(19)
(11)EP 3 363 612 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
24.06.2020 Bulletin 2020/26

(21)Application number: 17156782.9

(22)Date of filing:  17.02.2017
(51)International Patent Classification (IPC): 
B29C 45/28(2006.01)
B22D 17/20(2006.01)
B29C 45/27(2006.01)

(54)

HOT RUNNER INJECTION NOZZLE AND ACTUATOR FOR INJECTION MOLDING DEVICE

HEISSKANALEINSPRITZDÜSE UND AKTUATOR FÜR SPRITZGIESSVORRICHTUNG

BUSE D'INJECTION À CANAUX CHAUFFANTS ET ACTIONNEUR POUR DISPOSITIF DE MOULAGE PAR INJECTION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
22.08.2018 Bulletin 2018/34

(73)Proprietor: Otto Männer GmbH
79353 Bahlingen a.K. (DE)

(72)Inventor:
  • Spuller, Swen
    79362 Forchheim (DE)

(74)Representative: Rentsch Partner AG 
Bellerivestrasse 203 Postfach
8034 Zürich
8034 Zürich (CH)


(56)References cited: : 
EP-A1- 1 316 404
DE-A1-102008 028 577
US-A- 5 375 994
US-A1- 2006 233 911
EP-A2- 0 911 134
JP-A- H04 320 820
US-A- 5 423 672
  
      
    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).


    Description

    FIELD OF THE INVENTION



    [0001] The present invention relates to a hot runner injection nozzle for an injection molding device and an actuator for such an injection nozzle, as well as a method to operate the injection nozzle.

    BACKGROUND OF THE INVENTION



    [0002] WO15150501A1 was first published in October 2015 in the name of the same applicant as the herein disclosed invention. It is directed to a hot runner nozzle for side gating in a hot runner injection molding apparatus. A nozzle that is connectable to a melt outlet opening of a hot runner manifold. It comprises a nozzle flange portion, a nozzle body portion and a nozzle bridge portion. The nozzle bridge portion has at least two adjacently arranged nozzle tip sections. At least two valve pins are coupled to a valve pin actuating device which is moveable back and forth along a first axis. The at least two valve pins are moveable along a second axis which is arranged at an angle to the first axis. The nozzle tip sections are connected adjacent to the nozzle body portion and separated by a nozzle bridge separator which is designed so as to accommodate movements of the nozzle tip sections.

    [0003] DE102012211141A1 was first published in January 2014 in the name of HFT GmbH. It is directed to nozzle device which has a central channel branched out into two side channels which comprises outlet openings for connecting to injection molds. Heating devices are provided for the side channels, respectively. The heating devices are separately adjustable. The heating devices are arranged at circumferences of the respective side channels and surrounded by a shell. The side channels are equipped with respective temperature sensors which are arranged adjacent to the outlet openings.

    [0004] US2008152752A was first published in June 2008 in the name of Mold Masters Ltd. It is directed to an injection molding apparatus which includes an injection manifold having an inlet and a melt channel. The manifold melt channel branches to a plurality of melt channel outlets. A hot runner injection nozzle includes an axial melt channel extending along a central axis and communicating with one of the manifold melt channel outlets. The nozzle further includes at least two angled melt channels disposed at an angle to the central axis. At least two nozzle tips are provided, and each includes a nozzle tip melt channel in communication with one of the angled melt channels. A valve pin is disposed at least partially within the axial melt channel coaxially with the central axis and movable within the axial melt channel. Lateral valve pins movable within the nozzle tip melt channels are disposed at an angle to the valve pin. Linkage elements continuously connect the lateral valve pins to the valve pin. Axial movement of the valve pin is transmitted through the linkage elements to the lateral valve pins to open and close communication between the nozzle tip melt channels and the lateral mold gates.

    [0005] US2006233911A was first published in October 2008 in the name of the same applicant as the herein disclosed invention. US'911 is directed to an injection molding nozzle with a nozzle head including at least one discharge opening. A closure element for closing the discharge opening is movably supported in the nozzle head in order to control the supply of melt material to a communication opening in an injection mold. The closure element is operable by a drive mechanism provided with a short stroke actuating means for displacing the closure element in a direction opposite to the closing direction of the closure element by a predetermined short distance so as to automatically retract the closure element by the predetermined short distance when it is no longer biased by the actuating means in the closing direction.

    [0006] US2003099735A was first published in May 2003 in the name of Yudo Co. Ltd. It is directed to a multi-position control cylinder for hot runners of injection molding machines. This multi-position control cylinder has a multi-stage hole formed in a unit body, a first cylinder seated in the lower part of the multi-stage hole, and a first piston set in the first cylinder. In addition, a second cylinder is seated in the multi-stage hole at a position above the first cylinder, with a second piston set in the second cylinder. A valve pin is coupled to the second piston using a valve pin coupling member such that the valve pin extends downward from the second piston while passing through the first piston, with the lower portion of the valve pin inserted into the upper portion of the first piston. An anti-vacuum gap is formed between the first piston and the valve pin coupling member. A cylinder head covers the top of the multi-stage hole at a position above the second piston.

    [0007] WO0074920 was first published in December 2000 in the name of Husky Injection Molding Systems Ltd. It is directed to an injection nozzle having a valve stem which is mounted in a nozzle body. The valve stem is moving from an open position retracted from the injection orifice permitting the flow of resin to the mold cavity, to a closed position blocking the injection orifice and preventing the flow of resin to the mold cavity and to an advanced position within the gate nub area to assist in the ejection of a molded part and clear the gate nub area.

    [0008] US5423672 in the name of Gordon Edward was granted on 13 June 1995 and discloses a ring gating valve arrangement. The ring gating valve arrangement is provided with a multi-piston servo arrangement which enables a specially configured pin to be stepwisely reciprocated back and forth within a molding device. The pin is formed with a land at one end which is dimensioned and shaped to produce the required aperture. The pin further features a channel structure which includes an annular recess adapted to permit plastic to flow into the center of the mold cavity area when the pin is thrust to a predetermined location. After the cavity is filled with hot plastic, the pin is retracted to a position wherein the annular recess is located within a removable gate bushing and the shaped land is pulled up until it is appropriately located in the mold cavity area. As the injected plastic cools and solidifies, the shaped land acts as the aperture molding pin and forms a clean aperture in the molded part. After solidification, the pin is retracted and the mold is opened to permit the molded part to be ejected.

    [0009] EP0911134A2 was first published on 28 April 1999 in the name of Mold-Masters Limited and discloses a valve gated multi-cavity injection molding apparatus for five layer molding having actuating mechanisms for reciprocating elongated valve members between four different positions. Each actuating mechanism has a front and a rear aligned cylinders, a first piston connected to the head of one of the valve members in the front cylinder and second and third pistons in the rear cylinder. The third piston has a stem portion which extends forwardly through the second piston into the front cylinder. Hydraulic pressure from four hydraulic lines connected to each actuating mechanism reciprocates each elongated valve member between the different positions. In the first closed position, the front end of the valve member is seated in the gate. In the second position, the front end of the valve member is retracted sufficiently to allow an initial amount of PET to flow from an outer annular melt channel through the gate. Then the valve member is retracted further to a third position to allow simultaneous flow of the PET and a barrier material from an inner annular melt channel. Then the valve member is retracted to a fully open position which allows the simultaneous flow of PET from a central melt channel. When the cavity is almost filled, the valve member returns briefly to the second position for filling before returning to the closed position for ejection.

    [0010] EP1316404A1 was first published on 4 June 2003 in the name of Yudo Co., Ltd. and discloses A multi-position control cylinder for hot runners of injection molding machines is disclosed. This multiposition control cylinder has a multi-stage hole formed in a unit body, a first cylinder seated in the lower part of the multi-stage hole, and a first piston set in the first cylinder. In addition, a second cylinder is seated in the multi-stage hole at a position above the first cylinder, with a second piston set in the second cylinder. A valve pin is coupled to the second piston using a valve pin coupling member such that the valve pin extends downward from the second piston while passing through the first piston, with the lowerportion of the valve pin inserted into the upper portion of the first piston. An anti-vacuum gap is formed between the first piston and the valve pin coupling member (8). A cylinder head covers the top of the multi-stage hole at a position above the second piston.

    [0011] DE102008028 577A1 was published on 24 December 20018 28 April 1999 in the name of Mold-Masters Limited and discloses an injection molding apparatus. The injection molding apparatus includes a manifold having a manifold melt channel for receiving a melt stream of moldable material under pressure and at least one nozzle having a nozzle melt channel in fluid communication with the manifold melt channel. A primary actuator is connected to the valve pin. A nozzle locator piece is connected to the nozzle for mating with a side plate to locate the nozzle with respect to the mold gate. A secondary actuator may be provided intermediate the main actuator and the valve pin bushing. The secondary actuator serves to move the valve pin 6S from the fully closed position to an intermediate closed position wherein the forward-most end of the valve pin is slightly retracted out of the mold gate while still serving to close or shut-off the melt channels.

    [0012] US5,375,994 was published on 27 December on behalf of Otto Manner. Disclosed is a pin closure nozzle for injection molding molds that has several working pistons acting on the same closure pin. These working pistons are arranged on a common throughgoing piston rod. Each piston rides in its own chamber and the piston rod passes through and is slidingly guided in openings in the chamber floors. The pistons are fixed on the piston rod with the aid of spring rings or Seeger rings.

    [0013] The injection nozzles and their actuators known from the prior art often are not reliable for precise side injection of plastic material into a mold cavity. One problem results from the fact that the position of the closure element (valve pin) is often not defined and therefore may be wrong resulting in an increased risk of total loss of the thereto related mold. The problem results from the fact that the valve pin may still reach into the cavity of a thereto connected mold when wrong positioned thereby damaging the mold. For secure operation it is often advantageous that the valve pin is in a slightly rearward position not reaching into the cavity. This especially counts for side gating injection nozzles.

    SUMMARY OF THE INVENTION



    [0014] One aspect of the invention is directed to a hot runner injection nozzle in accordance with appended claim 1 for an injection molding device allowing to overcome the above described problem. A further aspect of the invention is directed to a method for operating the injection nozzle in accordance with the appended claim 19.

    [0015] The injection nozzle comprises a nozzle head including at least one discharge opening for injecting pressurized melted plastic material into a mold cavity of a thereto interconnected injection mold and forming therein a molded body. Furthermore the injection nozzle comprises at least one positively controlled closure element (valve pin) movably supported in the nozzle head for closing a communication opening in the thereto connected injection mold.

    [0016] An actuator cylinder is interconnected to the closure element. It comprises a cylinder housing in which a first piston is arranged. The first piston is interconnected to the at least one closure element and is arranged movable between a first position in which the closure element is fully closed and a second position in which the closure element is fully open.

    [0017] A second piston is directly or indirectly interconnectable to the closure element as well. It is arranged movable between a third position in which the second piston is not interconnected to the closure element and a fourth position in which the movement of the closure element is limited by the second piston in an intermediate position between the fully opened and the fully closed position. In this position it can be avoided that the closure element protrudes into, respectively above the communication opening in an unwanted manner. Thereby it can be effectively avoided that damage of the closure element occurs due to inappropriate positioning. Depending on the mold design the first and the second piston can be arranged in the same or spaced apart in a different housing. The first piston and the second piston each comprise an active surface, wherein the active surface of the first piston preferably is smaller than the corresponding active surface of the second piston, such that when pressurized with the same pressure the second piston has priority over the movement of the first piston. Thereby it can be avoided that the first piston dominates the second piston in an inappropriate manner whereby misalignment of the closure element would become possible.

    [0018] The second piston when in the fourth position directly interacts with the first piston in that it limits the movement of the first piston. Thereby the closure element remains locked with respect to its closing direction in the intermediate position. The second piston can be at least in the fourth position interconnected to the first piston, e.g. by a bushing as will be described hereinafter in more detail.

    [0019] To reduce the outer size of the actuator and to harmonize the outer diameter of the second piston with respect to the first piston, the second piston comprises a first part and a second part which are interconnected to each other e.g. by the bushing. In a variation the diameter of the first piston and the diameter of the first and the second part of the second piston deviate from each other by a maximum of 10 mm. The first and the second piston can be - despite to their different active surfaces - arranged in the same outer housing having an in general constant outer diameter.

    [0020] The first and the second piston are preferably arranged in the same cylinder housing. However, if necessary e.g. due to space saving reasons, the cylinder housing can comprise several parts housing the first or the second piston. Alternatively or in addition the cylinder housing can at least partially be integrated in an injection mold, i.e. forming part thereof.

    [0021] Good results can be achieved when the first piston delimits with respect to the cylinder housing a first fluid chamber and a second fluid chamber and the second piston delimits with respect to the cylinder housing a third fluid chamber and a fourth fluid chamber, wherein
    1. (a) the first fluid chamber, when pressurized by a fluid, causes the first piston to go to the first position;
    2. (b) the second fluid chamber when pressurized by a fluid causes the first piston to go to the second position; and
    3. (c) the third fluid chamber (14) when pressurized by a fluid causes the second piston to go to the third position;
    4. (d) the fourth fluid chamber (15)when pressurized by a fluid causes the second piston (8) to go to the fourth position.


    [0022] When the second piston comprises a first and a second part (section) the third as well as the fourth chamber correspondingly comprise two segments. Each pair is preferably directly functionally interconnected to each other e.g. by a thereto related connection channel. An advantageous arrangement can be achieved when the connection channel is arranged in the second piston.

    [0023] The closure element and the first piston are preferably interconnected to each other by a drive shaft directly or indirectly. The closure element and the drive shaft can be arranged in the same direction or at an angle to each other. In a special arrangement the drive shaft is coaxially in line with the closure element.

    [0024] In case of an angled arrangement of the injection nozzle the invention provides in one aspect an improved cam mechanism which is described hereinafter in more detail in accordance with Figure 3. The cam mechanism is considered to be in individual inventive concept and can be used with different actuators. It is therefore reserved to file one or more divisional patent applications directed to it.

    [0025] A method for operating an injection nozzle according to the invention normally comprises the following method steps:
    1. (a) During an injection molding cycle pressurizing the first piston such that the thereto interconnected closure element moves into the fully open position.
    2. (b) After sufficient melted plastic material is injected into the thereto connected injection mold, pressurizing the first piston such that it causes the thereto interconnected closure element to move into the fully closed position.
    3. (c) After the injected plastic material has cured to a certain degree, pressurizing the second piston such that the thereto interconnected closure element is moved into the intermediate position.
    4. (d) Opening the injection mold and removing the therein formed molded body.


    [0026] It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to pro-vide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0027] The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:
    Fig. 1
    An injection nozzle according to the invention in a perspective view from above;
    Fig. 2
    The actuator and the thereto interconnected closure element in three different positions;
    Fig. 3
    The cam mechanism in an exploded view.

    DESCRIPTION OF THE EMBODIMENTS



    [0028] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

    [0029] Figure 1 shows a hot runner injection nozzle 1 according to the invention in a perspective view from above. The injection nozzle 1 comprises an actuator cylinder 5 which is shown in a partially cut manner, such that the inside becomes apparent. In a cylinder housing 6 a first and a second piston 7, 8 are arranged linearly moveable with respectto the housing 6 and with respectto each other (z-direction). The second piston 8 comprises a first part 8.1 and a second part 8.2 which are interconnected to each other by a bushing 11. In the shown variation the second piston 8 is arranged coaxial to the first piston 7. The second piston 8, respectively the bushing 11 act as a linear bearing for the first piston 7. The housing 6 comprises a side wall 42, a top wall 43, a bottom wall 44 and a first and a second intermediate wall 45, 46.

    [0030] The injection nozzle 1 further comprises a nozzle head 2 including at least one discharge opening 3 for injecting melted material into a mold cavity of a thereto interconnected injection mold (not shown) and forming therein a molded body. At least one positively controlled closure element 4 is movably supported in the nozzle head 2 for closing a communication opening in the thereto connected injection mold. The actuator cylinder 5 is interconnected to the closure element 4 by a drive shaft 17 which extends across the bottom wall 44 of the housing 6.

    [0031] As visible in the drawings, the herein described variation of the injection nozzle 1 is a side gating nozzle, wherein at least one closure element 4 is arranged movable in a first direction (x-direction) wherein the first and the second piston 7, 8 are arranged moveable in a second direction (z-direction). The first and the second direction are arranged at an angle with respect to each other. In the shown variation the angle is 90°, however other angles are in principle possible.

    [0032] The actuator cylinder 5 is arranged at a rear end of a nozzle housing 30. The nozzle housing 30 comprises a nozzle flange 31 and a nozzle body section 32. With respect to the viewer's position at the lower end a nozzle bridge portion 33 is interconnected to the nozzle body section 32 and carries the nozzle head 2 as described herein above. The nozzle head 2 houses the closure element 4 and a cam mechanism 18 which interconnects the closure elements 4 with the actuator cylinder 5.

    [0033] The cam mechanism 18 is described in accordance with Figure 3 in more detail hereinafter.

    [0034] The first piston 7 delimits with respect to the cylinder housing 6 a first fluid chamber 12 (in the drawing above to the top wall 43) and a second fluid chamber 13 (in the drawing below to the first intermediate wall 45). The second piston 8 delimits with respect to the cylinder housing 6 a third fluid chamber 14 (to the first intermediate wall 45) and a fourth fluid chamber 15 comprising a first segment 15.1 (to the bottom wall 44) and a second segment 15.2 (to the second intermediate wall 46) which are interconnected to each other by a connection channel 16. In the shown variation the connection channel 16 is arranged in the bushing 11.

    [0035] As visible in Figure 1 the nozzle head 2 comprises in the shown variation per closure element 4 a closure element housing 35 which houses the closure element 4 on the inside. Inside the closure element housing 35 at least one distribution channel (not shown in detail) is arranged which is interconnected to an inlet opening 29 and guides melted plastic material from the inlet opening 29 to the discharge opening 3, wherein the flow of the melted plastic material is controlled by the actuator cylinder 5 via the thereto interconnected closure elements 4 and the cam mechanism 18. At a time two closure element housings 35 are arranged back to back with respect to each other, wherein the closure elements 4 are arranged coaxial with respect to and opposite to each other (x-direction). Two pairs of closure element housings 35 are arranged in a lateral direction (y-direction) adjacent to each other comprising in total four discharge openings 3. The closure elements 4 are arranged parallel to each other. All four closure elements 4 of the shown injection nozzle 1 are interconnected to and controlled by the actuator cylinder 5 via the cam mechanism 18.

    [0036] In each closure element housing 35 at least one heating element 36 is arranged in a thereto related bore 37. Each closure element housing 35 may comprise or be interconnected to temperate sensors (not shown in detail) which allow to control the temperature of each closure element housing 35 separately. As it can be seen in the drawings on either side of the control elements 4 a heating element 36 is arranged in a symmetric manner. Due to the slim design it is possible to arrange the heating elements 36 very close to the control elements 4. This offers the advantage that the temperature of each discharge opening 3 can be individually controlled.

    [0037] In Figure 2a through Figure 2c the actuator cylinder 5 and the thereto via a cam mechanism 18 interconnected closure element 4 can be seen in three different positions. The housings of the injection nozzle are left away, such that the inside becomes better apparent. The first piston 7 is arranged movable between a first position (see Figure 2a) in which the closure element 4 is fully closed (i.e. most outward position with respect the discharge opening 3). In a second position (see Figure 2c) the closure element 4 is fully open (i.e. most inward position with respect the discharge opening 3).

    [0038] The second piston 8 is also interconnected to the closure element 4 (in the shown variation via the first piston 7 as will be described in more detail hereinafter) arranged movable between a third position (see Figures 2a and 2c) in which the second piston 8 is not interconnected to the closure element 4 and a fourth position (see Figure 2a) in which the closure element 4 is with respect to the discharge opening limited in an intermediate position between the fully opened and the fully closed position.

    [0039] The first fluid chamber 12 when pressurized by a fluid causes the first piston 7 to go to the first position, while the second fluid chamber 13 when pressurized by a fluid causes the first piston 7 to go to the second position. The third fluid chamber 14 when pressurized by a fluid causes the second piston 8 to go to the third position and the fourth fluid chamber 15 when pressurized by a fluid causes the second piston 8 to go to the fourth position.

    [0040] If appropriate the second fluid chamber 13 and the third fluid chamber 14 can be supplied with pressurized fluid by a common supply line 27 (see Figure 2c). Thereby the first piston 7 can be moved to the second position, while the second piston is moved simultaneously to the third position.

    [0041] An active surface 9 of the first piston 7 is smaller than a corresponding total active surface 10 of the second piston 8, such that when pressurized with the same pressure the second piston 8 has priority over the movement of the first piston 7. As visible in Figure 2b the second piston 8 when in the fourth position limits the movement of the first piston 7 such that the closure element 4 remains in the intermediate position. In this intermediate position the closure element 4 does not extend into related the mold cavity (not shown in detail). Thereby it is secured that parts made are not damaged when opening the mold cavity to remove the molded body made therein.

    [0042] The injection nozzle 1 comprises in total four discharge openings 3 of which each can be opened and closed by a thereto related closure element 4. Two closure elements 4 are grouped forming a first and a second pair. The two closure elements 4 forming a pair are arranged coaxial with respect to each other and are interconnected by a thereto related common wedge 19 to the actuator cylinder 5. The two wedges 19 as visible are interconnected by a bridge element 25 to the drive shaft 17.

    [0043] If appropriate the injection nozzle may comprise a transport securing device as indicated in Figure 2c. The cylinder housing 6 therefore comprises a bore 38 and the first piston 7 a thereto coaxially arranged threaded hole 39. Thereby it becomes possible to attach the first piston 7 to the housing 6 in a secure position. The transport securing device should be considered a separate inventive concept, which may be made subject of one or several divisional patent applications.

    [0044] Figure 3 shows the cam mechanism 18 as herein mentioned above in an exploded view and in a simplified manner. The assembly of the exploded parts is indicated by dotted lines. The cam mechanism 18 corresponds to the cam mechanism 18 as shown in Figure 2a through Figure 2c. It is shown without the bridge element 25 which interconnects two neighboring wedges 19 arranged laterally adjacent to each other. While the wedge 19 is (with respect to the viewer's direction) arranged linearly moveable in z-direction, the closure elements 4 are arranged linearly moveable in x-direction (perpendicular to the moving direction of the wedge 19, if appropriate other angles would be possible). The closure elements 4 are arranged symmetric with respect to the z-axis.

    [0045] The wedge 19 comprises per closure element 4 a first drive surface 20 arranged at an angle α with respect to the moving direction (z-direction) of the wedge 19. Depending on the field of application the first drive surface 20 can have a non-flat design. The first drive surface 20 is foreseen to interact at least during a closing movement of the closure element 4 with a second drive surface 24 arranged at the closure element 4 thereby pushing the closure element 4 in an outward direction away from each other. In that the wedge 19 is moved in -z-direction, due to the wedged arrangement of the first drive surfaces 20 at an angle α, the first drive surfaces 20 push via the second drive surfaces 24 the closure elements 4 apart from each other in an outward direction. The second drive surfaces 24 are preferably arranged as well at an angle α with respect to z-direction (90°- α with respect to x-direction).

    [0046] To move the closure elements 4 in the opposite direction (against each other), each wedge 19 comprises or is interconnected to at least one third drive surface 26 which interacts at least during opening of the thereto related closure element 4 with a thereto related fourth drive surface 27 arranged at the closure element 4. In the shown variation a first and a second third drive surface 26 are arranged at a first and a second protrusion 22 which extend along a first and a second side plate 21. The side plates 21 are arranged in the mounted position (see e.g. Figure 2a) opposite to each other with respect to the wedge 19. The wedge 19, the first and the second side plates 21, as well as the first and the second protrusions 22 can be made in one piece. However, it is advantageous to design at least one side plate 21 removable as shown herein.

    [0047] The fourth drive surfaces 27 are arranged in a notch 23 arranged in a first and a second notch 23 arranged at a rear end of a thereto related closure element 4. If appropriate the fourth drive surfaces 27 can be arranged at a protrusion as well, e.g. at a shoulder extending outwardly (not shown in detail). Alternatively the third drive surfaces 26 can be arranged in a recess formed in a side plate (not shown in detail). The first and third drive surfaces 20, 26 both extend in the same general direction (parallel to each other), i.e. the distance between them remains constant.

    [0048] The closure elements 4 of the shown variation are having a cylindrical design with several diameters. A bearing surface 40 is arranged in a rearward section and a sealing surface 41 is arranged in a forward section (close to a discharge opening). The bearing surface 40 is used to support the closure element 4 with respect to the thereto related closure element housing 35 as shown in Figure 1. The first and the second notch 23 are arranged in symmetric manner at the bearing surface 40. The notch has an in general V-shaped cross section which matches to the cross section of the protrusion 22, which has in the shown variation an in general V-shaped cross section as well. The V-shaped cross sections offer advantages and improves self-centering of the elements during operation. Depending on the field of application other cross-sections are applicable (e.g. U-shaped,

    [0049] The improved cam mechanism 18can in principle be used in connection with other nozzles/actuators and should thus be considered a separate inventive concept, which may be made subject of one or several divisional patent applications. The first, the second, the third and the fourth drive surfaces are preferably arranged that during moving of the closure elements 4 apart, the first and the second drive surfaces 20, 24 are engaged and the third and the fourth drive surfaces 26, 27 remain disengaged, while during moving of the closure elements 4 against each other, the third and the fourth drive surfaces 26, 27 are engaged and the first and the second drive surfaces 20, 24 remain disengaged.

    [0050] Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the scope of the invention.
    LIST OF DESIGNATIONS
    x First direction 15.1 First segment
    z Second direction 15.2 Second segment
    1 Injection nozzle 16 Connection channel
    2 Nozzle head 17 Drive shaft
    3 Discharge opening 18 Cam mechanism
    4 Closure element (Valve pin) 19 Wedge
    5 Actuator cylinder 20 First drive surface (wedge)
    6 Cylinder housing 21 Side plate
    7 First piston 22 Protrusion
    8 Second piston 23 Notch
    8.1 First part (second piston) 24 Second drive surface (closure element)
    8.2 Second part (second piston)
    25 Bridge element
    9 Active surface (first piston) 26 Third drive surface
    10 Active surface (second piston) 27 Fourth drive surface
    28 Pressure pipe
    11 Bushing (between first and second piston) 29 Inlet opening
    30 Nozzle housing
    12 First fluid chamber 31 Nozzle flange
    13 Second fluid chamber 32 Nozzle body section
    14 Third fluid chamber 33 Nozzle bridge portion
    15 Fourth fluid chamber 34 Nozzle tip retainer
    35 Closure element housing 40 Bearing surface
    36 Heating element 41 Sealing surface
    37 Bore (for heating element) 42 Side wall
    38 Bore (Transport securing device) 43 Top wall
    44 Bottom wall
    39 Threaded hole (Transport securing device) 45 First intermediate wall
    46 Second intermediate wall



    Claims

    1. An injection nozzle (1) with

    a. a nozzle head (2) including at least one discharge opening (3) for injecting melted plastic material into a mold cavity of a thereto interconnected injection mold and forming therein a molded body,

    b. at least one positively controlled closure element (4) which is movably supported in the nozzle head (2) for closing a communication opening in the thereto connected injection mold, and

    c. an actuator cylinder (5) comprising

    d. a first piston (7) which is interconnected to the at least one closure element (4) is arranged movable between

    i. a first position in which the closure element (4) is fully closed and

    ii. a second position in which the closure element (4) is fully open, and

    e. a second piston (8) is arranged movable between a third position in which the second piston (8) is not interconnected to the closure element (4) and a fourth position in which the second piston (8) is interconnected to the closure element (4) and the closure element (4) is thereby limited in an intermediate position between the fully opened and the fully closed position,

    wherein the second piston (8) is in the fourth position interconnected to the first piston (7) by a bushing (11) and wherein an active surface (9) of the first piston (7) is smaller than a corresponding active surface (10) of the second piston (8), such that when pressurized with the same pressure the second piston (8) has priority over the movement of the first piston (7).
    characterized in that the second piston (8) comprises a first part (8.1) and a second part (8.2), the first part (8.1) and the second part (8.2) are interconnected to each other by the bushing (11), and the second piston (8) acts in the housing (6) as a linear bearing for the first piston (7).
     
    2. The injection nozzle (1) according to claim 1, wherein the second piston (8) when in the fourth position limits the movement of the first piston (7) such that the closure element (4) remains in the intermediate position.
     
    3. The injection nozzle (1) according to one of the preceding claims, wherein the diameter of the first piston (7) and the outer diameter of the first and the second part (8.1, 8.2) of the second piston (8) deviate from each other by a maximum of 10 mm.
     
    4. The injection nozzle (1) according to one of the preceding claims, wherein the first piston (7) delimits with respect to a cylinder housing (6) a first fluid chamber (12) and a second fluid chamber (13) and the second piston (8) delimits with respect to the cylinder housing (6) a third fluid chamber (14) and a fourth fluid chamber (15), wherein

    a. the first fluid chamber (12) when pressurized by a fluid causes the first piston (7) to go to the first position;

    b. the second fluid chamber (13) when pressurized by a fluid causes the first piston (7) to go to the second position;

    c. the third fluid chamber (14) when pressurized by a fluid causes the second piston (8) to go to the third position;

    d. the fourth fluid chamber (15), when pressurized by a fluid, causes the second piston (8) to go to the fourth position.


     
    5. The injection nozzle (1) according to claim 4, wherein the fourth chamber (15) comprises two segments (15.1, 15.2) which are functionally interconnected to each other by a connection channel (16).
     
    6. The injection nozzle (1) according to claim 5, wherein the connection channel (16) is arranged in the second piston (8).
     
    7. The injection nozzle (1) according to one of the claims 4 to 6, wherein the second fluid chamber (13) and the third fluid chamber (14) are supplied with pressurized fluid by a common supply line (27).
     
    8. The injection nozzle (1) according to one of the preceding claims, wherein at least one heating element (36) is arranged next to a closure element (4).
     
    9. The injection nozzle (1) according to claim 8, wherein the heating element (36) is arranged in a bore (37) of a closure element housing (35).
     
    10. The injection nozzle (1) according to claim 9, wherein the closure element housing (35) comprises two heating elements (36) and the closure element (4) is arranged between them.
     
    11. The injection nozzle (1) according to one of the preceding claims, wherein the closure element (4) and the first piston (7) are interconnected to each other by a drive shaft (17).
     
    12. The injection nozzle (1) according to one of the preceding claims, wherein the first piston (7) and the closure element (4) are interconnected to each other by a cam mechanism (18).
     
    13. The injection nozzle (1) according to claim 12, wherein the cam mechanism (18) comprises a wedge (19) and at least one side plate (21).
     
    14. The injection nozzle (1) according to claim 13, wherein at least one side plate (21) is attached to the wedge (19) as a separate part.
     
    15. The injection nozzle (1) according to one of the claims 12 through 14, wherein the wedge (19) comprises at least one first drive surface (20) foreseen to interact with a second drive surface (24) arranged at the closure element (4) at least during closing of the closure element (4).
     
    16. The injection nozzle (1) according to claim 15, wherein the at least one side plate (21) comprises a third drive surface (26) foreseen to interact with a fourth drive surface (27) arranged at the closure element (4) at least during opening of the closure element (4).
     
    17. The injection nozzle (1) according to claim 16, wherein the third drive surface (26) is arranged at a protrusion (22) of the at least one side plate (21) extending parallel to and spaced a distance apart from the first drive surface (20).
     
    18. The injection nozzle (1) according to claim 16 or 17, wherein the fourth drive surface (27) is arranged in a notch (23) arranged at the closure element (4).
     
    19. Method for operating an injection nozzle (1), comprising the following method steps:

    a. Providing an injection nozzle (1) according to one of claims 1 to 19 for injecting melted plastic material into a mold cavity of a thereto interconnected injection mold

    b. during an injection molding cycle pressurizing the first piston (7) such that the thereto interconnected closure element (4) moves into the fully open position;

    c. after sufficient melted plastic material is injected into the thereto connected injection mold pressurizing the first piston (7) such that the thereto interconnected closure element (4) moves into the fully closed position;

    d. after curing of the injected plastic material to a certain degree pressurizing the second piston (8) such that the thereto interconnected closure element (4) is moved into the intermediate position,

    e. opening the injection mold and removing the therein formed molded body.


     


    Ansprüche

    1. Einspritzdüse (1) mit

    a. einem Düsenkopf (2), der zumindest eine Auslassöffnung (3) zum Einspritzen von geschmolzenem Kunststoffmaterial in einen Formhohlraum einer damit verbundenen Spritzgussform und zum Ausbilden eines Formkörpers darin umfasst,

    b. zumindest ein zwangsgesteuertes Verschlusselement (4), das im Düsenkopf (2) beweglich gelagert ist, zum Schließen einer Verbindungsöffnung in der damit verbundenen Spritzgussform und

    c. einen Betätigungszylinder (5), umfassend

    d. einen ersten Kolben (7), der mit dem zumindest einen Verschlusselement (4) verbunden ist beweglich zwischen

    i. einer ersten Position, in der das Verschlusselement (4) vollständig geschlossen ist, und

    ii. einer zweiten Position, in der das Verschlusselement (4) vollständig offen ist, angeordnet ist und

    e. einen zweiten Kolben (8), der beweglich zwischen einer dritten Position, in der der zweite Kolben (8) nicht mit dem Verschlusselement (4) verbunden ist, und einer vierten Position, in der der zweite Kolben (8) mit dem Verschlusselement (4) verbunden ist und das Verschlusselement (4) dadurch in einer Zwischenposition zwischen der vollständig geöffneten und der vollständig geschlossenen Position begrenzt ist, angeordnet ist,

    wobei der zweite Kolben (8) in der vierten Position durch eine Buchse (11) mit dem ersten Kolben (7) verbunden ist und wobei eine Wirkfläche (9) des ersten Kolbens (7) kleiner ist als eine entsprechende Wirkfläche (10) des zweiten Kolbens (8), sodass bei Druckbeaufschlagung mit demselben Druck der zweite Kolben (8) Vorrang vor der Bewegung des ersten Kolbens (7) hat,
    dadurch gekennzeichnet, dass der zweite Kolben (8) einen ersten Teil (8.1) und einen zweiten Teil (8.2) umfasst, dass der erste Teil (8.1) und der zweite Teil (8.2) durch die Buchse (11) miteinander verbunden sind und dass der zweite Kolben (8) im Gehäuse (6) als ein Linearlager für den ersten Kolben (7) wirkt.
     
    2. Einspritzdüse (1) nach Anspruch 1, wobei der zweite Kolben (8), wenn er sich in der vierten Position befindet, die Bewegung des ersten Kolbens (7) begrenzt, sodass das Verschlusselement (4) in der Zwischenposition bleibt.
     
    3. Einspritzdüse (1) nach einem der vorangehenden Ansprüche, wobei der Durchmesser des ersten Kolbens (7) und der Außendurchmesser des ersten und des zweiten Teils (8.1, 8.2) des zweiten Kolbens (8) um maximal 10 mm voneinander abweichen.
     
    4. Einspritzdüse (1) nach einem der vorangehenden Ansprüche, wobei der erste Kolben (7) eine erste Fluidkammer (12) und eine zweite Fluidkammer (13) in Bezug auf ein Zylindergehäuse (6) begrenzt und wobei der zweite Kolben (8) eine dritte Fluidkammer (14) und eine vierte Fluidkammer (15) in Bezug auf das Zylindergehäuse (6) begrenzt, wobei

    a. die erste Fluidkammer (12) bei Druckbeaufschlagung durch ein Fluid bewirkt, dass der erste Kolben (7) die erste Position einnimmt;

    b. die zweite Fluidkammer (13) bei Druckbeaufschlagung durch ein Fluid bewirkt, dass der erste Kolben (7) die zweite Position einnimmt;

    c. die dritte Fluidkammer (14) bei Druckbeaufschlagung durch ein Fluid bewirkt, dass der zweite Kolben (8) die dritte Position einnimmt;

    d. die vierte Fluidkammer (15) bei Druckbeaufschlagung durch ein Fluid bewirkt, dass der zweite Kolben (8) die vierte Position einnimmt.


     
    5. Einspritzdüse (1) nach Anspruch 4, wobei die vierte Kammer (15) zwei Segmente (15.1, 15.2) umfasst, die durch einen Verbindungskanal (16) miteinander wirkverbunden sind.
     
    6. Einspritzdüse (1) nach Anspruch 5, wobei der Verbindungskanal (16) im zweiten Kolben (8) angeordnet ist.
     
    7. Einspritzdüse (1) nach einem der Ansprüche 4 bis 6, wobei die zweite Fluidkammer (13) und die dritte Fluidkammer (14) über eine gemeinsame Versorgungsleitung (27) mit druckbeaufschlagtem Fluid versorgt werden.
     
    8. Einspritzdüse (1) nach einem der vorangehenden Ansprüche, wobei zumindest ein Heizelement (36) neben einem Verschlusselement (4) angeordnet ist.
     
    9. Einspritzdüse (1) nach Anspruch 8, wobei das Heizelement (36) in einer Bohrung (37) eines Verschlusselementgehäuses (35) angeordnet ist.
     
    10. Einspritzdüse (1) nach Anspruch 9, wobei das Verschlusselementgehäuse (35) zwei Heizelemente (36) umfasst und wobei das Verschlusselement (4) zwischen diesen angeordnet ist.
     
    11. Einspritzdüse (1) nach einem der vorangehenden Ansprüche, wobei das Verschlusselement (4) und der erste Kolben (7) über eine Antriebswelle (17) miteinander verbunden sind.
     
    12. Einspritzdüse (1) nach einem der vorangehenden Ansprüche, wobei der erste Kolben (7) und das Verschlusselement (4) durch einen Nockenmechanismus (18) miteinander verbunden sind.
     
    13. Einspritzdüse (1) nach Anspruch 12, wobei der Nockenmechanismus (18) einen Keil (19) und zumindest eine Seitenplatte (21) umfasst.
     
    14. Einspritzdüse (1) nach Anspruch 13, wobei zumindest eine Seitenplatte (21) als ein separater Teil an dem Keil (19) befestigt ist.
     
    15. Einspritzdüse (1) nach einem der Ansprüche 12 bis 14,
    wobei der Keil (19) zumindest eine erste Antriebsfläche (20) umfasst, die dazu vorgesehen ist, zumindest während des Schließens des Verschlusselements (4) mit einer zweiten Antriebsfläche (24), die am Verschlusselement (4) angeordnet ist, zusammenzuwirken.
     
    16. Einspritzdüse (1) nach Anspruch 15, wobei die zumindest eine Seitenplatte (21) eine dritte Antriebsfläche (26) umfasst, die dazu vorgesehen ist, zumindest während des Öffnens des Verschlusselements (4) mit einer vierten Antriebsfläche (27), die am Verschlusselement (4) angeordnet ist, zusammenzuwirken.
     
    17. Einspritzdüse (1) nach Anspruch 16, wobei die dritte Antriebsfläche (26) an einem Vorsprung (22) der zumindest einen Seitenplatte (21) angeordnet ist, der sich parallel zur ersten Antriebsfläche (20) erstreckt und um einen Abstand von dieser beabstandet ist.
     
    18. Einspritzdüse (1) nach Anspruch 16 oder 17, wobei die vierte Antriebsfläche (27) in einer am Verschlusselement (4) angeordneten Kerbe (23) angeordnet ist.
     
    19. Verfahren zum Betreiben einer Einspritzdüse (1), umfassend die folgenden Verfahrensschritte:

    a. Bereitstellen einer Einspritzdüse (1) nach einem der Ansprüche 1 bis 19 zum Einspritzen von geschmolzenem Kunststoffmaterial in einen Formhohlraum einer damit verbundenen Spritzgussform;

    b. während eines Spritzgusszyklus Druckbeaufschlagen des ersten Kolbens (7), sodass sich das damit verbundene Verschlusselement (4) in die vollständig geöffnete Position bewegt;

    c. nachdem ausreichend geschmolzenes Kunststoffmaterial in die damit verbundene Spritzgussform gespritzt wurde, Druckbeaufschlagen des ersten Kolbens (7), sodass sich das damit verbundene Verschlusselement (4) in die vollständig geschlossene Position bewegt;

    d. nach dem Aushärten des eingespritzten Kunststoffmaterials bis zu einem gewissen Grad Druckbeaufschlagen des zweiten Kolbens (8), sodass das damit verbundene Verschlusselement (4) in die Zwischenposition bewegt wird,

    e. Öffnen der Spritzgussform und Entnehmen des darin ausgebildeten Formkörpers.


     


    Revendications

    1. Buse d'injection (1), comprenant

    a. une tête de buse (2) comportant au moins une ouverture de décharge (3) pour injecter de la matière plastique en fusion dans une cavité de moule d'un moule d'injection interconnecté à celle-ci et formant dans celui-ci un corps moulé,

    b. au moins un élément de fermeture commandé positivement (4) qui est supporté de manière déplaçable dans la tête de buse (2) pour fermer une ouverture de communication dans le moule d'injection connecté à celle-ci, et

    c. un cylindre d'actionneur (5) comprenant

    d. un premier piston (7) qui est interconnecté à l'au moins un élément de fermeture (4) et qui est disposé de manière déplaçable entre

    i. une première position dans laquelle l'élément de fermeture (4) est complètement fermé et

    ii.une deuxième position dans laquelle l'élément de fermeture (4) est complètement ouvert, et

    e. un deuxième piston (8) qui est disposé de manière déplaçable entre une troisième position dans laquelle le deuxième piston (8) n'est pas interconnecté à l'élément de fermeture (4) et une quatrième position dans laquelle le deuxième piston (8) est interconnecté à l'élément de fermeture (4) et l'élément de fermeture (4) est ainsi limité dans une position intermédiaire entre la position entièrement ouverte et la position entièrement fermée,

    le deuxième piston (8), dans la quatrième position, étant interconnecté au premier piston (7) par une douille (11) et une surface active (9) du premier piston (7) étant inférieure à une surface active correspondante (10) du deuxième piston (8), de telle sorte que lorsqu'ils sont soumis à la même pression, le deuxième piston (8) ait priorité sur le mouvement du premier piston (7),
    caractérisée en ce que le deuxième piston (8) comprend une première partie (8.1) et une deuxième partie (8.2), la première partie (8.1) et la deuxième partie (8.2) étant interconnectées l'une à l'autre par la douille (11), et le deuxième piston (8) agissant dans le boîtier (6) comme un palier linéaire pour le premier piston (7).
     
    2. Buse d'injection (1) selon la revendication 1, dans laquelle le deuxième piston (8), dans la quatrième position, limite le mouvement du premier piston (7) de telle sorte que l'élément de fermeture (4) reste dans la position intermédiaire.
     
    3. Buse d'injection (1) selon l'une des revendications précédentes, dans laquelle le diamètre du premier piston (7) et le diamètre extérieur de la première et de la deuxième partie (8.1, 8.2) du deuxième piston (8) s'écartent l'un de l'autre d'un maximum de 10 mm.
     
    4. Buse d'injection (1) selon l'une des revendications précédentes, dans laquelle le premier piston (7) délimite, par rapport à un boîtier de cylindre (6), une première chambre de fluide (12) et une deuxième chambre de fluide (13) et le deuxième piston (8) délimite, par rapport au boîtier de cylindre (6), une troisième chambre de fluide (14) et une quatrième chambre de fluide (15),

    a. la première chambre de fluide (12), lorsqu'elle est pressurisée par un fluide, amenant le premier piston (7) à se déplacer dans la première position ;

    b. la deuxième chambre de fluide (13), lorsqu'elle est pressurisée par un fluide, amenant le premier piston (7) à se déplacer dans la deuxième position ;

    c. la troisième chambre de fluide (14), lorsqu'elle est pressurisée par un fluide, amenant le deuxième piston (8) à se déplacer dans la troisième position ;

    d. la quatrième chambre de fluide (15), lorsqu'elle est pressurisée par un fluide, amenant le deuxième piston (8) à se déplacer dans la quatrième position.


     
    5. Buse d'injection (1) selon la revendication 4, dans laquelle la quatrième chambre (15) comprend deux segments (15.1, 15.2) qui sont interconnectés fonctionnellement l'un à l'autre par un canal de connexion (16).
     
    6. Buse d'injection (1) selon la revendication 5, dans laquelle le canal de connexion (16) est disposé dans le deuxième piston (8).
     
    7. Buse d'injection (1) selon l'une des revendications 4 à 6, dans laquelle la deuxième chambre de fluide (13) et la troisième chambre de fluide (14) sont alimentées en fluide sous pression par une ligne d'alimentation commune (27).
     
    8. Buse d'injection (1) selon l'une des revendications précédentes, dans laquelle au moins un élément chauffant (36) est disposé à côté d'un élément de fermeture (4).
     
    9. Buse d'injection (1) selon la revendication 8, dans laquelle l'élément chauffant (36) est disposé dans un alésage (37) d'un boîtier d'élément de fermeture (35) .
     
    10. Buse d'injection (1) selon la revendication 9, dans laquelle le boîtier d'élément de fermeture (35) comprend deux éléments chauffants (36) et l'élément de fermeture (4) est disposé entre eux.
     
    11. Buse d'injection (1) selon l'une des revendications précédentes, dans laquelle l'élément de fermeture (4) et le premier piston (7) sont interconnectés l'un à l'autre par un arbre d'entraînement (17).
     
    12. Buse d'injection (1) selon l'une des revendications précédentes, dans laquelle le premier piston (7) et l'élément de fermeture (4) sont interconnectés l'un à l'autre par un mécanisme de came (18).
     
    13. Buse d'injection (1) selon la revendication 12, dans laquelle le mécanisme de came (18) comprend une cale (19) et au moins une plaque latérale (21).
     
    14. Buse d'injection (1) selon la revendication 13, dans laquelle au moins une plaque latérale (21) est attachée à la cale (19) en tant que pièce séparée.
     
    15. Buse d'injection (1) selon l'une des revendications 12 à 14, dans laquelle la cale (19) comprend au moins une première surface d'entraînement (20) prévue pour coopérer avec une deuxième surface d'entraînement (24) disposée au niveau de l'élément de fermeture (4) au moins au cours de la fermeture de l'élément de fermeture (4).
     
    16. Buse d'injection (1) selon la revendication 15, dans laquelle l'au moins une plaque latérale (21) comprend une troisième surface d'entraînement (26) prévue pour coopérer avec une quatrième surface d'entraînement (27) disposée au niveau de l'élément de fermeture (4) au moins au cours de l'ouverture de l'élément de fermeture (4).
     
    17. Buse d'injection (1) selon la revendication 16, dans laquelle la troisième surface d'entraînement (26) est disposée au niveau d'une saillie (22) de l'au moins une plaque latérale (21) s'étendant parallèlement à la première surface d'entraînement (20) et espacée de celle-ci.
     
    18. Buse d'injection (1) selon la revendication 16 ou 17, dans laquelle la quatrième surface d'entraînement (27) est disposée dans une encoche (23) disposée au niveau de l'élément de fermeture (4) .
     
    19. Procédé de fonctionnement d'une buse d'injection (1), comprenant les étapes de procédé suivantes :

    a. fourniture d'une buse d'injection (1) selon l'une des revendications 1 à 19, pour injecter de la matière plastique en fusion dans une cavité de moule d'un moule d'injection interconnecté à celle-ci,

    b. au cours d'un cycle de moulage par injection, pressurisation du premier piston (7) de telle sorte que l'élément de fermeture (4) interconnecté à celui-ci se déplace dans la position entièrement ouverte ;

    c. après l'injection d'une quantité suffisante de matière plastique en fusion dans le moule d'injection connecté à celle-ci, pressurisation du premier piston (7) de telle sorte que l'élément de fermeture (4) interconnecté à celui-ci se déplace dans la position entièrement fermée ;

    d. après le durcissement de la matière plastique injectée jusqu'à un certain degré, pressurisation du deuxième piston (8) de telle sorte que l'élément de fermeture (4) interconnecté à celui-ci soit déplacé dans la position intermédiaire,

    e. ouverture du moule d'injection et enlèvement du corps moulé formé dans celui-ci.


     




    Drawing














    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description