JPH0321267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention supplies a consumable electrode at a set substantially constant speed, and when either the base current or the pulse current is below a predetermined current value, the constant current characteristic changes to the constant voltage characteristic. The present invention relates to a pulsed arc welding method and apparatus for welding by switching to the pulsed arc welding method.

In the conventional pulsed arc welding method, a consumable electrode (hereinafter referred to as wire) is fed at a preset approximately constant speed, so the method of controlling the arc length to a constant value is to respond to fluctuations in the arc length. There is a first method in which the base current value is changed by changing the base current value, and a second method in which the pulse current value is changed. In the first method, a welding power source with a substantially constant current characteristic that can obtain a substantially constant pulse current value set according to the type of workpiece is used as a pulse current supply power source, and a As the current supply power source, a welding power source with approximately constant voltage characteristics is used that restores the arc length by changing the current value according to changes in the arc length and changing the melting speed of the wire. .

Contrary to the first method, the second method uses a base current supply power source that has approximately constant current characteristics that can obtain an approximately constant base current value that is set according to the type of workpiece. On the other hand, as a power source for supplying pulsed current, a nearly constant voltage characteristic is used to restore the arc length by changing the current value according to fluctuations in the arc length and changing the melting speed of the wire. Welding power source is used. In these first and second methods, the instantaneous value of the output current varies greatly from moment to moment in response to changes in the arc length, so the penetration depth changes particularly in the high current region, causing a molten pool. The drawback was that it became unstable.

Therefore, the present inventors have completed the present invention as a method for obtaining a stable pulsed arc from small currents to large currents.

In the present invention, the wire is fed at a set substantially constant speed, and the average value of the welding current exceeds around a critical current value predetermined by welding conditions such as the material and diameter of the wire, the composition of the shielding gas, etc. In this range, the arc length is maintained stably by the arc length self-control function unique to the arc, and the average value of the welding current is below the vicinity of the critical current value, and the arc length self-control function unique to the arc is maintained stably. In the range where it does not exist, welding can be performed by maintaining the arc length stably by the arc length control action by the current change of the welding power source of the conventional first or second method. The welding result is better than that of the welding method, and despite the wide welding current range, it can be carried out economically with one welding machine. The present invention provides a pulse arc welding method and a welding device.

The first invention of the present application is to feed the wire at a set substantially constant speed, and in a current range exceeding a critical current value predetermined according to welding conditions such as the material and diameter of the wire and the composition of the shielding gas, Both the base current supply power supply and the pulse current supply power supply have substantially constant current characteristics (first characteristics) as welding power sources.
The arc length is maintained stably by the arc length self-control function unique to the arc, and in the current range below the predetermined critical current, either the base current supply power supply or the pulse current supply power supply is operated at a substantially constant current. The welding power source has a characteristic (first characteristic), and the other welding power source has a characteristic (second characteristic) between drooping characteristic and almost constant voltage characteristic, and the arc length due to the current change of the welding power source is This proposed a pulsed arc welding method that welds by stably maintaining the arc length through a control action.

Further, a second invention provides a wire feeding device that feeds a wire at a set substantially constant speed, a base current supply power source that supplies a base current with constant current characteristics to the wire, and a pulsed current that supplies the wire with a pulsed current. A pulse current supply power supply, a constant current characteristic signal generation circuit that generates a control signal for the pulse current supply power supply to output a pulse current having constant current characteristics (first characteristic), and this pulse current supply power supply. is equipped with a constant voltage characteristic signal generation circuit that generates a control signal for outputting a pulse current having the second characteristic, and a characteristic switching circuit that switches these two control signals and supplies the pulsed current supply power supply with the same. The present invention provides a pulse arc welding device.

Furthermore, a third invention provides a pulsed arc welding device in which the characteristics of the base current are switched instead of the characteristics of the pulse current of the second invention.

Hereinafter, the welding method of the present invention will be explained with reference to FIG. This figure shows the melting characteristics of pulsed arc welding, where the horizontal axis shows the average value I _{a [A] of the welding current consisting of the base current and pulsed current, and the vertical axis shows the average value I a} [A] of the welding current consisting of the base current and pulsed voltage. The average value V _a [V] of welding voltage is shown. The three curves shown in the same figure are the average values of welding current using aluminum alloy 5183 using a wire with a diameter of 1.6 mm made of the same material and using wire rapid feeding speeds (10.2, 7.0, and 4.0 [m/min]) as parameters. The relationship between I _a [A] and the average value V _a [V] of welding voltage is shown. In the same figure, the dash-dotted line I _c is the average value of the welding current at which spray transfer is possible without superimposing a pulse current, and is called the critical current value, and for an aluminum alloy wire with a diameter of 1.6 mm, I _c = 180 [ A]. It is well known that splay transition is possible when this critical current value _Ic is exceeded, but even below this current value _Ic , if a pulse current is superimposed, the minimum average current 80
Spray transfer to [A] position is possible. In addition, the three curves V _f1 , V _f2 and V _f3 in the same figure change the arc length by feeding the wire at constant speeds of 10.2, 7.0 and 4.0 [m/min], respectively, and varying the welding voltage. The relationship between the average value I _a [A] of the welding current and the average value V _a [V] of the welding voltage is shown. Each number on the curve indicates the arc length [mm]. In the curve V _f1 , the average value of the welding current decreases as the arc length becomes shorter between 5 [mm] and 0 [mm]. This means that even though the wire feeding speed is constant, the welding current value decreases as the arc length becomes shorter, so if the welding current value is kept constant, the wire will melt as the arc length becomes shorter. It acts in the direction of increasing the arc length as the speed increases. Therefore, in the horizontal component of the curve V _f1 there is an arc-specific self-control effect that automatically controls the arc length. Similarly, for curve V _f2 , the arc length is 5 [mm]
There is an arc-length self-control effect inherent to the arc between 3 mm and 3 mm. But the curve V _f3
In this case, there is almost no horizontal component on the curve, so there is no arc-specific self-control effect.

From the above study results, in the pulsed arc welding method of the present invention in which the wire is fed at a set substantially constant speed for welding, the average value of the welding current varies depending on the material and diameter of the wire and the composition of the shielding gas. A predetermined critical current value (for example, in the example shown in Figure 1, aluminum alloy, 1.6 mm, argon
In the range exceeding 180 [A]), even if both the base current supply power supply and the pulse current supply power supply are welding power supplies with approximately constant current characteristics (first characteristic), the arc length peculiar to the arc The self-control action allows pulse arc welding to be performed while stably maintaining the arc length. Next, in a current range in which the average value of the welding current is around or below the critical current value, either the base current supply power source or the pulse current supply power source is used as a welding power source with substantially constant current characteristics (first characteristic); By using the other as a welding power source with any characteristic (second characteristic) between the drooping characteristic and the almost constant voltage characteristic, the arc length can be stabilized by the arc length control effect due to the current change of the welding power source. Pulse arc welding can be performed by maintaining the

Next, the pulse arc welding apparatus of the present invention will be explained with reference to FIGS. 2 and 3.

In FIG. 2, W is an object to be welded, E is a wire, and an arc A is generated between them. 1 is
A wire feeding control circuit receives the signal set by the wire feeding speed setting circuit 1a as input and supplies an output to the wire feeding motor M, R is a feeding roll rotated by the electric motor M to feed the wire E. , 10 is a welding power source that is connected to a commercial frequency power source (not shown) and outputs welding power, and 11 is a welding power source 10.
11a is a pulse current control circuit that controls the power output from the circuit and supplies a pulse current to wire E through reactor L and chip T; 11 is a pulse current setting circuit that outputs an output, 12 is a base current control circuit that controls the power output from the welding power source 10 and supplies a base current to the wire E through the reactor L and the chip T, and 12a corresponds to the base current value. This is a base current setting circuit that outputs a signal to the base current control circuit 12. Welding power source 10, pulse current control circuit 11, and pulse current setting circuit 11a constitute a pulse current supply power source, and welding power source 10, base current control circuit 12, and base current setting circuit 12a constitute base current supply. Configuring the power supply. 13 is a power output setting circuit, VD is a welding voltage detection circuit that detects the average value of the welding voltage, pulse voltage or base voltage, and 14 is the output signal V _r of the power output setting circuit 13 and the welding voltage detection circuit VD. Compare the output signal V _p and the difference signal V _r
The comparison circuit 13a which outputs _-Vp is an attenuation circuit which inputs the output signal _Vr of the power output setting circuit 13 and adjusts the signal level to the output signal _{Vr -Vp} of the comparison circuit 14. 15 is a characteristic having, for example, a first fixed contact CP to which the output signal V _r -V _p of the comparison circuit 14 is supplied and a second fixed contact CC to which the output signal V _r ' of the attenuation circuit 13a is supplied. This is a characteristic switching circuit composed of a changeover switch SW. Reference numeral 16 denotes a signal conversion circuit that receives the output signal of the movable contact of the characteristic changeover switch SW and outputs a signal for controlling at least one of the pulse current value, pulse frequency, and pulse duration to the pulse current control circuit 11.

The above power output setting circuit 13 and attenuation circuit 13a
This constitutes a constant current characteristic (first characteristic) signal generation circuit, and the power output setting circuit 13, the welding voltage detection circuit VD, and the comparison circuit 14 constitute a constant current characteristic (first characteristic) signal generation circuit. A control signal generating circuit (hereinafter referred to as a constant voltage characteristic signal generating circuit) having one characteristic (second characteristic) is configured.

With the configuration described above, the characteristic changeover switch SW
When the movable contact of is connected to the fixed contact CC side, the pulse current control circuit 11 has the power output setting circuit 1
Output signal of attenuation circuit 13a input from 3
V _r ' is supplied through the signal conversion circuit 16. Therefore, a pulse current with a constant current characteristic (first characteristic) is supplied to the wire E and the workpiece W, and as described above, the arc length is stably maintained by the arc length self-control function inherent to the arc. Then perform pulse arc welding. Next, when the movable contact of the characteristic changeover switch SW is connected to the fixed contact CP side, the pulse current control circuit 11 receives the output signal V _r of the power output setting circuit 13 and the output signal V _p of the welding voltage detection circuit VD. The difference signal V _r -V _p is fed back through the signal conversion circuit 16. Therefore, the pulse current of any one characteristic (second characteristic) between the drooping characteristic and the constant voltage characteristic is applied to the wire E and the workpiece W.
As described above, pulse arc welding is performed by stably maintaining the arc length by controlling the arc length by changing the output current of the welding power source.

To change the above-mentioned characteristic changeover switch SW, the welding operator may change it directly or by using a torch switch, foot switch, or other remote switch during welding or during a welding pause, but as shown in Fig. 3. Alternatively, the welding current value may be automatically switched when reaching a preset welding current value (critical current value I _c ).

FIG. 3 shows, in addition to the configuration shown in FIG. 2, a characteristic switching current setting circuit (hereinafter referred to as a switching setting circuit) 17 and a welding current detection circuit ID as a characteristic switching circuit.
These two output signals I _r and I _p are compared and a signal I _r − is used to operate the characteristic changeover switch SW.
A characteristic switching current comparison circuit (hereinafter referred to as a current comparison circuit) 18 that outputs I _p is provided. This switching setting circuit 17 is set to output a signal I _p corresponding to a value somewhat larger than the critical current value I _c explained in FIG. A signal I _p corresponding to this critical current value
The value depends on the wire material used, the wire diameter,
It is set in accordance with the critical current value I _c which changes depending on the components of the shielding gas, etc.

Next, the operation shown in FIG. 3 will be explained. In the figure, when the average value I _a of the welding current is larger than the critical current value I _c , the output signal I _p of the welding current detection circuit ID becomes larger than the output signal I _r of the switching setting circuit 17. Therefore, the output signal of the current comparison circuit 18 I _r −I _p
operates the characteristic changeover switch SW to connect the movable contact to the fixed contact CC side. Therefore, the second
As described above in the figure, the pulse current control circuit 11 receives the output signal V _r ' of the attenuation circuit 13a inputted from the power output setting circuit 13 and outputs it to the signal conversion circuit 1.
6, a pulsed current with a substantially constant current characteristic (first characteristic) is supplied between the wire E and the workpiece W, and the arc length is maintained stably by the arc length self-control action inherent to the arc. Then perform pulse arc welding. Next, when the average value I _a of the welding current becomes smaller than the critical current value I _c , the switching setting circuit 17
The output signal I _r of the welding current detection circuit ID is the output signal I _p of the welding current detection circuit ID.
Therefore, the output signal I _r -I _p of the current comparison circuit 18 returns the characteristic changeover switch SW and connects it to the movable contact CP side. Therefore, as described above in FIG.
1 is a signal representing the difference between the output signal V _r of the power output setting circuit 13 and the output signal V _p of the welding voltage detection circuit VD.
V _r −V _p is fed back through the signal conversion circuit 16, and a pulse current having any characteristic (second characteristic) between the drooping characteristic and the substantially constant voltage characteristic is supplied to the wire E and the workpiece W. Pulse arc welding is performed by stably maintaining the arc length by controlling the arc length by varying the welding current of the welding power source.

In the embodiments shown in FIGS. 2 and 3 described above, the output signal of the signal conversion circuit 16 is supplied to the pulse current control circuit 11 as shown by the solid line, and the pulse current is changed from constant current characteristics to constant voltage characteristics. Instead, the output signal of the signal conversion circuit 16 is supplied to the base current control circuit 12 as shown by the dashed line, and the base current is changed to one of the constant current characteristics. The characteristics may be changed to any one of the characteristics from 1 to 2 to constant voltage characteristics. Note that although the SW in FIGS. 2 and 3 uses a movable contact, it is naturally possible to perform non-contact switching using a semiconductor.

Furthermore, in the embodiments of FIGS. 2 and 3,
As shown by the two-dot chain line, the output signal of the wire feeding speed setting circuit 1a is output from the power supply output setting circuit 13, the pulse current setting circuit 11a, or the base current setting circuit 1.
2a to centrally adjust the wire feeding speed and the pulse current or base current.

As described above, according to the welding method and welding device of the present invention, when the welding current value exceeds a predetermined value, both the base current supply power supply and the pulse current supply power supply have constant current characteristics. Even if the arc length fluctuates, the welding current remains constant and the penetration depth remains constant.The arc length can also be maintained constant due to the arc's own self-control action, and the welding current value remains at a predetermined value. If the voltage is below, either the base current supply power supply or the pulse current supply power supply should be brought close to constant voltage characteristics.
By having arc length control performed by the average current variation of the power supply, pulsed spray transfer provides better welding results than either conventional single method without the addition of a special arc length control circuit. Arc welding can be performed, and spray transfer arc welding can be performed over a wide range of current values from small current values below the critical current value to large current values with one welding machine, which is economical.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the average value of welding current I _a (horizontal axis) and welding voltage V _a (vertical axis) using wire feed speed V _f as a parameter, Figures 2 and 3 1 is a configuration diagram showing an embodiment of a welding apparatus of the present invention. E...Consumable electrode (wire), 10 and 12
... Base current supply power source (10... Welding power source, 12... Base current control circuit), 10 and 11... Pulse current supply power source (10... Welding power source, 11... Pulse current control circuit) , 1, M and 1a... wire feeding device (1... wire feeding control circuit, M... wire feeding motor, 1a... wire feeding speed setting circuit), 13... constant current characteristic signal generation circuit (13...Power output setting circuit, 13a
...attenuation circuit), 13, VD, 14 and 19...
... Constant voltage characteristic signal generation circuit (13 ... Power output setting circuit, VD ... Welding voltage detection circuit, 14 ... Comparison circuit), 15 ... Characteristic switching circuit (17 ... Current value setting circuit for characteristic switching, ID ...Welding current detection circuit, 18...Characteristic switching current comparison circuit, SW...Characteristic switching switch).

Claims (1)

[Claims] 1. Feeding the consumable electrode at a set substantially constant speed;
In a pulsed arc welding method in which a base current and a pulsed current are supplied to the consumable electrode for welding, the average value of the welding current is determined in advance according to welding conditions such as the material and diameter of the consumable electrode and the composition of the shielding gas. In the current range exceeding the vicinity of the determined critical current value, both the base current supply power supply and the pulse current supply power supply function as welding power supplies with approximately constant current characteristics (first characteristic), and the arc length self-control function inherent to the arc is applied. In a current range where the arc length is maintained stably and the average value of the welding current is around or below the critical current value, either the base current supply power supply or the pulse current supply power supply is operated at a substantially constant current. By using the welding power source as a welding power source with a characteristic (first characteristic) and the other as a welding power source with one characteristic (second characteristic) between drooping characteristic and substantially constant voltage characteristic, A pulse arc welding method that maintains a stable arc length by controlling the arc length by changing the current. 2. a wire feeding device that feeds the consumable electrode at a set substantially constant speed; a base current supply power source that supplies the consumable electrode with a base current having substantially constant current characteristics;
a pulse current supply power supply that supplies a pulse current to the consumable electrode; and a constant current characteristic signal that generates a control signal for the pulse current supply power supply to output a pulse current having constant current characteristics (first characteristic). a constant voltage characteristic signal that generates a control signal for the pulse current supply power supply to output a pulse current having any one characteristic (second characteristic) between a drooping characteristic and a substantially constant voltage characteristic; The generator circuit switches the constant current characteristic signal in a current range in which the average value of the welding current exceeds around the critical current value, and switches the constant voltage characteristic signal in the current range below around the critical current value to generate the pulsed current supply power source. A pulse arc welding device equipped with a characteristic switching circuit that supplies power to the pulse arc welding device. 3. The base current supply power supply and the pulsed current supply power supply include a welding power supply, a base current control circuit, and a pulsed current control circuit, and the output signal of the characteristic switching circuit is supplied to the pulsed current control circuit. A pulse arc welding device according to claim 2. 4. The constant current characteristic signal generation circuit includes a power output setting circuit and an attenuation circuit, and the constant voltage characteristic signal generation circuit includes the power output setting circuit, the welding voltage detection circuit, and the outputs of the two circuits. The pulse arc welding apparatus according to claim 2, further comprising a comparison circuit that outputs a signal representing a difference between the signals. 5. The characteristic switching circuit comprises a characteristic switching switch;
The pulse arc welding device according to claim 2, comprising a welding current detection circuit, a characteristic switching current value setting circuit, and a characteristic switching current comparison circuit that outputs a difference between the output signals of the two circuits. . 6. The wire feeding device includes a wire feeding speed setting circuit, a wire feeding control circuit, and a wire feeding motor, and the power output setting circuit includes:
The pulse arc welding apparatus according to claim 2, wherein the output signal of the wire feed setting circuit is input. 7. A wire feeding device that feeds a consumable electrode at a set substantially constant speed, a pulse current supply power source that supplies a constant pulse current to the consumable electrode, and a base that supplies a base current to the consumable electrode. a current supply power supply; a constant current signal generation circuit that generates a control signal for the base current supply power supply to output a base current having a constant current characteristic (first characteristic); A constant voltage characteristic signal generation circuit that generates a control signal for outputting a base current of any one characteristic (second characteristic) from characteristics to constant voltage characteristics, and a characteristic switching circuit that switches the constant current characteristic signal in a current range exceeding a critical current value and the constant voltage characteristic signal in a current range below a critical current value and supplies the same to the pulse current supply power source. 8. The base current supply power source and the pulse current supply power source include a welding power source, a base current control circuit, and a pulse current control circuit, and the output signal of the characteristic switching circuit is supplied to the base current control circuit. A pulse arc welding device according to claim 7. 9. The constant current characteristic signal generation circuit includes a power output setting circuit and an attenuation circuit, and the constant voltage characteristic signal generation circuit includes the power output setting circuit, the welding voltage detection circuit, and the outputs of the two circuits. The pulse arc welding apparatus according to claim 7, further comprising a comparison circuit that outputs a signal representing a difference between the signals. 10 A patent claim in which the characteristic switching circuit comprises a characteristic switching switch, a welding current detection circuit, a characteristic switching current value setting circuit, and a characteristic switching current comparison circuit that outputs a difference between the output signals of the two circuits. The pulse arc welding device according to item 7. 11 The wire feeding device includes a wire feeding speed setting circuit, a wire feeding control circuit, and a wire feeding motor, and the power output setting circuit includes:
The pulse arc welding apparatus according to claim 7, wherein the output signal of the wire feed speed setting circuit is input.