Method and device for the formation and protection of deposits of sedimentary materials on the bottoms of bodies of water.

摘要

1355552 Making cover blanks: twisting E LARSSON 14 June 1971 [12 June 1970] 27726/71 Headings B3A and B3E A helical borer is made by guiding a pair of steel wires 21, 22 towards a common position where they are gripped by a rotating and axially movable fixture 33 and twisted together. The wires are pulled through inclined guide channels 30 in guides 29 and then supported by jaws 35 with guide grooves 36. A central core 20 may be fed axially within the wires. The wires are subsequently unwound from each other and are ground externally to form a cutting edge (53), Fig. 3 (not shown): a gimlet end (55) may be fitted. In another embodiment, Fig. 2 (not shown), a single steel wire (41) is wound around a pre-formed helically wire fed axially through the centre of the guides 29.