Note: Descriptions are shown in the official language in which they were submitted.
106;~
The present invention relates generally to various
cutting tools such as die rule blades, slitter blades, hollow
punches, and the like and more p~rticular~y to a novel cutting
edge configuration.
Several unsolved problems have existed in the art of
cutting devices prior to the present invention. For example,
many cutting devices have somewhat elaborate cutting configur-
ations which are costly to form on the cutting blade. Many
other cutting blade arrangements simply do not qive a clean cut
on the stock material as desired.
Still other problems arise in connection with a
cutting die press. For example, many of the prior art cutting
blades require a relatively high tonnage or force to press the
cutting blade entirely through the stock material. In die
presses where a resilient die pad is used, inordinate wear of
the die pad has been experienced with various types of notched
blades because of the cutting blade cutting away the die pad
after it has sliced through the stock material. If a hard
metallic back up die pad is used, the cutting blade is dulled
; 20 by metal-to-metal contact a~ter the cutting operation.
Specific,examples of prior art cutting blade configur-
ations are disclosed in United States Patents Nos. 3,277,764 to
Henc, 3,422,712 to Lovas, and 201,104 to Frary. Each of these
prior art devices likewise include inherent disadvantages not
experienced by the present invention.
In short, the prior art does not provide the overall
range of advantages or the structural arrangement or method of
cutting edge disclosed herein.
; The present invention relates to an improved compound
cutting edge configuration for die rule blades, slitter blades,
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1062604
hollow punches, shearing blades or similar cutting tools. This
specific compound cutting edge configuration enables an improved
method of cutting stock material.
Accordlng to the present invention there is provided a
cutting tool having a cutting portion comprising two converging
surfaces having a plurality of teeth formed therein, the teeth
terminating in points spaced along the line of intersection
; between the two surfaces and defining a plurality of primary
cutting edges each of which extends from a respective tooth point
along one of the converging surfaces generally towards an adja-
cent tooth point through at least 75 percent of the distance -
between the tooth points, at an angle in side elevation of the
cutting tool of from about one to about fifteen degrees to the
line of intersection between the tooth points.
,'f According to one particular aspect of the invention there
is provided a cutting tool having a shank terminating in a cutting
.. .
;^ portion which includes two converging surfaces forming a conver-
gent angle of between one and thirty degrees, wherein the improve-
ment comprises a plurality of side-by-side notches formed in one
of the converging surfaces of the cutting portion, the notches
defining (a) a series of generally equally spaced sharp piercing
points and (b) a primary cutting edge extending away from each
piercing point toward the next adjacent piercing point, each
primary cutting edge extending substantially the entire distance
between two adjacent piercing points and defining an angle in
side elevation of the cutting tool with a line through the
' piercing points of between one and fifteen degrees, and each
primary cutting edge defining an angle in plan view of the
cutting tool with a line through two adjacent piercing points of
between about zero and 15.
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According to another particular aspect of the invention
there is provided a die rule having two converging surfaces
forming a cutting portion, wherein the improvement comprises a
plurality of side-by-side generally boomerang-shaped indentations
formed in one of the converging surfaces defining (a) a plurality
. of generally equally shaped piercing points, and (b) a substan-
tially linear cutting edge extending from each piercing point
toward a next adjacent piercing point, each of the cutting ed~es
extending substantially the entire distance between the two
10 piercing points, and in side elevation of the die rule the cut-
ting edge forming an angle with a line through two piercing
points of between about one and five degrees, the cutting edges -
thereby forming a generally check-shaped valley between each of
the piercing points, the maximum depth of the valleys being about
three-sixteenths of an inch.
According to a further particular aspect of the invention
there is provided a cutting press including a resilient die pad
~ aligned with an axially reciprocal die rule, the improvement of
: the die rule having a cutting surface defined by (a) a plurality
; 20 of generally equally spaced piercing points and (b) a plurality
of cutting edges between the piercing points, each of the cutting .
edges extending from a piercing point toward a next adjacent
piercing point for substantially the entire distance between the
two piercing points, the cutting edges extending in a direction
away from the die pad at an angle in side elevation of the die
rule with a line through the tips of the piercing points of be-
tween about one and fifteen degrees, thereby forming a generally
check-marked shaped cutting surface valley between adjacent -
: piercing points, the valley having a depth of not more than three
30 sixteenths of an inch, and the die rule piercing points thereby
having to penetrate into the resilient die pad for a distance
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1062604
equal only to the depth of the cutting surface valley for the
die rule to completely cut through the thickness of the material
being cut.
According to yet another particular a~pect of the invention
: there is provided an improved die rule having a plurality of gen-
erally equally spaced piercing points and primary cutting edges on :;:
a chamfered cutting portion of the cutting edges being substan-
; tially linear and extending from one piercing point substantially
the entire distance to a next adjacent piercing point, each cut-
ting edge and a line through the tips of the piercing points def- : :
ining an acute angle between about one and five degrees in side
elevation of the die rule, the piercing points and cutting edges
being defined by notches formed in the die rule chamfer, the
notches being defined by major and minor triangular-shaped notch
faces between adjacent piercing points, the major triangular face
; being bounded on one edge by a primary cutting edge, the notch
. faces having a common side, and the minor triangular face defining
a secondary edge interconnecting the primary cutting edge with a
next adjacent piercin~ point, the primary cutting edge and secon- .
dary edge defining a generally check-marked shaped edge configura- -
~ tion between each pair of adjacent piercing points. - :;
.~ The invention also provides a method of cutting material
with a cutting tool as recited above, the method comprising the
~ steps of relatively moving the cutting tool and the material to-
.~ ward one another, initially contacting the material by the tooth
points of the cutting tool thereby to pierce the material at a ~.
plurality of positions, and continuing to relatively move the
. cutting tool and the material to cut the material between the
plurality of pierced positions with the primary cutting edges of
the cutting tool, the primary cutting edges progressively cutting
the materially substantially unidirectionally from each pierced
position toward a next adjacent pierced position.
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One particular aspect of the method of the invention pro-
vides the steps of positioning the stock material in alignment
with a die rule, relatively moving the die rule and stock mater-
ial toward one another, initially contacting the stock material
by a plurality of generally equally spaced peaks on a cutting
portion of the die rule, thereby piercing the stock ma~erial at
a plurality of generally equally spaced positions, continuing to
relatively move the material and the die rule and cutting the
stock material between the plurality of pierced positions with
a plurality of primary cutting edges, each of the primary cutting
edges (a) extending from one piercing peak substantially the
entire distance to the next piercing peak and (b~ extending away
from the stock material by an angle of from about one to fifteen
degrees with a line connecting the piercing peaks, the cutting
edges thereby progressively cutting the stock material substan-
tially unidirectionally from one pierced position progressively
toward a next adjacent pierced position at a rate in comparison
with the rate of relative movement between the cutting tool and
: stock material within the ratios of between about 57.29:1 and
,,: . .
3.73:1. - .
Another particular aspect of the method of the invention
: provides in a method of cutting stock material the steps of:
positioning the stock material on a resilient die pad in alignment
with a cutting die rule, the die rule having a chamfered portion
defined by two converging surfaces which intersect to form a
cutting portion, the cutting portion having formed thereon a
, plurality of notches which define a plurality of generally equally
spaced piercing points and a plurality of substantially linear
.-: .,
primary cutting edges extending from each piercing point substan- ~
tially the entire distance to an adjacent piercing point, the : -
primary cutting edges extending away from the piercing points by
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an angle of no more than fifteen degrees, thereby forming a
valley on the cutting portion between each piercing point, the
valley having a depth of no more than three sixteenths of an
inch; relatively moving the stock material and the die rule to-
ward one another, and in a substantially simultaneous, sequential
operation (a) initially penetrating the stock material at a
plurality of positions with the die rule piercing points, (b)
cutting the stock material with the primary cutting edges in a -
direction away from each initially penetrated position toward a
n~xt adjacent penetrated position, whereby the stock material
from each penetrated position is cut substantially the entire dis-
tance therebetween in a progresslve cutting action in substanti-
ally only one direction at a rate of greater than 3.73 times the
rate of relative movement between the stock material and the die
rule, due to the angle of the primary cutting edges, and (c)
pressing the piercing points through the stock materlal and into
the resilient die pad by a distance of not more than about three
sixteenths of an inch due to the shallow valley depth on the cut-
~ ting portion, at which depth the stock material will be cut
- 20 through its entire depth by the cutting edges; and retracting the
stock material from the die rule and die pad. .
A further particular aspect of the method of the invention
provides in a method of cutting blanks from stock material, the
.~ steps of: positioning the stock material in alignment with a cut-
ting tool having a pair of converging faces, and relatively moving
the cutting tool and stock material toward one another ta) to ini-
: tially pierce the stock material in a plurality of generally eq~ly
spaced positions by a plurality of generally equally spaced peaks
. on a cutting portion of the cutting tool, and thereafter (b) to
3t) progressively cut the stock material substantially unidirectionally
from each of the pierced positions toward a next adjacent pierced
,
.
10626~14
position with a plurality of primary cutting edges on the cutting
tool, each of the primary cutting edges extending from one pierc- -
ing peak substantially the entire distance to the next piercing
peak and extending away from the stock material by an angle of
from about 1 to 5 with a line connecting the piercing peaks
and (c) to cut the stock material between the pierced positions
at rate of between about 11.43 and 57.29 times the rate of
relative movement between the cutting tool and stock material.
In an embodiment of the invention the cutting edge config-
uration includes a plurality of side-by-side notches formed on a
chamfered cutting edge portion, thereby forming a plurality of
generally equally spaced piercing points or peaks, A primary cut- -
ing edge is defined which extends into the notch away from each
peak and toward a next adjacent peak. This primary cutting edge
extends substantially the entire distance between the two adjacent
peaks, providing for a substantially unidirectional compound slic-
ing or cutting action between the peaks. The cutting edge forms
an angle with a line connecting the peaks of between about one and
fifteen degrees. In the most preferred embodiment, this angle is
between about one and five degrees. This relatively small angle
forms a shallow notch valley between adjacent peaks, which sub-
stantially reduces the wear on a resilient backup die pad that may
be used in combination with the present cutting bla~e configuration.
It has been found that this novel compound cutting blade
configuration reduces the pressure required for cutting stock
material. This is somewhat surprising since it would be expected
that larger angles would reduce the rate of cutting and therefore
result in less resistance of the stock material to cutting.
n a preferred embodiment of the invention, each notch is
formed individually by placing the cutting tool against a grinding
edge. This forms major and minor compound angle pyramidal-shaped
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10~ ;04
notch faces. The major notch face includes the primary cutting
edge and the minor notch face forms a secondary cutting edge
which interconnects the primary edge with the next adjacent
piercing point.
A preferred method of using the novel compound cutting
edge includes first placing stock material in alignment with the
cutting tool, which is then moved under pre~sure toward the stock
material. First contact between the cutting tool and the stock
material is by the cutting edge piercing points which penetrate
the material and initiate the cutting action. This initial pene-
tration or piercing contributeg to the overall reduction in pres-
sure required for cutting by the present invention, as will be
appreciated by those skilled in the art. The continued movement
of the compound cutting tool through the stock material results
in the primary cutting edges slicing the stock material substan-
tially unidirectionally from one piercing point to the next
adjacent piercing point. A minimal amount of cutting is accom-
plished by the secondary cutting edge which interconnects the
primary cutting edge with the next adjacent piercing point. Axial
movement of the cutting tool is continued until the stock material
is completely cut into the desired cvnfiguration.
One preferred application of the present cutting edge con-
figuration is on a cutting die rule that is used in combination
with a resilient back up die pad underneath the stock material.
In this arrangement, the piercing points and cutting edges must
extend completely through the stock material and into the die
pad for a depth which is at least equal to the depth of the
notch valley between the piercing points. Since the present
invention enables a relatively shallow notch valley depth, the
penetration into the die pad is reduced, resulting
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106Z604
in increased die pad life.
This novel cutting configuration can be used in a wide
variety of applications including die rule blades, shearing
blades, slitter blades, hollow punches, rotary hole saws, and
the like. Additionally, the present invention may be used quite
satisfactorily to cut a wide range of materials, including for
example, fiberglass, fabrics, foam rubber, paper, surgical pads,
sheet material including vinyl fibers, aluminum, plastics, and
various and numerous types of textile goods. This extreme wide-
range utility o~ the present invention can therefore be appre-
ciated.
Many advantages have also been found to follow from
the present invention. First, less tonnage or pressure is
required to press the cutting tool through the stock material.
This enables smaller power means with an associated reduction
in cost. Additionally, the lower tonnage requirement results
in longer life of the cuttinq tool, increased production, less
maintenance and machine down time is obtained, since reduced
pressure is developed at the cutting edge.
Another advantage is the cleaner, straighter cuts
that are accomplished by the present invention. Additionally,
the notched compound cutting edge configuration is relatively
simple to form and can be done, for example, by grinding. As
previously discussed, another advantage afforded by the present
invention is longevity of the back up cutting die pad.
Other advantages are particular to the individual
stock material being cut. For example, in cutting fiber glass
it has been found that approximately eighty percent less dust
is generated during cutting. Fibers in vinyl and other fiber
materials are not fused together, because of less heat gener-
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106Z604
ated during the cutting action, resulting from cleaner cutting
while the reduced pressure is exerted on the cutting tool.
Cutting cylindrical holes in foam with prior art
cutting instruments generally results in a concave-shaped cut
along the thickness of the stock material. This i5 due to
the cutting instrument compressing the foam material before the
cutting action actually begins. The present invention elimin-
ates the concave or convex holes or end cuts and proves a
straighter cut for foam materials because the piercing points
initiate the cutting action and reduces the foam compression.
Other advantages and meritorious features of this
invention will more fully appear from the following specifica-
tions, claims and accompanying drawings.
The invention will now be described with reference to
the accompanying drawings in which:
Figure 1 is a schematic, cross-sectional view of a
die press which includes a~cutting tool having the cutting edge
configuration of the present invention;
Figure 2 is a perspective view of the cutting tool s
., .
o Figure l;
Figure 3 is a schematic, partially cross-sectional
view of another die press and cutting tool in combination with
~'!, a punch tool;
Figure 4 is a perspective view of the cutting tool
of Figure 3;
Figures 5-10 are perspective views of various cutting
tools which may include the cutting configuration of the present `
invention;
- Figure 11 is an enlarged, fragmented plan view of one -~
embodiment of the cutting edge configuration;
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1~6260~
Figure 12 is an enlarged, fragmented side elevational
view of the cutting edge configuration of Figure 11;
Figure 13 is a cross-sectional view taken along plane
13-13 of Figure 12.
Referring to the drawings, Figure 1 illustrates a cutting
press 10 which is primarily suited for use in cutting thick or
tough materials, such as soft metallic materials. The die press
10 includes a fixed die base 12 surmounted by and connected to
mounting plate 14 in a conventional manner. A male punch 16 and
a resilient stripper pad 18 are suitably mounted on top of
mounting plate 14 for receiving stock material 20. The stock
material is cut with a flat die rule 22 which is shown in per-
spective in Figure 2. The cutting edge of die rule 22 includes ~ ~-
a plurality of side-by-side notched configurations 23 which form
a novel cutting edge that will be more fully explained below.
Die rule 22 is mounted in a die rule mounting block 24,
which is illustrated as being a wood block. Mounting block 24 $
is suitably mounted to a back up plate 26 which is connected
to a punch holder 28. A compressible stripper pad 30 is also
attached to mounting block 24 in conventional manner and com-
prises, for example, hard rubber as is somewhat conventional ;
in the art. The die rule 22, stripper pad 30, mounting block
. .
~- 24, back up plate 26, and punch holder 28 comprise a vertically
reciprocal cutting die.
Operation of the embodiment of Figure 1 includes
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~06Z604
- raising the cutting die so that a piece of stock material 20
may be properly positioned on male punch 16 and stripper pad 18.
The cutter die is then driven under pressure downwardly so that
the die blade 22 sevsrs the stock material to form a blank of
predesired configuration, thereby leaving scrap material 33.
As illustrated, die rule blade 22 cuts through the stock
material and barely extends into a slot 32 defined between punch
16 and stripper pad 18. Downward movement of the die press is
limited substantially to the po~ition shown in Figure 1, so
that the cutting edge on rule 23 does not strike mounting plate
14. As the die rule blade 22 projects into slot 32, the
stripper pad 30 is compressed. Then as the die press is raised,
stripper pad 30 expands and leaves the cut stock material on
punch 16.
Figure 3 illustrates a die press primarily suited for
cutting soft stock material. This embodiment includes a fixed
base 42 and a vertically reciprocable punch holder 44 to which
back up plate 46, mounting block 48, and die rule blade 50 are
mounted. In this particular embodiment, the die rule blade is ` `
cylindrical as shown in Figure 4 and includes a plurality of
side-by-side notches 52 in accordance with the present inven-
tion. Also in this embodiment, a punch 54 is suitably mounted
; in mounting block 48, and may include the cutting edge config-
uration of this invention.
.! In operation of the embodiment in Figure 3, the punch
holder 44 is raised from the position illustrated and a piece
of stock material 56 is properly positioned on a resilient die
- pad 58. Die pad 58 is suitably mounted on the fixed base 42 and
is comprised of a rubber or polyurethane material. Scrap
material is formed during the cutting operation by punch 54,
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la62604
the scrap being removed through a knock-out hole 60 in punch
54, as is conventional.
After the stock material is properly positioned on the
die pad, punch 54 is moved under pressure by suitable power
means, such as a hydraulic cylinder and piston, to drive the
die rule cutting blade through the stock material 56. At about
the same time, punch 54 forms a scrap slug.
As shown in Figure 3, tbe die rule cutting edge barely -
cuts into the die pad. This is necessary so that the notched
configuration of the cutting edge in the present invention will
completely cut through the stock material. However, in later
portions of this disclosure, it will be explained that the
present invention limits the extent to which the die rule cuts
into the die pad, thereby yielding one of the advantages of the
present invention; i.e., greater die pad longevity, with very
little resurfacing required.
From the embodiments shown in Figures 1 and 3, it
can be readily seen that the cutting edge configuration of this
invention can be used in a variety of ways. Figures 5-10
further illustrate that the cutting edge configuration is not
limited to a die rule, per se, but is virtually unlimited in
its application. For e~ample, Figure 5 illustrates a circular
hole saw 70 having a shaft 71 and being conventional in every
aspect except the novel cutting edge configuration 72 of the
present invention.
Figure 6 illustrates a flat die rule blade similar
to that of Figure 2 and including a shank 74. A chamfer 75
'
- at the cutting edge of the die rule is formed by two conver-
ging, generally V-shaped surfaces. The novel cutting edge con-
figuration of this invention is formed on the chamfer 75 and
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1062604
includes the plurality of notches and side-by-side peaks 76.
Figures 7 and 8 illustrate cylindrical die rules, or
punches, 78 and 82 having respective chamfer regions 79 and 83.
In these embodiments, the internal bore of the die rule is
generally cylindrical, but there still exists two converging
; surfaces to define the cutting edge. Notches 80 and 84 are
formed on the terminus of the cylindrical die rules to define -
the cutting edge configuration of this invention. Each punch
includes a knockout hole 77 and 85, respectively, for scrap
material ejection.
Figure 9 illustrates a slitter wheel 86 including a
circular hole 87 and being conventional in every respect except
for the cutting edge configuration 88 of the present invention.
As is known to those who are skilled in the cutting art, a
slitter wheel traverses stock material under pressure to effect
the cutting operation.
; Figure 10 illustrates another version of a cylindrical
die rule 90 which is substantially similar to die rule 50 illus-
trated in Figure 4. Of course, the cutting edge configuration
92 is that of the present invention.
Figures 11-13 show in enlarged fashion a cutting
edge configuration according to a preferred embodiment of the
the present invention. From Figure 11, it
can be seen that the illustrated tool is a cylindrical die rule
100, similar to that in Figure 10. The die rule 100 includes
a shank 102 and a chamfer formed by converging surfaces 104 and
106. Figure 13 shows the converging sides forming an angle C,
-- which in preferred embodiment, should be chosen to fall in the
- range of between one and thirty degrees. As discussed pre- ;
30 viously in regard to Figures7 and 8, surface 104 could be cylin-
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~06Z~04
drical, but there would still exist two converging surfaces to
define the die rule cutting region.
The cutting edge configuration includes side-by-side
notches or indentations which are formed on only one of the
chamfer converging surfaces, for example, by grinding.
These notches define a plurality of teeth having
generally equally spaced peaks 108 which serve to pierce the
stock material to initiate the cutting action. The notches are r
also configured to form a plurality of primary cutting or
10 slicing edges 110, each extending away from one peak into an
associated notch and toward a next adjacent peak. It can be
; seen from Figure 12, that cutting blade edge 110 extends approx-
imately 75 to 80 percent or more of the distance between two
ad~acent peaks. For purposes of defining the present invention,
it is considered that this constitutes the primary cutting edge
extending substantially acroas the entire distance between two
adjacent peaks.
Further, it can be -~een from Figure 12 that the
primary cutting edge 110 forms an angle "b" with a line through
20 piercing points 108. According to the invention, this angle
should be no more than about fifteen degrees. More preferably,
the angle should be within the range of between about one and
five degrees.
Figure 11 also shows that cutting edge 110 forms an
angle "a" in plan view with a line through peaks 108. This
angle is directly related, in general, to the slope angle of
surface 104 relative to the vertical. This relationship can
be seen in Figure 13, wherein the notch is illustrated in
phantom. In most instances, this angle "a" will be between
30 about one and fifteen degrees, but this is not critical. In
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die rule embodiments having a cylindrical inner bore, such as
in Figures 7 and 8, angle "a" would appear to approach zero for
strict geometrical reasons.
The notched configuration of the present invention
also defines a pair of pyramidal notch surfaces 112 and 114
and an incidentally-occurring secondary cutting edge 116. The
secondary cutting edge, of course, cuts only small portions of
the stock material so that the cutting action i~ substantially
~ unidirectionally along primary cutting edge 110 from one
10 piercing point to the next. In some embodiments, edge 116 may
even become purely vertical so that the entire cutting action
is along a primary cutting edge 110. For definitional purposes,
surfaces 110 and 116 are considered to constitute a check-marked
shaped edge interconnecting adjacent piercing points.
Pyramidal-shaped surface 112, the major pyramidal
surface, is bounded on one side by primary cutting edge 110 and
has a common side with secondary pyramidal surface 114. For
definitional purposes, these surfaces are considered to define
a generally boomerang-shaped notch configuration. However, it
is not necessary that the notches be defined by these pyramidal
surfaces. The important consideration would appear to be the
combination of the piercing points, the major cutting edges
:
establishing progressive angular cutting from one piercing point
; to the next, and the notches being formed on only one side of
the chamfer.
Figure 12 also illustrates that the small angle "b"
defines a relatively shallow valley depth "d". This depth will,
of course, be a direct result of the angle "b" and the distance
between adjacent piercing points. For most applications of the
' 30 present invention, this depth will not be more than about three
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~062604
sixteenths (3/1&3 of an inch. In the more preferred embodiments,
the depth of the valley will be no more than about 3/32, and
may even be as shallow as 1/32 and 1/64 of an inch, depending e~
upon the material to be cut. In the most preferred embodiment,
the valley depth will result from angle "b" being from about 1 to
5. It will be recalled from the discussion relating to the
embodiment of Figure 3 that this shallow valley depth has great
significance when a resilient back up die pad supports the stock
material. Specifically, for a notched die rule blade to com-
pletely cut thxough stock material the cutting edye portion must
project completely through the stock material and therefore into
the resilient die pad material. This penetration depth is mini-
mized in the present invention because of the shallow notch
valley depth. Accordingly, the resilient die pad does not ex-
perience the wear associated with prior art notched cutting
edges.
The manner of using a cutting tool having the present
cutting edge configuration is substantially identical to that
of prior cutting t~ools. However, the cutting action created by
the present invention is not the same as in the prior art.
Specifically, when the cutting tool is pressed into the stock
material peaks 108 pierce the material to initiate the cutting
' action. Continued movement of the cutting tool through the
st~ck material results in a progressive cutting or slicing by
the primary cutting edge substantially unidirectionally from
one piercing point to the next. Further, the piercing points
and primary cutting edges are formed by a notch which is only
on one side of the cutting tool so that stock material exerts a
resistive pressure substantially on only one side of the cutting
tool which creates a unidirectional cutting pressure on the
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material being cut. These overall ~tructural limitations and
cutting method steps result in the reduced tonnage requirements
previously explained.
It will be understood from the foregoing description
that the rate of cutting action in the dir~ction between the
pierced points on the stock material will be dependent upon the
angle of the cutting edges. Specifically, the cotangent for a
one degree cutting edge is 57.29, the cotangent for a five degree
cutting edge is 11.43 and the cotangent for a fifteen degree
cutting edge is 3.73. Therefore, with a one degree cutting edge,
; the stock material will be cut at a rate of about 57.29 times
the rate of relative movement between the cutting tool and stock
material; with a five degree cutting edge, the stock material
between the pierced positions will be cut at a rate of about
11.43 times the rate of relative movement between the cutting
tool and stock material; and with a fifteen degree cutting edge,
the stock material between the pierced positions will be cut by a
,~ rate in comparison with the rate of relative movement between the
cutting tool and stock material of about 3.73:1.
It is to be understood that the description and explana-
tion herein is merely exemplary of the overall invention and is
not intended to be limiting in any respec~. For example, the
cutting edge configuration may be formed by other methods than
, grinding and may be used in all equivalent cutting tools.
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