Note: Descriptions are shown in the official language in which they were submitted.
923
IMPROVED CUTTER WHEEL FOR TILLAGE APPARATUS
The present invention relates generally to a tillage appara-
tus, and more specifically to a tillage apparatus having an
improved cutter wheel.
Background of the Invention
Conventional tillage implements such as the disk harrow,
disk cultivator and rotating hoe are not completely suitable for
preparing ground for seeding where legumes are to be grown in
established grass sod.
In order to provide a tillage apparatus better suited for
preparing ground for seeding or grassland renovation where sod is
present, towed implements having a series of cutting wheels
driven to open a furrow have b~en developed. Devices of this
type are shown, for example, in U. S. Patent Nos. 4,023,510;
~,043,281; 4,043,404; and 4,051,792. This type of tillage imple-
ment is particularly useful where legumes are to be grown in
- established grass sod, especially since the ground surface is
often uneven or rocky and may have grass swards of differing
thicknesses thereon. The implement is also useful for inter-
seeding grasses such as rye and wheat into Bermuda grass.
Cutting of the sward and sod mat and provision of a furrow
therein has been a continuing problem. Although cutter wheels
for the tillage implements have been known and suggested, such
wheels have not been completely satisfactory. Wearing of the
cutter wheels is a common problem because the wheels are driven
in the soil. Additionally the rough, rocky terrain often encoun-
tered adds to the problem of wear and breakage.
Summary of the Invention
:
This invention provides an improved cutter wheel for use
; 30 with a tillage implement.
As a part of the improved structure, a cutter wheel is
formed from a disk which receives a plurality of inserts, each
~k
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923
1 having a hard bullet-shaped tip secured thereon and defining a
cutting tooth. In addition, in the preferred embodiment, each
insert is backed by a portion of the disk, and the tip is attached
to the insert so that it is loaded primarily in compression. The
disk is shaped to protect the tip from breaking off when obs-tacles
are encountered.
It is, therefore, an object of the present invention to
provide an improved cutter wheel.
It is a further object of this invention to provide an
improved cutter wheel for a tillage apparatus for sod seeding
purposes.
It is another object of this invention to provide an improved
cutter wheel which has an increased lifetime.
It is still another object of the present invention to
provide an improved cutter wheel for receiving a plurality of
hardened tips thereon, each tip defining a cutting tooth.
It is a further object of the invention to provide a cutter
wheel having a tungsten carbide tip secured thereon so that the
area of the connection is loaded primarily in compression to
prevent breaking off of the tip.
These and other objects, features and advantages of the
present invention will become obvious from the description which
follows taken in conjunction with the accompanying drawings, in
which:
Fig. 1 is a perspective view of the tillage apparatus
having the improved cutter wheel mounted thereon;
Fig. 2 is a perspective view of a portion of the tillage
apparatus shown in Fig. 1 to illustrate the cutter wheel on a
mounting unit;
Fig. 3 is a perspective view of the drive structure for
a cutter wheel showing the friction drive and threaded driveshaft
upon which the cutter wheel is mounted;
~ -,
,:','~1,
1 Fig. 4 is a side elevation view of the preferred embodiment
of the cutter wheel; and
Fig. 5 is an end view of the cutter wheel shown in ~ig. 4.
Description of the Preferred Embodiment
As shown in Fig. 1, a tillage apparatus 10 carries the
improved cutter wheel 12 of the present invention. The tillage
apparatus 10 includes a frame member 14 which has gauge wheels 16
mounted thereon. Also mounted on the frame 14 is a seed box 18.
Seed tubes 20 lead from seed gates below the box 18 to seed boot
assemblies 22. ~railing each seed boot assembly 22 is a packex
wheel member 24 carried by arms 26. The apparatus 10 is connec-
ted to a tractor 28 or similar vehicle by a conventional three-
point hitch 30.
As shown in Fig. 2, the cutter wheels 12 are mounted in a
double-row configuration shown generally at 32. A drive shaft 34
is supported by a casing 36 pivotally connected to a transverse
pivot rod (not shown~ near the front of the frame member 14. The
drive shaft 34 is rotated by a drive chain and sprocket located
within casing 36. The chain and sprocket are powered in a con-
ventional manner through shafts and a gear box from the tractorpower take-off. A friction hub 38 (Fig. 3) is preferably mounted
on shaft 34 for rotation therewith. A nut 40 threaded on threaded
end 42 secures the cutter wheel 12 between a disk 44 and the
friction hub 38 for rotation with the shaft 34.
Each double-row assembly 32 is biased downwardly by down-
pressure springs 46. Depth skids 48 maintain the cutter wheels
12 at the proper cutting depth and are adjustable up or down to
set the depth for various seed and soil conditions.
A more detailed discussion of the foregoing structure may be
found for example in U. S. Patent Nos. 4,043,404, 4,043,281 and
4,023,510, as well as in the patents mentioned therein. An
alternate skid arrangement is shown in U. S. Patent No. 4,051,792.
439Z3
1 However, the structure is utilized merely to orient the cutter
wheel of this invention with respect to a tillage apparatus.
The cutter wheel 12, as best seen in Figs. 4 and 5, includes
a disk-like maln body portion 50 with a central shaft receiving
aperture 52. The body portion 50 includes a plurality of insert
receiving slots 54 equally spaced about the periphery. Each slot
is defined by a rear wall 56 facing generally in the direction of
rotation, an opposed forward wall 58, and a generally flat bottom
section 60. The bottom section 60 is generally perpendicular to
a line extending radially from the center of the body through the
midpoint of section 60.
Between consecutive slots 54 are arcuate sections 62, each
preferably with an identical radius of curvature R but each
having a different center of radius of curvature 64. The centers
are generally equispaced about aperture 52, as best seen in Fig.
4. The peripheral configuration provides the slots 54 with rear
walls 56 of greater dimension than forward walls 58. Tn the
preferred embodiment, six slots 54 are provided equally spaced
about the periphery.
Each slot 54 receives a cutter-tip assembly 66 made up of an
insert 68 and a cutting tip 70. The lower portion of the insert
68 generally conforms to the shape of the slot 54 for receipt
thereby. The rear portion 72 of the insert is generally equal in
dimension to the rear wall 56. The front portion 74 of the
insert is greater in dimension than forward wall 58 and includes
a tip-receiving face 76 disposed slightly at an angle rearwardly
from the plane of the front portion 74. Cutting tip 70, prefer-
ably bullet-or cone-shaped and fashioned from a hard material
such as tungsten carbide, is brazed or silver soldered to the
face 76. The cutter-tip assembly 66 is positioned in the slot 54
and secured to the main body portion 50, for example, by welding
the insert 68 near the bottom and walls of the slot as indicated
at 78.
~i~1339Z3
1 When the assembly 6G is connected to the body portion 50,
the top 80 of the insert 68 îs generally aligned with the preced-
ing arcuate section 62 and extends that contour in a straight
line to the tip-receiving face 76. The point of the tip 70
extends forwardly in the dir~ction of rotation beyond the plane
of the front portion 7~ and above the counterclockwise-most
portion of the next arcuate section 62. As evident from Fig. 4,
the shape of the disk 50 allows cutting clearance for the tip 70
while providin~ substantial back support for the insert 68 along
the rear wall 56 of the slot 54. The above disk and insert
configuration provides better protection for the tips 70 against
obstacles than a conventional deep gullet configuration. Vsing
deep gullets, the tips 70 were found to break off more easily
than in the above configuration wherein the outer diameter of the
disk 50 tends to hit the obstacle before the tip contacts it.
The angle of face 76 and the general axial orientation of
tip 70 indicated by line 82 are chosen so that the brazed or
soldered connection between the insert 68 and the tip is loaded
primarily in compression to reduce the possibility of breaking
the connection. In the preferred embodiment, the angle x between
the axis of tip 70 and line extending radially from the center of
- disk 50 through the point of the tip is considerably greater than
0 but less than 90. If angle is too small, the tip 70 will
be torqued radially outwardly as it contacts the soil. On the
other hand, if is too large, the apex of the tip 70 will be
urged radially inwardly upon soil contact.
As seen in Fig. 5, the width of the base of tip 70 is
approximately equal to the width of insert 68. Tip 70 can have
various shapes, such as conical, pyramidal, or wedge, and prefer-
~ 30 ably terminates in an apex extending generally in the directionof rotation. A satisfactory furrow can be cut using a tip base
width of approximately 5/8 inch. The disk 50 is formed from a
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1 thin sheet of metal, typically 0.25 inch, and each cutter-tip
assembly 66 is located in its corresponding slot 5A so that its
sides extend an equal distance beyond the sides of the disk.
Alternatively, the inserts can be offset with respect to the disk
and each other to increase the width of the furrow cut by cutter
wheel 12 for a given width of tip 70. The inserts 68 can be made
wider or narrower than the tip width as long as they provide
adequate support for the tip. ~f the inserts are wider, the
relatively soft material quickly wears and tapers to conform to
the width of hardened tip 70. In another embodiment, the disk 50
can ~e formed directly with tip-receiving portions to eliminate
the inserts 68. The entire wheel can be cast or fashioned from
sheet metal and the tips 70 connected at the proper angle on the
tip-receiving portions by a suitable method such as soldering or
brazing.
In a working embodiment of the present invention, a 12 inch
cutter wheel is provided with each arcuate section 62 having a
radius of curvature R equal to about 5 1/4 inches. The center of
each radius R is located on the periphery defining a l-inch
aperture 64. Each insert 68 is about 5/8 inch wide and is welded
to a 1/4 inch wide disk 50. Six inserts are equally spaced about
the periphery of the disk. Each tip-receiving face 76 is angled
back at approximately 25 from the front portion 74 of the insert
68. A bullet-shaped tungsten carbide tip 70 is brazed to each
face 76 with the angle ~ ~eing approximately 53. With the above
configuration, the tip connections are loaded primarily in com-
pression as the cutter wheel cuts a furrow. When an obstacle
such as a rock is encountered, it is contacted by the unique
outer periphery of the disk 50 before the tip 70 reaches it, thus
protecting the tip. The incidence of tip breakage is greatly
reduced by using the above configuration rather than, for example,
providing a deep gullet forwardly of the tip.
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23
1 In operation, the cutter wheels are lowered to contact the
ground and are rotated at a relatively high speed, preferably
about 630 rpm. The tips 70 dig into the ground to cut a furrow
therein, the maximum depth o~ which is determined by the setting
of the depth skids 48 and is generally between 1/2 and 2-1/2
inches. The furrow cut has a width approximately equal to or
slightly wider than the width of the cutting tip 70. Seed is
deposited in the furrow from the seed tube 20 and packed at the
bottom of the furrow by packer wheel 24.
The hardened tips 70 provide long lasting cutting teeth.
- The shape of the disk 50 provides cutting clearance for the tips
70 while protecting them from obstacles and providing backing for
the inserts 68 when used. By properly positioning the tips 70
with respect to the rotating disk 50, the joints between the tips
and the inserts or disk are loaded primarily in compression
during the tilling operation further reducing connection fatigue
which would result in the breaking off of the tips.
; 20
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