JP3389349B2 - Magnetic plate positioning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic plate positioning device, and more particularly to a device for positioning a steel plate (ferromagnetic plate) in a direction perpendicular to the surface thereof, and particularly for suppressing vibration in that direction. .

[0002]

2. Description of the Related Art For example, in transporting or winding a thin steel sheet after hot rolling or cold rolling, or transporting a thin steel sheet in a plating treatment line or a continuous heat treatment line, the thin steel sheet is oriented in a direction perpendicular to its surface. If a displacement or vibration occurs, it may hit a structure near the transfer line and cause scratches,
There arises a problem that the tension of the thin steel sheet fluctuates and the quality deteriorates.

Conventionally, in order to prevent displacement or vibration in a direction (thickness direction) perpendicular to the plate surface of the thin steel plate, the conveying speed of the thin steel plate is set low, or the rotation speed of the thin steel plate conveying roller is set. Is controlled so that the tension becomes constant and the tension does not vibrate, or a slack of the thin steel plate is removed by inserting a looper between the transport rollers.

[0004]

However, if the conveying speed of the thin steel sheet is set to be low, the productivity of the processing and treatment of the thin steel sheet is reduced by that much, and the conveying speed control of the thin steel sheet in the machining and processing is hindered. May bring. Even when controlling the tension, the required tension of the thin steel sheet in processing and processing and the tension control are hindered. Since the looper supports the thin steel plate by the driven roller, it may scratch the thin steel plate and, at the same time, it is not expected to be effective against the vibration of a relatively small amplitude, and the vibration is amplified. Or, the tension of the thin steel plate may be excessively increased in a vibrational manner.

The first object of the present invention is to suppress vibration in the thickness direction (direction perpendicular to the plate surface) of the magnetic plate in a non-contact manner. For this purpose, the present invention uses a pair of electromagnets. The second purpose is to enhance the vibration suppressing effect of the electromagnet pair, and the third purpose is to improve the stability of the vibration suppressing.

[0006]

A magnetic material plate positioning device of the present invention has a magnetic material plate (FP) in between, and first and second magnetic pole plates whose magnetic pole end faces face each other perpendicularly to the wide surface (in the x direction). And a second electromagnet (1L, 1R); corresponding to the first gap (Gs) between the magnetic pole end surface of the first electromagnet (1L) and the magnetic plate (FP), when it is large, the high level is low; First energizing means (5A, 4L) for energizing the first electric coil (1La) of the first electromagnet (1L); and the magnetic pole end surface of the second electromagnet (1R) and the magnetic plate (FP). Corresponding to the second gap (Gsc), when it is large, when the level is high, when it is small, the level is low, while the polarity of the magnetic pole end surface of the first electromagnet (1L) is opposite to the polarity of the magnetic pole end surface of the second electromagnet (1R). Second energizing means (5B, 4R) for energizing the second electric coil (1Ra) of the second electromagnet (1R) with a current having a reverse polarity. In addition, in order to facilitate understanding, the reference numerals of corresponding elements or corresponding matters in Examples described later are added in parentheses for reference.

[0007]

[Function] The magnetic pole end surface of the first electromagnet (1L) and the magnetic plate (FP)
If the first gap (Gs) with the first energizing means (5A, 4
L) applies a high level current to the first electric coil (1La), and the first electromagnet (1L) strongly attracts the magnetic plate (FP) in the x direction, at this time, the second gap (Gsc) Is small, the second energizing means (5B, 4R) supplies a low level current to the second electric coil (1Ra).
Since the second electromagnet (1R) is weakly attracted by the magnetic plate (FP), the magnetic plate (FP) moves toward the first electromagnet (1L). That is, the magnetic plate (FP) moves in the direction of decreasing the first gap (Gs). As the first gap (Gs) becomes smaller, the second gap (Gsc) becomes larger, and the force of the first electromagnet (1L) attracting the magnetic plate (FP) decreases and the second electromagnet becomes smaller.
The force that (1R) attracts the magnetic plate (FP) increases. As a result, the magnetic plate (FP) has a first electromagnet (1L) and a second electromagnet (1R).
X position where the electromagnetic attraction force of is balanced. The first electromagnet so as to suppress the vibration when the magnetic plate (FP) vibrates.
Since the current of (1L) and the second electromagnet (1R) increases and decreases, the magnetic plate
(FP) vibration is prevented. Such a magnetic plate (FP)
Since the drive to the position where the electromagnetic attraction force of the first electromagnet (1L) and the second electromagnet (1R) is balanced is non-contact drive by the electromagnetic attraction force, the magnetic plate (FP) is orthogonal to the x direction. Even if it is moved in the y direction (longitudinal direction of the magnetic plate FP), scratches do not occur.

In addition, the second energizing means (5B, 4R) supplies a current whose polarity is opposite to that of the magnetic pole end surface of the first electromagnet (1L) with respect to that of the magnetic pole end surface of the first electromagnet (1L). Since the second electric coil (1Ra) of the second electromagnet (1R) is energized, the first electromagnet (1L)
Generated magnetic flux penetrates the magnetic plate (FP) and the second electromagnet (1
R), and similarly, the magnetic flux generated by the second electromagnet (1R) penetrates the magnetic plate (FP) and reaches the first electromagnet (1L). That is,
In the same magnetic path (magnetic flux loop), the magnetic flux generated by the first electromagnet (1L) and the second electromagnet (1R) does not relatively cancel each other,
On the contrary, it flows in a stimulating manner, and the electromagnetic force acting on the magnetic plate (FP) is extremely strong. For example, as shown in FIG. 7, when the magnetic plate (FP) is displaced from the equilibrium position by 3 mm, the electromagnetic force to return it to the equilibrium position is the same when both electromagnets have the same polarity and are opposed to each other. , About 0.9 Kgf / m ((b) in FIG. 7), but it is about 10 Kgf / m ((a) in FIG. 7) when facing each other with different polarities, which is more than 10 times stronger. . Therefore, the energization current level of both electromagnets for maintaining the magnetic plate (FP) at the equilibrium position can be low, and the power consumption efficiency of the electromagnets is extremely high.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0010]

FIG. 1 shows the overall construction of an embodiment of the present invention. The magnetic material plate FP (in this example, a thin steel plate) moving in the vertical direction y is opposed to the left and right in the x direction, and the magnetic material plate F
Electromagnets 1L and 1R are arranged so as to face the flat plate surface of P. Cores 1Lb of the first and second electromagnets 1L, 1R,
1Rb includes first and second electric coils 1La and 1Ra.
Is attached to the electric coils 1La and 1Ra,
With the coil drivers 4L and 4P, in this embodiment, the end faces facing the tip faces of the cores 1Lb and 1Rb, that is, the flat plate face of the magnetic plate FP, have different polarities (the N pole and the S pole are different). Direct current is applied.

The magnetic flux emitted from the end face of the N pole core of the first electromagnet 1L penetrates the magnetic plate FP and reaches the end face of the S pole core of the second electromagnet 1R, as indicated by the two-dot broken line arrow in FIG. Really
It passes through the core 1Rb of the second electromagnet 1R, exits from the end face of the N pole core thereof, penetrates the magnetic plate FP, and reaches the end face of the S pole core of the first electromagnet 1L. The magnetic flux generated in the second electromagnet 1R also flows through the same loop in the same direction. The reference line Lxs shown in FIG.
Is to extend in the y direction passing through an intermediate (Dw / 2) position of the distance Dw between the electromagnets 1L and 1R facing each other.

In FIG. 1, the gap sensor 3 faces the flat plate surface of the magnetic plate FP. The gap sensor 3 measures a gap Gs (first gap) between the end face of the first electromagnet 1R and the surface of the magnetic plate FP and gives an analog signal G1 indicating the first gap Gs to the control circuit 5A.
The control circuits 5A and 5B feedback control the energization current levels of the electromagnets 1L and 1R via the coil drivers 4L and 4R, respectively.

FIG. 2 shows a perspective view of the electromagnets 1L and 1R surrounded by the chain double-dashed line frame 2a in FIG. The cores 1Lb and 1Rb of the electromagnets 1L and 1R have a length of 50 mm in the vertical direction y, a length of 40 mm in the horizontal direction x, and a front-back direction (width direction of the magnetic plate FP) z.
Is a rectangular parallelepiped with a width of 1000 mm, in which slots for inserting the electric coils 1La and 1Ra are opened, and the slot space is
The dimensions are 30 mm (x) x 30 mm (y) x 1000 mm (z). The electric coils 1La and 1Rb are inserted in this slot,
Electric currents flow in these electric coils in the directions indicated by the solid arrows in FIG. 2 by the coil drivers 4L and 4R. As a result, the facing surfaces of the cores 1Lb and 1Rb have different magnetic poles S and N, respectively.

The structure of the control circuit 5A is shown in FIG.
The configuration of B is shown in FIG. The control circuits 5A and 5B include
Information regarding the magnetic plate FP to be conveyed, that is, the plate thickness d, the target gap G ₀ (G ₀ = (Dw−d) / 2, which uniquely corresponds to the plate thickness d) and the reference current value is corresponding to the target gap G _0. Is given. The reference current value is is a current supplied to the electric coil 1La of the electromagnet 1L in order to maintain the steel plate (predetermined standard) having the plate thickness d in the gaps Gs = G ₀ and Gsc = G ₀ . That is, is is a current value that can constantly maintain Gs = G ₀ and Gsc = G ₀ when Gs and Gsc = G ₀ and there is no disturbance.

Referring to FIG. 3, the signal processing circuit 9a of the control circuit 5A digitally converts the analog signal G1 indicating the first gap Gs provided by the gap sensor 3 to convert the digital data Gs * into the computer 24a. It is given to the signal processing circuit 9b of the control circuit 5B as well as being given.

The coil driver 4L for energizing the electric coil 1La of the first electromagnet 1L has a built-in coil current detection circuit, which supplies the signal processing circuit 8a with an analog signal io1 representing the current value of the electric coil 1La. The signal processing circuit 8a digitally converts the digital data iLs representing the current value of the electric coil 1La into the computer 24.
give to a.

The distance between the left end surface of the core 1Rb of the second electromagnet 1R and the right-side flat plate surface of the magnetic plate FP to be conveyed is G.
sc (second gap), Dw is the distance between the electromagnets 1L / 1R, and d is the plate thickness of the magnetic plate FP. Magnetic plate FP
When the plate width value d of is given, the target gap G ₀ = (Dw−
d) / 2 is uniquely determined, and when the first gap Gs is detected, the second gap Gsc = Dw-d-Gs can be calculated. The second gap Gsc may be detected in the same manner as the detection of the first gap Gs.

Referring to FIG. 6, the signal processing circuit 9b of the control circuit 5B has data Gs representing the first gap Gs.
*, The distance Dw between the electromagnets and the plate thickness d of the magnetic plate are given, and the signal processing circuit 9b displays the second gap Gsc = Dw−.
The d-Gs * is calculated, and the data Gsc * representing this is given to the computer 24b. Electric coil 1Ra of electromagnet 1R
A coil current detection circuit is incorporated in the coil driver 4R that supplies the current to the coil driver 4R, which supplies an analog signal io2 representing the current value of the electric coil 1Ra to the signal processing circuit 8b. The signal processing circuit 8b converts this into a digital signal, and the electric coil 1
Computes digital data iRs representing the current value of Ra
Data 24b.

Referring again to FIG. The control circuit 5A for controlling the energization of the electromagnet 1L includes a digital computer 24a mainly composed of a CPU, signal processing circuits 8a, 9a and P.
It is composed of a WM (pulse width modulation) circuit 7a. PW
The M circuit 7a calculates the energization duty corresponding to the output data (current instruction value) of the computer 24a, and supplies the energization instruction pulse of the calculated energization duty to the coil driver 4L.
Give to. The coil driver 4L turns on / off the electric coil 1La in response to the energization instruction pulse. Thereby, a constant DC voltage is applied to the electric coil 1La at the energizing duty, and the voltage (time-series average value) of the electric coil 1La is determined by the energizing duty. That is, the voltage applied to the electric coil 1La is controlled by the computer 24a via the coil driver 4L and the PWM circuit 7a.

When the computer 24a shown in FIG. 3 is provided with information (plate thickness d, target gap G ₀ and reference current value is) regarding the magnetic plate FP for position control, it stores it in the register 25a, When the start command arrives, the energization level control (PWM control) of the electric coil 1La is started based on the information in the register 25a, and when the stop instruction arrives, the energization of the electric coil 1La is stopped to start the start or the like. Wait for the control command to arrive. In controlling the energization level of the electric coil 1La, the detection data (gap Gs * and current iLs) of the signal processing circuits 8a and 9a are read at a predetermined cycle (sampling cycle), and a current instruction value is generated by feedback calculation. This is then output to the PWM circuit 7a. This control operation is performed by digital processing according to a program. This control function is shown by being replaced with a hardware block (functional block) in FIG. 3 for easy understanding. The control operation of the computer 24a will be described below with reference to this functional block.

The memory 23a stores gain groups corresponding to the plate thicknesses d _{1 to} d _n in correspondence with the plate thicknesses. This is schematically shown in FIG. Here, the memory area in which the gain group for one plate thickness is stored is called a memory table. The gain group data of one plate thickness d _j , that is, the gain data of one memory table dj is also schematically shown in FIG. One plate thickness d
For j, the gap is divided into a number of gap regions x1 to xa for each certain tolerance xd from the initial value x1.
The electric coil current is divided into b gap areas i1 to ib for each certain tolerance id from the initial value i1 and is divided into each area specified by the gap value (x = p) and the current value (i = q). , Gains M _{1,1 to} Ma _{, b} (each of which is a set of K _{1 to} K ₄ ) are written. The same applies to the memory 23b of the control circuit 5B.

When information about the magnetic plate FP to be controlled (plate thickness d, target gap G ₀ and reference current value is) is given and the start command arrives, the computer 24a
The following processing is performed at a predetermined cycle (sampling cycle; for example, 1 to 3 msec).

The computer 24a first reads the gap data (Gs *) and the current data (iLs) from the signal processing circuits 8a and 9a. Next, the region determination 22a determines which of the regions shown in FIG. 5 the gap (Gs *) and the current (iLs) are in. In this determination, first, it is determined whether the gap (Gs *) is in the above p = 1 to a, and the subsequently read current (iLs) is in any of the above q = 1 to b. It is determined (area information p, q). And
The memory table dj (one of the tables d1 to dn of FIG. 4) corresponding to the plate thickness d is specified from the plate thickness d information of the register 25a, and the specified memory table shown in FIG. -Specify one area of dj in the bull, and set the gain group there-
Reads M _{p, q} and writes it in the gain register 21a.
As a result, the specified plate thickness d and the current gap (Gs *)
And the gains K _{1 to} K ₄ corresponding to the current (iLs) are selected.

[0024] Computer 24a then calculates the gap deviation xL = Gs * -G ₀ by subtraction 10a, subtraction 12a
By subtracting the deviation one sampling cycle before held by the delay 11a from the current deviation xL, the change speed dxL / dt (hereinafter referred to as xL ') of the gap deviation is calculated,
The current deviation iL = iLs-is is calculated by the subtraction 18a, and the deviation accumulated value one sampling cycle before held by the delay 20a is added to the current deviation xL by the addition 19a.
Calculate the accumulated value (integrated value) ∫xLdt of the gap deviation. And multiplications 13a, 14a, 16a and 17a
Then, the gain data K of the gain register is added to these calculated values.
_{1 to} K ₄ is multiplied, and the subtraction 15a is performed to obtain the electric coil 1La.
Current level _{Ia out = is-K 1 ·} xL-K 2 · xL'-K 3 · iL-K 4 · ∫xLdt energizing calculates the de-express this - Output data to the PWM circuit 7a.

On the basis of this data Ia _out , the PWM circuit 7a supplies the electric coil 1La of the electromagnet 1L with the electric coil applied voltage (time-series average value) required for supplying the electric current Ia _out (ON / ON). OFF) Duty (H section length during one pulse period) is calculated, and the pulse of the duty is given to the coil driver 4L. Coil driver 4L
Makes the electric coil 1La conductive (ON) in response to the pulse H given by the PWM circuit 7a, and makes it non-conductive (OFF) in response to the pulse L.

As described above, the gap value Gs * and the coil current value iLs are read, these values are stored in the register 21a), the feedback output value is calculated using the set gain, and the output to the PWM circuit 7a is performed. , Computer 24
By repeating a in a predetermined cycle, the feedback gain is updated to a value corresponding to the gap and the coil current value which change every moment.

Please refer to FIG. 6 showing the control circuit 5B. The control circuit 5B, like the control circuit 5A, has a digital computer 24b mainly composed of a CPU and signal processing circuits 8b and 9b.
b and a PWM (pulse width modulation) circuit 7b. The PWM circuit 7b calculates the energization duty corresponding to the output data (current instruction value) of the computer 24b, and gives the energization instruction pulse of the calculated energization duty to the coil driver 4R. The coil driver 4R turns on / off the electric coil 1Ra in response to the energization instruction pulse. Thereby, a constant DC voltage is applied to the electric coil 1Ra at the energizing duty, and the voltage (time-series average value) of the electric coil 1Ra is determined by the energizing duty. That is, the voltage applied to the electric coil 1Ra is applied to the computer 2 via the coil driver 4R and the PWM circuit 7b.
4b.

The computer 24b shown in FIG. 6 has information regarding the magnetic plate FP to be controlled (plate thickness d, target gap G).
₀ and the reference current value is) are stored in the register 25b, and when the start command arrives, the applied voltage control of the electric coil 1Ra is started based on the information in the register 25b, and the stop command arrives. Then the electric coil 1
The power supply to Ra is stopped, and the control command such as the start is waited for. In controlling the voltage applied to the electric coil 1Ra, the signal processing circuit 8b is driven at a predetermined cycle (sampling cycle).
And 9b detection data (gap Gsc * and current iR
s) is read, voltage feedback information is generated by feedback calculation, and this is output to the PWM circuit 7b. This control operation is performed by digital processing according to a program. This control function is shown by being replaced with a hardware block (functional block) in FIG. 6 for easy understanding. Below, refer to this function block and computer 2.
The control operation of 4b will be described.

As described above, information regarding the magnetic plate FP to be controlled (plate thickness d, target gap G ₀ and reference current value i)
s) is given, the computer 24b stores it in the input register 25b. Then, when the start command arrives, the computer 24b performs the following processing at a predetermined cycle (sampling cycle; for example, 1 to 3 msec).

The computer 24b first reads the gap data (Gsc *) and the current data (iRs) from the signal processing circuits 8b and 9b. Next, by the area determination 22b,
It is determined which of the regions shown in FIG. 5 the gap (Gsc *) and the current (iRs) are in. In this determination, it is first determined whether the gap (Gsc *) is in the above p = 1 to a, and the current (iRs) read subsequently is q = 1 to the above.
It is determined which of the two is b (area information p, q). Then, the memory table (one of the tables d1 to dn in FIG. 4) corresponding to the plate thickness d is specified from the plate thickness d information of the register 25b, and the specified region information p and q is used for the specified FIG. One area of dj in the memory table shown in FIG. 3 is specified, the gain group Mp, q there is read, and the gain register 21 is read.
Write to b. As a result, the gain K ₁ corresponding to the specified plate thickness d, the current gap (Gsc *) and the current (iRs) is obtained.
~ K ₄ is selected.

[0031] Computer 24b then calculates the gap deviation xR = Gsc * -G ₀ by subtraction 10b, subtraction 12
b, the deviation one sampling cycle before held by the delay 11b is subtracted from the current deviation xR to calculate the gap deviation change speed dxR / dt (hereinafter referred to as xR '), and the subtraction 18b subtracts the current deviation iR = iRs-is is calculated, and the addition 19b is added to the current deviation xL and the deviation accumulated value one sampling cycle before held by the delay 20b to calculate the accumulated value (integrated value) ∫xRdt of the gap deviation. . And the multiplications 13b, 14b, 16b and 1
7b, the gain value of the gain register is added to these calculated values.
The electric coil 1 is multiplied by K _{1 to} K ₄ and subtracted 15b.
Calculating a current level _{Ib out = is-K 1 ·} xR-K 2 · xR'-K 3 · iR-K 4 · ∫xRdt be energized Ra, de express this - Output data to the PWM circuit 7b .

On the basis of this data Ib _out , the PWM circuit 7b supplies the electric coil 1Ra of the electromagnet 1R with the electric coil applied voltage (time-series average value) required for supplying the electric current Ib _out (ON / ON). OFF) Duty (H section length during one pulse period) is calculated, and the pulse of the duty is given to the coil driver 4R. Coil driver 4R
Makes the electric coil 1Ra conductive (ON) in response to the pulse H given by the PWM circuit 7b, and makes it non-conductive (OFF) in response to the pulse L.

As described above, the gap value Gsc * and the coil current value iRs are read, and the feedback gain corresponding to these values and the plate thickness d is set (read from the memory 23b and stored in the register 21b) and set. The computer 24b repeats the calculation of the feedback output value using the gain and the output to the PWM circuit 7b in a predetermined cycle so that the feedback gain corresponds to the gap and the coil current value which change every moment. Will be updated.

Please refer to FIG. 1 and FIG. FIG. 7A shows Maxwell stress Fx when the magnetic poles on the end faces of the facing electromagnets 1L and 1R have different polarities, and FIG.
The stress Fx of Maxwell when the magnetic poles of the end faces of the electromagnets 1L and 1R are the same is shown in FIG. As can be understood from this, when the magnetic poles of the facing electromagnets have different poles, the reference line L of the ferromagnetic plate FP shown in FIG.
The electromagnetic force acting on the ferromagnetic plate FP is large with respect to the lateral displacement Δx from xs. This is because when the end faces of the facing electromagnets have the same polarity, the magnetic forces emitted from the end faces repel each other,
Since the magnetic force lines are dispersed, the magnetic flux density in the ferromagnetic plate FP portion becomes low, and the magnetic force becomes weak. Therefore, the lines of magnetic force are generated in the direction indicated by the two-dot broken line arrow in FIG. 1 and converge in the direction traversing the ferromagnetic plate FP, the magnetic flux density of the ferromagnetic plate FP increases, and the electromagnetic force increases. Because it becomes stronger.

The fact that the electromagnetic force acting on the ferromagnetic plate FP with respect to the displacement Δx is large means that a large electromagnetic force can be obtained with a small current, and the response is excellent with a small capacity power source. Position control is possible.

According to the above embodiment, the electromagnet 1
Direct current is applied to L and 1R, and the electromagnets 1L and 1R
The displacement of the ferromagnetic material plate FP in the thickness direction x is controlled by the attraction force generated by, and the ferromagnetic material plate FP is always kept at the reference position Lxs, and the vibration of the ferromagnetic material plate FP is suppressed. Furthermore, the electromagnets 1L, 1
Since R controls the position of the ferromagnetic plate FP in a non-contact manner, and since the flat plate surface of the ferromagnetic plate FP does not stick to the end face of the electromagnet core, the ferromagnetic plate FP is flawed. There is no.

The thickness d of the ferromagnetic plate FP and the electromagnet 1
Current i applied to L and 1R and electromagnet / ferromagnetic material plate F
The optimum gain K corresponding to the inter-P gaps Gs and Gsc is read from the memories 23a and 23b, and is used to supply the current i.
a _out, since to calculate the ib _out, matched suction force is automatically generated in the gap between the thickness and the current i and the electromagnet / ferromagnetic plate FP of the ferromagnetic plate FP.

In the above embodiment, the coil drivers 4L,
The DC constant voltage is chopped by PWM control by 4R and applied to the electric coils 1La and 1Ra, and the chopping duty (energization period / (energization period + interruption period))
Is adjusted to determine the energization level, but the electric coils 1La and 1Ra may be energized with alternating current. For example, a thyristor is used as the current-carrying elements of the coil drivers 4L and 4R, and an AC current of a level indicated by the control circuits 5A and 5A is controlled by conducting phase control of the thyristor.
La and 1Ra may be energized, or the coil drivers 4L and 4R may be AC chopping circuits.
By the chopping duty control, the control circuit 5A,
AC coil of the level indicated by 5A is supplied to the electric coil 1La,
You may make it energize to 1Ra.

[0039]

According to the present invention, the magnetic force generated by the electromagnets 1L and 1R always keeps the magnetic plate FP at the reference position, and at the same time, the magnetic poles generated on the end faces of the electromagnets 1L and 1R facing each other have different polarities. As a result, it is possible to obtain a position control device that is a small-capacity power supply and that has a large responsiveness to the displacement Δx and that has a large electromagnetic force acting on the magnetic plate FP. Further, since the electromagnets 1L and 1R control the attitude of the magnetic plate FP in a non-contact manner, and since the side surface of the magnetic plate FP does not stick to the end face of the electromagnet core, the electromagnets 1L and 1R come into contact with the electromagnets 1L and 1R. The magnetic plate FP is never scratched.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention.

2 is a perspective view showing electromagnets 1L and 1R surrounded by a two-dot broken line frame 2a shown in FIG. 1. FIG.

FIG. 3 is a block diagram showing a schematic configuration of a control circuit 5A shown in FIG.

4 is a block diagram schematically showing memory areas of a memory 23a shown in FIG. 3 and a memory 23b shown in FIG.

5 is a block diagram showing the contents of a memory table dj shown in FIG.

6 is a block diagram showing a schematic configuration of a control circuit 5B shown in FIG.

7A is a graph showing Maxwell stress Fx acting on the magnetic plate FP when the magnetic poles on the end faces of the electromagnets 1L and 1R shown in FIG. 1 have different polarities, and FIG. ,
3 is a graph showing Maxwell stress Fx when the magnetic poles of the end faces of the electromagnets 1L and 1R shown in FIG. 1 have the same polarity.

[Explanation of symbols]

1L, 1R: Electromagnet 1La, 1Ra: Electric coil 1Lb, 1Rb: Core 3: Gap sensor 4L, 4R: Coil driver 5A, 5B: Control circuit 7a, 7b: PWM circuit 8a, 8b: Signal processing circuit 9a, 9b: Signal Processing circuit 22a, 22b: Area determination circuit 23a, 23b: Memory 24a, 24b: Computer FP: Magnetic plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI H01F 7/20 H01F 7/20 Z (58) Fields investigated (Int.Cl. ⁷ , DB name) B21B 39/00 B21C 47 / 34 B65G 54/02 B65H 23/00 F16F 15/03

Claims (7)

(57) [Claims] 1. A first electromagnet and a second electromagnet whose magnetic pole end faces face each other perpendicularly to a wide surface of the magnetic substance plate; a first gap between the magnetic pole end face of the first electromagnet and the magnetic substance plate is constant. A first energizing means for supplying a current to the first electric coil of the first electromagnet; and a first gap so that the second gap between the magnetic pole end surface of the second electromagnet and the magnetic plate becomes constant. A magnetic material plate positioning device, comprising: second passing means for supplying a current, which has a polarity opposite to that of the magnetic pole end surface of the second electromagnet, to the second electric coil of the second electromagnet. 2. A first electromagnet and a second electromagnet having magnetic pole plates facing each other perpendicularly to a wide surface of the magnetic body plate; corresponding to a first gap between the magnetic pole end surface of the first electromagnet and the magnetic plate. Then, when it is large, a high level is small and a low level current is supplied to the first electric coil of the first electromagnet; first energizing means; and a second end of the magnetic pole end surface of the second electromagnet and the magnetic plate. When the gap is large corresponding to the gap, the high level is small, and when the gap is small, a low level current having a polarity opposite to the polarity of the magnetic pole end surface of the first electromagnet with respect to the polarity of the magnetic pole end surface of the second electromagnet is generated. 2. A second energizing means for energizing the electric coil; 3. A gap detecting means for detecting the first gap is further provided; the first energizing means determines a current level for energizing the first electric coil corresponding to the first gap detected by the gap detecting means; Item 2. A magnetic plate positioning device according to item 2 . 4. A gap calculating means for calculating a second gap between the magnetic pole end surface of the second electromagnet and the magnetic plate based on the first gap detected by the gap detecting means; The magnetic plate positioning device according to claim 3, wherein a current level to be applied to the second electric coil is determined corresponding to the second gap calculated by the gap calculating means. 5. The first energizing means and the second energizing means energize the first and second electric coils with a current having a level corresponding to a deviation of the first and second gaps with respect to a given target gap. Item 4. A magnetic plate positioning device according to item 4 . 6. The device further comprises current detection means for detecting the value of the current flowing in the electric coils of the first and second electromagnets;
The first energizing means multiplies a deviation of the first gap with respect to the target gap and a deviation of the current value of the first electric coil with respect to the reference current value by a feedback gain corresponding to the first gap, and a given reference current value. A current of a level corresponding to the second electric coil is applied to the first electric coil; and a second energizing means determines a deviation of the current value of the second electric coil from a deviation of the second gap from the target gap and a reference current value.
6. The magnetic plate positioning device according to claim 5 , wherein a value obtained by multiplying a feedback gain corresponding to a gap and a current having a level corresponding to a given reference current value are passed. 7. The first and second energizing means respectively include a memory means storing a feedback gain corresponding to the gap and the electric coil current value, and a field corresponding to the gap and the electric coil current value at each time point. The magnetic plate positioning device according to claim 6 , further comprising: a gain setting unit that reads a feedback gain from the memory unit.