Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
2002-10-21
2004-04-20
Dunn, Tom (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
Reexamination Certificate
active
06723945
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a welding device, in particular to a welding device for arc welding by lifting and striking.
Welding devices are known for welding a weld part which comprise a holder for weld parts. The holder is movable substantially perpendicularly to the surface of a workpiece and away from it. The welding device comprises a system for producing an arc by lifting and striking between the weld part and the surface of the workpiece. To influence the arc, it is known that the welding device is equipped with a system comprising a field former for producing magnetic field acting on the arc. A welding device of this type is described, for example, in German Patent No. 44 00 957. This device is provided with an electromagnetic coil to which a flux guiding part with a truncated cone shaped field former is coupled. The extended surface line of the field former indicates the welding position. A magnetic field component extending substantially radially to the weld part is formed on the substantially annular pole face of the field former. European Patent No. 167 150 and German Patent No. 195 12 094 describe further embodiments of a welding device. Devices of the kind described in these patents, however, typically use magnetic fields generated by coils, that add complexity and expense, or permanent magnets that will deteriorate in the high temperature environment of the welding operation.
SUMMARY OF THE PRESENT INVENTION
On the basis of the foregoing, the object of the present invention is to develop the known welding device so as to improve the welded joint produced by the welding device.
The welding device according to the invention, in particular for arc welding by lifting and striking, is distinguished in that it comprises at least one field former consisting at least in part of a low-retentivity steel. The field former influences the magnetic field and therefore also the propagation of the arc. A field former consisting at least in part of a low-retentivity steel is particularly effective, in particular if workpieces made of non-magnetic materials are to be welded together.
According to a further feature of the invention there is proposed a welding device comprising at least one field former having at least one straight portion. This allows the arc to be influenced better in the case of non-circular weld parts. It is proposed, in particular, that the field former consists at least in part of a low-retentivity steel.
According to an advantageous configuration of the welding device, it is proposed that the at least one field former has a polygonal cross section, and is preferably substantially U-shaped in design. The arms of the U-shaped field former are preferably spaced from one another such that the weld part can be introduced at least in part between them. This configuration of the field former allows the magnetic field to be influenced even in the corner region, in particular in the case of weld parts with a substantially rectangular cross section.
According to a further advantageous configuration of the welding device it is proposed that two U-shaped field formers are provided which are spaced with free arms directed toward one another.
It has been found that the magnetic field and therefore also the arc can be influenced sufficiently and adequately for the quality of the welded joint if the at least one field former is rod-shaped in design. The welding device according to the invention preferably comprises two field formers extending substantially parallel to one another.
According to a further advantageous configuration of the welding device, it is proposed that the at least one field former is connected to a mouth-piece which can be brought into contact with the surface of the workpiece.
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Dunn Tom
Johnson Jonathan
Murphy Edward D.
Newfrey LLC
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