U.S. patent application number 13/479650 was filed with the patent office on 2012-09-13 for solid state processing of hand-held knife blades to improve blade performance.
This patent application is currently assigned to DIAMOND BLADE, LLC. Invention is credited to Charles E. Allen, Richard A. Flak, Scott M. Packer, Hobie Smith, Russell J. Steel.
Application Number | 20120227546 13/479650 |
Document ID | / |
Family ID | 35064256 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120227546 |
Kind Code |
A1 |
Allen; Charles E. ; et
al. |
September 13, 2012 |
SOLID STATE PROCESSING OF HAND-HELD KNIFE BLADES TO IMPROVE BLADE
PERFORMANCE
Abstract
A system and method for friction stir processing of a hand-held
cutting edge, wherein friction stir processing techniques are used
to modify the properties of the hand-held cutting edge to obtain
superior edge retention and superior resistance to chipping of the
hand-held cutting edge.
Inventors: |
Allen; Charles E.; (Denison,
TX) ; Flak; Richard A.; (Provo, UT) ; Packer;
Scott M.; (Alpine, UT) ; Steel; Russell J.;
(Salem, UT) ; Smith; Hobie; (Houston, TX) |
Assignee: |
DIAMOND BLADE, LLC
Denison
TX
MEGASTIR TECHNOLOGIES LLC
Provo
UT
|
Family ID: |
35064256 |
Appl. No.: |
13/479650 |
Filed: |
May 24, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11090909 |
Mar 24, 2005 |
8186561 |
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13479650 |
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60556050 |
Mar 24, 2004 |
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60573707 |
May 21, 2004 |
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60637223 |
Dec 17, 2004 |
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60654608 |
Feb 18, 2005 |
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Current U.S.
Class: |
76/104.1 |
Current CPC
Class: |
C21D 9/18 20130101; C22F
1/00 20130101; B23P 15/40 20130101; B23K 20/1225 20130101; B23D
63/12 20130101; C23C 26/00 20130101; B23P 15/28 20130101; B23K
20/1275 20130101 |
Class at
Publication: |
76/104.1 |
International
Class: |
B21K 11/00 20060101
B21K011/00 |
Claims
1-20. (canceled)
21. A method for creating a metallic blade for a hand-held knife,
said method comprising: providing a high melting temperature
metallic workpiece that is to be formed into a hand-held knife
blade; providing a friction stir processing tool that includes a
higher melting temperature material than the workpiece on a portion
thereof; and friction stir processing at least a portion of the
workpiece using the tool to thereby modify characteristics thereof
to form a friction stir processed region of the workpiece; and
forming the blade of the hand-held knife blade from the workpiece,
such that a cutting edge of the blade is formed in the friction
stir processed region such that the cutting edge comprises the
friction stir processed material and will resist fracturing after
repeated impacts thereon while also retaining a shaving sharpness,
and wherein the cutting edge will retain these characteristics
longer than a cutting edge on a conventional blade unmodified by
friction stir processing which exhibits an inverse relationship
between impact resistance and toughness in comparison to wear
resistance and hardness.
22. The method as defined in claim 21, wherein forming the blade of
the hand-held knife blade from the workpiece comprises forming the
blade such that a portion of the blade other than the cutting edge
is formed in a portion of the workpiece outside the friction stir
processed region of the workpiece.
23. The method as defined in claim 21, wherein forming the blade of
the hand-held knife blade from the workpiece comprises grinding the
workpiece to form a blade after friction stir processing.
24. The method as defined in claim 21, wherein the method further
comprises the step of causing a substantially solid state
transformation without passing through a liquid state of the base
material.
25. The method as defined in claim 21, wherein providing the high
melting temperature base material includes selecting the high
melting temperature base material from the group of high melting
temperature materials including ferrous alloys, non-ferrous
materials, superalloys, titanium, cobalt alloys typically used for
hard-facing, and air hardened or high speed steels.
26. The method of claim 21, wherein selecting the high melting
temperature base material from the group of high melting
temperature materials including ferrous alloys, non-ferrous
materials, superalloys, titanium, cobalt alloys typically used for
hard-facing, and air hardened or high speed steels comprises
selecting ATS 34 steel or D2 steel.
27. The method as defined in claim 21, wherein the method further
comprises the step of synthesizing a new material from solid state
processing of the workpiece, wherein the new material has
characteristics that are advantageous to a hand-held knife
blade.
28. The method as defined in claim 21, wherein friction stir
processing at least a portion of the workpiece using the tool to
thereby modify characteristics thereof to form a friction stir
processed region of the workpiece further comprises providing an
additive material; and friction stir mixing the additive material
into the workpiece to thereby modify at least one characteristic of
the workpiece base material.
29. The method as defined in claim 28, wherein providing an
additive material comprises providing diamond particles, carbide or
stainless steel.
30. The method as defined in claim 21, wherein the method further
comprises the step of modifying a microstructure of the
workpiece.
31. The method as defined in claim 30, wherein the method further
comprises the step of modifying a macrostructure of the
workpiece.
32. The method as defined in claim 31, wherein modifying the
microstructure includes increasing toughness of the base
material.
33. The method as defined in claim 31, wherein modifying the
microstructure includes increasing or decreasing hardness of the
base material.
34. The method as defined in claim 31, wherein modifying the
microstructure includes increasing or decreasing strength of the
workpiece.
35. The method as defined in claim 31, wherein modifying the
microstructure includes friction stir processing the workpiece to
thereby obtain superior edge retention on the hand-held knife blade
that is formed therefrom.
36. The method as defined in claim 31, wherein modifying the
microstructure includes friction stir processing the workpiece to
thereby obtain superior resistance to chipping on the hand-held
knife blade that is formed therefrom.
37. The method as defined in claim 21, wherein providing the
friction stir processing tool further includes the step of
providing the friction stir processing tool having a shank, a
shoulder and a pin.
38. The method as defined in claim 37, wherein friction stir
processing at least a portion of the workpiece using the tool to
thereby modify characteristics thereof to form a friction stir
processed region of the workpiece comprises friction stir
processing using a surface area of the pin to process at least a
portion of the surface of the workpiece without plunging the pin
into the workpiece.
39. The method as defined in claim 37, wherein friction stir
processing at least a portion of the workpiece using the tool to
thereby modify characteristics thereof to form a friction stir
processed region of the workpiece comprises friction stir
processing with at least a portion of the pin plunged into the
workpiece.
40. The method as defined in claim 21, wherein providing the
friction stir processing tool further comprises providing a
friction stir processing tool having a shank and a shoulder, but
having no pin.
41. The method as defined in claim 21, wherein providing a friction
stir processing tool that includes a higher melting temperature
material than the workpiece on a portion thereof comprises
providing a friction stir processing tool including a superabrasive
material.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This document claims priority to and incorporates by
reference all of the subject matter included in the provisional
patent applications having docket number 2992.SMII.PR with Ser. No.
60/556,050 and filed Mar. 24, 2004, docket number 3043.SMII.PR with
Ser. No. 60/573,707 and filed May 21, 2004, docket number
3208.SMII.PR with Ser. No. 60/637,223 and filed Dec. 17, 2004, and
docket number 3212.SMII.PR with Ser. No. 60/654,608 and filed Feb.
18, 2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to hand-held knives. More
specifically, the invention relates to a method for improving
characteristics of hand-held knife blades.
[0004] 2. Description of Related Art
[0005] When discussing the present invention, the term "knife
blade" or "blade" will be most often used to refer to cutting edges
of hand-held instruments to which this invention is applicable. It
should be understood that the present invention applies to any type
of hand-held instrument having a cutting edge where sharpness, the
ability to remain sharp, and resistance to chipping are important
features of the hand-held cutting edge. Examples of applicable
instruments include hunting knives, pocket knives, hatchets,
cleavers, axes, scissors, box cutters, craft blades and the
like.
[0006] Sharpness and the ability to retain a razor sharp edge are
two important criteria for a hand-held knife blade. When hand-held
knives are used to cut wire, bone, or any other hard or abrasive
material, it is understood to be abuse. Abuse often results in the
blade of the hand-held knife failing by becoming dull and/or
developing chips. A hand-held blade that can withstand abuse and
yet retain a sharp edge is a most desired characteristic that has
long been sought after by those in the business of manufacturing
hand-held knife blades. However, because impact resistance and
toughness is inversely related to wear resistance and hardness for
most hand-held blade materials, different hand-held knife blades
are typically required for impact applications, such as chopping
through bone and hard wood without chipping, and sharpness
applications, such as cutting through animal flesh, and the
like.
[0007] Certain products such as large cleavers and hatchets have
been specifically designed to withstand the impact of cutting
through hard dried wood and especially bone without the edge
chipping. However, conventionally, increased impact toughness means
lower RC hardness as compared to the higher RC values of other
hand-held knife blades. As a result, the ability to maintain a
sharp edge (referred to hereinafter as edge retention) is
compromised. A technique has been developed to test several
different types of steel at different "Rockwell" or RC hardness
measurements until a happy medium is found between "good" edge
retention, where there is no dulling of the blade, and the
prevention of edge chipping.
[0008] For example, a conventional D2 steel hand-held cleaver, such
as a Brown Bear.TM. Cleaver sold by Knives of Alaska, is designed
to consistently cut through bone without chipping. However, when a
rope is repeatedly cut with the hand-held cleaver, the edge
retention is typically not up to par with harder hand-held knife
blades, such as a Jaeger.TM. Boning knife also sold by Knives of
Alaska. Similarly, harder hand-held knife blades that offer
increased edge retention in low impact cutting applications
typically experience edge chipping when used to cut or chop through
harder material such as hard wood and bone due to the increased
brittleness of the hand-held blade.
[0009] Ideally, a hand-held blade would be able to withstand
abrasive cutting and retain a sharp edge, yet be able to withstand
the high impact necessary to chop through solid bone, hard dried
wood, etc., without the edge chipping or fracturing.
[0010] Accordingly, what is desired is a hand-held knife blade or
cutting edge for a hand-held hatchet or other hand cutting
instrument that can withstand the high impact of chopping or
cutting through hard materials, and still provide superior edge
retention.
BRIEF SUMMARY OF THE INVENTION
[0011] In one aspect, the present invention provides a method for
enhancing the mechanical properties of a hand-held cutting
edge.
[0012] In another aspect the present invention provides a hand-held
cutting edge having superior edge retention and a method for
forming the same.
[0013] In another aspect, the invention provides a method for
forming a cutting edge on a hand-held knife that will result in
superior resistance to chipping of the hand-held cutting edge.
[0014] In one embodiment, the present invention provides a system
and method for friction stir processing of a hand-held cutting
edge, wherein friction stir processing techniques are used to
modify the properties of the hand-held cutting edge to thereby
obtain superior edge retention and superior resistance to chipping
of the hand-held cutting edge.
[0015] These and other objects, features, advantages and
alternative aspects of the present invention will become apparent
to those skilled in the art from a consideration of the following
detailed description taken in combination with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of one tool that can be used to
perform the friction stir processing of the present invention.
[0017] FIG. 2 is a cross-sectional view of another tool that can be
used to perform the friction stir processing of the present
invention.
[0018] FIG. 3 is a cross-sectional view of another tool that can be
used to perform the friction stir processing of the present
invention.
[0019] FIG. 4 is a cross-sectional view of a material that is
friction stir processed to modify the characteristics of the
material.
[0020] FIG. 5 is a cross-sectional view of a material that is
friction stir processed to modify the characteristics of the
material, and having an overlay identifying where a cutting edge
could be formed from the friction stir processed material.
[0021] FIG. 6 is a cross-sectional view of material that has been
friction stir mixed so as to include another material.
[0022] FIG. 7 is a cross-sectional view of the microstructure of
the steel of FIG. 6.
[0023] FIG. 8 is a cross-sectional view of one embodiment for
friction stir mixing an additive material 112 into another using a
mesh or screen 110 to hold the additive material 112 in place.
[0024] FIG. 9 is an image of a friction stir processed region of a
hand-held knife blade.
[0025] FIG. 10 is an image of the microstructure of the hand-held
knife blade of FIG. 9.
[0026] FIG. 11 is a view of a grinding machine with mist coolant,
getting ready to grind the first hand-held test blade.
[0027] FIG. 12 shows a Brown Bear Cleaver striking rope with
particles flying.
[0028] FIG. 13 shows hammer strike on blades.
[0029] FIG. 14 shows hammer strike on hand-held test blade
illustrating test area and where each of the 100 cuts occurred.
[0030] FIG. 15 shows 100 cuts by hand-held test blade and still
shaving sharp.
[0031] FIG. 16 shows fractured edge of Knives of Alaska knives
after cutting elk antler.
[0032] FIG. 15 shows anvil being chopped.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Reference will now be made to the diagrams of the present
invention in which the various elements of the present invention
will be given numerical designations and in which the invention
will be discussed so as to enable one skilled in the art to make
and use the invention. It is to be understood that the following
description is only exemplary of the principles of the present
invention, and should not be viewed as narrowing the claims which
follow.
[0034] In one aspect, the present invention provides a system and
method for performing friction stir processing on a hand-held
cutting edge, also referred to as a "blade." Three blades processed
using a friction stir processing system and method in accordance
with the present invention were prepared and tested against
conventional blades. The creation of the test blades was
accomplished by friction stir processing a workpiece that was then
finished to form a hand-held knife blade having a profile
substantially identical to a conventional knife blade used for a
comparison.
[0035] Another embodiment of the present invention is to use a tool
as shown in FIG. 2. FIG. 2 is a cross-sectional view of a
cylindrical friction stir processing tool 20. The friction stir
processing tool 20 has a shank 22 and a shoulder 24, but no pin.
Therefore, instead of plunging a pin into the material to be solid
state processed, the shoulder is pressed against the material.
Penetration by the shoulder is typically going to be restricted to
the surface of the material or just below it because of the larger
surface area of the shoulder as compared to the pin.
[0036] It should be noted that while the pin 16 of the tool 10 in
FIG. 1 does not have to be plunged into the material, the pin is
more likely to be designed for easy penetration. Thus, because the
pin 16 is more likely to have a very small surface area as compared
to the tool 20 of FIG. 2, the pin is more likely to plunge into the
material. However, it may be advantageous to use the smaller
surface area of the pin 16 for processing much smaller areas of a
material, even just on the surface thereof. Therefore, it is
another embodiment of the present invention that surface and
near-surface processing can also be accomplished using a tool that
is more typically used for penetration and joining of
materials.
[0037] FIG. 3 is provided as an alternative embodiment for a tool
having no pin. FIG. 3 shows a tool 30 having a shank 32 that is
smaller in diameter than the shoulder 34. This design can be more
economical because of less material used in its construction,
depending upon the diameter of the shoulder 34.
[0038] It is important to recognize that nothing should be inferred
from the shape of the shoulders 24 and 34 in FIGS. 2 and 3. The
shoulders 24 and 34 are shown for illustration purposes only, and
their exact cross-sectional shapes can be modified to achieve
specific results.
[0039] Experimental results have demonstrated that the material to
be used for the hand-held knife blade may undergo several important
changes during friction stir processing. These changes may include,
but should not be considered limited to, the following:
microstructure, macrostructure, toughness, hardness, grain
boundaries, grain size, the distribution of phases, ductility,
superplasticity, change in nucleation site densities,
compressibility, expandability, coefficient of friction, abrasion
resistance, corrosion resistance, fatigue resistance, magnetic
properties, strength, radiation absorption, and thermal
conductivity.
[0040] Regarding nucleation, observations indicate that there may
be more nucleation sites in the processed material due to the
energy induced into the material from friction stir processing.
Accordingly, more of the solute material may be able to come out of
solution or precipitate to form higher densities of precipitates or
second phases.
[0041] In FIG. 4, a section of ATS 34 steel was friction stir
processed by plunging a tool similar to the tool shown in FIG. 2
into the base material 70 and moving the tool transversely along a
middle length thereof. Transverse movement would be perpendicular
to the page, thus FIG. 5 is a cross-sectional view of the base
material 70.
[0042] FIG. 4 shows that the tool plunged into the base material 70
from the top 72. Several areas appearing as small circles are shown
as having been tested for hardness relative to the Rockwell scale
in the various zones of the base material. The stir zone 74 is
shown having a hardness of 60 RC. Close to the boundary of the
inner TMAZ (thermally mechanically affected zone) and the outer HAZ
(heat affected zone) the base material 70 is shown as having a
hardness value of 44 RC at a location 76. Finally, an unprocessed
or original base material zone is shown as having retained, in
other samples, its original hardness value of 12 RC at
approximately location 78.
[0043] FIG. 5 is an illustration of an overlay 90 of a cutting edge
on the ATS-34 steel base material 70. The overlay 90 indicates one
advantageous configuration of a cutting edge that could be machined
from the material 70, wherein the configuration takes the greatest
advantage of the improved toughness and hardness characteristics of
the friction stir processed material 70. Note that the cutting edge
overlay 90 is formed in the processed region 74 that will result in
a hard and yet tough cutting edge. Likewise, any object being
formed from a processed material can be arranged to provide the
most advantageous properties where it is most critical for the
object. In this example, a beneficial cutting edge will be achieved
from having an edge disposed well within the processed
material.
[0044] The hand-held test blades of the present invention were
created by machining the hand-held test blades in accordance with
the following instructions. FIG. 11 illustrates the grinding
machine that was used to grind the hand-held test blades to the
desired shape. The first attempt at grinding was to obtain a 22
degree angle with a 600 grit diamond belt. The result was a
polished edge. A 320 diamond grit was then used with good results
to further refine the hand-held blade. The desired angle was
established and after a few passes, the cutting edge was placed
against the 600 grit diamond belt to establish the desired wire
"burr". The wire burr was removed with an 8,000 grit diamond belt
and then polished with a 50,000 grit diamond belt. A razor
"shaving" edge was established on the test blades and the cutting
edge appeared to remain totally within the processed material.
[0045] It should be noted that the instructions provided above are
only to create test blades that are comparable in sharpness to the
blades that are being used for comparison purposes. A hand-held
blade that can be created using the friction stir processing of the
present invention should not be considered to be limited to the
parameters stated above.
[0046] An important element of the present invention is also the
concept of friction stir mixing. Whereas friction stir processing
will be regarding as the processing of a single material that is to
be fashioned into a hand-held blade, friction stir mixing provides
for additional additive materials to be included in the friction
stir mixing process. The additive materials become an integral part
of the resulting hand-held test blades.
[0047] FIG. 6 is a cross-sectional view of a base material that has
been friction stir mixed so as to include another additive
material. Specifically, a steel member 100 has been friction stir
mixed so as to work in diamond particles 102 into the steel
member.
[0048] FIG. 7 is a cross-sectional view of the microstructure of
the steel member 100. The figure shows that the diamond particles
102 are present throughout the mixed region of the steel member
100.
[0049] FIG. 8 is a cross-sectional view of one embodiment for
friction stir mixing an additive material 112 into another using a
mesh or screen 110 to hold the additive material 112 in place.
Specifically, a stainless steel mesh or screen 110 is being used to
hold carbide 112 in the form of a powder. The screen 110 and
carbide powder 112 are disposed on the surface of a base material
114. The surface of the base material 114 is then friction stir
processed, resulting in a mixing of the stainless steel 110, the
carbide 112, and the base material 114 at the surface of the base
material. Alternatively, the different materials could be mixed
further into the base material 114 using a tool having a pin, or by
using a tool having a shoulder that is pressed harder into the base
material.
[0050] FIG. 9 is a close-up view of a hand-held knife blade that
was created in accordance with the process described below.
[0051] FIG. 10 is a view of the microstructure of the hand-held
knife blade of FIG. 9.
[0052] An important concept of the present invention is that solid
state processing or friction stir processing that is performed is a
temporary transformation into a plasticized state. Thus, the
material that is used as the workpiece and formed into the
hand-held knife blade does not pass through a liquid state.
[0053] The balance of this document is devoted to test results for
comparisons that achieved unexpected results. For comparison
purposes, a Brown Bear.TM. hand-held Cleaver blade formed of D-2
steel was bolted to a test handle. A hand-held test blade having a
cutting edge formed of friction stir processed D-2 steel ground to
an identical profile was also prepared and bolted to a handle in a
similar manner. The resulting hand-held cleaver blade and hand-held
test blade were both 24 ounce blades that provided ample weight and
inertia for chopping.
[0054] A first chopping test was performed on a green red oak limb;
a second chopping test was performed on a dried Osage orange limb,
which is an extremely hard, dense wood; a third chopping test was
performed on an elk antler (bone); a fourth chopping test was
performed on a brick block, and a fifth chopping test was performed
on a steel anvil. Results for chopping with the test blade are as
follows in Table 1:
TABLE-US-00001 TABLE 1 Test Result Green red oak No edge chipping;
edge will still shave dry hair Dried Osage No edge chipping; edge
will still Orange shave dry hair Elk antler No edge chipping; minor
edge wear evident; would shave wet hair Brick Edge damage evident
with several small chips and dulled edge Steel anvil Small edge
separation at point of machining groove for friction stir
[0055] Both hand-held cleavers were able to consistently cut
through bone and hard wood without chipping. However, the hand-held
test blade was found to provide greater edge retention over the
conventional hand-held cleaver.
[0056] The above tests were also performed using a hand-held
Bush.TM. Camp Knife and a hand-held Jaeger.TM. Boning knife which
both have good edge retention when compared to other hand-held
knives. As shown in FIG. 16, both hand-held knives had catastrophic
cutting edge failures when tested on the elk antler and, thus, were
not tested on the harder materials.
[0057] A second hand-held test blade was sharpened to perform new
tests. The second test blade was used to cut rope for 30 minutes.
In that time, 607 cuts were made until the rope was gone. The
second hand-held test blade still shaved dry hair afterwards.
[0058] Further tests were performed on hand-held test blades, such
as the sharpness test of the friction stir processed edge. For this
test, five different Knives of Alaska.TM., Inc. hand-held knife
models were first tested. These hand-held knives include the
Alaskan Brown Bear Skinner/Cleaver (D2 steel; RC 55-57), the Jaeger
Boning Knife (ATS-34 steel; RC 59-61), the Bush Camp Knife (AUS8
steel; RC 57-59), the Coho fisherman's knife (hollow ground AUS8
steel; RC 57-59), and the Magnum Ulu (D2 steel; RC 59-61). The
final test was on a hand-held test blade with the friction stir
processed edge.
[0059] The test for sharpness involved placing a 3/4 inch thick
hemp rope on a 2.times.6 board. A section on each knife was
selected and the rope was cut completely through by striking the
back of the blade with a soft mallet. FIG. 12 shows a Brown Bear
cleaver striking the rope. FIG. 13 shows a mallet or hammer that
was used to strike the hand-held blades to cause them to cut
through the rope. FIG. 14 shows the area on the hand-held test
blade where the rope was repeatedly.
[0060] The rope was repeatedly cut, at the same point on the
hand-held knife blade. The number of cuts was recorded for each
hand-held blade. When the hand-held knife's tested section would no
longer shave dry hair on the tester's arm--this was recorded as one
past the maximum number of cuts that that hand-held blade steel
would retain a shaving edge. The test results are as follows as
shown in Table 2:
TABLE-US-00002 TABLE 2 Number of Cuts Where hand-held Hand-held
Knife Knife No Longer Shaves Alaskan Brown Bear 17 Jaeger Boning
Knife 67 Bush Camp Knife 41 Coho Fisherman's Knife 14 Magnum Ulu 52
Test Blade 100+
[0061] It is observed that the testing of the hand-held test blade
was stopped at 100 cuts as the hand-held test blade was already
exceeding all other test samples. The hand-held test blade is shown
in FIG. 15. Furthermore, the hand-held blade would still shave and
there was no appreciable difference between the edge when the
testing began and after 100 cuts.
[0062] The test blades formed in accordance with the present
invention held up to and exceeded expectations in the sharpness
category and in the impact test results. Conventionally, it is
unexpected to be able to take a two pound hand-held test blade and
swing it smartly to cut through a hard material such as elk antler,
repeatedly, and still retain a shaving edge with no edge
fracturing. Such performance is unheard of in the hand-held knife
industry.
[0063] Friction stir processing may be applied to any hand-held
knife blade to enhance performance characteristics of the blades.
Such hand-held knife blades may be formed of any material known in
the art, including D2 steel, ATS-34 steel, AUS8 steel, S-30V steel,
or other materials.
[0064] It is to be understood that the above-described arrangements
are only illustrative of the application of the principles of the
present invention. Numerous modifications and alternative
arrangements may be devised by those skilled in the art without
departing from the spirit and scope of the present invention. The
appended claims are intended to cover such modifications and
arrangements.
* * * * *