Note: Descriptions are shown in the official language in which they were submitted.
3 ~5~8
This invention relates generally to hollow,
shaped articles and to methods and apparatus for shaping
such articles in one piece from a thermoplastic material
and, more specifically, to such artlcles having both
internal and external shapes along with methods and
apparatus for compression-blow moldiny such articles.
Blow molding of hollow shaped articles to be used
as dispensers of flowable materials is not new (U.S. Patent
No. 3,325,860). Compression molding of shapes, such as
threads, in the neck of a blow molded article is known
(U.S. Patent No. 3,311,950). It is also known to
compression mold separate members, such as closures, in the
same parison used for blow molding an article (U.S. Patent
No. 3,534,435). The shaping of a parison prior to blow
molding has been shown (U.S. Patent No. 3,294,885).
Containers assembled from blow molded and
compression molded parts, as well as from paper, foil and
metal parts, have been used for dispensing flowable
materials. The containers are normally shaped to have a
cylindrical body with a conically shaped nozzle on one end
and a plunger in the opposite end. The nozzle is ooened,
often bv cutting, and the flowahle mat~rial is pushed Ollt
of the container by the plunger.
Sealants, caulks and glues are frequently
dispensed from such containers. Such containers have many
advantages, particularly with respect to the regularity of
the size of the dispensed stream. Ho~ever, a major problem
with such dispensers has been the hardening of the
dispensed material in the nozzle between uses.
e
_
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For example, cne commercially available sealant
dispensing cartridge is formed from an extruded tube and an
injection molded nozzle. The tube and nozzle are connected
by spin welding. The user opens the conical nozzle by
cutting it to the desired diameter. The sealant is
squeezed out of the tube through the nozzle by operation of
the plunger.
When the sealant is an air or moisture curing
polymer, it can set up in the nozzle between uses due to
the air or water vapor which passes through the open end of
the nozzle and through the nozzle material. The nozzle
becomes plugged. The plug must be removed by digging or a
passageway must be punctured through it. Failing this, the
unused sealant in the tube is normally lost.
Similar situations occur with partially used
dispensers of glue or caulk.
An attempt to solve this problem has been to
provide a cap to cover the nozzle between uses. One
commercially available sealant dispenser is furnished with
a cap attached to the tube by a flexible connector.
Between uses, the open end of the nozzle can be covered
with the cap. Hardening of the sealant due to air or
moisture exposure at the open end of the nozzle is reduced.
However, hardening is not stopped because of the
permeability of the nozzle material and/or air or moisture
leakage through the joint.
Yet another response to this problem is a
commercially available sealant dispenser which comprises a
fiberfoil tubular body having a flat metal end crimped into
the fiberfoil. A two-piece injection molded nozzle is
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crimped into the metal end at its center. The injection
molded nozzle is conical in shape and has a female base
portion which is threaded to receive the male tip portion.
When the sealant sets u2 to form a plug in the male tip
portion, the tip is unscrewed from the base for easy
removal of the plug.
Such a dispenser has many advantages, but it is
expensive to manufacture. The several molding, forming and
assembling steps require a great deal of individual
handling, which can be both slow and expensive. The cost
of manufacturing such a dispenser can be prohibitive in a
highly competitive market.
It is an object of the invention to supply a
dispensiny cartridge which includes a nozzle portion
capable of being temporarily separated from the cartridge
and a plug portion which is capable of being substituted
for the nozzle portion.
It is also an object of the invention to make
such a cartridge by a method which is simpler and less
expensive than prior art methods.
These and other objects are accomplished bv a
method for making a hollow, shaped article ~rom a parison
of thermoplastïc material. According to the method, the
parison is positioned in the cavity of a mold which has a
closed end and an open end so that it is gripped near the
open end by a collar portion oE the mold.
An extendable blow pin means is extended into the
parison at the open end of the mold cavity, and the gripped
end of the parison is compressed between the colla~ and a
mandrel porti~n of the blow pin means. The opposite end of
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the parison is compressed by an extended portion of the blow pin
means. The parison conforms internally to the shape of the extended
portion of the blow pin means and externally to the shape of the
closed end of the nold cavity.
The parison is inflated by fluid pressure so that it assumes
the shape of the mold cavity. After cooling, the article is ejected
from the mold. The ejected article has an open end and a
substantially closed end. The substantially closed end has internal
and external compression molded shapes which correspond to the shape
of the extended portion of the extendable blow pin means and to the
shape of the closed end of the mold cavity.
The apparatus for performing this method includes, generally
speaking, a mold for receiving the plastic parison. The mold has a
cavity with a closed end and an open end. The closed end of the
cavity is shaped for forming one end of the outside of the parison.
The apparatus further includes an axially movable blow pin
means which has a mandrel portion and an extendable portion. The
blow pin means is adapted for supplying fluid pressure to the inside
of the parison.
A means for axially moving the blow pin means into the
parison is also provided. The blow pin means is movable in such a
way that the gripped end of the parison is compressed between the
collar of the open end of the mold cavity and the mandrel portion of
the blow pin means. Movemènt of the blow pin means also results in
the opposite end of the parison being compressed by the extended
portion of the blow pin means, causing the parison to conform to
the shape of the extended portion on the inside and to the shape of
the closed end of the mold cavity on the outside.
~eans for providing fluid pressure through the blow pin
means sufficient to cause the parison to assume the shape of the
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cavity and means for ejecting the shaped article from the mold
are also included. The apparatus may also include means for
cooling the parison prior to ejecting the article.
The invention includes a hollow shaped article which is
formed in one piece so as to have a substantially closed end and
an open end with shapes formed both inside and outside the
article at the closed end.
The invention is described below with reference to the
accompanying drawings wherein:
FIG. 1 shows schematically and in cross-section a
hollow shaped article according to the present invention wherein
the shape is suitable for use as a dispensing cartridge.
FIG. 2 shows schematically and in cross-section a
portion of an article similar to the article in FIG. 1 ready for
use as a dispensing cartridge.
FIG. 3 shows in perspective view an apparatus for
extruding a parison.
FIG. 4 shows schematically and in cross-section an
extruded parison placed in a mold in preparation for compression
blow molding.
FIG. 5 shows schematically and in cross-section a
detail of the mandrel portion of a blow pin assembly positioned
to close the open end of a mold cavity.
FIG. 6 shows schematically and in cross-section an
extended blow pin assembly positioned for compressing internal
and external shapes in the closed end of the article.
FIG. 7 shows schematically and in cross-section an
alternative embodiment of an apparatus according to the present
invention.
FIGS. 8a and 8b show schematically and in cross-section
mold arrangements for injection-blow molding an article
according to the present invention.
FIG. 9 shows schematically and in cross-section a mold
arrangement for injection molding an article according to the
present invention.
FIG. 10 shows schematically and in cross-section a
hollow shaped article according to tne present invention which
is useful as a dispensing cartridge and which includes an
externally threaded portion suitable for plugging the internally
threaded portion.
FIG. 11 shows schematically and in cross-section an
assembly for forming the article of FIG. 10.
Referring more specifically to FlG. 1, there is shown a
hollow shaped article 1 formed in one piece and having an open
end 2 and a closed end 3. External threads 4 and internal
threads S are compression molded on closed end 3. Threads 4 and
5 are sized to be matable. Article 1 also includes a thin
walled break-away portion 6 between internal threads 5 and
external threads 4. External threads 4 disposed on a hollow tip
7 can be used to form a nozzle (such as nozzle 9 in the
embodiment of FIG. 2).
Thin walled breakaway portion 6 is formed so that tip 7
can be easily broken away from cartridge 1 and threaded into it.
Any easily broken connecting piece can be used in this preferred
embodiment as long as it can be formed as a part of the one
piece article. For example, it is within the contemplated scope
of the invention that thin walled portion 6 be omitted and that
hollow tip 7 be connected to cartridge 1 by an easily broken
connecting strip, or by flashing. In such an embodiment, the
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hollow shaped article would have a substantially closed end even
though portion 6 is not present.
Article 1 can be made from any useful material.
Suitable materials are normally thermoplastics capable of being
blow molded or injection molded into useful shapes. That is,
the material should be plastic during shaping and relative
inflexible afterward. T~pical of such materials are glass,
polyvinylidene chloride, nylon, polyethylene glycol
terephthalate, polyethylene, polypropylene, poly-l-butene,
poly-4-methylpentene-1, vinyl chloride, styrene polymers and
copolymers and mixtures thereof.
Polyethylene and polypropylene are preferred because of
their commercial availability. Good results have been obtained
using Dylan~ polyethylene pellets and Dypro~ polypropylene
pellets, both available from and trademarked by ARCO Polymers
Inc. (Philadelphia, PA 13101).
Article 1 may have any useful shape. The exemplary
shape shown in FIG. 1 is useful for being made into a dispensing
cartridge.
Referring more specifically to FIG. 2, there is shown a
dispensing cartridge 8 made from an article similac to article 1
of FIG. 1.
Cartridge 8 includes a nozzle portion 9 which is
threaded into cartridge body 10. Cartridge 8 is first formed in
a shape similar to article 1 of FIG. 1 and nozzle 9 subsequently
has been broken away from body 10 and threaded into it.
Nozzle 9 is shaped so that its outside diameter is
graduated at shoulders 11. The graduations are a convenient
guide for cutting the nozzle so as to expose a selected inside
diameter.
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Rupturable seal 12 is an optional, preferred feature.
Seal 12 is positioned so as to separate nozzle portion 9 and the
interior of the rest of cartridge 8. Seal 12 is normally formed
from a metal foil or the like.
The main part of cartrid~e 8 is filled with a flowable
material 13 to be dispensed. ~aterial 13 can be any flowable
material. Typically it is caulk, glue, sealant or the like.
When used, nozzle portion 9 is cut to provide a
dispensing orifice of the desired diameter. Seal 12, if
present, is ruptured to allow material 13 to be squeezed through
nozzle portion 9 and applied. Material 13 is normally squeezed
from cartridge 8 by a plunger (not shown).
Between uses, material 13 remaining in nozzle portion 9
may become hard and form a plug. The plug is cleared by
separating nozzle portion 9 from body 10, removing the plug and
reconnecting nozzle portion 9 to body 10.
Cartridge 8 may, optionally, have a thread shape 16
compression molded on its open end. Thread shape 16 may be
useful in mounting cartridge 8 in a holder when it is used for
dispensing material 13.
Referring more specifically now to FIGS. 3-9, methods
and apparatus for making a hollow shaped article according to
the present invention are described.
FIG. 3 shows an extrusion blow molding head 17 which
forms a plastic parison 18 by extrusion of a material such as
polyethylene. The parison is tubular in shape, relatively thick
walled and heated sufficiently to be plastic.
Sectional mold 19 is shown in an open position. It is
adapted for being moved to a position so that it can be closed
original position. Such an extruder-mold combination is known
18
in the art as an extrusion-blow molding assembly. Such
assemblies are co.nmercially available and can be used as a
component of an apparatus according to the present invention.
: Extendable blow pin assembly drive means 20 is
- positioned to be above the open end of the cavity of mold 19
after mold 19 has received parison 18. The compression-blow
molding operation is accomplished by means 20 as described in
FIG. 4-6.
FIG. 4 shows mold 19 which has been closed around
parison 18. Mold 19 has a closed end 21 and an open end 22.
Parison 18 is gripped near the open end of the mold by collar
portion 23.
As is well known in the extrusion-blow molding art, a
stream of air pressure is normally applied centrally to the
parison through suitable ports in the center of the extrusion
die (not shown). The air pressure causes parison 18 to flare
slightly when mold 19 is closed. The flaring causes parison 18
to fit collar 23. Parison 18 is normally separated from the
extruder by first drawing a hot wire, or the like, (not shown)
through it and then moving mold 19 laterally so that parison 18
is positioned under the blow pin asselnbly as shown in FIG. 5.
FIG. 5 shows extendable blow pin assembly 24 as it is
inserted into parison 18 at the open end 22 o~ mold 19.
Assembly 24 compresses the gripped end of parison 18 between
itself and collar 23.
Extended blow pin assembly 24 comprises a mandrel
portion 25 and an extendable shaped portion 26. Shaped portion
26 includes ports 27 which are suitab].e for supplying fluid
pressure (such as air pressure) for inflating parison 18.
. 9
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FIG. 6 sho~s assembly 24 after mandrel 25 has been
seated in collar 23 and shaped portion 26 has been extended by
drive means 20. Shaped portion 26 compresses a portion of
parison 18 between itself and closed end 21 of mold 19.
Compressing force supplied by drlve means 20 causes parison 18
to take on an internal shape corresponding .o the for~ of shaped
portion 26 of assembly 24 and an external shape corresponding to
the shape of closed end 21 of mold 19.
In the exemplary embodiment of FIG. 6, the shapes
impressed in parison 18 are threads sized to be matable.
Parison 18 is inflated to conform to the shape of the
cavity in mold 19. Inflation is accomplished by the
introduction of fluid pressure into parison 18 through ports 27
in shaped portion 26.
Means 20 includes hydraulic cylinder 30 which is
activated to lower assembly 24 until mandrel 25 is seated in
collar 23. Cylinder 31 is then hydraulically activatec. to move
shaped portion 26 so that it applies a compressive force to
parison 18 which is held between staped portion 26 and closed
end 21 of the mold 19. In the exemplary embodiment of FIG. 6,
shaped portion 26 extends concentrically through mandrel portion
25.
After the parison has been blown to shape by fluid
pressure through ports 27, the parison is cooled so that the
thermoplastic material will set into shape. It can be allowed
to cool by the conduction of heat through the mold. However, in
order to speed setting, the mold and parison are normally cooled
by the passage of a cold liquid, such as water, through cooling
jacket 32.
~563~18
After parison 18 has cooled, shaped portion 26 is
retracted and mandrel portion 25 is withdrawn. Shaped portion
26 of the exemplary embodinent of FIG. 6 is desirably removed
without substantially disrupting the thread shapes formed on the
inside of parison 18.
This is accomplished by rotating portion 26 so that it
unscrews from the threads it has formed. Rotation of portion 26
is accomplished by the operation of hydraulic motor 35 which
rotates wheel 36. Teeth on wheel 36 fit cogs 37 on idler wheel
38. As wheel 38 rotates, tabs 39 on wheel 38 rotate against
tabs 40 on flange 41. Flange 41 is connected to portion 26.
As portion 26 is rotated, it unscrews from the threads
it has formed. The unthreading action moves portion 26 in a
retracting direction until portion 26 clears the threads. The
lengths of tabs 40 and 39 can be selected so that they disengage
at about the same time portion 26 clears the threads. Hydraulic
pressure to cylinder 31 is normally reduced during the
unthreading operation in order to ease movement of portion 26.
The retained air pressure in the article exerts a pressure on
member 26 to aid in moving it in a disengaging direction.
Cylinders 30 and 31 can then be operated to retract
shaped portion 26 and, mandrel portion 25 prior to operating
clamps 28 and ejecting a hollow shaped article such as article 1
of FIG. 1. It is to be understood that whenever shaped portion
26 forms other shapes in parison 18, the rotating prior to
withdrawal may not be necessary or desirable.
FIG. 7 shows an alternative embodiment of an apparatus
according to the present invention. I~old 42 grips parison 43 at
a collar portion of the mold and mandrel 45 compresses the
gripped portion of parison 43 between the collar and itself so
S~:18
that pattern 46 in the collar portion is compressed into the
gripped portion of parison 43.
Mandrel 45 is a flared portion of extendable blow pin
means 47. A shaped portion 48 of extendable blow pin means 47
compresses a portion of parison 43 against closed end 49 of mold
42.
In the exemplary embodiment of FIG. 7, shaped portion
48 impresses a roughened pattern in parison 43 on the inside of
its closed end. The outside of the closed end of the parison
assumes the shape of closed end 49 of mold 42.
Movement of the extendable blow pin .neans into the mold
is accomplished by the operation of cylinder 50.
Fluid pressure (such as air pressure) to inflate
parison 43 is supplied through tube 53 and a channel (not shown)
which opens at ports 54 on means 47.
In operation, parison 43 is gripped in mold 42 much as
parison 18 is gripped in mold 19 of FIG. 5. Cylinder 50 moves
means 47 into the parison while fluid pressure is supplied
through tube 53 and ports 54. As mandrel 45 and end portion 48
; 20 seat against parison 43, the fluid pressure inflates the parison
so that it assumes the shape of the cavity Oe mold 42. Pressure
from cylinder 50 compresses the shapes at shaped end 48 and at
46 into the parison. After the blow molded shape is allowed to
cool and is no longer plastic, means 47 is retracted and clamps
55 are released to eject the article from the mold.
FIGS. 8a and 8b show that an article according to the
present invention can be made by well known injection~blow
molding techniques.
Mandrel 56 is placed in the cavity of injection mold
30 57. Injection mold 57 is securely fastened with clamps 58.
1~5~ 8
Mandrel 56 is connected to a fluid pressure source (not shown)
through flexible connector 59. Channels (not shown) in mandrel
56 connect flexible connector 59 with valved ports 60.
Injection mold 57 is connected to a supply of
thermoplastic material under pressure (not shown) b~- connector
61.
Plastic material under pressure is injected into the
cavity between injection mold 57 and mandrel ~6 to form parison
62 and injection molded shape 63 at one end of parison 62.
Shape 63 is formed when the plastic material is injected between
shaped portion 66 of the inside of mold 57 and shaped portion 67
of mandrel 56. In the embodiment of FIGS. 8a and 8b, shape 63
comprises matable male and female threads with a thin walled
breakaway portion therebetween.
After parison 62 and shape 63 are formed, clamps 58 are
released. Mandrel 56, holding the parison, is transferred to
blow mold 64. Blow mold 64 has a shaped tip portion 65 which is
substantially identical in shape to shaped portion 66 of
injection mold 57. Shape 63 fits between shaped tip portion 65
of blow mold 64 and shaped tip portion 67 of mandrel 56.
Mold 64 is sealed with clamps 68 and fluid pressure is
provided through flexible connector 59 and valved ports 60. The
fluid pressure inflates parison 62. Parison 62 is cooled b~ the
action of cooling veins 76 to form a shaped article. The shaped
article is formed in one piece naving a closed end and an open
end with shapes formed both inside and outside the article at
the closed end.
FIG. 9 shows that an article according to the present
invention can be formed by well known injection molding
techniques.
115C~
Mandrel 70 is 2ositioned inside mold 71 so that there
is a cavity therebetween. ~old 71 and mandrel 70 are shaped at
one end so that the cavity defines a hollow tip section 72 with
matable male and female threads.
Mold 71 is connected by connector means 73 to a source
(not shown) of plastic material under pressure. The plastic
material is injected into the cavity between mold 71 and mandrel
70 to take on the shape of the cavity.
After injection and cooling, mold 71 is opened by
releasing clamps 74 to expose mandrel 70 covered with article
75. Article 75 can be unscrewed from mandrel 70. The unscrewing
action removes article 75 from the thread shapes on mandrel 70
without stripping the corresponding thread shapes in the
article. Article 75 is formed in one piece and has an open end
and a closed end with shapes formed both on the inside and
outside of the closed end.
Referring more specifically to FIG. 10, there is shown
a portion of a hollow shaped article 80 formed in one piece.
Article 80 has an open end (not silown) such as end 2 of FIG. 1.
The closed end of article 80 is shown in FIG. 10.
The closed end includes internal threads 81 and
external threads 82. External threads 82 are disposed on hollow
tip 83. The internal and external threads are shaped to be
matable.
The closed end further includes a plug 84 connected to
hollow tip 83. Plug 84 has external threads 85 which are shaped
to be matable with internal threads 81.
Article 80 is useful as a dispensing cartridge. ~ollow
tip 83 can be separated from body 86 and reattached by screwing
external threads 82 into internal threads 81. ~hen plug 84 is
separated ~rom hollow tip 83, the article is useful as a
dispensing cartridge in a ~nanner similar to that described in
connection with cartridge 8 of FIG. 2.
The material to be dispensed may become hard and form a
plug in hollow tip 83 during long periods between uses. In the
embodiment of FIG. 10, this problem can be avoided by removing
hollow tip 83 and screwing in plug 84. Hollow tip 83 may then
be kept clear until subsequent use.
Referring more specifically to FIG . 11, there is shown
a portion of an assembly for making article 80 of FIG. 10.
Article 80 can be made using an apparatus and method similar to
those described in connection with FIGS . 4-6 .
Parison 87 is placed in sectional mold 88 and held in
position between the mold collar (not shown) and the mandrel
portion (not shown) of an extendable blow pin means. Extendable
portion 39 of the extendable blow pin means is moved to compress
parison 87 at the closed end of mold 88.
The closed end 90 of mold 88 is adapted to shape
parison 87 into a plug, such as plug 8~ of FIG. 10. The
mechanism oE Eilling closed end 90 wlth parison 87 so that it
assumes the shape oE the end 90 is not critical to the invention
and may vary from apparatus to apparatus de,oending on the shape
of the article.
For example, the plug may be blow molded by fluid
pressure supplied through ports (not shown) in the end of
portion 89. The plug could also be blow molded by the
compressive force of ambient gas which is pushed ahead of
portion 89 as it enters a narrow portion of mold 88, such as
portion 91. Alternatively, the plug could be solid and rormed
3 ~S~
by compressive force as the parison is pushed into end 90 by
portion 89.
The present invention has been disclosed in the above
teachings and drawings with sufficient clarity and conciseness
to enable one skilled in the art to make and use the invention,
to know the best mode for carrying out the invention and to
distinguish it from other inventions and from what is old. Many
variations and obvious adaptations of the inventions will
readily come to mind, and these are intended to be contained
within the scope of the invention as claimed below.
16
