Note: Descriptions are shown in the official language in which they were submitted.
2~29~7
~ETHOD FOR INJE:C~!ION ~IOI~ llG
BacX~round o~ the In~entio~
This invention generally pertains to methods of
injection molding. More specifically, the present
invention relates to a method ~or injection molding which
employs fluids of different viscosities.
The invention is particularly app~icable to a method
by which a relatively viscous fluid, such as a molten
thermoplastic, is molded into a particular product with the
aid of a relatively non viscous fluid, such as a gas,
during an injection molding process known as gas assisted
injection molding. However, it will be appreciated to
those skilled in the art that the invention has broader
applications and may also be adapted for use in other
injection molding environments where both a relatively
viscous fluid, such as a plastic or wax, and a relatively
non-viscous fluid, such as a gas, steam or a liquid, are
injected into a mold cavity.
Gas assisted injection molding processes are
becoming wid~ly known in the art. Such processes employ
the step of injecting a plasticized (melted) ~hermoplastic
material under high pressure, in the range of 2,000 p.s.i.
injection pressure, into a finite mold space to a volume
less than lOOS of the ~old space. Either simultaneously
therewith or shortly thereafter a relatively non-viscous
fluid, such as an inert gas, is injected into the
~25 plasticized material in order to fill the remainder of the
volume in the mold cavity. The gas which enters the
plasticized material moves along the paths of least
resistance therein. Such paths are normally in areas where
the thermoplastic body is the thickest and has slower
cooling sections. In this way, with a suitably designed
part, one or more hollowed out sections can be provided in
3 , 2~2947
the part. The matsrial is displaced by the gas ~rom the
middle of th~se sectic,ns and moves out to fill the
remainder of the mold space. In this way, the plastic
material remains held against the ~mold surfaces during
hardening and sink takes place intlernally, rath~r t~an on
the exterior surfaces o~ the part. Sinca the pressur~ used
for final filling of the part is c3nfined to an area
defined by the gas channel or cavity, the resultant force
against the sections of the ~old is relatively modest so
that lower clamping forces on the mold are adequate.
The added equipment and process control mechanisms
necessary to implement gas assisted injection molding
contributes significantly to the cost and complexity of
this type of molding process. The circuits needed to
charge, inject and vent the pressurized gas at spPcific
times and at desired pressures are quite complex and the
methods for utilizing such apparatus have not at ~his point
been optimized. Another problem with conventional
injection molding processes in general is the venting of
the gas ~rom the gas cavity formed in the molded part. A
further problem is that the time required to cool the
molded product is substantial in relation to the time that
the injection molding process itself takes. Thus,
producing a quantity of such products is a time-consuming
process.
Accordingly, it has been considered desirable to
develop a new and ~mproved injection molding process which
would overcome the foregoing difficulties and others while
providing better and more advantageous overall results.
Brief Summary of the Invention
In accordance with the present invention, a new and
improved process for producing an injection molded product
is provided.
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More particularly in accordance with this aspect of
the invention, the process comprises introduci~g ~n a~ount
of a molten thermoplastic material sufficient for the
prepara~ion of the injec~ion moldedl product i~o a mold
cavity. A quantity of heated fluicl is introduced into the
molten thermoplastic in the mold cavity thereby forming a
fluid cavity in the molten thermoplastic. The heated fluid
is then vented from the fluid cavit;y and a cooling ~luid is
introduced into the fluid cavity. The injection mold~d
product is thereupon cooled and th~ cooling fluid is
subsequently vented ~rom the ~luid cavity.
In accordance with another aspect of the invention,
a process is provided for producing an injection molded
product.
More particularly in accordance wi~h this aspect of
the invention, the process comprises the step of
introducing a stream o~ a molten thermoplastic material at
a first, injection, pressure into a mold cavity and
introducing a heated gas at a second pressure which is at
least as high as the first pressur~ into the molten stream
of thermoplastic material. A gas cavity is thereby formed
in the thermoplastic material. The heated gas is ve~ted
from the gas cavity and a cooling ga~ is introduced into
the gas cavity. The cooling gas is held at a third
pressure which is high2r than the second pressure. The
injection molded product is cooled and ~he cooling gas is
then vented from the gas cavity.
In accordance with still another aspect of the
invention, a procass for fluid assisted injection molding
for producing an injection molded product is provid~d.
More particularly in accordance with this aspect of
the invention, the process comprises the step of
introducing a molten strea~ of a thermoplastic material at
a first, injection, pressure into a mold cavity. A heated
gas is then introduced at a second pressure into the molten
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stream of thermoplastic material thereby forming a gas
cavity in the thermoplastic material. The second pressure
is at least as high as the first pressure. The heated gas
is thereupon vented from the gas cavity and a cooling gas
is circulated through the gas cavity. The injection msldad
product is cooled and it is subsequently removed from the
mold cavity.
One advantage of tAe present invention is the
provision of a new and improved method for fluid assisted
injection molding.
Another advantage of the presant invention i5 the
provision of a process for fluid assisted injection molding
which is faster than the heretofoxe Xnown processes of this
type.
Still another advantage of the present in~en~ion is
the provision of a fluid assisted injection molding process
in which a cooling fluid is circulated through a fluid
cavity formed in the thermoplastic material.
Yet another advantage of the present invention is
the provision of a process for producing an injection
molded product which employs the step of filtering the
fluid during its venting from the fluid cavity.
A further advantage of the present invention is the
provision of a fluid assisted injection molding process in
25 which differen$ paths are utilized for introducing the
fluid and for Yenting the fluid.
A still further advantage of the pres~nt invention
is the provision of a ~luid assisted injection molding
process in which the fluid to be injected is heated so that
it approaches the temperature at which the molten
thermoplastic enters the mold cavity.
A yet ~urther advantage of the present invention is
the provision of a fluid assisted injection ~olding proce~s
in which differe,nt paths are utilized for intro~ucing and
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venting a cooling fluid than are utilized for introducing
and venting the heated fluid.
Still other benefits and advantages of the invention
will become apparent to those skilled in the art upon a
reading and understanding of the following d~tailed
specification.
Brie~ Description of the Drawi~a~
The invention may ~ake physi.cal form in certain
parts and arranyements of parts, preferred and al~e~nate
embodiments of which will be described in detail in this
specification and illustrated in the accompanying drawings
which form a part hereof, and wherein:
FIGURE 1 is a side elevational view in cross section
of an adaptor body and an insert body together with
associated apparatus utilized in the process according to
the first preferred embodi~ent of the present invention:
FIGURE 2 is a greatly enlarged front elevational
view of an extension tube secured at one end to t~e adaptor
body of FIGURE 1 along line 2-2;
FIGURE 3 is a partially broken away front
: elevational view of~the adaptor body and insert body of
FIGURE l;
FIGURE ~ is a sche~atic side elevational view of the
apparatus utilized for a process for fluid assisted
injection molding according to a second preferred
embodiment of the present invention;
FIG~RE 5 is an enlarged vie~ of a section of FIG~RE
4;
FIGURE 6 is a sid~ elevational view in cross section
of an injection molding nozzle according to a third
~, preferred embodiment o~ the invention which can be utilized
in the apparatus illustrated in FIGUR~ 4; and,
FIGURE 7 is an enlarged side elevational view in
cross section of a portion o~ the nozzle of FIGURE 6.
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Detailed DescriPtion of Pre~ferred and ~lternate Embodiments
Referring now to tha drawings, wherein the showings
are for purposes ~f illustrating preferred embodiments of
the invention only and not for purposes of limiting same,
FIGURE 1 shows the subject new bushing, including an
adaptor body A and, prefarably, an insert body B, which is
utilized in the process for fluid assisted i~jection
molding according to the present invention. It should,
however, be recognized that tAe adaptor body can be
utilized by itself in the method according to the present
invention and that the adaptor body can have many different
configurations.
The ~daptor body A is substantially cylindrical in
cross-section in the embodiment sho~n, although it could
also have any o~her conventional cross sectional shape as
well. The body has a larger diameter first section 10 on
which is defined a first or rPar end 12 and a second or
front end 14. Mounted on the front end is a redu~ed
diameter second section 16. Provided on an ~xterior
periphery of the second section 16 is a threaded area 18.
The adaptor body A also incIudes a smooth outer periphery
on the first section 10 thereof.
Extending longit~dinally through the adaptor body A,
substantially along its center line, from the first section
rear end 10 to a second section front ~nd 20 is a bore 22.
The bore accommodates a flow of a relatively viscous fluid,
such as a molten thermoplastic, through the body.
Extending transversely across the bore 22 between
opposing walls of the bore and adjacent the adaptor body
front end 20 is a bridge 30. Fluid flow is allowed through
the first bore around the bridge through semi-circular
slots 32 of the bore 22 as is evident from FIG~RE 2. The
bridge 30 has a substantially flat front end 34. Extending
into the bridge 30 from the front surface 34 thereof is a
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first bore 36 for accommodating a flow of a relatively non-
viscous fluid. This fluid can be a neutral gas such as
nitrogen, but it could also be air, steam or t~e like~ The
first bore 36 terminates on the bridge front sur~ace in
such a manner as to be substantially coaxial with the
adaptor body longitudinal bore, a~ best seen in FIGURE 2.
The f irst bore 36 communicates with a second bore 38
extending approximately normal to the fir5t bore in the
adaptor body A. A third bore 40 of substantially larger
diameter than the second bore co~nunicates therewith and
extends to the outer periphery of the adaptor body first
section lo. The third bore.includes a threaded section
adjacent the adaptor body outer periphery 20 so as to
accommodate a suitably threaded ~itting 42. Communicating
with the third bore 40 is a fourth bore 44 defined in the
adaptor body A in a direction normal to the third bore.
; The fourth bore 44 in turn communicates with a fifth larger
diameter bore 46 that extends through the rear end 10 of
the adaptor body A. Suitably threaded in the fifth bore 46
is a second fitting 48.
: Located in the adaptor body third bore section 40 is
a suitably designed, cylindrically shaped filter 50 made of
suitable, conventional material for filtering the gas or
other relatively non-viscous fluid flowing through the
bores 36, 38, 40, 44 and 46. The filter is especially
useful during the decompression o~ fluid which is held in
: the fluid cavity formed in the molded part during the
molding operation. The filter prevents the flow back into
the fluid line of plastic particles which ~dust off" the
now solidified plastic part when the fluid is vented from
the fluid cavity created in the molded part. Thus, the
main function of the filter 50 is to filter the fluid
flowing back out of the mold cavity in order to prevent
~`~ thermoplastic particles from flowing back into the fluid
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line and eventually clogging the line or a valve positionedin the line.
A first fluid line 60 communicates with the ~itting
42 and hence with the plurality of bores. The line 60
leads from a first fluid supply so~rce 62 with the flow of
fluid being controlled by a suitab.le conventional ~irst
valve 64. Also provided is a seco:nd fluid line 66 which
communicates with the fit~ing 48 and allows fluid to flow
from a pressurized second fluid source 68 as controlled and
regulated by a second valve 70.
Preferably, the third bore 3~ extends away from the
: second bore 36 in both directions so as to also communicate
with sixth, seventh and eighth bores, 80, 82 and 84
provided in the adaptor body A. In this way, two paths are
provided for the fluid to flow through the adaptor body A.
A third fitting 86 communicates fluid from a third line 88
with the sprue bushing A. The third line leads to a third
pressurized fluid source 90 and is regulated by a third
valve 92 positioned in the line 88. Also provided is a
fourth fluid line 94 which communicates with a fitting 96
that is secured to the adaptor body A in the line 84. The
~`~ fourth line 94 allows pressurized fluid from a fourth
~ supply source 98 to communicate with th~ fitting 96 as
controlled by fourth valve 100.
If desired, a fifth ~luid line 110 can be provided
bet~een the first and second ~luid lines 60 and 66 with a
one way check valve 112 being positioned in that line to
~; prevent communication between the fluid 1 ines in one
. direction. Similarly, a sixth fluid line 114 can be
provided to allow selective communication between ~he ~hird
. and fourth fluid lines 88 and 94 and a check valve 116 can
`i be provided in that line to allow communication only in one
direction.
Provided on the adaptor body ~irst bore 36 is a
~: 35 threaded area 120 which cooperates wi~h a suitabl~ threaded
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section 122 of a tube 124 that is secured to the adaptor
body A. The tube 124 extends away from the adaptor body A
and includes a longitudinally exte!nding through bore 126
(FIGURE 2) which coTLmunicates with the ~irst bore 36. In
this way, gas will flow out o~ the first bore 36 and into
the tube through bore 126.
As shown in FIGURE 2, the t:hrough bor~ 126 can, i~
desired, be sealed with a suitabl~! plug 127 suc~ that the
plug is provided with a plurality of spaced small sized
apertures 128, as shown in FIGURE 2. This would be
advantageous to prevent the inflow of molten thermoplastic
material during the depressurization. ThP small size
apertures make it difficult for the molte~ thermoplastic
material to flow back through them and into the larger
-~ 15 diameter bore 126 in the tube 124.
With continuing rePerence to FIGURE 1, an insert
body B, which can have a substantially cylindrical shape,
if desired, is preferably provided ~djacent the adaptor
body A. The insert body can include a flat ~irst or rear
: 20 end 130, as well as a bulbous seoond or front end 132. A
longitudinally extending bore 134 extends between the first
: and second ends. The bore 134 is provided with a threaded
section 136 at its rear end which is adapted to engage the
threaded outer periphery 18 of the adaptor body second
: 25 section 16 in order to provide a securing ~eans to fasten
the adaptor body to the insert body.
The tube 12~ preferably extends throu~h the insert ~ -
body bore 134 to the insert front end 132. The tube is
advantageous in order to allow direct communication of the
fluid flowing through the tube and the bores 36, 38, 40, 44
and 46 as well as 80, 82 and 84 with a~ associated sprue C
positioned adjacent the insert body B. In this way, fluid
does not flow into the molten thermoplastic flowing through
the insert body bore 134 but rather it communicates with
the molten the~oplastic only at the sprue C~ This is
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11 2~29'17
advantageous in order to insure that the fluid ~lows
directly into the middle of the molten thermoplastic
material instead of diffusing therein.
The fluid which flows through the sprue C creates a
fluid cavity 140 in a plastic body or part 142 which is
formed in a mold space 144 that is oreated hy oooperation
of a pair of mold halves 146 and 148 of a mold body D. As
can be seen from FIGURE 1, t~e fluid ca~ity is formed in a
thicker section of the plastic body 142. The tube 124 also
ensures that, during the exhaust of ~he fluid from a ~luid
cavity 140 created in the plas~ic body 142, there will not
be molten thermoplastic flowing out with the gas.
In order to ensure that the fluid or gas flowing
through the adaptor body and the insert body B is heated,
suitabla heater bands 152 and 154 can preferably encircle
the adaptor body A and the insert body B. Alternatively,
another way of heating the adaptor body A and insert body B
would be by use of one or more heater cartridges (not
illustrated) which could extend into one or more suitably
configured bore~ (not illustrated) provided in the adaptor
body and the insert body.
It is advantageous to provide hot gas to the plastic
material which is being formed into the plastic part 142
because the heating of the gas where it enters the plastic
keeps the plastic hot. ~olten the~moplastic when it is
cooled from the center, i.e., by cool ga~ entering the ga-
cavity 140 formed in the molten ther~oplas~ic will under
some circumstancPs deteriorate the properties of some
plastics. These plastics particularly include crystalline
plastic materials such as nylon, polyphenylene sulfide and
polyester.
Generally, the mold is adapted to cool from the
outside in and not from the inside out. The:refore the
center of the plastic flow is meant to be hotter than the
outside. If, on the other hand, a cool fluid is introduced
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29~7
12
into the center of the molten thermoplastic material, i.~.,
such as a gas which has not been heated, then the center o~
the molten thermoplastie cools which will deteriorat~ the
properties of some plastics. While the gas temperature is
generally alway~ cooler than ~he melt temperature of the
plastic (i.e., the melt temperature may be on the order of
600-F and the heated gas temperatures on the order of
350'F) if the gas were not heated at all (and would be at
the ambient temperature of 50-80-F) then the properties Or
certain thermoplastic materials will be deteriorated.
Extending longitudinally through the insert body B
is a second bore 160. An aperture 162 extends into the
adaptor from the front end 132 thereof. The locations of
the bore 160 and the aperture 162 can vary as necessary.
In the embodiment of FIGURE 2, there ar~ two such apertures
162 and foux such bores 160. It should be recognized,
however, that any other suitable number of such apertures
and bores may bs provided as necessary.
Secured to the insert body B is a layer of a
suitable conventional insulating material 164 such as mica.
It is advantageous to insulate the bushing from the sprue C
and hence the rest of the mold body, in order to allow the
mold body to fully cool down. This is done by insulating
the molten thermoplastic in the heated nozzle (not
; 25 illustrated) the adaptor body A and the insert body B from
the sprue C and the re~t of the mold body. Thus, the
;~ thermoplastic in ~he mold body ~nd sprue can c901 down
while the thermoplastic in the nozzl~ and the bushing
(i.e., the adaptor A in the insert B) stays molten.
In so~e instances, it may be desirable to eli~inate
the layer o~ insulation material 164 so that the sprue C is
kept hot along with ~he material being injected into the
mold cavity 144. This may be advantageous when materials
of different thermal conductivities are utilized for the
sprue bushing A and insert body B on the one hand and the
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sprue C on the other hand. For example, a copper beryllium
compound can be utilized for the sprue C, whereas a
different material can be utilized ~or ~he sprue bushin~ A
and adaptor B. In this way, heat can extend beyond th~
adaptor B to the sprue bushing rear portion thereby
allowing the sprue to attach easily and reduce material
-thermal shock.
A ~ore 166 extends through the insulation material
164 in a manner so as to communicate with the bore 134 of
the insert body B thereby allowing molten thermoplastic
material to flow therethrough. Also provided in the
insulation material is a first aperture 168 for
accommodating a fastener 170 that secures the layer of
insulation material to the insert body B by extending into
and being fastened in the aperture 162 of the insert body.
Further extending through the insulation material 164 is a
second aperture 172 for accommodating a fastener 174 which
secures the insert body B to the sprue C by extending into
an aperture 176 of a sprue body 178. Extending
longitudinally through the sprue body 178 is a bore 180
which communicates with the insert body bore 134 and hence
th~ adaptor body longitudinal bore 22. The bores 22, 134
and 180 are coaxial so that molten thermoplastic material
can, as illustrated, flow entirely through them in a
relatively easy fashion. In the meanwhlle, gas will enter
the sprue bore 180 directly at the ~ront o~ ~he bore
through the tube 122 as shown and will not be mixed with
the molten thermoplastic material flowing through ~he
insert body bore 134, as mentioned previously.
The method of utilizing the apparatus heretofore
described is as follows. An amount o~ a molten
thermoplastic sufficient for the preparation of the
injection molded product in the mold cavi~y 144 (but less
than the volume of the mold cavity) is prepared and the
plastic material is introduced through the bores 22, 32,
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2~g47
14
134 into the sprue bore 180 from whence it flows into the
mold cavity 144. Either simultaneously therewith or
thereafter, a quantity o~ heated f:Luid, such as ~he neutral
gas nitrogen, is introduced into tlle molten thermoplastic.
In other words, the gas and plastic can be utilized in a
simultaneous injection molding process or the so-called
post injection molding process in which the gas is
introduced only after the thexmopl;~stic has already ~lowed
into the mold cavity 144.
The heated gas proceeds to form the gas cavity 140
in the molten thermoplastic material. The gas can be
introduced through both the lines 60 and 88 if desired so
that gas flows simultaneously through both of these lines
and thus through both ends of bore 38 through bore 36 and
the bore 126 in the tube 124 to the front of the insert
body B and thence into the sprue C. Alternatively gas
inflow may take place only through line 60 or line 88 if
desired.
Thereafter, once the fluid cavity has been ~ormed in
the plastic material 142 and when it is time to cool the
molded product, the heated gas can ~e vented ~rom the gas
cavity. Such venting may take place through the lines 36,
38 and through both lines 60 and 88 if desired~ or only
through one of them such as the line opposite the gas
inflow line~ In other words, gas can flow in through line
60 and out through line 88 if desired. The gas will ~low
through the filters 80 thereby trapping any plastic
particles.
; It is advantageous to have both gas lines 60 and 88
allow flow in and out so as to ensure that the lines 4n and
80 ~ill not plug due to the deposition of particles of
thermoplastic material onto the filters 50. In other
words, as gas enters through the filters 50, the gas will
blow the thermoplastic parkicles back into the mold cavity
and thereby clean the various gas flow channels in the
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sprue bushin~ A.
The heated gas i5 preferably at a pressur~ which is
higher than the injection pressure at which the molten
thermoplas~ic is introduced into the mold cavity. In this
regard, the injection pressure, or booster pressure, can be
at a pressure which is on the order of 2,000 p.s.i. On the
other hand, the h2ated gas pressure, or pac~ing pressure,
or fill pressure, can be on the order of 2,500 p.s.i. Or
perhaps evan as high as 3,500 to 4,000 p.s.i. i~ required.
The pressure of the molten thermoplastic material as
it flows into the sprue bushing orifice 22 may be higher
due to the volume ratio of the flow channels involved.
However, the pressure required to penetrate the molten
thermoplastic may not be as great. Accordingly, a ga~
injection pressure of approximately 2500 p.s.i. may be
adequate for the gas to penetrate the molten ther~oplastic
and flow into the center of the melt.
After the heated gas is vented, a cooling gas can
thereupon be introduced into the gas ~avity 140~ The
cooling gas can flow in through lines ~6, 46, 44, 40, 38
and 36 as well as lines 94, ~4, 82, 80, 38 and 36 if
desired. In other words, the cooling gas can flow through
both of the lines 66 and 94 if desired. Alternatively,
cooling gas can flow in through line 66 and out through
line 94 if so desired.
If desired, the body 142 can be cooled in such a
fashion that a charge of cooling gas flows in through lines
66 and 94 and is held in the gas .avity 140 b~cause valves
70 and 100 are closed. The gas will pick up a certain
amount of heat from the interior of the plastic material
142. Thereupon, the valves 70 and 100 are opened so that
the now heated gas can be exhausted. Thereafter, another
charge of cool gas can enter through lines 66 and 94 and be
held in the gas cavity 140 with the valves 70 and 100 bei~g
shut off. Subsequently, the valves 70 and 100 can again be
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16 / 2~42947
opened in order to exhaust the now heated cooling gas
(which has now picked up heat from the plastic part 142,
thereby cooling the part) from the gas cavity 140. By this
means, the body 142 can be readily cooled ~xom the inside
at the same time that the mold body halves 146 and 148 cool
~rom the outside.
Once the part 142 has been cooled, the injectiôn
molded product is removed from th~ mold cavity 144.
If desired, the cooling gas can be held at a
pressure wAich is higher than the pressure at which the
heated gas is injected into the mold cavity~ This would be
advantageous to insure that the plastic stays against the
mold cavity walls instead of shrinking away therefrom.
Alternatively, the cooling gas can be at the same or a
lower pressure than the heated gas. It is at this point
envisioned that the cooling gas will be at a pressure
higher than the 2,500-4,000 p.s.i. pressure of the heated
gas although it could be at a lower pressure, such as a
holding pressure of, e.g., 700-800 p.s.i. if desired.
With reference now to FIGURES 4 and 5, th~ use o~
~he sprue bushing in a different type of mold syste~
according to a second praferred e~bodi~ent of the-invention
is there illustrated. For ease o~ illustration and
appreciation of this embodiment, like components will be
identified by like numerals with a primed ('~ suffix and
new components will be identified by ne~ nu~erals.
In this embodiment, a ~hermoplastic material
injection machine or plasticizer E is illustrated together
with a suitable associated nozzle F. The nozzle F delivers
molten thermoplastic material to a mold body G which is
defined by a base member 200 and a cover member 202. As
best shown in FIGURE 5, defined between the base and the
cover is a mold cavity 204. Extending through the cover
202 is a suitable sprue 206. Holding the base 200 and
cover 202 togethsr is a suitable clamping plate 210. The
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clamping plate has a central bore 212 extending
therethrough. An outer periphery of the plate 210 is so-
shaped as to be able to cooperate with a profiled tip
portion 214 of the injection nozzle F. Located in a space
215 defined between the cover 202 and the clamping plate
210, are a pair of hot runner cha~mels 216 which feed th~
molten thermoplastic material to 21 sprue bushing Hl which
can include an adaptor A' and an insert B'. A second,
spaced, sprue bushing H2, which can have an identical
construction, is also located in the mold body G. Also
flowing through the two sprue bushings Hl and H2 is a
relatively non-viscous fluid, such as a gas. As in the
embodiment of FIGURE 1, the molten thermoplastic ~orms a
body 220 in the mold cavity 204 and the gas forms separate
unconnected first and second gas cavities 222 and 224 in
the thermoplastic material. It is noted that unlike the
adaptor A of FIGURE1, the adaptor Al in FIGURE S only has
one gas inflow path utilizing channel 4~' and one gas
outflow path employing channel 82'. The other two paths in
the adaptor Al are closed off.
With reference now again to FIG~RE 4, gas is
provided from as gas reservoir 230 through a first line 232
and past a pressure reducing valve or first valve 234. At
that point, two pressure gauges 235 and 236 are provided to
measure the pressure of the incoming gas before and after
the pressure reducing valve, respectively. The gas
encounters a first manual control valve 237 which leads to
a branch 238 which leads through a second branch 239 to a
first pump 240 for pumping up the gas to a higher pressure
which is indicated on a third pressure gauge 242. A first
check valve 244 prevents the now-pressurized gas from
flowing back downstream to the valve 234. Located in the
first line 232 and downstream from the first branch 238 is
a second check valve 246. Downstream therefrom, is a third
branch line 248 which leads to a second pump 250. A fourth
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pressure gauge 25Z indicates the pressure at which the
second pump 250 pressuri~es the gas. Provided downstream
from the third branch 248 is a ~hird check valve 254 and,
downstream there~rom is a second ~anual contrcl valve 256.
A first remotely actuated fluid operated valve 258 is
provided in the line 232. Supplyi:ng fluid ~ro~ reservoir
Tl to control the valve 258 is a solenoid actuated valve
25~. Branching away ~rom the first line 232 is a first
inlet line 260 which leads gas to the sprue bushing H2.
Provided downstream from the first inlet line 260
are fourth and fifth check valves 262 and 264 which prevent
a flow of the gas in either direction through the line at
that point. These check valves can be manually opened and
they can be housed in a common housing 266.
A first outlet line 270 leads the gas away from the
sprue bushing H~. Provided in the first outlet line 270 is
a second remotely actuated control valve 272 selectively
allows the flow of gas to a suitable sump 274. The valve
274 is fluid operated and is controlled by a solenoid
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actuated valve 276 which selectively supplies fluid fro~
reservoir T3 to actuate the valve 272.
In order to provide gas to l:he sprue bushing Hl, a
second inlet line 280 communicates with the ~irst branch
238 in order to allow pressurized gas to be sent through
the second inlet line 280 to the adaptor body A' and then
into the second gas cavity 224 ln the body 220.
Controlling the flow of gas throug}l the first branch 238 i~
a third remotely actuated control valve 282. As with the
other two control valves 258 and 272, the third control
valve 282 is a fluid actuated valve. Pressurized fluid is
selectively provided to actuate the valve 232 by a solenoid
operated valve 284 from a reservoir T2. Allowing a venting
from the second gas cavity 224 is a second outlet line 290
which is in communication with the sprue bushing H2.
Provided in the line 290 is a re~otely controlled fluid
actuated control valve 292 which selectively allows outlet
gas to flow to a sump 294. Controlling the actuation of
the val~e 292 is a solenoid actuated valve 296 which
selectively allows pres~urized fluid to ~low fro~ reservoir
T4 to the valve 292.
Instead of providing a sprue bushing as shown in
FIGURE 5 for the bodie-~ ~l and H2, an injection nozzle
according to FIGURE 6 can be utilized instead. This type
of injection nozzle comprises a nozzle body 310 having an
; inlet end 312 in a discharge end 314. The nozzle includes
a housing which co~prises a central secti~n 320, an ad~ptor
:~ or rear section 322 having a longitudinal bore 324
extending therethrough and a tip or front section 326
having a longitudinally extending bore 328 therethxough.
The adaptor 322 .is suitably secured to the central section
320 by interengaging threads as at 330. Securing the tip
326 to the central section 320 is a suitable coupling
member 332 which has a central longitudinally extending
bore 334 therethrough with th2 bor2 having a pair o~ spaced
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209L2g~ J
threaded areas 33S and 336 which respectively cooperate
with threaded exterior peripheries provided on the tip 326
and a front end of the central section 320. The central
section 320 has a first aperture ~l40 extending
longitudinally therethrough in an orientation which is
coaxial with the bores 324 and 328 in the adaptor and the
tip respectively. There are preferably two such apertures
340 which can be kidney shaped if desired. Thus, a flow
channel is formed entirely through the nozzle. A second
aperture 342 ~xtends through opposing side walls of the
central section 320 in a direction normal to the ~irst
apertures 340 and not in communication therewith.
A valve body 348 is adapted to reciprocate in the
nozzle body 310. For this purpo~e, a needle 350 of the
valve body is reciprocally mounted in a third aperture or
bore 351 extending longitudinally in the central section
320 and parallel with the first apertures 340. The needle
has a tapered first end 352, a cylindrical central portion
353 and a flat second end 354. A longitudinal aperture 356
extends from the first end into the valve needle 350 until
it meets a second ~perture 358 which extends normal to the
- first aperture inwardly from the exterior periphery of the
- needle 350. The second aperture is suitably threaded so
that it can receive an externally ~hreaded fitting 360.
Extending longitudinally through the fitting is a bore 361
that communicates with the longitudinal aperture 356 of the
needle 350. 1~ this way, a suitable gas or other
relatively non-viscous fluid such as st~am can be
transmitted through the fitting 360 into the needle 350 so
that it can flow out the free end of the needle 350 and
into the bore 328 in the tip 326. From there, the gas will
flow into the gas cavities 222 and 224 as shown in FIGURE
4. A filter 362 is preferably located in the bore in order
to filter the ~as flowing therethrough.
21 20~2~47
With reference now also to FIGURE 7, preferably
sscured to the needle first end 352 is a tube 363 which has
a forward end thereof extending pa~;t the needle ~irst end.
The tube 363 is in ~luid communicat:ion with ~he relatively
non-viscous fluid flow aperture 356 extending through the
needle 3S0. A layer of insulation 364 is pre~erably
disposed between the nozzle body central section 320 and
the tip 326.
The insulation 364 is useful in order to restrict
heat transfer from the nozzle to the sprue bushing 326.
The normal material for such insulation is mica which is
relatively weak in impact strength. Accordingly, a spacer
element 365 is preferably disposed between the insulation
and the central section 320. The spacer can be made from a
relatively hard mat~rial such as steel. Apertur~s are
provided through the insulation 3~4 and spacer 3~5 which
apertures are coaxial with the tip ~ore 328 and the coupler
bore 334.
Encircling a forward portion of the needle 350 is
preferably a weir bushing 366 which can be made from a
relatively hard material, such as carbide.
As shown, the nozzle preferably further comprises a
means for selectively urging the valve body 348 in a first
~irection so as to close the nozzle body dischar~e end 314
by abutting a side face o~ the needle front end 352 against
an angled portion of the spacer element through ~hich the
tip bore extends.
With reference again to FIG~RE 6, the means ~or
selectively urging can be secured to the nozzle body
central section 320 and preferably can comprise a
torroidally shaped piston 372 which reciprocates in a
chamber 382 formed by elements of a housing ~hat are
secured to the body central section 320. A suitable gas
can be fed to either side of the piston 372 in order to
.
22 ( 2 0~29l~7
reciprocate same. This then will r~ciprocate the needle
350 held in the noæzle 320.
In this embodiment, the gas will enter the fitting
360 and flow through the bore 361 and into the longitudinal
aperture 356 of the needle 350. The gas will then flow
through the bore 328 and into one of the spaced gas
cavities 222 or 224. As with the embodiment described
hereinabove, two of these noz21es 310 are required, one at
the location marXed by the identifying numeral H1 and the
other one located at H2. The flow of gas through the
nozzles is as described hereinabove, except that a common
flow line for gas flow in and gas flow out is utilized. In
other words, the lines 260 and 270 are merged or joined at
the ~itting 360 into a single line. However, upstream from
the fitting 360, the lines separate out and flow through
them is controlled by the remotely actuated fluid operated
; valves 258 and 272 respectively. However, separate flow
lines could also be employed if desired. For example, two
such fittings 360 could be provided for the valve 350 so
that both fittings communicate with the bore 356, in much
the same way as the common line 36 in ~IGURE 1 communicates
gas from separate gas lines 44 and 82.
Also, in this embodiment, a separate plastic
injection molding nozzle, such as F in FIG~RE 4, is not
required. Just the injection machine E is necessary since
the nozzle function is provided by the no~zle body 310.
The invention has been descri~ed with reference to
preferred embodiments. Obviously, modifications and
alterations will occur to others upon the reading and
understanding of this specificat~on. It is intended to
include all such modi~ications and alterations insofar as
they come within the scope of the appended claims or the
equivalents theraof.
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