U.S. patent application number 15/681485 was filed with the patent office on 2018-01-11 for sickle cutter system.
The applicant listed for this patent is Macdon Industries Ltd.. Invention is credited to Francois R. Talbot.
Application Number | 20180007827 15/681485 |
Document ID | / |
Family ID | 60892348 |
Filed Date | 2018-01-11 |
United States Patent
Application |
20180007827 |
Kind Code |
A1 |
Talbot; Francois R. |
January 11, 2018 |
Sickle Cutter System
Abstract
In a sickle cutting system, it has been found that a significant
reduction in average stubble length, which is calculated based on
the distance crop is pushed forwardly without cutting occurring,
can be obtained by a combination of the features where the length
of the cutting edge of each knife blade from a transverse rearmost
cutting line at which a cutting action occurs is increased to a
length greater than 2.2 inches; the width at the rear of the ledger
surface of each guard is increased to greater than 1.2 inches; and
the front edge of the blade is formed with an apex to shed crop
material to one or other side of the apex.
Inventors: |
Talbot; Francois R.;
(Winnipeg, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Macdon Industries Ltd. |
Winnipeg |
|
CA |
|
|
Family ID: |
60892348 |
Appl. No.: |
15/681485 |
Filed: |
August 21, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13743968 |
Jan 17, 2013 |
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15681485 |
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61587843 |
Jan 18, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A01D 34/18 20130101;
A01D 34/13 20130101; A01D 34/14 20130101 |
International
Class: |
A01D 34/13 20060101
A01D034/13; A01D 34/18 20060101 A01D034/18; A01D 34/14 20060101
A01D034/14 |
Claims
1. A sickle cutting apparatus 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 knife guards mounted along the cutter bar and
projecting forwardly therefrom; each of said guards having at least
one guard finger so that the fingers are arranged in a row along
the cutter bar with a space between each finger and the next
allowing crop to enter the space up to a position of engagement
with a surface of the guard; each guard finger having an upwardly
facing ledger surface with opposed side edges thereof arranged to
provide first and second shearing edges; a sickle bar mounted in
transversely extending position and being driven for reciprocating
movement relative to said guard fingers; the sickle bar having a
plurality of the sickle knife blades mounted thereon for movement
therewith; each sickle knife blade comprising a blade body having a
cutting surface for passing across the ledger surface of the knife
guard fingers and an opposed surface with the blade body having on
first and second sides first and second side cutting edges to
cooperate with said shearing edges of said guard fingers; wherein
cooperation between the blade and the ledger surface of the guard
length defines a transverse rearmost cutting line at which a
cutting action occurs; wherein a length of each knife blade from
the transverse line to a forwardmost tip of the knife blade is
greater than 2.2 inches; and wherein a width of each guard at the
transverse line is greater than 1.2 inches.
2. The sickle cutting apparatus according to claim 1 wherein a
center line spacing between each knife blade and the next is less
than 3.0 inches and a length of each knife blade from the
transverse line to a forwardmost tip of the knife blade is greater
than 2.5 inches.
3. The sickle cutting apparatus according to claim 1 wherein the
length of each blade from the transverse line to the forwardmost
tip of the knife blade is greater than 2.5 inches.
4. The sickle cutting apparatus according to claim 1 wherein the
length of each blade from the transverse line to the forwardmost
tip of the knife blade is greater than 2.75 inches.
5. The sickle cutting apparatus according to claim 1 wherein the
length of each blade from the transverse line to the forwardmost
tip of the knife blade lies in the range 2.2 to 3.0 inches.
6. The sickle cutting apparatus according to claim 1 wherein a
width of each guard at the transverse line is equal to or greater
than 1.5 inches.
7. The sickle cutting apparatus according to claim 1 wherein a
width of each guard at the transverse line is of the order of 1.75
inches.
8. The sickle cutting apparatus according to claim 1 wherein the
transverse line is defined by a trash bar attached to the guard
finger and extending outwardly to the sides thereof.
9. The sickle cutting apparatus according to claim 1 wherein a
stroke length of the reciprocating movement is equal to the center
line spacing between the knife blades.
10. The sickle cutting apparatus according to claim 1 wherein each
knife blade has a front point portion in front of the side cutting
edges which front point portion has side edges converging to front
apex, where the apex and the side edges of the front point portion
are shaped and arranged such that crop material engaging the front
point portion, as the point portion is moved forwardly in the crop,
is shed to one or other side of the front point portion for cutting
by the side cutting edges and is not pushed forwardly by the front
point portion.
11. The sickle cutting apparatus according to claim 10 wherein each
side cutting edge is beveled from the opposed surface to the
cutting surface of the knife blade defining a cutting edge at the
cutting surface; the blade having a front point portion in front of
the beveled side cutting surfaces; wherein the front point portion
has side surfaces of the front point portion converging to a front
apex of the front point portion having an apex surface generally at
right angles to the cutting surface and the opposed surface and
wherein the apex surface of the front point portion is not beveled
with the thickness of the plate at the front apex of the front
point portion being equal to said constant thickness.
12. The sickle cutting apparatus according to claim 11 wherein the
beveled side surfaces are serrated in a direction generally at
right angles to the center line.
13. The sickle cutting apparatus according to claim 12 wherein the
beveled and serrated side surfaces terminate at a position spaced
from the front apex of the front point portion such that the side
surfaces of the front point portion are not serrated.
14. The sickle cutting apparatus according to claim 10 wherein the
side surfaces and the front apex of the front point portion are
curved around an axis on the center line at right angles to the
plate.
15. The sickle cutting apparatus according to claim 10 wherein the
front apex has a width less than 0.3 inch.
16. The sickle cutting apparatus according to claim 1 wherein each
knife guard comprises a stub guard with a lower member defining the
finger and an upper member overlying the finger with the knife
blade having a length so as to project forwardly from a front tip
of the upper and lower members.
Description
[0001] This application is a continuation in part of application
Ser. No. 13/743,968 filed Jan. 17.sup.th 2013. This application
claims the benefit under 35 USC 119 (e) of Provisional Applications
U.S. 61/587,843 filed Jan. 18, 2012; U.S. 61/664,345 filed Jun. 26,
2012; 61/677,169 filed Jul. 30, 2012 and U.S. 61/677,177 filed Jul.
30, 2012.
[0002] This invention relates generally to a sickle knife cutter
system for harvesting crop with improved cutting action which can
lead to a reduction in average stubble length in the crop as cut by
the system, as measured beyond a nominal length as determined by a
nominal height of the ledgers surfaces of the cutter guards from
the ground.
BACKGROUND OF THE INVENTION
[0003] The present invention relates generally 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 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 sickle bar
mounted in transversely extending position and being driven for
reciprocating movement relative to said knife guards; the 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 and an
opposed surface; each of the knife blades having two side cutting
edges which are beveled from the opposed surface to the cutting
surface to cooperate with said shearing edges of said knife guards;
the sickle bar being driven to carry the knife blades back and
forth between the knife guards.
[0004] 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 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.
[0005] Pointed guards generally feature a point with a cut slot
that the sickle blades 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
favor in easier cutting conditions due to the ease of adjustment
and superior performance.
[0006] 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.
[0007] In tough cutting, stub or no-clog guards have found the most
favor. Stub guards use a separate top and bottom guard pieces that
spaced slightly more than one sickle blade thickness apart create a
slot for the blade to operate in. The front edge of the blade
protrudes slightly past the front tip of the two guards. 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. 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 piece to act as a much more
effective hold-down than the hold-downs found on regular pointed
guard systems.
[0008] 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 a front edge of each blade,
which is typically a blunt front edge of a width of the order of
0.5 inch, 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 over the stub guard for most crops.
[0009] The guards can be formed as single elements separately
mounted on the guard bar or as double or triple elements connected
together side by side for common mounting and common adjustment
relative to the guard bar. There is no reason why more elements
might be included but this is not typical.
[0010] 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 assembly are minimized.
[0011] The sickle knife cutting system has been widely accepted as
the most power efficient system due to the shearing action. However
due to speed restrictions of generally less than 5 to 8 mph ground
speed, other systems such as rotating flail systems have come into
use since these can be operated at much higher ground speed of up
to 14 mph while maintaining a high cutting efficiency. Such rotary
systems have however much higher power usage, are limited in width
and provide crop handling difficulties for forming effective swaths
for drying of the crop.
[0012] It remains therefore an ongoing and highly desirable
objective to construct a sickle knife system which can cut standing
crop with sufficient cutting efficiency that the ground speed can
be significantly increased. It is believed that the construction of
a sickle cutting system which can operate at ground speeds of
greater than 5 to 8 mph and up to 14 mph would enable the
advantages of the sickle cutting action to take back the market
currently being met by the flail systems.
[0013] Cutting crops such as soy beans where the bean pods can be
located closely adjacent the ground typically requires low ground
speeds of around 4 to 5 mph to ensure that the crop is cut and fed
into the combine harvester without too much loss of the pods. Pods
can be lost if the cutting action causes some or too many of the
lowest pods to be left at the stubble or broken up by the cutting
action. It would be highly desirable to increase cutting speed
above the typical range of 4 to 5 mph so as to increase this to or
above 6 mph.
[0014] Cutting crops such as hay or forage crops such as alfalfa or
grasses typically allows higher ground speeds of up to 10 mph since
the crop is more resistant to a poor or inefficient cutting action.
It would be highly desirable to increase cutting speed above the
typical range of up to 10 mph so as to increase this to or above 12
or even 14 mph.
[0015] 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.
SUMMARY OF THE INVENTION
[0016] It is one object of the present invention to provide a
sickle cutting apparatus which can provide a reduction in average
stubble length in the crop as cut by the system.
[0017] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0018] a frame structure arranged for forward travel over ground
having a standing crop thereon;
[0019] a cutter bar secured to the frame structure and extending
transversely across a front end of said frame structure;
[0020] a plurality of knife guards mounted along the cutter bar and
projecting forwardly therefrom;
[0021] each of said guards having at least one guard finger so that
the fingers are arranged in a row along the cutter bar with a space
between each finger and the next allowing crop to enter the space
up to a position of engagement with a surface of the guard;
[0022] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges;
[0023] a sickle bar mounted in transversely extending position and
being driven for reciprocating movement relative to said guard
fingers;
[0024] the sickle bar having a plurality of the sickle knife blades
mounted thereon for movement therewith;
[0025] each sickle knife blade comprising a blade body having a
cutting surface for passing across the ledger surface of the knife
guard fingers and an opposed surface with the blade body having on
first and second sides first and second side cutting edges to
cooperate with said shearing edges of said guard fingers;
[0026] wherein cooperation between the blade and the ledger surface
of the guard length defines a transverse rearmost cutting line at
which a cutting action occurs;
[0027] wherein a length of each knife blade from the transverse
line to a forwardmost tip of the knife blade is greater than 2.2
inches;
[0028] and wherein a width of each guard at the transverse line is
greater than 1.2 inches.
[0029] The above arrangement obtains yet further improvements when
used with an arrangement in which each knife blade has a front
point portion in front of the side cutting edges which front point
portion has side edges converging to front apex, where the apex and
the side edges of the front point portion are shaped and arranged
such that crop material engaging the front point portion, as the
point portion is moved forwardly in the crop, is shed to one or
other side of the front point portion for cutting by the side
cutting edges and is not pushed forwardly by the front point
portion.
[0030] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0031] a frame structure arranged for forward travel over ground
having a standing crop thereon;
[0032] a cutter bar secured to the frame structure and extending
transversely across a front end of said frame structure;
[0033] a plurality of knife guards mounted along the cutter bar and
projecting forwardly therefrom;
[0034] each of said guards having at least one guard finger so that
the fingers are arranged in a row along the cutter bar with a space
between each finger and the next allowing crop to enter the space
up to a position of engagement with a surface of the guard;
[0035] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges;
[0036] a sickle bar mounted in transversely extending position and
being driven for reciprocating movement relative to said guard
fingers;
[0037] the sickle bar having a plurality of the sickle knife blades
mounted thereon for movement therewith;
[0038] each sickle knife blade comprising a blade body having a
cutting surface for passing across the ledger surface of the knife
guard fingers and an opposed surface with the blade body having on
first and second sides first and second side cutting edges to
cooperate with said shearing edges of said guard fingers;
[0039] wherein cooperation between the blade and the ledger surface
of the guard length defines a transverse rearmost cutting line at
which a cutting action occurs;
[0040] wherein a length of each knife blade from the transverse
line to a forwardmost tip of the knife blade is greater than 2.2
inches;
[0041] and wherein each blade has at least one cut out opening
through the blade extending from a rear edge of the opening
adjacent to but spaced from a rear edge of the blade toward the
tip.
[0042] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0043] a frame structure arranged for forward travel over ground
having a standing crop thereon;
[0044] a cutter bar secured to the frame structure and extending
transversely across a front end of said frame structure;
[0045] a plurality of knife guards mounted along the cutter bar and
projecting forwardly therefrom;
[0046] each of said guards having at least one guard finger so that
the fingers are arranged in a row along the cutter bar with a space
between each finger and the next allowing crop to enter the space
up to a position of engagement with a surface of the guard;
[0047] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges;
[0048] a sickle bar mounted in transversely extending position and
being driven for reciprocating movement relative to said guard
fingers;
[0049] the sickle bar having a plurality of the sickle knife blades
mounted thereon for movement therewith;
[0050] each sickle knife blade comprising a blade body having a
cutting surface for passing across the ledger surface of the knife
guard fingers and an opposed surface with the blade body having on
first and second sides first and second side cutting edges to
cooperate with said shearing edges of said guard fingers;
[0051] wherein each knife blade has a front point portion in front
of the side cutting edges which front point portion has side edges
converging to front apex;
[0052] and wherein each blade has at least one cut out opening
through the blade extending from a rear edge of the opening
adjacent to but spaced from a rear edge of the blade toward the
tip.
[0053] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0054] a plurality of stationary knife guards arranged to be
mounted along a cutter bar;
[0055] a sickle bar mounted in transversely extending position and
arranged to be driven for reciprocating movement relative to said
knife guards;
[0056] the sickle bar having a plurality of knife blades mounted
thereon for movement therewith;
[0057] each of the knife blades having a cutting surface for
passing across the knife guards;
[0058] each of the knife blades having on first and second sides
first and second side cutting edges converging toward a forward tip
of the blade;
[0059] each knife guard comprising a base portion arranged to be
mounted on the cutter bar and at least one guard finger mounted on
the base portion so that the guard fingers are arranged to be
mounted in a row along the cutter bar;
[0060] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges which cooperate with said side cutting edges
of said knife blades;
[0061] and a plurality of hold-down members arranged to be mounted
along the cutter bar;
[0062] each hold-down member comprising a base mounting member
arranged to be attached to the cutter bar;
[0063] each hold-down member comprising at least one hold-down
finger thereon carried on the base mounting member arranged to be
at positions spaced longitudinally of the cutter bar so as to be
cantilevered forwardly from the cutter bar to a position of a front
tip of each hold-down finger located at a spacing in front of the
sickle bar above the ledger surface of a respective one of the
guard fingers;
[0064] the guard fingers and hold down fingers thus forming
cooperating overlying pairs between which the blades pass in the
cutting action;
[0065] the guard fingers having no portion elevated above the
ledger surface thereof in front of the tip of the blade;
[0066] wherein the guard fingers and blades have lengths from the
cutter bar arranged such that a forwardmost tip of the guard finger
is forward of the tip of the blade.
[0067] Preferably also the guard fingers, blades and hold down
fingers have lengths from the cutter bar arranged such that a
forwardmost tip of the hold down finger is rearward of the tip of
the blade.
[0068] Preferably the tip of the guard finger is longer than the
tip of the blade by a distance in the range x to x and preferably
y.
[0069] Preferably the tip of the hold down finger is shorter than
the tip of the blade by a distance in the range x to x and
preferably y.
[0070] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0071] a plurality of stationary knife guards arranged to be
mounted along a cutter bar;
[0072] a sickle bar mounted in transversely extending position and
arranged to be driven for reciprocating movement relative to said
knife guards;
[0073] the sickle bar having a plurality of knife blades mounted
thereon for movement therewith;
[0074] each of the knife blades having a cutting surface for
passing across the knife guards;
[0075] each of the knife blades having on first and second sides
first and second side cutting edges converging toward a forward tip
of the blade;
[0076] each knife guard comprising a base portion arranged to be
mounted on the cutter bar and at least one guard finger mounted on
the base portion so that the guard fingers are arranged to be
mounted in a row along the cutter bar;
[0077] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges which cooperate with said side cutting edges
of said knife blades;
[0078] each guard finger having an forwardly projecting tip portion
in front of the ledger surface;
[0079] each guard finger having a rearwardly projecting tang
portion connected to a rear end of the tip portion and extending
therefrom over the ledger surface to a rear edge of the tang
portion located over the blade;
[0080] a lower surface of the tang portion thus defining with the
ledger surface a slot through which the blade passes;
[0081] the lower surface of the tang portion including a first
portion adjacent the tip portion which is generally parallel to the
ledger surface and a second portion adjacent the rear edge which is
inclined at an angle away from the ledger surface.
[0082] Preferably the second portion defines a common plane
inclined at a common angle to the ledger surface.
[0083] In one preferred arrangement for forming the tang the second
portion of the tang portion is bent relative to the first portion
at a transverse line across the tang portion at the front of the
second portion so that both the upper and lower surfaces are
inclined.
[0084] In another arrangement, the second portion of the tang
portion tapers in depth from the lower surface to an upper surface
thereof toward the rear edge thereof.
[0085] Preferably a length along the tang portion of second portion
from the rear edge to the first portion is shorter that a length of
the first portion to the tip portion.
[0086] According to one aspect of the invention there is provided a
sickle cutting apparatus comprising:
[0087] a plurality of stationary knife guards arranged to be
mounted along a cutter bar;
[0088] a sickle bar mounted in transversely extending position and
arranged to be driven for reciprocating movement relative to said
knife guards;
[0089] the sickle bar having a plurality of knife blades mounted
thereon for movement therewith;
[0090] each of the knife blades having a cutting surface for
passing across the knife guards;
[0091] each of the knife blades having on first and second sides
first and second side cutting edges converging toward a forward tip
of the blade;
[0092] each knife guard comprising a base portion arranged to be
mounted on the cutter bar and at least one guard finger mounted on
the base portion so that the guard fingers are arranged to be
mounted in a row along the cutter bar;
[0093] each guard finger having an upwardly facing ledger surface
with opposed side edges thereof arranged to provide first and
second shearing edges which cooperate with said side cutting edges
of said knife blades;
[0094] each guard finger having an forwardly projecting tip portion
in front of the ledger surface;
[0095] each guard finger having a rearwardly projecting tang
portion connected to a rear end of the tip portion and extending
therefrom over the ledger surface to a rear edge of the tang
portion located over the blade;
[0096] a lower surface of the tang portion thus defining with the
ledger surface a slot through which the blade passes;
[0097] wherein a width of the tang portion across the guard finger
at the rear end of the tang portion is greater than 1.2 inches and
more preferably equal to or greater than 1.5 inches.
[0098] Preferably a width of the tang portion across the guard
finger at the rear end of the tang portion is substantially equal
to a width of the guard at the rear end of the tang portion.
[0099] The stubble which is cut by the knife blades and is longer
than the nominal cutting height is caused by the distance travelled
over the ground while crop is in contact with and pushed by
elements of the blades and guards as the elements move forward
without cutting occurring. The elements include a trash bar of the
guard and a serrated edge of the blade where the crop is pushed
forward by engagement into a serration of the serrated edge.
[0100] It has been found, as described hereinafter, in relation to
the embodiments particularly described, that a significant increase
in ground speed while maintaining an acceptable level of cutting
efficiency as measured by the average stubble length can be
obtained by a combination of one or more of the features where:
[0101] a) The distance between the center line of the guards which
is generally equal to the distance between the center line of the
blades can be equal to the conventional length of 3.0 inches or may
be reduced to a narrower width typically 2.5 or 2.0 inch. This
distance may be equal to the stroke length so that a shorter stroke
length can allow a significant increase in reciprocation rate.
However the stroke length may be a multiple of the center line
distance. Even where the stoke length is not reduced so that the
increase in reciprocation rate cannot be achieved, the reduced
center line distance has been shown to provide a significant
advantage.
[0102] b) the length of the cutting edge of each knife blade as
measured from a rearmost end of a cutting action to a forwardmost
tip of the knife blade is increased from a conventional length to a
length greater than 2.2 inches.
[0103] c) the width of the ledger surface of each guard at a
position thereon aligned with the rear end of the cutting edge of
each knife blade is increased from a conventional length to a
length greater than 1.0 inches or 1.2 or 1.5 inches.
[0104] d) the front edge of the blade is formed with a pointed
portion where the shape of an apex and side edges of the pointed
portion are arranged to shed crop material engaging the point
portion as the point portion is moved forwardly in the crop to one
or other side of the point portion for cutting and to avoid pushing
crop forwardly by the point portion.
[0105] This combination surprisingly provides a crop cutting
efficiency which is sufficiently high that the ground speed can be
increased from the conventional of the order of 5 to 8 mph to 12 to
14 mph. This increase is significant and significantly alters the
ability of the draper header to harvest forage crops such as
alfalfa at greater than 10 mph and up to 14 mph and to harvest soy
beans at greater than 5 mph and up to 6 or 7 mph.
[0106] The invention herein can be defined as or relate to the
method of cutting, the header for cutting, the guards and/or the
knife blades. Thus each of these components of the invention
includes aspects of the invention which distinguish that component
from the prior art as defined hereinafter.
[0107] A first improvement can therefore be obtained by providing a
knife blade which is narrower than conventional system so that
typically the width is equal to approximately 2.0 inches center to
center while providing a blade which has a length greater than
conventional system so that the length from the trash bar to the
tip is greater than 2.0 inches, greater than 2.2 inches or 2.5
inches and typically of the order of or greater than 2.75
inches.
[0108] This can be further combined with an arrangement in which
the width of the guard at the trash bar is increased so that the
width of each guard at the rear trash bar is equal to the maximum
width which can be obtained while leaving a space at the trash bar
between the ledger surfaces of the order of 0.5 inch or the
distance necessary to avoid pinching of crop stalks between the
ledger surfaces.
[0109] Typically each of the knife blades is generally triangular
in shape so that the side edges converge to a front edge at an
angle of the order of 60 degrees to the direction of reciprocating
movement. The blade has a bottom cutting surface for passing across
the ledger surface of the knife guards and an opposed or upper
surface. The two converging side cutting edges are beveled from the
upper surface to the bottom cutting surface to cooperate with the
shearing edges of said knife guards. In addition the beveled side
edges are typically serrated with grooves running in a direction
longitudinal to the reciprocating direction. In order to maximize
the cutting action, the length of the cutting edge is substantially
the maximum length extending from the trash bar at the rear to a
position close to the front edge of the blade.
[0110] The fore-aft length of a blade has traditionally been in the
order of 45 mm (1.75 in) from the front of the trash bar, that is
the rearmost cutting location or the rear of the cutting action, to
the tip of the section, or 55 mm (2.2 in) from the front edge of
the knife back to the tip of the section. Traditionally this
dimension is usually similar to the length of the cutting edge.
[0111] In this new arrangement, the fore-aft length of the blade is
increased substantially. Thus the length of cutting edge of each
sickle blade from a rearmost end of the cutting action at the trash
bar, or to the rear of the shearing action on the ledger surfaces,
to a front edge of the blade in the present invention is greater
than 1.75 inches. This can lie in the range 2.2 to 3.0 inches.
[0112] The term "trash bar" as used herein typically is defined by
a specific transverse bar interconnecting to the ledger surfaces of
the lower guards but does not require the provision of a specific
bar member extending across the blades but merely relates to the
position of that component of the system where the crop is halted
as it moves rearwardly between the guard fingers. Thus at some
point the crop is halted so that it remains in the position where
it can be engaged by the side edges of the blades and can be cut in
the shearing action relative to the side edges of the ledger
surface. This element which halts the crop movement is called
herein the "trash bar".
[0113] This also reduces the angle of inward inclination of the
cutting edge from the typical 30 degrees to an angle less than 20
degrees and typically of the order of 15 degrees and in the range
15 to 30 degrees.
[0114] Thus in one example the blade has a width of 2.0 or 3.0
inches at the base and a length from the front of the trash bar to
the tip of 2.5 inches.
[0115] It is common practice for sickle sections, of the current
type having beveled and serrated side edges, to have a front edge
in the order of 15 mm (0.6 inches) wide. When used with a pointed
guard, this is not as much of a problem as this edge is sometimes
in the shadow of the guard. However, even with pointed guards and
certainly when used with stub guards, the wide tip has the
potential for running down crop or pushing the crop forwardly with
the forward motion of the cutter bar, thus leaving more long uncut
stems greater in length than the nominal minimum value above thus
significantly increasing the average length with is the measure
herein of cutting efficiency. In present invention the blade is
designed with a pointed tip, thus eliminating the problem when used
with stub guards.
[0116] In some crop conditions e.g. forage with a mat of wet leaves
near the ground, pointed guards will tend to plug due to "mouse
nesting" on the guard point. It is therefore important that a
cutting system works well with stub guards.
[0117] The intention is therefore to provide a sickle blade which
is as pointed as reasonably practical. A sharp point is difficult
to obtain so that typically the front edge is smoothly curved with
a radius of curvature less than 0.5 inches thus defining a front
apex which is sufficiently narrow to shed crop stalks to each side.
That is, each knife blade has a front point portion in front of the
cutting edges which has side edges converging to front apex where
the apex and the side edges are shaped and arranged such that crop
material engaging the point portion, as the point portion is moved
forwardly in the crop, is shed to one or other side of the point
portion for cutting and is not pushed forwardly by the point
portion. In the present arrangement the front apex is not a point
as this can be damaged but is a curved front edge of a radius of
curvature less than 0.5 inches and preferably less than 0.25
inches. From this curvature the sides of the pointed portion
diverge rearwardly at an angle approximately equal to or slightly
greater than the angle of the cutting edges.
[0118] In a blade which has a center to center spacing of the order
of 2.0 inches and a length from apex to trash bar greater than 2.0
inches, the angle of the side edges of the blade is less than 20
degrees and can be as low as 15 degrees.
[0119] The angle of the side edges of the front point portion can
be greater and is typically in the range 30 to 45 degrees and
preferably of the order of 35 degrees.
[0120] This curvature at the apex and the angle of divergence from
the curved apex acts to shed the crop to the sides and to avoid
trapping and pushing the crop forwardly.
[0121] While this is the optimum arrangement, a practical
construction may have a straight line across the apex with a
transverse width which is much less than the conventional 0.6
inches and is typically less than 0.25 inches.
[0122] Thus each knife blade has a front point portion in front of
the beveled and serrated side cutting edges which front point
portion has side edges converging to front apex, where the apex and
the side edges of the front point portion are shaped and arranged
such that crop material engaging the front point portion, as the
point portion is moved forwardly in the crop, is shed to one or
other side of the front point portion for cutting by the side
cutting edges and is not pushed forwardly by the front point
portion.
[0123] Preferably the beveled side sedges are serrated in a
direction at right angles to a forward direction.
[0124] Preferably the pointed portion has a thickness at the apex
equal to that of the blade.
[0125] Preferably the beveled edges are reduced in width at as they
approach the pointed portion leaving a strip of the upper surface
between the beveled edges having thickness equal to that of the
blade with side edges of the strip being parallel to the center
line of the blade.
[0126] Preferably at this strip the beveled edges become narrower
as the beveled edge approaches the front pointed portion of the
blade.
[0127] Preferably the beveled edges and the serrations therein
terminate at a position spaced from the apex of the pointed portion
such that the front pointed portion forms an arrow-head shape in
front of a forwardmost one of the serrations with the width of the
front pointed portion being substantially equal to the width of the
side edges at the forwardmost one of the serrations.
[0128] Preferably a center line spacing between each knife blade
and the next is less than 3.0 inches, preferably less than 2.5
inches and more preferably of the order of or equal to 2.0 inches.
Thus the center line spacing can be equal to the conventional value
of 3.0 inches.
[0129] Preferably a length of each knife blade from the trash bar
to a forwardmost tip of the knife blade is greater than 2.0 inches,
preferably greater than 2.2 or 2.5 inches and more preferably
greater than 2.75 inches.
[0130] Preferably the front point portion has side edges which are
not sharpened.
[0131] Preferably the radius of curvature of the front pointed
portion at the apex is less than 0.5 inch and more preferably less
than 0.25 inch.
[0132] The characteristics of the blade defined above, where it is
narrower than conventional, 2.0 inches as opposed to 3.0 inches,
and significantly longer, greater than 2.2 inches or 2.5 to 2.75
inches as opposed to 2.2 inches places considerable limitations on
the shape and arrangement of the beveled and serrated edges.
[0133] In order to form the pointed portion at the front edge in
front of the beveled edges, the beveled edges are reduced in width
as they approach the front edge leaving a strip of the upper
surface between the beveled edges with side edges of the strip
parallel to a center line of the blade. Thus at this strip the
beveled edge becomes narrower and the grooves in the edge get
shorter as the beveled edge approaches the front apex of the blade.
The beveled edges and the serrations therein terminate at a
position spaced from the front apex to define an arrow-head shaped
pointed portion in front of the beveled edges which imparts
sufficient strength to the construction to allow the formation of
the serrations. The thickness of the blade through the main body of
the blade excluding the beveled edges is constant so that the
pointed portion and the apex have the same thickness as the rest of
the main body of the blade and the bevel which reduces the
thickness does not extend to the apex.
[0134] The cutting efficiency and therefore stubble length are also
affected by the width of the cutting edge of the knife guard.
Generally, the width at the rear of the cutting edge on the guard
is in the order of 25 mm (1.0 in). In the arrangement of the
present invention that width is substantially increased. Thus the
width of each guard at a position thereon aligned with the rear end
of the cutting edge of each blade is greater than 1.0 inches or 1.2
inches or 1.5 inches. The maximum width of the guard is slightly
less than the center to center spacing of the blades since it is
necessary to leave a gap between the guards at the back to prevent
pinching the crop and to allow the crop to reach the back for the
rearmost cutting action. Thus with a blade center to center spacing
of 2.0 inches the width of the guard is slightly less than that of
the width of the blade or roughly 1.9 inches. Thus with a blade of
this width, the width of the guards can be as much as 1.9 inches
and preferably lies in the range 1.2 to 1.9 inches. However where
the blade is greater than 2.0 inches in width, the guard can have a
width which is between 0.5 and 0.1 inches less than the width of
the blade.
[0135] Thus the arrangement provided herein provides a center line
spacing between each guard finger and the next which is in some
cases less than 3.0 inches and more preferably 2.0 inch where a
width of each guard at the rear trash bar is greater than 1.5
inches and preferably 1.75 inches.
[0136] Thus a width of each guard at the rear trash bar is equal to
the maximum width which can be obtained while leaving a space at
the trash bar between the ledger surfaces of the order of 0.5 inch
or the distance necessary to avoid pinching of crop stalks between
the ledger surfaces.
[0137] Preferably the stroke length is equal to the center line
spacing between the knife blades.
[0138] Preferably, at the position in the stroke where the center
line of the knife blades is aligned with the center line of the
guard fingers, the side cutting edges of the knife blades
substantially directly overlie the side edges of the ledger
surface.
[0139] Preferably each knife blade has a front point portion in
front of the side cutting edges which front point portion has side
edges converging to front apex, where the apex and the side edges
of the front point portion are shaped and arranged such that crop
material engaging the front point portion, as the point portion is
moved forwardly in the crop, is shed to one or other side of the
front point portion for cutting by the side cutting edges and is
not pushed forwardly by the front point portion.
[0140] Of course ground speed can be increased if the operator has
no regard for cutting effectiveness and the quality of the cut
crop. This is of course unacceptable.
[0141] One measure of cutting effectiveness is that of the length
of stubble which remains on the ground. If the cutting blades run
at a nominal height from the ground then they will theoretically
cut all crop to a nominal length equal to the height of the blade
from the ground. However this does not occur as the sickle knife
moves forwardly since not all crop is cut immediately as it enters
the cutting system. As some cutting is delayed and the crop pushed
forwardly by engagement with elements of the cutting system to bend
over from the normal upstanding position, then some stubble will
have a length exceeding the nominal length and this length
difference will increase as the ground speed increases. Thus
cutting effectiveness can be measured by detecting and measuring
the average length difference of stubble which exceeds this nominal
length.
[0142] An acceptable effectiveness is defined where the average
stubble length difference, that is the average length beyond the
minimum or nominal length defined by the distance of the blades
from the ground, is less than 1.0 inches, as measured at a set
speed of 10 mph. Thus for example where the nominal height is a
typical 1.5 inches, an acceptable effectiveness is where a measured
average length is no greater than 2.5 inches.
[0143] Of course machines can run at different speeds and there is
no intention herein to limit the speed to a particular value.
However as the stubble length is of course speed dependent, it is
necessary, in order to analyze the system, to set a predetermined
value at which the stubble length is measured.
[0144] Of course in a practical situation there may be failures in
proper cutting action leaving some crop stalks greater than the
allowed length difference defined above. However discarding such
discernible failures in the cutting action which are due to cutting
errors and are not a measure of the actual efficiency of the proper
cutting, a proper efficiency is defined by the average stubble
length as set forth above.
[0145] Thus the best measure of cutting effectiveness is the
stubble length that is left after cutting. The requirement however
will vary depending on the crop. For example for a wheat crop, it
will not be critical that a short stubble length be maintained, as
the heads are generally high on the plant.
[0146] In the case of hay (alfalfa) it will be important that a
fairly short stubble length is maintained so that a significant
quantity of crop is not left in the field. A typical acceptable
total average stubble length in this case would be in the area of
2.75 inches (that is 1.25 inches longer than the nominal minimum
length). Thus the ground speed can typically exceed the 10 mph
value set above for the above analysis and may be as high as or
higher than 14 mph.
[0147] In the case of soybeans, the acceptable average stubble
length depends on the general height of the lowest bean pod on the
plants. The acceptable average stubble length thus varies from
about 2 to 2.5 inches or 0.5 to 1.0 inches greater than the nominal
value. In this case a speed of less than 10 mph is likely to be
desirable.
[0148] The guard fingers, knife blades and the trash bar are
arranged so as to provide a cutting action on the crop in which:
[0149] in a first cutting stroke, each knife blade moves across
from one guard finger to the next in a first direction so as to cut
crop located on said first side of the knife blade between the
first cutting edge of the knife blade and the next guard finger by
the shearing action while leaving uncut crop located on the second
side of the knife blade; [0150] and, in a second cutting stroke,
each knife blade moves across from the next guard finger to said
one guard finger in a second direction so as to cut crop located on
the second side of the knife blade between the second cutting edge
of the knife blade and said one guard finger by the shearing
action, including said uncut crop, while leaving uncut crop located
on the second side of the knife blade.
[0151] While this crop remains upstanding before it is cut, the
stubble length remains at the nominal value. However as soon as the
crop is pushed forwardly by a non-cutting surface or a cutting
surface which is not in a cutting action at that position in the
stroke, it begins to bend over and its length when it is cut is
increased from the nominal value by the distance the crop is bent
forwardly.
[0152] The guard fingers, knife blades and the trash bar are shaped
and arranged therefore to provide a percentage cutting inefficiency
of less than 35%, 30% or 25%, at the above set speed of 10 mph and
at a sickle stroke rate set at a value which provides inertia
values equal to those obtained by a three inch stroke at 750
rpm,
[0153] where percentage cutting inefficiency is calculated as
follows: [0154] within a rectangular area defined by the length of
the knife stroke and the ground distance travelled during one knife
cycle, the sum of any areas of crop in which the crop remains uncut
until it reaches an element of the cutting system by which the crop
is pushed forward, without cutting, by contact with the element as
the element moves forward; [0155] divided by: [0156] the
rectangular area defined by the length of the knife stroke and the
ground distance travelled during one knife cycle.
[0157] Thus in a first cutting stroke, there is an area of crop
located on the second side of each knife blade in which the crop is
gathered by contact with the guard fingers and trash bar as the
guard fingers and trash bar move forward while the knife blade is
cutting on said first side of said knife blade. Symmetrically in a
second cutting stroke, there is an area of crop located on the
first side of each knife blade that is gathered by contact with the
guard fingers and trash bar as the guard fingers and trash bar move
forward while the knife blade is cutting on said second side of
said knife blade.
[0158] The elements which can engage and push the crop while not
cutting the crop as the blade moves away from those elements
include the trash bar and the serrated edge of the blade on the
understanding that crop cannot slide along the serrated blade but
instead will remain at a particular serration and be pushed forward
by the blade at that location until the return stroke cuts the
crop.
[0159] There is in many prior art arrangements an area that is
generated by any crop which is pushed forward by contact with a
front edge of the knife blade. In the present invention the blade
is of a shape to shed the crop thus reducing this significant
inefficiency.
[0160] The definition of inefficiency can also be applied at
different ground speeds wherein the percentage cutting inefficiency
can calculated at 6 mph and at a sickle stroke rate set at a value
which provides inertia values equal to those obtained by a three
inch stroke at 600 rpm, is less than 30%; or the percentage cutting
inefficiency can be calculated at 10 mph and at a sickle stroke
rate set at a value which provides inertia values equal to those
obtained by a three inch stroke at 750 rpm, is less than 35%; or
the percentage cutting inefficiency can be calculated at 14 mph and
at a sickle stroke rate set at a value which provides inertia
values equal to those obtained by a three inch stroke at 900 rpm,
is less than 40%.
[0161] The reason for identifying the theoretical calculated
efficiency at three different speeds of 6, 10 and 14 mph is that
different machines can be designed and arranged to travel at
different speeds.
[0162] Thus for example a 40 foot header used as a straight cut
header for a combine can have a sickle knife length of 40 feet and
can be designed to travel in the range 2 to 8 mph so that using a
pre-set speed of 6 mph and a stroke rate of 600 rpm falls
reasonably in the range of a machine of this type.
[0163] The present invention sets out that, at the pre-set speed
and pre-set stroke rate, the shape and arrangement of the cutting
system is such that it obtains the stated inefficiency. Of course,
at different speeds and stroke rates, the same cutting system will
have different inefficiencies, but in order to determine whether a
cutting system provides the inefficiency of the present invention,
pre-set parameters must be determined to allow the calculation to
be carried out.
[0164] Thus as another example, at 14 mph the machine concerned can
be of the type for cutting hay or forage crops and will have a
header of for example 20 feet in width with two 10 foot sickle
knives.
[0165] At 10 mph the machine has intermediate characteristics. The
pre-set characteristics used therefore are set forth as alternative
to determine the actual theoretical calculated inefficiency of the
cutting system of a machine and the calculation can be carried out
at those pre-set characteristics selected from the above different
examples which best match the range of operation of the machine
concerned.
[0166] As defined in the figures hereinafter, the sickle stroke
rate for a 4.0 inch stroke, which provides inertia values equal to
those obtained by a 3.0 inch stroke at 750 rpm, is 650 rpm and the
sickle stroke rate for a 2.0 inch stroke, which provides inertia
values equal to those obtained by a 3.0 inch stroke at 750 rpm, is
918 rpm.
[0167] The pre-set parameters for the inefficiency calculation are
set out in table 23 hereinafter.
[0168] In order to achieve the above decrease in cutting
inefficiency, the following characteristics are preferably to be
selected, although other characteristics may when analyzed provide
the same level of inefficiency: [0169] a center line spacing
between each knife blade and the next which is less than 3.0 inches
and preferably of the order of 2.0 inches. [0170] a length of each
knife blade from the trash bar to a forwardmost tip of the knife
blade which is greater than 2.0 inches and preferably of the order
of 2.75 inches. [0171] a width of each guard at the rear trash bar
which is greater than 1.0 inches and preferably, for a guard
spacing center to center of 2.0 inches of the order of 1.75 inches.
That is the width of each guard at the rear trash bar is equal to
the maximum width which can be obtained while leaving a space at
the trash bar between the ledger surfaces of the order of 0.5 inch
or the distance necessary to avoid pinching of crop stalks between
the ledger surfaces.
[0172] Preferably the stroke length is equal to the center line
spacing between the knife blades.
[0173] Preferably at the position in the stroke where the center
line of the knife blades is aligned with the center line of the
guard fingers, the side cutting edges of the knife blades
substantially directly overlie the side edges of the ledger
surface.
[0174] Preferably each knife blade has a front point portion in
front of the side cutting edges which front point portion has side
edges converging to front apex, where the apex and the side edges
of the front point portion are shaped and arranged such that crop
material engaging the front point portion, as the point portion is
moved forwardly in the crop, is shed to one or other side of the
front point portion for cutting by the side cutting edges and is
not pushed forwardly by the front point portion.
[0175] Preferably the front point portion has side edges which are
not sharpened.
[0176] While much of the description herein is directed to a
narrower cutting system using blades of 2 inch width, the same
cutting action and operation of the blades can be obtained with
blades which have a spacing from tip to tip of 3 inches.
[0177] Preferably each blade with a base portion and only two
cutting edges is a separate component from each of the other blades
so that the side edges of each blade lie immediately adjacent the
side edges of the next adjacent blades. However blades can be
formed in pairs connected to the same base
[0178] Preferably the blade has only a single cut out opening
luring symmetrically on the center line and converging to an apex
directed toward the apes of the blade. However more than one cu out
opening can be provided with different shapes.
[0179] Preferably the cut out opening has a rear edge parallel to a
rear edge of the blade, two side edges substantially parallel at
right angles to the rear edge and two converging edges extending
from the side edges to a forward apex.
[0180] Preferably the length of each blade from the transverse line
defining the rearmost cutting action to the forwardmost tip of the
knife blade is greater than 2.5 inches. A maximum of less than 2.9
inches is preferred.
BRIEF DESCRIPTION OF THE DRAWINGS
[0181] FIG. 1 is a top plan view of a part of header showing a
portion of the sickle knife according to a first embodiment of the
present invention using a stub guard.
[0182] FIG. 2 is a cross-sectional view along the lines 2-2 of FIG.
1.
[0183] FIG. 2A is a side elevational view of a sickle apparatus
showing the engagement of the front edge of the knife and the
engagement of the trash bar with the crop which leads to cutting
inefficiencies leading to maximum stubble length increases.
[0184] FIG. 3 is top plan view of a knife blade for use in the
sickle knife of FIG. 1.
[0185] FIG. 4 is a side elevational view along of the knife blade
of FIG. 3.
[0186] FIG. 5 is top plan view of one knife blade of FIG. 3 on an
enlarged scale showing the angles of the side edges for different
length blades.
[0187] FIG. 6 is top plan view of a knife blade of the type of FIG.
3 showing a different width blade.
[0188] FIG. 7 is a top plan view of a part of header showing a
blade of a sickle knife according to a second embodiment of the
present invention using a pointed guard.
[0189] FIG. 8 is a cross-sectional view along the lines 8-8 of FIG.
7.
[0190] FIG. 9 is top plan view of another embodiment of cutting
system using a 3 inch spacing of the blades and using stub
guards.
[0191] FIG. 10 is a cross sectional view along the lines 10-10 of
FIG. 9.
[0192] FIG. 11 is a detail of the cross-sectional view of FIG. 10
showing the tips of the bottom guard finger, blade and hold down
finger.
[0193] FIG. 12 is top plan view of another embodiment of cutting
system using a 3 inch spacing of the blades and using pointed
guards.
[0194] FIG. 13 is a cross sectional view along the lines 13-13 of
FIG. 12.
[0195] FIG. 14 is a detail 14 of the cross-sectional view of FIG.
13 showing the shape of the tang portion.
[0196] FIG. 15 is a detail 15 of the plan view of FIG. 12 showing
the shape of the tang portion.
[0197] FIG. 16 is a top plan view of blade of the embodiments of
FIGS. 9 and 12.
DETAILED DESCRIPTION
[0198] In FIGS. 1 and 2 is shown a first embodiment of a crop
cutting 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 forms only one part of the total frame structure that is the
part of the frame that is relevant to the present invention.
[0199] 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 attached to the
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.
[0200] Each knife guard 14 includes one or more guard fingers 14A
so that guards can be arranged with a single finger, pair of
fingers or triples. As shown the guard bar forms a triple guard
construction with three fingers where a series of such guards are
mounted on the guard bar 13 at spaced positions along the length of
the guard bar. In the embodiment as shown, only one of the guards
is shown but it will be appreciated that there are additional
guards as required to provide a crop cutting device of a required
width.
[0201] The knife guards shown in FIGS. 1 and 2 are basically of a
conventional construction of a stub guard in that each guard finger
14A includes a lower portion 15 and an upper portion 16. These two
portions are mounted on the guard bar 13 by a mounting arrangement
17 including bolts 18. 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 fingers of the guard project 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 has fingers which extend forwardly
to a nose 22.
[0202] In the embodiment shown the guards are stub guards so that
the noses 20, 22 of the upper and lower portions substantially
overlie one another and confine between them the blades 23 of the
sickle bar or knife back 24.
[0203] 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 FIG. 1 at 15 and 16. A front crop guide bar
or trash bar 28 is also provided. Between the mounting bar 21 and
the front guide bar 28 is provided a channel 25 within which the
sickle bar or knife back 24 is mounted for reciprocating
movement.
[0204] The trash bar may form a continuous bar member extending
along the lower guard portion 15 in front of the bar 24 to prevent
any crop reaching that area. However the trash bar may be formed by
any part of the system which prevents the crop from moving
rearwardly beyond the rear end of the cutting edges of the
blades.
[0205] There may be a single sickle bar driven from one end or in
some cases there are two sickle bars driven from opposite ends and
meeting in the middle. The sickle bar or bars are driven by the
reciprocating drive motor (not shown but conventional) such that
the bar reciprocates back and forth.
[0206] In some cases the bar reciprocates by a distance S1 equal to
the space between the nose of one guards 15, 16 and that of the
next along the guard bar 13 so that the blades reciprocate from a
position with the center line of the knife aligned with the center
line of the first guard to a position aligned with the next and
back to the first. In other cases, the reciprocation stroke may be
as shown at S2 a multiple of, typically double, the distance
between the guards so that the knife moves from a first guard
finger across a second to a third and back to the first. This
arrangement reduces the available reciprocation rate due to
increased acceleration forces but reduces the number of
reversals.
[0207] Each sickle bar comprises the support bar member 24 and the
plurality of blades indicated at 23. As shown the blades are formed
in pairs mounted on a common base as shown in FIG. 3, but
individual blades may be provided or in some cases the blades may
have more than two on the same base.
[0208] Each of the blades forms a generally triangular-shaped
member which has a rear end or base 23A bolted to the bar and
converges from the rear end to a front end 23B. 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
beveled 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. The blades are also serrated at each cutting edge with
grooves 23L, 23M extending parallel to the bars 24 that is at right
angles to a center line 23H.
[0209] The top member 16 acts to hold the blades downwardly into
engagement with the top ledger surface 15A of the bottom portion
15. The bottom portion 15 has two side edges of the ledger surface
15A as best shown in FIG. 2 with those side edges 15B and 15C
acting as side edges of the ledger surface 15A. Thus the cutting
action of the blades occurs between the ledger 15A and the bottom
surface 23E 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 next guard in a cutting action
between the bottom surface of the blade and the top surface of the
guard which are immediately adjacent and generally in contact or at
least closely adjacent to provide a shearing action on the
crop.
[0210] In these guards, the upper portion 16 acts merely as a hold
down member contacting the upper surface of each of the blades so
as to prevent it from moving away from the ledger surface 15A by
applying pressure to that upper surface 23D of the blade and
holding the blade in contact with or closely adjacent the ledger
surface 15A of the bottom portion where the cutting action occurs.
The upper portion 16 therefore as shown in FIG. 1 has side surfaces
16B and 16C of the bottom surface 16A which is narrower than the
ledger surface 15A of the bottom portion 15.
[0211] The mounting and adjustment arrangements for the bottom
portion 15 and the upper portion 16 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.
[0212] The disclosures of the following documents of the present
Applicants are incorporated herein by reference or may be referred
to for details of the construction not provided herein. These show
various conventional details of the sickle knife system which can
be used in the arrangement herein but are not described as they are
known to persons skilled in the art.
[0213] U.S. Pat. No. 7,328,565 (Snider) issued Feb. 12 2008;
[0214] U.S. Pat. No. 4,894,979 (Lohrentz) issued Jan. 23, 1990
[0215] U.S. Pat. No. 4,909,026 (Molzahn) issued Mar. 20, 1990.
[0216] U.S. Pat. No. 6,962,040 (Talbot) issued Nov. 8, 2005.
[0217] U.S. application Ser. No. 13/680,557 filed Nov. 19 2012
based on a Provisional application 61/577,427 filed Dec. 19 2011
(Talbot) relating to an adjustable hold down.
[0218] In FIG. 1, a drive for knife bar 24 is indicated
schematically at 24A. This can comprise any suitable drive system
known to persons skilled in this art of a type which can generate a
stroke S1 of 2 inches at a drive rate of typically 918 rpm. The
system can also be arranged in an alternative embodiment to drive
the stroke S2 of 4 inches in which case the reciprocation rate may
be lower. The drive system 24A includes an input from a ground
speed indicator 24B which allows automatic adjusting of the stroke
rate of the drive system 24A in dependence on ground speed. As the
system herein provides a cutting efficiency which is higher than
that of previous designs and suitable for cutting at speeds as much
as 14 mph, it is possible when running at lower ground speeds such
as less than 10 mph to reduce the drive rate of the knife since the
maximum cutting effect is not required at those lower ground
speeds. Thus the system can be arranged to automatically control
the knife speed to a lower fixed value when the ground speed is
less than a predetermined set value or to provide a proportional
control of the drive speed.
[0219] The knife blade 23 is narrower than conventional system so
that typically the width W is equal to the stroke length which is
approximately 2.0 inches center C to center C while providing a
blade which has a length L greater than conventional system so that
the length from the trash bar 28 to the tip 23K is greater than 2.0
inches and typically of the order of or greater than 2.75
inches.
[0220] This can be further combined with an arrangement in which
the width W1 of the guard ledger surface at the trash bar 28 is
increased so that the width W1 of each guard at the rear trash bar
is equal to the maximum width which can be obtained while leaving a
space S at the trash bar between the ledger surfaces of the order
of 0.5 inch or the distance necessary to avoid pinching of crop
stalks between the ledger surfaces.
[0221] Typically each of the knife blades is generally triangular
in shape with straight side edges 23F, 23G. However other shapes of
the side edges 23F, 23G in plan such as convex or concave can be
used. Thus the side edges 23F, 23G converge to the front apex 23K
at an angle of the order of 60 degrees to the direction of
reciprocating movement. The two converging side cutting edges 23F,
23G are beveled from the upper surface 23D to the bottom cutting
surface 23E to cooperate with the shearing edges of the knife
guards. In addition the beveled side edges are serrated with
grooves 23L, 23M running in a direction longitudinal to the
reciprocating direction. In order to maximize the cutting action,
the length of the cutting edge is substantially the maximum length
extending from the trash bar 28 at the rear to a position close to
the front apex 23K of the blade.
[0222] In this new arrangement, the conventional fore-aft length of
the blade is increased substantially. Thus the length of cutting
edge of each sickle blade from a rearmost end of the cutting action
at the trash bar 28, or to the rear of the shearing action on the
ledger surfaces 15A, to the front apex 23K of the blade in the
present invention is greater than 1.75 inches. This can lie in the
range 2.2 to 3.0 inches.
[0223] The cutting efficiency and therefore stubble length are also
affected by the width of the cutting edge of the knife guard. In
the arrangement of the present invention that width is
substantially increased. Thus the width W1 of each guard at the
trash bar 28 is greater than 1.0 inches. The maximum width of the
guard is slightly less than the center to center spacing of the
blades since it is necessary to leave the gap S between the guards
at the back to prevent pinching the crop and to allow the crop to
reach the back for the rearmost cutting action. Thus with a blade
center to center spacing of 2.0 inches the width W1 of the guard is
slightly less than that of the width of the blade or roughly 1.9
inches. Thus with a blade of this width, the width of the guards
can be as much as 1.9 inches and preferably lies in the range 1.2
to 1.9 inches. However where the blade is greater than 2.0 inches
in width, the guard has a width which is between 0.5 and 0.1 inches
less than the width of the blade.
[0224] At the position in the stroke shown in FIG. 1 where the
center line C of the knife blades is aligned with the center line
CI of the guard fingers, the side cutting edges of the knife blades
23F, 23G substantially directly overlie the side edges 15B, 15C of
the ledger surface 15A.
[0225] Each knife blade has a front point portion 23X in front of
the side cutting edges 23F, 23G which front point portion has side
edges 23N, 23P converging to the front apex 23K, where the apex and
the side edges of the front point portion 23X are shaped and
arranged such that crop material engaging the front point portion,
as the point portion is moved forwardly in the crop, is shed to one
or other side of the front point portion for cutting by the side
cutting edges and is not pushed forwardly by the front point
portion 23X.
[0226] As shown in FIGS. 3, 4 and 5, the arrow head shaped front
point portion 23X has side edges 23N, 23P which are not sharpened.
The angle of the bevel of the sides 23F and 23G may extend partly
into the side edges 23N and 23P but the side edges 23N and 23P are
not beveled to the bottom surface 23E so that they are not sharp.
Also the last serration 23Y of the bevel edges 23F and 23G is
located at the bottom of the portion 23X so that the side edges 23N
and 23P are not serrated. The pointed portion 23X has a thickness
at the apex 23K equal to that of the blade so that as shown in FIG.
4B, the thickness along the center line remains constant right up
to the apex 23K. The arrangement is designed so that the front
portion 23X is as thick as possible over its full extent consistent
with the requirement to machine the blade to form the beveled and
serrated edges 23F, 23G. Thus the beveled side edges 23N and 23P
are reduced in width in plan view at as they approach the pointed
portion 23X leaving a strip 23R of the upper surface between the
beveled edges having thickness equal to that of the blade with side
edges 23Q of the strip being parallel to the center line 23H of the
blade. Thus, at this strip 23R, the beveled side edges 23N and 23P
become narrower as the beveled side edges 23N and 23P approach the
front pointed portion 23X of the blade.
[0227] The beveled side edges 23N and 23P and the serrations 23L
therein terminate at the position 23Y spaced from the apex 23K of
the pointed portion 23X such that the front pointed portion 23X
forms an arrow-head shape in front of a forwardmost one 23Y of the
serrations with the width of the front pointed portion 23X being
substantially equal to the width of the side edges 23N and 23P at
the forwardmost one 23Y of the serrations.
[0228] As shown in FIGS. 3 and 4, a center line spacing CLS between
each knife blade and the next is less than the conventional value
of 3.0 inches and preferably of the order of or equal to 2.0
inches. It will be appreciated that a measurement of center to
center spacing which is equal to an integral number of inches is
preferred for engineering reasons but in theory it is not essential
to have an integral number and in some cases the spacing can be in
millimeters. In practice, a spacing in the range 2.5 to 1.5 inches
is suitable. In FIG. 6 (not to scale) a wider spacing of 2.5 inches
is shown. In FIG. 5 the angles of different lengths of blade are
shown where a blade having a length of at least 2.5 inches from the
trash bar is shown having an angle A2 of the side edges and a
shorter blade having a length of the order of 2.0 inches from the
rash bar has angles A3. In each case the angles of the side edges
23N and 23P is slightly greater than that of the cutting edges.
[0229] As shown in FIGS. 3 and 4, a length L along the center line
23H of each knife blade from the trash bar that is the rearmost end
23T of the cutting edge 23F to the forwardmost tip 23K of the knife
blade is substantially equal to or greater than 2.75 inches.
Improvement in cutting efficiency is obtained by increasing the
length of the blade so that the selection of a value of at least
2.75 inches is preferred which provides the improved cutting action
while avoiding a blade which has a length greater than can be
manufactured to remain stiff and straight in the cutting action
without danger of bending. Improvement can be obtained at any value
greater than conventional blades so that any value greater than 2.0
inches is within the invention herein. A length greater than 2.5
inches will provide a significant improvement.
[0230] In order to provide shedding of crop at the apex, the radius
of curvature of the front pointed portion at the apex is less than
0.5 inch and preferably less than 0.25 inches. However a blunt
front edge is possible provided it is sufficiently narrow and a
value of less than 0.25 inch or more preferably less than 0.125
inch is possible.
[0231] The above geometry provides a construction in which the side
edges of the blade are arranged relative to a center line of the
blade at an angle less than 30 degrees and preferably less than 25
degrees.
[0232] Similarly the side edges of the front portion, which are
typically but not necessarily at the same angle as the side edges
of the blade, are arranged relative to a center line of the blade
at an angle less than 30 degrees and preferably less than 25
degrees. In practice this angle is preferably of the order of 20
degrees.
[0233] Thus the preferred construction provides a center line
spacing between each knife blade and the next is of the order of or
equal to 2.0 inches, the radius of curvature of the front pointed
portion at the apex is less than 0.25 inch and the side edges of
the front portion are arranged relative to a center line of the
blade at an angle of the order of 20 degrees.
[0234] As shown in FIG. 1, the width between the centers of the
guards is indicated at D. This can be the same as the length of the
cutting stroke so that the blades move from a position aligned with
the center line of one guard finger to that of the next. However in
some embodiments the stroke may be a multiple of the distance D,
typically twice, so that the blades move from the first guard
finger to the third crossing the second. The reversal of the
reciprocating action at the guard center line ensure that the
blades are stationary and therefore carrying out no cutting when
they are overlying the guard and not at an intermediate location.
The increase of the stroke length to a multiple of the finger
reduces the number of times the blades are stationary but requires
a reduced stroke rate due to the increased forces on the drives
system.
[0235] This distance D is less than 3.0 inches and is more
preferably of the order of 2.0 inches. Typically the stroke can lie
in the range 1.5 to 2.5 inches since this provides a stroke length
which allows an increase in the cutting reciprocation rate of the
sickle bar by a percentage of the order of 22%. This allows a
typical rate of 600 cycles per minute, suitable for a 40 ft sickle
bar, to be increased a rate greater than 750. For shorter bars this
rate can be greater than 900. The length of the stroke and the rate
are determined by the selected geometry of the drive system.
[0236] Typically each of the knife blades 23, as shown in FIG. 2,
is generally triangular in shape. In the example shown, the blade
23 forms a double blade connected by a base 23A. The base has holes
23J for mounting on the blade drive bar 24. The blade 23 has two
side edges 23F, 23G which converge at an angle A to the direction
of reciprocating movement. At the front of the blade is provided a
front apex 23K of a front arrow head shaped portion 23X.
[0237] The blade has a bottom cutting surface 23E for passing
across the ledger surface 15A of the bottom knife guards 15 and an
opposed or upper surface 23D. The two converging side cutting edges
23F, 23G are beveled from the upper surface 23D to the bottom
cutting surface 23E to cooperate with the shearing edges of the
knife guards. In addition the beveled side edges 23F, 23G are
typically serrated with grooves 23L, 23M running in a direction
longitudinal to the reciprocating direction. In order to maximize
the cutting action, the length of the cutting edge is substantially
the maximum length extending from the trash bar 28 or the rear edge
23T at the rear to a position at the front edge or tip 23K of the
blade.
[0238] The fore-aft length of a blade has traditionally been in the
order of 1.75 inches from the front of the trash bar to the tip of
the section, or 2.2 inches from the front edge of the knife back to
the tip of the section.
[0239] In this new arrangement, the fore-aft length L of the blade
is increased substantially. Thus the length of the cutting edges of
each sickle blade or blade is greater than 2.2 inches. This can be
as much as 2.6 inches and can lie in the range 2.2 to 3.0
inches.
[0240] This also reduces the angle A of inward inclination of the
cutting edge from the typical 30 degrees relative to the center
line (an equilateral triangle) to an angle less than 30 degrees and
typically of the order of 15 degrees and in the range 15 to 30
degrees.
[0241] It is common practice for sickle blades to have the front
edge as a transverse straight edge in the order of 0.6 inches wide.
The wide tip has the potential for running down crop, thus leaving
long uncut stems. In the present invention the blade is designed
with a pointed tip or front apex 23K, thus eliminating the
problem.
[0242] The intention is therefore to provide a sickle blade which
is as pointed at the front apex 23K as reasonably practical. A
sharp point is difficult to obtain so that typically the front apex
23K is smoothly curved with a radius of curvature R of a curvature
circle C less than 0.5 inches thus defining the front apex 23K
which is sufficiently narrow to shed crop stalks to each side.
[0243] Each knife blade therefore has a front point portion in
front of the cutting edges which has side edges 23N, 23P converging
to front apex where the apex and the side edges are shaped and
arranged such that crop material engaging the point portion as the
point portion is moved forwardly in the crop is shed to one or
other side of the point portion for cutting and is not pushed
forwardly by the point portion.
[0244] While this is the optimum arrangement, a practical
construction may have a transverse width of a straight line across
the apex 23K which is much less than the conventional 0.7 inches
and is typically less than 0.25 inches. This narrow front edge is
selected to be sufficiently narrow so that crop is shed to either
side and not pushed forwardly as the blade moves forwardly.
[0245] The side edges 23N and 23P are inclined outwardly and away
from the apex at an angle A1 relative to the center line 23H of the
order of 35 degrees and certainly less than 45 degrees to the
center line 23H.
[0246] The characteristics of the blade defined above where it is
much narrower than conventional and significantly longer places
limitations on the shape and arrangement of the beveled and
serrated edges 23F, 23G.
[0247] Thus the beveled edges 23F, 23G are reduced in width at 23Q
as they approach the front edge pointed portion 23K at the apex 23X
leaving a strip 23R of the upper surface between the beveled edges
with parallel side edges of the strip 23R. Thus at this strip 23R
the beveled edge 23F, 23G becomes narrower and the grooves 23L, 23M
in the edge get shorter as the beveled edge approaches the front
pointed portion 23X of the blade. The beveled edges 23F, 23G and
the grooves 23L, 23M therein terminate at a position spaced from
the front apex 23K to define the arrow head shaped portion 23X in
front of the beveled edges which imparts sufficient strength to the
construction to allow the formation of the serrations.
[0248] The cutting efficiency and therefore stubble length are also
affected by the width of the cutting edge 15B, 15C of the ledger
surface 15A of the knife guard 15. Generally, the width W1 between
the edges 15B and 15C at the rear of the cutting edge on the guard
in the arrangement of the present invention is substantially
increased from the conventional width of the order of 1.0 inches.
Thus the width W1 of each guard at a position thereon aligned with
the rear end of the cutting edge of each blade is greater than 1.0
inches. The maximum width with a blade of 2.0 inches in width is
slightly less than that of the width of the blade or roughly 1.9
inches. Thus with a blade of this width, the width of the guards
can be as much as 1.9 inches and preferably lies in the range 1.2
to 1.9 inches. However where the blade is greater than 2.0 inches
in width, the guard has a width which is between 0.5 and 0.1 inches
less than the width of the blade. The bottom guard also tapers so
that its edges 15B and 15C lie closely adjacent the edges of the
blade when the blade and guard are in the aligned position at the
end of a stroke. Thus the angle of convergence of the edges 15A and
15B matches closely the angle A. This leaves a space S at the rear
of the guards 15 at the trash bar 28 to avoid pinching crop at this
location. This space S generally should be greater than 0.4 inches
and typically is of the order of 0.5 inches.
[0249] Thus the cutting system is carried so that it moves across
the ground either closely in contact with the ground as shown or at
a set cutting height. In both cases this determines a cutting
height or nominal cutting distance from the ground with is the
length of any crop stalk if cut efficiently and directly as it
reaches the location between the blade and ledger surface. In FIG.
2, the cutter bar rests on the ground at a skid plate 80 which
holds the ledger surface 15A at the height ND from the ground.
Typically this is of the order of 1.5 inches but this can be varied
slightly by changing the angle of the cutter bar about a transverse
axis by changing the angle of the header.
[0250] Turning now to FIGS. 7 and 8, the shape of the pointed guard
for use in the present invention in conjunction with the pointed
blade is shown and described in more detail as follows.
[0251] The knife guard 30 for use in a sickle cutting apparatus 10
includes the frame structure 11, guard bar 13, sickle bar 24 and
knife blades 23 as previously described. Each the knife blades 23
has a cutting surface 23D for passing across the ledger surface 15A
of the knife guards 151. Each of the knife blades has on first and
second sides first and second side cutting edges as previously
described to cooperate with shearing edges 152 of the guard guards
151.
[0252] The knife guard 151 includes a base portion 154 for mounting
on the cutter bar 13, a rear trash bar 28 in front of the base
portion 154 and at least one guard finger 153. In this embodiment
three fingers 153 are arranged in a row, where the finger or
fingers 153 are mounted on the base portion 154 so that the fingers
are arranged in a row along the cutter bar with a space 155 between
each finger and the next allowing crop to enter the space up to a
position of engagement with the rear trash bar 28.
[0253] The guard fingers have the upwardly facing ledger surface
15A with opposed side edges arranged to provide first and second
shearing edges. The guard fingers have a downwardly facing ground
engaging surface 156 shaped and arranged to provide protection for
stone engagement as the fingers slide over the ground. That is each
finger has sufficient strength to avoid breakage when impacting
stones and obstacles causing the cutter bar to rise if the impact
is sufficient and extends over sufficient number of guard fingers
to provide the lifting action. This shape of the ground engaging
surface is well known to persons skilled in the art and includes a
longitudinal rib which is generally triangular in cross-section on
the underside of the upper part containing the ledger surface. The
base of the rib thus forms an apex which runs over the ground to
prevent upward forces from snapping the guard finger at the ledger
surface.
[0254] An upstanding transverse shoulder 157 is provided at a front
edge of the ledger surface 15A and extends upwardly to a top
surface 158 of the finger where the shoulder terminates. Thus there
is no tang of conventional shape, that is no portion of the guard
extending rearwardly over the ledger surface 15A from the shoulder
158. Above the ledge surface therefore the knife blades are free
from confinement by a conventional tang as used in a conventional
pointed guard or by a cooperating upper guard finger of the type
used in a stub guard as described above.
[0255] A tip portion 159 in front of the ledger surface extends
forwardly from the shoulder 158 and defines a forwardmost generally
pointed tip 160 for engaging crop in front of the ledger surface
15A.
[0256] A length L1 of the ledger surface 15A from the trash bar 28
to the shoulder 157 is greater than 2.0 inches or more preferably
greater than 2.5 inches; and a length L2 of the tip portion 159
from the shoulder to the tip is less than 1.0 inch or more
preferably less than or equal to 0.75 inches.
[0257] As defined previously, a center line spacing between each
knife guard finger and the next is less than 3.0 inches and
preferably of the order of 2.0 inches.
[0258] As defined previously, a width of each guard finger at the
rear trash bar is greater than 1.0 inches and more preferably is
greater than 1.5 inches or equal to the maximum width which can be
obtained while leaving a space at the trash bar between the ledger
surfaces in the range 0.25 to 0.5 inch or the distance necessary to
avoid pinching of crop stalks between the ledger surfaces.
[0259] The side edges of the ledger surface 15A converge from the
trash bar 28 to the shoulder 15 at an angle A4 greater than 10
degrees and preferably of the order of 12 degrees to a line LR at
right angles to the trash bar or parallel to the center line CL.
The angle A5 of the side edges at the shoulder increases so that
the tip portion is shorter than would be the case if the angle A4
were continued up to the tip. However overall, it will be
appreciated that a line joining the rear end 161 of the side edge
151 of the ledger surface 15A and the tip 160 converges at an angle
greater than the 10 degrees of the side edge to a line at right
angles to the trash bar.
[0260] As the side edges converge at a relatively rapid angle from
the base to the tip, the ledger surface has a width W3 at the
shoulder 157 of less than 0.75 inches and preferably of the order
of 0.5 inches.
[0261] There is also provided a plurality of separate hold down
members 162 arranged to engage the blades at every third spaced
ones of the fingers. This has a base portion 163 mounted on the
cutter bar 13 and a finger portion 164 extending over the ledger
surface of one of the fingers 14A.
[0262] Generally the cutting speed can be increased as the speed of
the sickle is increased. One limitation for the sickle speed is the
stress that is induced in the sickle drive and the knife back from
the inertia loads resulting from the acceleration of the sickle at
the start of the stroke. These acceleration loads are proportional
to the stroke length and to the square of the sickle speed.
[0263] Therefore for the same acceleration loads, if the stroke is
decreased, the speed can be increased by an amount represented by
the following formula:
stroke2=stroke1.times.rpm1 2/rpm2 2
or in terms or speed:
rpm2=(stroke1.times.rpm1 2/stroke2) 0.5
[0264] For example for a typical 35 ft header and a single sickle
knife driven from one side, to achieve the same loads, if a sickle
with a 3 inch stroke, is run at 750 rpm, a sickle with a 2 inch
stroke can be run at 918 rpm for the same inertia loads.
[0265] This distance of the cutting stroke is less than 3.0 inches
and is more preferably of the order of 2.0 inches. Typically the
stroke can lie in the range 1.5 to 2.5 inches since this provides a
stroke length which allows an increase in the cutting reciprocation
rate of the sickle bar. This rate is preferably greater than 900. A
range of 900 to 1200 rpm is particularly suitable depending on the
length of the sickle.
[0266] Thus, the maximum sickle speed is affected by the length of
the sickle assembly. Generally headers vary in width from 15 ft to
45 ft and are generally available in single knife drive for widths
up to 40 ft. Therefore the length of the sickle can vary in length
from 7.5 ft to 40 ft.
[0267] Where the maximum speed for a 40 ft single knife drive (SK)
header with a 3.0 inch stroke might be set at 600 rpm, the maximum
speed for 15 ft double knife drive (DK) header might be set at 950
rpm.
[0268] Therefore in the case of a 2 inch cutting stroke, the
cutting speed of the new system will be increased by a percentage
(22.4%) over the current system. Depending on the length of the
sickle, for same inertia loads, the sickle speed can be
increased.
[0269] It has been found with the current cutting system, that the
increasing the knife speed beyond a speed of about 950 rpm (1900
strokes per minute) produces little improvement in cutting
performance. It is suspected that this is due to the blunt face of
the traditional knife blade or sickle section essentially creating
a wall that prevents crop from entering the cutting area.
[0270] Turning now to the cutting efficiency obtained by the above
geometry of cutting system relative to prior art arrangements shown
in FIGS. 9 to 13, a generic cutting system is shown in FIG. 2A to
show how cutting inefficiency and the associated increase in
maximum stubble length arises.
[0271] Thus in FIG. 2A, the cutting system is carried so that it
moves across the ground either closely in contact with the ground
as shown or at a set cutting height. In both cases this determines
a cutting height or nominal cutting distance ND from the ground
with is the length of any crop stalk if cut efficiently and
directly as it reaches the location between the blade and ledger
surface. In FIG. 2A, the cutter bar rests on the ground at a skid
plate 80 which holds the ledger surface 15A at the height ND from
the ground. Typically this is of the order of 1.5 inches but this
can be varied slightly by changing the angle of the cutter bar
about a transverse axis by changing the angle of the header.
[0272] Cutting inefficiency arises where stalk S1 engages a blunt
front edge 23BL of the knife blade 23 so that it is pushed
forwardly by the knife blade rather than reaching the side edges of
the knife blade where it can be cut.
[0273] In conventional thinking it is understood that this effect
is of little importance in that the knife blade is moving rapidly
side to side with the expectation that the sideways movement will
immediately cause any such crop to be shed to the side away from
the movement allowing it to be quickly cut.
[0274] However the analysis of the cutting system shows that, at
high ground speed, the forward movement has much more effect on the
crop than the sideways movement so that a band remains in contact
with the blunt front edge L. This crop is then pushed forward
forwardly and downwards without cutting until the crop is shed from
the blade at the location where the blade reverses at the next
guard finger, or at some point prior to that location, so that the
crop can then enter into the shearing action on the second side of
the blade.
[0275] Another analysis shows that, in each cycle of cutting crop,
the side of the blade which is not cutting will allow some stalks
to move to a position between and the guard as the blade moves away
from the guard sufficiently that the blade reaches a position in
which the stalks engage the trash bar. Again therefore these stalks
are pushed forwardly and downwards by the trash bar without cutting
until the blade comes back in the reverse direction to effect the
shearing action of the crop of that second side of the guard.
[0276] It is known that sideways movement of the crop also occurs
during cutting. That is each stalk is carried sideways by the
moving blade into the shearing action with the guard finger. This
amount of movement varies depending on the timing of the stalk
entering the area to be cut and engaging the blade and the side to
side position of the stalk as it enters the area. The amount of
sideways movement will of course increase the length of the stalk
as it is cut since the position of the cut is at a height of the
stalk greater than the distance ND from the ground. The analysis
herein does not take into account this sideways movement since the
maximum stalk length which can be obtained by the sideways movement
is always less than the maximum stalk length which is obtained by
the above described forward movement.
[0277] However another benefit of the wider guard fingers is that
the crop moves to the side by a shorter distance before
encountering the shearing action at the side edge of the guard.
[0278] It will be appreciated therefore that some stalks provide
stubble length of ND because they are cut without any forward
pushing movement and some stalks are pushed forward to a length L2
or L3 where the actual stubble length is equal to the hypotenuse of
the distance of forward movement before cutting occurs and distance
ND.
[0279] As shown as an example in FIG. 12A, the guard fingers 15,
knife blades 23 and the trash bar 28 are arranged so as to provide
a cutting action on the crop in which in a first cutting stroke,
each knife blade 23 moves across from one guard finger 151 to the
next 152 in a first direction 231 so as to cut crop located on said
first side of the knife blade 23 between the first cutting edge of
the knife blade and the side 15C of the next guard finger 152 by
the shearing action while leaving uncut crop located on the second
side of the knife blade. In a second cutting stroke, each knife
blade moves across from the next guard finger 152 to said one guard
finger 151 in a second direction opposite to direction 231 so as to
cut crop located on the second side of the knife blade between the
second cutting edge of the knife blade and the guard finger 151 by
the shearing action. The cutting action includes the previously
uncut crop located on the first side of the blade 23, while leaving
uncut crop located on the second side of the knife blade.
[0280] Turning now to FIGS. 9, 10 and 11 there is shown a stub
guard system similar to that previously described and shown in
FIGS. 1 and 2 and including many of the features previously defined
above. In this embodiment, however the system is a 3 inch system so
that the tip to tip spacing of the blades and guards is 3 inches
and the stroke of the sickle knife drive is also 3 inches so that
the blades reciprocate back and forth between a first points
aligned with one guard to a point aligned with the next. Thus as
shown in the stub guard system of these figures there is provided a
bottom guard 50, a top hold down 51 and a set of blades 52 carried
on the reciprocating sickle bar.
[0281] In this embodiment the shape and arrangement of these
components is substantially as previously described except that
each guard element has only two fingers so that the pair of fingers
of the bottom guard underlie the pair of fingers of the top hold
down.
[0282] The pair of fingers of the top hold down are individually
adjustable so as to change the spacing SP between the finger 51A
and the ledger surface of the guard finger 50A using the
construction as shown and described in U.S. Pat. No. 9,622,405
(Talbot) assigned to the present applicant and issued Apr. 18
2017.
[0283] As best shown in FIGS. 10 and 11, the guard fingers 50A and
blades 52 have lengths from the cutter bar arranged such that a
forwardmost tip 50B of the guard finger 59A is forward of the tip
52B of the blade 52 and a forwardmost tip 51B of the hold down
finger 51A is rearward of the tip 52B of the blade 52.
[0284] Preferably the tip of the guard finger is longer than the
tip of the blade by a distance up to 6.0 mm and preferably of the
order of 3.0 mm.
[0285] Preferably the tip of the hold down finger is shorter than
the tip of the blade by a distance in the range 1.5 to 10.5 mm and
preferably of the order of 5.0 mm.
[0286] That is the fingers form a conventional stub guard where
there is no component of the lower stub guard finger which is above
the ledger surface. However in this arrangement the tip 50B is
located just in front of the tip of the blade rather than behind
the tip of the blade as would be conventional. It has been found
that this arrangement allows the clearing of the blade tip in tough
cutting conditions as does a normal stub guard system but in
addition the slightly longer finger cooperates with the pointed
blade system described in detail herein where there is an
additional point portion in front of the conventional beveled side
cutting edges of the blade. This may improve the cutting action and
may protect the point against damage while still allowing the
clearing action of the crop from the front of the guards and blade
which is obtained using a stub guard system.
[0287] Turning now to FIGS. 12 to 15 there is shown a pointed guard
system similar to that previously described and shown in FIGS. 7
and 8 above.
[0288] In this arrangement however the pointed guard arrangement 60
includes a tang portion 62 overlying the ledger surface 61 so that
the blade 52 passes through a slot 63 defined between the underside
65 of the tang portion and the ledger surface. The tang portion is
connected to the tang portion in front of the slot by a pointed
portion 64 of the pointed guard which converges to a front tip in
front of the forward tip of the blade. The tang portion 62 extends
rearwardly over the ledger surface from the point portion 64 to a
rear edge 65 of the tang portion. As shown in FIG. 12, the rear
edge 65 is aligned with a trash bar 66 of the guard which extends
outwardly to each side of the ledger surface. As described above
therefore the trash bar 66 forms or defines a transverse line
across the ledger surface which constitutes the line of the
rearmost cutting action of the blade on the ledger surface. This
line is coincident with the rear edge of the sharpened cutting edge
of the blade.
[0289] As shown in FIG. 12, the width of the tang portion at the
rear edge 65 is equal to the width of the ledger surface of the
guard at this point which is greater than 1.2 inches and more
preferably of the order of 1.5 inches. This wider width of the
guard and tang portion than is conventional in systems of this type
provides an improved cutting action with the blade as described in
more detail above. This wider width of the tang portion also
operates to provide improved control over the blade as it
reciprocates through the slot. Even though the blade is contacted
by a hold down finger 68 between the guards, there is a tendency
for it to rise so that the increased width of the tang portion
ensures that it is properly guided into the slot as it approaches
the slot from one side. Thus a width WT of the tang portion across
the guard finger at the rear end of the tang portion is greater
than 1.2 inches and more preferably 1.5 inches.
[0290] As best shown in FIG. 15, the lower surface 69 of the tang
portion includes a first portion 70 extending along the slot from
the front of the blade to a junction point 72 where the first
portion joins a second portion 71. The lower surface of the tang
portion thus includes a first portion adjacent the tip portion
which is generally parallel to the ledger surface and a second
portion adjacent the rear edge which is inclined at an angle away
from the ledger surface. The first portion is planar and parallel
to the plane of the ledger surface. The second portion is also
planar and is inclined upwardly away from the ledger surface from a
transverse line at the junction 72 up to the rear tip 65. This
shape of the slot surface of the underside of the tang portion
provides effective control of the blade movement across the ledger
surface while also allowing the guard to be disconnected from the
mounting bolts and tilted about the line at the junction 72 to lift
the tip upwardly and to lower the rear edge downwardly to allow the
guard to be pulled out forwardly with the blade and sickle bar 76
in place. This allows the rear of the guard to clear the sickle bar
to move forwardly away from the cutter bar 77.
[0291] In one arrangement, the second portion of the tang portion
at the inclined angle is obtained by bending the tang upwardly at
the junction line 72 relative to the first portion. This bending
action occurs at the arrow 79 and results in a situation where both
the upper and lower surfaces are inclined cause by the bending of
the material forming the tang portion.
[0292] As an alternative, the second portion of the tang portion
tapers in depth TD from the lower surface to an upper surface
thereof toward the rear edge 65 thereof.
[0293] As shown in FIG. 13, a length along the tang portion of
second portion 72 from the rear edge 65 to the first portion at the
junction 72 is shorter that a length of the first portion 70 to the
tip portion 64. Thus the main body of the slot is parallel to
properly guide the blade and only a relatively short part of the
slot is inclined upwardly.
[0294] Turning now to FIG. 16, there is shown a blade 52 for use
with the systems of FIGS. 9 and 12. It will be noted that the blade
member which has a base portion 80 to attach to the sickle bar 76
forms a single blade and not a double blade arrangement as shown
and described previously herein. Each blade is therefore a separate
component from each of the other blades with two side edges 81, 82
so that the side edges of each blade lie immediately adjacent the
side edges of the next adjacent blades when fastened to the sickle
bar 76.
[0295] The base portion 80 has two countersunk holes 83 connected
to slots 84 which communicate with the rear edge 85 of the mounting
portion. This allows the blade to be pulled from the sickle bar 76
simply by loosening mounting bolts 86 (FIG. 13) sufficiently to
allow the bolts to slide along the slots. This arrangement is
described in more detail in U.S. Pat. No. 8,893,462 (Talbot) issued
Nov. 25 2014 and assigned to the present applicant, the disclosure
of which is incorporated herein by reference.
[0296] Each knife blade has a front point portion 87 in front of
the side cutting edges 88, 89 which front point portion has side
edges 90, 91 converging to a front apex 92. This construction is
substantially as previously described with the exception that the
wider blade of 3 inches rather than the previous shown 2 inches
provides a shorter and less pronounced point portion. However the
point portion has the same construction relative to the beveled and
serrated side edges as previously described. Also as shown in FIG.
16, a length LB1 of each knife blade from the transverse line TL to
the forwardmost tip 92 of the knife blade is greater than 2.2
inches and preferably greater than 2.5 inches. As described before,
the transverse line TL coincides with or is defined by the front of
the trash bar and the rear of the beveled edges which form the
rearmost line of cutting action of the blade on the guard ledger
surface.
[0297] Also as shown in FIG. 16, each blade has a cut out opening
93 through the blade extending from a rear edge 99 of the opening
adjacent to but spaced from a rear edge 85 of the blade toward the
tip of the blade. The cut out opening 93 has a rear edge 99
parallel to a rear edge 85 of the blade, two side edges 94, 95
substantially parallel at right angles to the rear edge 99 and two
converging edges 96, 97 extending from the side edges to a forward
apex 98. This shape takes out an amount of the material of the
blade which ensures that the blade has approximately the same
weight as a conventional 3 inch blade of a conventional length
rather than the increased length herein. The shape and location of
the cut out opening ensures that the material is removed without
compromising the strength of the blade to meet its required
loadings form the cutting action. The cut out opening does not
interfere with the sliding action of the hold down fingers over the
upper surface.
* * * * *