JPH0417748B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a welding device, and particularly to a hot wire TIG welding device that performs good welding. A type of arc welding is TIG welding, which is performed under an inert gas shield using a less consumable metal such as tungsten as an electrode. Although this welding can form a good weld bead, the welding speed is slow, and improvements in this point are desired. As a method for increasing the welding speed in TIG welding, hot wire TIG welding is attracting attention, in which the welding wire is heated to a predetermined temperature before welding. Figure 1 shows the configuration of equipment commonly used in hot wire TIG welding. The tungsten electrode 1 of the welding torch 4 and the base material 2 are connected by an arc power source with DC drooping characteristics, and an arc 5 is formed by the arc power source 3 in a shielding gas such as argon with the tungsten electrode 1 as the negative electrode and the base material 2 as the positive electrode. If the wire 6 sent out from the reel 11 is added directly to this arc 5, it is normal TIG welding, but in the hot wire TIG welding method, the contact tip 7 and the base metal 2 are connected by a DC or AC wire power source 9. However, a direct current or an alternating current is passed through the wire 6 sent from the wire feeding device 10 to the arc generating part to generate heat and heat the wire 6 before welding, thereby increasing the melting speed of the wire 6. . This hot wire
The problem with the TIG welding method is that the wire current causes a magnetic blow phenomenon in the arc. That is, the magnetic field generated near the wire due to the wire current and the magnetic field due to the arc current interfere, and an attractive or repulsive force is generated between the two, causing the arc to swing and making stable welding impossible. For this reason, the wire current is limited to about one-half of the arc current, and the wire melting speed that can be welded without the influence of magnetic blowing is limited to about 20 g/min, making it impossible to significantly improve the welding speed. For this reason, the hot wire switching TIG welding method has been implemented as a method to eliminate the magnetic interference of the arc caused by the wire current and further increase the amount of wire melting. In this method, as shown in Figure 2, the arc current is made into a pulse-like square wave, and during the period _T1 when the arc current is at its peak, the wire is not energized, and the base current at which the arc current is low is used.
The wire current WP is caused to flow only during the period _T2 of AB to eliminate magnetic blowing and to obtain a high welding amount. This eliminates the influence of magnetic blowing.
Melt rates of over 100 g/min are currently being obtained.
FIG. 3 shows the principle of the configuration circuit of a conventionally used hot wire switching TIG power supply, which is an application of a chopper type power supply using a large capacity transistor 20. This method requires a large power transformer 21, a large number of large capacity transistors, and a complex control circuit, resulting in a large and expensive welding machine. It is an object of the present invention to provide a hot wire switching TIG welding power source which eliminates the above-mentioned drawbacks of the prior art, provides a high welding amount, is inexpensive and simple. In short, the present invention provides a device for performing hot wire switching TIG welding that has means for alternately supplying power to a tungsten electrode that generates an arc and a wire, in which a switching element is supplied with power from one power source and is connected in series with an additive wire. A hot wire switching TIG welding device, characterized in that a wire heating control circuit having the following is connected in parallel with the tungsten electrode circuit, and means for switching power supply to the tungsten electrode and the wire by controlling the switching element. It is. FIG. 4 shows a first embodiment of the invention. Reference numeral 23 in the figure indicates gate turn-off.
off) thyristor (hereinafter referred to as "GTO"), and is configured to perform switching using this GTO. Reference numeral 24 designates a conventional arc forming circuit configured to connect the tungsten electrode 1 and the base metal 2 with a welding power source 3 having DC drooping characteristics to form an arc 5 between the electrode 1 and the base metal 2. on the other hand
The GTO 23 is connected to this circuit 24 and the wire 6 (directly to the contact chip 7), and is connected in parallel to the arc 5, and these circuits together form the power supply circuit for hot wire switching TIG welding. It consists of In the device with the above configuration, GTO23 is OFF
At this time, an arc current flows between the electrode and the base material 2, forming an arc 5 and melting the base material 2. GTO23
When turned on, the current flowing to the arc 5 is bypassed and flows from the base metal 2 to the wire 6. The wire is then heated to increase the melting rate. Fifth
The figure shows the above state, and GTO23 is
In the case of OFF, the arc current AP flows, and in the case of ON, the wire current WP flows, and during this period the arc current becomes the base current AB. Next, in the above-mentioned FIG. 4, an auxiliary power source 12 is connected to the circuit 24, and this auxiliary power source 12 maintains the arc when the output of the welding power source 3 is conducted to the wire side by the GTO 23. It supplies the base current AB of the arc. However, when the GTO23 is turned on, the arc 5 disappears and the temperature of the electrode 1 made of tungsten is high enough to easily emit electrons.
If it is turned off, the arc 5 will occur again and the arc current will flow, so this auxiliary power source 12 is not necessarily necessary. FIG. 7 shows a second embodiment of the invention;
The device is configured to improve the controllability of the device shown in the embodiment. That is, the wire melting speed increases in proportion to the electric power applied to the wire, as shown in FIG. 6, and therefore, the wire melting speed can be easily controlled by changing the current value. However, in the embodiment shown in Fig. 4, the peak values of arc current and wire current are
Since AP and WP are equal, only the wire current cannot be controlled individually. The wire melting speed can be controlled by changing the ratio (duty) of the arc current and wire current, but the average value of the arc current changes at the same peak current, so the arc conditions change and this This makes it difficult to maintain proper welding conditions. In this embodiment, a GTO is added in parallel to the method shown in FIG. 4, so that the wire current conduction time can be controlled individually. In other words, in addition to the GTO(1) 23 of the first embodiment, a GTO(2) 25 is provided in parallel, and both GTO(1) 23 and GTO(2) 25 are turned off.
In this state, an arc current AP flows between the electrode 1 and the base material 2 as shown in FIG. At time t ₁
When GTO(1) is turned ON, the arc current is short-circuited to the wire 6, and the wire current WP is passed to heat the wire. Furthermore, at time t ₂ , GTO(2)25 is turned on, and GTO(1) is turned on.
When 23 is turned off, the current is short-circuited to the power supply side, and neither wire current nor arc current flows. Next, when GTO(2) 25 is turned off at time _t3 , an arc occurs again and arc current flows. In other words, the electric power applied to the wire can be adjusted by varying the time the wire is energized, and the melting rate of the wire can now be controlled independently of the arc current. Furthermore, GTO(1)
The same function can be achieved by turning on GTO(2) 23 from _t1 to _t3 and turning on GTO( ₂ ) 25 from t2 to _t3 . Specifically, as shown in FIG. 7, the control device 13 detects the wire current Iw and wire voltage Vw during welding, calculates the wire power Pw=Iw×Vw×(t ₂ −t ₁ )/T,
The rotation speed of the feed motor 10a is controlled so as to obtain a wire feed speed VF corresponding to this. Conversely, control can also be performed by changing the time (t ₂ −t ₁ ) so as to obtain electric power commensurate with the wire feeding speed VF. In addition, the symbols G ₁ and G ₂ in the figure indicate each GTO.
Indicates the ON/OFF interval. Table 1 below shows the range of welding conditions under which hot wire switching TIG welding can be performed using this method and an example of typical welding conditions. FIG. 9 shows a third embodiment, in which other GTOs, that is, GTOs, are used for GTO23 shown in the first embodiment.
(2) 25 are connected in series. In this embodiment, the arc current is shunted to the hot wire 6 by the conduction of GTO (1) 23, and the conduction of GTO (2) 25 is

[Table] The heating state of the hot wire is controlled by controlling the time (power) for applying current to the hot wire 6. In the embodiment, a case has been described in which a GTO is used as a switching element, but a transistor whose switching function is conventionally known may also be used. By implementing the present invention, the device can be made smaller in size compared to a conventional device using a large number of large-capacity transistors, and the controllability of switching and the like can be made equal to or better than that of the conventional device. In addition, this device is a general-purpose device that has been used conventionally.
Since it can be configured by simply adding a switching circuit to the TIG welding power source, it can be implemented in a wide range of conventional devices.

[Brief explanation of drawings]

Figure 1 shows commonly used hot wires.
Basic configuration diagram of TIG welding equipment. Figure 2 is an explanatory diagram of the arc and current flowing through the wire in hot wire switching TIG welding. Figure 3 is a circuit principle diagram of hot wire switching TIG welding equipment using large capacity transistors. , FIG. 4 is a circuit diagram of a hot wire switching TIG welding device showing the first embodiment of the present invention, FIG. 5 is an explanatory diagram of the current of the device shown in FIG. 4, and FIG. A diagram showing the relationship with the melting rate, FIG. 7 is a circuit diagram of a hot wire switching TIG welding device showing the second embodiment, FIG. 8 is an explanatory diagram of the current of the device shown in FIG. 7,
FIG. 9 is a circuit diagram of a hot wire switching TIG welding apparatus and shows a third embodiment. 1...Tungsten electrode, 2...Base material, 3...
Arc power supply, 5... Arc, 6... Wire, 9...
... wire power supply, 23, 25 ... gate turn-off thyristor (GTO), 24 ... arc power supply circuit.

Claims (1)

[Scope of Claims] 1. A hot wire switching TIG welding device having means for alternately supplying power to a tungsten electrode that generates an arc and a wire, which is supplied with power from one power source and connected in series with the additive wire. a wire heating control circuit having a switching element connected in parallel with the tungsten electrode circuit;
A hot wire switching TIG characterized by providing means for switching power supply to a tungsten electrode and a wire by controlling the switching element.
Welding equipment. 2. A wire heating period control circuit having a second switching element is provided in parallel with the tungsten electrode circuit, and the second switching element is controlled to control the period during which the wire heating current is applied to the wire. A hot wire switching TIG welding device according to claim 1, characterized in that: