JP3110483B2 - Permanent electromagnetic chuck power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation power supply for driving a so-called permanent electromagnetic chuck for holding a ferromagnetic material (hereinafter referred to as a "work") to be worked by a magnetic force.

[0002]

2. Description of the Related Art There are a so-called magnetic chuck which attracts a ferromagnetic material using a magnetic force and holds it at a predetermined position, and there are an electromagnetic type, a permanent magnetic type and a permanent electromagnetic type. A permanent electromagnetic chuck (hereinafter referred to as a permanent electromagnetic chuck) includes a permanent magnet and a coil for exciting the permanent magnet inside, and maintains the state of the magnetic force when the permanent magnet is not excited. Utilizing the nature. That is, by feeding a current to the exciting coil and magnetizing, demagnetizing or magnetizing in the opposite direction, the magnetic flux that appears on the chucking surface of the chuck is controlled, and the work is sucked and peeled. The permanent electromagnetic chuck does not have the drawback that the chucking force is lost when the electromagnetic chuck loses power, and does not have the drawback that the handle operation during the suction and peeling operations of the permanent magnetic chuck is heavy.

FIG. 8 is a plan view of such a permanent electromagnetic chuck,
FIG. 9 is a cross-sectional view taken along the line XX ′ in FIG. 8, and corresponding portions in both the drawings are denoted by the same reference numerals.

First, permanent magnets m1 to m12 are arranged at substantially equal intervals on the bottom surface of a container 1 constituting a part of a magnetic circuit of a permanent electromagnetic chuck. The permanent magnets m1 to m12 are in the shape of a prism or a cylinder, and the exciting coils L1 to L12 are respectively wound therearound or the current direction is determined so that adjacent magnetic poles are magnetized to different polarities. On the upper part of the container 1, a face plate 4 in which polarizing materials 2 and magnetic pole members 3 are alternately arranged is placed so as to be in close contact with each permanent magnet. The work 5 is placed on the face plate 4.

In the permanent electromagnetic chuck, when the work 5 is attracted, the exciting coils L1 to L12 are divided into an appropriate number of groups, for example, groups A and B as shown in FIGS. With an appropriate value, a positive sine wave pulse-like excitation current is supplied to each of the excitation coils L1 to L12 to change the permanent magnets m1 to m12 from the demagnetized state to the magnetized state. When the work 5 is not attracted, a negative sine wave pulse-like exciting current is supplied to each of the exciting coils L1 to L12 to excite the permanent magnets m1 to m12 in a direction opposite to the magnetizing direction, thereby making the magnets magnetic. And demagnetize.

Since a large amount of power is required for the magnetization or demagnetization of the permanent magnets m1 to m12, a large-capacity power supply device for supplying the power for the magnetization is required. When such a power supply device is connected, the power supply equipment of a factory is greatly affected by the use of the power supply device. In particular, a permanent electromagnetic chuck requires a relatively wide attracting surface, and the required power becomes large because of the large number of permanent magnets.

[0007]

For this reason, it is important in terms of cost to perform sufficient magnetization with less power and to reduce the number of circuit elements by connecting in series an exciting coil through which a large current flows. Issues.

In order to solve such a problem, a method of exciting the permanent magnet in a time-division manner is considered. Permanent magnets maintain their magnetic state once magnetized or demagnetized,
As shown in the figure, the excitation coils of the permanent electromagnetic chuck are divided into several groups, for example, A and B groups, and the excitation divided into positive half-wave rectification and negative half-wave rectification for each coil group. Then, the power required for one excitation can be small.

The measurement results of the magnetic flux of the permanent electromagnetic chuck by such excitation will be described with reference to FIGS.
FIG. 12 is a plan view of the permanent electromagnetic chuck, and FIG. 13 is a cross-sectional view along the line XX ′ in FIG. FIG.
In FIG. 13 and FIG. 13, parts corresponding to those in FIG. 8 and FIG. 9 are denoted by the same reference numerals, the face plate 4 is removed for measuring the generated magnetic flux, and a 50 × 75 × 180 mm iron plate test work 5
And the gap between the 70 × 70 mm magnetic poles m6 and m7 is 1.6
The magnetic flux density was measured at a central portion a of the magnetic pole m6, a peripheral portion b of the magnetic pole m6, a central portion d of the magnetic pole m7, and a peripheral portion c of the magnetic pole m7 with a hole detector (not shown). The result is shown in FIG.

[0010] The first column of FIG.
A half-wave pulse current was supplied to only the group A excitation coil group for 0.2 seconds (10 pulses) to excite it, and the magnets m1, m2, m5, m6, m9 and m10 were magnetized. The magnetic flux density (unit: kilogauss) at the above points a to d in the case is shown. The second column in the figure shows that after the magnets of the group A have been magnetized, only the exciting coil groups of the group B are similarly excited for 0.2 seconds, and the magnets m3, m4, m7, m8,.
It shows the magnetic flux density (unit: kilogauss) at points a to d when magnetizing m11 and m12.

As can be seen from the results, when each group is excited in a time-division manner, there is a problem that the magnetic force of the first magnetized portion becomes weaker at the end of the magnetic pole at the boundary between the two groups.

Accordingly, it is an object of the present invention to provide a power supply device for a permanent electromagnetic chuck which can perform sufficient and uniform magnetization with smaller power.

[0013]

In order to achieve the above object, the present invention comprises a plurality of permanent magnets, each of which is arranged such that the pole faces of adjacent permanent magnets alternately form different polarities, An exciting coil is wound around each of the permanent magnets.
The magnetizing force of the permanent magnet is supplied to energize the magnetic force of the permanent magnet to attract the work made of a magnetic material to the face plate, and the magnetizing force of the permanent magnet is supplied by supplying the magnetizing current of the second polarity for demagnetizing. In a power supply device for a permanent electromagnetic chuck for releasing a work from a work surface plate, a plurality of excitation coils wound around a plurality of permanent magnets are connected to a first excitation coil group having substantially equal impedance and a second excitation coil group.
And the first excitation coil group
The polarity of each excitation coil is determined by the supply of current on one side.
The second excitation coil is connected in the direction to generate the magnetizing magnetomotive force.
In the group of coils, the polarity of each excitation coil is used to supply the current on the other side.
Therefore, the first pair of control rectifiers connected in the direction of generating the magnetomotive force of magnetization and connected in series to the first excitation coil group, and connected in series to the second excitation coil group. A rectifier circuit including a second pair of control rectifiers connected in anti-parallel, and turning on one of the first pair of control rectifiers at the time of chucking the work to connect the first excitation coil group to one of the AC power supplies. A half-wave rectification pulse of the polarity is supplied, and one of the second pair of control rectifiers is turned on to supply a second-wave half-rectification pulse of the AC power to the second group of exciting coils, thereby releasing the work. At the same time, the other of the first pair of control rectifiers is turned on to supply a half-wave rectification pulse of the other polarity of the AC power supply to the first excitation coil group, and the other of the second pair of control rectifiers is turned on. To the second excitation coil group Characterized by comprising a control unit for controlling the rectifier circuit to supply a half-wave rectified pulses sex.

[0014]

The plurality of exciting coils of the permanent electromagnetic chuck are divided into sets corresponding to the number of phases of the AC power supply, for example, two sets when a single-phase AC power supply is used. The alternating current is half-wave rectified, and one set of exciting coils is excited with the obtained positive current, and the other set of exciting coils is excited with the negative current.

[0015] In this way, it is possible to complete in a short time and a small peak current magnetization or demagnetization of the permanent magnet, sine wave AC power supply current is positive-negative symmetrical with the power source
It becomes a flow.

[0016]

FIG. 1 shows an embodiment of a power supply device for a permanent electromagnetic chuck according to the present invention.
An alternating current is supplied to the rectifier circuit 10 from the commercial power supply z. The rectifier circuit 10 has two functions of a switch for interrupting power supply and a rectifier for obtaining a sinusoidal pulse current. Specifically, two sets of half-waves whose conduction is controlled by the control output of the control unit 11 are provided. It is composed of a rectifier circuit. 1
The set of half-wave rectifier circuits includes a rectifier that rectifies an AC current and outputs a pulsed current in a positive direction, and a rectifier that rectifies the AC current and outputs a pulsed current in a negative direction. By providing two sets of these, a magnetized output and a demagnetized output whose current directions are reversed are generated. Permanent electromagnetic chuck 12
Has at least two inductance circuits of group A and group B in which the same number of exciting coils are connected in series with each other. The currents in the positive direction and the negative direction are supplied to the exciting coils of the group A and the group B of the permanent electromagnetic chuck 12, respectively. When receiving an ON command to hold the work from a switch on a control panel (not shown), the control unit 11 supplies a control output for supplying a magnetizing current to the rectifying circuit 10 to a set of half-wave rectifying circuits for magnetizing. Further, when an off command to release the work is received from a switch on the control panel, a control output for supplying a demagnetizing current to the rectifying circuit 10 is supplied to another set of half-wave rectifying circuits for demagnetizing. Whether the permanent electromagnetic chuck 12 is in the holding state or the release state is determined by the indicator light 13 controlled according to the state of the control output of the control unit 11.
It is indicated by the lighting state of.

FIG. 2 shows an example of the configuration of the exciting coil circuit of the rectifier circuit 10 and the permanent electromagnetic chuck 12. The rectifier circuit 10 includes, for example, silicon-controlled rectifiers SCR1a and SCR2a connected in parallel in opposite directions, and SCR1
b and SCR2b. Silicon controlled rectifiers SCR1a and S
CR1b is given the same magnetization control output. The silicon controlled rectifiers SCR2a and SCR2b are provided with the same demagnetization control output. The exciting coil circuit divides the exciting coil into the same number of A and B groups,
Are connected between positive output and neutral and between negative output and neutral. Silicon controlled rectifier SCR1a
While the control output is being applied to both gates of the SCR1b and SCR1b, the positive half-wave pulse current of the alternating current is supplied to the excitation coil group of the A group, and the negative current is supplied to the excitation coil group of the B group. Explaining with the permanent electromagnetic chuck method shown in FIGS. 8 and 9, the excitation coil group of the group A is connected in such a direction that the polarity of each excitation coil generates a magnetizing force by the supply of a positive current. The excitation coil group of group B is
The polarity of each excitation coil is connected in such a direction as to generate a magnetomotive force for magnetization by supplying a negative current. As a result, when a control output is applied to both gates of the silicon controlled rectifiers SCR1a and SCR1b, the positive side current of the AC current becomes A
A negative current is supplied to the group of excitation coils in the group B. The work is attracted to the face plate by exciting current flowing through each exciting coil. An appropriate period of time for supplying the exciting current is determined according to the characteristics of the permanent electromagnetic chuck.

When an OFF command is issued, the control unit 11 applies a control output including current adjustment to both gates of the silicon controlled rectifiers SCR2a and SCR2b for a period applicable to the gate. As a result, a current in the opposite direction to that when the silicon controlled rectifiers SCR1a and SCR1b are turned on flows through each excitation coil, thereby canceling the residual magnetism of the permanent magnet. Thus, the work is released .

FIG. 5 shows the same exciting current as the magnetic flux generated when each exciting coil of the permanent electromagnetic chuck is driven by the power supply device shown in FIG. 2 and the magnetic flux generated by the conventional exciting device shown in FIG. 10 and the split exciting circuit shown in FIG. The results are compared in terms of the number of pulses. In each case, 20 half-wave current pulses were applied from a power supply of 50 Hz and 200 V AC.

In the practical circuit, the exciting current flowing through the line can be reduced to half that of the conventional circuit. Although the magnetic flux density is somewhat lower than that of the conventional circuit, the conventional 92.6-93.
0% can be secured. This means that substantially the same magnetization can be performed with a device having a current capacity of ２.

Further, the magnetic flux density is higher than that of the divided excitation circuit, and the variation in the value is small. In addition, the excitation time is a short time, which is の of the division excitation.

FIGS. 14 and 6 show the circuit of FIG.
1 shows a comparison of magnetization results when excitation is performed for the same time (0.2 seconds) by a power supply of 50 Hz and 200 V AC in one divided excitation circuit, and the present embodiment performs magnetization more uniformly, Is strong.

FIG. 3 shows that when the rectifier circuit 10 conducts,
5 shows a state of a transient current supplied from a commercial AC power supply. Although a half-wave waveform (sine-wave pulse-like) current flows through the A group and the B group, respectively, A certain alternating current flows.

Therefore, as compared with a configuration in which a commercial AC current is intermittently supplied to supply an exciting current and a half-wave waveform current is supplied as shown in FIGS. There is an advantage that it is possible to reduce a high-frequency disturbance to other devices and a current-voltage fluctuation.

FIG. 4 shows another embodiment of the present invention, and shows an example in which a commercial three-phase AC power supply is used in the permanent electromagnetic chuck system of FIG. Referring to FIG.
Excitation coils L1 and L2 of group A are driven by the positive current of the phase. The excitation coils L3 and L4 of the B group are driven by the negative current of the R phase. Excitation coils L5 and L6 of group A are driven by the S-phase positive current. The excitation coils L7 and L8 of the B group are driven by the negative current of the S phase. The excitation coils L9 and L10 of the A group are driven by the positive current of the T phase.
The excitation coil L11 of the B group is generated by the negative current of the T phase.
And L12 are driven. Silicon control rectifier SCR
When a control output is supplied to the gates of 1a to SCR1f,
An exciting current flows through each exciting coil in the forward direction, and the permanent magnets m1 to m12 (not shown) are magnetized. When a control output is supplied to the gates of the silicon controlled rectifiers SCR2a to SCR2f, an exciting current flows in the opposite direction to each exciting coil, and the permanent magnets m1 to m12 are magnetized in the opposite direction.

In this embodiment, the excitation coil has a three-phase Y connection, but it is of course possible to use a three-phase Δ connection or a V connection. For example, the excitation coils can be grouped into four groups for V connection and six groups for Δ connection. Further, it is possible to drive a plurality of groups of excitation coils by a polyphase alternating current by converting a three-phase voltage into a six-phase voltage. In this way, more exciting coil groups are excited at once.
It is possible to do.

FIG . 15 shows an embodiment in the case of the aforementioned Δ connection.
It is something. In the figure, the RS phase of a three-phase AC power supply is shown.
Excitation coils L1 and A1 of group A
L2 is driven. Due to the negative current between the R and S phases, B
The exciting coils L3 and L4 of the loop are driven. ST
Excitation coil L5 and A5
And L6 are driven. B due to the negative current between the ST and T phases
The excitation coils L7 and L8 of the group are driven. T-
Excitation coil L9 of group A by positive current between R phases
And L10 are driven. The negative current between the T and R phases
As a result, the excitation coils L11 and L12 of the group B are driven.
You. Silicon control rectifiers SCR1a to SCR1f
When the control output is supplied to the
Excitation current flows in the forward direction, and permanent magnets m1 to m12 are magnetized
Is done. In addition, silicon control rectifiers SCR2a to SC
When the control output is supplied to the gate of R2f, each excitation coil
Excitation current flows in the opposite direction to the permanent magnets m1 to m
12 is magnetized in the opposite direction.

FIG. 7 shows another example of a permanent electromagnetic chuck to which the power supply circuit of the present invention is applied. The variable permanent magnet whose polarity is reversed by an exciting coil, and the fixed permanent magnet whose polarity is fixed are shown. 5 shows an example in which a permanent electromagnetic chuck is configured using the above. When the variable-polarity permanent magnet mi and the fixed-polarity permanent magnet hi adjacent to each other have the same polarity for the magnetic poles adjacent to each other, a magnetic force is generated on the chuck surface. No magnetic force is generated.

[0029]

As described above, the power supply device for the permanent electromagnetic chuck according to the present invention utilizes both the positive side and the negative side of the one-phase alternating current, and these are respectively divided into separate groups of exciting coils. Since the arrangement is such that the two groups are alternately excited within one cycle of the distribution, the peak value of the total exciting current is reduced by half compared to the conventional circuit in which all the exciting coils are excited in a short time by a large current pulse. Not only reduces the current capacity of the circuit elements , but also provides sufficient and uniform magnetization.
This makes it possible to reduce the size and cost of the device. Also, the excitation time is shorter and the magnetic force is larger than in the split excitation method. Since the current supplied from the power supply is a sine wave, there is little adverse effect on the power supply side due to current interruption as in the prior art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline (time division excitation) of the present invention.

FIG. 2 is a circuit diagram illustrating a rectifier circuit 10 and a permanent electromagnetic chuck 12 shown in FIG.

FIG. 3 is a waveform diagram showing a waveform of a current flowing in an AC power supply.

FIG. 4 is a circuit diagram showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining effects of the embodiment.

FIG. 6 is an explanatory diagram for explaining effects of the embodiment.

FIG. 7 is a sectional view showing another configuration example of the permanent electromagnetic chuck 12.

FIG. 8 is an explanatory diagram for explaining a permanent electromagnetic chuck.

9 is a cross-sectional view of the permanent electromagnetic chuck shown in FIG. 8, taken along line XX '.

FIG. 10 is a circuit diagram for explaining simultaneous excitation of a conventional device.

FIG. 11 is a circuit diagram for explaining split excitation of a permanent electromagnetic chuck.

FIG. 12 is an explanatory diagram for explaining a permanent electromagnetic chuck.

FIG. 13 is an explanatory diagram for explaining measurement of the magnetic flux density of the permanent electromagnetic chuck.

FIG. 14 is an explanatory diagram for explaining a measurement result of a magnetic flux density.

FIG. 15 is a circuit diagram showing a modification of the embodiment shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Polarizing material 3 Magnetic pole member 4 Face plate 5 Work L1-L12 Excitation coil m1-m12 Permanent magnet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-217605 (JP, A) JP-A-63-251139 (JP, A) JP-A-62-157750 (JP, A) 280380 (JP, A) JP-A-3-283606 (JP, A) JP-A-1-166035 (JP, U) JP-A-4-97313 (JP, U) JP-B-61-31604 (JP, B2) (58) Field surveyed (Int.Cl. ⁷ , DB name) B23Q 3/154 B25J 15/06 B65H 3/16

Claims (1)

(57) [Claims] 1. A permanent magnet comprising a plurality of permanent magnets, wherein each permanent magnet is arranged such that magnetic pole surfaces of adjacent permanent magnets alternately form different polarities, and an exciting coil is wound around each permanent magnet. Rectified by the AC excitation coil
The magnetizing force of the permanent magnet is supplied to energize the magnetic force of the permanent magnet to attract the work made of a magnetic material to the face plate, and the magnetizing current of the second polarity is supplied to the permanent magnet to supply the magnetizing force. A power supply unit for a permanent electromagnetic chuck for canceling a magnetic force and releasing a work from the face plate, wherein a plurality of excitation coils wound around the plurality of permanent magnets are a first excitation coil group and a second excitation coil having substantially equal impedance. A first excitation coil divided into groups;
In the group, the polarity of each excitation coil is controlled by the current supply on one side.
In the direction in which the magnetomotive force for magnetization is generated,
In the excitation coil group of, the polarity of each excitation coil is set to the other side.
Connected in the direction that generates the magnetizing magnetomotive force
A first pair of anti-parallel control rectifiers connected in series to the first excitation coil group, and a second pair of anti-parallel connection connected in series to the second excitation coil group A rectifier circuit comprising a control rectifier element of the type described above, and turning on one of the first pair of control rectifier elements at the time of chucking the workpiece to supply a half-wave rectification pulse of one polarity of an AC power supply to the first excitation coil group. Supply, and turn on one of the second pair of control rectifier elements to supply the second excitation coil group with a half-wave rectification pulse of the other polarity of the alternating current power supply. The other of the first pair of control rectifiers is turned on to supply a half-wave rectification pulse of the other polarity of the AC power supply to the first excitation coil group, and the other of the second pair of control rectifiers is supplied to the first excitation coil group. Turn on the AC to the second excitation coil group A control unit for controlling the rectification circuit so as to supply a half-wave rectification pulse of one polarity of a power supply.