Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Reexamination Certificate
2001-09-28
2003-08-12
Bagnell, David (Department: 3672)
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
C175S426000, C175S428000, C175S434000
Reexamination Certificate
active
06604588
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to gage trimmers and, more specifically, to gage trimmers that are mounted on a bit gage for maintaining accurate tolerances in the bit gage area while drilling a hole in earth formations and to a bit incorporating the same.
Current gage trimmers
2
, also referred to as “preflat cutters”, are manufactured from standard polycrystalline diamond cutters, which comprise a polycrystalline diamond layer (“PCD”)
4
over a carbide substrate body
5
, as for example shown in FIG.
1
. These gage trimmers are formed by cutting off a portion of a PCD cutter at an angle to the cutter central axis. This is typically accomplished by grinding to form a flat surface
6
extending across the cutter ultra hard material layer and a flat surface
7
across the body of the cutter as for example shown in FIG.
1
. The two flat surfaces are typically angled relative to each other. The flat surface
6
formed on the ultra hard material layer is referred to herein as the “ultra hard material flat” or “ultra hard material preflat area”. The ultra hard material flat extends from the upper surface of the PCD layer to the interface of the PCD layer with the substrate.
The gage trimmers
2
are mounted in the gage area
12
of a bit
14
, i.e., the circumferential side area of the bit defining the bit gage (FIG.
2
). The gage trimmers are typically mounted above all bit cutters and with their ultra hard material flat
6
parallel to the longitudinal axis of the bit, and thus parallel to the drill hole or bore wall
16
as for example shown in FIG.
1
. Consequently the entire ultra hard material flat
6
is subject to engagement with the wall
16
of the drilled hole. For descriptive purposes the ultra hard material flat is also referred to herein as the “critical flat.” The flat
7
formed on the gage trimmer body provides clearance between the trimmer body and the bore wall
16
.
The critical flat
6
serves as a bearing against the drilled hole wall to prevent the wear of the bit body by the hole wall. Consequently, the gage trimmers do not wear as much as standard PCD cutters because they bear against and do not cut the bore wall. However, it is important that the gage trimmers do not wear significantly, otherwise the bit body can wear to a point that it is under gage.
One of the more significant problems with gage trimmers is that during drilling operations their PCD/carbide interface is exposed to significant shear loads. These loads are due to contact with hole walls by the critical flat during cutting. The gage trimmers are operated at an effective 0° rake angle without any or with minimal clearance behind the ultra hard material, as for example shown in FIG.
1
. Thus, in contrast with the normal full-round shear cutters, which are inserted into the bit at a rake angle, the gage trimmer interface between the PCD layer and the carbide body of a gage trimmer is subject to direct shear loading.
The interface region is often the weakest part of the gage trimmer. Consequently the direct shear loading on the interface region results in early failure of the gage trimmer. Furthermore, as the gage trimmer wears with time, the interface is exposed to abrasive wear and impact due to contact with the bore wall, which often leads to erosion of the carbide substrate, resulting in failure of the gage trimmer. Failure of the gage trimmers ultimately results in failure to keep the drill hole in gage.
SUMMARY OF THE INVENTION
A gage trimmer and a bit incorporating such a gage trimmer is provided. In an exemplary embodiment the gage trimmer comprises a body having a central longitudinal axis, a base and an end face, the body having a circumferential surface comprising a generally cylindrical portion and a relatively flat portion formed along a first plane. An ultra hard material layer is formed over the end face having a circumferential surface comprising a generally cylindrical portion and a relatively first flat portion formed along a first plane for bearing against a circumferential wall of a hole drilled by the bit. The first plane is inclined toward a diameter of the cutting layer in a direction away from the interface surface at an angle relative to a second plane parallel to a third plane aligned with said central longitudinal axis. The flat portion does not extend to the interface surface. Furthermore, in the exemplary embodiment, the ultra hard material layer thickness is greater at the circumferential flat portion than at the circumferential cylindrical portion of the ultra hard material layer.
REFERENCES:
patent: 4570726 (1986-02-01), Hall
patent: 4861350 (1989-08-01), Phaal et al.
patent: 4954139 (1990-09-01), Cerutti
patent: 5119714 (1992-06-01), Scott et al.
patent: 5120327 (1992-06-01), Dennis
patent: 5201376 (1993-04-01), Williams
patent: 5287936 (1994-02-01), Grimes et al.
patent: 5341890 (1994-08-01), Cawthorne et al.
patent: 5435403 (1995-07-01), Tibbitts
patent: 5469927 (1995-11-01), Griffin
patent: 5484330 (1996-01-01), Flood et al.
patent: 5486137 (1996-01-01), Flood et al.
patent: 5494477 (1996-02-01), Flood et al.
patent: 5566779 (1996-10-01), Dennis
patent: 5590727 (1997-01-01), Tank et al.
patent: 5590728 (1997-01-01), Matthias et al.
patent: 5598750 (1997-02-01), Griffin et al.
patent: 5605199 (1997-02-01), Newton
patent: 5655612 (1997-08-01), Grimes et al.
patent: 5711702 (1998-01-01), Devlin
patent: 5740874 (1998-04-01), Matthias
patent: 5743346 (1998-04-01), Flood et al.
patent: 5788001 (1998-08-01), Matthias et al.
patent: 5816347 (1998-10-01), Dennis et al.
patent: 5829541 (1998-11-01), Flood et al.
patent: 5881830 (1999-03-01), Cooley
patent: 5890552 (1999-04-01), Scott et al.
patent: 5967250 (1999-10-01), Lund et al.
patent: 5971087 (1999-10-01), Chaves
patent: 5979577 (1999-11-01), Fielder
patent: 6000483 (1999-12-01), Jurewicz et al.
patent: 6009963 (2000-01-01), Chaves et al.
patent: 6053263 (2000-04-01), Meiners
patent: 6065554 (2000-05-01), Taylor et al.
patent: 6068071 (2000-05-01), Jurewicz
patent: 6082223 (2000-07-01), Tibbitts
patent: 6135219 (2000-10-01), Scott
patent: 6170583 (2001-01-01), Boyce
patent: 6176333 (2001-01-01), Doster
patent: 6196341 (2001-03-01), Chaves
patent: 6202770 (2001-03-01), Jurewicz et al.
patent: 6202771 (2001-03-01), Scott et al.
patent: 6202772 (2001-03-01), Eyre et al.
patent: 6290008 (2001-09-01), Portwood et al.
patent: 6332503 (2001-12-01), Pessier et al.
patent: 6405814 (2002-06-01), Eyre et al.
patent: 6460636 (2002-10-01), Yong et al.
patent: 6510910 (2003-01-01), Eyre et al.
patent: 6513608 (2003-02-01), Eyre et al.
patent: 6527069 (2003-03-01), Meiners et al.
patent: 0295032 (1988-12-01), None
patent: 2274129 (1994-07-01), None
patent: 2323398 (1998-09-01), None
patent: 2337063 (1999-11-01), None
Belnap Lynn L.
Eyre Ronald K.
Middlemiss Stewart
Bagnell David
Bomar T. Shane
Christie Parker & Hale LLP
Smith International Inc.
LandOfFree
Gage trimmers and bit incorporating the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gage trimmers and bit incorporating the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gage trimmers and bit incorporating the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3081056