JP2011098393A - Device and method for heat treating thick steel plate, method of manufacturing steel plate and line for manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make with planned, the temperature distribution in the longitudinal direction of a thick steel plate. <P>SOLUTION: In a heat treating device for the thick steel plate including a straightening device 1 and an induction heating device 2 on a line, a pressing roll 3 having a predetermined rolling force for preventing the deformation or a slip of the thick steel plate 5 which is heat treated with the induction heating device, is provided oppositely to the conveying rolls 4 on the outlet side of the induction heating device 2. Even when the thick steel plate 5 is deformed by the heat treatment, because the deformation of the thick steel plate 5 is straightened with the pressing roll 3, the target conveying speed is maintained, the heating time becomes constant and the steel plate 5 is heated at the target temperature in the longitudinal direction. Because the deformation of the thick steel plate 5 is straightened with the pressing roll 3, even when using the induction heating device 2, the target heat treatment is performed without obstructing the conveyance of the thick steel plate 5 and the thick steel plate 5 is manufactured stably at higher productivity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus and method for a thick steel plate that reheats and heat-treats a hot-rolled steel plate for material adjustment, and a method and a production line for the thick steel plate.

Heat treatment of thick steel plates is often performed in a batch-type reheating furnace, and since it is inferior in productivity, induction heating type heat treatment has been proposed conventionally.
One conventional induction heating type heat treatment method is that when a thick plate is continuously heated by an induction heating furnace array in which a plurality of induction heating furnaces are arranged, the end in the width direction of the thick plate inserted in the final induction heating furnace Since the temperature of the part is higher than that of the central part, the temperature of the end of the thick plate is lowered by cooling water from the temperature of the central part before being inserted into the final induction heating furnace. The thick plate is heated to make the temperature in the width direction uniform (see, for example, Patent Document 1).

Further, another conventional induction heating type heat treatment method is such that when the leading end of the metal material is inserted into the induction heating furnace, the induction heating furnace has an outlet, while the rear end of the metal material is the induction heating furnace. When inserted into the induction heating furnace, the heat generator is positioned at the inlet of the induction heating furnace, and the front and rear ends of the metal material are heated, so that the temperature of the front, rear and center of the metal material is uniform. (For example, refer to Patent Document 2).
Furthermore, another conventional heat treatment method for thick steel plates is to heat-treat thick steel plates with a small amount of residual stress efficiently by heat-treating the steel plates with an induction heating device installed online after hot rolling. (For example, refer to Patent Document 3).

Japanese Patent Laid-Open No. 48-25239 (first page, FIG. 1) Japanese Patent Laid-Open No. 48-25237 (first page, FIG. 1) Japanese Patent Laying-Open No. 2003-13133 (first page, FIG. 1)

Although it has been obvious that conventional induction heating type heat treatment can be performed with high efficiency, it has not become a standard method until now. This is because, as shown in Patent Document 1 and Patent Document 2, there was a problem of uniform heating properties with respect to the material to be heated.
That is, the induction heating type heat treatment method described in Patent Document 1 is intended to solve the problem of uniform heating in the width direction, but is not considered for uniform heating in the longitudinal direction. This is because there was a problem of becoming.
In addition, in the induction heating type heat treatment method described in Patent Document 2, the problem of uniform heatability in the longitudinal direction is solved, but the problem of cooling of the leading end in the longitudinal direction is insignificant. This is because the temperature uniformity and the heating to a predetermined temperature were more serious problems.

Furthermore, the heat treatment method of the thick steel plate described in Patent Document 3 heat-treats the thick steel plate with an induction heating apparatus installed on-line, which is based on the premise that the steel plate is uniformly heated. Correction is performed by a hot leveler.
However, in actuality, deformation such as warpage occurs in the steel sheet by heat treatment by the induction heating device, but since it is assumed that the steel sheet is heated uniformly, no consideration is given to the deformation of the steel sheet. .

Therefore, when the steel sheet is deformed by heat treatment by an induction heating device, the thick steel sheet slips even if the transport roll for transporting the thick steel sheet has a predetermined speed.
The temperature of the thick steel plate is determined by the conveying speed of feeding the thick steel plate and the output of the induction heating device. However, if the thick steel plate slips, the conveying speed becomes slow due to the slip, or the thick steel plate becomes electromagnetic of the induction heating device. There is a problem that the suction speed is increased and the transport speed is increased and the transport speed is changed, so that the temperature in the longitudinal direction becomes unexpected.

Furthermore, since the space through which the induction heating device can pass the thick steel plate is limited, it is necessary to correct the deformation of the plate so as not to destroy the induction heating device. Although it can be easily imagined that a method for flattening the sheet is necessary, even if it is corrected in advance, the plate may be deformed by the heating of the induction heating device.
Therefore, even if the method of flattening the thick steel plate is adopted before the induction heating device, the deformation of the plate still occurs, and the deformation of the plate is mainly warping or twisting, and the induction heating device is broken or the plate is inclined. As a result, there is still a problem that heating failure occurs and the temperature in the longitudinal direction becomes unscheduled.

  In addition, when a thick steel plate is rapidly heated using an induction heating device, as described above, it is difficult to heat-treat the thick steel plate uniformly in the width direction and the longitudinal direction, and the thick steel plate is warped. In a thick steel plate having a large width, a large warp that is compounded in the longitudinal direction and the width direction is likely to occur. Therefore, when a thick steel plate collides with the next induction heating device when a transport roll or a plurality of induction heating devices are provided, the thick steel plate This significantly impedes the transfer of the material and makes the target heat treatment impossible. In this regard, as described above, Patent Document 3 proposes a method of arranging a hot leveler on the downstream side of the induction heating device. However, since the hot leveler is a large-scale device, induction heating is not possible. In the hot leveler, there is a problem that it cannot be placed close to the equipment, and when multiple induction heating devices are provided, it cannot be placed between adjacent induction heating devices. There is a problem that collision with the heating device cannot be prevented.

  The present invention has been made in order to solve such problems, and a heat treatment apparatus and method for a thick steel plate, and a heat treatment thereof, which enables the temperature distribution in the longitudinal direction of the thick steel plate to be as intended. It aims at providing the manufacturing method and manufacturing line of a thick steel plate using an apparatus.

  The heat treatment apparatus for a thick steel plate according to the present invention has a plurality of transport rolls for transporting the thick steel plate and at least one induction heating device for heating the steel plate, and the induction heating device is adjacent to each other. And a predetermined rolling force for preventing deformation or slippage of the plate, on the exit side of the induction heating device that is disposed between the conveying rolls and at least the most upstream of the induction heating devices, At least one pressing roll for pressing the thick steel plate from the upper surface is provided, and at least the uppermost pressing roll among the pressing rolls faces the conveying roll above the conveying roll on the outlet side of the induction heating device. Are arranged.

  The thick steel plate heat treatment apparatus according to the present invention is provided with at least one pressing roll for pressing the thick steel plate from the upper surface on the entry side of the induction heating device on the most upstream side.

In addition, the thick steel plate heat treatment apparatus according to the present invention has a line equipped with an induction heating device that heat-treats the hot-rolled thick steel plate and a straightening device that corrects deformation of the plate heat-treated by the induction heating device. In the steel plate heat treatment apparatus, there are a plurality of the induction heating apparatuses, and at least a predetermined number for preventing deformation or slippage of the sheet on the exit side or the entry side and the exit side of the induction heating apparatus on the most upstream side. Each is provided with a pressing roll having a rolling force.
The thick steel plate heat treatment apparatus of the present invention is characterized in that the pressing rolls are provided between the induction heating apparatuses adjacent to each other.

In the thick steel plate heat treatment apparatus of the present invention, the roll diameter of the pressing roll is larger than about ½ of the size of the opening of the induction heating apparatus.
Further, in the thick steel plate heat treatment apparatus of the present invention, the pressing roll is a driving roll having a rotational force capable of suppressing a speed change due to electromagnetic attraction and repulsion of the induction heating device. And

Moreover, the heat processing method of the thick steel plate of this invention prevents the deformation | transformation of the board heat-processed with the induction heating apparatus using the said heat processing apparatus of a thick steel plate, or the slip of a board.
Moreover, the manufacturing method of the thick steel plate of this invention includes the process of pressing a thick steel plate from the upper surface using the said heat processing apparatus in a heat processing process.

  Moreover, the production line of the thick steel plate of this invention is equipped with the hot rolling mill, the accelerated cooling apparatus, and said heat processing apparatus on the same line.

The thick steel plate production line of the present invention includes a straightening device between the accelerated cooling device and the heat treatment device.
Moreover, the production line of the thick steel plate of this invention equips the downstream of the said heat processing apparatus with the said correction apparatus.

  As described above, according to the present invention, the slip and the deformation of the plate that are generated when the plate is deformed by the heat treatment of the induction heating device can be prevented by the pressing roll, and the target conveyance speed is maintained. The time becomes constant and the thick steel plate is heated at the target temperature in the longitudinal direction. For this reason, even if it uses an induction heating apparatus, the target heat processing can be performed without inhibiting conveyance of a steel plate, and a steel plate can be manufactured stably with higher productivity.

The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 1 of this invention. The side view which shows a deformation | transformation of the front-end | tip of the thick steel plate by an induction heating apparatus. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 2 of this invention. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 3 of this invention. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 4 of this invention. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 5 of this invention. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 6 of this invention. The side view which shows the structure of the heat processing apparatus of the thick steel plate of Embodiment 7 of this invention. (A)-(G) are figures which show arrangement | positioning of a pressing roll. Explanatory drawing which defines the curvature height h of a thick steel plate. The figure which showed the relationship between the arrangement | positioning conditions of the pressing roll of FIG. 9 (A)-(G), and the curvature height h of a thick steel plate. The figure which shows an example of the manufacturing line of this invention. The figure which shows another example of the manufacturing line of this invention. The graph which shows the temperature distribution of a comparative example.

Embodiment 1 FIG.
FIG. 1 is a side view showing a configuration of a heat treatment apparatus for a thick steel plate according to Embodiment 1 of the present invention, and FIG. 2 is a side view showing deformation of the tip of the thick steel plate by an induction heating device.
In the figure, the heat treatment apparatus for a thick steel plate according to Embodiment 1 of the present invention is installed after the straightening device 1 for correcting the deformation of the plate after hot rolling and water cooling the thick steel plate 5, and after the straightening device 1, The basic configuration is that one induction heating device 2 that performs rapid heating treatment and a pinch roll 3 installed after the induction heating device 2 are provided on the line. The pinch roll 3 has a predetermined rolling force to prevent the deformation of the thick steel plate 5 within the elastic deformation, and is referred to as a pressing roll in the present invention because the thick steel plate 5 is pressed. Reference numeral 4 denotes a transport roll that is installed in front of the straightening device 1, at a position facing the pressing roll 3, and downstream of the pressing roll 3, and transports the thick steel plate 5. The transport roll 4 has a driving force that is rotated by a driving source (not shown). In the figure, the steel sheet is conveyed from left to right. The same applies to the drawings of the embodiments described later.

The straightening device 1 is provided with a plurality of upper and lower rolls, and corrects the shape defect of the thick steel plate 5 caused by rolling such as warping or accelerated cooling by repeated bending.
The induction heating device 2 is of a solenoid type.
The pressing roll 3 is disposed so as to face the transport roll 4 and is configured so that a predetermined reduction force can be applied to the thick steel plate 5. The pressing force of the pressing roll 3 is set to such an extent that the thick steel plate 5 can be prevented from deforming or slipping when the thick steel plate 5 passes between the pressing roll 3 and the transport roll 4. The pressing roll 3 can freely rotate. And the roll diameter R of this pressing roll 3 is set to a dimension more than half of the gap G of the opening 2a of the induction heating device 2 so that the deformed thick steel plate 5 does not pass above the axis of the pressing roll 3. ing. Thereby, the complicated control which lowers the pressing roll 3 according to the front-end | tip passage of a steel plate becomes unnecessary.

Next, the operation of the thick steel plate heat treatment apparatus according to Embodiment 1 of the present invention will be described.
Even if the thick steel plate 5 after hot rolling and water cooling is flattened by the straightening device 1, when the thick steel plate 5 is heat-treated by passing through the induction heating device 2, the thickness is increased by heating as shown in FIG. The steel plate 5 may be deformed to warp upward.
As described above, when the thick steel plate 5 is warped upward, the mass of the thick steel plate 5 to be heated increases by 1 / cos θ, and is heated by a corresponding amount lower than the target temperature. . Further, when the thick steel plate 5 is deformed downward, the steel plate 5 collides with the transport roll 4 and slips, and becomes slower than the target transport speed, so that the heating time becomes longer and is heated higher than the target temperature. The Rukoto.

  Thus, even if the thick steel plate 5 is deformed to warp or warp by the induction heating device 2, the pressing roll 3 has a pressing roll 3 at a position opposed to the transport roll 4, so that the slippage is caused by the pressing roll 3. Is prevented, and the deformation of the upper and lower warpage of the thick steel plate 5 is corrected and the thick steel plate 5 is flattened, so that the target conveying speed is maintained, the heating time is constant, and the target It will be heated at temperature.

As described above, the amount of temperature increase is inversely proportional to the increase in mass in the induction heating device 2 due to deformation of the thick steel plate 5, and is therefore proportional to cos θ.
Therefore, in contrast to θ = 0 ° and cos θ = 1 in which the thick steel plate 5 is straight, it is better to industrially set cos θ> 0.995 and θ <5.7 °, which is caused by heating. This corresponds to heating to the target temperature within a deviation of 2.5 ° C. when the temperature rise is 500 ° C.

  In the first embodiment, since the pressing roll 3 is provided on the exit side of the induction heating device 2 so as to oppose the transport roll 4, even if the plate is deformed by the heat treatment of the induction heating device 2, the deformation of the plate is pressed. Since it is corrected by the roll 3, the target conveying speed is maintained, the heating time is constant, and the thick steel plate 5 is heated at the target temperature in the longitudinal direction.

In the first embodiment, the pressing roll 3 is freely rotatable, but the pressing roll 3 itself may have a driving force. In this case, it is necessary to keep the rotational speeds of the pressing roll 3 and the transport roll 4 the same and to synchronize the rotational speeds of the pressing roll 3 and the transport roll 4 in order to keep the transport speed of the thick steel plate 5 constant.
This is desirable when the upward and downward warping of the thick steel plate 5 is small, but when the upward and downward warping of the thick steel plate 5 is large, the rotational speeds of the pressing roll 3 and the conveying roll 4 are changed. Thus, it becomes possible to correct these warpages.
Another reason for applying a driving force to the pressing roll 3 is to counter the speed change caused by the electromagnetic force when the conveying speed of the thick steel plate 5 is changed by the electromagnetic force of the induction heating device 2. The torque is applied in combination with a predetermined reduction force.

Embodiment 2. FIG.
FIG. 3 is a side view showing the structure of the thick steel plate heat treatment apparatus according to Embodiment 2 of the present invention. In FIG. 3, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description of the duplicated components is omitted. The second embodiment is different from the first embodiment in that three induction heating devices 2 are used. In this second embodiment, the pressing roll 3 is arranged in the immediate vicinity of the exit side of the induction heating device 2 on the most upstream side so as to face the transport roll 4, and the exit side or entry of the induction heating device 2 on the downstream side thereof is arranged. The pressing roll 3 is not arranged on both the side and the exit side.

  In the second embodiment, when three induction heating devices 2 are used, the pressing roll 3 is arranged to face the transport roll 4 only in the immediate vicinity of the outlet side of the most upstream induction heating device 2. I am doing so. This is because the effect of correcting the deformation of the plate and the prevention of the slip of the plate by the pressing roll 3 arranged in the immediate vicinity of the outlet side of the induction heating device 2 on the most upstream side is great. This is because it is considered that the pressing roll 3 does not need to be disposed on the entry side and the exit side. In addition, when it thinks that the effect of correction | amendment of a deformation | transformation of the board by the pressing roll 3 arrange | positioned in the immediate vicinity of the exit side of the induction heating apparatus 2 of the most upstream side and the prevention of a board slip is not enough, it is downstream from it. It goes without saying that the pressing roll 3 may be arranged on the exit side of the induction heating device 2 or on both the entrance side and the exit side.

Embodiment 3 FIG.
FIG. 4 is a side view showing the structure of the thick steel plate heat treatment apparatus according to Embodiment 3 of the present invention. In FIG. 4, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description of the duplicated components is omitted. This Embodiment 3 is a case where three induction heating devices 2 are used as in Embodiment 2, and the pressing roll 3 is opposed to the transport roll 4 against the outlet side of the induction heating device 2 on the most upstream side. However, as a result, the pressing rolls 3 are arranged opposite to the conveying rolls 4 between the induction heating devices 2 adjacent to each other.

As described above, when the three induction heating devices 2 are used, the pressing rolls 3 are arranged between the induction heating devices 2 adjacent to each other. When a deformation occurs in the thick steel plate 5 by heating, the deformation is corrected by the pressing roller 3 on the outlet side, and before the thick steel plate 5 enters the induction heating device 2 on the downstream side, the deformation of the plate is corrected. It is intended to prevent slipping.
Since the thick steel plate 5 is flattened in this way, the target conveyance speed is maintained, the heating time is constant, and the thick steel plate 5 is heated at the target temperature in the longitudinal direction. . Moreover, whenever the thick steel plate 5 is heat-processed with each induction heating apparatus 2, the residual stress of the thick steel plate 5 will be reduced.

Embodiment 4 FIG.
FIG. 5 is a side view showing the structure of the thick steel plate heat treatment apparatus according to Embodiment 4 of the present invention. In FIG. 5, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description of the duplicated components is omitted. In the fourth embodiment, when three induction heating devices 2 are used as in the second embodiment, the pressing roll 3 is opposed to the transport roll 4 in the immediate vicinity of the outlet side of the induction heating device 2 on the most upstream side. In addition, the pressing roll 3 is arranged opposite to the conveyance roll 4 in the immediate vicinity of the entry side and the exit side of each induction heating device 2 on the downstream side thereof.

  In addition, the distance between the pressing rolls 3 that sandwich the induction heating devices 2, in other words, the length of the induction heating device 2 is, for example, that the thickness of the thick steel plate 5 that is a product is 30 m. It is set to less than 1 m, which is the amount of each cut off. The reason is that the pressing roll 3 has an effect on a portion excluding the front end and the rear end of the thick steel plate 5, and the front end and the rear end may cause a heating failure. For this reason, it is desirable to make this defective heating part coincide with the cut-off part of the front and rear ends which is not normally a product. However, the thick steel plate 5 has extremely high rigidity, and the pressing force required for the pressing roll 3 becomes enormous at such a short distance. Therefore, the cutting distance of the leading and trailing ends is set within a range that is economically acceptable and pressed. It is effective to simplify the configuration of the roll 3. Therefore, the economical distance, that is, the length that can be used as the induction heating device 2 is limited to 2 m for a typical rolling length of 30 m.

  In the fourth embodiment, when three induction heating devices 2 are used, not only the pressing roll 3 is disposed after the most upstream induction heating device 2 but also each induction heating on the downstream side thereof. Since the pressing rolls 3 are arranged on the entry side and the exit side of the apparatus 2, when the thick steel plate 5 is deformed by the heating of the induction heating apparatus 2 on the most upstream side, the deformation is applied to the pressing roll on the exit side. 3, when the deformation of the thick steel plate 5 is not sufficiently corrected by the pressing roller 3 on the outlet side, and there is a risk of causing slippage of the plate, the thick steel plate is placed on each induction heating device 2 on the downstream side thereof. The deformation of the plate is corrected and the slip of the plate is prevented by the pressing roller 3 on the entry side before 5 enters, and the deformation is also caused when the thick steel plate 5 is deformed by the heat treatment by each induction heating device 2. Outside pressing Since the thick steel plate 5 is flattened by the correction by the tool 3, the target conveying speed is maintained, the heating time is constant, and the thick steel plate 5 is at the target temperature in the longitudinal direction. It will be heated.

  Moreover, whenever the thick steel plate 5 is heat-processed with each induction heating apparatus 2, the residual stress of the thick steel plate 5 will be reduced. In addition, since the influence of the deformation and slip of the steel plate due to the third heating is small depending on the target steel plate size and heating temperature, the front and back pressing rolls of the third induction heating device 2 can be omitted. is there.

Embodiment 5 FIG.
FIG. 6 is a side view showing the structure of the thick steel plate heat treatment apparatus according to Embodiment 5 of the present invention. In FIG. 6, the same components as those of the fourth embodiment are denoted by the same reference numerals as those of the fourth embodiment, and the description of the duplicated components is omitted. In the fifth embodiment, unlike the fourth embodiment, when the three induction heating devices 2 are used, the pressing roll 3 is conveyed to the nearest side of the entry side and the exit side of the induction heating device 2 on the most upstream side. It arrange | positions facing the roll 4, and it is made not to arrange | position the pressing roll 3 in the entrance side and exit side of the induction heating apparatus 2 downstream from it. In addition, in the example of FIG. 6, although the pressing roll is arrange | positioned at the entrance side and exit side of the induction heat apparatus of the most upstream side, you may arrange | position a pressing roll only to an exit side.

  This is because the effect of correcting the deformation of the plate and the prevention of the slip of the plate by the pressing roll 3 arranged in the immediate vicinity of the outlet side of the induction heating device 2 on the most upstream side is great. This is because it is considered that the pressing roll 3 does not have to be disposed on the entry side and the exit side. In addition, when it thinks that the effect of correction | amendment of a deformation | transformation of the board by the pressing roll 3 arrange | positioned in the immediate vicinity of the exit side of the induction heating apparatus 2 of the most upstream side and the prevention of a board slip is not enough, it is downstream from it. It goes without saying that the pressing roll 3 may be arranged on the exit side of the induction heating device 2 or on both the entrance side and the exit side.

Embodiment 6 FIG.
FIG. 7 is a side view showing the configuration of the heat treatment apparatus for thick steel plates according to Embodiment 6 of the present invention. In FIG. 7, the same components as those of the fourth embodiment are denoted by the same reference numerals as those of the fourth embodiment, and the description of the duplicated components is omitted. In the sixth embodiment, the three induction heating devices 2 are used as in the fifth embodiment, and the pressing roll 3 is opposed to the transport roll 4 against the entry side of the induction heating device 2 on the most upstream side. However, as a result, the pressing rolls 3 are arranged opposite to the conveying rolls 4 between the induction heating devices 2 adjacent to each other.
As described above, when the three induction heating devices 2 are used, the pressing rolls 3 are arranged between the induction heating devices 2 adjacent to each other. When a deformation occurs in the thick steel plate 5 due to heating, the deformation is corrected by the pressing roller 3 on the outgoing side, and before the thick steel plate 5 enters the induction heating device 2 on the downstream side, the deformation of the plate is corrected. It is intended to prevent slipping.

  Since the thick steel plate 5 is flattened in this way, the target conveyance speed is maintained, the heating time is constant, and the thick steel plate 5 is heated at the target temperature in the longitudinal direction. . Moreover, whenever the thick steel plate 5 is heat-processed with each induction heating apparatus 2, the residual stress of the thick steel plate 5 will be reduced.

Embodiment 7 FIG.
FIG. 8 is a side view showing the configuration of a heat treatment apparatus for thick steel plates according to Embodiment 7 of the present invention. In FIG. 8, the same components as those of the fourth embodiment are denoted by the same reference numerals as those of the fourth embodiment, and the description of the duplicated components is omitted. In the seventh embodiment, when the three induction heating devices 2 are used as in the fifth embodiment, the pressing rolls 3 are respectively placed in the immediate vicinity of the entrance side and the exit side of the induction heating device 2 on the most upstream side. In addition to being arranged facing the transport roll 4, the pressing roll 3 is also placed facing the transport roll 4 in the immediate vicinity of the entry side and the exit side of each induction heating device 2 downstream from it. It is.

  In the seventh embodiment, when three induction heating devices 2 are used, not only the pressing rolls 3 are arranged on the entry side and the exit side of the induction heating device 2 on the most upstream side, but also on the downstream side thereof. Since the pressing rolls 3 are also arranged on the entry side and the exit side of each induction heating device 2 on the side, first the hot-rolled and deformed thick steel plate 5 after water cooling is the most upstream induction heating. The pressing roll 2 installed in front of the device 2 prevents the slip of the plate and corrects the deformation of the thick steel plate 5 to flatten the thick steel plate 5 and then put it into the induction heating device 2.

  Next, when the thick steel plate 5 is deformed by the heating of the induction heating device 2 on the most upstream side, the deformation is corrected by the pressing roller 3 on the outlet side, and the thick steel plate 5 by the pressing roller 3 on the outlet side is corrected. When the deformation is not sufficiently corrected and there is a risk of causing slippage of the plate, the deformation of the plate is corrected by the pressing roll 3 on the entry side before the thick steel plate 5 enters the induction heating device 2 on the downstream side. In addition, the slip of the plate is prevented, and even when the thick steel plate 5 is deformed by the heat treatment by each induction heating device 2, the deformation is corrected by the pressing roller 3 on the outgoing side, so that the thick steel plate 5 is Since it is flattened, the target conveyance speed is maintained, the heating time is constant, and the thick steel plate 5 is heated at the target temperature in the longitudinal direction.

In addition, since there is a correction device on the downstream side, the third exit side pressing roll 3 may be omitted. Furthermore, depending on the target steel plate size and heating temperature, the pressing roll 3 on the outlet side of the second induction heating device 2 can be sufficiently corrected, so that the pressing on the entry side of the third induction heating device 2 is pressed. The roll 3 can also be omitted. Moreover, whenever the thick steel plate 5 is heat-processed with each induction heating apparatus 2, the residual stress of the thick steel plate 5 will be reduced.
In the first to seventh embodiments described above, a solenoid type is used as the induction heating device 2, but it goes without saying that the present invention can be implemented even if a transverse type is used.

Embodiment 8 FIG.
The inventors of the present invention use a steel plate having a plate thickness of 40 mm and a plate width of 2000 mm, heat-treat with a solenoid-type induction heating device provided between the conveyance rolls, and examine the following examination on the warp of the thick steel plate tip after the heat treatment. went. This will be described as an eighth embodiment.

  As shown in FIGS. 9 (A) to 9 (G), the pressing for pressing the thick steel plate 5 from the upper surface facing the transporting roll 4 above the transporting roll 4 on the entry side and the exit side of the induction heating device 2. After the roll 3 is placed and heated so that the surface temperature of the thick steel plate rises by 60 ° C., the pressing roll 3 is pressed against the thick steel plate 5 with a pressing force of 80000 N, and the warp of the thick steel plate tip on the exit side of the induction heating device 2 The height h was determined. Here, as shown in FIG. 10, the warp height h is a height measured from the surface of the thick steel plate when warp does not occur at the highest point of the warped thick steel plate.

  In FIG. 11, the relationship between arrangement | positioning of the pressing roll 3 shown to FIG. 9 (A)-(G), and curvature height h is shown. 9 (C), (D), (E), (F), and (G), the pressing roll 3 is opposed to the transport roll 4 above the transport roll 4 on the exit side of the induction heating device 1. Therefore, the height of the warp can be suppressed to 20 mm or less, and the thick steel plate 5 can be prevented from colliding with the transport roll 4 and the induction heating device 2.

  Even if the pressing roll 3 is arranged above the first conveying roll 4 from the induction heating device 2 as shown in FIGS. 9C and 9E, the pressing roll 3 can be removed from the induction heating devices 2 to 2 as shown in FIG. Even if it arrange | positions above the 2nd conveyance roll 4, the curvature of a thick steel plate can be suppressed. Note that the same effect can be obtained by disposing it above the third transport roll 4. Here, in the case where it is arranged above the second or third transport roll 4, if the tip of the thick steel plate passes through the heating device and then collides with the pressing roll 3 or rides on the pressing roll 3, You may install a guide roll etc. so that the front-end | tip of a thick steel plate may be pressed and guide | induced to the roll 3. FIG.

  When a plurality of induction heating devices 2 are provided and the distance between the induction heating devices 2 is increased, as shown in FIGS. A pressing roll 3 can be provided. Further, as shown in FIG. 9 (F), the pressing roll 3 does not necessarily have to be disposed immediately above the transport roll 4, and is disposed so that a pressing force is applied to the thick steel plate 5 by the pressing roll 3 and the transport roll 4. It only has to be. Further, as shown in FIG. 9E, when the pressing roll 3 is also provided on the entry side of the induction heating device 2, the thick steel plate 5 is placed on the upper side in the width direction on the entry side of the induction heating device 2 as shown in FIG. It is more effective when it is warped. On the other hand, in the case of FIGS. 9A and 9B where the pressing roll 3 is not above the transport roll 4 on the exit side of the induction heating device 2, the warp height exceeds 40 mm, and the thick steel plate 5 is transported by the transport roll 4. And the danger of collision with the induction heating device 2 is very high.

  In addition, when providing the several induction heating apparatus 2, if the pressing roll 3 is provided in the exit side of the induction heating apparatus 2 in the most upstream, the curvature of the thick steel plate 5 can be suppressed. The reason is that the most upstream induction heating device 2 has a large temperature rise when the thick steel plate 5 is heated, and when the temperature is 50 ° C. or higher, the thick steel plate 5 is likely to be warped. Since the induction heating device 2 other than the most upstream induction heating device 2 may also be heated with a large amount of temperature increase, the pressing roll 3 can be provided on the outlet side of the induction heating device 2.

  Further, the pressing force by the pressing roll 3 is constant because the plate width of the thick steel plate is fixed in the above examination, but it is necessary to appropriately change it according to the plate width. When the plate width is about 1000 mm or more, warpage occurs in the width direction and the longitudinal direction, so that a larger pressing force is required as the plate width becomes smaller. For example, when the plate width is 1000 mm or more and 1500 mm or less, a pressing force of 100000 N or more is required. is there. On the other hand, when the plate width is 3000 mm or more, a pressing force of about 20000 N is sufficient. Furthermore, the same result can be obtained even if a transverse type is used as the induction heating device 2.

Embodiment 9 FIG.
As a production line for thick steel plates, higher productivity can be achieved by providing a hot rolling mill, an accelerated cooling device, and a heat treatment device for thick steel plates according to the present invention as described above on the same line. A thick steel plate can be manufactured stably. FIG. 12 shows an example of the production line of the present invention. The slab 7 heated in the heating furnace 8 is rolled into the thick steel plate 5 by a hot rolling mill 10. After the hot rolling, the thick steel plate 5 is rapidly cooled by the accelerated cooling device 20 and heat treated by the heat treatment device 30 to give desired characteristics. The heat treatment apparatus 30 includes six induction heating apparatuses 2, and one pressing roll 3 is provided on the exit side of the most upstream induction heating apparatus 2 directly above the conveyance roll 4 and opposed to the conveyance roll 4. Has been placed.

  The thick steel plate 5 heat-treated by the induction heating device 2 is pressed by the pressing roll 3 with a pressing force corresponding to the plate width of the thick steel plate, so that it does not warp greatly and the downstream induction heating device 2 performs heat treatment without problems. Can receive. Since the heat treatment apparatus 30 has six induction heating apparatuses 2, a desired heat treatment can be performed in one pass.

Embodiment 10 FIG.
FIG. 13 shows another example of the production line of the present invention. The configuration of the production line is the same as in the case of FIG. 12, but the number of induction heating devices 2 of the heat treatment device 30 is three. As in the case of FIG. 12, one pressing roll 3 is disposed immediately above the conveyance roll 4 on the exit side of the most upstream induction heating device 2 so as to face the conveyance roll 4. In the heat treatment apparatus 30, since there are only three induction heating apparatuses 2, it is preferable to perform the heat treatment in a reverse pass. In the reverse pass, it is not always necessary to use the pressing roll 3 except for the first pass. In this case, the pressing force may be set to zero. 12 and 13, when a straightening device (hot leveler) is provided between the accelerated cooling device 20 and the heat treatment device 30 or on the downstream side of the heat treatment device 30, a thicker steel plate having higher flatness. Can be manufactured.

Example 1.
In Example 1 of the present invention, the thick steel plate 5 is bent back by the straightening device 1 using the thick steel plate heat treatment apparatus shown in FIG. Then, the pressing roll 3 was used to suppress the deformation of the thick steel plate 5 to eliminate the slip and maintain the target conveying speed, and the effect was examined. Here, the straightening device 1 for straightening the thick steel plate 5 has a total of three rolls, one upper and two lower.
The induction heating device 2 is a solenoid type having a frequency of 1500 Hz, has an opening of 200 mm × 200 mm, a length of 1000 mm, and a maximum output of 1 MW.
The pressing roll 3 has a roll diameter of 200 mm so that the rolling force can be changed.
The thick steel plate 5 has a thickness of 25 mm, a width of 100 mm, and a length of 2 m. The induction heating device drives the transport roll 4 at a constant speed from room temperature to a uniform temperature of 300 ° C. over the entire length. Heating was performed according to 2.

Further, as a comparative example, the thick steel plate 5 is bent back by the straightening device 1 for the thick steel plate having the same size as that of the embodiment, among the thick steel plate heat treatment devices shown in FIG. The straightened thick steel plate 5 was heat treated by the induction heating device 2 and the effect was examined. The other devices are all in the same conditions as in the embodiment except that there is no pressing roll.
FIG. 14 shows an example of the temperature distribution of the full length after heating in the comparative example in which the pressing roll 3 is not used. In the comparative example, the tip of the thick steel plate was warped upward by about 100 mm. When this plate was heated, the temperature rise at the tip was small. In addition, when the center of the length of the plate approaches the induction heating device, a slip occurs twice, and the conveyance speed becomes slow, so there is a portion where the temperature is high.

The temperature fluctuation shown in FIG. 14 is ΔT, and the result is shown in Table 1 as a comparative example.
Moreover, in the Example of this invention, the result of the temperature fluctuation | variation (DELTA) T at the time of changing the pressing force which is the pressing force of the pressing roll 3 in three steps was shown as the present invention 1-3 in the following Table 1.

  As can be seen from Table 1, the heating temperature is not constant in the comparative example in which the pressing roll is not used, whereas in the present invention using the pressing roll, the deviation of the temperature fluctuation ΔT is reduced by increasing the rolling force. You can see the effect.

Example 2
Using the production line of FIG. 12 or FIG. 13, a hot steel mill 10 produces a thick steel plate having a plate thickness of 12-40 mm and a plate width of 1500-4000 mm as shown in Table 2, and then reaches almost room temperature with the accelerated cooling device 20. Rapid cooling and heating to 300 ° C. by the most upstream induction heating device 2 of the heat treatment device 30, and the pressing force of the pressing roll 3 disposed above the transport roll 4 on the exit side of the most upstream induction heating device 2 are shown in Table 2. Thus, the presence or absence of collision between the thick steel plate 5 and the transport roll 4 or the induction heating device 2 was examined. In addition, although the case where the thick steel plate was passed through the heat treatment apparatus 30 by 3 passes using the production line of FIG. 13 was examined, in this case, the pressing roll 3 was used in the 1st pass. The induction heating device 2 is a solenoid type having a frequency of 1500 Hz, the opening of the coil is 200 mm (height) × 5000 mm (width), the length is 2000 mm, and the maximum output is 1 MW. The results are shown in Table 2.

  In the present invention examples (present inventions 4 to 6) in which the pressing roll 3 was used and the thick steel plate was pressed with an appropriate pressing force according to the plate width, the collision with the transport roll 4 and the induction heating device 2 did not occur at all. When the heat treatment was performed in the reverse pass using the production line in FIG. 13, the collision could be avoided by using the pressing roll 3 in the first pass. On the other hand, in the comparative examples (conventional examples 1 to 4) in which the pressing roll 3 was not used or the thick steel plate was pressed with a small pressing force even when it was used, a collision with the transport roll 4 and the induction heating device 2 occurred.

  DESCRIPTION OF SYMBOLS 1 Correction apparatus, 2 Induction heating apparatus, 2a Opening part of induction heating apparatus, 3 Pressing roll, 4 Conveyance roll, 5 Thick steel plate, 7 Opening part of induction heating apparatus, R Diameter of pressing roll.

Claims (11)

A plurality of transport rolls for transporting thick steel plates;
Having at least one induction heating device for heating the thick steel plate,
The induction heating device is disposed between the adjacent transport rolls, and
A pressing roll for pressing the thick steel plate from the upper surface has a predetermined rolling force for preventing deformation or slippage of the plate on the outlet side of the induction heating device at the most upstream of the induction heating devices. At least one is provided,
A heat treatment apparatus for a thick steel plate, wherein at least the most pressing pressing roll among the pressing rolls is disposed above the conveying roll on the outlet side of the induction heating device so as to face the conveying roll.   The apparatus for heat-treating a thick steel plate according to claim 1, wherein at least one pressing roll for pressing the thick steel plate from the upper surface is provided on the inlet side of the induction heating device in the uppermost stream. In the heat treatment apparatus for a thick steel plate provided on the line with an induction heating device for heat-treating the hot-rolled thick steel plate and a straightening device for correcting deformation of the plate heat-treated by the induction heating device,
There are a plurality of the induction heating devices, and a pressing roll having a predetermined rolling force for preventing deformation or slippage of the plate on at least the induction side of the induction heating device on the most upstream side or the entry side and the exit side. A heat treatment apparatus for thick steel plates, characterized in that each is provided.   The heat treatment apparatus for thick steel plates according to claim 3, wherein the pressing rolls are provided between induction heating apparatuses adjacent to each other.   The heat treatment apparatus for a thick steel plate according to any one of claims 1 to 4, wherein a roll diameter of the pressing roll is larger than about ½ of a size of an opening of the induction heating apparatus.   The said pressing roll is a drive-type roll which has a rotational force which can suppress the speed change by the electromagnetic attraction | suction of the said induction heating apparatus, and a repulsive force, The one of Claims 1-5 characterized by the above-mentioned. Heat treatment equipment for thick steel plates.   The heat processing method of the thick steel plate which prevents the deformation | transformation or slip of the board heat-processed with the induction heating apparatus using the heat processing apparatus in any one of the said Claims 1-6.   A method for producing a thick steel plate, comprising the step of pressing the thick steel plate from above using the heat treatment apparatus according to any one of claims 1 to 6.   A thick steel plate production line comprising a hot rolling mill, an accelerated cooling device, and the thick steel plate heat treatment device according to claim 1 or 2 on the same line.   The thick steel plate production line according to claim 9, wherein a straightening device is provided between the accelerated cooling device and the heat treatment device.   The thick steel plate production line according to claim 9 or 10, further comprising a straightening device downstream of the heat treatment device.

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