JP2005342767A - Equipment for manufacturing hot-rolled steel sheet and method for manufacturing hot-rolled steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing equipment of a hot-rolled steel sheet with which the rolling efficiency of the hot-rolled steel sheet is improved and a manufacturing method of the hot-rolled steel sheet which is high in the rolling efficiency. <P>SOLUTION: In this manufacturing equipment 100 of the hot-rolled steel sheet, the final stand 11 of a hot finishing mill train 10, a first cooling unit 20, a second cooling unit 30 and a winding device 40 are arranged in order in the conveying direction of the steel sheet and also the manufacturing equipment 100 of the hot-rolled steel sheet is provided with an uncooling area 25 between the first cooling unit 20 and the second cooling unit 30. The first cooling unit 20 is provided with nozzles 21, 21, ... which are expected to form a belt-like or an ellipse-shaped jet impacting area on the surface to be cooled of the steel sheet 1 and a damming roll 22 for damming up the cooling water jetted from the nozzles 21, 21, ... and the damming roll 22 is arranged so that the pool 23 of the cooling water is formed in a area between the final stand 11 and the damming roll 22 and also the steel sheet 1 conveyed in the first cooling unit 20 is immersed in the cooling water of the pool 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to equipment for producing a hot-rolled steel sheet with high efficiency and a method for producing the hot-rolled steel sheet.

  The hot-rolled steel sheet is usually processed into a predetermined thickness by processing a heated slab using a roughing mill and a continuous hot finish rolling mill, and subsequently cooled in a cooling stand on the runout table. It is wound up by a winding device. And in the thin plate hot rolling performed by the manufacturing equipment of the hot-rolled steel sheet having these apparatuses, the production efficiency can be improved by increasing the line speed. Increasing the performance of motors in recent years can easily increase the speed of the rolling mill itself, but increasing the steel plate conveyance speed on the run-out table shortens the cooling time of the steel plate, so cooling the steel plate There is concern about the impact.

  Although it is possible to make the runout table long enough to cool the steel plate to a predetermined temperature even at higher transfer speeds than before, a line with a sufficiently long runout table is a new facility. This is not preferable because it is expensive at both the time and the modification of existing equipment. On the other hand, since the traveling of the front end portion of the rolled steel sheet is unstable, it must be rolled at a relatively low speed until the front end portion reaches the winding device. Therefore, when the run-out table is lengthened, the time for passing the plate at a low speed is increased accordingly. As a result, there is a problem that the effect obtained by increasing the steel plate conveyance speed is reduced.

  Therefore, it is desired to increase the cooling capacity per unit length of the runout table, that is, the cooling efficiency, so that the runout table can cool the steel plate to a predetermined temperature even at a higher conveying speed than conventional. In general, cooling in the runout table is performed by laminating water from a circular tube nozzle in the upper part and by spraying from a conical spray nozzle installed between table rollers in the lower part. Therefore, in order to increase the cooling efficiency of the runout table while maintaining such an apparatus configuration, it is necessary to increase the flow rate of the cooling water ejected from the nozzle. However, in particular, an increase in the flow rate on the upper surface of the steel sheet causes an increase in the amount of stagnant water on the steel sheet, and it is difficult to obtain a collision force of running water to break the boiling film generated on the steel sheet surface. There is a problem that improvement is limited. Moreover, there is a problem that a large amount of staying water significantly impedes running of the steel sheet.

Techniques aimed at solving these problems have been disclosed so far. For example, in Patent Document 1, a winding device is disposed within 30 m from the final finish rolling mill, and a rapid cooling device of a circular tube laminar nozzle type is provided between them, thereby enabling high-speed sheet feeding and high-speed rolling. Is disclosed. Patent Document 2 discloses a technique of installing a cooling device of a method in which a cooling header is brought close to a steel plate behind the final finish rolling mill.
JP 2003-211205 A JP 2001-246410 A

However, in the technology disclosed in Patent Document 1, the cooling capacity is about 200 ° C./s for cooling a steel plate having a thickness of 2 mm (about 3000 kcal / h · m ² · ° C. when converted to a heat transfer coefficient). Therefore, when manufacturing a steel sheet having a thickness of 3 mm or more, which generally occupies most of the rolled material, there has been a problem that the rolling speed has to be reduced.

On the other hand, in order to dramatically improve the capacity of the cooling device, it is currently necessary to rely on cooling of a method in which a high-speed water stream is injected at a high density from a close distance of the steel plate, and the technology related to this method Is disclosed in Patent Document 2. However, although the cooling capacity of the cooling device exemplified in Patent Document 2 is 500 ° C./s when the plate thickness is 3 mm, this is a local capacity in the cooling header portion, and the average cooling rate in the cooling device. Is only 270 ° C./s (about 6000 kcal / h · m ² · ° C. in terms of heat transfer coefficient). However, with such a cooling capacity, it is difficult to sufficiently cool a steel plate to be passed through at a high speed. Therefore, there is a problem that it is difficult to improve the rolling efficiency with a cooling device having the capacity.

  The object of the present invention is to increase the cooling efficiency of the run-out table as much as possible and to minimize the time required for rolling. However, the cooling in the run-out table is originally performed in order to control the structure and characteristics of the steel sheet, and the current situation is that not only the cooling end point temperature but also the cooling rate in the middle is limited.

For example, rolling of a steel sheet with a manufacturing facility having a winding device arranged within 30 m from the final finish rolling mill in Patent Document 1 and a cooling device capable of rapidly cooling a 3 mm-thick steel sheet in Patent Document 2 at 300 ° C./s. Consider the case. In this case, even if the steel sheet is rolled at a speed of 1300 mpm, a steel sheet whose temperature after the continuous hot finish rolling mill (hereinafter referred to as “rolling end temperature”) is 900 ° C. up to 500 ° C. Since it can be cooled, it can be said that the cooling efficiency is sufficiently high. However, the structure of the steel sheet manufactured in this way has a problem that it is highly likely that it will be necessary to redesign the material because the grain size and fraction of the ferrite phase are significantly different from those of the steel sheet produced by the conventional manufacturing method. is there.
Here, it is known that the higher the cooling rate, the worse the controllability of the steel sheet temperature, and it becomes extremely difficult to control the temperature of the steel sheet particularly in the transition boiling region of 400 to 500 ° C. Therefore, in order to obtain a steel sheet having a structure equivalent to that of a steel sheet produced by a conventional manufacturing method, it is considered necessary to make the cooling rate particularly in the low temperature region comparable to that of the conventional manufacturing method.

  On the other hand, installing a cooling system that jets jet water from a short distance of the steel plate over a wide area of the run-out table increases the equipment cost, especially when remodeling the water cooling system in existing equipment. There is also a problem of becoming.

  Then, this invention provides the manufacturing method of the hot-rolled steel plate which can improve the rolling efficiency of a hot-rolled steel plate, and the manufacturing method of a hot-rolled steel plate with high rolling efficiency in order to solve the said conventional problem. This is the issue.

The inventors conducted research on rapid cooling and obtained the following findings.
(1) By cooling the flow rate density of the cooling water by increasing the nozzle interval in the longitudinal direction of the steel plate, cooling at 20000 kcal / h · m ² · ° C. is possible in terms of the heat transfer coefficient. This corresponds to the ability to cool a steel plate having a thickness of 3 mm at about 900 ° C./s. For example, when cooling is performed to reduce the average temperature of the steel sheet whose average temperature in the sheet thickness direction is 850 ° C. to 650 ° C., the surface temperature of the steel sheet instantaneously decreases to 500 ° C. or less. Then, the steel plate is soaked in about 0.1 s.
(2) When the flow rate density of the cooling water is increased, the amount of staying water on the upper surface of the steel sheet becomes large, so that it is not possible to cope with conventional counterspray draining. On the other hand, when this stagnant water is completely dammed, the water level may reach 300 mm or more.
(3) The cooling water is dammed with a large-diameter weir roll of 400 mm or more, and the steel plate to be conveyed is immersed in a pool of accumulated water formed between the dam roll and the roll of the final stand. However, if the method of cooling the steel sheet with high-pressure jet water that can penetrate the stagnant water is adopted, even if the stagnant water level is 300 mm or more, it is possible to realize a capacity substantially equal to the cooling capacity described in (1).
(4) Cooling that lowers the temperature by 200 ° C. (hereinafter referred to as “assumed cooling”) for a 3 mm-thick steel sheet having a rolling end temperature of about 850 to 900 ° C. is 900 ° C./s. If performed at a speed, the assumed cooling is completed in about 0.2 s. Therefore, for example, when the rolling speed is 1500 mpm, the cooling section necessary for the assumed cooling is about 5 m. However, since the cooling device is usually provided with a member for supporting the steel plate passing through the device and a mechanical device for raising and lowering the cooling device itself, the assumed cooling is completely performed by a cooling device having a total length of 5 m. It is difficult to implement. In addition to the above devices (mechanical devices, etc.), in addition to the above devices (mechanical devices, etc.), it is necessary to have a capacity with a slight margin for the thickness and rolling speed of the steel plate to be cooled. The length of the cooling device actually required for performing is about 6 to 7 m.
(5) When the average heat transfer coefficient of the cooling zone is 12000 kcal / h · m ² · ° C., the length of the cooling zone required for performing the above assumed cooling on the steel sheet rolled at 1500 mpm is , About 8 m.
(6) According to the investigation of the effect of the cooling rate in various temperature ranges on the structure of the steel material, in a general low carbon steel, if it is in the temperature range of 700 ° C. or higher, the ferrite phase is slightly increased even if the cooling rate is increased. The particle size of the material is such that the structure and properties are not significantly changed. However, when the steel material was rapidly cooled to around 600 ° C., the formation of a bainite phase became prominent. Accordingly, the rapid cooling is performed at an average temperature of up to 700 ° C., preferably up to 750 ° C., and when the steel sheet is further cooled, soaking of the surface layer portion is prevented before the secondary cooling after the rapid cooling in order to prevent the structural change of the surface layer. It is necessary to secure the conversion time. The time required for soaking (about 0.1 s) can be ensured by providing a 2 m non-water-cooled section in the steel sheet manufacturing facility.

  The present invention has been completed based on the above findings, and the gist thereof is as follows.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The invention according to claim 1 includes a final stand (11), a first cooling device (20), a second cooling device (30), a winding device (10) in the hot rolling finish rolling mill row (10). 40) are sequentially arranged in the steel sheet conveying direction, and a non-cooled region (25) is provided between the first cooling device (20) and the second cooling device (30). The first cooling device (20) is a nozzle (21, 21,...) That should form a belt-like or oval jet collision area on the surface to be cooled of the steel plate (1). And a damming roll (22) for damming the cooling water sprayed from the nozzles (21, 21,...), In a region between the roll of the final stand (11) and the damming roll (22). A pool of cooling water (23) is formed and transported through the first cooling device (20). That such steel plate (1) is immersed in the cooling water pool (23), characterized in that the blocking roll (22) is disposed, is the production facility of hot rolled steel sheet (100).

  According to the invention described in claim 1, a pool (23) is formed between the roll of the final stand (11) and the weir roll (22), and the steel plate (1) is placed in the cooling water of the pool (23). Is cooled by cooling water sprayed from the nozzles (21, 21,...), So that rapid cooling is possible and the length of the cooling device can be shortened. Moreover, the manufacturing apparatus (100) of a hot-rolled steel plate can be provided.

  Invention of Claim 2 is the manufacturing equipment (100) of the hot-rolled steel sheet of Claim 1, Comprising: A nozzle (21, 21, ...) has all the points of the width direction of a steel plate (1). It is arrange | positioned so that it may pass through a jet collision area 2 times or more.

According to invention of Claim 2, a nozzle (21, 21, ...) is arrange | positioned so that all the points of the width direction of the steel plate (1) conveyed may pass a jet collision area 2 times or more. Therefore, it is possible to provide a hot-rolled steel sheet manufacturing facility (100) capable of rapid cooling of 12000 kcal / h · m ² · ° C. or higher in terms of an average heat transfer coefficient.

  Invention of Claim 3 is a manufacturing apparatus (100) of the hot-rolled steel sheet of Claim 1 or 2, Comprising: A dam roll (22) is provided in the area | region within 8 m from the last stand (11). At the same time, the diameter of the weir roll (22) is 400 mm or more.

  According to the invention described in claim 3, since the large diameter roll having a diameter of 400 mm or more is used as the weir roll (22), the flow rate density of the cooling water injected from the nozzle (21, 21,...) Is increased. Even if it is a case, the manufacturing apparatus (100) of a hot-rolled steel plate which can suppress the outflow of the cooling water to the downstream of the steel plate conveyance direction can be provided.

Invention of Claim 4 is a manufacturing apparatus (100) of the hot-rolled steel sheet of any one of Claims 1-3, Comprising: The cooling capacity of a 1st cooling device (20) is an average heat | fever. It is characterized by being 12000 kcal / h · m ² · ° C. or higher in terms of transmission coefficient.

  According to the invention described in claim 4, hot rolling is provided with the first cooling device (20) whose device length is shortened to the maximum by optimizing the cooling capacity of the first cooling device (20). A steel plate manufacturing facility (100) can be provided.

  Invention of Claim 5 is a manufacturing apparatus (100) of the hot-rolled steel sheet of any one of Claims 1-4, Comprising: A nozzle (21, 21, ...) is a pool (23). It is provided so that it may be immersed in cooling water.

  According to the invention described in claim 5, since the nozzles (21, 21,...) Are arranged so as to be immersed in the cooling water of the pool (23), it is possible to perform rapid cooling more effectively. A hot-rolled steel sheet manufacturing facility (100) can be provided.

  Invention of Claim 6 is the last stand (11) in a hot-rolling finish rolling mill row | line | column (10) using the manufacturing equipment (100) of the hot-rolled steel sheet of any one of Claims 1-5. It is a manufacturing method of a hot-rolled steel sheet characterized by including the process of processing the rolled steel plate.

  According to invention of Claim 6, the manufacturing method of the hot-rolled steel plate which can improve rolling efficiency can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing equipment of the hot-rolled steel plate which can improve the rolling efficiency of a hot-rolled steel plate, and the manufacturing method of a hot-rolled steel plate with high rolling efficiency can be provided.

Embodiments of the present invention will be described below.
FIG. 1 shows a first embodiment of the hot-rolled steel sheet manufacturing facility of the present invention, and FIG. 2 shows an enlarged view of the first cooling device in the hot-rolled steel sheet manufacturing facility of the present invention. With reference to FIGS. 1 and 2, the hot-rolled steel sheet manufacturing equipment of the present invention will be described.

  The hot-rolled steel sheet manufacturing facility 100 of the present invention includes a hot-rolling finish rolling mill row 10, a first cooling device 20, a second cooling device 30, and a winding device 40, and the first cooling device 20 Between the 2nd cooling device 30, the non-cooling area | region 25 where the measuring instrument 5 is arrange | positioned is provided. In FIG. 1, the steel plate 1 is transported from the left to the right in the drawing, and the steel plate 1 that has passed through the final stand 11 in the hot rolling finish rolling mill row 10 includes a first cooling device 20, a non-cooling region 25, And after passing the 2nd cooling device 30, it is wound up by the winding device 40. FIG.

  As shown in FIG. 2, the first cooling device 20 includes nozzles 21, 21,... That should inject cooling water onto the surface to be cooled of the steel plate 1, and cooling water injected from the nozzles 21, 21,. A dam roll 22 to be dammed is provided. Are arranged on the upper surface side and the lower surface side of the steel plate 1, respectively, and the cooling water sprayed from the nozzles 21, 21,. A cooling water pool 23 is formed by damming a region surrounded by a stop roll 22 and a side guide (not shown). Then, in the first cooling device 20, the steel plate 1 is passed through so as to be immersed in the pool 23.

In FIG. 2, the weir roll 22 is disposed at a position 8 m from the final stand 11. When the steel plate 1 is 3 mm thick and the rolling speed of the steel plate 1 in the rolling mill row 10 is 1500 mpm, the section sandwiched between the roll 22 and the final stand 11 (hereinafter referred to as “first section”). In order to lower the temperature of the steel plate 1 by 200 ° C. or more, the average heat transfer coefficient in the section is required to be 12000 kcal / h · m ² · ° C. or more. On the other hand, in order to obtain the same temperature drop when the first section is 6 m, the average heat transfer coefficient in the section is required to be 17000 kcal / h · m ² · ° C. or more. Therefore, in the present invention, when the length of the first section is 8 m or less, the flow rate of the cooling water injected from the nozzles 21, 21,... Is adjusted, and the pool 23 is formed. By providing the weir roll 22, it is preferable that the apparatus 20 has a cooling capacity of at least 12000 kcal / h · m ² · ° C. or more in terms of an average heat transfer coefficient.

  On the other hand, in the present invention, if the cooling water sprayed from the nozzles 21, 21,... Stays in a limited range on the steel plate in the first section, the water level of the cooling water pool 23 may reach 300 mm. . Therefore, from the viewpoint of effectively damping the cooling water in the pool 23 by the damming roll 22, the diameter of the roll 22 is preferably 400 mm or more.

  On the other hand, in the first cooling device 20, the weir roll 22 is preferably in close contact with the steel plate 1, but from the viewpoint of considering the consumption of the roll 22, the influence of the roll 22 on the surface of the steel plate 1, etc. A very small gap (for example, a gap of about 0.5 mm) may exist between the steel plate 22 and the steel plate 1. In addition, depending on the distribution of the plate thickness in the width direction of the steel plate, it is unavoidable that the roll 22 and the steel plate 1 are not in contact with each other locally. A sufficient damming effect can be obtained by the damming roll 22. Since there is a non-contact part, the auxiliary water draining may be performed by counter spraying or the like on the cooling water leaking from the pool 23 to the downstream side in the steel plate conveyance direction. On the other hand, when the roll 22 and the steel plate 1 are brought into close contact with each other, the roll 22 is pressed against the steel plate 1 with a predetermined pressing force, and a driving torque is applied so that the roll 22 also serves as a pinch roll.

  In the present invention, the distance between the nozzles 21, 21,... Arranged on the upper side of the steel plate 1 in the first cooling device 20 and the steel plate 1 is better from the viewpoint of increasing the cooling capacity of the device 20. From the viewpoint of improving the plate-passability of the front end portion of the steel plate 1, the larger the better. Therefore, in consideration of these two viewpoints, the interval in the present invention is preferably set to 200 mm to 500 mm. By setting the interval within such a range, it may be assumed that the nozzles 21, 21,... When the injection holes of the nozzles 21, 21,... Are submerged, the water level of the accumulated water does not fluctuate even if the cooling water is injected from the nozzles 21, 21,. As a result, the cooling water can be effectively injected onto the surface of the steel sheet, so that more accurate and stable cooling can be performed. Therefore, in the present invention, the nozzles 21, 21,... Arranged on the upper side of the steel plate 1 are in a range of 200 mm to 500 mm from the steel plate 1 and the injection holes are submerged in the retained water. Preferably they are arranged. On the other hand, the nozzles 21, 21,... Arranged on the lower side of the steel plate 1 are installed below the platen aprons 8, 8, and the cooling water is supplied to the steel plate 1 through holes formed in the aprons 8, 8. It is preferable to adopt a spraying form.

  FIG. 3 shows a schematic diagram of a jet collision area on the steel plate surface in the first cooling device 20, and FIG. 4 shows a schematic diagram of an injection state of cooling water injected from the nozzles 21, 21,. In FIG. 3, white circles represent positions immediately below (or just above) the nozzles 21, 21,..., And thick lines represent water jet collision areas ejected from the nozzles 21, 21,.

  As shown in FIGS. 3 and 4, the first cooling device 10 according to the present invention includes a plurality of nozzles 21, 21 that form a belt-like or oval jet collision area on the surface of the steel plate 1 that is a surface to be cooled. The nozzles 21, 21,... Are arranged such that adjacent jets do not interfere with each other by tilting the jet collision area at a predetermined angle with respect to the width direction of the steel sheet, and the collision areas are densely packed. Has been placed.

In the hot-rolled steel sheet manufacturing equipment 100 of the present invention, when the steel sheet 1 is cooled by the first cooling device 20, all the positions in the width direction on the surface of the steel sheet 1 are at least twice part of the jet collision area. It is preferable that the nozzles 21, 21,. By arranging the nozzles 21, 21,... In this way, it becomes possible to inject cooling water having a large flow density of 20 m ³ / m ² · min onto one side of the steel plate.

  Further, the nozzles 21, 21,... Provided in the first cooling device 20 are nozzles 21, 21,... Arranged on the upper surface side of the steel plate 1 together with a method of jetting jet water from a short distance of the steel plate 1. It is preferable that the nozzles 21, 21,... Arranged on the lower surface side have substantially the same cooling capacity. By doing in this way, it can be set as the 1st cooling device 20 which can suppress the temperature nonuniformity in a steel plate. In addition, it is preferable that the first cooling device 20 includes means for adjusting the cooling capacity. By providing such means, it is possible to provide a cooling device 20 that can cope with steel plates having various plate thicknesses and rolling speeds. Note that the means is not particularly limited. For example, means for enabling jet water injection to enter and exit for each predetermined nozzle group, and means for adjusting the flow rate of cooling water injected from the nozzles. Etc.

  In FIG. 5, the example of arrangement | positioning of the cooling device in the rolling equipment of the conventional hot-rolled steel plate is shown. The conventional rolling equipment includes a hot rolling finish rolling mill 2, a measuring instrument 5, a cooling device 3, and a winding device 4. Generally, in the conventional rolling equipment, the distance from the final stand of the finish rolling mill 2 to the cooling device 3 is about 10 m, and various measuring instruments 5 are arranged therebetween. Therefore, if the measuring instruments 5 are closely arranged, it is sufficient to install a cooling device for rapid cooling in the 10 m section and provide a non-cooling section of 2 m or more in the conventional rolling equipment. Is possible. In this case, the measuring instruments 5 may be arranged in the non-cooling section. Therefore, with this arrangement, the existing cooling device 3 can be changed to the production facility of the present invention without changing the cooling device 3 at all, so that it is possible to reduce the remodeling cost when remodeling the existing rolling facility. .

  Returning to FIG. 1 again, the description will be continued. In the manufacturing equipment 100 of the present invention, a non-water cooling section 25 having a length of 2 m or more is provided on the exit side of the weir roll 22 in the first cooling device 20. By providing such a non-water cooling section 25, it is possible to secure 0.1 s, which is the time required for soaking the hot rolled steel sheet. In the facility 100 of the present invention, various measuring devices 5 such as a thermometer, a plate thickness meter, and a plate width meter can be installed in the non-water cooling section 25.

Further, as described above, in the manufacturing facility 100 of the present invention, the length of the first section in the first cooling device 20 is short. Therefore, for example, even when feedback control of the plate thickness using a thickness meter is performed, the delay time due to the arrangement of the cooling device 20 between the finish rolling mill row 10 and the equipment 5 hardly causes a problem. Therefore, the facility 100 of the present invention can perform the same control as that of a conventional rolling facility that does not include the first cooling device 20 (hereinafter referred to as “conventional facility”).
On the other hand, in a conventional facility, a radiation thermometer arranged immediately after the final stand in the finishing rolling mill row usually has a steel plate temperature before rolling and before cooling (hereinafter referred to as “temperature before cooling”). Used as a means of confirmation. On the other hand, since the radiation thermometer is arranged after the first cooling device 20 in the facility 100 of the present invention, the radiation thermometer is used for measuring the steel plate temperature after the primary cooling in the facility 100 of the present invention. Is done. Therefore, in the facility 100 of the present invention, a new thermometer is installed immediately before the final stand 11 in the rolling mill row 10, and the measured value by this thermometer and the measured value by the radiation thermometer arranged after the apparatus 20 are set. The pre-cooling temperature is estimated by means such as estimation based on the original.

  In the manufacturing facility 100 of the present invention, the second cooling device 30 can be a cooling device having a flow rate density comparable to that of the cooling device in the conventional facility, and the form thereof is above and below the steel sheet conveying line. The form etc. which have arrange | positioned the several nozzle to the side can be mentioned. In addition, this cooling device 30 is not limited to the form in which the nozzles are continuously arranged, and may be in the form of being divided in the longitudinal direction of the steel plate (steel plate conveying direction) and having a non-water cooling section therebetween. good. However, from the viewpoint of carrying out highly efficient rolling, it is preferable that the cooling device has a sufficient cooling capacity with a length as short as possible.

  In addition, in the facility 100 of the present invention, since a large cooling capacity is added to the first cooling device 20, it is possible to improve the rolling efficiency by increasing the rolling speed as compared with the conventional facility. Further, the efficiency of the rolling can be improved by increasing the cooling capacity of the second cooling device 30 to shorten the length of the device 30 and shortening the distance from the rolling mill 10 to the winding device 40. Can be planned. Here, in general, the rolling speed must be limited to a relatively low speed called a sheet passing speed until the tip of the steel sheet is wound around the winding device. Also, after the tail end of the steel plate has passed through the rolling mill, the same speed must be constrained, and the time required for this low-speed rolling depends on the distance between the rolling stand and the winding device, but the total rolling time is It may be 20%. Therefore, shortening the distance from the rolling mill 10 to the winding device 40 leads to an improvement in rolling efficiency.

  In the equipment 100 of the present invention, the length required for the second cooling device 30 includes the cooling capacity of the device 30, the maximum rolling speed, the steel plate temperature on the outlet side of the first cooling device 20, and the steel plate. 1 can be determined from the winding temperature at the time when 1 is wound by the winding device 40. For example, the cooling capacity of the second cooling device 30 is 80 ° C./s for a steel plate having a thickness of 3 mm, the rolling speed is 1500 mpm, the steel plate temperature on the outlet side of the device 20 is 750 ° C., and the winding temperature is 600. When it is ° C., the device length required for the second cooling device is 46 m.

  In the facility 100 of the present invention, there is no problem even if a winding device called a proximity coiler (hereinafter simply referred to as “proximity coiler”) located in the middle of the runout table is used. The proximity coiler and the winding device 40 may be used properly. In addition, by providing a third cooling device between the proximity coiler and the winding device 40, cooling of a material that requires a larger cooling capacity as a whole, or air cooling for several seconds or more during the cooling is required. It can also be set as the manufacturing equipment of a hot-rolled steel plate which can be properly used for the secondary cooling etc. of such a special material. In addition, the manufacturing equipment 100 of the present invention uses the first cooling device 20 to rapidly cool the material to 700 ° C. or less by using a material having a sufficient thickness or rolling speed with respect to the capacity of the first cooling device 20. However, it can also be used for the purpose of generating a special tissue in the material.

(Example 1)
The rolling (Example 1) by the manufacturing equipment of the present invention provided with the apparatus shown in FIG. 1 and the rolling (comparative example 1) by the conventional manufacturing equipment shown in FIG. 5 were carried out, and the rolling efficiencies of the two were compared. In FIG.1 and FIG.5, the steel plate is conveyed from the left of the figure to the right direction. In the following description, the left side and the right side in these drawings are described as the upstream side and the downstream side, respectively.

Test conditions in Example 1 and Comparative Example 1 will be described.
In the manufacturing facility according to this example, the weir roll 22 having a diameter of 800 mm was installed at a position 6 m downstream of the final stand 11, and the first cooling device 20 was installed between the roll 22 and the stand 11. . In the present embodiment, the first cooling device 20 includes a roll 22 and a plurality of nozzles arranged on the upper side and the lower side of the steel plate conveyance line, and the length of the device is 6 m. On the other hand, a second cooling device 30 having a length of 80 m is disposed downstream of the first cooling device 20, and a length of 2 m is provided between the first cooling device 20 and the second cooling device 30. The non-water cooling section 25 was provided. In the manufacturing facility according to this example, the distance from the final stand 11 to the winding device 40 was 100 m.

In the present embodiment, the nozzle of the first cooling device 20 is a flat type spray nozzle capable of forming a fan-shaped cooling water jet on both the upper and lower sides of the steel plate conveyance line, and has an average flow density of 20 m at a water pressure of 1.5 MPa. ^The aperture was selected to be ³ / m ² · min. Further, in this embodiment, as shown in FIG. 3, the nozzles are arranged so that one nozzle row can pass a part of the jet collision area at least twice over all positions in the width direction on the steel plate surface. That is, the nozzle pitch Pw = 0.04 m, the cooling water jet collision width L = 0.1 m, and the torsion angle β = 36.9 °,
L = 2Pw / cosβ
The relationship was established. Furthermore, in order to further improve the uniformity of the cooling water in the width direction of the steel plate, the nozzles were twisted in directions opposite to each other between adjacent nozzle rows as viewed in the transport direction.
In the present embodiment, the nozzle is connected to a steel pipe header extending in the plate width direction of the steel plate in the apparatus 20, and the apparatus 20 is adjusted while adjusting the cooling capacity by turning water on and off in units of the header. Was used.

Further, in the present embodiment, the second cooling device 30 is the same as the cooling device used in the conventional manufacturing equipment in which the pipe lamina type nozzle is disposed on the upper side of the steel plate conveyance line and the conical spray nozzle is disposed on the lower side. The cooling efficiency was 2400 kcal / h · m ² · ° C.

  On the other hand, as shown in FIG. 5, the manufacturing facility according to this comparative example is configured by removing the first cooling device from the manufacturing facility according to the present embodiment, and the cooling device includes the second cooling in the present embodiment. The cooling device 3 which is an apparatus equivalent to the apparatus 30 was used.

  In Example 1 and Comparative Example 1, a low-carbon steel material having a sheet thickness after rolling of 3 mm and a length of 1100 m was used. Moreover, the steel plate temperature after the rolling by the hot rolling finish rolling mill and the steel plate temperature at the time of winding by the winding device were set to 900 ° C. and 400 ° C., respectively. Furthermore, the sheet feeding speed from the end of the steel plate after passing through the final stand until it is taken up by the take-up device and from the time when the tail end of the steel plate passes through the final stand until taken up by the take-up device is 650 mpm. It was. In addition, the acceleration rate and the deceleration rate between the sheet feeding speed and the maximum rolling speed were 20 mpm / s and 40 mpm / s, respectively.

  Under the above conditions, in Example 1 and Comparative Example 1, the required rolling time was measured when the rolling speed was accelerated to the maximum cooling speed, and the results were compared. Table 1 shows the average heat transfer coefficient of each controlled cooling device, the section length of each cooling device, the maximum rolling speed, and the required rolling time in Example 1 and Comparative Example 1. Moreover, the temperature pattern calculation value in each of the maximum speed rolling of Example 1 and Comparative Example 1 is shown in FIG.

表１より、第１の冷却装置を設けることで、所要圧延時間が８８ｓから７７ｓへと１２．５％短縮した。したがって、実施例１および比較例１により、本発明の熱延鋼板の製造設備は、熱延鋼板の圧延能率を向上させることができる一方で、本発明の熱延鋼板の製造設備を用いることで、圧延能率の高い熱延鋼板の製造方法を提供できることが確認された。

From Table 1, by providing the first cooling device, the required rolling time was reduced by 12.5% from 88 s to 77 s. Therefore, according to Example 1 and Comparative Example 1, the hot-rolled steel sheet manufacturing facility of the present invention can improve the rolling efficiency of the hot-rolled steel plate, while using the hot-rolled steel sheet manufacturing facility of the present invention. It was confirmed that a method for producing a hot-rolled steel sheet with high rolling efficiency can be provided.

(Example 2)
The condition of Example 2 is that the length of the second cooling device 30 is 40 m, the distance from the final stand 11 to the winding device 40 is 60 m, the steel plate temperature when being wound by the winding device is 550 ° C., and The conditions were the same as in Example 1 except that the maximum rolling speed was 1400 mpm. On the other hand, the conditions of Comparative Example 2 were set to the same conditions as Comparative Example 1 except that the steel sheet temperature when being wound by the winding device was 550 ° C. and the maximum rolling speed was 1400 mpm.

  Under the above conditions, in Example 2 and Comparative Example 2, the required rolling time was measured when the rolling speed was accelerated to the maximum cooling speed, and the results were compared. Table 2 shows the average heat transfer coefficient of each controlled cooling device, the section length of each cooling device, the maximum rolling speed, and the required rolling time in Example 2 and Comparative Example 2. Moreover, the temperature pattern calculation value in each of the maximum speed rolling of Example 2 and Comparative Example 2 is shown in FIG.

表２より、第１の冷却装置を設けることで、所要圧延時間が７６ｓから７０ｓへと約７．９％短縮した。したがって、実施例２および比較例２によっても、本発明の設備が熱延鋼板の圧延能率を向上させることができ、かつ、本発明の設備を用いることで、圧延能率の高い熱延鋼板の製造方法を提供できることが確認された。

From Table 2, by providing the first cooling device, the required rolling time was reduced from 76 s to 70 s by about 7.9%. Therefore, also in Example 2 and Comparative Example 2, the facility of the present invention can improve the rolling efficiency of the hot-rolled steel sheet, and the production of the hot-rolled steel sheet having a high rolling efficiency by using the facility of the present invention. It was confirmed that a method could be provided.

It is a figure which shows roughly the manufacturing equipment of the hot rolled sheet steel concerning 1st embodiment of this invention. It is a figure which expands and shows the 1st cooling device in the manufacture equipment of the hot-rolled steel plate of the present invention roughly. It is a schematic diagram of the jet collision area on the steel plate surface in a 1st cooling device. It is a schematic diagram of the injection condition of the cooling water injected from a nozzle. It is a figure which shows roughly the example of arrangement | positioning of the cooling device in the rolling equipment of the conventional hot-rolled steel plate. It is a figure which shows the calculated value of the temperature pattern in the maximum speed rolling. It is a figure which shows the calculated value of the temperature pattern in the maximum speed rolling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 10 Hot rolling finishing rolling mill row 11 Final stand 20 1st cooling device 21 Nozzle 22 Weiring roll 23 Pool 25 Non-cooling area 30 2nd cooling device 40 Winding device 100 Manufacturing equipment of hot-rolled steel plate

Claims (6)

A final stand, a first cooling device, a second cooling device, and a winding device in the hot rolling finish rolling mill row are sequentially arranged in the steel plate conveyance direction, and the first cooling device and the first cooling device 2 is a hot-rolled steel plate manufacturing facility in which a non-cooling region is provided between the cooling devices of
The first cooling device includes a nozzle that should form a belt-like or oval jet collision area on a surface to be cooled of a steel plate, and a damming roll that should dampen the cooling water sprayed from the nozzle,
A pool of the cooling water is formed in a region between the roll of the final stand and the damming roll, and the steel plate transported in the first cooling device is immersed in the cooling water of the pool. Thus, the said dam roll is arrange | positioned, The manufacturing equipment of the hot-rolled steel plate characterized by the above-mentioned. The said nozzle is arrange | positioned so that all the points of the width direction of the said steel plate may pass the said jet collision area 2 times or more, The manufacturing equipment of the hot-rolled steel plate of Claim 1 characterized by the above-mentioned. The equipment for manufacturing a hot-rolled steel sheet according to claim 1 or 2, wherein the weir roll is provided in an area within 8 m from the final stand, and the diameter of the weir roll is 400 mm or more. The heat according to any one of claims 1 to 3, wherein the cooling capacity of the first cooling device is 12000 kcal / h · m ² · ° C or more in terms of an average heat transfer coefficient. Production equipment for rolled steel sheets. The said nozzle is provided so that it may be immersed in the cooling water of the said pool, The manufacturing equipment of the hot rolled sheet steel of any one of Claims 1-4 characterized by the above-mentioned. The manufacturing method of the hot-rolled steel sheet according to any one of claims 1 to 5 includes a step of processing the steel sheet rolled at the final stand in the hot-rolling finish rolling mill row. A method for producing rolled steel sheets.

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