Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Reexamination Certificate
1999-12-17
2001-06-26
Bagnell, David (Department: 3672)
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
C175S331000, C384S092000
Reexamination Certificate
active
06250407
ABSTRACT:
TECHNICAL AREA OF THE INVENTION
The present invention relates to a rotary drilling bit wherein a rotary cutter is mounted on a journal by means of cylinder bearings.
PRIOR ART
A conventional manner to orient the rotary cutter of a rotary drilling bit in the axial direction relative to the journal of the leg is by inserting bearing balls in an interface between the cutter and the journal. The balls are introduced via a filling opening in the journal, whereafter said hole is closed by a locking pin which is welded to the journal. These balls primarily do not have any bearing function but when the main axial bearings (e.g., Stellite® washers) become worn, the balls can be exposed to axial strains, which is not desirable since that can to a substantial degree shorten the life of the rotary cutter bit.
Through U.S. Pat. No. 4,256,193 there is previously known a rotary drilling bit which does not include a number of balls for axial locking of the rotary cutter relative to the journal of the leg. The rotary cutter of said rotary drilling bit has a flange at the area of its open end. Said flange cooperates with cylinder bearings which form a radial bearing situated at the open end of the rotary cutter when the same is mounted on the leg, for securing the rotary cutter in the axial direction relative to the journal. A filling opening is provided in the leg to enable the rolling elements to be installed with the rotary cutter already mounted on the leg. The filling opening passes axially forwardly beyond the flange, without interfering with it (i.e., the filling opening is disposed radially inwardly of the flange) and has a smallest diameter which is somewhat greater than the diameter of the rolling elements that shall be mounted through the filling opening. Since the filling opening is straight, extends parallel to the axial axis of symmetry of the rotary cutter and does not interfere with the flange of the rotary cutter, said filling opening will interfere with the bearing race of the radial bearing situated closest to the open end of the rotary cutter, i.e., the filling opening opens into the bearing race and removes a portion of the same in the circumferential direction. This removed portion must be replaced by a filler piece which is placed in the filling opening when all the rolling elements are assembled at the radial bearing closest to the open end of the rotary cutter. The part of the filler piece that extends axially forwardly of a rear axial end of the radial bearing and that replaces the removed portion of the bearing race must be formed with a curvature that corresponds to the curvature of the bearing race and said part must be mounted with great exactness. Also, there is a risk is that a difference in level may arise at transitions between the filler piece and the bearing race (i.e., there steps are formed between the filler piece and the bearing race if the filler piece is not positioned with exact precision), which naturally impairs the life of the actual radial bearing.
OBJECTS AND SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a rotary drilling bit wherein the rotary cutter is axially secured by a flange on the rotary cutter without cutting into the bearing arrangement of the rotary cutter bit.
Another object of the present invention is to improve the radial bearing arrangement of the rotary cutter bit compared to rotary drilling bits of conventional design.
Still another object of the present invention is to improve the axial bearing arrangement of the rotary cutter bit compared to conventional rotary.
At least the primary object of the present invention is realized by a rotary drilling bit that comprises a leg forming a journal, the journal defining a first axis. A rotary cutter is rotatably mounted on the journal for rotation about the first axis. The cutter carries rock cutting elements. First and second axially spaced radial bearing arrangements are disposed in an interface between the journal and the rotary cutter. Each radial bearing arrangement includes an annular array of cylindrical rolling elements disposed between a radially outer race of the cutter and a radially inner race of the journal. Each rolling element is rotatable about a respective second axis disposed parallel to the first axis. An axial bearing arrangement is arranged in the interface for absorbing axial forces between the rotary cutter and the journal. The leg includes a filling opening arranged substantially parallel to the first axis for enabling the rolling elements of the first radial bearing arrangement to be installed, with the rotary cutter being in a mounted state on the journal. The rotary cutter includes a radial flange arranged to radially overlap the rolling elements of the first radial bearing arrangement for securing the rotary cutter axially on the journal. The flange is disposed axially in front of the filling opening and axially behind the first radial bearing arrangement and includes a recess aligned with a filling opening for accommodating the passage of cylindrical rolling element being installed. A locking pin is disposed in the filling opening for preventing removal of the cylindrical rolling elements of the first radial bearing arrangement. The locking pin includes a lip projecting forwardly past an axial rear end of the flange. The lip is disposed radially inwardly of the flange to avoid blocking rotation of the rotary cutter. The lip terminates axially behind the cylindrical rolling elements of the first radial bearing arrangement.
REFERENCES:
patent: 4256193 (1981-03-01), Kunkel et al.
patent: 4263976 (1981-04-01), Lachonius
patent: 4427307 (1984-01-01), Norlander et al.
patent: 4516640 (1985-05-01), Karlsson
patent: 4619534 (1986-10-01), Daly et al.
patent: 6026917 (2000-02-01), Zahradnik et al.
Bagnell David
Burns Doane Swecker & Mathis L.L.P.
Dogherty Jennifer
Sandvik AB
LandOfFree
Rotary drill bit having filling opening for the installation... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotary drill bit having filling opening for the installation..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotary drill bit having filling opening for the installation... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541266