| 摘要 |
1,138,844. Boring earth etc.; releasable fastenings. P. GROSPAS. 22 March, 1966 [22 March, 1965], No. 12647/66. Headings E1F and E2A. Cable-drilling apparatus comprises a cable 9 supporting a bit 13, and a column 10 having a head 7 for the supply of drilling fluid to, or removal of drilling fluid from, the bit. The head is adjustable for vertical movement in a derrick 1. The column has dependant conduits 57, 58 on which the bit is guided, and the upper section of the column is of square section so that the column and bit may be rotated by a rotary table 12. During drilling the bit and its supporting rods 14, 15 are connected to the cable by a latch 17 and springs 16 carried by the rods are compressed by an internal projection 19 in the column. If the column is raised to engage the projection with the latch, the rods and bit are disconnected from the cable and their weight is transferred to the projection. The latch (see Fig. 3) comprises a tubular guide 64 fixed to the rods and bit, the guide carrying members 66 pivotting about the lower edge of a plate 71 fixed to the guide. In the position of the members shown in Fig. 3 arms 73 of the members cooperate with an end fitting 18 on the cable to support the rods and bit. On engagement of the projection 19 with arms 77 of the members, the members pivot to release the fitting and transfer the weight of the rods and bit to the projection. The flushing fluid which may be mud, air or a liquid-solid-gas mixture passes down the column and is discharged by the conduits to return to the surface in the annulus between the column and hole. In a modification fluid from the column passes through a central passage in the bit which is guided by the interior of the column. In a further modification having reverse circulation of drilling fluid the springs are outside of an enlargement at the lower end of the column, and engage the top of the bit and an external projection on the column. |
