INJECTION MOULDING INSTALLATION

INSTALLATION DE MOULAGE PAR INJECTION

English Abstract

The invention concerns an injection moulding installation in which an
injection unit (17) and a clamping unit (1) are so arranged that the transport
direction (16) of the injection unit (17) and the clamping direction of the
tools (3, 5; 4, 6) are at right angles to each other. This arrangement permits
the tools (3, 5; 4, 6), which are laid out in pairs, to operate either
synchronously or alternately with the aid of an appropriate valve (18). The
paired layout of the tools (3, 5; 4, 6) enables the forces exerted upon them
by feed pressure to be compensated and bending moments within the clamping
unit (1) to be avoided.

French Abstract

L'invention concerne une unité de moulage par injection, dans laquelle une unité d'injection (17) et une unité de fermeture (1) sont disposées de sorte que le sens de transport (16) de l'unité d'injection (17) et le sens de fermeture (15) de l'unité de fermeture (1) soient perpendiculaires l'un par rapport à l'autre. Cette disposition permet de faire fonctionner les deux outils (3,5;4,6) agencés sous forme de paires, soit de façon synchronisée, soit en alternance au moyen d'une soupape appropriée (18). L'agencement des outils (3,5;4,6) sous forme de paires permet de compenser les forces exercées par la pression d'alimentation sur les outils et d'éviter la production de moments de flexion à l'intérieur de l'unité de fermeture (1).

Claims

Claims
1. An injection moulding installation for the manufacture
of mould parts from plasticised synthetic material with
at least one dosing and feeding device, as well as with
a closure unit (1) for at least two mould tools
(3,5;4,6) arranged in pairs and having several
cavities, whereby said closure unit of said mould tools
(3,5; 4,6) being arranged in pairs is perpendicular to
the feed direction (16) of the at least one dosing and
feeding device, characterised in that the at least one
dosing and feeding device is an injection unit for
mould tools, said mould tools (3,5; 4,6) being multiple
hot-runner standard mould tools having 48 or more form
cavities and that, to avoid bending moments within or
between the individual tool plates, the closure unit
(1) comprises a distributor plate (2) which is formed
as a fixed machine plate of the injection unit (17).
2. Injection moulding installation according to claim 1,
characterised in that the mould tools (3,5; 4,6) are
arranged in pairs axially symmetrically to the feed
direction (16) of the at least one injection unit (17).
3. Injection moulding installation according to one of
claims 1 or 2, characterised in that the mould tools
(3,5; 4,6) are multiple hot-runner co-injection tools.
4. Injection moulding installation according to one of the
preceding claims, characterised in that the distributor
plate (2) comprises a centrally arranged valve (18) for
regulating the supply of melt to the mould tools (3,5;
4,6).

5. Injection moulding installation according to one of
claims 1 to 4, characterised in that the closure unit
(1) with the at least one injection unit (17) forms a
T-shaped installation.
6. Injection moulding installation according to claim 5,
characterised in that the closure unit (1) with at
least two injection units (17) lying opposite one
another form a cross-like installation.

Description

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PCT/CH97/00235 W0 97/48540
Translation of ~pplic~tion as-filed
An inj ection moulding assembly
The present invention relates to an injection moulding
installation for the manufacture of mould parts of
plasticised synthetic material according to the preamble of
claim 1.
Such injection moulding installations are applied everywhere
today in plastics technology and comprise basically an
injection unit and a closure unit, wherein the injection
units have more or less complicated machines for
plasticising and injecting. The closure units are as a rule
hydraulically or pneumatically operated, are equipped with
exchangeable mould tools and are arranged such that their
plates are perpendicular to the feed direction of the
plasticising device, i.e. they may be opened and closed in
the direction of travel.
In order to increase the production of such mould parts it
has already been variously suggested to so form the closure
units that two or more mould tools simultaneously or
alternately may be charged with the desired quantity of
plastics melt. With these closure units, as is for example
described in US 5,464,579 or US 5,370,523, the plastics melt
centrally is conveyed through at least one of the mould
tools into a distributor block, in order from here to be
supplied to the respective tool plates on the nozzle side.
The supply of melt centrally through a part of the tool
plates requires specially designed mould tools, which makes
the production of the mould parts more expensive.
It is therefore known by way of example from W0 95/08428 to
guide the plastics melt around the mould tools to the
multiple closure unit and to lead it into a middle die
platen. With this, this middle die platen may be
. . .

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PCT/CH97/00235
Transl~tion of ~,-,on~l",cnt ~cc. to Art. 34 2 wo 97/48540
stationarily assembled, or designed displaceable as with the
known multiple closure units, known as tandem machines.
These closure units operating with a laterally displaced
injection unit permit the use of standard tools and thus the
reduction of production costs. Unfortunately it has been
shown that these laterally supplied multiple closure units,
with the application of tools which are suitable for the
simultaneous production of 48 and more mould parts, partly
leak and close more rashly than the centrally supplied
closure units and thus require more intensive maintenance.
In FR 2 294 041 there is described a piston injection
moulding machine in which a vertically arranged piston - in
the following called dosing and feed device - for dosing and
feeding the melt cooperate with a fixed tool clamping plate.
This clamping plate is supported on a base structure and
distributes the injected melt in two flankingly arranged
injection moulding tools having several cavities. Such
piston injection moulding machines are not suitable for the
simultaneous production of 48 and more shell-shaped preforms
made of PET, as are used today in the beverage industry.
These piston injection moulding machines are today only used
for the manufacture of miniature parts. A disadvantage of
these machines is the material loss caused by the branched-
off gating, which is avoided today by using hot-runner
systems.
The general expert technical knowledge for such injection
moulding systems, and in particular the meaning of the
terminology used here, in particular "injection unit",
"machine plate", "tool plate" etc. is known, for example,
from the Plastics Handbook, Saechtling, Carl Hanser
Publishers.

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It is therefore the object of the present invention to
provide a multiple closure unit which can be equipped with
standard tools and which has a higher functional capability,
i.e. with a lower maintenance expense. In particular with
this, proven multiple tools with for example 48 and more
mould cavities may function with operational dependability.
According to the invention this is achieved with an
injection moulding installation according to claim 1 and in
particular by an arrangement of the injection unit and the
closure unit, in a manner such that the feed direction of
the injection unit and the closing direction of the tools
are perpendicular to one another. It has shown to be
particularly important for the construction that the middle
clamping plate stands directly in the feed direction and is
formed as a rigid machine plate. Likewise important is the
arrangement in pairs of the tool plates so that the forces
produced by the injection pressure in each case may be
mutually compensated. With this the whole closure unit
obtains a high mechanical stability and in particular by way
of the injection pressure required for the supply of the
melt, no bending moments are produced within or between the
individual tool plates.
The advantages of the injection moulding machine arrangement

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according to the invention result for the sman skilled in
the art from the geometric construction which is shown in
the figures and which also permits multi-layered mould
parts, in particular by way of proven tools with 48 or more
mould cavities, to be manufactured with operational
dependability and with low wear.
In the following the invention is explained in more detail
by way of embodiment examples and with the aid of the
figures. With this there are shown:
Fig. 1 a view of a closure unit of an injection moulding
installation arranged according to the invention;
Fig. 2 a view of a closure unit of an injection moulding
installation arranged according to the invention
with two injection units;
Fig. 3 a view of a closure unit of an injection moulding
installation arranged according to the invention
with three injection units.
The closure unit 1 shown in Figure 1 comprises centrally a
rigid machine plate which in the following is also called
a distributor plate 2. On both sides of this rigid
distributor plate 2 there is in each case a tool plate
(matrix) 3 rigidly connected to this disributor plate 2. A
movable tool plate (male mould) 5, 6 which belongs to the
respective tool plates is in each case fastened to a movable
machine plate 7, 8. These movable machine plates 7, 8 are
guided on spars and are moved via hydraulic systems 9, 10
which are supported on base plates 11, 12. In the present
figure there is moreover shown a removal system 13 with
which the injected mould parts may be removed from the tool
and may be thrown out onto a transport belt 14. Essential
to the present invention is that the closing direction 15

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is perpendicular to the feed direction 16 of the injection
unit 17. This arrangement permits the tools 3,5; 4,6
arranged in pairs, to be operated either synchronously or
alternately with the help of a suitable valve 18. By way of
this paired arrangement of the tools 3,5; 4,6, the forces
exerted on these tools by the feed pressure compensate and
no bending moments may be produced within the closure unit
1.
The closure unit 1 shown in Figure 2 differs from the
closure unit shown in Figures 1 only in that the rigid
distributor plate 2 (machine plate) is supplied by two
injection units 25 and 26. In order to prevent bending
moments with this arrangement, between the injection units
25, 26 and the rigid machine plate 2 there is provided a
distributor girder 20. With this distributor girder 20 the
plastics melt may be led centrally into the machine plate
2 via feed channels 21, 22, in order from here to be led in
multiple tools 23, 24. By way of the use of several
injection units, multi-layered mouldings may be produced,
these being used nowadays in particular for foodstuffs
packaging and in particular in the drinks industry. It has
been shown that the installation according to the invention
even with several injection units does not render necessary
any additional material expense at the tools, and the whole
closure unit 1 retains its strength depending on shape also
with the application of tools with 48 and more mould
cavities. This permits in particular the application of
standard tools, which are also applied in simple injection
units and here have proven themselves. In a further
formation of this injection moulding installation an
additional tool (not shown) whose closing direction runs in
the direction of supply 34 may be mounted to the rigid
machine plate 2, without at the same time bending moments
being produced on this central machine plate 2.

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The embodiment form of the injection moulding installation
according to the invention, shown in Figure 3 shows a
further formation with three injection units 27, 28, 29. The
feed direction 30, 31, 32 of these injection units again is
perpendicular to the closing direction 33 of the tools
arranged in pairs. With this installation multi-layered
mould parts may be manufactured with operational
dependability and with low wear. Also with this device no
bending moments occur which in the injection moulding
operation could lead to deformations of the components.
It is to be understood that this installation may be further
modified by the man skilled in the art. Thus the mould tools
for example do not need to lie in a plane, but may be
arranged in pairs axially symetrically to the feeding axis.
With such an arrangement several tool pairs may be
distributed about the feeding axis and the individulal tool
pairs which operate synchronously with one another may be
cycled after one another.
. . _

Representative Drawing