JP4848984B2 - Manufacturing method and manufacturing apparatus for hot-rolled steel sheet - Google Patents

Description

  The present invention relates to a method and an apparatus for manufacturing a hot-rolled steel sheet, and more particularly to a method and an apparatus for manufacturing a hot-rolled steel sheet that can improve cooling capacity while appropriately performing various measurements between stands of a finish rolling mill.

  In a hot-rolled steel sheet, after heating a slab in a heating furnace or immediately after casting, a high-temperature slab is directly rolled with a roughing mill to obtain a rough rolled material. Thereafter, the rough rolled material is transported from the rough rolling mill to a finishing rolling mill by a transporting table with a predetermined transport pattern, and further rolled by the finishing rolling mill to obtain a hot rolled steel sheet having predetermined dimensions and mechanical performance. . The obtained hot-rolled steel sheet is wound up into a coil shape.

  In finish rolling, in order to shorten the manufacturing time, it is required to shorten the rolling time and perform rolling efficiently. Therefore, it is required to accelerate and decelerate in a predetermined pattern and to roll at as high a speed as possible. However, when rolling at high speed, the transport time from the finish mill entrance to the exit is shortened, so the amount of heat removed from the material surface is reduced, and the temperature of the steel sheet is higher than the target temperature at the finish mill exit. . If the temperature of the steel sheet is high, the mechanical properties necessary for the steel sheet cannot be given, which is a problem from the viewpoint of the performance of the hot-rolled steel sheet. Moreover, even if the rolling speed is maintained as it is, the temperature on the exit side of the roughing mill actually increases due to operation changes such as the heating furnace, and the steel sheet temperature on the exit side of the finish rolling mill increases accordingly. There was a case.

  On the other hand, conventionally, as disclosed in Patent Document 1, a plurality of cooling devices such as sprays are installed between the stands of the finish rolling mill so that the temperature of the steel sheet at the exit of the finishing mill becomes the target temperature. Cooling is in progress. Thereby, a hot-rolled steel sheet having predetermined dimensions and mechanical performance can be obtained.

By the way, during finish rolling, since it is necessary to suppress problems such as meandering of the steel plate during rolling and a decrease in flatness, various measuring devices for measuring the state of the steel plate are provided between the stands. Patent Documents 2 to 4 disclose a method of measuring and controlling a steel plate using a meandering meter, a flatness meter, and a plate thickness meter provided between the stands of a finish rolling mill. According to these, each measuring instrument is an optical type and a radiation type in order to obtain a more accurate value.
JP 2002-11502 A JP 2004-141956 A JP-A-63-134903 JP-A-3-71910

  However, the measuring instruments used in Patent Documents 2 to 4 cannot be measured in a water environment, or even if they are measured, the accuracy is insufficient, so that cooling water can be sprayed between stands provided with the measuring instrument. Therefore, there was a problem that cooling could not be performed. In order to solve this problem, it is conceivable to spray the cooling water at a position closer to the steel plate than the inter-stand measuring device so that water is not directly applied to the visual field range of the inter-stand measuring device. Since the momentum of water is strong and the splash of water splashing on the steel plate is applied to the visual field range of the measuring instrument, it is difficult to measure with high accuracy.

  As described above, when there is a measuring instrument between the stands due to the measurement accuracy, there is a case where the cooling ability in the finishing mill is lowered due to the inability to cool between the stands. In order to achieve more efficient production, it is necessary to increase the rolling speed, but cooling cannot be performed between stands equipped with measuring instruments, so the rolling speed is increased further to achieve the target temperature. I couldn't.

  Therefore, the present invention can cool even between stands equipped with a measuring instrument, and can also improve the measurement accuracy of the measuring instrument, thereby improving product quality and manufacturing efficiency. It aims at providing the manufacturing method of a steel plate, and its manufacturing apparatus.

  As a result of intensive studies, the inventors have obtained knowledge that the rolled material can be controlled without necessarily measuring the steel sheet with the measuring instrument in the entire range from the front end to the rear end of the steel plate. And by developing this knowledge, the cooling device between the stands where the measuring device is installed is stopped only during the control (measurement) using the measuring device, and the measuring device is used by using the cooling device at other times. Thus, the present invention has been completed, in which cooling can be performed even between stands equipped with the above. Hereinafter, the manufacturing method and manufacturing apparatus of the hot-rolled steel sheet of the present invention will be described. 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.

Invention of Claim 1 is a method (S1) which manufactures a hot-rolled steel plate using the finish rolling mill (12) which has at least 3 stand (21a-21g), Comprising: Among several stands, A step (S32) of measuring a physical quantity of the steel plate (1) with at least one measuring instrument (40) provided between at least one stand of the above, and a step of controlling the finishing mill based on the obtained physical quantity ( S34) and a step (S23) of cooling the steel sheet by a cooling device (33a to 33e) capable of emitting cooling water provided between a plurality of stands including between the stands provided with the measuring device. While the physical quantity is being measured by the cooling device, the cooling water is prohibited between the stands provided with the measuring device and the cooling device provided between the stands provided with no measuring device. Solves the problems by providing a method of manufacturing a hot rolled steel sheet characterized by controlling the conditions of the cooling water to increase the amount of cooling.
Here, “physical quantity” expresses the physical properties of the steel sheet, and is defined as a quantity in which the unit of measurement or the unit of size is defined. For example, it is an amount related to flatness, meandering amount, plate thickness, plate width, surface temperature, etc.

The invention described in claim 2 is characterized in that the measuring instrument (40) in the method (S1) for producing a hot-rolled steel sheet according to claim 1 includes a meandering meter.

The invention described in claim 3 is characterized in that the measuring instrument (40) in the method (S1) for producing a hot-rolled steel sheet according to claim 1 or 2 includes a flatness meter.

Invention of claim 4, the cooling device in the production process of hot-rolled steel sheet according to any one of claims 1~ 3 (S1) (33a~33e) are backflow prevention to prevent the backflow of the cooling water Means are provided.

Invention of Claim 5 is a manufacturing apparatus (10) of a hot-rolled steel plate provided with the finish rolling mill (12) which has a some stand (21a-21g), Comprising: Between at least 1 stand among the stands A measuring device (40) for measuring the physical quantity of the steel plate (1), a control device (51) for determining a control amount of the finishing mill based on the physical quantity measured by the measuring instrument, and a control Cooling capable of emitting cooling water provided between a plurality of stands including an operation device (52a, 52b) for controlling the finishing mill based on a control amount determined by the device and a stand provided with a measuring device. apparatus and a (33a to 33e), the cooling device (33a to 33e), provided with a backflow prevention device for preventing backflow of the cooling water, while the measurement of the physical quantity is performed by meter (40), the measuring instrument Between provided stand resolve the problem by providing an apparatus for manufacturing a hot-rolled steel sheet, characterized in that the exit of the cooling water is inhibited.

  According to the method for producing a hot-rolled steel sheet of the present invention, the steel sheet can be cooled even between the stands where the measuring devices are installed, and the cooling capacity can be improved, so that the rolling efficiency is improved, and Since the measurement accuracy in the measuring instrument is also improved, the quality of the hot-rolled steel sheet can be improved. Furthermore, it is possible to control the rolling mill based on accurate measurement, and it is possible to obtain a high-quality hot-rolled steel sheet that is closer to the target quality.

  Moreover, according to the apparatus for producing a hot-rolled steel sheet of the present invention, an apparatus that exhibits the above effects can be provided.

  Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  Here, for easy understanding, a hot-rolled steel sheet manufacturing apparatus according to one embodiment of the present invention will be described first, and then a hot-rolled steel sheet manufacturing method according to one embodiment will be described.

  FIG. 1 is a diagram schematically showing a hot-rolled steel sheet manufacturing apparatus 10 (hereinafter, sometimes referred to as “manufacturing apparatus 10”) according to one embodiment of the present invention. The manufacturing apparatus 10 includes a rough rolling mill 11 and a finish rolling mill 12. Further, the finish rolling mill 12 includes a rolling means 20, a cooling means 30, a measuring means 40, and a rolling control means 50 according to its role, and exchanges information between the means, and operates based on the information to operate the steel plate 1. Is configured to roll. This will be described in detail below.

  The rough rolling mill 11 is a facility that performs rolling so that a slab produced by casting can be provided to the finish rolling mill 12 and has a metal structure. The rough rolling mill 11 is provided with a slab as it is immediately after casting, or a slab that has been once cooled and reheated in a heating furnace or the like. The rough rolling mill 11 can apply the rough rolling mill 11 used for the rolling of a normal hot-rolled steel sheet, and may be comprised from the rolling mill group which consists of a some stand.

  The finish rolling mill 12 is a facility that is arranged on the subsequent process side of the rough rolling mill 11 and performs rolling so as to have dimensions, mechanical properties, and the like that are ultimately required for a hot-rolled steel sheet. Accordingly, the finish rolling mill 12 is provided with the steel plate 1 formed by the rough rolling mill 11. The finishing mill 12 includes the rolling means 20, the cooling means 30, the measuring means (measuring instrument) 40, and the rolling control means 50 as described above. Details are as follows.

  The rolling means 20 is a tandem rolling mill composed of seven rolling mills (also referred to as “stands”) 21a to 21g, and the steel sheet 1 is in turn from the rolling mill 21a to the direction of the rolling mill 21g (in FIG. 1). Rolled from left to right on the page. About each rolling mill 21a-21g, what is used for the finish rolling of a normal hot-rolled steel plate can be applied. In this embodiment, the rolling means 20 is formed from seven rolling mills 21a to 21g, but is not limited to this, and may be formed from at least two rolling stands, that is, at least three rolling mills. If it is, it can be set as the manufacturing apparatus 10 of the hot rolled sheet steel of this invention.

The cooling unit 30 includes a cooling control device 31, temperature measuring sensors 32a and 32b, and cooling devices 33a to 33e.
The cooling control device 31 sets the temperature on the exit side of the finish rolling mill 12 as a target based on information such as the temperature of the steel sheet 1 and the rolling speed pattern transmitted from the temperature measuring sensor 32a arranged on the entry side of the finish rolling mill 12. The cooling water supply conditions are calculated so that the temperature is reached. Here, as described later, the usable range of the cooling devices 33a to 33e is considered, and based on the calculation result, an ON / OFF command for cooling water emission or a water amount adjustment command is transmitted to the cooling devices 33a to 33e. Accordingly, the cooling control device 31 stores in advance information for controlling the cooling water, such as a change in the pump speed, a change in the opening of the flow valve, and the cooling capacity of each cooling device according to the number of cooling devices used. ing. The cooling control device 31 is configured to exchange information with the rolling control means 50. How the cooling water emission is actually controlled to achieve the target temperature control will be described in detail later. As the cooling control device 31 described above, for example, an information processing unit can be cited, which includes an input terminal for inputting temperature information and the like, a RAM for temporarily storing the information and the calculation result, as described above. There are provided a ROM in which a formula for a predetermined calculation is stored, a CPU that performs a calculation based on the acquired information and a predetermined calculation formula, and an output terminal that outputs a calculation result.

  The temperature measuring sensors 32a and 32b are thermometers. The temperature measuring sensor 32a is installed on the entry side of the finishing mill 12, and the temperature sensor 32b is installed on the exit side of the finishing mill 12. The temperature information obtained by the temperature sensors 32a and 32b is transmitted to the cooling control device 31 as a signal. Therefore, the types of the temperature sensors 32a and 32b can be used regardless of contact or non-contact, but it is necessary to be configured so that the measurement result can be transmitted as an electric signal. An example of this is a radiation thermometer. In the present embodiment, the temperature measuring sensors 32a and 32b are provided on both the entry side and the exit side of the finish rolling mill 12, but either one may be used. This also makes it possible for the cooling control device 31 to appropriately process the temperature information.

  The cooling devices 33a to 33e are cooling devices installed above and below the pass line between the stands of the rolling mills 21a to 21g, and are provided between the stands except for the stand between the rolling mill 21d and the rolling mill 21e. . Specifically, the cooling devices 33a to 33e perform cooling by emitting cooling water to the steel plate based on a command from the cooling control device 31, and control the temperature over the entire length of the hot-rolled steel plate. Here, the total cooling amount is based on a command from the cooling control device 31. However, the flow rate adjustment in the actual cooling water discharge is performed by opening and closing the provided valve or continuously by the flow rate adjusting valve. May be adjusted. Further, the amount of cooling water may be changed by changing the rotational speed of the pump. However, when each cooling device 33a-33e arrange | positioned between each stand is driven by the independent pump etc. corresponding to each, the cooling capacity of each cooling device 33a-33e is the other cooling device. Although it is constant regardless of the cooling water emission conditions, if a plurality of cooling devices are driven by a single pump, even if the number of rotations of the pump is constant, if the number of cooling device usage is reduced, one unit There is a characteristic that the cooling capacity of the is high. Further, when the number of rotations of the pump is increased, the amount of water discharged from each cooling device and the pressure are also increased. Since these characteristics differ depending on the piping path between the pump and the cooling device and the specifications of the nozzle of the cooling device to be described later, the amount of water discharged from the cooling device when the pump rotation speed, the number of used cooling devices is changed, and It is preferable to measure the pressure and to grasp in advance the influence (cooling characteristics) of the amount of water and the pressure on the cooling capacity. Since the above cooling characteristics are stored in the cooling control device 31, even when the cooling water discharge conditions of the cooling device are intentionally changed during rolling, it is possible to perform cooling utilizing the characteristics of the cooling device. Thus, accurate temperature control can be realized.

  Here, the cooling water outlet used in the cooling device is preferably provided with a uniform and efficient nozzle. Examples thereof include a flat spray, a slit jet, and a porous jet. Moreover, it is preferable that a backflow prevention device is attached to the nozzle as a backflow prevention means. As a backflow prevention device, there is a check valve. As a result, when the cooling water is stopped, air can be prevented from entering the nozzle and the pipe from the outside air. Therefore, the cooling water discharge is stopped with good response to the cooling water stop command. On the contrary, since air does not enter the pipe, the cooling water is discharged with good response when the cooling water supply is started again. Thereby, the intended steel plate can be cooled, and accurate cooling is possible. Also, the so-called water hammer phenomenon caused by the presence of air in the piping can be prevented, and the maintenance of the equipment can be ensured.

  Further, in the cooling devices 33a to 33e, when the steel plate 1 reaches the finish rolling mill 12, a tracking process is performed based on a cooling command from the cooling control device 31. By using such tracking processing, the use of the cooling device 33d during the measurement of the steel sheet can be appropriately prohibited as will be described later. There are cases where an error occurs in such tracking processing, or the cooling operator intentionally uses the cooling device. In such a case, the intended cooling and measurement of the steel sheet cannot be performed, which causes a problem in the quality of the hot-rolled steel sheet. Therefore, measures may be taken to prevent this. An example of this is an interlock process.

  Next, the measuring device 40 which is a measuring means will be described. The measuring device 40 is an optical or radiation measuring device, and can measure a physical quantity of the steel plate 1 passing therethrough. The type of measuring device can be used without particular limitation as long as it can obtain the required physical quantity, and may be singular or plural. The present invention is particularly effective in the case of using a measuring instrument that cannot measure or deteriorates accuracy when used in an environment where water exists. Examples thereof include a flatness meter, a meandering meter, a width measuring meter, and a plate thickness meter. The flatness meter is a measuring instrument that can measure the flatness of the steel sheet 1, that is, the waviness in the thickness direction. The meandering meter measures the runout of the steel plate 1 in the plate width direction. Further, the width measuring meter and the plate thickness meter are devices that can measure the plate width and the plate thickness.

  Next, the rolling control means 50 will be described. The rolling control means 50 has a rolling mill control device 51 and operation devices 52a and 52b.

  The rolling mill control device 51 is a device that performs a predetermined calculation based on the measurement result of the steel sheet 1 by the measuring device 40 and issues a control command to the rolling mills 21e and 21f. That is, measurement information is acquired from the measuring device 40, and control amounts of the rolling mills 21e and 21f are determined by calculation based on conditions stored in advance, and this is instructed to the rolling mills 21e and 21f. For example, in the case of a flatness meter, since the flatness at the front end of the steel plate 1 and the rear end of the steel plate 1 is measured and controlled as will be described later, the time of measurement and the work roll bending force to be controlled are calculated. . Further, in the case of a meandering meter, the amount of meandering at the rear end of the steel plate 1 is measured and controlled, so the timing and leveling amount to be controlled are calculated. Examples of the rolling mill control device 51 include an information processing unit, which includes an input terminal for inputting a measurement result, a RAM for temporarily storing the measurement result, and a calculation result, and a predetermined one as described above. A ROM that stores expressions for calculation in advance, a CPU that performs calculations based on the acquired information and a predetermined calculation expression, and an output terminal that outputs a calculation result are provided. Further, the rolling mill control device 51 is configured to be able to exchange information with the cooling control device 31 as described above. For example, the cooling device 33d for the steel plate 1 is stopped and the measurement by the measuring device 40 is started. Can be linked appropriately.

  The operation devices 52a and 52b are devices that actually operate the rolling mills 21e and 21f in response to a command from the rolling mill control device 51. Specifically, in the case of a flatness meter, it is a shape correction actuator such as a work roll bending force attached to the rolling mill, and in the case of a meandering meter, the rolling position difference (leveling) between the rolling mills 21e and 21f. It is a device to control.

  With the manufacturing apparatus 10 described above, cooling can be performed even between stands provided with the measuring device 40, and manufacturing efficiency can be improved. Next, one example of what information is actually included in the cooling control device 31 and the rolling mill control device 51 in advance and the relationship between the discharge of the cooling water and the measurement by the measuring device 40 is performed. explain. FIG. 2 shows a diagram for explaining the relationship between the cooling water emission and the measurement by the measuring instrument 40. FIG. 2A shows at least information included in the cooling control device 31 and a range in which the cooling devices 33a to 33e arranged between the stands can emit the cooling water and a range in which the cooling water must be stopped. FIG. For example, in FIG. 2A, the cooling device 33a is set so that the cooling water can be emitted over the entire range from the front end of the steel plate to the rear end of the steel plate. Here, since the length of the steel plate that originally passes through each of the cooling devices 33a to 33e varies depending on the position, all the cooling devices 33a to 33e should be indicated with the same length as shown in FIG. However, for ease of understanding, they are all converted to the same length (length after finish rolling).

  Similarly, the cooling device 33b, the cooling device 33c, and the cooling device 33e are set so that the cooling water can be emitted over the entire range from the front end of the steel plate to the rear end of the steel plate. However, just because cooling water can be emitted in the entire range does not necessarily mean that cooling water must be emitted, and it is emitted or stopped for each steel sheet provided according to the required cooling amount and target temperature. Is calculated each time. Further, when the cooling device 33d cannot emit the cooling water, the cooling supply conditions of the other cooling devices 33a to 33c and 33e can be temporarily changed to compensate for the insufficient cooling amount. .

  As for the cooling device 33d, before the leading end of the steel plate reaches the cooling device 33d, the cooling water is prohibited to be emitted from a predetermined region including the leading end of the steel plate. In addition, the emission of the cooling water is also prohibited for a predetermined region with respect to the rear end of the steel plate.

  As described above, the portion where the cooling water can be emitted and the portion where the emission should be prohibited are set in advance, and the cooling control device 31 assumes that the cooling water is emitted in an area where the cooling water can be emitted. The cooling water emission timing, amount, etc. are calculated. Here, it is the area | region of the front-end | tip part of a steel plate, and a rear-end part between the stands with which the measuring device 40 is provided that discharge | emission of cooling water is prohibited. As a result, the measuring device 40 is not affected by the cooling water during the measurement, and therefore can measure with high accuracy. On the other hand, since the cooling water can be normally emitted in other regions, the steel plate can be cooled at this time.

  FIG. 2B is a diagram showing that measurement is performed in a predetermined region from the front end portion of the steel plate and in a predetermined region from the rear end portion of the steel plate with information included in at least the rolling mill control device 51. . The steel sheet is measured by the measuring device 40 in the region painted in FIG. At this time, since the emission of the cooling water is prohibited as described above, accurate measurement can be performed without being affected by the cooling water.

In the present embodiment, the cooling device 33d prohibits the cooling water from being emitted from the front end and the rear end of the steel plate. This is because in the present embodiment, it is necessary to measure the steel plate at the front end and / or rear end of the steel plate. For example, in the case of a meandering meter, it is important to measure the steel plate at the rear end of the steel material. This is because suppressing the meandering that occurs when the rear end of the steel sheet comes out of the rolling mill has a great effect on prevention of narrowing of the steel sheet (folding of the side and end portions). In the case of a flatness meter, it is important to measure the steel sheet at both the front and rear ends of the steel sheet. This is because when the steel material existing between the stands is bitten by any of the rolling mills before and after the stand, a predetermined tension is generated in the steel plate and accurate flatness cannot be obtained. Accordingly, an accurate value can be obtained by measuring the flatness at the front end and the rear end protruding from at least one rolling mill between the stands.
For this reason, in the present embodiment, each control for performing measurement in the region of the front end and the rear end of the steel plate has been described. However, the present invention is not limited to this, and is necessary when it is necessary to stop the supply of cooling water. Accordingly, it is possible to adopt the same method as described above.

  Moreover, the cooling water emission prohibition region in the cooling device 33d shown in FIG. 2A is larger than the measurement time by the measuring device 40 shown in FIG. Is set. This considers the response of the cooling water actually emitted to the cooling water supply stop command. That is, even if the cooling water supply stop command is issued, the cooling water emission is not always stopped immediately, and if the measurement is started by the measuring instrument 40 at this time, the measurement accuracy deteriorates. Therefore, the measurement is started after the region indicated by A after the instruction to stop the supply of the cooling water is given.

  The size of the portion indicated by A in FIG. 2B can be appropriately set in consideration of the characteristics of the actual cooling device. When the above-described backflow prevention device (check valve) is provided here, since the actual cooling water emission is also stopped in response to the cooling water supply stop command, the portion indicated by A can be reduced. it can.

  The above-described effect of the present invention can be achieved by providing the cooling control device 31 and the rolling mill control device 51 as conditions in advance with the relationship between the cooling water emission and the measurement by the measuring device 40 as described above.

  Next, the forming of the hot rolled steel sheet by the manufacturing apparatus 10 will be described in order. Thus, the production apparatus 10 of the present invention and the production method S1 of the hot-rolled steel sheet of the present invention according to one embodiment (hereinafter sometimes referred to as “production method S1”) can be described in more detail.

  FIG. 3 shows a flowchart of the manufacturing method S1. As described above, the manufacturing method S1 includes the steel plate forming step S10 performed by moving the steel plate 1 along the manufacturing line, the cooling step S20 for cooling the steel plate 1, and the steel plate 1 between the rolling mill 21e and the rolling mill 21f. The rolling mill control process S30 which measures a physical quantity and controls a rolling mill is provided. Although the three steps S10, S20, and S30 can be controlled independently of each other, they interact with each other and constitute the manufacturing method S1. Each step will be described below.

The steel plate forming step S10 includes a rough rolling step S11, a conveying step S12, and a finish rolling step S13.
<Rough rolling process S11>
The rough rolling step S11 is a step of rolling the slab cast by the rough rolling machine 11 so as to have a predetermined size (thickness, width) and metal structure. Here, the characteristics of the steel sheet 1 to be supplied to the finish rolling mill 12 are determined in consideration of the finally required dimensions and characteristics of the hot-rolled steel sheet, and this is obtained by the rough rolling step S11. Rolled under conditions.

<Conveying step S12>
Conveyance process S12 is a process of conveying steel plate 1 obtained by rough rolling process S11 to finish rolling process S13. Here, in addition to conveyance, various inspections of the steel sheet are performed, and at least temperature measurement is performed. This temperature measurement is based on a temperature measuring step S21 described later, and will be described in detail later.

<Finishing rolling process S13>
The finish rolling step S13 is a step of rolling the steel sheet 1 after the rough rolling by the finish rolling machine 12 so as to have a predetermined size (thickness, width) and metal structure. Here, it rolls so that the dimension and mechanical characteristic of a hot-rolled steel plate which are finally requested | required can be generally obtained. In the finish rolling step S13, various conditions are set in order to obtain the required dimensions and characteristics of the hot-rolled steel sheet. One of them is the supply of cooling water. And another one is control of a rolling mill based on a steel plate measurement result. These will be described later.

Next, the cooling step S20 will be described. The cooling step S20 includes a temperature measurement step S21, a control determination step S22, a cooling water control step S23, and a temperature measurement step S24.
<Temperature measurement step S21>
In the temperature measuring step S21, the temperature of the steel sheet 1 is measured by the temperature measuring sensor 32a in the step provided in the conveying step S12. Thereby, the temperature information of the steel plate 1 can be obtained as shown by the broken line in FIG. Further, in the temperature measuring step S21, the obtained temperature information is converted into an electrical signal.

<Control determination step S22>
The control determination step S22 is performed by the cooling control device 31 of the manufacturing apparatus 10, acquires the electrical signal of the temperature information obtained in the temperature measurement step S21, and determines the cooling amount of the steel sheet 1 to be cooled in the finish rolling step S13. To do. And the instruction | indication of the quantity of water, timing, etc. of the cooling water which should be supplied to each cooling device 33a-33e from the obtained cooling amount is transmitted. At this time, as described above, the supply of the cooling water in the region where the supply of the cooling water is disabled is excluded. At the same time, the cooling information, the position information of the steel plate, and the like are transmitted to the information acquisition step S31 of the rolling mill control step S30 described later, whereby cooling and measurement are appropriately linked.

<Cooling water control process S23>
The cooling water control step S23 is a step in which cooling water is supplied based on the command transmitted from the cooling control device 31 in the control determination step S22. Specifically, the valve is opened or closed based on the command, or the flow rate of the flow rate adjustment valve changes.

<Temperature measurement process S24>
The temperature measuring step S24 is a step of measuring the temperature of the steel sheet 1 by the temperature measuring sensor 32b at the exit of the finish rolling mill 12. Here, it can be known how much the finish rolling mill 12 is different from the delivery target temperature.

Next, the rolling mill control step S30 will be described. The rolling mill control step S30 includes an information acquisition step S31, a steel plate measurement step S32, a control amount determination step S33, and a rolling mill control command step S34.
<Information acquisition step S31>
The information acquisition step S31 is a step of acquiring the cooling information and the position information of the steel plate from the cooling step S20 and confirming the timing for measuring the steel plate.

<Steel plate measuring step S32>
The steel plate measuring step S32 is a step of actually measuring the physical quantity of the steel plate based on the previously set measurement time. The measured result is transmitted to the rolling mill control device 51. Specifically, the measurement is performed by the measuring device 40. As described above, for example, a flatness meter, a meandering device, a plate width measuring device, and a plate thickness meter can be used.

<Control amount determination step S33>
The control amount determination step S33 determines how and how to control the rolling mill based on the result measured in the steel plate measurement step S32. This is calculated based on the relationship between the measurement result stored in advance in the rolling mill control device 51 and the control amount.

<Rolling mill control command process S34>
The rolling mill control command step S34 is a step of actually controlling the rolling mill based on the rolling mill control amount calculated in the control amount determination step S33. Specifically, the rolling mill is controlled by operating devices 52a and 52b attached to the rolling mill. This is, for example, a shape correction actuator such as a work roll bending force attached to a rolling mill in the case of a flatness meter, and a reduction position difference (leveling) between the left and right rolling mills 21e and 21f in the case of a meandering meter. Mention may be made of the device to be controlled.

  By the manufacturing method S1 as described above, the cooling and the measurement of the steel plate are appropriately linked, and the cooling can be improved even between the stands for measuring the steel plate.

  Moreover, the kind of the steel plate provided to the production apparatus 10 and the production method S1 of the present invention is not particularly limited, and any kind of steel sheet can be provided. Examples thereof include low-tensile steel, high-tensile steel, and special steel.

  Next, the embodiment will be described in more detail. However, the present invention is not limited to this embodiment. In this example, a hot-rolled steel sheet was manufactured by the hot-rolled steel sheet manufacturing method of the present invention using the hot-rolled steel sheet manufacturing apparatus 10 shown in FIG.

First, test conditions are shown.
<About steel plates>
・ Steel type: Low carbon steel ・ Dimensions of steel plate after finish rolling: 1200mm width, 4mm thickness
<About manufacturing equipment>
-Number of stands of finish rolling mill: 7-Cooling device mode: Supply / stop of cooling water by ON / OFF control of solenoid valve-Measuring instrument: Flatness meter-Control of rolling mill: rolling mills 21e and 21f (Fig. Change the work roll vendor in 1).
<Measurement time of steel sheet>
In the present embodiment, the flatness measurement by the flatness meter is performed at the front and rear ends of the steel plate between the stands of the rolling mills 21e and 21f. FIG. 4 (b) shows the time in the figure. The description of FIG. 4B corresponds to the description of FIG. 2B, and is omitted here.

Next, the results obtained based on the above test conditions will be described.
<Cooling of steel plate>
Based on the measurement conditions of the steel sheet and the rolling speed pattern of the steel sheet to be obtained (see FIG. 4C), the mode of the cooling instruction for the steel sheet was calculated. FIG. 4A shows the mode of the cooling command obtained. According to this, there is a command that cooling is not required at the tip of the steel plate and the cooling device is not used at all. And since rolling predicted that the steel plate temperature on the delivery side of the finish rolling mill would rise as the steel plate accelerated, the order to use the cooling device was issued in sequence. For example, the portion indicated by B of the steel plate is cooled only by the cooling device 33a, and the cooling devices 33a to 33d are used at the portion C of the steel plate.
In addition, a command for automatically stopping the supply of the cooling water in the cooling device 33d can be appropriately calculated even at the rear end of the steel plate before the measurement. In the region where the use of the cooling device 33d is prohibited at the rear end of the steel plate, the steel plate 1 is cooled by the cooling device 33e instead.

<Finishing outlet temperature>
FIG. 4D shows the steel plate temperature on the delivery side of the finish rolling mill in each part of the steel plate obtained by the temperature sensor 32b (see FIG. 1). According to this, the steel plate temperature close to the target temperature can be obtained from the front end to the rear end of the steel plate. Conventionally, a cooling device could not be installed between stands equipped with measuring instruments, and the cooling device 33d could not be installed. However, the maximum rolling speed of the steel sheet has to be reduced, and the rolling efficiency could not be increased. This also confirms the effectiveness of the present invention. Also, if the cooling device 33d is stopped normally, the temperature measured by the finishing mill rises due to insufficient cooling capacity, but in this embodiment, the finish rolling is performed by using the cooling device 33e instead of stopping the cooling device 33d. The rise of the steel plate temperature on the machine exit side could be suppressed.

<Relevance>
Furthermore, the experiment concerning a present Example was performed over a long period of time, and the moderate ratio of temperature and flatness was obtained. Here, “property” is the difference between the target value and the actual value. The temperature predictive value is the absolute difference between the actual value and the target for each rolled material. The length / rolling length × 100 where the value is 15 ° C. or less is obtained, and the average value of all rolled materials is calculated. On the other hand, the flatness predictability is 100% when the absolute value of the difference between the actual value of the steepness (%), which is a flatness index, and the target is 1% or less, and 0% in the other cases. The average value of all the rolled materials is calculated.

  The results are shown in FIG. In FIG. 5, the graph before the speed increase shows the case where the cooling device 33d is not provided as in the prior art, and a problem occurs if the rolling speed is increased further. According to this, the appropriate ratio of temperature and flatness was approximately 85%. On the other hand, when the rolling speed is increased by 2 m / s, as shown in “after the speed increase”, in the conventional example, the moderate ratio of flatness can be maintained, but the temperature greatly deviates from the target. This is due to the lack of cooling. On the other hand, in the examples, the moderate ratios of temperature and flatness were generally maintained despite the increase in rolling speed, and the effects of the present invention could be confirmed. As a result, the rolling efficiency could be improved by 100%.

  Although the present invention has been described in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein, The method and apparatus for producing a hot-rolled steel sheet, which can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, are also within the technical scope of the present invention. It must be understood as included.

It is a schematic diagram of the manufacturing apparatus of the hot rolled sheet steel of the present invention concerning one embodiment. It is the cooling control apparatus which concerns on one embodiment, the cooling memorize | stored in a control apparatus, and the information of a physical quantity measurement time. It is a flowchart of the manufacturing method of the hot rolled sheet steel of this invention which concerns on one embodiment. It is a graph which shows the conditions of an Example and a result. It is a graph which shows the result (property rate) of an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 10 Hot-rolled steel plate manufacturing apparatus 11 Rough rolling mill 20 Rolling means 21a to 21g Rolling mill (stand)
DESCRIPTION OF SYMBOLS 30 Cooling means 31 Cooling control apparatus 32a, 32b Temperature measuring sensor 33a-33e Cooling apparatus 40 Measuring device (measuring means)
DESCRIPTION OF SYMBOLS 50 Rolling control means 51 Rolling mill control apparatus 52a, 52b Operation apparatus S1 Manufacturing method S10 Steel plate forming process S11 Coarse rolling process S12 Conveyance process S13 Finishing rolling process S20 Cooling process S21 Temperature measuring process S22 Control determination process S23 Cooling water control process S24 Measurement Temperature process S30 Rolling mill control process S31 Information acquisition process S32 Steel plate measurement process S33 Control amount determination process S34 Rolling mill control command process

Claims (5)

A method of producing a hot-rolled steel sheet using a finish rolling mill having at least three stands,
Measuring the physical quantity of the steel sheet with at least one measuring device provided between at least one of the plurality of stands;
Controlling the finish rolling mill based on the obtained physical quantity;
Cooling the steel sheet with a cooling device capable of emitting cooling water provided between a plurality of stands including between the stands provided with the measuring device, and
While the physical quantity is being measured by the measuring device, the cooling water is prohibited from being emitted between the stands provided with the measuring device, and provided between the stands where the measuring device is not provided. In the cooling device, the condition of the cooling water is controlled so as to increase the cooling amount. The method for manufacturing a hot-rolled steel sheet according to claim 1, wherein the measuring device includes a meandering meter. The method for producing a hot-rolled steel sheet according to claim 1 or 2 , wherein the measuring device includes a flatness meter. The method for producing a hot-rolled steel sheet according to any one of claims 1 to 3 , wherein the cooling device is provided with a backflow prevention means for preventing a backflow of the cooling water. A hot-rolled steel plate manufacturing apparatus including a finish rolling mill having a plurality of stands,
At least one measuring unit provided between at least one of the stands and measuring a physical quantity of the steel sheet;
A control device for determining a control amount of the finish rolling mill based on a physical quantity measured by the measuring device;
An operation device for controlling the finish rolling mill based on a control amount determined by the control device;
A cooling device capable of emitting cooling water provided between a plurality of stands including between the stands provided with the measuring device,
The cooling device includes a backflow prevention device that prevents backflow of the cooling water. While the physical quantity is being measured by the measuring device, the cooling water is emitted between the stands provided with the measuring device. apparatus for producing a hot-rolled steel sheet shall be the characteristic to be prohibited.

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