GB651973A - Improvements in or relating to the manufacture of fluted tools and like articles - Google Patents

Abstract

651,973. Making drills &c. BOOTH, C. H., and HARDWICK, H. B. Jan. 8, 1948, No. 669. [Classes 83 (ii) and 83 (iv)] Axial rolling ; die-rolling ; rolling helical grooves.-A method of rolling articles such as twist drills, taps, augers and the like having helical flutes comprising rotating the blank about its axis under pressure between a pair of platens or oppositely rotating die rolls, the platens or rolls having a succession of transverse ribs.or grooves of progressively increased pitch or spacing to accommodate increases in the circumferential rolling length of the blank as the rolling progresses. The method includes the rolling of parts having straight flutes or of other non-circular shape capable of being formed by the method. The invention is shown applied to the rolling of a twist drill, Fig. 1, comprising flutes 2, 3, lands 4, taper shank 6 and driving tang 7. In one method a cylindrical blank is rolled between two similar platens, one of which is shown in Fig. 2, and comprises flute-forming projections 23-34, a taper-forming portion 18 and a tang-forming portion 19. The rough-forming projections are arranged at progressively increasing angles in order to allow for the lengthening of the blank during rolling. These are followed by four finishing projections. The different portions of the platens may be fixed together by dowels or may be provided with dovetail slides so as to allow relative movement of the parts when rolling work having portions of different diameters. In a modification, Fig. 8, the blank 54 is formed between rolls 52, 53 provided with flute forming projections and with ejection grooves 59, 60. During rolling the work is held between supports 55 and 56. The rolling may be carried out hot or cold and in the former case, preferably in a non-oxidizing atmosphere. If the work is heated electrically, heating may be effected, at least in part, during the rolling operation. The fluted portion and the shank may be separately formed and then welded together.