| 摘要 |
<p>1,234,055. Stud and socket fastenings. INSTITUT FRANCAIS DU PETROLE DES CARBURANTS ET LUBRIFIANTS. 4 Oct., 1968 [6 Oct., 1967], No. 47255/68. Heading E2B. [Also in Division F2] A coupling 6..9 between a drill string 3 and a drill mandrel 1 is automatically disengaged when a predetermined pull is applied to the drill string 3 for a predetermined time. As shown teeth 8 integral with flexible strips 6 secured to the mandrel 1 are held in engagement with teeth 9b on a rod 9 by a locking ring 7 fast with the drill string 3. When a predetermined pull is applied to the drill string 3 it moves up relative to the rod 9 against the bias of a spring 15 until the ring 7 releases the strips 6 to permit disengagement of the coupling. To prevent a short pull releasing the coupling accidentally the spring chamber 12 is filled with oil which discharges through a restricted passage 24 into a chamber 10 to slow the upward movement of the drill string relative to the rod 9. In the event of an excessive pull on the drill string 3 a one-way valve 29 opens to discharge oil from the chamber 12 rapidly. The drill string may be a conventional rigid string or may as shown be a flexible drill string with the mandrel supporting a driving motor for the drill bit. The mandrel 1 may be keyed to the drill string 3 for the transmission of torque. The teeth 8,. 9b may be circular as helical ribs. In Fig. 3 (not shown) the locking ring (7) presses balls (36) carried by the mandrel (1) into engagement with a recess (38) in the rod (9). In Fig. 4 (not shown) catches (42) pivoted to the rod (9) engage a circumferential rib (41a) on the mandrel (1).</p> |
