| 摘要 |
PCT No. PCT/HU85/00052 Sec. 371 Date Jun. 26, 1986 Sec. 102(e) Date Jun. 26, 1986 PCT Filed Aug. 30, 1985 PCT Pub. No. WO86/01561 PCT Pub. Date Mar. 13, 1986.A rotary drilling apparatus is disclosed, in which the pipe string is both lifted and lowered, as well as rotated, by an opposed pair of endless chains, eliminating the need for a high drilling tower structure. An advantageous form of gripping mechanism, attached to the chain links, enables the pipe string to be gripped with extremely heavy force, with the gripping means automatically confirming to pipe diameters of a variety of sizes and also conforming to the pipe coupling elements, as well as to the pipe areas inbetween, so that manipulation of the pipe string can be continuous. The gripping assembly includes a plurality of articulated gripping elements supported at each end by pivoted support arms. This assembly is urged against the pipe string by high pressure, hydraulic pistons. |
