Preform cutting elements for rotary drill bits

(19)

(11)

EP 1 052 367 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	27.12.2000 Bulletin 2000/52

(43)	Date of publication A2:
	15.11.2000 Bulletin 2000/46

(21)	Application number: 00303645.6

(22)	Date of filing: 28.04.2000

(51)	International Patent Classification (IPC)⁷: E21B 10/56

(84)	Designated Contracting States:
	AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
	Designated Extension States:
	AL LT LV MK RO SI

(30)

Priority:

14.05.1999 GB 9911139

(71)	Applicant: Camco International (UK) Limited
	Stonehouse, Gloucestershire GL10 3RQ (GB)

(72)	Inventors:
	Griffin, Nigel Dennis Whitminster, Gloucestershire GL2 7PS (GB) Watson, Dean Travers Leckhampton, Cheltenham GL50 2HA (GB)

(74)	Representative: Bailey, Richard Alan
	A.R. Davies & Co., 27 Imperial Square Cheltenham, Gloucestershire GL50 1RQ Cheltenham, Gloucestershire GL50 1RQ (GB)

(54)	Preform cutting elements for rotary drill bits

(57) A preform cutting element, for a rotary drag-type drill bit, includes a facing table 10 of superhard material having a front face and a rear surface bonded to the front surface of a substrate 12 which is less hard than the superhard material, the cutting element having a peripheral surface which includes at least one cutting apex 18 defined between two adjacent regions of the peripheral surface which are disposed at an angle to one another, and the rear surface of the facing table 10 being formed with at least one protuberance 20 which projects into a correspondingly shaped recess in the substrate 12.

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