JP2586530B2 - Power supply structure for welding gun - Google Patents

Description

The present invention relates to a method for supplying a current to a high-current machine requiring a large current, such as a welding machine.

b. Conventional technology Two cables for reciprocation were used as welding cables.
There is a current supply method in which they are separately used. In this method, a repulsive force acts upon energization, and a force is applied to the cable. As a result, stress and vibration occur in the cable. Further, since an external magnetic field is generated, it becomes an external noise source. To prevent this, a cable in which a plurality of reciprocating conductors covered with an insulating cover are helically twisted and combined, and the whole is covered with a hose cover is disclosed in Japanese Utility Model Laid-Open Publication No. 61-65827. Kickless cables are commercially available for canceling and weakening magnetic fields generated by a current flowing in a conductor. FIG. 4 is a sectional view of a commercially available kickless cable. 6 conductors a1, a2, a3, b1, b2, b3
Are arranged in a regular hexagonal shape, adjacent conductors are insulated by a common insulator c, and the whole is covered with an insulator d.
The conductors are connected so that current flows in the opposite direction through conductor pairs (a1, a2, a3) and (b1, b2, b3), which are every other three conductors out of the six conductors.

c. Problems to be Solved by the Invention Commercially available kickless cables have a disadvantage that they are thick, hard to bend and expensive because they require six or more conductors. Furthermore, strictly speaking, not all components of the magnetic field vector are canceled out, so that a force is generated in the outward direction of the circle.
Therefore, when used with a large current, an outer presser is required.

The cable described in Japanese Utility Model Laid-Open Publication No. 61-65827 has the same difficulty.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for supplying current to a high-current machine in which stress and vibration generated in a cable are weak and a magnetic field generated in the surroundings is small.

d. Means for Solving the Problems The above-mentioned problem is achieved by connecting two insulated conductors together and connecting the respective conductors of a composite cable in which the outside is covered with an insulator so that the conducting directions are opposite to each other. Supply power to the
In the power supply structure to the welding gun, a plurality of the composite cables are arranged in parallel, and the conducting wires in the composite cables having the same conduction direction are collectively connected and connected to a common terminal. The problem was solved by a power supply structure to the welding gun.

e. Action When 1 amp current is supplied from a transformer using n composite cables, 1 / n amp current flows through each composite cable.

The magnetic field created by the current flowing through each conductor in the composite cable is proportional to the current value. The Lorentz force acting on a conductor in a magnetic field is proportional to the current value in the conductor. That is, the magnetic field H around the first conductor through which the current of I1 amperes flows is H = aI1 (a: constant), and when the current of I2 amperes flows through the second conductor in the magnetic field H, the magnetic field H flows through the second conductor. The acting force F is F = bH × I2 (b: constant). Therefore, the force F acting between the first conductor and the second conductor is F = abI1 × I2
It is.

In the current supply method according to the present invention, the current flowing through each conductor in the composite cable is 1 / n. Therefore, the force acting between the conductors is proportional to (1 / n) ² . For example, when n = 2, the force acting between the conductors in each composite cable is 1/4 of that when n = 1.

Further, the force acting between the composite cables is weak. Because the electric current reciprocates in the multiple conductors in each composite cable, the magnetic fields created around each composite cable as a whole are canceled out by each other and weak, and the force generated by the slightly generated magnetic field on each conductor in the composite cable also increases. Because it is the opposite.
This effect is greater if the conductors in the composite cable are helically twisted.

f. Embodiment FIG. 1 is a conceptual diagram when the current supply method according to the present invention is implemented as a method for supplying current from a transformer secondary side to a welding gun using two composite cables.

The composite cable 1 has a sectional shape as shown in FIG. That is, it is composed of two conductors 1b covered with an insulator 1a, and the two conductors 1b are spirally joined to each other as shown in FIG. 1, and the whole is covered with an insulator 1c.

One conductor drawn from one end of both composite cables 1 is connected to one terminal on the secondary side of the transformer 3 via a common terminal plate 2a, and the other conductor of each composite cable is connected to a common terminal. It is connected to the other terminal on the secondary side of the transformer 3 via another terminal plate 2b.

As shown in FIG. 2, the welding gun 4 includes a pair of electrode members 6, 7 rotatable about a hinge 5, and an object between the electrodes 6a, 7a of both electrode members 6, 7 (shown in FIG. 2). Welding). The two electrode members 6, 7 have connection terminals 6b, 7b that are in electrical contact with the electrode member, and connection terminals 6c, 7c that are insulated and fixed to the electrode member. The connection terminals 6b and 7c are electrically connected to the connection terminals 6c and 7c insulated by the other electrode members via air-cooled multi-core cables 8a and 8b, respectively.

The other ends of both composite cables 2 are connected to connection terminals of a welding gun 4. At this time, the conductors connected to the same terminal of the transformer 3 are connected to a pair of connection terminals (6b, 7c) and (6c, 7b) connected by a composite cable or a shunt plate (thin copper plates). It is connected.

Since the conductors are connected in this manner, the output current of the transformer is controlled by one terminal plate 2a, one conductor in both composite cables, the connection terminals (6b, 7c) of the welding gun, the composite cable or the shunt plate. 8a, one electrode 6a, work piece (not shown), the other electrode 7a, composite cable or shunt plate 8b,
It flows to the connection terminals (6c, 7b) of the welding gun, the remaining one conductor in each of the two composite cables, the other terminal plate 2b, and the transformer.

The current flowing through each composite cable is 1
Since it is 1/2 compared to the case of the book, the force acting between the conductors in each composite cable is / 4. In addition, since a reciprocating current flows in each composite cable and both wires are helically twisted, the magnetic field generated outside the composite cable and its influence are very small.

FIG. 5 is a top view of the transformer for illustrating another aspect of the connection between the transformer and the two composite cables.

One conductor 11a of the composite cable 10a is connected to the output terminal 9a of the transformer 3 by appropriately using a terminal plate, and one conductor 11b of the composite cable 10b is connected to the output terminal 9b. The other conductor 11c of the composite cable 10a is fixed to the output terminal 9a in an insulated state, and the other conductor 11d of the composite cable 10b is fixed to the output terminal 9b in an insulated state. Further, the conductor 11a and the conductor 11d are connected by a copper bar 12a, and the conductor 11b and the conductor 11c are connected by a copper bar 12b. Output terminal 9a
In, the copper bar 12a, the conducting wire 11a, the output terminal 9a, the conducting wire 11c, the copper bar 12b or a terminal plate therefor are fixed by bolts and nuts 14a insulated by an insulator 13a. Similarly, for the output terminal 9b, a bolt
It is fixed with a nut 14b.

FIG. 6 is a top view of a connection portion for showing another mode of connection between the welding gun and the two composite cables.

One of the conductors of one composite cable 10a is in electrical contact with one electrode member 6, and the other is insulated and fixed. One of the conductors of the other composite cable 10b is in electrical contact with the other electrode member 7, and the other is insulated and fixed.
Further, the conductor in electrical contact with the one electrode member 6 and the conductor insulated by the other electrode member 7 are connected to the connection conductor 14a.
Are electrically connected via The conductor insulated by one electrode member 6 and the conductor electrically in contact with the other electrode member 7 are electrically connected via a connection conductor 14b.

Conductors 11a, 11b, 11c, 11d or terminals and connection conductors 14a, 14b for them are fixed using bolts and nuts 16a, 16b insulated with insulators 15a, 15b, respectively, as shown. .

g. Effects of the Invention i) The force generated within and between cables can be reduced without using a kickless cable incorporating three or more sets of electric wires.

ii) Cables are cheaper.

iii) Since the cable can be made thin, it becomes mechanically flexible and easy to handle.

iv) Generation of electromagnetic noise can be prevented.

v) The service life of the cable can be extended, and the operation rate of the equipment can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a preferred embodiment of a current supply method according to the present invention, FIG. 2 is a side view of a welding gun, FIG. 3 is a sectional view of a composite cable composed of two conductors, and FIG. FIG. 5 is a cross-sectional view of a commercially available kickless cable composed of a set of conductors, FIG. 5 is a top view of a transformer showing connection between the transformer and a composite cable in an embodiment of the current supply method according to the present invention, and FIG. FIG. 6 is a side view of a connection terminal portion of the welding gun for illustrating connection between the composite cable and the welding gun in the embodiment of the current supply method according to the present invention. 1 ... Composite cable, 1a ... Insulator, 1b ... Conductor, 1c ... Insulator, 2a, 2b ... Terminal plate, 3 ... Transformer, 4 ... Welding gun, 5 ... Hinge, 6,7 ... electrode members, 6a, 7a ... electrodes, 6b, 6c, 7b, 7c ... connection terminals, 8a, 8b ... composite cables or shunt plates.

Claims (1)

(57) [Claims] An electric conductor is connected to two insulated wires (1a, 1b) so that the conducting direction of each of the wires (1a, 1b) of the composite cable (1) covered with an insulator is reversed. In a power supply structure for a welding gun, which connects and supplies power to a welding gun, a plurality of the composite cables (1) are arranged in parallel, and a current flowing direction in each of the composite cables (1) is the same. The power supply structure for the welding gun, characterized in that the conductors are connected together and connected to a common terminal.