Heat treatment of drawn copper tubes - where inert gas is circulated through bore of hot tube to remove drawing lubricants without permitting air to enter

摘要

The tubes are made via pressing or rolling, followed by drawing to finished size using a lubricating oil. Separate tube lengths are joined together, and are heated via electric resistance or induction to above 600 deg.C. in a continuous process. An inert gas is fed through the bore of the heated tube to sweep out the oil evaporated by the heat. In the pref. annealing plant, the tail end of a coil of tube is connected to a suction pump, whereas the front end of the coil is connected to one of two chambers contg. inert gas and pref. connected to the delivery side of the pump. An economic, continuous annealing process, where drawing oils are removed from the tube bore without the entry of oxygen into the tubes.