U.S. patent application number 10/816500 was filed with the patent office on 2005-10-06 for preform assembly, container assembly, and method of manufacture.
Invention is credited to Barker, Keith J., Kalmouni, Bassam M., Lynch, Brian A., Mani, Nikhil, Nahill, Thomas E..
Application Number | 20050218103 10/816500 |
Document ID | / |
Family ID | 34964346 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050218103 |
Kind Code |
A1 |
Barker, Keith J. ; et
al. |
October 6, 2005 |
Preform assembly, container assembly, and method of manufacture
Abstract
A method of making a preform assembly including providing a
finish ring of plastic construction, placing the finish ring onto a
core pin, introducing a preform polymer into a mold cavity that
includes the core pin, and compression molding the preform polymer
to the finish ring. A resulting preform assembly, and container
assembly blow-molded from the preform assembly, are also
disclosed.
Inventors: |
Barker, Keith J.; (Candia,
NH) ; Kalmouni, Bassam M.; (Pembroke, NH) ;
Lynch, Brian A.; (Merrimack, NH) ; Mani, Nikhil;
(Billerica, MA) ; Nahill, Thomas E.; (Amherst,
NH) |
Correspondence
Address: |
OWENS-ILLINOIS, INC.
ONE SEAGATE, 25-LDP
TOLEDO
OH
43666
US
|
Family ID: |
34964346 |
Appl. No.: |
10/816500 |
Filed: |
April 1, 2004 |
Current U.S.
Class: |
215/44 ; 215/40;
428/36.92 |
Current CPC
Class: |
B29B 11/14 20130101;
B29K 2023/086 20130101; B29K 2067/00 20130101; B29B 2911/14326
20130101; B29B 2911/14093 20130101; B29B 11/12 20130101; B29B
2911/14337 20150501; B29B 2911/1444 20130101; B29B 11/08 20130101;
B29B 2911/1412 20130101; B29B 2911/1406 20130101; B29B 2911/1458
20130101; B29B 2911/14033 20130101; B29B 2911/14126 20130101; B29B
2911/14466 20130101; B29C 49/0073 20130101; B29B 2911/1404
20130101; B29B 2911/14146 20130101; B29B 2911/14226 20130101; B29K
2023/06 20130101; B29B 2911/14333 20130101; B29B 2911/14153
20130101; Y10T 428/1397 20150115; B29B 2911/14233 20130101; B29B
2911/14066 20130101; B29B 2911/1402 20130101; B29L 2001/00
20130101; B29B 2911/14026 20130101; B29C 43/18 20130101; B29B
2911/14053 20130101; B29B 2911/14113 20130101; B29K 2023/12
20130101; B29B 2911/1408 20130101; B29B 2911/14328 20150501; B29B
2911/14335 20150501; B65D 1/023 20130101 |
Class at
Publication: |
215/044 ;
215/040; 428/036.92 |
International
Class: |
B65D 041/58; B65D
001/02 |
Claims
1. A method of making a preform assembly, said method including:
(a) providing a finish ring of plastic construction, (b) placing
said finish ring onto a core pin, (c) introducing a preform polymer
into a mold cavity, (d) placing said core pin and finish ring into
said mold cavity around said core pin, and (e) compression molding
said preform polymer to said finish ring.
2. The method of claim 1 wherein said step (a) includes providing
said finish ring with an internal surface having at least one
radial interengagement feature, such that a portion of said preform
polymer flows during said step (e) into interengagement with said
at least one radial interengagement feature during said compression
molding step.
3. The method of claim 2 wherein said step (a) includes said at
least one radial interengagement feature being at least one radial
recess, such that a portion of said preform polymer flows into said
at least one radial recess during said compression molding
step.
4. The method of claim 3 wherein said step (a) also includes said
at least one radial recess being at least one annular groove, such
that a portion of said preform polymer flows into said at least one
annular groove during said compression molding step.
5. The method of claim 1 wherein said step (a) includes providing
said finish ring with an internal surface having at least a portion
thereof greater in diameter than said core pin, such that a gap is
formed during said step (e) between said at least a portion of said
internal surface, said core pin, and a forward edge of said preform
polymer, said gap being provided to accommodate within-tolerance
variation of a molten charge of said preform polymer to prevent
overpacking of said preform polymer into said finish ring.
6. A preform assembly produced by the method of claim 5.
7. A preform assembly produced by the method of claim 1.
8. A method of making a container assembly includes blow molding
the preform assembly of claim 7.
9. A container assembly produced by the method of claim 8.
10. A preform assembly for blow molding a container assembly, which
includes: a molded plastic finish ring, and a plastic preform
compression molded to said finish ring such that a neck portion of
said plastic preform radially interengages said finish ring.
11. The preform assembly set forth in claim 10 wherein said finish
ring includes at least one internal surface with at least one
radial interengagement feature formed therein, further wherein said
neck portion of said plastic preform radially interengages with
said at least one radial interengagement feature.
12. The preform assembly set forth in claim 10 wherein said finish
ring includes at least one tapered internal surface, at least one
straight internal surface, and a transition point therebetween, and
wherein there is an open gap between said transition point and a
forward edge of said neck portion of said plastic preform to
prevent said neck portion of said plastic preform from being
overpacked into said finish ring.
13. A container assembly blow molded from a preform assembly
produced from compression molding a preform to a molded plastic
finish ring, said container assembly includes: said molded plastic
finish ring, and a plastic container having a neck portion thereof
interengaging said finish ring.
14. The container assembly set forth in claim 13 wherein said
finish ring includes at least one internal surface with at least
one radial interengagement feature formed therein, and wherein said
neck portion of said plastic container interengages with said at
least one radial interengagement feature.
15. The container assembly set forth in claim 14 wherein said
finish ring includes at least one tapered internal surface, at
least one straight internal surface, and a transition point
therebetween, and wherein a gap is defined between said transition
point and a forward edge of said neck portion of said plastic
container to prevent said neck portion of said plastic container
from being overpacked into said finish ring.
Description
[0001] The present invention is directed to preform assemblies for
blow molding plastic container assemblies, to plastic container
assemblies blow molded from such preform assemblies, and to methods
of making such preform assemblies and container assemblies.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] In the manufacture of plastic containers, it is conventional
to injection mold or compression mold a container preform having a
body and a neck finish with one or more external threads or other
closure attachment means. The preform neck finish typically is
molded to its final geometry, while the body of the preform
subsequently is blow molded to the desired geometry of the
container body. The preform may be of monolayer construction, or
may be of multilayer construction in which one or more intermediate
layers in the preform body may or may not extend into the neck
finish of the preform. U.S. Pat. Nos. 4,609,516, 4,710,118 and
4,954,376 illustrate injection molding of multilayer container
preforms.
[0003] Molding the neck finish portion of a container as part of
the container preform presents a number of problems. For example,
when the preforms are formed by injection molding, the plastic
material typically is injected into a mold cavity at the closed end
of the preform body, so that the material must flow along the sides
of the preform mold cavity into the area in which the neck finish
is molded. The neck finish typically requires more accurate and
stable dimensioning than the body of the preform, which can limit
the cycle time of the preform molding process. Furthermore, the
neck finish of the preform is of the same material as a monolayer
preform body, and of the same material as at least the outer layers
of a multilayer preform body, which limits the ability to obtain
the most desirable material characteristics at the neck finish.
When the preform is of polyester construction, such as polyethylene
terephthalate (PET), the neck finish of the preform can be wholly
or partially crystallized to improve the operating characteristics
of the neck finish area, particularly in hot-fill container
applications. However, the requirement that the neck finish be of
the same material as at least the outer layers of a multilayer
preform body still limits the design capabilities of preform
manufacture.
[0004] A method of making a preform assembly in accordance with one
aspect of th present invention includes providing a finish ring of
plastic construction, placing the finish ring onto a core pin,
introducing a preform polymer into a mold cavity that includes the
core pin, and compression molding the preform polymer to the finish
ring.
[0005] In accordance with a second aspect of the present invention,
there is provided a preform assembly for blow molding a container
assembly, which includes a molded plastic finish ring and a plastic
preform compression molded to the finish ring such that a neck
portion of the plastic preform radially interengages the finish
ring.
[0006] In accordance with a third aspect of the invention, there is
provided a container assembly blow molded from a preform assembly
which is produced from compression molding a preform to a molded
plastic finish ring. The container assembly includes the molded
plastic finish ring, and a plastic container having a neck portion
thereof radially interengaging said finish ring.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention, together with additional objects, features,
advantages and aspects thereof, will be best understood from the
following description, the appended claims and the accompanying
drawings, in which:
[0008] FIG. 1 illustrates a side elevational view of a preform
assembly according to one exemplary embodiment of the present
invention;
[0009] FIG. 2 illustrates a side elevational view of a container
assembly, blow-molded from the preform assembly of FIG. 1,
according to another exemplary embodiment of the present
invention;
[0010] FIG. 3 illustrates a side elevational view of a finish ring
for the preform and container assemblies of FIGS. 1 and 2;
[0011] FIG. 4 illustrates a top view of the finish ring of FIG.
3;
[0012] FIG. 5 illustrates a cross-sectional view of the finish ring
of FIG. 3, taken along line 5-5;
[0013] FIG. 6A illustrates a compression molding apparatus for use
in accordance with an exemplary method of the present invention,
wherein the apparatus is shown in an open position in which a
charge of preform material is located within a mold cavity and a
pre-made finish ring is loaded to a core pin;
[0014] FIG. 6B illustrates the compression molding apparatus of
FIG. 6A wherein the apparatus is shown in a closed position in
which the preform material is compression molded within a portion
of the pre-made finish ring;
[0015] FIG. 7 illustrates a fragmentary cross-sectional view of a
portion of the compression molding apparatus of FIGS. 6A and 6B and
a cross-sectional view of the resulting preform assembly, wherein
the preform assembly has been retracted and is carried on the
compression core pin; and
[0016] FIG. 8 illustrates an enlarged cross-sectional view of the
preform assembly of FIG. 7, taken from circle 8 thereof.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0017] FIG. 1 illustrates a preform assembly 20 in accordance with
one presently preferred embodiment of the invention as comprising a
preform 22 and a separate finish ring 24 secured thereover. The
preform 22 may be injection molded, but is preferably produced by
compression molding as will be discussed in greater detail below.
The preform 22 is composed of any suitable plastic material such as
monolayer polyethylene terephthalate (PET) or the like, or
multilayer PET or the like in which matrix layers of PET, for
example, alternated with one or more layers of a barrier resin
material such as ethylene vinyl alcohol (EVOH), nylon or the like.
The finish ring 24 is injection or compression molded or the like,
and is composed of any desired material such as PET, post consumer
resin (PCR), process regrind (REG), polypropylene (PP),
polyethylene (PE), polyethylene napthalate (PEN), or the like.
Preferably, however, the finish ring 24 is composed of a material
different than that of the preform 22, such as amorphous PET for
preform 72 and crystalized PET for finish ring 24. FIG. 2
illustrates a container assembly 120 that is blow molded from the
preform assembly 20 of FIG. 1 in accordance with another presently
preferred embodiment of the present invention, and includes the
finish ring 24 secured to a container 122 in a manner that is in
all significant respects identical to that of the preform assembly
20 from which the container assembly 120 is blow-molded.
Accordingly, such securement details will not be repeated for this
embodiment.
[0018] In FIG. 1, the preform 22 includes a closed lower end 26 and
extends upwardly therefrom in the form of a body 28 that terminates
in a cylindrical neck 30 that is integrally molded with the body
26. (Directional words such as "upper" and "lower" are employed by
way of description and not limitation with respect to the upright
orientation of the preform assemblies and components illustrated in
the drawings. Directional words such as "radial" and
"circumferential" are employed by way of description and not
limitation with respect to the axis of the preform neck or finish
ring as appropriate.) As also shown in FIGS. 3-5, the finish ring
24 is circumferentially continuous and includes an annular
cylindrical wall 32 having one or more external threads or thread
segments 34. In the preferred embodiment illustrated in the
drawings, a circumferential bead 36 extends around the outer
surface of the wall 32 beneath the threads 34 for cooperating with
a tamper-indicating mechanism on a closure (not shown) to be
secured to the finish portion of the final container. A capping or
support flange 38 extends radially outwardly from the lower end of
the wall 32, giving the finish ring 24 a generally L-shaped lateral
cross section in the illustrated embodiments of the invention. As
best shown in FIG. 5, the finish ring 24 includes a cylindrical
internal surface 40 and a tapered internal surface 42 extending
between top and bottom ends 44, 46. Annular grooves 48 are provided
in the tapered internal surface 42, as will be further described in
reference to FIGS. 6A-8 below.
[0019] Referring now in general to FIGS. 6A-8, there is illustrated
a compression molding apparatus 50 for use in accordance with an
exemplary method of the present invention. In FIG. 6A, the
apparatus 50 includes a core pin 52 positioned above a compression
mold 54. The compression mold 54 includes a closed bottom end 56, a
body portion 58, and a partial finish portion 60 that together
define a mold cavity 62. The apparatus 50 occupies an open position
in FIG. 6A, in which a charge of preform material 64 is introduced
into the compression mold cavity 62 and the pre-made finish ring 24
is placed on to the compression core pin 52, as shown. The charge
64 is soft or molten, and thereby conforms to and fills the lower
end of the mold cavity 62. The core pin 52, with the finish ring 24
mounted thereto, and the mold 54 are positioned in vertical
alignment.
[0020] As shown in FIG. 6B, the core pin 52 and finish ring 24 are
then moved into the mold 54 to compression overmold the charge 64
partially within the finish ring 24. The term "overmold" is a term
of art and, as used herein, means to mold one component from a soft
or molten state to another component in a solid or finished state.
The molten preform material charge 64 flows in an upward or forward
direction between the core pin 52 and mold 54. As a result, the
preform 22 is formed including the closed bottom end 26, the body
28 and the neck 30. More significantly, however, the preform
assembly 20 is formed from the overmolding of the preform 22 to the
finish ring 24. Thereafter, and as shown in FIG. 7, the core pin 52
is retracted with the preform assembly 20, including the preform 22
and finish ring 24, mounted thereto.
[0021] As shown in FIG. 8, the preform assembly 20 includes the
preform 22 compression molded partially within a portion of the
finish ring 24. More specifically, the neck 30 of the preform 22
includes an upper portion 66 having annular projections 68 that
extend into the annular grooves 48 of the finish ring 24 so as to
positively radially interlock or interengage the finish ring 24 to
the preform 22. The annular grooves 48 in the finish ring 24 can
also be referred to as radial recesses or radial interengagement
features. The radial interengagement between the preform 22 and
finish ring 24 provides positive resistance to any axially applied
force tending to separate the components 22, 24. The preform 22
also includes a tapered or conical external surface 70 that
corresponds to the tapered or conical internal surface 42 of the
finish ring 24. The tapered internal surface 42 of the finish ring
24 is greater in diameter than the corresponding portion of the
core pin 52. Accordingly, a small gap 72 is provided between the
core pin 52, tapered internal surface 42 of the finish ring 24, and
a leading edge 74 of the preform 22. In terms of the preform
assembly 20, the gap 72 is provided between a transition point 76
of the finish ring 24 and the forward edge 74 of the preform 22,
wherein the transition point 76 is defined by the intersection of
the cylindrical or straight internal surface 40 and the tapered
internal surface 42. The gap 72 is intentionally provided to
accommodate within-tolerance variation of the size, volume or
weight of the molten preform charge. In other words, at least some
gap 72 should always be present under maximum material conditions
of both the preform 22 and the finish ring 24, to ensure a proper
fit therebetween without any distortion due to overpacking of the
preform material into the finish ring 24. The term "overpack" is a
term of art and, as used herein, refers to a condition where an
excessive amount of molten polymer is compression molded and tends
to lead to difficulties in ejecting the finished formed part or
parts from the compression molding apparatus. Overpacking also
tends to lead to warpage of, and residual stress within, the
finished part or parts.
[0022] With one or more of the embodiments described above, the
present invention provides a number of advantages. The present
invention facilitates production of preform assemblies and
container assemblies wherein a finish ring is composed of a
material different from that of a preform or container to which the
finish ring is radially interengaged. Likewise, the present
invention facilitates application of finish rings of various sizes
and/or materials, to a common size preform and/or container.
Moreover, the present invention enables a decrease in the cycle
time required to produce a preform because the constraint of the
process--forming the neck finish portion--can be subordinated to a
separate, parallel production process for producing just finish
rings. In the same vein, the present invention enables a reduction
in the piece price of each preform because the mold tooling can be
simplified, and reduced in cost, to omit the complex thread split
features typically required for the threaded finish portion of the
preform.
[0023] There have thus been described preform assemblies for blow
molding plastic container assemblies, plastic container assemblies
blow molded from such preform assemblies, and methods of making
such preform assemblies and container assemblies that fully satisfy
all of the objects and aims previously set forth. The present
invention has been disclosed in conjunction with presently
preferred embodiments thereof, and a number of modifications and
variations have been discussed. Other modifications and variations
will readily suggest themselves to persons of ordinary skill in the
art in view of the foregoing description. Indeed, the invention is
intended to embrace all modifications and variations as fall within
the spirit and broad scope of the appended claims.
* * * * *