JP2532769B2 - Arc welding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding machine which uses a wire-shaped consumable electrode for welding in a shield gas atmosphere.

[0002]

2. Description of the Related Art A conventional arc welder using a consumable electrode has a circuit configuration shown in FIG. In FIG. 3, 1
Is a welding power supply unit, 2 is a control power supply, 3 is a welding main power supply, 4 is a + side output terminal of the welding main power supply 3, 5 is a-side output terminal of the welding main power supply 3, 6 is a control cable, 7 Is a + side output current cable, 8 is a-side output current cable, 9 is an electric motor for feeding consumable electrodes, 10 is a consumable electrode feeding roller, 1
Reference numeral 1 is a consumable electrode, 12 is a power feeding portion to the consumable electrode 11, 13 is a base material to be welded, and 14 is a control circuit of the electric motor 9.

As is apparent from FIG. 3, in the conventional arc welding machine using the consumable electrode 11, the output terminals 4 and 5 of the welding main power source 3 are respectively the power supply section 12 to the consumable electrode 11 and the mother to be welded. The input of the control circuit 14 of the electric motor 9 which is connected to the material 13 and supplies the consumable electrode 11 uses two wires 6 included in a multi-core control cable different from the two output current cables 7 and 8. Was being supplied.

[0004]

In the above configuration, the input of the control circuit of the electric motor of the consumable electrode is supplied by using the two cores of the control cable. Normally, this control cable is
Copper stranded wire having a cross section of 0.75 mm ² was used.
In this case, when the load on the motor increases and the current flowing through the control cable increases, the voltage drop in the control cable itself reduces the supply voltage of the motor, which causes the rotation speed of the motor to fluctuate, which results in fluctuations in welding output and welding arc It was a cause of stability.

It is an object of the present invention to reduce the fluctuation of the rotation speed of the electric motor due to the voltage drop in the control cable as described above and prevent the fluctuation of the welding output and the instability of the welding arc.

[0006]

In order to achieve the above object, according to the present invention, when the electric current of the electric motor is increased, the number of rotations of the electric motor, which occurs when the input voltage of the control circuit decreases due to the voltage drop in the control cable, In order to reduce fluctuations (hereinafter referred to as motor regulation), the welding power source also serves as the output current cable that connects the negative side input line of the control circuit, the positive side output terminal of the welding main power source, and the current-carrying part of the consumable electrode. Connect so that the DC power supply for the control circuit of the motor of the unit and the main power supply for supplying the welding current are connected in series,
1 of the control cable as the + input line of the control circuit input
Line is used, the + side input of the control circuit is supplied from one line of the control cable, and the-side input of the control circuit is supplied from the output current cable that connects the + side output terminal of the main welding power source and the current-carrying part of the consumable electrode. It was done like this.

[0007]

According to the above means, the minus side input line of the control circuit also serves as the plus side output current cable for supplying the welding current, so that the voltage drop in the output current cable caused by the flowing of the welding current is It becomes a form to be added to the input voltage of the control circuit of the electric motor which supplies the consumable electrode.

That is, the voltage drop in the output cable and the DC power source for the control circuit provided in the welding power source unit are connected in series. Therefore, the voltage drop in the output current cable causes an increase in the input voltage for the control circuit, and serves to prevent the decrease in the motor regulation due to the shortage of the control input that occurs when the load on the electric motor increases.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the arc welding machine of the present invention will be described with reference to FIG.

In FIG. 1, the same parts as those in FIG. 3 are designated by the same reference numerals, and therefore, the common points with FIG. 3 will not be described in detail and the different points will be described.

In FIG. 1, the minus side of the control power source 2 and the plus side of the welding main power source 3 are directly connected, the connection point is connected to the plus side output terminal 4, and the plus side output terminal 4 is the consumable electrode 11.
Is connected to the power supply unit 12 to. Further, the + side input of the control circuit 14 of the electric motor is connected to the control current 2 by the control cable 6, but the − side input of the control circuit 14 is connected to the + side output terminal 4 and the consumable electrode 11 of the welding main power source. Is connected to the position of the + side output current cable 7 that connects the power feeding unit 12 of the above.

According to this structure, when the welding current flows, the + side output current cable 7 is set such that the + side output terminal 4 side of the welding main power source is positive and the connection point side to the control circuit 14 is negative. A voltage drop appears. This voltage drop works as if the voltage of the control power supply 2 increased when viewed from the control circuit 14,
Even if some voltage drop occurs in the control cable 6,
The voltage applied to the control circuit 14 is compensated by the voltage generated in the + side output current cable 7, and the fluctuation of the rotation speed of the electric motor 9 can be reduced.

FIG. 2 shows the effect of the present invention by using the load fluctuation characteristic of the electric motor (characteristic representing the relationship between the load and the rotational speed). In FIG. 2, reference numeral 15 shows the load variation characteristic of the embodiment according to the present invention, and 16 shows the load variation characteristic of the conventional example. In the case of the embodiment according to the present invention, even if the load of the electric motor increases, It can be seen that the section in which the power supply voltage is substantially increased and the rotation speed is constant is larger than in the case of the conventional example.

[0014]

As is apparent from the above description, according to the present invention, the voltage drop in the + side output current cable acts to increase the voltage of the control power source with respect to the increase in the load of the electric motor. Fluctuations in the motor rotation speed are reduced, and it is possible to prevent fluctuations in welding output and unstable welding arc.

Further, since one control cable is required, the cost is reduced and the reliability is improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of an arc welding machine of the present invention.

FIG. 2 is a load characteristic diagram of an electric motor in the same example and a conventional example.

FIG. 3 is a circuit configuration diagram of a conventional arc welder.

[Explanation of symbols]

 3 Main power supply for welding 4 + side output terminal 5 − side output terminal 6 Control cable 7 + side output current cable 8 − side output current cable 9 Electric motor 11 Consumable electrode 12 Power supply part 13 Weld base metal 14 Control circuit

Claims (1)

(57) [Claims] 1. A control circuit for controlling the number of revolutions of an electric motor for feeding a consumable electrode is arranged near the electric motor, and a + side output terminal of the main power source for welding, a power supply section to the consumable electrode, and a main power source for welding. -Side output terminal and the base material to be welded are respectively connected by an output current cable, and the input of the control circuit is one wire of the control cable other than the output current cable and + of the main power source for welding.
It is configured to be supplied via an output current cable that connects the side output terminal and the power supply part of the consumable electrode. The + side input of the control circuit is connected to one line of the control cable, and the-side input of the control circuit is used for welding. An arc welding machine that is connected to the output current cable that connects the + output terminal of the power supply and the power supply section of the consumable electrode.