JPS6247630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma torch,
It is particularly suitable for welding narrow gaps.

As a conventional plasma torch for welding a narrow gap, there is one shown in FIG. Fig. a is a longitudinal cross-sectional view of the torch, and Fig. b is a cross-sectional view taken along the line A-A' in Fig. A. 1 is an electrode, 2 is a nozzle provided with a plasma gas passage 3 formed therein, and 4 is a nozzle inside the nozzle 2. A cooling water passage 5 provided in the cooling water passage 5 is a shield cap provided to form a shield gas passage 6. The tip of the nozzle 2 is narrow as shown in Figure b, and has a shape suitable for insertion into a narrow gap. However, with this configuration, because the cooling water is not circulated to the tip of the nozzle 2, which is most likely to be overheated by arc heat, a large current cannot be passed, and deep penetration with a uniform underwave cannot be achieved. Welding is difficult.

In addition, in the shield gas passage 6 through which shield gas flows to protect the welding part from the atmosphere, the shield cap 5 is located on the surface of the welding materials 7, 7', so that a sufficient shielding effect cannot be obtained. There are drawbacks. In particular, when the welding materials 7, 7' are thick, the shielding effect is significantly inferior. In order to create a plasma torch that can be inserted into a groove, it is necessary to ensure the plasma arc current necessary to melt the weld joint and achieve deep penetration, and also to create a structure that has a good shielding effect.

On the other hand, as an alternative welding torch, there is, for example, Japanese Utility Model Publication No. 52-50203. this is,
The flat torch body is water-cooled, but cooling water holes are provided in a U-shape on both outsides of the torch body, and the structure is such that the cooling water does not flow around the tungsten electrode insertion part in the center. .

Since the tungsten electrode itself is checked by a collector chuck installed at the tip of the torch, cooling is insufficient and a large arc current cannot flow through it.

Unlike plasma arc, which has a high current density because the arc is constricted by a nozzle, the TIG arc uses no nozzle, so the current density is low, and the disadvantage is that the welding penetration is shallow and the welding speed is slow.

The present invention has been made in view of the above, and provides a thin plasma torch that can be inserted into a groove and efficiently perform welding while maintaining the current capacity necessary for welding and sufficient shielding effect. The purpose is to

The present invention provides a plasma torch in which the nozzle is water-cooled, in which a nozzle 12 having a nozzle hole is provided at the tip of the torch, the periphery of the nozzle 12 is covered with a shield cap 16, and a space 36 at the tip of the nozzle 12 is provided.
The electrode 8 is built in with the nozzle hole 20 facing toward the
Two plasma gas passages 19 are formed in the nozzle 12 so as to be coaxial with the electrode 8 and the electrode holder 9, and two independent plasma gas passages 19 are formed on both sides of the electrode 8 and electrode holder 9. The gas passage 19 communicates with the nozzle hole 20 through the space 36, and also communicates with the nozzle hole 20 through the space 36.
2, a cooling water passage 21 is formed around the electrode 8 and electrode holder 9 and outside each of the plasma gas passages 19, and the cooling water passages 21 on both sides are provided around the nozzle hole 20. A shield gas passage 18 is formed between the nozzle hole 12 and the shield gap 16. Embodiments of the present invention will be described below with reference to the drawings.

Fig. 2a is a longitudinal sectional view of a thin plasma torch according to an embodiment of the present invention, and Fig. 2b is a longitudinal sectional view taken along line A-A' in Fig. 2, showing the tip of the torch being inserted into the groove. It is now possible to do so. In the figure, an electrode (tungsten) 8 is fixed to an electrode holder 9. The inner tube 10 is inserted into the electrode holder 9 to form a cooling water passage 11, and by flowing cooling water 29, a high current plasma arc can be generated in the electrode 8. The flat nozzle 12 has a flat cross section and is fixed to the torch body 13 by a fastening ring 14. The insulating sleeve 15 is located between the electrode holder 9 and the flat nozzle 12 to insulate them.
The shield cap 16 is attached to the torch body 13 by screw 1.
A shield gas passage 18 is formed between the flat nozzle 12 and the shield gas passage 16, and a shield gas 28 flows to the tip of the torch. The plasma gas passage 19 is provided on the inner surface in the longitudinal direction of the flat nozzle into which the electrode 8 is inserted, and communicates with the nozzle hole 20 via the space 36, through which the plasma gas 27 flows.

Similarly, the cooling water passage 21 is provided on both sides of the plasma gas passage 19 further outward with the electrode 8 as the center, and communicates with a communication passage 22 provided around the nozzle hole 20 at the tip of the nozzle. 29 flows like an arrow.

O-rings 24, 25, and 26 each have a sealing function.

FIG. 3 is a sectional view of the flat nozzle, FIG. 3B is a cross-sectional view taken along the line A-A' in FIG. A, and FIG. As described above, the plasma gas passage 19 and the cooling water passage 21 are provided on both sides of the flat nozzle in the longitudinal direction with the electrode (not shown) in the center. Furthermore, a communication passage 22 is also provided so as to surround the nozzle hole 20 .

With this configuration, the torch can be made thin enough to be inserted into the groove, and since the nozzle tip, which tends to be overheated by arc heat, is water-cooled, it can withstand high current loads.

Figure 4 shows another embodiment of the flat plasma torch.
Figure a is a longitudinal cross-sectional view, and figure b is a cross-sectional view taken along line A-A' in figure a. In this embodiment, only the tip of the nozzle is replaceable, and the shielding gas passage is formed by providing a groove on the outer surface of the nozzle, thereby making the torch narrower and having a flat structure.

In the figure, a flat nozzle tip 30 having the same cross section is fixed to the tip of the flat nozzle 12 with a screw 31 so as to match the flat nozzle 12. Notches are formed at the four corners of the flat nozzle 19 and the chip 30, and a shield gas passage 32 is formed by the shield cap 16. Furthermore, a groove is provided on the side surface to form a shield gas passage 33.

With such a configuration, even if the chip 30 becomes molten due to heat during use, it can be easily replaced and can be used economically. Further, since the shield cap 16 is brought into close contact with the outer surface of the water-cooled nozzle, cooling can be improved.

FIG. 5 shows still another embodiment of a flat plasma torch, in which figure a is a longitudinal sectional view and figure b is a bottom view of only the nozzle portion of figure a.

In this embodiment, a communication passage is effectively provided around the nozzle hole in order to further improve the cooling effect of the chip.

In the figure, a communication passage 35 is provided in the tip 34 of the flat nozzle over the entire circumference of the nozzle hole 20. Groove processing is applied to the two parts,
It can be easily manufactured by soldering afterwards.

Since the communication passage 35 extends around the entire circumference of the nozzle hole 20, the cooling effect is high, and therefore a large capacity torch can be obtained with a torch of the same size.

Fig. 6 shows an example of narrow gap welding using the torch of the present invention as described above, and Fig. a shows the dimensions (mm) of the welding material, and the root face of the weld is 7.
mm. Figure b shows the cross-sectional structure of the first layer weld when performed on stainless steel (SuS304). The specific conditions for implementation are welding speed: 200 mm/mm, plasma current: 280 A, plasma flow rate: Ar3/min, and shielding gas flow rate: Ar + 5% H ₂ 20/min.

As can be seen from the figure, a uniform welded part with back waves was obtained, and the welded appearance was also extremely good. The plate shown in the figure has a thickness of 50 mm, but by extending the length of the flat nozzle, the groove depth can be increased to 150 mm.
Since the current capacity necessary for welding and sufficient shielding effect are maintained even when the welding temperature is exceeded, the torch can be inserted into the groove and welding can be performed satisfactorily.

Furthermore, not only flat plate welding but also plasma welding after keyhole welding with a back wave can be performed by feeding the wire.

As explained above, according to the thin plasma torch of the present invention, it becomes possible to easily perform groove welding of thick plates, which could not be welded with conventional plasma torches having a large diameter, and welding efficiency is greatly improved. do.
By extending the length of the flat nozzle, it can be used for keyhole welding of narrow grooves with a groove depth exceeding 150mm, as well as welding of shallow grooves like conventional torches.
Multilayer welding after keyhole welding with back waves can also be performed while feeding the wire. This method can also be applied to fillet welding.

It goes without saying that this torch can be used for cutting, thermal spraying, etc.

[Brief explanation of the drawing]

Figure 1a is a vertical cross-sectional view of a conventional plasma torch for narrow gap welding, and figure b is the line A--A of figure a.
A cross-sectional view taken along line A', FIG. 2a is a vertical cross-sectional view of the thin plasma torch of the present invention, and FIG.
A vertical cross-sectional view along line A', Figure 3a is a vertical cross-sectional view of the flat nozzle, figure b is a cross-sectional view along line A-A' in figure a, and figure c is a cross-sectional view along line B-B'. Figures 4 and 4 show other embodiments of the thin plasma torch of the present invention, in which figure a is a longitudinal sectional view, figure b is a cross-sectional view taken along line A-A' in figure a, and figure 5 is another embodiment of the thin plasma torch of the present invention. FIG. 6A is a longitudinal sectional view, FIG. 6B is a bottom view of only the flat nozzle portion, FIG. 6A is an example of implementation using the torch of the present invention, and FIG. 8... Electrode, 9... Electrode holder, 10... Inner tube, 12... Flat nozzle, 13... Torch body, 14... Fastening ring, 15... Insulating ring, 16... Shield cap, 18, 32,
33... Shield gas passage, 19, 23... Plasma gas passage, 20... Nozzle hole, 21... Cooling water passage, 22, 35... Communication passage, 30, 34...
...Flat nozzle tip.

Claims (1)

[Claims] 1. A nozzle having a nozzle hole is provided at the tip of the torch, and the periphery of the nozzle is covered with a shield cap,
An electrode is built into the space at the tip of the nozzle facing the nozzle hole, an electrode holder for fixing the electrode is built into the nozzle so as to be coaxial with the electrode, and the electrode and the electrode are also built into the nozzle so as to be located coaxially with the electrode. Two mutually independent plasma gas passages are formed on both sides of the holder, and each plasma gas passage communicates with the nozzle hole through the space,
Further, a cooling water passage is similarly formed in the nozzle around the electrode and the electrode holder and outside each of the plasma gas passages, and the cooling water passages on both sides are communicated through a communication passage provided around the nozzle hole. . A plasma torch, characterized in that a shielding gas passage is formed between the nozzle and the shielding cap. 2. The plasma torch according to claim 1, wherein the shield gas passage is formed by covering a groove formed on a side surface of the nozzle with the shield cap. 3. The plasma torch according to claim 1, characterized in that a replaceable nozzle tip is provided at the tip of the nozzle.