JP2520526B2 - Induction heating furnace for directional magnetic steel slab - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating furnace provided in a hot rolling line for grain-oriented electrical steel slabs.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets have excellent magnetic properties such as high magnetic flux density and low iron loss, and are widely used as core materials for transformers and the like. In the manufacturing process, an inhibitor such as MnS or AlN that controls the crystal grain direction is used in order to obtain secondary recrystallization highly integrated in the [110] <001> orientation. In order for the inhibitor to have the intended effect properly, it is necessary to sufficiently dissociate and dissolve the inhibitor during slab heating prior to hot rolling. Further, it is important that the slab is hot-rolled under appropriate conditions, cooled, and the inhibitor is finely and uniformly dispersed and precipitated. The slab is heated at a high temperature of, for example, 1300 ° C. or higher to dissociate and solidify the inhibitor.

The above high temperature heating is disclosed, for example, in Japanese Patent Laid-Open Nos. 61-6994 and 61-69927. In the high temperature heating methods disclosed in these publications, the slab is preheated to about 1250 ° C. in a gas combustion type heating furnace, and the subsequent high temperature heating is performed in a short time in an induction heating furnace controlled to an inert atmosphere.

The induction heating furnace for performing the high temperature heating is provided along the hot rolling line. The induction heating furnace includes a slab tilting device, a slab lifting support device, and a slab upper support device, and supports the slab so that its upper and lower surfaces are vertical to heat the slab. The slab tilting device turns the slab 90 degrees to take a vertical posture. The slab lifting support device supports the lower slab side surface from below. Further, the slab upper support device is provided with a plurality of support shafts arranged along the furnace longitudinal direction. The support shaft can go up and down through the ceiling wall of the furnace body and presses the side surface of the upper slab. Since the slab is flat, it is prone to collapse, but since it is supported from above and below as described above, it does not collapse in the furnace during heating.

The slab is loaded into the induction heating furnace as follows. Since the slab conveyed along the hot rolling line has a horizontal posture (the upper and lower surfaces of the slab are horizontal), first, the slab is rotated 90 degrees by the slab tilting device to be in a vertical posture. Then, the slab in the vertical position is received by the slab lifting / lowering support device, pushed up and loaded into the induction heating furnace. If the slab is supported only by the slab tilting device and the slab lifting / lowering device until the slab is rotated 90 degrees and loaded into the induction heating furnace, the support becomes unstable and the slab may tip over. Therefore, a fall prevention device is provided below the induction heating furnace. For example, Jitsuko Sho 52-
In the fall prevention device of Japanese Patent No. 56335, a fall prevention plate that can move forward and backward toward the slab surface is arranged below the furnace body. Further, the fall prevention device disclosed in Japanese Utility Model Publication No. 52-56336 is
A presser roller that can move forward and backward toward the slab surface is provided directly below the furnace body.

Further, since the width of the furnace chamber is narrow, it is necessary to adjust the charging position in the slab thickness direction. In the induction heating furnaces described in both of the above publications, the slab receiving member (claw) and its driving device are provided on the carriage. Then, the carriage is moved back and forth to adjust the slab charging position.

[0007]

In the above-mentioned conventional induction heating furnace, the tilting device, the tilting device driving device, the holding plate and the holding plate driving device are mounted on the carriage, and the carriage on which these devices are mounted is mounted. Had been moved back and forth with a hydraulic cylinder. Therefore, the entire charging device is large and expensive.

Further, since the carriage is moved back and forth, the charging position in the slab width direction cannot be finely adjusted. Therefore, it was not possible to accurately position the slab and load it into the furnace. If the charging position is incorrect, there is a risk that the slab with a particularly warped slab may hit the furnace wall and damage the furnace wall, and the slab cannot be heated uniformly.

The present invention aims to reduce the size and cost of a slab charging device in an induction heating furnace for grain-oriented electrical steel slabs. Furthermore, the present invention is intended to improve the accuracy of slab charging positioning and to uniformly heat the slab.

[0010]

An induction heating furnace for grain-oriented electrical steel slabs according to the first aspect of the present invention is a furnace for heating a slab by supporting it so that the side surfaces of the slab are horizontal.
The slab tilting device that turns around, the slab lifting support device that supports the lower slab side surface from below, and the slab lifting support device that is arranged along the furnace longitudinal direction and penetrates the furnace ceiling wall to hold the upper slab side surface And a slab upper supporting device having a plurality of supporting shafts. The slab tilting device is rotatable between a horizontal position and a vertical position, and has a plurality of tilting frames arranged along the furnace longitudinal direction, and tilting frames respectively provided to the tilting devices. Rotating device, movable frame attached to each tilting frame so as to be able to advance and retreat in the slab thickness direction, movable frame advancing and retracting device attached to each tilting frame, and guide frame fixed to each movable frame And a slab receiving member which is attached to each guide frame so as to be able to move up and down, and a slab receiving member elevating device which is attached to each guide frame.

The number of tilting frames depends on the length of the slab, but is about 4 to 8. A hydraulic cylinder is used as the tilting frame driving device and the movable frame advancing / retreating device.

The induction heating furnace for directional electromagnetic steel slabs according to the second aspect of the present invention further comprises a device for detecting the advancing / retreating distance of the movable frame in the heating furnace, and the advancing / retreating with respect to the upper and lower surfaces of the slab in the vertical posture, A plurality of slab press plates arranged along the furnace longitudinal direction below the bottom of the furnace, slab press plate advancing and retracting devices respectively provided on each slab press plate, and a device for detecting the advancing and retracting distance of each slab press plate, respectively. A loading position control device for determining the loading position in the slab width direction based on signals from the movable frame advancing / retreating distance detecting device and the slab presser plate advancing / retreating distance detecting device and controlling the movable frame advancing / retreating device and the slab presser plate advancing / retreating device. Is equipped with.

The number of slab holding plates depends on the length of the slab, but is about 2 to 5. A hydraulic cylinder is used as the slab presser plate advancing / retreating device. Further, as the advancing / retreating distance detecting device of the movable frame and the advancing / retreating distance detecting device of the slab presser plate, a rack / gear mechanism, a magnetic scale or the like for detecting the displacement of the rod of the hydraulic cylinder advancing / retreating the movable frame or the slab presser plate is used.

[0014]

Operation: The slab is placed inside the furnace as follows.
The slab receiving member of the slab tilting device is standing by in a horizontal posture. When the slab is conveyed in a horizontal posture and stopped at a predetermined position, the tilting frame is turned 90 degrees so that the slab receiving member picks up the slab, and the slab and the slab receiving member are placed in a vertical posture. Then, the movable frame is moved forward until the width center of the slab reaches the center of the furnace chamber width. Then, the slab is sandwiched between the slab elevating support device and the support shaft, the slab elevating support device and the support shaft are raised synchronously, and the slab is loaded into the furnace.

To discharge the slab out of the furnace, the reverse operation to the above operation is performed.

According to the second aspect of the invention, when the slab is loaded into the furnace, the slab in a vertical posture is sandwiched between the slab receiving member and the slab holding plate, and the slab position and the slab holding position are determined from the distance between the movable frame and the slab holding plate. Ask for warpage. Then, the movable frame and the slab holding plate are moved forward and backward so that the width center of the warped slab comes to the furnace chamber width center.

[0017]

EXAMPLE FIG. 1 schematically shows a structural example of a hot rolling facility equipped with an induction heating furnace according to the present invention. As shown in the drawing, the hot rolling facility comprises a gas combustion type heating furnace 11, an induction heating furnace 12, a rough rolling mill 61, and a finishing rolling mill train 63 which are sequentially arranged along a hot rolling line L.

The induction heating furnace 12 is provided with a heating coil 19 along the outer peripheral surface of the furnace body 13. Further, in the induction heating furnace 12, a side surface of the slab 1 is horizontal, that is, a slab tilting device 21 that turns in a vertical posture, a slab lifting support device 51 that supports the slab 1 in the furnace in a vertical posture, and the slab 1. Is provided with a slab upper support device 55 for supporting by pressing from above.

Roller table 6 along the rolling line L
5 are provided. The roller table 65 is rotated by a drive motor 66 and conveys the slab 1 in the longitudinal direction thereof. The controller 67 controls the drive motor 66,
Stop the slab 1 in place.

FIG. 2 shows the slab tilting device 21 and the slab lifting support device 51 arranged below the induction heating furnace.

As shown in the drawing, the slab tilting device 21 is provided adjacent to the hot rolling line L. In the slab tilting device 21, six tilting frames 22 each having a lever 25 are arranged along the furnace longitudinal direction. A rotating shaft 26 is fixed to a fulcrum of the lever 25, and the tilting frame 22 is supported by a bearing (not shown) via the rotating shaft 26. The rear end of the lever 25 is connected to a rod 32 of a hydraulic cylinder 31 that is swingably attached to a frame 28. A movable frame 35 is attached to the tilting frame 22 so that a roller 36 fits in a guide groove 23 of the tilting frame 22. Tilt frame 2
The movable frame 35 is connected to a rod 39 of a hydraulic cylinder 38 that is swingably attached to the second frame 2. The hydraulic cylinder 38 includes a movable frame displacement detector 40 for detecting the displacement of the rod 39, that is, the moving distance of the movable frame 35.
Is attached. A claw (slab receiving member) 43 is attached to a guide frame 41 fixed to the movable frame 35 so as to be movable along the guide frame 41. In this embodiment, the number of claws 43 is 6, as shown in FIG. The tip of the claw 43 is connected to a rod 47 of a hydraulic cylinder 46 that is swingably attached to the guide frame 41.

The slab elevating / lowering support device 51 is disposed below the furnace chamber 16 and includes a hearth 52 and an electric winch 53 for elevating the hearth 52. The hearth 52 is inserted into the furnace chamber 16 by driving the electric winch 53.

The slab upper support device 55 includes a plurality of support shafts 5.
6, and the support shafts 56 respectively penetrate through the through holes 15 provided in the ceiling wall 14 of the furnace body 13. An air cylinder 58 is attached to the upper end of the support shaft 56, and the air cylinder 58 acts to push the support shaft 56 downward. The support shaft 56 of the slab upper support device 55 can be lowered until the shaft lower end 57 reaches below the furnace bottom surface 17 as shown in the figure.

A slab pressing device 71 is provided at the bottom of the furnace. That is, the guide cylinder 73 is fixed to the support frame 72 attached to the bottom of the furnace. Guide tube 7
A slab presser plate 74 is inserted in 3 so as to be movable back and forth.
In this embodiment, the number of slab pressing plates 74 is three as shown in FIG. A rod 77 of a hydraulic cylinder 76 is connected to the slab holding plate 74. A displacement detector 78 for detecting the advance / retreat distance of the slab pressing plate 74 is attached to the hydraulic cylinder 76.

The detection signals from the displacement detector 40 of the movable frame and the displacement detector 78 of the slab holding plate are input to the controller 81. The control device 81 determines the position and the warpage δ (see FIG. 3) of the slab 1 based on the detection signal. Then, an operation signal is output to the hydraulic cylinder 38 of the movable frame 35 and the hydraulic cylinder 76 of the slab holding plate 74 so that the width center of the warped slab 1 comes to the furnace chamber width center.

Here, a method for charging the slab 1 into the furnace in the induction heating furnace 12 configured as described above will be described.

As shown in FIG. 2, the slab 1 is conveyed along the hot rolling line L by the roller table 65 and stops at a predetermined position. At this time, the claw 43 stands by at the position of the roller table 65 in a horizontal posture. The hydraulic cylinder 31 is driven to rotate the movable frame 35 by 90 degrees to erect the claw 43. Then, the hydraulic cylinder 38 is driven to move the movable frame 35 forward in the horizontal direction to bring the slab 1 onto the furnace center line C. At this time, the hearth 52
Is below the slab 1 in the vertical posture, and the support shaft 56
Is waiting slightly above the position shown in the figure. Such a state is shown by a chain line. Next, electric winch 53
To raise the hearth 52 to raise the hearth 52 and the support shaft 56.
And sandwich slab 1 from above and below. A cutout (not shown) into which the receiving portion 44 of the claw 43 is inserted is provided at the top of the hearth 52. Next, again the hydraulic cylinder 38
Is driven to move the movable frame 35 backward and to stand by. The electric winch 53 is driven again to move the slab 1 to the hearth 5
The hearth 52 is raised while being sandwiched between the No. 2 and the support shaft 56, and is charged into the furnace. Then, the slab 1 is heated while being supported between the hearth 52 and the support shaft 56.

When the high temperature heat treatment is completed, the electric winch 5
3 is driven to lower the slab 1. When the slab 1 descends to a predetermined position, the hydraulic cylinder 38 is driven to move the movable frame 35 forward, and the receiving portion 44 of the pawl 43 is brought directly below the slab. At this time, the lower end of the support shaft 56 is separated from the upper side surface of the slab 1. Then, the electric winch 53 is driven to further lower the hearth 52, and the slab 1
To the nail 43. After the hydraulic cylinder 38 is driven again to move the movable frame 35 backward, the hydraulic cylinder 3
1 is rotated to rotate the tilting frame 22 by 90 degrees, and the slab 1 is placed in a horizontal posture.

According to the above apparatus, the slab could be loaded with a positional accuracy of ± 3 mm in the slab width direction.

[0030]

According to the present invention, only the movable frame having the vertically movable slab receiving member is moved forward and backward in the thickness direction of the slab. Therefore, unlike the conventional case, a dolly is not required, and it is not necessary to attach a tilting device, a tilting device driving device, a holding plate, and a holding plate driving device on the dolly, so that the entire charging device can be downsized and the price can be reduced. Can be realized. When positioning the slab charging, the movable frame is moved forward and backward instead of moving the carriage forward and backward, and the charging position is determined by detecting the position and warpage of the slab. Therefore, it is possible to position the slab with high accuracy and load it into the furnace,
Even if the slab is warped, it can be safely charged into the furnace. Furthermore, it is possible to heat the slab uniformly.

[Brief description of drawings]

FIG. 1 is a drawing schematically showing a configuration example of a hot rolling facility provided with an induction heating furnace of the present invention.

FIG. 2 is a view showing a slab tilting device and a slab lifting / lowering device arranged below the induction heating furnace.

FIG. 3 is a view showing a warp of the slab and an example of arrangement of the slab receiving member and the slab holding plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 slab 46 hydraulic cylinder 11 gas combustion type heating furnace 51 slab lifting support device 12 induction heating furnace 52 hearth 14 furnace ceiling wall 53 electric winch 15 through hole 55 slab upper support device 16 furnace chamber 56 support shaft 21 slab tilting device 58 air cylinder 22 tilting frame 61 rough rolling mill 25 arm 63 finishing rolling mill 26 rotating shaft 65 roller table 31 hydraulic cylinder 71 slab holding device 35 movable frame 74 slab holding plate 38 hydraulic cylinder 76 hydraulic cylinder 40 movable frame displacement detector 78 Slab presser plate displacement detector 41 Guide frame 81 Loading position control device 43 Claw

Claims (2)

(57) [Claims] 1. A furnace for heating a slab by supporting the side surface of the slab horizontally, and a slab tilting device for rotating the slab by 90 degrees, and a slab lifting support for supporting the lower slab side surface from below. In an induction heating furnace comprising a device and a slab upper support device having a plurality of support shafts arranged along the furnace longitudinal direction and penetrating through the furnace body ceiling wall and pressing the upper slab side surface, The slab tilting device
A plurality of tilting frames that can be rotated between a horizontal posture and a vertical posture and are arranged along the longitudinal direction of the furnace, a tilting frame turning device provided in each tilting device, and each tilting frame. Movable frame attached to each slab in the thickness direction, movable frame advancing / retracting device attached to each tilting frame, guide frame fixed to each movable frame, and vertically movable to each guide frame An induction heating furnace for directional electromagnetic steel slabs, comprising: a slab receiving member attached to the guide frame; and a slab receiving member lifting device attached to each guide frame. 2. A device for detecting the advancing / retreating distance of the movable frame, and a plurality of slab pressing plates which are capable of advancing / retreating with respect to the upper and lower surfaces of the slab in a vertical posture and are arranged below the bottom of the furnace along the longitudinal direction of the furnace. A slab presser plate advancing / retreating device provided on each slab presser plate, a device for detecting the advancing / retreating distance of each slab presser plate, a moving frame advancing / retreating distance detecting device and a slab presser plate advancing / retreating distance detecting device. The directional electromagnetic steel slab according to claim 1, further comprising a charging position control device for determining a charging position in the slab width direction based on the signal and controlling the movable frame advancing / retreating device and the slab presser plate advancing / retreating device. Induction heating furnace.