| 摘要 |
1,178,643. Boring earth. GEBR. BOHLER & CO. A.G. 18 March, 1968 [17 March, 1967], No. 13059/68. Heading E1F. A device for drilling into bedrock covered with top soil or loose rock, comprises a headpiece 3 to which may be attached a casing comprising pipes 5 and connecting sleeves 4, and/or a boring bar comprising bars 10 and connecting sleeves 11, with a rotary percussion bit 6 on the casing, and a percussion bit 12 on the boring bar, flushing fluid being fed in through a central duct 2, 9, and discharged through aperture 7 in the headpiece. In operation, the casing is increased by one pipe length and attached to the headpiece, and advanced correspondingly. The boring bar is then increased in length and attached to the headpiece, and used to drill out material within the casing. This is repeated until bedrock is reached, when boring continues with the boring bar alone. Alternatively, bits 6 and 12 may be used to drill simultaneously, suitable clearance being provided between them for flow of flushing fluid. |
