Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The present invention relates to an improved cap
for use with containers whereby removal of the cap leaves
behind a telltale ring member, and specifically
to a method and mold for forming the capi and to a method of
removing them from the mold. There are presently available
many pilfer-proof closure or cap constructions of this type.
Tamper evident container caps are widely used to demonstrate
~o the final consumer that the contents of a container have
not been contaminated or adulterated subsequent to the time
the cap was initially secured to the container.
Generally, pilfer-proof caps are constructed with a
threaded skirt portion extending downwardly from the top wall
of the cap and a pilfer-proof ring member attached to the
lower end of the skirt. The ring is attached by frangible
members which break upon unthreading of the cap from the
container due to engagement of the ring member below a
protruding ledge or shoulder on the container. More
particularly, the ring includes an inside annular rib which,
in use on the container, is located below a cooperating
outwardly extending rib on the neck of the container. As the
cap is twisted off the container, contact between the outside
rib on the container neck and the inside rib on the separable
ring of the cap breaks the previously mentioned frangible
members, separating the ring from the remainder of the cap.
With metal closures, the formation of the pilfer-
proof ring is typically effected af~er the closure has been
placed onto the container. More particularly, the pilfer-
proof ring is secured under a cooperating shoulder on the
container neck by a rolling operation. With the advent of
molded plastic caps, the pilfer-proof ring portion of the cap
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is preformed as part of the initial molding of the cap. This
presents some problems with respect to structuring the
pilfer-proof ring and frangible members so that the cap can
be threaded onto the container without breaking the frangible
members. If breakage occurs, the ring is obviously of no
value for use as an indicator of tampering with or removal of
the closure.
The molding of plastic caps with pilfer-proof rings
also presents some problems. The molding operation reguires
1~ an internal die member for shaping the internal surface of
the cap. This die member has external threads just like the
bottle with which the cap is to be used. This thread
structure and other portions of the die required for forming
the pilfer-proof ring can interfere with removal of the cap
by obstructing the ring and causing it to break away just as
if the cap were being unthreaded from the container.
Attempts have been made to design plastic caps to
overcome the problems associated with molding and applying
the cap to the container. My prior patent, No. 4,32~,012
discloses a molded plastic pilfer-proof cap in which the
pilfer-proof ring is attached to the skirt by frangible
members and constructed internally with locking members
having the appropriate camming surface to permit threading of
the cap to the container without breaking o~ the frangible
members. Molding of this type of cap construction, however,
typically requires a collapsible inner die member.
UOS. Patent No. 4,147,268 also discloses a molded
plastic pilfer-proof cap. In this cap the pilfer-proof ring
is constructed with internally protruding locking members
30 which extend at an angle so as to permit the cap to be
removed from the internal die member by unthreading. This
- same structure permits the cap to be ~hreaded onto the
container. In addition, the locking members are provided
with camming surfaces to permit sliding over the locking
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shoulder of the container as the cap is fully threaded onto
the container.
SUMMARY OF THE INVENTION
The pilfer-proof cap constructed in accordance
with the teachings of co-pending parent Canadian Patent
Application No. 474,033, filed February ll, l9a5
includes a pilfer-proof ring which is structured and
connected to the skirt portion of the cap in such a
manner as to readily permit its removal from the
internal molding die and subsequent attachment to the
container. More particularly, the pilfer-
proof ring is constructed with an inwardly protruding lockingmeans, in the form of an annular rib, for engagement under a
cooperating rib or shoulder on the neck of the container to
which it is applied. The frangible means which connects the
pilfer-proof ring to the lower end of the skirt portion of
the cap is axially aligned with both the skirt and the
pilfer-proo~ ring.
The mold for forming this cap comprises a female
member forming a socket an an orifice for conducting plastic
material into the socket, and a male member including a core
assembly axially extending into the socket to form a mold
cavity with the female member. The outer surface of the male
member has a first annular recess for forming the radially
inwardly extending rib on the tamper indicating ring and a
second threaded recess for forming the internal threads on
the cap. The female member of the mold includes an upper
~ssembly that forms an upper portion of the socket, and a
lower assembly having a plurality of cams that form a lower
portion of the socket. Each of these cams has a radial
protrusion engaging the core assembly of the male member at
circumferentially spaced intervals to form an annular recess
in the cap axially separa~ing the skirt portion from the ring
and circumferentially separating the frangible members which
connect the ring to the skirt.
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To remove the cap from the mold, the female ~ember
of the mold is removed from the cap, and then the cap itself
is removed from the male member of the mold. The female
member is removed from the cap by moving the upper assembly
of the female member axially and the cams thereof radially
away from the cap. Preferably, the cap is shrunk onto the
male member to develop a space between the cap and the female
member of the mold prior to removing the female member from
the cap. Developing this space between the cap and the
female member of the mold eliminates any tendency of the
female member to rub against the cap or to tear or to pull
the cap apart as that female member is removed from the cap.
This permits the molding of caps wherein the outer wall
surface of the skirt portion i3 at a right angle to the ~op
of the cap rather than tapered outwardly from that top.
Removal of the cap from the male member is
accomplished, in part, by pushing on the bottom edge of the
ring of the cap in an upward direction. This forces the
inside rib of the ring out of the annular recess of the male
member in which that rib is formed.
The cap may be removed from the mold without
exerting ~ensile forces on the frangible members of the cap.
The axial alignment of the frangible members with the skirt
and ring together with their thickness provide enough axial
riqidity to prevent the pilfer-proof ring from unduly flexing
relative to the skirt portion of the cap during this removal
operation. The entire wall structure of the cap simply
expands more or less as an integral unit. Thus, breaking of
the frangible members is avoided. In this way, the frangible
members may be designed to break readily when any appreciable
tensile force is applied to those members, insuring that the
tamper indicating ring of the cap will break away from the
skirt of that cap when the cap is removed from a container.
This same feature is also useful during a~taching
the cap to the container. As the cap is threaded down onto
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the neck of the container, the bottom of the pilfer-proof
ring engages against the threads and creates an axial
compression of the ring toward the overlying skirt. This
holds the ring, frangible members and skirt together in
compression as an integral unit and permits them to expand
without such severe flexing of the rin~ relative to the skirt
which would cause breaking of the frangible members. The
bottom surface of the protruding rib locking means on the
pilfer-proof ring is also str~lctured to readily pèrmit this
expansion of the ring over the threaded portion of the neck
of the container.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is an enlarged cross-section view of
the cap made by the present invention showing generally
in schematic form a part of the internal mold structure
on which it is molded and with the cap partially removed
therefrom; and
Fig. 2 is an enlarged cross-sectional view,
partly broken away, showing the cap as attached to a
container.
Fig. 4 i5 an axial cross-sectional view of the cap
shown in Fig. 3, taken along line 4-4 thereof, showing the
cap secured to a container.
Fig. 5 is a front cross-sectional view through the
mold used to form the cap shown in Figs. 3 and 4, showing the
mold in a closed position.
Fig. 6 is a side cross-sectional view through the
mold shown in Fig. 5, showing the mold in an open position.
Fig. 7 is a top view showing the cam3 of the female
member of the mold illustrated in Figs. S and 6.
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Fig. 8 is an enlarged view of a portion of Fig. 5
showing the mold cavity in which the cap is formed and the
immediately adjacent parts of the mold in greater detail.
Figs. 9 and 10 are similar to Fig. 8 and depict in
sequential order different stages of the removal of the cap
from the mold.
Fig. 11 is a simplii-ied view of a molding apparatus
carrying a plurality of molds of the type shown in Figs. 5
and 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
with reference to Figs l and 2 the cap
produced by the present invention generally includes a
top wall l, a depending side wall or skirt 2 and the
improved pilfer-proof ring 3 attached to the bottom end
of the skirt. The internal wall surface of the skirt
includes a threaded portion 4 adapted to mate with
complementary threads S on the neck 6 of a container
such as shown in Fig. 2. The cap is fabricated from a
relatively rlgid plastic such as polypropylene.
The pilfer-proof ring 3 is connected to the skirt
portion of the cap by separate frangible members 7 and
includes a radially inwardly extending locking means in the
form of an inwardly directed protrusion or rib 8 extending
completely around the inner periphery of the ring. The
locking means is adapted to slide over a rib or shoulder 9 on
the outside surface of the container neck as the cap is
- threaded onto the container. With the cap fully threaded
onto the container, the locking means is positioned under the
shoulder 9 so that upon unthreading of the cap, upward
movement of the pilfer-proof ring will be blocked thereby.
The frangible members 7 connecting the ring to the skirt are
constructed so that they will break away as the ring engages
the shoulder 9. This puts the member~ 7 in tension and ~t
the same time causes the ring to expand outwardly, in turn,
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causing flexing of the members. The combined pulling and
flexing of the frangible members causes their breaking. More
particularly, as the cap is unthreaded from the bottle neck
6, the skirt 2 is moved upward and pulls the ring 3 upward
therewith. Upward movement of the ring 3 is resisted however
by contact between the rib 8 and the shoulder 9. This
contact and resistance, first, develops tensile forces on the
frangible members 7 connecting the ring 3 to the skirt 2 and
second, forces the rib 8 and those frangible members
outwardly. The combination of the tensile forces and the
outward flexing of the frangible members 7 breaks the
members, separating the ring 3 from the skirt 2. The skirt 2
is then completely unthreaded from the bottle neck 6, opening
the bottle and leaving the ring 3 behind.
In accordance with the teachings of the
afore~aid parent application, the frangible members 7
are axially aligned with both the skirt and ring
portions of the cap adjacent the outside surface of the
skirt. They also are constructed with a sufficient
cross-sectional dimension so as to provide axial
rigidity between the skirt and the ring upon subjecting the
ring to an axial compressive force directed toward the s~irt.
This construction facilitates removal of the molded cap from
the internal die member 10 on which it i9 formed. Removal is
effec~ed by pushing the cap off the internal die member by a
stripper ring 10'. The pushing force is exerted against the
bottom of the pilfer-proof ring as indicated in Fig. 1. Due
to the axial alignment of the frangible members 7 with both
the ring and skirt and also due to the cross-section
thickness of the frangible members, the force exerted on the
bottom of the ring puts the members in compression. The
pushing force is directed in a generally straight line
through the ring, frangible members and skirt with the result
that there ils little bending moment created.
The cap generally expands radially outwardly as it
is removed from the internal die member 10. Partial removal
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of the cap from the die member is shown in Fig. 1. There it
is seen that the internal thread 4 of the cap as it engages
against the external thread 11 on the die member 10 effects a
camming of the skirt portion of the cap radially outwardly of
the die member. The skirt actually expands as it is cammed
over the die threads. At the same time the upper surface 12
of the locking protrusion 8 on the pilfer-proof ring engages
against the complementary shaped wall surface 13 of the
internal die member. This engagement effects a camming of
the ring in a radially outwardly direction to cause it to
expand at the same time the skirt is being cammed and
expanded radially outwardly.
Doe to the location of the frangible members and
the rigidity provided by their cross-sectional thickness, the
skirt and ring expand more or less as an integral unit
without flexing of the ring relative to the sXirt to an
extent which would cause breaking of the frangible members.
Removal of the molded cap from the internal die member can
therefore be accomplished with a simple pushing operation.
Complicated collapsible male die structure is not required.
In the preferred embodiment of the cap the
inwardly directed protrusion 8 of the locking
portion of the pilfer-proof ring has an axial cross-section
which is generally conical in shape. That is, this cross-
section of protrusion 8 has a shape generally similar to theshape of an axial cross-section of a solid cone. The upper
surface 12 of thiR pro~rusion is a straight surface; and as
shown in Fig. 2, this surface i5 disposed at ~n angle about
equal to the angle at which the shoulder 9 of the container
extends. The bottom surface of the protrusion has an axially
downwardly facing convex surface 14. These surfaces
facilitate connection of the cap to the container and
retention of the ring on the container upon re~oval of the
cap. More particularly, the flat surface 12 engages against
the complementary shaped surface of the shoulder 9 whereby
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axial unthreading of the cap produces a pulling effect on the
ring and the frangible members to put them in tension. The
tensionin~ or pulling on the frangible members together with
their simultaneous flexing as the ring is ca~med outwardly
over the shoulder 9 of the bottle causes the frangible
members to break.
The convex shape of the bottom surface 14 of the
protrusion 8 of the pilfer-proof ring assists in camming the
ring over the threads 5 of the container neck as the cap is
threaded onto the container. Again, engagement of the bottom
of the ring against the threads produces some compressive
force through the ring, frangible members and skirt coupling
these members together as an integral unit to thereby prevent
undue flexing of the ring relative to the skirt. And without
1~ any simultaneous pulling of the frangible members as occurs
upon removing the cap from the container, they do not break.
As shown in Figs. 1 and 2, the radially inwardly
most surface of the protrusion 8 of the pilfer-proof ring is
provided with multiple circumferentially spaced areas 15
disposed radially outwardly of the remainder of this surface.
Although these areas 15 are located radially ou~wardly of the
innermost extent of the protrusion, they will, nevertheless,
be located under the shoulder 9 of the container when the cap
is fully threaded onto the container~ This is shown in Fig.
2. Accordingly, engagement of the upper surface 12 of the
protrusion with the shoulder 9 occurs at all point~ around
the pilfer-proof ring.
In the preferred embodiment, the circumferentially
spaced areas are curved to dPfine radially inwardly facing
curved portions and they are evenly spaced from each other.
Together they extend over one-half of the inner periphery of
the protrusion 8. There are eight such areas spaced about
the internal periphery and each area covers a circumferential
distance of about 22 1/2~. The remainder of the inner
surface of the protrusion 8 is formed as flats 16. These
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flats define chordal portions, spaced between the curved
portions of the protrusion, and are aligned with the
frangible members 7.
Figs. 5 through 10 illustrate in detail the
presently preferred continuation of a mold 50 for forming the
cap of Figs. 3 and 4. Mold 50 comprises a female member 52
and a male member 54. The female member 52 forms a socket 56
and an orifice 58 for conducting plastic material, such as
polypropylene, into that socket. More specifically, a cavity
plate 60 of female member 52 forms a central opening 62 and a
mold piece 64, which forms an upper portion of the socket 56,
is disposed therein. A clamp plate 66 extends over the mold
piece 64 and over the cavity plate 60 and is bolted to the
cavity plate to clamp the mold piece within the central
opening 62. A material conduit 70 is secured to the clamp
plate 66 and forms an upper portion of the orifice 58. One
or more water passages 72 extend through female member 52,
adjacent the socket 56, to conduct water through the female
member of the mold 50 to cool material fed into the socket
56.
A plurality of cams 74 together form a lower
portion of the socket 56, and these cams include radial
projections 76 that engage circumferentially spaced section
of male member 52, specifically a core assembly 78 thereof,
to form the annular recess of the cap between franyible
members 16 thereof. The cams 74 rest on and are supported by
the male member 54 specifically a top surface 80 thereof, for
sliding movement between a closed position, shown in Fig 5,
wherein the cams engage core assembly 78, and an open
position, shown in Fig 6, wherein the cams are spaced from
the core assembly to facilitate removing cap from the mold
cavity in which the cap is formed.
A spring 82 is provided to urge the cam3 74 from
their closed position to their open position. In particular,
the spring 82 is a conventional clip spring with a circular
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shape and is positioned against radially inwardly facing
surfaces of the cams 74, urging those cams radially
outwardly, away from the core assembly 78. A groove is
formed in these radially inwardly facing surfaces of the cams
74 to hold the spring 82. A plurality of screws or bolts 84
are threaded into the top surface 80 of male member 54 to
limit outward movement of the cams 74. Means other than
springs 82 ~ay be used to move cams 74 to their open
positions. For instance a plurality of pins may be connected
to the cavity plate 60 and slant downwardly outwardly into
sockets formed in the cams, whereby the pins would push the
cams outwardly when the cavity plate 60 is raised and push
the cams 74 inwardly when the cavity plate is lowered. Also,
means 86 (illustrated in Fig. 7) such as L-shaped pins,
rails, pins, or similar devices may be secured to the surface
80 to guide movement of the cams 74 between their open and
closed positions and to hold those cams against upward axial
movement away from the surface 80.
With the embodiment of mold 50 illustrated in the
drawings, the cams 74 are moved from their open position to
their closed position and are releasably held in the latter
position by means of engagement between cooperating surfaces
of the cams and the cavity plate 60. More specifically, ~he
cams 74 have upper surfaces 90 that slant upwardly radially
inwardly, and cavity plate 60 has a lower surface 92 directly
above the upper surfaces 90 of the cams and that also slants
upwardly radially inwardly. As cavity plate 60 moves
downwardly from its open position, shown in Fig. 6, ~o its
closed position, shown in Fig. 3, the surface 92 of the
cavi~y plate contacts ~he surfaces 90 of the cam3 74 and
forces those cams radially inwardly to their closed position.
As the cavity plate 60 is held in its closed position, the
surface 92 holds the cams 74 in their closed po~ition.
With par~icular reference to Fig. 7, inside edges
of the radial protrusions 76 of the cams 74 have a plurality
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of circumferentially spaced grooves 94. When cams 74 are in
their closed position, the grooves 94 form openings extending
between the cams and the core assembly 78. The frangible
members 7 of the cap are formed in those openings. Also,
while the embodiment of mold 50 shown in the drawings
includes four cams 74, the mold may be provided with fewer or
more cams, for example two, six, or eight, without departing
from the scope of the present invention.
As outlined above, cavity plate 60, mold piece 64,
clamp plate 66, and material conduit 70 comprise an upper
assembly of female member 52 oE mold 5~; and cams 74, spring
82, and guide means 86 comprise a lower assembly of the
female member.
A support assembly 96 of male member 54 provides a
base of support for the female member 52 and the other parts
of the male member of the mold 50. Plates sa and lO0 of the
assembly 96 are generally horizontal and parallel, and these
plates form generally aligned central openings 102 and 104
respectively. Spacer blocks 106 and 110 of the support
assembly 96 extend between the plates 98 and 100, across the
bottom left and right sides of the mold S0. The various
plates and blocks of the support assembly 96 are secured
together by a plurality of bolts to form a rigid, unitary
assembly.
With respect to the core assembly 78 of male member
54, when the mold 50 is in the closed, or cap forming
position, shown in Fig. 5, the core assembly 78 axially
extended into the socket 56 to form, with the female member
52, the particular mold cavity in which the c~p is formed.
More specifically, an outer core piece 112 rests on the upper
plate 98 of the support assembly 96 and extended axially
- upwardly therefrom. The upper portion of the outer core
piece 112 extends into the socket 56 of the female member 52
and, during formation of cap, forms the interior of the sides
and a portion of the interior of the top of the cap. The
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upper portion of the outer core piece 112 includes a firs~
recess 114 which is used to form the rib 8 on the ring of the
cap and a second annular recess 116 to form the threads 4 of
the cap.
The outer core piece 112 is axially held in place
by means of a retainer sleeve 118 and a retainer ring 120.
The bottom portion of the outer core piece 1t2 includes a
radially outwardly extending shoulder, and the retainer
sleeve 118 includes a downwardLy facing radial surface that
extends directly over that shoulder of the outer core member.
In turn, the lower portion of the retainer ~leeve 118
includes a radially outwardly extending shoulder, and the
retainer ring 120 includes a downwardly facing radial surface
that extends directly over that shoulder of the retainer
sleeve. The retainer ring 120 itself is securely bolted to
the top plate 98 of support assembly 96.
The interior of the outer core piece 112 forms an
axial through bore, and an inner core piece 104 extends
therein and is supported for axial movement relative to ~he
outer core piece. The upper portions of the inner core piece
122 and the through bore of outer core piece 112 are both
flared out. In the closed position shown in Fig. 5, the top
surface of the inner core piece 122 i~ ubstantially coplanar
with the top surface of the outer core piece 112 and, during
formation of the cap, forms the major portion of the interior
surface of the top of the cap. The outer and inner core
pieces 112 and 122 together form a top axial recess 124 in
which top annular sealing member 26 of the cap is formed, and
the inner core piece 12Z forms a top axially slanted recess
126 in which the top annular sealing member 30 of the cap is
formed. Preferably, the inner core piece 122 includes a
separable upper insert that is in a tight pressure fit with
the main body of the inner core piece, and these two pieces
in combination form the recess 126.
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The inner core piece 122 also defines an axial
through bore and a knockout pin 130 axially extends therein
and is supported for axial movement relative to the inner
core piece. The knockout pin 130 generally i5 a smooth,
solid cylinder, with a small annular shoulder 132 extending
outward from the bottom of the pin. When the mold 50 is in
the closed position shown in Fig. 5, the top surface of the
knockout pin 130 is coplanar with the top surface of the
inner core piece 122, and the knockout pin extends downwardly
therefrom, through the inner core member, to a position below
the bottom thereof. One or more water passages 134 extend
through the knockout pin 130 to conduct water therethrough,
adjacent the mold cavity in which the cap is formed, to cool
material fed into the mold cavity.
A stripping assembly 136 is provided to push cap
axially off core assembly 78. The stripping assembly 1~6
includes a ring 138 and a plate 140. Ring 138 extends around
core assembly 78, below ~he mold cavity in which the cap i5
formed, to push the bottom of the cap off the core assembly,
and the ring 138 rests directly on plate 140 so that upward
movement of the plate 140 moves the ring 138 upwardly. When
the mold 50 is in the closed position shown in Fig. 5, and
upper portion of ring 138 tightly fits around an intermediate
portion of outer core piece 112 and form3 the bottom of the
mold cavity in which cap is formed. An outer portion of ring
138 forms a radially outwardly extending shoulder 142 that
rests on the top surface 80 of the plate 140. This
engagement between ~houlder 142 and surface 80 forces ring
138 upward with plate 140. A lower portion of ring 138
axially extends into a central opening 146 of plate 140, in a
close radial fit therewith, to hold the ring 138 securely in
place, around core assembly 78.
The plate 140 directly rests on the top support
plates 98 when the mold 50 is in the closed po~ition shown in
Fig. 5. When cavity plate 60 and mold piece 64 of female
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member 52 are moved upward away from their closed position
shown in Fig. 5, the plate 140 is free to move upward away
from support plate 98 for a limited distance, and means such
as springs 150 are provided to move the plate 140 upward
relative to that support plate. More particularly, the plate
140 and support plate 98 form a plurality of recesses, and
springs 150, which may be conventional coil springs, are
located in these recesses, urging plates 140 and 9~ axially
apart. Cf course, means other than conventional coil
springs, for example air or hydraulic cylinders, may be used
to move the plate 140 away from the support plate 98. Means
such as bolts 152 (only one is shown in the drawings), may be
used to guide axial movement of the plate 140 away from and
towards support plate 98 and to limit axial movement of the
plate 140 away from that support plate.
A first ejector assembly 154 is located be~ween
plates 92, 94, 96 and 100, and engages the inner core piece
122 to push that core piece upward to belp push the cap 10
off the outer core piece 112. Plates 156 and 158 of the
ejector assembly 154 form central openings, with the inner
core member 122 extendin~ through those openings in a close
radial fit with the surfaces thereof. Bolts 152 extend
between the plate 156 and the plate 140 to move the former
plate axially upward with the latter plate, and bolts 160
(only one is shown in the drawings) connect the plate 158 to
the plate 156 for unitary axial movement. A retainer ring
162, which may be a conventional snap ring, is secured within
an a~nular groove formed in the lower portion of the outside
surface of the interior core member 122, extends radially
outward therefrom, and is tightly captured between the plates
156 an 158. In this manner, upward movement of the plate 158
- forces the ring 162, and thus the core member 122, upward
therewith; while downward movement of the plate 156 forces
the ring 162, and hence ~he core member 122, downward
therewith.
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A second ejector assembly 164 is located directly
below the first ejector assembly 154 and engages the knockout
pin 130 to push that pin upward. A plate 166 of the second
ejector assembly 164 extends directly below and contacts the
bottom of the knockout pin 130O Another plate 168 of the
ejector assembly 164 is located above the plate 166, is
connected thereto by means of bolts 170 (only one is shown in
the drawings), and forms a central axial opening through
which the knockout pin 130 extends.
The plate 168 forms a downwardly facing radial
surface that extends directly over the shoulder 132 of the
~nockout pin 130. With this arrangement, upward movement of
the plate 166 forces the knockout pin 130 upward therewith
via the direct contact between the plate 16S and the knockout
pin; while downward movement of the plate 166 forces the
knockout pin downward therewith via the bolts 170, the plate
168, and the shoulder 132. The plate 166, in turn~ is
connected to a pair of knockout bars 174 by connecting pins
176 for unitary upward and downward movement therewith.
Bolts 178 (only one i5 shown in the drawings) are secured to
the plate 158 of the first ejector assembly 1S4 and extend
through ~he plates 166 and 168 of the second ejector
assembly 164 to guide axial movement of t~e second ejector
assembly within the mold 50. The bolts 178 also serve to
pull the first ejector assembly 154 downward with the second
ejector assembly 1~4 after the former assembly has moved a
pre-set, limited distance downward relative to the latter
asse~bly.
In operation, ~he mold 50 is connected to a molding
apparatus 180, schematically shown in Fig. 11, that first,
supports the mold 50, and second, operates to raise and to
lower the knockout bars 174, the upper assembly of the female
member 52, and the stripping assembly 136 of the male member
54. A~ a practical matter, it will normally be more
economical to connect a multitude of the molds 50 to a sinqle
molding apparatus.
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If this is done, it should be observèd, it is not
necessary to provide each mold 50 with separate
means for raising the cap, stripper mechanism 136 of the
mold. For instance, a molding apparatus that carries twenty
or thirty molds 50 may use two, four, or six air..cylinders
182 to raise the cap stripper mechanisms of the molds.
With reference to Fig 5, to form the container cap,
plastic material, such as polypropylene, is injected through
the orifice 158 to fill the mold cavity formed between the
female and male members 52 and 54. Coolinq water is
conducted through the water passages 72 and 134 of the mold
50, and the plastic material in the mold cavity cools and
hardens. This cooling of female and male members 52 and 54
-- in particular, the rate at which the cooling water is
conducted through those members -- is controlled so that the
temperature of the portion of the male member adjacent the
cap is maintained below the temperature o~ the portion of the
female member adjacent the cap. For example~ the portion of
the male member 52 adjacent the mold cavity in which the cap
is formed may be maintained at 400~ while the portion of the
female member 54 adjacent that mold cavity may be maintained
at 600~F. Because of this temperature difference, as the
plastic material in the mold cavity hardens, the material in
the mold cavity shrinks onto the male member 52, specifically
the core as~embly 78 thereof, and a space develops between
the cap and the female member 54, specifically mold piece 64
thereof.
Once the cap hardens, the female member 54 is
removed from the cap. With reference to Figure~ 4 and 9,
thi3 i3 done by moving the upper assembly of the female
member 54 upwardly axially and the lower assembly of the
female member 54 radially away from the cap. This is done by
expanding cylinders 184 of molding apparatu~ t80, which
raises plate 186 thereof, which in turn, raises
clamp plate 66, cavity plate 60, and mold
piece 64 of mold 50. Since the cams 74 are
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releasably held in their closed position by the pressure
exerted on the cams by the cavity plate 60, as soon as the
cavity plate is moved away from the cams, tho~e cams
automatically slide outward along the surface 80, away from
the cap.
It should be observed that, because of the space
developed between the mold piece 64 and the cap, that mold
piece does not rub against or tend to ~ear or to pull the cap
apart as the upper assembly is moved away from the cap.
This, of course, facilitate moving the mold piece 64 away
from the cap and ensures that 1:he mold piece does not weaken
or otherwise deleteriously affect the container cap as the
mold piece moves away therefrom. This permits the molding of
cap wherein the outer wall surface of the skirt portion of
the cap is at a right angle to the top of the cap rather than
tapered outwardly downwardly therefrom.
Next, the cap is removed from the male member 54.
This is done through coordinated movement of the stripping
assembly 136, the inner core piece 122, the knockout pin 130,
and the first and second ejector assemblies 154 and 164. As
- the cavity plate 60 of the female member 52 is moved
upwardly, the plate 140 becomes free to move upwardly, and
the plate 140 is moved upwardly by the spring~ 150.
Alternatively, with the arrangement depicted in Fig. 11,
plate 140 may be moved upwardly by means of cylinders 182
plate 190, which is rigidly secured to the plates 140 of the
molds ~0 shown in Pig. 11. A~ the plate 140 is pushed
upwardly, that plate, first, pushes the ring 138 upwardly;
and second, pulls the bolts 152, the first ejector assembly
154, and the inner core member 122 of the core assembly 78
upwardly. With reference to Fig. 9, as the ring 138 is
pushed upwardly, this ring, in turn, pu~he~ the bo~tom of the
cap upwardly, pu~hing the rib 8 and the threads 4 out of the
recesses 114 and 116 of the outer core piece 112.
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Because the rib 8 is pushed -- a~ opposed to pulled
-- out of the recess 114, the frangible members 7 of the cap
are not stretched, ~ut rather are compressed, as the rib 8 is
removed from the recess in which the rib 8 is formed. Thus,
the cap may be removed from the mold 50 without exerting
appreciable tensile forces on the frangible members 7.
At the same time that: the ring 138 is pushing the
bottom of the cap upwardly, the inner core piece 122 and the
knock-out pin 130 are moved upwardly to push the top of the
container cap away from the outer core piece 112. The inner
core piece 122 is moved upwardly by means of the first
ejector assembly 154 which, as discussed above, is pulled
upwardly with the plate 140 by means of the bolts 152. The
knockout pin 130 is pushed upwardly by the second ejector
assembly 164, which itself is moved upwardly by the knockout
bars 174. The knockout bars 174 are pushed via cylinders 192
and plate 194 of molding apparatus 180.
The stripper plate 140~ the ring 138, the first
ejector assembly 154, and the inner core piece 122 continue
to move upwardly until the plate 156 of the first ejector
a!;sembly abut~ against the plate 98, as shown in Fig 6,
terminating the upwardly movement of the plate 156, the first
ejector assembly, and the inner core pie~e. At this time,
the plate 15~ of the ejector assembly 154 also prevents
further upwardly movement of the bolts 152, preventing
further upwardly movement of the plate 14~. Because the
plate 140 can no longer move upwardly, that plate does not
force the cam3 74 or the ring 38 further upwardly, and the
came and the ring 138 come to a s op. The po~ition of the
plate 140, the ring 138, the inner core piece 122, and the
- knockout pin 130 when upwardly movement of the plate 140, the
ring 138, and the inner core piece is terminated is shown in
Fig. 8. It should be noted that the ring 138 iR employed ~o
push the rib 8 of the cap past the recess 116 in which the
threads 8 of ~he container cap are formed. In thi~ way, the
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frangible members 7 of the cap are not stretched in case the
rib 8 rubs against upper surfaces of the recess 116 as that
rib slides upwardly therepast.
The knockout pin 130 is free to continue to move
upwardly from the position shown in Fig. 10, however, and the
knockout pin is so moved by further upwardly movement of the
second ejector assembly 164. 'rhe knockout pin 130 directly
contacts the central portion oE the top of the cap, and as
- the knockout pin is pushed upwardly, the knockout pin forces
1~ the cap completely off and away from the outer and the inner
core pieces 112 and 122, from the position shown in Fig. 10
to the position shown in broken lines in Fig. 6. From this
position, the cap may be lifted off the knockout pin 130, and
completely removed from the mold 50 by hand.
Once the cap is removed, the knockout bars 174 are
pulled downwardly to the position in Fig 5, pulling the
second ejector assembly 164 and the knockout pin 130
downwardly into their position shown in Fig. 5. As the top
plate 168 of the second ejector assembly 164 moves
downwardly, that plate engages the head of the bolt 178 and
pu115 that bolt downwardly. This pulls the plate 158 of the
first ejector assembly 154 downwardly, and this pulls the
plate 156 of that ejector assembly downwardly via the bolts
160. As the plate 156 is pulled downward, that plate forces
the inner core piece 102 downward via the retainer ring 162
and, at the same time, forces the bolts 152 downward, which
in turn pulls the plate 140 downward. The ring 138 an~ the
cams 74 are pulled downward with the plate 140. With the
knockout pin 130, the inner core piece 112, the cams 7~, the
stripping assembly 136, and the ejector as3emblies 154 and
164 all moved downwardly, the upper assembly of the female
member 52 is then moved downwardly into its closed po~ition.
This forces the cams 74 radially inwardly, into their closed
position, rendering the mold 50 again ready for use.
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