U.S. patent number 3,746,396 [Application Number 05/103,211] was granted by the patent office on 1973-07-17 for cutter bit and method of causing rotation thereof.
This patent grant is currently assigned to Continental Oil Company. Invention is credited to Frederick J. Radd.
United States Patent |
3,746,396 |
Radd |
July 17, 1973 |
CUTTER BIT AND METHOD OF CAUSING ROTATION THEREOF
Abstract
A method and apparatus for turning a cutter bit in a continuous
mining machine by providing one or more projections coupled to the
bit having sufficient length so that when the cutter bit is in
operation, material dislodged by the cutter bit, when falling, will
impact the projections. The impact will generate a torque about the
axis of the cutter bit causing the cutter bit to rotate a few
degrees about the axis. Continual impact of the projections will
provide continuous turning of the bit thereby increasing its useful
life.
Inventors: |
Radd; Frederick J. (Ponca City,
OK) |
Assignee: |
Continental Oil Company (Ponca
City, OK)
|
Family
ID: |
22293973 |
Appl.
No.: |
05/103,211 |
Filed: |
December 31, 1970 |
Current U.S.
Class: |
299/10; 299/110;
299/104 |
Current CPC
Class: |
E21C
35/18 (20130101); E21C 35/19 (20130101) |
Current International
Class: |
E21C
35/19 (20060101); E21C 35/00 (20060101); E21C
35/18 (20060101); E21c 035/18 () |
Field of
Search: |
;299/86,91-93,10-18
;175/354 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Purser; Ernest R.
Claims
What I claim is:
1. In a continuous mining machine, a method for turning a cutter
bit having a cylindrical shaft, a cutter head and one or more
extended projections coupled thereto of a distance as measured from
the axis of said cutter bit at least twice the radius of said
shaft, comprising,
a. passing said cutter bit through material to be mined, thereby
breaking some of said material free above said cutter bit so that
said material falls past said cutter bit;
b. placing said one or more extended projections under at least a
portion of said falling material, whereby said falling material
impacts one or more of said projections causing said bit to
turn.
2. In a cutter bit having a cylindrical shaft, a shoulder formed on
one end of said cylindrical shaft and a cutting head formed to said
shoulder, an improvement to said rotation of said cutter bit
comprising a plurality of spaced projections extending radially
from said shoulder by a distance as measured from the axis of said
cutter bit at least twice the radius of said shaft for imparting a
rotational force about the axis of said shaft by impact to said
projections.
3. A device as described in claim 2, wherein said means coupled to
the cutting head for imparting a rotation comprises a plurality of
rods welded to the cutting head and substantially radial to the
axis of said cutting head.
4. A device as described in claim 2 wherein the length of said rods
radially extend from the cutting head on a radius of 11/2 inches
from the axis of said cutting head.
5. A device as described in claim 2 including a cutter bit holder
having an outer diameter, wherein said plurality of rods extends to
the outer diameter of said cutter bit holder.
6. In combination with a cutter bit for a cutter bit holder said
cutter bit having a shaft and a cutter head axially formed with the
shaft, an improvement comprising means provided on said cutter bit
and extending normal to said cutter bit by a distance as measured
from the the axis of said cutter bit greater than twice the radius
of said shaft in a manner to provide an impact surface whereby
mined material when falling will impact said impact surface causing
rotation of said cutter bit.
7. A device as described in claim 6 wherein said means comprises a
plurality of rods attached to the outer surface of said cutter bit
and extending normal to the outer surface thereof.
8. An impact rotation means for a cutter bit comprising a disc
having an external diameter greater than the external diameter of
said cutter bit, and having an axial opening therethrough, means
for coupling said cutter bit to said disc through said opening, and
impact receiving means formed in said disc in a manner to project
from the surface of said disc.
9. A device as described in claim 8, wherein said means for
coupling said cutter bit to said disc through said opening
comprises welding said disc around said opening to said cutter
bit.
10. A device as described in claim 8, wherein said means for
coupling said cutter bit to said disc through said opening
comprises forming an engaging means in said opening and a mating
engaging means on said cutter bit to prevent relative rotation of
said cutter bit of said impact rotation means.
11. A device as described in claim 8, wherein said impact means
comprises a plurality of raised portions on the surface of said
disc.
12. A device as described in claim 8 wherein said impact means
comprises forming a plurality of pairs of radial slots in said
disc, and bending the portion of said disc between said pairs of
slots at an angle with the surface of said disc.
13. A device as described in claim 8 wherein said impact means
comprises forming a plurality of radial slots in said disc, and
bending portions of said disc adjacent said slot at an angle with
said disc surface.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in the cutter bits used in
continuous mining machines. The invention relates particularly to a
method for providing continuous turning of the cutter bit in order
to even the wear of the cutter bit thereby prolonging its life.
2. Description of the Prior Art
Many attempts have been made in the past in an effort to solve the
uneven wear of cutter bits used in continuous mining machines.
These cutter bits are mounted either in rotating drums along the
periphery of the drum so that the axis of the bit is normal to the
axis of the drum, or on a series of parallel chain-type drives such
that the axis of the bits is always normal to the surface of the
chain. The continuous mining machines cause the bits to move into
the material being mined and tear away said material. If the bits
are stationary only one surface will contact the material
continuously. The single surface will wear excessively causing the
bit to fail in a short period of time by wearing away the metal
supporting the hardened tungsten carbide tip. A typical cutter bit
is disclosed in the U.S. Pat. to A. B. Bower, Jr. No. 3,476,438.
This patent, along with the U.S. Pat. to J. K. Maddock No.
3,361,481 and a French patent to Gerald Wayne Elders 1,483,463, are
illustrative of patents relating to cutter bits used in continuous
mining machines. These patents all are directed toward methods of
continuously rotating the bits by providing rib extensions along
the outer conical surface of the bit so that friction of the rib
against the material being cut will cause rotation of the bit.
SUMMARY OF THE INVENTION
The present invention contemplates a method and apparatus for
rotating a cutter bit not by the use of friction against the
surface being cut, but rather by impact of the bit by falling
material dislodged by the cutter bit.
In order to provide a means for rotating the bit by impact, novel
projections are mounted on the bit and extend radially from the
bit. The projections are of sufficient length so that material
being dislodged above the bit will fall striking the projections.
The forces thus transferred to the projections will cause a torque
about the axis of the cutter bit imparting rotation thereto. Many
types of configurations are possible which will suffice to cause
impact rotation of the cutter bit. The projections can be mounted
directly to the bit by welding or keyed to the bit
mechanically.
It is, therefore, an object of this invention to provide a method
for rotating a cutting bit in an effort to extend the life of the
bit.
It is a further object of this invention to use the forces
generated by falling mined material as a means of developing
sufficient torque to cause continuous turning of a cutter bit in a
mining machine thereby providing even wear of the bit cutting
surface resulting in an extended useful life of the cutter bit.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a side view of the cutter bit illustrating the preferred
impact arms;
FIG. 2 is a front view of FIG. 1;
FIG. 3 is a perspective view of FIGS. 1 and 2;
FIG. 4 illustrates the method of operation of the impact arms;
FIG. 5 is a modified impact arm mounting which is removable from
the cutter bit, with the bit shown in dotted lines;
FIG. 6 is a cross-sectional view of the impact arm ring shown in
FIG. 5;
FIG. 7 is a perspective view of a modified impact arm ring with the
cutter position defined by dotted lines; and
FIGS. 8 through 14 illustrate various modifications of the impact
ring shown in FIGS. 2 through 7.
SPECIFIC DESCRIPTION OF THE FIGURES
Referring to all of the FIGURES, but in particular to FIGS. 1
through 4, a cutter bit generally referred to by the number 20 is
shown. The cutter bit has a shank portion 21 and a conical cutting
portion 22 axially formed with shank 21. A hardened material insert
23 is mounted in conical head 22 so that a portion of insert 23
projects from head 22. Insert 23 is generally made from tungsten
carbide-type materials, and is preformed to a sharpened point to
enhance the cutting of the bit.
A mounting for the cutter bit is generally referred to by number
24, and is shown in dotted lines since it forms no part of this
invention, but is included to illustrate the method for holding the
bit only. The bit normally is anchored or secured in the mounting
24 by means of a pin 25; however, other means are also normally
employed such as a ring having a plurality of dimples positioned to
engage the holes for pins 25 in the mounting. A circumferential
groove 26 is formed behind the head 22, and is generally used to
assist in removing the bit once it becomes worn. A shoulder 27 acts
as a bearing surface for the bit during use.
To a standard bit is mounted a plurality of impact arms 30 which in
the embodiment shown in FIG. 1 are attached to shoulder 27, and
normal to the surface of the shoulder. The impact arms can be
mounted by welding, brazing or any other suitable means or forged
directly during the manufacture of the cutter bit. Impact arms 30
can be made of any suitable material such as iron, steel, or other
metals which can take an impact from falling material without
breaking or bending severely. The length of the impact arms can
vary greatly; however, the efficiency of the impact arms will
increase with their length. For example, referring to FIG. 2, the
radius labeled R which is the distance between the axis of the
shaft 21 and the tip of the impact arm can have a minimum just
slightly larger than the diameter of the shoulder 27 and a maximum
preferred length which does not exceed the diameter of the mounting
24.
The force generated (useful in rotating the shaft 21) is dependent
on the weight of the material impacting arm 30 and the distance or
radius R where the impact occurred on arm 30. Thus, the longer the
arm, the greater the rotational force generated by the falling
material. The maximum length of arms 30, of course, depends on the
diameter of the rod forming the impact arms 30 and the mechanical
strength of the rod. Thus, if the rods were beyond the maximum
diameter of mounting 24, the coal or mined material could bend the
rod back over mounting 24 causing the arms to jam thereby
preventing rotation of the cutter bit. Furthermore, if the arms are
too long, they could be easily bent and their effectiveness reduced
or eliminated. In addition, the length of impact arms 30 is
determined by the closeness of the adjacent cutter bits. The arms
should not interfere with the rotation movement of adjacent cutting
bits. If arms 30 are too short, the material will have little to
impact, thereby reducing the chances of impact and, in addition,
the radius R will be minimum, thereby generating the minimum force
possible. The preferred embodiment uses arms which extend out to
the diameter of mounting 24.
OPERATION
The operation of the arms can be better understood by referring to
FIG. 4. A cutter bit 20 is moving in the direction of the arrow 32.
As it moves, it breaks away material 33a, 33b or 33c. For example,
if 33b should impact arms 30a at point 34, a force will be
generated about the axis of cutter bit 20 in the direction of arrow
35. Mined material 33c will likely impact arms 30c since it is
moving in the direction of arrow 36. If material 33c impacts arms
30c a rotational force will be generated in the direction of arrow
35c. Mined material 33a as it falls will probably impact arm 30a or
one of the two arms 30b or 30d if these arms have moved into a
position under material 33a. From the description of the operation,
it can be observed that the falling material will probably not
cause a complete rotation of cutter 20, but will cause a partial
rotation. However, the random impact of the falling material on the
impact arms will cause a continual rotation of bit 20, resulting in
what amounts to a continuous rotation in both directions, clockwise
and counterclockwise. The continual rotation will cause equal wear
on all sides of the cutter bit cone 22 and equal wear on sharpened
hard insert 23. Since the softer metal on cone 22 will wear away
first, insert 23 will always be exposed as a cutting element. Since
it is rotating, more or less, continuously (regardless of its
direction), the point on insert 23 will remain fairly round. That
is, it will not sharpen to a chisel shape which is likely if the
bit ceases to rotate.
In an embodiment incorporating this invention which was
successfully tested, a bit having a shaft diameter 21 of
fifteen-sixteenths inch and a shoulder diameter 27 of 11/4 inch had
impact arms mounted on the shoulder comprising 1/4 inch diameter
mild steel rods with a radius R of 11/4 inch.
A second embodiment was successfully tested using the same rods 30
as above and the same radius R with the rods mounted in the
circumferential groove 26.
A third embodiment was successfully tested where the rods 30 were
one-fourth inch in diameter, radius R was 11/8 inch and the rods
were bent forward approximately 20.degree. to increase the impact
probability. From the above tests, it was determined that bits
without impact means averaged approximately 64 hours of continuous
use while bits with impact arms made as described above operated
104 hours and were still useable.
MODIFIED IMPACT ARMS
Referring to FIGS. 5 and 6, a modified impact arm is illustrated
and essentially comprises a disc 40 having an axial opening 41 of a
size sufficient to permit the disc to pass over the shank 21 of
cutter 20. A pair of notches 42 is formed in the opening 41 and
engages a raised portion 43 which cooperates with the notch 42 to
prevent turning of disc 40. A plurality of impact arms 44 are
formed extending from disc 40. The impact arms of this embodiment
are bent at an angle .theta. in order to increase the probability
of impact. Obviously, the arms need not necessarily be bent.
However, any configuration which increases the probability of
impact is preferred over other embodiments. A notch 42 is
illustrated in this embodiment. It is well within the skill of the
art to incorporate any method which would prevent ring 40 from
turning on shaft 21. In fact, the ring could be welded to the
shaft. The advantage of the embodiment shown in FIGS. 5 and 6,
however, is that the ring can be used for a plurality of cutter
bits in succession; that is, once a bit becomes unserviceable, the
ring can be removed and placed on a new bit. The ring in this
embodiment is shown mounted behind shoulder 27. It is obvious that
the ring can be mounted over shoulder 27 or in the circumferential
groove 26. Many ways can be devised for attaching the ring to the
cutter bit so that it can be released and reused and yet will not
turn on shaft 21 once the cutter bit is put into service. Four
impact arms are shown in the embodiment of FIG. 6. It is obvious
that many types of impact arms can be used and more than four or
less than four impact arms 44 can be incorporated. If less than
four are used, efficiency of the system may be impaired to some
extent when compared to the performance of a cutter bit having four
impact arms.
ADDITIONAL MODIFICATIONS
The embodiments shown in FIGS. 7 through 14 illustrate some of the
ways the impact arms can be designed or formed in order to
accomplish the purposes of this invention. It should be understood
that the embodiments illustrated in these FIGURES can either be
welded to the cutter bit or mounted releasably to the cutter bit as
illustrated in FIGS. 5 and 6. FIGS. 7 and 8 illustrate impact arms
which have notches 50 cut about the periphery and extensions 51
which may be mounted to the arms 52, or formed with arms 52 by
forging, turning, casting or other well-known manufacturing
methods. The projections 51 can also be formed by merely being bent
up from the arms 52. The impact arms can then be attached to the
cutter bit as previously described.
FIG. 8 illustrates that there can be at least two impact arms or
four impact arms -- two being illustrated by dotted lines. The
impact arms shown in FIGS. 9 and 10 are formed by merely dimpling
or creasing a ring using a hydraulic press or other well-known
means. It is obvious, of course, the impact arms above-described
can also be easily cast. The arms shown in FIG. 11 consist of a
disc 60 having a plurality of projections 61 about the outer
diameter of disc 60. The impact ring shown here can easily be
formed by molding, forging, turning or any other well-known
system.
The impact arms shown in FIG. 14 are similar to that shown in FIG.
11 except the projections are radial and formed in the surface of a
disc 60. The impact arms shown in FIGS. 12 and 13 are obviously
formed by cutting disc 60 and bending up radial portions to form
impact arms. It is obvious that many conceivable impact arms can be
constructed which operate on the basic principle that falling
material will cause a rotational force to be applied to a cutter
bit if the material strikes a projection attached to the cutter
bit. The main criteria for rotating the bit essentially consists in
providing projections from the cutter bit surface having sufficient
length not only to cause a sufficient rotating force being imparted
to the cutter shaft when the arms are impacted by falling material,
but also having the arms sufficiently placed and oriented and in
sufficient number so that there is a high likelihood that falling
material will strike the arms.
These and other features of this invention will become apparent
when reference is made to the drawings and the accompanying
specification and claims.
* * * * *