JPH05116083A - Electric power supply device of permanent electromagnetic chuck - Google Patents

Abstract

PURPOSE:To accomplish enough and uniform magnetizing with a comparative small electric power by using both positive side and negative side currents in monophasic a.c. current, and distributing the currents to groups of exciting coils, and exciting two groups alternately within one cycle. CONSTITUTION:An a.c. current from a commercial power supply is supplied to a rectifying circuit 10. The rectifying circuit 10 comprises two sets of half- wave type rectifying circuits controlled in their conductivity by the control output of a control unit 11, so that the magnetizing output and demagnetizing output, the current directions of which are judged mutually are generated. On the other hand, inductance circuits of plural groups A, B where the same number of exciting coils are connected in series to each other are provided on a permanent electromagnetic chuck 12. Furthermore the lighting condition of an indicating lamp 13 indicates whether the permanent electromagnetic chuck 12 is in the held state or in the released state. In the control portion 11, the control output for supplying magnetizing current or demagnetizing current to the rectifying circuit 10 is supplied to the respective half-wave rectifying circuits for magnetizing or demagnetizing.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art There are an electromagnetic type, a permanent magnetic type, and a permanent electromagnetic type as a so-called magnetic chuck that attracts a ferromagnetic material by using a magnetic force and holds it at a predetermined position. A permanent electromagnetic chuck (hereinafter referred to as a permanent electromagnetic chuck) is provided with a permanent magnet and a coil for exciting the permanent magnet inside, and maintains that magnetic force when the permanent magnet is not excited. Take advantage of nature. That is, by applying a current to the exciting coil to magnetize, demagnetize or magnetize in the opposite direction, the magnetic flux generated on the chucking surface of the chuck is controlled, and the workpiece is attracted and separated. Permanent electromagnetic chucks do not have the drawback that the chucking force disappears when the electromagnetic chuck loses power, and that permanent magnet chucks do not have the drawback of heavy handle operation during suction and peeling operations.

FIG. 8 is a plan view of such a permanent electromagnetic chuck.
FIG. 9 shows a cross-sectional view in the XX ′ direction in FIG. 8, and the corresponding parts in both figures are given the same reference numerals.

First, the permanent magnets m1 to m12 are arranged at substantially equal intervals on the bottom surface of the container 1 forming a part of the magnetic circuit of the permanent electromagnetic chuck. The permanent magnets m1 to m12 are prisms or cylinders, and exciting coils L1 to L12 are wound around the respective magnetic poles so that adjacent magnetic poles are magnetized to have different polarities, or the current direction is determined. On the upper part of the container 1, a face plate 4 in which a polarizing material 2 and a magnetic pole member 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 this 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, A and B groups as shown in FIGS. A proper value is applied to each of the exciting coils L1 to L12 to supply a positive direction sinusoidal pulsed exciting current 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 sinusoidal pulse-shaped exciting current is supplied to each of the exciting coils L1 to L12 to excite the permanent magnets m1 to m12 in the direction opposite to the magnetizing direction. To cancel the demagnetization.

Since a large amount of electric power is required to magnetize or demagnetize the permanent magnets m1 to m12, a large-capacity power supply device is required to supply the electric power for magnetizing. When such a power supply device is connected, the power supply equipment of the factory is greatly affected by the use of the device. In particular, the permanent electromagnetic chuck requires a relatively wide attracting surface, and since the number of permanent magnets is large, it also requires a large amount of power.

[0007]

For this reason, it is important in terms of cost to perform sufficient magnetization with a smaller power and to connect the exciting coils in which a large current flows in series to reduce the number of circuit elements. It becomes a problem.

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

The measurement result of the magnetic flux of the permanent electromagnetic chuck by such excitation will be described with reference to FIGS. 12 and 13.
FIG. 12 is a plan view of the permanent electromagnetic chuck, and FIG. 13 is a sectional view taken along line XX ′ in FIG. 12
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 to measure the generated magnetic flux, and the test work 5 of the iron plate of 50 × 75 × 180 mm is used.
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 and a peripheral edge portion b of the magnetic pole m6, a central portion d of the magnetic pole m7 and a peripheral edge portion c of the magnetic pole m7 by a Hall detector (not shown). The result is shown in FIG.

The first column of FIG. 14 shows the switch of FIG.
Connected to the group and excited by supplying a half-wave pulse current for 0.2 seconds (10 pulses) only to the exciting coil group of group A, magnetizing magnets m1, m2, m5, m6, m9 and m10. The magnetic flux densities (unit: kilogauss) at the points a to d in the case are shown. In the second column of the figure, after magnetizing the magnets of the A group, only the exciting coil groups of the B group are similarly excited for 0.2 seconds, and the magnets m3, m4, m7, m8,
The magnetic flux densities (unit: kilogauss) at points a to d when m11 and m12 are magnetized are shown.

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

[0012] Therefore, an object of the present invention is to provide a power supply device for a permanent electromagnetic chuck which can perform sufficient and uniform magnetization with a smaller electric power.

[0013]

In order to achieve the above object, a power supply device for a permanent electromagnetic chuck according to the present invention rectifies an output current of an AC power supply to an exciting coil group wound around a plurality of permanent magnets of the permanent electromagnetic chuck. In a power supply device for a permanent electromagnetic chuck that supplies an exciting current obtained by the above, two sets of inductance series circuits formed by dividing the exciting coil group into substantially equal impedances and an output current of one phase of the AC power source Positive side pulsed current obtained by half-wave rectification is supplied to one of the inductance series circuits, and negative side pulsed current obtained by half-wave rectification of the output current is supplied to another of the inductance series circuits. It has a rectification circuit for supplying to.

[0014]

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

With this configuration, it becomes possible to complete the magnetization or demagnetization of the permanent magnet with a small peak current and in a short time, and a sine wave is supplied from the power supply.

[0016]

FIG. 1 shows an embodiment of a power supply device for a permanent electromagnetic chuck of the present invention, in which an alternating current is supplied to a rectifier circuit 10 from a commercial power supply of single phase 50 Hz or 60 Hz. The rectifier circuit 10 includes a switch for connecting and disconnecting power supply,
It has two functions of rectification to obtain a sinusoidal pulse current,
Specifically, it is composed of two sets of half-wave rectifier circuits whose conduction is controlled by the control output of the control unit 11. One set of half-wave rectifier circuits includes a rectifier that rectifies an alternating current and outputs a positive pulsed current, and a rectifier that rectifies the alternating current and outputs a negative pulsed current. By providing two sets of these, a magnetizing output and a demagnetizing output whose current directions are opposite to each other are generated. The permanent electromagnetic chuck 12 includes 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 positive and negative currents are supplied to the exciting coils of the A group and B group of the permanent electromagnetic chuck 12, respectively. When the control unit 11 receives an ON command for holding a work from a switch of a control panel (not shown), the rectifier circuit 1
A control output for supplying a magnetizing current to 0 is supplied to a pair of half-wave rectifying circuits for magnetizing. Further, when an OFF command for opening the work is received from the switch of the control panel, a control output for supplying the demagnetizing current to the rectifying circuit 10 is supplied to the other half-wave rectifying circuit for demagnetizing. Whether the permanent electromagnetic chuck 12 is in the holding state or the open state is indicated by the lighting state of the indicator lamp 13 which is controlled according to the state of the control output of the control unit 11.

FIG. 2 shows a configuration example of the exciting coil circuit of the rectifying circuit 10 and the permanent electromagnetic chuck 12. The rectifier circuit 10 is composed of, for example, four silicon controlled rectifier elements SCR1a and SCR2a and SCR1b and SCR2b which are connected in parallel in opposite directions. The same magnetization control output is given to the silicon control rectifying elements SCR1a and SCR1b. Silicon controlled rectifier S
The same demagnetization control output is given to CR2a and SCR2b.
The exciting coil circuit is configured by dividing the exciting coil into the same number of A and B groups and connecting these to the positive output-neutral and the negative output-neutral of the rectifier circuit 10, respectively. While the control output is applied to both gates of the silicon controlled rectifiers SCR1a and SCR1b, the positive half-wave pulse current of the alternating current is in the exciting coil group of group A and the negative side current is the exciting coil group of group B. Is supplied to. Figure 8,
Explaining with the permanent electromagnetic chuck system of FIG. 9, the exciting coil groups of the A group are connected in a direction in which the polarities of the exciting coils generate a magnetomotive force for magnetization by the supply of the positive side current. The exciting coil groups of the B group are connected such that the polarities of the exciting coils generate a magnetomotive force for magnetization by the supply of a negative current. As a result, when the control output is applied to both gates of the silicon controlled rectifying elements SCR1a and SCR1b, the positive side current of the alternating current is supplied to the exciting coil group of the A group and the negative side current is supplied to the exciting coil group of the B group. It The work is attracted to the face plate by the flow of the exciting current through each exciting coil. The supply period of the exciting current is set to an appropriate time according to the characteristics of the permanent electromagnetic chuck.

When the off command is issued, the control section 11 applies a control output including current adjustment to both gates of the silicon controlled rectifying elements SCR2a and SCR2b for an appropriate period. As a result, a current in the opposite direction to that when the silicon controlled rectifying elements SCR1a and SCR1b are turned on flows through each exciting coil to cancel the residual magnetism of the permanent magnet. In this way, the work is released.

FIG. 5 shows the same magnetic flux generated when the respective exciting coils of the permanent electromagnetic chuck are driven by the power supply device of FIG. 2 and the magnetic flux generated by the conventional exciting device of FIG. 10 and the split exciting circuit of FIG. The result of comparison in the number of pulses is shown, and 20 half-wave current pulses were applied by a power source of 50 Hz and AC200V.

In the embodied circuit, the exciting current flowing through the line can be reduced to half that of the conventional circuit. The magnetic flux density is slightly lower than that of the conventional circuit, but the conventional 92.6 to 93.
It is possible to secure 0%. This means that a device with a half current capacity can perform substantially the same magnetization.

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

14 and 6 show the implementation circuit of FIG. 2 and FIG.
It shows a comparison of the magnetization results when the excitation was performed at the same time (0.2 seconds) by the power supply of 50 Hz and AC200V in the divided excitation circuit of No. 1, and the present implementation circuit more uniformly magnetized the magnetic force. It turns out that is strong.

FIG. 3 shows that when the rectifying circuit 10 is turned on,
The figure shows the state of the transient current supplied from the commercial AC power supply. Even though the half-wave waveform (sine wave pulse-shaped) currents flow through the A group and the B group, respectively, the composite power of these waves is supplied to the AC power supply. A certain sine wave flows.

Therefore, as compared with the configuration of supplying a half-wave waveform current by intermittently supplying a commercial alternating current for supplying an exciting current as shown in FIGS. There is an advantage that it is possible to reduce high frequency interference to other devices and current / voltage fluctuations.

FIG. 4 shows another embodiment of the present invention, which is an example in which a commercial three-phase AC power source is used in the permanent electromagnetic chuck system of FIG. In the figure, R of three-phase alternating current
The group A exciting coils L1 and L2 are driven by the phase positive current. The exciting currents L4 and L5 of the B group are driven by the negative current of the R phase. The exciting coils L5 and L6 of the A group are driven by the positive current of the S phase. The exciting coils L7 and L8 of the B group are driven by the negative current of the S phase. Exciting coils L9 and L10 of the A group are driven by the positive current of the T phase. T
The negative side currents of the phases drive the exciting coils L11 and L12 of the B group. Silicon controlled rectifier SCR1a-S
When the control output is supplied to the gate of CR1f, an exciting current flows in the forward direction to each exciting coil, and the permanent magnets m1 to m12 (not shown) are magnetized. When a control output is supplied to the gates of the silicon controlled rectifying elements 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 exciting coil has a three-phase Y connection, but it can of course be a three-phase Δ connection or a V connection. For example, if the V connection is used, the exciting coils can be combined into 4 groups, and if the Δ connection is used, the exciting coils can be combined into 6 groups. Further, it is possible to drive a multi-group of exciting coils by a multi-phase AC by converting a three-phase voltage into a six-phase voltage.

By doing so, it becomes possible to excite more exciting coil groups at one time.

FIG. 7 shows another example of a permanent electromagnetic chuck to which the power supply circuit of the present invention is applied. The permanent magnet has a variable polarity whose polarity is reversed by an exciting coil and a fixed permanent magnet having a fixed polarity. An example is shown in which a permanent electromagnetic chuck is constructed by using. When the magnetic poles of the variable polarity permanent magnets mi and the adjacent polarity fixed permanent magnets hi adjacent to each other have the same polarity, magnetic force is generated on the chuck surface, and when they are of different polarities, a short circuit of magnetic flux is formed on the chuck surface. No magnetic force is generated.

[0029]

As described above, the power supply device for a permanent electromagnetic chuck of the present invention utilizes both positive and negative side currents of a one-phase alternating current, and these are provided to different groups of exciting coils, respectively. Since the configuration is such that the two groups are alternately excited within one cycle, the peak value of the total exciting current is halved compared to the conventional circuit that excites all exciting coils in a short time by a large current pulse. Therefore, the current capacity of the circuit element can be small, and the device can be downsized and the cost can be reduced. In addition, the excitation time is shorter than the split excitation method,
The magnetic force is large. Since the current supplied from the power supply is a sine wave, the current supply and disconnection does not adversely affect the power supply side.

[Brief description of 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 through 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 the effect of the embodiment.

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

FIG. 7 is a cross-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 taken along line XX 'of the permanent electromagnetic chuck shown in FIG.

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

FIG. 11 is a circuit diagram for explaining divisional 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 magnetic flux density of a permanent electromagnetic chuck.

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

[Explanation of symbols]

 1 Container 2 Polarizing Material 3 Magnetic Pole Member 4 Surface Plate 5 Workpiece L1 to L12 Excitation Coil m1 to m12 Permanent Magnet

Claims (1)

[Claims] 1. A power supply device for a permanent electromagnetic chuck, which supplies an exciting current obtained by rectifying an output current of an AC power supply to an exciting coil group wound around a plurality of permanent magnets of the permanent electromagnetic chuck, said exciting device comprising: An even number of inductance series circuits formed by dividing the coil group into substantially equal impedances, and a positive-side pulse-shaped current obtained by half-wave rectifying the output current of one phase of the AC power supply are used in the inductance series circuit. Power supply device for a permanent electromagnetic chuck, comprising a rectifying circuit for supplying a negative pulsed current obtained by half-wave rectifying the output current to another one of the inductance series circuits. ..