| 摘要 |
A method of severing an elongated flat metal tube (10) of the type including upper and lower flat horizontal walls (10a, 10b), vertical edge walls and vertical partition walls spaced between the edge walls and interconnecting the upper and lower walls to divide the tube into a series of parallel, generally rectangular, longitudinally extending passages. The tube is cut by forming transverse kerfs in the upper and lower walls of the tube and thereafter exerting a relative pulling force on the tube sections on opposite sides of the plane in which the kerfs have been formed to tear apart the remaining tube material at the severing plane and sever the tube. The kerfs are formed in a two-step broaching operation comprising a first cut in which a narrow generally V-shaped narrow angle kerf is formed and a second cut in which the kerf is widened to provide a wide, generally V-shaped, wide angle kerf.
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