U.S. patent application number 13/080230 was filed with the patent office on 2011-07-28 for apparatuses for forming objects with undercut portions.
This patent application is currently assigned to SACMI COOPERATIVA MECCANICI IMOLA SOCIETA'COOPERATIVA. Invention is credited to Alessandro BALBONI, Maurizio Borgatti, Zeno Zuffa.
Application Number | 20110180967 13/080230 |
Document ID | / |
Family ID | 37156013 |
Filed Date | 2011-07-28 |
United States Patent
Application |
20110180967 |
Kind Code |
A1 |
BALBONI; Alessandro ; et
al. |
July 28, 2011 |
APPARATUSES FOR FORMING OBJECTS WITH UNDERCUT PORTIONS
Abstract
An apparatus for forming an object from a dose of plastics
comprises a die arrangement provided with a cavity for receiving
said dose and with at least two parts that are reciprocally movable
for shaping an undercut portion of said object, at least one fluid
for applying a clamping force so as to keep said at least two parts
in contact; said at least one fluid is such as to increase
discontinuously said clamping force from an initial force that is
applicable when said dose is substantially contained in said cavity
to a final force applicable when said at least two parts shape said
undercut portion.
Inventors: |
BALBONI; Alessandro;
(Granarolo dell'Emilia (BO), IT) ; Borgatti;
Maurizio; (Imola (BO), IT) ; Zuffa; Zeno;
(Borgo Tossignano (BO), IT) |
Assignee: |
SACMI COOPERATIVA MECCANICI IMOLA
SOCIETA'COOPERATIVA
Imola (BO)
IT
|
Family ID: |
37156013 |
Appl. No.: |
13/080230 |
Filed: |
April 5, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11990308 |
May 14, 2008 |
7939005 |
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PCT/EP2006/064921 |
Aug 1, 2006 |
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13080230 |
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Current U.S.
Class: |
264/318 |
Current CPC
Class: |
B29L 2001/00 20130101;
B29C 43/42 20130101; B29C 43/08 20130101; B29C 2043/3283 20130101;
B29C 33/20 20130101; B29C 43/50 20130101 |
Class at
Publication: |
264/318 |
International
Class: |
B28B 7/20 20060101
B28B007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2005 |
IT |
MO2005A000212 |
Claims
1. Apparatus for compression-moulding an object from a dose of
plastics, comprising a die arrangement provided with a cavity for
receiving said dose and with at least two parts suitable for
shaping an undercut portion of said object, wherein said at least
two parts are movable with respect to one another along a
substantially rectilinear trajectory.
2. Apparatus according to claim 1, wherein said at least two parts
comprise a first part and a second part.
3. Apparatus according to claim 2, wherein said first part and said
second part are mounted on a carriage movable parallel to a
approach direction along which said die arrangement and a punch
move together for shaping said dose.
4. Apparatus according to claim 3, wherein said carriage is
slidingly drivable along a guiding arrangement parallel to said
approach direction through a driving bar.
5. Apparatus according to claim 2, wherein said first part and said
second part are fixed respectively to a first supporting element
and to a second supporting element.
6. Apparatus according to claim 5, wherein said first supporting
element and said second supporting element comprise respectively a
first sliding portion and a second sliding portion, that are
movable with respect to one another parallel to said
trajectory.
7. Apparatus according to claim 6, wherein said first part and said
second part are mounted on a carriage movable parallel to a
approach direction along which said die arrangement and a punch
move together for shaping said dose and wherein said first sliding
portion and said second sliding portion are slidingly movable along
a bar of said carriage, arranged transversely to said approach
direction.
8. Apparatus according to claim 7, wherein said first sliding
portion and said second sliding portion is provided with respective
rollers, rotatable around respective rotation axes arranged
transversely to said bar and to said approach direction.
9. Apparatus according to claim 8, wherein said rotation axes are
substantially orthogonal to said bar and to said approach
direction.
10. Apparatus according to claim 2, and further comprising a cam
profile for driving said first part and said second part along said
trajectory.
11. Apparatus according to claim 10, wherein said cam profile
comprises a pair of tracks along which said rollers can run and
which are arranged symmetrically with respect to a plane parallel
to said approach direction.
12. Apparatus according to claim 2, and further comprising a
positioning arrangement for positioning said first part in a
contact position wherein said undercut portion can be shaped.
13. Apparatus according to claim 12, wherein said first part and
said second part are mounted on a carriage movable parallel to a
approach direction along which said die arrangement and a punch
move together for shaping said dose and wherein said first sliding
portion and said second sliding portion are slidingly movable along
a bar of said carriage, arranged transversely to said approach
direction and wherein said positioning arrangement comprises a
projection that projects transversely from said bar so that said
first sliding portion can abut against said projection in said
contact position.
14. Apparatus according to claim 13, wherein said projection
projects from an intermediate portion of said bar substantially
orthogonally to a longitudinal axis of said bar.
15. Apparatus according to claim 13, wherein said positioning
arrangement comprises an elastic element arranged for pushing said
first sliding portion against said projection in said contact
position.
16. Apparatus according to claim 15, wherein said elastic element
comprises a helical spring wound around a said bar.
17. Apparatus according to claim 12, and further comprising a
pressing element arranged for pushing said second part against said
first part in said contact position.
18. Apparatus according to claim 17, wherein said positioning
arrangement comprises an elastic element arranged for pushing said
first sliding portion against said projection in said contact
position and wherein said pressing element comprises a further
elastic element having stiffness less than said elastic
element.
19. Apparatus according to claim 18, wherein said further elastic
element comprises a further helical spring wound around said
bar.
20. Apparatus according to claim 13, wherein, in said contact
position, between said second sliding portion and said projection a
gap is defined.
21. Apparatus according to claim 1, wherein said die arrangement is
included in a forming device for compression-moulding a preform of
a container from said dose.
22. Apparatus according to claim 21, wherein said forming device
comprises a plurality of moulds arranged peripherally on a carousel
rotatable around a rotation axis.
23. Apparatus according to claim 22, wherein said rotation axis is
substantially vertical.
24. Apparatus for forming an object, comprising a die arrangement
having a reciprocally movable first part and second part so as to
shape an undercut portion of said object in a contact position
(P1), wherein it comprises a positioning arrangement for
positioning said first part in said contact position and a pressing
element for pushing said second part against said first part in
said contact position.
25. Apparatus according to claim 24, wherein said first part and
said second part are mounted on a carriage that is movable parallel
to an approach direction along which said die arrangement and a
punch approach mutually for forming said object.
26. Apparatus according to claim 25, wherein said carriage is
slidingly drivable along a guiding arrangement parallel to said
approach direction through a driving bar.
27. Apparatus according to claim 24, wherein said first part and
said second part are fixed respectively to a first supporting
element and to a second supporting element.
28. Apparatus according to claim 27, wherein said first supporting
element and said second supporting element comprise respectively a
first sliding portion and a second sliding portion, that are
movable with respect to one another to move said first part and
said second part between said contact position and a distanced
position.
29. Apparatus according to claim 28, wherein said first part and
said second part are mounted on a carriage that is movable parallel
to an approach direction along which said die arrangement and a
punch approach mutually for forming said object and wherein said
first sliding portion and said second sliding portion are slidingly
movable along a bar of said carriage, arranged transversely to said
approach direction.
30. Apparatus according to claim 28, wherein said positioning
arrangement comprises a projection against which said first sliding
portion can abut in said contact position.
31. Apparatus according to claim 30, wherein said first part and
said second part are mounted on a carriage that is movable parallel
to an approach direction along which said die arrangement and a
punch approach mutually for forming said object and wherein said
first sliding portion and said second sliding portion are slidingly
movable along a bar of said carriage, arranged transversely to said
approach direction and wherein said projection projects
transversely from said bar.
32. Apparatus according to claim 31, wherein said projection
projects from an intermediate portion of said bar substantially
orthogonally to a longitudinal axis of said bar.
33. Apparatus according to claim 30, wherein said positioning
arrangement comprises an elastic element arranged for pushing said
first sliding portion against said projection in said contact
position.
34. Apparatus according to claim 33, wherein said first part and
said second part are mounted on a carriage that is movable parallel
to an approach direction along which said die arrangement and a
punch approach mutually for forming said object and wherein said
first sliding portion and said second sliding portion are slidingly
movable along a bar of said carriage, arranged transversely to said
approach direction and wherein said elastic element comprises a
helical spring wound around said bar.
35. Apparatus according to claim 24, and further comprising a
pressing element arranged for pushing said second part against said
first part in said contact position.
36. Apparatus according to claim 35, and further comprising a
pressing element arranged for pushing said second part against said
first part in said contact position and wherein said pressing
element comprises a further elastic element having stiffness less
than said elastic element.
37. Apparatus according to claim 30, wherein, in said contact
position, between said second sliding portion and said projection a
gap is defined.
38. Apparatus according to claim 24, wherein said die arrangement
is included in a forming device for compression-moulding said
object from a dose of plastics.
39. Apparatus according to claim 38, wherein said forming device is
shaped in such a way as to obtain a container preform from said
dose.
40. Apparatus according to claim 38, wherein said forming device
comprises a plurality of moulds mounted on a carousel rotatable
around a rotation axis.
41. Apparatus according to claim 40, wherein said rotation axis is
substantially vertical.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. application Ser.
No. 11/990,308, filed May 14, 2008, now allowed, which is the U.S.
national phase of International Application No. PCT/EP2006/064921,
filed 1 Aug. 2006, which designated the U.S. and claims priority to
Italy Patent Application No. MO2005A000212, filed 10 Aug. 2005,
each incorporated herein by reference in its entirety.
DESCRIPTION
[0002] The invention relates to apparatuses for forming objects, in
particular through compression moulding of plastics. The
apparatuses according to the invention are particularly suitable
for forming preforms for containers, such as bottles, made for
example of polyethyleneterephthalate (PET), polypropylene (PP),
polyvinylchloride (PVC), high density polyethylene (HOPE) or
polyethylenenaphthalate (PEN). WO 2005/058572 discloses an
apparatus for compression moulding synthetic resin preforms by
pressure-inserting a mould punch into a die cavity which is loaded
with a charge. The apparatus comprises a first tubular element,
which is axially fixed during the charge loading and moulding
stage, and a second tubular element, which is axially movable
telescopically relative to the first tubular element in order to
define the die cavity. The apparatus further comprises a thrust
element for pushing the second tubular element upwards.
[0003] U.S. Pat. No. 5,932,155 discloses an apparatus for making
plastic articles utilizing a plurality of tools peripherally
supported on a rotating turret. Each tool comprises a female mould
assembly cooperating with a core. Each tool is moved by cams and
includes a nitrogen cylinder that prevents catastrophic
overload.
[0004] U.S. Pat. No. 4,529,372 discloses an apparatus and a method
for forming hollow articles from plasticized material. A charge of
plasticized material is subjected to a pressure forming step to
form a preform on a core. The preform is then blow-moulded in a
blow cavity by introducing blowing gas into the preform through the
preform core.
[0005] WO 03/072333 discloses an apparatus for forming preforms for
containers comprising a carousel rotatable around a vertical axis
and peripherally provided with a plurality of moulds.
[0006] Each mould comprises a first half mould and a second half
mould that are movable towards and away from one another in a
vertical moulding direction. The first half mould comprises a
punch, associated with two movable die parts provided with shaping
surfaces shaped for forming a threaded neck of the preform. The die
parts are rotatable around a hinge axis arranged parallel to the
moulding direction and can move between a distanced position, in
which the shaping surfaces associated with each die part are
distanced from one another, and a contact position, in which the
shaping surfaces are near one another. A hollow presser keeps the
die parts in contact with one another in the contact position and
is slidable inside a cylindrical chamber containing a substantially
invariable quantity of pressurised gas.
[0007] The latter pushes the hollow presser to the outside of the
cylindrical chamber in contact with the die parts. The cylindrical
chamber is obtained on a movable slide in the moulding
direction.
[0008] The die parts and the punch are reciprocally movable in the
moulding direction. The second half mould comprises a die cavity
shaped for shaping an external substantially cylindrical surface of
the preform.
[0009] A supplying device is furthermore provided that introduces
inside the die cavity a dose of plastics to be shaped.
[0010] During operation, initially, the first half mould and the
second half mould are distant from one another by a quantity that
is such as to enable the supplying device to deposit a dose of
plastics to be shaped inside the die cavity.
[0011] A driving device arranges the two movable die parts in
reciprocal contact and drives the latter and the punch so as to
make them approach the die cavity along the moulding direction. In
an initial phase of the closing operation of the die, the two
movable die parts come into contact with the die cavity and stop
whilst the punch continues to approach said cavity, compressing the
plastics that constitutes the dose and making it progressively
occupy the entire forming chamber defined between the punch, the
die cavity and the movable die parts.
[0012] The slide in which the cylindrical chamber is obtained moves
together with the punch, approaching the die cavity, whilst the
hollow presser remains in a fixed position with respect to the die
cavity, exerting a clamping force on the two movable die parts. The
gas contained in the cylindrical chamber is progressively
pressurised, inasmuch as the volume available to it decreases. As a
result, the clamping force that keeps the two movable die parts
together progressively increases depending on the position of the
hollow presser inside the cylindrical chamber.
[0013] A drawback of the apparatus disclosed in WO 03/072333 is
that it is not possible to apply optimal clamping force to the two
movable die parts. In fact, if in the cylindrical chamber a gas is
present having pressure that is too low, the force exerted on the
hollow presser when the movable die parts shape the neck of the
preform may not be sufficient to counteract the thrust exerted by
the plastics. On the other hand, if in the cylindrical chamber a
gas is present having a pressure that is too high, clamping forces
are generated that are greater than what is required in the phase
in which the movable die parts, although already closed, have not
yet been reached by the plastics. This causes excessive stress to
the components of the apparatus, particularly at the moment in
which the movable die parts come into contact with the die cavity
with a blow that can be rather violent.
[0014] A further drawback of the apparatus disclosed in WO
03/072333 is that the movable die parts, in order to disengage from
undercut portions of the preform that has just been shaped, require
ample maneuvering space. In fact, the neck of each preform is
normally provided with an external thread that is not symmetrical
with respect to a longitudinal axis of the preform. When the
movable die parts rotate around the hinge axis, an end zone of a
die part that has formed a certain thread can interact with
adjacent portions of the thread and possibly damage them. In order
to try to overcome this drawback the distance between the shaping
surface of each die part and the respective hinge axis is
increased, so that the shaping surface moves along a circumference
arch having a relatively great radius. This causes an increase in
the overall dimensions of the apparatus.
[0015] The necks of the preforms are usually provided with a
plurality of grooves that are substantially parallel to the
longitudinal axis of the preform. These grooves enable any gas
contained in the bottle obtained from the preform to leave the
bottle progressively whilst the consumer removes the cap
thereof.
[0016] The aforementioned grooves are delimited, parallel to the
longitudinal axis of the preform, by sides that are tilted
according to a preset angle. If the movable die parts move away
from one another by rotating around a vertical hinge axis, it may
happen, in particular with certain arrangements of the grooves and
of the tilt of the sides that delimit them, that when the movable
die parts move from the contact position to the distanced position
they interfere with the sides of the grooves. In other words, the
sides of the grooves may, for preforms having necks of certain
geometries, constitute undercut portions that it is not possible to
extract from the moulds disclosed in WO 03/072333 without the
movable die parts interfering with the corresponding neck.
[0017] A still further drawback of the known apparatuses is that
they do not enable precise positioning of the movable die parts in
relation to the die cavity and to the hollow presser to be
obtained. In fact, owing to processing errors or assembly defects
in the movable die parts or in a cam that drives them between the
distanced position and the contact position, the movable die parts,
which should meet along a theoretical contact plane, may touch in a
different position from the one envisaged. If this occurs, the
movable die parts may be misaligned with respect to a seat obtained
in the die cavity and/or to a further seat obtained in the hollow
presser with which they are intended to engage through shapingly
coupling. Imprecisions in the moulding operations and undesired
blows are thus generated or even the closing of the mould may be
prevented.
[0018] Apparatuses are known for forming caps through compression
moulding, comprising a to moulding carousel on which there is
mounted a plurality of moulds. Each mould comprises a die that is
movable with respect to a corresponding punch in a moulding
direction, between an open position in which a dose of plastics is
introduced into the die and a closing position in which the dose is
shaped so as to obtain the cap.
[0019] In the known apparatuses for producing caps, the dies are
moved by respective actuators connected to a single hydraulic
circuit provided with valves that regulate the moulding operations.
When a die receives a dose, the hydraulic circuit sends a driving
fluid to the corresponding actuator so as to move the die to the
punch. Only when the die is in the closed position, the hydraulic
circuit can be used to drive a subsequent die that has just
received a new dose.
[0020] In order to increase productivity in the apparatuses
disclosed above, the hydraulic circuit is run in extreme
conditions, so as to reduce as far as possible the time required to
close or open the moulds. Nevertheless, peaks and jumps of pressure
are recorded in the driving fluid operating in the hydraulic
circuit that generate a rapid deterioration of the components and
can seriously damage the apparatus.
[0021] An object of the invention is to improve the apparatuses for
forming objects, particularly preforms for containers.
[0022] Another object of the invention is to provide an apparatus
for forming objects having undercut portions by using a die
arrangement comprising at least two movable parts, in which the
movable parts are kept in contact with one another with an optimal
clamping force.
[0023] A still further object of the invention is to obtain an
apparatus provided with a die arrangement comprising at least two
movable parts that require reduced maneuvering space to completely
disengage from undercut portions of the formed objects without
damaging them.
[0024] A still further object of the invention is to obtain an
apparatus provided with a device for positioning in a precise and
repeatable manner said at least two movable parts.
[0025] A still further object of the invention is to provide an
apparatus provided with a mould arrangement drivable by a drive
circuit arrangement that enables the closing and opening operations
of the mould arrangement to be optimised.
[0026] In a first aspect of the invention, there is provided an
apparatus for forming an object from a dose of plastics, comprising
a die arrangement provided with a cavity for receiving said dose
and with at least two parts reciprocally movable for shaping an
undercut portion of said object, at least one fluid for applying a
clamping force so as to keep said at least two parts in contact,
wherein said at least one fluid is such as to increase
discontinuously said clamping force from an initial force that is
applicable when said dose is substantially contained in said cavity
to a final force that is applicable when said at least two parts
shape said undercut portion.
[0027] Owing to this aspect of the invention, it is possible to
obtain an apparatus in which to the at least two movable parts an
optimal clamping force is applied in subsequent forming phases. In
fact, the at least one fluid exerts a relatively low initial force
whilst the plastics, initially received in the cavity, flows to the
at least two movable parts without yet having reached them. A final
force that is significantly greater than the initial force is on
the other hand exerted when the plastics, having reached the at
least two movable parts, tends to distance them from one
another.
[0028] The at least one fluid acts on the at least two movable
parts with very reduced overall dimensions and maintains high
long-term operating efficiency, thus reducing maintenance
costs.
[0029] In a second aspect of the invention, there is provided an
apparatus for compression-moulding an object from a dose of
plastics, comprising a die arrangement provided with a cavity for
receiving said dose and with at least two parts suitable for
shaping an undercut portion of said object, wherein said at least
two parts are movable with respect to one another along a
substantially rectilinear trajectory.
[0030] Owing to this aspect of the invention, it is possible to
obtain an apparatus in which the aforementioned at least two parts
can disengage completely from the formed objects in very reduced
maneuvering spaces without damaging undercut portions of these
objects. In a third aspect of the invention, there is provided an
apparatus for forming an object, comprising a die arrangement
having a first part and a second part that are reciprocally movable
so as to shape an undercut portion of said object in a contact
position, wherein it comprises a positioning arrangement for
positioning said first part in said contact position and a pressing
element for pushing said second part against said first part in
said contact position.
[0031] Owing to this aspect of the invention, it is possible to
obtain an apparatus that enables the first part and the second part
of the die arrangement to be arranged in a precise and repeatable
manner. In fact, the pressing element only pushes the second part
against the first part in the contact position, without modifying
the contact position, determined unequivocally by the positioning
arrangement.
[0032] This enables the positioning errors of the first part and of
the second part of the die arrangement to be reduced considerably
that may cause undesired blows to the moulds and imperfections in
the formed objects.
[0033] In a fourth aspect of the invention, there is provided an
apparatus for forming objects comprising a plurality of moulds that
are openable and closable by means of a hydraulic device, wherein
said hydraulic device comprises a hydraulic circuit arrangement
arranged for driving a fraction of said plurality of moulds and a
further hydraulic circuit arrangement distinct from said hydraulic
circuit arrangement and arranged for driving a further fraction of
said plurality of moulds.
[0034] Owing to this aspect of the invention, it is possible to
obtain an apparatus provided with a hydraulic device that enables
the opening and closing times of the moulds to be optimised. In
this way it is possible to obtain high productivity without it
being necessary to have to subject the components of the hydraulic
device to extreme operating conditions. For example, if the
hydraulic circuit arrangement comprises a first hydraulic circuit
and the further hydraulic circuit arrangement comprises a second
hydraulic circuit, the first hydraulic circuit and the second
hydraulic circuit being distinct from one another and each arranged
for driving a respective fraction of the aforementioned plurality
of moulds, it is possible to double the operating time that each
mould requires in order to be able to complete a particular
operation during moulding. For example, a first mould, after
receiving a dose of plastics to be shaped, has time within which to
complete closure that is double the traditional ease in which only
one hydraulic circuit is provided. In fact, it is not necessary to
complete closure of the first mould in order to enable a second
mould adjacent thereto to be able to be driven, inasmuch as the
latter is connected to the second hydraulic circuit and is
independent of the first mould. Closing of the first mould has to
be completed to enable driving of a third mould, adjacent to the
second mould and connected operationally to the first hydraulic
circuit. It is possible to provide a number of hydraulic circuits
equal to the number of moulds so that each of the latter can be
driven in a manner that is completely autonomous and independent of
the other moulds.
[0035] The invention can be better understood and implemented with
reference to the attached drawings that illustrate some embodiments
thereof by way of non-limitative example, in which:
[0036] FIG. 1 is a fragmentary and partially sectioned view of a
portion of an apparatus for forming objects in a first operating
configuration;
[0037] FIG. 2 is a view of the apparatus in FIG. 1 in a second
operating configuration;
[0038] FIG. 3 is a view of the apparatus in FIG. 1 in a third
operating configuration;
[0039] FIG. 4 is a view of the apparatus in FIG. 1 in a fourth
operating configuration;
[0040] FIG. 5 is a view of the apparatus in FIG. 1 in a fifth
operating configuration;
[0041] FIG. 6 is a view of the apparatus in FIG. 1 in a sixth
operating configuration;
[0042] FIG. 7 is a view of the apparatus in FIG. 1 in a seventh
operating configuration;
[0043] FIG. 8 is a view of the apparatus in FIG. 1 in an eighth
operating configuration;
[0044] FIG. 9 is a perspective view showing a portion of the
apparatus in FIG. 1 comprising some movable die parts;
[0045] FIG. 10 is a view from above of the portion of apparatus
shown in FIG. 9;
[0046] FIG. 11 is a perspective view of the rear of the portion of
apparatus shown in FIG. 9;
[0047] FIG. 12 is another view of the rear of the portion of
apparatus shown in FIG. 9;
[0048] FIG. 13 is a partially sectioned side view, showing
supporting arms for supporting the movable die parts of FIG. 9;
[0049] FIG. 14 is a plan view of the supporting arms of FIG.
13;
[0050] FIG. 15 is a section taken along the plane XV-XV in FIG.
13;
[0051] FIG. 16 is a fragmentary and partially sectioned view of an
apparatus for forming objects provided with a hydraulic circuit
arrangement and with a further hydraulic circuit arrangement;
[0052] FIG. 17 is a partially sectioned schematic view that shows
the hydraulic circuit arrangement in FIG. 16;
[0053] FIG. 18 is a partially sectioned schematic plan view showing
the hydraulic circuit arrangement in FIG. 17;
[0054] FIG. 19 is a partially sectioned schematic view that shows
the further hydraulic circuit arrangement in FIG. 16;
[0055] FIG. 20 is a partially sectioned schematic plan view,
showing the further hydraulic circuit arrangement in FIG. 19.
[0056] With reference to FIGS. 1 to 8, there is shown an apparatus
1 for forming objects, in particular preforms 2, from doses 3 of
plastics.
[0057] The apparatus comprises a plurality of moulds 4 supported
peripherally on a moulding carousel rotatable around a rotation
axis. Each mould 4 comprises a first half mould 5 and a second half
mould 6 that are drivable in a reciprocal approaching/moving away
direction along a moulding axis D parallel to said rotation
axis.
[0058] The first half mould 5 comprises a supporting element 7
provided with a cavity delimited by a wall 10. Within the aforesaid
cavity a fixing body 8 is housed centrally by means of which a
punch 9 is fixed to the supporting element 7.
[0059] Within the cavity of the supporting element 7 an internal
transverse surface 12 is provided to which a fixed-sleeve element
11 is fixed that is coaxial to the moulding axis D. The
fixed-sleeve element 11 is provided below with an abutting portion
19 that projects radially to the moulding axis D towards the wall
10. The abutting portion 19 is distant from the wall 10 by a
quantity that is such as to define a passage section 20.
[0060] Between the fixed-sleeve element 11 and the wall 10 a
movable sleeve element 14 is housed that is slidable along the
moulding axis D. The movable sleeve element 14 comprises a first
operating surface 15 above, facing the transverse surface 12 and
distanced from the latter by a quantity that is variable according
to the position of the movable sleeve element 14 inside the
supporting element 7. In this way the first operating surface 15,
an internal surface of the wall 10 and an external surface of the
fixed-sleeve element 11 define an upper chamber 16 having a height,
measured along the moulding axis D, which is variable according to
the position of the movable sleeve element 14.
[0061] The movable sleeve element 14 is provided below with a
resting surface 18 shaped to rest on the abutting portion 19 of the
fixed-sleeve element 11. From the resting surface 18 an appendage
21 of cylindrical shape provided with a second operating surface 22
that is transverse to the moulding axis D projects towards the
second half mould 6. The appendage 21 is able to traverse the
passage section 20 so as to arrange the second operating surface 22
at a lower height than the abutting portion 19.
[0062] The upper chamber 16 is supplied, by means of a conduit 17,
with a fluid, for example compressed air, that pushes the movable
sleeve element 14 downwards so as to arrange the resting surface 18
in contact with the abutting portion 19. The aforesaid fluid can be
contained in a tank that is not shown, connected to the conduit 17.
If the tank has a volume that is much greater than that of the
upper chamber 16, it can be stated that the fluid inside the
chamber has substantially constant pressure.
[0063] Seals are arranged on side surfaces of the movable sleeve
element 14 that perform a sealing action on the fluid inside the
upper chamber 16.
[0064] The fixed-sleeve element 11 is arranged in relation to the
fixing body 8 in such a way that a cylindrical cavity 23 shown in
FIGS. 1 and 2 is defined therebetween.
[0065] The first half mould 5 further comprises a holding sleeve 13
partially housed inside the supporting element 7 and arranged in
such a way as to partially surround the punch 9. The holding sleeve
13 is slidingly movable with respect to the punch 9 parallel to the
moulding axis D and comprises a coupling portion 24 on which there
can be obtained a frustum conical surface 27 and a cylindrical
surface 79, both facing the punch 9. The cylindrical surface 79 is
arranged above the frustum conical surface 27.
[0066] The coupling portion 24 is delimited above by a contact
surface 25, arranged transversely to the moulding axis D, from
which a cylindrical portion 26 having a section such as to be
received inside the cylindrical cavity 23 projects towards the
internal transverse surface 12.
[0067] The holding sleeve 13 comprises an air suction-injection
conduit 50 that is used to suck air during closing operation of the
mould 4 to facilitate the forming operation and to inject air
during opening operation of the mould 4, to facilitate the
extraction of the newly-shaped preform 2.
[0068] Between the contact surface 25, the wall 10, the appendage
21, the abutting portion 19, and the cylindrical portion 26, there
is defined a lower chamber 28, the height of which, measured
parallel to the moulding axis D, is variable according to the
position of the holding sleeve 13 with respect to the supporting
element 7. The lower chamber 28 communicates, through a gap defined
between the cylindrical portion 26 and the fixed-sleeve element 11,
with a zone 30 of the cylindrical cavity 23, shown in FIGS. 1 and
2. The zone 30 is delimited by the cylindrical portion 26, by the
fixed-sleeve element 11 and by the fixing body 8. A further conduit
29 supplies the zone 30, and then also the lower chamber 28, with a
further fluid, for example compressed air, at a pressure that is
less than the pressure provided in the upper chamber 16.
[0069] The aforementioned further fluid can be contained in a
further tank that is not shown, connected to the further conduit
29. If the further tank has a volume that is much greater than that
of the lower chamber 28, it can be stated that the further fluid
inside the chamber has a substantially constant pressure.
[0070] If the fluid in the upper chamber 16 and the further fluid
in the lower chamber 28 are compressed air, the tank and the
further tank to which the conduit 17 and the further conduit 29 are
connected can be connected periodically to an air-dispensing
device, which can be provided on the carousel. In this way it is
ensured that the pressure in the upper chamber 16 and in the lower
chamber 28 does not decrease excessively because of possible
leaks.
[0071] The dispensing device can withdraw relatively low-pressure
compressed air, for example 6 bar, from an industrial supply line.
Rotating joints are provided that are equipped with seals and that
connect a removal port of the dispensing device to a distribution
port of the supply line.
[0072] As the pressure of the compressed air coming from the supply
line is relatively low, complicated arrangements are not necessary
for the seals to prevent leaks inside the rotating joint.
[0073] The dispensing device further comprises a first pressure
multiplier that compresses the air, initially having pressure that
is equal to the supply line pressure, until it reaches a first
pressure value, for example 24 bar, with which the lower chamber 28
is supplied. The dispensing device further comprises a second
pressure multiplier that compresses the air until it reaches a
second pressure value that is greater than the first pressure value
and equal, for example, to 48 bar, with which the upper chamber 16
is supplied. The second pressure multiplier can be provided
downstream of the first pressure multiplier so as to receive from
the latter a fraction of air flow that has already undergone a
first increase in to pressure and which is intended to be again
compressed until it reaches the second pressure value.
[0074] The holding sleeve 13 is provided on the side, in a central
region thereof, with an external seal surface 31, provided with
seals, delimited below by a further resting surface 32, arranged
transversely to the moulding axis D and shaped to be supportingly
received by an abutting element 33, fixed below the wall 10.
[0075] The further fluid in the lower chamber 28 pushes down the
holding sleeve 13, in such a way that the further resting surface
32 is in contact with the abutting element 33.
[0076] Thermoregulating conduits 34 are provided arranged between
the punch 9 and the holding sleeve 13, that are used to cool the
mould 4 during the moulding operations.
[0077] The first half mould 5 comprises a pair of movable die parts
35 (also shown in FIGS. 9 to 12), that are used to shape a portion
of the preform 2 comprising a threaded neck that is provided with
undercut zones. The movable die parts 35 are drivable towards/away
from one another and with respect to the moulding axis D. The
movable die parts 35 at least partially surround the punch 9 and
can move parallel to the moulding axis D with respect to the
aforementioned punch.
[0078] Each of the movable die parts 35 comprises an internal
shaping surface 36 suitable for shaping at least an external
surface of the threaded neck of the preform 2. In particular, if it
is desired to obtain a bottle of limited capacity from the preform,
the internal shaping surface 36 shapes only the neck of the preform
which comprises an external thread, an annular projection and a
collar, which do not undergo substantially shape variations during
the subsequent stretch-blowing process undergone by the preform. If
on the other hand it is desired to obtain a bottle with great
capacity, for example 1.5 litres, the movable die parts 35 shape
not only the neck but also an intermediate portion of the preform
intended to form part of the containing body of the bottle.
[0079] Each movable die part 35 is delimited externally by a
further frustum conical surface 37, suitable for interacting with
the frustum conical surface 27 of the holding sleeve 13 and by a
further cylindrical surface 80, arranged above the further frustum
conical surface 37 to interact with the cylindrical surface 79 of
the holding sleeve 13.
[0080] The movable die parts 35 are delimited below by a transverse
coupling surface 57, transverse to the moulding axis D and shaped
to interact with the second half mould 6.
[0081] The transverse coupling surface 57 is surrounded by an
annular surface 60 of frustum conical shape, suitable for
interacting with the second half mould 6.
[0082] The movable die parts 35 are provided above with abutting
portions 77, shown in FIG. 2, that can abut on resting portions 78
of the punch 9.
[0083] As shown in FIGS. 14 and 15, a carriage 38 is provided that
supports the movable die parts 35, and which can be slidingly moved
by a driving bar 41 along a guiding column 40, parallel to the
moulding axis D. The carriage 38 enables owing to a cam profile 49
that will be disclosed in detail below, the movable die parts 35 to
be moved between a contact position P1 and a distanced position P2,
shown in FIGS. 9 and 10. In the contact position P1, the movable
die parts 35 are in contact together so as to shape at least the
neck of the preform 2. In the distanced position P2, the movable
die parts 35 have moved away from one another to free the neck of
the preform 2 so that the latter can be extracted from the mould
4.
[0084] The movable die parts 35 are supported on the carriage 38
respectively by means of a first supporting arm 39a and a second
supporting arm 39b, shown in FIGS. 13 to 15. The first supporting
arm 39a and the second supporting arm 39b comprise respectively a
first sliding portion 42a and a second sliding portion 42b that can
slide along a supporting cylindrical bar 43 fixed to the carriage
38, in a direction E arranged transversely to the moulding axis
D.
[0085] The cylindrical bar 43 is provided, in an intermediate
portion thereof, with an abutting element comprising a cylindrical
projection 45, shaped in such a way as to supportingly receive the
first sliding portion 42a of the first supporting arm 39a. A first
positioning spring 46 is provided arranged around a portion of the
cylindrical bar 43, so as to push the first sliding portion 42a
against the cylindrical projection 45.
[0086] The first positioning spring 46 and the cylindrical
projection 45 act as a positioning arrangement that enables the
first supporting arm 39a, together with the movable die part 35
mounted thereupon, to be positioned in the contact position P1 in a
precise and repeatable manner.
[0087] The apparatus 1 further comprises a pressing element
provided with a second positioning spring 47, having lower
stiffness than the first positioning spring 46. The second
positioning spring 47 is arranged around a further portion of the
cylindrical bar 43 opposite the portion on which the first
positioning spring 46 is wound with respect to the cylindrical
projection 45.
[0088] The second positioning spring 47 acts on the second sliding
portion 42b so as to push the movable die part 35 mounted on the
second supporting arm 39b against the movable die part 35 mounted
on the first supporting arm 39a.
[0089] As the second positioning spring 47 is less stiff than the
first positioning spring 46, the movable die part 35 mounted on the
second supporting arm 39b is not able to significantly move the
movable die part 35 mounted on the first supporting arm 39a, held
in the contact position P1 by the positioning arrangement.
[0090] It should be noted that, in the contact position P1, it is
possible to define a gap C between the second sliding portion 42b
and the cylindrical projection 45, as shown in FIG. 15. Owing to
the gap C, in the contact position P1, the cylindrical projection
45 does not influence the movable die part 35 mounted on the second
supporting arm 39b. Said part is thus positioned only by the
movable die part 35 mounted on the first supporting arm 39a. This
enables the movable die parts 35 to be positioned with great
precision with respect to the moulding axis D in the contact
position P1.
[0091] On the first sliding portion 42a and on the second sliding
portion 42b rollers 44 are supported respectively that are
rotatable around respective rotation axes G that are transverse to
the moulding axis D. Each roller 44 is shaped to move in relation
to the aforementioned cam profile 49 that is arranged in a fixed
position on the moulding carousel and is shown in FIGS. 9 to
12.
[0092] In the contact position P1, the rollers 44 do not interact
with the cam profile 49, as shown in FIG. 11. When it is desired to
extract the preform 2 from the mould 4, the carriage 38 is moved
along the guiding column 40 by the driving bar 41, so that the
rollers 44 start to interact with respective ramps of the cam
profile 49, with which they are kept in contact respectively by the
first positioning spring 46 and by the second positioning spring
47.
[0093] The rollers 44 move away from or towards one another
depending on the zone of the cam profile 49 along which they
travel. In particular, in the example shown, the rollers 44 move
away from one another when the carriage 38 is moved down along the
moulding axis D, whilst they move towards one another when the
carriage 38 is moved upwards.
[0094] The first sliding portion 42a and the second sliding portion
42b, dragged by the respective rollers 44, can move away from one
another or towards one another in the direction E, as shown in
FIGS. 13 to 15. As a result, also the movable die parts 35 can move
away from or towards one another, as shown in FIGS. 9 to 12,
depending on the position of the rollers 44 with respect to the cam
profile 49. It is noted that when the carriage 38 runs parallel to
the moulding axis D, the movable die parts 35 mounted on the
carriage 38 move with respect to one another in a rectilinear
manner.
[0095] The movable die parts 35 can, in this way, be moved without
changing the orientation thereof with respect to the moulding axis
D.
[0096] As shown in FIGS. 1 to 8, the second half mould 6 comprises
a die portion 54 provided internally with external shaping surfaces
55 that delimit a central cavity 53. The external shaping surfaces
55 are suitable for shaping externally a side wall 56 and a bottom
wall 81 with which the preform 2 is provided.
[0097] The die portion 54 comprises above a further transverse
coupling surface 58, intended to come into contact with the
transverse coupling surface 57 of the movable die parts 35.
[0098] The further transverse coupling surface 58 is delimited
peripherally by an annular projection 59 that projects towards the
first half mould 5 and is provided internally with a further
annular surface 61 having frustum conical shape, shown in FIG. 4,
intended to come into contact with an annular surface 60. The
further transverse coupling surface 58 and the annular surface 60
ensure precise positioning of the die parts mobile 35 with respect
to the die portion 54.
[0099] During operation, the first half mould 5 and the second half
mould 6 are initially far from one another to enable the dose 3 of
plastics to be introduced inside the central cavity 53, as shown in
FIG. 1.
[0100] The carriage 38 moves parallel to the moulding axis D the
movable die parts 35 that, controlled by the cam profile 49, are
arranged in the contact position P1. Subsequently, the movable die
parts 35 start to interact with the holding sleeve 13. In
particular, the further cylindrical surfaces 80 of the movable die
parts 35 start to interact with the cylindrical surface 79 of the
holding sleeve 13 before the further frustum conical surfaces 37
start to interact with the frustum conical surface 27. This enables
the movable die parts 35 to be centred correctly with respect to
the holding sleeve 13. Further, when the movable die parts 35 have
come into complete contact with the holding sleeve 13, as shown in
FIG. 1, the cylindrical surface 79 cooperates with the further
cylindrical surfaces 80 and the frustum conical surface 27
cooperates with the further frustum conical surfaces 37 to keep the
movable die parts 35 in the contact position P1.
[0101] In the configuration shown in FIG. 1, the holding sleeve 13
is pressed against the abutting element 33 by the further fluid
contained in the lower chamber 28.
[0102] Subsequently, the second half mould 6 is advanced to the
first half mould 5 along the moulding axis D. At a certain moment,
shown in FIG. 2, the die portion 54 comes into contact with the
movable die parts 35. The punch 9 is received inside the central
cavity 53, starting to interact with dose 3, that flows to the
movable die parts 35.
[0103] Whilst the second half mould 6 continues to move to the
first half mould 5, the die portion 54 pushes up the movable die
parts 35 that in turn lift up the holding sleeve 13, that
compresses the further fluid contained in the lower chamber 28. The
aforementioned further fluid keeps the holding sleeve 13 in contact
with the movable die parts 35, so that the coupling portions 24
exert on the further cylindrical surfaces 80 and on the further
frustum conical surfaces 37 an initial clamping force that is
proportionate to the pressure of the further fluid contained in the
lower chamber 28. As this pressure is less than the pressure of the
fluid contained in the upper chamber 16, the initial clamping force
is not particularly great. On the other hand, in these moulding
phases great clamping force is not required to keep the movable die
parts 35 in contact, as the latter have not yet been reached by the
plastics that would tend to separate them.
[0104] Simultaneously, through the injection-suction conduit 50,
air is sucked from the central cavity 53 through gaps defined
between the punch 9 and the movable die parts 35. This helps the
dose 3 to flow upwards and prevents the plastics from deteriorating
due to the high temperatures of the air contained in the forming
chamber defined between the punch 9, the movable die parts 35 and
the die portion 54. The air in the aforementioned chamber in fact
has become significantly overheated due to the great pressure that
is generated during the forming phases.
[0105] Subsequently, as the second half mould 6 continues to
approach the first half mould 5, the contact surface 25 of the
holding sleeve 13 abuts on the second operating surface 22 of the
movable sleeve element 14. The holding sleeve 13 thus starts to
interact with the movable sleeve element 14 and pushes it to the
internal transverse surface 12 of the supporting element 7,
compressing the fluid contained in the upper chamber 16.
Simultaneously, the plastics flow near the shaping surfaces 36
generating progressively the threaded neck of the preform 3.
[0106] The movable die parts 35, and therefore also the holding
sleeve 13, end the upward stroke when the abutting portions 77 meet
the resting portions 78, as shown in FIG. 3. The plastics
constituting the dose 3 completely fill the forming chamber defined
between the punch 9, the movable die parts 35 and the die portion
54.
[0107] During this phase, the holding sleeve 13 keeps the movable
die parts 35 in the contact position P1 with a final clamping force
depending on the pressure of the fluid in the upper chamber 16.
More precisely, the fluid contained in the upper chamber 16 exerts
on the movable sleeve element 14 a first force that is proportional
to the pressure in the upper chamber 16. The aforementioned first
force, which is substantially parallel to the moulding axis D and
is directed to the movable die parts 35, is not transmitted
completely by the movable sleeve element 14 to the holding sleeve
13. In fact, on the movable sleeve element 14 a second force also
acts that is parallel to the moulding axis D and directed to the
supporting element 7, which is proportional to the pressure in the
lower chamber 28. As the first force and the second force have
directions that are opposite to one another, the movable sleeve
element 14 transmits to the holding sleeve 13 a third force
obtained by removing the second force from the first force. The
holding sleeve 13 in turn exerts on the movable die parts 35 a
clamping force that is proportional to said third force.
[0108] As the pressure in the upper chamber 16 is noticeably
greater than that present in the lower chamber 28, the second force
tending to push the movable sleeve element 14 to the supporting
element 7 is significantly less than the first force with which the
movable sleeve element 14 is pushed towards the holding sleeve 13.
In this way a third force is obtained and thus a final clamping
force proportional thereto that is noticeably higher than the
initial clamping force, depending on the pressure in the lower
chamber 28. This enables the movable die parts 35 to be kept in the
contact position P1 even when, as shown in FIG. 3, the plastics has
filled the space defined between the punch 9 and the movable die
parts 35 and exerts a thrust on the parts that tends to move them
away from one another.
[0109] It is noted that the clamping force with which the holding
sleeve 13 keeps the movable die parts 35 in reciprocal contact is
initially rather low, being proportional to the pressure in the
lower chamber 28. When the holding sleeve 13 starts to interact
with the movable sleeve element 14, the clamping force increases
discontinuously, i.e. in a almost instantaneous manner inasmuch as
the fluid is compressed, having relatively high pressure, contained
in the upper chamber 16. The stroke of the components that
constitute the mould 4, and in particular the holding sleeve 13 and
the movable sleeve element 14, is dimensioned in such a way that
the fluid contained in the upper chamber 16 starts to be compressed
when the plastics has arrived near the movable die parts 35. In
this way, the clamping force increases only when it is actually
necessary, i.e. when the plastics tend to separate the movable die
parts 35.
[0110] After the preform 2 has remained inside the mould 4 for a
sufficient time for the shape thereof to stabilise and the plastics
that constitutes it to cool sufficiently, through the
injection-suction conduit 50, air is injected inside the second
half mould 6, so as to promote the detachment of the punch 9 from
the preform 2.
[0111] The second half mould 6 is then moved away from the first
half mould 5. The punch 9 is partially disengaged from the preform
2 that has just been shaped whilst the movable die parts 35 remain
joined together through the holding sleeve 13, and retain the
preform 2 by means of the undercuts obtained on the threaded neck,
as shown in FIG. 4.
[0112] Whilst the second half mould 6 disengages from the first
half mould 5, the movable die parts 35, together with the holding
sleeve 13, are moved away from the supporting element 7 through the
effect of the pressure of the fluids contained respectively in the
upper chamber 16 and in the lower chamber 28, until the position
shown in FIG. 5 is reached. In this position, the resting surface
18 of the movable sleeve element 14 is in contact with the abutting
portion 19 of the fixed-sleeve element 11, whilst the further
resting surface 32 of the holding sleeve 13 is in contact with the
abutting element 33. The volume of the upper chamber 16 and of the
lower chamber 28 is thus optimal.
[0113] Subsequently, the movable die parts 35 are moved downwards
by the carriage 38, so as to disengage from the holding sleeve 13,
as shown in FIGS. 6 and 7.
[0114] The cam profile 49 thus moves the movable die parts 35 away
from one another so that the latter parts separate from the
threaded neck of the preform 2, without generating impediments
connected with the undercuts of the latter. At this point, as shown
in FIG. 8, the preform 2 can be extracted from the mould 4 and
conveyed to a subsequent is processing station.
[0115] In an embodiment that is not shown, instead of the upper
chamber 16 and of the lower chamber 28 a single chamber can be
provided, in which a fluid is conveyed having a relatively low
initial pressure, so as to apply on the movable die parts 35 an
initial clamping force that is not particularly great. When the
plastics starts to interact with the movable die parts 35, the
pressure of the fluid sent to the aforementioned single chamber is
suddenly increased by a significant quantity. This enables the
clamping force to be increased in such a manner as to keep the
movable die parts 35 closed even when the plastics would tend to
separate them.
[0116] In a further embodiment that is not shown, more than two
chambers can be provided containing respective fluids having
progressively growing pressure values. This enables the clamping
force to be well calibrated during closing the mould.
[0117] With reference to FIG. 16, there is shown an apparatus 100,
comprising a carousel 68 that is rotatable around a rotation axis
H, and that is provided, in a peripheral region thereof, with a
plurality of moulds that are not shown, for example of the type
disclosed previously with reference to FIGS. 1 to 15.
[0118] Each mould is movable between an open position, of the type
shown in FIG. 1, in which a dose of plastics can be inserted inside
the mould, and a closing position, of the type shown in FIG. 3, in
which the dose is shaped so as to obtain a desired object, for
example a preform for bottles. To take the mould from the open
position to the closed position or vice versa, it is possible to
drive a mould component with respect to a further mould component
that remains fixed. For example, if the mould is of the type shown
in FIGS. 1 to 8, the second half mould 6 is moved with respect to
the punch 9 by means of a hydraulic device that will be disclosed
below.
[0119] The aforementioned hydraulic device comprises a first
hydraulic circuit 66 that drives a first fraction, particularly a
first half, of the plurality of moulds mounted on the carousel 68,
and a second hydraulic circuit 67 that drives a second fraction,
particularly a second half, of the aforementioned plurality of
moulds.
[0120] The first hydraulic circuit 66 and the second hydraulic
circuit 67 are connected to the moulds mounted on the carousel 68
in an alternate manner, i.e. the first hydraulic circuit 66 drives
a plurality of first moulds each of which is interposed between two
second moulds of a plurality of second moulds associated with the
second hydraulic circuit 67, and vice versa.
[0121] As shown in FIGS. 17 and 18, the first hydraulic circuit 66
is provided with a first pump that is not shown that sends a first
pressurised driving fluid, for example oil, in a first inlet
conduit 82 arranged parallel to the rotation axis H. The first
inlet conduit 82 leads into a first annular conduit 83, extending
around the rotation axis H, from which a plurality of first
distributing conduits 69 leads away. The latter are arranged
radially with respect to the first annular conduit 83 and are
angularly equidistant around the rotation axis H. Each first
distributing conduit 69 is in fluid communication with a plurality
of first supply conduits 84, obtained in a peripheral region of the
carousel 68 and arranged transversely to the first distributing
conduits 69. Each first supply conduit 84 is associated with a
first valve 85 that enables the first driving fluid to be
introduced to a corresponding first actuator that is not shown that
is associated with a first mould of the first fraction of
moulds.
[0122] Each first valve 85 is mounted in a first seat 86, obtained
on the carousel 68 and more visible in FIG. 20. The first seats 86
are positioned along a first circumference C1, centred on the
rotation axis H and arranged near the external perimeter P the
carousel 68. The first seats 86 are angularly distanced at an equal
distance along the first circumference C1.
[0123] With each first valve 85 a first connecting conduit 87 is
further associated by means of which the first driving fluid
coining from the first valve 85 can be sent to the corresponding
first actuator. The first valve 85 is adjacent to a first discharge
channel 88 for discharging the first driving fluid when the
corresponding first mould is opened.
[0124] The first hydraulic circuit 66 further comprises first
return conduit arrangement 70, shown in FIG. 16, that takes the
first driving fluid from the first discharge channel 88 to the
first pump.
[0125] Similarly, the second hydraulic circuit 67, shown in detail
in FIGS. 19 and 20, is provided with a second pump that is not
shown that sends a second pressurised driving fluid, for example
oil, to a second inlet conduit 89 arranged parallel to the rotation
axis H. The second inlet conduit 89 leads into a second annular
conduit 90, from which a plurality of second distributing conduits
71 lead away. The latter are arranged radially with respect to the
second annular conduit 90 and are angularly equidistant around the
rotation axis H.
[0126] Each second distributing conduit 71 is in fluid
communication with a plurality of second supply conduits 91
obtained on the carousel 68 transversely to the second distributing
conduits 71. The second supply conduits 91 are arranged in the
peripheral region of the carousel 68 in which the first supply
conduits 84 are obtained, in a more inward position than the
latter.
[0127] Each second supply conduit 91 is associated with a second
valve 92 that enables the second driving fluid to be introduced to
a corresponding second actuator that is not shown that is
associated with a second mould of the second fraction of
moulds.
[0128] Each second valve 92 is mounted in a second seat 93,
obtained on the carousel 68 and better visible in FIG. 18. The
second seats 93 are positioned along a second circumference C2,
centred on the rotation axis H and arranged in an internal position
with respect to the first circumference C1. The second seats 93 are
angularly equidistant along the second circumference C2. The second
seats 93 are further arranged in an angularly staggered position
around the rotation axis H with respect to the first seats 86.
[0129] With each second valve 92 a second connecting conduit 94 is
further associated, by means of which the second driving fluid
coming from the second valve 92 can be sent to the corresponding
second actuator. The second valve 92 is arranged near a second
discharge channel 95 for discharging the second driving fluid when
the corresponding second mould is opened.
[0130] The second hydraulic circuit 67 further comprises second
return conduit arrangement 72, shown in FIG. 16, that takes the
second driving fluid from the second discharge channel 95 to the
second pump.
[0131] During operation, a first mould, associated with the first
hydraulic circuit 66, is initially in the open position in such a
way that a dispensing device for dispensing plastics can introduce
a dose 3 of plastics inside it. Whilst the carousel 68 rotates
continuously around the rotation axis H, the first valves 85
interact with a first cam arrangement that is not shown that
modifies the position of the aforementioned valves along the
rotation axis H. In particular, after the first mould has received
the dose 3 from the dispensing device, the first cam arrangement
positions the corresponding first valve 85 in a driving position,
in which the first supply conduit 84 communicates with the first
connecting conduit 87. The first driving fluid is thus sent to the
corresponding first actuator to move the corresponding second half
mould 6 to the first half mould 5, thus shutting the first mould.
As the first mould is closed, a second mould, adjacent to the first
mould and arranged in the open position, interacts with the
dispensing device to receive in turn a dose of plastics.
Subsequently, the second hydraulic circuit 67, in a similar manner
to what has been disclosed above regarding the first mould, closes
the second mould. Whilst the second hydraulic circuit 67 starts to
close the second mould, the first hydraulic circuit 66, since it is
independent of the second hydraulic circuit 67, can stop closing
the first mould. In the meantime, the second mould moves away from
the dispensing device to enable a third mould, associated with the
first hydraulic circuit 66, to be supplied with a respective
dose.
[0132] After closing the first mould completely, the first driving
fluid remains in the first actuator so as to keep the first mould
in the closed position, in order to enable the preform that has
just been formed to be cooled and the shape thereof to
stabilize.
[0133] The first pump, having already closed the first mould, can
start to send the first driving fluid to the third mould, so as to
close the latter in a manner that is completely similar to what has
been disclosed above with reference to the first mould. The second
hydraulic circuit 67 can subsequently close a fourth mould,
arranged in a position that is adjacent to the third mould, and so
on for all the moulds mounted on the carousel 68.
[0134] When the first mould has to be taken to the open position,
the first cam arrangement positions the first valve 85 in a
discharge position in which the first driving fluid contained in
the first actuator can be discharged into the first discharge
channel 88. This may occur, for example, by making the first
connecting conduit 87 communicate with the first discharge channel
88. By so doing, the first mould opens and the corresponding
preform can be extracted.
[0135] The moulds of the second fraction of moulds can be opened in
a completely similar way. It should be noted that the first mould,
like all the other moulds, has an interval of time available within
which to close that is twice that of the traditional case, in which
a single driving hydraulic circuit is provided. In this latter
case, in fact, as a single hydraulic circuit is provided that
drives all the moulds, the closing operation of the first mould
should be completed before the second mould is closed.
[0136] It is possible to provide a number of hydraulic circuits
greater than two. A number of hydraulic circuits that is identical
to the number of moulds can even be provided so as to drive the
latter in a completely autonomous and independent manner from one
another, optimising moulding operations.
* * * * *