Note: Descriptions are shown in the official language in which they were submitted.
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This is a division of Patent Application
Serial No. 377,954, filed May 20, 1981.
The present invention relates generally to
containers such as cups and the like manufactured of
plastic material. In par1:icular, the present invention
relates to the manufacture of one-piece foam sheet
material cups. For some 1:ime cups have been manufactured
of expanded polystyrene beads by the well-known steam
chest process. This method of cup manufacture has the
inherent disadvantage in that each container, if so
desired, must be individu<~lly decorated by an elaborate
and time consuming process. It was then discovered that
oriented foam sheet mater:ial could be produced and
decorated on one side similar to and by techniques used
in the paper decorating industry. The decorated foam
sheet material was then C11t into rectangular shaped
blanks which were then roLled into cylinders containing
a single side seam. The cylinders were then placed on
a mandrel with a portion of the cylinder protruding
beyond the mandrel. The mandrel and the plastic foam
sheet stock cylinder which it contained were then sub-
jected to heat which in turn caused the foam sheet
cylinder to shrink to the external configuration of the
mandrel. A separate bottom closure has been used with
the foam sheet cylinder to produce a two-piece container.
Also, a one-piece cup has been produced by merely pres-
sing the extra material, that protrudes beyond the
mandrel into a bottom structure. After the containers,
such as cups for beverages, were produced by the above
described method, the cup, were then subjected to a
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separate rimming process which produced the familiar bead on
the rim of the cup.
The present invention provides a method of form-
ing a container rim,`includlng the steps of mounting a sleeve
of thermoplastic sheet material on a mandrel, holding the sleeve
in position on the mandrel by exerting a first radial force
outwardly against the interior of an end portion of the sleeve,
heating the end portion of the container where it is being
held by the first radial force, expanding the end portion in
a radial direction by the application of a second radial force
outwardly against the interior of the end portion, transla-
ting the sleeve along its longitudinal axis while holding the
expanded end portion fixed against an abutment ring, and causing
the end portion to upset, thus forming a rim on the container.
Preferably, the method includes the step of continu-
ing the heating of the end portion during the upsetting of
the end portion.
The invention will be more readily understood from
the following description of a preferred embodiment shown in
the drawings, in which:
Fig. 1 is a sectional view of an apparatus embody-
ing the present invention.
Fig. 2 is a sectional view taken along the line 2-
2 of Fig. 1.
Fig. 3 is an enlarged sectional view of that por-
tion represented by numeral 96 of Fig. 1.
Fig. 4 is a view similar to Fig. 3 which shows the
segments in an outward position.
Fig. 5 is a view similar to Fig. 4 that shows the
downward movement of the mandrel sleeve.
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Fi~. 6 is a view similar to Fig. 5 wherein the
contalner bead is completely formed.
THE PREFERRED EMBODIMENT
The apparatus for the manufacture o~ a container
rrom a foam sleeve is show.n generally at l0 in Fig. l. A
base 12 is provided for the support o~ the mandrel 14 and
its associated mechanism. The base mechanism can be, for
example, a drum assembly o:r conveyor system that permits
mobility cf the mandrel assembly. Since the container will
be partialiy formed by the shrlnkage of the foam material,
lt is desirable that the m;~ndrel pass through a heated zone
such as an oven. A support column 16 is cantilevered normal
to base plate 12 and as shown for convenience in an upright
position in Fig. 1. Support column-16 contains a M anged
head 18 at its free end and a reduced diameter 20 at its
threaded end 22. A hollow cylindrically shaped support post
24 contalns a centrally pos1tioned bore 26 through which the
reduced diameter 20 of support column l~ is inserted. As
nut 28 ls tlghtened, support post 24 is clamped firmly
against the top surface 30 o~ base 12. m us, base 12, support
column 16 and hollow support post 24 are in fixed relation-
ship wlth one another and do not move as does the remainder
of mandrel 14 and lts associated parts which are described
below.
Mandrel 14 is adapted for movement along support
column 16 as described in detail. Mandrel 14 comprises a
cylindrical section 32 which is supported at both ends. The
top end 34 coacts with end plate 36 and bottom plate 38.
The top end plate 36 contalns an end closure that is recessed
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as at 40. This particular recess provides room ror the
formation of the bottom structure Or a cup. Ir the bottom
o~ the cup or container is not recessed, lt will not always
maintain its stability when lt slts on a surrace that ls not
exactly planar. A tubular ~;ectlon 42 is ~ormed as an inte-
gral part o~ top end plate '36. Tubular sectlon 42 ls
generally concentrlc with the cylindrical section 32 of
mandrel 14, although the ext;erlor Or sectlon 32 may ln some
instances have a slight taper to facllltate the removal Or
COmpleted containers from the mandrel. me lnterior bottom
end 44 cGntains an lnternally threaded bore 46 that is
zdapted ~cr engagement wlth simllar threads on slide column
4. Thus it is possible to not only disengage cylindrical
sectlon 32 from the remaining portion of mandrel 14, but it
is also an added advantage to be able to ~uickly change the
cyllndrlcal sectlon 32 to a longer or shorter plece wlthout
entlrely dismantllng or replacing the overall assembly 10.
Sllde column 48 contalns a centrally positloned through bore
50 that has an internal diameter of greater extent than the
outer dlameter of support column 16. A top slide bearlng 52
ls press ritted lnto the cen.trally posltioned bore 50 o~
sllde column 48. A similar bottom sllde bearing 54 is also
press fitted into the lower section of slide column 48. Thus
it can be observed that bearings 52 and 54 permit slide
column 48 to move up and down while being guided by the outer
surface of support column 16. ~lide column 48 ls biased in
an upward position by the influence o~ compression sprlng 56
which is positioned around support column 16 so that it
abutts against and extends from the lower end Or slide bearing
54 to the top inside surface 58 of hollow support post 24.
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The low~r end o~ sllde column 48 contains a radlally out-
wardly extending ~lange 60. A cyllndrlcal spacer bushing 62
ls pressed over the exteric,r Or sllde column 48 and ln abutt-
ing relatlonship with the t;op surface o~ outwardly extending
rlange 60. A cam disc 64 is posltloned in clrcum~erentlally
slidlng en8agement with the outer sur~ace o~ spacer bushing
62 m e cam disc also has its bottom surrace restlng on the
top surface Or outwardly extendlng ~lange 60. A handle 66
ls attached to cam dlsc 64 so that cam disc 64 can be rotated
in either dlrection about ;pacer bushing 62. A series o~ cam
pins 68 æ~e circumferentia:ly spaced around cam disc 64. The
cam pins ~8 protrude in an upward direction and coact with
c~m fol'owing tracks 70 whLch are positioned in radially
outwardly movable segments 72. It can be determined from the
description set rorth supra that slide column 48 moves up and
down along support column :l6 and also supports movable seg-
ments 72 which are adapted for movement in a radial direction
Attention is once again directed to hollow support
post 24. A cut-out 74 is provided so that handle 66 can move
rreely up and down with mandrel 14. The free cylindrical end
Or hollow support post 24 contains an internally cylindrical
cavity 76 that is bounded on its interior side by air distri-
bution ring 78. Air distribution ring 78 not only forms the
lnterior wall of cavity 76, but it also provides the means
for air egress ~rom cavity 76. Small air holes 80 permit a
continuous flow o~ radially inwardly directed cooling air to
flow from cavity 76. An a:ir infeed line 82 provides the air
supply to cylindrical cavity 76. The radially inward cylin-
drical extent of air distributian rlng 78 contains two
concentrically positioned ba~le rings 84 and 86. The spaces
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provlded between and ad~acent to ba~fle rln~s 84 and 86
create a turbulent ~low of air just arter the air has exlted
air holes 80. It is to be understood that the size and
spacing o~ holes 80 can be varied so as to provlde equal
heati-ng around the arcuate~ extent o~ air distributlon ring
78.
An abutment rin~; 88 is supported on a ledge formed
on the interior of hollow support post 24. The abutment
ring 88 is ~ree to float ln a radial direction through the
extent provlded for by gap 90. The vertical freedom Or
abutment r ng 88 is restrained by the bottom of air distri-
bution rin2 78.
Fig. 2 is a sec1;ional view taken along the lines
2-2 of Fig. l. Fig. 2 shows the movable segments 72 and the
arcuate cam following tracks 70 that are formed into the
lower bottom hal~ of each segment. Cam pins 68 are shown in
engagement wlth cam following tracks 70. The cam disc 64
which supports cam pins 68 is shown beneath the movable seg-
ments 72. The bottom pla1;e 38 contains a plurality of
radially oriented slide bars 92 which protrude in a downward
direction from the lower ~;urface of bottom plate 38. Sllde
bar 92 can be best seen in Fig. l. Each movable segment 72
contains a radially milled groove 94 in its top surface that
coacts with slide bar 92. The position of groove 94 is
shown in Fig. 2 although :Lt ls apparent that groove 94 is in
a position above section ;2-2. As each moYable segment 72 is
cammed radially outward and inward under the influence of
cam disc 64 and its attached cam pins 68, the movable seg-
ments 72 all keep their alignment and move only in a radial
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dlrection as desired.
Fig. 3 ls an enlarged fra~mentary view of that
area shown in circle 96 on Fig. 1. The top sldewall Or an
inverted ~oam plastlc contalner 98 ls shown in posltlon over
the mandrel 14 and bottom plate 38. The movable segments 72,
described heretofore, are in their radially inward position,
thus their cylindrical outer surface 100 is rlush wlth the
outer edge surface 102 of ~)ottom plate 38.
The leading or top end 104 of container 98 is
~ositioned so that it over]aps the outer surface of movable
segment 72. Care is exerclsed to assure that edge 104 does
not exter.d lower than the t;op surface 106 of abutment ring 88.
As the top end 104 of contalner 98 is positloned on mandrel
14, lt ls sub~ected to heated alr exiting from air holes 80.
The heat softened end 104 ls then ready for radlal expansion.
Flg. 4 ls a view similar to Fig. 3 except that
movable segments 72 have been moved to their radially outer-
most position, thus causin~; end 104 of container 98 to
lncrease in diameter. At this time, hot air is be~ng directed
by baffle rings 84 and 86 toward end 104 and its immedlate
area. The end 104, in its radially expanded position, is in
abutment with the top surface 106 of abutment ring 88.
Fig. 5 is a view similar to Fig. 4 except that the
entlre mandrel 14 assembly has begun its downward movement,
thus compressing compresslcn spring 56 which ls depicted ln
Fig. 1. Since the end 104 of container 98 is in abutment
with the top surface o~ abutment ring 88, it begins to bend
or curl outwardly and back against the sidewall of container
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98. Of course, as previou-;ly polnt~d out, abutment ring 88
does not move down with mandrel 14 slnce lt ls rlgidly
supported in a vertical dlrectlon by hollow support post 24.
Flg. 6 is a vlew slmilar to Flg, 5, however, the
mandrel 14 has moved to its downwardmost position. As man-
drel 14 moves downward, the end 104 of container 98 is
completely folded back aga'inst the sidewall Or the container.
At thls time the hot air from alr holes 80 ls reduced so
that lts impingement against the sldewall Or the contalner
98 will not have an adverse effect.
A.ter the rim has been formed on the contalner 98
as descrlbed and shown in ~lg. 6, the contalner is ready ~or
removal from the mandrel 14. Referring once again to Fig. 1,
an air source 108 is shown in base 12. The air source 108 ls
in turn coupled to a concentrlcally relief cut 110 in the
reduced dlameter sectlon 20 of support column 16. The alr
that reaches relief cut 110 vla air source 108 communicates
with alr passage 112 by way of air duct 114. Alr passage
112 ls rormed concentrically around support column 16 and is
positloned between top sllde bearlng 52 and bottom sllde
bearlng 54. Air duct 114 ls posltloned wlthln the central
extent Or support column 16. Apertures are placed ln the
sldes Or threaded bore 46, thus providing rurther communi-
catlon for the alr as it progresses from air passage 112 to
the space 116 between the lnner wall of cylindrical section
32 and the exterlor Or tubular section 42. Air egress holes
118 are positioned circumferentially around the perlpheral
extent of the top end plate 36 Or mandrel 14. m us it can
be observed that air from air æource 108 can be utili~ed to
3o create a force against the lnternal surface of a cup bottom~
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thus e~ectlng complet~d cup rrom the conrin~ment o~ mandrel
14 once the rim has been completely formed.
In the utili~atlon Or the contalner formlng
apparatus heretorore described, a cyllndrical sleeve of
oriented thermoplastic heat; shrlnkable plastic materlal is
positioned on the mandrel and the leading edge Or the
sleeve ls positioned as previously descrlbed and shown ln
the drawlngs. A portlon of the cylindrlcal sleeve extends
beyond the er.d of the mandrel and is subjected to a carerully
controlled and dlrected heat source such as hot alr. The
free end O~a the sleeve shrinks into a small elongate tube
that is but a fraction Or the sleeve's origlnal dlameter.
The sleeve ~s, while ln the heat softened condltlon, pressed
against the bottom of the mandrel to rorm an end closure on
the container.
The mandrel is made to telesco~e upon itself
when a force is applied to ~he free end. Thus, it becomes
evident that the rim of the container is formed at the same
time that the bottom of the container is pressed.
Thus lt becomes apparent that the present invention
contemplates not only the apparatus for rorming a contalner,
but also the method simultaneously forming the bottom Or a
one-plece container and also the rim Or the container.
m e container thus produced by the present apparatus
and`method has a rim that folds back upon itself, thus pro-
viding a reinrorcement for the reception Or a closure. The
rim is essentially two concentric cylindrical sections. me
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150
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rirst seotlon ls that cy~ drlcal portion Or the sldewall
near the top Or the container and the second section ls the
cyllndrical section of slightly larger diameter positioned
next to the first section. The two contiguous sectlons are,
of course, coupled ~ogether at the ~ery top of the rim.
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