| 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. The heat coming from the welding process produces negative effects in a contact tube. The material of the contact tube which becomes hot combines easily with the deposits on the wire surface. The result of this is that: The transition resistance between contact-tube bore and welding wire changes and thus the welding-current intensity changes. The contact-tube bore becomes smaller, and the wire feed rates increase. To remove these shortcomings, a contact tube has been developed in which passages are located which open out into an annular encircling hollow space at the tip of the contact tube. The torch is designed in such a way that it is able to direct the cooling water into the contact tube, where it can flow in the feed passage up to the tip of the contact tube. The existing heat of the contact tube is absorbed by the water and is supplied to the torch via the return passage. The contact tube therefore remains cold.
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