U.S. patent application number 12/988933 was filed with the patent office on 2011-02-17 for cutting method and apparatus.
This patent application is currently assigned to Crown Packaging Technology, Inc.. Invention is credited to Paul Robert Dunwoody.
Application Number | 20110036134 12/988933 |
Document ID | / |
Family ID | 39493977 |
Filed Date | 2011-02-17 |
United States Patent
Application |
20110036134 |
Kind Code |
A1 |
Dunwoody; Paul Robert |
February 17, 2011 |
CUTTING METHOD AND APPARATUS
Abstract
A method and apparatus for manufacturing a two-part article from
a cup (1) formed from a single sheet metal blank. The method
includes forming a "V"-shaped groove (15) by pressing and rolling
an anvil (25) on one side of the cup sidewall (3), against one or
more cutting rings (21) on the opposite side of the sidewall.
Generally, this stage is followed by a second stage, which cuts the
cup (1) into a separate ring (11) and shallower cup (10). This
second stage enables profiled edges (17, 18) such as slight bends
or flares to be formed which are beneficial when flanging or
curling of the edges is subsequently required.
Inventors: |
Dunwoody; Paul Robert;
(Oxfordshire, GB) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
CIRA CENTRE, 12TH FLOOR, 2929 ARCH STREET
PHILADELPHIA
PA
19104-2891
US
|
Assignee: |
Crown Packaging Technology,
Inc.
Alsip
IL
|
Family ID: |
39493977 |
Appl. No.: |
12/988933 |
Filed: |
April 6, 2009 |
PCT Filed: |
April 6, 2009 |
PCT NO: |
PCT/EP09/54076 |
371 Date: |
October 21, 2010 |
Current U.S.
Class: |
72/71 |
Current CPC
Class: |
B23D 31/001 20130101;
B23D 21/14 20130101; B23D 31/002 20130101 |
Class at
Publication: |
72/71 |
International
Class: |
B21D 51/38 20060101
B21D051/38 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 21, 2008 |
GB |
0807237.3 |
Claims
1. A method of manufacture of a two-part article from a cup having
a sidewall and integral base, formed from a single sheet metal
blank, the method comprising: placing the cup over a circular
cutting ring having a sharp peripheral edge; and pressing and
rolling an anvil having a curved surface against the outside of the
cup, to cause the edge of the cutting ring to penetrate into the
sidewall of the cup to form a "V" shaped groove.
2. A method according to claim 1, in which the pressing and rolling
step forms a flare.
3. A method according to claim 1, wherein the pressing and rolling
step includes limiting axial movement of the cup.
4. A method according to claim 1, in which the depth of the groove
is at least two-thirds of the sidewall thickness and the
penetration angle is between about 45 degrees and 90 degrees,
whereby the material at the base of the groove splits.
5. A method according to claim 1, in which the depth of the groove
is from about half to three quarters of the sidewall thickness,
whereby the material at the base of the groove forms a "score
residual".
6. A method according to claim 5, further comprising, as a second
stage, placing the cup over a profiled ring having a grooved
profile; aligning the profile opposite the "V" shaped groove;
pressing and rolling a parting tool against the outside of the cup
opposite the groove, whereby penetration of the parting tool into
the wall of the cup causes the material at the bottom of the groove
to split, and the material either side of the split flare
inwards.
7. A method according to claim 5, further comprising, as a second
stage, progressively rolling and "pinching" the cup between two
rails or between a rail and a circular disc, each having an edge,
thereby causing the material at the bottom of the groove to split,
and the material either side of the split flare inwards.
8. A method according to claim 1, in which the groove forming step
is on the outside wall and the material breaking step comprises
penetrating from the outside.
9. An apparatus for claims 1 to 9, in which manufacturing a
two-part article from a cup having a sidewall and integral base,
formed from a single sheet metal blank, the apparatus comprising:
one or more cutting rings each having a sharp peripheral edge and
arranged for rotation about a central axis; and an anvil having a
curved surface capable of being applied against the outside of the
cup to cause the edge of the cutting ring to penetrate into the
sidewall of the cup to form a "V" shaped groove, and the anvil is
concentric to the concentric axis.
10. An apparatus according to claim 9, in which the axis of a
central cutting ring is stationary and the anvil rotates, the anvil
having a portion of constant radius for contacting the cup.
11. An apparatus according to claim 9, further comprising guiding
surfaces for controlled axial sliding of the cup.
12. An apparatus according to claim 9, in which each side of the
groove in the profiled ring is asymmetrical whereby a different
flare is formed in the cut ring from that of the cut end-part.
13. A method according to claim 2, wherein the flare formed by the
pressing and rolling step is an outward flare.
14. A method according to claim 2, wherein the flare formed by the
pressing and rolling step is an inward flare.
15. A method according to claim 4, in which penetration angle is
between about 50 degrees and 75 degrees.
Description
TECHNICAL FIELD
[0001] The present invention concerns the cutting of the sidewall
of a cup-shaped sheet metal can body, closure or similar article.
In particular it relates to the cutting of a drawn cup-shaped
closure body having an inwardly protruding feature or features at
its rim, into a separate ring and shallower cup-shaped article.
BACKGROUND ART
[0002] Several methods are known by which can bodies are cut
(trimmed) to a desired height to produce a separate ring. These
methods are used in rotating machinery commonly supplied for
example by Belvac Production Machinery and by CarnaudMetalbox
Engineering, and are well suited to trimming where the ring is
usually discarded, and where the height of the cut ring is usually
significantly less than the height of the trimmed can body.
[0003] WO 08053013 A (CROWN PACKAGING TECHNOLOGY, INC.) and
un-published patent application EP-08153134.5 describe methods of
manufacturing a two-part closure and the resulting two-part
closures respectively. To produce such closures requires the
cutting of a drawn cup-shaped article close to its end panel, such
that the height of the cut ring part is greater than the height of
the cut end-part. To manufacture the closures described in these
patents, it would be useful for the cup shaped article to have an
inwardly protruding curl already formed at the rim before cutting.
It would be even better to be able to cut a cup shaped article that
also had inwardly protruding lugs.
[0004] Known cutting methods are difficult to use to cut such
closures due to the proximity of the closed end of the cup to the
cutting tools.
[0005] Most conventional cutting processes use a pair of knives to
cut the metal in a rotary scissor-action and may leave undesirable
burrs on opposing sides of the cut edge. If similar cutting
processes are used on coated metal, then hairs of coating material
may be created during cutting and/or subsequent forming of the cut
edges.
[0006] Residual stresses in drawn sheet metal parts can result in
distortion of the cut parts during cutting. This can cause the
cut-edges of the ring and end-parts to deviate from a circular path
as cutting progresses around the periphery such that undesirable
sharp slivers can be produced.
[0007] The cut edges produced by known rotary cutting methods
produce little or no bending inwards or outwards ("flare") of the
cut-edge, thus neither increasing nor decreasing the diameter of
the wall significantly at the cut-edge. However, if it is desired
subsequently to flange or curl either or both the cut-edges
inwardly or outwardly, as in the case of producing the closures
described in WO 08053013 A (CROWN PACKAGING TECHNOLOGY, INC.) and
EP-08153134, it would be advantageous for the cut-edge already to
have a flare in the same direction after cutting.
[0008] Most known cutting apparatus cannot be used to cut a can
body having any inwardly protruding rim.
[0009] Other known methods of cutting also have disadvantages.
Laser cutting produces vaporised debris, which may contaminate the
finished article. Clip trimming as described in WO 08053013 A
(CROWN PACKAGING TECHNOLOGY, INC.) can only be carried out on an
article that has no inwardly projecting features on the
sidewall.
[0010] The processes of "scoring" and "parting" are known for
producing two open-ended cylinders from one open-ended cylinder.
This involves firstly producing a linear indentation or "score" on
a flat, typically rectangular sheet metal blank. The blank is then
rolled into an open-ended cylinder so that the score becomes
circumferential part way up the outside of the cylinder, and then
the adjacent edges of the blank are joined by welding. The cylinder
is then parted by rolling a circular tool around the inside of the
cylinder adjacent to the score whilst the outside of the cylinder
is supported by a pair of curved rails positioned at either side of
the score. However, this method can only be used on a flat sheet
metal blank, to produce cylinders which are open at both ends.
DISCLOSURE OF INVENTION
[0011] According to the present invention, there is provided a
method of manufacture of a two-part article from a cup formed from
a single sheet metal blank, comprising: inserting a circular
cutting ring having a sharp peripheral edge inside the cup; and
pressing and rolling an anvil having a curved surface against the
outside of the cup, to cause the sharp edge of the cutting ring to
penetrate into the wall of the cup to form a "V" shaped groove.
[0012] This cost-effective manufacture of, for example, certain
two-part closures or can body and end component combinations from
one drawn sheet metal blank thus uses a rotary method (and
complementary apparatus) to cut a substantially cylindrical portion
of the sidewall of the cup-shaped article (`cup`) to an even
height. The cutting process of the invention is suitable to cut a
cup-shaped article that has an inwardly protruding feature or
features already formed on its rim before cutting.
[0013] Advantageously, the cutting process may produce a slight
inward (or outward) bend or "flare" to assist subsequent forming of
features such as curls to hide or protect the cut-edge. The method
of the invention also ensures that the end of the cut coincides
with the start of the cut to avoid the formation of slivers.
Ideally, the cutting process positions any burrs or weakened
coatings that are formed during the cutting process so as to avoid
being dislodged by subsequent forming operations.
[0014] The diameter of the cutting ring is smaller than the inside
diameter of any curl or the distance between any inwardly
protruding lugs or other features below the position of the cut, to
allow the cup to be placed over the cutting ring and to allow the
cut ring to be removed.
[0015] In a rotating-type machine, one or more circular cutting or
profiled rings may be arranged such that their individual axes
rotate around a central axis, with the surface of the anvil or
parting tool concentric to that central axis.
[0016] In a manually fed or an indexing-type machine, the axis of
the circular cutting or profiled ring may be stationary, and the
anvil or parting tool may rotate. In this case the anvil or parting
tool would have a portion of constant radius, which would contact
the cup and a portion of reduced radius to allow space for the cup
to be placed over and removed from the cutting disc.
[0017] In either type of machine, the entire cup may be held
axially to slide between two close-fitting flat (guiding) surfaces,
or the closed end of the cup may be held to slide between an
external guiding surface and a guiding surface on top of the
cutting ring. Alternatively or additionally, either or both sides
of the closed end of the cup may be urged to slide against a flat
surface by the application of compressed air, vacuum or magnets.
One of the guiding surfaces may be held against the cup by a spring
mechanism.
[0018] The angles of the "V" shaped cutting ring may be equal, or
may be unequal so as to urge the cup to slide against one of the
guiding surfaces in preference to the other. Unequal angles of the
cutting ring may also be used to preferentially compress and/or
work-harden material on one side of the "V" shaped groove, or to
produce a groove or cut shape to suit subsequent manufacturing
processes.
[0019] In one embodiment, the invention provides a single stage
process, in which the depth of the groove created by the cutting
ring (typically greater than two-thirds of the wall thickness) and
the forces created by the penetration angle (the total angle
between each side of the cutting ring which is typically between 45
degrees and 90 degrees, and preferably between 50 degrees and 75
degrees) are sufficient to cause the material at the bottom of the
groove to split. Splitting will occur because the shape of the
cutting ring acts as a wedge.
[0020] A complete circumferential cut is created when the anvil has
rolled around the entire periphery of the cup. The single stage
process will produce little or no flare.
[0021] The sharp edge of the cutting ring may be prevented from
accidentally contacting the anvil during cutting and the depth of
the groove may be closely controlled by providing a second ring
portion of a slightly smaller diameter than the sharp edge adjacent
to it.
[0022] The cut may be kept in one plane and slivers may thus be
avoided by limiting the axial movement of the cup. Provided that
the axial movement of the cup is limited to less than half the
width of the "V" shaped groove, then the end of the cut should meet
the start of the cut and slivers should be avoided.
[0023] Distortion of the cup and the risk of forming slivers may be
further avoided if the anvil surface rotates the cup more than
once, such that the groove is progressively formed before splitting
occurs.
[0024] A flare may be produced at the cut edges if a groove is
provided around the anvil to bend the wall during cutting.
[0025] In other preferred embodiments of the invention, the method
is a two-stage process to cut a ring from a cup-shaped article. In
the two stage process, the first stage is the same as the one-stage
process, except that the depth of the groove (typically between
half and three quarters of the wall thickness) and the forces
created by the penetration angle (typically between 45 degrees and
90 degrees, and preferably between 50 degrees and 75 degrees) are
not sufficient to cause the material at the bottom of the groove to
split. The penetration angle may be reduced from these angles, if
it is desired to use a cutting ring with unequal angles. In this
process, the reduced thickness of the sidewall at the bottom of the
groove is described as the "score-residual".
[0026] The second stage of the two-stage process may comprise
inserting a profiled ring having a grooved profile is inserted
inside the cup with the centre of the grooved profile opposite the
"V" shaped groove in the cup, and pressing and rolling a parting
tool having a sharp edge or small edge radius against the outside
of the cup opposite the "V" shaped groove in the cup. The
penetration of the parting tool into the wall of the cup causes the
material at the bottom of the groove to split, and the material
either side of the split or "cut-edge" to bend or "flare"
inwards.
[0027] The diameter of the profiled ring is smaller than the inside
diameter of any curl or the distance between any inwardly
protruding lugs or other features below the position of the cut, to
allow the cup to be placed over the profiled ring and to allow the
cut ring to be removed.
[0028] The length of wall that is bent inwards and the distance it
is bent may be optimised to suit subsequent processes by varying
any combination of the grooved profile of the profiled ring, the
edge radius of the parting tool, the penetration depth of the
cutting ring in the first stage to alter the "score-residual", or
the penetration of the parting tool into the profiled ring in the
second stage.
[0029] A complete circumferential cut is created when the parting
tool has rolled around the entire periphery of the cup. The amount
of "flare" may be kept even around the periphery of each cut part
by limiting the axial movement of the cup.
[0030] The amount of flare may be further kept even if the parting
tool rotates the cup more than once, such that the flare is
progressively formed before splitting occurs.
[0031] Each side of the groove in the profiled ring may be
symmetrical, or may be asymmetrical so as to urge the cup to slide
against one of the guiding surfaces in preference to the other or
to create a different flare on the cut ring to the flare on the cut
end-part. Similarly the groove in the profiled ring may be
positioned centrally or offset in relation to the "V" shaped groove
in the cup. The profile of the parting tool may also be symmetrical
or asymmetrical.
[0032] In an alternative second stage process, the cup may be
progressively rolled and "pinched" between two rails or between a
rail and a circular disc each having a penetrating sharp edge or
small radius edge. The penetration of the edges into the wall of
the cup causes the material at the bottom of the groove to split,
and the material either side of the split or "cut-edge" to bend or
"flare" inwards.
[0033] In another embodiment, a ring is inserted inside the cup to
one side of the "V" shaped groove, and a parting tool is pressed or
rolled against the outside of the cup to the other side of the "V"
shaped groove. The penetration of the parting tool into the wall of
the cup causes the material at the bottom of the groove to split,
and the material to one or both sides of the split or "cut-edge" to
bend or "flare" inwards.
[0034] The diameter of the ring is smaller than the inside diameter
of any curl or the distance between any inwardly protruding lugs or
other features below the position of the cut, to allow the cup to
be placed over the ring and to allow the cut ring to be
removed.
[0035] The length of wall that is bent inwards and the distance it
is bent may be optimised to suit subsequent processes by varying
any combination of the profile of the ring, the profile of the
parting tool, the penetration depth of the cutting ring in the
first stage to alter the "score-residual", the penetration of the
parting tool into the ring in the second stage or the axial
distances of the ring and the parting tool from the "V" shaped
groove.
[0036] A complete circumferential cut is created when the parting
tool has rolled around the entire periphery of the cup. The amount
of "flare" may be kept even around the periphery of each cut part
by limiting the axial movement of the cup.
[0037] The amount of flare may be further kept even if the parting
tool rotates the cup more than once, such that the flare is
progressively formed before splitting occurs.
[0038] In yet another embodiment, the second stage is a repetition
of the first stage, but with a cutting ring or anvil of a different
profile to complete the cut.
[0039] In any of the two-stage embodiments, it is not necessary to
carry out the second stage immediately after the first stage, and
other manufacturing steps may be carried out between each stage if
desired.
[0040] Other features such as curls, beads or embossing may be
rolled or formed on, or materials such as lubricants or
corrosion-resistant materials may be applied to the cup at the same
time as the first stage or second stage is being carried out.
[0041] Lubricants or other materials may be delivered or applied to
parts of the apparatus and transferred to the cup during operation
of the apparatus. Lubricants or other materials may be applied to
the "V" shaped groove between the first and second stage.
[0042] The invention has been described as currently preferred to
manufacture a two-part metal closure, having a groove formed on the
inside of the cup wall and the cup wall being penetrated by a
parting tool or rails from the outside. However, it is also
possible to form the groove on the outside of the wall and to break
the material at the bottom of the groove by penetration from either
the inside or the outside in order to suit subsequent forming
processes for other products.
[0043] Other products that may be manufactured using the methods
described include but are not limited to drawn can and end
combinations, drawn can and ring combinations and drawn end and
ring combinations. Can bodies may also be trimmed using the methods
described.
[0044] The apparatus described for any of the embodiments may
include means of driving the working surfaces of the cutting ring
and anvil, or of the ring and parting tool, at specific relative
speeds.
[0045] Alternatively or additionally, the apparatus may include
means of sucking and/or blowing any debris from the cut edges. This
is particularly useful in the case of cups made from coated
material, where hair-like pieces of coating may detach during
cutting or forming of the "V"-shaped groove.
[0046] The quality of products manufactured using the cutting
methods described is improved because the subsequent forming
operations can be carried out with fewer defects, and the ability
to use thinner and more cost-effective materials without causing
defects is increased.
BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS
[0047] Preferred embodiments of the invention will now be described
by way of example only, with reference to the drawings, in
which:
[0048] FIGS. 1a, 1b, 1c and 1d are side, top, sectional and
perspective views of a cup;
[0049] FIGS. 2a, 2b, 2c and 2d are a sectional view of a cut
end-piece, a sectional view of a cut ring and enlarged detailed
partial sectional views of their respective cut edges;
[0050] FIGS. 3a and 3b are a sectional view and an enlarged
detailed partial sectional view of a scored cup;
[0051] FIGS. 4a, 4b, 4c, and 4d are a sectional view of a parted
end-piece, a sectional view of a parted ring and enlarged detailed
partial sectional views of their respective parted edges;
[0052] FIGS. 5a and 5b are perspective and side views of a manually
operated apparatus used to score a cup;
[0053] FIGS. 6a, 6b, 6c and 6d are a sectional view of a manually
operated apparatus being used to score a cup, enlarged detailed
partial sectional views of the scoring tools and a sectional view
of a manually operated apparatus being used to score a cup,
sectioned in the plane of the score;
[0054] FIGS. 7a, 7b and 7c are a sectional view of a manually
operated apparatus being used to part a cup and enlarged detailed
partial sectional views of the parting tools;
[0055] FIG. 8 is a schematic view of an alternative arrangement to
score cups;
[0056] FIGS. 9a, 9b, 9c, and 9d are perspective, top, sectional and
enlarged detailed sectional views of an alternative arrangement to
part cups;
[0057] FIGS. 10a, 10b, and 10c are a sectional view of a manually
operated apparatus being used to score a cup, and enlarged detailed
partial sectional views of the scoring tools; and
[0058] FIGS. 11a, 11b and 11c are a sectional view of a manually
operated apparatus being used to part a cup and enlarged detailed
partial sectional views of the parting tools.
MODE(S) FOR CARRYING OUT THE INVENTION
[0059] FIGS. 1a to 1d show a cup 1 comprising an end 2 and integral
sidewall 3. The end 2 is profiled into beads 4 and centre panel 5
during the cupping process (see FIG. 1b and section through A-A in
FIG. 1c). The sidewall 3 terminates with an inward curl 6 which is
best seen in FIG. 1c.
[0060] FIG. 2 shows the cut end piece 10 (FIG. 2a) and cut ring 11
(FIG. 2b) from a single stage process. Their respective cut edges
12 and 13 are shown in FIGS. 2c and 2d.
[0061] The two stage option of FIGS. 3 and 4 first forms a score 15
in sidewall 3 towards the end 2 with a `V`-shaped cut between half
and three quarters of the wall thickness having a total internal
angle 16 of about 60.degree. (degrees). When the end piece 2 of
FIG. 4a is parted from sidewall (ring) 3, the parted edges 17 and
18 are flared inwardly
[0062] A manual cutting or scoring apparatus 20 is shown in
perspective and side views respectively in FIGS. 5a and 5b. The
apparatus comprises a cutting ring 21 positioned below a cut-out of
top plate 22. Beneath the top plate 22, an anvil 25 can be seen in
the side view of FIG. 5b.
[0063] The shape of the anvil 25 can be better seen in FIG. 6d. The
anvil 25 has a portion of constant radius and also a portion of
reduced radius coincident with the cut-out of top plate 22. The
length of the constant radius portion of the anvil 25 is greater
than the circumference of the cup 30. Handle 26 is connected by
bolts to the rotating anvil 25 and top plate 22.
[0064] In the sectional view of the scoring apparatus in FIGS. 6a,
6b and 6c, a cup 30 has been placed over a lower guide surface 23
and an upper guide surface of top plate 22 traps the cup 30 in
position over cutting ring 21. As the handle is rotated, the anvil
25 turns until it pushes cup 30 against the edge 24 of cutting ring
21. The cutting ring edge has an angle of 60.degree.-70.degree.
(degrees), which forms a corresponding groove in the cup 30. The
rotation of the constant radius portion of the anvil 25 rotates the
cup 30 and cutting ring 21 about their respective axes, such that
the cup 30 revolves at least one full turn.
[0065] Whilst the top plate 22 is connected to and rotates with the
anvil 22 for convenience of loading the cup through the cut-out, an
upper guide surface 22 may be provided by any flat surfaced part
attached to the apparatus adjacent to the cup in the position shown
in FIG. 6b.
[0066] The depth of the groove may be controlled by adjusting the
distance between the shafts 27 and 27', to which the cutting ring
and anvil are mounted. In the apparatus of FIG. 6a, these shafts
run in bearings 28 which are mounted in housings 29 either or both
of which may have inside diameters that are eccentric to their
outside diameters. Rotating such an eccentric housing will alter
the distance between the shafts.
[0067] The depth of the groove may be further controlled by the
radius of the depth-setting ring 27 in relation to the radius of
the cutting ring 21. If the depth of the groove is sufficient, the
bottom of the groove will be split by the cutting ring edge 24, and
the cutting will be complete in a single stage. If the depth of the
groove is shallow and there is a sufficient residual thickness of
metal, then cutting is completed using the parting apparatus 40 of
FIG. 7.
[0068] In another version of this embodiment the anvil may have two
portions of constant radius, each having sufficient chordal length
to drive the cup through at least one revolution. The first portion
to contact the cup would have a slightly smaller radius than the
second, such that a shallow groove would be formed by the first
portion and would be deepened by the second portion. In this
version, the distortion of the cup during forming of the shallow
groove would be reduced, and this groove would then provide
guidance for the cup to the cutting ring during deepening by the
second portion. Such an apparatus might also be used to complete
the cutting of the cup if the second portion of the anvil deepened
the cut so as to cause it to split.
[0069] This scoring stage produces a groove which is then parted by
the apparatus of FIG. 7. The cutting edge 24 of FIG. 6c produces a
circumferential groove on the inner sidewall 32 of cup 30. In the
parting apparatus 40, parting tool 42 pushes and enters the outside
sidewall 34 of cup 30 adjacent the groove 15 to split the bottom of
the groove and produce a slight inward bend or flare 36.
[0070] The penetration distance of the parting tool 42 into the cup
wall may be controlled by adjusting the distance between the shafts
68, 68', to which the supporting annuli 44 and parting tool 42 are
mounted. In the apparatus of FIG. 7a, these shafts run in bearings
68 which are mounted in housings 69 either or both of which may
have inside diameters that are eccentric to their outside
diameters. Rotating such an eccentric housing will alter the
distance between the shafts.
[0071] Supporting annuli 44 enable metal to be formed around radii
at each apex 45 as parting tool 42 moves radially inwardly. This
assists any subsequent forming operations which are to be carried
out on the cut cup or ring, such as curls, seams or flanges. By
using this apparatus, the cut is formed completely circumferential,
with the end of the cut accurately positioned so as to coincide
with the start of the cut. This ensures that the formation of
slivers of metal is avoided.
[0072] In another version of this embodiment, the parting tool 42
may have two portions of constant radius, each having sufficient
chordal length to drive the cup through at least one revolution.
The first portion to contact the cup would have a slightly smaller
radius than the second, such that a shallow indentation would be
formed by the first portion and would be deepened by the second
portion to cause the bottom of the groove to split. In this
version, the flare would be formed more evenly around the periphery
of the cut edges, especially where the split starts and
finishes.
[0073] An alternative scoring arrangement for rotary movement of
the cup 1 could carry a series of cups supported by scoring or
cutting mandrel 46 rolling the cups along a curved rail 47, which
acts as the anvil. This arrangement is shown in FIG. 8. A similar
arrangement may be used for parting.
[0074] The alternative parting apparatus 50 of FIG. 9 comprises a
bottom plate 51 and guide rail 52, a fixed outer parting rail 53
having an edge 54 and a rotating parting wheel 55 having an edge
56. The cup 30 is introduced between the rail 53 and wheel 55. The
cup is held in one plane by the close fit of bottom plate 51 and
guide rail 52. The diameter of the cup 30 is slightly less than the
difference between the radii of the edges 54 and 56, and thus the
cup is both driven around the apparatus as indicated by the arrow,
and the sidewall is progressively indented to form a flare 36 and
is split to form a cut end piece 10 and cut ring 11.
[0075] An additional supporting ring or rings may be attached to
either or both sides of the parting wheel, and additional
supporting rails may be attached to either or both sides of the
outer parting rail, to contact and help drive the cup around the
apparatus during parting
[0076] The scoring apparatus of FIGS. 10a, 10b and 10c shows
additional and alternative features to the scoring apparatus of
FIGS. 6a, 6b and 6c. In FIG. 10, the rim (70) of the cup (30) is
held against a planar surface (71), by applying suction to the
inside of the cup through the channel (72). Rotation of the handle
(26) drives both shafts (27 and 27') via wheels (73 and 73'). This
arrangement avoids skidding of the cup, and ensures complete
formation of the "V" shaped groove around the cup.
[0077] Application of a lubricant to the cutting rings of either
FIG. 6 or FIG. 10, before the cup is placed in the apparatus may
improve the life of the cutting ring and assist subsequent
performance in manufacturing and use.
[0078] The parting apparatus of FIGS. 11a, 11b and 11c shows
additional and alternative features to the scoring apparatus of
FIGS. 7a, 7b and 7c. In FIG. 11, the scored cup (30) is able to
rotate and slide between planar surfaces (81 and 82). Suction is
applied via interconnecting channels (85, 86), which pulls the rim
of the cup (30) against planar surface (81).
[0079] Rotation of the handle (26) brings the parting tool (83)
into contact with the outer sidewall of the cup, just above the "V"
shaped groove, and pushes the inner sidewall of the cup against the
ring (84) just below the "V" shaped groove. The shearing action of
the parting tool and ring splits the cup (30) into a cut end piece
(10) and a cut ring (11). Rotation of the handle (26) rotates the
parting tool (83) and rotates the ring (84), cup (30), and surface
(81) via the shafts (27 and 27') and wheels (73 and 73'). This
arrangement avoids skidding of the cup, and ensures complete
cutting around the cup. Air that is sucked through the gap that is
formed between the cut end piece (10) and the cut ring (11) carries
away any debris released during cutting through the interconnecting
channels (85, 86). Whilst FIG. 11 shows a ring inside a cup below a
parting tool outside a cup, it is equally possible to position a
ring inside a cup above a parting tool outside a cup.
[0080] The apparatus of FIG. 6 or FIG. 10 could be used twice in
any combination--firstly to form a groove using one cutting ring,
and secondly to complete the cut by splitting along the groove
using another cutting ring.
[0081] Further methods of achieving even cutting without risk of
tearing material are possible within the scope of the invention,
including for example combinations of any of the methods and
apparatus described.
* * * * *