JPH03210969A - Hot wire tig welding equipment - Google Patents

Abstract

PURPOSE:To prevent a DC part of a TIG current from shunting and flowing into a heating power source by connecting a capacitor to one end of an output end of a pulse power source for heating a wire and connecting the other end of this capacitor to base metals and an electrode for heating. CONSTITUTION:Since the impedance of the capacitor 11 connected to the output side of the heating power source is in inverse proportion to frequency of the impressed voltage, it acts as very high impedance for a DC voltage component to cut off a current. While the impedance of a value calculated according to the frequency for AC or a pulse voltage component being maintained, the current is passed. Accordingly, while the DC current shunted to the heating power source 9 from a power source 1 for welding being cut off by the capacitor, the pulsative heating current outputted by the heating power source 9 can be carried smoothly. Consequently, a breakdown of a switching control element such as burning and triode AC switch of a transformer in the heating power source and other troubles of equipment can be obviated and the welding equipment with high reliability can be furnished.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hot wire type arc welding method that performs arc welding while supplying a current to a welding part and filler metal (hereinafter referred to as a wire) that has been preheated by resistance heating. This relates to TIG welding equipment.

Conventional technology TIG welding (inert-gas tungsten welding) involves welding by generating an arc between a non-consumable electrode such as a tungsten electrode rod and a base metal in an inert gas atmosphere.
-arc welding) has the advantage of providing high welding quality, but has the disadvantages of slow welding speed and low wire welding efficiency.

As a means of improving the welding speed and welding efficiency of this TIG welding method, a hot wire type TIG welding method is used in which the wire supplied to the welding part is heated in advance.

The principle will be explained with reference to FIG. In FIG. 2, l is a welding power source, and one with DC constant voltage characteristics is generally used. The positive output of the welding power source 1 is connected to the base metal 3, and the negative output is connected to the non-consumable electrode 2, and a TIG welding current is passed between the base metal and the non-consumable electrode to generate a TIG welding arc (hereinafter referred to as arc) 4. continue to occur. On the other hand, the wire 5 is supplied to the welding part within the arc by rotating a feeding roller 6 by a wire feeding electric motor (hereinafter referred to as electric motor) 7. A heating electrode 8 is provided near the tip of the wire 5. Reference numeral 9 denotes a wire heating pulse power source (hereinafter referred to as a heating power source), which preheats the wire 5 by passing a DC pulsed heating current between the heating electrode 8 and the base material 3. The heating power source 9 includes a transformer 9a, a rectifier 9b for rectifying the output of the transformer 9a, and a triac 9c connected to the input side of the transformer 9a to control switching of the input of the transformer 9a. Further, the rotational speed of the electric motor 7 is controlled by a motor control circuit 1o.

As mentioned above, the conventional welding device feeds the wire 5 heated by pulsed power to the welding part in the arc 4 using the electric motor 7 and the feeding roller 6, thereby improving the welding speed and efficiency of TTG welding. The reason why pulsed power is used as wire heating power is to minimize the time of magnetic blowing that occurs when electricity is applied to the wire, and to improve welding workability by securing a time when magnetic blowing does not occur. be.

The rotational speed of the electric motor 7 is set so that the tip of the wire 5 is supplied to the welding part while stably contacting the surface of the base material 3 in a solid state.

Problems to be Solved by the Invention However, the setting latitude for the rotational speed of the electric motor in the conventional example is extremely narrow, and a stable insertion state can be maintained due to changes in the wire insertion position due to variations in the arc length of the arc 4 or curling of the wire 5. It is often impossible to do so. That is, if the arc length becomes long or the tip of the wire enters the center of the arc 4 too much due to the winding of the wire, the wire becomes overly molten and moves to the base material 3 at the spherical part. The tip of the wire is separated from the base material 3. If the tip of the wire is separated from the base metal 3 in this way, the wire will melt irregularly, which is unfavorable from the viewpoint of welding quality, but this may also cause a failure of the heating power source 9. In other words, the part of the wire tip away from the base material 3 is floating in the plasma of the arc 4, and its potential is an intermediate potential between the base material 3, which is the anode, and the non-consumable electrode 2, which is the cathode. However, at this time, a part of the TIG welding current output from the welding power source 1 is shunted to the heating power source side.

Figure 3 explains the details of this situation.
When the wire tip 5a is in a solid state and in stable contact with the base metal 3, the TIG welding current 12 flowing out from the positive terminal 1a of the welding power source 1 flows to the base metal 3, the TIG arc 4, and the non-consumable electrode 2. However, when the wire tip 5a is floating in the plasma of the TIG arc 4, a part of the TIG welding current 12 returns to the negative terminal 1b of the welding power source 1.
3 is the base material 3, one end 9d of the output terminal in the heating power source 9, the secondary winding of the transformer 9a, the rectifier 9b, the other end 9e of the output terminal, and then the heating electrode 8, the wire tip 5a, the arc 4, The flow is divided through the non-consumable electrodes 2 in turn. Through such a path, the DC output current of the welding power source l is transferred to the transformer 9a in the heating power source 9.
However, at this time, one of the secondary windings of transformer 9a! When the values of the shunt current flowing through the transformer 4 and the shunt current flowing through the other shunt 15 are different, the transformer 9a is DC excited. When the amount of DC excitation exceeds the permissible limit amount, the transformer 9a enters a magnetic saturation state, and the primary current increases abnormally, and its value may become several times that of a normal state. Such an abnormal increase in the primary current of the transformer 9a often causes malfunctions of the heating power source, such as burnout of the transformer 9a in the heating power source 9 or destruction of the switching control triac 9C.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a hot wire type TIG welding device that is free from malfunctions such as burnout of transformers and destruction of switching control elements such as triacs.

Means for Solving the Problems In order to achieve the above object, the present invention provides a welding power source connected to a non-consumable electrode and a base material, a filler metal supplied by a wire feeding electric motor and a feeding roller, , is equipped with an electrode for heating the filler metal and a pulse power source for wire heating connected to the base material, a capacitor is connected to one output end of the pulse power source for wire heating, and the other end of the capacitor is connected to the base material. This was a hot wire type TIG welding device connected to a heating electrode.

Operation According to the configuration of the present invention, the impedance 2 of the capacitor connected to the output side of the heating power source is Z=1/2zfC(Ω)
...It can be expressed as (1). However, 1)
In the formula, f is the frequency of the voltage applied to the capacitor, C
is the capacitance of the capacitor, and π is the constant of pi. As shown by equation (1), a capacitor acts as a very large impedance for DC voltage components and blocks the current, but for AC or pulse voltage components, depending on the frequency f, (Equation 11) The current is allowed to pass while having an impedance of the value calculated by .Therefore, while the DC current that is shunted from the welding power source to the heating power source is blocked by the capacitor, the pulsed heating current output from the heating power source is allowed to flow smoothly. Now you can.

EXAMPLE Hereinafter, a hot wire type TIG welding apparatus which is an example of the present invention will be explained with reference to FIG.

1 is a welding power source, 2 is a non-consumable electrode, 3 is a base material, 4 is a T
The IG welding arc, 5 is a wire, 6 is a feeding roller, 7 is an electric motor, 8 is a heating electrode, and 9 is a heating power source, which are the same as in FIG. The heating power source 9 includes a transformer 9a and a rectifier 9.
b and a triac 9c.

The embodiment of the present invention differs from FIG. 2 in that a capacitor 11 is connected to one end of the output side of the heating power source (pulse power source) 9. Due to the action of this capacitor 11, the pulsed heating current output from the heating power source can be smoothly passed while blocking the direct current that is branched from the welding power source to the heating power source.

Effects of the Invention Since the present invention has the above-described configuration, it is possible to prevent the DC component of the TIG current from flowing in a shunted manner into the heating power supply, thereby preventing burnout of the transformer in the heating power supply and switching control of triacs, etc. Destruction of elements and other equipment failures can be eliminated, and a highly reliable hot wire TIG welding device can be provided.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a hot wire type TIG welding device according to the present invention, and Fig. 2 is a circuit diagram of a conventional hot wire type TIG welding device.
The circuit diagram of the welding device, FIG. 3, is an explanatory diagram showing the state of branching of TIG welding current. l...Welding power source 2...Non-consumable electrode 3...
Fil material 5...Filler material 6...Feeding roller 7
・・・Wai A・Feeding motor 8 ・・・Heating electrode 9
...Pulse power supply for wire heating II...Capacitor

Claims (1)

[Claims] A welding power supply connected to a non-consumable electrode and a base metal, a filler metal supplied by a wire feeding motor and a feeding roller, a heating electrode for this filler metal and a wire connected to the base metal. A hot wire type TIG welding device comprising: a heating pulse power source; a capacitor is connected to one output end of the wire heating pulse power source; and the other end of the capacitor is connected to a base material and a heating electrode. Device.