| 摘要 |
1,261,927. Heating inductors. UNITED STATES STEEL CORP. 7 March, 1969 [7 March, 1968], No. 12274/69. Heading H5H. [Also in Division C7] In a process for hardening the teeth and teeth roots of a circular saw blade the latter is rotated at a peripheral speed of 5 to 50 inches per minute to bring the teeth into an inductor and then under a quenching unit spaced therefrom, e.g. by about one-fifteenth of the blade circumference, a shield being applied to a portion of: the blade that has been already hardened as it approaches the inductor again. As shown in Fig. 3 the shielding device 17 consists of a water-cooled manifold 24 from which depend side plates 25 provided with magnets 28, and has a hook 27 which fits over one of the teeth. The heating effect may be localized by blocks of non-conducting ferromagnetic material extending over the combined length of a tooth and tooth root. The inductor may consist of a length of rectangular section copper tubing 18 of the form shown in Fig. 2 carrying blocks 22, 23 of ferromagnetic material, consisting of fine particles embedded in a plastic matrix. To further improve the fatigue life of the blade a radial slot 30 (Fig. 3) may be cut in the root following the last hardened one.
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