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| United States Patent
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5,496,043 |
| Ester |
March 5, 1996 |
Over the arrow shaft broad head
Abstract
An overshaft hunting broadhead is used to duplicate practice
arrow balance point and flight characteristics. Assuming the optimal
balance point of the practice arrow is in accord with manufacturer's
recommendations, removal of the practice arrow point and converting
to an overshaft hunting broadhead will duplicate the balance point,
weight and flight characteristics of the arrow the archer has become
accustomed to while practicing. The arrow shaft enters the ferrule
of the overshaft hunting broadhead. The ferrule is free to rotate
about the axis of the arrow's shaft to be properly positioned, then
securely tightened by rotating the arrow tip. The ferrule is
equipped to hold cutting edges (razors). The ferrule is coupled
securely to the end of the arrow shaft by a hunting point tip that
couples into a standard threaded insert in the arrow shaft. The
broad head ferrule will not experience the load at impact that is
typical to existing broad head styles due to the reinforcement of
the arrow shaft by an arrow shaft insert located concentrically and
internally beneath the overshaft broadhead ferrule.
| Inventors: |
Ester; Lee (Chandler,
AZ) |
| Appl. No.:
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07/926,502 |
| Filed: |
August 7, 1992 |
| Current U.S.
Class: |
473/584 |
| Current
International Class: |
F42B
6/08 (20060101); F42B 6/00 (20060101); F42B 006/08 () |
| Field of
Search: |
273/416,419-422
|
References Cited
[Referenced By]
U.S. Patent
Documents
Other References
Archery, Apr. 1978, p. 14, Snuggers..
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Primary Examiner: Shapiro; Paul E.
Attorney, Agent or Firm:
Stoneman; Martin L.
Claims
That which is claimed is:
1. In an arrow having an arrow shaft with a threaded insert at a
first end thereof, said insert being internal to and concentric with
said shaft, and an arrow tip, having a threaded extension, thread
coupled to said insert, the improvement comprising:
a broad head cutting blade;
means coupled to said shaft for coupling said broad head cutting
blade to said arrow shaft at first end of said shaft and above the
outer surface of said shaft;
wherein said means for coupling said broad head cutting blade to
said arrow shaft further comprises means coupled to said shaft for
lockingly, removably coupling said broad head cutting blade to said
shaft; and
wherein said means for lockingly, removeably coupling said broad
head cutting blade to said shaft comprises locking means coupled to
said shaft in cooperation with said arrow tip whereby the threaded
rotation of said tip functions to lock and release said broad head
cutting blade from its coupling with said shaft; and
wherein said locking means comprises means coupling said arrow tip,
said shaft, and said cutting blade for drawing said cutting blade
into locked, intimate contact with said outer surface of said shaft
as said tip is threadedly rotated into said threaded insert and for
releasing said locked, intimate contact as said tip is threadedly
rotated out of said threaded insert.
2. The improvement of claim 1 wherein said means for drawing said
cutting blade into locked intimate contact with said shaft further
comprises means for lockingly positioning said cutting blade at
selected radial angles with respect to said shaft.
3. The improvement of claim 2 wherein said means for lockingly,
removably coupling said broad head cutting blade to said shaft
comprises:
a ferrule rotatingly encompassing said first end of said arrow shaft
and extending a selected length away from said first end along said
arrow shaft;
said broad head cutting blade removably coupled to said ferrule; and
extending along said ferrule away from said first end of said arrow
shaft; and
means for lockingly coupling said blade and said ferrule to said
shaft at a selected radial angle to said shaft.
4. In an arrow having an arrow shaft with a threaded insert at a
first end thereof, said inert being internal to and concentric with
said shaft, and an arrow tip, having a threaded extension, thread
coupled to said insert, the improvement comprising:
a board head cutting blade;
means coupled to said shaft for coupling said broad head cutting
blade to said arrow shaft at said first end of said shaft and above
the outer surface of said shaft;
wherein said means for coupling said broad head cutting blade to
said shaft comprises:
a ferrule rotatingly encompassing said first end of said arrow shaft
and extending a selected length away from said first end along said
arrow shaft;
said broad head cutting blade removably coupled to said ferrule and
extending along said ferrule away from said first end of said arrow
shaft; and
means for lockingly coupling said blade and said ferrule to said
shaft at a selected radial angle to said shaft;
wherein said means for lockingly coupling said blade and said
ferrule to said shaft at a selected radial angle comprises
compression means couple to said arrow tip for exerting a
compressive force on said broad head cutting blade for lockingly
positioning said as ferrule and said cutting blade on said arrow
shaft as said arrow tip is threadedly rotated into said insert; and
wherein said ferrule has an outer wall with a longitudinal slot
therethrough, said broad head cutting blade coupled within said slot
and thereby in contact with the surface of said arrow shaft.
Description
TECHNICAL FIELD OF THE INVENTION
The invention relates to the field of archery. In particular, the
invention relates to the means and particular method of attaching a
hunting broad head to an arrow shaft for improved performance in
arrow flight characteristics.
PRIOR BACKGROUND ART
Arrow shafts, in general, are equipped with replaceable arrowheads.
There are many reasons for this, not the least of which is to permit
the ready replacement of a damaged arrowhead while an archer is in
the field. More frequently, an archer is prompted to change
arrowheads when he changes the type of shooting with which he is
involved. Thus, the archer may have been shooting at straw targets
or the like, using standard arrow points, and decide to mount
hunting heads on each of his arrow shafts so that he might partake
of the hunt.
Assuming that the archer has been having success using an arrow
point of a given weight, he will, in all likelihood, install a
hunting head of the same weight. Having done so, it may come as a
surprise to the archer to find that the flight of the arrow is
erratic; and, the accuracy he has gained in practice with the arrow
point on his shaft is no longer in evidence when shooting with a
hunting head.
Hunting heads (broadheads) are designed to cut, producing
hemorrhaging in body. Hunting heads typically carry many different
styles of cutting edges (razors), some fixed, some folding out of
the hunting head ferrule body at impact. Although the heads differ
in cutting configuration and design, they each have a means for
coupling to the end of an arrow shaft. Typically, an existing
hunting head has a threaded shaft protruding rearward from its end.
The arrow has an internally threaded insert at it's forward end for
receiving this threaded shaft. The threaded insert is commonly glued
into the arrow shaft's leading end.
Typical arrow shafts are hollow in design. However, there are arrows
used having shafts that are of solid construction, usually wood.
Typical fittings are readily available to convert this type of arrow
shaft to allow for threaded arrow points.
When inserted and rotated securely into the arrow insert, current
hunting broad heads will terminate rotation at random radial
positions; and, because of their length they increase the arrow's
overall assembled length. The uncontrolled radial positioning of the
broad head and the increased assembled length is undesirable.
In current, common practice, the archer wants to assemble his
broadheaded arrow in a manner that maximizes cutting blade clearance
on the bow and allow blade alignment with the flights on the arrow.
In the prior art, this could only be achieved by successively
installing many different hunting heads to a single arrow shaft
hoping that one would couple at the correct radial position. Most
commonly however, an archer, in frustration, will remove the arrow
head and insert from the shaft and glue the assembly to the shaft in
proper orientation. This marriage of the glued assembly to the arrow
shaft to achieve correct radial alignment makes the arrow, insert
and hunting head inseparable and dangerous to transport to the hunt
location.
Although the overall weight of the arrow may not be changed by
changing from arrow point to broadhead hunting point, the archer may
not realize that the overall geometry of the arrow has been
sufficiently changed to move the balance point and inpair the flight
characteristics of the arrow to which he had become accustomed.
The balance point of the arrow is of critical importance. In tests
of the accuracy of arrows, both actual and computer simulated
testing, it has been shown that arrows are most accurate when they
are seven to ten per cent (front of center) nose heavy. While many
archers are familiar with this rule, they are limited as to where
the balance point of their arrow will fall based on their selection
of a particular broadhead hunting point. As is many times the case,
the arrow's balance point will not be the same as when a practice
arrow point was attached.
It is the objective of the present invention to enable an archer to
exactly duplicate his arrow's finished length, weight, balance point
and flight characteristics when changing from practice arrow points
to broadhead hunting points, within the established standards set by
the manufacturers of the various arrow shafts and devices. This will
be accomplished by utilizing a broadhead hunting point that weighs
the same (or approximately the same) as the practice arrow point,
and, will duplicate the overall assembled length of the practice
arrow when the invention disclosed herein is utilized. Another
objective of the invention will allow the ready alignment of the
arrow flights to the broadhead razors.
SUMMARY DESCRIPTION OF THE INVENTION
The invention represents an improvement in ar arrow which has an
arrow shaft with a threaded insert at a first end thereof. The
insert is internal to and concentric with the shaft. There is an
arrow tip, having a threaded extension, thread coupled to the
insert. The improvement includes a broad head cutting blade. Means
are coupled to the shaft for coupling the broad head cutting blade
to the arrow shaft at first end of the shaft and above the outer
surface of the shaft.
The means for coupling the broad head cutting blade to the arrow
shaft further comprises means coupled to the shaft for lockingly,
removably coupling the broad head cutting blade to the shaft. This,
in turn is made up of locking means coupled to the shaft in
cooperation with the arrow tip whereby the threaded rotation of the
tip functions to lock and release the broad head cutting blade from
its coupling with the shaft.
The locking means itself comprises means coupling the arrow tip, the
shaft, and the cutting blade for drawing the cutting blade into
locked, intimate contact with the outer surface of the shaft as the
tip threadedly rotated into the threaded insert. The locking means
also releases the locked, intimate contact as the tip is threadedly
rotated out of the threaded insert.
The means for drawing the cutting blade into locked intimate contact
with the shaft further comprises means for lockingly positioning the
cutting blade at selected radial angles with respect to the shaft.
In a presently preferred embodiment, the means for lockingly,
removable coupling the broad head cutting blade to the shaft
comprises a ferrule rotatingly encompassing the first end of the
arrow shaft and extending a selected length away from the first end
along the arrow shaft to the broad head cutting blade is removably
coupled to the ferrule and it extends along the ferrule away from
the first end of the arrow shaft. Included are means for lockingly
coupling the blade and the ferrule to the shaft at a selected radial
angle to the shaft.
The means for lockingly coupling the blade and the ferrule to the
shaft at a selected radial angle comprises compression means coupled
to the arrow tip to exert a compressive force on the broad head
cutting blade to lockingly position the ferrule and the cutting
blade on the arrow shaft as the arrow tip is threadedly rotated into
the insert. The ferrule has an outer wall with a longitudinal slot
therethrough. The broad head cutting blade is coupled within the
slot and thereby comes into contact with the surface of the arrow
shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the evershaft broadhead invention installed on an
arrow shaft.
FIG. 2 establishes arrow balance point and calculation
considerations defining the optimum balance region.
FIGS. 3A and 3B show the bending and wobbling phenomena typical to
arrow flight.
FIGS. 4A, 4B and 4C illustrate the assembled lengths gained with a
typical arrow shaft equipped with various arrow tips. FIG. 4A
illustrates the overshaft broadhead invention and arrow assembly.
FIG. 4B illustrates a typical prior art broadhead and arrow
assembly. FIG. 4C illustrates a typical prior art target point and
arrow assembly.
FIG. 5 displays the radial adjustment capabilities of the overshaft
broadhead when installed on an arrow shaft.
FIG. 6 is an exploded view of the overshaft broadhead and partial
view of the arrow shaft and threaded insert.
FIG. 7 is a sectional view of the overshaft broadhead when installed
on a typical arrow shaft.
DETAILS OF BEST MODE FOR CARRYING OUT THE INVENTION
For purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiments illustrated
in the drawings and specific language will be used to describe same.
It will never the less be understood that no limitation of the scope
of the invention is thereby intended. Alterations and modifications
of the illustrated device are contemplated, as are such further
applications of the principles of the invention as would normally
occur to one skilled in the art to which the invention pertains.
FIG. 1 illustrates arrow assembly 7 with the invention, broadhead 7,
made up of components: ferrule 1, razor ring 2, razor(s) 3, razor
retaining washer 4 and hunting point tip 5 installed on typical
arrow shaft 13.
FIG. 2 illustrates the suggested actual values for establishing
balance point on an arrow of length L. Arrow and equipment
manufacturer's are presently suggesting that, in order for the
flight of an arrow to be accurate, the arrow should be between (aL)
and (bL) (region between designated "X") front heavy calculated from
the overall length L of arrow 7. Arrow 7, being assembled with
typical prior art target point 12, threaded arrow insert 9, flights
10, hock 11 and arrow shaft 13 has a given balance point and mass
weight due to it's geometry of the assembled components. Assuming
that assembled arrow 7 balances in the optimum region "X", any
changes to nock 11, flights 10 and/or a particular prior art
broadhead 8 or prior art arrow point 12, the overall length L of the
arrow may possibly remain the same, however, in all likelihood the
previous length L will change by some length and balance point will
change at well. When length L of the assembled arrow 7 channels so
will the region in which the balance point had been established.
This change in the previous balance point, will cause assembled
arrow 7 (with broadhead 8 installed) to act differently in flight
when compared to assembled arrow 7 with arrow point 12 installed,
even though broadhead 8 and arrow point 12 may weigh the same. This
change in balance region resulting from an overall change in
assembled arrow length (L.+-.M) brings on different bending
characteristics in assembled arrow 7 when shot from bow 6.
FIGS. 3A and 3B display the bending and wobbling phenomena typical
of arrow 7's flight. Bending, wobbling and porpoising (a result of
column buckling, due to the extreme acceleration arrow 7 experiences
when shot from bow 6), must be consistent from arrow to arrow within
an archer's usage. Changing from one point style to a different
point style may negatively affect repeatable accuracy for which the
archer has become accustomed. (Example, FIG. 2, broadhead 8 removed
and arrow point 12 installed.)
In FIG. 4A, the invention, overshaft broadhead 14, is installed on
raw arrow shaft 13 resulting in arrow length L. This length L,
critical to repeatable balance point and down range accuracy, is
duplicated in FIG. 4C with prior art arrow point 12 installed on the
same raw arrow shaft 13. In FIG. 4B, prior art broadhead 8, when
installed on raw arrow shaft 13, increases the overall length of the
assembled arrow to a length L+M and typifies the current state of
the art in broadhead designs as they relate to arrow assembly
lengths.
In FIG. 5, the invention, overshaft broadhead 14, includes a
threaded hunting point tip 5 used to secure the over shaft broadhead
14 assembly to arrow shaft 13. Since the broadhead ferrule 1 is
independent of threaded hunting point tip 5, overshaft broadhead
ferrule assembly can be rotated three hundred sixty degrees about
the axis of arrow shaft 13 and be exactly located prior to locking
it into position. This allows the overshaft broadhead 14 to be
radially adjusted to whatever location razors 3 may need to be so as
to maximize clearances of razors 3 when arrow 7 is shot from bow 6
(see FIG. 3), or, as is many times the case, lined up with razors 3
aligned with arrow flights 10. Threaded hunting point tip 5 passes
through the razor retaining washer 4, through overshaft broadhead
ferrule 1 and into arrow insert 9, (see FIG. 6) and, when rotated to
tighten, draws itself (5) into the arrow shaft's threaded insert 9,
to securely couple overshaft roadhead ferrule 1, razors 3 and the
hunting point tip 5 securely in position.
As seen in FIGS. 1, 6 and 7, razors 3 of the overshaft broadhead are
held in position by means of slots 22 cut longitudinally through the
overshaft broadhead ferrule 1 so that razors 3, when installed, will
come into contact with the outside surface 17 of arrow shaft 13. The
rearward edge 18 of each of razors 3 is tapered to allow a closing
down, collet effect to occur as the razors 3 are axially tightened.
The front, edge 20 of each of razors 3 is in contact with razor
retaining washer 4, located between threaded hunting point tip 5 and
broadhead ferrule 1. Razor retaining washer 4 will contact the front
of the razors 3, and, when threaded hunting point tip 5 is
tightened, will produce an axial load on razors 3. Razor ring 2,
contained over and to the rear of broadhead ferrule 1: allows the
razors 3 to slide towards the axis of arrow shaft 13 when tip 5 is
tightened. Likewise, razor retaining washer 4, allows the razors 3
to slide towards the axis of arrow shaft 13 when tip 5 is tightened.
Threaded arrow insert 9 located within arrow shaft 13 provides the
necessary means to support and strengthen the outside diameter of
arrow shaft 13 when in contact with the razors 3.
FIG. 7 is a detailed sectional view of the invention, overshaft
broadhead 14, assembled and installed on raw arrow shaft 13. (For
clarity, only one razor 3 is shown installed). Raw arrow shaft 13 is
a thin walled tube of length L. Internally threaded arrow insert 9
slides with an interference fit into raw arrow shaft 13. Broadhead
ferrule 1 slides over arrow shaft 13. Razor 3 is installed in slot
22 in ferrule 1. Razor 3 contacts the outside surface of arrow 13
along edge 17. Hunting point tip 5 is threaded, and passes through
razor retaining washer 4 to screw into threaded arrow insert 9.
Rotation of tip 5 (when applied to achieve final securement) creates
an axial load on razor 3 at contact areas 15 and 16. A description
of both contact areas follows. At contact area 15, a radius on
leading edge 20 (of razor 3) is in contact with tapered edge 19 (of
razor retaining washer 4). Contact area 16, edge 18 (of razor 3) is
in contact with corner 21 of razor ring 2. When tip 5 is rotated to
tighten, an axial force created in contact areas 15 and 16 will
cause razor 3 to slide at the inclined surfaces edges 18, 19 and 20
towards the center of axis of arrow 13 and bear forcibly against
edge 17 in contact with the arrows surface regardless of the radial
position of ferrule 1 about arrow shaft 13. Thus, one can readily
align the razors to maximize bow clearance and to achieve alignment
to the arrow's flights.
In using the invention to achieve the stated objectives, the archer
can exactly duplicate his arrow's finished length, weight, balance
point and obtain the feature to readily align the invention to his
arrow flights. This will allow the archer to achieve exact
repeatable arrow flight that he has become accustomed to while using
his practice arrows. The invention is so designed as to not increase
the arrow's assembled length. This is accomplished by inserting the
arrow shaft into the invention's ferrule body and securing it to the
arrow shaft with a threaded tip. This effectively prevents a change
in length to the lever arm that the tip's weight is acting upon. The
weight of the invention duplicates the target point weight the
archer has selected, but, is appropriately distributed to promote
the same balance point as found in the practice arrow. The added
feature of the invention which allows it to be readily aligned to
the arrow's flights, or, to achieve adequate bow clearances, greatly
simplifies the methods currently used. Assuming that the archer has
been having success using an arrow point of a given weight, he will,
in installing a like weight broadhead per the invention, see the
same performance in arrow flight that he has become accustomed to.
Those skilled in the art will conceive of other embodiments of the
invention which may be drawn from the disclosure herein. To the
extent that such other embodiments are so drawn, it is intended that
they shall fall within the ambit of protection provided by the
claims herein.
Having described the invention in the foregoing description and
drawings in such clear and concise manner that those skilled in the
art may readily understand and practice the invention,
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