| 摘要 |
In the manufacture of tubing, and particularly finned tubing, for use by the heat transfer industry in the manufacture of heat exchangers, annealed ends and lands are desirable in certain applications to facilitate the assembly of the tubes to headers and baffles by expanding techniques. Such spot-annealed portions can be produced on a continuous basis by the described apparatus and method in which the moving tube is passed through a heating chamber which reciprocates on a carriage in the direction of tube movement. The heating chamber has a pair of power-actuated, current-carrying clamps which grip spaced portions of the tube so as to resistance-heat the tube portion between the clamps. The heating chamber and carriage move with the tube while it is clamped to provide sufficient heating time. The carriage then returns to its starting position. If desired, an inert gas can be supplied to the heating chamber to prevent oxidation and/or discoloration. Also, if desired, a quench can be supplied in a secondary chamber positioned on the carriage immediately downstream of the heating chamber to prevent post-oxidation of the annealed tube.
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