U.S. patent number RE41,572 [Application Number 12/099,024] was granted by the patent office on 2010-08-24 for blow molding device for producing thermoplastic containers.
This patent grant is currently assigned to Sidel. Invention is credited to Dominique Briere, Leon Coisy, Paul La Barre, Pascal Santais.
United States Patent |
RE41,572 |
Briere , et al. |
August 24, 2010 |
Blow molding device for producing thermoplastic containers
Abstract
The invention concerns a device for producing thermoplastic
containers, in particular bottles, by the blow-molding or stretch
blow-molding of a preheated preform. The device comprises at least
one mould consisting of two half-molds (2) each supported by a
mould carrier, the two mould carriers being movable relative to
each other. Each half-mould (2) comprises a shell holder (9),
supported by the respective mould carrier, and a shell (7) which is
equipped with a half-impression (8) of the container to be obtained
and can be rendered integral in a detachable manner with its shell
holder (9) by rapid-fastening means (19-23). The shell (7) and the
shell holder (9) are of complementary shapes such that they contact
each other at least partially for heat conduction purposes whilst
the pipes and connections for circulating and/or heating fluids are
provided in the shell holder alone.
Inventors: |
Briere; Dominique (Le Havre,
FR), Coisy; Leon (Saint Martin du Manoir,
FR), La Barre; Paul (Sainte Adresse, FR),
Santais; Pascal (Sainte Adresse, FR) |
Assignee: |
Sidel (Le Havre Cedex,
FR)
|
Family
ID: |
9478234 |
Appl.
No.: |
12/099,024 |
Filed: |
July 9, 2001 |
PCT
Filed: |
July 09, 2001 |
PCT No.: |
PCT/FR96/00576 |
371(c)(1),(2),(4) Date: |
October 17, 1997 |
PCT
Pub. No.: |
WO96/33059 |
PCT
Pub. Date: |
October 24, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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09553413 |
Apr 20, 2000 |
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Reissue of: |
08945089 |
Oct 17, 1997 |
05968560 |
Oct 19, 1999 |
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Foreign Application Priority Data
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Apr 19, 1995 [FR] |
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95 04651 |
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Current U.S.
Class: |
425/195; 249/102;
425/526; 425/541; 249/79; 425/522; 425/405.1 |
Current CPC
Class: |
B29C
33/305 (20130101); B29C 49/48 (20130101); B29C
49/4823 (20130101); B29C 2049/4856 (20130101); B29C
33/26 (20130101); B29C 2049/4892 (20130101); B29K
2067/00 (20130101); B29C 49/08 (20130101); B29C
2049/4864 (20130101) |
Current International
Class: |
B29C
49/48 (20060101) |
Field of
Search: |
;425/192R,195,522,526,541,405.1 ;249/79,80,81,102 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1916129 |
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Oct 1969 |
|
DE |
|
2307727 |
|
Aug 1973 |
|
DE |
|
2545130 |
|
Apr 1977 |
|
DE |
|
2545131 |
|
Apr 1977 |
|
DE |
|
2545132 |
|
Apr 1977 |
|
DE |
|
2545134 |
|
Apr 1977 |
|
DE |
|
3613543 |
|
Dec 1986 |
|
DE |
|
3934495 |
|
Dec 1990 |
|
DE |
|
2057196 |
|
May 1971 |
|
FR |
|
2613979 |
|
Oct 1988 |
|
FR |
|
2646802 |
|
Nov 1990 |
|
FR |
|
2653058 |
|
Apr 1991 |
|
FR |
|
2659265 |
|
Sep 1991 |
|
FR |
|
1230090 |
|
Apr 1971 |
|
GB |
|
1425638 |
|
Feb 1976 |
|
GB |
|
1577034 |
|
Oct 1980 |
|
GB |
|
2240300 |
|
Jul 1991 |
|
GB |
|
58-36418 |
|
Mar 1983 |
|
JP |
|
60-011316 |
|
Jan 1985 |
|
JP |
|
63-227315 |
|
Sep 1988 |
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JP |
|
HEI 1-60725 |
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Apr 1989 |
|
JP |
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2-82436 |
|
Jun 1990 |
|
JP |
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5-169522 |
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Jul 1993 |
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JP |
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WO 94/03320 |
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Feb 1994 |
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WO |
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Other References
"Quick-Change Systems Add to Blow Molders' Market Reach", by
Patrick A. Toenmeier, Modern Plastics International, Aug. 1991 (pp.
30-31). cited by other .
Patent Abstracts of Japan, vol. 12, No. 286 (M-727), Aug. 5, 1988
(Abstract of Japanese Reference 63-062,710, dated Mar. 19, 1988).
cited by other.
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Primary Examiner: Davis; Robert B
Attorney, Agent or Firm: Alston & Bird, LLP
Parent Case Text
.Iadd.CROSS-REFERENCE TO RELATED APPLICATIONS.Iaddend.
.Iadd.This application is a continuation of U.S. application Ser.
No. 09/553,413, filed Apr. 4, 2000 which was a Reissue Application
filed for U.S. Pat. No. 5,968,560, application Ser. No. 08/945,089
filed Oct. 17, 1997, which was the National Phase Entry of PCT
application PCT/FR/00576, filed Apr. 16, 1996. The 09/553,413 and
08/945,089 applications are hereby incorporated herein in their
entirety by reference..Iaddend.
Claims
We claim:
.[.1. Device for manufacturing containers, made of a thermoplastic
by blow molding or stretch-blow molding of a preheated preform, the
said device including at least one mold (1) consisting of two
half-molds (2) respectively supported by two mold carriers (3)
which are made in the form of enveloping structures and which can
move one with respect to the other, characterized in that each
half-mold (2) comprises a shell holder (9) supported by the
respective mold carrier (3) and a shell (7) which is provided with
a half-impression (8) of the container to be obtained and which can
be removably fastened to its shell holder (9) by quick-fixing means
(19-23), the shell (7) and the shell holder (9) being in
complementary shapes in order to be in at least partial mutual
thermal-conduction contact while the pipes and connections for the
circulation of cooling and/or heating fluids (11, 12) are provided
exclusively in the shell holder..].
.[.2. Device according to claim 1, characterized in that the mating
faces (14, 15) of the shell (7) and of the shell holder (9) are in
total thermal-conduction contact..].
.[.3. Device according to claim 1, characterized in that the mating
faces (14, 15) of the shell (7) and of the shell holder (9) are in
partial thermal-conduction contact by leaving regions of limited
thermal conduction..].
.[.4. Device according to claim 1, characterized in that the
mutually contacting mating faces (14, 15) of the shell (7) and of
the shell holder (9) are approximately semicylindrical surfaces of
revolution with an axis approximately parallel to the axis of the
impression (8) of the container to be manufactured..].
.[.5. Device according to claim 1, characterized in that the
mutually contacting mating faces (14, 15) of the shell and of the
shell holder are provided with axial mutual-positioning means (16,
17)..].
.[.6. Device according to claim 5, characterized in that the axial
mutual-positioning means comprise a system of one or more mating
ribs (16) and grooves (17) extending circumferentially..].
.[.7. Device according to claim 1, characterized in that the means
(19-23) for quickly fixing the shell (7) to the shell holder (9)
are provided on their respective parting faces (13, 18)..].
.[.8. Device according to claim 4, characterized in that the means
(19-23) for quickly fixing the shell and the shell holder are
located on their respective edges parallel to the axis of the
impression..].
.[.9. Device according to claim 8, characterized in that the
quick-fixing means (19-23) comprise, on one side, at least one stop
for positioning the parting face of the shell with respect to the
parting face of the shell holder and, on the other side,
quick-screwing means (23) on the parting face (18) of the shell
holder (9) with a clamping surface (21) projecting from the parting
face (19) of the shell..].
.[.10. Device according to claim 9, in which the mold carriers are
rotationally pivoted with respect to each other whereby at least
one stop is located on the pivot (4) side of the mold carriers (3)
and the quick-screwing means are located on the opposite
side..].
.[.11. Device according to claim 1, characterized in that the shell
holder (9) is also provided with members (24) for guiding the
half-molds in order to close the mold..].
.[.12. Device according to claim 1, characterized in that at least
one of the shell holders is equipped with pressure-compensating
means suitable for maintaining the sealed closure of the mold
during blow molding..].
.[.13. Device according to claim 1, characterized in that the shell
holders (9) are equipped with a number of fluid pipes, by virtue of
which it is possible to create suitable circuits for a given
manufacture with a given impression..].
.[.14. Device according to claim 1, wherein said containers are
bottles..].
.Iadd.15. A mold assembly for use in manufacturing molded
thermoplastic containers comprising: two mold shells each
containing a half-impression of a substantial portion of the
container to be molded; two mold shell holders each defining a
cavity for receiving each said respective mold shell such that each
said respective mold shell is in at least partial mutual
thermal-conduction contact with its respective shell holder, said
shell holders being shaped to be supported by two mold carriers
made in the form of enveloping structures movable one with respect
to the other; and at least two axial positioning assemblies by
which said mold shells are fixed in an axial direction with respect
to said mold shell holders..Iaddend.
.Iadd.16. The mold assembly of claim 15, wherein each of said at
least two axial positioning assemblies comprises at least one
meshing male coupling member disposed on at least one of said mold
shells and mold shell holders, and at least one complementary
meshing female coupling member disposed on at least one of said
mold shells and mold shell holders..Iaddend.
.Iadd.17. The mold assembly of claim 15, wherein said mold shell
holders further comprise a number of internal fluid pipes and
connections for the circulation of cooling and/or heating
fluids..Iaddend.
.Iadd.18. The mold assembly of claim 15, wherein at least one of
said mold shells and/or mold shell holders define at least one
cavity at the interface between said mold shells and mold shell
holders into which pressurized fluid suitable for maintaining the
sealed closures of the mold assembly may be interposed during the
molding process..Iaddend.
.Iadd.19. The mold assembly of claim 16, wherein said meshing male
and female coupling members further comprise a system of one or
more mating ribs and grooves in said mold shells and mold shell
holders..Iaddend.
.Iadd.20. An article for use in manufacturing molded thermoplastic
containers comprising: a mold shell containing an impression of a
substantial portion of a container; and at least two coupling
members by which said mold shell can be fixed in an axial direction
with respect to a mold shell holder, said shell holder defining a
cavity for receiving said mold shell such that said mold shell is
in at least partial mutual thermal-conduction contact with said
shell holder, said shell holder being shaped to be supported by one
of a pair of mold carriers made in the form of enveloping
structures movable one with respect to the other..Iaddend.
.Iadd.21. The article of claim 20, wherein said impression further
comprises a neck portion, a sidewall portion, and a base
portion..Iaddend.
.Iadd.22. The article of claim 20, wherein each of said at least
two coupling members further comprises either a groove or a rib
disposed about the exterior surface of said mold
shell..Iaddend.
.Iadd.23. The article of claim 22, wherein said groove or rib is
proximate a neck portion of said mold shell..Iaddend.
.Iadd.24. The article of claim 20, further comprising: a parting
face adjacent a generally mating face of said shell holder; and at
least one clamping surface projecting from said parting
face..Iaddend.
.Iadd.25. A mold shell holder assembly for use in manufacturing
molded thermoplastic containers comprising: two mold shell holders
each defining a cavity shaped to receive a mold shell in at least
partial mutual thermal-conduction respective contact; said shell
holders being shaped to be supported by two mold carriers made in
the form of enveloping structures movable one with respect to the
other; and at least one quick-fixing locking member positioned on
each of said mold shell holders, said quick-fixing locking member
being configured to be engaged by a respective one of said mold
shells for removably securing said one mold shell to a respective
one of said mold shell holders, said quick-fixing locking member
including a selectively retractable locking member
portion..Iaddend.
.Iadd.26. The mold shell holder assembly of claim 25, further
comprising: at least two axial positioning assemblies positioned
along each of said shell holders by which said shell holder may be
fixed in an axial direction with respect to a respective one of
said mold shells..Iaddend.
.Iadd.27. A mold shell holder assembly for use in manufacturing
molded thermoplastic containers comprising: two mold shell holders
each defining a cavity shaped to receive a mold shell in at least
partial mutual thermal-conduction respective contact; said shell
holders being shaped to be supported by two mold carriers made in
the form of enveloping structures movable one with respect to the
other; and at least two axial positioning assemblies positioned
along each of said shell holders by which said shell holder may be
fixed in an axial direction with respect to a respective one of
said mold shells..Iaddend.
Description
The present invention relates to improvements made to devices
making it possible to manufacture containers, in particular
bottles, made of a thermoplastic by blow molding or stretch-blow
molding of a preheated preform, the said device including at least
one mold consisting of two half-molds respectively supported by two
mold carriers which can move one with respect to the other.
It is common practice for the half-molds to be removably fixed to
the respective mold carriers so that the said half-molds can be
replaced or changed should they become damaged and/or worn and,
above all, should containers of different shapes and/or sizes be
manufactured, without it being necessary to replace the entire
molding device.
However, such an arrangement is still far from being to the
complete satisfaction of users. This is because each half-mold is
heavy (for example about 25 to 30 kg for a steel mold): the fixing
means must be able to support this weight and comprise many
nut-and-bolt and/or screw connections; furthermore, each half-mold
must be handled by several people and/or by means of a hoist,
thereby requiring a suitable installation above the manufacturing
device. Each half-mold is equipped with means for the circulation
of one or more fluids for the cooling and/or heating of the walls
of the impression: replacing each half-mold is accompanied by
disconnecting, followed by reconnecting, of the corresponding fluid
connections, all operations requiring time.
It is also necessary to add an economic consideration regarding the
actual construction of each half-mold. The impression serving for
pressure molding the final container must have a perfectly polished
surface finish, to which, furthermore, the hot thermoplastic must
not adhere: it is therefore necessary for the impression to be made
of a suitable metallic material (for example stainless steel)
which, moreover, may differ depending on the thermoplastic
employed. Given the monobloc structure of the half-mold, it is
therefore the totality of each half-mold which must be made of this
suitable metallic material, this being a special and therefore
expensive material, while the rear part of the half-molds merely
fulfills a mechanical strength function, giving the mold rigidity
and non-deformability, for which rear part a more ordinary, and
therefore less expensive, material could be perfectly suitable.
The object of the invention is therefore essentially to remedy, as
far as is possible, the drawbacks of the currently known
manufacturing devices and to provide an improved device which
allows quick and simple changing of the molding impressions in
order to make it easier to adapt the device to the manufacture of
various containers, and the improved structure of which device is,
at the end of the day, less expensive than that of the current
devices while still maintaining the same strength and
non-deformability properties.
To these ends, a device for manufacturing thermoplastic containers,
as mentioned in the preamble, is essentially characterized, being
designed in accordance with the invention, in that each half-mold
comprises a shell holder supported by the respective mold carrier
and a shell which is provided with a half-impression of the
container to be obtained and which can be removably fastened to its
shell holder by quick-fixing means, the shell and the shell holder
being of complementary shapes in order to be in at least partial
mutual contact, with thermal conduction, while the pipes and
connections for the circulation of cooling and/or heating fluids,
and optionally the members for guiding the half-molds in order to
close the mold, as well as the pressure-compensating means for
maintaining the sealed closure of the mold during blow molding, are
provided exclusively in the shell holder.
By virtue of this arrangement, the part of the half-mold
corresponding to the impression, which may be economically made of
a suitable and relatively expensive material, and the rear part of
the half-mold, which provides rigidity and mechanical strength and
which may be made of a more ordinary and less expensive material
(for example a standard aluminum alloy), are separated from each
other. In addition, being less heavy, this rear part has less
inertia, thereby contributing to facilitating the rotational
movements of the half-molds. In addition, and above all, changing
the impression in order to manufacture containers of various shapes
merely requires changing the shell, which is of a much lower weight
(for example about 10 kg) compared to the complete half-mold and
which can therefore be handled manually: the handling installation
(which, however, remains necessary in order to handle other
components, and in particular the shell holders, of the device)
may, however, be simplified and, above all, the procedure for
replacing the shells is speeded up. This procedure is, furthermore,
made even more rapid as there are no longer the fluid fittings to
be disconnected, and then reconnected, these remaining permanently
connected to the shell holders.
It is also possible to standardize the shell holders which are,
from the outset, equipped with a number of fluid pipes from among
which those useful for a given manufacture with a given impression
may be selected. Thus, it is possible to create independent
circuits making it possible to produce, in each shell holder and
therefore in the shell, regions with differentiated temperature
settings. Here again, this results in the possibility of reducing
the manufacturing cost of the shell holders, which accompanies
their standardized production in larger number.
Preferably, the mutually contacting mating faces of the shell and
of the shell holder are approximately semicylindrical surfaces of
revolution with an axis approximately parallel to the axis of the
impression of the container to be manufactured; it is thus easier
to produce mutually-contacting mating faces which ensure heat
transfer as close as possible to that of a monobloc structure,
something which may furthermore be obtained by providing for the
shell and the shell holder to be in total thermal-conduction
contact. However, it should be noted here that the arrangement
according to the invention also provides the possibility of
ensuring, when this proves to be desirable, that the shell and the
shell holder are in partial thermal-conduction contact by leaving
regions of limited thermal conduction, which also constitutes
another means of creating, in the wall of the impression, regions
with differentiated temperature settings.
It is desirable, in order to allow quick, and therefore easy,
assembly of the shell on the shell holder, while still having
precise relative positioning of the shells one with respect to the
other, for the mutually-contacting mating faces, with thermal
conduction, of the shell and of the shell holder to be provided
with axial mutual-positioning means; preferably, the said axial
mutual-positioning means comprise a system of one or more mating
ribs and grooves extending circumferentially, which arrangement, in
combination with the aforementioned semicylindrical configuration
of the said mating faces of the Shell and of the shell holder,
allows very simple assembly, with very precise positioning of the
shell, using simplified fixing means.
Thus, advantageously, the means for quickly fixing the shell to the
shell holder are provided on their respective parting faces. In the
case of semicylindrical mating faces, the said fixing means are
located on the respective edges of the shell and of the half-shell,
these being parallel to the axis of the impression; it is then
desirable for the quick-fixing means to comprise, on one side, at
least one stop for positioning the parting face of the shell with
respect to the parting face of the shell holder and, on the other
side, quick-screwing means on the parting face of the shell holder
with a clamping surface projecting from the parting face of the
shell, by virtue of which the shell is put into place on and locked
onto the shell holder by curvilinear sliding of the shell, guided
by the rib(s)/groove(s) system, in the cradle formed by the shell
holder. In particular, if the mold carriers are rotationally
pivoted with respect to each other, in order to form a
"jackknife"-type mold, provision is made, in order to simplify
connection and disconnection, for the above-mentioned stop to be
located on the pivot side of the mold carriers and the
quick-screwing means to be located on the opposite side.
In order to be more specific, it may be pointed out that, in a
typical molding device designed in accordance with the invention,
the time to replace a pair of shells is about 8 minutes while the
time to replace a pair of half-shells in a prior device is about 20
minutes, using appropriate handling equipment.
The invention will be more clearly understood on reading the
detailed description which follows of a preferred embodiment given
solely by way of illustrative example. In this description,
reference is made to the appended drawings in which:
FIG. 1 is a diagrammatic view from above of part of a molding
device designed in accordance with the invention;
FIG. 2 is a front view of a two-piece half-mold of the device in
FIG. 1; and
FIG. 3 is a view from below of a half-mold in FIG. 2.
FIG. 4 is a view from left, partially cutaway, of the device of
FIG. 1.
Referring first of all to FIG. 1, this shows part of a device for
manufacturing containers, in particular bottles, made of a
thermoplastic such as polyethylene terephthalate PET, polyethylene
apththalate PEN or another material, as well as alloys or blends
thereof, by blow molding or stretch-blow molding a preheated
preform.
This device includes at least one mold 1 consisting of two
half-molds 2 respectively supported by two mold carriers 3 which
can move one with respect to the other. In the example shown, the
two mold carriers 3 are made in the form of two enveloping
structures pivotally mounted on a common rotation axis 4 in such a
way that the two half-molds can move apart by pivoting (a socalled
"jackknife" structure). The mold carriers may be driven, in order
to open and close the mold, in a conventional manner using a system
of traction arms pivoted at 5 to the respective mold carriers a
certain distance from the axis 4 of the latter.
Locking means, denoted in their entirety by 6, lock the two
half-molds in the closed, molding position.
In accordance with the invention, each half-mold is made in the
form of two subassemblies, namely a shell 7 provided with a
half-impression 8 of the container to be manufactured and a shell
holder 9 which supports the shell 7 and which is itself fastened to
the corresponding mold carrier 2.
Each shell holder 9 may be considered as corresponding externally,
in shape and size, to the mold carrier of the previous structures
and it may therefore be fastened to the respective mold carrier 3
in the same manner, for example by a nut-and-bolt connection 10, it
being possible for the number and disposition of the holes and
internal threads to be identical to those of the previous
arrangements.
As may be seen in FIG. 3, each shell holder is provided with
internal pipes 11 and with fittings 12 which are necessary for the
circulation of at least one fluid for cooling or heating the wall
of the impression. Any number of these pipes and fittings may be
provided and they may, for example, be independent of each other so
as subsequently to allow them complete freedom, by externally
connecting them appropriately, to constitute circuits of various
and/or independent configurations depending on the type of
containers to be produced and the type of material employed. Thus,
it is possible to standardize to some extent the manufacture of the
shell holders 9 and to reduce the manufacturing cost thereof.
Because of the fact that the impression 8 is physically separated
from the shell holder 9, it is possible to make the latter from a
less special material, for example an ordinary aluminum alloy, even
when the shell is made of steel, thereby making it possible, here
too, to reduce its cost; in addition, the shell holder 9 thus
produced is lighter than a steel shell holder, which desirably
decreases its inertia and has a favorable effect on the dynamic
operation of the mold.
Each shell 7 has a half-impression 8 of the final container,
hollowed out in its parting face 13. The external face 14 of each
shell 7 has the general shape of a semicylinder of revolution, the
axis of which is approximately parallel to the axis of the
impression 8 of the container; in practice, the impression is
coaxial with the semicylinder. The shell 7 rests in a cradle 15 of
complementary shape cut out in the shell holder 9. The shapes of
the shell and shell holder are perfectly matched and they are thus
in as close a contact as possible. Provision may thus be made for
the mating faces 14 and 15 of the shell 7 and of the shell holder 9
to be in complete thermal-conduction contact so that heat transfer
from one to the other is as good as possible and approaches as far
as possible that of a monobloc half-mold.
However, it is also conceivable for the said mating faces 14 and 15
to be only partially in thermal-conduction contact, with provision
of regions of limited thermal conduction; it is thus possible to
produce differentiated temperature settings in the wall of the
impression. In order for the impression 8 to have the required
polished finish and for the hot thermoplastic not to adhere to its
surface, the shells are made from a suitable material, for example
stainless steel. In order for the shapes of the mating parts of the
shell holder 9 and the shell 7 to remain perfectly matched, it is
necessary to choose materials exhibiting thermal expansion
coefficients which are substantially identical.
In the example shown in FIG. 2, the container to be produced has a
bottom of complex shape (petaloid bottom) and the requirements for
demolding the container after it has been formed result in the
provision of a separate mold bottom 25, distinct from the
half-molds 2, which includes the impression of the bottom of the
container. It will be noted here that FIG. 3 is a view from below
of the half-mold in FIG. 2, the mold bottom 25 not being shown.
The axial mutual positioning of the shell holder 9 and of the shell
7 is achieved by a rib(s)/groove(s) set of mating elements which
fit together, one in the other. As shown in FIG. 2, the shell 7 is
provided with two grooves 17, hollowed out circumferentially in its
external face 14 axially separated from each other; likewise, the
cradle-shaped face 15 of the shell holder 9 has two ribs 16 which
fit together without any clearance in the two respective grooves
17. Once the shell 7 has been placed in the shell holder 9, it can
no longer move axially with respect to the latter but can only
slide rotationally about its axis on the cradle 15.
In order fully to lock the shell onto the shell holder,
quick-fixing means are provided in the parting face 13 of the shell
and in the parting face 18 of the shell holder. For this purpose,
respective housings 19 and 20, hollowed out in the facing edges of
the afore-mentioned parting faces 13 and 18, respectively, are
provided. The bottoms of the housings 19 of the shell 7 constitute
flat bearing surfaces on which may bear members for locking the
shell holder 9. These locking members may be formed in many ways
known to those skilled in the art. In the example shown in FIG. 2,
these are projecting lugs 21 drilled with an elongate hole 22 and
retained by a screw 23 fixed to the bottom of the corresponding
housing 20 of the parting face 18 of the shell holder 9; this
arrangement has the advantage that the shell is released as soon as
the lugs 21 are unlocked and pushed back toward the outside,
without it being necessary to remove the screws 23 completely.
Notwithstanding this, the shell could also be locked onto the shell
holder by using wide-head screws overlapping the flats of the
housings 19, or else by using quick-face eccentric-head screws,
etc.
It will be noted that in practice the two locking members 21
located on the side adjacent to the axis of rotation 4, in the case
of a jackknife mold, do not have to be actuated and may thus
constitute simple stops (with the possibility of adjusting the
position of these stops) under which the flats of the respective
housings 19 are brought when the shell is inserted into the shell
holder, by causing the shell to slide rotationally in the latter.
Moreover, given the position of these two locking members 21
located in the bottom of the open mold, their access is difficult
and their removal would unnecessarily lengthen the process of
replacing the shell 7.
As for the rest, each shell holder 9 is designed in the same way as
a previous half-mold, which includes the elements necessary for
correct operation of the molding device, and in particular the
means 10 for fixing it to the corresponding mold carrier 3, the
guiding fingers 24 (and the respective housings in the other shell
holder) for closing the mold, the rear face provided with a chamber
26 and with an O-ring seal 27 for compensation as shown in FIG. 4.
It is therefore possible, in a preexisting installation, to replace
the conventional monobloc half-molds with two-element half-molds
according to the invention.
Needless to say, and as results already from the foregoing, the
invention is in no way limited to those of its methods of
application and of its embodiments which have been more
particularly envisaged; on the contrary, it embraces all variants
thereof.
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