JPH0615108B2 - Hot Wire TIG Welding Equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot wire TIG welding apparatus, and more particularly to a welding apparatus having a power source structure that can achieve a large melting amount at a low cost.

<Prior art and its problems> While TIG welding has the advantage that high welding quality can be obtained, it has the disadvantage that the welding speed is slow and the efficiency is low. The hot wire TIG welding method, which preheats the wire supplied to the weld, was devised as a countermeasure against this. FIG. 5 shows the principle.

An arc 5 is generated between the tungsten electrode 4 attached to the torch 3 and the base material 8 to melt the base material. At that time, if the wire is simply added and welded, the normal TIG welding is used. In the hot wire TIG welding, the wire heating power source 2 is connected to the contact chip 7 and the base metal 8, and the wire is energized to generate juule heat. By welding while heating, the welding efficiency can be greatly improved.

However, this method causes a so-called magnetic blowing phenomenon in which the magnetic field generated by the wire heating current and the arc interfere with each other and the arc 5 is deflected, resulting in very poor workability. For this reason, the range of appropriate welding conditions becomes extremely narrow, and the amount of deposition is limited to about 40 g / min.

Therefore, a hot wire switching TIG (hereinafter abbreviated as HST) welding method has been devised as a method for solving the problem of magnetic blowing and further improving the welding efficiency while maintaining high quality and good workability. Shows the current conduction principle of the HST welding in FIG. 7, the arc current peak (I _AP), a pulsed current having a base (I _AB), I _AP period without current for wire heating I _AB This is a method in which the wire is electrically heated only during the period to substantially eliminate the influence of magnetic blowing.

Fig. 6 shows the basic structure of the HST welding power source. It has two power sources, a TIG power source 1 and a wire heating power source 2, and each has a switching part including a transistor 13 and the like inside thereof, and an arc current and a wire current are mutually passed by a control circuit 11. According to this method, welding can be performed at a high efficiency of 100 g / min or more, and the magnetic spray phenomenon can be substantially prevented, so that the welding quality is also improved.

By the way, this power supply performs switching by analogly controlling the arc current and the wire current value, requires a large number of large capacity transistors, and has a complicated control circuit. Moreover, because the transformer is large, the power supply is very expensive and large.

In order to solve these problems, the inventors previously proposed the method of FIG. 4 as Japanese Patent Application No. 58-177124. In this method, the proper heating control of the wire is performed during the energization time. By connecting a GTO (gate turn-off thyristor) 9 connected in series with the wire in parallel with the arc, the TIG power supply 1
The current output from the arc 5 is shunted to the wire 6 side for heating. Further, the GTO 10 connected in parallel with this was made conductive to adjust the energization time to the wire, and both GTOs 9 and 10 were arranged in parallel in the same circuit 20.

Since this method can supply current to the arc and wire with one power source, the current can be made cheaper than the method shown in FIG. 5, but the welding efficiency is at most 30.
It is about 40 g / min, which is not very useful for improving the welding efficiency.

<Object of the present invention> An object of the present invention is to provide a hot wire TIG welding apparatus which eliminates the above-mentioned drawbacks of the prior art, achieves high efficiency without the influence of magnetic spraying, and is inexpensive and has a practical large melting capacity. There is.

<Summary of the present invention> In short, the present invention, in a welding apparatus for performing welding by alternately energizing an arc current and a wire current, a switching element is arranged in parallel with the arc power circuit to provide a pulse arc current. Other switching elements are arranged in series with the wire for the hot wire heating power supply circuit, and each of these switching elements is heated only while the switching element of the arc power supply circuit is ON. The hot wire TIG welding apparatus is characterized in that each is connected to a control circuit for controlling the switching element of the power supply circuit for turning on.

<Embodiment> FIG. 1 shows an example of an HST power supply configuration according to the present invention. In the TIG power supply 1, a GTO 9 is connected in parallel with the arc 5 to the output of the constant current power supply whose setting current is variable.
A circuit 21 is formed so that a pulse arc current can be formed by N-OFF. On the other hand, to the wire heating power source 2, the GTO 10 is connected to the output of the constant voltage power source whose setting voltage is variable so as to be in series with the wire 6 to configure the circuit 22, and both circuits are connected via the base material 8. The wire is periodically energized and heated while the arc power is low. Reference numeral 11 is a control circuit for controlling the current of both circuits.

Fig. 2 shows the time variation of arc and wire currents and GTO.
The ON / OFF timing of 1 (reference numeral 9) and GTO2 (reference numeral 10) is shown.

The arc current is changed in pulses by repeating ON-OFF of GIT1 (9). The arc is output to the electrode 4 side while GTO1 is conducting and the current is short-circuited in the power supply 1. The current is essentially zero and the arc disappears. Therefore, it is necessary to maintain the arc 5 by some method. However, it is known that when the current is supplied to the arc while the space between the tungsten electrode 4 and the base material 8 is in the plasma state, the arc is re-ignited. The arc is in almost the same state as it is formed continuously. In addition, considering the GTO heat generation and arc flickering, a switching frequency of 1 / T of 30 to 200 Hz is appropriate. Further, the arc current conduction time ratio Tα / T is
0.5 to 1.0, and the wire current energization time ratio Tω / T may be changed in the range of 0 to 0.5 according to the feeding speed.

The heating of electricity to the wire is performed by conducting GTO2 while GTO1 is conducting and the arc current is short-circuited. At this time, the output voltage of the wire heating power supply is controlled and the peak value of the conducting current I _{In addition} to controlling _WP , the wire energization time TW is adjusted so that the wire heating power corresponding to the wire feeding speed is supplied.

FIG. 3 shows the relationship between the wire melting speed VW and the power applied to the wire Pw when the wire is melted only by energizing the wire without generating an arc, but both are in a proportional relationship. It shows that the proper heating amount of the wire can be obtained by changing Pw.

That is, the heating amount of the wire can be controlled by controlling the output voltage of the wire heating power source to change the peak value of the energizing current or by changing the energizing time as shown in FIG.

Therefore, the output voltage of the wire heating current is initially set to an appropriate value, and the value is controlled so as to be kept constant. During welding, the distance between the contact chip 7 and the base metal 8 changes and the wire resistance changes. When I _WP changes, the wire energization time T
The electric power can be adjusted to be constant by changing w, and proper heating control of the wire can be easily performed.

That is, in the present invention, since the heating of the wire can be digitally controlled by turning the current ON and OFF, compared with the conventional method in which the current value is changed in an analog manner as shown in FIGS. 6 and 7. , The control circuit is very simple, and it can be used with a simple modification such as connecting a switching element in parallel or in series to a general-purpose constant current type or constant voltage type welding power source. It became like this.

In the example shown in FIG. 1, the switching element is a GTO.
However, the present invention is not limited to this, and a large capacity transistor or the like may be used.

Originally, HST welding is a welding method that eliminates the influence of magnetic spraying and achieves high efficiency and high quality. In the conventional HST power supply, switching of arc current and wire current is performed in an analog manner, so a large number of large capacity transistors are used, and since the transformer is also large, it is an expensive and large power supply. In the HST power supply of the present invention, since the switching control is performed digitally, the control becomes very simple, and since it can be used by simply modifying the general-purpose power supply, it has the same performance as the conventional method. The cost of power supply is about 1/4
Can be

<Effect> As described above, the present invention makes it extremely easy to control, and can significantly reduce the power supply cost while maintaining high welding quality.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the configuration of the HST power supply of the present invention, and FIG.
FIG. 3 is a diagram showing the principle of energization, FIG. 3 is a diagram showing the relationship between the wire melting rate and heating power when a wire is energized, and FIG. 4 is a circuit diagram showing a technique prior to the present invention. 5
The figure shows the principle of general hot wire TIG welding.
FIG. 7 is a diagram showing the principle of a conventional HST power supply, and FIG. 7 is a diagram showing the energization principle of the conventional technique. 1 …… TIG power supply, 2 …… Wire heating power supply 5 …… Arc, 6 …… Wire 9,10 …… GTO, 11 …… Control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihide Kondo 6-9 Takara-cho, Kure-shi, Hiroshima Babkotuku Hitachi Ltd., Kure Factory (56) Reference JP-A-59-179274 (JP, A)

Claims (2)

[Claims] 1. A welding apparatus for welding by alternately passing an arc current and a wire current, wherein a switching element is arranged in parallel with an arc in a power source circuit to form a pulsed arc current. , Another switching element is arranged in series with the wire for the hot wire heating power supply circuit, and each of these switching elements is switched only when the switching element of the arc power supply circuit is ON. A hot wire TIG welding device, each of which is connected to a control circuit for controlling to turn on. 2. A wire heating power source is a constant voltage power source with a variable set voltage, and in addition to this, a control function of a wire energizing time is added to the control circuit to control the wire heating to adjust the output voltage of the power source. The hot wire TIG welding apparatus according to claim 1, wherein the hot wire TIG welding apparatus is configured so that it can be performed by any one of the methods of adjusting the energization time.