摘要 |
Tubing is made by continuously pulling steel strip at a predetermined feed speed from a supply, shaping the strip into a multilayer tube of a predetermined mass per unit length, and advancing the tube at the feed speed through a soldering station. The strip is coated with a solder-type material and an electric current is passed through the tube between a contact engaging the tube in the station and a contact engaging the tube downstream of the station to fuse the solder and tube together. The contact outside the soldering station is displaced so that the spacing between the contact is varied substantially proportionately with the product of the feed speed and the predetermined mass per unit of length of the tube. Downstream of the soldering station the tube and solder are cooled to bond the tube together. |