JPH0623595A - Pulse magnet exciting method for magnetic field press machine and its exciting power source device - Google Patents

Abstract

PURPOSE:To execute the magnetic field pressing in the high magnetic field and a short time by making a power source equipment that a pulse energizing current is made to flow in a coil of magnetic field. CONSTITUTION:When the charging operation is stopped by making gate signals of thyristors 2, 3, 4, 5 OFF, and gate signals of thyristors 10, 11 are instantly made to ON, the energy accumulated in a capacitor 9 generates the high magnetic field in a magnetic field coil 17. At the same time, a reverse direction resonance energy is accumulated in the charging capacitor 9. Successively, when gate signals of thyristors 12, 13 are instantly made ON, the second wave pulse energizing is executed to the same direction of the first wave pulse current. By repeating this operation, the powder of magnetic material packed in a metallic mold 17 inside the coil of magnetic field is formed with magnetic field pressing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse excitation method for a magnetic field press molding machine and a pulse excitation power supply device for the method. Generally, the magnetic field that can be generated in the electromagnetic coil in the conventional DC excitation method for magnetic field press molding of magnetic materials with high coercive force such as rare earth is limited to 15 kOe to 20 kOe (kilo-Oersted), but with this pulse excitation method. And the magnetic field that can be generated in the magnetic field coil is 30 kOe to 40 kO
The present invention relates to a pulse excitation method capable of obtaining a high magnetic field and a pulse excitation method capable of shortening the molding time by the pulse excitation method, and a pulse power source excitation device thereof.

[0002]

2. Description of the Related Art In magnetic field press molding, a molding die installed in an electromagnetic coil is filled with magnetic material powder, and a magnetic field is generated by the electromagnetic coil at the same time as the pressing is started to make the magnetic material anisotropic and magnetic field press molding. That is, as shown in FIG. 3, a magnetic field press molding machine, a fixed mold 23 mounted in a fixed electromagnetic coil 26 arranged on the fixed pre-22.
23A is filled with the magnetic material powder 29 and the frame 21 is filled.
A direct current is applied to the electromagnetic coil from the exciting power source with the movable mold 25 interlocking with the movable coil 27 arranged on the lower surface of the movable plate 24 located in the upper part of the inner space of the container while the fixed mold 23 is covered. Then, a closed magnetic circuit 28 is formed, and is anisotropic in the magnetic path direction indicated by the solid arrow in FIG. 3, and magnetic field press molding is performed. In this case, the magnetic field generated between the molding dies 23A and 25 is limited by the saturation magnetic field of the mold material and the magnetic fields generated by the electromagnetic coils 26 and 27 (at present, approximately 15 kOe.
20 kOe is the limit of the generated magnetic field). While applying to the electromagnetic coil, press to the thickness of the predetermined magnet to stop the excitation, apply a magnetic field in the opposite direction (called demagnetization field) to the electromagnetic coils 26 and 27 to erase the magnetic force of the magnet after molding and Makes it easy to remove from the mold. FIG. 4 shows the exciting current supplied to the electromagnetic coil, the demagnetizing current, and the operation relationship of the magnetic field press molding machine.
It takes about 0 seconds.

[0003]

As described above, in the conventional magnetic field press molding by direct current excitation, there is a limit to the magnetic field that can be generated during pressing. As a natural result of the recent demand for high coercive force for magnetic materials, even in magnetic field press molding, the magnetic field generated in the electromagnetic coil is also 30 kOe to 40 kO.
A high magnetic field of e is required. In the conventional method of generating a magnetic field between the magnetic poles of a mold using a closed magnetic circuit, the magnetic field is difficult due to the saturation characteristics of the material used for the mold. It is an object of the present invention to generate an infinite high magnetic field by supplying a pulse excitation current to a magnetic field coil with an air core regardless of the material of the molding die, the magnetic path of the molding machine frame, etc. A magnetic field press molding machine is applied to a magnetic field coil to provide a pulse excitation method for anisotropically molding a magnetic material and its pulse power supply device.

[0004]

According to a first aspect of the present invention, in a pulse excitation method for a magnetic field press molding machine, a combination of a thyristor is applied by applying a resonance action between energy stored in a capacitor and a magnetic field coil. According to the above, a circuit mechanism for periodically applying a pulse current a plurality of times in the same direction is provided. A second aspect of the present invention is a pulse excitation power supply device for a magnetic field press molding machine, which is equipped with a magnetic field coil and is used for magnetic field press molding of magnetic material powder filled in a mold attached to the magnetic field press molding machine. In the above, in the magnetic field coil, the energy charged and accumulated in the capacitor is instantaneously discharged to generate a high magnetic field in the magnetic field coil, and the resonance between the capacitor and the magnetic field coil incorporated in the power supply device is completed in order to complete the magnetic field press molding. Utilizing the phenomenon, the resonance energy of the capacitor is reversely charged at the same time as the excitation of the first wave pulse, and the energy of the second wave is excited by the combination of the thyristor in the same direction as the first wave pulse current. In the process of repeating the above operation, the magnetic material powder filled in the magnetic field coil mold is subjected to magnetic field press molding.

[0005]

The operation of the above means is as follows. That is, a magnetic field coil is provided, and a capacitor is provided in the excitation power supply device.
The energy charged by DC is instantaneously discharged to the magnetic field coil. Then, using the L and C resonance phenomena, a pulse current in the same direction is periodically supplied to the magnetic field coil several times 30 kOe to 4
A high magnetic field of 0 kOe is periodically generated by a pulse current, and during this period, magnetic material powder can be subjected to anisotropic magnetic field press molding.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a power supply circuit diagram used in a pulse excitation power supply for a magnetic field press molding machine according to the present invention, and FIG. 2 is a diagram showing a flow of a resonance pulse current.

In FIG. 1, the transformer 1 is a thyristor.
The charging capacitor 9 is charged at a high voltage by a circuit in which 2, 3, 4, 5 and the resistor 6 and the capacitors 7 and 8 are composed of a double voltage rectification circuit. Thyristor 10, 11, 1
Reference numerals 2 and 13 operate as valves for pulse-discharging (exciting) the energy stored in the charging capacitor 9 through the connection terminal 16 to the magnetic field coil 17. Further, the thyristors 10, 11, 14, 15 are operated as valves for causing the magnetic field coil 17 to undergo the alternating pulse discharge (demagnetization) of the residual energy after the pulse discharge through the connection terminal 16.

With reference to FIG. 2, the waveforms of the pulse excitation current, the pulse alternation and the demagnetization current of the excitation power supply device and the operation process of the thyristor will be described. First, when a magnetic material powder is filled in a magnetic field press molding machine and a magnetic field coil mold, and a fixed mold is covered with a movable mold, thyristors-2, 3, 4, 5 are used.
The gate signal is turned off (A) to stop the charging operation. Next, the gate signal is instantaneously turned on to the thyristors 10 and 11.
Let N (B). The energy stored in the capacitor 9 flows in the direction shown by the solid line arrow in FIG. 1 in the form of a resonance pulse current with the magnetic field coil 17 shown in FIG. At the same time, resonance energy in the opposite direction is stored in the charging capacitor-9. Next, the gate signal is momentarily turned on to the thyristors 12 and 13 (C) The energy charged in the reverse direction to the charging capacitor 9 is the magnetic field coil 1 in the direction of the dotted arrow in FIG.
Resonant pulse current with 7 flows in the shape shown in FIG. At the same time, the resonance energy in the initial direction is stored in the charging capacitor-9.
At this time when the charge is accumulated, the gate signal is turned on (D) to the thyristors-2, 3, 4, and 5 to replenish the energy attenuated by the two discharges. The magnetic field press molding is completed in the process of repeating the same operation. Since the magnetic material powder in the die is anisotropically magnetized and pressed, it is necessary to demagnetize the magnetism before opening the die. When the molding of the magnetic material powder is completed, the thyristors-2, 3, 4, 5 are turned off (E).
Let the state continue. Thyristor 10, 11, 14, 1
When the gate signal is continuously turned ON (F) to 5, the power is consumed by the two resonance pulse currents of (B) and (C), and the charging capacitor-
The energy remaining in 9 is discharged as an alternating current having the waveform shown in FIG. Thyristor-1
Gate signals 0, 11, 14, and 15 are turned off (G). After the above operation is completed, the mold of the magnetic field press molding machine is opened and the magnet subjected to anisotropic magnetic field molding is taken out. Finally, the thyristors-2, 3, 4, and 5 are charged with the gate signal to the ON (H) initial molding voltage and stand by.

[0009]

As described above, according to the excitation power supply device of the present invention, by using the palace current excitation for the excitation current of the magnetic field coil, the peak value of the current that can flow in the magnetic field coil is about 10,000 amperes. DC excitation type 10-2
It is possible to obtain 0 times and high magnetic field press molding can be obtained. Further, since the resonance decrement current of the magnetic field coil and the charging capacitor is used for the demagnetizing current, it is not necessary to adjust the demagnetizing current and the demagnetizing time can be shortened to 0.5 seconds or less. According to the exciting power supply device of the present invention, it is possible to perform magnetic field press molding in a high magnetic field for a short time, and to obtain high quality and improved productivity.

[Brief description of drawings]

FIG. 1 is a power supply circuit diagram used in a pulse excitation power supply for a magnetic field press molding machine according to the present invention.

FIG. 2 is a diagram showing a flow of a resonance pulse current.

FIG. 3 is a front view showing a schematic structure of a conventional magnetic field press molding machine apparatus.

FIG. 4 is a waveform diagram showing a conventional DC excitation current and demagnetization current.

[Explanation of symbols]

 1 Transformer 2 Thyristor 3 Thyristor 4 Thyristor 5 Thyristor 6 Resistance 7 Capacitor-8 Capacitor-9 Capacitor-9 Capacitor-10 Thyristor-11 Thyristor-12 Thyristor-13 Thyristor-14 Thyristor-15 Thyristor-16 Connection terminal 17 Magnetic field coil

Claims (2)

[Claims] 1. A circuit mechanism is provided which periodically applies a plurality of pulse currents in the same direction by a combination of a thyristor by applying a resonance effect to the energy stored in a capacitor and a magnetic field coil. Pulse excitation method for magnetic field press molding machine. 2. An excitation power supply device for magnetic field press-molding a magnetic material powder filled in a mold attached to a magnetic field press molding machine, comprising a magnetic field coil, and energy stored in a capacitor in the magnetic field coil. -By instantly discharging, a high magnetic field is generated in the magnetic field coil, and a capacitor built in the power supply device to complete the magnetic field press molding-
By utilizing the resonance phenomenon between the magnetic field coil and the magnetic field coil, the energy in which the resonance energy is reversely charged in the capacitor simultaneously with the excitation of the first wave pulse is changed in the same direction as the direction of the first wave pulse current by the combination of the thyristor. Pulse excitation of the second wave,
A pulse excitation power supply device for a magnetic field press molding machine, characterized by performing magnetic field press molding of a magnetic material powder filled in a magnetic field coil mold in a process of repeating the above operation.