U.S. patent application number 09/813739 was filed with the patent office on 2001-07-26 for thermoplastic containers manufactured by extrusion blow molding apparatus.
Invention is credited to Atkins, William P., Czesak, Theodore M., Krall, Thomas J..
Application Number | 20010009242 09/813739 |
Document ID | / |
Family ID | 23106207 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009242 |
Kind Code |
A1 |
Czesak, Theodore M. ; et
al. |
July 26, 2001 |
Thermoplastic containers manufactured by extrusion blow molding
apparatus
Abstract
Extrusion blow molding apparatus (10) having a blow mold (12), a
neck mold (14) positioned above the blow mold and an anvil (30)
positioned in an outwardly facing cavity (32) of the neck mold. A
container (C) is produced in the molding apparatus from a parison
of a heated thermoplastic material by introducing pressurized
blowing fluid into the container being formed by way of a blow pin
assembly (16) that is reciprocable relative to the blow mold. The
blow pin assembly has an inner tubular member (20) with a free end
that is within the container during blowing, and an outer tubular
member (22) that surrounds the inner tubular member and defines an
annulus therewith for withdrawing spent blowing fluid from the
container. The outer tubular member has radial ports (24) for
directing spent blowing fluid against a moil (M) being formed at a
rim (R) of a finish (F) of the container. A restricted outlet from
the finish of the container is obtained by providing the anvil with
an inwardly and downwardly directed nose portion (34) to form a
restricted annular portion (P) in the finish at a location below
the rim.
Inventors: |
Czesak, Theodore M.;
(Perrysburg, OH) ; Krall, Thomas J.; (Toledo,
OH) ; Atkins, William P.; (Merriam, KS) |
Correspondence
Address: |
H. G. Bruss
Owens-Illinois
One SeaGate, 25-LDP
Toledo
OH
43666
US
|
Family ID: |
23106207 |
Appl. No.: |
09/813739 |
Filed: |
March 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09813739 |
Mar 21, 2001 |
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09288208 |
Apr 8, 1999 |
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6213756 |
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Current U.S.
Class: |
215/44 |
Current CPC
Class: |
B29C 49/50 20130101;
B29C 49/76 20130101; B29C 49/4236 20130101; Y10S 425/806 20130101;
B29C 49/58 20130101; B29C 49/04 20130101 |
Class at
Publication: |
215/44 |
International
Class: |
B65B 007/28 |
Claims
What is claimed is:
1. A container having a body portion and a finish portion formed
integrally with said body portion, said container being formed from
an extruded parison of a thermoplastic material in blow molding
apparatus in which said body portion is formed from a portion of
the parison in a blow mold of the blow mold apparatus and the
finish is formed from another portion of the parison in a neck
mold, said finish portion having an annular partition extending
across said finish portion at a location positioned within said
finish portion at an elevation below a rim of said finish portion,
said annular partition having an internal diameter that is
substantially smaller than any other internal diameter of said
finish portion
2. A container according to claim 1 in which said blow molding
apparatus is apparatus of the extrusion blow molding type.
3. A container according to claim 2 in which the container is
produced from a melt of polypropylene or high density
polyethylene.
4. A container according to claim 1 wherein the internal diameter
of said annular partition is the "C" dimension of the finish
portion of the container.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a division of co-pending U.S. patent
application Ser. No. 09/288,208, which was filed on Apr. 18,
1999.
FIELD OF THE INVENTION
[0002] This invention relates to an improved container manufactured
by the extrusion blow molding process, a process that is
occasionally referred to as the "shuttle" blow molding process.
More particularly, this invention relates to a container of the
foregoing character with an integral restricted outlet.
BACKGROUND OF THE INVENTION
[0003] In the manufacture of thermoplastic containers by the
shuttle blow molding process, the threaded or otherwise configured
closure receiving neck portion of the container, which is commonly
referred to as the "finish" of the container, is formed by a neck
mold that is positioned against an outermost end surface of a body
mold cavity in which the body portion of the container is blown
from a previously extruded form or parison of the container. The
blowing of the container is done by air or another gas that is
introduced into the parison within the mold cavity by a blow pin
that extends through the neck mold into the parison within the body
mold. The blow pin reciprocates with respect to the neck mold and
body mold, and an anvil of a hard material is positioned within an
open-ended cavity on the outermost surface of the neck mold to
prevent impact damage to the neck mold as the blow pin reciprocates
with respect to the neck mold.
[0004] In the manufacture of thermoplastic containers by the
extrusion blow molding process, heretofore it has been very
difficult to produce a container with a smaller internal control
diameter at or near the top of its finish, the "C" dimension in
industry nomenclature, than the minimum internal diameter at or
near the bottom of the finish, the "I" diameter in industry
nomenclature. However, for proper dispensing of the packaged
product, when the packaged product is a liquid, it is often
important that the size of the opening at the "C" dimension be
substantially smaller than the "I" dimension. Heretofore, this has
usually been accomplished by inserting a separate annular fitment
in the outlet of the container finish. This added element, and the
assembly step involved in its insertion in a container, however,
add to the expense involved in the manufacture of restricted outlet
liquid containers by the extrusion blow molding process.
[0005] Another problem encountered in the manufacture of
thermoplastic containers by the extrusion blow molding process,
according to prior art techniques, relates to dimensional
variations in the rims of such containers resulting from the time
required to properly cool the portion of the container to be
removed from the rim, often called a "moil," at the conclusion of
the blow molding process.
[0006] Another problem encountered in the manufacture of
thermoplastic containers by the extrusion blow molding process,
according to prior art techniques, relates to the removal of the
moils from the containers at the conclusion of the molding process,
especially containers produced with a restricted outlet.
Heretofore, stripper plates, which are conventionally used to
remove moils from other types of extrusion blow molded containers,
were not effective in removing moils from restricted outlet
containers of such type, and such moils often disengaged from the
containers in an uncontrolled manner upon impact of the containers
with a removal conveyor.
BRIEF DESCRIPTION OF THE INVENTION
[0007] The aforesaid and other problems heretofore associated with
the manufacture of containers by the extrusion blow molding process
are solved by the apparatus of the present invention in which the
container is provided with a "C" dimension that is substantially
smaller than its "I" dimension, to eliminate the need for inserting
a separate fitment into the container to be able to properly
control the rate of flow of liquid from the container, and this is
done by providing the anvil used in such process with an annular,
transversely extending partition at an elevation that will occur
within the finish of the container, near but below the rim of the
container. Such anvil partition will then serve to mold a
restricted diameter annular partition within the container neck in
addition to performing its historical function of preventing neck
damage to the adjacent neck mold of the apparatus, and the
restricted diameter annular partition thereby formed within the
container finish will be an integral part of a single piece
container and finish.
[0008] The extrusion blow molding apparatus of the present
invention also provides containers with more precisely defined
finishes by the use of a blow pin assembly that exhausts spent
cooling air in an annulus that surrounds a cooling air inlet tube,
and the exhausted spent cooling air is exhausted from the annulus
of the blow pin assembly against the moil portion of the container
being molded, that is, the annular portion of the container that
projects outwardly from the rim at the finish of the container,
such moil portion normally being trimmed from the container during
or after its discharge from the mold. This spent cooling air
discharge technique serves to accelerate the cooling of the moil,
and to a lesser extent the cooling of the finish itself, and this
acceleration of the cooling rates in the region of the finish of
the container will help to reduce the distortion of the container
finish that occurs when finish cooling occurs more slowly.
[0009] The extrusion blow molding apparatus of the present
invention also provides for the stripping, or removal, of the moil
section of a blow molded container with a restricted outlet before
the container is removed from the mold, and therefore before the
container is impacted against a removable conveyer, an action that
heretofore was not consistently possible. According to the present
invention, at the conclusion of the molding cycle the mold opens
and the blow pin assembly is retracted relative to the mold. The
shoulder of a tube of the blow pin assembly is stopped by a pair of
tube drop rods, and the stem of the blow pin assembly continues to
rise. The moil of the container, now detached or partly detached
from the container finish because it engages the exterior of the
blow pin assembly, is held up by a stripper doughnut insert. The
stem of the blow pin assembly continues to rise through the
stripper doughnut insert, which causes the moil to disengage from
the blow pin assembly and fall to a conveyer below the mold.
[0010] Accordingly, it is an object of the present invention to
provide an improved thermoplastic container. More particularly, it
is the object of the present invention to provide an improved
container with a restricted outlet.
[0011] For a further understanding of the present invention and the
objects thereof, attention is directed to the drawing and the
following brief description thereof, to the detailed description of
the preferred embodiment and to the appended claims.
BRIEF DESCRIPTION OF THE DRAWING
[0012] FIG. 1 is a fragmentary elevational view, partly in
cross-section, of apparatus for blow molding a container according
to the preferred embodiment of the present invention from a
thermoplastic material according to the extrusion blow molding
process;
[0013] FIG. 2 is a fragmentary view, at an enlarged scale, of a
portion of the apparatus shown in FIG. 1;
[0014] FIG. 3 is a fragmentary elevational view, at a reduced
scale, of a portion of the apparatus of FIGS. 1 and 2 showing a
step in the extrusion blow molding process occurring after the step
illustrated in FIGS. 1 and 2;
[0015] FIG. 4 is a view similar to FIG. 3 showing a subsequent step
in the manufacture of containers according to the preferred
embodiment of the present invention;
[0016] FIG. 5 is a view similar to FIGS. 3 and 4 showing another
subsequent step in the manufacture of containers according to the
extrusion blow molding process of the present invention; and
[0017] FIG. 6 is a perspective view showing a detail of the
apparatus of FIGS. I and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] A container C according to the present invention is shown in
FIGS. 1 and 2 being molded in blow molding apparatus according to
the present invention, such apparatus being generally identified by
reference numeral 10. As shown in FIGS. 1 and 2, the blow molding
apparatus 10 is made up of a blow mold 12 in which a body portion
of the container C is formed by blowing, and a neck mold 14 in
which a threaded or otherwise configured closure receiving finish
portion F of the container C is formed. In that regard, the blow
mold 12 is made up of opposed, semi-cylindrical mold halves, which,
when joined end-to-end, define a cavity corresponding in
configuration to the exterior of the body portion of the container
C; likewise, the neck mold 14 is made up of an opposed, like pair
of mold halves which, when joined end-to-end, define a cavity whose
configuration corresponds to the exterior of the finish F of the
container C.
[0019] In the manufacture of containers by an extrusion blow
molding process, in which the blow molding apparatus 10 is adapted
to be used, containers are produced from extruded forms, often
called parisons, which are produced elsewhere in an extrusion blow
molding machine and are then transferred to a blow molding station
for blowing into containers. In any event, the containers C are
blown from extruded parisons that are extruded from a melt of a
thermoplastic material, such as polypropylene or high density
polyethylene, as is known in the art, and the blow molding process
occurs while such thermoplastic material is at an elevated
temperature.
[0020] The container C is blown in the blow molding apparatus by
blowing air or other gaseous medium that is introduced in the
container C while the container C is in the blow mold 12 of the
blow molding apparatus 10 by air that is introduced through a blow
pin assembly, which is generally indicated by reference numeral 16.
The blow pin assembly 16, which is reciprocable relative to the
blow mold 12, receives blowing air through an inlet line 18, and
the blowing air, which is cooler than the parison to be blown into
the container C, passes from the air inlet line 18 into the
interior of the parison to be blown into a container in the blow
mold 12 through an air introduction tube 20. Spent blowing air from
the container being blown in the blow mold 12 is withdrawn
therefrom in an annulus that is defined by the exterior of the air
introduction tube 20 and the interior of an annular tube 22, whose
free end terminates within a container C short of the termination
of a free end of the air introduction tube 20. Radial exhaust ports
24 are formed in the annular tube 22 at the location of an annular
moil portion M that is formed at a rim R of the annular finish
portion F of the container C, and spent blowing air from the
annular tube 22, which is still cooler than the moil M of the
container C, is directed against the moil M through the exhaust
ports 24 and through radially aligned ports 26 in an annular member
28 that supports an exterior free end portion of the annular tube
22. This cooling of the moil M, which results in cooling of the
finish F to a lesser extent, results in less thermal distortion of
the finish F than would otherwise occur in an arrangement where
cooling proceeded more slowly, and results in a more precisely
defined finish F because of such accelerated cooling.
[0021] Because of the reciprocation of the blow pin assembly
relative to the blow mold 12, as heretofore described, impact loads
would be borne by the neck mold 14, but for the presence of an
anvil 30 of a hard material that is made up of opposed,
semi-cylindrical elements joined end-to-end to form an annular
opening. The anvil 30 is placed against the exterior of the neck
mold 14, specifically, in an open cavity 32 thereof. In the present
case, the anvil 30 has an inwardly and downwardly projecting nose
portion 34 that projects into the finish F of the container C to
form, with the exterior of the blow pin assembly 16, a transversely
extending annular partition P integrally with the container C and
at a location slightly below the rim of the finish F. The inside
diameter of the partition P, then, becomes the "C" dimension of the
container finish F, and the "C" dimension can be substantially
smaller than the "I" dimension of the finish F, which will occur
near the juncture of the finish F and a shoulder portion S of the
container C. With such a restricted "C" dimension, it becomes
unnecessary to insert a separate fitment into the outlet of the
finish F to reduce the rate at which liquid or other product
packaged in the container C can be withdrawn therefrom.
[0022] At the conclusion of the molding of the container C in the
blow molding apparatus 10, the neck mold 14, with the anvil 30, is
removed form the blow molding apparatus 10, and the blow pin
assembly 16 begins to be retracted from the blow molding apparatus
10 relative to the blow mold 12 and to fixed support structure 36.
This has the effect of lifting the container C out of the blow mold
12 by virtue of bonding between the blow pin assembly 16 and the
thermoplastic material in the container C, and specifically between
the blow pin assembly 16 and the thermoplastic material in the moil
M of the container C. This motion continues until the shoulder S of
the container C engages the free ends of a pair of downwardly
depending drop rods 38 that depend from a donut insert 42 of
stripper plate 40, which is releasably secured to the support
structure 36, the releasable connection between the donut insert 42
and the support structure 36 permitting the substitution of a
different donut insert 42, with drop rods 38 that depend a
different distance therefrom, as required to process containers C
of a different configuration. This is the condition depicted in
FIG. 3.
[0023] As is shown in FIG. 4, the blow pin assembly 16 continues to
be withdrawn relative to the blow mold 12 and relative to the
support structure 36. However, the container C is no longer free to
move relative to the blow mold 12 because of the engagement of the
shoulder S of the container C by the drop rods 38. Nevertheless,
the continued retraction of the blow pin assembly 16 will cause the
moil M of the container C to separate from the finish F of the
container C because of the bonding of the interior of the moil M to
the exterior of the blow pin assembly 16, and the moil M will
thereby be separated from the container C before the container C is
withdrawn from the mold 12. The moil M can then be disposed of at a
location away from the mold 12, and no separate moil removal step
need be performed on the container C after its removal from the
mold 12, the removal of the moil M from the blow pin assembly 16
being shown in FIG. 5.
[0024] Although the best mode contemplated by the inventor for
carrying out the present invention as of the effective filing date
hereof has been shown and described herein, it will be apparent to
those skilled in the art that suitable modificafions, variations
and equivalents may be made without departing from the scope of the
invention, such scope being limited solely by the terms of the
following claims and the legal equivalents thereof.
* * * * *