SE440617B - CONTACT TRACTOR AT A WELDING BURN NOZZLE FOR A MELTABLE THREAD ELECTRODE - Google Patents

Description

8002917-6 In fully automatic welding operations, in which the movement of the welding torch is controlled by manipulators or robots, the electrode emerging from the contact nozzle must always have the same direction towards the welding site, as a special control of the free electrode direction would significantly complicate the automatic welding operation. It is therefore desirable that the contact nozzle has a straight guide channel. However, this also increases the risk of poor contact between the electrode and the contact nozzle, which ultimately leads to substandard welding results. This problem becomes noticeable when welding with electrodes, the diameter of which is less than 2.0 mm, and is particularly striking when the diameter of the electrodes is less than 1.3 mm.

The object of the present invention is to provide a contact tube which constitutes such a reliable contact means and directing means for the electrode that the current transfer to the electrode is ensured in the contact nozzle of the contact tube and the feed direction of the electrode does not change once it has left the contact nozzle. The invention is characterized in that the guide tube on its inside is provided with at least one projection, which causes an eccentric constriction in the guide tube. For guiding the electrode to the part of the inner wall of the guide tube opposite the projection.

By means of the constriction created by the projection, the electrode is forced to follow an eccentric path on a part of its feed through the guide tube. In the rest of the guide tube, the position of the electrode is rather indeterminate, since the inner diameter of the guide tube is larger than that of the contact nozzle and consequently substantially larger than the diameter of the electrode, which in itself is desirable to reduce the movement resistance of the electrode as far as possible. From a wire magazine to the welding point. When the electrode is passed from the guide tube into the narrower guide channel of the contact nozzle, it is forced to a change of direction and thus a slight bending, which is then completely equalized in the guide channel of the contact nozzle. When equalizing this bend, the required contact pressure between the electrode and the contact nozzle is achieved. For electrodes with a diameter of 1.6 and 2.0 mm, the bend to which the electrode is subjected during the passage of one of the constrictions and when it is inserted into the contact nozzle is fully sufficient for a good contact.

For smaller diameter electrodes, however, it is advantageous to allow them to pass two constrictions in the guide tube. According to a preferred embodiment of the invention, the guide tube is therefore provided with two projections arranged one behind the other. It is particularly advantageous in this case that these projections are arranged diametrically in order to effectively bring about the desired changes of direction in the feed path of the electrode through the guide tube.

The invention will now be described in more detail in connection with the accompanying drawing, which shows an embodiment of the same.

Fig. 1 shows a section through a burner nozzle. Fig. 2 is a section along II-II and Fig. 3 a section along III-III in Fig. 1.

An electrode conductor hose 1 of a welding hose not shown here is inserted into a connecting pipe 2, through which the welding current is led from the said welding hose to a contact pipe consisting of a guide pipe 3 and a contact nozzle 4 screwed into it.

The connecting pipe 2 is provided on its outside with longitudinal channels 5 for supply and removal of cooling water for the burner nozzle. These channels 5 communicate with each other at the front end of the coupling tube 2 through an annular channel 6.

The connecting pipe 2 is surrounded by a concentric outer pipe 7, which has a longitudinal shielding gas duct 8, which opens into a gas nozzle formed by the outer pipe 7 and a nozzle sleeve 9.

The electrode conductor channel 10 of the guide tube 3 has two constrictions 13, 14 formed by projections 11, 12 in the channel wall. The projections 11, 12 have been produced by diametrical embossing of grooves 15, 16 in the outside of the guide tube.

An electrode fed through the electrode conductor hose 1 and the rear part of the guide tube 3, not shown here, is forced to a first change of direction at the constriction 13 and a second change of direction at the constriction 14. In both constrictions the electrode is guided by the projections 11, 12 towards the inner wall of the guide tube.

The electrode leaves the guide tube 3 eccentrically and is forced to a third change of direction when it enters the guide channel 17 of the contact nozzle 4, the diameter of which is smaller than the inner diameter of the guide tube at its narrowing section. The inner diameter of the guide tube should be 1.5 to 5 times the inner diameter of the contact nozzle. The slightly curved electrode is straightened in the guide channel 17 and thereby slides along the wall of the guide channel, whereby a very good contact is achieved between the electrode and the contact nozzle.

It is conceivable to provide the guide tube only with a constriction, which would force the electrode to only two changes of direction when passing through the guide tube 3 and the contact nozzle 4. This is sufficient for electrodes with a diameter of at least 1.6 mm. When welding with leaner electrodes, however, it is advisable to force the electrode to at least the three directional changes described above, To ensure a good contact in the contact nozzle.

The electrode directed in the contact nozzle leaves this practically completely straight and the electrode can therefore be directed exactly towards the welding point without difficulty.

The production of the guide tube constrictions is very simple.

By an exact setting of the embossing depth, the desired channel cross-section at the constriction can be determined very accurately.

The burner nozzle is primarily intended for use with fully automated welding equipment, e.g. in connection with robots, in which the direction of the electrode between the contact nozzle and the welding point must not change, which in that case would require additional control and steering equipment.

The burner nozzle according to the invention is particularly suitable for welding with small electrodes, the diameter of which is less than ÛUALIçV 1.6 mm.

Claims (6)

8002937-6 Data Requirements Contact tube at a welding torch nozzle For a fusible wire electrode, the front part of which is a contact nozzle with a straight guide channel. For the electrode and the rear part of which is a guide tube having a larger inner diameter than the contact nozzle, characterized in that the guide tube (3) on its inside is provided with at least one projection (11; 12), which causes an eccentric displacement (13; 14) in the guide tube, For guiding the electrode to the part of the inner wall of the guide tube opposite to the projection. 2.; Contact tube according to claim 1, characterized in that the contact nozzle (4) and the guide tube (3) are releasably connected to each other. Contact tube according to Claim 1 or 2, characterized in that the guide tube (3) is Forsett with two projections arranged one behind the other (11,12). Contact tube according to claim 3, characterized in that the projections (11, 12) are arranged diametrically. Contact tube according to one of Claims 1 to 4, characterized in that the guide tube (3) is provided on its outside with radially directed imprints (15, 16), the material projecting during the imprinting forming the projections (11, 12). ) on the inside of the tube. Contact tube according to one of Claims 1 to 5, characterized in that the inner diameter of the guide tube (3) is 1.5 to 5 times as large as the diameter of the guide channel (17) of the contact nozzle (Q).