JP2747338B2 - Wire conduction type TIG welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electric wire type TIG welding apparatus for energizing and heating a filler wire.

[Conventional technology]

The wire-energized TIG welding system is designed to increase the amount of welding by supplying energized and heated wires while taking advantage of the high-quality welding that is an advantage of TIG welding, thereby increasing the amount of welding and increasing efficiency. If the TIG arc current and the wire conduction current flow simultaneously, they may interfere with each other and cause magnetic blowing. To solve this problem,
There has been proposed a method in which a TIG arc current is periodically changed, and a current is not supplied to a wire during a large current period, but is supplied to a wire only during a small current period.

[Problems to be solved by the invention]

However, such a wire-powered TIG welding apparatus usually requires two independent power supplies for arc generation and wire power supply, and the power supply unit is large.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate mutual interference between a TIG arc current and a wire conduction current, which are problems of a wire conduction type TIG welding apparatus, and to achieve a compact power supply. Still another object is to provide a wire-energized TIG welding apparatus that can switch and use one power supply for AC TIG welding.

[Means for solving the problem]

In order to achieve the above object, an invention according to claim 1 includes, in a welding power source, a primary rectifier for converting a commercial AC input to DC, and a transformer for converting a DC output of the rectifier to a high-frequency AC. An inverter to be applied to the primary side, a secondary side rectifier for converting the AC output of the transformer secondary to DC, and a DC output of the rectifier alternately to a TIG welding electrode and a power supply tip of a filler wire. A pair of switching elements controlled to be supplied, a pair of capacitors connected between an input side of the switching elements and a return line, and a pair of re-ignition voltage sources for charging the capacitors are provided. It is characterized by having.

According to another aspect of the present invention, a welding power supply includes a primary rectifier that converts a commercial AC input into DC, and a DC output of the rectifier that is converted into a high-frequency AC. An inverter applied to the primary side of the transformer, two sets of secondary-side rectifying elements for converting the AC output of the secondary side of the transformer into DC outputs in the positive and negative directions with respect to the neutral point, and A pair of switching elements respectively connected to the output side of the secondary side rectifier and controlled to alternately supply a positive DC output and a negative DC output to a load;
The output side of the switching element that supplies the DC output in the negative direction of the pair of switching elements is always connected to the electrode for TIG welding, and the output side of the switching element that supplies the DC output in the positive direction is switched by a switch provided separately. It is characterized in that it can be switched and connected to the welding electrode and the power supply tip of the filler wire.

[Operation] In the invention according to claim 1, after the high-frequency AC output of the inverter is appropriately stepped down by a transformer, it is converted into DC by a secondary-side rectifying element, and the DC output is used for TIG welding by a pair of switching elements. By alternately supplying the electrode and the wire feeding chip, a single inverter control power supply can supply the TIG arc current and the wire current without interfering with each other.

According to the second aspect of the present invention, the high-frequency AC output of the inverter is appropriately stepped down by a transformer, and then converted into a DC output in a positive direction and a negative direction with respect to a neutral point by two sets of secondary rectifiers. During AC TIG welding, a positive DC output and a negative DC output are alternately supplied to a TIG welding electrode by a pair of switching elements. By alternately supplying a DC output to the TIG welding electrode and a positive DC output to the wire feed tip, one inverter control power supply can be switched between AC TIG welding and wire-on TIG welding and used. I have.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a primary rectifier for converting a commercial AC input into DC, 2 an inverter for converting the DC output of the rectifier 1 to high-frequency AC, and 3 a voltage suitable for welding the high-frequency AC output of the inverter 2 for welding. The size of the transformer is reduced by applying a high frequency. 4-1 to 4-
Reference numeral 4 denotes a secondary-side rectifying element, which outputs a negative direct-current output from one set of rectifying elements 4-1 and 4-2 to a neutral point (center tap) N on the secondary side of the transformer. Set of rectifying elements 4-3, 4-4
Are connected so that a DC output in the positive direction can be taken out. 5-1 and 5-2 are the two sets of secondary side rectifiers 4-
1, 4-2 and 4-3, 4-4, each of which is a transistor as a switching element connected to the output side.
-2 is controlled by a signal from the drive circuit 6 so as to alternately supply a positive DC output to the load. Reference numeral 7 denotes a TIG welding electrode, and the nozzle is not shown. 8 is the base material, 9
Is a filler wire, and a wire feeder 10 feeds a chip 11
Is sent to the molten pool of the base material 8. The output side of the transistor 5-1 for supplying a negative DC output of the pair of transistors 5-1 and 5-2 is always connected to the electrode 7, and the transistor 5- for supplying a positive DC output is provided.
The output side of 2 is connected to the electrode 7 and the power supply chip by the changeover switch 12.
The connection is switched to 11. The changeover switch 12 can switch between AC TIG welding and wire-energized TIG welding. 13 is a return line connecting the base material 8 and the neutral point N, 14 is a current detector connected to the return line 13, 15 is a smoothing reactor connected to the return line 13, and 16-1 and 16-2 are transistors. Current limiting resistor 1 between input side of 5-1 and 5-2 and return line 13
Capacitors connected in series with 7-1 and 17-2, 18-1 and 18
-2 is a re-ignition voltage source for charging the capacitors 16-1 and 16-2 to a voltage (about 200 V) necessary for re-ignition of the TIG arc;
-1,19-2 are transient voltage absorbing diodes connected in anti-parallel to the transistors 5-1 and 5-2. Detection signal from the current detector 14 compares the setting signal 21 and error amplifier 23 of the setting signal 20 and the wire current applied Tiguaku current that is switched by the signal switcher _{22 (I a) (I w} ), the error signal PWM control The output of the inverter 2 is controlled as a control input of the circuit 24.

The operation at the time of AC TIG welding and at the time of wire-energized TIG welding will be described with reference to FIGS. 1 to 3 as follows.

(1) AC TIG Welding In FIG. 1, when the a contact side of the changeover switch 12 is closed, a voltage having a negative polarity is applied to the electrode 7 during the ON period of the transistor 5-1. During the on-period of −2, a voltage having such a polarity that the electrode becomes positive is applied to the electrode 7, so that an AC TIG arc is generated between the electrode 7 and the base material 8. In this case, when the transistor 5-1 is turned on, the charging voltage of the capacitor 16-1 is applied between the electrode and the base material with the negative polarity of the electrode, and when the transistor 5-2 is turned on, the charging voltage of the capacitor 16-2 is applied to the electrode. -Applied with a positive polarity between the electrodes to help reignite the arc after polarity reversal. That is, the arc current I _a , the capacitor 16
The waveforms of the discharge currents I _c1 and I _c2 of −1 and 16-2 are as shown in FIG. ₂ , and the polarities are at a period determined by the on period T ₁ of the transistor 5-1 and the on period T _{2 of} the transistor 5-2. The reversing arc current _Ia flows, and its current value is
Is controlled by the inverter 2 so as to have a value corresponding to.

In AC TIG welding, transistors 5-1 and 5-2
Transient voltage generated in the load cable due to turn-off of the capacitor 16-
The transient voltage generated in the reactor 15 is absorbed by the capacitors 16-1 and 16-2 via the secondary side of the transformer 3 and the rectifiers 4-1 to 4-4.

(2) Wire conduction type TIG welding In FIG. 1, when the b contact side of the changeover switch 12 is closed, a voltage having a polarity such that the electrode becomes negative only during the ON period of the transistor 5-1 is applied to the electrode 7, Thus, a DC TIG arc is generated between the electrode 7 and the base material 8. On the other hand, the on period of the transistor 5-2, the power supply tip 11 through the transistor 5-2 and the changeover switch 12 wire energization current I _w flows energized heating the filler wire 9. Therefore, by synchronizing the on / off switching of the transistors 5-1 and 5-2 with the switching of the current setting signals 20 and 21 in the signal switch 22, the arc current _Ia and the wire conduction current Ia as shown in FIG. _w is supplied alternately, and the respective current values are controlled by the inverter so as to be values corresponding to the setting signals 20 and 21. The arc current _Ia and the wire current _Iw are not continuous, but flow intermittently as shown. Also in this case, the capacitor 16 is turned on when the transistor 5-1 is turned on.
By applying a charging voltage of -1 between the electrode and the base material,
It can help reignite the arc.

Thus instead of passing a arc current I _a intermittently, the main arc current is passed alternately with the wire energization current I _w, since even during the wire energization to maintain the arc of a small current,
A rectifying element 26 provided separately using the auxiliary winding 25 of the transformer 3
And a current may be supplied between the electrode and the base material via the current limiting resistor 27.

Further, in this embodiment, the switching between the AC TIG welding and the wire conduction type TIG welding is enabled by the changeover switch 12, but the changeover switch 12 is eliminated, and the output side of the transistor 5-2 is always connected to the power supply chip 11. Alternatively, it may be a dedicated wire welding type TIG welding machine.

It is not necessary to provide two sets of rectifying elements on the secondary side in the wire-energized TIG welding machine. Only one set of rectifying elements 4-1 and 4-2 is used, and the DC output is controlled by a pair of switching elements. By alternately supplying the power to the power supply 7 and the power supply chip 11, the welding power source can be further simplified.

〔The invention's effect〕

According to the first aspect of the present invention, the TIG arc current and the wire conduction current can be alternately supplied by one inverter control power supply, so that the wire conduction type TIG welding can be performed without causing a magnetic blowing phenomenon due to mutual interference between the two currents. And the welding power source can be downsized.

According to the second aspect of the present invention, in addition to the above effects, one power supply can be switched between AC TIG welding and wire-energized TIG welding to be used, so that it is possible to increase the utility value. it can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams of its operation. 1. Primary rectifier, 2. Inverter, 3. Transformer, 4-1 to 4-4. Secondary rectifier, 5-1 and 5-2
... Switching element, 6 ... Drive circuit, 7 ... Tig welding electrode, 8 ... Base metal, 9 ... Solution wire, 11 ... Power supply tip, 12 ... Switch, N ... Neutral point .

Claims (2)

(57) [Claims] In a wire welding type TIG welding apparatus for electrically heating a filler wire, a welding power source converts a commercial AC input into DC, a primary rectifier, and converts a DC output of the rectifier into high-frequency AC. An inverter applied to the transformer primary side, a secondary rectifier for converting the AC output of the transformer secondary to DC, a DC output of the rectifier for the TIG welding electrode and a power supply tip of the filler wire. , A pair of capacitors connected between the input side of the switching element and the return line, and a pair of re-ignition voltage sources for charging the capacitors. And a wire-energized TIG welding apparatus characterized in that: 2. A wire welding type TIG welding apparatus for heating a filler wire by heating a welding power source, a primary rectifier for converting a commercial AC input into DC, and a DC output of the rectifier for converting into a high frequency AC. An inverter applied to the transformer primary side, and two sets of secondary side rectifiers for converting the AC output of the transformer secondary side into a DC output in a positive direction and a negative direction with respect to a neutral point;
A pair of switching elements respectively connected to the output sides of these two sets of secondary-side rectifying elements and controlled to alternately supply a positive DC output and a negative DC output to a load; A switching switch TIG in which the output side of a switching element supplying a negative DC output of a pair of switching elements is always connected to a TIG welding electrode, and the output side of the switching element supplying a DC output in a positive direction is separately provided. A wire-energized TIG welding apparatus characterized in that it can be switched and connected to a welding electrode and a power supply tip of a filler wire.