Note: Descriptions are shown in the official language in which they were submitted.
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BACK~ROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus
for forming oriented thermoplastic articles, and more par-
ticularly to a method and apparatus utilizing moveable blow
pins for transporting blown pre-forms through a thermal con-
ditioning region prior to the final blowing operation.
2. The Prior Art
In the art of blow molding thermoplastic articles, the
so-called "blow and blow" technique has become widely used
for molecular orientation. In such operations, a blowable
plastic parison is positioned within a first mold cavity and
blown to a pre-form configuration. Next, the pre-form is
positioned within a second mold cavity, where it is blown to
a configuration of the final container. This general overall
process has undergone several refinements, including a se- `~
quential blow, stretch, and blow technique as disclosed in
United States Patent No. 3,781,395.
Even though the overall operation of Patent No. 3,781,
395 advanced the art of molecular orientation, this patent
does not disclose a thermal conditioning means between the
pre-form mold and final blow mold. Thus, the blown pre-form
must be maintained in the pre-form mold for a sufficient period
of time to bring the plastic material temperature to within the
range for molecular orientation. Depending upon the material
being used, an unnecessarily long dwell time may be required
for the pre-form in the first mold cavity, thereby prolonging
the overall "blow and blow" operation cycle.
United States Patent No. 3,873,660,
proposes that the temperature of a blown pre-form be
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adjusted within a thermal conditioning chamber between the
pre-form molding station and the final molding station.
The apparatus disclosed in this patent, however, requires pre-
form handling and trimming mechanism which can adversely
affect the temperature for optimum molecular orientation.
Applicants here propose to overcome these disadvantages
in the prior art by the use of a plurality of moveable blow
pins from which the blow preforms suspend while in a thermal
conditioning chamber in transit to the final blow molding
station. Although moveable blow pins, per se, are disclosed
in United States Patent No. 3,599,280, and pre-form conveying
systems are disclosed in United States Patent No. 3,324,507,
these patents do not provide the overall advantages, method,
or apparatus of the present invention.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus
for blowing a plastic parison into a pre-form, thermally con-
ditioning the pre-forms to a temperature conducive to molecular
orientation, and then blowing the thermally conditioned pre-
form to a final article. The method utilizes the pre-forming
step to thermally pre-condition the plastic material by direct
mold contact prior to a secondary thermal conditioning step
within a separate thermal region.
In a first proposed embodiment, a plurality of indepen-
dently moveable blow pins are utilized for transporting the
blown pre-forms from a pre-form molding station to the final
molding station, the blow pins being connected to individual
carrier plates that are slideable along guide rails. These
independently moveable blow pins are inserted into an open
end portion of a mold-enclosed parison at the pre-form molding
station. Air under pressure is supplied through the blow pin
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to inflate the parison to a pre-form configuration. After
the molding operation, the pre-form mold sections are opened,
leaving the blown pre-form pendently suspended from the move-
able blow pin, which is then indexed into a thermal condition-
ing chamber.
In accordance with the invention, the thermal condition-
ing chamber adjusts the temperature of the pre-form to within
a range conducive to substantial molecular orientation in a
final molding operation. After the proper thermal treatment,
the moveable blow pins with suspended pre-forms are then moved
to a final molding station where the pre-form is blown to the
final article and the plastic material is molecularly oriented.
In the appartus of this first embodiment, the pre-form
mold, thermal conditioning chamber, and final blow mold are
arranged on one seneral horizontal level and the moveable blow
pins are moved from the pre-form blowing station to the final
blowing station along a set of guide rails. After the blow
pins are used in the final blowing operation, they are lifted
to a position above the final blow mold and then intermittently
moved back to a position generally above the pre-form mold.
When positioned above the pre-form mold, the blow pin carrier
plates are inserted within a descent yoke and lowered to
insert the blow pins in an open ended portion of a mold-enclosed
parison.
In a second embodiment, the moveable carriers, or blow
pins, are attached to a chain-type system which progressively
and intermittently moves the blow pins through a thermal con-
ditioning chamber to a final blow molding station. In this
embodiment, a separate blow nozzle is used at the pre-form
molding station for inflating the parison to a pre-form con-
figuration. A set of bracket arms are attached to the pre-form
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molds for transporting the blown pre-form from the blowing
nozzle to the moveable blow pins. These bracket arms include
vertically reciprocal members which grasp the outer surface of
the blown pre-form neck for t~lescopically inserting the pre-
form neck over the moveable blow pins. Then, the bracket armsrelease the pre-form necks, leaving the pre-form pendently
suspended from the moveable blow pins for displacement through
the thermal conditioning means to the final blowing station.
With respect to the present teachings, an improvement is
provided in an apparatus for blow molding plastic containers
which includes a first sectional blow mold for receiving suc-
cessive blowable parisons, the parisons being blown within a
mold cavity of the first sectional blow mold to successive
pre-forms which have a blown plastic body surmounted by a neck,
a second sectional blow mold for successively receiving the
blown pre-forms, the pre-forms being blown within a cavity of
the second blow mold to the final containers and a thermal
conditioning ch~r interposed between the first and second
molds and including means for adjusting the temperature of the
blown body of the pre-forms to within a range conducive to
molecular orientation. The improvement which is provided
includes a plurality of laterally moveable blow pins for
pendently conveying the blown pre-forms through the thermal
conditioning chamber to the final blown mold, each blow pin
includes a d~wM=~ly directed nozzle portion which includes a
substantially cylindrical surface for telescopically fitting
within and engaging the neck portion of a pre-form, means is
provided for intermittentily and successively displacing the
blow pins with pendently suspended pre-forms from the thermal
conditioning chamber to the final blow mold, means is provided
for injecting air through the moveable blow pins into the
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pre-forms at the final mold to form the blown plastic
containers, and each blow pin has an axial, generally
vertical bore therethrough w~th the means for injecting blow
air includes a vertically reciprocal blow nozzle at the second
blow mold station in alignment with the blow pin bores as each
blow pin is positioned at the second blow mold; and means
provided for downwardly displacing the blow nozzle through the
blow pin bore to engage and longitudinally stretch the blown
pre-form, with the blow nozzle having a blow air passageway
therethrough to supply blow air under pressure.
Various alternative structures are also disclosed for
use with either of the two primary overall embodiments. First,
means are disclosed for rotating the blow pins while in the
thermal conditioning chamber to achieve a more uniform peri-
; 15 pheral pre-foxm temperature. Second, a replaceable blow pin
is disclosed, as being releaseably maintained in a blow pin
carrier by a snap-fit arrangement. Third, means are disclosed
for stretching the blown pre-form prior to the final blowing
operation.
It is therefore an object of the present invention to
provide a method and apparatus for continuously manufacturing
blown plastic articles, for reducing overall operational cycle
time and for reducing apparatus components.
A further object of the invention is to provide a molding
method and apparatus capable of accurately adjusting the tem-
perature of a pre-form to within the range for substantial
molecular orientation during a final blowing operation.
Still another object is to provide a method and apparatus
capable of rapidly quenching plastic material from melt
temperature during a pre-form molding operation to create shape
stability and to control crystalline structure.
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Other objects of this invention will appear from the
following description and claims.
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BRIEF DESCRIPTION OF THE DRA~INGS
; Figure 1 is a schematic elevational view of one embodi-
ii~ ment proposed by the present invention for thermally condition-
ing a blown pre-form while suspended on a moveable blow pin.
Figure 2 is a top plan view taken along plane 2-2 as
indicated in Figure 1.
Figure 3 is a perspective view of the blow pin carrier
descent yoke utilized in the embodiment of Figure 1.
Figure 4 is a schematic cross-sectional view taken
along plane 4-4 as indicated in Figure 1, illustrating the
thermal conditioning chamber with a pre-form suspended from a
moveable blow pin.
Figure 5 is a schematic cross-sectional view taken along
plane 5-5 as indicated in Figure 1, illustrating the final
blow mold station.
Figure 6 is a schematic elevational view illustrating
the parison ejection station and blow pin carrier lift mech-
ansim.
Figure 7 is a schematic elevational view of an alter-
native mechanism for spinning the suspended pre-forms while
in a thermal conditioning chamber to provide a uniform per-
ipheral pre-form temperature.
Figure 8 is a cross-section elevation view taken along
plane 8-8 as indicated in Figure 7.
Figure 9 is a schematic top plan view of a second em-
bodiment for thermally conditioning a blown pre-form as it is
suspended from a moveable blow pin.
Figure 10 is a cross-sectional view taken along plane 10-
10 as indicated in Figure ~, illustrating the pre-form mold
and pre-form conveyor arm proposed for this embodiment.
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Figure 11 is a view similar to Figure 10, illustrating
the manner of inserting a blown pre-form onto a moveable blow
pin.
Figure 12 is a cross-sectional view taken along plane
12-12 as indicated in Figure 9, illustrating suspended pre-
forms in the thermal conditioning chamber.
Figure 13 is a cross-sectional elevation view illus-
trating an alternative blow pin proposed for use in the embodi-
ment of Figure 9, as it is positioned at a final blowing
station.
Figure 14 is a cross-sectional elevation view similar
to Figure 13, illustrating the pre-form in a stretched con-
dition prior to final blowing.
Figure 15 is a cross-sectional elevation view similar
to Figures 13 and 14, illustrating the final blown container
within the final blow mold.
Figure 16 is a cross-sectional view taken along plane
16-16 as illustrated in Figure 15.
Figure 17 is a cross-sectional elevational view taken
along plane 17-17 as illustrated in Figure 9.
DETAILED DESCRIPTION OF T~IE PREFERRED EMBODIMENTS
The overall method and apparatus of this disclosure
relates to forming a plastic parison, blowing the plastic
parison to a pre-form configuration in a first mold cavity,
thermally conditioning the blown pre-form while suspended from
a moveable blow pin, and then blowing the thermally conditioned
pre-form within a final blow mold. Referring to the drawings,
and in particular Figures 1 and 2, a first embodiment is
illustrated for carrying out this overall process.
Reference numeral 20 indicates an extruder which includes
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a downwardly directed annular orifice structure 22 from which
a generally tubular thermoplastic parison 24 issues, either
continuously or intermittently as is well known in the art.
A pre-form mold 25 includes mold sections 26 and 28
which are mounted on tie rods 3Q and 32 for transverse sliding
movement relative to one another by hydraulic cylinders and
pistons 34,36,38, and 40, respectively. When closed, as
shown in Figure 2, the pre-form mold sections define a neck
or finish region 41 and a pre-form cavity 42 against which
the parison is expanded to form a blown pre-form.
Figure 1 also illustrates an inclined actuating cylinder
44 having a piston rod 46 that is secured to tie rod 32 for
moving the pre-form molding assembly 25 from the pre-form mold
position illustrated in Figures 1 and 2 to a position illustra-
ted in phantom in Figure l for receiving a tubular parison 24.
The sequence of operation for positioning a tubular
parison within a pre-form cavity 42 at the pre-form molding
station is as follows. First, hydraulic cylinders 34 and 38
are actuated to retract piston rods 36 and 40 to thereby open
the pre-form mold sections 26 and 28. Next, hydraulic cylinder
44 is actuated to extend piston rod 46 and position the opened
pre-form mold sections on each side of the extruded tubular
parison 24. The pre-form mold sections 26 and 28 are then
closed by hydraulic cylinders 34 and 38 to pinch the parison
shut at its bottom end. A conventional blade 48 then severs
the mold enclosed parison portion from that portion of the
parison which is issuing from the extruder nozzle 22, thereby
forming an open-ended parison portion to receive a blow pin
at the pre-form molding station. Piston rod 46 is then re-
tracted and moves the closed pre-form mold sections 26 and
28 to the position shown in Figures 1 and 2.
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In accordance with the embodiment of Figure 1, a plur-
ality of independently moveable blow pins, or carriers, 50,52,
54,56,58,60,62 and 64 are provided for successive insertion
into the severed, opened ends of blowable plastic parisons
enclosed in the pre-form mold 25. As illustrated, blow pin
50 is supported within a descent yoke 70 at the pre-form mold-
ing station; blow pins 52 and 54 are supported on guide rail
sections 98A and 98B in a thermal conditioning chamber 102;
blow pin 56 is supported on guide rail sections at the final
blowing station; blow pin 58 is supported within a lift
mechanism 150; and blow pins 60,62 and 64 are supported on
guide rails sections 170, prior to placement within the descent
yoke assembly 70 for insertion within a blowable parison at the
pre-form molding station.
As best illustrated in Figures 4 and 5, each blow pin
includes a downwardly directed, dome-shaped terminal nose
portion A, for example 54A and 56A, which is dimensioned to
fit within the open end portion of a parison, so that the pre-
form can be suspended therefrom. An enlarged cylindrical shaft
portion B, for example 54B and 56B, surmounts the blow pin nose
and is threadly received in a blow pin carrier plate C, for
example 54C and 56C. A bore extends through each blow pin
carrier plate and blow pin shaft and nose, as illustrated in
Figure 5, to supply blow air into the parisons and pre-forms
during the molding operations.
As illustrated in Figure 1, blow pin carrier plate 50C
is supported within the yoke descent assembly 70, with the blow
pin nose 50A inserted within the open-ended neck portion of a
mold enclosed parison. The yoke assembly 70 is illustrated in
the perspective view of Figure 3 and includes a vertical abut-
ment plate 72, a top horizontal pressure plate 74, and two
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parallel support arms 76 and 78 extending from the vertical
abutment plate 72. Thus, the blow pin carrier plate C fits
between top pressure plate 74 and rests upon the two horizontal
support arms 76 and 78, with the blow pin extending downwardly
between the slot between the two horizontal support arms.
The descent yoke assembly is raised and lowered by a
hydraulic cylinder 80 and piston rod 82, which is rigidly
connected at its lower end to the top horizontal pressure
plate 74. Prior to placement within the descent yoke assembly
70, blow pin 50 was supported on guide rail sections 170 at
the position where blow pin 64 is illustrated in Figure 1.
The descent yoke assembly was raised to the position as illus-
trated in phantom in Figure 1, and blow pin 50 was pushed hori-
zontally into a descent yoke assembly as will be more fully
explained below.
With the blow pin 50 and descent yoke assembly position-
ed as illustrated in Figure 1, the mold-enclosed parison is
blown to the pre-form configuration by injecting air under
pressure through a blow line 84, into a bore 86 which extends
through piston rod 82 and top pressure plate 74, and then
through the bore of the blow pin. The preform may be removed
from the preform mold prior to being cooled to room temperature,
thus serving (a) to reduce the energy required for reheating
to orientation temperature and (b) to reduce the time required
within the next adjacent thermal conditioning chamber. After
the pre-form has been blown, conventional tail pullers 88 are
actuated to remove excess plastic material depending from the
pre-form mold cavity.
An indexing mechanism 90 is provided for displacing blow
pin 50 from within the descent yoke 70 after the formation of
the pre-form and after the pre-form mold sections have been
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opened. The indexing mechanism includes a hydraulic cylinder
92, a piston rod 94, and a pull plate 96, the hydraulic
cylinder 92 being secured to the top of thermal conditioning
chamber 102 by suitable means. As illustrated in Figure 2,
pull plate 96 is securely mounted to the end of piston rod
94 and extends laterally therefrom for alignment with at least
a portion of the blow pin carrier plate. Thus, to move blow
pin 50 from descent yoke 70, piston rod 94 is retracted and
pull arm 96 displaces blow pin 50 to the position previously
occupied by blow pin 52. Blow pin 50 in turn pushes blow pin
52 to the position previously occupied by blow pin 54 and so
on, so that blow pin 56 is pushed to a position beneath lift
assembly 150 as supported partially on guide rails sections 98,
99, and 100. As illustrated in Figures 4 and 5, the guide
rails sections are comprised of sets of L-shaped members, for
example, 98A and 98B. Guide rail sections 98,99 and 100
are longitudinally spaced to provide clearance for components
of the lift assembly 150, as will be explained in greater
detail below.
Reference numberal 102 indicates a thermal conditioning
chamber which has a dual purpose in the present invention.
First, the chamber reduces the cure time for the blown pre-
form within the pre-form mold and therefore reduces the over-
all cycle time for the "blow and blow" process. Second, the
thermal conditioning chamber provides the ability to very
accurately adjust the temperature of the preforms to within
the optimum range for the most effective molecular orientation
of plastic material in the final blowing operation. As ill-
ustrated in the drawings, the pre-forms are pendently suspended
from the moveable blow pins while in the thermal conditioning
chamber so that the body of the pre-forms are not in communi-
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cation with other transporting members which could conductheat and therefore adversely affect the pre-form thermal con-
dition. It should be noted also that no additional handling
means are necessary for transporting the thermally conditioned
pre-forms from chamber 102 to the final blowing station. That
is, the thermally conditioned pre-forms remain in a suspended
position from the moveable blow pins for placement in the
final blowing position.
To achieve proper pre-form temperature, a variety of
thermal condition sources may be utilized, depending upon the
particular material being used. For example, Figure 4 illus-
trates a plurality of heating coils or rods 104 for supplying
heat to the thermal conditioning chamber. These heating rods
could be replaced with hot air sources, or even alternatively
cool air sources. Specifically, heating sources may be utili-
zed when the blown pre-form is maintained in the pre-form mold
for a significant period of time and becomes cooled, for
example, for transfer stability. In this instance, the pre-
form would be re-heated to a temperature conducive to a
optimum molecular orientation. As is known in the art, the
most preferable orientation temperature is just above the
glass transition temperature point for the particular plastic
material being used.
In certain instances, the thermal conditioning chamber
may include cool air sources. For example, when thick, heavy
weight polyethylene material is used to form bottles, the
curing time in the pre-form mold may not cool the material
to the optimum temperature for substantial molecular orienta-
tion.
In other situations, it may be desireable to adjust
different portions of the pre-form to differing temperatures,
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so-called differential temperature adjustment. For example,
the heel sections of a blown pre-form may be adjusted to a
temperature cooler than the remaining portions of the pre-form
since it is known that cool sections expand to a less extent
during final blowing. Therefore, cool air sources could be
positioned in the bottom portion of the thermal conditioning
chamber with warmer air sources being provided for the bl~wn body
portion of the pre-form. Further, as will be discussed in
regard to Figures 7 and 8, it may be desirable to rotate the
blown pre-form while in the thermal conditioning chamber to
achieve a more uniform temperature distribution around the
entire pre-form periphery.
Turning now more specifically to Figure 5, the final
blow mold is illustrated as including a pair of sectional
mold halves 106 and 108 which are securely mounted on platens
110 and 112 in any conventional manner. The platens 110 and
112 are slideably transversely toward and away from one another
by power means 113 and 114 (Figure 2) along tie rods 115 and
116. When closed, the blow mold sections 106 and 108 define
a final blow mold cavity 118 which surrounds the pendently
supported, thexmally conditioned pre-form. From Figure 5, it
should be noted that the final blow mold sections 106 and 108
initially contact the pre-form substantially only at the pre-
viously formed pre-form neck portion, thus maintaining the
desired pre-form orientation temperature for the body of the
pre-form until the final blowing operation.
The means for supplying blow air to the pre-form for the
final blowing operation comprises an arm 120 which is pivotally
mounted on a hinge pin 122 that extends between upstanding
arms 124 and 126 on platen 110. One end of the arm 120 is
pivotally connected by a pin 128 to a piston rod 130 of a
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hydraulic cylinder arrangement 132 that is suitably mounted
by a bracket 134 to platen 110. A coupling 136 is threadly
: secured within the other end portion of pivotal arm 120 and
establishes fluid communication between an air supply line 138
and a bore 140 for accommodating the supply of blow air through
the bore in the blow pin for blowing the pre-form to the con-
figuration of the final article. As illustrated, a suitable
gasket 142 may be secured to the bottom surface of pivotal
arm 120 in alignment with bore 140 so that a fluid-tight
connection will be achieved between the pivotal arm 120 and
the blow pin carrier plate 56C.
- The operational sequence of the final blowing station
is as follows. After the pre-form has been blown to the final
blown article, during which blowing operation substantial
molecular orientation is accomplished because the pre-form
is at a temperature conducive to orientation, piston rod 130
is retracted to pivot arm 120 about hinge pin 122, thus lifting
gasket 142 away from the top surface of blow pin carrier plate
56C. Next, hydraulic power sources 113 and 114 are actuated
to displace platens 110 and 112 away from each other, leaving
the blown final article pendently suspended from blow pin 56.
When the indexing mechanism 90 is actuated to pull blow pin
50 from the pre-form molding station to a position within the
thermal conditioning chamber, blow pin 56 in turn pushed to
a position beneath a lift mechanism 150 and blow pin 54 with
a thermally conditioned pre-form is pushed to a position
between the opened mold sections 106 and 108. Next, the
hydraulic sources 113 and 114 are actuated to displace plates
110 and 112 along tie rods 115 and 116, thereby enclosing the
pre-form on blow pin 54 within mold cavity 118. Piston rod
130 is then extended to the position shown in ~igure 5 so
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that communication is established between air supply bore
140 and the bore extending through blow pin 54. A suitable
valving mechanism (not shown) then supplies blow air through
supply line 138, and another blown article is formed.
While blow pin 56 is positioned at the final blowing
station, blow pin 58 is supported with a suspended final
article 144 on guide rail sections 98,99 and 100. At this
position, the final blown article is ejected from the blow
pin by any suitable means for position on a conveyor belt
146.
As illustrated in Figure 1, ejection of article 144
has been accomplished and blow pin 58 is supported within a
lift mechanism 150. As illustrated in Figures 1 and 6, the
lift mechanism includes four lift arms 152 having inwardly
directed flanges 153 for supporting and lifting the blow pin
carrier plates. The lift arms 152 are each pivotally mounted
to tab members 154 by pins 156, the tabs extending from a
central lift body 158 which is raised and lowered by a piston
rod 160 of a hydraulic cylinder 162. Hydraulic cylinders 164
and piston rods 166 are pivotally mounted at respective ends
to each set of lift arms 152 by pins 168 and 170.
As illustrated in Figure 1, lift mechanism 150 is in
the process of raising blow pin 58 from the lower guide rails
sections. The assent of the lifting mechanism will continue
until blow pin carrier plate 58C is in horizontal alignment
with the blow pin carrier plates of blow pins 60,62 and 64,
as supported on guide rail sections 170 which are similar in
shape and configuration with guide rail sections 98,99 and 100.
At this position, blow pin carrier plate 58C will also be in
horizontal alignment with a push rod 172, which in essence is
a piston rod of a hydraulic cylinder 174. To remove blow pin
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58 from the li~t assernbly 15u, push rod 172 is extended toengage the end sur~ace of blow pin carrier plate 58~ and
then to shove the blow pin onto the guide rail surfaces 170.
At this same time, the descent yoke assembly 7û will be
positioned as illustrated by the phantom lines in Figure 1.
When blow pin 58 is pushed onto guide rail 170 it will engage
blow pin 6û and therefore push blow pins 6û, 62 and 64 to the
left as viewed in Figure 1, with blow pin 64 being pushed
into the descent yoke assembly 7û for displacement to the pre-
form blowing station.
nydraulic cylinders 164 are then activatea to pivot arms
152 outwardly about hinge pins 156. Piston rod 16û is then
lowered, and the outwardly pivoted flange surfaces 153 clear
a blow pin carrier plate positioned on guide rail surfaces 98,
99, and lûû. When the lift mechanism 150 is positioned in
its lowermost descent, pivot arms 152 fit between the spaces
between guide rail sections 98, 99 and 100. At this position,
hydraulic cylinders 164 are activated to inwardly pivot flange
support surfaces 153 for engaging the bottom surface of a blow pin
carrier plate. Next, hydraulic cylinder 162 is activated
and piston rod 162 raises the lift mechanism.
Turning now to Figures 7 and 8, an alternative embodiment
is provided for spinning the pendently suspended pre-forms
while in the thermal conditioning chamber to achieve a more
uniform peripheral temperature. This embodiment is especially
useful when heating coils or bands are used, since these
elements concentrate their effect on the most adjacent pre-
form surface.
For illustrative purposes, two blow pins 200 and 202 are
shown, these blow pins being similar to those of Figures 1-6
in the sense of having a cylindrical shaft portion 204 sur-
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mounting a dome-shaped nose portion 206 for insertion within
a parison and pre-form. In this embodiment, however, the
blow pin carrier plate 208 includes a circular opening 209
within which a cylindrical, rotatable shaft 210 is maintained.
A circular supporting plate 212 is secured to the top of the
shaft 210 and rests upon the top surface of the blow pin car-
rier plate 208. Blow pin shaft 204 is threadedly secured to
the bottom portion of shaft 210, with an annular collar 214
fitting on member 204 in close proximity to the lower surface
of blow pin carrier plate 208. Thus, the blow pin assembly,
including components 204,206,210,212, and 214, are rotatable
with respect to the blow pin carrier plates.
The mechanism for rotating the blow pins includes a sup-
port ledge 214 having a pair of shafts 216 and 218 rotatably
maintained within respective circular openings, one such open-
ing being indicated by reference numeral 220 in Figure 8. Each
rotatable shaft has a respective driven wheel 222,224 secured
to the top thereof, and an annular cap 226,228 threadedly
secured to the bottom thereof. Each annular cap secures an
expansible member 230, 232 in position for engaging and impart-
ing rotary motion to the respective circular support plates
of the blow pin arrangement.
A rotary drive motor is suitable mounted on ledge 214 and
has an output shaft 236 connected to a drive wheel 238. A
drive belt 240 fits over drive wheel 238 and imparts rotary
motion to driven wheels 222 and 224.
The support ledge 214 also includes a longitudinal bore
242 which is in communication with an air supply line 244 that
is connected to the ledge 214 by a threaded coupling 246.
Secondary transverse bores 248 extend from the longitudinal
bore 242 and communicate with an annular groove 250 in each
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peripheral surface of rotary shafts 216 and 218. A transverse
bore 252 extends radially from the annular groove 250 to com-
municate with an axial, longitudinal bore 254, thus establish-
ing communication between supply line 244 and a collapsible
chamber 256 defined between the lower surface of the rotatable
shafts 216, 218 and the expansible members 230 and 232.
As illustrated in Figures 7 and 8, air under pressure is
being supplied from line 244 to the inflatable, resilient
members 230 and 232. Simultaneously, rotary drive motor 234
is imparting rotary motion to rotatable shafts 216 and 218.
With the inflatable, resilient pads 230 and 232 being in engage-
ment with the circular supporting plates 212, the blown pre-
forms are rotated about their longitudinal axes while suspen-
ded from the blow pins.
Just prior to the blow pin carrier plates being indexed
to the next position in operational sequence, a negative pres-
sure may be pulled by line 244, thus collapsing the expansible
members 230 and 232. When blow pin 202 is indexed to the pre-
vious position of blow pin 200, a positive pressure is re-
supplied by line 244, thus expanding pad 230 into contact with
the circular support plate of blow pin 202 to continue the pre-
form spinning operation.
Turning now to Figures 9-17, a second overall embodiment
is illustrated for thermally conditioning pendently supported
pre-forms to a temperature conducive to substantial molecular
orientation. As illustrated in Figure 9, this embodiment
includes an extruder 300, a pre-form mold 310, a thermal con-
ditioning chamber 312, a moveable blow pin conveyor system 314,
a final mold assembly 316, and a conveyor system 318. The
extruder 300 is conventionally designed and includes a down-
wardly directed annular orifice structure 302. The thermal
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conditioning chamber 312 may include heating means, coolingmeans, or combinations thereof as more fully discussed in
relationship to thermal conditioning chamber 102 of Figure 1.
The moveable blow pin conveyor system may be comprised of con-
ventional chain links, to which separate moveable blow pins
are connected.
As illustrated in Figures 9,10 and 11, the pre-form blow
mold assembly 310 includes a pair of blow mold sections 320
and 322 which are moveable transversely toward and away from
one another along tie rods 324 and 326 by piston rods 328 and
330 of hydraulic cylinders 332 and 334. When closed, the blow
mold halves 320 and 322 define apre-form mold cavity 336 and a neck
or finished region 338. A piston rod 340 of hydraulic cylinder
342 is connected to tie rod 326 for moving the pre-form mold
assembly 310 from the pre~form molding position shown in
Figure 10 to a position beneath extruder 300.
A neck bracket assembly 344 is also connected to the pre-
form mold 310 for transporting a blown pre-form from the pre-
~orm molding station for placement on a moveable blow pin.
The neck bracket assembly includes bracket arms 346 and 348
slideably connected to respective blow mold halves 320 and 322,
the bracket arms having semi-circular recesses 350 and 352 for
gripping the neck portion of a blown pre-form. The bracket
arms are maintained in suitable guideways, (not shown) and
are raised and lowered by respective piston rods 352 of hydraul-
ic cylinders 354.
As illustrated in Figure 10, a freshly extruded tubular
parison 304 depends from extruder nozzle 302, a tubular
parison 306 is enclosed within mold cavity 336 in preparation
for the pre-form blowing operation, and a just-blown pre-form
308 is supported by the neck bracket assembly 344 for place-
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ment on a terminal nose portion 361 of a moveable blow pinassembly 362. Further, a vertically reciprocal blow nozzle
356 has been inserted into the open end of the mold-enclosed
parison 306 by a hydraulic cylinder 358.
With the molding assembly positioned as shown in Figure
10, blow air under pressure is supplied through a longitudinal
; bore 360 in blow nozzle 356 for expanding the mold-enclosed
parison 305 to a pre-form configuration. Subtantially
simultaneously, hydraulic cylinders 354 are actuated to extend
piston rods 352 to raise bracket arms 346 and 348 for inserting
the neck portion of pre-form 308 onto the blow pin nose 361,
as illustrated in Figure 11.
Next, hydraulic cylinders 332 and 334 are actuated to
open the mold halves 320 and 322, thus leaving the fresly
blown pre-form suspended on blow nozzle 356 and pre-form 308
suspended on blow pin assembly 362. Then, hydraulic cylinder
342 retracts piston rod 340 to position mold halves 320 and
322 on each side of parison 304 and neck bracket arms on each
side of the freshly blown pre-form on blow nozzle 356.
Hydraulic cylinders 332 and 334 are then actuated to close the
pre-form mold halves on parison 304, pinching the bottom por-
tion of the tubular parison shut. At the same time, neck
support bracket arms 346 moved together, with semi-circular
surfaces 350 and 352 closing upon the neck portion of the
previously blown pre-form. While the pre-form mold assembly
is in this position, the moveable blow pin conveyor system 314
is indexed to advance the blow pins. Then hydraulic cylinder
358 raises blow nozzle 356, hydraulic cylinders 354 lower the
neck bracket assembly, and hydraulic cylinder 342 extends
piston rod 340 to position the pre-form mold assembly as shown
in Figure 10.
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Figure 12 simply shows moveable blow pin assemblies 364
and 366 with pendently suspended pre-forms 368 and 370 in
thermal conditioning chamber 312. As previously discussed,
the temperature of the suspended pre-forms is adjusted in the
thermal conditioning chamber 312 to within the range most con-
ducive to substantial thermal orientation during the final
blowing operation.
; As shown in Figures 13-15, the final blow mold assembly
316 includes mold halves 372 and 374 which are transversely
moveable toward and away from each other by piston rods 376
and 378 of fixed hydraulic cylinders 380 and 382. When
closed, the mold halves 372 and 374 define a final blow mold-
ing cavity 384 and a finish or neck region 385. It should be
noted from Figure 14 that the pre-form is contacted by the
final blow mold halves substantially only at the neck portion
prior to the final blowing, thus maintaining the blown pre-
form body substantially at the optimum orientation temperature.
The moveable blow pin assemblies of this embodiment in-
clude a carrier frame 386 which has a central bore 388. A
cylindrical blow pin, or carrier, 390 is maintained within the
central bore 388, with a nose portion of the blow pin 390 ex-
tending below the carrier frame 386 for insertion within the
neck of a blown preform. The carrier frame 386 includes a
transverse bore 392 within which a biasing spring 394 is main-
tained by a threaded plug 396, the spring urging a retention
ball 398 into an annular groove 400 of blow pin 390. This
arrangement releaseably maintains the blow pin 390 in the
carrier frame assembly 386 to enable quick ejection of the
blow pins or blow pin substitution.
A hydraulic cylinder 404 is positioned above the final
blow mold assembly 316 and includes a vertically moveable
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blow nozzle 406. Figure 13 illustrates the pendently sup-
ported pre-form in position prior to closure of the blow mold
halves, with blow nozzle 406 in alignment with the central
bore 402 of blow pin 390. Figure 14 illustrates that blow
nozzle 406 may be advanced completely through the blow pin
390 to axially stretch the pre-form to establish an axial
orientation of the thermoplastic material. After the stretch-
ing operation, air under pressure is injected through the blow
pin or carrier 390 into the stretched pre-form by supplying
air through an axial bore 408 in the blow nozzle to radial
ports 410 for expanding the pre-form to the configuration
shown in Figure 15, thus bi-axially orienting the molecular
structure of the thermoplastic material.
After the blowing operation hydraulic cylinders 380 and
382 are actuated to retract blow mold halves 372 and 374,
leaving the blown article pendently suspended from the termin-
al nose portion of blow pin 390. The moveable blow pin con-
veyor system then indexes the moveable blow pin to a position
as illustrated in Figure 17 above a conveyor 318 where the
blown article can be ejected in any suitable manner.
The foregoing disclosure, therefore, relates to two
primary embodiments for utilizing moveable blow pins for con-
tinuously forming molecularly oriented thermoplastic contain-
ers. It is to be understood that many facets of the invention
which were discussed in regard to one embodiment could be
employed equally as well with the other embodiment. For
example, the rotation means of Figures 7 and 8 may easily be
adapted for use with the moveable blow pin conveyor system
illustrated in the embodiment of Figure 9. Further, the pre-
form stretching mechanism disclosed in Figures 13-15 may like-
wise be used in conjunction with the final blow mold assembly
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shown in Figure 5.
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