Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STEEL RULE DiE WITH CLOSELY NESTED CAVITIES
FIELD OF THE INVENTION
This invention relates to steel rule cutting dies, and more particularly to
improved method steel rule cutting dies with a reduced gap between adjacent
cavities of multi-cavity dies so as to reduce the amount of material scrap.
BACKGROUND OF THE INVENTION
~o Steel rule cutting dies are commonly used for cutting cloth, cloth like
materials such as natural textiles and synthetic materials such as vinyl, and
other
materials. Steel rule dies are particularly advantageous in the repetitive
cutting of
specific shapes for use in clothing, furniture, and automotive interior
panels. In
brief, a steel rule cutting die typically comprises a base substrate or
backing
~s board in which a groove matching the desired pattern to be cut is formed or
otherwise provided. A length of sharpened blade, known as a steel rule, is
formed
to the shape of the desired pattern to be cut and is embedded in the
corresponding groove in the board. The steel rule has a sharpened cutting edge
extending away from the board. The die is used in conjunction with a cutting
table
2o and a press which may be either single cut or progressive feed. A single
steel
rule cutting die is often constructed with multiple blades or cavities as to
enable
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cutting of multiple patterns with a single pass through the press. Multiple
cavities
or patterns can be nested together on the substrate in an efficient
configuration to
minimize scrap. Adjacent cavities of the die must be separated from one
another
by a gap sufficiently large to allow for scrap material to be removed from the
gap
s after the cutting operation is complete. It is general practice in the die
cutting
industry to use a gap of'/ inch or more. However, using a gap of'/4 inch or
more
causes significant scrap of wasted unused material. Accordingly, a reduction
in
scrap, and thus cost, could be attained by either reducing or completely
eliminating this gap between cavities.
~o In existing multi-cavity dies, a certain amount of waste is produced due to
the gap between adjacent cavities. The gap between cavities is used because of
the bevel on the sharpened portion of the rule. As the rule cuts through
several
layers of material, the material is compressed laterally by the thickness of
the
rule. If two cavities are placed next to each other with too small of a gap,
the
~s scrap material between the cavities will be compressed into the gap and
become
stuck. Thus, existing multi-cavity dies have not been able to successfully
reduce
the gap between cavities to less than '/ inch in conventional dies.
Steel rule dies are used in applications where a large number of pieces
are required so that repetitive cuts can be automated. Because of the large
2o number of pieces, even a small amount of scrap material per piece can add
up to
a large waste for the manufacturer. For instance, a typical manufacturer of
automotive interior panels may produce interior trim panels for 1,000,000 cars
per
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year. This amounts to approximately 6,000,000 yards of material per year. The
average material cost may be $8.50 per yard yielding an annual cost of
$51,000,000 for material alone. If the gap between adjacent cavities could
successfully 1 a reduced from 114 inch to 1/8 inch, typical savings in the
range of
s 2 - 5% can be achieved. In the above example, this would equate to an annual
savings of $1,020,000 to $2,550,000 for the typical automotive interior panel
manufacturer. It can therefore be seen that it would be desirable to reduce or
eliminate the gap between adjacent cavities.
Prior attempts to reduce or eliminate the gap between cavities have not
~o proven successful and the general practice in the industry continues to be
a'/
inch gap. Prior attempts at reducing or eliminating the gap have been complex
and cumbersome, difficult to clean, have resulted in weakened rule in the area
of
the gaps or have not been suitable for large or complex patterns. One method
that has been used to eliminate the gap is to use a single piece of cutting
knife on
~s straight sections of adjoining cavities. Use of a single common knife
section,
however, is not possible on irregular shapes.
One approach to eliminating the gap between adjacent cavities of a
cutting device is disclosed in U.S. Pat. No. 1,321,896. This patent describes
the
manufacture of a cutting die in one continuous piece with irregular shaped
2o cavities sharing common sections of cutting blade. This concept suffers
from the
fact that all cavities must be formed from a solid piece at the joining
locations,
and are inseparably connected making it impractical for larger dies such as
those
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used in cutting parts for automobile interiors and furniture, as well as
making
repair difficult or impossible.
Another approach to eliminating the gap between adjacent cavities of a
cutting device is disclosed in U.S. Pat. No. 1,177,005. This patent describes
the
s use of a grouping frame to position adjacent cavities of a cutting die so as
to
contact one another. The concept suffers from the fact that the grouping frame
adds complexity and thus cost to the apparatus. Further, the apparatus may
need
to be disassembled between consecutive cutting operations to clean scrap or
waste material from the apparatus, thus decreasing the productivity and
raising
~o the cost of using such an apparatus.
In neither of the above mentioned patents is there mention of device for
accommodating evacuation of scrap from the substrate of a steel rule die or
cutting marker notches on the common sections of the die. Nor is a device for
reducing without eliminating the gap between cavities discussed. Nor do they
~s encompass steel rule cutting dies or dies fabricated with pre-sharpened
blade.
SUMMARY OF THE INVENTION
According to the present invention, the gap of'/ inch between adjacent
cavities, which is general practice in the industry, is reduced or completely
Zo eliminated by using rule with the cutting edge offset toward the outer edge
of the
cavity. it has been found that the ability to remove scrap material from
between
adjacent cavities is dependent on the percentage of crass sectional reduction
that
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the material undergoes during the cutting operation. Through the offset of the
cutting edge, the amount of material wedged between cavities is reduced, and
thus the distance between cavities can be reduced to less than'/ inch. In
order
to accommodate the tact that the cutting edge has been shifted from the center
of
the rule, the groove in the board is also offset by the same amount so that
the cut
piece is the correct size.
If the cutting edge of the rule is offset all the way to the outside of the
rule,
then two sections of rule can directly contact each other with their cutting
edges
back to back. In this way, no material will be wedged between the cavities and
~o the gap between cavities can be completely eliminated. In the common areas
of
contact between two cavities with side bevel rule, the two sections of rule
can be
joined using a variety of techniques including welding, silver soldering,
brazing,
riveting, or a combination of these techniques.
Using two pieces of side bevel rule to eliminate the gap between cavities
has several advantages over using a single piece of Gammon rule between
cavities. Complex shapes can be accommodated wherein the adjacent cavities
touch each other only at one point. It is also possible to have two adjacent
cavities touch each other at several points with the patterns diverging from
each
other in between contact points. Use of individual side bevel rule cavities
also
2o allows for easier cleaning and maintenance than does a common piece of rule
attached to two adjacent cavities.
The amount of gap to be left between adjacent cavities, if any, is
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dependent on the specific application and on the type and cost of material
being
cut. A die is in no way limited to having all cavities using either the
reduced gap
technique or the butted cavity technique. Rather, it has been found that using
a
combination of the two types of gap may be the best approach in some
s circumstances.
Another aspect of the present invention is the provision for evacuation of
scrap materials in areas where small angles are formed between two adjacent
sections of rule. When adjacent cavities are butted and small angles are
formed
as the knives diverge, some frayed material can build up in the small crevice
~o formed by the diverging knives. In order to allow evacuation of this scrap
material, a small portion of the base or substrate material can be removed to
allow an exit path for the material. In addition, the base of the cutting
knife, inside
the substrate, can be cut away or relieved, further aiding in the evacuation
of the
scrap material.
15 A further aspect of the present invention is the manner of providing marker
notches in the pattern being cut. Marker notches are frequently used in
patterns
to give a small notch in the cut material. These notches indicate where the
material is to be folded or they can allow two pieces of material to be
aligned
while being sewn together. If a marker notch is be placed in a position where
two
Zo sections of rule are closely adjacent each other or butted against each
other,
allowance should be made for evacuation of the extra material cut by the
marker
notch. Several types of marker notches are contemplated by the present
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invention.
The first type of marker notch is bent or formed in the full depth of the
steel rule prior to joining adjacent cavities thereby allowing scrap material
to be
ejected from the rear of the cutting die with consecutive cuts. In this case
the
s portion of the substrate under the marker notch must be removed to allow
scrap
material to pass through. This type of marker notch can be used with either
the
reduced gap or the butted cavity techniques.
The second type of marker notch is made by forming the notch only in the
upper portion of the cutting blade prior to joining the adjacent cavities.
Prior to
~o forming the notch, an evacuation hole is made in the blade just below the
area to
be formed. The section of rule to be notched is then heated and formed using a
forming tool. The forming tool enters the steel with an upward motion so that
it
forces the cutting edge upwards as the knife is formed. Forming the notch in
this
manner ensures that the cutting edge does not dip during the forming operation
which would cause incomplete cuts at the notch locations. The forming tool is
made in an irregular configuration so as to bite into the steel while forming
it with
the upward motion, thus preventing the forming tool from sliding up the knife
edge. The formed notch can then be relieved below the knife edge, and the
evacuation hole ground at an angle to allow for smooth evacuation of the scrap
2o pieces. After the cavities are butted together, the mating area around the
hole is
sealed to the adjacent cavity using a suitable arrangement. This prevents
scrap
material from being wedged between the two adjacent cavities. This type of
notch
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causes scrap material to be evacuated to the top of the die rather than out
the
bottom as with the previous method.
This notch technique is also used to form notches in non joined areas of
the die with the elimination of the exhaust hole. It is also used in areas
where the
knives are diverging from a joined area. In this situation the bottom section
of the
exhaust hole is sharpened such that as the cut material is forced down past
the
notch, the notch is cut by sharpened hole, causing the notch portion of the
scrap
to be exhausted to the top of the die.
On long common edges, fabrication can be simplified by eliminating one of
1o the pieces of steel and joining the cavities at the intersection points at
each end
of the common area. Notches are accommodated by joining small pieces of steel
with notches formed into them, as explained above with the side outlet holes,
at
the notch locations. For straight sections opposite notches in adjacent
cavities,
small pieces of straight steel are joined opposite the notch leaving a
straight
1s section in the cavity and a notch in the adjacent cavity.
Another aspect of the invention allows for wandering gaps where two
adjacent cavities contact each other at several locations and diverge in
between
contact locations. Wandering gaps in the steel are accommodated by removing
the base substrate material between the two cavities and relieving the base of
the
2o steel between the cavities, allowing the scrap material to be ejected from
the rear
of the die. For longer sections, small pieces of steel rule can be joined
across the
gap every 3 to 6 inches along the cavity. These small pieces of steel serve to
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maintain the strength of the die as well as to cut the scrap material to be
ejected
from the rear of the die into smaller pieces which are more easily ejected.
The steel rule is attached to the substrate by cutting a groove in the
substrate and inserting the rule into the notch. The groove should not be cut
into
s the substrate over the entire periphery of a pattern or the center part of
the
pattern would be unsupported. Therefore bridges of substrate should be left in
place and the steel rule should be cut away to fit over the bridges. The
bridges
maintain the integrity of the base substrate. The bridges of adjacent cavities
should be aligned to maintain the strength of the board. The bridges may also
be
~o made larger than what is normally used to further enhance the integrity of
the
board.
The location of the groove in the substrate that holds the rule should be
shifted by a certain amount to account for the offset bevel in the rule. To
account
for the shift in the location of the groove, the groove should be cut with
great
accuracy. In order to facilitate accurate cutting of the offset pattern in the
base
substrate, it is preferred to use a computer controlled cutting apparatus. The
cutting apparatus preferably consists of an X-Y gantry system that supports
and
accurately positions a router driven rotary cutting tip. The X-Y gantry system
allows the cutter to traverse the substrate in the shape of the patterns to be
cut.
2o The cutter can be lowered to cut the grooves and raised to leave the
bridges in
the substrate. Cuts with such a table can easily be controlled to within ~
.010
inches as required for the shifting of the groove locations. Such a level of
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accuracy is difficult to obtain with conventional manual cutting techniques.
Another aspect of the present invention is the use of ejection foam. In
order to facilitate proper ejection of the cut patterns from the cavities and
the
scrap from between the cavities, foam is installed inside and around all
cavities.
It has been found that both open and closed cell foam with an Indentation
Force
Deflection (IFD) between 130 & 165 has yielded acceptable results.
It is an objective of the present invention to provide a multi-cavity steel
rule
die with adjacent cavities spaced less than'/ inch from each other.
It is a further objective of the present invention to provide a multi-cavity
~o steel rule die wherein adjacent cavities contact each other in one or more
locations.
It is a further objective of the present invention to provide a multi-cavity
steel rule die with complex shaped cavities that come in and out of close
proximity or contact with each other at several locations and diverge away
from
each other in between these locations.
It is a further objective of the present invention to provide a multi-cavity
steel rule die with adjacent cavities in close proximity or contact with each
other
in which material is easily expelled after a cutting operation.
It is a further objective of the present invention to provide a multi-cavity
2o steel rule die that can be easily cleaned and repaired.
It is a further objective of the present invention to provide a multi-cavity
steel rule die that include marker notches on portions of the steel rule where
inches as required for
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adjacent cavities are in close proximity or in contact with each other.
The foregoing and other objects and advantages of the invention will be
more fully understood from the following detailed description of the invention
and
from the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 A is a plan view of a prior art die with adjacent cavities spaced by
a'/ inch gap which is typical in the general practice in the industry.
Figure 1 B is a detailed view taken within circle 1 B of Figure 1A.
~o Figure 2A is a plan view of a die using smaller gaps between adjacent
cavities according to the present invention.
Figure 2B is a detailed view taken within circle 2B of Figure 2A.
Figure 3 is a sectional view taken along line 3 - 3 of Figure 1A.
Figure 4 is a sectional view taken along line 4 - 4 of Figure 2A.
Figure 5 shows the offset bevel rule of the present invention.
Figure 6 shows the serrated blade of the rule used in the present
invention.
Figure 7 is a perspective view showing two adjacent cavities in contact
with each other.
2o Figure 8. is a sectional view taken along line 8 - 8 of Figure 7.
Figure 9 is a plan view of a section of die with the substrate removed in
the areas where two sections of rule are diverging.
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Figure 10 is a perspective view of Figure 9.
Figure 11 is a perspective view of a section of rule with a first embodiment
of marker notch formed therein.
Figure 12 is a perspective view illustrating the process for forming a
second embodiment of marker notch.
Figure 13 is a perspective view of a section of rule with the second
embodiment of marker notch formed therein.
Figure 14 is a perspective view illustrating the process for forming a third
embodiment of marker notch.
~o Figure 15 is a perspective view of a section of rule with the third
embodiment of marker notch formed therein.
Figure 16 is a perspective view of a section of rule with a fourth
embodiment of marker notch formed therein.
Figure 17 is a perspective view showing two adjacent cavities with a
wandering gap.
Figure 18 is a perspective view of a section of substrate with a groove
formed therein for attaching the rule.
Figure 19 is a perspective view showing a portion of of the present
invention with ejection foam used therein.
2o Figure 20 is a perspective view of the cutting system used to cut slots in
the substrate of the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
One of the main features of the invention allows adjacent cavities on a
multi-cavity die to be nested more tightly with each other. The effect of
tighter
nesting according to the invention can be understood with reference to Figures
1A and 2A. Figures 1A and 2A show a die 1 with several cavities 2 mounted to a
substrate 3. Each cavity 2 is made of a length of steel rule 4 that is
attached to
the substrate. The steel rule 4 is sharpened so that when the die is placed
into a
press it can cut patterns in the shape of cavities 2 into a stack of material.
The
difference between Figures 1A and 1 B, and 2A and 2B, is that in Figures 1A
and
~0 1 B, the gap 40 between cavities which is commonly used in the industry
is'/
inch, and in Figures 2A and 2B, the cavities are spaced by a gap 42 of 1116
inch
so that the cavities can be more tightly spaced.
In the example shown in Figures 1A and 2A, the substrate 3 has a usable
width 44 of, for example, 60 inches. The usable width of each substrate is
determined by the width of the material to be cut. Material is bought in
standard
width bolts and so that dimension is fixed and is not a design variable when
designing a die. A certain amount of overhang space 46 must be left on the
sides
of the die to allow for misalignment of stacked layers of material on the die.
A
typical overhang space 46, as shown in Figures 1A and 2A, can be %2 inch. The
zo overhang space is a fixed dimension and is also not a design variable when
designing a die. Each cavity 2 of the die has a width of, for example, 11.7
inches.
In this example, the combined width of five cavities is 58.5 inches. The
substrate
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substrate 3 would have room to fit five cavities side by side across its width
except for the requirement that the cavities be separated by'/4 inch to allow
for
compression of scrap material between adjacent cavities. Because the prior art
embodiment is limited by the requirement for a'/inch gap between cavities, it
can
be seen in Figure 1A that only four cavities can fit across the width of the
substrate. Accordingly, a large amount of substrate area, and therefore
material,
is wasted. In Figure 2A, a gap 42 of only 1/16 inch is used between cavities
according to the present invention. With the smaller gap 42, it is possible to
fit a
fifth cavity in the width 44 of the substrate. In this example, it is clear
that the use
of smaller gaps between cavities can-have a large effect on the utilization of
material, and on the speed and efficiency of cutting operations.
It is apparent from Figures 2A, 2B, and 4, adjacent cavities can each
include adjacent linear portions of rule which are parallel to each other, and
that
the cutting edges 5 of the parallel linear portions can be separated by a gap
42 of
less than'/4 inch.
Figure 3 shows the rule of adjacent cavities using the industry typical'/4
inch gap 40 between cavities. The tips 5 of the cutting edges on rule 4 are
thus
spaced apart by gap 40 of '/inch. If the typical rule 4 has a width or
thickness of
085 inches, the material 6 being cut is compressed between the two cavities
2o from the gap 40 of .25 inches to a rule segment spacing 48 of .165 inches.
The
material is therefore compressed by 34%. If the rule 4 of adjacent cavities
were
moved closer to each other than the gap 40 of'/4 inch, the material 6 would be
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compressed by a higher percentage. Many in the industry accept that'/ inch is
the closest the rule can be moved together.
The present invention uses offset bevel rule as shown in Figure 4 to
reduce the amount of material that is compressed between the rule of adjacent
s cavities. Offset bevel rule can be purchased from National Steel Rule
Company
of Linden, NJ. The offset bevel rule used is shown in more detail in Figure 5.
The
rule 4 may have some similar qualities to the center bevel rule shown in
Figure 3.
For example, a thickness t of .085 inches, the height, and a material of alloy
steel
may be used. One difference between offset bevel rule and center rule is in
the
~o placement and type of its cutting edge. The rule used in the present
invention is
preferably serrated as can be seen looking at the side of a section of rule in
Figure 6. In Figure 6 the rule 4 can be seen to have serrations 36. Each
serration
36 should be arcuate in shape with a concave portion of each serration
pointing
towards the cutting edge of the rule 4. The rule preferably includes 11 - 14
serrations per inch of length.
The rule can be seen in Figure 5 to have a thickness t with a cutting edge
or tip 5 that is displaced from the geometric center of the thickness of the
rule.
Side 7 of the rule 4 is situated towards the outside of a cavity in the die.
Side 8 of
the rule 4 is situated towards the inside of a cavity in the die. Between the
cutting
2o tip 5 and the inner side 8 of the rule there is a major bevel which has a
dimension
in the plane of the thickness of b~. Between the cutting tip 5 and the outer
side 7
of the rule there is a minor bevel which has a dimension in the plane of the
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thickness of b2. The major bevel dimension b~ is preferably between 65% to 95%
as wide as the thickness t of the rule. In one preferred embodiment, the major
bevel dimension b~ is 86% as wide as the rule. The slope of the minor bevel
forms an angle 8 to vertical as shown in Figure 5. The slope 8 of the minor
bevel
s may be any angle between 20° - 35°, but is preferably
27°. The minor bevel is
used to increase the strength of the rule. The larger the dimension b2 of the
minor
bevel, the stronger the rule will be. However, increasing the dimension b2 of
the
minor .bevel also compresses the cut material between cavities by a larger
amount, and so the cavities may need to be spaced by a larger gap. The exact
~o position of the cutting tip 5 and the exact relative dimensions of the
major bevel
b~ and the minor bevel b2 are dependent on the particular application. The
amount
of offset to be used in the rule is influenced by the type and thickness of
material
being cut and the size and shape of patterns being cut.
Referring to Figure 4, the lengths of rule of adjacent cavities can be seen
to have their outer sides 7 facing each other. Therefore the minor bevels b2
of the
two lengths of rule also face each other. The material 6 between the adjacent
cavities is compressed by the amount of two times the dimension b2 of the
minor
bevel. in the example shown, the cutting tips 5 of the two lengths of rule are
spaced by 1116 inch (.0625"), and the dimension b2 of the minor bevel of the
rule
2o is .012 inches. Therefore, the material 6 between the cavities is
compressed from
.0 25 inches to .0385 inches. This is a compression of the material by 38%. If
the
minor bevel of the rule is smaller, the gap between cavities can be smaller.
If the
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minor bevel of the rule is larger, the gap between the cavities must be
larger. It
has been found that gaps between cavities of 1116 to 3116 inch are preferred.
Additionally, it is recognized that-the present invention permits the
efficiency of numerous cavity shapes and configurations to be maximized. For
example, one such configuration can provide adjacent portions of rule in
adjacent
cavities wherein the cutting edges of the adjacent portions of rule are
separated
by a gap of less than '/ inch at two spaced apart locations and are separated
by
a gap of more than '/ inch in areas between the spaced apart locations.
In certain applications it may be possible to eliminate the minor bevel of
~o the rule entirely, i.e., make the dimension b2 equal to zero. With no minor
bevel,
the dimension b, of the major bevel is equal to the thickness t of the rule:
This
type of rule is herein referred to as side bevel rule. By using side bevel
rule the
gap between cavities can be completely eliminated and adjacent cavities can
butt
up against each other. Figures 7 and 8 show a portion of a die with side bevel
rule being used to eliminate the gap between cavities. The rule of a first
cavity 9
and the rule of an adjacent second cavity 10 can be seen to converge at points
11 and 12. Between points 11 and 12 the lengths of rule of cavities 9 and 10
are
touching and there is no gap between the cavities. The common section of rule
can be joined by a variety of techniques such as welding, silver soldering,
Zo brazing, riveting, or a combination of these. The cavities 9 and 10 can
touch
each other over a section of common rule as shown in Figure 7 or they can
touch
at a single point and then diverge again immediately. In this way the gap can
be
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eliminated between cavities of any geometry.
Figure 8 shows a cross section of the rule of adjacent cavities 9, 10 in the
area that they touch each other. The rule can be seen to have a dimension b2
of
the major bevel that is the same as the thickness t of the rule. Therefore the
cutting tips 5 of the rule are at the outside edges of the rule. When the fiwo
sections or rule touch each other the cutting tips 5 of the two sections
substantially coincide with each other. The two sections of rule therefore can
function as a section of center bevel rule with twice the thickness of rule.
It can be
seen that the material 6 is compressed only into the interior of each cavity
and no
~o material is compressed between the two sections of rule.
The arrangement in Figure 8 can also be achieved by using offset bevel
rule in which the portions of adjacent rule are removed such that in adjacent
contacting areas the minor bevel is zero. This arrangement provides the
additional advantages of having lengths of rule with enhanced strength in the
areas which do not contact each other.
The choice of whether to use offset bevel rule to reduce the gap between
adjacent cavities or to use side bevel rule to completely eliminate the gap
between cavities is a dependent on the particular application. The choice may
be
influenced by the type and thickness of material being cut and the size and
shape
20 of patterns being cut. The use of offset bevel rule and side bevel rule are
not
mutually exclusive. Indeed, in many applications, a combination of offset
bevel
rule and side bevel rule may be the most appropriate choice. In this case some
CA 02462704 2004-04-19
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adjacent cavities could have a reduced gap between them and other adjacent
cavities could have no gap between them. If side bevel rule is used to
eliminate
the gap between adjacent cavities, provisions should be utilized to prevent
small
scraps of material getting caught between the rule of adjacent cavities,
especially
s if the two cavities diverge at a small angle. One aspect of the present
invention
relieves this problem by removing the substrate in areas where the lengths of
rule
of two adjacent cavities diverge at a small angle. Figure 9 shows a portion of
a
die where two adjacent cavities 9, 10 converge to touch each other and then
diverge again. The adjacent cavities 9, 10 touch each other at points 11, 12
and
~o immediately adjacent the points 11, 12 the lengths of rule of cavities 9,
14, form a
small angle relative to each other. In the area where the lengths of rule of
adjacent cavities form a small angle a portion of the substrate 3 has been
removed to form holes 13. As shown by rows 14 in Figure 10, the material
scraps that would normally become wedged in the small crevices between
~s adjacent cavities can now pass through the holes 13 and be ejected out the
back
side of the substrate 3.
In many applications, it may be desired or necessary to make marker
notches in the pattern of one or more cavity of the die. Marker notches put
notches in the resulting cut piece of material. The marker notches are used in
zo assembling the material into finished products. Sometimes the marker
notches
may be used to mark the location of a fold in the material. Other times, if
two
pieces of material are to have a long seam sewn between them there may be
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corresponding marker notches in each of the two pieces so that the notches can
be aligned during sewing to assure that the pieces are properly aligned. The
marker notches are usually small triangular shaped cutouts along the periphery
of
the pattern. If a marker notch is be placed in an area where the gap between
adjacent cavities has been reduced or eliminated, then some allowance should
be made for evacuation of the extra scrap material created by the notch.
Figure 11 shows one embodiment of a marker notch formed in the rule. In
Figure 11, two sections of rule 4 from two adjacent cavities 9, 10 touch each
other along one section. In the middle of this section, the rule 4 of cavity
10 has a
~o marker notch 15 formed therein. Marker notch 15 is merely a triangular
shaped
bend formed in the rule 4. !n this embodiment the marker notch 15 is formed
over
the entire height of the rule 4 so that the space between cavities 9 and 10
form a
triangular shaped cylinder at the marker notch 15. An extra scrap of material
will
be formed by marker notch 15 and there should be provision for evacuating that
~s scrap. In this embodiment, the substrate 3 of the die is removed in an area
corresponding to the cross section of marker notch 15. As indicated by arrow
16
the scrap material can now pass through the substrate 3 and be ejected out of
the back of the die.
A second embodiment of marker notch is shown in Figures 12 and 13.
2o Here the marker notch 16 is formed only in the top portion of the rule 4.
Before
forming the notch 16 in the rule 4, a hole 17 is drilled in the rule at the
bottom
extent of the marker notch. After drilling the hole 17 in the rule 4 a notch
16 is
CA 02462704 2004-04-19
-21 -
stamped into the portion of the rule that is above hole 17. The notch 16 is
stamped into rule 4 by forcing dies 18 and 19 together over the portion of the
rule
above hole 17. Die 18 is a male die and die 19 is a female die and both dies
are
of the shape of notch 16. Male die 18 forces the rule 4 into the female die 19
so
s that the rule takes the shape of the notch 16. In stamping the notch 16 into
rule
4, it is preferred that the male die 18 be moved with an upward movement so
that
the rule 4 remains at the same height over notch 16 and does not dip
downwardly. The die 18 is preferably made with an irregular edge so that it
can
bite into the rule and not slide over the rule. After the notch has been
formed in
~o the rule the bottom of the hole 17 is ground at an angle to form a bevel 20
on the
bottom of t hole. The bevel 20 allows scrap material to evacuate through the
hole
17 as shown by arrow 21.
If the rule 4 of adjacent cavities 9, 10 do not touch each other, it is
possible to form a third type of marker notch. The third embodiment of marker
notch is shown in Figures 14 and 15. In this embodiment the rule 4 does not
get
a hole drilled in it as described above. Rather a notch 22 is formed in the
top
portion of a solid rule 4. The notch 22 is formed by stamping between two dies
18, 19 as described above. When marker notches of this type are used in
sections of adjacent cavities 9, 10, the marker notch material will compress
into
2o the gap between cavities. It may be necessary to use a slightly larger gap
between adjacent cavities 9, 10 when using this type of marker notch.
If there are long straight sections between adjacent cavities; it may be
desirable
CA 02462704 2004-04-19
-22-
to use a single piece of rule to define the common border of the two cavities
as
shown in Figure 16. The lengths of rule of cavities 9, 10 can be joined at
intersection points 11, 12 and a single piece of rule used in between. If a
marker
notch is to be placed in the area of common rule, then a small piece of rule
with a
s notch 16 formed therein can be attached to the long stretch of single rule
at the
appropriate locations. The notch 16 in this embodiment is preferably the type
described in the second embodiment of marker notch above. The marker notch
preferably has a scrap evacuation hole 17 with a bevel 20 on the bottom
thereof
so that scrap material can escape as shown by arrow 21.
~o One of the advantages of the present invention is its ability to adapt to
complex shapes of cavities. Adjacent cavities can converge for long straight
sections, a single point of contact, or have wandering gaps where two adjacent
sections come into and out of contact with each other. Figure 17 illustrates a
wandering gap where the rule 4 of adjacent cavities come into contact with
each
~s other at two points 23, 24 and diverge again, between points 23, 24. In the
gap
between points 23, 24, the substrate 3 should be removed to allow scrap
material
to be evacuated through the back of the die as shown by arrows 25. If the gap
between points 23, 24 is long and/or wide, the rule 4 of cavities 9, 10 may be
Weakened in the area of the gap because the removed substrate can not support
2o the rule. Therefore, it may be desirable to join an extra piece of rule 26
to the
rule of cavities 9, 10. The extra piece of rule 26 forms a bridge to
strengthen the
rule of cavities 9, 10. Extra rule 26 also serves to cut scrap material into
smaller
CA 02462704 2004-04-19
-23-
pieces for easier evacuation. Bridges should preferably be placed every 3 to 6
inches along the gap between adjacent cavities.
The steel rule 4 is attached to the substrate 3 of the die by cutting a slot
27 in the
substrate and inserting the rule into the slot in the substrate. The slot 27
cannot
be cut along the entire periphery of the cavities or the substrate in the
middle of
the cavities would not be supported and would fall out. Therefore the slots 27
should be cut intermittently as shown in F re 18. The gaps between portion of
slot 27 are known as bridges 28. Where two sections of adjacent cavities are
closely spaced according to the present invention, it is important that the
bridges
~0 28 of adjacent cavities be aligned with one another. By so aligning the
bridges
28 of adjacent cavities, the strength and integrity of the substrate 3 is
maintained.
If the bridges 28 of adjacent cavities are not aligned when the cavities are
in
close proximity to each other the substrate will likely be weakened along the
slots
and could crack or split.
Figure 19 shows the die of the present invention with ejection foam
mounted thereon to facilitate removal of material from the die after it has
been
cut. The die is the same as described above with sections of rule 4 inserted
into
slots in substrate 3 to form die cavities. The difference is that foam 29 has
been
attached to the substrate 3 by an appropriate technique. Foam 29 is
2o compressible so that it is compressed as material is cut by rule 4. After
the
material has been cut, the foam 29 expands to its original shape and forces
the
material out of the die. This makes removal of material from the die easier
and
CA 02462704 2004-04-19
-24-
speeds up the cutting process. it has been found that both open and closed
cell
foam with an Indentation Force Deflection (IFD) between 130 & 165 yields
acceptable results. When portions of the substrate have been removed to allow
material to pass through the back of the substrate, no ejection foam is used
on
those portions.
It is preferable that the slots be cut very precisely into the substrate. In
conventional dies, the slots are cut in the substrate with the center of the
slot
defining the shape of the cavities. Because of the offset bevel of the rule
used in
the present invention, the slots should be offset by a small amount. The small
~o offset in the location of the slots allows the cutting edge of the rule to
define the
proper shape of the cavity. In order to cut the slots in exactly the proper
position
on the substrate, it may be necessary to cut the slots to within a precision
of ~
.010 inches. This precision may be very difficult to achieve with conventional
manual cutting techniques. in prior embodiments, slots are typically cut into
the
~5 substrate by drilling a hole in the substrate, inserting a jigsaw blade
into the hole,
and manually cutting the slot with a jigsaw. However, not only does the
conventional manual cutting process lack the desired accuracy, but the
drilling of
a starting hole to allow the jigsaw blade to be inserted weakens the
substrate. !n
areas where two cavities are close to each other, the starting hole may extend
a!1
2o the way into the slot of the adjacent cavity further weakening the
substrate. In
order to cut slots accurately in the substrate without need to drill starting
holes,
an automated cutting set-up is proposed.
,, CA 02462704 2004-04-19
-25-
Figure 20 shows the automated cutting apparatus used to cut slots in the
substrate. The cutting apparatus has a cutting table 30 onto which a substrate
3
is laid. An X-Y cutfiing system is mounted on the table 30. The X-Y cutting
system consists of a pair of side rails 31 fixedly mounted to the sides of the
table
30 with their longitudinal axes extending in the X direction as shown in
Figure 20.
A gantry 32 extends between the side rails 31. The gantry is supported on the
rails 31 by wheels or other structure that allow the gantry to move back and
forth
in the x direction along rails 31. The gantry's longitudinal axis extends in
the Y
direction as shown in Figure 20. A mounting device 33 is movably mounted to
~o gantry 32 so as to-be able to move in the y direction along gantry 32. The
mounting device 33 is also capable of reciprocating motion in a vertical
direction
so as to be able to extend and retract the cutter. Attached to mounting device
33
is the slot cutter which consists of a spindle motor 34 and a cutting tip 35.
When
spindle motor 34 is activated, the cutting tip 35 spins and is capable of
cutting
~s slots 27 in substrate 3. The motion of the gantry 32 on the side rails and
the
motion of mounting device 31 on the gantry 32 are computer controlled. By
controlling these two motions simultaneously, it is possible to cause the
cutting tip
35 to traverse any desired path and cut the slots 27 in the desired pattern in
substrate 3. By moving the mounting device 33 downwardly to extend the cutting
Zo tip 35 the slots 27 will be cut in the substrate 3. If the mounting device
33 is
moved upwardly the cutting tip 35 will be retracted and no slot will be cut in
the
substrate 3. In this way it is possible to cut slots 27 in some locations
while
CA 02462704 2004-04-19
-26-
leaving bridges 28 intact in other locations.
Accordingly, a multi-cavity die has been presented in which the gap
between adjacent cavities can be reduced from the frequently used '/d inch, to
as
little as 1 /16 inch, or even eliminated in some applications. Complex shapes
of
cavities can be accommodated with the present invention. Allowance has been
made for evacuation of scrap material out of the back of the die in areas of
tight
crevices between cavities or in marker notches. Because individual cavities
can
be used without need to attach the rule of adjacent cavities along common
sections, cleaning and repair of the die is easily facilitated. The die is
simple and
~o inexpensive to fabricate and is rugged and durable in use.
While preferred embodiments of the invention have been shown and
described, it will be apparent to those skilled in the art that various
modifications
may be made in these embodiments without departing from the scope of the
invention. Therefore, it is intended that the invention not be limited to the
15 particular embodiments disclosed but that the scope of the invention be
defined
by the following claims.
