DE2460124C2 - Non-consumable electrode - Google Patents

Description

The present invention relates to a non-consumable Electrode for torches for arc welding or cutting, such as TIG welding torches, TIG cutting torch, plasma welding torch and / or plasma cutting torch.

When arc welding with a non-consumable electrode under shielding gas (TIG welding) As is well known, electrodes are used which consist predominantly of tungsten and apart from those in tungsten Usually occurring impurities usually one or more, the electron emission contain beneficial elements in low concentration. The best known are tungsten electrodes with Additions of thorium oxide in amounts of up to three percent by weight (DE-PS 8 05 899). Next to it are Tungsten electrodes for TIG welding become known (DE-PS 9 72 750), the additions of oxides Contains elements of strontium, yttrium, zirconium, niobium, molybdenum, cesium, barium, lanthanum and cerium. All The additives mentioned improve the emission properties of the tungsten electrodes and thus their usability in TIG welding. However, over time it has been found that generally with Thorium oxide compared to the other additives mentioned the two results can be achieved even if other additives may have special properties for very special applications.

For this reason, thoriated tungsten electrodes are almost always used today in TIG welding.

It is therefore not surprising that even in plasma cutting and welding, in addition to pure Tungsten electrodes also tungsten electrodes with the above-mentioned oxide additives, in particular thorium oxide additives be used.

However, it has been found in practice that also with the use of thoriated electrodes reduces the ignition capability of the Electrode is deteriorated. whereby in particular the contactless ignition of arcs between the Electrode and the workpiece or between two

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b0 electrodes are made more difficult and in some cases even impossible by means of ignition pulses or the like.

The invention is based on the object of a non-consumable electrode, in particular a tungsten electrode for electric arc welding or cutting, such as for TIG welding torches, TIG cutting torches, Plasma welding torch and / or plasma cutting torch to develop, their service life and Ignitability is increased compared to the known electrodes.

This object is achieved according to the invention in that the burner electrode predominantly Tungsten or a tungsten alloy and an additive of an oxide of the element aluminum contains.

The addition of aluminum oxide proposed according to the invention surprisingly results in a non-melting Achieved electrode, its service life and ignitability compared to the previous electrodes is much improved.

The welding electrodes according to the invention surprisingly have welding properties, some of which surpass those of the thoriated tungsten electrodes. Particularly noteworthy is first of all an improvement in ignitability, especially when igniting direct and alternating current arcs as well as when welding with alternating current, in which the arc is re-ignited at the beginning of each Half period is required is of great importance. The alternating current arc can also be used here a relatively low voltage can be safely maintained. It also increases the burn time of the arc in the half-cycle in which the electrode is the cathode is not insignificantly increased.

In comparison to pure tungsten electrodes, the electrodes according to the invention have the same dimensions just like the well-known thoriated electrodes, they have a higher load capacity. If this advantage is used in the used in the opposite sense, in comparison with pure tungsten electrodes, with the same current intensity thinner electrodes are used and, as a result, weld seams of smaller width are produced. Narrow weld seams in turn reduce the distortion of the welded workpiece.

Furthermore, the electrodes according to the invention show due to the relatively low temperature Electrode tip when welding low wear, which means that the need for a frequent sharpening of the electrode spii / c or the replacement of used electrodes is reduced. In addition, this also reduces the transition of tungsten into the melt and thus the Tungsten content of the workpiece reduced in the area of the weld seam.

In the case of the electrodes according to the invention, which are preferably designed as pointed rod electrodes , the aluminum addition is expediently uniform over the entire electrode material distributed. For certain special cases, however, it can also be advantageous to use the aluminum oxide inside the Electrode concentrate along its axis, creating an electrode in the manner of the known Soul electrodes are created.

In an advantageous further development of the invention, it is proposed that the electrode contain an aluminum oxide additive / of 0.1-8%, preferably 2-3%.

The electrode can be manufactured in the simplest possible manner, with the invention proposed for this purpose.

That is, first of all, aluminum oxide with tungsten metal powder or tungstic anhydride is mixed, this powder mixture is then pressed and then is sintered. The finished sintered metal can then be processed into electrodes in a known simple manner will.

Claims (5)

Patent claims: 1. Non-consumable electrode made of tungsten or a tungsten alloy and a metal oxide for torches for arc welding or cutting, such as for TIG welding torches, TIG cutting torches, Plasma welding torch and / or plasma cutting torch, characterized in that the metal oxide is aluminum oxide 2. An electrode according to claim 1, characterized characterized marked ^ul in that the electrode has an alumina addition of 0.1 -8%, preferably 2-3%. 3. Electrode according to claim 1 or 2, characterized in that the aluminum oxide is uniform is distributed in the electrode material. ' 4. Electrode according to claim 1 or 2, characterized in that the aluminum oxide is inside of the electrode is concentrated along the electrode axis. 5. Electrode according to one of claims 1 to 4, - ° characterized in that the electrode is designed as a pointed rod electrode.