Note: Descriptions are shown in the official language in which they were submitted.
:1~29~t3
V-260
i
BACKGR~UND OF THE INVENTION
This invention relates to the art of blow molding from a
parison of articles of organic plastic material suscept~ble to
the improvement of their properti~s by orientation and has for
its principal objects the provislon of an apparatus which is
characterized by a more rapid operating cycle with less effect
upon the temperature of the parison, carrying out the steps of
parison production, stretch orien~ation and circumferential
orientation in a single uninterrupted, yet completely controlled
sequence, and the provision of improved, oriented hollow
articles.
The art teaches various methods and apparatus for obtaining
blow molded articles of organic plastic material from a
parison, such as in U.S. Patent 3,349,155 and Re~ 27,104.
i Generally, these methods are characterized by forming a parison
in a parison mold on a blow core, placing said formed parison
and blow core into a blow mold and expanding said parison in
the blow mold by means of fluid pressure.
~ hile the blow molding operation tends to i~.part
) orientation to the article, such orientation is predominantly
circumferential, i.e., not bi-axial. Also, the degree of
such orientation is difficult to control. It is therefore
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~ 1 2 9~1 ~ Y~260
di~ficult to obtain the ad~antageous properties in the article
that bi-axial orientation is capa~le of proyiding,
It is known th~t the control o~ ~r~entatlon de~ends la~gel~
upçn the control of the temperature of the parison ~ust prlor
to orlentation. ~t ls found that such te~perature control is
best obtained by enclosing the article prior to the orienting
step in heating ~eans that impart temperatures, preferably by
contact ~ith the corresponding surfaces of the parison, to the
regions of the parison correspondlng to the degree o~
de~ormation that is lntended for such regions.
Ho~ever, art devices that o~tain the desirable hi-a~lal
orientation are often cumbersome and slo~ and incon~enient to
operate. Also, production rates with such devices are ~ar
~rom optimum.
SUMMARY OF THE INYENTION
In accordance ~ith the present invention~ an apparatus is
provided for khe prep~rat~on o~ hollow articles ~aintainlng
su~stantially consistent temperature control of the articles
prior to orientation and/or prior to final expansion, ~hile
also ohtaining an i~pro~ed, conrolled inJectlon ~low ~oldin~
or st~etc~ ~low molding sequence ~th a rapid operating cycle
w~ich ~as less effect upon the temperature o~ the parison.
The apparatus of the present invention also obtains numerous
other significant ad~antages which will he-more readily
apparent ~rom the ensuing specification.
The apparatus o~ the present in~ention co~prises; a
reciprocahle first core, preferahly ~ially reclprocable~
and a temperature controlled ~irst mold, preferably laterally
reciproca~le; ~eans ~or providing a parison on said ~irst core;
means includlng said ~irst core to place said parison in said
2 9~1 3 ~-260
~lrst mold; means for separating said parison fr~m ~aid first
core while retaining said parison in said first mold to ad~ust
the temperature thereof; a second csre and a second mold in
spaced relationship to said ~irst core and first ~old,
respectively, preferably in lateral spaced relationship,
wherein said second core is reciprocable, pre~erably a~ially
and laterally reciprocable, and wherein said second mold is
stationary; means for transferring said parison to said second
core and second mold; and means to expand said parison on sald
second core in said second mold to provide a finished article.
Preferably, the apparatus includes an article removal
plug for removing the ~inished article in integral, spaced
relationship to said second core, preferably in lateral spaced
relationship, so that when the second core engages the parison
in the first mold, the removal plug engages the finished
article in the second mold.
In accordance with the apparatus of the present invention,
the parison walls may be caused to est;ablish intimate surface
contact with the walls o~ the first moldg such as by forcing
said parison ln the first mold to conf`orm to the shape of the
first mold~ such as by expansion, The parison shape may be
chosen so as to permit the insertion there1n of the second core
into intimate surface contact with the inside of the parison.
The parison is therefore in full surface contact wlth the first
mold for adjust~ent o~ the temperature ~f t~e parison~ an~
possibly also in full surface contact with the second core~
The temperatures o~ the first mold, of-the second core, or of
both~ may be controlled to provide optimum conditions in the
parlson for orientation thereof.
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1129613 Y~260
Alternatively, the parison may be stripped ~rom the first
core into the first ~old without substantially deforming the
parlson~ in whlch case the shape Or the ~irst ~old is
substantially the same as that of the parison to insure.adequate
surface contact between the two. At times, the parison may be
placed within a heated cavity that does not correspond to the
shape of the parison, such heated cavity taking the place of
the ~irst mold. This heated cavity is the equivalent of the
first mold in the present conte~t and it will be included
within the term "first mold" throughout the present
specification.
In view o~ the plural cores and molds used in the present
invention and the high degree of temperature control which can
be e~er.cised over the parison, the present invention readily
obtains a multi-axially oriented art'Lcle by axially stretching
the temperature adjusted parison at a predetermined rate in
the second mold by means of the second core and by e~panding
the parison to form the ~inished art-Lcle. ~urthermore, the
~ovement parameters of the components of the present apparatu~
prov~de a highly efficient and smooth operation.
If it is desired to produce a multi-layered parison.and a
multi-layered ~inal article, the first core may be provided
with-a layer o~ one plastic and a subsequent layer may then be
pressure ~olded therearound in accordance with.my U.S. Patent
Nos. 3,349,155~ 3,717~544 and 3,719,735, It should be
understood, therefore, that where the general description that
follows refers simply to parisons, the method and apparatus o~
the present invention are applicable to ~ulti-layered as
well as sin~le-layered par~sons.
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112g613
Y_260
Thus, a multl-axially oriented article may be readily
obtained in accordance with the apparatus o~ the present
inyention by-providlng means ~or axially stretching the
temperature ad~usted parison at a predetermined rate and by the
e~pansion of the same, such as by an axially reciprocable
portion of the second core that is actuated by means capable of
ad~usting the speed of reciprocation.
It can be seen that the apparatus of the present in~ention
ef~iciently and conveniently obtains uniform temperature control
0 of the parison so that the resultant article is characterized by
highly improved properties~ while obtaining a high production
rate. It is known that orientation substantially improves the
significant properties of plastics, as clarity, impact
resistance, strength, resistance~to permeation, etc. Among
the plastics that can be so improved are polystyrene,
polyYinyl chloride, polyolefins, as polyethylene and
polypropylene, polyesters, polycarbonate 8, polyamides~ acrylics,
fluorocarbon resins, acrylonitrile, and ~etbacrylonitrile
polymers. The improved temperature control of the present
~0 invenkion enables one to obtain improved properties and
controlled multi-a~ial orientation in a simple and e~peditious
manner.
Accordingly, it is a principal object of the present
invention to provide an apparatus for the preparation of hollow
articles from moldable organic plastic material which enables
accurate temperature control and a rapid and e~peditious
operating cycle.
It is a ~urther ob~ect of the present in~ention to
eonveniently and expeditiously provide improved artlcles whlch
are multi-axlally oriented under condltions of close contrvl
9 6 1 3
of temperature and deformation rate.
It is a still further object of the present inven-
tion to provide an apparatus as aforesaid which provides
products possessing reproducibly uniform properties due to
orien-tation.
In accordance with a particular em~odiment of the
invention, there is provided an apparatus for forming objects
of moldable organic plastic material which comprises: a
reciprocable first core and a temperature controlled first
mold, means for providing a parison on said first core,
means .including said first core to place said parison in
said first mold, means associated with said first core for
separating said parison from said first core while retaining
said parison in said first mold to adjust the temperature
thereof; a second core and a second mold in spaced-relationship
to said first core and first mold, respectively, wherein
said second core is reciprocable into and out of engagement
with said second mold and wherein said second mold is
stationaryi means for trans~erring said parison to said
second core and second mold; and means to expand said
parison on said second core in said second mold to provide
a finished article.
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1~9~13
Other objects and advantages of the present
invention will be apparent to those skilled in the art from
the description which follows with reference to the accompany-
ing drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an elevation, partly in section, illus-
trating the apparatus of the present invention,
Figure lA shows a core modification in the apparatus
of Figure 1.
Figures 2 and 3 are views similar to Figure 1 with
additional portions in phantom showing a sequence of operations
according to an embodiment of the present invention.
Figure 4 is a partial vle,w similar to Figures 1-3
showing a modification of the apparatus of the present
invention,
Figure 5 is a schematic elevation similar to Figure 1
showing a plurality of cores and molds.
Figures 5A and 5B are schematic top views o~ the
second cores showing a variation of the embodiment of Figure 5,
Figure 6 is a schematic view showing a plurality
of first cores in a variation of the apparatus of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in more detail,
Figures 1, 2 and 3 illustrate an apparatus in accordance
with one embodiment of the present invention, In this
embodiment, the parison is provided by an injection
molding process' however, the invention is not limited
thereto and includes other known molding processes that
are capable of producing parisons such
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.,
11~9~13 V~26Q
as compression moldingg castlng9 extrusion with or without
secondary operation, and the like. Fig~re 1 depicts a parison
die 1~ having ou~er walls 11 whlch may be separable, depending
upon the shape of the pari~on and whlch are adapted to form the
- outer surface of the parison9 and havlng an end wall 12 shaped
to form the end wall of the parlson. The par~son die 10 may be
temperature controlled, such as by heating or cooling elements
lOa contained therein which are connected to appropriate heat
- transfer sources (not shown) whereby such temperature control
may be arranged in se~eral zones to obtain different
temperatures in different regions of the parison The end
wall 12 of the parison die has an injection opening 13
registering w-l~t~ an injection n~zzle 14 through ~hich the
organic plastic material is inJected into the parison die.
The parison die 10 is shown as split for.con~enience in opening
to release the ~ormed parison; however, it should be understood
that the in~ention is not limited th~ereto, as one piece dies
suitably designed for release o~ the parison are encompas~ed
herein.
As indicated hereinabove, the plastic~.conte~plated in
accordance wlth the present invention are the molda~le organic
plastic materials and preferably those whose properties are
impro~ed by orientation, such as the pol~o1e~ns-J polyethylene,
polypropylene and copolymers thereof, polyvinyl chloride,
polystyrene and other s.ty~en~c resins, acrylonltrile,
methacrylvnitrile, poly~inylidene chloride, polycarbonates,
polyesters, polyamides~ fluorocarbon resins, etc.
The formation of the parison in accordance with the
embodiment il-lustrated in Figures 1, 2 and 3 ~akes place a~ter
a ~irst core 15 ~preferably a blow core) illustrated in
11~9613 Y-260
Figure 1, and set ~orth in phantom in ~lgures 2~3, and die 10
are brought into engagement by suitable mechanical ~eans such
as the motive means shown schematically in ~igure l. In the
embodiment shown in Figures 1, 2 and 3, core 15 is axlally
reciprocable in.the.direction of the arrow into and o~t of
engage~ent with die 10. Upon completion of inJection through
nozzle 14, a parison 16g having substantlally the config~ration
represented in ~igure 2, is formed.
Side wall 17 and an end 18 of core 15, walls 11 and 12 of
parison die 10, and the neck mol.d 20 constitute a die cavity
in which the parison is for~ed. Core 15 may ~e temperature
controlled in one or more zones, such as by internal heat
exchange clrcuits known in the art contained therein, which are
connected to an appropriate heat tranæfer or power source
(not shown). Core 15 is carried by platen 19. This assem~ly
further includes a neck mold 20 in which the neck of the parison
is formed and ~hich remains en~aged with the parison while the
latter remains on blow core 15 after disengagement from the
parison die, ~hich neck mold ~ay be independently temperature
controlled. The neck mold may possess threads 21 ~or definlng
a threaded opening in the final molded o~ect. The neck mold 20
may be split and opened lnto two portions by suitable mechanical
means such as the motive means shown schematically in ~igure 1,
to release the parison, or, if the configuration o~ the neck
permits, may be of one piece construction and, thus, separable
from the parlson as a unit.
During separation of the parison die 10 and the core 15,
the parison 1~ is sufficiently retained thereon by means Or
neck-mold 20, or by other means, such as an undercut, 1~
necessary. Upon separation, the parison assumes the position
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Y 260
ll~g~
deplcted in Figure 1 and shown in ph~ntom ln ~igu~e 3,
First mold 2?, which is a conditloning, i.e., te~pering
mold and may be a pre-forming mold, and core 15 are ~rought into
align~ent so as to ~u~tapose ~irst mold 22 and parison 16,
lllustrated, as noted earlier in phan~ in Flg~re 3. As
sho~n, ~irst mold 22 is laterally reciprocable by suita~le
mechan~cal means, such as the motive means shown sch~atically
in Figure 1, with the flrst mold moving in the direction of the
arrow into and out of alignment with core 15. ~old 22 iS .
temperature controlled, frequently in multiple zones which may
be dlsposed along the length thereor, as by heating or cooling
e.le~ents 22a which are connected to appropriate heat transfer
sources (not shown). It is possi~le, although not preferred,
to align first mold 22 and parison 16 by lateral or circular
reciprocation of core 15.
Referring to Figure 3, upon the alignment of first mold 22
and ~core 15 bearing parison 16, core 15 and parison 16 are then
placed wlthin first ~old 22, ~or exa~ple, by the axial
reGiprocation of core 15. Other ~eans of engaging parisons
and molds may be used and are .~ell known, such as t~ose '.
disclosed:.in U.S. Patent Nos. 2,853~736 and 2,974~362. The
parison is then released from first core 15 into first ~old 22~
as by stripping it a~ially which may be facilitated, if desired,
by partially expanding the par~son. The partial expansion is
carried out by arranging for the mold cavity of mold 22 to be
a small frackion of an inch larger than the parison and ~y
applying fluid pressure thrsugh channel 27 on the inside of
the parison thereby e~panding the parison into conformance with
the cav~ty ~f mold 22. Passage 27 is provided withln core 15
~0 and may terminate at a valve-like, closeable portion Or the
;
_g_
11~36 ~ 3 Y~2~Q
core well known in the art. Separation of the parison from
core 15 may then be facilitated by air-pressure stripping o~
the parison from the core,-with remsval of the core ir~m the
parison leaving the parison in mold 22. It should be noted that
such expans1on is not always necessary, but is often helpful
as in the e~ample shown. If des~re~, an exit channel (not
shown~ may be provided on ~old 22 to permit the remoYal of air
from the mold cavity as the parison enters facilitating the
esta~lishment of contact of the parison with the mold walls
The temperature of first mold 22 is controlled by heating
or cooling means 22a connected to appropriate heat trans~er
sources (not shown)~ or by electric heaters, to opt~mize the
parison temperature for subsequent operations in a manner to be
described below. Naturally any suitable heatln~ or cooling
means may be used in any of the heating or cooling coils
described herein, such as a passage containing heat transfer
fluld maintained at a suitable temperature, electric -resistance
heaters or radiant heat sources.
Fi~ure 3 illustrates the pressure ~olded parison 16 as
conformed to the shape of the mold ca~ity in firs~ mold 22, for
e~ample, by the exertion of fluid pressure, with the partially
expanded parison labeled 29. At tl~es the shape o~ partially
expanded parison 29 may be made such that a second core, e.g.,
stretch-blow core 30, may bè inserted lnto substantially
complete surface contact therein, as shown in ~igure 2,
permitting heat exchange throughout, by contact o~ the second
core and the parison. In such an instance, the said shape should
exhibit no undercuts or reverse curves on the inside surfaceg
fDr e~ample, due to an outward taper oYer its inside surface.
Ho~ever, the parison shape does not always permit this, for
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~2bo
1~29613
. example, in some cases of long, narrow-necked parisons, in which
cases lt may be necessary to forego contact heating the inside
of the parisons
After c~mpletion of the transfer of the pari~on lnto
first mold 22 9 that mold and ~irst~core 15 are separated ~ by
moving the first core plu5 flrst neck mold axially in the
direction of the arrow, usually accompanied by the application
of air pressure at the inside o~ the parison by ~eans of the
first core, and the parison 29 thus transferred is retained in
0 first ~old 22. Core 15 and neck mold 20 are then returned to
the starting posltion as illustrated in ~igure-l, and first
~old.22 containing the pari~on 29 which may be partially
e~panded, is shifted laterally into the position illustrated in
Figures 1 and 2.
Parlson 29, which is retained within first ~old 22, is
thereby trans~erred into alignment with a second core 30 which
is carried by platen 31 and which ma~ be proYided w~th
.temperature cont~ol means, and which may ha~e an e~ternal
con~ig~ration shaped to conform to the internal con~iguration
of the parison 2~. WheneYer axial stretching of the parison is
desired, core 30 will include a stretch and ~lo~ assembly
which comprises a mandrel extension 32 which is reciprocable
as-~ndicated by the arro~.in Figure.l to axially e~tend t~e
parlson 29. An actuating means i3 shown which co~prises a
push rod 34 which engages extension 32, and which is connected
to a.piston 35 housed within a cylinder 36.which may, for
example, be responsiYe to hydraulic pressure e~erted by a
pump, not shown. B~ controlling the ~low of fluid lnto
cylinder 36, the speed of piston 35 and therefore of the
moYable portion of core 30 may be controlled to stretch the
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11~9613
parison at the speed best suiked for the ke~perature of the
pari~n. Such actuating ~eans i5 merely illustrati~e o~ one
manner of operation, as other actuating means known in the art
can be employed herein. If a highly oriented article is not
desired, the a~ial extension operation may be dispensed with.
For the final forming sequence, the parison is separated
from first mold 22 by retaining it at the neck reglon on core 30
and, at times, also on.a neck mold 37 ~hich operates in the s~me !
manner as neck ~old 20. In the absence of neck mold 37, one may
o retain parison 29 on core 30 by close fit of core 30 within the i
neck of the parison, or, as shown in Flgure lA~ by pro~idlng an .
expandable sleeve 30a made of an elastomer or the like at the
neck region o~ core 30 arranged to grip the neck of the parison
internally, ~hereby such a sleeYe may ~e oaused to e~pand by air
pressure brought to it from the core, as through fluid
passageway 38.
Core 30 i5 situated in spaced relationship to core 15,
and ~irst mold 22 is situated in spaced relationship to second
mold 23, to enable both cores to engage a respectiye ~old when
core 15 is aligned with mold 22 a~ shown in Figure 3, This
facil~t~tes the concurrent pursuit of hoth the temperi~ and
final forming processes with separate parisonsO Further, and
with regard to the trans~er of parison 29 to core 30, it should
be noted that par~son die 10 is spaced rrom first mola 22, as ,
illustrated in ~igures 1 and 2, so that core 15 may engage with
die 10 to form another parison while core ~0 engages with first
mold 22 and also while a th~rd core 41 e~ects the fully
expanded article 40. The ability to concurrently conduct the
Yario-~s-operations o~ the process outlined herein comprises one
of .the nota~le advanta~es o~ the invention. The s~multane~us
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Y~260
112961~ `
formatlon3 transfer, or final expanslon and finished article
removal o~ a plurality o~ parts is en~isioned, as the apparatus
illustrated ln the accompanylng figures can be further modified
to provide additional intermediate molds and cores 9 such as
mold 22 and core 30.
A fluid passageway 38 is provided and terminates at the
end surface of that portion of the core 30 which does not moYe
during the movement of extenslon 32. Fluid passagewày 38 also
connects to a source of fluid under pressure, not shown.
Accordingly, fluid ~ay enter the space inside parison 2~ during
final expansion, discussed hereinafter, once passageway 38 is
opened by movement of the extension 32 and correspond~ngly of
the mo~able portion of core 30. If the transfer of the parlson
out of first mold 22 is to be facilitlated by gripping the
parison from the inside as shown in Figure lA, elastic
sleeve 3~ais pressurized from its inside surface ~y means of
pressure air through secondary passageway 38a causing the sleeve
to expand against the inner half of the parison neck.
In the instance ~here core 30 may be made to conform to
the inner contour of parison 29, it can be seen that core 30 may
be heated or cooled. Thus, the ~emperature of parison 29 may
be ad~usted by heat exchange between both the inner and outer
surfaces of parison 29 and the corresponding mold and -core
surfacesO
The parison 29 s thereby rapidly and uniformly prepared
for further processing, such as axial e~tension and f~nal
e~pan~ion. This is a considerable advantage since it avoids
the problem of parison cooling during a multi~step process.
Whenever core 30 may be made to conform to the shape of
parison 29, the heat trans~er conditions may ~e further improyed
` 11~9~13
over the ones prevailin~ if only the outer surface of parison
Z9 is in heat transfer relation with a corresponding mold
element. Naturally, the conventional temperature regulators
that are used to control the heating means of core 30 and
mold 22 are able to do so individually, in several zones within
the assembly, corresponding to the desired temperature profile.
In the interest of a rapid operating cycle, it is
particularly advantageous to first rapidly alter the heat con-
tent of parison 16 by heat exchange with core 15 and mold 10
to result in a heat content desired for subsequent operations,
but almost always at the cost of an unequal distribution of
temperature in said parison. This must be followed by sub-
stantially equalizing the temperature distribution across the
wall thickness of said parison by heat exchange with mold 22
and, whenever made to conform with the inner wall of the
parison, with core 30, to avoid a layer-wise pattern of
properties in the finished article corresponding to the known
relationship between such properties and the deformation
temperatures. This procedure is described in more detail
in my U. S. Patent 4,116,606. ~hus, for example, one
can form parison 16 by injection molding, rapidly cool ;`
said parison by heat exchange with core 15 and mold 10
which will result in a rapid cycle, but will also produce
said unequal temperature distribution, ~ollowed by substan-
tially equalizing the cross-sectional temperature distribu-
tion of said parison, all in a controlled manner, to impose
thereon the temperature profile desired for orientation.
Naturally, the parison rem~ins in mold 22 until the necessary
desired temperature distribution adjustment is obtained.
Alternatively, in accordance with the present invention, a
-7 `~ ~ - 14 -
11296:13 ~; 26n
pre-formed parison may be placed in mold 10, heated rapldly ln
~old 10 by heat e~change-~ith mold 10 and core 15, whlch is
al~o apt to produce said ~nequal temperature distribution~ and
further treated in-~old 22 by heat e~change ~ith ~old 22 and
core 30 to substant~ally equalize the temperature dlstrl~ution
of said parison. The foregoing provides the considerable
advantages of enabling the attainment of a predetermined
temperature profile Or the parlson resulting in optimu~
conditions for orientation without excessiYe dwell time in the
molds. The parlson mold is freed for ~urther use ~hile the
~irst mold is completing the conditioning o~ the parison,
resulting in an expeditious processing cycle.
Referring to Figure 2, the transfer of parison 29 to
finishing mold 23 is conducted by core 30 whlch is in
engagement with ~lrst mold 22 and parison 29. Core 30 ~ith
parison 29 thereon is separated from flrst mold 22,- ~hich ~ay
be split to release parison 29, by moYing core 30 a~ially by
suitable mechanical means such as the motive means shown
schematically in ~igure-l. Upon release, core 30 ~Ith parison
29 thereon returns to the posi~-lon lll~strated in Figure 1 and
depicted in phantom in Figure 3.
In accordance with the apparatus of the present lnvention,
the second mold 2-3 is ln lateral spaced relationship to said
first mold 22, with the second mold being fi~ed. The ~i~ed or
stationary position of the second mold represents a significant
ad~antage o~ the apparatus of the present invention, It per~it~
the placement of the parison much more rapidly and hence with
less er~ect upon its temperature~ Also, second mold 233 if it
is a multi--impression mold (which is o~ten the case) ls apt to
weigh several tons~ The movement Or such a mass ~ith great
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1 1 ~ g~ Y_260
speed requires elaborate, expensive and not altogether
efficaclou~ means to control acceleration and deceleration of
the ~vement; ~hereas9 the parison with the core assembly
weighs but a ~ew pounds and may be mo~ed swiftly by s~mple
means~ e.g., cushioned-end air cyllnders.
As can be seen in Figures 1 and 2, a third core or article
removal plug 41 for removing the finished article is ln integral,
lateral spaced relationshlp to second core 30, ~ith both the
second and thlrd cores being carried on platen 31. Therefore,
L0 when the second core engages parison 29 in second mold 22, the
removal plug 41 engages the finished art~cle 40 in the second
mold 23. As shown by the arrows, the second and third cores are
ax1ally and laterally reclprocable so that the ~econd core
transfers parison 29 from mold 22 to mold 23 ~y a combination
of axial, lateral and axial movements. Simultaneously, third
core 41 removes the finished article from mold 23, which may
be split and separable to facilitate the extraction Or the
~inis~ed article, and transfers same to an e~ection station
~ located laierally of mold 23 (not shown) ~or remoYal of the
~inished article while core-30 engages mold 2~.
Core 30 carrying parison 29 is then recelYed in ~old 23;
with the te~perature of parison 29 having been ad~usted as
described above. Parison 29 is usually axially extended to the
bottom of mold 23 by the advancement o~ the movable portion of s
mandrel 32 by ~eans of push rod 34 at a predetermined rate.
Thus, the present invention ~ay controllably stretch the parison
longitudinally be~ore final blowing and thereby produce
orientation in the axial direction as well as the orientation
subsequently produced by blowing. It can be seen that the
temperature of the parison preparatory to stretching and blowing
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~129613 ~_260
may be properly and con~eniently controlled by the respect~Ye
molds and core. -W~ile stretching occurs, pa~sageway 38 is
kept open to pro~lde pressure equalization Or the inside of the
parlson with the atmosphere to pre~ent collapse of ~he parison
due to the vacuum created inslde It as its inside volume
increases during stretching.
- After completion of axial ~xtenslon~ the parison-is fully
e~panded to conform to the configuration o~ ~inishing, i.e,,
second mold 23, to form the flnal:ob~ect ~O:which9 in the
embod~ment illustrated herein,-is an open-ended container.
Naturally, a wide variety of shapes may be prepared as the
commercially known shapes which ~ay be a bottle, a ~ar or a
cup-shape. Full expansion is accomplished by supplying fluid
under pressure through passageway 38 into the interlor of
a~ially extended parison 29, or at times and at ~arious rates,
into the interior of the parison ~h'Lle it ls being e~tended.
After full expansion is c~mpleted, second core 30 and
second mold 23 containing final ob~ect 40 are separated as
descri~ed Elereina~ove with reference to first core 15 and
first mold 22. The second core is moved axially, laterally and
~ axially, ~hlch positions the second core in the ~irst mold 22
- and at the same time positlons removal core 41 in finished
article 40 for removal-of same after the ~inished article has
cooled-sufficiently for that purpose.
- In the embodiment illustrated herein, finlshing ~old 23 is
longitudinally split into two sections la~eled 42 and 43, whlch
may reclprocate in and out o~ communication by an actuating
meansj not shown, such as ror ~xample a hydraulic cylinder.
~hus, sections 4? and 43 ma~--be parted an amount -suffic~ent to
permit ~he rem~val of article 4~ ~y core 41 w~ic~ may be inserted
1~29613 Y-26a
into the neck thereo~ with a tight flt. Prior to such opening
of mold 23 and removal, fluid pressure may he applied through
passageway 46 to continue the blowing process, i~ desired3 in
cases requiring continued contact of article 4~ with second
mold 23 for the purpose of extended coollng. Alternatively,
passageway 46 may ~e utilized to continue to supply cooling air
to the 1nside Or the finished art~cle, or to apply suction to -
the inside of the finished article to aid in retaining same
thereon.
Thus, it can be seen that the present invention improves
the in~ection ~low molding process and carries out the steps of
parison production, stretch orientation and circumferential
orientation in a single unlnterrupted and co~pletely controlled
sequence. The parison is in~ected or provided in a first
station and is moved axially from the first station on a first
core. The parison is then transferred by the first core into
a first or tempering mold which i9 9hifted laterally into
alignment with the flrst core for that purpose. The first mold
is then shi~ted laterally ~ith the parison thereIn into a
second station wherein a second core is inserted into the
parison and the second core with parison thereon is ~oved
axially away from the first mold. The second core with
parison thereon is then shifted into alignment wlth the second
mold and inserted therein for final processing inko a finished
article, with the finlshed article being e~ected by a third
or e~ection core.
The apparatus and process of the present invention is
simple, convenient and progressive in nature. The parison moves
fr~m the--~n~ection ~old-to first-core; from ~irst core to
tempering mold; from tempering mold to a second core which may
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112 9 6 .L 3
be a stretch-blow core; fr~m second core to finishing mold and
out; or prefera~ly from flnlshing mold to a third eJection core
and out. The ~aYement of components is quite s~mple and
convenlent and e~peditious, with the large, ~u~ky ~lnish~ing
mold being stationary.
The temperature ad~ustment of the parison afrorded by the
present invention has been found to provide an oriented product
ha~ing consistently good properties. The parison is in~ected
into a comparatively cool mold and le~t there ~or a ~ery short
time, long enough to remo~e the amount o~ heat from the parison
that corresponds to the condition ~est su~ted ~or orientation.
The parison is then trans~erred into a tempering ~old ~hich
imparts the opt~mum orientation temperature distribution to the
given plastic artlcle, staying in that mold long enough to
equalize the temperature across the ~all thickness o~ the
parison whlch naturally arrives from the In~ection mold with a
poor cross-sectional temperature prof'~le. After tempering, the
parison, now having the right temperature pro~ile with good
cross-sectional d~stri~ution, is transferred into a cool
~20 ~in~shing mold in which it is stretched at a-controlled rate and
~lown. The steps of in~ection plU5 dwell in the in~ectlon mold;
o~ tempering and o~ stretch-blo~ing with cooling overlap; and
of article remoYal, occ~r at the same tl~e allowing ~or
ef~lcient macbine utillzation. Also, the component ~ovements
allow ~or smooth operation.
Naturall~, many ~ariations ~ay ~e ~ncluded, In~ected or
blown necks may ~e ~ade. The stretch ~nction ~ay ~e ~mitted,
ln which ca~e a Yery e~r~cient in~ection blo~ ~old~ng operation
is provlded. Instead o~ tempering, the second station ~ay he
~sed as a ~irst hlo~ station and the thlrd station m~y ~e used
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11~9613 Y~260
as a second blow statlon in order to dl~de the cooling d~ell
bet~een-the t~o. This may be deslra~le in the case of thick-
walled articles~ In fact, additional cooling stat~ons may
~e added.
In one modification, the-parison ~ay be-~ormed earller at
a time and location of its own and stored ~efore ~e~ng for~ed
into the flnal artlcle. In addition to in~ection mold~ng,
numerous methods are known that may be employed to provide
thermoplastics in the shape o~ a parison~ such as tube
e~trusion with welding of one open end, dipping, deposition,
thermoforming and the like. Thus, the previously formed parison
may be transported to and placed upon a first blow core which
cooperates with a heating means to raise the te~perature of the
parison suf~iciently to enable it to undergo de~ormation.
Secondary operations often need to be per~ormed upon the
hollo~ article made in accordance wlth the present invention.
Among these is the application of a base cup to the articles
ha~ing a domed bottom as is frequently the case ~lth ~ottles
that haYe t~ withstand appreciable internal pressure, e,g.,
car~onated beverage bottles. These ~ase cups are ~sually
plastic dish-like o~Jects ~ith a ~lat bottom, the-inside o~
the dish often bein~ glued to the conve~ ~otto~ of the bottle
so as to render it capable of standing upon a ~iat sur~ace,
These ~ase cups are usually applied in a special deYice to which
~ottles that haYe been previously made are rand~ly presented.
In accordance with the improvement illustrated by the
modificatlon of ~lgure 4, it is posslble to dispense ~ith suc~
a separate de~ice and lnstead to integrate the ba~e cup
applicator-lnto the apparatus itself. In accordance with the
em~odi~ent oY ~i~ure 41 a ba~e cup applicator i5 proYided for
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1 1 2 g~ 26n
applying a ~ase cup to the hase o~ the finished article~ wlth
the applicator being located ln lateral spaced relatlons~ip to
the ~econd mold so that ~hen the second core and parison engage
the second mold CFigure 3) the appllcator carrylng a ~ase cup
engages the base of the finished article on the removal plug.
As shown ~n Figure 4, base cup applicator 50 ls carried ~y
a suitable platen 51 ~hich may be movable in the directlon of
the arrow by suita~le ~otive means. The applicator includes a
sleeYe portion 52 and a bottom base cup carrier 53. In
operation, carrier 53 is loaded ~ith a base eup 54 by
conventional means, not shown. The ~ase cups ~ay ~e proYided
wlth adhesive 55 at predetermlnedg spaced locatlons for adhering
to the bottom of the finished article. The base cups carried by
applicator 50 are then engaged with the base o~ the finished
article 40 with sleeve 52 surroundin~ the finished article to
keep same ~rom ~uckling outwards. Air pressure may ~e supplied
inside the ~insihed article by passageway 46 in coxe 41.
Pressure is then applied-to carrier 53 ln the direction of the
arro~ pressing c~p 54 firmly agalnst the base of the bottle 40.
Upon c~pletion o~ the requisite setting times for the
adhesive 55, if used, the applicator is removed frQm the
~inlshed article 40 now equipped with a base cup 54, and the
article is stripped from the plug 41.
It is well known that in in~ection molding it is desira~le
to minimize the length over which molten plastic is ~ade to
~low and also to group individual cavlties ln in~ection multi_
cavity ~olds so as to minim~ze the platen space which helps
accuracy in moldin~ due to the reduced hazard of deflectln~ the
support structure-of--the mold under-the great forces of
in~ection. As shown in the schematic diagrams of ~ig~res 5,
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~1~961 3 Y.26n
.
5A and 5B which utiliæe an apparat~s according to F~g~res 1,
2 and 3, an apparatus is provided includlng a pl~rallty of first
cores in spaced relatlonshlp to each other carried by a c~mon
carrying ~eans~ a plurality of first-molds ln spaced
relationship to each other carr~ed ~y a c~m~on carrying means, a
plurality of second cores in spaced relationship to each other
carried by a common carrying means, and a plurality of second
molds in spaced relationship to each other carried by a com~on
carrying means, wherein a plurality of the fin~shed articles
I are made simultaneou~ly. Naturally, the molds may be spllt for
convenience of article or parison remoYal. As shD~n in
Figure 5, the cavities 111 in multiple parison mold 110 are
arranged in a row cooperating with ~irst cores carried on
common carrying means or support plate 119. The parison die 110
cooperates with in~ectlon unit 114 through wh~ch ~olten plastlc
is injected through channel 113 dist;ributed by runner 113a.
The spacin~ between cavities 111 corresponds to the d~mensions
of the parisons. Accordingly, the spacing of the second cores
130 carried ~y common carrying ~ean~ or platen 131 must
o correspond to t~at of the cavities 111 if the parisons made in
cavitles 111 are to ~e transferred in the manner shown in
Figures 1, 2 and 3. The parisons are then transferred thro~gh
the processing cycle in a manner after Figures 1, 2 and 3
- utilizing a plurality of first molds 122 and a plurality of
second molds 123.
Hollow art~cles to be made ~r~m parisons are frequently
much larger than the parisons and hence cannot be accommodated
with the s~me center spaclng as the parisons. F~r example,
the parison for a large bottle may have a diameter of
approximately 1-1~2 inches~ while the bottle ~de ~r~m the
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~129~.3 ~-260 -j
parison ~ay ~easure 4 inches ln d~eter. In accordance w~th the
e~bod~ent of ~igures 5A and 5B, whlch represents a schematic
top ~ew of the second cores-in two di~erent positlons, means
are provlded ~or ~o~ing said second cores aw~y ~r~m and towards
each other in a predetermined relationship. The apparatus
accordlng to ~igures 5A and 5B acc~modates the larger center
spacing of the finished article ~hile preserving the c~mpact
arrangement ~n the parison ~old as in ~igure ~. Two ro~s 131'
and 131" of second cores 130' are pro~ided to mate with two
o correspond~ng rows or-parisons (not shown~. ~eans are provlded
to spread the two rows-o~ second cores, such as spreader bars 150
connected to any suita~le motive means, in the direction of the I
arrows. Thus, once the parisons carried by second cores 130'
complete the tempering cycle in the first molds Cthe position
æhown in ~igure 5A~ and the parisons-are separated there~rom~
khe spreader bars 150 are ~oved to spread the second cores 130'
to the center lines of the ~lnishing ca~tie~ of the second
~olds. ~to the po~Ition shown in ~igure 5B~, A~te~ stretching ¦
- and ~lo~ing in the second molds, the second cores are remo~ed
~o fro~ the hollow art~cles and ~oved toget-her aga~n to the
center lines-of the ~lrst ~olds to resume the ne t c~cle. ¦
~igure 6-shows a ~rther impro~ement aimed at handl~ng
parisons ~ade o~ plastics that require a prolonged t~mpering .
cycle pr~or to bi~axial orientation ~y stretching and blo~ing.
A~ong these plastics,.polyprop~lene being the ~ost prominent,
I tempering cycles in terms of ~inutes are called for, ln
contrast to t~mpering cycles measured in seconds that are .
needed in connection with other materials. The pxoblem in
connect~on ~ith an apparatus ~or th~s type o~ ~aterlal is to
IQ introduce an extended tempering cycle without at the ~e t~me
. -23-
11~9613 Y~260
prolonging the actual operating cycle o~ the de~lce and ~ithout
constructlng extremely bulky and ine~icient heating-apparatus.
Figure 6 seh~atieally- show~ an apparatus ~hich acco~plishes
the~oregOing ~y including a plurallty ~f ~irst ~olds ~oYahle
~nto positions spaced ~rom the cores ~o~ Extended ad~ustment
of the t~perature of the parison, In the em~odiment s~own ln
Figure 6, a multi-tier arrange~ent is pro~lded ~n the te~pering -
station show~ng a plurallty of ~rst ~olds 222, In operatlon
accord~ng to ~igures 1, 2 and 3, when a mold 222 ~lth the
par~son reaches the tempering station it is side~hifted hy
conventional motive means to neighboring position A. In a
ne~t cycle, lt may ~e further slde-shlfted into an ad~oining
posl~i~n A', and so on, whereby the nu~ber o~ such side
positions will depend upon the actual tempering c~cle desired~
As ~llustrated in Fig~re 6, upon reach~ng position A', the
tempering mold is moved to a lo~er tier, i.e., into pos~tion Bt',
~rom whence it is moved ~urther into posit~on B', and ~r~
there to posltion B, ~rom ~hich pos~tion tt is elevated into
the original upper tier, i.e., into the ~osition at which
~old 222 had or~inally entered the tempering cycle, Positions
A~ A', etc. and B, ~', etc. may of course be arranged at either
s~de, or ~oth sides o~ the temperlng station. It can ~e readily
seen that by means of this simple side-shift and eleYator
dev~ce, the parisons may ~e given any e~tended te~pering des~red
without impeding the overall operat~ng cycle of the ~aehine.
Thus, the ~ach~ne output ~-11 remain the sa~e regardless of the
tempering dwell provided that a sufficient num~er o~ tempering
~olds are used. -Naturally, all ~ol~s in circulation ~ay ~e
c~nne¢ted to a source ~f energy9 for example, in the case o~
electrlc heatlng, electric power may reach each mold over a
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~ Y~260 - . ~
1129~13
slld~ng connector .cooperating ~lth suitable conventional bus
bars,
In accordance ~ith the embodiment of Figure 6~ the.parisons
arri~ing ln the.~lrst o~ tempering mold are not remo~ed
therefrom by the second cores, but prior thereto, the first
~old is side-s~ifted to giYe an e~tended tempering cycle ~hile
keep~ng.the parisons under controlled temperature conditions.
The length of time for this d~ell will depend ~pon the number
of molds that are in circulation. The remo~al o~ the temperPd
par~son may occ~r at positlon B.
Instead of the preferred device for using a multipllcity
o~ tempering molds as aboYe described, it is conceiva~le to
move a ~ultipllcity of first molds along different paths, for
example, in a circle, which may be ~e-rtical or horizontal~
However, care must be taken to keep t:he parisons in a vertical
pos~tlon to a~oid their di.stortion and to keep the molds in
contact with temperature control unlts~ .
In summary, in accordance with the embodiment of Figure 6,
an apparatus is provided for form~ng obJects of moldable
2~ plastlc material requiring prolonged temperin~ cycles to obtain
conditlons suitable for.orientation, said apparatus lncluding
a multiplicity Or temper~ng molds for retaining parisons prior
to .orientation, whereby the tempering molds recei~e an~ release .
the parisons seriatim and whereby the o~erall cycle of the
apparatus is substantially unaf~ected by the number of the
tempering molds. Preferably, the apparatus is of the type
shown in Figures 1~ 2 and 3. .
As indicated hereinabove, in connection with the discussion ¦
of Figure 4, secondary operations can if desired be per~or~ed
3o at the eJe~tor station. One illustration of these secondary
,
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~. -
1 ~2 g~ 1 3 Y~260
operatlons ls the attachment o~ a ba~e cup 54 to the finishedarticle 40 by means of a base cup applicator 50, Naturally,
other ~econdary operations may readily be performed at the
e~ector station as sho~n in my pre~lous ~.S. Patents 3j336,425
and 3~587,133, ~or e~ample, one ~ay flll the ~inished article
while-said article ls confined by means oi the base cup
applicator 50 or other suitable means to confine the walls of
the finished artIcle ~hile said article is betng ~llled.. This
procedure ~ill ena~le one to readily hot ~ill the finished
1~ article and, if desired, maintain the fllled article confined
until cooled suf~iciently to handle~
This invention may be em~odied in other forms or carried
out in other ways without depart~ng ~r~ the splrit or
essential characteristlcs thereor. The present em~odiment is
therefore to be con~idered as in all respects illustrattve
and not restrictiYe, the scope of the lnvention being Indicated
by the appended clai~s, and all changes which come ~lthln the
meanin~ and range o~ equiYalency are.intended to ~e em~raced
therein.
3Q
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