Note: Descriptions are shown in the official language in which they were submitted.
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GAS VALVE PIN MECHANISM
Technical Field
The present invention relates to pin-type
valve-gate bushings and nozzles for use with gas-
assisted injection molding systems.
Background of the Invention
There are many processes and techniques today
for a gas-assisted injection molding. Gas-assisted
injection molding processes have added flexibility to
the design and manufacture of plastic parts with their
ability to produce partially hollow, lightweight, rigid
parts with minimal sink marks and less tendency to
warp. These processes can reduce material
requirements, as well as equipment costs and cycle
time, and thus have advantages over conventional
injection molding processes and techniques for many
applications.
In general, gas-assisted injection molding
systems utilize gas, under pressure, to expand the
plastic material in the mold and conform it to the mold
cavity details. The gaseous fluid can be introduced
into the mold in several ways, such as through a
bushing, or machine nozzle in one or more cavities, or
in more than one location. In conventional plastic
injection molding processes,' the molten plastic
material is injected through sprue bushings, heated or
unheated, into the cavities of hollow molds. Often,
two or more sprue bushings attached to a common
manifold are used. In this instance, the plastic melt
coming from the injection molding machine through
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runners is distributed by a heated distributor block
(or manifold) to the individual sprue bushings. One
conventional method used to control the melt flow
utilizes one or more pins or needle valves, also known
as valve-gate bushings.
With these systems, a needle valve is
inserted through the manifold into the sprue bushing
and controlled for axial movement by a hydraulic,
electric or pneumatic control device or mechanism. The
needle valve has an elongated pin member which is moved
axially by the control mechanism and is adapted to fit
within an orifice in the end of the sprue bushing in
order to open and close the passageway of plastic melt
from the sprue bushing into the mold cavity. A second
moveable pin member can be positioned inside the
elongated pin member and, via a valve mechanism at the
end of the two pin members, allow gas to enter the
plastic in the mold cavity.
Summary of the Invention
It is an object of the present invention to
provide an improved valve-gate bushing or machine
nozzle for use with a gas-assisted injection molding
process. It is also an object of the present invention
to provide an improved valve-gate bushing or nozzle
with a moveable gate pin which is biased to its closed
position and utilizes gas pressure to open the gas
orifice and allow gas to flow into the plastic in the
mold cavity.
The present invention provides an improved
valve-gate type bushing or nozzle for use with gas-
assisted systems, and fulfills the object and purposes
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noted above. The present invention provides a pin-type
valve-gate device which easily and effectively opens and
closes the flow of plastic material into the mold as
desired, and also easily and effectively opens and closes
the gas passageway into the mold cavity.
In particular, a moveable inner pin member is
provided which cooperates with an outer pin member to open
and close a gas passageway for passage of gas into the
plastic material in the mold cavity. The inner pin member
is biased by a spring washer or the like to its
valve-close position. Upon entry of gas into the annular
channel between the inner and outer pin members, the gas
acts on a large surface of the inner pin member which
overcomes the biasing force of the spring washer and opens
the gas passageway to allow gas to enter into the mold
cavity and plastic material. The ends of the outer and
inner pin members mate with each other creating a valve
or "gate" for entry of gas material into the mold cavity.
In a broad aspect, then, the present invention
relates to a gas pin mechanism comprising: an outer pin
member having an internal passageway; said outer pin
member having a first body portion, a first head portion
at one end and a first valve member at the other end, said
first head portion having a cavity therein; an inner pin
member; said inner pin member having a second body portion
positioned in said internal passageway, a second head
portion at one end and positioned in said cavity in said
first head portion and a second valve member at the other
end adapted to mate with said first valve member; a spring
member positioned longitudinally behind said second head
portion and biasing said inner pin member relative to said
outer pin member in a direction to mate said first and
second valve members; and said first valve member and said
second valve member forming a valve mechanism for
corltrolling the flow of a fluid material therethrough;
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wherein fluid material introduced against said second head
portion can overcome said biasing of said inner pin member
and separate said first and second valve members in order
to allow flow of fluid material therethrough.
In another broad aspect, then, the present
invention relates to a valve-gate bushing mechanism
comprising: a bushing having a first internal passageway
with a first valve member at a discharge end; and a gas
pin mechanism positioned in said bushing for controlling
the discharge of plastic material from said discharge end,
said gas pin mechanism comprising: an outer pin member
having a second internal passageway, a first body portion,
a first head portion at one end and a second and third
valve member at the other end adapted to mate with said
first valve member, said first head portion having a
cavity therein; an inner pin member; said inner pin member
having a second body portion positioned in said second
internal passageway, a second head portion at one end
positioned in said cavity in said first head portion, and
a fourth valve member at the other end adapted to mate
with said third valve member; a spring member positioned
longitudinally behind said second head portion and biasing
said inner pin member relative to said outer pin member
in a direction to mate said third and fourth valve
members; and said first and second valve members forming
a first valve mechanism for controlling the flow of a
plastic material therethrough, and third and fourth valve
members forming a second valve mechanism for controlling
the flow of a gas material therethrough.
In a further broad aspect, then, the present
invention relates to a valve-gate machine nozzle mechanism
comprising: a machine nozzle having a first internal
passageway with a first valve member at a discharge end;
arid a gas pin mechanism positioned in said bushing for
controlling the discharge of plastic material from said
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discharge end, said gas pin mechanism comprising: an outer
pin member having a second internal passageway, a first
body portion, a first head portion at one end and a second
and third valve member at the other end adapted to mate
with said first valve member, said first head portion
having a cavity therein; an inner pin member; said inner
pin member having a second body portion positioned in said
second internal passageway, a second head portion at one
end positioned in said cavity in said first head portion,
and a fourth valve member at the other end adapted to mate
with said third valve member; a spring member positioned
longitudinally behind said second head portion and biasing
said inner pin member relative to said outer pin member
in a direction to mate said third and fourth valve
members; arid said first and second valve members forming
a first valve mechanism for controlling the flow of a
plastic material therethrough, and third and fourth valve
members forming a second valve mechanism for controlling
the flow of a gas material therethrough.
These and other objects, features, and benefits
of the invention will become apparent from the following
description of the invention, when taken together in view
of the accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 clepicts a representative valve-type
bushing mechanism with which the present invention can be
utilized;
FIGURE 2 is a separate view of the piston and
pin mechanisni shown in Figure 1 apart from the bushing
mechanism;
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FIGURE 3 is an enlarged view of the inventive
pin mechanism in the closed position;
FIGURE 4 depicts the pin mechanism as set
forth in Figure 3 but with the gas valve member in the
open position allowing gas to enter the mold cavity;
FIGURE 5 illustrates an alternate proposed
use for the present invention; and
FIGURES 6 and 7 illustrate the use of the
present invention in a machine nozzle.
Best Modes For Carrying Out The Invention
Figures 3 and 4 illustrate a preferred
embodiment 10 of the present invention, while Figures
1, 2, and 5-7 depict representative uses of the present
invention in gas-assisted injection molding systems. In
this regard, the present invention is particularly
adapted to be used in gas-assisted injection molding
processes or systems and will be referred to herein in
that manner. However, it is to be understood that the
use of the term "gas" herein is not meant to be
limiting relative to the invention since other fluids
may be used in place of the gas.
Also, the present invention is particularly
adapted for use with sprue bushings or machine nozzles.
In this regard, the invention is described herein for
use with one type of sprue bushing 80 (see Figure 1)
and one embodiment of machine nozzle (Figures 6-7). Of
course, other sizes, shapes and types of sprue
bushings, machine nozzles, and the like can be used
with the present invention and fall within the spirit
and scope thereof.
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The valve-gate pin mechanism is generally
referred to by the reference numeral 10 in the
drawings. As particularly shown in Figures 3 and 4,
the pin mechanism includes an outer pin member 12
having an elongated passageway 13 and an inner pin
member 14 positioned within the elongated hollow
passageway 13. The outer hollow pin member 12 has an
elongated body portion 16 and an enlarged head portion
17. The head portion has a central cavity 18. The
inner pin member 14 similarly has an elongated body
portion 20 and an enlarged head portion 22. The head
portion 22 is positioned within cavity 18. A seal
member 24 is positioned in annular cavity or groove 25
in the head portion 22 in order to seal the two head
portions 17 and 22 together and prevent the passage of
gas or other fluids. It is to be understood that
alternatively a sealing member and groove could be
positioned in the wall of the cavity 18 for the same
purpose.
A cap member 30 is positioned on the head
portion 17 and has an insert portion 32 which fits
within the cavity 18. The cap member 30 can be secured
to the head portion 17 in any conventional manner, such
as by bolts or other fasteners, or by a mating threaded
mechanism 34.
A spring member 36 is positioned between the'
insert portion 32 and the head portion 22 of the inner
pin member. More specifically, the spring member 36 is
positioned between the lower surface 30A of the cap
member 30 and the upper surface 22A of the head portion
22.
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The spring member is preferably a spring
washer member, such as a Belleville washer. It is
understood, of course, that other spring biasing
members could be utilized in place of a spring washer
member such as a small coil spring member or the like,
and that more than one spring member could be utilized,
depending on the amount of biasing force desired.
The lower end 10A of the pin mechanism is
adapted to mate with an orifice 40 in a mold member 42
(or sprue bushing 80 or machine nozzle 200 as described
below). The orifice 40 opens into a cavity 44 in a
mating mold member 46. The lower end 10A mates with the
orifice 40 to form a valve mechanism which controls the
flow of plastic material from plastic passageway 48
into the mold cavity 44. Plastic is intro,duced into
the passageway 48 through conduit 49 from a plastic
injection molding machine ("IM") 50.
Pressurized gas from source 52 ("GAS") is
introduced through conduit 53 to passageway 13 in the
outer pin member 12. The movement of inner pin member
14 relative to outer pin member 12 controls the entry
of gas into the mold cavity 44. In this regard, the
lower end 13A of passageway 13 is tapered and forms a
valve mechanism 56 with the tapered lower end 14A of
inner pin member 14.
The spring member 36 biases the inner pin
member 14 towards the valve-closed position, as shown
in Figure 3. In this situation, the valve mechanism 56
is closed and prevents gas in passageway 13 from
entering the mold cavity 44. In order to open the
valve mechanism 56 to the valve-open position as shown
in Figure 4, pressurized gas from source 52 is
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introduced into passageway 13 where it acts on surface
22B of the head portion 22 of the inner pin member 14.
When the force of the gas, represented by arrow 60 in
Figure 4, overcomes the force of the spring member 36,
represented by arrow 62, the spring member flexes and
flattens allowing the inner pin member 14 to move
axially upwardly and open valve mechanism 56.
When gas pressure is not applied, some
plastic pressure in the mold cavity or runner system
will also act on surface 64 on the end of the inner pin
member 14. However, the area of surface 64 is
insufficient to provide a force sufficient to overcome
the force of the spring member 36.
In summary, when 'gas pressure is applied
inside the pin mechanism 10, a force is created which
unseats the valve pin and compresses the spring washer
36. When the washer compresses, the inner pin retracts
and allows a path for the gas to escape at the end of
the pins.
An annular groove 66 is provided on the end
12A of the outer pin member 12. The groove allows
plastic material injected into the mold cavity 44 to
form a seal which prevents gas introduced into the
cavity from passing around the outer surface of the
plastic part being formed in the mold cavity. The
seal helps direct the gas into the plastic mass in
order to form a hollow cavity and expand the plastic
against the walls of the mold cavity. The size of the
groove 66 is sufficiently.small to allow a thin flange
or flash of plastic to be formed therein as the plastic
starts to set up which, when forced against the walls
of the groove by the gas, forms a satisfactory seal.
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One preferred use of the present invention is
shown in Figures 1 and 2. As shown, the pin mechanism
is connected to a piston member 70 and utilized in
combination with a sprue bushing 80.
5 The sprue bushing 80 includes a body portion
82, a head portion 84, and an annular heater member 86.
The heater member 86 is preferably an annular coil or
resistive-type heating element and is powered by
electricity through conduit 88. Heat from the.heater
10 member 86 maintains the plastic material in central
passageway 90 in a molten condition.
The sprue bushing 80 is attached to a
manifold 92. The manifold 92 has one or more conduits
or passageways. 94 which are connected to an injection
molding machine ("IM") 50 which supplies molten plastic
material to the passageway in a conventional manner.
Plastic material in passageway 94 is maintained in a
molt.en condition by one or more heating elements (not
shown) positioned in or on manifold 92.
Passageway 94 has an opening 96 which is
aligned with the passageway 90 in the sprue bushing in
order to allow the flow of plastic material from the
injection molding 'machine into the mold cavity 44,
which is positioned in mold member 46. The sprue
bushing 80 is positioned in cavity 98 in mold member
100.
A tip member 102 is threadedly secured to the
end of the body member 82 of the sprue bushing 80. The
tip member 102 has an outer surface 104 which mates
with, and is positioned in, opening 106 in the mold
member 100. The tip member 102 also has a central
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orifice 40 which mates with the lower end or tip 12A of
the outer pin member 12.
The piston member 70 is positioned in cavity
110 in a block member 112. The piston member 70 is
adapted to slide axially or longitudinally in the
cavity or chamber 110 and is attached to the pin
mechanism 10. In particular, the cap member 30 of the
pin mechanism 10 is threadedly positioned in threaded
opening or passageway 120 in the piston member 70. The
threaded engagement between the pin mechanism 10 and
the piston member 70 provides a secure connection
between the two components and, at the same time,
allows adjustment of the pin member relative to the
piston member when desired in order to provide the
desired mating of the lower end of the pin mechanism 10
in the orifice 40. In this regard, adjustment of the
pin mechanism 10 axially relative to the piston member
70 can be accomplished by insertion of an instrument or
tool through central opening 120. A conventional
wrench socket or screwdriver slot 122 is provided in
the cap member 30 for this purpose.
A cap member 130 is secured to the top of the
block member 112 and securely holds the piston member
70 in the cavity 110. Movement of the piston member 70
in the chamber 110 is effectuated by introduction and
exhaust of fluid pressure from a fluid pressure source
("FPS") 132. The fluid pressure source 132 is
connected by conduits 134 and 136 to openings 135 and
137, respectively, which are in fluid communication
with cavity. 110 and on opposite sides of the piston
member 70.
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A plurality of seals or sealing members
retain the fluid pressure in the cavity 110. These
include seal 140 between the cap member 130 and the
block member 112, seal 142 between the cap member 130
and the piston member 70, a pair of seals 144
positioned between the piston 170 and the walls of the
chamber 110, and seal 146 which is positioned between
the block member 112 and the piston member 70. The
seals are positioned in annular grooves or cavities and
prevent leakage of the hydraulic or pneumatic fluid
from the fluid power source.
In operation, the piston member 70 is moved
axially in the chamber 110 by appropriate application
of fluid pressure from the FPS through openings 135 and
137. In this regard, pressure introduced through
conduit 134 and opening 135 will force the piston
member 70 toward surface 110A of the chamber 110 and in
turn lower the pin mechanism 10 into mating engagement
with orifice 40. Similarly, when fluid pressure is
relieved from chamber 110 through conduit 134 and fluid
pressure is activated through conduit 136, the piston
member 70 will be moved in chamber 110 toward surface
130A on the cap member 130, thus raising the pin
mechanism 10 and opening the orifice 40.
Gas or other desired fluid is introduced
through conduit 53 into the annular passageway 13
between the outer pin member 12 and the inner pin
member 14. In this regard, the operation of the pin
mechanism 10 relative to allowing introduction of gas
from source 52 into the plastic material P in the mold
cavity 44 is the same as that described above with
reference to Figures 3 and 4. Thus, when gas is
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supplied from source 52 into the annular passageway 13
between the pin members 12 and 14, the spring member 36
is compressed, and the inner pin member 14 is moved
axially upwardly relative to outer pin member 12
allowing gas to flow into the plastic material P. At
the rest or closed position when gas is not being
supplied to pin mechanism 10, the spring member 36
provides a biasing force on the inner pin member 14
preventing gas from flowing through the annular
passageway and into the plastic material.
In operation of the injection molding system
shown in Figures 1 and 2, the piston member 70 is moved
longitudinally in the block member 112 in order to open
and close the orifice 40 to allow introduction of
plastic material from the injection molding machine 50
into the mold cavity 44. In this regard, when the
piston member 70 is in the position show'n in Figure 1,
the lower end 10A of the pin mechanism 10 is raised
above the orifice 40 allowing plastic in passageway 90
to flow into the mold cavity 44. When the desired
amount of plastic material is injected into the mold
cavity, the fluid power source is activated and the
piston member 70 is moved to the position shown in
Figure 2. This causes the lower end l0A of the pin
mechanism 10 to mate with the orifice 40 and prevent
further flow of plastic material into the mold cavity.
In this regard, the lower end l0A of the pin mechanism
10 and the walls of the orifice 40 form a valve
mechanism 56.
When it is desired to inject gas or another
fluid into the plastic material in the mold cavity, gas
is introduced from source 52 into the annular
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passageway in the pin mechanism 10, thereby moving
inner pin member 14 relative to outer pin member 12 and
allowing gas to enter the plastic material P as
described above with reference to Figures 3-4.
The gas pressure is held in order to pack out
the molded part, which also keeps the inner pin
retracted. When the gas pressure is released or
vented, the inner pin stays retracted until the
remaining pressure in the system decreases sufficiently
for the force of the compressed washer to overcome the
force generated by the gas. When the inner pin shuts
off again, the pressure of the remaining gas in the
part is sufficiently low in order not to damage the
part upon ejection from the Ynold.
The block member 112 is separated or spaced
from the manifold 92 by a plurality of spacers or
risers 99. The block member 112, spacer members 99,
manifold 92 and mold member 100 are connected together
in a conventional manner, such as by bolts, other
fasteners, clamp mechanisms, and the like.
Another embodiment illustrating use of the
present invention is shown in Figure 5. In this
embodiment, the gas valve pin is used in a single
valve-gate application.
In Figure 5, the present inventive pin
mechanism 10 is used with a system or mechanism which
controls the flow of plastic material into an injection
mold cavity. In this regard, plastic material is
injected from an injection molding machine ("IM" ) 50
directly into an adapter mechanism 150 which is
attached to a sprue bushing 152. Plastic from the
injection molding machine 50 is inserted through
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passageway 176 in adapter member 150 and into
passageway 162 in the sprue bushing 152. The sprue
bushing 152 is similar to the sprue bushing 80 as
described above with reference to Figure 1. The sprue
bushing 152 has a central body member 154, a head
member 156, an annular heating member 158 and a tip
member 160. The body member 154 has a central
passageway 162 in which plastic material is allowed to
pass through into a mold cavity 174. The sprue bushing
152 is positioned in a cavity 164 in a mold member 166.
The mold member 166 has an opening 170 in which the
tip member 160 is positioned. Mold member 172 is
positioned in contact with mold member 166 and contains
cavity 174 in which the plastic material is injected.
Axial movement of the pin mechanism 10 opens
and closes the valve member 56 in the sprue bushing in
order to either allow the injection of plastic material
into the mold cavity or prevent further injection.
Movement of the pin mechanism 10 is actuated by
actuation mechanism 180. Actuation member 18'0 includes
a pivoted arm member 182 and a piston mechanism 184.
The piston mechanism 184 includes a piston member 186
positioned in a chamber 188 in a housing 190. Fluid
from a fluid pressure source 132 operates and controls
the operation of the piston member 186 in the cavity
188. Operation of the piston member 186 in turn
operates movement of rod member 192 in the direction of
the arrow 194. Movement of the rod member 192 pivots
arm member 182 around pivot member 183. One end 182A
of the arm member 182 is attached to the upper end 10B
of the pin mechanism 10 while the other' end 182B of
the arm member is connected to the rod member 192.
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Pivoting of the arm member 182 acts to move the pin
mechanism 10 axially or longitudinally relative to the
sprue bushing 152. This in turn opens and closes the
valve member 56 which controls the injection of plastic
material into the mold cavity.
In operation, movement of the piston member
186 and rod member 192 moves end 182B of the arm member
182 which in turn moves end 182A of the arm member 182.
in the opposite direction causing the pin mechanism 10
to open and close the valve mechanism 56. Adjustment
of the position of the pin mechanism 10 in forming the
valve mechanism 56 is accomplished by adjusting the
length of the rod member 192 relative to the piston
member 186. The rod member 192 is threadedly secured
to the piston member 186 by threads 193 for this
purpose.
Figures 6 and 7 illustrate the use of the
present invention in a machine nozzle. A machine
nozzle is a standard part of an injection molding
machine. In Figure 6, the injection molding machine
is generally referred to by the reference numeral 202.
The injection molding machine 202 is typically
positioned on a common base 204, together with a pair
of platen members 206 and 208, which are used to hold
a mold 210 for formation of a molded plastic part. The
injection molding machine 202 typically includes a body
212, a hopper 214, and a barrel member 216, together
with the machine nozzle 200. As indicated, the machine
nozzle 200 is positioned on the forward end of the
barrel 216. In this regard, the machine nozzle 200 is
typically threaded or screwed onto the end of the
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barrel member 216 and held by a plurality of threads
218, as shown in Figure 7.
In an injection molding process, plastic
pellets are inserted into the injection molding machine
202 through the hopper member 214 into a central cavity
or chamber (not shown). A rotating screw member (not
shown) is positioned in the chamber and is used to
convey the plastic material through the barrel and
machine nozzle and into the mold cavity 220. A
plurality of heater members 222 positioned on the
outside of the barrel member 216 and other strategic
locations on or in the injection molding machine 202
melt the plastic material and keep it in a molten
condition so that it can be injected through the
machine nozzle and into the mold cavity. In this
regard, a heater member 224 is also typically
positioned around the outer end of the machine nozzle
200, as shown in Figure 7. The heater member 224 is
typically a coil or resistant heater and, in this
.20 instance, is energized or powered through a lead or
connector 226.
The platen member 206 is moveable relative to
stationary platen member 208. The two platen members
are connected and moveable along rod members 230. In
this regard, typically four rod members 230 are
provided.
The mold 210 typically comprises a core
member 232 and a cavity member 234. The two mold
members (232 and 234) are connected to the two platen
members 206 and 208, respectively. In this manner, the
mold 210 can be opened or closed depending on relative
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movement of the platen member 206 relative to the
stationary platen member 208.
The machine nozzle 200 is inserted through an
opening 240 in platen member 208 and forced directly
against a "sprue bushing" 242 or the like in order to
inject molten plastic material directly into the mold
cavity 220. For this purpose, the machine nozzle 200=
has a tip member 244 at its outer or digital end which
has a spherical mating surface 246 for mating with the
"sprue bushing" or the like. The tip member 244 is
typically threadedly secured to the end of the machine
nozzle 200 by thread mechanism 248.
Molten plastic material entering the machine
nozzle 200 is inserted into passageway 250 at end 252
and subsequently injected into the mold cavity through
an orifice 254 in the tip member 244. The passageway
250 includes a first portion 250A, a second portion
250B, and a third portion 250C. The passageway
portions 250A and 250B are angled, as shown in Figure
7, in order to provide space for the actuation
mechanism 260 which is explained in more detail below.
The passageway:portion 250C is centrally located in
the machine nozzle 200 and allows plastic material to
flow around pin mechanism 10 and into the tip member
244.
The pin mechanism 10 is substantially the
same as the pin mechanism 10 described above with
reference to Figures 1-5. In this regard, the pin
mechanism 10 includes an outer pin member 12 having an
elongated passageway 13 and an inner pin member 14
positioned within the passageway 13. The hollow outer
pin member 12 has an elongated body portion 16 and an
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enlarged head portion 17. The head portion has a
central cavity 18. The inner pin member 14 similarly
has an elongated body portion 20 and an enlarged head
portion 22, which is positioned within the cavity 18.
A cap member 30 is positioned on the head
portion 17, and the spring member 36 is positioned
between the cap member and the head portion 22. The
spring member 36 is preferably a spring washer member,
such as a Belleville washer, although other equivalent
spring biasing members can be utilized, as set forth
above.
The lower end l0A of the pin mechanism is
adapted to mate with the orifice 254 in the tip member
244 on the nozzle member 20d. The lower end 10A and
orifice 254 form a valve mechanism which controls the
flow of plastic material from the plastic passageway
250 and eventually into the mold cavity 220.
Pressurized gas from source 52 (GAS) is
introduced through conduit 53 to passageway 13 in the
outer pin member 12. The movement of the inner pin
member 14 relative to the outer pin member 12 controls
the entry of gas into the mold cavity 220. In this
regard, the 'lower end of the passageway 13 is tapered
and forms a valve mechanism with a corresponding
tapered lower end of inner pin member 14 (as explained
above ) .
Pin mechanism 10 operates in the same manner
as described above. In summary, when gas pressure is
applied inside the pin mechanism 10, a force is created
which unseats the valve pin and compresses the spring
washer 36. This allows gas to flow from the pin
mechanism and into the plastic material and mold
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cavity. When the washer compresses, the inner pin
retracts and allows a path for the gas to flow at the
end of the pin.
Movement of the pin mechanism 10 is actuated
by actuation mechanism 260. The actuation member 260
includes a pivoted arm member 262 and a piston
mechanism 264. The piston mechanism 264 includes a
piston member 266 positioned in chamber 268 in housing
290. Fluid from a fluid pressure source ("FPS") 292
operates and controls the operation of the piston
member 266 in the cavity 268. Operation of the piston
member 266, in turn, operates movement of rod member
294 in the direction of the arrow 296. Movement of the
rod member 294 pivots the arin member 262 around pivot
member 263. One end 262A of the pivoted arm member 262
is attached to the upper end 10B of the pin mechanism
10, while the other end 262B of the arm member 262 is
connected to the rod member 294. Pivoting of the arm
member 262 acts to move the pin mechanism 10 axially or
longitudinally relative to the machine nozzle 200.
This, in turn, opens and closes the orifice 254, which
controls injection of plastic material into the mold
cavity.
The operation of the pivot member 262 is
substantially the same as the operation of the pivoted
arm member 182 described above with reference to Figure
5. In operation, movement of the piston member 266 and
rod member 294 moves the end 262B of the arm member 262
which, in turn, moves the end 262A of the arm member
262 in the opposite direction, causing the pin
mechanism 10 to open and close the valve mechanism at
the orifice 254. Adjustment of the position of the pin
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CA 02426858 2003-04-22
WO 02/34496 PCT/US01/46060
mechanism 10 in forming the valve mechanism is
accomplished by adjusting the length of the rod member
294 relative to piston member 266. The rod member 294
is threadedly secured to the piston member 266 by
threads 295 for this purpose.
While the invention has been described in
connection with orne or more embodiments, it is to be
understood that the specific mechanisms and techniques
which have been described are merely illustrative of
the principles of the invention. Numerous
modifications may be made to the methods and apparatus
described without departing from the spirit and scope
of the invention as defined by the appended claims.
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