| 摘要 |
<p>1,217,921. Continuous casting; rolling; forging; making billets. BOHLER & CO. A.G. GEB. 13 Nov., 1968 [13 Nov., 1967], No. 53842/68. Headings B3A, B3F, B3H and B3M. A hollow casting, e.g. of steel, is produced by the method described in Specification 1,088,909, i.e. a continuous casting is conveyed from a mould in a curved path, first downwardly, then upwardly to a level above that to which the molten core can rise, and then the hollow shell is compressed by at least one pair of rolls or at least one forging or pressing device (or more, in stages) so that the hollow space is eliminated and inner faces of the shell are welded together and subjected to hot working. For making billets of high-speed tool steel or ledeburitic Cr-steel for sheet or strip production, the shell thickness (controlled by adjustment of casting speed or direct water cooling) is not more than 50 mm. and there is a hydrogen atmosphere in the hollow space. The temperature of the casting is controlled by insulation or cooling to obtain the desirable hotworking temperature. Lengths may be cut from the strand, taking care to close the strand at the cutting point to exclude air, and reheated in a furnace to attain the hot-working temperature. Reference has been directed by the Comptroller to Specification 1,088,909.</p> |
