Note: Descriptions are shown in the official language in which they were submitted.
CA 02617411 2008-01-30
H-741-CA-B
TRANSFER OF FORCE FROM MANIFOLD TO PLATE OF HOT RUNNER OF
INJECTION MOLDING SYSTEM USABLE FOR MOLDING METAL ALLOY
TECHNICAL FIELD
The present invention relates to molding systems; and more specifically, the
present invention relates
to, but not limited to: (i) injection molding systems usable for molding of a
metal alloy above a
solidus temperature of the metal alloy, injection molding system having a hot
runner, and/or (ii) hot
runners of injection molding systems usable for molding of a metal alloy above
a solidus temperature
of the metal alloy.
BACKGROUND OF THE INVENTION
The present invention is concerned with the molding of a metal alloy (such as
Magnesium) in a semi-
solid or fully liquid (i.e. above solidus) state. Detailed descriptions of
exemplary apparatus and
operations of injection molding systems used for such alloys are available
with reference to U.S.
Patent Nos. 5,040,589 and 6,494,703.
FIG.(s) I and 2 show a known injection molding system 10 including an
injection unit 14 and a
clamp unit 12 that are coupled together. The injection unit 14 processes a
solid metal feedstock (not
shown) into a melt and subsequently injects the melt into a closed and clamped
injection mold
arranged in fluid communication therewith. The injection mold is shown in an
open configuration in
Fig. I and comprises complementary mold hot and cold halves 23 and 25. The
injection unit 14
further includes an injection unit base 28 which slidably supports an
injection assembly 29 mounted
thereon. The injection assembly 29 comprises a barrel assembly 38 arranged
within a carriage
assembly 34, and a drive assembly 36 mounted to the carriage assembly 34. The
drive assembly 36 is
mounted directly behind the barrel assembly 38, for the operation (i.e.,
rotation and reciprocation) of
a screw 56 (Fig. 2) arranged within the barrel assembly 38. The injection
assembly 29 is shown to be
connected to a stationary platen 16 of the clamp unit 12, through the use of
carriage cylinders 30.
The carriage cylinders 30 are configured to apply, in operation, a carriage
force along the barrel
assembly 38 for maintaining engagement between a machine nozzle 44 (Fig. 2),
of the barrel
assembly 38, within a melt conduit (e.g., sprue bushing, manifold 170, etc.),
of a hot half runner
system 26, whilst the melt is being injected into the mold (i.e., acts against
the reaction forces
generated by the injection of the melt). The connection between the machine
nozzle 44 and the melt
conduit of the runner system is preferably a spigot connection, as described
in United States patent
6,357,511.
1
CA 02617411 2008-01-30
H-741-CA-B
The barrel assembly 38, in Fig. 2, is shown to include an elongated
cylindrical barre140 with an axial
cylindrical bore 48A arranged therethrough. The bore 48A is configured to
cooperate with the screw
56 arranged therein, for processing and transporting the metal feedstock, and
for accumulating and
subsequently channeling a melt of molding material during injection thereof.
The screw 56 includes
a helical flight 58 arranged about an elongate cylindrical body portion 59
thereof. A rear portion (not
shown) of the screw 56 is preferably configured to couple with the drive
assembly 36. A forward
portion of the screw (also shown) is configured to receive a non-return valve
60 with an operative
portion thereof arranged in front of a forward mating face of the screw 56.
The barrel assembly 38
also includes a barrel head 42 that is positioned intermediate the machine
nozzle 44 and a front end of
the barrel 40. The barrel head 42 includes a melt passageway 48B arranged
therethrough that
connects the barrel bore 48A with a complementary melt passageway 48C arranged
through the
machine nozzle 44. The melt passageway 48B through the barrel head 42 includes
an inwardly
tapering portion to transition the diameter of the melt passageway to the much
narrower melt
passageway 48C of the machine nozzle 44. The central bore 48A of the barrel 40
is also shown as
including a liner 46 made from a corrosion resistant material, such as
StelliteTM, to protect the barrel
substrate material, commonly made from a nickel-based alloy such as InconelTM,
from the corrosive
properties of the high temperature metal melt. Other portions of the barrel
assembly 38 that come
into contact with the molding material melt may also include similar
protective linings or coatings.
The barrel 40 is further configured for connection with a source of comminuted
metal feedstock
through a feed throat (not shown) that is located through a top-rear portion
of the barrel (also not
shown). The feed throat directs the feedstock into the bore 48A of the barrel
40. The feedstock is
then subsequently processed into a melt of molding material by the mechanical
working thereof, by
the action of the screw 56 in cooperation with the barrel bore 48A, and by
controlled heating thereof.
The heat is provided by a series of heaters 50 (not all of which are shown)
that are arranged along a
substantial portion of the length of the barrel assembly 38.
The clamp unit 12 includes a clamp base 18 with a stationary platen 16
securely retained to an end
thereof, a clamp block 22 slidably connected at an opposite end of the clamp
base 18, and a moving
platen 20 arranged to translate therebetween on a set of tie bars 32 that
otherwise interconnect the
stationary platen 16 and the clamp block 22. As is known, the clamp unit 12
further includes a means
for stroking (not shown) the moving platen 20 with respect to the stationary
platen to open and close
the injection mold halves 23, 25 arranged therebetween. A clamping means (not
shown) is also
provided between the clamp block and the moving platen to provide of a
clamping force between the
mold halves 23, 25 during the injection of the melt of molding material. The
hot half of the injection
2
CA 02617411 2008-01-30
H-741-CA-B
mold 25 is mounted to a face of the stationary platen 16, whereas the
complementary cold half of the
mold 23 is mounted to an opposing face of the moving platen 20.
In further detail, the injection mold includes at least one molding cavity
(not shown) formed between
complementary molding inserts shared between the mold halves 23, 25. The mold
cold half 23
includes a core plate assembly 24 with at least one core molding insert, not
shown, arranged therein.
The mold hot half 25 includes a cavity plate assembly 27, with at least one
complementary cavity
molding insert arranged therein, mounted to a face of a runner system 26. The
hot runner system 26
provides a means for connecting the melt passageway 48C of the machine nozzle
44 with at least one
molding cavity for the filling thereof. The runner system 26 includes a
manifold plate 64 and a
complementary backing plate 62 for enclosing melt conduits therebetween, and a
thermal insulating
plate 60. The runner system 26 may be an offset or multi-drop hot runner
system, a cold runner
system, a cold sprue system, or any other commonly known melt distribution
means.
The process of molding a metal in the above-described system generally
includes the steps of: (i)
establishing an inflow of metal feedstock into the rear end portion of the
barrel 40; (ii) working (i.e.,
shearing) and heating the metal feedstock into a thixotropic melt of molding
material by: (iia) the
operation (i.e., rotation and retraction) of the screw 56 that functions to
transport the feedstock/melt,
through the cooperation of the screw flights 58 with the axial bore 48A, along
the length of the barrel
40, past the non-return valve 60, and into an accumulation region defined in
front of the non-return
valve 60; and (iib) heating the feedstock material as it travels along a
substantial portion of the barrel
assembly 38; (iii) closing and clamping the injection mold halves 23, 25; (iv)
injecting the
accumulated melt through the machine nozzle 44 and into the injection mold by
a forward translation
of the screw 56; (v) optionally filling any remaining voids in the molding
cavity by the application of
sustained injection pressure (i.e. densification); (vi) opening the injection
mold, once the
molded part has solidified through the cooling of the injection mold; (vii)
removal of the molded part
from the injection mold; (viii) optionally conditioning the injection mold for
a subsequent molding
cycle (e.g., application of mold release agent).
A major technical challenge that has plagued the development of a hot runner
system 26, suitable for
use in metal injection molding, has been the provision of a substantially leak-
free means for
interconnecting the melt conduits therein. Experience has taught that the
traditional connection
regime used in a plastics hot runner system (i.e., a face-seal that is
compressively loaded under the
thermal expansion of the melt conduits) is not suitable in a hot runner system
for metal molding. In
particular, in a metal hot runner system, the extent to which the melt
conduits must be compressed to
maintain a face-seal therebetween is also generally sufficient to crush them
(i.e., yielding occurs).
3
CA 02617411 2008-01-30
H-741-CA-B
This is partly the result of the high operational temperatures of the melt
conduits (e.g., around 600 C
for a typical Mg alloy), which significantly reduces the mechanical properties
of the component
material (e.g., typically made from a hot work tool steel such as DIN 1.2888).
Another problem is that
significant thermal gradients exist across the melt conduits at the high
operating temperature cause
significant unpredictability in their geometry which complicates the selection
of suitable cold
clearances.
Another challenge with the configuration of structure for interconnecting melt
conduits has been in
accommodating the thermal growth of the interconnected melt conduits (i.e., as
the conduits are
heated between ambient and operating temperatures) without otherwise
displacing functional portions
thereof that may need to remain fixed relative to other structure. For
example, in a single drop hot
runner system, with an offset drop, wherein there are two melt conduits,
namely a supply and a drop
manifold, respectively, it is advantageous to fix the location of a machine
nozzle receptacle portion of
the supply manifold for sake of alignment with the machine nozzle 44, while
also fixing a drop (i.e.,
discharge) portion of the drop manifold for sake of alignment with an inlet
gate of a molding cavity
insert. Accordingly, some means for sealing between the supply and drop
manifolds must be
provided that accommodates an expansion gap therebetween in the cold
condition, and that does not
rely on a face-seal therebetween in the hot condition. This becomes even more
of a challenge in a
multi-drop hot runner (i.e., a hot runner with more than one discharge nozzle
for servicing a large
molding cavity or a mold with more than one molding cavity) wherein there are
many fixed drop
portions, the drop portions being configured on a corresponding quantity of
drop manifolds.
SUMMARY OF THE INVENTION
The present invention provides an injection molding machine apparatus and /or
a hot runner.
According to a first aspect of the present invention, there is provided an
injection molding system
usable for molding of a metal alloy above a solidus temperature of the metal
alloy, the injection
molding system having a hot runner, including: (i) a manifold plate, and (ii)
a manifold abutting the
manifold plate, the manifold having a drop, the manifold configured to
transfer a load to the manifold
plate along a direction extending inclined relative to the drop.
According to a second aspect of the present invention, there is provided a hot
runner of an injection
molding system usable for molding of a metal alloy above a solidus temperature
of the metal alloy,
the hot runner, including: (i) a manifold plate, and (ii) a manifold abutting
the manifold plate, the
manifold having a drop, the manifold configured to transfer a load to the
manifold plate along a
4
CA 02617411 2008-01-30
H-741-CA-B
direction extending inclined relative to the drop.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the presently preferred features of the present
invention will now be
described with reference to the accompanying drawings in which:
Fig. I is a schematic representation of a known injection molding machine;
Fig. 2 is a partial section of a portion of the Fig. I injection molding
machine;
FIG.(s) 3A and 3B, comprise schematic plan and cross-section views of a first
embodiment according
to the present invention;
FIG.(s) 4A and 4B comprise perspective and cross-section views of an
alternative embodiment
according to the present invention;
Fig. 5 is a cross-section of another alternative embodiment according to the
present invention;
Fig. 6 is a perspective view of an embodiment according to the present
invention used in an injection
mold hot half;
Fig. 7 is a cross-section of the Fig. 6 embodiment;
FIG.(s) 8A and 8B comprise perspective and cross-section views of the supply
manifold shown in
FIG.(s) 6 and 7;
FIG.(s) 9A and 9B comprise perspective and cross-section views of the drop
manifold shown in
FIG.(s) 6 and 7; 30
Fig. 10 is a perspective view of another embodiment according to the present
invention used in an
injection mold hot half;
Fig. 11 is a is a cross-section of the Fig. 10 embodiment;
FIG.(s) 12A and 12B comprise perspective and cross-section views of the supply
manifold shown in
5
CA 02617411 2008-01-30
H-741-CA-B
FIG.(s) 10 and 11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
1. Introduction
The present invention will now be described with respect to several
embodiments in which an
injection molding system is used for the molding of a metal alloy, such as
Magnesium, above its
solidus temperature (i.e., semi-solid thixotropic, or liquidus state).
However, the present invention
may find use in other injection molding applications such as plastic, liquid
metal, composites, powder
injection molding, etc.
Briefly, in accordance with the present invention, a melt conduit coupler is
provided for
interconnecting discrete melt conduits. Preferably, complementary male and
female 'spigot' coupling
portions are arranged on each of a melt conduit coupler and along portions of
the melt conduits to be
interconnected, respectively. A'spigot', as used in this description, is a
modifier that characterizes
the relative configuration of pairs of complementary coupling portions that
cooperate to interconnect
discrete melt conduits in a substantially leak-free manner. In particular, a
complementary pair of
'spigot' coupling portions are characterized in that the coupling portions are
configured to cooperate
in an overlapping, closely-spaced, and mutually parallel relation. The spigot
coupling portions are
preferably configured to cooperate to provide a'spigot connection' between
each of the melt conduit
spigot coupling portions and the complementary spigot coupling portion
provided on the melt conduit
coupler. The 'spigot connection' is characterized in that the interface
between the complementary
spigot coupling portions is cooled. Accordingly, a spigot connection is
provided as a cooled
engagement between closely-fit complementary cylindrical sealing faces,
wherein a weepage or
leakage of melt therebetween solidifies to provide a further effective seal
that substantially prevents
further leakage of melt.
The invention provides a new use for a spigot connection that solves some
rather vexing problems in
metal molding runner systems, outlined hereinbefore. U.S. Patent No.
6,357,511, discloses a spigot
connection configured between a machine nozzle and a mold sprue bushing.
According to the present
invention, a melt conduit coupler has been devised that uses the spigot
connection to interconnect
pairs of melt conduits. The presently preferred form of the invention is as an
interconnection between
a pair of melt conduits.
Furthermore, a runner system may also make use of the inventive melt conduit
coupler to join typical
melt distribution manifolds contained therein. For example, a single drop hot
runner, in an offset
6
CA 02617411 2008-01-30
H-741-CA-B
configuration, is disclosed herein that is particularly useful in adapting
cold chamber die casting
molds for use in a metal injection molding machine. Also disclosed is a multi-
drop hot runner for use
in a metal injection molding machine.
In a preferred embodiment of the invention, each of the melt conduits includes
a spigot coupling
portion that is provided on an outer circumferential surface that is arranged
along a cylindrical end
portion thereof. Similarly, the melt conduit coupler preferably comprises a
cooled ring body wherein
a complementary spigot coupling portion is arranged along an inner
circumferential surface thereon.
The ring body is preferably configured for the cooling thereof, in use, to
maintain the required
temperature at the spigot connection (i.e., provide a seal of relatively
cooled, solidified melt). As one
example, the temperature of the melt conduit coupler is controlled, in use, to
maintain the
temperature at the spigot connection at about 350 C, when molding with a
typical Magnesium alloy
melt.
In the following description, the mold operating temperature is typically
around 200-230 C; the melt
temperature is typically around 600 C; hot work tool steel (DIN 1.2888) is
preferably used for
manifolds, spigot tip inserts, etc. Also, the sealing/cooling rings are
preferably made from regular
tool steel (AISI 4140, or P20) because they are kept at a relatively low
temperature and are generally
isolated from large forces. Alternatively, the sealing/cooling rings can be
made from AISI H13 where
some force transmission is expected. The manifold insulators are preferably
made from a relatively
low thermally conductive material that is also capable of withstanding the
extremely high processing
temperatures without annealing. Presently, the preferred insulators are made
from InconelTM
However, the actual mold operating temperature, melt temperature, tool steel,
sealing/cooling ring
material, and manifold insulators may be selected based on the material being
molded, the required
cycle times, the available materials, etc. All such alternate configurations
are to be included within
the scope of the attached claims.
2. Spigot Seal Parameters
In accordance with the preferred embodiment, a melt conduit coupler is
provided for interconnecting
discrete melt conduits. Accordingly, spigot coupling portions are arranged on
each of the melt
conduit couplers and along portions of the melt conduits that are to be
interconnected. Preferably, the
fit between the complementary spigot coupling portions includes a small
diametrical gap. The small
gap provides for ease of engagement between the complementary coupling
portions during assembly.
Preferably, the gap is designed so that it is taken-up by the relative
expansion of the spigot coupling
portions when the melt conduits and the melt coupler are at their operating
temperatures. Any
diametrical interference between the spigot coupling portions at their
operating temperatures may
7
CA 02617411 2008-01-30
H-741-CA-B
provide supplemental sealing, but is not otherwise relied upon.
In the presently preferred embodiments, a typical gap between the coupling
portions is about 0.1 mm
per side when the melt conduits and the melt conduit coupler are at ambient
temperature. However,
this 0.1 mm gap is not essential, the fit between the complementary spigot
coupling portions could
otherwise be exact or include a slight interference at ambient temperature.
Preferably, each melt
conduit coupler is independently temperature-controlled.
As will be described in detail hereinafter, active cooling of the melt conduit
coupler is preferred to
control the temperature at the interface between the spigot coupling portions
to maintain a
substantially leak-free spigot connection. However, by configuring the melt
conduit within cooled
runner system plates (manifold and manifold backing plates which are
maintained at about 200-
230 C) it may also be possible to rely solely on passive heat transfer
therewith. Preferably, the melt
conduit components to be interconnected are arranged in the melt conduit
coupler such there is a
longitudinal cold clearance therebetween when the melt conduit components are
at ambient
temperature. In particular, there is a cold clearance gap between
complementary annular mating faces
that are disposed at the ends of each of the complementary melt conduits when
the melt conduits are
at ambient temperature.
Preferably, the clearance between the mating faces is taken up when the melt
conduits are at their
operating temperatures, due to the thermal expansion thereof. Accordingly, the
preload between the
mating faces of the melt conduit components, if any, can be controlled to
avoid excessive
compressive forces that could otherwise crush the melt conduit components. In
the preferred
embodiments, a typical cold clearance for a melt conduit that is heated to 600
C is about 1 mm. Any
face-seal that is provided between the complementary mating faces, at
operating temperature, is
supplemental.
3. The First Embodiment
With reference to FIG.(s) 3A and 3B, the first embodiment of the present
invention is shown. A first
melt conduit 70 and a second melt conduit 70' (respectively containing melt
channels 148A and
148B) are interconnected by a melt conduit coupler 80. The melt conduit
coupler 80 is, in a simple
form, an annular body 81 having a coolant passage or passages 82 therein,
which can be seen in Fig.
3B. Two coolant fittings 100 are provided for the inlet and outlet of the
coolant passage(s). The
coolant passage(s) 82 are preferably connected to a source of coolant,
typically air, that maintains the
temperature of the melt conduit coupler 80 somewhere around 350 C. However,
other coolants such
as oil, water, gasses, etc. may be used, depending upon the molding
application. Note that 350 C is
8
CA 02617411 2008-01-30
H-741-CA-B
relatively cool when compared to the melt conduits, which typically are
maintained somewhere
around 600 C, for Magnesium alloy molding.
The melt conduit coupler 80 is also shown to include a thermocouple
installation 86 that includes a
bore that is configured for receiving a thermocouple. Adjacent to the
thermocouple installation is a
thermocouple retainer 88 that includes a bore that is configured to receive a
fastener, the fastener
retains, in use, a clamp (not shown) that retains the thermocouple within the
thermocouple
installation 86. Preferably, the thermocouple installation 86 is located very
close to a spigot coupling
portion 76' disposed around an inner circumferential surface of the melt
conduit coupler 80 so that
the temperature at a spigot connection with complementary spigot coupling
portions 76, disposed
around end portions of the melt conduits 70, 70', can be controlled. Each of
the melt conduits 70, 70'
may have a heater 50 to maintain the temperature in the melt in conduits at
the prescribed operating
temperature, which again is about 600 C for Magnesium alloy molding.
Fig. 3B shows a schematic cross-section of the melt conduit coupler 80. The
preferred embodiment
uses a spigot connection between the melt conduit coupler 80 and the end
portions of the melt
conduits 70, 70'. Preferably, an inner circumferential surface of the annular
body 81 and an outside
circumferential surface of end portions of the melt conduits 70, 70', that are
to be interconnected, are
given a complementary configuration wherein the location of the melt conduit
coupler 80
substantially fixed about the interface between the melt conduits 70, 70'.
Accordingly,
complementary shoulder portions are configured around the outside
circumferential surface at the end
portions of the melt conduits 70, 70' and around an inner circumferential
surface of the melt conduit
coupler 80, respectively. The melt conduit coupler 80 is configured to include
a pair of the shoulder
portions, one for each of the melt conduits 70, 70' that are to be
interconnected, and are configured at
opposing ends of the inner circumferential surface of the melt conduit coupler
80, the shoulder
portions being separated by a residual annular portion 92. The complementary
spigot coupling
portions 76, 76' are configured across an outside circumferential surface of a
recessed portion of the
shoulder, and across the inner circumferential surface of the annular portion
92, on the melt conduit
couplers 70, 70' and the melt conduit coupler 80, respectively. Of course, the
coupling may eliminate
the complementary shoulder portions, or may incorporate any number and/or
shape of protruding and
recessed surfaces to enhance coupling, depending upon the molding application.
As described hereinbefore, the spigot coupling portions 76, 76' are preferably
configured to have a
small gap therebetween. In use, a Magnesium alloy at 600 C has a viscosity
like water and is
therefore generally able to seep between complementary mating faces 120, 120'
of the melt conduits
70, 70', and to thereafter seep between spigot coupling portions 76, 76'.
However, because the melt
9
CA 02617411 2008-01-30
H-741-CA-B
conduit coupler 80 is kept at a relatively low temperature by active or
passive cooling (i.e., around
350 C), the melt will fully or at least partially solidify in such gaps and
provide a seal that
substantially prevents the further leakage of melt.
A thermocouple 74 may be disposed at the end portions of either or both of the
melt conduits 70, 70',
to detect the temperature of the melt conduit adjacent the melt conduit
coupler 80. Preferably, the
thermocouple 74 is located very close to the interface between the spigot
coupling portions 76, 76',
so that the temperature of the melt within the melt passageway 148A, 148B
adjacent the spigot
connection can be controlled (for example, by controlling the power to the
heaters 50 disposed about
the melt conduits 70, 70'), to prevent the formation of a plug in the melt
passageway 148A, 148B
adjacent the cooled spigot connection.
The mating faces 120, 120' of the melt conduits 70 and 70' are shown to
preferably include a
longitudinal cold clearance 116 of about 1 mm therebetween when the melt
conduits are at that
ambient temperature. This gap is selected (predetermined) to be taken up (or
substantially closed) as
the melt conduits expand in length as they are heated to the operating
temperatures. Accordingly,
there is substantially no gap, and maybe even some compression between the
mating faces of the melt
conduits 70 and 70'. Any such compression may act to provide a supplemental
seal against leakage
of melt. In this fashion, excessive compressive forces between the melt
conduits 70, 70', due to
thermal expansion, that may otherwise cause local yielding in the melt
conduits 70, 70' is
substantially avoided.
As discussed above, the melt also has a way of working its way through the
gaps between the spigot
coupling surfaces 76, 76', and is only substantially prevented by carefully
controlling the temperature
at the interface between these spigot coupling portions 76, 76' well below the
melting point of the
molding material. For the preferred embodiments, it is preferable that a cold
clearance gap of about
0.1 mm between the spigot coupling portions 76, 76' be provided at ambient
temperature. In use, the
relative thermal expansion of the melt conduit coupler 80 and the melt
conduits 70, 70' is such that
this diametrical gap will be substantially taken up and preferably there is as
an intimate contact
between the accompanying portions at the operating temperature. Such intimate
contact would
provide a supplemental seal against further leakage of the melt, although a
small residual gap is
tolerable in view of the main mode of sealing (i.e. seal of solidified melt).
Alternatively, there could
be an exact fit, or even a small compressive preload between the spigot
coupling portions 76, 76' at
ambient temperature. This would ensure that there is supplemental sealing from
the compression
between the spigot coupling portions 76, 76' at the operating temperatures.
Accordingly, the melt
coupler 80 of the present invention provides a substantially leak-free seal
between melt conduits 70,
CA 02617411 2008-01-30
H-741-CA-B
70' that operates without requiring a compressive sealing force between the
mating faces 120, 120' of
the melt conduits 70, 70'.
In, an alternative embodiment (not shown), the melt conduit coupler may be
integrated onto an end of
one of the melt conduits.
In, an alternative embodiment, the melt conduit coupler 180 is a
parallelepiped, as shown with
reference to FIG.(s) 4A and 4B. Accordingly, the outer surface of the melt
conduit coupler 180 is
rectangular, and a central cylindrical passageway configured therethrough is
configured in a
lo consistent manner as the prior embodiment with reference to FIG.(s) 3A and
3B. The rectangular
body 181 of the melt conduit coupler 180 is more easily integrated, that is
retained, within the plates
of a hot runner system, as shown with reference to FIG. 6 and in FIG. 10.
Preferably, the rectangular
body 181 is configured to be retained in a complementary formed pocket
provided in a hot runner
plate (e.g. with reference to FIG. 7, the hot runner plates include a manifold
plate 64 or a backing
plate 62). As will be explained in detail hereinafter, the hot runner plates
provide a housing for the
melt conduits 70, 70' (or 'manifolds', as more commonly known), the melt
conduit couplers 80, and
all the other related components.
As previously mentioned, the specific features of the melt conduit coupler 180
are substantially
similar to those discussed above with respect to melt conduit coupler 80 in
FIG.(s) 3A and 3B. The
spigot coupling portion 76 is provided on the inner circumferential surface of
an annular portion 192,
and also provided are shoulder portions configured on each side of the annular
portion 192 that
cooperate, in use, with complementary shoulder portions configured on the end
portions of the melt
conduits, or manifolds, to generally retain the melt conduit coupler 180. A
coolant passageway 182
preferably comprises various drilled portions so there is a first coolant
passage portion 182A, a
second coolant passage portion 182B, a third coolant passage portion 182C, and
a fourth coolant
passage portion 182D. Preferably, the coolant passage portions are formed by
drilling and the drill
entrances may be plugged with plugs 102, as required. Coolant ports 184 and
184' are provided in
communication with the coolant passageways 182 for receiving coupling fittings
100. As before, a
thermocouple may be installed within a thermocouple installation 186, in
proximity to the
complementary spigot coupling portion 76 such that the temperature of the
spigot connection can be
closely monitored and the temperature and/or flow of the coolant can be
adjusted accordingly.
Preferably, the coolant is conditioned outside of the mold through the use of
a ThermolatorTM
heating/cooling unit, as required. Again, a thermocouple retainer is provided
adjacent to the
thermocouple installation 186 to receive a fastener that fastens a clamp (not
shown) for retaining the
thermocouple within the thermocouple installation 186.
11
CA 02617411 2008-01-30
H-741-CA-B
Also shown in FIG. 4A are a pair of cylindrical bores 194 that are configured
on either side of the
central opening in the melt conduit coupler 80, and that are substantially
perpendicular to an axis
thereof. In addition, a cut-out 196 is configured at the first end of each of
the cylindrical bores 194, on
an end of the rectangular body 181. The cylindrical bores 194 and the cut-out
196 provide a structure
that cooperates with a shank and a head of a fastener, respectively, such as a
socket head cap screw,
such that the melt conduit coupler 180 can be retained within the pocket
provided in a hot runner
plate (e.g. the manifold plate 64 with reference to FIG. 7).
Also shown in FIG. 4A is a pocket surface 198 on each face 199 of the melt
conduit coupler 180.
The faces 199 are in contact with the surfaces of the pocket within the hot
runner plate and control
the amount of heat transfer therebetween. The larger the contact surface
between the faces 199 of the
melt conduit coupler 180 and the pocket, the more heat transfer between the
two. Accordingly, the
preferred design uses pocket surfaces 198 to minimize the contact surface
between the faces 199 and
the pocket in the hot runner plate so that the temperature at the spigot
coupling portion 76, 76' may
be more precisely controlled by influence of the coolant flow within the
coolant passage 182.
4. Supplemental Expansion Bushing
With reference to FIG. 5, an alternative embodiment of the present invention
is shown. Structures
which are the same as those shown in FIG. 3B are designated by the same
reference numbers. In FIG.
5, a expansion bushing 93 is provided to provide a supplemental seal between
the melt conduits 70,
70'. Preferably, the expansion bushing is provided by an annular ring. An
outside circumferential
surface of the annular ring is configured to cooperate with a bushing seat 78
that is provided along an
inner circumferential surface of a cylindrical bore that is formed through the
end portions of the melt
conduits 70, 70', concentric with the melt passageways 148A, and 148B. The
inner circumferential
surface of the expansion bushing connects the melt passageways 148A and 148B,
and preferably has
the same diameter. Preferably, the supplemental expansion bushing 93 is made
from a metal which is
different from that of the melt conduits whereby a compressive sealing force
is developed between
the outside surface of the expansion bushing 93 and the bushing seat 78 as a
result of the relative
thermal expansion of the expansion bushing 93 and the melt conduits 70, 70'.
Preferably, the
supplemental expansion bushing 93 is made from a material, like StelliteTM (a
Cobalt-based alloy),
which will grow slightly more per given temperature change than the melt
conduits that may be made
from DIN 1.2888. As the bushing seat 78 will also expand in length, a
longitudinal cold clearance is
preferably provided between the ends of the expansion bushing and the
corresponding end of the
seats to the extent that a portion of the gap remains even when the melt
conduits 70, 70' are at their
12
CA 02617411 2008-01-30
H-741-CA-B
operating temperature such that the expansion bushing 93 does not act to
separate the melt conduits
70, 70'.
5. Use in Offset Applications
With reference to FIG.(s) 6 and 7, an injection mold hot half 25 is shown as
including a single drop
hot runner 26, with an offset drop, and a cavity plate assembly 27. The hot
half 25 is preferably
configured to accommodate a cavity molding insert (not shown). The hot runner
26 is useful in
adapting molds that were intended for use in cold chamber die casting machine
for use in an injection
molding machine. In particular, many such molds include an offset injection
portion (not shown) that
is otherwise required to prevent the free-flow of melt into the mold cavity
during an initial "slow
shot" that purges air from the cold chamber. Thus, in order to center the
cavity in die-casting
machines, the injection point is situated offset from the center of the mold.
Also, offset injection
points may be necessary for parts that have to be filled from outside in. The
hot runner includes a
backing plate 62 and a manifold plate 64, with the melt conduit component and
other auxiliary
components housed therebetween. The hot runner 26 includes two melt conduits,
namely a supply
manifold 170 and a drop manifold 172. Both the supply and drop manifolds 170,
172 are configured
to include right angle melt passageways therein, as shown in detail in FIG.(s)
8A , 8B, 9A, and 9B.
The supply and drop manifolds 170 and 172 are preferably interconnected with a
melt conduit
coupler 180. Preferably, the manifolds themselves are located in manifold
pockets 65 provided in the
manifold plate 64 and as shown with reference to FIG. 7. The manifolds 170,
172 are also configured
to receive side insulator 106 and axial insulators 108 and 110 that
substantially isolate the heated
manifolds from the relatively cooler plates and to transfer axial loads
thereto. Also shown in FIG. 6
are coolant conduits 104 that are configured to connect with the coolant ports
184, 184' on the melt
conduit coupler 180. Also shown in the backing plate 62 is a services pocket
63, which provides a
clearance for portions of the manifolds 170, 172, wiring for the thermocouples
and heaters, the
coolant conduits, and other auxiliary components.
Also shown in FIG. 6 is a cooling ring 185 which cools the inlet portion of
the supply manifold 170.
Cooling the inlet portion will assist in making a spigot connection between a
spigot coupling portion
174 of a nozzle seat that is configured through the inlet portion of the
supply manifold 172, and
described in detail hereinafter, and a complementary spigot portion 45
provided on the machine
nozzle 44. Such a configuration is generally known with reference to U.S.
Patent No. 6,357,511.
The cooling ring 185 comprises an annular coupling body with coolant
passage(s) configured therein.
13
CA 02617411 2008-01-30
H-741-CA-B
Also shown in FIG. 6 is a mold locating ring 54, that is configured to
cooperate with a
complementary locating ring (not shown) that is provided in the stationary
platen 16 (FIG. 1) of the
injection molding machine clamp 12 (FIG. 1) for aligning the nozzle seat of
the supply manifold 170
with the machine nozzle 44 (FIG. 2). The cavity plate assembly 27, in further
detail, comprises a
cavity plate 66 and a spacer plate 68. A cavity molding insert (not shown) may
be connected to a
front face of the cavity plate 66. Also provided in the cavity plate 66 is a
modified mold cold sprue
150 that comprises a sprue bushing 151 in which an outwardly tapering sprue
passageway 153 is
configured for the discharge of melt therethrough. The mold cold sprue 150
could be otherwise be a
drop nozzle assembly 250, as will be explained later with reference to the
embodiment of FIG. 10.
The spacer plate 68 is simply an intermediate plate that spans a gap between
the hot runner 26 and the
cavity plate 66 that is otherwise dictated by the length of the discharge
portion (elbow segment 308 as
shown with reference to FIG. 9A and 9B). The length of the discharge portion
was established to
ensure its versatility for use with a drop nozzle assembly 250 (FIG. 11).
Preferably, the manifold
plate 64 is provided with a drop passage 67 through which extends the
discharge portion of the drop
manifold 172.
With reference to FIG.(s) 8A and 8B, the supply manifold 170 is shown in
greater detail. The supply
manifold 170 preferably has a cross-like shape and includes four structural
portions; a first elbow
portion 206, a second elbow portion 208, a third elbow portion 210, and a
fourth elbow portion 212.
Each of the elbow portions 206, 208, 210, and 212 is configured to serve a
unique function. The first
elbow portion 206 is essentially an inlet portion that is configured for
interconnection with the
machine nozzle 44 for connecting, in use, the machine nozzle melt passageway
48C with a melt
passageway 148A of the first elbow portion 206. The first and second elbow
portions 206, 208 are
configured to be substantially perpendicular to one another. Accordingly, the
second elbow portion
208 includes a melt passageway 148B extending therealong that is configured to
cooperate with the
melt passageway 148A of the first elbow portion 206 for substantially
redirecting the melt traveling
therethrough. The second elbow portion 208 is further configured for
interconnection with an
adjacent drop manifold 172 through the use of a melt conduit coupler 80. The
third elbow portion
210, which is generally aligned with the first elbow portion 206, is
configured for locating the supply
manifold 170 within the plates 62, 64 along a first axis, and for transferring
loads thereto. The fourth
elbow portion 212, which is substantially perpendicular to the third elbow
portion 210 and is
generally aligned with the second elbow portion 208, is also configured for
locating the supply
manifold 170 within the plates 62, 64 along a second axis, and again for
transferring loads thereto.
Each of the elbow portions is preferably configured as a generally cylindrical
body.
14
CA 02617411 2008-01-30
H-741-CA-B
With reference to FIG. 8B, the first elbow portion 206 includes the melt
passageway 148A that
extends from a free end of the first elbow portion 206 along the length of the
first elbow portion
where it interconnects with the melt passageway 148B that is provided along
the second elbow
portion 208. Also provided at the free end of the first elbow portion 206 is a
shallow cylindrical bore
that provides aseat for receiving a spigot tip of the machine nozzle 44.
Accordingly, an inner
circumferential surface of the seat provides a spigot-mating portion 174.
Preferably, a gap is
configured between the shoulder 175 at the base of the seat and a front face
of the spigot portion 45
when it is fully engaged within the seat. Accordingly, an annular face 218
provided at the free end of
the first elbow portion 206 provides a spigot mating face 218 that is
configured to cooperate with a
complementary mating face provided on the machine nozzle 44 for limiting the
longitudinal
engagement of the spigot portion 45 of the machine nozzle 44 into the seat,
and may otherwise
provide a supplemental face sea] to prevent the leakage of melt of molding
material. Also shown, is a
seat that is configured along a shallow diametrical relief provided in the
outer circumferential surface
of the first elbow portion 206, immediately adjacent the free end thereof, for
receiving the cooling
ring 185. As previously described, the cooling ring 185 functions to cool
interface between the spigot
coupling portion 174 of the seat for providing a spigot seal with the
complementary spigot coupling
surface on the spigot portion 45 of the machine nozzle 44.
The cooling ring seat includes a mating portion 200 and a locating shoulder
201. The mating portion
200 preferably cooperates with a complementary mating portion provided on the
cooling ring 185, to
conduct heat between the supply manifold and the cooling ring for cooling the
spigot coupling
portion 174. Preferably, the locating shoulder 201 retains the cooling ring
185 adjacent the free end
of the first elbow portion 206.
The cooling ring 185 is shown in FIG.(s) 6 and 7. It preferably comprises an
annular body with a
coolant channel configured therein. The coolant channel is coupled to a source
of coolant in the same
manner as the melt conduit coupler 80, as described above. The cooling ring is
configured to cool the
free end of the supply manifold 170 to ensure that the interface between the
spigot tip 45 of the
machine nozzle 44 and the spigot coupling portion 174 in the supply manifold
is kept at or below the
melting temperature of the melt, so that a seal of molding hardened or semi-
hardened melt material is
provided therebetween.
The remaining outer circumferential surface of the first elbow portion 206 is
configured to receive a
heater 50. The heater maintains the temperature of the melt in the melt
passageway 148A at the
prescribed operating temperature. A controller (not shown) controls the heater
50 through feedback
from one or more thermocouples, located in thermocouple installation cavities
186, that monitor
CA 02617411 2008-01-30
H-741-CA-B
the temperature of the melt passageway 148A. The feedback from the
thermocouples could also
be used to control the temperature in the cooling ring 185. A thermocouple
clamp retainer may
be used to retain one or more of the thermocouples in their respective
thermocouple installation
cavities 186.
The second elbow portion 208 is generally perpendicular to the first elbow
portion, and also
includes a melt passageway 148B that extends through a free end thereof and
interconnects with
the melt passageway 148A of the first elbow portion at substantially right
angles thereto. An
annular planar front face at the free end of the second elbow portion 208
provides a mating space
220 that is configured to cooperate with a complementary mating face on the
drop manifold 172,
as will be described hereinafter. Also shown is a shallow diametrical relief
in the outer surface
of the second elbow portion 208 that provides a seat for receiving the melt
conduit coupler 180.
In further detail, the melt conduit coupler seat includes a spigot coupling
portion 76 which is
provided along an outer circumferential surface of the relief portion and a
locating shoulder 79
which retains the melt conduit coupler adjacent the free end of the second
elbow portion 208.
As with the first elbow portion 206, the second elbow portion 208 is
configured to receive a
heater 50 for maintaining the temperature of the melt within the melt
passageway 148B at the
prescribed operating temperature. Also, there is preferably a thermocouple
installation cavity
provided along second elbow portion 208, for providing temperature feedback to
the heater
controller and the temperature controller for the melt conduit coupler 180.
The third elbow portion 210 is also preferably substantially perpendicular to
the second elbow portion
208, and is generally coaxial with the first elbow portion 206. The third
elbow portion 210 includes a
shallow cylindrical bore that provides a seat 214 configured for receiving an
axial insulator 108, as
shown in FIG. 7. The axial insulator 108 functions to thermally insulate the
supply manifold 172
from the cold manifold plate 64. The axial insulator 108 is also configured to
assist in substantially
locating the supply manifold 172 on a first axis, and is also configured to
direct the longitudinally
applied compressive force from the machine nozzle into the manifold plate 62.
Accordingly, the
axial insulators are preferably designed to withstand the separating forces
due to melt pressures and
the carriage force developed by the carriage cylinders. The third elbow
portion 210 is preferably
heated by a heater 50 located on the outer surface thereof to compensate for
the heat lost to the
cooled manifold plate 62.
The fourth elbow portion 212 is also generally perpendicular to the third
elbow portion 210, and is
substantially coaxial with the second elbow portion 208. The fourth elbow
portion 212 includes an
16
CA 02617411 2008-01-30
H-741-CA-B
insulator stand 216 that is configured on the end face of a free end of the
fourth elbow portion, and
includes generally parallel sidewalls that are configured to cooperate with a
complementary slot and a
side insulator 106, as shown in FIG. 7. The side insulators 106 are also
configured to cooperate with
complementary seat provided in the manifold plate 64 to assist in positioning
and thermally isolate
the supply manifold 170. The fourth elbow portion 212 is preferably heated by
a heater 50 located
on the outer surface thereof to compensate for the heat lost to the cooled
manifold plate 62.
As introduced hereinbefore, the location of the first elbow 206 (i.e. inlet
portion) of the supply
manifold 170 is preferably substantially fixed with respect to a first axis.
With reference to FIG. 7, it
can be seen that the location of the supply manifold 170 is substantially
fixed, along the first axis,
between the cooling ring 185 and the axial insulator 108 that are themselves
located within seats
provided in the backing plate 62 and in the manifold plates 64, respectively.
Preferably, a cylindrical
bore is provided through the backing plate 62 and provides a passageway 59
that provides clearance
for the machine nozzle 44 and the first elbow portion 206 of supply manifold
170. In addition, an
inner circumferential surface of the passageway 59 provides a cooling ring
seat 204 that locates the
cooling ring 185 and thereby locates the first elbow portion 206 of the supply
manifold 170.
Similarly, in the manifold plate 64 is a shallow cylindrical bore which
provides an insulator pocket 69
and provides clearance for the third elbow portion 210 of the supply manifold
170. Preferably, there
is another shallow cylindrical bore that is concentric with the insulator
pocket 69 that provides a seat
114 for receiving the axial insulator 108. The axial insulator 108 is
preferably fixed or retained into
the insulator seat 114, and the insulator seat (in cooperation with the
complementary insulator seat in
the third elbow portion) substantially locates the third elbow portion 206 of
the supply manifold.
In FIG. 7, the side insulator 106 is shown installed in an insulator seat 114
provided in the manifold
plate 64 immediately adjacent a manifold pocket 65. The side insulator 106 is
further configured to
cooperate with the insulator stand 216 on the fourth elbow portion 212 to
preferably thermally isolate
the supply manifold 170 from the cooled manifold plate 64, to counteract, in
use, any separation
forces (e.g. reaction forces from melt flow within the melt passageway 148B)
between the supply and
drop manifold 170, 172, and to provide a limited degree of alignment for the
supply manifold 170.
The drop manifold 172 is shown in FIG.(s) 9A and 9B. The drop manifold 172 is
very similar in
configuration to the supply manifold 170 and has a similar cross-like
configuration with first, second,
third, and fourth elbow portions 306, 308, 310, and 312, respectively. The
first elbow portion 306 is
configured to be coupled to the second elbow portion 208 of the supply
manifold 170.
17
CA 02617411 2008-01-30
H-741-CA-B
Accordingly, the first elbow portion 306 includes a melt passageway 148C that
extends through the
free end thereof and along the length of the first elbow portion 306, and is
interconnected with a melt
passageway 148D that extends along the second elbow portion 308. As with the
second elbow
portion 208 of the supply manifold, the first elbow portion 306 of the drop
manifold includes a
diametrically relieved portion adjacent the free end that provides a seat for
the melt conduit coupler
180. As explained previously, the seat preferably comprises a spigot coupling
portion 76 and a
locating shoulder 79. An annular planer face at the free end of the first
elbow portion 306 provides a
mating face 220 that cooperates with the complementary mating face on the
supply manifold 170.
The remaining outer portion of the first elbow portion 306 is configured to
receive a heater 50 and
one or more thermocouple installations 186, as explained previously.
The second elbow portion 308, or discharge portion, is substantially
perpendicular to the first elbow
portion 306. The second elbow portion 308 includes the melt passageway 148D
that extends through
the free end of the second elbow portion 308 and interconnects with the melt
passageway 148C of the
first elbow portion 306. The free end of the second elbow portion 308 is
preferably configured to
include a seat for receiving a spigot tip insert 145. Of course, the spigot
tip insert could otherwise be
made integrally with the second elbow portion as shown with reference to FIG.
11 wherein an
alternative embodiment of the drop manifolds 172 and 172' is shown. This
spigot tip insert 145, as
shown in FIG. 7, is configured to interconnect the drop manifold 172 with the
sprue bushing 151 of
the cold sprue 150. The seat provided through the free end of the second elbow
portion 308 is
provided by a shallow cylindrical bore, and an inner circumferential surface
of the shallow bore
provides a spigot coupling surface 176 that cooperates with an outer
circumferential complementary
spigot coupling portion 176' on the spigot tip insert 145. Also, an annular
shoulder provided at the
base of the shallow cylindrical bore provides a locating shoulder 177 for
locating the spigot tip
insert 145 within the seat. The outer circumferential surface of the spigot
tip insert 145 also
provides a spigot coupling portion 147 that is configured to cooperate with a
complementary spigot
coupling portion 147' provided in the sprue bushing 151. Through heat
conduction to the cooled
cavity plate assembly 66, a spigot seal is maintained between the
complementary spigot interface
portions 147, 147' and also between the spigot coupling portions 176, 176'.
The remaining outer
surface of the second elbow portion 308 is preferably configured for receiving
heaters 50, and
includes one or more thermocouple installation cavities 186 for temperature
feedback control of
the heaters 50, as explained previously.
The third elbow portion 310 is configured similarly to the fourth elbow
portion 212 of the supply
manifold 170 and accordingly includes an insulator stand 216 for receiving the
side insulator 106, as
18
CA 02617411 2008-01-30
H-741-CA-B
shown in FIG. 7. The side insulator 106 is shown to be installed in a
insulator seat 114 provided in
the manifold plate 64.
The fourth elbow portion 312 is configured similarly to the third elbow
portion 210 of the supply
manifold 170, and accordingly includes a insulator seat 214. The insulator
seat 214 is preferably
configured to receive an end of an axial insulator 110 that can be seen in
FIG. 7. The axial insulator
110 is retained within a insulator seat 114 provided in the backing plate 62.
Also shown configured
in the backing plate 62 is a shallow cylindrical bore that provides an
insulator pocket 69 for providing
clearance around the fourth elbow portion 312 of the drop manifold 172. The
insulator seat 114 is
preferably configured as a concentric shallow cylindrical bore formed at the
base of the insulator
pocket 69. As before, the axial insulator 110 functions to thermally insulate
the drop manifold 172
from the backing plate 62, transfer axial loads to the manifold plate 62, and
to assist in positioning of
the drop manifold 172 about the inlet of the cold sprue 150. In particular,
with reference to FIG. 7, it
can be seen that the location of the drop manifold 172 is substantially fixed,
along the first axis,
between the sprue bushing 151 and the axial insulator 110 that are themselves
located within seats
provided in the cavity plate 66 and in the backing plates 62, respectively.
Also shown in FIG. 7, the melt conduit coupler 180 is located within a seat
178 provided in the
manifold plate 64. As described previously, the melt conduit coupler 180 is
preferably retained within
the seat 178 through the use of fasteners that pass through the cylindrical
bores 194 in the melt
conduit coupler 180, and cooperate with complementary portions in the manifold
plate 64.
As explained previously with reference to FIG.(s) 3A, 3B, and 5, the spigot
coupling portion 76
provided on the inner circumferential surface of the melt conduit coupler
cooperates with the
complementary spigot coupling portions 76' of the free ends of the supply and
drop manifolds 76 to
provide a spigot seal therebetween. In the cold condition, there is preferably
a cold clearance gap 116
between the mating faces 220 of the drop manifold 172 and the supply manifold
70. At operating
temperatures, however, by virtue of the thermal growth of the manifolds, the
mating faces of the
manifolds will preferably meet to provide a supplemental face seal
therebetween.
Also shown in FIG. 7 is an optional insulating plate 60 which thermally
insulates the hot runner 26
from the relatively cool stationary platen 16 (FIG. 1) of the machine clamp
12.
With reference to FIG.(s) 10 and 11, another embodiment according to the
present invention is
shown. In particular, the hot half 25 is configured to include a multi-drop
hot runner 26. The drops of
a multi-drop hot runner 26 may be used for servicing a large molding cavity or
a multi-cavity mold.
19
CA 02617411 2008-01-30
H-741-CA-B
While the present embodiment is configured to include two vertically oriented
drops, other quantities
and configurations of drops are possible. In the present embodiment the
molding inserts are not
shown, but would otherwise have been mounted to a front face of the cavity
plate assembly 27, or
recessed therein. The cavity plate assembly 27 has been configured to include
two mold drop nozzle
assemblies 250, each of which is configured to couple the molding cavities
(not shown) with the drop
manifolds 172 and 172'. The structure and operation of such a drop nozzle
assembly 250 is generally
described with reference to the description of a sprue apparatus in pending
PCT Application
PCT/CA03/00303. The important difference, is that the drop nozzle assembly 250
is presently
configured to couple with the drop manifolds 172 instead of a machine nozzle
44.
As shown with reference to FIG. 11, the drop nozzle assembly 250 comprises a
sprue bushing 252,
which is essentially a tubular melt conduit, that is housed between a front
housing 250 and a cooling
insert 256.
The sprue bushing 252 is arranged within a front housing 254 such that a
spigot ring portion 288,
configured at the front of the sprue brushing 252, is received within a
complementary spigot coupling
portion provided in the front portion 290 of front housing 254. A rear portion
of the sprue bushing
252 is received within a cooling insert 256 that is located within a rear
portion of the front housing
254. The cooling insert 256 functions to cool an inlet portion of the sprue
bushing 252 such that a
spigot connection can be maintained between a spigot coupling portion 174,
configured along an
inner circumferential surface of a shallow cylindrical bore formed through the
end of the sprue
bushing 252, and the complementary spigot coupling portion disposed on the
drop manifold 172.
Also shown is a plurality of heaters that are arranged along the length of the
sprue bushing 252 to
maintain the temperature of the melt within a melt passageway therein at a
prescribed operating
temperature.
The configuration of the supply 270 and drop manifolds 172, 172' that are
shown arranged between
the manifold plate 64 and the manifold backing plate 62 with reference to FIG.
7 is substantially the
same as that described with reference to the hot runner configuration (FIG.
7). As shown with
reference to FIG.(s) 12A and 12B, a notable difference with respect to the
supply manifold 270,
relative to the that described previously and shown in FIG.(s) 8A and 8B, is
that the fourth elbow
portion 412 has been configured identically to the second elbow portion 408,
including an additional
melt passageway 148B', and hence is configured for interconnection with the
additional drop
manifold 172' adjacent thereto. To accommodate the extra drop manifold 172',
as shown in FIG. 11,
CA 02617411 2008-01-30
H-741-CA-B
there is provided an additional melt conduit coupler 180, drop passage 67,
insulator pocket 69, and
insulator installation 114.
As described hereinbefore, the hot runner 26 could be reconfigured to include
any quantity and/or
configuration of drops. Accordingly, many variations on the number and
configuration of the
manifolds are possible. For example, an intermediate manifold (not shown)
could be configured
between the supply and drop manifolds.
Any type of controller or processor may be used to control the temperature of
the melt and structure,
as described above. For example, one or more general-purpose computers,
Application Specific
Integrated Circuits (ASICs), Digital Signal Processors (DSPs), gate arrays,
analog circuits, dedicated
digital and/or analog processors, hard-wired circuits, etc., may receive input
from the thermocouples
described herein. Instructions for controlling the one or more of such
controllers or processors may
be stored in any desirable computer-readable medium and/or data structure,
such floppy diskettes,
hard drives, CD-ROMs, RAMs, EEPROMs, magnetic media, optical media, magneto-
optical media,
etc.
6. Conclusion
Thus, what has been described is a method and apparatus for the coupling of
molding machine
structures to provide enhanced sealing while allowing for the thermal
expansion of the components.
The individual components shown in outline or designated by blocks in the
attached Drawings are all
well-known in the injection molding arts, and their specific construction and
operation are not critical
to the operation or best mode for carrying out the invention.
While the present invention has been described with respect to what is
presently considered to be the
preferred embodiments, it is to be understood that the invention is not
limited to the disclosed
embodiments. To the contrary, the invention is intended to cover various
modifications and
equivalent arrangements included within the spirit and scope of the appended
claims. The scope of
the following claims is to be accorded the broadest interpretation so as to
encompass all such
modifications and equivalent structures and functions.
All U.S. and foreign patent documents discussed above are hereby incorporated
by reference into the
Detailed Description of the Preferred Embodiment.
21
