JPH0369629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding torch, and particularly to a welding torch effective for performing TIG (tungsten inert gas) arc welding.

FIG. 1 is a sectional view of a welding torch showing a typical structure of a water-cooled TIG welding torch that is conventionally and generally used.

A metal torch body 3 that is cooled by being in direct contact with the cooling water W flowing in and out through the pipes 1 and 2 at its upper part.
A cylindrical metal collet 4 with a slit formed at the tip divided into two to four parts is placed inside the collet 4, and a tungsten electrode 5 is placed inside the collet 4.
When the collet 4 is pressed below the torch body 3 by the torch cap 6, the tip of the collet 4 having the slit tends to deform inward because the surface formed at the bottom of the torch body 3 that receives the collet 4 is conical. As a result, the tungsten electrode 5 is tightened and fixed. Since the tungsten electrode 5 is closely fixed by the metal collet 4 and the torch body 3, which have good thermal conductivity, the heat generated in the tungsten electrode 5 during welding is transferred to the cooling water W through these.
Tungsten electrode 5 will be cooled. A water-cooled TIG welding torch generally has such an electrode holding mechanism, but in order to perform welding in an inert gas atmosphere, a heat-resistant gas nozzle 7 is attached surrounding the electrode holding mechanism, and argon gas, etc. is supplied from the gas pipe 8. The shielding gas G is caused to flow out from the nozzle 7.

Conventional water-cooled TIG welding torches have the above structure, so the outside diameter of the torch is as large as 20 mm or more. Therefore, if such a torch is to be applied to butt welding of thick plates, the groove width must be widened significantly just to insert the torch into the groove in order to generate an arc at the bottom of the deep groove. First, there are problems in that work efficiency is significantly reduced and reliability of the welded part is also reduced.

Therefore, a welding torch was devised for TIG welding thick plates with an extremely narrow gap of 5 mm width using a normal cold wire. (Japanese Patent Application No. 57-63241) FIGS. 2 and 3 are diagrams schematically explaining the torch fixing member 10, the electrode holding plate 15, and the cooling device interposed therebetween and forming part of the entire torch 9. It consists of water tubes 11 and 12 and gas tubes 13 and 14 for passing shield gas, and the torch 9 is thin and has a width very close to the diameter of the tungsten electrode 17. The electrode holding plate 15 is provided with a fastening hole 21 that is perpendicular to the axial direction of the electrode hole 20 and partially overlaps with this hole 20. The tungsten electrode 17 is fixed to the electrode holding plate 15 by inserting gold 22.
By adopting such a fixing method, it is possible to easily attach and detach the tungsten electrode 17 and to make the torch 9 extremely thin.

As a result, the welding torch 9 is configured to have a thickness of 4.2 mm, making it possible to easily perform welding within a narrow gap with a width of 5 mm. However, since the tungsten electrode 17 is strongly tightened and fixed by the clasp 22, it is not possible to adjust the protruding length of the tungsten electrode 17 by sliding the tungsten electrode 17 against the electrode holding plate 15 during welding. .

By the way, the usual addition of cold wire
TIG welding has a disadvantage in that the wire melting rate is slow, usually less than 10 g/min, and the work efficiency is significantly lower than other arc welding methods. Therefore, hot wire TIG welding was developed in which the additive wire is electrically heated to increase the melting rate to, for example, 40 g/min. In the hot wire TIG welding method, as shown in Figure 4,
Using an arc power source 23 and a wire heating power source 24, the base metal 27 is melted by an arc 26 generated by a tungsten electrode 25. The hot wire 28 that is heated by electricity is usually placed behind the arc 26, and the molten pool 29 is heated. By inserting the tip into the bead 30, electric heating and melting proceed, forming a good bead 30.
However, when the tip of the hot wire 28 comes out of the molten pool 29, the added metal that was melted by the electrical heating of the wire 28 is placed in a lump, whereas the bead was simply melted by the TIG arc without adding any wire. As a result, a bead that is not welded to the base metal 27 is formed, so a normal weld bead 30
becomes unable to form. Furthermore, if the tip of the hot wire 28 comes too close to the arc 26, the arc 26 will become unstable, which is not preferable. That is, it can be seen that in hot wire TIG welding, the distance l between the hot wire tip and the arc is a control factor that has a significant effect on the welding result.

Therefore, when attempting to perform hot wire TIG welding within a gap using a combination of the above-mentioned conventional techniques, as shown in FIG.
2 may be combined in such a way that they can move independently. However, when I actually tried to perform narrow welding with this configuration, the hot wire torch 3
2 and the arc torch 31, it is necessary to place them apart, and the hot wire 28 has to be fed diagonally from the side, which prevents the arc during welding. It has become extremely difficult to observe the situation on 26. Also welding torch 31
If the hot wire torch 32 is held by the welding torch 32 and the hot wire torch 32 is configured to move up and down in unison with the vertical movement of the welding torch 31, the distance l between the center of the tungsten electrode 25 and the tip of the hot wire 28 will be constant. However, since the angle θ between the hot wire 28 and the tungsten electrode 25 is large, even a small change in the welding arc length causes a large change in l, making it impractical for practical use. Therefore, in order to perform stable welding work on a multi-layered bead 30 with an uneven surface, the hot wire torch 32 and the arc torch 31 are constructed so that they can move virtually independently, and they are placed in a position that is difficult to see. Welding work was accompanied by great difficulty, as the position of the wire tip had to be constantly adjusted while somehow monitoring a certain arc.

An object of the present invention is to provide a TIG arc welding torch that can be made significantly thinner as a whole and that can easily weld using a hot wire even in a narrow and deep groove.

In short, this invention provides a hot wire type TIG arc welding torch used for narrow gap welding, which includes an electrode holding plate through which the electrode is inserted and a cooling water pipe is connected, a wire guide made of heat-resistant insulating material through which the hot wire is inserted, and an inert gas A series of supply pipes are placed in close contact with each other, and their outer surfaces are wrapped with heat-resistant insulating tape to form the torch body, and the electrode holding plate is provided with a recess containing a heat-resistant elastic body that presses the side of the electrode. It is characterized by connecting an adjustment rod.
It is a TIG arc welding torch.

Embodiments of the present invention will be described below with reference to the drawings.
In FIGS. 6 and 7, the first block 33
The insulating member 50 is held between the second block 34 and the torch fixing member is formed.The gas pipe 35, which is an inert gas passage member, is inserted through the first block 33, and the gas pipe 36 is inserted through the second block, and the upper part of each is inserted. Retained.
Reference numeral 37 denotes a cooling water pipe having two half-moon-shaped cross-sectional holes 37a and 37b, which are constructed in the form of a partition inside one pipe, and constitute the outward and return paths of the cooling water. An electrode holding plate (electrode holding member) 38 and a wire guide 39 are integrally provided at the tip of each of these tubes. 40 has a tungsten electrode 4 at its tip.
The torch fixing member 53 is tightened using the electrode adjustment rod 1.
It is screwed against. The tungsten electrode 41 is inserted into an electrode hole 42 provided in the electrode holding plate 38. Furthermore, the electrode holding plate 38 has electrode holes 4.
A press spring hole 43 is provided so as to be orthogonal to the axial direction of 2 and partially overlap with this hole 42, and a slit 44 is provided in a part of the hole 43, and a press spring 45 is embedded therein. A projection 46 is provided at the center of the pressing spring 45.
, thereby effectively connecting the tungsten electrode 4
1 is pressed against the electrode holding plate 38 from the side. 47 is a contact tube through which the hot wire 48 is passed, and a contact chip 49 is attached to the tip end of the contact tube.
are screwed together. Torch fixing member 33
is connected to a TIG arc power source (not shown), and the torch fixing member 34 is connected to a hot wire power source (not shown), and an insulating member 50 made of Bakelite and a wire guide 39 made of ceramic are used to connect the torch fixing member 34 to a hot wire power source (not shown). isolated. The torch main body 51 is formed in this way. A cooling water pipe 37 and a gas pipe 35 are connected to the electrode holding plate 38.
The tungsten electrode 41 is brought into close contact with the electrode holding plate 38 by the pressing spring 45, so that the tungsten electrode 41 is not only cooled but also energized. ing. The wire 52 is connected to the torch fixing member 34,
Contact tube 47, contact tip 49
The straight wire 52 is fed into the molten pool through the wire guide 39.
Since the wire 52 is bent in such a way as to change its traveling direction by the wire 9, the wire 52 is strongly pressed against the inner wall surface of the contact chip 49, where a sufficient and stable contact current is applied, and the wire 52 is heated and sent out as a hot wire 48. It will be done. When the contact tip 49 becomes worn out, the structure is such that a deep hole is made in the torch fixing member 34 and the contact tube 47 is inserted, so the contact tube 47 can be moved to the torch fixing member 34 side and the contact tip 49 can be easily removed. It can be replaced with . When actually performing arc welding within a narrow gap,
It is necessary to prevent a short circuit between the torch body 51 and the side wall of the groove, and for this purpose, a heat-resistant and insulating coating (not shown), such as an adhesive glass tape, is formed on the outer periphery of the torch body 51.

The inventors prototyped a torch with the above-mentioned configuration and obtained the following results.

That is, the diameter is 2.4 mm and the tungsten electrode 41
is fastened with a fastening hole 53 provided in a tapered manner at the tip of a steel electrode adjustment rod 40 with an outer diameter of 4 mm, and an inner diameter of 2.5 mm provided in an electrode holding plate 38 made of a copper plate with a thickness of 4 mm. The planar part of the tungsten having a semicircular cross section is placed through the electrode hole 42 and then inserted into the protrusion 46.
A pressing spring 45 made of a heat-resistant spring material attached to the holder is used to press from the lateral direction. The wire guide 39 is made of alumina, and the gas pipes 35 and 36 are made by crushing copper pipes with an outer diameter of 6 mm and a thickness of 0.5 mm to have an oval cross section with a minor diameter of 4 mm.
They were wrapped together with adhesive glass tape, and the final product was approximately 4.5 mm thick, 35 mm wide, and approximately 35 mm long.
This is a hot wire TIG welding torch for 120mm narrow gap.

Using this torch, the average arc current was measured for a carbon steel joint consisting of an I-type narrow groove with a width of 7 mm and a thickness of 70 mm.
Stable and good welding was possible under the conditions of 240A, welding speed of 150mm/min, and hot wire melting rate of 35g/min. During this welding, the electrode adjustment rod 4
0 and placed the tip of the hot wire approximately 3 mm from the center of the tungsten electrode. However, when this distance was changed,
It was possible to adjust freely from mm to 6 mm. Note that welding is performed in an argon gas atmosphere, and in order to perform shielding more effectively, the torch 51 is
In addition to shielding with gas from the tip, we adopted a so-called double shielding method in which a shield box is also placed on the surface of the base material for sealing.

Although narrow gap hot wire TIG welding has been described above, the present invention is not limited to narrow gap welding.

FIG. 8 shows a general-purpose torch having a circular gas nozzle 54 to which a heat-resistant elastic material structure for pressing an electrode according to the present invention is applied. 55 is water cooling pipe 5
6 and 57 are connected and water-cooled, and an electrode hole 58 for inserting a tungsten electrode is provided in the center, and the heat-resistant rubber 61 is held between horizontally holding plates 59 and 60. The tungsten electrode 63 is pressed against the holding member 55 with an appropriate force by the holding screw 62 via the tungsten electrode 63, and the tungsten electrode 63 is energized and cooled. On the other hand, the tungsten electrode 63
4, but the collet 64
Since there is a screw connection between the electrode 63 and the torch body 65, the electrode 63 can be slid up and down by rotating the collet 64. The shielding gas passes from the gas pipe 66 through the hole provided in the electrode holding material 55, passes through the gas lens 67, and is made into a laminar flow to shield the arc. On the other hand, the hot wire 68 is guided to the tip of the electrode through a contact tube 69 attached to the torch body 65. Because of this structure, the collet 64 is
The tungsten electrode can be moved up and down by turning the tungsten electrode, thereby easily adjusting the distance between the tip of the hot wire 68 and the tungsten electrode.

By carrying out this invention, the tungsten electrode and wire can be inserted into the groove with an integrated torch, so welding work can be easily performed even in narrow and deep grooves, and the reliability of the welded part is improved.

Additionally, even if the tungsten electrode wears out during welding, it can be continuously replenished, making it possible to continue circumferential welding for long periods of time without cutting the arc.

Furthermore, in hot wire TIG welding, adjusting the position where the hot wire is inserted into the molten pool is essential for stable welding work, but by sliding the tungsten electrode against the electrode holder, the torch The structure has become more compact, and the handling and operation of the torch has become much easier.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a conventional water-cooled TIG welding torch, Fig. 2 is a structural diagram showing an example of a conventional TIG torch for narrow gap welding, Fig. 3 is a side view of the same torch, and Fig. 4 is a cross-sectional view showing an example of a conventional water-cooled TIG welding torch. Figure 5 is an explanatory diagram of the conventional hot wire TIG welding method, Figure 5 is a diagram illustrating the situation of TIG welding in a narrow gap using the torch of Figure 2, and Figure 6 is an illustration of the welding torch according to the present invention. 7 is a side view of the same torch, FIG. 8 is a sectional view of a round torch in which the structure of the present invention in which the electrode is pressed by a heat-resistant elastic body is applied, and FIG. 9 is a side view of the torch. - It is a sectional view taken along the A line. 40... Electrode adjustment rod, 41, 63... Tungsten electrode, 45... Push button, 51... Torch body.

Claims (1)

[Claims] 1 In a hot wire type TIG arc welding torch used for narrow gap welding, there is an electrode holding plate through which the electrode is inserted and a cooling water pipe is connected, a wire guide made of heat-resistant insulating material through which the hot wire is inserted, and an inert gas supply pipe. The electrode holding plate is provided with a recess containing a heat-resistant elastic body that presses the side of the electrode, and the electrode and the electrode adjustment are placed in close contact with each other in series, and their outer surfaces are wrapped with heat-resistant insulating tape to form the torch body. A TIG arc welding torch characterized by connecting rods and forming a thin layer.