A METHOD AND SYSTEM FOR OPERATING AN

INJECTION MOLDING MACHINE
TECHNICAL FIELD
The present invention relates to molding systems in general, and more specifically to a method
and system for operating an injection molding machine.
BACKGROUND

Examples of known molding systems are (amongst others): (i) the HYPET (TRADEMARK)
Molding System, (ii) the QUADLOC (TRADEMARK) Molding System , (iii) the
HYLECTRIC (TRADEMARK) Molding System, and (iv) the HYMET (TRADEMARK)
Molding System , all manufactured by Husky Injection Molding Systems (Location: Canada).
United States Patent Number 4522778 (Inventor: BACIU et al.; Published: 1985-06-11)
discloses a method and apparatus for production of parts made from a plastics material using
an injection press in which a mold cavity is defined by a mold surface and a surface of a
movable piston. Firstly, the plastics material is introduced into the mold cavity, and during
20 injection the piston is kept stationary for a time to form a rough mold and then retracted to
form a parison. Secondly, after injection has been completed the piston is advanced again, and
maintained in position while cooling takes place. Thirdly, the mold is opened and the part is
ejected from the mold cavity.
25 European Patent Number 244783 (Inventor: MAUS et al.; Published: 1987-11-11) discloses a
method- and apparatus for injection compression molding of thermoplastic parts. Enlarged
mold cavities receive plasticized resin, and compression of the injected resin is provided by a
toggle clamp assembly. Preferably, the toggle clamp assembly provides multiple-stage
compression of the resin to first redistribute the resin and vent the cavities and, second,
30 compress the resin to compensate for cooling-induced shrinkage thereof. In the multiple
cavities, because all cavities are equally compressed simultaneously, control of the molding
process and balancing of the mold are readily accomplished.
European Patent Number 369009 (Inventor : UEHARA et al.; Published : 1990-05-23)
35 discloses a desired quantity of a molten thermoplastic resin injected into a mold cavity which
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has a greater capacity than a product volume and is set in advance to a higher temperature than
the temperature at which the thermoplastic resin starts curing under a normal pressure. The
thermoplastic resin thus injected is cooled inside the mold cavity and is pressed before it is
cooled down to a temperature at which it starts curing under a normal pressure. Due to this
5 pressing, the glass transition point of the thermoplastic resin is shifted to a higher temperature
side and the thermoplastic resin cures during a small temperature drop. The thermoplastic
resin is cooled in the pressed state until dynamic rigidity at normal temperature and normal
pressure is obtained. The thermoplastic resin is further cooled to a withdrawing temperature
and the pressure applied to the thermoplastic resin is controlled so that dynamic rigidity of the
10 thermoplastic resin during this cooling process can be maintained at the normal temperature
and normal pressure by offsetting the rise of dynamic rigidity of the thermoplastic resin to be
caused by cooling.
European Patent Number 425060 (Inventor: KASAI et al.; Published: 1991-05-02) discloses a
15 process for effecting injection molding of plastic resin products on an injection molding
apparatus including a metal mold composed of a slidable mold element and a fixed mold
element defining together a mold cavity, an actuator for sliding the slidable mold element, and
an injection means with an injection nozzle permissible of adjusting the nozzle flow path
section. The operation includes: (i) a first molding step of injecting a molten resin into the
20 mold cavity which has been preset by the slidable mold element so as to include a postcompression
margin to be compressed afterwards in a second molding step, to effect the
injection under a reduced molding pressure, while causing a temperature elevation and, thus, a
viscosity reduction of the molten resin, until the mold cavity has been filled up, and (ii) a
second molding step of compressing the resin so charged in the mold cavity by operating the
25 slidable mold element to compress the charged resin to compensate said post-compression
margin, so as to allow an effective pressing force to be imposed onto the charged resin within
the mold cavity also after the mold gate has been sealed.
European Patent Number 593308 (Inventor: HENDRY; Published : 1994-04-20) discloses a
30 mold apparatus and method to form a solid injection molded plastic part. The mold portions
of the mold apparatus are closed , charges of molten thermoplastic and pressurized gas are
sequentially injected into a mold cavity, and the mold portions are sequentially separated and
closed. The pressurized gas forces the hot plastic away from one mold half and against the
other mold half, and separation of the mold portions ensures uniform distribution of the
35 pressurized gas behind the hot plastic , which pressure is maintained during cooling.
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Depending on the application, the plastic completely packs the cavity, fills but does not pack
the cavity, and the mating faces can be abutted or maintained partially separated when the
mold portions close. A gas seal is formed by the plastic to prevent gas in the mold cavity from
reaching the finished exterior surface of the part during shrinkage of the plastic.
5
European Patent Number 597108 (Inventor: MORIKITA; Published: 1994-05-18) discloses a
localized pressurizing type injection molding machine for applying various processes to
moldings during an injection-molding cycle; the injection molding machine can apply various
processes to the moldings after the injection molding process.
10
European Patent Number 944466 (Inventor: HEHL; Published: 1999-09-29) discloses a
process for manufacturing injection moldings in an injection molding machine for processing
plasticized masses, in which a regulated subsequent pressure is applied by the injection
molding unit. At least in the areas of the molding away from the sprue, the subsequent
15 pressure is generated by a regulated volume alteration of the mold cavity. The subsequent
pressure can be distributed during the subsequent pressure phase even in the case of complex
moldings.
European Patent Number 1343621 (Inventor: WEINMANN; Published: 2003-09-17)
20 discloses controlled correction of possible quantitative errors in the production of optical data
supports. The cavity of the mold is only partially filled prior to the stamping phase. It is the
subsequent stamping that is used to complete the filling process by moving one mold half. In
the first phase of stamping or compressing the melt, the pressure is detected in defined
positions of the molds or at a defined point in time and any deviation from a predetermined set
25 pressure value is corrected by the immediate introduction of a movement change in the
stamping process. By acting on the pressure conditions in the mold cavity, it is possible to
influence the backflow before the sprue is set, in terms of a set weight value of the finished
data support.
30 PCT Patent Application Number WO/2007/039766 (Inventor: CLARKE; Published: 2007-04-
12) discloses a mold for mounting between relatively movable platens of an injection molding
press for injection impact compression molding of an article. The mold comprises a cavity
plate formed with a depression, a core plate having a projecting core at least part of the outer
surface of which is cylindrical, and a closure plate movable relative to the core plate and the
35 cavity plate, and a surface in sealing contact with the cylindrical outer surface of the core. A
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locking mechanism is provided to lock the closure plate relative to the cavity plate while
permitting the core plate to move relative to the cavity plate.
United States Patent Number 7293981 (Inventor: NIEWELS; Published: 2007-11-13)
5 discloses a method and apparatus for compressing melt and/or compensating for melt
shrinkage in an injection mold. The apparatus includes a cavity mold portion adjacent a cavity
plate, a core mold portion adjacent a core plate, a mold cavity formed between the mold
portions, and at least one piezo-ceramic actuator disposed between either or both of the core
plate and the core mold portion and the cavity plate and the cavity mold portion. A controller
10 may be connected to the at least one piezo-ceramic actuator to activate it, thereby causing the
mold cavity volume to decrease, compressing the melt.
United States Patent Application Number 2008/0026239 (Inventor: BALBONI; Published:
2008-01-31) discloses a preform that is formed by an upper neck which maintains unchanged
15 its form in the final object and a hollow body, joined to the neck. The method foresees the
insertion, within a matrix cavity, of a metered body of polymeric material whose mass is
metered according to a reference value, and the subsequent pressure insertion of a punch
within the matrix cavity until it closes the mold's molding chamber, the punch conferring the
shape to the inner surface of the preform and the matrix having an inner surface which confers
20 the shape to the outer surface of the preform. In the molding of the preform, the error of the
mass of the metered body with respect to the reference value is distributed in the hollow body,
which undergoes a subsequent hot deformation until it achieves the final shape. In the mold,
the matrix comprises at least one deformable wall whose inner surface defines at least part of
the inner surface of the matrix part intended to give form to the hollow body of the preform,
25 said deformable wall having, at least in part, a relatively thin thickness which permits it to be
elastically deformed under the pressure of the polymeric material in the final preform molding
step, thereby varying the thickness of the hollow body.
SUMMARY
30
The inventors believe that the persons of skill in the art do not fully understand the problem
associated with the state of the art. The following description provides an understanding of the
problem and the solution provided by the aspects of the present invention.
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FIG. I depicts a schematic representation of a graph 10 having known PVT curves 16, 18 of a
known PET resin. It will be appreciated that the PVT curves 16, 18 are provided by way of
example, and that the present invention is not necessarily limited to any particular PVT per se
or any PVT curve for that matter, and that the present invention is applicable to any resin
5 material where density of the resin changes with temperature. PVT stands for pressure,
volume, and temperature. PET is the common name for a unique plastic belonging to the
polyester family. PET polyester is formed from ethylene glycol (EG) and terephthalic acid
(TPA), sometimes called purified terephthalic acid or PTA. PET's full chemical name is
polyethylene terephthalate. The PET bottle is the modem, hygienic package of choice for
10 many food products - particularly carbonated soft drinks and water.
The graph 10 includes a temperature axis 12 aligned along a horizontal direction of the graph
10 (that is, located along the bottom side of the graph 10) and increasing in magnitude from
the left side to the right side of the graph 10. The graph 10 also includes a specific volume
15 axis 14 aligned along a vertical direction of the graph 10 (that is located along the left side of
the graph 10) and increasing in magnitude from the bottom side to the top side of the graph
10. The PVT curve 16 represents the characteristics (that is, the temperature and volume
characteristics) of the known PET resin for a relatively lower internal pressure of the known
PET resin. The PVT curve 18 represents the characteristics of the PET resin for a relatively
20 higher internal pressure of the PET resin. It will be appreciated that the curves 16 and 18
usable for any type of pet resin.
FIG. 2 depicts a schematic representation of a graph 20 having a known molding cycle 30
superimposed on modified PVT curves 26, 28 of the PET resin of FIG. 1. It will be
25 appreciated that the graph 20 depicts flipped versions of the curves 16, 18 depicted in FIG. 1.
Specifically, the modified PVT curves 26, 28 of FIG. 2 are the flipped versions (that is,
flipped side to side) of the curves 16, 18 of FIG. 1, respectively. The arrangement depicted in
FIG. 2 permits the depiction of time as increasing from the left side to the right side of the
graph 20, and that the known cycle of a known molding machine may be better understood
30 when time is depicted in this fashion. The graph 20 includes a time axis 18 aligned along a
horizontal direction of the graph 20 (that is, located along the bottom side of the graph 20) and
increasing from the left side to the right side of FIG. 2. The graph 20 also includes the specific
volume axis 14 aligned along a vertical direction of the graph 20 (that is, located on the left
side of the graph 20), and increasing from the bottom side to the top side of FIG. 2. The graph
35 20 also includes the temperature axis 12 aligned the horizontal direction of the graph 20 (that
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is, located along the top side of the graph 20), and increasing from the right side to the left
side of FIG. 2.
A known cycle time or operation 30 of a known molding system includes (more or less): an
5 operation 31, an operation 32, an operation 33, an operation 34, an operation 35, an operation
36, an operation 37, and an operation 38. The operations 31 to 38 are depicted along the top
side of FIG. 2. The modified PVT curve 28 is used to describe the characteristics of the
known PET resin during the operations 31, 32, 33, 34 and 35. The characteristics of the PET
resin during operation 36 is described by a horizontally aligned line extending between a point
10 21 and a point 22, which represent terminus points for a beginning and an ending of the
operation 36. The horizontal line (that extends between the point 21 and the point 22) is used
because a volume of a mold cavity does not increase or decrease during the operation 36, and
therefore the volume of the molten resin in the mold cavity does not change during the
operation 36. The modified PVT curve 26 is used to describe the characteristics of the known
15 PET resin during operations 37 and 38.
The operation 31 includes closing a mold cavity. The operation 32 includes locking the mold
cavity shut and pressurizing a clamp assembly so as to apply clamp tonnage to the mold
assembly. The operation 33 includes injecting melted resin into the mold cavity volume of the
20 mold assembly; it will be appreciated that the operation 33 is sometimes known as the "fill"
cycle. The operation 34 includes slowly adding the melted resin to maintain a full cavity
volume; it will be appreciated that the operation 34 is also known as the "hold" cycle. The
operation 34 provides compensation for the pressure change of the melt in the mold cavity as
the temperature of the resin or melt drops; specifically, as the temperature drops the tendency
25 is for the pressure to drop, but the operation 34 is used to maintain or control (or may
increase) the pressure of the molten resin during the operation 34. This arrangement results in
increased density by pushing more of the melt into the mold cavity.
Typically, at the end of the hold cycle or the operation 34, the operation 35 is executed; the
30 operation 35 includes shutting off the mold cavity or isolating the mold cavity; the operation
35 is sometimes referred to as the "shut-off cycle" (that is, the time taken to close the mold
gate, which is expected to be a very short duration). The operation 35 includes moving a valve
stem into a mold gate that leads into the mold cavity, and the valve stem is used to stop further
movement of the molten resin into and out from the mold cavity (via the mold gate).
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The operation 36 permits the molten resin in the mold cavity to cool down for a period of
time; he operation 36 is commonly known as the "cool" cycle, in which the molded part is
cooled while it remains held in the mold assembly. During the operation 36, the mold gate
5 (sometimes called the "gate nub") is allowed to freeze. As the molten resin cools down and
the internal pressure remaining within the molten resin is reduced, but the density of the
molten resin remains the same because the mass of the molten resin and the volume of the
molten resin do not change (since the mold cavity is isolated from the upstream melt as a
result of the valve stem blocking the mold gate.
10
The operation 37 includes depressurizing a clamp assembly and unlocking a mold assembly.
Since the internal pressure of the resin in the mold cavity has reduced to near zero or
preferably zero pressure, there is very little or no danger of undesired or inadvertent
(unwanted) opening of the mold assembly (this is the preferred situation so that the molded
15 article is not inadvertently damaged by allowing the mold assembly to pop open under
pressure); in this manner the mold assembly is safely opened. The operation 38 includes
removing the molded article formed in the mold cavity, and then passing the molded article to
a post mold cooling apparatus for further temperature reduction if so desired.
20 It will be appreciated that the PVT curves and the operations of the cycle 30 are not accurately
drawn, but were drawn for illustrative purposes for ease of explaining the concepts. It will be
appreciated, for example, that typically, (i) the amount of time for the operation 34 (hold
cycle) is approximately equal to three times longer than the time required for the operation 36
(cool cycle), and (ii) the time for the operation 33 (injection cycle) plus the time for the
25 operation 36 (cool cycle) is approximately equal to the time for the operation 34 (hold cycle).
The inventors believe that the aspects of the present invention provide a technical solution to
the problem at hand. Specifically, the problem at hand is believed to pertain to cycle time, and
more specifically it is believed to be about reducing cycle time. A reduction of even a fraction
30 of a one second represents a significant improvement for an injection molding system used to
manufacture PET preforms. It is believed that the cycle time of the injection molding system
can be significantly reduced by using the aspects of the present invention.
The inventors have arrived at an understanding that the cool time during the operation 36
35 disadvantageously adds a substantial portion of time to the cycle time of the injection molding
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system; the inventors believe that the operation 36 serves several functions. A typical PET
preform requires (for example) approximately 1.5 seconds of cool cycle for a twelve second
total cycle time, which represents 12.5% of the total cycle time of the injection molding
system. The functions provided by the operation 36 are as follows: (i) freezing off the mold
5 gate area (sometimes called a gate nub) of the preform, and (ii) reducing an internal pressure
of the PET perform, so that the mold assembly may be opened safely (that is, without
inadvertently damaging the molded part or perform in specific and/or the mold assembly as
well).
10 The inventors believe that the solution to the problem of reducing the cycle time is to reduce
or (more preferably) overlay the time used for the operation 36 (that is, the cool cycle) by
having other molding-system operations execute, at least in part, the functions associated with
operation 36. This feat or arrangement is accomplished by managing the internal pressure of
the PET perform (that is, the molded article) preferably through physical methods, such as
15 altering the effective volume of a mold cavity to manipulate an internal pressure of the molten
resin received in the mold cavity while the mold cavity remains in an isolated condition.
The inventors believe that the state of the art does not overlay the operation 34 and the
operation 36, and the aspects of the present invention is to overlay the operation 34 and the
20 operation 36 so that the operation 36 is carried out in parallel with at least a portion of the
operation 34. The overlaying of operation 34 and operation 36 requires a modification of the
operations 34, 36. Namely, pressure control during operation 34 has to be done with another
device acting on the pressurized melt held in the mold assembly. Decompression at the end of
the operation 36 needs to be provided by a different mechanism than the natural change in
25 density of the resin as a function of cooling the "locked-in" material.
The inventors believe that the technical advantage of the aspects of the present invention is a
reduction in an overall cycle time of the injection molding system.
30 In accordance with a first aspect of the present invention, there is provided a molding system
being configured to manufacture a molded article in a mold-cavity system by using a
molding material , the molding system including: a pressure-control system being coupled
with the mold-cavity system ; and a controller operatively coupling to the pressure-control
system , the controller having a controller-usable memory tangibly embodying a set of
35 controller-executable instructions being configured to direct the controller , the set of
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controller-executable instructions including: mold-unpack instructions , including instructing
the controller to control the pressure-control system to reduce, after solidification, at least in
part, of the molding material being located in a nub region of the mold-cavity system ,
internal pressure of the molding material received in the mold-cavity system while the mold-
5 cavity system remains isolated from a stream of flowable-molding material, beyond any
reduction of the internal pressure in the molding material resulting from cooling of the
molding material , so that the reduction in the internal pressure of the molding material is
enough to permit safe opening of the mold-cavity system while permitting safe extraction of
the molded article from the mold-cavity system .
10
In accordance with a second aspect of the present invention, there is provided a method of
operating a molding system being configured to manufacture a molded article in a moldcavity
system by using a molding material , the molding system having a pressure-control
system being coupled with the mold-cavity system , the method including: controlling the
15 pressure-control system to reduce, after solidification, at least in part, of the molding material
being located in a nub region of the mold-cavity system , internal pressure of the molding
material received in the mold-cavity system while the mold-cavity system remains isolated
from a stream of flowable-molding material, beyond any reduction of the internal pressure in
the molding material resulting from cooling of the molding material , so that the reduction in
20 the internal pressure of the molding material is enough to permit safe opening of the moldcavity
system while permitting safe extraction of the molded article from the mold-cavity
system .
According to another aspect of the present invention, there is provided molding system being
25 configured to manufacture a molded article by using a molding material. The molding system
comprises a mold-cavity system for forming, in use, the molded article; the mold-cavity
system including: a primary parting line defined between a cavity portion and a neck portion
206 and; a secondary parting line defined between the neck portion and a top portion; a
controller operatively coupling to the a mold-moving actuator, the controller having a
30 controller-usable memory tangibly embodying a set of controller-executable instructions being
configured to direct the controller, the set of controller-executable instructions including a
mold open instruction configured to cause initial separation of the top portion and the neck
portion relative to the secondary parting line, while keeping the primary parting line unopened,
while maintaining at least some clamp force.
35
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According to yet another broad aspect of the present invention, there is provided a molding
system being configured to manufacture a molded article by using a molding material. The
molding system comprises a mold-cavity system for forming, in use, the molded article; the
mold-cavity system including: a stationary-mold assembly and a movable-mold assembly,
5 defining therebetween a mold cavity; the movable-mold assembly including: a base portion, a
top portion, a neck portion; a core portion, the stationary-mold assembly including: a cavity
portion, and a gate portion; a controller operatively coupling to the a mold-moving actuator,
the controller having a controller-usable memory tangibly embodying a set of controllerexecutable
instructions being configured to direct the controller, the set of controller-
1o executable instructions including a mold open instruction configured to cause relative
movement between the core portion and the cavity portion by a distance sufficient to displace
the totality of molecules of plastic of the molded article that abut with the core portion from
their relative positioning during a process cycle, the displacement being in substantially the
same direction, while maintaining at least some of the clamping force.
15
BRIEF DESCRIP-TION OF THE DRAWINGS
A better understanding of the exemplary embodiments of the present invention (including
alternatives and/or variations thereof) may be obtained with reference to the detailed
20 description of the exemplary embodiments of the present invention along with the following
drawings, in which:
FIG. 1 depicts the schematic representation of the graph 10 having known PVT curves 16, 18
of the known PET resin;
25 FIG. 2 depicts the schematic representation of the graph 20 having the known cycle time 30
superimposed on the modified PVT curves 26, 28 of the PET resin of FIG. 1;
FIG. 3 depicts a schematic representation of a molding system 100 in accordance with a first
non-limiting embodiment;
FIG. 4 depicts a schematic representation of a mold-cavity system 200 used in the molding
30 system 100 of FIG. 3;
FIGS. 5A, 513, 5C, 5D, 5E depict additional schematic representations of the mold-cavity
system 200 of FIG. 4;
FIGS. 6A, 6B, 6C, 6D, 6E, 6F, 6G depict schematic representations of a pressure-control
system 126 used in the molding system 100 of FIG. 3;
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FIG. 7 depicts a schematic representation of a set of controller-executable instructions 500
having instructions for operating the molding system 100 of FIG. 3; and
FIGS. 8A, 8B depict schematic representations of graphs 401 and 501, respectively, having a
cycle time 499 and a cycle time 599, respectively, superimposed on modified PVT
5 curves 26, 28 of the PET resin of FIG. 2; and
FIGS. 9A and 9B are schematic representations of the mold cavity system, implemented in
accordance with another non-limiting embodiment.
FIGS. 10A and lOB are schematic representations of the mold cavity system, depicting the
effect of executing the pre-eject function.
10
The drawings are not necessarily to scale and are sometimes illustrated by phantom lines,
diagrammatic representations and fragmentary views. In certain instances, details that are not
necessary for an understanding of the embodiments or that render other details difficult to
perceive may have been omitted.
15
REFERENCE NUMERALS USED IN THE DRAWINGS
The following is a listing of the elements designated to each reference numerals used in the
drawings:
10 graph
18 known pvt curves
26 modified pvt curve
30 known cycle time
100 molding system
102 stationary platen
104 movable platen
107 nub portion
109 parting line
121 bar locks
124 mold-cooling system
128 melt-preparation system
141 feed throat
143 heater assembly
145 screw assembly
150 housing
16 known pvt curves
20 graph
28 modified pvt curve
36 operation
101 molding material
103 molded article
106 platen bars
108 group of controllable systems
120 platen actuator
122 clamp assemblies
126 pressure-control system
140 hopper
142 barrel assembly
144 machine nozzle
146 screw drive
151 hydraulic piston
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152 chamber 153 stop
154 seal 156 link
157 wedge 158 coupler
160 controller 162 controller-usable memory
200 mold-cavity system 201 stationary-mold assembly
202 base portion 203 movable-mold assembly
204 top portion 206 neck portion
208 core portion 210 cavity portion
212 gate portion 213 mold cavity
214 nub region 216 mold gate
222 parting line 224 witness line
226 split line 240 core-cooling circuit
241 cooling tube 242 cavity-cooling circuit
244 nub-cooling circuit 246 cooling tube
247 rib assembly 249 jacket assembly
251 shoulder portion 252 spring
253 bottom surface 254 bolt
255 mounting bore 256 bottom face
257 tube mount 258 tube-receiving bore
260 plate assembly 261 tip
264 locating device 265 wedge-receiving groove
266 surface 267 wedge body
268 wedge groove 269 link body
270 link head 271 link shoulder
272 housing cover 273 plate body
274 wedge cavity 275 cooling circuit
276 plug 300 hot-runner system
401 graphs 412 temperature axis
414 specific volume axis 418 time axis
420 graph 421 point
423 point 425 point
430 operation 431 operation
432 operation 433 operation
434 operation 435 operation
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436 operation 437
438 operation 439
441 region 443
445 time 480
499 cycle time 500
501 graphs 502
504 mold-close instructions 506
508 tonnage-engage instructions 510
512 mold-injection instructions 514
516 melt-stream disconnection
instructions
518
519 time axis 520
521 point 522
523 point 524
525 point 526
530 hold instructions 531
532 mold-volume increase
instructions
540
542 mold-volume increase
instructions
543
545 time 580
590 first non-limiting variation 592
599 cycle time
operation
region
amount of time
molding operation
set of controller-executable
instructions
melt-preparation instructions
mold-lock instructions
melt-stream connection instructions
mold-pack instructions
heat-reduction instructions
mold-unpack instructions
tonnage-disengage instructions
mold-unlock instructions
mold-open instructions
compensation instructions
mold-volume reduction instructions
amount of time
aggressive cycle operation
second non-limiting variant
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
FIG. 3 depicts the schematic representation of the molding system 100. It will be appreciated
that the molding system 100 includes components that are known to those skilled in the art,
5 and these known components will not be described here; these known components are
described, at least in part, in the following reference books, for example: (i) "Injection
Molding Handbook" authored by OSSWALD/TURNG/GRAMANN (ISBN: 3-446-21669-2),
(ii) "Injection Molding Handbook" authored by ROSATO AND ROSATO (ISBN: 0-412-
99381-3), (iii) "Injection Molding Machines" 3rd Edition authored by JOIIANNABER
10 (ISBN 3-446-17733-7) and/or ( iv) "Runner and Gating Design Handbook " authored by
BEAUMONT (ISBN 1-446-22672-9).
The molding system 100 is configured to manufacture a molded article 103 by using a moldcavity
system 200 and using a molding material 101. The mold-cavity system 200 includes a
15 stationary-mold assembly 201 and a movable-mold assembly 203. Details for the mold-cavity
system 200 are depicted in FIG. 4. The molding system 100 includes (but is not limited to): (i)
a hot-runner system 300, (ii) a stationary platen 102, (iii) a movable platen 104, (iv) platen
bars 106, (v) a group of controllable systems 108, and (iv) a controller 160. The group of
controllable systems 108 includes (but is not limited to): (i) a platen actuator 120, (ii) bar
20 locks 121, (iii) clamp assemblies 122, (iv) a mold-cooling system 124, (v) a pressure-control
system 126 and, (vi) a melt-preparation system 128 (also called an extruder). The components
of the mold-cooling system 124 are depicted in FIG. 4. The components of the pressurecontrol
system 126 are depicted in FIG. 6. The hot-runner system 300 is coupled with the
stationary-mold assembly 201. The stationary platen 102 is configured to support the hot-
25 runner system 300 and the stationary-mold assembly 201. The movable platen 104 is
configured to support the movable-mold assembly 203, and is movable relative to the
stationary platen 102. The platen bars 106 operatively extend between the stationary platen
102 and the movable platen 104. The platen actuator 120 is coupled with the movable platen
104. The bar locks 121 lockably couple the platen bars 106 with the movable platen 104. The
30 clamp assemblies 122 are coupled with the platen bars 106. The clamp assemblies 122 are
configured to apply a clamp tonnage to the platen bars 106. The mold-cooling system 124 is
configured to couple with the mold-cavity system 200. The details for the pressure-control
system 126 are depicted in FIG. 6. The pressure-control system 126 is configured to couple
with the mold-cavity system 200.
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The melt-preparation system 128 is configured to couple with the mold-cavity system 200.
The melt-preparation system 128 includes (but is not limited to): a hopper 140, a feed throat
141, a barrel assembly 142, a heater assembly 143, a machine nozzle 144, a screw assembly
5 145, and a screw drive 146. The hopper 140 receives solid particles of resin. The feed throat
141 connects the hopper 140 to the barrel assembly 142. The heater assembly 143 is
connected with the barrel assembly 142. The machine nozzle 144 connects the barrel
assembly 142 with the hot-runner system 300. The screw assembly 145 is received in the
barrel assembly 142 and the screw drive 146 is connected with the screw assembly 145. In
10 operation, the screw assembly 145 prepares the melt and injects the melt under pressure
through the machine nozzle 144 and into the hot-runner system 300, and then the hot-runner
system 300 distributes the melt into respective mold cavities defined in the mold-cavity
system 200.
15 The controller 160 is operatively coupling to the group of controllable systems 108. The
controller 160 has a controller-usable memory 162 tangibly embodying a set of controllerexecutable
instructions 500 that are configured to direct the controller 160 to control
instructions of the molding system 100. The set of controller-executable instructions 500 are
depicted in FIG. 7.
20
FIG. 4 depicts the schematic representation of the mold-cavity system 200 used in the molding
system 100 of FIG. 3. The mold-cavity system 200 includes the stationary-mold assembly 201
and the movable-mold assembly 203. The movable-mold assembly 203 includes a base
portion 202, a top portion 204, a neck portion 206, and a core portion 208. Mold-moving
25 actuators (not depicted) are connected with the components of the movable-mold assembly
203. The stationary-mold assembly 201 includes a cavity portion 210, a gate portion 212, a
nub region 214, and a mold gate 216. Between the neck portion 206 and the top portion 204
there is a parting line 222. Between the cavity portion 210 and the neck portion 206, there is a
witness line 224. Between the cavity portion 210 and the gate portion 212 there is a split line
30 226. Between the top portion 204 and the core portion 208 there is a split line.
The mold-cooling system includes: a core-cooling circuit 240, a cavity-cooling circuit 242,
and a nub-cooling circuit 244. The core-cooling circuit 240 includes a cooling tube 241, an
inlet 243 formed at the end of the cooling tube 241, and an outlet 245 formed between the
15
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outer surface of the cooling tube 241 and the base portion 202. The cooling tube 241 extends
into the interior of the core portion 208 to an area located near the nub region 214. A cooling
fluid, such as water, flow from the inlet 243 to the tip of the cooling tube 241 and strikes the
core portion 208 that is located near the nub region 214, and flows back to the outlet 245
5 between the outer surface of the cooling tube 241 and the core portion 208 and the base
portion 202. The cavity-cooling circuit 242 includes cooling tube 246, a rib assembly 247, and
a jacket assembly 249. The rib assembly 247 includes a set of ribs extending outwardly from
the cavity portion 210. The jacket assembly 249 is received overtop of the rib assembly 247
(the jacket assembly 249 is not depicted along the top side of the cavity portion 210 for
10 illustrative purposes). The cooling tube 246 is defined by the outer surface of the cavity
portion 210, the rib assembly 247 and the jacket assembly 249. The nub-cooling circuit 244
includes a passageway defined in the gate portion 212.
It will be appreciated that a mold cavity 213 is formed within the mold-cavity system 200, and
15 the mold cavity 213 is formed as a result of the relative arrangement of the parts of the moldcavity
system 200, as the relative placement of the core portion 208, the cavity portion 210,
the gate portion 212, etc.
The molded article 103 (depicted as a PET preform) includes a parting line 109 formed as a
20 result of the witness line 224 during the manufacturing of the molded article 103. The molded
article 103 also includes a nub portion 107 that was formed as a result of the nub region 214.
FIGS. 5A, 5B, 5C, 5D, 5E depict the additional schematic representations of the mold-cavity
system 200 of FIG. 4.
25
FIG. 5A depicts the schematic representation of the mold-cavity system 200 having the
molding material 101 after the gate is shut , and the nub region is beginning to freeze.
FIG. 5B depicts the schematic representation of the mold-cavity system 200 adjusted to reduce
30 the internal pressure of the molten resin in the mold cavity after the nub region has frozen
sufficiently enough. Depicted is an example of how the internal pressure of the molten resin
was reduced, which is by moving the core portion 208 to the left side of the FIG. 5B. It should
be noted that the actual movement of the core portion 208 is exaggerated in Figure 5B for
illustration purposes. Within certain examples of implementation of embodiments of the
16
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present invention , it is expected that the movement can be within about 0.5 mm. In other
embodiments of the present invention , the movement can be within about 0 .2 mm to about 0.7
mm range. In other applications , the range of movement can be different and can be selected
based on some or all of the initial pressure within the molded article 103, volume of the
5 molded article 103 and the desired pressure drop to be obtained by implementing
embodiments of the present invention. Once the internal pressure is reduced to a much lower
pressure than what is associated with FIG. 5A (preferably zero pressure), the mold-cavity
system 200 is opened as soon as possible because the molded article 103 in the mold cavity is
still somewhat warm , so it would be advantageous at this time to permit the molded article
10 103 to be further cooled off by a post-cooling apparatus (not depicted but known).
FIG. 5C depicts an exploded perspective view of the mold-cavity system 200 of FIG. 4. The
core portion 208 includes a shoulder portion 251 that extends radially outward from a
longitudinal axis of the core portion 208. A spring 252 is positioned between the shoulder
15 portion 251 of the core portion 208 and a bottom surface 253 of the top portion 204. For
convenience, the spring 252 forms a disk shape with a passageway defined through the central
axis of the spring 252, and the central passageway of the spring 252 receives the core portion
208. A bolt 254 is positioned near a mounting bore 255. The bolt 254 is used to mount or
couple the top portion 204 to a plate assembly 260 (the plate assembly 260 is depicted in FIG.
20 6A). In operation, (i) the pressure-control system 126 is used to apply a force to the core
portion 208 and the force is large enough to overcome the biasing effect of the spring 252, so
that in effect the core portion 208 is actuatably moved or translated toward the top portion
204, and (ii) the pressure-control system 126 stops applying the force to the core portion 208
so that the spring 252 is then used to move the core portion 208 away from the top portion
25 204. The manner in which the pressure-control system 126 is connected with the core portion
208 is depicted in FIG. 6C.
FIG. 5D depicts a cross-sectional perspective view along the longitudinal axis of the moldcavity
system 200 of FIG. 4. The spring 252 is positioned between the bottom surface 253 of
30 the top portion 204 and the shoulder portion 251 of the core portion 208. The spring 252 abuts
the bottom surface 253 of the top portion 204 and the shoulder portion 251 of the core portion
208.
17
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FIG. 5E depicts a cross-sectional view through a longitudinal axis of the core portion 208 of
the mold-cavity system 200 of FIG. 4. The core portion 208 includes a bottom face 256
(which is tapered or cammed). The bottom face 256 is used to interface with the pressurecontrol
system 126, which is depicted in FIG. 6D. The core portion 208 defines a tube-
5 receiving bore 258 that is configured or sized to receive the cooling tube 241. The tubereceiving
bore 258 securely receives a tube mount 257, and the cooling tube 241 is connected
to the tube mount 257. The tube mount 257 securely positions the cooling tube 241 in the
tube-receiving bore 258 of the core portion 208. A plug 276 is securely received at the end of
the tube-receiving bore 258, and the plug 276 is offset from the tube mount 257. Between the
10 tube-receiving bore 258 and the plug 276 there is a cooling inlet 259 that receives a cooling
fluid (such as water), and the cooling fluid is made to flow into the cooling tube 241 and
toward a tip 261 (depicted in FIG. 5D) of the core portion 208. By way of example, the
bottom face 256 has a five degree taper.
15 F1GS. 6A, 6B, 6C, 6D, 6E, 6F, 6G depict the schematic representations of the pressure-control
system 126 used in the molding system 100 of FIG. 3.
FIG. 6A depicts a perspective view of a top side of the plate assembly 260 of the mold-cavity
system 200 of FIG. 4. The top portion 204 is bolted (securely connected) to the plate assembly
20 260. The plate assembly 260 defines a bore that receives the core portion 208. The tip 261 of
the core portion 208 extends outwardly from the plate assembly 260, while a bottom portion
of the core portion 208 remains within the bore defined by the plate assembly 260. The
pressure-control system 126 is connected to a side edge or a peripheral edge of the plate
assembly 260. Depicted in FIG. 6A is a non-limiting example in which two core portions 208
25 are connected to respective pressure-control systems 126. It will be appreciated that it is
possible to adapt or vary the configuration depicted in FIG. 6A such that a single pressurecontrol
system 126 may control two or more core portions 208.
FIG. 6B depicts a perspective view of a bottom side of the plate assembly 260 of the mold-
30 cavity system 200 of FIG. 4. The plate assembly 260 is formed or machined so that the plate
assembly 260 accommodates the pressure-control system 126. FIG. 6B depicts the pressurecontrol
system 126. FIG. 6B recessed into the plate assembly 260.
18 .
HA7371-2-WO
FIG. 6C depicts a perspective view of the pressure-control system 126 of FIG. 6A. For
convenience, the plate assembly 260 has been removed so as to permit a clearer view of the
pressure-control system 126. The pressure-control system 126 includes: (i) a housing 150, (ii)
a link 156, (iii) a wedge 157, and (iv) a coupler 158. The housing 150 defines or provides a
5 housing inlet 262 and a housing outlet 263, both of which are used to receive and expel a
hydraulic fluid, respectively. A bolt 254 is used to connect the pressure-control system 126 to
the plate assembly 260 (which is depicted in FIG. 6A). The link 156 extends out from the
housing 150, and the link 156 connects with the wedge 157. The coupler 158 couples the
wedge 157 with the core portion 208 of the mold-cavity system 200. The coupler 158 abuts a
10 surface of the plate assembly 260, and to locate or register the coupler 158 to the plate
assembly 260, a locating device 264 (such as a pin) is received by the coupler 158, and the
plate assembly 260 includes a bore that also receives the locating device 264. The coupler 158
defines bores that each receives respective bolts 254, and the bolts 254 are used to securely
connect the coupler 158 to the plate assembly 260. The coupler 158 defines a wedge-receiving
15 groove 265 that faces the plate assembly 260, and the wedge-receiving groove 265 receives, at
least in part, the wedge 157. The wedge 157 presents a surface 266 (which is tapered or
caromed) that touches the bottom face 256 (depicted in FIG. 5E) of the core portion 208. The
wedge 157 is slidable relative to the bottom face 256 of the core portion 208. it will be
appreciated that the wedge 157 and the coupler 158 and the core portion 208 are made of
20 suitable wear-resistant materials. A locating device 264 (also called a pin) extends from the
core portion 208. A groove (not depicted) is defined by the plate assembly 260, and the grove
slidably receives the locating device 264 that extends from the core portion 208, and the
locating device 264 permits linear movement of the core portion 208, and this linear
movement is along a direction that is aligned substantially perpendicular relative to the
25 alignment of the wedge 157. The locating device 264 of the core portion 208 permits slidable
- movement of the core portion 208 relative to the top portion 204 (the top portion 204 is
securely connected to the plate assembly 260 depicted in FIG. 6A).
The pressure-control system 126 operates, generally, in accordance with the following
30 approach: in operation, (i) while the mold cavity 213 is being filled, under pressure, with the
molding material and before the mold gate 216 is shut, the pressure-control system 126 is
actuated so as to apply pressure to the core portion 208, so that the mold cavity 213 maintains
a predefined volume. After the mold gate 216 is shut so as to isolate the mold cavity 213 from
the stream of molding material, the pressure-control system 126 is deactuated or de-energized
19
HA7371-2-WO
so as to remove pressure to the core portion 208, so that the volume of the mold cavity 213
becomes relatively larger and in this manner there is a pressure reduction realized in the mold
cavity 213 after the mold gate 216 is shut or closed.
5 In operation, the pressure-control system 126 operates under the following operational modes:
(i) an increase-pressure mode, or (ii) a decrease-pressure mode.
In the decrease-pressure mode, the pressure-control system 126 is actuated so that the link 156
is moved toward the housing 150, and in response the link 156 moves the wedge 157 toward
10 the housing 150, so that the surface 266 of the wedge 157 moves away from the bottom face
256 of the core portion 208, and in this manner the spring 252 (depicted in FIGS. 5C and 5D)
pushes the core portion 208 away from the top portion 204. The decrease-pressure mode is
enabled or executed after the mold gate 216 (depicted in FIG. 4) is held shut so as to isolate
the mold cavity 213 (isolating the mold cavity 213 means that the mold cavity 213 is fluidly
15 disconnected from the melt stream associated with the melt-preparation system 128, which is
depicted in FIG. 3), and in this manner the volume of the mold cavity 213 (also depicted in
FIG. 4) of the mold-cavity system 200 becomes larger; since (i) the mold gate 216 is held shut
during the decrease-pressure mode, and (ii) the volume of the mold cavity 213 is increased,
then the pressure in the mold cavity 213 becomes decreased, which is required in accordance
20 with mold-unpack instructions 520 that is depicted in FIG. 7.
In the increase-pressure mode, the pressure-control system 126 is actuated so that the link 156
is moved outwardly of the housing 150, and in response the link 156 moves the wedge 157
away from the housing 150, so that the surface 266 of the wedge 157 moves towards and
25 against the bottom face 256 of the core portion 208 , so that the spring 252 becomes
compressed because the core portion 208 is urged to move toward the top portion 204.
It will be appreciated that the increase-pressure mode may be used with different instructions
of the set of controller-executable instructions 500, which is depicted in FIG. 7, in accordance
30 with the following options:
A first option is to use or enable or execute the increase-pressure mode before the mold gate
216 (depicted in FIG. 4) is shut and while the mold cavity 213 remains not isolated (that is,
the mold cavity 213 remains fluidly connected with the melt stream associated with the melt-
20
HA7371-2-WO
preparation system 128, which is depicted in FIG. 3); in this manner, the volume of the mold
cavity 213 (depicted in FIG. 4) of the mold-cavity system 200 becomes smaller; since (i) the
mold gate 216 is held open during the decrease-pressure mode, and the melt-preparation
system 128 continues to apply pressure to pack out the mold cavity 213, and (ii) the volume of
5 the mold cavity 213 is decreased, then the pressure in the mold cavity 213 becomes increased,
which is required in accordance with a hold instructions 530, which is depicted in FIG. 7. It
will be appreciated that the melt-preparation system 128 continues to apply pressure to pack
out the mold cavity 213 while the mold cavity 213 remains not isolated (that is, the mold gate
216 is held open for this case) in the following manner, (by way of example): the screw
10 assembly 145 located in the barrel assembly 142 is urged forwardly so as to maintain pressure
on the melt located in the mold cavity 213 (since the mold gate 216 is held open for this case),
and this arrangement avoids the resin to become pushed back from the mold cavity 213 back
into the hot-runner system 300 as a result of the mold gate 216 being held open as the core
portion 208 is advanced to reduce the cavity volume of the mold-cavity system 200. It will be
15 appreciated that for this case, there is some other blockage located upstream in the melt stream
(to realize a packing process for this case).
A second option is to use or enable or execute the increase-pressure mode after the mold gate
216 (depicted in FIG. 4) is shut and the mold cavity 213 becomes isolated (that is, the mold
20 cavity 213 is fluidly disconnected from the melt stream associated with the melt-preparation
system 128, which is depicted in FIG. 3); in this manner, the volume of the mold cavity 213
(depicted in FIG. 4) of the mold-cavity system 200 becomes smaller; since (i) the mold gate
216 is held shut during the decrease-pressure mode, and (ii) the volume of the mold cavity
213 is decreased, then the pressure in the mold cavity 213 becomes increased, which is
25 required in accordance with a mold-volume reduction instructions 540, which is depicted in
FIG. 7.
FIG. 6D depicts a perspective cross-sectional view of the pressure-control system 126, which
further includes: (i) a hydraulic piston 151, (ii) a chamber 152, (iii) a stop 153, and (iv) a seal
30 154. The housing 150 receives the hydraulic piston 151. The chamber 152 is defined between
the housing 150 and the hydraulic piston 151. The stop 153 is received at one end of the
housing 150 so as to limit the travel of the hydraulic piston 151. The seal 154 is received in
the end of the housing 150 and the seal 154 is used to prevent leakage of a hydraulic fluid
received in the chamber 152. Movement of the core portion 208 occurs within the top portion
21
HA7371-2-WO
204 (also called a lock ring). In accordance with a non-limiting example, the wedge 157 is
used to hydraulically actuate movement of the core portion 208 of about 0.8 millimeters
(MM).
5 FIG. 6E depicts an exploded perspective view of the pressure-control system 126. The wedge
157 includes a wedge body 267 that provides the surface 266 (which is preferably a tapered
surface), and the wedge body 267 defines a wedge groove 268 that is sized so as to receive, at
least in part, the link 156. The link 156 includes a link body 269, a link head 270 that extends
from the link body 269, and a link shoulder 271 that is offset from the link head 270. The link
10 head 270 is received in the wedge groove 268, in this manner the link 156 is connected with
the wedge 157. A housing cover 272 is attached with the housing 150, and the housing cover
272 defines a central passageway that permits the link 156 to be connected with the hydraulic
piston 151 (as depicted in FIG. 6F).
15 FIG. 6F depicts a cross sectional perspective view of the pressure-control system 126, in an
assembled state.
FIG. 6G depicts a partial cross-sectional view of the pressure-control system 126. The plate
assembly 260 includes a plate body 273. The plate body 273 defines a cooling circuit 275,
20 which receives a cooling fluid in operation so as to maintain the temperature of the moldcavity
system 200. The plate body 273 also defines a wedge cavity 274 that is configured or
sized so as to receive and accommodate the wedge 157 and the pressure-control system 126.
FIG. 7 depicts the schematic representation of the set of controller-executable instructions 500
25 having instructions for operating the molding system 100 of FIG. 3. The set of controllerexecutable
instructions 500 includes (but is not limited to): mold-unpack instructions 520. The
set of controller-executable instructions 500 also includes (but is not limited to) other
instructions, such as: (i) melt-preparation instructions 502, (ii) mold-close instructions 504,
(iii) mold-lock instructions 506, (iv) tonnage-engage instructions 508, (v) melt-stream
30 connection instructions 510, (vi) mold-injection instructions 512, (vii) mold-pack instructions
514, (viii) melt-stream disconnection instructions 516, (ix) heat-reduction instructions 518, (x)
tonnage-disengage instructions 522, (xi) mold-unlock instructions 524 and , (xii) mold-open
instructions 526. It will be appreciated that the instructions 500 may be executed either in a
parallel manner or a serial manner as known to those skilled in the art of processors.
22
HA7371-2-WO
The melt-preparation instructions 502 include instructing the controller 160 to control the
melt-preparation system 128, which is depicted in FIG. 3, to convert the molding material 101
into a stream of flowable-molding material. The melt-preparation instructions 502 may be
5 executed by actuating the melt-preparation system 128 (also called an extruder, etc) having the
screw assembly 145 in the barrel assembly 142 that is connected to the hopper 140 configured
to receive granules of the molding material 101. The screw assembly 145 rotates in the barrel
assembly 142 so as to convert the molding material 101 into the stream of flowable-molding
material. The barrel assembly 142 has the machine nozzle 144 connected with the mold-cavity
10 system 200, either via: (i) a hot-sprue apparatus (for the case where a single cavity is to be
filled, under pressure, with the stream of flowable-molding material), or (ii) a hot-runner
system (for the case where multiple cavities need to be filled, under pressure, with the stream
of flowable-molding material). It will be appreciated that the stream of flowable-molding
material does not flow in a continuous manner but in an intermittent (on and off) manner.
15
The mold-close instructions 504 include instructing the controller 160 to control the platen
actuator 120, which is depicted in FIG. 3, to move the movable platen 104 toward the
stationary platen 102 thereby shutting the mold-cavity system 200 in a closed or shut state,
and once closed the mold-cavity system 200 defines the mold cavity 213.
20
The mold-lock instructions 506 include instructing the controller 160 to control the bar locks
121, which are depicted in FIG. 3, to lock the movable platen 104 and the platen bars 106 so
that the mold-cavity system 200 is locked, and in effect the portions of the mold-cavity system
200 do not move relative to each other when the mold-cavity system 200 is injected, under
25 pressure, with the stream of flowable-molding material. The mold-lock instructions 506 may
be executed by engaging the bar locks 121 so that the platens 102, 104 do not move relative to
each other; specifically, this arrangement may be achieved, for example, by locking the platen
bars 106 to the movable platen 104.
30 The tonnage-engage instructions 508 include instructing the controller 160 to control the
clamp assemblies 122 (depicted in FIG. 3) to apply the clamp tonnage to the mold-cavity
system 200 via the platen bars 106 after the mold-cavity system 200 is closed shut and locked.
The tonnage-engage instructions 508 may be executed by pressurizing the clamp assemblies
23
HA7371-2-WO
122 to apply the clamp tonnage to the mold-cavity system 200 via the platens 102, 104 and the
platen bars 106.
The melt-stream connection instructions 510 include instructing the controller 160 to control
5 the melt-preparation system 128 (depicted in FIG. 3) to connect the mold-cavity system 200 to
the stream of flowable-molding material, so that the stream of flowable-molding material may
flow into the mold-cavity system 200. The melt-stream connection instructions 510 may be
executed by opening the mold gate 216 leading into the mold-cavity system 200.
10 The mold-injection instructions 512 include instructing the controller 160 to control the meltpreparation
system 128 (depicted in FIG. 3) to inject a portion of the stream of flowablemolding
material into the mold-cavity system 200 while the clamp tonnage maintains the
mold-cavity system 200 closed. The mold-injection instructions 512 may be executed by
translating the screw of the screw assembly 145 of the melt-preparation system 128 toward the
15 stationary platen 102.
The mold-pack instructions 514 include instructing the controller 160 to control any one of
the following options: (option i) the melt-preparation system 128, which is depicted in FIG. 3,
or (option ii) the melt-preparation system 128 and the pressure-control system 126 (depicted
20 in FIG. 3) to apply an additional pressure to the molding material 101 contained in the moldcavity
system 200 while the molding material 101 becomes cooled, at least in part, in the
mold-cavity system 200. The mold-pack instructions 514 are executed while the mold gate
216 is open (specifically, the mold-pack instructions 514 are executed before the mold gate
216 is closed). The purpose of the mold-pack instructions 514 is to compensate for shrinkage
25 of the molding material held in the mold cavity 213 as a result of the molding material cooling
down. For option (i), the melt-preparation system 128 applies the additional pressure to. the
molding material 101 contained in the mold-cavity system 200 while the mold gate 216 is
held open by forcing the screw assembly 145 to apply additional pressure to the molding
material. For option (ii), both the melt-preparation system 128 and the pressure-control system
30 126 to apply the additional pressure to the molding material 101 contained in the mold-cavity
system 200 while the mold gate 216 is held open.
The melt-stream disconnection instructions 516 include instructing the controller 160 to
control the melt-preparation system 128 (depicted in FIG. 3) to disconnect the mold-cavity
24
I-A7371-2-WO
system 200 from the stream of flowable-molding material; in this manner the mold-cavity
system 200 becomes isolated from the stream of flowable-molding material after the moldcavity
system 200 has received the portion of the stream of flowable-molding material (and
the molding material in the mold cavity 213 has been packed in before the mold gate 216 is
5 closed). The melt-stream disconnection instructions 516 may be executed by closing the mold
gate 216 by using gate valves, gate nozzles, etc.
The heat-reduction instructions 518 include instructing the controller 160 to control the moldcooling
system 124 (depicted in FIG. 4) to remove heat from the molding material 101
10 received in the mold-cavity system 200 after the mold-cavity system 200 has been
disconnected from the stream of flowable-molding material (so that the mold-cavity system
200 becomes isolated from the stream of flowable-molding material); in response to the above
instruction, solidification of the molding material 101 occurs in a gate portion 212 of the
mold-cavity system 200 so that the molded article 103 may be removed from the mold cavity
15 213 of the mold-cavity system 200.
The mold-unpack instructions 520 include instructing the controller 160 to control the
pressure-control system 126 to reduce, after solidification, at least in part, of the molding
material 101 that is located in a nub region 214 of the mold-cavity system 200, internal
20 pressure of the molding material 101 that is received in the mold-cavity system 200 while the
mold-cavity system 200 remains isolated from a stream of flowable-molding material. The
reduction of the internal pressure of the molding material 101 that is received in the moldcavity
system 200 while the mold-cavity system 200 remains isolated from the stream is
beyond any reduction of the internal pressure in the molding material 101 resulting from
25 cooling of the molding material 101. The technical effect is that the reduction in the internal
pressure of the molding material 101 is enough to permit safe opening of the mold-cavity
system 200 while permitting safe extraction of the molded article 103 from the mold-cavity
system 200.
30 The mold-unpack instructions 520 include instructing the controller 160 to control the
pressure-control system 126 (depicted in FIG. 6) to reduce, after solidification, at least in part,
of the molding material 101 located in a nub region 214 of the mold-cavity system 200,
internal pressure of the molding material 101 received in the mold-cavity system 200 beyond
any reduction of the internal pressure in the molding material 101 as a result of cooling of the
25
HA7371-2-WO
molding material 101; the reduction in the internal pressure of the molding material 101 is
enough to permit safe opening of the mold-cavity system 200. It will be appreciated that the
mold-unpack instructions 520 may be executed once the nub region 214 has solidified
sufficiently enough and the molded article 103 may be solidified sufficiently enough so as to
5 be conveniently removed from the mold-cavity system 200. If the mold-unpack instructions
520 are executed before the molded article 103 has had sufficient time to cool down, it may be
too difficult to remove the molded article 103 article from the mold cavity 213 because the
molded article 103 has not become solidified enough for handling (that is, removal from the
mold cavity 213). The mold-unpack instructions 520 may be executed in accordance with an
10 aggressive manner (as depicted in FIG. 813) or in accordance with a relaxed manner (as
depicted in FIG. 8A), depending on the specifics of the geometry of the molded article 103,
the mold-cavity system 200, the molding system 100, etc. It is recommended to use a trial and
error approach to find the most appropriate time to begin execution of the mold-unpack
instructions 520.
15
The tonnage-disengage instructions 522 include instructing the controller 160 to control the
clamp assemblies 122 (depicted in FIG. 3) to disengage the clamp tonnage from the moldcavity
system 200. The tonnage-disengage instructions 522 may be executed by to
disengaging or depressurizing the clamp assemblies 122 so as to stop application of the clamp
20 tonnage to the mold-cavity system 200 via the platens 102, 104 and the platen bars 106.
The mold-unlock instructions 524 include instructing the controller 160 to control the bar
locks 121 (depicted in FIG. 3) to unlock the movable platen 104 and the platen bars 106 so
that the mold-cavity system 200 may be unlocked. The mold-unlock instructions 524 may be
25 executed by unlocking the bar locks 121 so that the platens 102, 104 can be moved relative to
each other so as to separate the mold-cavity system 200 (and thus be able to remove the
molded article 103 from the mold-cavity system 200).
The mold-open instructions 526 include instructing the controller 160 to control the movable
30 platen 104 (depicted in FIG. 3) to away from the stationary platen 102 thereby open the moldcavity
system 200, so that a molded part made in the mold-cavity system 200 may be removed
from the mold-cavity system 200 (either manually or by robot assembly, which is not depicted
but known).
26
HA7371-2-WO
FIG. 7 also depicts a first non-limiting variation 590 of the set of controller-executable
instructions 500: variations may be made to: (i) the mold-pack instructions 514, (ii) the meltstream
disconnection instructions 516, and (iii) the mold-unpack instructions 520.
Specifically, the mold-pack instructions 514 may be varied so as to further include: hold
5 instructions 530, and compensation instructions 531.
In accordance with the first non-limiting variation 590, the hold instructions 530 include
instructing the controller 160 to control the molding system 100 to apply and hold the pressure
to the molding material 101 being contained in the mold-cavity system 200 while the molding
10 material 101 remains in a semi-solid state in the mold-cavity system 200 ; the hold instructions
530 may be executed by using the screw assembly 145 and maintaining the mold gate 216
open.
In accordance with the first non-limiting variation 590, the compensation instructions 531
15 include instructing the controller 160 to control the molding system 100 to inject an additional
amount of the molding material 101 into the mold-cavity system 200 while the molding
material 101 in the mold -cavity system 200 remains in the semi-solid state; the additional
amount of the molding material 101 compensates for shrinkage of the molding material 101
received in the mold-cavity system 200; the compensation instructions 531 may be executed
20 by using the screw assembly 145, and keeping the mold gate 216 open; the compensation
instructions 531 are executed during the hold cycle. The hold cycle is used to compensate for
density change of the molding material 101 by adding molding material 101, under the
pressure, and permitting freezing of the nub portion 107 of the molded article 103. The nub
portion 107 is also called the "melt injection point".
25
In accordance with the first non-limiting variation 590, the melt-stream disconnection
instructions 516 are executed: (i) after the mold-pack instructions 514 are executed so that the
mold-cavity system 200 becomes isolated from the stream of flowable molding material, and
(ii) before the mold-unpack instructions 520 are executed.
30
In accordance with the first non-limiting variation 590, the mold-unpack instructions 520
further include: mold-volume increase instructions 532. The mold-volume increase
instructions 532 include instructing the controller 160 to control the pressure-control system
126 of the molding system 100 to increase the volume of the mold cavity 213 of the mold-
27
HA7371-2-WO
cavity system 200. Increasing the volume of the mold cavity 213 reduces the pressure within
the molding material 101 received in the mold-cavity system 200 while: (i) the molding
material 101 remains in the semi-solid state in the mold-cavity system 200, and (ii) the mold
cavity 213 remains isolated from the stream of the molding material; an internal pressure of
5 the molded article 103 is relieved by increasing effective volume of the mold cavity 213, and a
reduction of the pressure is accomplished by waiting for the molded article 103 to cool and
actively increasing the volume of the mold cavity 213. The result is a reduction in cycle time
instead of waiting for the molded article 103 to shrink and cool off in the mold cavity 213.
This arrangement provides an opportunity to decrease the pressure by allowing the volume of
10 the mold cavity 213 to increase.
FIG. 7 also depicts a second non-limiting variant 592 of the set of controller-executable
instructions 500: variations may be made to: (i) the melt-stream disconnection instructions
516, (ii) the mold-pack instructions 514, and (iii) the mold-unpack instructions 520.
15
In accordance with the second non-limiting variant 592, the melt-stream disconnection
instructions 516 are executed: (i) before the mold-pack instructions are executed, and (ii)
before the mold-unpack instructions 520 are executed.
20 In accordance with the second non-limiting variant 592, the mold-pack instructions 514
further include mold-volume reduction instructions 540. The mold-volume reduction
instructions 540 include instructing the controller 160 to control the pressure -control system
126 to decrease a volume of the mold cavity 213, so that the additional pressure is applied to
the molding material 101 received in the mold-cavity system 200 while the molding material
25 101 remains in a semi-solid state in the mold-cavity system 200, so that a size of the volume
of the mold cavity 213 is reduced and the molding material 101 located in the mold cavity 213
is compressed, so that density of the molding material 101 located in the mold-cavity system
200 increases. This arrangement may be accomplished, for example, by moving the core
portion 208 toward the mold gate 216, or other suitable mechanism, such as the mechanisms
30 described in US Patent Number 7293981.
In accordance with the second non-limiting variant 592, the mold-unpack instructions 520
further include: mold-volume increase instructions 542. The mold-volume increase
instructions 542 include instructing the controller 160 to control the pressure -control system
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126 to increase the volume of the mold cavity 213, so that an internal pressure of the molding
material 101 contained in the mold-cavity system 200 is reduced while the molding material
101 remains in the semi-solid state in the mold-cavity system 200, so that the molding
material 101 located in the mold-cavity system 200 becomes decompressed and the density of
5 the molding material 101 decreases by expanding the volume of the mold cavity 213 before
the mold-cavity system 200 is opened sufficiently so as to remove the molded article 103 and
while the mold-cavity system 200 remains isolated from the stream of the molding material
101. For example, this arrangement may be executed by having the core portion 208 moving
away from the mold gate 216 by using the mechanism described in US Patent Number
10 7293981.
FIGS. 8A and 813 depict schematic representations of graphs 401 and 501, respectively,
having a cycle time 499 and a cycle time 599, respectively, superimposed on modified PVT
curves 26, 28 of the PET resin of FIG. 2.
15
FIG. 8A depicts an example of using the set of controller-executable instructions 500 of FIG.
7. The graph 420 has a molding operation 480 superimposed on the modified PVT curves 26,
28 of FIG. 2. It will be appreciated that the graph 420 depicts flipped versions of the known
PVT curves 16, 18 depicted in FIG. 1. Specifically, the modified PVT curves 26, 28 of FIG.
20 8A are the flipped versions (that is, flipped side to side) of the known PVT curves 16, 18 of
FIG. 1, respectively. The arrangement depicted in FIG. 8A permits the depiction of time as
increasing from the left side to the right side of the graph 420, and that the cycle of the
molding system 100 may be better understood when time is depicted in this fashion. The
graph 420 includes a time axis 418 aligned along a horizontal direction of the graph 420 (that
25 is, located along the bottom side of the graph 420) and increasing from the left side to the
right side of FIG. 2. The graph 420 also includes the specific volume axis 414 aligned along a
vertical direction of the graph 420 (that is, located on the left side of the graph 420), and
increasing from the bottom side to the top side of FIG. 2. The graph 420 also includes the
temperature axis 412 aligned the horizontal direction of the graph 420 (that is, located along
30 the top side of the graph 420), and increasing from the right side to the left side of FIG. 2.
Along the top of the graph 420 there is depicted the operations of the molding system 100 of
FIG. 1. An operation 430 of the molding system 100 includes (more or less): an operation
431, an operation 432, an operation 433, an operation 434, an operation 435, an operation 436,
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an operation 437, and an operation 438. The operations 431 to 438 are depicted along the top
side of FIG. 8A. The modified PVT curve 28 is used to describe the characteristics of the
known PET resin during the operations 431, 432, 433, 434 and 435.
5 The operation 431 includes closing a mold cavity. The operation 432 includes locking the
mold cavity shut and pressurizing a clamp assembly so as to apply clamp tonnage to the mold
assembly. The operation 433 includes injecting melted resin into the mold cavity volume of
the mold assembly; it will be appreciated that the operation 433 is sometimes known as the
"fill" cycle. The operation 434 includes slowly adding the melted resin to maintain a full
10 cavity volume; it will be appreciated that the operation 434 is also known as the "hold" cycle.
The operation 434 provides compensation for the pressure change of the melt in the mold
cavity as the temperature drops for the molding material; specifically, as the temperature drops
the tendency is for the pressure to drop but the operation 434 is used to increase of the density
of the molten resin during the operation 434. Typically, at the end of the hold cycle or the
15 operation 434, the operation 435 is executed; the operation 435 includes shutting off the mold
cavity or isolating the mold cavity; the operation 435 is sometimes referred to as the "shut-off
cycle".
The operation 435 includes moving a valve stem into a mold gate that leads into the mold
20 cavity, and the valve stem is used to stop further movement of the molten resin into and out
from the mold cavity (via the mold gate); when sufficient plastic density change has occurred,
the molded part can be cooled down and removed from the mold cavity without, ideally, the
molded article suffering from shrinkage related deformation. The operation 435 occurs at a
point 421. The characteristics of the PET resin during operation 436 are described by a
25 horizontally aligned line extending between a point 421 and a point 423. The point 423 is the
point at which the mold-unpack instructions 520 are executed (so that the pressure in the mold
cavity 213 is reduced after the mold gate 216 is closed and the mold cavity 213 is isolated
form the stream of molding material). The specific volume of the molding material located
inside the mold cavity 213 will now increase from point 423 to point 425 (as a result of the
30 reduction in pressure). The point 421 and the point 425 represent terminus points for a
beginning and an ending of the operation 436. The horizontal line (that extends between the
point 421 and the point 423) is used is because a volume of the mold cavity 213 does not
increase or decrease during this portion of the operation 436, and therefore the volume of the
molten resin in the mold cavity does not change during this portion of the operation 436.
30
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However, between the point 423 and the point 425 the pressure in the mold cavity 213 is
decreased during this portion of the operation 436 (in sharp contrast to the operation 36 of
FIG. 2). At a region 441 the nub portion 107 of the molded article 103 is considered to be
solidified enough so as to permit safe removal of the molded article 103 from the mold cavity
5 213 (the molded article 103 is removed in a hot condition from the mold cavity 213). At a
region 439, the internal pressure of the molded article 103 is near or at zero pressure, so that
unlocking of the bar locks 121 would not cause the mold-cavity system 200 to inadvertently
pop open (thus avoiding potential damage to the mold-cavity system 200).
to The modified PVT curve 26 is used to describe the characteristics of the known PET resin
during the operation 437 and the operation 438. The operation 437 includes depressurizing a
clamp assembly and unlocking a mold assembly. Since the internal pressure of the resin in the
mold cavity has reduced to near zero or preferably zero pressure, there is little or no danger of
popping open the mold assembly (this is the preferred situation so that the mold assembly is
15 not inadvertently damaged by allowing it to pop open under pressure). The operation 438
includes removing the molded article formed in the mold cavity, and then passing the molded
article to a post mold cooling apparatus for further temperature reduction if so desired.
The cycle time 499 is depicted along the time axis 418, and it will be appreciated that the
20 cycle time 499 is less than the known cycle time 30 depicted in FIG. 2. It will be appreciated
that the PVT curves and the cycle time 499 are not accurately drawn, but were drawn for
illustrative purposes for ease of explaining the concepts. Time 445 represents the amount of
time saved or reduced in the cycle time in comparison to the known cycle time 30 of FIG. 2. It
will be appreciated that the amount of time 443 (that is, the mold unpack time) used during
25 the mold-unpack instructions 520 can vary in accordance to the conditions that may be
required to ensure production of a molded article 103.
FIG. 8B represents a cycle time 599 (that is considered to be more aggressive than the cycle
time depicted in FIG. 8A) corresponding with an aggressive cycle operation 580 for the
30 molding system 100 of FIG. 1. The points 521, 523 and 525 correspond with the points 421,
423 and 425 of FIG. 8A, respectively. The point 523 is moved closer to the point 521 (while
the point 423 is further away from the point 421, in relative terms). Similarly, the point 525 is
moved closer to the point 521 (while the point 425 is further away from the point 421, in
relative terms). It will be appreciated that under the scenario depicted in FIG. 8B, the molded
31
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article 103 removed from the mold cavity 213 will be hotter than the molded article 103
moved out from the mold cavity 213 under the scenario depicted in FIG. 8A. The cycle time
599 is depicted along the time axis 519, and it will be appreciated that the cycle time 599 is
less than the cycle time 499 depicted in FIG. 8A. Time 545 represents the amount of time
5 saved or reduced in the cycle time in comparison to the known cycle time 30 of FIG. 2. It will
be appreciated that the amount of time 543 used during the mold-unpack instructions 520 can
vary in accordance to the conditions that may be required to ensure production of a molded
article 103.
10 With reference to FIGS. 9A and 9B another non-limiting embodiment of the present invention
will be described. FIG 9A depicts a schematic representation of the mold-cavity system 200
having the molding material 101 after the gate is shut, and the nub region is beginning to
freeze. The mold-cavity system 200 can be said to depict two parting lines (amongst others)
between various components of a molding stack forming the mold-cavity system 200. More
15 specifically, there can be said to be a "primary parting line" which is depicted as the witness
line 224, discussed in greater detail herein above. There is also depicted a "secondary parting
line" depicted as the parting line 222, also discussed herein above. Accordingly, it can be said
that within the depiction in FIGS. 9A and 9B, the primary parting line is defined between the
cavity portion 210 and the neck portion 206 and the secondary parting line is defined between
20 the neck portion 206 and the top portion 204.
FIG. 9B depicts the mold-cavity system 200 during initial stages of a mold open operation.
Generally speaking, the initial stages of the mold open operation occur at the end of the socalled
"process portion" of the molding cycle, which generally includes filling, holding and
25 cooling operations. As such, the initial stages of the mold open operation can be implemented
at the end of the in-mold cooling cycle or, in other words, at the end of the molding cycle
when the mold-cavity system 200 is ready to be opened.
More specifically, it can be seen that during the initial stages of the mold open operation (but
30 prior to unclamping of the mold-cavity system 200 or, put another way, while maintaining at
least some of the clamping force), the stack components of the mold-cavity system 200 are
first separated relative to the secondary parting line, while the primary parting line is kept unopened.
32
1-1A7371-2-WO
More specifically, prior to the release of clamp tonnage (i.e. while maintaining at least some
of the clamp force), the controller 160 can activate an ejector actuator (not depicted), which is
configured to actuate a stripper assembly (not depicted) to which the neck portion 206 of the
mold-cavity system 200 is coupled to. As is known to those of skill in the art, the ejector
5 actuator can include push-pull or push rods, coupled to suitable actuation structures. Within
the embodiments of the present invention, during the initial stages of mold opening, the
primary parting line can be kept un-opened by urging the neck portion 206 towards the cavity
portion 210, which can be achieved by activating ejector actuator to urge the neck portion 206
towards the cavity portion 210. It is noted that within these embodiments of the present
10 invention, the ejector actuator has to exert enough force to keep the neck portion 206 urged
towards the cavity portion 210. It is also noted that the ejector actuator is actuated while at
least a portion of the clamp force is still being applied.
Within the architecture of FIGS. 9A and 9B, it is possible to implement a non-limiting
15 embodiment of a method for opening the mold-cavity system 200. It will be recalled that the
controller 160 (schematically depicted in FIG. 9B, but which can be implemented similarly to
the illustration in FIG. 3) houses the controller-usable memory 162 tangibly embodying a set
of controller-executable instructions 500 being configured to direct the controller 160.
20 Within these embodiments, the set of controller-executable instructions 500 includes a moldopen
instruction 902. The mold-open instruction 902 is configured to cause activation of the
ejector actuator to urge the neck portion 206 towards the cavity portion 210, such that to urge
the neck'portion 206 towards the cavity portion 210 in order to keep the primary parting line
un-opened. The mold-open instruction 902 is further configured to cause the mold-moving
25 actuator (not depicted) to cause the clamp to reduce and/or cease applying clamp force.
It is noted that in some embodiments of the present invention, the actions of activation of
ejector actuator and ceasing application of the clamp force can be triggered substantially
simultaneously. In other embodiments, one can be triggered after another, as long as the
30 ejector actuators are actuated and are capable of applying sufficient force to urge neck portion
206 towards the cavity portion 210 at the point in time when the clamp force falls below the
plastic pressure in the molded article 103 (i.e. before clamp force falls under plastic pressure
value that is sufficient to cause the mold-cavity system 200 to open relative to the primary
parting line if the neck portion 206 was not being urged towards the cavity portion 210).
35
33
HA7371-2-WO
At a point in time thereafter and, more specifically, at the point in time when the clamp force
is reduced sufficiently to enable safe opening of the mold-cavity system 200, the mold-open
instruction 902 is further configured to cause the mold-cavity system 200 to open vis-a-vis the
primary parting line in a normal fashion to implement removal of the molded article 103 from
5 the mold-cavity system 200. This, in turn, can be implemented by either (a) de-activation in
case of push rods or (b) activation in an opposite direction in case of the push pull rods of the
ejector actuator, to urge the neck portion 206 away from the cavity portion 210, at which point
standard operation of the neck portion 206 can be implemented, i.e. lateral opening of the split
mold inserts forming the neck portion 206 by use of cams, servo motors or other suitable
10 actuators. A technical effect of these embodiments of the present invention may include fewer
part defects attributable to the mold-opening function. Another technical effect of these
embodiments of the present invention may include reduction of the internal pressure
associated with the molded article 103.
Even though embodiments of the present invention have been described with reference to
15 actuating of ejector actuators, this needs not be so in every embodiment of the present
invention. For example, in an alternative embodiment of the present invention, a separate
actuator (not depicted) can be used to urge neck portion 206 towards the cavity portion 210.
An example of such a separate actuator may include, for example, an actuator based on active
material (such as piezo-electric actuator, an example of which is described in co-owned US
20 patent 7,293,981 issued to Niewels on November 13, 2007.
Within non-limiting embodiments described above, it is contemplated that the core portion
208 can be moved away from the cavity portion 210 in order to execute various embodiments
of the present invention. The degree of such movement will vary, depending on the specific
25 implementation. However, what is noteworthy is that the degree of movement within
previously described embodiments is such that only some molecules of the plastic of the
molded article 103 that abut with the core portion 208 will move relative to the core portion
208, while others of the molecules of the plastic of the molded article 103 that abut with the
core portion 208 will not move or, in a sense, they "stick" in their relative position on the core
30 portion 208.
In alternative non-limiting embodiments of the present invention, it is contemplated that the
core portion 208 can be moved away from the cavity portion 210 by a distance sufficient to
displace the totality of molecules of the plastic of the molded article 103 that abut with the
35 core portion 208 from their relative positioning during the process cycle, the displacement
34
HA7371-2-WO
being in substantially the same direction. This movement can be executed while maintaining
at least some of the clamping force. For the avoidance of doubt, by term "maintaining at least
some clamping force" inventors contemplate maintaining clamping force such that the sum of
the clamping force and the friction between the molded article 103 and the core portion 208 is
5 less than the ejector force (i.e. force exerted by the ejector actuator).
This is illustrated in more detail with reference to FIG 10A and FIG lOB, in which FIG 10A
depicts a schematic representation of the mold-cavity system 200 having the molded article
103 with its molecules being in a position relative to the core portion 208 which can be
10 generally called "positioning during the process cycle" and FIG 10B depicts a schematic
representation of the mold-cavity system 200 having the molded article 103 after the core
portion 208 has been moved away from the cavity portion 210 by a distance sufficient to
displace the totality of molecules of the plastic of the molded article 103 that abut with the
core portion 208 from their relative positioning during the process cycle, the displacement
15 being in substantially the same direction (this direction of displacement being right-bound as
viewed in FIG 10B). It is noted that within this illustration, the mold-cavity system 200 has
been effectively opened relative to what was referred before as the "secondary parting line".
However, this needs not be so in every embodiment of the present invention. For example, in
alternative embodiments of the present invention, the mold-cavity system 200 can be opened
20 similarly to the illustration in FIG 5A and 5B.
Effectively, by executing this movement, a part pre-eject function can be executed, while the
molded article 103 maintains most contact with the cavity portion 210 and the neck portion
206. A specific technical effect attributable to these embodiments of the present invention
25 may include avoidance of part defect known as "rolled necks" (which is a name used for
certain deformations to the neck finish of the molded article 103), due at least partially to
executing the pre-eject function while maintaining the contact between the molded article 103
and the neck portion 206.
30 Within these embodiments of the present invention, the exact magnitude of the travel distance
will depend on several parameters, such as for example, the inside draft angle associated with
the molded article 103, i.e. the draft angle on the inner skin that abuts with the core portion
208.
35
HA7371-2-WO
The description of the non-limiting embodiments provides non-limiting examples of the
present invention; these non-limiting examples do not limit the scope of the claims of the
preselif invention. The non-limiting embodiments described are within the scope of the claims
of the present invention. The non-limiting embodiments described above may be: (i) adapted,
5 modified and/or enhanced, as may be expected by persons skilled in the art, for specific
conditions and/or functions, without departing from the scope of the claims herein, and/or (ii)
further extended to a variety of other applications without departing from the scope of the
claims herein. It is understood that the non-limiting embodiments illustrate the aspects of the
present invention. Reference herein to details and description of the non-limiting
10 embodiments is not intended to limit the scope of the claims of the present invention. Other
non-limiting embodiments, which may not have been described above, may be within the
scope of the appended claims. It is understood that: (i) the scope of the present invention is
limited by the claims, (ii) the claims themselves recite those features regarded as essential to
the present invention, and (ii) preferable embodiments of the present invention are the subject
15 of dependent claims. Therefore, what is protected by way of letters patent is limited only by
the scope of the following claims:
36
HA7371-2-WO
WHAT IS CLAIMED IS:
1. A molding system (100) being configured to manufacture a molded article (103) in a
mold-cavity system (200) by using a molding material (101), the molding system (100)
comprising:
a pressure-control system (126) being coupled with the mold-cavity system (200); and
a controller (160) operatively coupling to the pressure-control system (126), the
controller (160) having a controller-usable memory (162) tangibly embodying a set of
controller-executable instructions (500) being configured to direct the controller (160), the set
of controller-executable instructions (500) including:
mold-unpack instructions (520), including instructing the controller (160) to
control the pressure-control system (126) to reduce, after solidification, at least in part,
of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the moldcavity
system (200) while the mold-cavity system (200) remains isolated from a stream
of flowable-molding material, beyond any reduction of the internal pressure in the
molding material (101) resulting from cooling of the molding material (101), so that the
reduction in the internal pressure of the molding material (101) is enough to permit safe
opening of the mold-cavity system (200) while permitting safe extraction of the molded
article (103) from the mold-cavity system (200).
2. A molding system (100) being configured to manufacture a molded article (103) by
using a mold-cavity system (200) and using a molding material (101), the molding system
(100) comprising:
a group of controllable systems (108), including:
a mold-cooling system (124) being configured to couple with the mold-cavity
system (200);
a pressure-control system (126) being configured to couple with the mold-cavity
system (200);
a melt-preparation system (128) being configured to couple with the mold-cavity
system (200); and
a controller (160) being operatively coupling to the group of controllable systems (108),
the controller (160) having a controller-usable memory (162) tangibly embodying a set of
controller-executable instructions (500) being configured to direct the controller (160) to
37
I A7371-2-WO
control operation of the molding system (100), the set of controller-executable instructions
(500) including:
melt-stream disconnection instructions (516), instructing the controller (160) to
control the melt-preparation system (128) to disconnect the mold-cavity system (200)
from a stream of flowable-molding material, so that the mold-cavity system (200)
becomes isolated from the stream of flowable-molding material after the mold-cavity
system (200) has received a portion of the stream of flowable-molding material;
heat-reduction instructions (518), instructing the controller (160) to control the
mold-cooling system (124) to remove heat from the molding material (101) being
received in the mold-cavity system (200) after the mold-cavity system (200) has been
disconnected from the stream of flowable-molding material so that the mold-cavity
system (200) becomes isolated from the stream of flowable-molding material, and in
response solidification of the molding material (101) occurs in a gate portion (212) of
the mold-cavity system (200) so that the molded article (103) may be removed from the
mold-cavity system (200); and
mold-unpack instructions (520), including instructing the controller (160) to
control the pressure-control system (126) to reduce, after solidification, at least in part,
of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the moldcavity
system (200) while the mold-cavity system (200) remains isolated from the
stream of flowable-molding material, beyond any reduction of the internal pressure in
the molding material (101) resulting from cooling of the molding material (101), so that
the reduction in the internal pressure of the molding material (101) is enough to permit
safe opening of the mold-cavity system (200) while permitting safe extraction of the
molded article (103) from the mold-cavity system (200).
3. The molding system (100) of claim 2, wherein:
the set of controller-executable instructions (500) further include:
mold-pack instructions (514), instructing the controller (160) to control any one
of. (i) the melt-preparation system (128), and (ii) the melt-preparation system (128) and
the pressure-control system (126) to reduce a pressure to the molding material (101)
being contained in the mold-cavity system (200) while the molding material (101)
becomes cooled, at least in part, in the mold-cavity system (200);
the mold-pack instructions (514) include:
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HA7371-2-WO
hold instructions (530), instructing the controller (160) to control the molding
system (100) to apply and hold the pressure to the molding material (101) being
contained in the mold-cavity system (200) while the molding material (104) remains in a
semi-solid state in the mold-cavity system (200); and
compensation instructions (531),1 instructing the controller (160) to control the
molding system (100) to inject an additional amount of the molding material (101) into
the mold-cavity system (200) while the molding material (101) in the mold-cavity
system (200) remains in the semi-solid state, and the additional amount of the molding
material (101) compensating for shrinkage of the molding material (101) being received
in the mold-cavity system (200);
the melt-stream disconnection instructions (516) are executed: (i) after the moldpack
instructions (514) are executed so that the mold-cavity system (200) becomes
isolated from the stream of flowable-molding material, and (ii) before the mold-unpack
instructions (520) are executed; and
the mold-unpack instructions (520) further include:
mold-volume increase instructions (532), instructing the controller (160) to
control the pressure-control system (126) to increase a volume of a mold cavity (213) of
the mold-cavity system (200), the mold cavity (213) receiving the molding material
(101), increasing the volume of the mold cavity (213) reduces the pressure within the
molding material (101) being received in the mold-cavity system (200) while: (i) the
molding material (101) remains in the semi-solid state in the mold-cavity system (200),
and (ii) the mold cavity (213) remains isolated from the stream of the molding material.
4. The molding system (100) of claim 2, wherein:
the set of controller-executable instructions (500) further include:
mold-pack instructions (514), instructing the controller (160) to control any one
of. (i) the melt-preparation system (128), and (ii) the melt-preparation system (128) and
the pressure-control system (126) to reduce a pressure to the molding material (101)
being contained in the mold-cavity system (200) while the molding material (101)
becomes cooled, at least in part, in the mold-cavity system (200);
the melt-stream disconnection instructions (516) are executed: (i) before the moldpack
instructions (514) are executed, and (ii) before the mold-unpack instructions (520)
are executed;
the mold-pack instructions (514) further include:
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HA7371-2-WO
mold-volume reduction instructions (540), instructing the controller (160) to
control the pressure-control system (126) to decrease a volume of a mold cavity (213) of
the mold-cavity system (200), the mold cavity (213) having the molding material (101),
so that an additional pressure is applied to the molding material (101) being received in
the mold-cavity system (200) while the molding material (101) remains in a semi-solid
state in the mold-cavity system (200), so that the volume of the mold cavity (213) is
reduced and the molding material (101) located in the mold cavity (213) is compressed,
so that density of the molding material (101) located in the mold-cavity system (200)
increases; and
the mold-unpack instructions (520) further include:
mold-volume increase instructions (542), instructing the controller (160) to
control the pressure-control system (126) to increase the volume of the mold cavity
(213), so that the internal pressure of the molding material (101) being contained in the
mold-cavity system (200) is reduced while the molding material (101) remains in the
semi-solid state in the mold-cavity system (200), so that the molding material (101)
located in the mold-cavity system (200) becomes decompressed and the density of the
molding material (101) decreases by expanding the volume of the mold cavity (213)
before the mold-cavity system (200) is opened sufficiently so as to remove the molded
article (103) and while the mold-cavity system (200) remains isolated from the stream of
the molding material (101).
5. A molding system (100) being configured to manufacture a molded article (103) by
using a mold-cavity system (200) and using a molding material (101), the mold-cavity system
(200) having a stationary-mold assembly (201) and a movable-mold assembly (203), the
molding system (100) comprising:
a hot-runner system (300) being coupled with the stationary-mold assembly (201);
a stationary platen (102) being configured to support the hot-runner system (300) and
the stationary-mold assembly (201);
a movable platen (104) being configured to support the movable-mold assembly (203),
and being movable relative to the stationary platen (102);
platen bars (106) operatively extending between the stationary platen (102) and the
movable platen (104);
a group of controllable systems (108), including:
a platen actuator (120) being coupled with the movable platen (104);
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IIA7371-2-WO
bar locks (121) lockably coupling the platen bars (106) with the movable platen
(104);
clamp assemblies (122) being coupled with the platen bars (106), the clamp
assemblies (122) being configured to apply a clamp tonnage to the platen bars (106);
a mold-cooling system (124) being configured to couple with the mold-cavity
system (200);
a pressure-control system (126) being configured to couple with the mold-cavity
system (200);
a melt-preparation system (128) being configured to couple with the mold-cavity
system (200); and
a controller (160) being operatively coupling to the group of controllable systems (108),
the controller (160) having a controller-usable memory (162) tangibly embodying a set of
controller-executable instructions (500) being configured to direct the controller (160) to
control operation of the molding system (100), the set of controller-executable instructions
(500) including:
melt-preparation instructions (502), including instructing the controller (160) to
control the melt-preparation system (128) to convert the molding material (101) into a
stream of flowable-molding material;
mold-close instructions (504), including instructing the controller (160) to control
the platen actuator (120) to move the movable platen (104) toward the stationary platen
(102) thereby shutting close the mold-cavity system (200);
mold-lock instructions (506), instructing the controller (160) to control the bar
locks (121) to lock the movable platen (104) and the platen bars (106) so that the moldcavity
system (200) is locked, so that portions of the mold-cavity system (200) do not
move relative to each other when the mold-cavity system (200) is injected, under
pressure, with the stream of flowable-molding material;
tonnage-engage instructions (508), instructing the controller (160) to control the
clamp assemblies (122) to apply the clamp tonnage to the mold-cavity system (200) via
the platen bars (106) after the mold-cavity system (200) is closed shut and locked;
melt-stream connection instructions (510), instructing the controller (160) to
control the melt-preparation system (128) to connect the mold-cavity system (200) to the
stream of flowable-molding material, so that the stream of flowable-molding material
may flow into the mold-cavity system (200);
mold-injection instructions (512), instructing the controller (160) to control the
melt-preparation system (128) to inject a portion of the stream of flowable-molding
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material into the mold-cavity system (200) while the clamp tonnage maintains the moldcavity
system (200) closed;
mold-pack instructions (514), instructing the controller (160) to control any one
of, (i) the melt-preparation system (128), and (ii) the melt-preparation system (128) and
the pressure-control system (126) to reduce the pressure to the molding material (101)
being contained in the mold-cavity system (200) while the molding material (101)
becomes cooled, at least in part, in the mold-cavity system (200);
melt-stream disconnection instructions (516), instructing the controller (160) to
control the melt-preparation system (128) to disconnect the mold-cavity system (200)
from the stream of flowable-molding material, so that the mold-cavity system (200)
becomes isolated from the stream of flowable-molding material after the mold-cavity
system (200) has received the portion of the stream of flowable-molding material;
heat-reduction instructions (518), instructing the controller (160) to control the
mold-cooling system (124) to remove heat from the molding material (101) being
received in the mold-cavity system (200) after the mold-cavity system (200) has been
disconnected from the stream of flowable-molding material so that the mold-cavity
system (200) becomes isolated from the stream of flowable-molding material, and in
response solidification of the molding material (101) occurs in a gate portion (212) of
the mold-cavity system (200) so that the molded article (103) may be removed from the
mold-cavity system (200);
mold-unpack instructions (520), including instructing the controller (160) to
control the pressure-control system (126) to reduce, after solidification, at least in part,
of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the moldcavity
system (200) while the mold-cavity system (200) remains isolated from the
stream of flowable-molding material, beyond any reduction of the internal pressure in
the molding material (101) resulting from cooling of the molding material (101), so that
the reduction in the internal pressure of the molding material (101) is enough to permit
safe opening of the mold-cavity system (200) while permitting safe extraction of the
molded article (103) from the mold-cavity system (200);
tonnage-disengage instructions (522), instructing the controller (160) to control
the clamp assemblies (122) to disengage the clamp tonnage from the mold-cavity system
(200);
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mold-unlock instructions (524), instructing the controller (160) to control the bar
locks (121) to unlock the movable platen (104) and the platen bars (106) so that the
mold-cavity system (200) is unlocked; and
mold-open instructions (526), instructing the controller (160) to control the
movable platen (104) to away from the stationary platen (102) thereby opening the
mold-cavity system (200), so that a molded part made in the mold-cavity system (200)
may be removed from the mold-cavity system (200).
6. The molding system (100) of claim 5, wherein:
the mold-pack instructions (514) further include:
hold instructions (530), instructing the controller (160) to control the molding
system (100) to apply and hold the pressure to the molding material (101) being
contained in the mold-cavity system (200) while the molding material (101) remains in a
semi-solid state in the mold-cavity system (200); and
compensation instructions (531), instructing the controller (160) to control the
molding system (100) to inject an additional amount of the molding material (101) into
the mold-cavity system (200) while the molding material (101) in the mold-cavity
system (200) remains in the semi-solid state, and the additional amount of the molding
material (101) compensating for shrinkage of the molding material (101) being received
in the mold-cavity system (200);
the melt-stream disconnection instructions (516) are executed: (i) after the moldpack
instructions (514) are executed so that the mold-cavity system (200) becomes
isolated from the stream of flowable-molding material, and (ii) before the mold-unpack
instructions (520) are executed; and
the mold-unpack instructions (520) further include:
mold-volume increase instructions (532), instructing the controller (160) to
control the pressure-control system (126) to increase a volume of a mold cavity (213) of
the mold-cavity system (200), the mold cavity (213) receiving the molding material
(101), increasing the volume of the mold cavity (213) reduces the pressure within the
molding material (101) being received in the mold-cavity system (200) while: (i) the
molding material (101) remains in the semi-solid state in the mold-cavity system (200),
and (ii) the mold cavity (213) remains isolated from the stream of the molding material.
7. The molding system (100) of claim 5, wherein:
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the melt-stream disconnection instructions (516) are executed: (i) before the mold-pack
instructions (514) are executed, and (ii) before the mold-unpack instructions (520) are
executed;
the mold-pack instructions (514) further include:
mold-volume reduction instructions (540), instructing the controller (160) to
control the pressure-control system (126) to decrease a volume of a mold cavity (213) of
the mold-cavity system (200), the mold cavity (213) having the molding material (101),
so that additional pressure is applied to the molding material (101) being received in the
mold-cavity system (200) while the molding material ( 101) remains in a semi-solid state
in the mold-cavity system (200), so that the volume of the mold cavity (213) is reduced
and the molding material (101) located in the mold cavity (213) is compressed, so that
density of the molding material (101) located in the mold-cavity system ( 200) increases;
and
the mold-unpack instructions (520) further include:
mold-volume increase instructions (542), instructing the controller (160) to
control the pressure-control system (126) to increase the volume of the mold cavity
(213), so that the internal pressure of the molding material (101) being contained in the
mold-cavity system (200) is reduced while the molding material (101) remains in the
semi-solid state in the mold-cavity system (200), so that the molding material (101)
located in the mold-cavity system (200) becomes decompressed and the density of the
molding material ( 101) decreases by expanding the volume of the mold cavity (213)
before the mold-cavity system (200) is opened sufficiently so as to remove the molded
article (103) and while the mold-cavity system ( 200) remains isolated from (he stream of
the molding material (101).
8. A controller (160) for use with a molding system (100) being configured to manufacture
a molded article (103) in a mold-cavity system (200) by using a molding material (101), the
molding system (100) including a group of controllable systems (108) including a pressurecontrol
system (126) being: (i) coupled with the mold-cavity system (200), and (ii) being
operatively coupled to the group of controllable systems (108), the controller (160)
comprising:
a controller-usable memory (162) tangibly embodying a set of controller-executable
instructions (500) being configured to direct the controller (160) to control operation of the
molding system (100), the set of controller-executable instructions (500) including:
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mold-unpack instructions (520), including instructing the controller (160) to
control the pressure-control system (126) to reduce, after solidification, at least in part,
of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the moldcavity
system (200) while the mold-cavity system (200) remains isolated from a stream
of flowable-molding material, beyond any reduction of the internal pressure in the
molding material (101) resulting from cooling of the molding material (101), so that the
reduction in the internal pressure of the molding material ( 101) is enough to permit safe
opening of the mold-cavity system (200) while permitting safe extraction of the molded
article (103) from the mold-cavity system (200).
9. A controller-usable memory (162) for use with a controller (160), the controller (160)
for use with a molding system (100) being configured to manufacture a molded article (103)
in a mold-cavity system (200) by using a molding material (101), the molding system (100)
including a group of controllable systems (108) including a pressure-control system (126)
being: (i) coupled with the mold-cavity system (200), and (ii) being operatively coupled to the
group of controllable systems (108), the controller-usable memory (162) comprising:
a set of controller-executable instructions (500) being tangibly embodied in the
controller-usable memory (162), and being configured to direct the controller (160) to control
operation of the molding system (100), the set of controller-executable instructions (500)
including:
mold-unpack instructions (520), including instructing the controller (160) to
control the pressure-control system (126) to reduce, after solidification, at least in part,
of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the moldcavity
system (200) while the mold-cavity system ( 200) remains isolated from a stream
of flowable-molding material, beyond any reduction of the internal pressure in the
molding material (101) resulting from cooling of the molding material (101), so that the
reduction in the internal pressure of the molding material (101) is enough to permit safe
opening of the mold-cavity system (200) while permitting safe extraction of the molded
article (103) from the mold-cavity system (200).
10. A method of operating a molding system (100) being configured to manufacture a
molded article (103) in a mold-cavity system (200) by using a molding material (101), the
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molding system (100) having a pressure-control system (126) being coupled with the moldcavity
system (200), the method comprising:
controlling the pressure-control system (126) to reduce, after solidification, at least in
part, of the molding material (101) being located in a nub region (214) of the mold-cavity
system (200), internal pressure of the molding material (101) received in the mold-cavity
system (200) while the mold-cavity system (200) remains isolated from a stream of flowablemolding
material , beyond any reduction of the internal pressure in the molding material (101)
resulting from cooling of the molding material (101), so that the reduction in the internal
pressure of the molding material (101) is enough to permit safe opening of the mold-cavity
system (200) while permitting safe extraction of the molded article (103) from the mold-cavity
system (200).
11. A molding system (100) being configured to manufacture a molded article (103) by
using a molding material (101), the molding system (100) comprising:
a mold-cavity system (200) for forming, in use, the molded article (103); the moldcavity
system (200) including:
a primary parting line (224) defined between a cavity portion (210) and a neck
portion 206 and;
a secondary parting line (222) defined between the neck portion (206) and a top
portion (204);
a controller (160) operatively coupling to the a mold-moving actuator, the controller
(160) having a controller-usable memory (162) tangibly embodying a set of controllerexecutable
instructions (500) being configured to direct the controller (160), the set of
controller-executable instructions including a mold open instruction (902) configured to:
cause initial separation of the top portion (204) and the neck portion (206) relative
to the secondary parting line, while keeping the primary parting line un-opened, while
maintaining at least some clamp force.
12. The molding system (100) of claim 11, to keep the primary line un-opened, the moldopen
instruction (902) is further configured to:
activate an ejector actuator to urge the neck portion (206) towards the cavity portion
(210) during the initial separation; and
cause a clamp to cease applying clamp force.
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13. The molding system (100) of claim 12, wherein the mold-open instruction (902) is
configured to activate the ejector actuator to urge the neck portion (206) towards the cavity
portion (210) during the initial separation before it is configured to cause a clamp to cease
applying clamp force.
14. The molding system (100) of claim 12, wherein the mold-open instruction (902) is
configured to activate the ejector actuator to urge the neck portion (206) towards the cavity
portion (210) during the initial separation substantially simultaneously as it is configured to
cause a clamp to cease applying clamp force.
15. The molding system (100) of claim 12, wherein the mold-open instruction (902) is
configured to activate the ejector actuator to urge the neck portion (206) towards the cavity
portion (210) during the initial separation after it is configured to cause a clamp to cease
applying clamp force.
16. The molding system (100) of claim 11, wherein the mold-open instruction (902) is
further configured to cause, at a point in time after the initial separation, the cavity portion
(210) and the neck portion (206) to open relative to the primary parting line to implement
removal of the molded article (103) from the mold-cavity system (200).
17. A molding system (100) being configured to manufacture a molded article (103) by
using a molding material (101), the molding system (100) comprising:
a mold-cavity system (200) for forming, in use, the molded article (103); the moldcavity
system (200) including:
a stationary-mold assembly (201) and a movable-mold assembly (203), defining
therebetween a mold cavity;
the movable-mold assembly (203) including:
a base portion (202),
a top portion (204),
a neck portion (206);
a core portion (208),
the stationary-mold assembly (201) including:
a cavity portion (210), and
a gate portion (212),
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a controller (160) operatively coupling to the a mold-moving actuator, the controller
(160) having a controller-usable memory (162) tangibly embodying a. set of controllerexecutable
instructions (500) being configured to direct the controller (160), the set of
controller-executable instructions including a mold open instruction (902) configured to:
cause relative movement between the core portion (208) and the cavity portion
(210) by a distance sufficient to displace the totality of molecules of plastic of the
molded article (103) that abut with the core portion (208) from their relative positioning
during a process cycle, the displacement being in substantially the same direction, while
maintaining at least some of the clamping force.