JP5617321B2 - Steel plate manufacturing method using pump for driving cooling device - Google Patents

Description

  The present invention relates to a method for manufacturing a steel plate, and more particularly to a method for manufacturing a steel plate using a pump that drives a cooling device capable of suppressing power consumption.

  Steel sheets used for automobiles, structural materials, and the like are manufactured so that mechanical properties such as strength, workability, and toughness, and appearance such as dimensions and surface properties become desired. One means for that purpose is to control the temperature of the steel sheet in hot rolling, which is one of the manufacturing processes of the steel sheet. In particular, the mechanical properties of the steel sheet vary greatly depending on the temperature control during rolling.

Cooling water is supplied to the steel sheet before the predetermined position so that the steel sheet reaches the target temperature at the predetermined position in the hot rolling process. Examples of the predetermined position and the cooling water supply position therefor include the following.
・ Cooling water is supplied between the stands of the finish rolling mill in order to set the steel sheet temperature on the exit side of the finishing mill as the target temperature.
-In order to set the steel sheet winding temperature as the target temperature, cooling water is supplied by a cooling device provided in the runout table.
-Cooling water is supplied in the cooling device in order to set the steel plate temperature on the outlet side of the cooling device installed immediately after the finishing rolling mill to the target temperature.

  Here, the cooling water is supplied by injecting the cooling water pressurized by the pump from a nozzle or the like. Therefore, the above-described control for setting the steel plate to the target temperature is performed by adjusting the number of headers to be used by turning on / off some of the plurality of arranged headers that supply cooling water to the nozzles. Often.

  Patent Document 1 discloses a method of manufacturing a hot-rolled steel strip that can manufacture a hot-rolled steel strip by controlling the finish rolling mill outlet temperature to a target value in the longitudinal direction. Here, in order to control the finishing temperature of the steel strip to a target value, it is described that the number of descaling devices and cooling devices used between the finishing stands and the injection pressure are set.

JP 2005-296773 A

  As described above, the temperature control is performed by ON / OFF of the header, and the number of rotations of the motor for driving the pump is usually fixed to a maximum value in a possible range. This is because the pump cannot change the rotation speed instantaneously, and therefore cannot cope with a sudden change in setting. However, wasteful electric power has been consumed by always maintaining the motor rotational speed at such a high level. Patent Document 1 describes that the injection pressure is set from the viewpoint of preventing upward and downward warping when the material to be rolled bites into the rolling mill and from the viewpoint of preventing a temperature increase after reaching the maximum speed. Yes, but not considering power consumption.

  Then, this invention makes it a subject to provide the manufacturing method of the steel plate using the pump which drives the cooling device which can suppress the power consumption required for a pump drive in view of the said problem.

  The present invention will be described below.

The invention according to claim 1 is a method of manufacturing a steel sheet, comprising a step of bringing the steel sheet to a target temperature by supplying cooling water to the surface of the steel sheet, the pressure of the cooling water supplied in the step and / or Alternatively, the flow rate is controlled by changing the rotational speed of the pump, and the rotational speed of the pump is such that the difference between the target temperature of the steel plate and the predicted temperature of the steel plate in a predetermined facility is included in a predetermined range. The steel plate manufacturing method is characterized in that the rotational speed of the pump is changed before the tip of the steel plate reaches the predetermined equipment, and the rotational speed of the pump is not changed until the steel plate passes through the predetermined equipment. is there.

  Here, “steel plate surface” does not mean “front surface” but includes “front surface”, “back surface”, etc., and “surface” which is an interface between the steel plate and the atmosphere. It is a concept that means everything.

The invention according to claim 2 is a method of manufacturing a steel plate, comprising a step of bringing the steel plate to a target temperature by supplying cooling water to the surface of the steel plate, and the pressure of the cooling water supplied in the step and / or Alternatively, the flow rate is controlled by changing the number of revolutions of the pump, and the number of revolutions of the pump is such that the difference between the target temperature of the steel plate in the predetermined equipment and the predicted temperature of the steel plate is included in the predetermined range. A method of manufacturing a steel sheet, characterized in that the number of revolutions of the pump is changed at least once while the steel sheet is passing through a predetermined facility based on the determination.

The invention of claim 3 is a method of manufacturing a steel sheet according to claim 2, the rotation speed of the change of the pump requires the highest cooling capacity when not used tip of the steel plate, and the cooling water It is performed based on the position of the steel plate.

Invention of Claim 4 is a manufacturing method of the steel plate as described in any one of Claims 1-3. The number of rotations of a pump is the heat transfer coefficient per header with which a cooling device is equipped, and the header. A mathematical model based on the number of lines used is used.

Invention of Claim 5 is a manufacturing method of the steel plate as described in any one of Claims 1-4 . WHEREIN: The target temperature of a steel plate is between the stands of a finish rolling mill which has several stands, and a finish rolling mill. The temperature is at least one of the outlet side and the outlet side of the cooling device disposed on the outlet side of the finish rolling mill.

The invention according to claim 6 is the method for producing a steel sheet according to claim 5 , wherein the cooling water pressure and / or flow rate is controlled by a cooling device disposed between the stands of the finishing mill, and the finishing mill. It is performed with respect to at least one of the cooling devices arrange | positioned at the exit side of this.
Invention of Claim 7 is the manufacturing method of the steel plate as described in any one of Claims 1-4, After the rotation speed of a pump is determined, the process of determining the number of the header which injects cooling water including.

  The invention according to claim 8 is the method for producing a steel sheet according to any one of claims 1 to 4, wherein the required cooling capacity is derived from the predicted temperature when the cooling water is not used, and prepared in advance. The pump rotation speed and the header usage number are controlled with reference to a table that outputs the pump rotation speed and the header usage number according to the cooling capacity.

According to the ninth aspect of the present invention, when the required change in the cooling capacity is positive and the change is large, the number of rotations of the header is determined by determining the pump rotation speed based on the maximum value of the required cooling capacity. Steel sheet manufacturing method that controls cooling capacity by controlling the cooling capacity only by using the number of headers without changing the pump speed when the required change in cooling capacity is negative and the change is large It is.
The invention according to claim 10 is a rolling mill, a pump for pressurizing cooling water, a motor for rotating the pump, a header for flowing cooling water supplied from the pump, and the header disposed on the header, A cooling device having a nozzle for injecting cooling water, and a cooling control device that controls a motor and calculates a predicted temperature of the steel plate, and the cooling control device has a difference between the target temperature of the steel plate and the predicted temperature of the steel plate. The number of rotations of the pump is determined so that it is within the predetermined range, the number of rotations of the pump is changed before the tip of the steel plate reaches the rolling mill, and the number of rotations of the pump is changed until the steel plate passes through the rolling mill. This is an apparatus for manufacturing a steel sheet that performs control.
The invention according to claim 11 is a rolling mill, a pump for pressurizing cooling water, a motor for rotating the pump, a header for flowing cooling water supplied from the pump, and the header disposed on the header, A cooling device having a nozzle for injecting cooling water, and a cooling control device that controls a motor and calculates a predicted temperature of the steel plate, and the cooling control device has a difference between the target temperature of the steel plate and the predicted temperature of the steel plate. A steel plate that determines the rotational speed of the pump so as to be included in a predetermined range, and controls to change the rotational speed of the pump at least once while the steel plate is passing through the rolling mill based on the determination. It is a manufacturing apparatus.
The invention according to claim 12 is a program for controlling a pump for supplying cooling water to a cooling device arranged in a steel plate manufacturing apparatus, the step of determining the number of headers provided in the cooling device; Select the control point on the steel plate to determine the pump speed, set the control point condition, predict the steel plate temperature, and calculate the difference between the predicted temperature and the target temperature. And a step of determining the number of revolutions of the pump based on the result, and a program for controlling the pump for supplying cooling water.

  According to the steel plate manufacturing method of the present invention, the cooling device can be driven with the minimum number of rotations of the pump. Therefore, it is possible to suppress the power consumption required to drive the pump while maintaining the necessary cooling capacity. Moreover, according to this, since it is possible to adjust a cooling capacity with the rotation speed of a pump, a cooling capacity can be finely adjusted and the temperature fluctuation of a steel plate can also be suppressed.

It is the figure which showed typically a part of manufacturing apparatus provided to the manufacturing method of the hot-rolled steel plate concerning one embodiment. It is a figure explaining the upper surface water supply means among the cooling devices between stands. It is a flow which controls a pump rotation speed. It is the figure which showed the control of Example 1 typically. It is the figure which showed the control of Example 2 typically.

  The above-mentioned operation and gain of the present invention will be clarified from the following embodiments for carrying out the invention. Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these embodiments.

FIG. 1 is a conceptual diagram for explaining a hot-rolled steel sheet manufacturing apparatus 10 (hereinafter sometimes referred to as “manufacturing apparatus 10”) used in a method for manufacturing a hot-rolled steel sheet according to one embodiment. It is. In FIG. 1, the steel plate 1 is conveyed from the left side (upstream side, inlet side) to the right side (downstream side, outlet side) of the paper surface, and the vertical direction is the vertical direction of the paper surface. Here, the pass line is indicated by a broken line P. The upstream side (entry side) / downstream side (exit side) direction may be referred to as the passing plate direction, and the direction of the width of the steel plate to be passed in the direction perpendicular to this direction (back / near side in FIG. 1) Direction) may be referred to as the plate width direction. In the drawings, repeated reference numerals may be omitted for easy viewing.
In addition, although the manufacturing method of a "hot-rolled steel sheet" is demonstrated here as one embodiment, it is not necessarily intended only for a "hot-rolled steel sheet", and it cools by injecting cooling water using a pump. If so, it is applicable. This includes, for example, production of “thick steel plate”.

As shown in FIG. 1, the manufacturing apparatus 10 includes a hot finish rolling mill row 11, an inter-stand cooling device 12, 12,..., A pump 15, a motor 16, a pinch roll 17, a winding device 18, a cooling device 19 immediately after, And a hot-run cooling device 20.
Further, the manufacturing apparatus 10 has a cooling control device 25 as means for controlling the motor 16.
In addition, although illustration and description are omitted here, a heating furnace, a rough rolling mill row, and the like are arranged on the entry side from the hot finish rolling mill row 11, and a steel plate for entering the hot finish rolling mill row 11 is arranged. Conditions are in place.

  A hot-rolled steel sheet is generally manufactured as follows. That is, the rough bar extracted from the heating furnace and rolled to a predetermined thickness by the rough rolling mill is continuously rolled to the predetermined thickness by the hot finish rolling mill row 11. At this time, rolling is performed while the temperature of the steel plate 1 is controlled by the inter-stand cooling devices 12, 12,. The steel plate 1 exiting the hot finish rolling mill row 11 is rapidly cooled immediately by the cooling device 19. Then, it passes through the pinch roll 17, is cooled to a predetermined winding temperature by the hot run cooling device 20, and is wound in a coil shape by the winding device 18.

Hereinafter, the manufacturing apparatus 10 will be described in detail.
In the hot finish rolling mill row 11, seven rolling mills 11a, ..., 11f, 11g are arranged in parallel along the sheet passing direction. Each of the rolling mills 11a, ..., 11f, 11g is a rolling mill that constitutes a so-called stand, and can satisfy the conditions such as the thickness, mechanical properties, and surface quality of the steel plate 1 required for the final product. Thus, rolling conditions such as a rolling reduction are set. Here, the reduction ratio of each stand is set so as to satisfy the performance that the steel sheet to be manufactured should have, but high-pressure rolling (finish rolling with a higher reduction ratio of the subsequent stage stand) is performed to greatly deform the austenite grains. From the viewpoint of making the ferrite grains finer after cooling by increasing the transition density, in the stand 11g as the final stand, the reduction rate is 15% to 50%, which is higher than normal rolling. Also good.

  The rolling mill of each stand is a pair of work rolls 11aw, 11aw,..., 11fw, 11fw, 11gw, 11gw that are actually rolled down with a steel plate interposed therebetween, and a pair of backups arranged so that the outer circumferences are in contact with the work rolls. , 11fb, 11fb, 11gb, 11gb. Further, the rolling mill includes a work roll and a backup roll, and includes housings 11ah,..., 11fh, 11gh that form an outer shell of the rolling mill and support the work roll and the backup roll. This housing has an upright portion erected oppositely, and the upright portion is erected so as to sandwich the steel plate 1 to be passed through in the plate width direction.

  The inter-stand cooling devices 12, 12,... Are cooling devices disposed between the stands, and the inter-stand cooling device 12 includes an upper surface water supply means 13 and a lower surface water supply means 14. FIG. 2 is a perspective view schematically showing a part of the upper surface water supply means 13 of one inter-stand cooling device 12 and a state in which cooling water is jetted therefrom.

The upper surface water supply means 13 is a means for supplying cooling water to the upper surface side of the steel plate 1 and includes headers 13a, 13a,..., Conduits 13b, 13b,. , And nozzles 13c, 13c,... (Not visible in FIG. 2 by the conduits 13b, 13b,...) Attached to the tips of the conduits 13b, 13b,. Moreover, ON / OFF valve 13d, 13d, ... is arrange | positioned at each header 13a, 13a, ....
The headers 13a, 13a,... Are pipes extending in the plate width direction of the steel plate 1, and such headers 13a, 13a,.
The conduits 13b, 13b,... Are a plurality of thin pipes branched from the headers 13a, 13a,. A plurality of conduits 13b, 13b,... Are provided in a comb-teeth shape along the pipe length direction of the headers 13a, 13a,.

  A nozzle 13c, 13c,... Is attached to the tip of each conduit 13b, 13b,. The nozzles 13c, 13c,... Of the present embodiment are flat type spray nozzles capable of forming a fan-shaped cooling water jet (for example, a thickness of about 5 mm to 30 mm) as shown in FIG. It arrange | positions so that a predetermined angle may be twisted with respect to the width direction. In addition, the nozzle rows adjacent in the plate passing direction are arranged so that the positions in the plate width direction are shifted, and a so-called staggered arrangement is made so that the positions in the plate width direction are the same as the adjacent nozzle rows.

The ON / OFF valves 13d, 13d,... Are ON / OFF valves arranged in the headers 13a, 13a,..., And are configured to control the execution and stop of cooling water injection for each header. ing.
Although this embodiment demonstrated the aspect which provides an ON / OFF valve for every header, it is not limited to this, One ON / OFF valve may be provided with respect to several headers.

  The lower surface water supply means 14 is a means that is disposed at a position facing the upper surface water supply means 13 across the steel plate 1 and supplies cooling water to the lower surface of the steel plate 1. Although the lower surface water supply means 14 has substantially the same configuration as the upper surface water supply means 13, although the injection direction of the cooling water is different, the description thereof is omitted here.

In this embodiment, the hot finish rolling mill row 11 includes seven rolling mills (11a to 11g), and the inter-stand cooling devices 12, 12,... Are between the first stand and the second stand, and the second stand. And the third stand, between the third stand and the fourth stand, between the fifth stand and the sixth stand, and between the sixth stand and the seventh stand.
There is no particular limitation as to which stand the inter-stand cooling device is arranged between, and the relationship with other devices and the number and position of arrangement can be set as necessary.

  The pump 15 is a device that supplies pressurized cooling water to the inter-stand cooling devices 12, 12,. In this embodiment, a single pump 15 can supply cooling water to the plurality of inter-stand cooling devices 12, 12,.

  The motor 16 is a device that rotates and drives the pump 15, and the rotation speed of the pump 15 is changed by changing the rotation of the motor 16. The motor 16 is connected to the cooling control device 25 so as to receive the command.

  The pinch roll 17 also serves as a drainer and is provided immediately on the exit side of the cooling device 19. Thereby, it is possible to prevent the cooling water sprayed in the cooling device 19 immediately afterward from flowing out to the downstream side. Furthermore, it is possible to suppress the undulation of the steel sheet 1 in the cooling device 19 immediately afterwards, and in particular, it is possible to improve the plate passing property of the steel sheet 1 before the tip of the steel sheet 1 is bitten by the winding device 18. Here, the upper roll among the rolls of the pinch roll 17 is movable up and down.

  The winding device 18 is a device that winds the rolled steel sheet 1 into a coil shape. A well-known device can be applied as the winding device 18.

  Immediately after cooling device 19 is arranged between finish rolling mill row 11 and pinch roll 17 and cools steel plate 1 immediately after finish rolling. Immediately after, the cooling device 19 also has upper surface water supply means for injecting cooling water to the upper surface side of the steel plate 1 and lower surface water supply means for injecting cooling water to the lower surface side of the steel plate 1 in the same manner as the inter-stand cooling devices 12, 12,. Have.

  The form of the upper surface water supply means and the lower surface water supply means provided in the immediately after cooling device 19 is not particularly limited as long as the steel sheet 1 can be cooled immediately after rolling by the finish rolling mill row 11. This includes, for example, the same ones as the header, conduit, and nozzle described in the inter-stand cooling devices 12, 12,. In addition, the cooling device 19 immediately after the present embodiment is configured such that cooling water can be supplied by a plurality of pumps and motors.

Furthermore, it is preferable that the immediately after cooling device 19 has the following configuration. That is, rapid cooling immediately after rolling is effective from the viewpoint of refinement of the steel sheet structure. Therefore, as shown schematically in FIG. 1, the upstream end of the immediately subsequent cooling device 19 is disposed in the final stand 11g of the finish rolling mill 11, and the steel plate 1 can be cooled from the final stand 11g. . Further, from the viewpoint of the amount of cooling water, it is preferable to cool at a high water density, and examples thereof include 10 to 25 m ³ / (m ² · min). In addition, this water amount density is with respect to the single side | surface of the steel plate 1, and larger water amount density may be sufficient as it. The cooling capacity is preferably 600 ° C./second or more in a 3 mm thick steel plate.

  Returning to FIG. 1, the manufacturing apparatus 10 will be described. The hot-run cooling device 20 is a water-cooled cooling device disposed after the pinch roll 17 and is used for cooling the steel sheet 1 to the winding temperature. Similarly to the inter-stand cooling device 12, the hot run cooling device 20 also includes an upper surface water supply means and a lower surface water supply means, and is configured to be able to cool the steel plate 1 from both the upper and lower surfaces.

  The upper surface water supply means of the hot run cooling device 20 is means for supplying cooling water to the upper surface side of the steel plate 1, and a cooling means that is usually applied can be used here. This includes, for example, a pipe laminar cooling device, which has a laminar flow nozzle.

  The lower surface water supply means of the hot run cooling device 20 is means for supplying cooling water to the lower surface side of the steel sheet 1, and a cooling means that is normally applied can be used here. Examples thereof include a spray cooling device having a “full cone spray nozzle” that forms a conical jet.

The cooling control device 25 includes a finish rolling mill outlet side temperature prediction device 26 and a motor control device 27.
The finish rolling mill outlet temperature prediction device 26 calculates and obtains the predicted temperature of the steel sheet 1 on the exit side of the finish rolling mill 11. The contents of the calculation performed here are as follows, for example.

The amount of temperature increase ΔT ₁ due to processing heat generated during rolling of each stand is expressed by the following equation (1).

Here, c is the specific heat (J / kg · ° C.) of the steel sheet 1, ρ is the density (kg / m ³ ) of the steel sheet 1, η is the processing thermal efficiency, and G is the rolling torque (N · m). Further, r is a work roll diameter (m), w is the steel 1 plate width (m), the plate thickness after the stand _{h 2} is of interest (m).

The amount of temperature decrease ΔT ₂ due to contact with a work roll (11 gw or the like) can be calculated by equation (2).

Here, c is the specific heat of the steel plate 1 (J / kg · ° C.), ρ is the density of the steel plate (kg / m ³ ), and λ is the thermal conductivity of the steel plate 1 (W / m · ° C.). In addition, h ₂ is the thickness (m) after the target stand, t _R is the time (s) that the steel plate 1 is in contact with the work roll, and TS ₂ is the surface temperature of the steel plate 1 in contact with the work roll. (° C.), and _{T R} is the work roll temperature (° C.).

And the cooling temperature fall amount by the air cooling in the conveyance of the steel plate 1 between stands and water cooling can be calculated | required by Formula (3) and Formula (4). Equation (3) is the temperature drop ΔT _3A due to air cooling, and Equation (4) is the temperature drop ΔT _3L due to water cooling.

Here, σ is the Stefan-Boltzmann constant (W / m ² · K ⁴ ), ε is the emissivity (−) of the steel plate 1, c is the specific heat (J / kg · ° C.) of the steel plate 1, and ρ is the density of the steel plate 1. (Kg / m ³ ). Α _A is the heat transfer coefficient (W / m ² · ° C.) of the air cooling part, α _R is the heat transfer coefficient by water cooling (W / m ² · ° C.), and h ₂ is the plate of the steel plate 1 immediately after the target stand. Thickness (m). T _S3L is the surface temperature (° C.) of the steel plate 1 in the water-cooled portion, T _S3A is the surface temperature (° C.) of the steel plate 1 in the air-cooled portion, T _A is the air temperature (° C.), and _TL is the cooling water temperature (° C.). t _3L is a time (second) passing through the water-cooled portion, and t _3A is a time (second) passing through the air-cooled portion. The surface temperature of the steel sheet 1 in the water-cooled part means the average temperature in the water-cooled part.

Here, the heat transfer coefficient α _R by water cooling can be obtained as follows.
The number of rotations of the pump is N, and the number of headers to be used (headers for which the ON / OFF valve is ON) is n. The characteristics of the flow rate Q (n, N) and the pressure P (n, N) per header when N and n are changed are as shown in Equation (5) and Equation (6) by performing experiments. Can be mathematically modeled.

Here, N ₀ is the reference pump speed, and P ₀ and Q ₀ are the pressure and flow rate per header when the pump speed is N ₀ . f and g are functional expressions obtained through experiments. Α (n), β (n), a, and b are values obtained by experiments.

Based on Formula (5) and Formula (6), when the number of rotations of the pump is N and the number of headers used is n, the cooling capacity (heat transfer coefficient) α _R (n, N) per header Can be obtained by experiment using the reference heat transfer coefficient H ₀ when the pump rotational speed is N ₀ as shown in Equation (7). Here, h is a functional equation obtained through experiments. Also, c and d are values obtained by experiments.

  Using the above equations, the temperature of the steel plate 1 at each stand outlet is predicted, and finally the predicted temperature of the steel plate 1 on the outlet side of the hot rolling mill train 11 is obtained.

  The motor controller 27 controls the rotational speed of the motor 16 during rolling of the steel sheet 1 based on a command from the finish rolling mill outlet temperature predicting device 26 so that the rotational speed of the pump is a predetermined value.

  With the manufacturing apparatus 10 having the above-described configuration, it is possible to suppress power consumption required for driving the pump while obtaining an appropriate cooling capacity.

  Next, an example of a method for manufacturing a hot-rolled steel sheet using the manufacturing apparatus 10 will be described. Here, the manufacturing method using the manufacturing apparatus 10 will be described for the sake of clarity, but the manufacturing apparatus 10 is not necessarily required, and other manufacturing apparatuses may be used as long as manufacturing can be performed by the method described below.

  A steel plate 1 (coarse bar) extracted from the heating furnace and rolled to a predetermined thickness by a roughing mill is supplied to the hot finish rolling mill row 11. The steel sheet 1 supplied to the hot finish rolling mill row 11 is rolled by passing through each stand of the hot finish rolling mill row 11 in order from the tip. At this time, between the stands where the inter-stand cooling devices 12, 12,... Are arranged, the cooling water controlled as described above is injected, and the steel plate 1 is brought close to the target temperature.

  Here, the inter-stand cooling devices 12, 12,... Supply cooling water to the steel sheet 1 so that the temperature on the outlet side of the hot finish rolling mill 11 becomes the target temperature. Specifically, the supply of cooling water is controlled by the motor control device 27 as follows. FIG. 3 shows a flowchart.

The cooling water supply control determination S1 includes a pump rotation speed pattern determination process S10 and a header number determination process S20.
In the pump rotation speed pattern determination process S10, a pump rotation speed pattern for supplying cooling water to obtain necessary cooling capacity while minimizing the rotation speed of the pump 15 at each control point described later is obtained. It is a step of determining. Therefore, the pump rotation speed pattern determination step S10 includes steps S11 to S17.

  Step S11 is a step of selecting a header to be used. In step S11, the number of headers to be used in the maximum state during the rolling of the same steel plate (or the location of the header to be used in the maximum state among the installed headers) is determined from the material and manufacturing dimensions of the steel plate 1. It is determined from a predetermined table consisting of the above.

Step S12 is a step of selecting a control point i that determines the pump speed. Here, the control point i is a steel plate position arbitrarily selected from the front end to the tail end of the steel plate. When the control point i is one point, it means that the pump rotational speed is not changed in the longitudinal direction. When there are a plurality of control points i, the pump rotation speed may be changed with the control point i as a boundary.
There are various ways of determining the control point i, but it is not particularly limited. For example, if the pump speed is changed twice in the longitudinal direction, the tip, the hot end rolling mill side temperature when the header is not used, the highest point compared to the target temperature, and the tail end It can be mentioned that a total of three points are used as control points. In addition, a point obtained by equally dividing the steel plate in the longitudinal direction (for example, equally divided into 10 parts) may be used as the control point.

  Step S13 is a step of setting the condition for the control point i. This is various conditions for calculating the finish rolling mill exit temperature at the position of the control point i, specifically, for example, a hot finish rolling mill for calculating the above formulas (1) to (7). The temperature on the entry side, the steel plate moving speed on the exit side of each stand, the plate thickness, and the like can be mentioned.

  Step S14 is a step of minimizing the initial value of the pump speed. The initial value is minimized, and the rotational speed is increased as necessary in the following process. Needless to say, this minimum value takes into account the minimum value of the pump speed at which the cooling device can be supplied stably. In addition, it is a value that takes into account the minimum cooling capacity required for each header in operation.

  Process S15 is a process of calculating the predicted temperature on the delivery side of the finish rolling mill. The calculation is performed by the finish rolling mill outlet temperature prediction device 26 described above, and the calculation result is transmitted to the motor control device 27.

  Process S16 is a process for determining whether the difference between the predicted finish rolling mill exit temperature obtained in S15 and the target temperature is within a predetermined range (δ) in absolute value. Here, “δ” is a control adjustment parameter determined in advance by a table.

  If the absolute value of the difference is determined to be greater than or equal to δ in step S16, it is considered that sufficient cooling capacity has not yet been obtained. Accordingly, the number of rotations of the pump is increased in step S17, and the information is transmitted to the finish rolling mill outlet side temperature prediction device 26, so that the calculation in step S15 and the determination in step S16 are performed again.

  If it is determined in step S16 that the absolute value of the difference is less than δ, the process proceeds to the next header number determination step S20. The header number determining step S20 is a step of determining the number of headers used at the control point i, and includes steps S21 to S27.

  In this embodiment, it is assumed that the inter-stand cooling devices 12, 12,... Are driven from one motor 16 and a pump 15. It may be a mode of driving. In this case, when increasing the pump rotation speed in S17, increase the plurality of pump rotation speeds uniformly, or increase the pump rotation speed of one specific pump first, and then the remaining pump rotation speed This can be dealt with by changing the number.

Also, for example, when changing the pump speed twice in the longitudinal direction, the control point at the tip, the control point at which the highest cooling capacity is required when the header is not used, the control point at the tail end What is necessary is just to calculate the pump rotation speed required in total three places. Here, the tail end is set as one of the control points. When the steel plate comes out of the work roll at the tail end, when the narrowing due to warping is anxious, the steel plate speed is reduced at the tail end. It is because it is necessary to turn off the header. However, since the response is slow when the header is turned OFF, the influence of the header OFF response can be minimized by reducing the pump rotation speed.
Examples of the interpolation method of the pump rotation speed determined by the three control points, that is, the setting method of the pump rotation speed between the control points include the following. The method of changing at the same time timing as the rolling speed pattern, adding the number of used headers with the pump speed determined at the tip, maximizing the number of used headers, and then determining the pump speed at the highest point There are various methods such as a method of changing the rotation speed at a predetermined rate, and any method can be applied.

  The header number determination process S20 is a process of strictly calculating the necessary number of headers again based on all control points based on the pattern of the pump rotation speed pattern determination process S10. For this purpose, the header number determining step S20 includes steps S21 to S28.

  Process S21 is a process of setting the initial state at the tip. It means that the following process is advanced based on the tip. It is assumed that i = 0.

  Step S22 is a step of setting a condition for the control point i. This is various conditions for calculating the finish rolling mill exit temperature at the position of the control point i, specifically, for example, a hot finish rolling mill for calculating the above formulas (1) to (7). The temperature on the entry side, the steel plate moving speed on the exit side of each stand, the plate thickness, and the like can be mentioned.

  Step S23 is a step of giving an initial condition that all headers of the header selected in step S11 are unused. The initial condition is minimized, and the number of headers used is increased as necessary in the following process.

  Process S24 is a process for calculating the predicted temperature on the exit side of the finish rolling mill. The calculation is performed by the finish rolling mill outlet temperature prediction device 26 described above, and the calculation result is transmitted to the motor control device 27.

  Process S25 is a process for determining whether the difference between the predicted finish rolling mill exit temperature obtained in process S24 and the target temperature is within a predetermined range (δ) in absolute value. Here, “δ” is a control adjustment parameter determined in advance by a table.

  If it is determined in step S25 that the absolute value of the difference is greater than or equal to δ, it is considered that sufficient cooling capacity has not yet been obtained. Accordingly, the number of headers used in step S26 is increased by one, and the information is transmitted to the finish rolling mill outlet side temperature prediction device 26, so that the calculation in step S24 and the determination in step S25 are performed again.

  If it is determined in step S25 that the absolute value of the difference is less than δ, the process proceeds to step S27. Process S27 is a process for determining whether or not each of the above processes has been completed up to the position of the tail end. If it is determined that the tail end has not been completed yet, the control point is changed (i + 1 → i), and the process is repeated from step S22. On the other hand, if it is determined that the processing up to the tail end has been completed, based on the above determination, the motor 16 is controlled and the pump 15 is driven so that the inter-stand cooling devices 12, 12,. Make it work.

  The rotation speed of the pump is controlled based on the above-described contents. That is, the pump is kept at a certain level of rotation speed at a low level before the steel plate passes. Then, the rotational speed is increased to the target pump rotational speed before the leading end of the steel plate reaches. Furthermore, after the tail end of the steel plate passes, the standby state is restored.

  In the present embodiment, it has been described that the control is based on the exit temperature of the finish rolling mill, but the present invention is not limited to this, and the temperature on the finish rolling mill entrance side, the temperature immediately after the cooling device, or the hot run cooling device The temperature may be controlled based on the later temperature.

Further, in the present embodiment, an example in which calculation is sequentially performed based on the flow and control is given, but the present invention is not limited to this. In particular, in the case of typical rolling, this is applied by a table created in advance. You may do.
Further, when the required change in cooling capacity is large, the following control may be performed. For example, when the required change in the cooling capacity is positive and the change is large, the pump speed is determined based on the maximum value of the required cooling capacity, and the cooling capacity is controlled by the number of headers used. On the other hand, when the required change in the cooling capacity is negative and the change is large, the cooling capacity can be controlled only by the number of headers used without changing the rotational speed of the pump.

  The steel plate 1 exiting the finish rolling mill row 11 is rapidly cooled immediately by the cooling device 19. Then, it passes through the pinch roll 17, is cooled to a predetermined winding temperature by the hot run cooling device 20, and is wound in a coil shape by the winding device 18.

  According to the method for manufacturing a hot-rolled steel sheet as described above, the cooling device can be driven with the minimum number of rotations of the pump. Therefore, it is possible to suppress the power consumption required to drive the pump while maintaining the necessary cooling capacity. Moreover, according to this, since it is possible to adjust a cooling capacity with the rotation speed of a pump, a cooling capacity can be finely adjusted and the temperature fluctuation of the steel plate 1 can also be reduced.

  In the above-described embodiment, the cooling water supply control determination S <b> 1 is applied to the inter-stand cooling device 12. However, the present invention is not limited to this, and the immediate cooling device 19, the hot-run cooling device 20, or a plurality of them. The present invention may be applied to other cooling devices. In such a case, the same effect as described above can be obtained. In particular, the effect is particularly remarkable for a cooling device having a large variation in the amount of water required by the steel sheet to be rolled.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

In the first embodiment, the number of control points is one, the number of pump rotations and the number of headers used are determined based on the above flow, and rolling is performed. The results are shown in FIG. In FIG. 4A, the horizontal axis represents the position of the steel sheet, the vertical axis represents “necessary cooling capacity” with a solid line, and “number of headers used” with a broken line. In FIG. 4B, the horizontal axis represents the position of the steel plate, and the vertical axis represents the number of rotations of the pump. In this example, a so-called medium carbon steel having a C content of 0.4 mass% is finally rolled to a thickness of 4 mm and a width of 1200 mm.
As can be seen from FIG. 4A, when the required cooling capacity is maximum, the number of headers used is maximum. Further, the number of headers used is controlled following the required cooling capacity curve. In addition, as can be seen from FIG. 4B, in this embodiment, since there is one control point, the pump rotational speed is determined by the above-described flow, and the rotational speed is constant.

In Example 2, it is the figure which made the control point more than one, determined the rotation speed of the pump and the number of headers to be used based on the above flow, and performed rolling. The results are shown in FIG. In FIG. 5A, the horizontal axis represents the position of the steel sheet, and the vertical axis represents “required cooling capacity” with a solid line, “number of headers used” with a broken line, and “cooling capacity” with a thick solid line. In FIG. 5B, the horizontal axis represents the position of the steel plate, and the vertical axis represents the number of rotations of the pump. In this example, similarly to Example 1 described above, a so-called medium carbon steel having a C content of 0.4 mass% is finally rolled to a thickness of 4 mm and a width of 1200 mm.
As can be seen from FIG. 5A, when the required cooling capacity is maximum, the number of headers used and the cooling capacity become maximum. The number of headers used is controlled following the required cooling capacity curve. Further, as shown in FIG. 5B, the pump rotation speed is determined by the above flow, and the rotation speed is sequentially changed. The actual “cooling capacity” is controlled so as to approach “necessary cooling capacity” in conjunction with the change in the number of revolutions of the pump.

  While the invention has been described in connection with embodiments that are presently practical and preferred, the invention is not limited to the embodiments disclosed herein, The scope and the scope of the invention can be appropriately changed without departing from the gist or idea of the invention that can be read from the entire specification, and a method of manufacturing a steel sheet accompanied by such a change must be understood as being included in the technical scope of the present invention. Don't be.

DESCRIPTION OF SYMBOLS 1 Steel plate 10 Hot rolled steel plate manufacturing apparatus 11 Hot finishing rolling mill row 11g Final stand 12 Inter-stand cooling device 13 Upper surface water supply means 14 Lower surface water supply means 15 Pump 16 Motor 17 Pinch roll 18 Winding device 19 Immediately rapid cooling device 20 Hot run cooling Device 25 Cooling control device 26 Finishing mill exit side temperature prediction device 27 Motor control device

Claims (12)

A method of manufacturing a steel sheet,
A step of bringing the steel sheet to a target temperature by supplying cooling water to the steel sheet surface, and the control of the pressure and / or flow rate of the cooling water supplied in the process is performed by changing the number of rotations of the pump;
The number of rotations of the pump is determined so that a difference between a target temperature of the steel plate in a predetermined facility and a predicted temperature of the steel plate is included in a predetermined range, and a tip of the steel plate reaches the predetermined facility. rotational speed of the pump is changed before, a manufacturing method of a steel plate you characterized in that it does not change the rotational speed of the pump to the steel sheet passes through the predetermined equipment. A method of manufacturing a steel sheet,
A step of bringing the steel sheet to a target temperature by supplying cooling water to the steel sheet surface, and the control of the pressure and / or flow rate of the cooling water supplied in the process is performed by changing the number of rotations of the pump;
The number of rotations of the pump is determined so that a difference between a target temperature of the steel plate in a predetermined facility and a predicted temperature of the steel plate is included in a predetermined range, and based on the determination, the predetermined facility is at least once while the steel plate is passing, the manufacturing method of the steel plate characterized in that the rotational speed of the pump is changed. The rotation speed of the pump is changed based on a tip portion of the steel plate and a position of the steel plate that requires the highest cooling capacity when cooling water is not used. The manufacturing method of the steel plate of 2 . The said pump rotation speed uses the mathematical model based on the heat transfer coefficient per header with which a cooling device is equipped, and the usage number of the said header, It is any one of Claims 1-3 characterized by the above-mentioned. A method of manufacturing a steel sheet. The target temperature of the steel sheet is at least one of the stands of the finish rolling mill having a plurality of stands, the exit side of the finish rolling mill, and the exit side of the cooling device disposed on the exit side of the finish rolling mill. It is set as temperature, The manufacturing method of the steel plate as described in any one of Claims 1-4 characterized by the above-mentioned. Control of the pressure and / or flow rate of the cooling water is performed on at least one of a cooling device arranged between the stands of the finishing mill and a cooling device arranged on the exit side of the finishing mill. The manufacturing method of the steel plate of Claim 5 characterized by these.   The manufacturing method of the steel plate as described in any one of Claims 1-4 including the process of determining the number of the header which injects the said cooling water after the rotation speed of the said pump is determined.   Deriving the required cooling capacity from the predicted temperature when the cooling water is not used, referring to the table that outputs the pump speed and the number of headers used according to the cooling capacity prepared in advance, the pump speed The method of manufacturing a steel sheet according to any one of claims 1 to 4, wherein the number of headers used and the number of headers used are controlled. When the required change in cooling capacity is positive and the change is large, the pump rotation speed is determined based on the maximum required cooling capacity, and the cooling capacity is controlled by the number of headers used.
A steel sheet manufacturing method in which the required cooling capacity change is negative, and when the change is large, the cooling capacity is controlled only by the number of headers used without changing the number of revolutions of the pump.   A rolling mill,
A pump for pressurizing the cooling water;
A motor for rotating the pump;
A header through which the cooling water supplied from the pump flows, and a cooling device disposed in the header and having a nozzle for injecting the cooling water to a steel plate;
A cooling control device for controlling the motor and calculating the predicted temperature of the steel sheet,
  The cooling control device determines the rotational speed of the pump so that a difference between a target temperature of the steel plate and a predicted temperature of the steel plate is included in a predetermined range, and a tip of the steel plate reaches the rolling mill. An apparatus for manufacturing a steel plate, wherein the rotational speed of the pump is changed before and the control is performed so that the rotational speed of the pump is not changed until the steel plate passes through the rolling mill.   A rolling mill,
A pump for pressurizing the cooling water;
A motor for rotating the pump;
A header through which the cooling water supplied from the pump flows, and a cooling device disposed in the header and having a nozzle for injecting the cooling water to a steel plate;
A cooling control device for controlling the motor and calculating the predicted temperature of the steel sheet,
  The cooling control device determines the number of revolutions of the pump so that a difference between a target temperature of the steel plate and a predicted temperature of the steel plate is included in a predetermined range, and based on the determination, the rolling mill is An apparatus for manufacturing a steel sheet, which controls to change the rotational speed of the pump at least once while the steel sheet is passing.   A program for controlling a pump for supplying cooling water to a cooling device disposed in a steel plate manufacturing apparatus,
  Determining the number of headers used in the cooling device;
Selecting a control point on the steel plate to determine the rotational speed of the pump;
Setting conditions for the control points;
Predicting the temperature of the steel sheet;
Calculating a difference between the predicted temperature and the target temperature, and determining a rotation speed of the pump based on the result, and controlling a pump for supplying cooling water.