| 摘要 |
<p>675,273. Heat-treating metallic tubes. STEVENS, A. H. (Ohio Crankshaft Co.). Nov. 3, 1948, No. 28545/48. Class 72 In a method of surface hardening the inner and outer surfaces of an elongated metallic tube, the two surfaces are hardened simultaneously. To prevent distortion the outer surface is hardened to a greater depth than the inner surface, the preferred ratio of depth being 4 to 3. The process may be performed, as shown, by an inner heating and quenching head 12, 13 and an outer heating and quenching head 20, 21 which move together along the axis of a tube 10. There may be relative rotation between the tube and the heating and quenching heads.</p> |
