Drive arrangement for an injection molding machine

Europaisches Patentamt
(19)
J
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European Patent Office
Office europeen des brevets
(11)
EP
0 427
438
B1
E U R O P E A N PATENT S P E C I F I C A T I O N
(12)
ation and mention
mention
(45) Date of publication
of the grant of the patent:
09.12.1998 Bulletin 1998/50
(51) |nt. CI.6: B29C 4 5 / 6 6
(21) Application number: 90311862.8
(22) Date of filing : 30.1 0.1 990
(54) Drive arrangement for an injection molding machine
Antriebsanordnung fur eine Spritzgiessmaschine
Dispositif d'entraTnement pour une machine a mouler par injection
(84) Designated Contracting States:
AT DE ES FR GB IT NL
(74) Representative:
Singleton, Jeffrey et al
Eric Potter Clarkson,
Park View House,
58 The Ropewalk
Nottingham NG1 5DD (GB)
(30) Priority: 10.11.1989 CH 4062/89
(43) Date of publication of application:
15.05.1991 Bulletin 1991/20
(73) Proprietor: VICKERS INCORPORATED
Troy, Michigan 48007-0302 (US)
(72) Inventor: Stillhard, Bruno
CH-9011 St. Gallen(CH)
(56) References cited:
EP-A- 0 271 588
GB-A- 1 079 286
US-A- 1 880 874
DE-C- 2 252
US-A-1 344156
US-A- 4 755 124
• PATENT ABSTRACTS OF JAPAN, vol. 11, no. 14
(M-553)[2461], 14th January 1987; & JP-A-61 189
859 (JAPAN STEEL WORKS LTD) 23-08-1986
• IDEM
CO
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Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed byXerox (UK) Business Services
2.16.6/3.4
1
EP 0 427 438 B1
Description
The invention relates to a drive arrangement for an
injection molding machine and more particularly, but not
exclusively, the mold plates of an injection molding
machine.
For many years, the majority of injection molding
machines have utilised hydraulic cylinders as drive
means. For several years now, drive motors - particularly electric drives and servomotors - have been
employed for moving the mold mounting plates. In
drives of this kind, use is made of an electric servomotor
which runs at relatively high speed, the rotary movement of the motor being converted into linear movement
through the agency of a ball-spindle or ball-screw that
runs in a ball-spindle or ball-screw bearing.
Drives of this kind have been shown and described
in various publications, e.g. EP-A-0 271 588, EP-A-0
281 637 and EP-A-0 277 249. In expert circles, it has
thus been assumed that the use of motors - especially
electric motors - as drive means for injection molding
machines necessarily presupposes the use of a screw
or ball-spindle as a linear drive. The known drives enjoy
many advantages over the hydraulic drives. However,
they are exceptionally prone to wear, while the high
rotation speeds of ball-spindles lead to relatively high
moments of rotational inertia and corresponding difficult
control and drive characteristics. Further to these disadvantages, ball-spindle drives of this kind are overly complicated and expensive to manufacture, and they cannot
be protected from environmental influences - e.g. by
enclosing them - if only because the ball-spindle has to
be provided with a screw thread over its entire length
and, moreover, because it runs in a ball-spindle bearing
on the mold mounting plate.
In JP-A-61 -189859 there is disclosed clamping
apparatus for a vertical injection molding machine in
which mold plates are moved relative to each other by a
linear drive in the form of rack and pinion means, with
the rack having two opposed pinions. Each pinion is
driven by a brake-equipped reversible electric motor or
a hydraulic motor. The motors are energised and deenergised by limit switches with consequential lack of fine
control. More particularly, this arrangement suffers from
the following disadvantages :1. Precise final positioning of the mold plates is difficult to achieve.
2. Limited acceleration and deceleration control
during mold plate clamping operation.
3. Requires slower movements to ensure final
clamp position is attained without overshoot which
can be damaging.
4. During the acceleration phase, torque is not controlled to allow optimum acceleration profiles. Thus
acceleration has to be limited to avoid peak G loading on the machine frame and mounts.
5
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The object underlying the invention is to avoid the
disadvantages of the known art, and in particular to utilize this knowledge in the production of a drive arrangement for an injection molding machine, namely an
arrangement which can be employed as a general-purpose means of executing the various sequences of
movement at different drive locations on the injection
molding machine, while at the same time developing
high forces, attaining high speeds and being economical to manufacture and maintain.
In more detail the object of the invention may be
stated as the provision of an arrangement in which the
principal components of a rack-type drive are isolated
from contaminants in order to permit their use at the
aforesaid, different drive locations, whilst still providing
the aforesaid advantages of force, speed and economy.
According to the present invention there is provided
an injection moulding machine comprising a base
frame, two mold plates mounted on said base frame for
relative movement between a mold open position and a
mold closed position, and drive means mounted on said
base frame and operable to move and/or lock at least
one of said mold plates, the drive means being in the
form of linear drive means comprising at least one
motor, at least one set of gears driven by said motor,
and a toothed rack connected to said at least one mold
plate and in mesh with at least one gear of said set of
gears, whereby the rack and said at least one mold
plate are driven in operation of the motor, characterised
in that the motor of the drive means is a servomotor, and
in that the rack has a substantially circular cross-section
with one or more series of teeth provided only over a
portion of the length of said rack, and the rack is slidably
mounted in bearings on each side of the toothed portion, and in that the machine further comprises a casing
with the gears and at least a portion of the rack
arranged inside said casing, with the rack being led
through a wall of said casing, the rack being supported
in a bearing in the wall of the casing, and the bearing
being provided with a seal.
By utilizing a toothed rack drive known per se, in
conjunction with a servomotor also known per se, not
only is the design configuration of the drive simplified in
a wholly surprising way, but the control and drive characteristics of the injection molding machine are decisively improved, also in a way that could not be
expected. For example, the moment of rotational inertia
is decisively reduced because the rack executes linear
movements, as well as by virtue of the necessary - i.e.
large - reduction ratio provided by the gears between
the drive motor and the rack. Reducing the rotational
inertia in this way reduces wear and improves the control characteristics, as well as enabling higher moldmovement accelerations to be achieved.
Further decisive advantages also result, including
low manufacturing costs and drive arrangements which
entail substantially less wear than drives employing ballspindles.
3
EP 0 427 438 B1
The invention makes it possible to adopt an
enclosed style of construction, in which the rack can be
led into a gear casing via a device such as a throughbearing, and sealed by means of a conventional O-ring
or lip-type seal.
5
An arrangement possessing exceptional mechanical stiffness results if the rack is provided with series of
teeth on at least two sides which are preferably opposite
each other, and if two drive gearwheels are provided.
Such an arrangement enables the driving force to be 10
introduced into the rack on both sides, and this leads to
lower tooth loads and less tooth wear, as well as to an
improvement in the rack movement characteristics.
The drive arrangement according to the invention is
particularly suitable for generating high locking forces if 15
the driving gearwheels propel the rack from at least two
sides, via separate sets of gears and preferably through
the agency of separate drive motors.
A toggle-action force-boosting device is usually provided for generating the locking force. Like the motor, 20
this device can act on either the rack or the gears, as will
be known to an expert, who will regard this as conventional.
Illustrative embodiments of the invention will now
be described in greater detail, by way of example, with 25
reference to the drawings in which :Figure 1 shows a schematic representation of an
injection molding machine with the features of the
invention,
Figure 2 shows a schematic representation of various components of a drive arrangement,
Figure 3 shows a modified illustrative embodiment
of a drive arrangement,
Figure 4 shows a section through the rack along
line IV-IV in Figure 2, and
Figure 5 is a side view, partly in section, showing in
greater detail a toggle arrangement that can be
used in the embodiments of Figure 1 or 3,
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35
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Figure 1 shows an injection molding machine 1,
possessing a fixed mold mounting plate 2 and a movable mold mounting plate 3. The mold mounting plates 2,
3 are mounted on an axis 4, in a manner such that on
displacing a toothed rack 5, their positions relative to 45
each other can be varied, and this movement causes a
mold, clamped in the plates but not indicated in the
drawing, to be opened or closed in a known manner.
The injection molding machine 1 is provided with a
frame portion 6 (represented only schematically), a feed so
device 7 for the plastics material and a control unit 8. A
casing 9, mounted on the frame portion 6, contains an
electric servomotor 10 and a set of gears 11, arranged
in a manner such that the rack 5 can be caused to execute linear movements. Furthermore, the rack 5 is con- ss
figured as a cylindrical bar which is provided with a
series of teeth 12 over only a certain portion of its length
on the left-hand end as seen in Figure 1. The length of
3
4
the series of teeth depends on the distance through
which it is desired that the movable mold mounting plate
3 should be driven forward. The rack 5 is supported at
both ends in bearings 13, 14 which permit sliding. In
addition, the casing 9 is provided with a cylinder-like
protrusion 14a which receives and protects the rack
when it is displaced to the leftward limit of its travel.
The casing 9 is closed on all sides, and protects the
gears 11 and the teeth 12 from dirt accretion and damage. At the same time, the slide-bearing 13 acts as a
seal to prevent dirt ingress and leakage of grease or
some other lubricant from the casing 9.
Figure 2 shows the mounting of a rack 5 in two
slide-bearings 13 and 14, a Teflon scraper/sealing ring
15 being fitted in front of the slide-bearing 13 so as to
guarantee dependable sealing.
The cylindrical rack 5 is provided with a pair of diametrically opposed flats 30,31 (Figure 4) formed with
respective series of teeth 12a, 12b, with which the two
drive gearwheels or pinions 16, 17 associated with the
sets of gears 11 mesh. Because the rack 5 is mounted
in bearings at both ends, any tendency for it to tilt in the
bearings 13, 14 is eliminated and, moreover, wear on
the series of teeth 12a, 12b is reduced. In this embodiment, both drive gearwheels 16, 17 are driven through
the sets of gears 11 by the common servomotor 10. The
servomotor 10 is provided with a power supply apparatus 24 as indicated diagrammatically. This power supply
apparatus 24 receives feedback signals via a return line
18 from a tachometer (not represented) in the servomotor 10, via a return line 19 from a position transmitter 21
for monitoring the rack position, and via a return line 20
a force signal from a force transducer 22 for monitoring
the locking force as between the plates 2 and 3.
The design and constructional details of servo and
control drives of this kind are known, and are conventional.
Figure 3 shows an alternative embodiment in which
two servomotors 10a, 10b are provided, each driving a
drive gearwheel 16, 17 which is assigned to it, in each
case via a separate set of gears 11a, 11b. The power
supply apparatus 24 for the two servomotors 10a, 10b is
triggered to function in a manner such that the two drive
gearwheels 16,17 rotate in synchronism, this being
accomplished by providing position feedback signals via
the return lines 18a, 18b and by utilizing a pulse converter 23. The arrangement shown makes it possible, in
particular, to transmit high forces and to achieve high
accelerations.
The rack 5 shown in Figure 3 is of cylindrical configuration, similar to the rack shown in Figure 2, and is provided with series of teeth 12a, 12b on both sides.
Furthermore, instead of a single rack 5, it will be
appreciated that two or more racks could be provided,
and that they could be driven in common, e.g. by separate gearwheel 16, 17 for each, or by common gearwheels which would be designed to be of an appropriate
width.
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EP 0 427 438 B1
Figure 5 illustrates in greater detail the relationship
between the fixed and movable plates 2,3 and the rack
5 and associated drive. In addition, these Figures illustrate how a toggle mechanism is used to lock the movable plate 3 relative to the fixed plate 2 during the actual
molding operation, the toggle mechanism being driven
by the rack 5 rather than via an hydraulic actuator or ball
screw as is conventional.
The movable plate 3 is mounted on four tie rods 25
secured at one end to the fixed plate 2. The toggle
mechanism, indicated generally at 26, comprises an
upper portion 27 and a lower portion 28, each portion
being identical and attached to the upper and lower
sides, respectively, of the rack 5 via blocks 29. Each
block 29 is provided with a fixed link 31 to which is pivotally attached one end of a first movable link 32, the
other end of which is pivotally attached intermediate the
ends of a second movable link 33. One end of the movable link 33 is pivotally attached to a lug 34 carried by a
C-shaped support bracket 35 attached to the machine
frame 6. The other end of the second movable link 33 is
pivotally attached to one end of a third movable link 36,
the other end of which is pivotally attached to a lug 37
carried by the movable plate 3. It will be appreciated that
Figure 5 illustrates in the upper left-hand half the toggle
mechanism in the extended, lock-out position, and in
the lower left-hand half illustrates the toggle in the
retracted position.
The untoothed portion of the rack 5 extends
through an aperture in the support bracket 35 and is
provided, as already described above, with two
opposed series of teeth 12a and 12b with which mesh
the respective pinions 16 and 17. With the injection
moulding machine in the open position, i.e. with the
movable plate 3 retracted from the fixed plate 2, the toggle mechanism is in the folded or retracted position
shown in the lower left-hand portion of Figure 5. When it
is required to perform a molding operation, the servomotor 10 is energised and the rack 5 is moved to the
right in the manner already described above. As the
rack 5 moves to the right, the two fixed links 31 act on
the movable links 32,33 and 36 in a manner to unfold
them, resulting in the second and third movable links 33
and 36 finally being substantially in line with each other
in which position they are locked out by the action of the
fixed link 31 and first movable link 32, further movement
of the rack 5 serving to build up the required locking
force as between the plates 2 and 3.
Claims
1.
An injection moulding machine (1) comprising a
base frame (6), two mold plates (2,3) mounted on
said base frame (6) for relative movement between
a mold open position and a mold closed position,
and drive means (5,10,11) mounted on said base
frame (6) and operable to move and/or lock at least
one of said mold plates (2,3), the drive means being
6
in the form of linear drive means comprising at least
one motor (10), at least one set of gears (1 1) driven
by said motor (10), and a toothed rack (5) connected to said at least one mold plate (2,3) and in
mesh with at least one gear (16,17) of said set of
gears (11), whereby the rack (5) and said at least
one mold plate are driven in operation of the motor,
characterised in that the motor of the drive means is
a servomotor, and in that the rack (5) has a substantially circular cross-section with one or more
series of teeth (12a, 12b) provided only over a portion of the length of said rack (5), and the rack (5) is
slidably mounted in bearings (13,14) on each side
of the toothed portion, and in that the machine further comprises a casing (9) with the gears (16,17)
and at least a portion of the rack (5) arranged inside
said casing, with the rack being led through a wall
of said casing, the rack (5) being supported in a
bearing (13,14) in the wall of the casing (9), and the
bearing being provided with a seal (15).
5
10
is
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2.
A machine as claimed in claim 1, wherein said rack
(5) is provided with a series of teeth (12a, 12b) on at
least two sides, and wherein two drive gears
(16,17) of said set of gears (11) are in mesh with
respective ones of said series of teeth on said rack.
3.
A machine according to claim 2, wherein said rack
(5) is provided with series of teeth (12a, 12b) on two
opposed sides.
4.
A machine as claimed in claim 2 or 3, wherein said
drive gears (16,17) are driven via separate sets of
gears (11 a, 11b).
5.
A machine as claimed in claim 4, wherein said separate sets of gears (1 1a, 11b) are driven through the
agency of separate drive servomotors (10a, 10b).
40 6.
A machine as claimed in any of the preceding
claims, wherein said drive means comprises at
least two racks (5) driven by respective sets gears.
7.
A machine as claimed in any of the preceding
claims, wherein the or each servomotor (10) is
energised from a power supply apparatus which
receives as feedback signals a signal from a position transducer to monitor the position of said rack
(5), and a force signal to monitor the locking force
between said mold plates (2,3).
8.
A machine as claimed in any of the preceding
claims, wherein one of said mold plates is fixed (2)
and the other (3) of said mold plates is moveable
relative to said one mold plate.
9.
A machine as claimed in any of the preceding
claims, wherein toggle means (26) is provided for
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EP 0 427 438 B1
releasably locking said mold plates (2,3) in the mold
closed position, the toggle means being mounted
between said rack (5), said base frame (6), and said
at least one mold plate (3).
10. A machine as claimed as claimed in claim 5, and
any of claims 6 to 13 when appended thereto,
wherein the power supply apparatus (24) for the
two servo motors (10a, 10b) is triggered to function
in a manner such that the two drive gear wheels
(16,17) rotate in synchronism, by providing position
feedback means operable to sense the position of
the rack (5) and provide position feedback signals
to pulse converter means (23) the output of which
controls the power supply apparatus (24).
Zahnstange stehen.
2.
3.
Maschine nach Anspruch 2, wobei die Zahnstange
(5) mit Zahnreihen (12a, 12b) an zwei entgegengesetzten Seiten versehen ist.
4.
Maschine nach Anspruch 2 oder 3, wobei die
Antriebszahnrader (16,17) uber getrennte Satze
von Zahnradern (1 1a, 11b) angetrieben sind.
5.
Maschine nach Anspruch 4, wobei die getrennten
Satze von Zahnradern (1 1a, 11b) mittels getrennter
Antriebs-Servomotoren (10a, 10b) angetrieben
sind.
6.
Maschine nach einem der vorangehenden Ansprtiche, wobei die Antriebseinheit mindestens zwei
jeweils durch Zahnradsatze angetriebene Zahnstangen (5) umfaBt.
5
10
15
Patentanspruche
1.
SpritzgieBmaschine (1) mit einem Basisrahmen (6),
zwei am Basisrahmen (6) zur Relativbewegung 20
zwischen einer Formoffungsposition und einer
7.
FormschlieBposition angebrachte
Formplatten
(2,3) sowie am Basisrahmen (6) angebrachten und
zum Verschieben und/oder SchlieBen mindestens
einer der Formplatten (2,3) betatigbaren Antriebs- 25
mitteln (5,10,11), wobei die Antriebsmittel bzw. die
Antriebseinheit in Form einer Linearantriebseinheit
mit mindestens einem Motor (10), mindestens
einem vom Motor (1 0) angetriebenen Zahnradsatz
(11) sowie einer mit der mindestens einen Form- 30
8.
platte (2,3) verbundenen und in Eingriff mit mindestens einem Zahnrad (16,17) des Zahnradsatzes
(11) stehenden Zahnstange (5) vorliegen, wobei
die Zahnstange (5) und die mindestens eine Formplatte beim Betrieb des Motors angetrieben werden 35
9.
bzw. sind,
dadurch gekennzeichnet, daB der Motor der
Antriebseinheit ein Servomotor ist, und daB die
Zahnstange (5) einen im wesentlichen kreisformigen Querschnitt hat, wobei eine Oder mehr Zahnrei- 40
hen (12a, 12b) nur uber einen Teil der Lange der
Zahnstange (5) vorgesehen ist/sind und die Zahnstange (5) gleitfahig in Lagern (13,14) auf jeder
10.
Seite des verzahnten Teils angebracht ist, und daB
die Maschine des weiteren ein Gehause (9) auf- 45
weist, wobei die Zahnrader (16,17) und mindestens
ein Teil der Zahnstange (5) innerhalb des Gehauses angeordnet sind, die Zahnstange durch eine
Wand des Gehauses gefuhrt ist, die Zahnstange
(5) in einem Lager (13,14) in der Wand des Gehau- 50
ses (9) gelagert ist und das Lager mit einer Dichtung (1 5) versehen ist.
Maschine nach Anspruch 1, wobei die Zahnstange
(5) mit einer Zahnreihe (12a, 12b) an mindestens
zwei Seiten versehen ist, und (wobei) zwei
Antriebsrader (16,17) des Satzes von Zahnradern
(11) in Eingriff mit jeweiligen Zahnreihen an der
8
55
5
Maschine nach einem der vorangehenden Ansprtiche, wobei der oder jeder Servomotor (10) von
einem Energieversorgungsgerat mit Energie versorgt wird, das als Riickkopplungssignale ein
Signal von einem Positionswandler zum Uberwachen bzw. Kontrollieren der Position der Zahnstange (5) sowie ein Kraftsignal zum Uberwachen
der SchlieBkraft zwischen den Formplatten (2,3)
erhalt.
Maschine nach einem der vorangehenden Ansprtiche, wobei eine der Formplatten (2) feststehend
und die andere der Formplatten (3) relativ zu der
einen Formplatte bewegbar bzw. verschiebbar ist.
Maschine nach einem der vorangehenden Ansprtiche, wobei ein Kniehebelmittel (26) zum losbaren
VerschlieBen der Formplatten (2,3) in der FormschlieBposition vorgesehen ist, wobei das Kniehebelmittel zwischen der Zahnstange (5), dem
Basisrahmen (6) und der mindestens einen Formplatte (3) angebracht ist.
Maschine nach Anspruch 5 und einem der Ansprtiche 6 bis 13, soweit davon abhangig, wobei das
Energieversorgungsgerat (24) fur die beiden Servomotoren (10a, 10b) derart getriggert bzw. gesteuert
ist, daB es auf eine Weise funktioniert, daB sich die
beiden Antriebszahnrader (16,17) synchron zueinander drehen, indem Positions- Riickkopplungsmittel vorgesehen sind, die so betatigbar sind, daB sie
die Position der Zahnstange (5) abgreifen und die
Positions-Riickkopplungssignale an eine Impulswandlereinrichtung (23) liefern, deren Ausgang(ssignal) das Energieversorgungsgerat (24) steuert.
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EP 0 427 438 B1
Revendications
vomoteurs d'entramement (10a, 10b) separes.
1. Une machine a mouler par injection (1) comprenant
un cadre de base (6), deux plaques de moulage
(2,3) montees sur ledit cadre de base (6) afin 5
d'effectuer un mouvement relatif entre une position
d'ouverture de moule et une position de fermeture
de moule et des moyens d'entramement (5, 10, 11)
montes sur ledit cadre de base (6) et susceptibles
de fonctionner pour deplacer et/ou verrouiller au 10
moins I'une desdites plaques de moule (2, 3), les
moyens d'entramement etant realises sous la
forme de moyens d'entramement lineaire, comprenant au moins un moteur (10), au moins un jeu de
roues dentees (11) entrame par le moteur, et une 15
cremaillere dentee (5) reliee a au moins une des
plaques de moulage (23) et engrenant avec au
moins une roue dentee (16, 17) du jeu de roues
dentees (11), dans lequel la cremaillere (5) et au
moins une plaque de moulage sont entramees lors- 20
que le moteur est en fonctionnement, caracterisee
en ce que le moteur des moyens d'entramement
est un servomoteur et en ce que la cremaillere (5) a
une section transversale sensiblement circulaire
avec une ou plusieurs series de dents (12a, 12b) 25
prevues seulement sur une partie de la longueur de
ladite cremaillere (5), et la cremaillere (5) est montee a coulissement dans des paliers (13,14) sur
chaque cote de la partie dentee, et en ce que la
machine comprend en outre un carter (9) compor- 30
tant les roues dentees (16, 17) et au moins une partie de la cremaillere (5) agencee a I'interieur dudit
carter, la cremaillere etant passee a travers une
paroi dudit carter, la cremaillere (5) etant supportee
dans un palier (13,14) prevu dans la paroi du carter 35
(9) et le palier etant dote d'un joint d'etancheite
(15).
2.
Une machine selon la revendication 1, dans
laquelle ladite cremaillere (5) est dotee d'une serie
de dents (12a, 12b) sur au moins deux cotes et
dans laquelle deux roues dentees d'entramement
(16, 17) dudit jeu de roues dentees (1 1) engrenent
avec des dents respectives appartenant a ladite
serie de dents sur ladite cremaillere.
3.
Une machine selon la revendication 2, dans
laquelle ladite cremaillere (5) est dotee d'une serie
de dents (12a, 12b) sur deux cotes opposes.
4.
Une machine selon la revendication 2 ou 3, dans
laquelle lesdites roues dentees (16, 17) sont entraTnees via des jeux separes de roues dentees (1 1a,
11b).
5.
Une machine selon la revendication 4, dans
laquelle lesdits jeux separes de roues dentees
(1 1a, 11b) sont entrames par I'intermediaire de ser-
10
40
45
50
55
6
6.
Une machine selon I'une quelconque des revendications precedentes, dans laquelle lesdits moyens
d'entramement comprennent au moins deux cremailleres (5) entramees par des jeux de roues dentees respectifs.
7.
Une machine selon I'une quelconque des revendications precedentes, dans laquelle le ou chaque
servomoteur (10) est actionne depuis un dispositif
d'alimentation en puissance recevant, a titre de
signaux de retroaction, un signal depuis un transducteur de position, dans le but de surveiller la
position de ladite cremaillere (5), et un signal de
force, destine a surveiller la force de verrouillage
entre lesdites plaques de moulage (2, 3).
8.
Une machine selon I'une quelconque des revendications precedentes, dans laquelle I'une desdites
plaques de moulage est fixe (2) et I'autre (3) desdites plaques de moulage est deplagable par rapport
a ladite premiere plaque de moulage.
9.
Une machine selon I'une quelconque des revendications precedentes, dans laquelle des moyens a
genouillere (26) sont prevus afin de verrouiller de
fagon desolidarisable lesdites plaques de moulage
(2,3) dans la position de fermeture de moule, les
moyens a genouillere etant montes entre ladite cremaillere (5) ledit cadre (6) et ladite au moins une
plaque de montage (3).
10. Une machine selon la revendication 5, et I'une des
revendications 6 a 13 qui en dependent, dans
laquelle le dispositif d'alimentation en puissance
(24) destine aux deux servomoteurs (10a, 10b) est
declenche pour fonctionner d'une maniere telle que
les deux roues dentees d'entramement (16, 17)
tournent en synchronisme en prevoyant des
moyens de retroaction de position susceptibles de
fonctionner pour apprehender la position de la cremaillere (5) et fournir des signaux de retroaction de
position a des moyens de conversion en impulsions
(23) dont le signal de sortie commande le dispositif
d'alimentation en puissance (24).
EP 0 427 438 B1
EP 0 427 438 B1
EP 0 427 438 B1
EP 0 427 438 B1
10