JP2005226106A - Method and device for heat-treating thick steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a steel plate having excellent flatness and desired characteristics online without degrading the productivity. <P>SOLUTION: A thick steel plate 1 is press-straightened and flattened by providing a press-straightening device 4 on the inlet side of an induction heating device 8. The flattened thick steel plate 1 is fed to the induction heating device 8 while maintaining the target carrying speed. The thick steel plate is heated at the target temperature in the longitudinal direction while maintaining the predetermined heating time by the induction heating device 8, and steel having less temperature irregularity and excellent material can be manufactured consistently. Further, the flattened thick steel plate 1 is fed to the induction heating device 8, and breakage of the induction heating device 8 by the thick steel plate 1 before straightening having a large warp caused by improper operation of a carrying roll 3 can be prevented. Thus, the distance between the thick steel plate 1 and the induction heating device 8 can be reduced, and the heating efficiency of the induction heating device 8 can be enhanced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 sheet for material adjustment, and more specifically, an induction heating apparatus that continuously heats a hot-rolled steel sheet. The present invention relates to an article whose shape is corrected on the entry side and is heated to a uniform temperature from the front end portion to the rear end portion of the thick steel plate.

Since heat treatment of thick steel plates is often performed in a batch-type reheating furnace and is inferior in productivity, Patent Document 1 uses a heating device installed on a line after quenching or accelerated cooling after hot rolling. A method of performing a tempering process has been proposed.
Further, Patent Document 2 proposes a method in which a thick steel plate having a small amount of residual stress is efficiently heat-treated by heat-treating the thick steel plate with an induction heating apparatus installed on-line after hot rolling. ing.
Japanese Patent No. 3015923 (first page, FIG. 2) Japanese Patent Laying-Open No. 2003-13133 (first page, FIG. 1)

However, the heat treatment method for thick steel sheets described in Patent Document 1 does not describe any conditions for uniformly heating the steel sheets online with good productivity and conditions for obtaining excellent flatness of the steel sheets.
Moreover, although the heat processing method of the thick steel plate described in patent document 2 heat-treats a thick steel plate with the induction heating apparatus installed on-line, this presupposes that a steel plate is heated uniformly and is a shape. Correction is performed by a hot leveler.
However, in the correction of the shape using a hot leveler, a sufficiently satisfactory flatness cannot be obtained for a thick steel plate having a thickness of 30 to 40 mm, and the normal size generally includes a thin material. As for the thick steel plate, the front and rear ends have a limit to obtain sufficient flatness.

In addition, since the space through which the thick plate can pass through the induction heating device is limited, it is necessary to correct the deformation of the plate so as not to destroy the induction heating device. In addition, there is an idea to design an induction heating device with sufficient margin by assuming the warp height of the steel plate in advance, but the equipment becomes large and the equipment cost increases, and the distance between the material to be heated and the induction heating coil is large. As it is, the heating efficiency is lowered and the productivity is deteriorated.
Furthermore, if the distance from the induction heating coil is different in the longitudinal direction of the steel sheet due to the poor flatness of the steel sheet, heating temperature unevenness occurs, and from the viewpoint of causing variations in the material of the steel sheet. It is desirable to correct the shape of the steel plate as flat as possible.
Moreover, even if the steel plate is flattened before the induction heating device is charged, the steel plate may be deformed by the heating of the induction heating device.
The present invention has been made to solve such a problem, and an object of the present invention is to manufacture a steel sheet having excellent flatness and desired characteristics on-line without reducing productivity.

  A steel plate heat treatment apparatus according to the present invention is a steel plate heat treatment apparatus provided on a line with an induction heating device for heat-treating a hot-rolled thick steel plate, and includes a press straightening device on the entry side of the induction heating device. It is characterized by that.

  In the thick steel plate heat treatment apparatus of the present invention, there are a plurality of the induction heating devices, and the press straightening device is provided on the entry side of at least the most upstream induction heating device. .

  Furthermore, in the heat treatment apparatus for thick steel plates of the present invention, the induction heating device is a plurality of units, and the press straightening device is provided on the entry side of the most upstream side, and between the induction heating devices adjacent to each other. Each of the press correction devices is provided.

  In the thick steel plate heat treatment apparatus of the present invention, there are a plurality of the induction heating devices, and the press correction device is provided on the entrance side of the induction heating device on the most upstream side of the induction heating devices. A pinch roll having a predetermined reduction force for preventing deformation of the plate or slippage of the plate is provided on the exit side so as to face the conveyance roll.

  Furthermore, in the heat treatment apparatus for thick steel plates of the present invention, there are a plurality of the induction heating devices, of which the press straightening device is provided on the entrance side of the induction heating device on the most upstream side, and the remaining induction heating devices A pinch roll having a predetermined reduction force for preventing deformation of the plate or slippage of the plate is provided on the entry side and the exit side so as to face the conveyance roll.

  Moreover, in the heat treatment apparatus for thick steel plates according to the present invention, the press straightening device includes an upper press die having an integral structure, and independent individual pieces that are opposed to the upper press die and are provided between a plurality of conveying rolls. It consists of a lower press die.

  In the thick steel plate heat treatment apparatus of the present invention, the roll diameter of the pinch roll is larger than about ½ of the size of the opening of the induction heating apparatus.

  In the thick steel plate heat treatment apparatus according to the present invention, the pinch roll is a drive type roll having a rotational force capable of suppressing a speed change due to electromagnetic attraction and repulsion of the induction heating device. Features.

  Furthermore, the heat treatment method for a thick steel plate according to the present invention is such that the thick steel plate is heat treated by an induction heating device using the heat treatment device for the thick steel plate.

As described above, according to the present invention, since the thick steel plate is flattened by the press straightening device provided on the entrance side of the induction heating device and inserted into the induction heating device, the distance between the steel plate and the induction heating coil is constant. Thus, uniform heating with less uneven heating temperature can be performed.
In addition, since it is possible to prevent the slip during the steel plate conveyance caused by the warpage of the steel plate, the target conveyance speed is maintained and sent to the induction heating device, the heating time by the induction heating device becomes constant, and the thick steel plate is There is an effect that it is possible to stably manufacture a good steel material that is heated at a target heating temperature in the longitudinal direction and has little temperature unevenness.
Furthermore, since it is possible to prevent the steel plate before straightening having a large warp from destroying the induction heating device, the distance between the steel plate and the induction heating device can be reduced, and the heating efficiency of the induction heating device can be reduced. Has the effect of improving.

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 thick steel plate heat treatment apparatus according to the first embodiment of the present invention is installed after the straightening leveler 2 that corrects the deformation of the plate after hot-rolling and cooling the thick steel plate 1 and the straightening leveler 2. The basic configuration includes a press straightening device 4 that corrects the warp of the front and rear end portions of the thick steel plate and a single induction heating device 8 that performs a rapid heating process on the thick steel plate 1. A conveyance roller 3 conveys the thick steel plate 1 and 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 leveler 2 includes a plurality of upper and lower rolls, and corrects the shape defect of the thick steel plate 5 that occurs during rolling such as warping or accelerated cooling by repeated bending.
The press straightening device 4 is provided with an upper press die 5 of an integral structure that operates in the vertical direction, and is provided between the three transport rolls 3 so as to face the upper press die 5 and individually in the vertical direction. The lower press die 6 that operates in the same manner, and the upper press die 5 and the lower press die 6 are provided on the outlet side of the lower press die 6 and operate in the vertical direction. The induction heating device 2 is of a solenoid type.

Next, the operation of the thick steel plate heat treatment apparatus according to Embodiment 1 of the present invention will be described.
When the thickness of the thick steel plate 1 that is the material to be heated after hot rolling and water cooling is more than 30 mm, sufficient flatness may not be obtained even if it is corrected with the leveler 2 for correction. Further, with respect to a thin object, it is impossible to correct the shape with the correction leveler 2 alone against the upper and lower end warping shorter than between the roll pitches of the correction leveler 2.
Thus, if the upper warp of the thick steel plate 5 is heated by the heating device 8 without being corrected by the correcting leveler 2, the mass of the thick steel plate 5 to be heated is increased by 1 / cos θ, Accordingly, heating is performed lower than the target temperature. Further, when the thick steel plate 5 is deformed downward, the steel plate 5 collides with the transport roll 5 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.

  Therefore, in the present invention, when the thick steel plate 1 that has been straightened by the straightening leveler 2 enters the press straightening device 4, first, the steel plate positioning device 7 is actuated upward, and the upper press die 5 and the lower press die 6. In order to close the outlet opening, the tip of the thick steel plate 1 abuts against the steel plate positioning device 7, the movement of the thick steel plate 1 is stopped, and the thick steel plate 1 is positioned in the press straightening device 4.

After that, the upper press die 5 is operated downward and the two lower press dies 6 are operated upward so that the front and rear ends of the thick steel plate 1 are pressed and the thick steel plate 1 is flattened. Thereafter, the steel plate positioning device 7 operates downward, the outlet openings of the upper press die 5 and the lower press die 6 are opened, and at the same time the upper press die 5 operates upward and two lower The press die 6 operates downward.
Then, since the flattened thick steel plate 1 is kept at a constant distance from the induction heating coil and is sent to the induction heating device 8 while maintaining the target conveying speed, the heating time by the induction heating device 8 is also constant. Thus, the thick steel plate 1 is heated at a target temperature in the longitudinal direction, and a good thick steel plate 1 having a material with little temperature unevenness can be stably manufactured.

Further, a steel plate positioning device 7 that operates in the vertical direction is provided on the exit side of the press straightening device 4, that is, between the press straightening device 4 and the induction heating device 8, and the steel plate positioning device 7 positions the thick steel plate 1; Since the thick steel plate 1 flattened after correcting the warpage of the thick steel plate 1 by the press straightening device 4 is sent to the induction heating device 8, the thick steel plate before correction having a large warp due to a malfunction of the transport roll 3. 1 can prevent the induction heating device 8 from being destroyed, so that the distance between the thick steel plate 1 and the induction heating device 8 can be reduced, and the heating efficiency of the induction heating device 8 can be improved.
Furthermore, since the two lower press molds 6 provided independently between the three transport rolls 3 operate in the vertical direction, the lower press molds 6 are set higher than the level of the transport roll 3. Thus, when the warpage of the thick steel plate 1 is press-corrected, it is possible to avoid applying an unnecessary load to the transport roll.

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 8 are used.
In the second embodiment, when three induction heating devices 8 are used, the press straightening device 4 is arranged only on the entrance side of the induction heating device 8 on the most upstream side.

This is because the effect of the press correction of the warpage of the thick steel plate 1 by the press correction device 4 arranged on the entry side of the induction heating device 8 on the most upstream side is great, and therefore on the entry side of the induction heating device 8 on the downstream side. This is because it is considered that the press straightening device 4 need not be arranged.
In addition, when it thinks that the effect of the press correction of the curvature of the thick steel plate 1 by the press correction apparatus 4 arrange | positioned at the entrance side of the induction heating apparatus 8 of the most upstream side is not enough, the induction heating apparatus 8 downstream from it Needless to say, the press correction device 4 may be arranged on the entrance side of the.

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.
In the third embodiment, the three induction heating devices 8 are used as in the second embodiment. The press straightening devices 4 are arranged on the entrance side of the most upstream induction heating device 8 and are mutually connected. The press straightening device 4 is arranged between the adjacent induction heating devices 8.

As described above, when three induction heating devices 8 are used, the press straightening devices 4 are arranged between the induction heating devices 8 adjacent to each other. 5, when the deformation occurs, the deformation is corrected by the press correction device 4 arranged on the outlet side, and the steel plate 1 is flattened before the thick steel plate 1 enters the induction heating device 8 on the downstream side. It is a thing.
In this way, since the flattened thick steel plate 1 is sent to each induction heating device 8 while maintaining the target conveying speed, the heating time by each induction heating device 8 becomes constant and the thick steel plate 1 has its longitudinal length. It will be heated at the target temperature in the direction.
Moreover, whenever the thick steel plate 1 is heat-processed with each induction heating apparatus 8, the residual stress of the thick steel plate 1 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 3 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 the three induction heating devices 8 are used as in the second embodiment, not only the press straightening device 4 is disposed on the entrance side of the induction heating device 8 on the most upstream side. A pinch roll 11 having a predetermined reduction force with respect to the thick steel plate 5 is arranged opposite to the transport roll 3 on the exit side of each induction heating device 8.
The rolling force of the pinch roll 11 is set to such an extent that the thick steel plate 1 can correct the deformation of the thick steel plate when passing between the pinch roll 11 and the transport roll 3.

In the fourth embodiment, when three induction heating devices 8 are used, not only the press straightening device 4 is disposed on the entrance side of the induction heating device 8 on the most upstream side, but also each induction heating device 8. Since the pinch roll 11 is arranged on the outlet side of the steel plate, even if the thick steel plate 1 flattened by the press straightening device 4 is sent to the induction heating device 8 on the most upstream side, each induction heating device 8 When the thick steel plate 1 is deformed by heating, the flat steel plate 1 is flattened by correcting the deformation with the pinch roll 11 on the outlet side, so that the flattened thick steel plate 1 is brought into the target conveyance speed. Therefore, the heating time by each induction heating device 8 becomes constant, and the thick steel plate 1 is heated at a target temperature in the longitudinal direction.
Moreover, whenever the thick steel plate 1 is heat-processed with each induction heating apparatus 8, the residual stress of the thick steel plate 1 will be reduced.
Here, the pinch roll 11 was installed in place of the press straightening device 4 because it was considered that a high-temperature steel plate immediately after heating could be sufficiently corrected even with the rolling force of the pinch roll 11.
In addition, depending on the size and heating temperature of the target steel plate, the influence of the deformation and slip of the steel plate due to the third heating is small, and therefore the output side pinch roll 11 of the third induction heating device 8 is omitted. Is also possible.

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 configurations as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description of the overlapping configurations is omitted.
In the fifth embodiment, when three induction heating devices 8 are used, the press straightening device 4 is arranged on the entry side of the induction heating device 8 on the most upstream side and on the exit side of the induction heating device 8. Not only the pinch roll 11 is disposed, but the pinch roll 11 is disposed opposite to the transport roll 3 on the entry side and the exit side of each induction heating device 8 on the downstream side thereof.

In the fifth embodiment, when three induction heating devices 8 are used, the press straightening device 4 is arranged on the entrance side of the induction heating device 8 on the most upstream side and the exit side of the induction heating device 8 is used. In addition to the pinch rolls 11 being arranged on the upstream side, the pinch rolls 11 are arranged on the entry side and the exit side of each induction heating device 8 on the downstream side, so that the induction heating device 8 on the most upstream side is pressed. Even if the thick steel plate 1 flattened by the straightening device 4 is sent, when the thick steel plate 1 is deformed by the heating of the induction heating device 8, the deformation is corrected by the outgoing pinch roll 11, When the deformation of the thick steel plate 1 by the outlet pinch roll 11 is not sufficiently corrected, the deformation of the plate is corrected by the inlet pinch roll 11 of each induction heating device 8 on the downstream side thereof, and each induction heating device 8 for heat treatment Ri is obtained so as to correct the deformed steel plate 1 is the exit-side pinch over rolls that deform when produced.
Depending on the size and heating temperature of the target steel plate, the influence of the deformation and slip of the steel plate due to the second and subsequent heating is small, so that the pinch rolls 11 on the entry side and the exit side of the third induction heating device are used. Can be omitted.

As a result, the flattened thick steel plate 1 is sent to each induction heating device 8 while maintaining the target conveyance speed, so that the heating time by each induction heating device 8 is also constant and the thick steel plate 1 is in its longitudinal direction. It will be heated at the target temperature.
Moreover, whenever the thick steel plate 1 is heat-processed with each induction heating apparatus 8, the residual stress of the thick steel plate 1 will be reduced.
In the first to fifth embodiments described above, a solenoid type is used as the induction heating device 8, but it goes without saying that the present invention can be implemented even if a transverse type is used.

In the embodiment of the present invention, as the heat treatment apparatus for the thick steel plate shown in FIG. 1, the effect is obtained when the press straightening apparatus 4 is installed when heat treatment is performed by the straightening leveler 2 and one solenoid type induction heating apparatus 8. I investigated.
Moreover, the case where the press correction apparatus was not used was made into the comparative example, and it compared with the case of this invention using the press correction apparatus.
After the hot-rolled and water-cooled thick steel plate 1 is corrected by the straightening leveler 2, the thick steel plate 1 is conveyed to the press straightening device 4 on the conveying roll 3.
The thick steel plate 1 was 40 mm thick, 100 mm wide and 3 m long.
The straightening leveler 2 straightens the plate by bending back with three rolls having a roll diameter of 200 mm.

The upper press die 5 of the press straightening device 4 has an integral structure and is operated in the vertical direction by a hydraulic cylinder (not shown), and the lower press die 6 is provided separately between the transport rolls 3 and independently hydraulic. Operates in a vertical direction with a cylinder (not shown).
The upper press die 5 has a length of 600 mm and a width of 200 mm, and the lower press die 6 has a length of 160 mm and a width of 200 mm.
A steel plate positioning device 7 is provided on the exit side of the press straightening device 4, and this steel plate positioning device 7 is operated in the vertical direction by a hydraulic cylinder (not shown).
Reference numeral 8 denotes an induction heating device, which is a solenoid type having a frequency of 1500 Hz, has an opening of 200 mm × 200 mm, a length of 700 mm, and a maximum output of 1 MW.

In such a thick steel plate heat treatment apparatus, the upper press die 5 and the lower press die 6 are operated upward and downward, respectively, in order to receive the thick steel plate 1 conveyed from the leveling leveler 2 into the press straightening device 4. And the interval between the upper press die 5 and the lower press die 6 is widened.
At this time, in order to stop the tip of the thick steel plate 1 in the press straightening device 4, the steel plate positioning device 7 is operated upward.
Thereafter, the thick steel plate 1 is received in the press straightening device 4, and the upper press die 5 and the lower press die 6 are operated downward and upward, respectively, to correct warpage and waves of the thick steel plate 1. When correction is insufficient by one press correction, after the steel plate positioning device 7 is operated downward, the position of the thick steel plate 1 is changed by the inching movement of the transport roll 2, and press correction is performed again.

After straightening by the press straightening device 4, the thick steel plate 1 is transported to the induction heating device 8 by the transport roll 2, and is continuously heated by the induction heating device 8 with the target temperature set to a uniform temperature of 300 ° C. over the entire length.
In addition, since the upper and lower press dies 5, 6 are exposed to the radiant heat of the high-temperature thick steel plate 1 and the temperature rises, it is desirable to take heat resistance / cooling means.
In the case of the comparative example that does not use the press straightening device 4, the temperature distribution of the entire length of the thick steel plate 1 after heating is as shown in FIG. 7, and in this comparative example, the tip portion was warped upward by about 100 mm. . When this thick steel plate was heated, the temperature rise at the tip was small. The temperature variation in FIG. 7 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 of the press correction apparatus 4 in three steps was shown as the present invention 1-3 in the following Table 1.

  As can be seen from Table 1, in the comparative example in which the press straightening device 4 is not used, the heating temperature is not constant in the longitudinal direction, whereas in the present invention using the press straightening device, the press straightening force is increased. The temperature fluctuation ΔT is reduced, and the effect can be seen.

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 graph which shows the temperature distribution of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thick steel plate, 2 Leveler for correction, 3 Conveying roll, 4 Press straightening device, 5 Upper press die, 6 Lower press die, 7 Steel plate positioning device, 8 Induction heating device.

Claims (9)

In the heat treatment apparatus for a thick steel plate provided with an induction heating device on the line for heat treating the hot-rolled thick steel plate,
A heat treatment apparatus for a thick steel plate, comprising a press straightening device on the entrance side of the induction heating device.   2. The heat treatment apparatus for thick steel plates according to claim 1, wherein the induction heating apparatus includes a plurality of induction heating apparatuses, and the press straightening apparatus is provided on at least the most upstream induction heating apparatus.   There are a plurality of the induction heating devices, and the press correction device is provided on the entrance side of the induction heating device on the most upstream side, and the press correction devices are provided between the induction heating devices adjacent to each other. The heat treatment apparatus for thick steel plates according to claim 1.   There are a plurality of induction heating devices, and the press straightening device is provided on the entry side of the induction heating device on the most upstream side of the induction heating device, and deformation or slippage of the plate is prevented on the exit side of each induction heating device. 2. A heat treatment apparatus for a thick steel plate according to claim 1, wherein a pinch roll having a predetermined rolling force is provided so as to face the conveying roll.   There are a plurality of induction heating devices, of which the press straightening device is provided on the entry side of the induction heating device on the most upstream side, and the deformation of the plate or the slip of the plate on the entry side and the exit side of the remaining induction heating device 2. A heat treatment apparatus for thick steel plates according to claim 1, wherein a pinch roll having a predetermined rolling force for preventing the occurrence of the trouble is provided so as to face the conveying roll.   The press straightening device includes an upper press die having an integral structure, and an independent individual lower press die provided between a plurality of conveying rolls so as to face the upper press die. The heat processing apparatus of the thick steel plate in any one of claim | item 1 -5.   The steel plate heat treatment apparatus according to any one of claims 4 to 6, wherein a roll diameter of the pinch roll is larger than about ½ of a size of an opening of the induction heating device.   The said pinch 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 any one of Claims 4-7 characterized by the above-mentioned. Heat treatment equipment for thick steel plates. A heat treatment method for a thick steel plate, wherein the thick steel plate is heat treated by an induction heating device using the thick steel plate heat treatment device according to any one of claims 1 to 8.

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