U.S. patent number 3,870,370 [Application Number 05/353,539] was granted by the patent office on 1975-03-11 for universal saddle mounting for fixed and rolling cutters.
This patent grant is currently assigned to Dresser Industries, Inc.. Invention is credited to Norman D. Dyer, Douglas F. Winberg.
United States Patent |
3,870,370 |
Winberg , et al. |
March 11, 1975 |
UNIVERSAL SADDLE MOUNTING FOR FIXED AND ROLLING CUTTERS
Abstract
The present invention relates to non-rolling or fixed cutter
assemblies and supports for such assemblies for use on tunneling
machines, raise drilling machines and other types of earth boring
equipment. In particular the invention relates to cutter supports
adapted for removably mounting either rolling or fixed cutter
assemblies and to fixed cutter assemblies adapted for mounting in
the supports. A fixed cutter assembly and support according to the
invention comprises fixing means, including a fixing surface
integral with the cutting element of the cutter assembly, for
releasably fixing the cutting element against rotation relative to
the support.
Inventors: |
Winberg; Douglas F. (Issaquah,
WA), Dyer; Norman D. (Beaumont, TX) |
Assignee: |
Dresser Industries, Inc.
(Dallas, TX)
|
Family
ID: |
23389561 |
Appl.
No.: |
05/353,539 |
Filed: |
April 23, 1973 |
Current U.S.
Class: |
299/106; 175/87;
175/413; 175/364; 37/455 |
Current CPC
Class: |
E21B
10/10 (20130101); E21B 10/14 (20130101); E21B
10/62 (20130101); E21B 10/20 (20130101) |
Current International
Class: |
E21B
10/00 (20060101); E21B 10/10 (20060101); E21B
10/20 (20060101); E21B 10/14 (20060101); E21B
10/62 (20060101); E21B 10/08 (20060101); E21b
009/08 (); E01g 003/04 () |
Field of
Search: |
;299/80,86,91-93
;175/383,413,364,355,87 ;37/142R,142A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Purser; Ernest R.
Attorney, Agent or Firm: Browning & Bushman
Claims
We claim:
1. A rolling cutter assembly support and fixed cutter assembly
combination comprising: a rolling cutter assembly support having a
base portion adapted to be secured to a bit body, holding means on
said support spaced from said base portion engageable with a
non-rotating part of a rolling cutter assembly to rotatably support
a cutting element of said rolling cutter assembly; and a
non-rotating cutter assembly having a mounting part compatible with
and mounted on said holding means and also having a cutting
structure projecting from said holding means in a direction away
from said base portion; a fixed surface on said cutter support and
a fixing surface on said non-rotating cutter assembly engageable
with said fixed surface to prevent said cutting structure from
rotating relative to said support.
2. A non-rolling cutter assembly adapted to be mounted on a rolling
cutter assembly support for use on a bit body, said non-rolling
cutter assembly comprising: a cutting element having a longitudinal
centerline therethrough and a cutting structure extending generally
outwardly away from said centerline; pivot means carried on said
cutting element; a fixing surface integrally connected to said
cutting element and radially outwardly spaced from the axis of said
pivot means, said fixing surface being adapted to engage a fixed
surface separate from said non-rolling cutter assembly to limit
pivotal movement of said cutting element about the pivot means; and
a first bearing end at one end of said cutting element.
3. A non-rolling cutter assembly according to claim 2 including a
second bearing end at the other end of said cutting element, said
bearing ends being rigidly attached to said cutting element.
4. A non-rolling cutter assembly according to claim 3 having a
longitudinal passageway therethrough extending through said bearing
ends parallel to said axis but eccentric with respect to said
centerline, and wherein said pivot means comprises a pin extending
through said passageway.
5. A non-rolling cutter assembly according to claim 3 wherein said
bearing ends are integral with and located at opposite ends of a
bearing shaft extending longitudinally through said cutting
element, said cutting element being rigidly attached to but
removable from said bearing shaft.
6. A non-rolling cutter assembly according to claim 2 wherein said
cutting structure includes a plurality of replaceable cutting
picks.
7. A non-rolling cutter assembly according to claim 2 including a
second bearing end at the other end of said cutter element, a
bearing shaft integrally connecting said bearing ends, said cutting
element being rotatably mounted on said shaft, said cutting element
further having a hole therein for receipt of a torque reaction
bar.
8. A non-rolling cutter assembly according to claim 7 where said
bearing shaft has a longitudinal passageway therethrough generally
parallel to said centerline but eccentric with respect to said
centerline, and wherein said bearing shaft is concentric with said
centerline, said cutter assembly further comprising a pin extending
through said passageway.
9. A non-rolling cutter assembly according to claim 7 wherein said
cutting element includes a plurality of such cutting structures
circumferentially spaced from one another, and wherein said cutting
element has a plurality of such holes therein corresponding to the
number of cutting structures.
10. A non-rolling cutter assembly according to claim 7 wherein said
hole extends through said cutting element in a direction generally
parallel to said centerline and is spaced radially outwardly from
said bearing ends.
11. A non-rolling cutter assembly according to claim 7 wherein said
cutting structure includes a plurality of replaceable cutting
picks.
12. A rolling cutter assembly support having a non-rolling cutter
assembly removably mounted therein, said support comprising: a pair
of spaced apart support arms each having an inner surface, said
inner surfaces facing each other and being generally parallel, said
arms further comprising holding means supporting said non-rolling
cutter assembly at a given location along said arms, said holding
means also being engageable with a non-rotating part of a rolling
cutter assembly to rotatably support a cutting element of said
rolling cutter assembly; base means rigidly adjoining respective
aligned ends of said arms and adapted for rigidly attaching said
arms to a drill bit in fixed position relative to each other; and
means for releasably fixing a cutting element of said non-rolling
cutter assembly against rotation relative to said support.
13. The apparatus of claim 12 wherein said non-rolling cutter
assembly has a longitudinal centerline extending between said
support arms, a pair of bearing ends each engaged by the holding
means on one of said arms, and said cutting element of said
non-rolling cutter assembly is located between said bearing ends
and includes a cutting structure extending outwardly away from said
centerline, and wherein at least one of said support arms and its
engaged bearing end have end locking means for limiting relative
rotation therebetween.
14. The apparatus of claim 13 wherein said bearing ends are
integrally attached to said cutting element of said non-rolling
cutter assembly and wherein said end locking means also serve as
said fixing means.
15. The apparatus of claim 14 wherein said bearing ends are
integral with and located at opposite ends of a bearing shaft
extending longitudinally through said cutting element of said
non-rolling cutter assembly, said cutting element of said
non-rolling cutter assembly being integrally attached to, but
removable from, said bearing shaft.
16. The apparatus of claim 13 wherein said bearing ends are
integral with and located at opposite ends of a shaft extending
longitudinally through said cutting element of said non-rolling
cutter assembly, said cutting element of said non-rolling cutter
assembly being rotatable about said shaft.
17. The apparatus of claim 16 wherein said cutting element of said
non-rolling cutter assembly includes a plurality of
circumferentially spaced cutting structures and is rotatable into a
plurality of positions in said cutter support, each of said
positions orienting one of said cutting structures so that it
extends generally outwardly from said support in a cutting
position, the apparatus further including a plurality of such
fixing means for fixing said cutting element of said non-rolling
cutter assembly in each of said positions.
18. The apparatus of claim 16 wherein the fixing means comprises a
torque reaction bar, wherein said support has a hole therein for
receipt of said torque reaction bar, said cutting element of said
non-rolling cutter assembly also having a hole therein for receipt
of said torque reaction bar, said apparatus further comprising
means for preventing endwise movement of said torque reaction
bar.
19. The apparatus of claim 13 wherein said non-rolling cutter
assembly has a longitudinal passageway therethrough extending
through said bearing ends, said bearing ends being concentric with
said centerline and said passageway being eccentric with respect to
said centerline, wherein each of said support arms has a groove on
its inner surface partially surrounding its engaged bearing end,
each of said arms further having a bore therethrough of
substantially the same diameter as the passageway through the
cutter assembly, said bore being substantially parallel to the
cutter assembly centerline and being eccentric with respect to a
center of said groove, wherein said bores are axially aligned with
each other, and wherein said apparatus further includes a pin
extending through said bores and said passageway such that a force
tending to rotate said bearing ends with respect to said support
arms will cause them to become eccentrically locked on said grooves
against such rotation, and means preventing endwise movement of
said pin.
20. The apparatus of claim 19 wherein said cutting structure is
oriented at an angle such that the load on the cutting structure
during drilling tends to eccentrically lock said bearing ends
against rotation relative to said support.
21. A rolling cutter assembly support comprising: a pair of support
arms each having an inner surface, said inner surfaces facing each
other and being generally parallel, said arms further comprising
holding means for supporting a non-rolling cutter assembly to be
mounted in said support at a given location along said arms, said
holding means also being engageable with a non-rotating part of a
rolling cutter assembly to rotatably support a cutting element of
said rolling cutter assembly; base means rigidly adjoining
respective aligned ends of said arms and adapted for rigidly
attaching said arms to a drill bit in fixed position relative to
each other; and a releasable fixing member adapted for fixing said
cutter support to a cutting element of a non-rolling cutter
assembly to be mounted in said support.
22. The support of claim 21 having a hole therein and wherein said
fixing member comprises a torque reaction bar insertable into said
hole said support further comprising means for preventing endwise
movement of said torque reaction bar.
23. The support of claim 22 wherein both of said arms have such
holes extending therethrough, said holes being axially aligned and
extending in the general direction of said connecting member and
said torque reaction bar being sized to extend through both of said
holes.
24. The support of claim 21 including a connecting portion integral
with said base means and rigidly connecting said respective aligned
ends of said arms.
Description
BACKGROUND OF THE INVENTION
In mining, construction, and other industries involving earth
boring operations, the use of heavy duty machines for boring earth
and rock formation has become increasingly popular and has, to a
great extent, replaced hand mining. The present invention relates
to such machines and especially to those for drilling large
diameter holes. Such holes, if substantially horizontal, are
referred to as tunnels, and if substantially vertical, are often
referred to as raises or winzes.
Machines of this type generally comprise a large rotary bit or
cutterhead which is rotated and simultaneously pulled or pushed
through the formation by the machine. Mounted on the bit facing the
formation to be bored are a plurality of cutters. These cutters may
be of two basic types: rolling cutters and fixed cutters. Rolling
cutters are mounted for rotation about shafts which extend
generally radially from the axis of the cutterhead so that when the
cutterhead is rotated, the cutters will roll against the rock or
earth formation to be bored. Fixed cutters do not move relative to
the cutterhead and operate like blades which are dragged or scraped
against and into the formation as the bit rotates. The type of
cutters to be used in any particular case is determined by factors
such as the nature of the hole to be drilled, the make-up of the
formation, etc. In tunnel boring, for example, it is often
desirable to use a mixture of fixed and rolling cutters on the same
bit. However, as the drilling progresses different types of
formation may be encountered rendering the types of cutters and
their arrangement on the bit less effective.
U.S. Pat. Nos. 2,811,341 and 3,139,148 show cutterheads of
tunneling machines having both rolling and single blade fixed
cutters mounted thereon. U.S. Pat. No. 3,203,492 shows a drill bit
having rolling type cutter assemblies adapted for mounting on a
type of support often referred to as a "saddle."
The supports or saddles shown and described in U.S. Pat. No.
3,203,492 comprise a pair of generally parallel arms connected at
respective aligned ends by a rigid connecting portion to form with
the inner surfaces of the arms a generally U-shaped surface.
Rigidly adjoining the connecting portion opposite the U-shaped
surface is a base portion adapted for mounting on a drill bit. The
rolling cutter assembly used with this type of support includes a
wheel-like or roller-like cutting element which rotates about a
shaft. The ends of the shaft protrude from the ends of the cutting
wheel to engage holding means on the inner surfaces of the support
arms so that the cutter assembly is supported for rotation between
the arms at a given location therealong. The support arms and the
ends of the cutter assembly shaft also include end locking means
for limiting relative rotation therebetwen. The cutter supports
become a relatively permanent part of the bit, while the rolling
cutter assemblies are easiy removable for replacement or
repair.
SUMMARY OF THE INVENTION
The present invention relates to fixed cutter assemblies adapted to
be mounted in supports which can alternatively mount rolling
cutters.
The fixed cutter assemblies of the present invention each comprise
a cutting element having a longitudial centerline. The cutting
element includes at least one cutting structure extending generally
outwardly away from the centerline. The cutter assembly further
includes at least one bearing end and preferably a pair of bearing
ends located at opposite ends of the cutting element. These bearing
ends are analogous to the ends of the shaft in a rolling cutter
assembly and can be engaged by the holding means on the support
which ordinarily hold the shaft ends of the rolling cutter. The
cutter assembly has a fixing or rotation limiting surface rigidly
carried on the cutting element. When the cutter assembly is placed
in the support, the fixing surface is engageable with a fixed
surface on the support. Together, the fixing surface and engaged
fixed surface of the support form fixing means to fix the cutting
element against rotation relative to the support. In some
embodiments of the invention, the support must be modified to
provide for the fixing means. Such modification however does not
effect its ability to mount rolling cutter assemblies
interchangeably with the fixed cutter assemblies. The bearing ends
of the fixed cutter assembly preferably include means similar to
those on the shaft ends of the rolling cutter which lock with
mating means on the support to prevent relative rotation between
the bearing ends and the support arms.
The present invention also encompases a fixed cutter assembly whose
cutting element includes a plurality of circumferentially spaced
cutting structures and means by which any desired one of these
cutting structures can be fixed in cutting position. The invention
also includes forms in which the entire cutting element and/or
portions of its cutting structure are replaceable. Additionally,
the entire cutter assembly can be quickly and easily removed from
the support and replaced by another assembly.
It will be readily appreciated that in accord with the present
invention fixed cutter assemblies are provided for mounting in
supports which can also mount rolling cutter assemblies
interchangeably with the fixed cutter assemblies. This considerably
increases the usefulness of a given bit as it can be adapted for
many different rock and earth formations. Thus, the bit can be
adapted for different jobs or for different formations which may be
encountered as a long hole is being drilled. When fixed cutter
assemblies are used, the bit is made further adaptable for
different drilling conditions since cutting structures of different
configurations can be provided by re-positioning the cutting
element, replacing the cutting element, or replacing the entire
assembly in the support.
Further advantages are afforded by the fact that the fixed cutter
assembly is removable from the support and part or all of the
cutting element is replaceable. This makes for minimum repair or
replacement costs when part or all of a cutter assembly becomes
worn or damaged.
It is thus a principal object of the present invention to provide a
fixed cutter assembly removably mountable in a support.
Another object of the invention is to provide a cutter support and
both fixed and rolling cutter assemblies adapted for mounting
therein.
One more object of the invention is to provide a fixed cutter
assembly having a plurality of cutting structures, any one of which
can be fixed in cutting position in a support.
Still another object of the invention is to provide a fixed cutter
assembly having replaceable cutting structure.
Other objects and advantages of the invention will be made apparent
by the following detailed description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view partly in section and partly in elevation, with
parts broken away, showing one form of fixed cutter assembly
mounted in its support.
FIG. 2 is a view taken along lines 2--2 in FIG. 1.
FIG. 3 is an elevational view of the inner surface of the support
arm of FIG. 2.
FIG. 4 is a view partly in section and partly in elevation of
another form of cutter assembly mounted in its support.
FIG. 5 is a cross sectional view taken along lines 5-- 5 in FIG.
4.
FIG. 6 is a view partly in section and partly in elevation of a
third form of cutter assembly mounted in the support of FIG. 4.
FIG. 7 is a cross sectional view taken along lines -- 7 in FIG.
6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For purposes of illustration, the present invention will be
described as it pertains to the saddle type cutter supports shown
in U.S. Pat. No. 3,203,492. However it will be readily appreciated
that the invention can be applied to any type of support for
mounting roller cutters. To the extent to which it relates to the
present invention, the disclosure of U.S. Pat. No. 3,203,492 is
hereby expressly incorporated herein by reference.
FIGS. 1- 3 depict one embodiment of the invention in which a
support similar to those shown in U.S. Pat. No. 3,203,492 is
slightly modified to accommodate a fixed cutter assembly but
without altering its ability to accommodate a rolling cutter
assembly interchangeably with the fixed cutter assembly.
Referring to FIG. 1, the fixed cutter assembly 10 is shown mounted
in the support l2. The support 12 comprises a pair of substantially
parallel arms 14, 16 having respective inner surfaces 18, 20 facing
each other. The arms 14 and 16 are connected at their lower ends by
a connecting portion 22 which forms, with the inner arm surfaces 18
and 20, a U-shaped surface 24. the support also includes a base
portion 26 integral with connecting portion 22 and opposite the
U-shaped surface 24. In use the base portion 26 is rigidly attached
to a drill bit or cutterhead (not shown) as by welding or
bolting.
The arms 14, 16 have respective axially aligned bores 28, 30
extending therethrough near their upper ends. Arms 14, 16 also have
respective axially aligned holes 32, 34 extending therethrough.
Holes 32, 34 are located between the connecting portion 22 and the
bores 28, 30, and each of the bores 28, 30 and holes 32, 34 extends
in the same general direction as the connecting portion 22.
The inner surfaces 18 and 20 of arms 14 and 16 have respective
dovetail grooves 36, 38 which serve as holding means to receive the
bearing ends 40, 42 of the fixed cutter assembly 10 and threby
support the cutter assembly at a given location along arms 14, 16
and therebetween as shown.
The bearing ends 40 and 42 form the ends of a shaft 44 which
extends through a longitudinal bore in the cutting element 46. The
cutting element 46 seats against a shoulder 48 on the shaft 44 so
that the bearing ends 40 and 42 protrude from the ends of the
cutting element. In order to retain the bearing ends 40,42 in the
grooves 36, 38, a main pin 64 is inserted in bores 28, 30 and
through an aligned longitudinal passageway 66 in the shaft 44. Thus
the cutter assembly 10 is held in the support 12 no matter which
way the support may be turned. Main pin 64 is held against endwise
movement by a roll pin 68 extending transversely through main pin
64 and arm 14. The shaft 44 serves as a pivot means for the cutting
element 46, which is rotatable about the shaft. The cutting element
46 has a longitudinal centerline c therethrough and includes two
cutting structures extending generally outwardly away from
centerline c. It should be noted that the term "centerline" is used
herein to denote a line extending through the centers of the
bearing ends and does not necessarily denote a true center of the
cutter assembly as a whole. The cutting structure which is shown in
operating position in FIGS. 1 and 2 is comprised of a wing 50 and
four cutting picks 52. The wing 50 extends generally outwardly from
centerline c away from connecting portion 22 at a suitable angle.
The picks 52 extend outwardly from the wing 50 at an angle of
approximately 90.degree. thereto. Of course, the exact angle is a
matter of individual design. The picks 52 may be pressed into wing
50 or otherwise secured so that they can be removed and replaced
when worn. Or they may be formed integrally with wing 50. Wing 50
has a hole 54 therethrough extending in a direction substantially
parallel to the centerline c. The other cutting structure is
comprised of the three harrow-tooth type blades 56 located
generally opposite the first cutting structure. Blades 56 also have
aligned holes 58 therethrough substantially parallel to the axis
c.
When the first cutting structure is in operating position as shown,
the holes 58 are aligned with the holes 32 and 34 in the support
arms 14 and 16. A torque reaction bar 60 is inserted through holes
32, 58, and 34 and is held against endwise movement by a roll pin
62 extending transversely through bar 60 and arm 14. The surfaces
of the holes 58 serve as fixing surfaces and cooperate with the
torque reaction bar 60 to form fixing means which prevent rotation
of the cutting element 46 about the shaft 44 and keep the first
cutting structure in operating position. Similarly, when the second
cutting structure is used, the hole 54 is aligned with holes 32, 34
in the arms, and the torque reaction bar 60 is inserted through
holes 32, 54, and 34 to keep the cutting element in position.
It will readily be appreciated that many modifications of the
cutting element are possible. For example, the cutting element
shown has cutting structures of two different types so that the
assembly can be quickly and easily adapted for different drilling
conditions. However, the cutting structures could be made identical
so that when one is worn, the other can be placed in operating
position. The types of cutting structures could also be varied and
any other cutting structure could be employed.
The number of cutting structures on the cutting element could also
be varied to include more than two. Or a cutting element might be
provided with only one cutting structure. In the latter case, a
suitable projection located generally opposite the cutting
structure could be provided and this projection could have a hole
therethrough aligned with holes 32, 34 for receipt of the torque
reaction bar.
It will also be recognized that, because the cutting element is
removable from the shaft, it can be replaced when worn or damaged
or when a different type cutting structure is needed without the
need for replacing the entire assembly.
In preferred forms of the invention the bearing ends 40, 42 and the
respective support arms 14, 16 have end locking means for
preventing relative rotational movement. While any suitable type of
end locking means could be employed, the type illustrated in FIGS.
2 and 3, known as an eccentric lock, is highly effective. As best
seen in FIG. 3, the bottom of the groove 38 in arm 16 is arcuate,
having a center g which will be referred to as the center of groove
38. The sides of the groove are straight and extend from the
opposite ends of the arcuate portion in the same direction and
substantially parallel to each other. The bore 30 has a center b
which is offset from the center g in a direction generally normal
to the sides. The bore 28 in arm 14 is similarly offset from the
center of the bottom arc of groove 36 so as to be aligned with bore
30. Referring now to FIG. 2, it will be seen that the centerline c
lies along the center of the shaft 44. The center p of the
passageway 66 is offset from centerline c just as center b is
offset from center g. When the cutter assembly is placed in the
support, the shaft 44 is turned until passageway 66 is aligned with
bores 28 and 30. Then the main pin 64 is inserted through the bores
28 and 30 and the passageway 66. When a load is placed on the
cutting structure in operation, a torque is transmitted to the
shaft 44. Because of the presence of the main pin 64, the shaft 44
tends to rotate about an axis through center p rather than about
its own centerline c. Thus the edges of the bearing ends 40, 42 are
eccentrically locked against the surfaces of the grooves 36,
38.
FIGS. 4- 7 show two other forms of the invention. In each of these
two forms the cutting element is integrally connected to the
bearing ends so that the main pin serves as the pivot means for the
cutting element. Because the bearing ends and cutting element are
integral in these forms, the end locking means on the bearing ends
and support arms also serve as the fixing means which fix the
cutting element against rotation relative to the support. Each of
the two forms of FIGS. 4- 7 employs the eccentric type lock and the
fixing surfaces are comprised of the edges of the bearing ends.
However, it will be appreciated that the same principle may be
applied to any other type of end locking means.
In particular, FIGS. 4 and 5 show a form in which the cutting
element 70 and bearing ends 72, 74 are formed in one integral piece
except for the picks 76 which can be removed and replaced. Cutting
structures other than the pick type shown could also be used. The
cutting element 70 and the bearing ends 72, 74 have a longitudinal
passageway 78 therethrough whose center p.sub.1 is offset from the
centerline c.sub.1 of the cutting element. centerline c.sub.1
passes through the centers of the bearing ends 72, 74.
The support 80 is substantially identical to the suspport 12 of
FIGS. 1- 3 except that it does not have holes such as 32 and 34.
Support 80 comprises arms 82 and 84, connecting portion 86 and base
portion 88. The arms 82 and 84 have respective dovetail grooves 90
and 92 on their inner surfaces which serve as holding means to
engage the bearing ends 72 and 74. The lower portions of grooves 90
and 92 are arcuate and have axially aligned centers (not shown).
Axially aligned bores 94, 96 extend through the arms 82, 84 in the
area of the dovetail grooves 90, 92 and have centers (also not
shown) which are offset from the centers of the arcuate portions of
the grooves.
In mounting the cutter assembly in the support, the bearing ends
72, 74 are seated in the grooves 90, 92 and the cutting element is
rotated until passageway 78 is aligned with bores 94 and 96. A main
pin 98 is then inserted through the bores 94 and 96 and the
passageway 78 and retained against endwise movement by roll pin 100
which passes transversely through main pin 98 and support arm 82.
When the cutting structure is loaded in operation a torque is
placed on the cutting element 70 and it rotates a few degrees about
the main pin 98 until the edges of the bearing ends 72 and 74
become eccentrically locked against their respective grooves 90 and
92 in the support arms. It will be understood that the cutting
structure is oriented so that it will be in proper position for
drilling when the cutting element is in its locked position.
The embodiment of FIGS. 6 and 7 is similar to that of FIGS. 4 and
5. However in the embodiment of FIGS. 6 and 7 the bearing ends 102,
104 are integral with a shaft 106 which extends through the annular
cutting element 108. The cutting element 108 seats against a
shoulder 110 of the shaft 106 and is integrally connected to the
shaft by press fitting, heat shrinking, welding, or other suitable
means. Thus it can be cut away or otherwise removed and replaced
when worn. The cutting structure as shown is comprised of harrow
tooth blades 112, but of course any desired cutting structure can
be used.
The cutting element 108 has an axis c.sub.2 passing through the
centers of the bearing ends 102 and 104, and the shaft 106 has a
longitudinal passageway 114 therethrough whose axis p.sub.2 is
offset from centerline c.sub.2.
The support 80 is identical with that of FIGS. 4 and 5. Thus
bearing ends 102 and 104 can be seated in the grooves 90 and 92 and
passageway 114 can then be aligned with the bores 94 and 96. The
main pin 116 can then be inserted through bores 94 and 96 and
passageway 114 and retained by roll pin 118. Eccentric locking of
the bearing ends in the grooves and resultant fixing of the cutting
element against rotation is effected by the load on the cutting
structure in the same manner as in the embodiment of FIGS. 4 and 5
above.
* * * * *