JPH1128567A - Pulse arc welding power source and reactor for pulse arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely conduct heat input control and to improve welding quality. SOLUTION: A first wire (p) constituting a reactor P and a second wire (b) constituting a reactor B are wound to the same iron core (f), for a pulse period the reactor P is connected to an output circuit and the reactor B is cut off from the output circuit, further for a base period the reactor B is connected to the output circuit and the reactor P is cut off from the output circuit, also, the reactor P and the reactor B are connected to the output circuit so that directions of the magnetic fluxes formed by the reactor P and the reactor B are made same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse arc welding power supply and a reactor for pulse arc welding.

[0002]

2. Description of the Related Art FIG. 8 is an external connection diagram of a conventional consumable electrode type pulse arc welding power supply. Reference numeral 2 denotes a power supply unit of the welding power supply 1, which reduces the voltage of the three-phase AC power supply 4 to a voltage suitable for welding by a transformer 3, rectifies and smoothes the voltage by a diode 5 and a capacitor 6, and supplies a DC voltage between terminals A and B. Supply output. 7 and 8 are switching elements, 9 and 10 are diodes, 11 and 12 are reactors, and 13 and 14 are external output terminals. Note that the inductance value of the reactor 12 is larger than the inductance value of the reactor 11. Reference numeral 15 denotes an output cable on the positive side.
Are connected. 17 is a torch, 18 is a welding load, 19
Is a base material. Reference numeral 20 denotes a negative output cable, which connects the external output terminal 14 and the base material 19.

The operation will be described below. During the base period Tb, the switching element 7 is turned on / off by PWM control. When the switch is turned on, the base current Ib is changed from the terminal A → the switching element 7 → the reactor 11 → the reactor 12 → the external output terminal 13 → the output cable 15 → the wire 16 → the welding load 18 → by the DC output supplied from the power supply unit 2.
It flows through the circuit in the order of base material 19 → output cable 20 → external output terminal 14 → terminal B. In the off state, the energy stored in the reactors 11 and 12 causes the base current I
b is reactor 11 → reactor 12 → external output terminal 13 →
Output cable 15 → wire 16 → welding load 18 → base metal 1
9 → output cable 20 → external output terminal 14 → diode 9 Hereinafter, the portion from the external output terminal 13 to the external output terminal 14 in the above circuit is referred to as a load K.

[0004] In the pulse period Tp, the switching element 8 is turned on and off by PWM control. When the power supply is on, the DC output supplied from the power supply unit 2
Pulse current Ip is terminal A → switching element 8 → reactor 12 → external output terminal 13 → load K → external output terminal 14
→ It flows through the circuit in the order of terminal B. In the off state, the energy stored in the reactor 12 causes the pulse current I
p flows back in the order of the reactor 12, the external output terminal 13, the load K, the external output terminal 14, and the diode 10.

[0005]

FIG. 9 is a diagram showing an output current waveform when welding is performed by the above-mentioned conventional pulse arc welding power source. As is clear from the figure, the rise of the current in the period Tu after the transition from the base period Tb to the pulse period Tp has a gentle slope. Therefore, if the set pulse period Tp is shorter than the period Tu, the pulse current actually flowing to the welding load 18 becomes smaller than the set pulse current, so that the droplet transfer becomes unstable and the welding quality is reduced. . Further, the pulse period Tp is changed to the base period Tb.
The falling of the current in the period Td after the transition to the above also has a gentle slope. Therefore, if the set base period Tb is shorter than the period Td, the base current actually flowing to the welding load 18 becomes larger than the set base current, so that the droplet transfer becomes unstable. Further, in the base period Tb,
Since the short-circuit current at the time of short-circuit becomes large, the occurrence of spatters increases, and the welding quality deteriorates.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a pulse arc welding power source and a reactor for pulse arc welding that can reliably perform heat input control and improve welding quality.

[0007]

An object of the present invention is to provide a pulse current reactor P and a base current reactor B in an output circuit so that a pulse current Ip and a base current Ib are alternately supplied to a welding load. In the pulsed arc welding power source described above, the first line forming the reactor P and the reactor B
Is wound around the same iron core, the reactor P is connected to the output circuit during the pulse period and the reactor B is disconnected from the output circuit, and the reactor B is disconnected from the output circuit during the base period. This problem can be solved by connecting to an output circuit and disconnecting the reactor P from the output circuit, and connecting to the output circuit so that the directions of magnetic fluxes formed in the reactor P and the reactor B are the same. You.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described. FIG. 1 is a connection diagram of a consumable electrode type pulse arc welding power supply according to the present invention. Note that the same components or components having the same functions as those in FIG. 8 are denoted by the same reference numerals and description thereof is omitted. Reference numeral 30 denotes a switch, and when the contacts m and n are closed, the contact r,
When s is opened and contacts r and s are closed, contacts m and n are opened. The contact m is connected to the output side of the switching element 7 and the contact r
Are connected to the output side of the switching element 8, respectively. Reference numeral 31 denotes a reactor, which is composed of a winding p, a winding b, and one iron core f, and is magnetically coupled by winding the winding p and the winding b around the iron core f. And winding b and iron core f
And the reactor B with the winding p and the iron core f.
Is configured. One end of each of the windings b and p is connected to the output circuit such that the directions of magnetic fluxes formed by currents flowing through the windings b and p are the same. The value of the self-inductance of the reactor B is Lb, and the value of the reactor P is
Has a value of Lp.

The operation will be described below. In the base period Tb, the contacts m and n are closed. The base current Ib is supplied to an external load via the reactor B by the chopper control of the switching element 7 (hereinafter, a circuit formed when the contacts m and n are closed is referred to as a base current circuit). . In the pulse period Tp, the contacts r and s are closed. The pulse current Ip is supplied to an external load via the reactor P by the chopper control of the switching element 8 (hereinafter, a circuit formed when the contacts r and s are closed is referred to as a pulse current circuit). .

FIG. 2 shows a current waveform in the present invention.
The operation during the transition will be described with reference to FIG. The energy Ep stored in the reactor P when the pulse current Ip flows is ×× Lp × Ip ² , and the energy Eb stored in the reactor B when the base current Ib flows is ×× Lb × Ib ² . is there.

In the transition from the pulse period Tp to the base period Tb, the pulse current circuit is cut off on the reactor P side from the diode 10, so that no return circuit is formed, and all the energy Ep stored in the reactor P is consumed by the reactor P. B
Move to Further, the pulse period Tp is changed from the base period Tb to the pulse period Tp.
Similarly, all the energy Eb stored in the reactor B shifts to the reactor P. Therefore, if the coupling coefficient between reactor B and reactor P is α (where α ≦ 1), the following equations 1 and 2 hold. Equation 1 is a case where the pulse period Tp shifts to the base period Tb, and Equation 2 is a case where the base period Tb shifts to the pulse period Tb.
p. In addition, since the self-inductance is approximately proportional to the square of the number of turns, the following equation 3 holds.
Then, the following Expression 4 is obtained from Expressions 1 and 3, and the following Expression 5 is obtained from Expressions 2 and 3.

Α × 1/2 × Lp × (Ip) ² = 1/2 × Lb × (Ib) ² Equation 1 α × 1/2 × Lb × (Ib) ² = 1/2 × Lp × ( Ip) ² Equation 2 Lp = Lb × (Np / Nb) ² Equation 3 Ib = Np / Nb × Ip × √α Equation 4 Ip = Nb / Np × Ib × √α Equation 5 As is clear from Equation 5, when the base period Tb shifts to the pulse period Tp and the final current in the base period Tb is Ib ₀ , the pulse current in the pulse period Tp immediately becomes Ip ₀ (= Nb / Np × Ib ₀ × √α). From the above equation 4, when the pulse period Tp shifts to the base period Tb, the current of the pulse period Tp becomes Ip
, The base current immediately drops to Ib.

FIG. 3 is a photograph showing an actual current waveform.
= 550A, Ib = 90A, Tp = 1.6 ms, Tb =
This is the case of 1.6 ms. As is clear from the photograph, the rising and falling slopes of the current are steep, and it can be seen that the period Tu and the period Td in the related art can be made substantially zero.

FIG. 4 is a diagram showing a second embodiment of the present invention, in which the same components as those in FIG. 1 or those having the same functions are denoted by the same reference numerals. 32 is a diode. In this embodiment, switching elements 7, 8 and diodes 9, 1
The combination of 0 and 32 replaces the switch 30 in the first embodiment. That is, during the base period Tb, the switching element 8 is opened and the switching element 7 is chopper-controlled. In the pulse period Tp, the switching element 7 is chopper-controlled while the switching element 8 is closed. Note that the pulse period T
At p, a reverse bias is applied to the winding b by the current flowing through the winding p, and as a result, the voltage on the cathode side of the diode 32 becomes higher than the voltage on the anode side, so that the diode 32 becomes non-conductive. This is the same as the pulse current circuit in the first embodiment.

Note that the pulse period Tp is changed to the base period Tb.
And the base period Tb
Since the rise of the current at the time of shifting to the pulse period Tp is exactly the same as in the first embodiment, the description is omitted.

FIG. 5 is a diagram showing a modification of the second embodiment of the present invention, in which the same reference numerals as those in FIGS. In the figure, 51 is an inverter, 52 is a transformer, and 53 is a diode. Here, the operation of the portion surrounded by the dotted line in the figure will be described. The DC voltage input by the inverter 51 is converted into an AC voltage, and the AC voltage is converted by the transformer 52 into a voltage suitable for welding. Rectification is performed by a rectification circuit including 9, 10, 31, and 53. As a result, the outputs output to the output terminals J and B become substantially the same as those of the switching element 7 in the second embodiment. The falling of the current when shifting from the pulse period Tp to the base period Tb and the rising of the current when shifting from the base period Tb to the pulse period Tp are exactly the same as those in the first embodiment, and therefore the description is omitted. I do.

In this modification, the pulse period Tp
And the number of turns of the transformer 52 in the base period Tb is changed, the current waveforms of the pulse current Ip and the base current Ib can both be flat waveforms with small ripples. Further, among the terminals of the transformer 52, the terminals a and e are not provided, and only the terminals b, B and d are provided, and the connection point J in the figure may be connected to the connection point K. Then, it becomes almost the same as the second embodiment.

The number of turns Np and Nb are fixed.
Therefore, as is apparent from the above equations 4 and 5, when the value of the pulse current Ip is determined, the value of the base current Ib becomes a fixed value, and the magnitude cannot be changed. Therefore,
Reactor P and reactor B with different turns ratio Np / Nb
May be provided, and the connection may be changed according to welding conditions (for example, welding with a large current and welding with a small current).

FIG. 6 is a view showing a second embodiment of the reactor 31, in which the connection positions of the windings b and p in FIG. 1 are changed. That is, the base current Ib flows through both the winding b1 and the winding b2 (ie, the winding p), and the pulse current Ip flows through the winding p (ie, the winding b2).
By doing so, the degree of magnetic coupling between the winding p and the winding b can be improved as compared with that shown in FIG.

FIG. 7 is a diagram showing a third embodiment of the reactor 31. The winding p in FIG.
2 and connected in parallel. In this way, the degree of magnetic coupling between the winding p and the winding b can be further improved as compared with that shown in FIG.

When the windings p and b are wound edgewise, the degree of magnetic coupling can be improved. Further, at least the winding p is formed into a plurality of parallel windings,
By alternately arranging the windings p and the windings b, the degree of magnetic coupling can be improved. Further, in the above description, one iron core has been described, but a so-called outer iron core structure, which is substantially one iron core, may be used.

[0022]

As described above, according to the present invention,
Reactor P for pulse current and reactor B for base current
In the pulse arc welding power supply in which the pulse current Ip and the base current Ib are alternately supplied to the welding load, the first line p forming the reactor P and the second line forming the reactor B are provided in the output circuit. A line b is wound around the same iron core, and the pulse period connects the reactor P to the output circuit and disconnects the reactor B from the output circuit. The base period connects the reactor B to the output circuit. And the reactor P is disconnected from the output circuit, and connected to the output circuit such that the directions of magnetic fluxes formed in the reactor P and the reactor B are the same, so that the pulse period Tp to the base period Tb At the time of transition from the base period Tp to the pulse period Tb, the welding current is immediately changed to the preset base current Ib or the preset pulse current. It is possible to scan current Ip.
Therefore, even when the pulse period Tp or the base period Tb is short, it is possible to carry out a proper droplet transfer and improve the welding quality. Further, even when the base period Tb is short, the occurrence of spatter can be prevented by reducing the short-circuit current when short-circuiting occurs in the base period Tb.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a consumable electrode type pulse arc welding power supply according to the present invention.

FIG. 2 is a diagram showing an output current waveform in the present invention.

FIG. 3 is a photograph of an actual current waveform according to the present invention.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5 is a diagram showing a modification of the second embodiment of the present invention.

FIG. 6 is a diagram showing a second embodiment of the reactor 31.

FIG. 7 is a diagram showing a third embodiment of the reactor 31.

FIG. 8 is a connection diagram of a conventional consumable electrode type pulse arc welding power supply.

FIG. 9 is a diagram showing a conventional output current waveform.

[Explanation of symbols]

 31 Reactor B Reactor P Reactor b Second line p First line f Iron core

Claims (6)

[Claims] In a pulse arc welding power source, a pulse current reactor P and a base current reactor B are provided in an output circuit, and a pulse current Ip and a base current Ib are alternately supplied to a welding load. A first wire forming P and a second wire forming reactor B are wound around the same iron core, and during the pulse period, the reactor P is connected to the output circuit and the reactor B is disconnected from the output circuit. In the base period, the reactor B is connected to the output circuit and the reactor P is disconnected from the output circuit so that the directions of magnetic fluxes formed in the reactor P and the reactor B are the same. And a pulse arc welding power source connected to the output circuit. 2. A first wire and a second wire wound on the same iron core.
The reactor P and the reactor B consisting of
A plurality of sets are provided by changing the winding ratio of the second wire and the second wire, and one of the plurality of reactors P and one of the reactors B is connected according to welding conditions. 2. The pulse arc welding power source according to 1. 3. A winding comprising a winding p and a winding b and one iron core, wherein the winding p and the winding b are wound around the iron core to be magnetically coupled and wound around the iron core. The line p is connected to the reactor P
A reactor for pulse arc welding, wherein the wire b wound around the iron core is used as a reactor B. 4. The reactor for pulse arc welding according to claim 3, wherein the magnetic coupling between the reactor P and the reactor B is made dense by forming a plurality of parallel windings of the winding p. 5. The winding p and the winding b are edgewise wound,
5. The pulse arc welding according to claim 3, wherein at least the winding p is formed in a plurality of parallel windings, and the windings p and the windings b are alternately arranged. Reactor. 6. The reactor for pulse arc welding according to claim 3, wherein the iron core structure is a shell type.