JPH0574554A - Electric heating method and device - Google Patents

Abstract

PURPOSE:To prevent the contact portion of a pressing roll with a heating material from being set to the locally flat state even at the time of the line stop of a facility when the pressing force is applied with the elastically deformable pressing roll. CONSTITUTION:A roll pair 20 constituted of an electric roll 22 and a pressing roll 21 elastically deformable in the axial direction is brought into contact with a belt-like steel plate 10 fed continuously, the pressing force P is applied to the pressing roll 21 by a pneumatic cylinder 401, and the belt-like steel plate 10 is electrically heated. When the line of a facility is stopped, the application of the pressing force by the pneumatic cylinder 401 is interlockingly released, thus the contact portion of the pressing roll 2 is not set to the locally flat state during the line stop. When the line is started, the pressing force is applied by the pneumatic cylinder 401 interlockingly with it, and excitation is started. The fluctuation of the pressing force due to the local flatness of the pressing roll 21 does not occur, thus no spark is generated between the electric roll 22 and the belt-like steel plate 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for electrically heating a material to be heated having electrical conductivity while continuously feeding it, and for example, various methods such as quenching and annealing of band-shaped steel sheets. The present invention relates to an electric heating method and apparatus used for heating for heat treatment.

[0002]

2. Description of the Related Art Conventionally, as a method of heating a strip-shaped steel sheet for various heat treatments such as quenching and annealing, a strip-shaped steel sheet that is continuously fed is brought into contact with an energizing roll, and the strip-shaped steel sheet is cut from this energizing roll. There is an electric heating method in which electric power is supplied to heat the strip steel plate by electric heating. In such an electrification heating method, in order to secure the electrification capacity required for heating between the electrification roll and the strip-shaped steel sheet, in general, a roll pair consisting of the electrification roll and the electrification roll or a press roll and the electrification roll. The strip-shaped steel sheet is sandwiched by a pair of rolls, and a rolling-down force is applied to the roll pair so that the energizing roll and the strip-shaped steel sheet are brought into reliable contact with each other.

However, in this type of strip-shaped steel sheet which is continuously heated and electrically heated, there is a thickness deviation (crown) in the width direction, and the current-carrying roll has a perfect diameter dimension at the time of manufacture. Even during operation, however, a diameter deviation (thermal crown) occurs due to the temperature deviation in the axial direction.
Therefore, there is a problem that a contact failure occurs between the energizing roll and the strip-shaped steel sheet, particularly at an edge portion where a gap is large due to an edge drop, and a spark is generated between both.

As a countermeasure against the above problems, the present inventor, as shown in FIG. 5, uses a pair of rolls 2 for sandwiching the strip-shaped steel plate 1 as an energizing roll 3 and a pressing roll 4 which is elastically deformable in the radial direction. Considered to configure. That is, the pressing roll 4 is a roll having the elastic rubber layer 5 lined on the surface thereof, and the pressing force is applied to the strip-shaped steel plate 1 by applying a pressing force P to the pressing roll 4. According to this, when the pressing force P is applied to the press roll 4, the elastic rubber layer 5 contacting the strip steel plate 1 is elastically deformed and becomes flat, so that the press roll 4 and the strip steel plate 1 are The strip steel plate 1 and the energizing roll 3 are reliably brought into contact with each other over the entire width of the strip steel plate 1. Therefore, it is possible to prevent the occurrence of sparks between the strip steel plate 1 and the energizing roll 3.

[0005]

By the way, at the time of energization heating, there is a case where the feeding and energization of the strip-shaped steel sheet are stopped to suspend the line due to equipment failure or the like.
The pair of rolls sandwiching the strip-shaped steel sheet was in a standby state with the energization stopped while the regular rolling force was applied.

However, when the pressing roll 4 which is elastically deformable in the radial direction is used as described above, when the line is stopped, the pressing force P is applied to the pressing roll 4 in a stationary state for a long time. The contact portion of the elastic rubber layer 5 that contacts the strip-shaped steel sheet 1 is held in a flat state.
Therefore, when the strip-shaped steel sheet 1 is started to be fed by the line activation and the pressing roll 4 starts to rotate, it takes a considerable time to restore the contact portion of the elastic rubber layer 5 from the flat state to the original circular shape. For example, FIG. 6 is a graph showing the change over time in the rolling reduction force from the restart of the line after the line is stopped.
Using a 0 mm holding roll 4 and a 450 mm diameter energizing roll 3, a strip steel plate 1 having a thickness of 2.3 mm and a width of 1250 mm is
It is the one when it was operated by feeding at a line speed of 30 m / min. As is clear from this figure, the flattening residual portion comes into contact with the strip-shaped steel sheet 1 every one rotation of the presser roll 4 (about 2 seconds), so that the reduction force fluctuates and the flatness residual portion is restored (the reduction force variation is It takes about 30 seconds. Therefore,
If the energization is started within the time until the flat residual portion is restored, when the flat residual portion and the strip-shaped steel sheet 1 come into contact with each other, the contact between the strip-shaped steel sheet 1 and the energizing roll 3 becomes uncertain, and a spark occurs. There was a problem.

Therefore, according to the present invention, when the pressing force is applied by using the elastically deformable pressing roll, even if there is a line break of the equipment, the contact portion of the pressing roll with the material to be heated is locally flattened during that time. It is an object of the present invention to provide an electric heating method and an apparatus for preventing a state.

[0008]

In order to achieve the above object, the present invention provides a rolling means in which a pair of rolls, at least one of which is an energizing roll, is brought into contact with a continuously heated material to be fed. In the electric heating method of applying a rolling force to the pair of rolls to electrically heat the material to be heated, a pair of rolls composed of an electric roll and a pressing roll elastically deformable in the radial direction is used to interlock with the line stop of the equipment. Then, the pressure reducing means is deactivated, and the pressure reduction means is activated in conjunction with the line activation. In the present invention, at least one of a pair of rolls is brought into contact with a roll pair consisting of an energizing roll, and the roll is contacted with a material to be continuously fed. In the electric heating device for electrically heating, the roll pair is constituted by an electric roll and a pressing roll that is elastically deformable in the radial direction, and the rolling-down means is brought into a non-operating state in conjunction with a line stop and a line start of equipment. A control means for switching to the operating state is provided.

[0009]

According to the present invention configured as described above, since the pressure reducing means is brought into the non-operating state in association with the line stop, the application of the pressure reducing force to the presser roll is released during the line rest period.
The contact area of the press roll with the material to be heated does not become flat locally. Therefore, even if energization is started by operating the pressure-reducing means in conjunction with the line start-up, there is no fluctuation in the pressure-reducing force due to the local flatness of the presser roll, so there is spark between the energizing roll and the material to be heated. It never happens.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an electric heating method and apparatus to which the present invention is applied will be described below with reference to FIGS. First, FIG. 4 shows the entire apparatus, and a pair of roll pairs 20 and 30 are arranged at a predetermined interval along the feeding path L of the strip-shaped steel plate 10 as a material to be heated. These roll pairs 2
0 and 30 are the pressing roll 21 and the energizing roll 22 respectively.
, And a pair of a press roll 31 and an energizing roll 32, and are arranged opposite to each other with the strip-shaped steel plate 10 interposed therebetween. The rolls 21, 22, 31, 32 are rotatable around shafts 211, 221, 311, 321 respectively, and the energizing rolls 22, 32 are synchronized with the continuous feeding of the strip-shaped steel sheet 10 in the arrow direction. It may be rotationally driven by a motor.

The pressing roll 21 is a non-conductive roll having an elastic rubber layer or the like lined on its surface, and the pressing roll 31 is a non-conductive roll having a heat-resistant metal layer or the like laminated on the elastic rubber layer or the like, In both cases, the vicinity of the surface is configured to be elastically deformable in the radial direction. The pressing rolls 21 and 31 are rotated by the pressing means 40, which will be described later.
The strip-shaped steel plate 10 is pressure-bonded by applying a pressing force P to both ends of the strips 1, 311.

Next, in the apparatus of this embodiment, an annular transformer 50 is arranged around the outer periphery of the strip-shaped steel plate 10 between the roll pairs 20 and 30 as a means for energizing the strip-shaped steel plate 10. The ring-shaped transformer 50 includes, for example, a ring-shaped iron core 51 in which a silicon steel plate having a property suitable as a magnetic path is formed into a rectangular ring shape and laminated to have a predetermined length, and the ring-shaped iron core 51.
And a primary coil 52 wound around the inner and outer circumferences of the. The strip steel plate 1 is provided in the ring of the annular core 51.
0 is inserted. The primary coil 52 of the annular transformer 50 is connected to the AC power supply 60 having a power control switch.

Further, in this apparatus, the energizing roll 2
Reference numerals 2 and 32 have, for example, power receiving portions on their shafts 221 and 321, and a slider 71 is slidably contacted to these power receiving portions. A conductive member (so-called bus bar) 70 is installed between the pair of sliders 71, and the electrically conductive rolls 22 and 32 are electrically connected to each other. As the conductive member 70, a good conductive material such as a copper material having a predetermined width and thickness is used. Here, the energizing rolls 22 and 3
The relationship between the electrical resistance R1 of the strip-shaped steel sheet 10 and the electrical resistance R2 of the conductive member 70 between 2 is set to R1 >> R2. The conductive members 70 are arranged above and below the annular transformer 50 and the strip-shaped steel plate 10 at substantially equal intervals, and are integrally coupled near the energizing rolls 22 and 32 and connected to the slider 71.

Next, FIGS. 1 to 3 show an embodiment of the rolling-down means 40. It should be noted that the roll pair 20 on the heating input side
The rolling-down means 40 will be described, but the rolling-down means for the pair of rolls on the heating outlet side is substantially the same.

First, FIG. 1 shows a first embodiment, in which a pneumatic cylinder 401 is used. This pneumatic cylinder 4
01 is attached to the upper end of the fixed frame 402, and its piston rod 401a is connected to a bearing 403 supporting the shaft 211 of the press roll 21 via a pin 404. The bearing 403 is slidably engaged with the fixed frame 402. Further, solenoid valves 405 and 406 are respectively provided in the air supply passage and the exhaust passage of the pneumatic cylinder 401, and the solenoids 405a and 406a of these solenoid valves 405 and 406 are connected to the switching control unit 407. A line stop signal and a line start signal are input to the switching control unit 407 from a main control device 408 that controls the entire equipment. The switching control unit 4 based on these signals
07 controls the solenoids 405a and 406a, which opens or closes the solenoid valves 405 and 406.

FIG. 2 shows a second embodiment in which a compression coil spring 411 is used. A motor 412 is attached to the upper end of the fixed frame 402, and a compression coil spring 411 is arranged between the lower end of the screw down screw 413 rotatably driven by the motor 412 and the bearing 403. Therefore, the reduction screw 413 by the motor 412
The rotation of the compression coil spring 411 allows the spring force of the compression coil spring 411 to be adjusted. Further, in this example, the switching control unit 407 is configured to control the motor 412.

Further, FIG. 3 shows a third embodiment, in which the pneumatic cylinder 401 and the compression coil spring 411 as described above are used.
A series combination of and is used. Compression coil spring 41
1 is arranged between the lower end of the piston rod 401a of the pneumatic cylinder 401 and the bearing 403. The control system in this example is the same as that in the first embodiment.

Although not shown, as a fourth embodiment,
A hydraulic cylinder may be used instead of the pneumatic cylinder 401 in the third embodiment.

In the electric heating device configured as described above, in FIG. 4, when the primary voltage is applied from the AC power source 60 to the primary coil 52 of the annular transformer 50, it is inserted into the ring of the primary coil 52. Since the strip steel plate 10 functions as a secondary coil, a secondary voltage is induced in the strip steel plate 10. A conductive member 70 is provided between the energizing rolls 22 and 32.
Since it is electrically connected by
A short circuit is formed by the strip-shaped steel plate 10 and the conductive member 70 via the lines 2 and 32, and the secondary current generated in the strip-shaped steel plate 10 flows through the conductive member 70 as a return line. The secondary voltage induced in the strip-shaped steel sheet 10 is consumed by the voltage drop in the strip-shaped steel sheet 10 and the voltage drop in the conductive member 70, but (electrical resistance of the strip-shaped steel sheet 10) >> (electrical resistance of the conductive member 70) Since most of the secondary voltage is consumed for heating the strip steel sheet 10, the loss in the conductive member 70 is extremely small. As a result, the strip-shaped steel sheet 10 is heated with high efficiency by energization.

1 to 3, the pressing roll 21 is pressed down by the pressing means 40 during the above-mentioned electric heating, but the pneumatic cylinder 401 and the compression coil spring 41 are used.
1. The serial combination of the pneumatic cylinder 401 (or hydraulic cylinder) and the compression coil spring 411 has compressibility against the rolling force P. Therefore, even if the thickness of the strip-shaped steel sheet 10 that is continuously fed varies, the gap between the pressing roll 21 and the energizing roll 22 is displaced in a state where the magnitude of the variation in the rolling force P can be almost ignored. The variation rate of the rolling force P when the gap between the presser roll 21 and the energizing roll 22 changes with the variation of the sheet thickness becomes a value substantially equal to the variation rate of the thickness, and the variation of the rolling force P due to the sheet thickness variation. Does not cause plastic deformation of the strip steel plate 10.

As in the present embodiment, the energizing roll 22
The roll pair 20 including a pressing roll 21 that is elastically deformable in the radial direction does not give plastic deformation to the strip-shaped steel sheet 10 by elastically deforming the pressing roll 21. Therefore, the compression means 40 having compressibility
By displacing the gap between the pressing roll 21 and the energizing roll 22 with using the pressing force P with little change, the advantage of using the elastically deformable pressing roll 21 can be fully utilized.

By the way, when the line is stopped due to equipment failure during energization heating, the main controller 408 sends a line stop signal to the switching controller 407 at about the same time as the line stop in FIGS. 1 and 3. Based on this signal, the switching control unit 407 causes the solenoids 405a, 40
6a is controlled to close the electromagnetic valve 405 in the air supply passage and open the electromagnetic valve 406 in the exhaust passage. Further, in FIG. 2, the switching control unit 407 controls the motor 412 based on the line stop signal from the main control device 408,
The compression screw 413 is rotated to rotate the compression coil spring 41.
Release the spring force of 1. By this, the presser roll 2
The pressing force P to 1 is released, and the pressing roll 21 comes into contact with the strip-shaped steel plate 10 only by its own weight. Therefore, it is possible to prevent the elastic rubber layer of the press roll 21 from being locally flat while the line is stopped.

When the line is activated after the line is stopped, the main control unit 408 sends a line activation signal to the switching control unit 407 almost simultaneously with the line activation in FIGS. 1 and 3, and based on this signal. Switching control unit 407
Controls the solenoids 405a and 406a to open the solenoid valve 405 in the air supply passage and close the solenoid valve 406 in the exhaust passage. Further, in FIG. 2, the main controller 4
Based on the line activation signal from 08, the switching control unit 40
7 controls the motor 412 to rotate the reduction screw 413 to apply a spring force to the compression coil spring 411.
In this way, the pressing force P is applied almost at the same time when the line is activated,
Even if the energization is started at the same time when the required rolling force is reached, the rolling force does not fluctuate due to the local flatness of the press roll 21,
No spark is generated between the strip steel plate 10 and the energizing roll 22.

The embodiments of the present invention have been described above.
The present invention is not limited to the above embodiments, and various effective modifications and applications are possible based on the technical idea of the present invention. For example, although the compressing reduction means is used in the embodiment, an incompressible reduction means such as a liquid cylinder may be used. In the embodiment, the configuration in which the belt-shaped steel plate is heated by inducing a voltage by the annular transformer has been described, but a configuration in which power is supplied directly from the power supply means (AC power supply and transformer) to both energizing rolls may be used.

[0025]

As described above, according to the present invention,
When applying a pressing force using the elastically deformable pressing roll, by controlling the non-operating state and the operating state of the rolling-down means in conjunction with the line stop and the line starting of the equipment,
Even if the line is stopped for a long time due to a failure or the like, it is possible to prevent the contact portion of the pressing roll with the material to be heated from being locally flat. Therefore,
Even if a pressing force is applied in conjunction with the line activation to start energization, there is no fluctuation in the pressing force due to the local flatness of the press roll, so sparking does not occur between the energizing roll and the material to be heated. In addition, the operating rate of the equipment can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a roll pair and a rolling-down means in a first embodiment of the present invention.

FIG. 2 is a diagram showing a roll pair and a rolling-down means in a second embodiment.

FIG. 3 is a diagram showing a roll pair and a rolling-down means in a third embodiment.

FIG. 4 is a partially cutaway front view of the entire electric heating apparatus in the example.

FIG. 5 is a schematic view of a roll pair in a study example prior to the present invention.

FIG. 6 is a graph showing a change over time in the rolling force from the start of activation after the line is stopped in the above-described study example.

[Explanation of symbols]

 10 strip steel plate (material to be heated) 20, 30 roll pair 21, 31 pressing roll 22, 32 energizing roll 40 pressure reducing means 401 pneumatic cylinders 405, 406 solenoid valve 407 switching control section 408 main control device 411 compression coil spring 412 motor 413 reduction screw 60 AC power source 70 Conductive member

Claims (2)

[Claims] 1. A roll pair having at least one of a pair of rolls consisting of an energizing roll is brought into contact with a material to be heated which is continuously fed, and a rolling-down means applies a rolling force to the pair of rolls to roll the material to be heated. In the energizing heating method of energizing heating, a roll pair consisting of an energizing roll and a pressing roll that is elastically deformable in the radial direction is used. An electric heating method, characterized in that the pressing means is activated. 2. A roll pair of which at least one of a pair of rolls is an energizing roll is brought into contact with a continuously heated material to be fed, and a rolling down force is applied to the roll pair by a rolling down means to roll the heated material. In an electric heating device for electrically heating, the roll pair is composed of an electric roll and a pressing roll that is elastically deformable in the radial direction, and the rolling-down means is operated in a non-operating state in cooperation with a line stop and a line start of equipment. An electric heating device, characterized in that it is provided with a control means for switching to the state.