of the hot-rolled steel sheet and the temperature change of the steel sheet due to heat extraction from the iron coil skid, it is found that the winding of the hot-rolled steel sheet into a coil After 200 seconds, the transformation rate is about 90%, indicating that the transformation is almost completed. Here, the strength (hardness) of the hot-rolled steel sheet is affected by the structure formed depending on the cooling rate. Therefore, the present inventors studied a coil skid structure that would prevent the transformation from progressing too much 200 seconds after winding.
[0032]
In this embodiment, a coil skid having a heat insulating material is used so that there is no influence of heat removal from the contact portion with the outer peripheral portion of the hot rolled coil due to the coil skid, and 200 seconds after the hot rolled steel sheet is wound into the coil. The thickness of the heat insulating material was studied so that the temperature of the outer peripheral portion of the hot-rolled coil did not change and the transformed structure was not affected over time. For this study, a temperature analysis of the heat insulating material itself was performed.
[0033]
Specifically, as a heat insulating material, glass wool with a thickness of 0.15 m heated to 720 ° C. is used, and the lower surface of this heat insulating material (the surface 0.15 m below the top surface of the heat insulating material in the thickness direction) A temperature change in the thickness direction of the heat insulating material was measured when the heat insulating material was cooled by bringing a steel plate at room temperature into contact with the heat insulating material. The results are shown in FIG. For example, the legend of "1 s" in FIG. 2 indicates the temperature change in the thickness direction of the heat insulating material after 1 second has elapsed since the steel plate was brought into contact with the heat insulating material. The same is true for others.
[0034]
As shown in Fig. 2, for example, after one second has passed since the steel plate was brought into contact with the heat insulating material, the temperature has not decreased in almost the entire thickness of the heat insulating material, and it can be seen that cooling is hardly performed. In addition, after 200 seconds had passed since the steel plate was brought into contact with the heat insulating material, the temperature hardly decreased up to the portion where the heat insulating material had a thickness of 0.05 m. As a result, when a heat insulating material having thermophysical properties equivalent to glass wool is used, if the total thickness of the heat insulating material 12 possessed by the coil skid 10 is at least 100 mm (=0.15 m-0.05 m), the coil skid 10 is contacted. It has been found that the outer peripheral portion of the hot-rolled coil 1 is hardly cooled (that is, the outer peripheral portion of the hot-rolled coil 1 can be insulated), is not affected by uneven cooling, and has no effect on the transformed structure. The fact that the transformation structure is not affected (transformation does not progress easily) is that the CCT diagram of the hot-rolled steel sheet and the investigation results of the relationship between the temperature change of the steel sheet due to the heat extraction from the iron coil skid show that 200 seconds after winding. It can also be seen from the fact that the transformation rate is less than 50% if there is little cooling afterward.
[0035]
From the above study, in the coil skid 10 according to this embodiment, it is preferable that the total thickness of the heat insulating material 12 is 100 mm or more. The upper limit of the total thickness of the heat insulating material 12 is not particularly limited, but it may be 500 mm or less from the balance between the heat insulating effect and the strength.
[0036]
In the coil skid 10, at least two layers of metal plates 11 and heat insulating materials 12 are alternately laminated. By adopting the laminated structure, the strength of the coil skid 10 is increased compared to a structure having one layer each of the metal plate 11 and the heat insulating material 12 .
[0037]
The thickness of each of the heat insulating materials 12 is preferably 70 mm or less. The strength of the coil skid 10 is further enhanced by setting the thickness of each of the heat insulating materials 12 to 70 mm or less. Although the lower limit of the thickness of each of the heat insulating materials 12 is not particularly limited, it may be 10 mm or more in consideration of the balance between the heat insulating effect and the strength. Here, the thickness of each heat insulating material 12 refers to the average thickness of each heat insulating material 12 that exists in two or more layers. The average thickness means the arithmetic mean of the thicknesses of 5 randomly selected points (where the area expected to come into contact with the hot-rolled coil 1 is the area to be measured).
[0038]
The total thickness of the metal plates 11 and the thickness of each metal plate 11 may be determined in consideration of the strength of the coil storage space required from the mass of the hot-rolled coil 1. Also, when the metal plate in contact with the surface of the hot-rolled coil is thick, the cooling effect from the metal plate increases.
[0039]
In this embodiment, the method of winding the hot-rolled coil 1 is not particularly limited, but for example, a hot-rolled steel sheet may be wound by a coiler. That is, the coil skid 10 according to the present embodiment may be operated at the same time as the coil box. A skid 10 may be provided. By operating the coil skid 10 according to the present embodiment at the same time as the coil box, the hot-rolled coil 1 is cooled while being kept warm by the coil box, so heat removal through the coil skid 10 can be further reduced. . When the coil skid 10 and the coil box are operated simultaneously, the coil skid 10 and the coil box may be provided in one or both of the coil car and the coil storage area.
[0040]
In the present embodiment, the place where the coil skid 10 is provided is not particularly limited. It can be provided in a place for placing coils, or the like. Further, for example, a coil skid 10 may be provided in a coil box (thermal insulation box) for storing the hot rolled coil 1 between the rough rolling process and the finish rolling process of the hot rolling line.
[0041]
(Manufacturing method of steel plate)
The configuration of the coil skid 10 according to the present embodiment has been described in detail above. Subsequently, the method for manufacturing the steel sheet according to the present embodiment including the step of cooling the hot-rolled coil 1 on the coil skid 10 will be described in detail. do.
[0042]
In the steel sheet manufacturing method according to the present embodiment, after the hot-rolled steel sheet is wound into a coil, the wound hot-rolled coil 1 is transported to the coil storage place by a coil car, and hot-rolled in either or both of the coil car and the coil storage place. Coil 1 is cooled. In this embodiment, the coil skid 10 described above, that is, the coil skid 10 in which at least two layers of the metal plate 11 and the heat insulating material 12 are alternately laminated is provided on either or both of the coil car and the coil storage place. ing. Also, the metal plate 11 is in contact with the hot-rolled coil 1 .
[0043]
According to the steel sheet manufacturing method using the coil skid 10 according to the present embodiment as described above, the coil skid can be Uneven cooling of the outer peripheral portion of the hot-rolled coil 1 due to 10 can be prevented. Therefore, it is possible to suppress the hardness unevenness in the longitudinal direction of the hot-rolled coil 1 resulting from the uneven cooling. Furthermore, when a steel sheet is manufactured by cold rolling using this hot-rolled coil 1, it is possible to suppress gauge hunting in the cold-rolling of the steel sheet caused by hardness unevenness occurring in the longitudinal direction of the hot-rolled coil 1. .
[0044]
In the steel sheet manufacturing method according to the present embodiment, for example, the hot-rolled coil 1 may be manufactured at a coiling temperature of 400°C to 750°C. A steel sheet having a tensile strength exceeding 700 MPa may be produced by cold-rolling the hot-rolled coil 1 after cooling. According to this embodiment, it is possible to realize a method for manufacturing a steel sheet that suppresses gauge hunting in cold rolling.
Example
[0045]
(Example 1)
In order to confirm the effect of the method for manufacturing a steel sheet using the coil skid 10 according to the embodiment of the present invention described above, the components are mass%, C: 0.2%, Si: 0.1%, Mn: 2 0%, P: 0.005%, S: 0.001%, a slab for 1.2 GPa grade cold-rolled steel sheet is heated to 1200 ° C. in a heating furnace and hot rolled to a thickness of 2.5 mm. Rolled. After hot rolling, a plurality of hot-rolled coils wound at 720° C. using a coiler were prepared.
[0046]
In addition, when the required strength of the coil storage place was examined from the mass of the hot-rolled coil, by using a coil skid in which two steel plates with a thickness of 1 mm and a heat insulating material made of glass wool with a total thickness of 100 mm were alternately laminated, It was found to be strong enough. Therefore, a coil skid having the same structure as the coil skid 10 shown in FIG. 1 was produced. That is, a 1 mm-thick stainless steel plate is laid as a metal plate on the portion that contacts the outer peripheral portion of the hot-rolled coil, a 50 mm-thick glass wool as a heat insulating material is laid therebelow, and a 1 mm-thick stainless steel plate is further disposed therebelow. A coil skid in which glass wool having a thickness of 50 mm was laminated as a lower layer was manufactured on a coil storage site.
[0047]
The hot-rolled coil prepared as described above was cooled to room temperature in the coil storage area having the coil skid, and the cooled hot-rolled steel sheet was cold-rolled to 1.19 mm to produce a high-strength steel sheet.
[0048]
(Example 2)
A high-strength steel plate was manufactured in the same manner as in Example 1, except that the thickness of each layer of glass wool as a heat insulating material was changed from 50 mm to 40 mm.
[0049]
(Comparative example 1)
The procedure was the same as in Example 1, except that a 2 mm thick stainless steel plate was laid as a metal plate on the portion in contact with the outer periphery of the hot-rolled coil, and a 100 mm thick glass wool was laminated as a heat insulating material underneath to prepare a coil skid. A high-strength steel sheet was produced by
[0050]
(Comparative example 2)
The procedure was the same as in Example 1, except that a 1 mm thick stainless steel plate was laid as a metal plate on the portion in contact with the outer periphery of the hot-rolled coil, and a 80 mm thick glass wool was laminated as a heat insulating material underneath to prepare a coil skid. A high-strength steel sheet was produced by
[0051]
(Comparative Example 3)
A coil skid was prepared by laying a stainless steel plate with a thickness of 2 mm as a metal plate on the portion in contact with the outer peripheral portion of the hot-rolled coil, and glass wool with a thickness of 100 mm was used as a heat insulating material between the outer peripheral portion of the hot-rolled coil and the metal plate. A high-strength steel sheet was produced in the same manner as in Example 1, except that it was sandwiched between.
[0052]
(Evaluation method)
For the high-strength steel sheets of Examples 1-2 and Comparative Examples 1-3 manufactured as described above, the strength of the coil skid and the heat insulating effect were evaluated.
[0053]
(1) Evaluation of coil skid strength
The strength of the coil skid was evaluated by observing the surface of the coil skid after cooling the hot-rolled coil and evaluating it as follows.
　　○: When there was no effect on the metal plate part
　　×: When deformation such as dents or cracks occurs in the metal plate part
[0054]
(2) Evaluation of heat insulation effect
For the evaluation of the heat insulation effect, the occurrence of gauge hunting in cold rolling was evaluated as follows using the hunting amount H of the cold rolled steel sheet represented by the following formula as an index.
　H = {(amplitude of hunting [mm]) / (total thickness [mm]) x 100 [%]
◎: H is less than 0.5%
○: H is 0.5% or more and less than 1%
　　×: H is 1% or more
[0055]
(Evaluation results)
Table 1 shows the results of the above evaluation. As shown in Table 1, Example 1 and Example 2, in which two layers each of the metal plate and the heat insulating material were laminated, showed good results in both the strength of the coil skid and the heat insulating effect. In particular, Example 1, in which the total thickness of the heat insulating material was 100 mm, was particularly excellent in heat insulating effect.
[0056]
On the other hand, Comparative Example 1 and Comparative In Comparative Example 2, the strength of the coil skid was inferior. In particular, in Comparative Example 2, in which the total thickness of the metal plates was only 1 mm and the total thickness of the heat insulating material was less than 100 mm, both the strength and the heat insulating effect were inferior. In addition, in Comparative Example 3, in which the heat insulating material was interposed between the hot-rolled coil and the metal plate instead of providing the heat insulating material in the coil skid, the heat insulating material was crushed and the heat insulating effect was inferior. became. Furthermore, in Comparative Example 3, the heat insulating material was in contact with the hot-rolled coil, and adhesion of the heat insulating material was observed on the surface of the hot-rolled coil after cooling.
[0057]
[table 1]

Industrial applicability
[0058]
The present invention is useful for a coil skid and a steel sheet manufacturing method for cooling a hot-rolled coil on the coil skid.
Code explanation
[0059]
1 Hot-rolled coil
10 coil skid
11 Metal plate
12 Thermal insulation
The scope of the claims
[Claim 1]
A coil skid on which a hot-rolled coil wound from a hot-rolled steel sheet is placed,
At least two layers of the metal plate and the heat insulating material are alternately laminated,
A coil skid, wherein the metal plate is in contact with the hot-rolled coil.
[Claim 2]
2. The coil skid according to claim 1, wherein the total thickness of said heat insulating material is 100 mm or more.
[Claim 3]
3. The coil skid according to claim 1, wherein each thickness of said heat insulating material is 70 mm or less.
[Claim 4]
A method for manufacturing a steel sheet, comprising winding a hot-rolled steel sheet into a coil, transporting the wound hot-rolled coil to a coil storage place by a coil car, and cooling the hot-rolled coil in either or both of the coil car and the coil storage place. and
A steel sheet manufacturing method, wherein the coil skid according to any one of claims 1 to 3 is provided on one or both of the coil car and the coil storage place.
[Claim 5]
A coil box for accommodating the hot-rolled coil is provided in one or both of the coil car and the coil storage place, and the coil according to any one of claims 1 to 3 is provided in the coil box. 5. The method of manufacturing a steel sheet according to claim 4, wherein a skid is provided.
[Claim 6]
The method for producing a steel sheet according to claim 4 or 5, wherein the coiling temperature of the hot-rolled steel sheet is 400°C to 750°C.
[Claim 7]
The steel sheet manufacturing method according to any one of claims 4 to 6, wherein the hot-rolled coil is cooled and then cold-rolled.