U.S. patent application number 15/753543 was filed with the patent office on 2018-08-23 for cupper draw pad.
The applicant listed for this patent is Anheuser-Busch, LLC. Invention is credited to Scott Schaefer, Mark Schremmer, Mark Wagner.
Application Number | 20180236525 15/753543 |
Document ID | / |
Family ID | 56843045 |
Filed Date | 2018-08-23 |
United States Patent
Application |
20180236525 |
Kind Code |
A1 |
Schremmer; Mark ; et
al. |
August 23, 2018 |
Cupper Draw Pad
Abstract
A draw pad reduces instances and the extent of earing when a
blank of metal is clamped and punched during a drawing process that
results in the formation a cup-shaped body from the blank A draw
pad for a cupping press includes an inner surface that defines a
draw aperture that is configured to receive a punch. The draw pad
also includes a clamping surface that has a first force
concentrating segment disposed circumferentially spaced apart from
a second force concentrating segment, where each force
concentrating segment includes a first arcuate groove and a second
arcuate groove that is disposed concentric and radially spaced
apart from the first arcuate groove.
Inventors: |
Schremmer; Mark; (O'Fallon,
MO) ; Schaefer; Scott; (St. Louis, MO) ;
Wagner; Mark; (St. Louis, MO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Anheuser-Busch, LLC |
St. Louis |
MO |
US |
|
|
Family ID: |
56843045 |
Appl. No.: |
15/753543 |
Filed: |
August 19, 2016 |
PCT Filed: |
August 19, 2016 |
PCT NO: |
PCT/US2016/047847 |
371 Date: |
February 19, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62207722 |
Aug 20, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21D 22/20 20130101;
B21D 24/04 20130101; B21D 22/22 20130101; B21D 22/28 20130101; B21D
51/26 20130101 |
International
Class: |
B21D 51/26 20060101
B21D051/26; B21D 24/04 20060101 B21D024/04; B21D 22/28 20060101
B21D022/28 |
Claims
1-32. (canceled)
33. A draw pad for a cupping press, comprising: an inner surface
defining a draw aperture configured to receive a punch; a clamping
surface having a first force concentrating segment
circumferentially separated by a relief area from a second force
concentrating segment, each of the force concentrating segments
comprising a first arcuate groove radially spaced apart by a first
distance from an adjacent second arcuate groove, the relief area
having a first arcuate groove radially spaced apart by a second
distance from an adjacent second arcuate groove, the second
distance being greater than the first distance.
34. The draw pad of claim 33 wherein a first radial width of the
arcuate grooves of the force concentrating segments is greater than
a second radial width of the arcuate grooves of the relief
area.
35. The draw pad of claim 33 wherein the relief area has a
circumferential width between 10 and 20 degrees.
36. The draw pad of claim 33 wherein the clamping surface further
comprises a third and a fourth force concentrating segment, wherein
each force concentrating segment is circumferentially separated
from an adjacent force concentrating segment by a relief area.
37. A draw pad for a cupping press, comprising: an inner surface
defining a draw aperture configured to receive a punch; a clamping
surface configured to hold a blank of material to be formed into a
cup-like shape, the clamping surface comprising a plurality of
annular grooves, each groove being concentric to the draw aperture,
and a plurality of relief areas each defined by a depression in the
clamping surface disposed adjacent the inner surface.
38. The draw pad of claim 37 wherein the plurality of relief areas
comprises four relief areas equally circumferentially spaced
apart.
39. The draw pad of claim 37 wherein each relief area is spaced
apart approximately 90 degrees from a circumferentially adjacent
relief area.
40. The draw pad of claim 37 wherein a floor surface of each relief
area is concave and tapered to increase in depth toward the inner
surface.
41. The draw pad of claim 37 wherein each relief area bisects at
least one of the plurality of annular grooves.
42. The draw pad of claim 37 wherein each relief area does not
intersect any of the plurality of annular grooves.
43. The draw pad of claim 37 wherein the inner surface is
cylindrical and the clamping surface is circular.
44. A method for reducing earing in a drawn cup, comprising:
positioning a sheet of metal between a draw pad and a
blank-and-draw die; clamping the sheet of metal between the draw
pad and the blank-and-draw die by contacting a clamping surface of
the draw pad to a portion of the sheet of metal, wherein the
clamping surface has four force concentrating segments each
circumferentially equally spaced apart from an adjacent force
concentrating segment, wherein each force concentrating segment
comprises a first arcuate groove and a second arcuate groove
disposed concentric and radially spaced apart from the first
arcuate groove; shearing the sheet of metal to create a blank
having a disk shape; and directing a punch to displace a portion of
the blank into a die cavity and forming the blank between the punch
and the blank-and-draw die into a cup-like shape.
45. The method of claim 44 wherein the sheet of metal is
anisotropic and has a rolling direction.
46. The method of claim 45 wherein areas between adjacent force
concentrating segments are each offset 45 degrees from the rolling
direction.
47. The method of claim 44 wherein the sheet of metal comprises
aluminum.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application for Patent Ser. No. 62/207,722, filed Aug. 20, 2015,
which is hereby incorporated by reference.
TECHNICAL FIELD
[0002] This disclosure relates to a tool for use in manufacturing
metal containers, and in particular, to a cupper draw pad that
reduces earing during a drawing process.
BACKGROUND OF THE DISCLOSURE
[0003] Thin-walled, two-piece metal containers are often produced
using drawing processes. In a drawing process, a flat circular
blank of sheet metal, for example aluminum, is drawn through one or
more drawing dies to form a shallow preform cup. The blank of sheet
metal used to form the preform cup has a particular anisotropy,
which is the directional variation of sheet metal's mechanical
properties. In other words, the blank of sheet metal will react
differently to stresses applied in one direction than it would to
the same stresses applied in a different direction.
[0004] The drawing process employs a cupping press or a cupper. A
circular blank is cut from a sheet of material and is positioned
over a die cavity. The circular blank is held against a die by a
cupper draw pad, and a punch pushes the blank into the cavity with
enough pressure and force to form the blank into a cup-like shape.
The anisotropic properties of the blank of sheet metal contribute
to earing formation on the open end of a drawn cup. Earing is the
formation of uneven or wavy edges at the open end of the drawn cup.
The problem of earing is attributable to the drawing process, and
the anisotropy of a blank of sheet metal is the predominate cause
of earing. Ears are formed approximately 45 degrees from the
rolling direction of the sheet. These ears are the last material to
remain clamped in the drawing process. At that time, all the
clamping forces concentrate on those ears and can cause them to
become pinched or thinned. Earing is problematic in that it may
cause material to be wasted, such as when the earing portion of the
drawn cup needs to be cut away, or it may lead to undesirable metal
portions that may disrupt downstream formation processes.
[0005] In order to reduce undesirable earing, non-round blanks are
sometimes cut from the sheet of metal. Non-round blanks, however,
often have less material available approximately forty-five degrees
to the material grain, i.e., the direction the sheet metal was
rolled, and require more complex and expensive tooling in the
cupping press and in downstream manufacturing processes.
SUMMARY
[0006] According to the teaching of the present disclosure, a draw
pad reduces instances and extent of earing when a blank of metal is
clamped and punched during a drawing process that results in a
cup-shaped body. The ears that would be produced using a
conventional cupping press with a conventional draw pad are reduced
or eliminated, and therefore do not interfere in subsequent forming
operations of the cup-shaped body, for example, forming operations
that forms the cup-shaped body into a metal can or an elongated
metal bottle-shaped container.
[0007] According to one embodiment, a draw pad for a cupping press
includes an inner surface that defines a draw aperture that is
configured to receive a punch. The draw pad also includes a
clamping surface that has a first force concentrating segment
disposed circumferentially spaced apart from a second force
concentrating segment, where each force concentrating segment
includes a first arcuate groove and a second arcuate groove that is
disposed concentric and radially spaced apart from the first
arcuate groove.
[0008] According to an alternate embodiment, a draw pad for a
cupping press reduces earing formation in the drawn cup-shaped
body. The draw pad includes an inner surface that defines a draw
aperture that is configured to receive a punch. The draw pad also
includes a clamping surface that has a first force concentrating
segment that is circumferentially separated by a relief area from a
second force concentrating segment, where each of the force
concentrating segments include a first arcuate groove that is
radially spaced apart by a first distance from an adjacent second
arcuate groove. The relief area has a first arcuate groove that is
radially spaced apart by a second distance from an adjacent second
arcuate groove, where the second distance being greater than the
first distance.
[0009] According to still another embodiment of the present
disclosure, a method of forming a cup-shaped body with reduced
earing includes the steps of positioning a sheet of metal between a
draw pad and a blank-and-draw die. The sheet of metal is clamped
between the draw pad and the blank-and-draw die by contacting a
clamping surface of the draw pad to a portion of the sheet of
metal. The clamping surface has four force concentrating segments
that are each circumferentially equally spaced apart from an
adjacent force concentrating segment. Each force concentrating
segment includes a first arcuate groove and a second arcuate groove
that is disposed concentric and radially spaced apart from the
first arcuate groove. The sheet of metal is sheared to create a
blank that has a disk shape. A punch is directed to displace a
portion of the blank into a die cavity and thereby form the blank
between the punch and the blank-and-draw die into a cup-like
shape.
[0010] Technical advantages of the disclosed embodiments include a
draw pad with specifically located relief areas that allow for more
even distribution of gripping forces in areas of the metal blank
that are most susceptible to earing. According to other
embodiments, areas of a draw pad that contact a blank in locations
that are susceptible to earing include depressions in the clamping
surface that are generally in the shape of an ear that might be
formed using conventional draw pads.
[0011] Other aspects, features, and advantages will become apparent
from the following detailed description when taken in conjunction
with the accompanying drawings, which are a part of this disclosure
and which illustrate, by way of example, principles of the
inventions disclosed.
DESCRIPTION OF THE FIGURES
[0012] A more complete understanding of the method and apparatus of
the present invention may be acquired by reference to the following
Detailed Description when taken in conjunction with the
accompanying Drawings wherein:
[0013] FIGS. 1A and 1B are exploded, perspective views of a draw
pad and casing assembly in accordance with this disclosure;
[0014] FIG. 2 is a plan view of a clamping surface of the draw pad
of FIGS. 1A and 1B;
[0015] FIG. 3 is a section view of the draw pad of FIG. 2;
[0016] FIG. 4 is a plan view of a clamping surface of an alternate
embodiment of a draw pad according to the present disclosure;
[0017] FIG. 5 is a plan view of a clamping surface of an additional
alternate embodiment of a draw pad according to the teachings of
the present disclosure;
[0018] FIG. 6 is a plan view of a clamping surface of another
alternate embodiment of a draw pad according to the teachings of
the present disclosure; and
[0019] FIG. 7 illustrates a cupping press, with portions shown in
section view, including a draw pad according to the teachings of
the present disclosure.
DETAILED DESCRIPTION
[0020] FIGS. 1A and 1B illustrate exploded, isometric views of a
draw pad assembly 100, where FIG. 1A is a view toward a clamping
surface 120, and FIG. 1B is a view in a direction opposite the view
direction of FIG. 1A. The draw pad assembly 100 is part of a die
assembly used in a drawing process. The draw pad assembly 100
includes a draw pad 102 and a casing 104. The draw pad 102 is
formed of an ultra-hard material such as carbide, and the casing
104 is formed of a softer material. According to one embodiment,
the draw pad 102 is formed of a carbide material with a nickel
binder, and the casing 104 is formed of tool steel. When a cup is
formed, a metal sheet is clamped between the draw pad 102 and a
blank-and-draw die to allow a punch to form the metal into a
cup-like part as it forces the metal into a die cavity and the
metal flows between the punch and the blank-and-draw die. The
machine that includes the punch, the draw pad 102, the casing 104,
and the blank-and-draw die is often referred to as a cupping press
or a cupper because it is used to form hollow, cylindrical parts
with an open end that resemble a cup. The draw pad 102 disclosed
herein reduces the formation of ears, also referred to as earing,
in the drawn cup.
[0021] Embodiments of the draw pad 102 of the present disclosure
are used to form an elongated cup that undergoes subsequent metal
forming operations, such as ironing and necking, and is formed into
a metal can or a metal bottle-shaped container. A variety of
different draw pad configurations may be used and the
configurations may be based on the size and shape of the part to be
drawn, the type of material used for the blank, as well as the type
of drawing process employed. Some non-limiting, illustrative
embodiments of draw pads that may be used in the draw pad assembly
100 are disclosed herein.
[0022] With reference to FIG. 1B, the draw pad 102 includes a neck
portion 106, a shoulder portion 108, and one or more blind
apertures formed in the shoulder portion 108. In certain
embodiments, a threaded insert 110 is secured in the blind
aperture. The neck portion 106 is in the form of a cylindrical ring
extending from the shoulder portion 108. The neck portion 106, the
shoulder portion 108 and the one or more apertures including the
threaded insert 110 are configured to ensure a secure fit between
the draw pad 102 and the casing 104. According to one embodiment, a
fastener extends through a corresponding through hole 111 in the
casing 104 and is threaded to the threads of the insert 110 to
secure the draw pad 102 to the casing 104. In addition to or in
lieu of attaching the casing 104 to the draw pad 102 using a
threaded connector, the shoulder may include a back taper that can
shrink-fit with the casing 104. An adhesive may also be used to
further ensure that the draw pad 102 is securely attached to the
casing 104. According to one embodiment, the casing 104 may include
inserts 113, made of a resilient material, such as rubber, disposed
around an outer perimeter of the casing 104. The resilient inserts
113 serve as bumper pads with respect to the cylinder of the
cupping press that houses the casing 104.
[0023] The shoulder portion 108 typically has a diameter greater
than the diameter of the neck portion 106. In some embodiments, the
shoulder portion 108 has a diameter (outer diameter) that is
approximately 7 inches. However, it should be appreciated that the
diameter of the shoulder portion 108 may be greater than or less
than 7 inches as needed by the die assembly. An inner surface 112
of the draw pad 102 defines a draw aperture 114 for receiving the
punch (see FIG. 7). The draw aperture 114 is centrally located and
has a circular shape. The draw aperture 114 may have a diameter of
approximately 4.5 inches in some embodiments. However, it should be
appreciated that the draw aperture 114 may have a diameter greater
than or less than 4.5 inches. The inner surface 112 may be annular
or ring-shaped resulting in a cylindrical draw aperture 114. The
draw aperture 114, however, may take a number of shapes to include
square, rectangular, oblong, or any other shape.
[0024] FIG. 2 illustrates a plan view of an embodiment of the draw
pad 102 showing the clamping surface 120, and FIG. 3 illustrates a
cross-sectional view of the draw pad 102 according to one
illustrative embodiment. As discussed above, the draw pad 102 has a
clamping surface 120 that is configured to be clamped or otherwise
gripped against a blank to be formed into a cup-like shape through
the drawing process.
[0025] The clamping surface 120 of the draw pad 102 includes at
least a first annular row of grooves 122. In some aspects, the draw
pad 102 further includes a second annular row of grooves 126, a
third annular row of grooves 128, a fourth annular row of grooves
130, a fifth annular row of grooves 132, any combination thereof,
or even more annular rows of grooves. In some aspects, the first
annular row of grooves 122 is concentric to the draw aperture 114.
In still some aspects, the first, the second, the third, the fourth
and the fifth annular rows of grooves 122, 126, 128, 130, 132 are
concentric to the draw aperture 114. The first, the second, the
third, the fourth and the fifth annular rows of grooves 122, 126,
128, 130, 132 may be evenly spaced apart from each other along a
radial direction or have varying radial distances from each
other.
[0026] The annular rows of grooves are created by removing material
from the clamping surface 120. A ridge 121 is disposed between
radially adjacent grooves. In the area of the clamping surface 120
where the grooves are formed, the ridges 121 contact the blank
during drawing. Thus, the clamping forces on the blank are
concentrated by the ridges 121. It has been found that by creating
relief areas by eliminating the grooves and thereby the ridges 121
in certain areas of the clamping surface 120, or reducing the
grooves and increasing the surface area of the ridges 121, reduces
the occurrence of earing as the drawing process is completed. More
specifically, if the rolling direction of the material of the
blank, such as rolled aluminum, is 0/180 degrees, then eliminating
or reducing grooves at a position between 40-50 degrees, for
example 45 degrees, from the rolling direction reduces earing in
the drawn cup because the clamping forces are more evenly
distributed in these relief areas.
[0027] Earing is commonly referred to as "45 degree ears" because
they occur approximately 45 degrees from the rolling direction, but
the actual location of earing for a particular metal blank may
vary, for example from 40-50 degrees from the rolling direction and
may not be exactly at 45 degrees from the rolling direction. Thus,
the relief areas as shown and described throughout this disclosure
are contemplated to be disposed between 40-50 degrees from the
rolling direction.
[0028] In some aspects, the first, the second, the third, the
fourth and the fifth annular rows of grooves 122, 126, 128, 130,
132 extend into the draw pad 102 at a depth of between 0.001 to
0.009 inches. In some aspects, the depth is 0.003 inches. The width
of the first, the second, the third, the fourth and the fifth
annular rows of grooves 122, 126, 128, 130, 132 may be
approximately 0.09 inches. In some embodiments the width of the
first, the second, third, the fourth and the fifth annular rows of
grooves 122, 126, 128, 130, 132 may be greater than or less than
0.09 inches. For example, the width may be 0.01 to 0.1 inches. In
yet some aspects, the first, the second, the third, the fourth and
the fifth annular rows of grooves 122, 126, 128, 130, 132 each has
a diameter of between 5 and 7 inches. In one embodiment, the first
annular row of grooves 122 has a diameter of approximately 5.2
inches, the second annular row of grooves 126 has a diameter of
approximately 5.5 inches, the third annular row of grooves 128 has
a diameter of approximately 5.9, the fourth annular row of grooves
130 has a diameter of approximately 6.3, and the fifth annular row
of grooves 132 has a diameter of approximately 6.7 inches.
[0029] Each annular row of grooves may be comprised of one
continuous groove or be divided into multiple segments or
individual grooves. As illustrated in FIG. 2 and according to an
exemplary non-limiting embodiment, the first, second, third,
fourth, and fifth annular rows of grooves 122, 126, 128, 130, 132
are divided into a first segment 134, a second segment 136, a third
segment 138, and a fourth segment 140 where each segment is
separated from an adjacent segment by a relief area that interrupts
or otherwise bisects or divides the annular row of grooves.
[0030] Each of the segments 134, 136, 138, and 140 is a force
concentrating segment because the arcuate grooves in each segment
create the ridges 121, which concentrate the clamping force in the
area of the blank in contact with the force concentrating segments
134, 136, 138, and 140. The ridges 121 do not extend above the
surface of the clamping surface, so they may be more accurately
described as force concentrating regions 121 that are located
between adjacent radially spaced apart arcuate grooves. For
example, a force concentrating region 121 is disposed between the
first arcuate groove 122 and the radially spaced apart second
arcuate groove 126 in each force concentrating segment.
[0031] Relief areas or force distributing segments, such as the at
least one relief area 142, are positioned between the segments or
in the annular row of grooves. In some aspects, there are multiple
relief areas. As illustrated in FIG. 2, the first relief area 142
is positioned between the first segment of grooves 134 and the
second segment of grooves 136, a second relief area 144 is
positioned between the second segment of grooves 136 and the third
segment of grooves 138, a third relief area 146 is positioned
between the third segment of grooves and the fourth segment of
grooves 140, and a fourth relief area 148 is positioned between the
fourth segment of grooves 140 and the first segment of grooves 134.
In this embodiment, the relief areas 142, 144, 146, 148 are
coplanar with the ridges 121. In other words, the relief areas 142,
144, 146, 148 lack any groove or indentation into the clamping
surface 120.
[0032] The first relief area 142, the second relief area 144, the
third relief area 146, and the fourth relief area 148 are in some
aspects, positioned equal distance apart. In an illustrative
embodiment, the first, second, third and fourth relief area 142,
144, 146, 148 are positioned between 40-50 degrees offset, for
example 45 degrees offset, from the rolling direction of the
aluminum, which is 0/180 degrees. Thus, the relief area 142 is
shown centered at 45 degrees, the second relief area 144 is shown
centered at 135 degrees, the third relief area 146 is shown
centered at 225 degrees, and the fourth relief area is shown
centered at 315 degrees. However, a first relief area 142
positioned at 40-50 degrees, a second relief area 144 positioned at
130-140 degrees, a third relief area 146 positioned at 220-230
degrees, and a fourth relief area 148 positioned at 310-320 degrees
are contemplated by this disclosure. The first, second, third and
fourth relief areas 142, 144, 146, 148 may each be between 10 and
20 degrees wide. In an illustrative embodiment, the first, second,
third and fourth relief areas 142, 144, 146, 148 are approximately
15 degrees wide. Hence, the space between the segments 134, 136,
138, 140 of the first row of grooves 122 is less than the space
between the segments 134, 136, 138, 140 of the fifth row grooves
132. The relief areas ultimately reduce the height and pinching of
those ears in the drawn material by reducing or more evenly
distributing the clamping forces in the regions of the blank
corresponding to the relief areas 142, 144, 146, and 148, also
referred to as the force distributing segments, of the draw pad
102.
[0033] Referring now to FIG. 4, another embodiment of a draw pad
202 is presented. FIG. 4 illustrates a plan view of the draw pad
202 showing the clamping surface 220. The draw pad 202 is used with
a cupping press and is attached to a casing as described above with
respect to FIGS. 1A-3. The draw pad 202 also includes the same
features as described above with respect to FIGS. 1A-3, which
allows the draw pad 202 to be attached to the casing 104. The
difference between the draw pad 202 and the draw pad 102 lies in
the features of the clamping surface 220, and more specifically the
relief areas of the clamping surface, as described in greater
detail below.
[0034] The clamping surface 220 of the draw pad 202 includes at
least a first annular row of grooves 222. In some aspects, the draw
pad 202 further includes a second annular row of grooves 226, a
third annular row of grooves 228, a fourth annular row of grooves
230, a fifth annular row of grooves 232, any combination thereof,
or even more annular rows of grooves. Each annular row of grooves
is radially spaced apart from an adjacent annular row of grooves.
The first, the second, the third, the fourth and the fifth annular
row grooves 222, 226, 228, 230, 232 may be evenly spaced apart from
each other along a radial direction or have varying distances from
each other. In some aspects, the first, the second, the third, the
fourth and the fifth annular rows of grooves 222, 226, 228, 230,
232 are concentric to the draw aperture 214.
[0035] The annular grooves are created by removing material from
the clamping surface 220 such that a ridge 221 or force
concentrating region 221 is disposed between radially adjacent
grooves. In the area of the clamping surface 220 where the grooves
are formed, the ridges 221 contact the blank during drawing. Thus,
the clamping forces on the blank are concentrated by the ridges
221. It has been found that by creating relief areas by reducing
the radial width and optionally the depth of the grooves and
thereby increasing the surface area of ridges 223 in certain areas
of the clamping surface 220, the occurrence of earing is also
reduced.
[0036] In some aspects, the first, the second, the third, the
fourth and the fifth annular rows of grooves 222, 226, 228, 230,
232 extend into the draw pad 202 at a depth of between 0.001 to
0.009 inches. In some aspects, the depth is 0.003 inches. The width
of the first, the second, the third, the fourth and the fifth
annular rows of grooves 222, 226, 228, 230, 232 may be
approximately 0.09 inches. In some embodiments, the width of the
first, the second, the third, the fourth and the fifth annular rows
of grooves 222, 226, 228, 230, 232 may be greater than or less than
0.09 inches. For example the width may be 0.01 to 0.1 inches. In
yet some aspects, the first, the second, the third, the fourth and
the fifth annular row of grooves 222, 226, 228, 230, 232 have a
diameter of between 5 and 7 inches. In one embodiment, the first
annular row of grooves 222 has a diameter of approximately 5.2
inches, the second annular row of grooves 226 has a diameter of
approximately 5.5 inches, the third annular row of grooves 228 has
a diameter of approximately 5.9 inches, the fourth annular row of
grooves 230 has a diameter of approximately 6.3 inches and the
fifth annular row of grooves 232 has a diameter of approximately
6.7 inches.
[0037] Each annular row of grooves may be comprised of one
continuous groove that is divided into multiple segments with one
or more relief areas circumferentially positioned therebetween. In
an exemplary embodiment, the first, the second, the third, the
fourth, and the fifth annular rows of grooves 222, 226, 228, 230,
232, are divided into a first segment 234, a second segment 236, a
third segment 238, and a fourth segment 240.
[0038] Each of the segments 234, 236, 238, and 240 is a force
concentrating segment because the arcuate grooves in each segment
create the ridges 221, which concentrate the clamping force in the
area of the blank in contact with the force concentrating segments
234, 236, 238, and 240. The ridges 221 do not extend above the
surface of the clamping surface, so they may be more accurately
described as force concentrating regions 221 that are located
between adjacent radially spaced apart arcuate grooves. For
example, a force concentrating region 221 is disposed between the
first arcuate groove 222 and the radially spaced apart second
arcuate groove 226 in each force concentrating segment.
[0039] At least one relief area interrupts or otherwise divides the
segments. Relief areas are positioned between the segments or in
the row of grooves. In some aspects, there are several relief
areas. As illustrated, there is a first relief area 242 positioned
between the first segment of grooves 234 and the second segment of
grooves 236, a second relief area 244 positioned between the second
segment of grooves 236 and the third segment of grooves 238, a
third relief area 246 positioned between the third segment of
grooves 238 and the fourth segment of grooves 240, and a fourth
relief area 248 positioned between the fourth segment of grooves
240 and the first segment of grooves 234.
[0040] In an illustrative embodiment, the first, the second, the
third and the fourth relief areas 242, 244, 246, 248 are grooves
that interconnect two corresponding groove segments. The first
relief area 242 includes grooves positioned between and joining the
first segment of grooves 234 and the second segment of grooves 236.
The second relief area 244 includes grooves positioned between and
joining the second segment of grooves 236 and the third segment of
grooves 238. The third relief area 246 includes grooves positioned
between and joining the third segment of grooves 238 and the fourth
segment of grooves 240. The fourth relief area 248 includes grooves
positioned between and joining the fourth segment of grooves 240
and the first segment of grooves 234.
[0041] The grooves of the first, second, third and fourth relief
areas 242, 244, 246, 248 may have a depth of approximately 0.001
inches and a width of approximately 0.05 inches. It should be
appreciated that the depth may be greater than or less than 0.001
inches in the width may be greater than or less than 0.05 inches.
The depth and the width of the grooves comprising the first, the
second, the third and the fourth relief areas 242, 244, 246, 248
are smaller in size than the depth and the width of the first, the
second, the third, the fourth and the fifth row grooves 222, 226,
228, 230, 232.
[0042] The first, the second, the third, and the fourth relief
areas 242, 244, 246, 248 are in some aspects, positioned equal
distance apart. In an illustrative embodiment, a center of each of
the first, the second, the third and the fourth relief areas 242,
244, 246, 248 is positioned at 45 degrees, 135 degrees, 225
degrees, and 315 degrees, as illustrated. However, a first relief
area 242 positioned at 40-50 degrees, a second relief area 244
positioned at 130-140 degrees, a third relief area 246 positioned
at 220-230 degrees, and a fourth relief area 248 positioned at
310-320 degrees are contemplated by this disclosure. The first the
second, the third and the fourth relief areas 242, 244, 246, 248
may each be between 10 and 20 degrees wide. In some aspects they
may be 15 degrees wide.
[0043] According to the teaching of the present disclosure, the
relief areas 242, 244, 246, 248 reduce earing in a drawn cup
because they more evenly distribute the gripping force of clamping
the blank than the groove segments 234, 236, 238, and 240. The
relief areas include narrower (shorter radial width) and optionally
shallower grooves that are further spaced apart from radially
adjacent arcuate grooves than the arcuate grooves of the force
concentrating segments 234, 236, 238, and 240, which increases the
surface area of ridges 223 created by the grooves. The ridges 223
are the surfaces that contact the blank during clamping and
increasing the surface area of the ridges 223 reduces the
concentration of forces and more evenly distributes the clamping
forces at the locations of the blank associated with earing.
[0044] Referring now to FIG. 5, another embodiment of a draw pad
302 is presented. FIG. 5 illustrates a plan view of the draw pad
302 showing the clamping surface 320. The draw pad 302 is used with
a cupping press and is attached to a casing as described above with
respect to FIGS. 1A-3. The draw pad 302 also includes the same
features as described above with respect to FIGS. 1A-3, which
allows the draw pad 302 to be attached to the casing 104. The
difference between the draw pad 302 and the draw pad 102 lies in
the features of the clamping surface 320, and more specifically the
relief areas of the clamping surface 320, as described in greater
detail below.
[0045] Similar to the other disclosed embodiments, the draw pad 302
includes a plurality of radially spaced annular grooves and a
plurality of relief areas formed by removing material from the
clamping surface at locations associated with earing of a metal
sheet that has a 0/180 degree rolling direction. The draw pad 302
has a clamping surface 320 that is configured to be clamped or
otherwise be gripped against a blank to be formed into a cup-like
shape by a drawing process. The clamping surface 320 of the draw
pad 302 includes at least a first annular groove 322. In some
aspects, the draw pad 302 further includes a second annular groove
326 or more than two annular grooves, such as four or five annular
grooves.
[0046] The clamping surface 320 further includes at least one
relief area 324 that interrupts or otherwise bisects or divides the
first annular groove 322. The relief area 324 is an area of the
clamping surface 320 where material has been removed to form a
depression in the clamping surface 320. The floor surface of the
depression is a concave, tapered surface that is generally in a
shape corresponding to a formed ear that might be created by
conventional draw pads. The relief area tapers to increase in depth
as it extends to the inner surface 312. In this embodiment, the at
least one relief area 324 extends from the inner surface 312 and
into the first annular groove 324. The at least one relief area 324
is created by removing material to create a depression in the
clamping surface 320. In the embodiment shown, there are four
relief areas, each with a center positioned 45 degrees offset from
the rolling direction of the metal, for example a rolled aluminum.
However, relief areas 324 positioned at 40-50 degrees, 130-140
degrees, 220-230 degrees, and 310-320 degrees are contemplated by
this disclosure. Each of the relief areas 324 are spaced equal
distance apart at approximately 90 degrees.
[0047] Similar to the embodiments described above, a ridge 321 is
disposed between each radially spaced-apart groove, where the ridge
321 provides the contact surface that transmits the clamping force
to the blank of metal, for example aluminum. In the non-relief
areas, the ridges 321 concentrate the clamping force and localize
the clamping force to be proportional to the surface area of the
ridges 321. In contrast, the relief areas 324 relieve the clamping
force at that particular area associated with earing. In using the
draw pad 302 in a cupping press, as the blank is punched it is
gripped by the ridges 321. As the punch continues to form the
cup-like shape and the cup becomes deeper and the punch
displacement is near its maximum, the ridges 321 release their
respective grip as the blank tends to flow into the die cavity. At
this point of the drawing process, the portions of the clamping
surface 320 that would otherwise continue to grip the portions of
the blank that are most likely to ear, are replaced with the relief
areas 324, which reduces earing in the drawn cup.
[0048] According to the embodiment illustrated in FIG. 5, the
annular grooves are disposed proximal to a center of the draw pad
302 in that the annular grooves are disposed toward an inner
circumferential portion of the clamping surface 320 such that the
annular grooves are directly adjacent the inner surface 312.
[0049] FIG. 6 illustrates a clamping surface 420 of an embodiment
of a draw pad 402. The draw pad 402 includes the same features as
the draw pad 302 shown in FIG. 5, with the exception of the
position of the concentric annular grooves. According to an
embodiment, the draw pad 402 includes four concentric annular
grooves disposed radially distal a center of the draw pad 402 on
the clamping surface 420. According to this embodiment, the relief
areas 424 are positioned, formed, and shaped as described above
with respect to FIG. 5, but the relief areas 424 are radially
internal to the annular grooves such that the relief areas 424 do
not intersect the annular grooves.
[0050] Similar to the embodiments described above, a ridge 421 is
disposed between each radially spaced-apart groove, where the ridge
421 provides the contact surface that transmits the clamping force
to the blank of metal, for example aluminum. In the non-relief
areas, the ridges 421 concentrate the clamping force and localize
the clamping force to be proportional to the surface area of the
ridges 421. In contrast, the relief areas 424 relieve the clamping
force at that particular area associated with earing. In using the
draw pad 402 in a cupping press, as the blank is punched it is
gripped by the ridges 421. As the punch continues to form the
cup-like shape and the cup becomes deeper and the punch
displacement is near its maximum, the ridges 421 release their
respective grip as the blank tends to flow into the die cavity. At
this point of the drawing process, the portions of the clamping
surface 420 that would otherwise continue to grip the portions of
the blank that are most likely to ear, are replaced with the relief
areas 424, which reduces earing in the drawn cup.
[0051] The clamping surface 420 of the draw pad 402 includes at
least a first annular groove 422. In some aspects, the draw pad 402
further includes a second annular groove 426, a third annular
groove 428, a fourth annular groove 430, any combination thereof,
or even more annular grooves. The annular grooves 422, 426, 428,
430 extend into the draw pad 402 at a depth of between 0.001 to
0.009 inches. In some aspects, the depth is 0.003 inches. The width
of the first, the second, the third and the fourth annular grooves
422, 426, 428, 430 may be approximately 0.09 inches in some
embodiments, the width of the first, the second, the third, and the
fourth annular grooves 422, 426, 428, 430 may be greater than or
less than 0.09 inches. For example, the width may be 0.01 to 0.1
inches. In yet some aspects, the first, the second, the third, and
the fourth annular grooves 422, 426, 428, 430 have a diameter of
between five and seven inches. In one embodiment the first annular
groove 422 has a diameter of approximately 5.6 inches, the second
annular groove 426 has a diameter of approximately 5.9 inches, the
third annular groove 428 has a diameter of approximately 6.3 inches
and the fourth row grooves 430 has a diameter of approximately 6.7
inches.
[0052] Typically, the first, the second, the third, and the fourth
annular grooves 422, 426, 428, 430 are continuous grooves that are
unbroken by a relief area, as is generally the case in the previous
embodiments. Similar to the other disclosed embodiments, the draw
pad 402 includes a plurality of radially spaced annular grooves and
a plurality of relief areas formed by removing material from the
clamping surface at locations associated with earing of a metal
sheet that has a 0/180 degree rolling direction.
[0053] The relief area 424 is an area of the clamping surface 420
where material has been removed to form a generally concave,
tapered surface that is generally in a shape corresponding to a
formed ear as might be created by conventional draw pads. The
relief area 424 includes a floor surface that tapers to increase in
depth as it extends to the inner surface 412. In this embodiment,
the at least one relief area 424 extends from an inner surface 412
but does not intersect the first annular groove 422. The at least
one relief area 424 extends into the clamping surface 420 of the
draw pad 402. In the embodiment shown, there are four relief areas
whose center is positioned 45 degrees offset from the rolling
direction of the metal, for example a rolled aluminum. However,
relief areas 424 positioned at 40-50 degrees, 130-140 degrees,
220-230 degrees, and 310-320 degrees are contemplated by this
disclosure. Each of the relief areas 424 are spaced equal distance
apart at 90 degrees.
[0054] Reference is made to FIG. 7, which is illustrates a cupping
press or cupper 500 with portions shown in section view that
comprise the draw pad assembly, which includes the casing 104 and
one of the embodiments of the draw pad 102, 202, 302, 402, for
example the draw pad 102, as disclosed herein. In operation, sheet
metal, for example rolled aluminum, is fed through the cupper 500
to form into a cup-like shape through the drawing process. Upon
dwelling the metal sheet in the cupper 500 is clamped between the
draw pad 102 and a blank and draw die 502 to hold the metal sheet
in place for subsequent forming operations. Specifically, the
clamping surface 120 (or 220, 320, 420) as described in the
multiple alternate embodiments of the present disclosure contacts
the sheet metal to transmit a clamping force to sheet metal. Next,
a blank cutter 504 is displaced to shear and cut away material to
form a generally circular blank 506 from the sheet metal. According
to alternate embodiments, the blank may be shaped other than
circular.
[0055] After forming the blank 506, the blank continues to be
clamped between the draw pad 102 and the blank and draw die 502 and
the clamping surface 120 continues to transmit the clamping force.
That is, the ridges 121 (or 221, 321, or 421) adjacent the annular
grooves formed in the clamping surface 120 contact the blank 506.
With the blank 506 clamped, the punch 508 is displaced and forces
the blank 506 into the cavity 510 where the blank 506 is shaped
between the punch 508 and the blank and draw die 502. As the punch
508 nears the full displacement, the relief areas 124 or 224, as
taught herein, more evenly distribute the clamping force over the
portions of the blank 506 that are most susceptible to earing,
which is generally 45 degrees offset from the rolling direction.
According to the alternate embodiment shown and described with
respect to FIGS. 5 and 6, the relief areas 324 and 424 release the
clamping force at the portion of the blank 506 that is most
susceptible to earing.
[0056] The material used to form the blank is generally an
anisotropic material, which has directional variations in the sheet
metal's mechanical properties. In some materials, ears are formed
approximately 45 degrees from the rolling direction of the sheet.
These ears are the last material to remain clamped in the drawing
process. At that time, all the clamping forces concentrate on those
ears and can cause them to become pinched or thinned. The draw pads
are clamped or gripped against the blank such that the relief areas
are positioned at approximately 45 degrees offset from the rolling
direction, such as a 0/180 degree rolling direction. These areas
correspond to the location of the ears. The relief areas reduce the
height and pinching of the ears in the drawn material by reducing
or more evenly distributing the clamping forces in those
regions.
[0057] In the foregoing description of certain embodiments,
specific terminology has been resorted to for the sake of clarity.
However, the disclosure is not intended to be limited to the
specific terms so selected, and it is to be understood that each
specific term includes other technical equivalents which operate in
a similar manner to accomplish a similar technical purpose.
[0058] In this specification, the word "comprising" is to be
understood in its "open" sense, that is, in the sense of
"including", and thus not limited to its "closed" sense, that is
the sense of "consisting only of". A corresponding meaning is to be
attributed to the corresponding words "comprise", "comprised" and
"comprises" where they appear.
[0059] In addition, the foregoing describes only some embodiments
of the invention(s), and alterations, modifications, additions
and/or changes can be made thereto without departing from the scope
and spirit of the disclosed embodiments, the embodiments being
illustrative and not restrictive.
[0060] Furthermore, invention(s) have been described in connection
with what are presently considered to be the most practical and
preferred embodiments, it is to be understood that the invention is
not to be limited to the disclosed embodiments, but on the
contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the
invention(s). Also, the various embodiments described above may be
implemented in conjunction with other embodiments, e.g., aspects of
one embodiment may be combined with aspects of another embodiment
to realize yet other embodiments. Further, each independent feature
or component of any given assembly may constitute an additional
embodiment.
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