U.S. patent number 3,858,671 [Application Number 05/353,357] was granted by the patent office on 1975-01-07 for excavating tool.
This patent grant is currently assigned to Kennametal Inc.. Invention is credited to David C. Johnstone, John F. Kita.
United States Patent |
3,858,671 |
Kita , et al. |
January 7, 1975 |
EXCAVATING TOOL
Abstract
An excavating tool or bit for drilling holes in earth formations
in which the bit has a body with a working face on one end that is
provided with hard wear resistant carbide inserts. The inserts on
the working end of the body include peripheral gauge inserts and
disposed in the side of the body, preferably in axial alignment
with the gauge inserts, are other inserts also for holding gauge
and advantageously having square outer ends with the diagonals of
the squares arranged vertically and horizontally. More than one row
of the side gauge inserts can be provided in the bit body.
Inventors: |
Kita; John F. (Bedford, PA),
Johnstone; David C. (Claysburg RD, PA) |
Assignee: |
Kennametal Inc. (Latrobe,
PA)
|
Family
ID: |
23388761 |
Appl.
No.: |
05/353,357 |
Filed: |
April 23, 1973 |
Current U.S.
Class: |
175/426; 175/414;
175/406 |
Current CPC
Class: |
E21B
10/56 (20130101) |
Current International
Class: |
E21B
10/56 (20060101); E21B 10/46 (20060101); E21c
013/00 () |
Field of
Search: |
;175/410,413,374,375,411,353,406 ;299/91,79 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Murtagh; John E.
Assistant Examiner: Favreau; Richard E.
Attorney, Agent or Firm: Crosby; Melvin A.
Claims
What is claimed is:
1. In a mining bit; a bit body having a working face at the front
end and a peripheral wall extending rearwardly from said working
face, inserts mounted in the front end of said body and distributed
over said working face and protruding axially therefrom, at least
one row of gauge inserts mounted in the front end of said body near
the juncture of said working face and said peripheral wall and
extending angularly from the body so as to protrude radially
outwardly beyond said peripheral wall and axially outwardly beyond
said front end, and at least one row of further inserts extending
radially into the peripheral wall of said body in circumferentially
spaced relation and spaced axially along said peripheral wall from
said gauge inserts, each said further insert having a radially
extending sharp cutting edge on each of the axially upwardly and
axially downwardly facing sides thereof, the radially outer end of
each said further insert being disposed radially inwardly from the
cylindrical envelope of the radially outermost points on said gauge
inserts a fraction of the amount which the gauge inserts protrude
radially beyond said peripheral wall.
2. A mining bit according to claim 1 in which a said further insert
is disposed in each axial plane of the bit body which contains a
gauge insert.
3. A mining bit according to claim 1 in which the radially outer
end of each further insert is rectangular in cross section with a
diagonally of the rectangle disposed in a vertical axial plane of
the bit body.
4. A mining bit according to claim 1 in which each gauge insert has
a said further insert in axial alignment therewith, each said
further insert having a radially extending sharp cutting edge on
each of the axially upwardly and axially downwardly facing sides
thereof.
5. A mining bit according to claim 1 in which the further inserts
in said one row thereof are in axial alignment with respective ones
of said gauge inserts, and an additional row of said further
inserts axially displaced along said peripheral wall from said one
row and circumferentially staggered relative to the said further
inserts of said one row thereof, the inserts of said additional row
thereof also having radially extending sharp edges formed on the
axially upwardly and axially downwardly facing sides thereof.
6. An insert according to claim 1 in which said hard wear resistant
material comprises cemented tungsten carbide.
7. An insert according to claim 1 in which the radially outer end
of each said further insert is disposed about 0.010 inches radially
inwardly from the cylindrical envelope of the radially outermost
points of said gauge inserts.
Description
The present invention relates to excavating tools, particularly in
the form of bits, and is especially concerned with an improved
arrangement for mounting gauge controlling inserts in a bit body
and to the formation of the gauge controlling inserts.
Tools for drilling holes in earth formations are known and comprise
steel bodies which are preferably provided with hard wear resistant
inserts mounted in the working face of the bit body. Such hard wear
resistant inserts include at least one row about the periphery of
the working face serving as gauge inserts so that as drilling
proceeds, the sides of the bit will not wear away rapidly and cause
a hole to be tapered. A tapered hole is particularly
disadvantageous because if a bit becomes worn it must be removed
from a hole and replaced by another, a tapered hole can create
problems because a new full size bit will be likely to wedge in the
tapered hole.
The inserts mounted in the working face of the bit are extremely
hard and wear resistant, generally being formed of a cemented
tungsten carbide material, and will wear away only slowly, so that
the gauge inserts provided tend to maintain the gague of a hole
being drilled for a substantial period of time.
It has been found, however, that the gauge inserts will sometimes
wear off more rapidly than is desired, particularly when hard
formations are encountered so that even with hard wear resistant
gauge inserts the bit may wear away somewhat more rapidly than
desired and produce a tapered hole.
With the foregoing in mind, a primary objective of the present
invention is the provision of an arrangement for adding further
gauge controlling inserts in a bit body so as materially to
increase the life of the bit in which the added inserts are mounted
and particularly with respect to holding gauge.
Another object of the invention is the provision of special gauge
inserts mounted in the side of a bit body which present upwardly
and downwardly facing sharp edges so that the added inserts can
assist in cutting operations and can also serve to assist in
breaking up overburden which may collapse on top of the bit during
drilling operations.
These and other objects and advantages of the present invention
will become more apparent upon reference to the following detailed
specification taken in connection with the accompanying drawings in
which:
FIG. 1 is a side view of a typical bit according to the present
invention.
FIG. 2 is a fragmentary vertical sectional view indicated by line
II--II on FIG. 1 and drawn at enlarged scale.
FIG. 3 is a view looking in from the side of FIG. 2 as indicated by
arrow 3 thereon.
FIG. 4 is a perspective view showing a typical gauge insert
according to the present invention.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a bit body which may comprise a
steel forging, for example, has one end in the form of a working
face and the other end adapted for connection to a drive mechanism.
The working face of the bit is ordinarily provided with hard wear
resistant inserts distributed thereover in order to assist in
breaking up the formation being worked and to reduce the rate at
which the bit body wears in use.
One popular type of bit is a bit in which the inserts are rod-like
elements having domed outer ends and either press fitted or brazed
into holes provided therefor in the bit body. The holes are
distributed over the area of the work face and include at least one
row of inserts about the periphery of the working face and usually
extending angularly to the plane of the working face so as to hold
the gauge of the hole being worked by the bit.
The gauge inserts protrude radially from the peripheral wall of the
body and axially from the working end of the body and thereby are
effective for engaging and reducing the material being worked.
According to the present invention, the peripheral wall of the body
is provided with at least one further row of circumferentially
distributed radially extending inserts which protrude radially from
the peripheral wall of the bit body and advantageously to a
distance slightly less than the radial protrusion of the gauge
inserts.
The further inserts when consisting of one row are advantageously
arranged in axial alignment with respective ones of the gauge
inserts. The further inserts preferably have the protruding
radially outer ends thereof squared with the diagonals of the
square extending vertically and horizontally so that as further
insert has a radial cutting edge on each of the axially upwardly
and axially downwardly facing sides thereof.
It is possible to provide at least one further row of the further
inserts in the peripheral wall of the bit body, and when such a
further row is provided, this row is axially displaced from the
first mentioned row of further inserts and the inserts thereof are
circumferentially staggered relative to the further inserts of the
first mentioned row thereof.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings somewhat more in detail, the bit body is
designated at 10 and has one end 12 adapted for connection to a
driving instrumentality while the other end 14, and which may be
considered the front end, forms a working face which is generally
planar and perpendicular to the longitudinal axis of the bit body.
The bit body comprises a peripheral wall 16 extending rearwardly
from front end 14 and advantageously tapering inwardly slightly in
the rearward direction.
Rearwardly of peripheral wall 16, the bit body reduces in diameter
for the flow of reduced material backwardly along the bit body and
the bit body may, furthermore, be provided with axial flutes 18 for
the flow of reduced material taken by the bit.
The front working end of body 10 is provided with a plurality of
axial holes 20 in which are mounted rod-like inserts 22 having
domed outer ends 24 which protrude axially outwardly from working
face 14. Inserts 22 may be press fitted in bores 20 or may be
otherwise affixed therein, as by brazing. The inserts 22 are
distributed radially and circumferentially over face 14 and thereby
reduce a formation against which the bit is impacted.
Near the juncture of peripheral wall 16, with forward end 14 of the
bit body, there are provided axially inclined bores 26 in which are
mounted inserts 28 which also have domed outer ends 30. Inserts 28
may be identical with inserts 22 if desired.
It will be seen in the drawings, particularly in FIG. 2, that the
outer ends of inserts 28 not only protrude axially from front end
14 of the bit body, but also protrude radially as well. Inserts 28,
which are distributed about the circumference of the bit body,
thus, serve as gauge inserts and tend to maintain the size of the
hole being drilled by the bit substantially constant.
This is important because, if the bits wear in the circumferential
direction as drilling proceeds, the hole formed by the bit will be
tapered, and it will not be possible to introduce a new bit into
the hole. The gauge inserts, thus, have an extremely important
function to carry out during the operation of the bit.
According to the present invention, the holding of the gauge of a
hole being drilled is enhanced by the provision of at least one
further row of inserts, indicated at 32 and extending radially into
the periphery of bit body 10 within the range of peripheral wall 16
and spaced axially rearwardly from the forward end 14 of the bit
body. The inserts are distributed circumferentially about the body
and, as will be seen in FIG. 3, each gauge insert 28 preferably has
a respective further insert 32 in axial alignment therewith.
Inserts 32 protrude radially from peripheral wall 16 about the same
distance as the gauge inserts 28 although, advantageously, the
radial outer ends of inserts 32 may be set back a distance of up to
about 0.010 inches from the cylindrical envelope in which the
radially outermost regions of inserts 28 are disposed.
Still further, the radially outwardly protruding ends of inserts 32
are preferably formed square, as indicated at 34, and when the
inserts 32 are installed in body 10, the diagonals of the squared
outer ends thereof are arranged vertically and horizontally,
respectively.
Each of the inserts 34 is, thus, formed with axial cutting edges,
one of which faces vertically upwardly and the other of which faces
vertically downwardly. Especially by virtue of the aforementioned
axial cutting edges, the inserts 32 can take part in the cutting
action, particularly where it is necessary to remove material from
the hole being drilled to maintain the gauge.
Still further, in the event that material collapses in the hole
upwardly of the bit, thereby placing an overburden on the bit, at
least the axially upwardly facing sharp cutting edges referred to
assist materially in the extraction of the bit from the hole being
drilled.
As will be seen in FIG. 1, in addition to the row of inserts 32, an
additional row of inserts 38 can be provided protruding radially
from the peripheral wall 16 about the same distance as inserts 32
and also being formed with square ends thereon. This further row of
inserts are circumferentially distributed about the bit body and
preferably are staggered relative to the inserts 32.
The inserts 38, which may be identical with inserts 32 in respect
of size and radial protrusion measured from the axis of the bit
body, the disposition of the diagonals of the squared ends thereof
serve the same function as inserts 32 with respect to assisting in
holding the gauge of the hole being drilled and with respect to
assisting in extracting the bit from overburden which may collapse
thereon.
Where only a single row of the further inserts is provided, it is
advantageous to align the further inserts with the gauge inserts as
shown in FIG. 3 so that the gauge of the hole being drilled will be
accurately maintained for a prolonged period of time.
Modifications may be made within the scope of the appended
claims.
* * * * *