JPH0536152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a TIG arc welding torch, and particularly to a welding torch for hot wire TIG.

(Prior art) TIG (tungsten inert gas) welding, which performs welding by generating an arc between a non-consumable tungsten electrode and a base metal in an inert gas atmosphere such as argon, is more effective than other welding methods. Although the welding efficiency is inferior, the soundness of the welded part is excellent, and it is often used for welding alloy steels such as stainless steel and for welding in places where reliability is required. In TIG welding, unlike so-called consumable electrode welding such as covered arc welding and MAG welding, in which the electrode itself is melted by an arc to form weld metal, TIG welding uses a non-consumable tungsten as an electrode, so additive wire is used. It is necessary to feed it near the arc and melt it to form molten metal. For feeding the additive wire
There is a method of directly feeding a 2.4 mm diameter wire by hand, and a method of automatically feeding a 1.0 mm diameter wire wound on a reel using a roller through a wire guide fixed to a torch, but this method improves welding efficiency. An automatic feeding method is suitable for this purpose. Various types of welding of thin plates have already been put into practical use depending on the application. FIG. 3 shows an example of a TIG arc welding torch that integrates a conventional additive wire automatic feeding mechanism and a tungsten electrode holding mechanism.
The torch fixing member 1 is provided with a shield gas nozzle 2 and a tungsten electrode 7, and is also provided with a contact tube 11 integrally fixed to the torch fixing member 1 and an additive wire 25 passing therethrough. In addition, in the figure, 8 is a cooling water pipe, 18 is a screw for adjusting the angle of the additive wire, 19 is a gas pipe, 2
0 is a screw for adjusting the added wire back and forth.

However, with conventional welding torches, the width of the shield gas nozzle 2 alone is 20 mm or more, and when applying it to butt welding of thick plates, it is necessary to insert the torch into the groove. The development width had to be significantly widened to 20mm, which caused a problem in that welding work efficiency was significantly reduced.

In order to solve these problems, it is necessary not only to make the welding torch thinner so that it can be inserted into narrow grooves, but also to take measures to make it easier to observe the arc and molten pool inside the groove. It is. In addition, in order to improve the welding rate when welding thick plates, we use hot wire TIG, which heats the additive wire by passing a current through it.
A welding method is used, and measures are required to electrically insulate the hot wire guide mechanism and tungsten electrode holding mechanism. In hot wire TIG welding, the hot wire is usually placed behind the arc, its tip inserted into the molten pool, and current is passed between it and the base metal. However, if the tip of the hot wire moves away from the arc and comes out of the molten pool,
Since the current flowing through the wire is reduced and the wire is not effectively heated and melted, a normal bead cannot be formed. Furthermore, if the tip of the hot wire gets too close to the arc, the arc becomes unstable, making it difficult to perform good welding. In other words, in hot wire TIG welding, the distance between the hot wire tip and the arc, or tungsten electrode, is a controlling factor that has a significant effect on the welding result, and measures to control the distance between the hot wire tip and the tungsten electrode within a narrow groove are also required. is necessary.

To solve these problems, a welding torch for welding thick plates with a narrow gap of 10 mm or less in width was devised (Japanese Patent Application No. 1771213/1982).

FIG. 4 is a side view of a conventional narrow gap automatic TIG welding torch, and FIG. 4A is a front view of the same as viewed from A. In the figure, shield gas nozzles 2 and 3 are inserted through the torch fixing member 1, and a tungsten electrode holding plate 4 is fixed to the lower part of the gas nozzle 3. On the other hand, a hot wire is passed through the gas nozzle 2 in its length direction. A contact tube 11 is fixed. Further, at the lower end of the contact tube 11, a ceramic hot wire guide 12 is fixed between the electrode holding plate 4 and the gas nozzle 2. The tungsten electrode 7 is inserted into the electrode hole 5 provided in the electrode holding plate 4, and is tightly attached to the electrode holding plate 4 by a pressing spring 22 and a protrusion 23, which are also placed in the center of the electrode holding plate 4. Furthermore, the tungsten electrode 7 is fastened to an electrode adjustment screw 21 which is threaded and held in the torch fixing member 1. With this structure, the tungsten electrode 7 can be moved vertically by the adjustment screw 21. The hot wire 13 includes a wire guide nozzle 10 and a contact tube 11.
The wire is then bent and fed to the tungsten electrode 7 side via the wire guide 12. The angle θ is
The temperature is between 50 and 70 degrees. For this reason, the tungsten electrode 7,
That is, the distance between the position of the arc and the tip of the hot wire 13 can be adjusted by moving the tungsten electrode 7 in the vertical direction. Note that the holding mechanism for the tungsten electrode 7 and the guiding mechanism for the hot wire 13 are electrically isolated by an insulator 9 such as Bakelite and a wire guide 12 made of ceramic. Furthermore, as described above, since the feeding angle θ of the hot wire is large, it is easy to observe the molten pool from behind the welding.

On the other hand, in automatic TIG welding, a method is adopted in which the position of the welding torch is controlled to keep the arc length approximately constant so that stable welding can be performed. That is, an arc voltage that uniquely determines the arc length is detected, and a servo motor is used to move the welding torch in the vertical direction. For this reason, it has been found that when the arc length is varied by moving the tungsten electrode 7 up and down, the arc voltage also changes rapidly, sometimes causing an error in the arc length control mechanism. In addition, even when arc length constant control is not performed, the length of the molten pool depends on the current
There is some variation depending on influencing factors such as voltage and groove width, and it may be difficult to control the distance between the tungsten electrode 7 and the tip of the hot wire 13 only by moving the tungsten electrode 7 up and down.

(Problems to be Solved by the Invention) An object of the present invention is to freely adjust the distance between the tungsten electrode and the tip of the hot wire even in a deep groove, and to perform stable welding while observing the molten pool. Our goal is to provide a thin TIG arc welding torch that can be used.

(Means for Solving the Problems) In short, the present invention provides a torch in which a tungsten electrode holding mechanism and a hot wire guide mechanism are integrated, in which a hot wire guide nozzle tilted toward the tungsten electrode is slid in the vertical direction. This allows the distance between the tungsten electrode and the tip of the hot wire to be adjusted. That is, the present invention provides a TIG arc welding torch that integrally incorporates a holding mechanism for a tungsten electrode that forms an arc and a guide mechanism for a hot wire, in which the hot wire guide mechanism includes a guide nozzle that guides the hot wire, and a guide nozzle that guides the hot wire. A wire guide that bends and feeds the hot wire coming out from the lower end toward the tungsten electrode, and a tip of the hot wire that is provided at the upper part of the guide nozzle and that is moved up and down during welding to make contact with the molten pool. The method is characterized by comprising means for adjusting the distance between the center axes of the tungsten electrodes.

In the present invention, the wire guide that bends and feeds the hot wire coming out of the contact tube toward the tungsten electrode is made of ceramics, and the wire guide is moved up and down along a hot wire guide mechanism fixed to a welding torch such as the contact tube. It is preferable to be able to move.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 1A are a side view and a front view showing one embodiment of the TIG arc welding torch of the present invention. In the figure, a wire guide nozzle 10 and a hot wire guide 12 are fixed to a torch fixing member 1 via a shield gas nozzle 3, a cooling pipe 8, and an insulating member 9. The part that fixes the tungsten electrode 7 holding mechanism part consists of the gas nozzle 3, the cooling water pipe 8, and the electrode holding plate 4 fixed to their lower part, and the part that fixes the hot wire guide mechanism part consists of the gas nozzle 2 and the contact tube. Consists of 11. These parts are electrically isolated by an insulating member 9 made of Bakelite or the like. Electrode holding plate 4 has electrode holes 5
A tungsten electrode 7 is inserted thereinto, and is fixed to the electrode holding plate 4 by an electrode fixing screw 6. This tungsten electrode 7 is not shown.
It is connected to a TIG arc power source via a torch fixing member 1, a gas nozzle 3, and a cooling water pipe 8. The contact tube 11 into which the hot wire 13 is fed is fixed to the gas nozzle 2 and further fixed to the electrode holding plate 4 by an insulating member 24 made of ceramic. The contact tube 11 is connected to a hot wire power source (not shown),
Electricity is applied to the hot wire 13 through this contact tube 11. This hot wire guide mechanism is electrically isolated from the tungsten electrode holding mechanism by insulating members 9 and 24. Gas nozzle 2 or gas nozzle 2 and contact tube 1
1 is inserted and supported within a thin ceramic tube 12, and a hole is provided below it that is inclined so that the hot wire 13 can be fed to the tungsten electrode 7 side. The hot wire guide 12
It has the cross-sectional shape shown in the figure, is fastened to the wire guide holding jig 14, and is attached to the wire guide nozzle 10.
The wire guide 12 can be slid in the vertical direction along the gas nozzle 2 and the contact tube 11 by means of a screw thread 15 and a vertical adjustment screw 16.

Since the TIG arc welding torch according to the present invention has the above configuration, the wire guide 12 can be easily moved up and down using the adjustment screw 16.
The distance between the tip of the hot wire 13 and the tungsten electrode 7 can be adjusted as desired. Furthermore, as mentioned above, the arc length is controlled by the servomotor over the entire welding torch by detecting the arc voltage, but in the present invention, the arc length is controlled completely independently of the vertical movement of the welding torch. The addition position of the hot wire 13 to the molten pool can be adjusted.

Furthermore, in hot TIG welding, unless the protruding length of the wire is kept constant, the heating of the wire will not be constant, but according to the welding torch of the present invention, the entire hot wire guide mechanism can be moved up and down. Unlike, since the distance from the lower end of the contact tube 11 to the molten pool does not change, stable welding can be performed. Also,
Since the wire guide 12 made of high melting point ceramic is present between the contact tube 11 and the molten pool, the contact tube hole is not clogged by spatter or the like.

The inclination angle θ of the hole provided in the wire guide 12 is 70
We made a prototype welding torch with a high temperature and measured the change in the distance between the tungsten electrode 7 and the tip of the hot wire 13 by moving the wire guide up and down, and found that it could be freely adjusted from 1 mm to 7 mm. In actual welding, it was found that a distance of 3 mm to 5 mm is appropriate and can be put to practical use. Also, the tungsten electrode 7 will be somewhat worn out during welding, but if you take the amount of wear into consideration before welding and let it stick out long from the electrode holding plate 4, the tip of the hot wire 13 can be adjusted during welding, so you can cut the arc and re-adjust it. There is no need for adjustment, and welding can be performed continuously for a long time.

Although narrow gap hot wire TIG welding has been described above, the present invention is not limited to narrow gap welding, and can have similar effects even when applied to a normal TIG arc welding torch.

(Effects of the Invention) According to the present invention, a thin welding torch that can be fully inserted into a narrow gap is provided.
m, the body of a steel pressure vessel with a plate thickness of 150 mm and a diameter of 500 mm.
Narrow gap welding of stainless steel piping with a plate thickness of 100 mm using hot wire TIG is also possible. For this reason, the scope of application of the narrow gap hot wire TIG welding method, which produces high-efficiency and high-quality welds, has been expanded, and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a TIG arc welding torch according to the present invention, FIG. 1A is a front view as viewed from A in FIG. 1, and FIGS. 2 and 2A are shown in FIG. 1. Figure 3 is a structural diagram of a conventional welding torch for thin plates, and Figure 4 is a side view of a conventional welding torch for narrow grooves. Figure 4A is the figure A of Figure 4.
FIG. 3 is a front view in the viewing direction. 1... Torch fixing member, 2, 3... Shield gas nozzle, 4... Electrode holding plate, 5... Electrode hole, 6... Electrode fixing screw, 7... Tungsten electrode, 8... Cooling water pipe, 9... Insulating member, 10... For wire Guide nozzle, 11... contact tube, 12... hot wire guide, 13... hot wire, 14... hot wire guide holding member, 15... vertical adjustment screw.

Claims (1)

[Claims] 1. In a TIG arc welding torch that integrates a tungsten electrode holding mechanism that forms an arc and a hot wire guide mechanism, the hot wire guide mechanism includes a guide nozzle that guides the hot wire, and a hot wire that comes out from the lower end of the guide nozzle. a wire guide that bends and feeds the wire toward the tungsten electrode; and a wire guide provided at the top of the guide nozzle that moves the wire guide up and down during welding to connect the tip of the hot wire and the center of the tungsten electrode, which is in contact with the molten pool. A TIG arc welding torch, characterized in that it has means for adjusting the distance between the axes.