GB2035173A

GB2035173A - Gas-shielded arc welding torch with fume extraction means

Info

Publication number: GB2035173A
Application number: GB7845668A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-11-22
Filing date: 1978-11-22
Publication date: 1980-06-18
Also published as: DK492379A; DE2947284A1

Abstract

An arc welding torch having a non-consumable electrode 10 and a surrounding tube 8 for supplying shielding gas such as argon or CO2 to the welding area is provided with a suction channel or tube 14 the front end 20 of which is cut obliquely (at 45 DEG maximum) and located adjacent the electrode tip for sucking away welding fumes without considerably reducing the desired effect of the shielding gas. For use in fillet welding where the end 20 may be partly blocked by a workpiece, the tube 14 may be provided additionally with suction holes 26. <IMAGE>

Description

SPECIFICATION Improvements relating to welding implements This invention relates to welding equipment and more particularly to the electrode hand piece of welding tools of the type having means for directing to the welding area a protective gas such as carbon dioxide or argon in order to prevent access of atmospheric air to the welding spot, such tools being used mainly for welding stainless steel.The electrode may be a fixed, non-coated and nonconsumed welding pin, the outer end of which is located in relatively short distance from the handle of the pistol tool, and the handle piece, apart from connector means for electric power supply to the welding pin, is provided with a connector tube for receiving a gas supply hose and an annular gas outlet nozzle portion surrounding the welding pin so as to provide for a flow of protective gas along the welding pin towards the outer end thereof.

Even with the use of non-coated electrodes the operation of these welding tools aimost inevitably gives rise to local air contamination originating partly from impurities on the surface of the workpieces and partly from the generation of ozone in or about the welding area, i.e. the contamination may often be difficult to realize visually. The operator normally holds his head rather close to the welding area, so in fact he will always, during the work, be exposed to a breathing air contamination, even if there is provided for general removal of the contaminated air by way of exhaust means mounted near the work place.

In connection with ordinary arc welding without supply of a protective gas it is at least principally very easy to provide for an efficient removal of the welding gasses by arranging a suction intake immediately next to the operative end of the electrode, whether or not the intake is associated with the welding tool itself, but for obvious reasons a similar measure in connection with tools of the protective gas type would be liable to entirely disturb the operation, because even the protective gas would be sucked away and the suction would give rise to a sweep of atmospheric air across the welding area.

Many experiments have been carried out with respect to the mounting of a suction pipe near the electrode end, even concentrically about the inert gas supply nozzle, but so far no really usable solution has come out of the experiments, at least not unless it is associated with a considerably increased consumption of the protective gas.

It is the purpose of this invention to provide a welding tool of the protective gas supply type or an accessory for such a tool, whereby the contaminated welding air may be locally removed without requiring any considerably increased supply of the protective gas, or any increased supply at all.

The invention is based on the finding that it is in fact possible to suck away the contaminated air by means of a suction pipe arranged on the tool with its outer end located reasonably close to the tip of the welding electrode, when the outer pipe end is cut in an oblique manner such that its edge converges forwardly towards the electrode tip. This is a surprising fact which may even be difficult to explain in detail, but the effect is remarkable, and when the position of the suction end of the pipe is properly adjusted relative to the electrode tip a fully efficient removal of the contaminated air is achievable without any need of increasing the supply of the protective gas. It seems to be a requirement, however, that the oblique pipe end is cut at a pronounced acute angle of max. 45".

In the following the invention is described in more detail with reference to the accompanying drawing, in which: Figure 1 is a perspective view of a welding tool according to the invention, and Figure 2 is a side view of the tool shown in operation.

The tool shown is basically an ordinary welding pistol having a handle piece 2 provided with a handle 4, a rear connection to a hose 6 for supplying an inert gas from a gas cylinder or other suitable source (not shown) and a connection to an electric conductor such as a cable located inside the hose 6 for supplying welding current to the tool, and, projecting from the front end of the handle piece 2, a nozzle pipe 8 surrounding a central welding electrode 10 and having an outer nozzle opening 12 through which the inert protective gas from the tube 6 is caused to sweep along the electrode 10 so as to displace the atmospheric air adjacent the tip of the electrode and thus enable the tool to carry out a welding without access of oxygen to the welding area.

This ordinary tool, however, is provided with a suction tube 14 mounted in a holder 16 in a position generally parallel with the gas tube 8, or slightly converging towards the free end thereof, the tube 14 being connected with a suction hose 18 leading to any suitable vacuum source such as a suction fan mounted adjacent the said gas cylinder. The outer end of the tube 14 is cut so as to present an end edge 20 which is pronounced oblique with respect to the axis of the tube, and which tapers generally towards the front end of the tool. The angle between the plane of the edge 20 and the axis of the tube 14 (or 8) is maximum 45", preferably some 20-40", and the "pointed" front end of the tube 14 is placed so as to be rather close to the front end of the tool, though still retracted somewhat therefrom in order not to interfere with the practical usability of the tool, e.g.

in a situation as shown in Figure 2. In this connection it will be appreciated that the end of the tube 14 is cut in such a manner that it disturbs the practical usability of the tool to a very small degree only, if any at all.

As mentioned, it is a surprising fact that with the use of the obliquely cut suction tube end 20 and - of course - with a suitably adjusted position thereof relative to the tip of the welding electrode 10 and with a suitably adjusted suction through the hose 18, it is possible to obtain an effective removal of the contaminated air adjacent the welding area without disturbing the flow of the protective gas against the same area.

However, in the situation shown in Figure 2, where the tool is used for welding. the inside of a corner portion between two orthogonal plate members 22 and 24, the free intake through the suction tube end 20 may be more or less blocked by the plate member 22, especially if the tool is tilted upwardly still more than shown in Figure 2. For enabling an effective air intake even in this situation the tube 14 is provided with holes 26 located in the wall of the tube adjacent the outer end thereof.Normally, if the tube end 20 is not blocked, the suction air flow will pass these holes, such that they do not give rise to any considerable reduction of the intake air flow through the end 20, but the holes 26 will become operative whenever the free end opening is more or less blocked, such that the contaminated air will be sucked away anyhow, without the protective gas as supplied through the nozzle 12 being sucked away from the tip of the electrode 10.

Preferably the tube holdeer 6 is provided so as to be adjustable along the tube 8, both lengthwise and circumferentially but of course it will be possible, within the scope of the invention, to provide for the tube 14to be held in a holding portion formed integrally with the handle piece 2, or in any other convenient manner.

In a preferred embodiment the angle of the end edge 20 is some 30 , and the suction air velocity is 40-50 m/sec.

Claims

1. Aweldingtool of the type comprising a hand piece having a welding electrode and a gas tube arranged for conducting a protective gas to the area adjacent the tip of the electrode, the welding electrode preferably being mounted coaxially inside the gas tube so as to project from the front end thereof, said hand piece further being provided with a suction tube for sucking away the welding gasses from the welding area and with connector means for connecting the said tubes and electrode with a protective gas source, a vacuum source and a welding current source, respectively, characterized in that the suction tube is constituted by a separate tube or a channel provided in the hand piece and extending substantially parallel with the electrode radially spaced therefrom and having its front end located near the tip of the electrode, said front end of the tube or channel being obliquely cut in such a manner that the front edge thereof is located in a plane which is pronounced outwardly and rearwardly inclined as seen from the electrode tip.

2. A welding tool according to claim 1, in which the suction tube extends slightly converging towards the tip of the electrode.

3. Awelding tool according to claim 1 or 2, in which the front end of the suction tube is cut at an angle of maximum 45" with the longitudinal direction of the electrode or the tube or channel itself, preferably at an angle of 20-40" therewith.

4. Awelding tool according to claim 1,2 or 3, in which the foremost pointed end of the suction tube or channel is located somewhat behind the front end of the gas supply tube.

5. A welding tool according to any of the preceding claims, in which the suction tube is length adjustably arranged on the hand piece.

6. A welding tool according to any of the preceding claims, in which the suction tube or channel is provided with side holes adjacent the outer end thereof.

7. A welding tool according to any of the preceding claims, in which the suction tube is mounted in an exterior holder secured to the outside of the protective gas supply tube as surrounding the welding electrode, so as to be adjustable in both the longitudinal and the circumferential direction of the gas supply tube.

8. A welding tool substantially as herein described with reference to and as shown in the accompanying drawings.