Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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KNIFE GUARD CONSTRUCTION FOR SICKLE KNIFE
This invention relates to a sickle knife type cutter and particularly to a
knife guard construction for use for use in co-operating with the knife blades
in a
cutting action either at a center between two opposed sickle bars or at any
point
along a sickle bar.
BACKGROUND OF THE INVENTION
The present invention relates to a crop cutting device comprising:
a frame structure arranged for forward travel over ground having a
standing crop thereon;
a cutter bar secured to the frame structure and extending transversely
across a front end of said frame structure;
a piurality of knife guards mounted in spaced relation along said cut#er
bar and projecting forwardly therefrom in transverse alignment;
each of said guards having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing
edges;
at least one sickle bar;
the sickle bar being mounted in transversely extending positiort and
being driven for reciprocating movement relative to said knife guards;
the sickle bar having a plurality of knife biades mounted thereon for
movement therewith;
each of the knife blades having a boitom cutting surface for passing
across the upwardly facing ledger surface of the knife guards in a shearing
action
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and a top opposed surface;
each of the knife blades having two side cutting edges which are
chamfered from the top opposed surface down to the cutting surface to
cooperate
with the shearing edges of said knife guards;
each of the first and second sickle bars being driven by a distance
substantially equal to the distance between two knife guards such that each
knife
blade moves from a position at the outboard end of each stroke generally
aligned
with one of the knife guards to a position at the inboard end of each stroke
generally
aligned with a next adjacent knife guard.
The term "sickle bar" as used herein is intended to refer generally to a
structure which supports all of the knife blades at the spaced positions along
its
length and is not intended to be limited to a single continuous element
extending
along the whole length of the structure. Thus the bar may be formed of
different
elements at different parts of the length and may include pieces below and
above
the blades.
It is well known that many sickle knives of this general type include a
conventional or pointed guard where the guard is formed as an integral element
which includes a base piece attached to the cutter bar and defining the ledger
surface and a nose piece projecting forwardly from the ledger surface in front
of the
front edge of the blade which is generally pointed at a leading end so as to
separate
the crop to each side of the guard. This nose piece also stands up in front of
the
ledger surface to protect the front edge of the blade and includes a
rearwardly
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extending shelf over the ledger surface which forms a slot with the ledger
surface
through which the blade passes. Guards of this type include separate hold down
members between the guards which apply downward pressure on the cutter bar to
press the blades against the ledger surFace.
Pointed guards generally feature a point with a cut slot that the sickles
sections reciprocate in and out of. Various types of hold-down arrangement are
used to apply pressure to the sickle to keep its shearing surface in close
contact with
the guard ledger as cutting occurs. Usually these are located between the
guard
point or at the rear edge of the sickles. Most are sheet metal and feature
easy
adjustment using a hammer or a simple single point threaded adjustment. By
keeping the hold-downs separate from the guards fewer hold-downs than points
may
be used to reduce the cost and number of adjustments required. Pointed guards
have found much favour in easier cutting conditions due to the ease of
adjustment
and superior performance.
Another form of guard is known as a stub guard which is formed in two
separate pieces including a base piece which carries the ledger surface and a
top
piece which extends over the ledger surface, The pieces are separate and
separately adjustable relative to the cutter bar so that the top piece can
apply
pressure onto the blade to press it onto the ledger surface. The pieces
terminate at
a front edge which is just behind the front edge of the blade so that the
front edge of
the blade is presented to the crop. As this front edge must have a significant
width
for strength, there is a risk that crop engages this front edge rather than
the side
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cutting edges of the blade.
In tough cutting, stub or no-clog guards have found the most favour.
Stub guards use a separate top and bottom guard pieces that spaced slightly
more
than one sickle thickness apart create a slot for the sickle to operate in.
The front
edge of the sickle section protrudes slightly past the front tip of the two
guard
sections. This feature is what originally gave stub-guards their non-clogging
self-
cleaning action. A major improvement in stub guard technology was made when
fully adjustable top hold-down assemblies were introduced as shown in US
patent
4,894,979 (Lohrentz) issued January 236 1990 and in US Patent 4,909,026
(Molzahn) issued March 20th 1990. These arrangements allowed the gap to be
controlled much more precisely than previously so that the shearing surface of
the
blade was kept in close contact with the guard ledger surface. This
adjustability
allows the stub top to act as a much more effective hold-down than the hold-
downs
found on regular pointed guard systems.
One drawback of the stub guard system is that the blunt front edge of
the section is fully exposed to the crop entering during the entire sickle
stroke cycle.
This presents a banier to crop entry for any crop directly contacting the
front edge of
the section. The front edge must be blunt in order to avoid too narrow a point
becoming too weak and vulnerable to breakage.
The pointed guard has an advantage of presenting a point to the
incoming crop so that crop is effectively divided around it. This is
especially
advantageous when the sickle blade is at or near the end or start of each
stroke and
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the blunt front edge is hidden partially or entirely within the guard slot,
Since the
sickle bar velocity is lowest at or near the end or start of each stroke this
gives the
pointed guard a considerable advantage.
The guards can be formed as single elements separately mounted on
5 the guard bar or as double or even triple elements connected together side
by side
for common mounting and common adjustment relative to the guard bar.
US Patent 3,553,948 (White) issued January 12th 1970 discloses a
sickle bar of this general type which has a point in front of the ledger
surface.
However in this arrangement the point is located wholly in front of the ledger
surface
with no overhanging shelf extending rearwardly from the point over the ledger
surface. In its place is provided a plate which is clamped to the guard bar
and
extends forwardly therefrom over the ledger surface to engage into a slot at
the rear
of the point. This acts to hold down the knife blade as it reciprocates across
the
ledger surface and also provides a resistance to upward bending of the point
to
overcome the tendency of the point to break when engaged by an obstacle at the
ground surface.
Arrangements of this type are well known and very commonly used, In
some cases the arrangement is of the double sickle type where each sickle bar
is
essentially half the length of the cutter bar and the cutter bars reciprocate
in opposite
phase to minimize vibrating mass and vibrations. Usually the sickle bars are
timed
so that they move in opposite directions so that vibrations induced into the
cutter bar
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assembly are minimized. This allows higher knife speeds to be achieved and
therefore higher ground speeds and productivity from the mower.
Several attempts have been made to perfect the area where the
inboard ends of the sickles overlap during the inboard stroke near the center
of the
cutter bar assembly since this has always been a problem area subject to fast
wear
and/or poor cutting in tough cutting conditions .
US Patent 3,577,716 (McCarty) issued May 4th 1971 discloses a twin
sickle assembly where a single endmost blade on one sickle bar overlaps with a
single endmost blade on the other sickle bar during inboard stroke at a single
guard
point with one blade sliding directly on top of the other. The bottom blade is
inverted
relative to the other blades and particularly relative to the top blade across
which it
slides "to provide proper shearing relationship between the opposing
sections."
However, the shearing edges of the opposing blades as they move toward one
another meet while at the centerline of the center guard point so that, if the
cutting
occurs as intended between the two blades, the crop is foroed to bend around
the
side edges of the center guard point before being cut. Alternatively the crop
may be
cut as the blade enters the center guard point against the side edges of the
center
guard point. However, on the inboard stroke the shearing edges of both
sections
are spaced one section thickness from the guard ledger surFace which is not
desirable especially in tough cutting conditions. Further, on the outboard
stroke the
shearing edge of the inverted section is spaced one thickness from the guard
ledger
as it enters the next adjacent guard point.
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US Patent 4,236,370 (Shaver) issued December 2"d 1980 discloses a
twin sickle assembly where at the end of the inboard stroke at least two of
the end
sickle blades at the inboard end of one sickle bar overlap with at least two
of the
blades of the other sickle bar. One sickle bar is raised so that the
overlapping
blades of one slide directly on top of the other through a set of special
guards, used
only at the center, which have a slot which has a double height to allow
passage of
both blades simultaneously. At the end of the outboard stroke at least one
section of
one sickle bar overlaps with at least one of the other sickle bar. The upper
blades
on the upper knife in the overlap zone are inverted so that the cutting
surfaces face
upwardly to cut against upper ledger surface of the special guards. The lower
sections have shearing surface facing down to cut against the lower ledger
surfaces
of the special center guards. The guard ledger surfaces and sickle blade
shearing
surfaces therefore are all property in contact in this arrangement to provide
a proper
shearing action. However, careful analysis will reveal that the hold downs
between
the guards hold the sickle bars downwardly, so that the shearing relationship
between the upper inverted sections and the upper shearing surface of the
special
center guards will not be held to tight toterance especially as the guards and
blades
start to wear. Also with the double overlap of more than one end blade, a
substantial amount of crop in the center overlap area gathers between opposing
sickle sections both on inboard and outboard strokes. This means the cutting
occurs
between the opposing sections as they pass each other around mid-stroke rather
than against the guard ledger surfaces. The shearing surfaCes between the
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downwardly facing blade and the upwardly facing inverted blade in this center
area
are two thicknesses of blade apart so that there is no proper shearing action,
which
is not desirable in tough cutting conditions.
US Patent 4,246,742 (Clark) issued January 27th 1981 discloses a
twin sickle bar arrangement where during the inboard stroke two end sickle
blades
on each sickle bar overlap with the blades of one sliding directly on top of
the blades
of the other and cooperate with guards which have a double height slot. On the
outboard stroke one blade of one sickle bar overlaps one blade of the other.
The
blades on the upper sickle bar in the overlap zone have their shearing
surfaces
facing down to cut against the blades of the lower sickle bar. The lower
blades in
the overlap area have square non-bevelled edges to provide a good ledger
surface
for the top blades to cut against. In this arrangement some cutting occurs
between
the opposing blades as they pass each other around mid-stroke. However, some
crop gathers between the blades and the guards and has to be cut by the blade
as it
enters the guard slot. The shearing surface of the top blades is spaced by the
thickness of a blade from the guard upper ledger surface which is not
desirable in
tough cutting conditions. Furthermore the crop gathered between the bottom
square
edged non-bevelled blades and guards must be cut without the benefit of a
sharpened bevelled edge.
US Patent 4,644,738 (Krambeck) issued February 24th 1987 discloses
a twin sickle bar arrangement where a single end sickle blade on each sickle
bar
overlaps during inboard stroke at a single center guard with one blade siiding
directly
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on top of the other. This leaves the center guard open at the outboard stroke.
The
bottom blade is mounted with shearing edge down to provide proper shearing
relationship between the blade and the guard ledger surface. An adjustable two
pronged hold-down is used on top of the top blade in the center overlap area.
However, the shearing edges of upper blade also face down, meaning that i#s
shearing surface end up being one thickness below the hold-down and one
thickness above the guard ledger surface on the inboard stroke. This is not
desirable in tough cutting conditions.
US Patent 4,660,351 (Remillard) issued April 28th 1987 assigned to
the present assignee discloses a twin sickle bar arrangement where a single
end
blade from each sickle bar overlaps during the inboard stroke. Both blades
have
their shearing surfaces facing downwardly. A special center guard is provided
with
two vertically spaced, upwardly facing ledger surFaces. The sickle bars are
arranged
vertically apart so operate on the separate ledger surfaces at the special
center
guard. This arrangement provides correct shearing surface to ledger
relationships
between sickle blades and guards on both inboard and outboard strokes. However
the provision of two vertically spaced ledger surfaces requires a large
vertical
spacing between the two blades and thus the two sickle bars. This interferes
with
the ability of the reel, which sweeps the crop past the guards, to be mounted
close to
and consistently relative to the cutting elements which is desirable for
effective cut
crop removal. Secondly there is no effective means of holding the shearing
surfaces
of the blades at close clearances to the guard ledger surfaces at the overlap.
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SUMMARY OF THE INVENTION
It is one object of the invention to provide a center overlap
arrangement for a double sickle mower,
According to one aspect of the invention there is provided a crop
5 cutting device comprising:
a frame structure arranged for forward travel over ground having a
standing crop thereon;
a cutter bar secured to the frame structure and extending transversely
across a front end of said frame structure;
10 a plurality of knife guards mounted in spaced relation along said cutter
bar and projecting forwardly therefrom in transverse alignment;
each of said guards having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing
edges;
a first and a second sickle bar;
the first and second sickle bars being mounted in transversely
extending position and being driven for reciprocating movement relative to
said knife
guards such that the first and second sickle bars reciprocate at the same
frequency
but in opposed phase;
inboard ends of said first and second sickle bars terminating in
generally end to end relationship adjacent a mid position of said Gutter bar
such that
the relative positions of said inboard ends vary during said reciprocating
movement;
the first sickle bar having a plurality of knife blades mounted thereon
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for movement therewith including an endmost knife blade at an inboard end of
the
first sickle bar;
the second sickle bar having a plurality of knife blades mounted
thereon for movement therewith including an endmost knife blade at an inboard
end
of the first sickle bar;
each of the knife blades having a cutting surface for passing across the
ledger surface of the knife guards and an opposed surface;
each of the knife blades having two side cutting edges which are
chamfered from the opposed surface to the cutting surface to cooperate with
said
shearing edges of said knife guards;
the knife guards including a center knife guard at which the first and
second sickle bars meet in said generally end to end relationship;
each of the first and second sickle bars being driven by a distance
substantially equal to the distance between two knife guards such that each
knife
blade moves from a position at the outboard end of each stroke generally
aligned
with one of the knife guards to a position at the inboard end of each stroke
generally
aligned with a next adjacent knife guard;
the endmost knife blade of the first sickle bar being arranged at a
height higher than the endmost knife blade of the second sickle bar;
the first and second sickle bars and the endmost knife blades thereof
being arranged such that, at an inboard end of each stroke of movement of the
sickle bars, the endmost knife blade of the first sickle bar is located over
the
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endmost knife blade of said second sickle bar at the center knife guard;
the first and second sickle bars and the endmost knife blades thereof
being arranged such that, at an outboard end of each stroke of movement of the
sickle bars, the endmost knife blade of the first sickle bar is moved to
vacate the
center knife guard and the endmost knife blade of the first sickle bar is
moved to
vacate the center knife guard;
the end most knife blade of the first sickle bar being inverted relative to
the others of the knife blades such that the cutting surface is at the top and
the
opposite surface is at the bottom;
the center knife guard having a bottom ledger surface facing upwardly
for cooperating with the cutting surface of the endmost cutting blade of the
second
sickle bar; and
the center knife guard having a top ledger surface facing downwardly
for cooperating with the cutting surface of the endmost cuiting blade of the
first sickle
bar.
The concept of the invention is applied to both pointed and stub-type
guard systems.
For strength of mounting reasons most modem guard systems feature
at least two guard elements which are connected side by side together by
lateral
elements, However the present invention is not limited to such double guards
but
may include single or triple or even more guards in a single construction
In both cases, the center knife guard preferably includes a base portion
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thereof which attaches to the cutter bar and carries the bottom ledger surface
and
the center knife guard includes a top portion thereof which carries the top
ledger
surface which top portion is adjustable upwardly and downwardly relative to
the base
portion so as to adjust the top portion and the top ledger surface relative to
the end
most knife blade of the first sickle bar.
In the arrangement where the knife guards are stub guards, a forward
edge of each knife blade generally will project forwardly of a forward edge of
the
base portion of the knife guard and a forward end of the top portion.
In the arrangement where the knife guards are pointed guards, each
has a front crop engaging section in front of the ledger surface and standing
upwardly from the ledger surface for extending forwardly from the front edge
of the
knife blade at the ledger surface to engage crop in advance of the front edge
of the
knife blade.
In this arrangement, preferably at least the center knife guard of the
pointed guards has an adjustment portion separate from the base portion and
located on top of the base portion above the ledger surFace, the adjustment
portion
providing the upper ledger surface and being aligned with the base portion so
as to
define a space therebetween through which the knife blade passes, and the
adjustment portion being adjustable upwardly and downwardly relative to the
ledger
surface so as to adjust the space therebetween through which the knife blade
passes.
Preferably a front edge of the adjustment portion is behind a rear edge
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of the pointed element
Preferably the adjustment portion is supported at a rear end such that
adjustment thereof causes a forward end to be moved upwardly and downwardly
relative to the ledger surface.
Preferably the forward end of the adjustment portion is free to move
upwardly and downwardly relative to a rear edge of the front crop engaging
section.
Preferably a rear end of the adjustment portion is adjustably carried on
the cutter bar.
Preferably a forwardmost edge of the adjustment portion is located
behind the front crop engaging section.
Preferably each of the pointed guards has an adjustment portion
separate from the base portion and located on top of the base portion above
the
ledger surface, the adjustment portion being aligned with the base portion so
as to
define a space therebetween through which the knife blade passes, and the
adjustment portion being adjustable upwardly and downwardly relative to the
ledger
surface so as to adjust the space therebetween through which the knife blade
passes.
Preferably the width of the upper and lower ledger surfaces is
substantially equal to ensure that the crop can be cut as soon as the sickle
blade
reaches the guard point without being deflected before being cut,
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Preferably a next adjacent guard to the center guard has the lower
ledger surface vertically positioned one section thickness higher than the
lower
ledger surface of the central guard point.
Preferably the inverted upper blade cuts against a top ledger surface of
5 a next adjacent guard to the center guard which also has top and bottom
ledger
surfaces.
It is a further object of the present invention which is independent of
the first object set forth above to provide an improved sickle knife of the
type which
uses pointed guards, which may be used only at the center guard of a double
sickle
10 arrangement or may be used generally as pointed guards of a sickle knife
construction which has a single cutter bar or a double cutter bar.
In accordance with a second aspect of the invention there is provided a
crop cutting device comprising:
a frame structure arranged for forward travel over ground having a
15 standing crop thereon;
a cutter bar secured to the frame structure and extending transversely
across a front end of said frame structure;
a plurality of knife guards mounted in spaced relation along said cutter
bar and projecting forwardly therefrom in transverse alignment;
each of said guards having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing
edges;
at least one sickle bar;
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the at least one sickle bar being mounted in transversely extending
position and being driven for reciprocating movement relative to said knife
guards;
the at least one sickle bar having a plurality of knife blades mounted
thereon for movement therewith;
each of the knife blades having a cutting surface for passing across the
ledger surface of the knife guards, an opposed surface and a front edge;
each of the knife blades having two side cutting edges which are
chamfered from the opposed surface to the cutting surface to cooperate with
said
shearing edges of said knife guards;
the at least one sickle bar being driven by a distance substantially
equal to the distance between two knife guards such that each knife blade
moves
from a position at the outboard end of each stroke in which the knife blade
lies on
top of the ledger surface of one of the knife guards to a posi#ion at the
inboard end of
each stroke in which the knife blade lies on top of the ledger surface of a
next
adjacent knife guard;
wherein at least one of the knife guards comprises:
a base portion having a rear section mounted on the cutter bar and
extending forwardly therefrom;
the base portion having a mid section in front of the cutter bar having
said ledger surface defined by a surface thereof;
the base portion having a front crop engaging section in front of the
ledger surface and standing from the ledger surface for extending forwardly
from the
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front edge of the knife blade at the ledger surface to engage crop in advance
of the
front edge of the knife blade;
and an adjustment portion separate from the base portion and located
adjacent the base portion facing the ledger surface;
the adjustment portion being aligned with the base portion so as to
define a space therebetween through which the knife blade passes;
the adjustment portion being adjustable upwardly and downwardly
relative to the ledger surface so as to adjust the space therebetween through
which
the knife blade passes.
In accordance with a third aspect of the invention there is provided a
crop cutting device comprising:
a frame structure arranged for forward travel over ground having a
standing crop thereon;
a cutter bar secured to the frame structure and extending transversely
across a front end of said frame structure;
a plurality of pointed knife guards mounted in spaced relation along
said cutter bar and projecting forwardly therefrom in transverse alignment;
each of said pointed knife guards having an upwardly facing ledger
surface with opposed side edges thereof arranged to provide first and second
shearing edges;
at least one sickle bar;
the at least one sickle bar being mounted in transversely extending
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position and being driven for reciprocating movement relative to said pointed
knife
guards;
the at least one sickle bar having a piurality of knife blades mounted
thereon for movement therewith;
each of the knife blades having a cutting surface for passing across the
ledger surface of the pointed knife guards, an opposed surface and a front
edge;
each of the knife blades having two side cutting edges which are
chamfered from the opposed surface to the cutting surface to cooperate with
said
shearing edges of said pointed knife guards;
the at least one sickle bar being driven by a distance substantiaily
equal to the distance between two pointed knife guards such that each knife
blade
moves from a position at the outboard end of each stroke in which the knife
blade
lies on top of the ledger surface of one of the pointed knife guards to a
position at
the inboard end of each stroke in which the knife blade lies on top of the
ledger
surface of a next adjacent pointed knife guard;
wherein each of the pointed knife guards comprises:
a base portion having a rear section mounted on the cutter bar and
extending forwardly therefrom;
the base portion having a mid seckion in front of the cutter bar having
said ledger surface defined by a surface thereof;
the base portion having a pointed front crop engaging section in front
of the ledger surface and standing from the ledger surface for extending
forwardly
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from the front edge of the knife blade at the ledger surface to engage crop in
advance of the front edge of the knife blade;
and an adjustable hold down portion separate from the base portion
and located adjacent the base portion facing the ledger surface;
the adjustable hold down portion being aligned with the base portion so
as to define a space therebetween through which the knife blade passes so as
to
hold down the blade onto the ledger surface to effect a shearing action;
the adjustable hold down portion being adjustable upwardly and
downwardly relative to the ledger surface so as to adjust the space
therebetween
through which the knife blade passes.
Preferably as described hereinafter the base portion is at the bottom
and the adjustable hold down portion is on the top. However it is possible but
less
desirable that this arrangement may be inverted so that the adjustable hold
down
portion s at the bottom.
The embodiments described hereinafter provide constructions where
all of the sickles cutting blades in the center overlap are located and
arranged so as
to be in proper shearing arrangement the respective guard ledgers.
The arrangement uses a single overlap at the fully inboard position so
that so that the end section of one sickle is directly superimposed on the end
section
of the other knife at a single guard point position, spaced vertically apart
by
approximately one section thickness. This overlap occurs at a center cutter
bar
which is generally at center of the cutter bar but not necessarily if the two
sickles
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differ in length. The center guard actually consists of upper and lower parts
each
with a ledger surface. At the center point the arrangement features separate
top and
bottom guards both with ledger surfaces so that cutting can occur against the
top or
bottom guard depending on sickle section orientation. The ledger surfaces at
this
5 central point are spaced vertically slightly more than two sickle seCtion
thicknesses
apart since they are occupied by two blades when the sickles are in their
fully
inboard position.
During the outboard stroke the center blades move in opposite
directions towards the adjacent guard points. As the knives move outboard,
crop
10 gathered between the end blades and the adjacent guard points gets severed
at the
leading edges of the adjacent guard point ledger surfaces. On the outboard
stroke
the inverted upper blade cuts against the top ledger surface of the adjacent
point
which also features matching top and bottom ledger surfaces. These are spaced
only slightly more than one section thickness apart since they are never
occupied by
15 more than one section. The lower non-inverted end blade of the other sickle
bar
outs in the conventional manner against its adjaoent to center guard point. At
the
fully outboard position the end blades are at the adjacent guard points and
the
central guard point that was previously occupied by the two superimposed
blades is
now empty of blades.
20 During the inboard stroke both end blades again move toward the
central guard point. Crop is gathered between the end sickle blades and is eut
against both edges of the central guard point. The inverted top blade cuts
against
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the top ledger surface of the central point while the lower blade cuts against
the
bottom ledger surface of the central guard point. During the inboard stroke
the
second to last blade of the upper sickle cuts against the lower ledger surface
of the
adjacent guard point. Note that at this guard point the lower ledger is
surface is
verticafly positioned one blade thickness higher than the lower ledger surface
of the
central guard point.
In the arrangement shown one inverted section at the end of the upper
knife is used. Altematively more than one inverted section could be used in
some
less advantageous arrangements, as long as additional points with upper and
lower
ledgers are provided. However this is not preferred.
The preferred arrangement of the single overlap at the central point
ensures that all crop is gathered between sickle blades and guard ledgers
rather
than between the blades on opposing knives as with other designs that overlap
more
than one section on the inboard stroke.
The width of the ledgers surfaces is the same top and bottom to
ensure that the crop can be cut as soon as the sickle blade reaches the guard
point
without being deflected before being cut.
Thus as described above, all of the sickles cutting elements in the
center overlap are in proper shearing arrangement the respective guard
ledgers.
Another feature of the arrangement as described in the embodiments
herein is to allow clearance adjustment to ensure tight clearance between all
blade
cutting surfaces and the respective guard ledger surfaces. At the guards with
upper
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ledger surfaces the upper portion of the guard is mounted to an adjuster bar.
This
adjuster bar has threaded fasteners that allow the gap between the upper guard
ledger surfaces and lower ledger surfaces to controlled precisely.
For strength of mounting reasons most modern guard systems have at
least two points which are connected together by lateral elements.
In the embodiment shown the two points that are occupied by the
inverted end section of the upper knife during inboard and outboard strokes
consist
of an upper and lower guard each with two connected points. The bottom guard
mounts directly to the frame element while the upper guard is connected to the
frame with the aforementioned adjuster bar. Other mounting arrangements
between
the upper guard portion and the guard bar may be used.
The ledger surfaces of the two upper guard points are preferably in the
same vertical position. The bottom guard features two ledger surface
vertically
spaced one section thickness apart. This allows the central guard point to
have its
ledger surfaces spaced two blade thicknesses apart while the adjacent point
has
then spaced one blade thickness apart.
As an altemative the top guard can be offset.
In conventional guards the lateral elements connecting the guard
points generally consist of a trash bar near the rear of the cutting zone that
prevents
the crop from moving rearward and a wear bar at the rear of the sickle bar
that
supports the blades and the lateral bars that connect the blades together. In
the
preferred embodiment both the top and bottom guard portions have these lateral
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elements for maximum strength and support of both sickles. Alternatively one
or
both of these elements could be omitted from either guard.
The stub guard arrangement features a unique bottom guard at as
previously described at center with ledger surfaces vertioally offset by the
thickness
of one sickle section. For the top guard at the center a conventional bottom
guard
can be inverted and mounted to a convenfional adjuster bar to provide the
upper
ledger surfaces. The rest of the guards on the cutter bar are conventional
stub style
bottoms with conventional adjuster bar and conventional stub hold-downs.
In the pointed guard arrangement there is provided a unique bottom
guard as previously described at the center with ledger surfaces vertically
offset by
the thickness of one sickle blade. The conventional tang or shelf that usually
covers
the top of the section is absent to allow for the top guard to be used. The
top guard
is forrned with two points with but with blunt front edges and ledger surfaces
closely
matching in width to the ledger surfaces of he bottom guard. The top guard is
mounted to an adjuster bar that allows fine vertical adjustment. Another
unique
feature of the bottom guard is a raised projection at the front of the ledger
surface
that covers the front edges of the sickle blades and top guard. This prevents
crop
material from entering from the front and clogging the guard.
BRIEF DESCRIPTIQN OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a top plan view of a portion of a header showing a center
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section of a sickle knife of a type including two sickles which overlap at the
center
section and using stub-type guards.
Figure 2 is a front elevational view of the sickle knife of Figure 1.
Figure 3 is a cross sectional view along the line 3 of Figure 1.
Figure 4 is a cross sectional view along the line 4 of Figure 1.
Figure 5 is a cross sectional view along the line 5 of Figure 1.
Figure 6 is a front elevational view of a second embodiment of a sickle
knife according to the present invention utilizing pointed-type guards.
Figure 7 is a cross sectional view along the lines 7-7 of Figure 6.
Figure 8 is top plan view of one section of a further embodiment of a
sickle knife of the type which uses pointed guards.
Figure 9 is a front elevational view of the section of Figure 8.
Figure 10 is a cross sectional view along the lines 10-10 of Figure 9.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
In Figures 1 to 5 is shown a first embodiment of a crop cuffing device
generally indicated at 10. Only a part of the complete machine is shown since
the
remainder of the machine may vary widely depending upon requirements and since
the construction is of course well known to a person skilled in the art. In
this
embodiment as shown, there is a frame generally indicated at 11 which of
course
forms only one part of the total frame structure that is the part of the frame
that is
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relevant to the present invention.
The cutting device 10 further includes a cutter bar 12 attached to the
frame structure 11. Thus the frame structure 11 in the part as shown comprises
a
guard bar 13 to which is attached a plurality of knife guards 14. The guard
bar 13 is
5 attached to a cutter bar 15 along the front edge of a frame structure which
supports
the guard bar in fixed position across the front edge of the frame for a
cutting action
of the crop cutting device on the standing crop.
The knife guards 14 are arranged in pairs and mounted on the guard
bar 13 at spaced positions along the length of the guard bar. In the
embodiment as
10 shown, only three of the pairs of guards are shown but it will be
appreciated that
there are additional guards as required to provide a crop cutting device of a
required
width.
The knife guards are basically of a conventional construction in that
each includes a lower portion 15 and an upper portion 16, These two portions
are
15 mounted on the guard bar 13 by a mounting arrangement 17 including bolts
1$, The
mounting arrangement thus attaches a rear end 19 of the lower portion 15
rigidly on
the underside of the bar 13 so that the guard projects forwardly from the bar
to a
front nose 20. Similarly the upper portion 16 is mounted on the guard bar 13
by an
adjustment plate 21 attached onto the same bolts 18. Upper portion 16 extends
20 forwardly to a nose 22.
In the embodiment shown the guards are stub guards so that the nose
of the upper and lower portions substantiafly overlie one another and confine
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between them the blades 23 of the sickle bar 24.
Each pair of guards thus includes two guard elements each defined by
an upper portion and a lower portion and the guard elements are shown in
Figure 1
at 25 and 26 with these guard elements being connected by a bar 27. A front
crop
guide bar 28 is also provided. Between the mounting bar 26 and the front guide
bar
28 is provided a channel within which the sickle bar 24 is mounted for
reciprocating
movement.
In the embodiment shown there are two sickle bars including a first
sickle bar 24A and a second sickle 24B. The bar 24A is driven by a
reciprocating
drive motor 29A and symmetrically the bar 24B is driven by reciprocating drive
motor
29B. These drive motors are arranged at opposite ends of the sickle bar so
that the
sickle bars meet at a central guard generally indicated at 30. Each of the
sickle bars
is driven by the reciprocating drive motor such that the bar reciprocates by a
distance equal to the space between each of the guards along the guard bar 13.
Each sickle bar comprises a support bar member 31 and the plurality
of blades indicated at 23. Each of the blades forms a generally triangular-
shaped
member which has a rear end bolted to the bar and converges from the rear end
to a
front end 23B. The front end is blunt first to provide a leading edge 23C.
Each of
the blades has a top surface 23D and a bottom surface 23E. Each of the blades
has
a side edge 23F and a second side edge 23G. The sides edges are chamfered from
the top surface down to the bottom surface 23E so that a sharp edge is formed
at
the bottom surface at each of the side edges.
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Along the full length of each of the sickle blades 24A and 24B apart
from the center guard 30, the construction is of a conventional nature as
shown in
Figure 5 with the blade configuration as described above. The top member 16
acts
to hold the blades downwardly into engagement with the top surface of the
bottom
portion 15. The bottom portion 15 has two side edges as best shown in Figure
'2
with those side edges 15A and 15B acting as side edges of a ledger surface 15C
defined across the top of the bottom portion 15. Thus the cutting action of
the
blades occurs between the ledger 15G and the bottom surface of the blade as
the
blade reciprocates from its position at one of the guards to its position at
the next
adjacent one of the guards. In this cutting action, therefore, the side edge
of the
blade moves across the space between the guards and enters onto the ledger
surface of the guard in a cutting action between the bottom surface of the
blade and
the top surface of the guard which are immediately adjacent and either in
contact or
closely adjacent position to provide a shearing action on the crop.
9 5 In these conventional guards, the upper portion 16 acts merely as a
hold down member contacting the upper surface of each of the blades so as to
apply
pressure to that upper surFaCe and hold it in contact with or closely adjacent
the
ledge surface of the bottom portion where the cutting action occurs. The upper
portion therefore as shown in Figure 2 has side surfaces 16A and 16B which are
narrower than the side edges of the bottom portion 15.
The mounting and adjustment arrangements for the bottom portion 15
and the other portion 16 are shown only schematically and not described in
detail
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since these can vary in accordance with a number of different designs readily
available to a person skilled in the art. It suffice to say that the hold down
portion 16
is adjustable so that the gap between the bottom surface of the hold down
portion
and the ledger surface of the bottom portion 15 can be adjusted to allow the
sliding
action of the blades while holding the blades in the required position.
This construction is well known and widely used in sickle knife cutting
systems of this type.
In the center section where the two sickle blades meet is provided the
specially designed center guard 30 having its two guard portions 31 and 32.
These
two guard portions are shown in cross section in Figures 3 and 4 respectively.
These guard portions are modified relative to the conventional guard portions,
one of
which is shown in cross section in Figure 5. The guards 31 and 32 are modified
so
that the upper portion 35 also provides a ledger surface 36 at the bottom
surface
with that ledger surface facing downwardly, Thus it will be noted from Figure
2 that
the upper portion 35 and each of the guards 31 and 32 has side edges 35A and
35B
which match the width of the underlying bottom portion 15 which includes the
same
conventional upper ledger surfaoe 23E as previously described. Thus in
addition the
upper portion 35 extends to a nose 37 which has the same length as the nose 20
of
the bottom portion 15. Thus the upper and lower portions of these guards are
generally symmetrical. In a further modffication, it will be noted that the
ledger
surfaces of the guards 31 and those to the right of the guard 31 are elevated
relative
to the ledger surfaces of the bottom portion of the guard 32 and those to left
of the
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guard 32. Thus the blades 23 of the bar 24A slide over the ledger surfaces of
those
guards with an endmost one of the blades as indicated at 38 sliding undemeath
an
endmost one 39 of the blades of the bar 248. The amount of elevation is equal
to
the thickness of the blades so that the endmost blade 39 of the bar 24B sits
directly
on top of and substantially in contact with the endmost blade 38 of the bar
24A.
The arrangement is such that there is only a single overlap blade and
this overlapping occurs at the inboard end of the stroke which is illustrated
in Figure
2. In this position both of the blades are arranged in overlying position at
the guard
32. When the bars are moved outwardly to the outboard end of the stroke, the
blade
38 vacates the guard 32 and moves to the guard indicated at 40. Also the blade
39
vacates the guard 32 and moves to the guard 31.
The blade 38 is inverted relatively to all the remaining blades. The
blade is of a symmetrical or identical to all of the remaining blades such
that it has
one surface which forms a cutting surface and an opposed surface where the
sides
are chamfered from the opposed surface to the cutting surface. In this
position,
however, the blade 39 is inverted so that the cutting surface is at the top
rather than
at the bottom. However the blade along side the blade 39 which is indicated at
42 is
of the conventional orientation that is with its cufting surface downward for
co-
operation with the bottom ledger surface of the guard defined by the bottom
portion
15.
Thus as shown in Figure 3, the blade 39 sits directly on top of the
blade 38. The blade 39 is driven by the bar 24B and the blade 38 is driven by
the
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bar 24A, At this location the bar 24B is formed by a supplemental bar portion
which
is on top of the blades at the end of the sickle blade construction so that
the bar 24B
does not interfere with the bar 24A on the underside of the blade 38 and the
remaining blades along that bar. The bar 24A may be increased in length beyond
5 the end blade to provide a guide portion assisting movement of the end blade
through the guards. The side edges of the blades at the position behind the
chamfered cutting section may have curved upper edges to prevent interference
between the blades as they overlap, particularly when the height of the blades
has
varied due to wear on the bar.
10 The blade 39 which is inverted thus moves between the guards 31 and
32 in its reciprocating action. Since each of these guards has an upper
portion 35
with a bottom ledger surface acting as a cutting surface having side edges for
co-
operating with the side edges of the blade 39, an effective cutting action
occurs as
that blade moves between those two guards. The guard 32 also has a boitom
15 ledger surface for co-operating with the blade 38. The guard 31 also has a
bottom
ledger surface for co-operating with the next adjacent blade of the bar 24B.
The guard 32 is adjusted as shown in Figure 3 to provide a double
space between the upper and lower ledger surfaces. This adjustment is obtained
by
adjusting the upper portion 35 on the mounting assembly 17. Conventional
20 adjustment arrangements can be provided as known to a person skilled in
this art.
As shown in Figure 4 the same construction at the guard 31 is adjusted so that
there
is only a single spacing for receiving the blade 39 or its next adjacent blade
as it
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passes through the guard 31.
Thus a proper cutting action is provided at each of the guards along
the length of the sickle bar. In each cutting action the cutting occurs
between the
sharpened surface of the blade and an immediately adjacent the ledger surface
of
the guard. As there is only a single overlapping blade at the inboard end of
the
stroke, there is no cutting action which occurs between blade surfaces as they
move
together since the cutting action of each of those blades occurs between the
blade
itself and its respective ledger surface of the guard.
Turning now to the embodiment shown in Figures 6 and 7, this
embodiment shows a similar arrangement to that described above when used in
conjunction with pointed guards. Thus in Figure 6 there are shown three
separate
guard pairs indicated at 50, 51 and 52 respectively. The guard 50 forms one of
a
plurality of such guards co-operating with a sickle bar 53 carrying blades 54.
Guard
52 forms one of a plurality of such guards co-operating with a bar 55 carrying
blades
56. The central guard 51 is a special guard somewhat similar to the central
guard of
the arrangement previously described.
As is well known pointed guards 50 and 52 include a bottom portion 57
mounted on the guard bar 58. The bottom portion 57 includes a ledger surface
over
which the blades reciprocate together with an overhanging portion 59. The
overhanging portion 59 and the bottom portion 57 converge to a nose 60 in
front of
the blade. The pointed guards thus are advantageous relative to the stub
guards in
that the nose 60 acts as a crop divider and there is less possibility for the
crop to
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engage the front edge at the blunt blades of the embodiment previously
described
containing stub guards. In this arrangement there is a central hold down unit
61
between the two pointed guards of the pair 50 or the pair 52. This arrangement
if of
course entirely conventional and the guard itself together with the hold down
are
mounted on the bar 58 in a manner which allows adjustment in conventional
manner
using different arrangements as known to one skilled in the art.
The central special guard 51 is shown in cross section in Figure 7.
Again it will be appreciated that this comprises a pair of guard elements 62
and 63
which are similar in construction and similar to the arrangement shown cross
section
in Figure 7.
Thus each of the guards includes a bottom portion 65 which is carried
on the guard bar 66. This bottom portion 65 includes a ledger surface 67 over
which
the blade 68 reciprocates in a cutting action. The blade 68 is carried on a
bar 69
forming part of the sickle bar. This runs in a channel 70 in the bottom
portion 65.
The bottom portion 65 extends forwardly beyond the front edge 71 of the blade
68
into a nose 72 which projects forwardly and provides a raised surface 73 in
front of
and thus protecting the front edge of the blade. The front edge of the blade
can thus
be protected from engagement with the crop and the crop is divided by moving
along
one side or the other of the nose 72. Conventionally the surface of the nose
72
communicates with a shelf or tang which engages over the blade and forms a
slot
within which the blade slides.
However in this arrangement the surface 73 fotrns a shoulder at the
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front edge of the blade and there is no portion extending rearwardly from that
portion. In its place is provided a hold down adjustable element 75 which is
mounted on the guard bar 66 by an adjustment mechanism 76 carried on the bolts
77 of the guard bar which allows the position of the hold down portion 75 to
be
adjusted by bolts 78 thus shown in Figure 6. The upper hold down portion 75
includes a channel 79 within which the bar 80 of the upper knife element 81
runs.
As in the previous embodiment the guard element 62 is arranged to
receive overlying blades 68 and 81 in the inboard end of the stroke where the
blade
elements overlap. Again the blade 81 is inverted relative to the remaining
blades so
that its upper surface forms the cutting surface with the side edges chamfered
away
from that cutting surface to the opposed surface. All of the remaining blades
are of
the conventional orientation witlt the cutting surface at the boftom and the
top
surface containing the chamfered sections.
The upper hold down element 75 is formed with a bottom ledger
surface 84 which co-operates with the upper cutting surface of the blade 81.
Thus
the width of the upper portion 75 is equal to the width of the bottom portion
65 at the
ledger surface to provide side edges of that ledger surface which co-operate
in a
shearing action with the respective blades. Thus at the guard elements 62, the
bottom blade 68 of the bar 55 co-operates with the bottom ledger surface and
the
upper blade 81 co-operates with the top ledger surface of the portion 75.
At the guard 63, the upper portion is adjusted to provide only a single
thickness for receipt of the blade of the bar 53. However in this guard again
there
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are provided both the upper and lower ledger surfaces so that the upper ledger
surface can co-operate with the inverted end blade 81 and the bottom ledger
surface
can co-operate with the next adjacent or penuitimate blade which is in the
normal
orientation.
Again therefore an effective cutting action is provided with each of the
blades properly co-operating with an immediate adjacent ledger surface.
Cutting
action occurs only between the side edges of the blade and the side edges of
the
ledger surface without the necessity of any cutting occurring between surfaces
which
are more widely spaced which can interfere with the proper shearing action of
the
crop.
Turning now to Figures 8, 9 and 10, there is shown a sickle knife which
is formed wholly of pointed guards where all of the guards are of the type
including
an adjustable hold down element. Thus each of the guards is of the type
generally
indicated in Figure 8 at 80 and includes a pair of pointed guard elements 81
and 82.
Each of these has a bottom portion 83 as shown in Figure 10 together with an
adjustable top portion 84. The boltom portion 83 has a ledger surface 85 and
projects forwardly from the ledger surface into a pointed portion 86 defining
a rear
shoulder 87 at the rear of the pointed portion 86 and in front the ledger
surface 85.
The guard co-operates with a bar 88 carrying blades 89. The hold down portion
84
is directly aligned with the bo#tom portion 83 and has side edges 90 which are
slightly narrower that the side edges 91 of the bottom portion 83 so that the
crop
cutting action occurs on the ledger surface 85 with the chamfered side edges
of the
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blades 85 and their bottom cutting surface. The hold down portions 84 are
adjustable upwardly and downwardly on the bolts 92 in conventional manner
relative
the guard bar 93. In this way the top hold down portion 84 can be adjusted
upwardly
and downwardly relative to the ledger surface 85 and behind the shoulder 87 so
as
5 to provide a close tolerance for holding the blade surface onto the ledger
surface in
the cutting action. At the same time the pointed nose 86 and the shoulder 87
protect
these elements for engagement with the crop so that the crop is split and
divided in
conventional manner by the nose 86 in the manner of a conventional pointed
guard.
However instead of providing the fixed shelf or ledger surface over the blade
and
10 instead of holding the blade down by hold down elements such as those
elements
61 which are located between the guards, the hold down portion 84 is directly
aligned with the bottom portion of the guard to provide a more effective hold
down
and a more close tolerance for pressing the cutting surface of the blade onto
the
ledger surface. The hold down action occurs at the location where the blade
tends
15 to lift in the cutting action rather than at a position offset from the
cutting action of the
guard.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the spirit and scope of the claims without department from such spirit
and
20 scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
