JP3199169B2 - DC 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 a DC arc welding machine, and more particularly to a type using a welding rod consumed by welding, such as manual welding, MIG welding, and MAG welding.

[0002]

2. Description of the Related Art An example of a DC arc welding machine as described above is shown in FIG. The three-phase commercial AC power supply is connected to terminal 1a
To 1c to the input side rectifier circuit 2. The input-side rectifier circuit 2 converts commercial AC power into DC power and supplies the DC power to the inverter 3.

The inverter 3 includes semiconductor switching elements 4 to 7 such as IGBTs and FETs connected in full bridge.
have. These semiconductor switching elements 4 to 7
Is operated by a switching control circuit (not shown) to convert supplied DC power into high-frequency power. The switching elements 4 to 7 include:
Flywheeling diodes 8 to 11 are connected in anti-parallel.

The high frequency power output from the inverter 3 is:
It is supplied to the input side of the transformer 15. On the output side of the transformer 15, rectifier diodes 16, 17 are provided as output-side rectifiers. The high-frequency current rectified by the rectifier diodes 16 and 17 is smoothed by the reactor 28 and supplied to the welding rod 20. Welding rod 20 and base metal 21
Is returned to the intermediate tap on the output side of the transformer 15. Note that by converting DC power into high-frequency power by the inverter 3, the transformer 15 has:
A small one can be used, and the entire DC arc welding machine can be downsized.

[0005]

SUMMARY OF THE INVENTION Manual welding, MIG welding,
In MAG welding or the like, a welding rod that uses cellulose as a main raw material may be used. Welding using such a welding rod is widely performed. However, in welding using such a welding rod, the welding rod 20 is
Short-circuited, and when the transition from the short-circuit to the arc occurred, the arc was easily broken. To prevent this arc break,
The output voltage of the transformer 15 is increased and the reactor 28
Needed to be large-capacity.

When a welding rod made of a material other than cellulose is used, an arc is easily generated. Therefore, in preparation for using a welding rod made of cellulose as a main material, the output side voltage of the transformer 15 is increased, and a welding rod made of a material other than cellulose is used in a state where the reactor 28 has a large capacity. Then, the input capacity to the DC arc welding machine is excessively increased, and the efficiency of the DC arc welding machine is reduced.

[0007] The present invention provides a DC power supply that does not increase the input capacity even when using a welding rod that is liable to cause arc breakage, or even when using a welding rod that does not cause arc breakage and that hardly causes arc breakage. An object of the present invention is to provide an arc welding machine.

[0008]

According to the first aspect of the present invention, a DC power supply having first and second output terminals is connected to a welding rod mainly made of cellulose. And a terminal for a welding rod that may be provided. An intermediate tap of the reactor is connected to a first output terminal of the DC power supply, and one end of the reactor is connected to a welding rod terminal. A base material terminal is connected to a second output terminal of the DC power supply. The base material terminal is to be connected to the base material. A directional element is connected between the base material terminal and the other end of the DC reactor. This directional element allows current to flow only from the base material terminal side to the reactor side.

According to the first aspect of the invention, when, for example, the welding rod and the base material are short-circuited, a current flows between the intermediate tap and one end of the reactor, and energy is stored in the reactor. From this short-circuit state, a transition is made to a state in which an arc is generated between the welding rod and the base material. At this time, when the arc is going to break due to the welding rod being made of cellulose as a main raw material, and the arc current flowing between the welding rod and the base material is reduced, the current based on the energy stored in the reactor is increased by welding. Flows through rods, preforms and directional elements to prevent arcing. In particular, since the first output terminal of the DC power supply is connected to the intermediate tap of the reactor,
When the arc current is reduced, the voltage applied between the welding rod and the base metal is the voltage generated between both ends of the reactor. This voltage is higher than the voltage generated between the intermediate tap and one end of the reactor. When a reactor having no intermediate tap is used, the voltage applied between the welding rod and the base material cannot be increased.
However, according to the first aspect of the present invention, since the reactor has the intermediate tap, the voltage applied between the welding rod and the base material can be increased.

According to a second aspect of the present invention, in the DC arc welding machine according to the first aspect, the reactor includes a winding from the one end to the intermediate tap and a winding from the intermediate tap to the other end. However, their magnetic coupling is tightly wound on the same core.

According to the second aspect of the present invention, a high voltage is induced from the intermediate tap to the other end by the voltage applied from one end to the intermediate tap. Therefore, the voltage induced from one end to the other end of the reactor increases as a whole, and it is possible to reliably prevent the arc from breaking.

[0012]

FIG. 1 shows an embodiment of the present invention. In the DC arc welding machine of this embodiment and the DC arc welding machine shown in FIG. 2, the same components are denoted by the same reference numerals, and description thereof will be omitted. The input side rectifier circuit 2, the inverter 3, the transformer 15, and the rectifier diodes 16 and 17 constitute a DC power supply. The interconnection point between the cathodes of the rectifier diodes 16 and 17 corresponds to the first output terminal of the DC power supply,
The intermediate tap on the next side corresponds to the second output terminal of the DC power supply. The welding rod 20 is connected to a welding rod terminal 30. The base material 21 is connected to the base material terminal 31.

In the DC arc welding machine of this embodiment,
A reactor 18 is used. This reactor 18
Has an intermediate tap C in addition to its both ends A and B. The end A is connected to the welding rod terminal 30. An intermediate tap C is connected to the interconnection point of the cathodes of the rectifier diodes 16 and 17, that is, the first output terminal. A directional element, for example, an anode of a flywheeling diode 19 is connected to the base material terminal 31, and a cathode thereof is connected to an end B of the reactor 18.

As the DC reactor 18, for example, a winding AC between the end A and the intermediate tap C and a winding BC between the intermediate tap C and the end B are magnetically coupled to each other. It is wound around the same core so as to be dense.

According to this DC arc welding machine, the welding rod 2
0 and the base material 21 are short-circuited,
From the interconnection points of the cathodes 6 and 17, the reactor 18
A current flows to the intermediate tap of the secondary winding of the transformer 15 via the intermediate tap C, the end A, the welding rod 20, and the base material 21 of the transformer.
At this time, since the current flows through the winding CA of the reactor 18, energy is accumulated in the reactor 18,
A voltage is generated such that the intermediate tap C is positive and the end A is negative.
At this time, a voltage is generated between the end B and the intermediate tap C such that the end B is positive and the intermediate tap C is negative. That is, a voltage having a polarity opposite to that of the arrow shown in FIG. 1 is generated.

When the state is shifted from the short-circuit state to the arc-generating state, for example, as a result of using a welding rod 20 made of cellulose as a main raw material, an arc break is caused to occur, so that the welding rod 20 and the base material 21 are separated. The flowing arc current is reduced. At this time, based on the energy stored in the reactor 18, as shown by the arrow in FIG. 1, the current is changed to the end A of the reactor 18 so as to compensate for the reduced arc current.
From the welding rod 20, the base metal 21, and the flywheeling diode 19 to the end B of the reactor 18. At this time, a voltage VL1 having a positive polarity on the terminal A side and a negative polarity on the intermediate tap C and a voltage VL2 having a positive polarity on the intermediate tap C and a negative polarity at the end B are generated in the reactor 18. The voltage between both ends A and B of the reactor 18, VL1 + VL2
Is applied between the welding rod 20 and the base material 21, so that a large voltage is generated between the welding rod 20 and the base material 21 to prevent the arc from breaking.

For example, when a reactor that does not use the intermediate tap C is used instead of the reactor 18, the voltage applied between the welding rod 20 and the base material 21 at the time of arc transfer is as follows.
It is only based on the back electromotive force generated between both ends of the reactor. This corresponds to, for example, the intermediate tap C and the end A in FIG.
Is equivalent to the voltage VL1 generated between the two. However, when the reactor 18 with the intermediate tap is used, a voltage having a value obtained by adding the voltage VL1 and the voltage VL2 is applied, and it is possible to reliably prevent the arc from being cut.
Particularly, in the reactor 18, the winding AC and the winding BC are wound around the same core so that the magnetic coupling is dense, so that the voltage VL2 generated between the windings BC is set to a large value. Can be. Accordingly, it is possible to reliably prevent the arc from breaking.

Even if a welding rod made of a main material other than cellulose is used as the welding rod 20, the output voltage of the transformer 15 is not increased for a welding rod made of cellulose as a main material. The input capacity of the welding machine does not increase.

[0019]

As described above, according to the first aspect of the present invention, when a reactor having an intermediate tap is used, an arc break is caused by using a welding rod made of cellulose as a main raw material. , A high voltage can be applied between the welding rod and the base material. Therefore, even if a welding rod mainly composed of cellulose, which is likely to cause an arc break, is used, the arc break does not occur. In addition, in order to prevent such a break in the arc, no special measures are taken to increase the voltage of the DC power supply. Therefore, even when a welding rod that originally does not easily cause a break in the arc is used, the input capacity may not increase. And there is no reduction in efficiency.

Furthermore, according to the second aspect of the present invention, the voltage induced between the intermediate tap and the other end of the reactor can be increased, so that the voltage applied between the welding rod and the base metal can be increased. Voltage can be increased, and arc breakage can be reliably prevented.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of an example of a conventional DC arc welding machine.

[Explanation of symbols]

 2 Input side rectifier circuit (DC power supply) 3 Inverter (DC power supply) 15 Transformer (DC power supply) 16 17 Rectifier diode (DC power supply) 18 Reactor 20 Welding rod 21 Base metal

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Atsushi Kinoshita 2-14-3 Awaji, Higashiyodogawa-ku, Osaka-shi, Osaka Inside Sansha Electric Manufacturing Co., Ltd. (56) References JP-A-53-14143 (JP, A) JP-A-8-19862 (JP, A) JP-A-55-36048 (JP, A) JP-A-8-192269 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/073 H02M 9/00

Claims (2)

(57) [Claims] 1. A DC power supply having first and second output terminals, a welding rod terminal which may be connected to a welding rod mainly made of cellulose, and a first output terminal of the DC power supply. The middle tap is connected,
A reactor having one end connected to the welding rod terminal, a base material terminal connected to the second output end of the DC power supply, and to be connected to the base material, and the base material terminal; And a directional element that is connected between the DC reactor and the other end of the DC reactor and that allows current to flow only from the base material terminal side to the reactor side. 2. The DC arc welding machine according to claim 1, wherein the reactor is configured such that a winding from the one end to the intermediate tap and a winding from the intermediate tap to the other end are magnetically coupled to each other. DC arc welding machine in which the connections are tightly wound on the same core.