Cutting elements faced with superhard material

(19)

(11)

EP 0 878 602 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	25.08.1999 Bulletin 1999/34

(43)	Date of publication A2:
	18.11.1998 Bulletin 1998/47

(21)	Application number: 98303775.5

(22)	Date of filing: 14.05.1998

(51)	International Patent Classification (IPC)⁶: 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:

16.05.1997 GB 9709861

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

(72)	Inventor:
	Griffin, Nigel Dennis Whitminster, Gloucestershire (GB)

(74)	Representative: Carter, Gerald
	Arthur R. Davies & Co. 27 Imperial Square Cheltenham, Gloucestershire GL50 1RQ Cheltenham, Gloucestershire GL50 1RQ (GB)

(54)	Cutting elements faced with superhard material

(57) A preform element, such as may be used as a cutting element in a drag-type rotary drill bit, comprises a polycrystalline diamond facing table bonded to a tungsten carbide substrate. The rear face of the facing table is formed with a series of elongate ribs and grooves, and the front face of the substrate is formed with a series of elongate ribs and grooves which interengage the grooves and ribs respectively in the facing table. The ribs and grooves on each surface include ribs which are spaced from adjacent grooves so that the part ofthe surface which extends from the bottom of a groove to the apex ofthe adjacent rib is non-linear and discontinuous. The discontinuity between each rib and groove may be an intervening surface portion which is flat, inclined, curved or otherwise shaped.

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