(19)
(11) EP 0 033 654 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.10.1981 Bulletin 1981/42

(43) Date of publication A2:
12.08.1981 Bulletin 1981/32

(21) Application number: 81300424

(22) Date of filing: 02.02.1981
(84) Designated Contracting States:
BE CH DE FR GB LI NL SE

(30) Priority: 02.02.1980 GB 8003591
09.02.1980 GB 8004427

(71) Applicant: DRILLING & SERVICE U.K. LIMITED
 ()

(72) Inventor:
  • Denzil, Barr John
     ()

   


(54) Rotary drill bits and method of use


(57) To prevent foreign bodies or lost circulation material in drill mud locking the nozzles of a rotary drill bit, the central passageway incorporates a separating means arranged to separate larger particles from the drill mud and to divert them away from the nozzles and out of the bit. The separating means is arranged to operate in a static or dynamic manner.






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