JP2002273577A - Energizing device for electromagnetic welder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energizing device for an electromagnetic welder which is free from making noise, damage and exhaustion of a contact. SOLUTION: Capacitors 1a, 1b, 1c and 1d, upper flat coils 2a, 2b, 2c and 2d, lower flat coils 3a, 3b, 3c and 3d and transistors 4a, 4b, 4c and 4d are connected respectively in series. The connection points of one of the electrodes of the capacitors 1a, 1b, 1c and 1d and the transistors 4a, 4b, 4c and 4d are connected with one electrode of a high voltage DC power source device 5. The other electrode of the DC power source device 5 is connected with the connection points of the other electrodes of the capacitors 1a, 1b, 1c and 1d and the upper flat coils 2a, 2b, 2c and 2d respectively through restriction resistors 6a, 6b, 6c and 6d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current supply device for an electromagnetic welding machine for welding thin metal sheets by electromagnetic force.

[0002]

2. Description of the Related Art Aluminum has been increasingly used in response to demands for lighter products. When joining metal sheet materials, spot welding or seam welding is generally used using an electric resistance welder, but welding with an aluminum electric resistance welder has been difficult. That is, since aluminum has a high thermal conductivity and electrical conductivity irrespective of a low melting temperature, it is necessary to flow a large current during welding, and there is a problem that the molten aluminum is easily welded to the electrode. Further, in the case of seam welding, current is shunted to an already welded portion, making it difficult to weld an adjacent portion.

In order to solve such a problem, one of the inventors of the present invention has disclosed a technique disclosed in Japanese Unexamined Patent Publication No. Hei 11-1 in which a large current is instantaneously applied to a flat coil and a thin metal plate is instantaneously welded by electromagnetic force.
Considering the electromagnetic welding method of thin metal sheets such as 92562, practical application is underway. Japanese Patent Application Laid-Open No. 11-192
The electromagnetic welding method of metal sheets 562 is such that metal sheets to be welded are placed one on top of another and placed between flat coils, and a large current is applied to the coils to perform welding. At least one of the upper and lower portions of the flat coil is provided with a concentrated portion through which a current flows in a concentrated manner, and the thin metal plate, which is a workpiece to be welded and sandwiched between the upper and lower flat coils, faces the concentrated portion. Welded in position. In order to allow a large current to flow through the flat coil, the capacitor is charged by a DC high-voltage power supply, and the charge stored in the capacitor is discharged to the coil instantaneously through a switch.

The voltage of the DC high voltage power supply used here is 5 to 15 kV, the capacitance of the capacitor is 50 to 200 μF, and the peak value of the discharge current is 100 kA.
Reach more. Although the discharge time was 100 μsec or less, a semiconductor element could not be used as a switch in terms of capacity, and a discharge gap switch or a mechanical switch had to be used. However, there is a problem that the discharge gap switch and the mechanical switch generate noise such as an impact sound during operation, and the contacts are damaged or worn. Also, the discharge gap switch requires adjustment depending on the air condition because the discharge voltage fluctuates due to the humidity of the air.In extreme cases, the discharge gap switch conducts during the charging of the capacitor and discharges the capacitor. There has been a problem that insufficient current may cause poor welding.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a current supply device for an electromagnetic welding machine which does not emit noise by using a semiconductor element for a switch, does not damage contacts, and does not wear. It was made to provide.

[0006]

SUMMARY OF THE INVENTION The above-mentioned problems are caused by a plate-shaped coil through which a welding current flows, a plurality of series circuits in which a semiconductor element and a capacitor are connected in series, and a DC high-voltage power supply for charging the capacitor. The present invention can be solved by the current supply device for an electromagnetic welding machine according to the present invention, characterized in that a signal is simultaneously supplied to a plurality of semiconductor elements in a series circuit to make them conductive. Also, the capacitors of the plurality of series circuits may be charged by individual DC high-voltage power supplies, or one pole of the capacitors of the plurality of series circuits may be connected to one pole of the DC high-voltage power supply, and the other poles of the capacitors may be respectively connected. It can be embodied by being connected to the other pole of the DC high-voltage power supply via a limiting resistor and charged by a common DC high-voltage power supply, and the semiconductor element is preferably a transistor or a thyristor.

[0007]

Next, an embodiment of an electromagnetic welding machine of the present invention will be specifically described with reference to the drawings. FIG. 1 shows a case in which four series circuits are used, in which capacitors 1a, 1b, 1c, and 1d and an upper flat coil 2
a, 2b, 2c, 2d, and lower plate-shaped coils 3a, 3a
b, 3c, 3d and transistors 4a, 4b, 4c, 4
and d are connected in series. Capacitor 1a,
1b, 1c, 1d and transistors 4a, 4b, 4
c and 4d are connected to one pole of the high-voltage DC power supply 5, and the other poles of the high-voltage DC power supply 5 are connected via the limiting resistors 6 a, 6 b, 6 c and 6 d to the capacitors 1 a,
1b, 1c, and 1d and the other poles and the upper flat coil 2a, 2
b, 2c, and 2d. Here, the upper plate-shaped coils 2a, 2b, 2c, and 2d and the lower plate-shaped coils 3a, 3b, 3c, and 3d are provided with concentrated portions, respectively. Then, the upper plate-shaped coils 2a, 2b, 2c,
2d and the lower plate-shaped coils 3a, 3b, 3c, 3d are each closely adjacent to each other. Reference numeral 7 denotes a control device which turns on and off the output of the DC high-voltage power supply device 5, checks whether or not there is a set of an object to be welded, and includes transistors 4a, 4b, 4
It has a function of supplying a base signal to c and 4d.

The current supply device of the electromagnetic welding machine according to the present invention having the above-described structure is composed of upper flat coils 2a, 2b, 2c, 2d.
When the control device 7 confirms that an object to be welded has been set between the lower plate-shaped coil 3a, 3b, 3c, and 3d,
The control device 7 turns on the output of the high-voltage DC power supply 5 and the high-voltage DC power supply 5 generates a high DC voltage, and the capacitors 1a, 1
b, 1c and 1d are charged. Capacitors 1a, 1b, 1
When c and 1d are charged to a preset voltage,
The control device 7 supplies a base signal to the transistors 4a, 4b, 4c, and 4d all at once, and
c, 4d conduct and capacitors 1a, 1b, 1c, 1d
The electric charges stored in the upper plate-shaped coils 2a, 2a
b, 2c, 2d and lower flat coils 3a, 3b, 3
Discharge through c and 3d.

The four upper flat coils 2a, 2b, 2
c, 2d are each closely adjacent to each other, and the four lower flat coils 3a, 3b, 3c, 3d are also each closely adjacent to each other, so that the four upper flat coils 2a, 2b , 2c, 2d and lower flat coil 3a, 3c
b, 3c, and 3d are equivalent to the total current flowing through the single upper flat coil and the lower flat coil, respectively, and the upper flat coils 2a, 2b, 2c, 2
The object to be welded set between d and the lower flat coils 3a, 3b, 3c, 3d is to be welded.

As is apparent from the above-described embodiment, a necessary welding current is supplied to a plurality of upper plate-shaped coils 2.
a, 2b, 2c, 2d and lower flat coils 3a, 3
b, 3c, 3d and a plurality of transistors 4a, 4b, 4
Since the current is divided into c and 4d, the current flowing through the individual transistor becomes sufficiently small, and the current can be opened and closed by the semiconductor element.

In the above embodiment, the capacitor 1
Although a, 1b, 1c, and 1d are charged by a single DC high-voltage power supply 5, individual DC high-voltage power supplies may be used. When the DC high-voltage power supply is individually provided, the DC high-voltage power supply 5, the capacitors 1a, 1b, 1
c, 1d or transistors 4a, 4b, 4c, 4d
In the case where any one of the above-mentioned failures occurs, there is an advantage that welding can be continuously performed by disconnecting the failed series circuit.

In the above-described embodiment, the upper plate-shaped coils 2a, 2b, 2c, 2d and the lower plate-shaped coils 3a, 3b, 3c, 3d are divided vertically and overlapped in the vertical direction. However, as shown in FIG. 2, it is divided in the horizontal direction and overlapped in the horizontal direction, or FIG.
As shown in (1), an arbitrary configuration can be adopted, such as dividing in the horizontal direction and overlapping horizontally bent portions in the horizontal direction.

[0013]

According to the present invention described above, since the switch is a semiconductor element, there is an advantage that no noise is generated at the time of operation and no contact is consumed. Also, there is no possibility that the switch malfunctions and discharges the capacitor before the charging of the capacitor is completed, resulting in poor welding.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention.

FIG. 2 is an external view showing another shape of the flat coil.

FIG. 3 is an external view showing still another shape of the flat coil.

[Explanation of symbols]

 1a, 1b, 1c, 1d Capacitors 2a, 2b, 2c, 2d Upper flat coil 3a, 3b, 3c, 3d Lower flat coil 4a, 4b, 4c, 4d Transistor 5 High voltage DC power supply 6a, 6b, 6c, 6d Limiting resistor 7 Control device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Ozaki 5-12 Kagocho, Chigusa-ku, Nagoya-shi, Aichi Prefecture (72) Inventor Tomokatsu Aizawa 795-7, Arai Arai, Hino-shi, Tokyo

Claims (5)

[Claims] 1. A semiconductor device comprising a plurality of series circuits, comprising: a plate-shaped coil through which a welding current flows; a plurality of series circuits in which a semiconductor element and a capacitor are connected in series; and a DC high-voltage power supply for charging the capacitor. An energizing device for an electromagnetic welding machine, wherein signals are simultaneously applied to the elements to make them conductive. 2. The current supply device for an electromagnetic welding machine according to claim 1, wherein the capacitors of the plurality of series circuits are charged by individual DC high-voltage power supply devices. 3. One of the plurality of series circuit capacitors has one pole connected to one pole of the DC high-voltage power supply, and the other pole of the capacitor is connected to the other pole of the DC high-voltage power supply via a limiting resistor. The current supply device for an electromagnetic welding machine according to claim 1, wherein the charging is performed by a common DC high-voltage power supply device. 4. The current supply device for an electromagnetic welding machine according to claim 1, wherein the semiconductor element is a transistor. 5. The current supply device for an electromagnetic welding machine according to claim 1, wherein the semiconductor element is a thyristor.