JP2006286248A - Induction heating device and arc spot suppression method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating device and an arc spot suppression method for an induction heating device by which a shaft current can be stably absorbed by stable contact pressure and expansion of a contact area, and flaws occurring in a material to be heated can be reduced by effectively suppressing arc spots. <P>SOLUTION: If an eddy current occurring in the material B to be heated is unbalanced by heating due to deviations of the positional relationship between C-type inductors 1a, 1b and the material B to be heated. When the shaft current occurs in the material B to be heated, and shaft current is detected by a shaft current detector 24 and a shaft current measurement device 25 from a pinch roll 2a via slip-rings 21a, 21b and ground brushes 22a, 22b. The position of the material B to be heated in the widthwise direction is corrected by moving a material position adjustment device 30 or the C-type inductors 1a, 1b on the basis of the detected shaft current value. Consequently, the positional relationship between the C-type inductors and the material to be heated is corrected as the center in the longitudinal direction of the material to be heated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an induction heating apparatus for heating a rolled material or other heated material in a hot rolling line, and in particular, an arc spot generated during edge heating of the heated material using a C-type inductor is effective. TECHNICAL FIELD The present invention relates to an induction heating apparatus that suppresses mechanically and an arc spot suppression method for an induction heating apparatus.

  In a hot rolling line, a rolled material heated to a temperature capable of being rolled by a heating furnace is roughly rolled in a roughing mill and formed into a state called a rough bar, and the rough bar is further subjected to a finishing rolling mill to obtain a desired shape. Products with plate pressure and width are obtained. In this case, a full width heating device that heats the material to be heated over the full width and raises the overall temperature in order to prevent a temperature drop or to equalize the temperature of each part of the rolled material in the state of a coarse bar. A bar heater or a C-type inductor that is an end heating device that heats both ends of a material to be heated whose temperature is lower than that of a central portion is used.

  Such a C-type inductor is disposed in pairs at both ends in the width direction of the material to be heated, and an eddy current I flows by interlinking the magnetic flux Φ generated from the heating coil to the material to be heated. Joule heat is generated by this resistance to heat both ends of the material to be heated. At this time, the current applied to the heating coil has the same phase and reverse current, and the direction of the eddy current generated at both ends across the center in the longitudinal direction of the material to be heated is reverse. Accordingly, when the positional relationship between the material to be heated and the heating coil is centered in the longitudinal direction of the material to be heated and the objectivity is lost, an axial current is generated.

Conventionally, as an apparatus that absorbs such an axial current, there is a device that bypasses the current by creating a circuit having a resistance smaller than the resistance of the current circuit for the leakage current of the eddy current flowing through the metal roll (Patent Document 1). ). In addition, there is a device in which the entire material to be heated is passed through a ring-shaped iron core and a coil wound around the core, and the axial current is canceled by a magnetic flux generated from the coil (Patent Document 2).
Japanese Patent Laid-Open No. 11-290930 JP 2002-110335 A

  However, in the axial current absorbing device of Patent Document 1, the axial current is absorbed by a metal roll that supports the material to be heated from below and a pair of short-circuiting rolls connected via a conductor. The contact area with the material to be heated was small, and a sufficient contact pressure was not applied. Further, since the shaft current is not always measured and the material position and the C-type inductor position are not corrected positively based on the current value, stable absorption of the shaft current cannot be expected.

  In Patent Document 2, the axial current is measured, and the axial current is eliminated by applying a current in the opposite direction to the axial current. The axial current itself is not zero. Further, since the shaft current is not actively circulated, the shaft current cannot be accurately detected.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and the object thereof is to stably absorb axial current by expanding the contact pressure and the contact area. Another object of the present invention is to provide an induction heating apparatus and an arc spot suppression method for the induction heating apparatus that can reduce scratches generated in the material to be heated by effectively suppressing the arc spot.

  In order to achieve the above object, an invention according to claim 1 is directed to an induction heating apparatus including a C-type inductor for heating an edge of a material to be heated and a pinch roll disposed before and after the C-type inductor. And an axial current measuring device for measuring the axial current generated in the heated material by heating with the C-type inductor, and correcting the relative position in the width direction of the heated material based on the measured value by the axial current measuring device And a heated material correcting means.

  Further, the invention of claim 5 is the one in which the invention of claim 1 is grasped from the viewpoint of an arc spot suppressing method, and includes a C-type inductor for heating the edge of a material to be heated, and a pinch disposed before and after the inductor. In the arc spot suppression method for an induction heating device performed using an induction heating device provided with a roll, a process of measuring an axial current generated in a material to be heated by heating with the C-type inductor and the C-type inductor, And a process of correcting the relative position in the width direction of the material to be heated based on the measured value of the axial current.

  In the invention according to claim 1 or 5 as described above, the positional relationship between the C-type inductor and the material to be heated is shifted, so that the balance of eddy currents generated in the material to be heated by heating is lost, and axial current is generated in the material to be heated. Even in this case, this axial current can be detected by the axial current measuring device. Then, by correcting the position in the width direction of the material to be heated based on the detected axial current value, the positional relationship between the C-type inductor and the material to be heated is corrected as the center in the longitudinal direction of the material to be heated. It becomes possible to cancel the current.

According to a second aspect of the present invention, in the first aspect of the invention, the heated material position correcting means performs position correction by moving the heated material in the width direction.
According to a third aspect of the present invention, in the first or second aspect of the invention, the heated material position correcting means corrects the position of the heated material by moving the C-type inductor in the width direction of the heated material. It is characterized by performing.

The invention of claim 6 is the invention of claim 2 taken from the viewpoint of an arc spot suppressing method. In the invention of claim 5, the position correction of the material to be heated is performed by adjusting the width of the material to be heated. It includes a process of moving in the direction.
The invention according to claim 7 is the invention according to claim 5 or 6, wherein the invention according to claim 3 is caught from the viewpoint of an arc spot suppressing method, and the heated material position correction is performed by adjusting the C-type inductor. It includes a process of moving in the width direction of the material to be heated.

  In the invention of claim 2 or 3 and claim 5 or 6 as described above, the axial current generated in the material to be heated is detected, and the position of the material to be heated or the position of the C-type inductor is corrected. The axial current can be brought close to 0 to suppress the generation of arc spots, and the plate quality can be improved and stable operation can be realized.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the axial current measuring device is provided in a slip ring provided at an end of the pinch roll, and provided in the slip ring. An axial current absorbing means provided with an earth brush, a current circulation cable which is arranged before and after the C-type inductor and which short-circuits between the axial current absorption means of the pinch rolls, and a current which measures a current flowing through the current circulation cable It comprises a detection means.

  In the invention of claim 4 as described above, the pinch roll installed before and after the C-type inductor is provided with a slip ring and a ground brush for collecting axial current. By short-circuiting, it is possible to suppress the arc spot and reduce the scratches generated on the plate.

  According to the present invention, the stable contact pressure and the expansion of the contact area enable the stable absorption of the axial current and the reduction of the scratches generated in the material to be heated by effectively suppressing the arc spot. An induction heating device and an arc spot suppression method for the induction heating device can be provided.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be specifically described with reference to the drawings.

(1) Embodiment (1-1) Configuration As shown in FIG. 1, the induction heating device of the present embodiment includes C-type inductors 1 a and 1 b and pinch rolls 2 a and 2 b that sandwich and convey a material to be heated B. Are provided on the input side and the output side of the C-type inductors 1a and 1b, respectively.

[Configuration of C-type inductor]
The C-type inductors 1a and 1b have a configuration in which heating coils 5a and 5b are wound around upper and lower C-type iron cores 4a and 4b with an opening 3 interposed therebetween. As shown in FIG. 2, the C-type inductors 1a and 1b are mounted on carts 6a and 6b. The carts 6a and 6b are provided with moving wheels 7, and rails 8 (not shown in FIG. 1). The upper part is configured to be movable in the width direction of the material B to be heated by driving the motors 9a and 9b.

  FIG. 2 shows details of the C-type inductors 1a and 1b and the carriages 6a and 6b on which they are mounted. The carts 6a and 6b are equipped with cart position detection devices 10a and 10b for detecting the relative position in the width direction of the heated material B of the cart, and based on the cart positions detected by the cart position detection devices 10a and 10b. Then, the control device 11 issues an adjustment command to the motor control device 12. The motors 9a and 9b are driven by the motor control device 12, and the positions of the carriages 6a and 6b are adjusted by moving the moving wheels 7 on the rails 8. The carts 6a and 6b of the C-type inductors 1a and 1b are independently controlled, and are heated according to the plate width of the material B to be heated or by heating the C-type inductor 1 described later. The position is adjusted according to the balance of the eddy current generated in the material B.

[Configuration of pinch roll and circulating cable]
On the other hand, as shown in FIGS. 3 (a) and 3 (b), slip rings 21a and 21b made of current collecting rings fixed to the rotation shafts of the pinch rolls are provided at both ends of the pinch rolls 2a and 2b, and slip rings, respectively. Ground brushes 22a and 22b are provided which are in sliding contact with 21a and 21b and are electrically connected to the terminals. A circulation cable 23 is attached to the ground brushes 22a and 22b. When an axial current is generated, the current flows from the pinch roll 2a through the slip ring 21a, 21b and the ground brush 22a, 22b through the circulation cable 23 and circulates to the other pinch roll 2b. ing.

  Further, as shown in FIG. 1, an axial current detection device 24 and an axial current measurement device 25 for detecting a current flowing through the circulation cable 23 are provided in the middle of the circulation cable 23. The signal line 26 is connected to the control device 11. The control device 11 is connected to a calculation result display device D which is a display device represented by a human machine interface.

[Configuration of Heated Material Transfer Device]
As shown in FIG. 1, a material position adjusting device 30 that adjusts the relative position of the heated material B in the width direction by moving the heated material B is provided on the downstream side of the pinch roll 2a. As shown in FIG. 4, the material position adjusting device 30 is provided with two holding rollers 31a and 31b fixedly provided in the horizontal direction on the lower side of the material to be heated B, and on the upper side with jacks. One position adjusting roller 32 provided with one end portion movably in the horizontal direction by 33 is provided. As described above, the position adjusting roller 32 has one end portion moved in the horizontal direction by the jack 33, thereby changing the contact surface with the heated material B on the holding rollers 31a and 31b. The width direction L, R position of the material B is moved.

  The material position adjusting device 30 is provided with a position detecting device 34 for detecting the position of the material B to be heated. Both the position detecting device 34 and the material position adjusting device 30 are connected to the control device 11. .

(1-2) Operational Effects The operation of the present embodiment configured as described above will be described. First, by linking the magnetic flux Φ generated from the C-type inductors 1a and 1b to the material to be heated B, an eddy current I flows as shown in FIG. 5 and Joule heat is generated by the resistance of the material to be heated B. The both ends of the material to be heated B are heated.

  At this time, the currents applied to the heating coils 5a and 5b have the same phase and reverse current, and the direction of the eddy current I generated at both ends across the center in the longitudinal direction of the material to be heated B is reverse. Therefore, if the positional relationship between the C-type inductor and the material to be heated B is the same for both C-type inductors, that is, if the C-type inductors 1a and 1b are at symmetrical positions with respect to the longitudinal center of the material to be heated B, Axial currents do not cancel each other.

  On the other hand, an axial current is generated when the positional relationship between the material to be heated B and the C-type inductor sandwiches the center of the material to be heated B and the symmetry is lost. When the axial current is generated, the current flows from the pinch roll 2a through the slip rings 21a and 21b and the earth brushes 22a and 22b through the current circulation cable and circulates to the other pinch roll 2b.

  Here, the position correction processing in the material position adjusting device 30 for the material to be heated will be described in detail. First, when an axial current is detected by the axial current detection device 24, the axial current measurement device 25 converts it into a signal corresponding to the current value. Next, this signal passes through the signal line 26 and is input to the control device 11 to calculate the current value (see FIG. 1). The calculated shaft current value is displayed on the calculation result display device D connected to the control device 11.

  Further, the control device 11 outputs a position correction signal to the material position adjusting device 30 based on the detected shaft current value. Based on this position correction signal, as shown in FIG. 4, the material position adjustment device 30 causes the jack 33 to act so that one end X of the position adjustment roller 32 has a predetermined amount in a predetermined direction, for example, upward. The heated material B is moved in the L direction on the left side in the conveying direction.

  Next, the control device 11 detects the axial current value that changes with the movement from the axial current detection device 24 and the axial current measurement device 25, and the axial current before the material to be heated B is moved by the material position adjusting device 30. Compare the value (1) with the shaft current value (2) after movement. Here, when the pre-movement axial current value (1) is smaller than the post-movement axial current (2), the end X of the position adjusting roller 32 of the material position adjusting device 30 is moved downward, and the heated material B Is moved in the opposite R direction. Then, when the post-movement axial current (3) is smaller than the pre-movement axial current (1) again, the heated material B is further moved in the same direction.

  In this way, while constantly detecting the difference in the axial current, the above process is repeated and finally the axial current value is set to 0, that is, the C-type inductors 1a and 1b are based on the longitudinal center of the material to be heated. Correct so that it is located symmetrically.

  The position correction process in the position correction of the C-type inductor is the same as described above, and a position correction signal is output to the C-type inductors 1a and 1b based on the axial current value detected by the control device 11. Based on the position correction signal, the C-type inductors 1a and 1b are moved by a predetermined amount in a predetermined direction, for example, the L direction by the action of the carriages 6a and 6b and the moving wheel 7. Similarly to the above, the width of the C-type inductor is detected so that the axial current value finally becomes 0 by detecting the difference in the axial current and moving the C-type inductors 1a and 1b in the L direction or the R direction. This controls the relative position of the direction.

  According to the present embodiment that operates as described above, the positional relationship between the C-type inductors 1a and 1b and the material to be heated B shifts, so that the balance of the eddy current I generated in the material to be heated B by heating is lost and the material to be heated is lost. Even if an axial current is generated in B, the axial current can be detected by the axial current detecting device 24 and the axial current measuring device 25. Further, the axial current generated from the deviation between the pinch rolls 2a, 2b and the heated material B installed before and after the C-type inductor and the deviation between the C-type inductors 1a, 1b is detected, and the heated material B is detected based on the axial current value. By correcting at least one of these positions and the position of the C-type inductor, the axial current flowing to the pinch roll can be brought close to 0 and the generation of the arc spot can be suppressed. This prevents arc marks from remaining on the plate and makes it possible to manufacture a high-quality product.

  Further, slip rings 21a, 21b and earth brushes 22a, 22b for collecting axial current are installed on the pinch rolls 2a, 2b installed before and after the C-type inductors 1a, 1b. 22b can be short-circuited with the circulation cable 23, so that the stable contact pressure with respect to the material B to be heated and the contact area can be expanded, so that the axial current can be stably absorbed. It is possible to reduce scratches generated on the plate.

(2) Other Embodiments The present invention is not limited to the above-described embodiments, and includes other embodiments as described below. For example, in the above-described embodiment, the induction heating apparatus provided with both the position correcting means for the C-type inductor and the position correcting means for the material to be heated B is shown. However, the present invention is not limited to this, and for example, shown in FIG. Thus, it is also possible to employ a configuration in which only the material position adjusting device 30 for the material to be heated, which is the position correction means for the material to be heated B, is provided. On the other hand, as shown in FIG. 6, it is possible to configure only with the moving means of the C-type inductor.

  Further, the above-described moving means of the C-type inductor or moving means of the material to be heated B is merely one aspect for carrying out the present invention, and any other means can be used as long as it moves the C-type inductor to the relative position in the width direction. It can be configured by any known means.

The figure which shows the whole structure of the induction heating apparatus in embodiment of this invention. The schematic diagram which shows the structure of the C-type inductor in embodiment of this invention. The figure which shows the structure of the pinch roll in embodiment of this invention. The figure which shows the structure of the material position adjustment apparatus in embodiment of this invention. The conceptual diagram which shows the eddy current which generate | occur | produces in the induction heating apparatus in embodiment of this invention. The figure which shows the whole structure of the induction heating apparatus in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b ... C type inductor 2a, 2b ... Pinch roll 3 ... Opening part 4a, 4b ... C type iron core 5a, 5b ... Heating coil 6a, 6b ... Carriage 7 ... Moving wheel 8 ... Rail 9a, 9b ... Motor DESCRIPTION OF SYMBOLS 10a, 10b ... Carriage position detection device 11 ... Control device 12 ... Motor control devices 21a, 21b ... Slip rings 22a, 22b ... Earth brush 23 ... Circulation cable 24 ... Axial current detection device 25 ... Axial current measurement device 26 ... Signal line 30 ... Material position adjusting device 31a ... Holding roller 32 ... Position adjusting roller 33 ... Jack 34 ... Position detecting device B ... Heating material D ... Calculation result display device

Claims (7)

In an induction heating apparatus including a C-type inductor that heats an edge of a material to be heated, and a pinch roll disposed before and after the inductor,
An axial current measuring device for measuring an axial current generated in a material to be heated by heating by the C-type inductor and the C-type inductor;
An induction heating apparatus comprising: a heated material correcting unit that corrects a relative position in the width direction of the heated material based on a measurement value obtained by the axial current measuring apparatus.   The induction heating apparatus according to claim 1, wherein the heated material position correcting means performs position correction by moving the heated material in the width direction.   3. The induction heating apparatus according to claim 1, wherein the heated material position correcting means corrects the position of the heated material by moving the C-type inductor in the width direction of the heated material. .   The axial current measuring device is disposed before and after the C-type inductor, with axial current absorbing means including a slip ring provided at an end of the pinch roll and an earth brush provided on the slip ring. The current circulating cable for short-circuiting between the pinch roll axial current absorbing means and the current detecting means for measuring the current flowing through the current circulating cable are described in any one of claims 1 to 3. Induction heating device. In an arc spot suppression method for an induction heating device including a C-type inductor for heating an edge of a material to be heated and a pinch roll disposed before and after the inductor,
A process of measuring an axial current generated in a material to be heated by heating with the C-type inductor and the C-type inductor;
An arc spot suppression method for an induction heating device, comprising: correcting a relative position in a width direction of the material to be heated based on a measured value of the axial current.   6. The method of suppressing an arc spot in an induction heating apparatus according to claim 5, wherein the position correction of the material to be heated includes a process of moving the material to be heated in the width direction.   7. The method of suppressing an arc spot in an induction heating apparatus according to claim 5, wherein the correction of the heated material position includes a process of moving the C-type inductor in a width direction of the heated material.

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