Note: Descriptions are shown in the official language in which they were submitted.
CA 02654671 2009-02-18
POWERED WEED TRIMMER CUTTING HEAD AND METHOD
BACKGROUND OF THE INVENTION
Field of the Invention.
The present invention relates generally to gasoline or electrically powered
devices
used to trim or cut grass, weeds and brush, wherein a driven head assembly
contains a
plurality of cutting blades that rotate at high speed to cut the vegetation.
The invented
device relates more specifically to such a cutting device wherein the cutting
head need not
be disassembled to access the cutting blades and the blades are replaceable
without the use
of tools. This ease-of-replacement feature may be very beneficial at the
cutting site where
blades sometimes break, a quick fix is desired, and it is especially
troublesome to drop
pieces of the cutting device in the grass or weeds. Therefore, use of the
invented device
would be extremely practical by those persons who regularly use a powered weed
cutting
machine.
Related Art
Powered rotating vegetation cutting devices from the past have used a nylon
string
or a plurality of cutting blades rotating at a high rate of speed to cut plant
matter.
Periodically, the cutting blades in said conventional blade-based devices
become
unserviceable due to breakage or becoming dull and must be replaced. This
operation
normally requires the use of tools and at least partial disassembly of the
cutting head to
access the cutting blades. Frequently, a cutting blade may be broken during a
cutting job
due to striking a hard object such as a stone, tree trunk, etc. and it is
desirable to replace the
broken blade on the spot so that the cutting job may be completed. Thus, it
becomes
necessary to either return the cutting machine to the garage or shop to
accomplish the task,
or, to replace the cutting blade at the cutting site, wherein tools to do so
must be carried on
the person. Disassembly of the cutting head at the cutting site introduces the
risk of the loss
of cutting head parts within the vegetation at the cutting site and the
attendant frustrating
search through said vegetation to attempt to locate the missing parts.
Examples of conventional cutting heads are found in the patent literature.
Barbula,
in U.S. Patents D280,903 and D301,110, illustrates cutting heads wherein
screws are
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employed to retain the cutting blades upon the head, and wherein the cutting
heads do not
permit the removal and replacement of the cutting blades unless the screws are
first
removed. U.S. Patent #6,119,350, Sutliff, et.al.; U.S. Patent #6,681,865 B2,
Pace; and U.S.
Patent #6,912,789, Price, III each address a cutting head for a rotary
trimming device
wherein the cutting head must be disassembled and/or special tools are
required to remove
and replace the cutting blades.
There is a need for an improved rotary vegetation cutting head that allows
blade
changing without tools and without disassembly of the head. There is a need
for such a
cutting head that results in no loose parts or fasteners during use or
maintenance, except
for replacement blades and removed broken blades. Such a cutting head would be
convenient and beneficial to those who have trouble or dislike using small
tools and
handling small parts. The present invention may meet these and other needs.
SUMMARY OF THE INVENTION
The present invention relates generally to powered rotating weed or brush
cutting
devices of the type that use a set of cutting blades mounted and secured
within a cutting
head and where the centrifugal force of rotation tends to maintain the cutting
blades in a
fully extended attitude in a plane perpendicular to the centerline/axis of
rotation. The
invented cutting head device eliminates the need to disassemble the cutting
head to replace
cutting blades, thereby eliminating the need to carry tools upon the person,
and requires
only that replacement blades be available at the cutting site if so desired.
The invented device comprises a generally cylindrical structure that rotates
as a unit
when coupled to a powered trimmer, but wherein the upper and lower portions
may be
rotated with respect to one another to access the cutting blades. Said
rotation of the upper
and lower portions relative to one another may include, for example,
preferably rotating the
upper portion relative to a stationary lower portion, or in other embodiments
rotating the
lower portion relative to a stationary upper portion, or in other embodiments
rotating both
upper and lower portions in opposite directions at the same time. The term
"stationary" in
this context means held without moving during the blade replacement process,
but it should
be understood that, after the blade replacement process, all parts of the
preferred cutting
head will rotate together or substantially together for the cutting process.
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Preferably, the upper, or "cover," portion is held in the closed, operating
position by
one or more springs and/or by one or more locks. When it is desired to access
the cutting
blades, the lock(s), if any, is/are unlocked, and the cover portion is rotated
using the hand
(typically approximately 30 degrees) against the force of the spring to expose
the pinned
ends of the cutting blades, which then may be replaced as necessary. Upon
completion of
the replacement operation, all that is typically required to return the
preferred device to
operating condition is to release the hand from the cover to allow the cover
to rotate back to
the closed position, and, if present, the lock(s) is/are re-locked.
The preferred cutting device is constructed of materials that are lightweight,
suitably
strong, resilient, shock resistant and waterproof such as plastic, aluminum
and like
materials. The preferred device has three, evenly-spaced cutting blades, but
embodiments
with other numbers may be effective. The preferred device is capable of being
retrofit to
existing rotary cutting machines, replacing the cutting head originally
supplied with said
machines; in some cases, an adapter may be used to properly fit the preferred
cutting head
to the cutting machine.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view according to one embodiment of the present
invention, showing the device in use, wherein, due to the high speed of
rotation of the
cutting head, the details of the head and the blade are "blurred" in this
drawing. The
embodiment of Figure 1 is understood to connect to a power unit with a handle
for the user.
Figure 2 is a perspective view according to the embodiment of Figure 1,
showing the
device in the operating position but not yet rotating.
Figure 3 is an exploded perspective view of the embodiment of Figures 1 and 2.
Figure 4 is a partial perspective view of the embodiment of Figures 1-3,
showing the
action of one embodiment of a spring during the steps of revealing and
recovering the ends
of the cutting blades, which steps allow removal of a broken or dull blade and
replacement
with a new blade. The blades are not shown in Figure 4.
Figure 5 is a perspective view of the embodiment of Figures 1-4, showing the
device
rotated open for blade replacement.
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Figure 6 is a perspective view of the embodiment of Figures 1-5, showing a
broken
blade being removed and replaced with a new blade.
Figure 7 is a top plan view according to the embodiment of Figure 1-6, showing
the
cover closed.
Figure 8 is a top plan view according to the embodiment of Figure 1-7, showing
the
cover open.
Figure 9 is a cross-sectional elevation view of the embodiment of Figures 1-8.
.
Figure 10 is a bottom plan view showing the bottom surface and details of the
cover
of the embodiment of Figures 1-9.
Figure 11 is a bottom plan view showing the bottom surface and details of the
spacer/spindle of the embodiment of Figures 1-10.
Figure 12 is a top view of an alternative embodiment of the invented rotary
cutting
head, in the closed position, wherein the cutting head includes a safety lock
for further
ensuring that the cover will not open during use. For simplicity, the blades
are not shown
in Figure 12, but it will be understood that they may reside and be retained
on the pins by
the closed cover in Figure 12.
Figure 13 is a cross-sectional view of the embodiment of Figures 12, viewed
along
the line 13 - 13 in Figure 12, wherein Figure 13 illustrates to the lock
system of this
embodiment in a locked condition. Note from Figures 12 and 13 that the lock
system is
offset from the central axis of the cutting head and does not interfere with
attachment of the
cutting head to the cutting machine by means of structure extending through
the central
bore/aperture of the cutting head.
Figure 14 is a top view of the embodiment of Figures 12 and 13, wherein the
lock
has been depressed and the cover has been rotated approximately 30 degrees to
reveal the
pins, whereby the blades (not shown in this view) could be installed and/or
removed from
the pins. Note in this view that the spring arm has been forced to rotate with
the cover about
30 degrees.
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Figure 15 is a cross-sectional view of the embodiment of Figures 12 - 14,
viewed
along the line 15 - 15 in Figure 14, wherein the lock may be viewed in the
unlocked
position.
Figure 16 is a top view of yet another alternative embodiment of the invented
cutting
head 300, wherein the cap is removed to reveal the annular spring system that
biases the
cover to a closed position. In Figure 16, the cover is in the closed and
locked position.
Figure 17 is a schematic, cross-sectional view of the embodiment of Figure
16,with
cap installed, and the cross-sectional view being adapted so that the
structure that controls
each end of the springs is shown in addition to the lock system being shown.
Figure 18 is a top view of the embodiment of Figures 16 and 17, with cap
removed,
illustrating the lock unlocked, and the cover having been rotated
counterclockwise and the
annular springs compressed by said rotation of the cover.
Figure 19 is a schematic cross-sectional view of the embodiment of Figure 16 -
18,
with the lock in the open position, again with the cross-sectional view being
adapted so that
the structure that controls each end of the springs is shown in addition to
the lock system
being shown.
Figure 20 is bottom view of the assembled cutting head of Figures 16 - 19,
with the
structure below the locked lock system cut away.
Figures 21 and 22 are detail, cross-sectional views of the embodiment of
Figures 16
- 20, wherein the lock is locked (cover closed and locked) in Figure 21 and
the lock is
unlocked (cover may be opened) in Figure 22.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the Figures, there are shown several, but not the only,
embodiments, of
the invented cutting head device wherein the upper and lower portions may be
rotated with
respect to one another for convenient access to the cutting blades, said
access preferably
requiring neither the use of tools nor disassembly of the cutting head.
Referring now to Figure 1, one embodiment of a vegetation cutting head 10
according to the invention is coupled to the drive end of a conventional
rotary cutting
machine 100 and is shown being driven in conventional manner by the machine to
cut grass
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and weeds. Only a small portion of the shaft of the machine is shown in Figure
1, but the
nature and large variety of rotary cutting machines will be understood by one
of skill in the
art, and many are currently commercially available. In general, the cutting
head is attached
to the lower end of the cutting machine, with the rotating shaft of the
machine received
coaxially in the generally cylindrical cutting head and tightened to and/or
otherwise
engaging the cutting head so that the rotating shaft rotates the cutting head.
Referring now to Figures 2-4, it will be seen that cutting head 10 is coupled
to
cutting machine 100, and is generally comprised of base portion 12 and cover
14. Cutting
blades 20 are slidably installed on, or removed from, pins 24 extending
upwards from the
base portion 12, which pins 24 may be uncovered by means of access notches 40
in cover
14. Cap 16 and spindle 18 are secured to the base by fasteners 56, which may
be seen to
extend from/through cap 16, through spindle 18, through center plate 28, and
into base 12.
Cap 16 and fasteners 56 are used to secure spindle 18 and base 12 to one
another by
aligning holes 54 in cap 16, holes 50 in spindle 18, and threaded holes 34
through plate 28
and into base 12. Alternatively, if plate 28 if an integral, raised portion of
base 12, then
fasteners 56 may extend into and threadably engage holes 34 in plate 28 only,
rather than
extending farther down into base 12. It is important to note that fasteners 56
need not be
removed, and the head 10 need not be disassembled, in order to remove the
blades, as will
be discussed further below.
The center plate 28 may be described as rising up above and inward (that is,
closer
to the central axis of the head and not extending as far out radially as the
base), relative to
the upper surface 26 of the base. Also, the spindle 18 may be described as
rising up above
and inward (closer to the central axis of the head and not extending as far
out radially as the
plate 28) relative to the plate 28.
Cover 14 is received between the cap 16 and the central plate 28, with cover
14
received around spindle 18 by means of central bore 44. Cover 14 may rotate on
spindle 18
in its plane, which is parallel to the planes of cap 16, central plate 28, and
base 12, to an
extent controlled by spring 36, as discussed below. Cover 14 preferably rests
and rotates on
plate 28, and is spaced from the upper surface 26 of the base by a distance
equal to the
thickness (height) of plate 28.
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Cutting head 10 is secured to cutting machine 100 utilizing shaft 62 of
cutting
machine 100, which extends down through the cap 16, spindle 18 (thus,
extending through
the cover on said spindle), and the base 12. Threaded knob 58 connects to
shaft 62 by
engaging threaded bore 60 of the shaft 62. It will be noted that with cover 14
in the closed
position, cutting blades 20 are safely and positively secured and retained
within cutting head
10, by virtue of being captured between the base 12 and the cover 14 in a
plane parallel to
both of said base and cover.
Referring now to Figure 3, it will be observed that base 12 contains pins 24
anchored within and protruding upwardly to be received within holes 22 of
cutting blades
20. Cutting blades 20, when installed upon pins 24, are free to rotate through
an arc around
the centerline of pins 24, thus allowing cutting blades 20 to rotate
independently of the
centrifugal force imparted by the rotation of the cutting machine 100. Thus,
cutting blades
20, which normally will rotate in the positions/path shown in Figure 1, may
rotate out of the
centrifugal path of rotation should a hard or immoveable object such as a rock
be struck
during a cutting operation.
Preferably, there are no screws, bolts, clamps, or fasteners used to secure
the blades
to the cutting head. The only fastening means for the blades is the blades
being slidably and
removably received on the pins, and the base 12 and cover 14 capturing the
blades there-
between. Further, preferably, there are not screws, bolts, clamps, or
fasteners used to secure
the cover to either the base 12 or the cap 16.
Shown to best advantage in Figures 3 and 4, center plate 28 (or "center pad
28")
may be a plate attached by means of fasteners 56, for example, to the center
portion of
based 12, or, alternatively, plate 28 may be a raised, integral center portion
of base 12.
Center plate 28 is the surface upon which lower surface 38 of cover 14 rests,
thus, creating a
space between the outer upper surface 26 of base 12 and the lower surface 38
cover 14 in
which the pinned ends of cutting blades 20 are contained. Within center pad 28
is bore 30
(which may also be considered an upper portion of base bore 33, especially if
plate 28 is an
integral portion of base 12), wherein the central, coiled portion of torsion
spring 36 resides.
Cut through plate 28 and into the upper surface 26 of the base is slot 32,
which receives
lower leg 36B of spring 36, thereby fixing the position of spring 36 within
cutting head 10.
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When cover 14 is placed upon base 12, upper leg 36A of spring 36 resides
within slot 46 cut
within the lower surface 38 of cover 14. See, especially, Figures 3 and 10.
The lower leg (leg 36B) and central, coiled portion of spring 36, therefore,
are
captured in the base 12 and plate 28, while the upper portion (leg 36A) is
captured in the
cover 14. Spring 36 biases the cover to stay in a closed position relative to
the base. At
least the top coil of the central, coiled portion of the spring 36, and upper
leg 36A, both
extend upwards above the top surface of plate 28, said at least the top coil
and leg 36A
extend part way into spindle 18, as is shown to best advantage in Figure 9.
Leg 36A
extends from the top coil, received in bore 48 of the spindle, to slot 46 in
the cover, and, in
doing so, extends through recess 51 of the bottom surface of spindle 18.
Recess 51, shown
to best advantage in Figure 11, allows upper leg 36A to swing/pivot in said
recess 51 as
cover 14 is rotated with respect to base 12.
Referring to Figures 3, 5, and 10, channels 42 in cover 14 fit loosely over
the upper
ends of pins 24, so that there is some space between the pins and the cover.
The channels
42, however, are shaped and sized to limit said space, to prevent the blades
20 from falling
or flying out of the cutting head when the cover is closed. Also,
accommodation may be
made to assist the channels 42 in sliding over the blades 20, when the cover
closes, to help
prevent jamming of the cover against the inner end 20' of the blade. This may
be important
for blades that, when installed over the pin, tend to tilt so that their inner
ends 20' raise up
off of the upper surface 26. For example, rounding or otherwise removing
material from
the channel corner 42' (see Figure 5) may allow the cover to push the inner
end 20' of the
blade downward against the upper surface 26 of the base to be out of the way
while the
cover closes completely.
One of skill in the art will realize, upon reviewing this disclosure and the
drawings,
that there are various ways and structure of installing one or more springs or
other biasing
means in the cutting head. Preferably, one or more springs may be used and
preferably are
captured in the head at least to an extent that said one or more springs will
not fall easily out
of the cutting head during assembling the cutting head. As disassembly and re-
assembly of
the cutting head (after initial manufacture) is not required in the preferred
embodiments,
once the spring(s) are captured during manufacture, the spring(s) will
typically not be likely
to fall out or be lost. In the embodiment of Figures 1- 11, a single spring of
sufficient
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strength is used and positioned so that normal use of the cutting head will
not tend to open
the cover. While one orientation for the spring, cover, and cover slot system
relative to the
blades and the base is shown in Figures 1- 11, said orientation may be changed
for
embodiments wherein the cutting head rotates in the reverse direction. Said
orientation and
the spring strength are adapted so that the spring bias is not overcome by the
rotation of the
cutting head, so that the cover does not open during cutting operation.
Preferably, the
spring bias acts in a direction opposite to the direction of rotation of the
cutting head.
Optionally, a cover lock may be included in the embodiment of Figures 1- 11,
to ensure
that the cover does not open during cutting operation. Alternative embodiments
are
portrayed in Figures 12 - 22 that include two, but not the only, embodiments
of lock
systems, and/or different, but not the only, spring arrangements.
Cutting head 10 is secured to cutting machine 100 by inserting shaft 62 within
and
through aligned bore 52 in cap 16, bore 48 in spindle 18, and bores 30/33 in
plate 28 and
base 12. By extending through the plate 28 and its bore 30, the shaft 62 also
extends
through the center space of the coil of spring 36, which is received in bore
30. Treaded
shaft 59 of knob 58 is threaded and tightened within threaded bore 60 of shaft
62 to
complete the assembly.
Figure 4 illustrates the position of spring 36 and spindle 18 upon base 12,
wherein
the spring may be seen to be captured in the slot 32 of the base, and slot 32
and bore 30 of
the plate 28. The leg portion called-out as 36A in Figure 4 extends from the
recess 51 of
spindle 18 to extend into slot 46 of the cover (not shown in Figure 4).
Figure 5 illustrates cover 14 in the open position wherein the cover 14 has
been
rotated to align notches 40 with, and to expose, the pinned ends of cutting
blades 20. It may
be noted that the diameter of cap 16 is significantly smaller than the
diameters of cover 14
and base 12, and cap 16 does not extend across notches 40 or otherwise
interfere with
removal of the blades. It may be noted that the single cover (rotation of the
single cover,
relative to the base, to the open position) uncovers all of the blades at the
same time for
removal; thus, it is not necessary to manipulate multiple covers or multiple
screws, bolts,
clips, clamps, or fasteners in order to reveal and remove a plurality or all
of the blades.
When the preferred cover is opened and the cutting head is maintained with the
head in a
generally horizontal orientation, the blades will tend to remain on their
pegs/pins until the
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user purposely removes one or more blades. As the blades 20 are retained in
the cutting
head only by means of being received on said pins 24, and being retained on
said pins 24 by
the cover (when the cover is closed), the blades might tend to fall off the
pins and out of the
cutting head if the cover were opened and the cutting head turned up-side
down. Therefore,
during normal blade replacement, the cover will be opened while the cutting
head is held
generally horizontally, so that the user (rather than gravity) may decide what
blade(s) to
remove. During weed-cutting operation, the cover will be closed and the device
may be
used in horizontal or tilted orientation.
Figure 6 illustrates a broken cutting blade 20 having been removed from pin 24
and
a new cutting blade 20 about to be installed.
Figure 7 illustrates cutting head 10 with cover 14 in the closed position,
with
notches 40 rotated away from cutting blades 20 and pins 24 residing within
channels 42.
Figure 8 illustrates cutting head 10 with cover 14 rotated to align notches 40
with the
pinned ends of cutting blades 20. It will be noted that lower leg 36B of
spring 36 remains
stationary, while upper leg 36A of spring 36 rotates counter-clockwise within
recess 51 of
spindle 18.
Figure 9, taken along line 9-9 of Figure 8, illustrates the internal fitting
of the
various parts described in the preceding Figures.
Figure 10 illustrates the lower surface 38 of cover 14.
Figure 11 illustrates the lower surface of spindle 18, wherein recess 51 is
located to
receive upper leg 36A of spring 36.
Figures 12- 15 illustrate an alternative embodiment comprising a lock that is
accessible from the top of the cutting head. As shown to best advantage in
Figure 13,
cutting head 200 comprises base 212, which includes integral central plate 228
and integral
spindle 218 upending from generally flat platform 225. Thus, the general
structure and
function of parts (base 12, plate 28, and spindle 18) that are separate in
cutting head 10 are
combined in cutting head 200 in a single, integral base 212. Spring 236 is
embedded in
base 212, with its lower arm 236B resting in a slot in the plate 228 and its
coil resting in
bore 233, and it upper arm 236B extending out, through recess 251 in the top
surface 252 of
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the spindle 218, to reach the cover 214. Cover 214 rests on top of plate 228,
receives
spindle 218 in its bore (defined by surface 244), and is rotatable around
spindle 218 for
covering and uncovering the pinned ends of the blades (wherein the blades are
not shown in
Figures 12 - 15). Cap 216 rests on top of, and may be screwed or otherwise
fixed to, the
top surface 252 of spindle 218, with clearances provided so that cover 214 may
rotate
between plate 228 (upon which cover 214 rests) and cap 216 (which covers and
contains
cover 214). Pins 224 are provided in the platform 225, and may be secured
therein by
screws 227 extending inward from the outer perimeter of the platform 255 to
engage the
pins 224, or by other methods of anchoring the pins in the base.
The entire cutting head may be attached to the shaft of a cutting machine, as
described earlier in this disclosure. For example, the cutting machine shaft
extending
through centrally-located aligned bores through the cutting head and
connecting to a
threaded knob (similar to knob 58) or by another fastener or other means.
Cutting head 200 comprises a lock 270 that ensures that the cover will not
rotate,
that is, will not open, during use on the cutting machine. Lock 270 comprises
plate 272 that
is resides, and slides vertically up and down, in a vertical slot 274 that is
provided in the
base 212, wherein typically a portion of the slot 274 is in all of the
platform 225, plate 228,
and spindle 218 portions and also a portion of the slot 274 is also in the
cover 216. Handle
276 is provided at the top of the plate 272 and may be a portion of the plate
272 that is bent
over to provide a horizontal finger-contact pad for being pushed by the user.
The handle
276 is accessible at a top opening of the slot 274 at a top surface of the
head 200, which
may be the top surface of cap 216.
Plate 272 comprises three downwardly-protruding legs 281, 282, 283. Leg 282
protrudes into the hollow space of a spring 285 that biases the plate 272 into
a raised
position (as in Figure 13) wherein leg 283 resides in portions of the slot 274
in both the base
212 and the cover 214. Specifically, the lower corner 291 of leg 283 resides
in the slot
portion in base 212, while upper corner 292 of leg 283 resides in the slot
portion of the
cover 214. With the lock plate 272 in this position, as shown in Figure 13,
the cover 214 is
blocked by leg 283 from rotating relative to the base 212, so that cover 214
remains closed
over the pins 224, as shown in Figure 12.
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When the user desires to uncover the pins and blades, the lock 270 may be
unlocked
by depressing handle 276, as shown in Figure 15. Upon doing so, plate 272
slides
downward (axially) in the vertical slot 274, against the bias of spring 285
(compressing
spring 285), to the point at which leg 281 and leg 283 abut against the bottom
wall 294 of
the slot. The plate 272 is sized and shaped so that, at this point, the upper
corner 292 is
completely removed from the vertical slot portion 295 of the cover 214, that
is, is lower
than the cover, so that the cover 214 may now rotate relative to the base 212.
It may be
noted that most of the structure of plate 272 resides at all times in the base
212 and cap 216,
with only leg 283 extending generally radially outward to pass through a
portion of the
cover 214 (specifically through slot portion 295). The plate 272 slides up and
down to a
raised position wherein leg 283 extends across the boundary between base 212
and cover
214 to block relative movement, and to a lowered position wherein leg 283 is
lowered out of
the way of the cover 214 to allow relative movement. As shown in Figure 14,
when the
lock is lowered as it is in Figure 15, cover 214 may be rotated to uncover the
ends of blades
20 (not shown) on pins 224.
The lock handle 276 optionally may be released as soon as the cover is
manually
rotated to the open position, as spring 285 will urge the plate 272 to the
lock position, but
the plate 272 will not be able to re-enter the slot portion 295 in the cover
until the cover
again returns to the closed position and the slot portion 295 is again aligned
with the portion
of slot 274 in the base. Alternatively, the lock handle 276 may be held in the
depressed
condition by a finger of the same hand that is holding the cutting head (while
the other hand
rotates the cover), for example, until the one hand releases the cover and the
other hand
releases the handle 276 of the lock, and/or until both hands are removed.
Referring to Figures 16 - 22, there is shown yet another alternative cutting
head 300,
which uses an annular spring system for biasing the cover 314 to a closed
position, and that
uses a horizontal lock system. Base 312 comprises platform 325 having a large
central
bore 333. Cap 316 rests on base 312 and is fixed to base 312, for example, by
screws 317
that anchor an inner ring 313 of base 312 to a downwardly-protruding ring 319
of cap 316.
Rotatably received between base 312 and cap 316 is cover 314. Accommodation
may be
made to one or both of the base 312 and cover 314 to help prevent blade outer
ends 20 "(see
Figure 3) from becoming wedged between base 312 and cover 314 if said outer
ends 20
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swing into the space between the base and cover. For example, a lip 326
(Figure 17) and/or
other curvature in surfaces adjacent to the lip 326 may be provided to deflect
or block said
outer ends 20 ". Both cover 314 and cap 316 also have large central bores,
which aligns
with large bore 333 to provide a large central cavity 334 through the head 300
that may be
used to connect the head 300 to many different cutting machines. For some
machines, an
adapter may be used to fit the head 300 to the machine.
As in the other embodiments discussed above, blades are rotatably received on
the
pins 324 of cutting head 300, and covered/retained by cover 314 by virtue of
the tops of the
pins 324 being received in channels 342 of the cover (Figurel6). When the
cover 314 is
rotated approximately 25 - 45 degrees (and, more preferably, about 30 degrees,
Figure 18)
the pins 324 are uncovered to allow removal of the blades.
Referring specifically to Figures 16 and 18, head 300 is shown with cap 316
remove,
by removing screws 317 and lifting cap 316 up off of the head 300. This allows
the spring
bias system for cover 314 to be more easily viewed. It should be noted, also,
that the three
cap-abutment-members 343, which are normally fixed to the underside (bottom
surface
341) of cap 316 by screws 349, are shown in Figures 16 and 18 as being removed
from the
cap 316 and left resting in the annular grooves at the second ends 336" of the
springs 336.
The holes that are normally threadably engaged by screws 349 are left empty in
these views.
This way, members 343 may be viewed in their preferred position for use in
compressing
springs 336, as is further described below.
Cover 314 has in its upper surface one or more, and preferably three, annular
grooves 335 that each receives a coil spring 336. At one end of each groove is
a cover-
abutment-member 337 against which is placed a first end 336' of each spring.
As shown in
Figures 16 - 19, the three cover-abutment-members 337 may be three inserted
pieces
fastened by screws 339 into a single circular groove at three locations
approximately 120
degrees apart, to separate said single circular groove into three end-to-end
grooves 335.
Alternatively, the three cover-abutment-members may be closed ends of three
separate
channels molded or otherwise forming in the cover. In either structure, the
first end 336 'of
each spring abuts against one of the cover-abutment-members 337.
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CA 02654671 2009-02-18
A second end 336" of each spring abuts against a cap-abutment-member 343. The
cap-abutment-members 343 are attached to, and extend downward from, the
underside of
the cap 316, for example, by means of screws 349 retaining the members 343
against the
bottom surface 341. Cap-abutment-members 343 extend into, and slide in, each
groove 335
at the second ends 336"of the springs 336. When cover 316 is rotated relative
to the base
312 and cap 316, the cover-abutment-members 337 move counterclockwise (in
Figure 16)
relative to the base 312 and cap 316 and compress the springs 336 against the
cap-abutment-
members 343. Thus, the springs 336 are compressed between the members 337 and
members 343 as shown in Figure 18.
Springs 336 are retained from popping out of the grooves 335 by virtue of
being
captured between the groove surfaces (below and at two sides of the spring)
and the bottom
surface 341 of cap 316 (above the spring). The springs creates the bias that
tends to keep
the cover 314 closed over the pins 324.
Lock 370 is provided in cutting head 300 in a position that allows it to be
accessed
from the outer perimeter surface of the base 312, rather than from the top of
the cutting
head. This may allow the user to push the handle 376 with a finger of the hand
holding the
base 312, while the other hand rotates the cover 314. The details and
operation of lock 370
are shown to best advantage in Figures 17 and 21 (locked) and Figures 19 and
22
(unlocked).
Lock 370 comprises plate 372 that resides in a vertically-orientated slot 374
that
extends horizontally through the base 312 and upward into the cover 314 (slot
portion 375).
Plate 372 has two legs 382, 383, wherein leg 382 protrudes into a lock spring
385 and leg
383 protrudes up into slot portion 375 of cover 314. As one may see to best
advantage in
Figures 21 and 22, depressing handle 376 pushes plate 372 radially inward
toward the
center of the head 300, moving leg 383 radially out of slot portion 375
(Figure 22), so that
cover 314 can rotate relative to base 312 and cap 316. Upon releasing the lock
handle 376,
spring 385 biases the plate 372 radially outward again and leg 383 again
crosses the
boundary between, and resides in both, base 312 and cover 314, thus, locking
the cover.
A user may change out cutting blades on the preferred embodiments of the
invention, without tools and typically with one hand opening the cover and the
other hand
removing and replacing the blade(s). In embodiments wherein a lock is
included, the user
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CA 02654671 2009-02-18
may need to use both hands to accomplish the task of depressing the lock,
rotating the
cover, and removing/replacing the blade(s). Upon release of the hand(s), the
preferred
cover will rotate/snap back into a position that covers the ends of the blades
and the
connection between the blades and the cutting head, and, in embodiments that
have a lock,
the lock will spring back into the locked position.
No tools need to be used for the blade-change-out process. If a person has
problems
with agility or with use of one of his hands, an item such as a cap or spacer
may be inserted,
upon opening of the cover, between one of the blades (not being replaced) and
the spring-
biased cover, to block the cover from rotating/snapping into closed position
until the
cap/spacer is removed. This way, the user would not have to hold the cover
over while
replacing the blade(s).
The rotation of the cover and base relative to one another preferably
comprises
rotating the upper portion relative to a temporarily-stationary lower portion,
as described
above and in the figures. In other embodiments, structure that allows rotating
the lower
portion relative to a temporarily-stationary upper portion may be used, or, in
other
embodiments, structure that allows rotating both upper and lower portions at
the same time.
In each case, there are various constructions other than that shown in the
drawings that
might allow these types of rotation, but the preferred embodiment, wherein the
upper
portion rotated relative to the lower portion offers simple design, simple and
safe operation,
and low chance of any pieces or parts falling out and becoming lost or
becoming a hazard.
Having the upper portion rotate to reveal the blades is preferable because the
blades remain
supported on the lower portion, preferably on pins in the lower portion, even
when the
upper portion has been rotated, thus, allow the user to reach and lift the
blades without
significant chance of the blades falling to the ground.
While several embodiments have been described and drawn, it should be noted
that
other embodiments may have bodies that are shaped, and that cooperate,
differently. The
preferred structures and functions are a base that supports the blades, a
cover that retains the
blades on the base, and apparatus for rotatably joining the cover to the base
and for joining
the base to the cutting machine. Typically, the cover is rotatably received
between the base
and a cap, wherein both base and cap are fixed to each other and fixed to the
machine, but
other arrangements may be used.
CA 02654671 2009-02-18
Although this invention has been described above and drawn with reference to
particular means, materials, and embodiments, it is to be understood that the
invention is not
limited to these disclosed particulars, but extends instead to all equivalents
within the broad
scope of the following claims.
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