| 摘要 |
<p>1469296 Drills HELLER Gebr 1 April 1974 [4 April 1973] 14378/74 Heading B3C [Also in Division B4] A drill for drilling for example stone or concrete and for use with a percussion drilling machine or a rotary hammer drill comprises a shank portion 4 of the drill body 1 surrounded by a receiving member 2 of a material which is different from and of lesser hardness than the drill body, and has the part securely connected thereto, and the free end 5 of the shank portion extends at least approximately as far as the corresponding end of the receiving part or protrudes from the latter. The receiving member has a portion which in use fits in an adaptor and which extends over at least a part of the axial length of the receiving member and the peripheral surface of which portion is defined by lines extending its whole axial length, and each line being over its whole length at a constant radial distance from the axis of the drill. The part 2 transmits torque to the drill body whilst impacts are applied directly to the drill end. The surface of the shank portion is suitably shaped to key the part 2 thereto. The part is of aluminium, aluminium alloy or plastics suitably reinforced by glass fibres, metal wool or fibres or graphite.</p> |
