Global Patent Index - EP 1008718 B1

EP 1008718 B1 20040915 - 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 B1 20040915 (EN)

Application

EP 99309759 A 19991203

Priority

US 21051898 A 19981211

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

E21B 10/46; E21B 10/56; E21B 10/60

IPC 8 full level

E21B 10/42 (2006.01)

CPC (source: EP)

E21B 10/42 (2013.01)

DOCDB simple family (publication)

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

DOCDB simple family (application)

EP 99309759 A 19991203; DE 69920145 T 19991203