Global Patent Index - EP 1008718 A3

EP 1008718 A3 2001-04-11 - Rotary drag-type drill bits and methods of designing such bits

Title (en)

Rotary drag-type drill bits and methods of designing such bits

Title (de)

Drehbohr-Fräsmeissel und Verfahren zu deren Entwicklung

Title (fr)

Trépans racleurs rotatifs et méthodes pour leur conception

Publication

EP 1008718 A3 (EN)

Application

EP 99309759 A

Priority

US 21051898 A

Abstract (en)

[origin: EP1008718A2] The invention provides a rotary drag-type drill bit in which the relationship of torque to rotary bit speed is such that torque generally increases with bit speed. Such a bit has a reduced tendency to exhibit the phenomenon known as "stick-slip" while drilling, when compared with bits having a different torque /speed characteristic, as a result of the positive damping effect of the torque/speed relationship. One method of designing such a drill bit comprises ascertaining the torque/rotary bit speed relationship, or other correlated relationships, for a number of different drill bit designs and then selecting from those designs a design having the desired type of relationship. Examples of drill bit structures specifically designed to achieve the desired torque/speed relationship are also disclosed. <IMAGE>

IPC 1-7 (main, further and additional classification)

E21B 10/46; E21B 10/56; E21B 10/60

IPC 8 full level (invention and additional information)

E21B 10/42 (2006.01)

CPC (invention and additional information)

E21B 10/42 (2013.01)

Citation (search report)

Designated contracting state (EPC)

AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

EPO simple patent family

EP 1008718 A2 20000614; EP 1008718 A3 20010411; EP 1008718 B1 20040915; DE 69920145 D1 20041021; DE 69920145 T2 20050922

INPADOC legal status


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