Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CIRCULAR 8AW BLADE WITH SAW CHAIN
PROVIDING CVTTERS
Backqround and Summary of the Invention
The instant invention relates to circular cutting blades,
and particularly to a circular cutting blade which utilizes a chain
having cutter lin~s therein serving as cuttars in the blade.
Circular saw blades of the type disclosed herein are used
in connection with hand-he]d power saws and also with brush or
light timber harvesting equipment. The blade is mounted on a motor
driven arbor which is rotated at relatively high speed to cause the
blade to cut material, generally wood.
A number of circular saw blade assemblies utilizing
chain-type cutters are known. One such blade is disclosed in U.S.
Patent No. 4,627,322 to Hayhurst, Jr., which utilizes a pair of
discs which sandwich a portion of a saw chain about the periphery
of the disc. Other blades utilize a circular disc having chain-
saw type cutter links mounted about the periphery thereof, as by
rivets or other fasteners securing the links to the disc.
Although the above-described blades are useful for their
intended purposes, each blade encounters difficulties when used in
extremely heavy brush or on hard materials. In the case of the
~irst described blade, the chain portion is free to rotate about
the disc, as there is no provision to engage the driving or anchor
links on the saw chain. As the chain stretches during use,
slippage increases as the chain is driven by the disc. In the case
of units with chain-saw type cutters installed on a disc, the
cutting teeth must be individually
removed and replaced in the event that one oE them becomes
damaged, as is frequently the case when the blade is used as a
brush cutter wherein it engages rocks rathex than brush.
The invention of the application includes a cutting
chain having links -therein, including anchor links and cutter
links. Each anchor link has an anchor portion which extends to
one side of the chain. Opposed side links join the anchor
links. Certain of the side llnks are cutter links. A disc
having alternating sprocket teeth and gullies extending about
the periphery thereof is provided. The chain is secured about
the periphery of the disc with the anchor portions received in
the gullies. Side links in the chain straddle the sprocket
teeth and serve to hold the chain from lateral displacement on
the disc.
~n object of the invention is to provide a cutting
blade wherein anchor portions of a clltting chain are positively
engaged by the disc on which the cutting chain is carried. More
specifically, these anchor portions seat within gullies provided
in the disc.
Another object is to provide such a cutting blade
where side links in a cutting chain straddle sprocket teeth in
the disc mounting the chain.
Another object of the invention is to provide a
cutting blade wherein the cutting chain may be easily removed
and replaced.
A further object of the invention is to provide a
cutting blade wherein the cutting chain is carried on a single
disc.
Yet another object of the invention is to provide a
cu-tting blade which is easy to use, economical to manufacture
and is durable.
A specific object is to provide a circular cutting
blade comprising a cutting chain having links, including anchor
links and cuter links, each anchor link having an anchor portion
extending to one side of the chain, and a disc having
alternating sprocket teeth and gullies extending about the
periphery thereof, wherein the chain is secured about the
periphery of said disc with the anchor portions received in said
gullies.
These and other objects and advantages of the
invention will become more fully apparent as the description
which follows is read in conjunction with the drawi~gs.
Brief Descri~ion of the Drawin~
Fig. 1 is a partial plan view of a cutting blade
constructed according to the invention.
Fig. 2 is an enlarged view of a portion of the
cutting blade of Fig. 1.
Fig~ 3 is an enlarged view of an edge of the blade
shown in Fig. 1.
Fig. 4 is a partial plan view of a modified form of
the cutting blade, with portions broken away.
Fig. 5 is a view showing another modification of the
cutting blade.
Detailed Description of the Preferred Embodlments
Turning now to the drawings, and initially to
Figs. 1-3, a cutting blade constructed according to the
invention is shown generally at 10. Blade 10 includes a disc 12
which has a generally circular outline, and which has an arbor
receiving bore 14 loca-ted at the center thereof. Bore 14 is
operable to receive a motor-driven arbor therein which secures
disc 12 to a power unit which is operable to drive the disc.
Disc 12 has an arrangement of alternating sprocket
teeth and gullies arranyed about the periphery thereof. The
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sprocket teeth are shown at 16, and the gullies are shown at 18.
In the preferred embodiment, teeth 16 and gullies 1~ are
symmetrical about lines 20, 22, respectively, which extend
outwardly from the cen-ter 23 of the disc. Disc 12 is formed of
a single sheet of material, such as steel, and is therefore easy
to manufacture ancl of relatively light weight.
A cutting chain 24 is disposed about the periphery of
disc 12. Chain 24 is formed of a series of links which are
joined together by pins, in the manner of well-known saw cha.ins.
Thus, chain 24 includes center, or anchor, links 26 with anchor
portions 28 extending downwardly in the links. Interconnecting
the center links are opposed side links 30, certain of these
side links being cutter links 32 such as shown at 32A and 32B.
Interconnecting sets of side links with the center links are
pins 34 extending through accommodating bores made in the links.
The cutter links may be similar to cutter links found
in conventional saw chain and include, as shown by link 32B in
Fig. 2, a body portion 36 from which projects at the forward
part thereof a depth gauge 38 and from which projects at the
rear part thereof a cutting tooth or cutter 40. The cutter and
depth gauge are separated by a gullet 42. The cutter links
include left and right hand cutter links interspersed with each
other extending along the links of the chain, exemplified by
left-hand cutter lin~ 32A which is present on the left side of
the chain facing the direction of the chains cutting action and
right-hand cutter link 32B which is on the right side of the
chain facing the cut-ting action of the chain.
The cutting chain, it will be noted, is mounted on
and extends as a continuous chain circumferentially about the
periphery of disc 12. The chain may be dismounted from disc 12
by removing a pin 34. A new chain may be mounted by extending
the disc and securing the free ends with an appropriate pin.
If desired, a chain having an anti-kickback
construction may be employed such as the saw chain deqcribed in
U.S. Patent Mo. 4,425,830. Whatever the type of chain employed,
the chain after installation on the disc the chain becomes in
effect a unified part of the entire cutting blade assembly.
In khe chain and between successive center links is
an open space 44. This space is bounded on opposite sides by
the opposed side links which join the two cen-ter links. With
the chain mounted in place, sprocket teeth 16 extend into these
open spaces and each pair of opposed side links become
positioned with such straddling a sprocket tooth. Anchor
portions 28 become seated within gullies 18 of disc 12. In this
way there is a positive driving engagement between the disc and
chain. The side links by straddling the sprocket teeth serve to
hold the chain from lateral displacement on the disc. With this
organization, a disc in the form of a single plate may be used
to support and propel the chain during the cutting operation.
The provision of only a single plate as a disc provides an
extremely lightweight cutting blade.
Referring now specifically to ~ig. 3, it may be seen
that cutting tooth 40 of link 32A extends to one side of disc 12
well beyond the thickness of the disc. The cutting tooth of the
link of the opposite hand, link 32B, extends a like distance to
the other side of the disc. This arrangement provides that
chain 24 makes a cut having a kerf significantly thicker than
the thickness of disc 12, thereby allowing free passage of the
disc through the cut material.
In a second embodiment of the invention, depicted in
Fig. 4, a cutting blade 60 is provided which includes a disc 62,
formed substantially like disc 12, and a chain 64 which is
formed similarly to chain 24. A pair of side plates 66, 68 is
provided, one being on each side of disc 62, and these side
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plates have peripheral margins that extend at least partially
over gullies 18 thus to overlap the anchor portions of the
chain, thereby preventing the influx of debris into the region
of the gullies and anchor portions, and also to inhibit lateral
shifting of the chain. Edges of the side plates underlie the
side links. Side plates 66, 68 are secured to disc 6~ as by
welds 70, or the side plates may be secured by other suitable
fasteners. Side plates 66, 68 have a thickness approximating
that of chain side links 30. The addition of the side plates
still provides a structure having a thickness less than the kerf
formed by the cutters on chain 64. This form of the invention
is particularly well suited for the harvesting of larger timber,
as the side plates add additional stiffness to the cutti.ng
blade.
Referring to Fig. 5, the cutting blade illustrated
includes a disc, partially shown at 70, which, like disc 12, has
a generally circular outline, and further has an arbor-receiving
bore located at the center thereof (not shown). Alternating
sprocket teeth 72 and gullies 7~ appear about the periphery of
-the disc. A cutting chain 76 is mounted about the periphery of
disc 70. The chain includes center or anchor links 78 with
depending anchor portions 78a, and opposed side links
interconnecting these anchor links, as exemplified by the side
links 80, which are tie-strap links, and side links 82, which
are cutter links. Interconnecting sets of side links with a
center link are pins 84.
In the cutter blade of Fig. 5, disc 70 is cut away at
one side of each sprocket tooth whereby a catch portion 86 is
defined in the form of a projection which projects from the
tooth in a direction extending circumferentially of disc 70, or
in a direction extending the length oE the chain which is
mounted about the disc.
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Each anchor portion 78a of an anchor link is shaped
-to have a catch portion 88 defined at one side in the forrn of a
projection which projects outwardly from the anchor portion in
the direction of the length o~ the chain. With the chain
mounted in place, each anchor link is mounted with its anchor
portion residing in a gully, and wi-th catch portion 88 of the
link underlying catch portion 8~ which is part of a sprocke-t
tooth. The structure described includes means interconnecting
the anchor links and the disc preventing radially outward
displacement of the anchor links. This means, more
specifically, comprises interengaging catch por-tions on the
anchor portions of a link and on a sprocket tooth, respectively.
When a cutting blade is rotated at extremely high
speeds, a centrifugal force develops -tending to throw the chain
radially outwardly, which has the effect of stretching the
chain. When a chain is manufactured~ a pin 84 interconnecting
the side links and a center link is placed in a position
extending through accommodating bores provided in these links
and then "spun" or flattened at its opposite ends, firmly to
~0 secure these ends to the side links. When a chain so
constructed is subjected to tension and stretched, failure tends
to occur, either by the anchor link giving way at the location
of the bore which receives pin 84, or by pin 84 failing in a
region where the pin extends between an anchor link and a side
link. With the construction illustrated in Fig. 5, the e~tent
of any radial outward displacement in the chain which occurs by
reason of centrifugal force is limited, this in turn limiting
the extent to which the chain of the cutting blade may be
stretched, thus to inhibi-t failure in the chain.
Thus a cutting blade has been disclosed which
provides for the carrying of a cutting chain on a disc which is
operable to propel the chain and retain the chain thereon. The
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disc may be a single layer structure or may be equipped with
side plates. Alternating sprocket teeth and gu:Llies are
arranged about the periphery of the disc wherein anchor portions
of a cutting chain are received in the gullies and the sprocket
teeth project in between the links in the chain.
The invention is not restricted to the particular
embodiments which have been described, since variations may be
made therein without departing from the scope of the invention
as defined in the appended claims.
