JPH0735655Y2 - DC arc welder - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC arc welding machine which suppresses short circuit current.

[0002]

2. Description of the Related Art Generally, an arc welding machine has a large voltage fluctuation rate and has a drooping characteristic to stabilize an arc.

[0003]

However, in the conventional arc welding machine, regardless of direct current or alternating current, if the welding rod comes into contact with the object to be welded and the arc is extinguished for some reason during the welding operation, a large short circuit will occur. If an electric current flows and this state continues for an unnecessarily long time, the transformer, the welding rod, and the like will be burned out, so skill is required for the welding work.

This invention automatically suppresses the short-circuit current when the above-mentioned welding rod comes into contact with the object to be welded, prevents the transformer and the welding rod from burning, and facilitates the welding work. Provide a welding machine for downsizing and labor saving.

[0005]

The gist of the present invention for achieving the above object is a DC arc welding machine for rectifying the secondary side output of a transformer to obtain a welding power source output , A solid state relay is connected to the primary coil of the transformer, a control circuit for the solid state relay is provided on the welding power source output terminal side, and the solid state relay is turned off when the welding voltage falls below a predetermined set voltage value. The DC arc welding machine is characterized in that a resetting resistor is connected between the output terminals of the solid state relay.

[0006]

[Operation] During arc welding, the welding current increases and decreases and the welding voltage changes, but if the welding rod shorts and the welding voltage drops below the set voltage value, the control circuit turns off the solid state relay. Then, the load current flowing in the primary coil of the transformer is cut off to suppress an excessive short-circuit current. While the solid-state relay is off, current flows through the primary coil of the transformer through the resetting resistor to ensure the operation of the control circuit, and when the short circuit is resolved, the solid-state relay is turned on. Welding returns to the original state.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a connection diagram of a DC arc welding machine according to the present invention.

In the figure, 1 is a transformer in which electric power is supplied from an AC power supply input terminal 2 to a primary coil 3, and a secondary coil 4 of this transformer 1 has a rectifying circuit 5 composed of a diode or the like.
Is connected and used as a DC welding power output . 6 is a welding power source output terminal.

7 is connected to the primary coil 3 of the transformer 1,
A solid state relay for turning on / off the load current flowing in the primary coil 3, and 8 for a control circuit of the solid state relay 7 connected to the welding power source output terminal side. When the welding voltage drops below a predetermined set voltage value, the solid state relay 7 Is turned off to cut off the load current flowing through the primary coil 3. 9 is this solid state relay terry 7
Between the output terminals of the solid state relay 7, that is, with the resetting resistor connected in series to the primary coil 3.
This is for ensuring the operation of the control circuit 8 by supplying a current to the primary coil 3 of the transformer 1 during the FF operation.

In the above construction, the solid state relay 7 is in the ON state during welding, and as in a general-purpose DC arc welder, as shown in FIG. Changes and welding is performed.

When the welding rod comes into contact with the object to be welded and a short-circuit current flows and the welding voltage falls below a predetermined set voltage value, the solid-state relay 7 is turned off by the control circuit 8 and the load current flowing through the primary coil 3 is reached. And at the same time
A current flows through the primary coil 3 of the transformer 1 via the resetting resistor 9 to secure the operation of the control circuit 8 and suppress the short-circuit current flowing through the welding rod. That is, the welding rod contacts the object to be welded, and the current secures the current at the control operation point corresponding to point C in the figure. (In the past, the current corresponding to point B in the figure flows.) Then, when the short circuit is resolved, the solid state relay 7 turns O.
N operation is performed to return to the original state that enables normal welding.

[0013]

According to this invention, the following effects can be obtained.

(1) When the welding rod comes into contact with the object to be welded, excessive short-circuit current is automatically suppressed. Therefore, the transformer and the welding rod are prevented from being burnt out to improve safety and facilitate welding work. To

(2) While the solid state relay connected to the primary coil of the transformer is turned off, a current flows through the primary coil of the transformer through the resetting resistor to ensure the operation of the control circuit, so that a short circuit occurs. It recovers quickly and is highly reliable, and it also contributes to labor saving by reducing the size of the equipment.

[Brief description of drawings]

FIG. 1 is a connection diagram of a DC arc welding machine according to the present invention.

FIG. 2 is an explanatory diagram showing a proper welding range.

[Explanation of symbols]

1 ... Transformer 3 ... Primary coil 4 ... Secondary coil 6 ... Welding power supply output terminal 7 ... Solid state relay 8 ... Control circuit 9 ... Return resistance

Claims (1)

[Scope of utility model registration request] 1. A welding power source by rectifying the secondary side output of a transformer.
A DC arc welder for output, in which a solid state relay is connected to the primary coil of the transformer, and a control circuit for the solid state relay is provided on the welding power source output terminal side,
A DC arc welding machine characterized in that a solid state relay is turned off when a welding voltage drops below a predetermined set voltage value, and a resetting resistor is connected between output terminals of the solid state relay.