Boring or penetrating the earth – Processes – Boring curved or redirected bores
Reexamination Certificate
1999-10-26
2001-10-30
Neuder, William (Department: 3672)
Boring or penetrating the earth
Processes
Boring curved or redirected bores
C175S075000, C175S376000, C175S399000
Reexamination Certificate
active
06308789
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to drilling and more particularly to lateral underground drilling, e.g., to provide a conduit for communication lines.
BACKGROUND OF THE INVENTION
Communication lines are commonly placed underground. As permitted, a narrow trench is dug along the intended path of the line and the line is laid in the trench and then covered. This procedure is not complex and relatively inexpensive. However, often it happens that an obstruction lays in the path and digging a trench is not permitted or is too difficult.
In such instances, the alternative is to drill a hole through the ground and under the obstruction. For example, if the lines are to be buried to a four foot depth, a partial trench is first dug to the four foot depth prior to the obstruction and a drill bit mounted on an extendable pipe is fed laterally along the desired path. The pipe is moderately flexible and, in at least one version, the pipe is turned by a powerful motor to turn the bit and thereby auger through the ground with the pipe being fed behind it. A flushing slurry is fed through the pipe and into and through to the leading end of the drill bit. Material that is loosened by the drill bit is flushed by the slurry back through the hole. The line is then pulled through the hole formed by the drill bit and pipe.
All of the above is common to the art of directional drilling. Not referred to, however, and also common to the process explained above, is the need to control the direction of drilling. The drill bit is designed so that it can be maneuvered to change direction. The drill bit itself has a digging head that is non-symmetrical, i.e., teeth are projected angularly from the axis of the drill bit on one side only. During normal drilling, the drill bit is rotated so that the digging action is symmetrically applied and the drill bit travels in a straight line. To change direction, the rotation is stopped and the drill bit is pushed through the ground. At whatever direction the teeth are projected, that is the direction that the drill bit will turn toward (up, down or to either side). When the desired new direction is achieved, the rotation of the bit is commenced to head the digging action in the new direction.
The location of the drill bit and the position of the teeth on the drill bit is monitored through the use of a known detection device. Thus, an operator may determine that the hole is headed too deep, too shallow or otherwise off line in one direction or the other. He stops the rotation of the drill bit with the teeth facing the desired direction. He then pushes the bit forward until the bit is properly directed (which may include a sequence of side to side oscillation of the drill bit) and the normal drilling action is continued.
Whereas existing drill bits work quite well in dirt, they do not work so well in rock or shale. A cone-type drill bit cutting head has been developed to improve performance in rock or shale. Rows of circularly arranged teeth are provided on a conical cutter head that is rotatably mounted about its conical axis to the end of a forwardly protruded and outwardly directed shank of the drill bit. The base portion of the cone side of the conical head carries one of the rows of teeth and with the mounting arrangement described is adjacent to the shank and extends laterally outwardly of the shank. The axis of the rotatable cone is directed inwardly and forwardly. The apex of the cone side and the teeth adjacent the apex cuts the material from the center of the hole while the teeth adjacent the base provide the laterally outermost cutting which forms the hole side.
Whereas the conical cutter is considered an improvement when directional drilling through rock and shale, it is not completely satisfactory (and sometimes unsatisfactory), and an objective of the present invention is to improve on the above-described cone-type drill bit.
BRIEF DESCRIPTION OF THE INVENTION
The present invention modifies the above-described cone-type drill bit. A shank provided on the drill bit is projected forwardly and inwardly. The base of a cone-type (conical) cutter head is rotatably secured to the shank in a manner whereby teeth near the base of the cone side of the cutter (the base portion of the cone side) cuts the material from the center of the hole and the apex of the cone side is projected laterally from the shank to cut the side wall of the hole. This difference can be viewed in the comparison of
FIG. 1
(which illustrates the prior art) and
FIG. 2
(which illustrates the present invention).
This modification is significant in terms of performance. Whereas the prior art drill bit head does not readily produce the desired directional change, such is readily produced by the device of the invention. The reason for the improved performance has not been verified and the following explanations are theories as to why such improvement is achieved.
FIGS. 1A and 2A
, respectively, show the configuration of a hole being dug-by the prior art device and that of the present invention. When attempting to turn the drill bit, only one side of the hole is extended forwardly as indicated by dash lines
12
and
14
in
FIGS. 1A and 2A
, respectively. The desired change of direction is upwardly as viewed in the drawings and as indicated by the arrows. With reference to FIG.
1
and comparing it to
FIG. 1A
, it will be appreciated that the leading end of shank
16
will engage the upper side wall of the extended hole and resist turning of the tool in the upward direction. Applicant's shank
18
is on the opposite or bottom side of the hole and as it engages the extended portion of the hole, it urges the tool upwardly and in the direction of desired turning.
A second theory is suggested by the configuration of the hole being cut. Referring to the configuration of
FIG. 2A
, the center of the hole (point X) is the point of furthest extension. When full rotation of the tool is commenced, the bit will follow the path of least resistance and because the upper side is relieved, the bit will be urged upwardly.
In
FIG. 1A
, the center of the hole (point y) is inset from the side extensions. As the bit rotates to the bottom side of the hole, the inset center of the hole and the cam-like configuration that it produces will urge the bit back toward the bottom and directional change is resisted.
The above differences, advantages and benefits will, however, be more fully appreciated by reference to the following detailed description having reference to the accompanying drawings, referred to therein.
REFERENCES:
patent: 3633686 (1972-01-01), Bennett
patent: 4832143 (1989-05-01), Kaalstad et al.
patent: 4848486 (1989-07-01), Bodine
patent: 4936398 (1990-06-01), Auty et al.
patent: 5778991 (1998-07-01), Ranquist et al.
patent: 6119797 (2000-09-01), Hong et al.
Kuenzi Neal A.
Kuenzi Rodney R.
Harrington Robert L.
Neuder William
Walker Zakiya
LandOfFree
Drill bit for directional drilling does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Drill bit for directional drilling, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drill bit for directional drilling will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2604528