| 摘要 |
The present invention relates to a contact tube for inert gas-shielded arc welding, in order to guide the welding wire and transmit the current from the contact tube to the welding wire, which is effected in a known manner by a contact tube in which the guide bore is 0.2 mm larger than the wire to be welded. The welding wire, wound under an initial tension on spools, passes in a curved form through the contact tube. The direction in which the welding wire leaves the contact tube alters depending on the pretensioning of the welding wire or the wear of the contact tube. The welding contour cannot be achieved in an exact and reproducibly accurate manner. On the other hand the curvature of the wire is desired so that in the guide bore of the contact tube, which is 0.2 mm larger, the wire rests in a punctiform manner against the borehole wall and thus permits current to be transmitted. Since every 0.5 mm enlargement of the outlet opening can produce a deviation in the welding contour of around +1.0 mm, in practice contact tubes that are otherwise still operational are exchanged if the outlet opening has enlarged. The friction of the curved wire against the outlet opening is responsible for the change in the latter. In order to eliminate this defect, the invention proposes aligning the curved welding wire so that a straight welding wire is fed to the contact tube using a pressing mechanism. The positive properties of this contact tube, such as: ... Original abstract incomplete.
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