WO2011042161A2

WO2011042161A2 - Directly operated needle valve nozzle for an injection molding device

Info

Publication number: WO2011042161A2
Application number: PCT/EP2010/006085
Authority: WO
Inventors: Volker Reichert; Karl-Heinz Haberkorn; Joachim Hubrich; Ralph Herzog
Original assignee: Herzog Systems Ag
Priority date: 2009-10-10
Filing date: 2010-10-06
Publication date: 2011-04-14
Also published as: WO2011042161A3; DE102009044231A1

Abstract

The invention relates to a directly operated needle valve nozzle for an injection molding device for producing injection-molded parts on injection molding machines, an actuator (1) being secured to the housing (5) in annular manner about the nozzle body (2). The actuator (1) is connected directly to the needle (16) by means of an annular sleeve (14) via the yoke (15) and consists of one, two or a plurality of controllable electromagnets (10), which are individual or which function independently of one another, or said actuator consists of one, two or a plurality of permanent magnets (12) and of one, two or a plurality of controllable electromagnets (10), the effect of the coupled electromagnets (10) or the effect of the permanent magnets (12) with the effect of the electromagnets (10), also designated magnet arrangements (21), being harmonized such that said effect causes a controlled, defined and adjustable axial movement of the needle (16) in the nozzle body (2) of the needle valve nozzle by means of an annular armature disk (9), which can be coupled and actuated magnetically and which lies in the range of action of the magnet arrangements (21), via the annular sleeve (14), which is connected to the needle (16) perpendicularly.

Description

Direct operated needle valve nozzle for an injection molding device

The invention relates to a direct-operated needle valve nozzle for a

Injection molding device for the production of injection molded parts on injection molding machines according to the preamble of claim 1.

Needle valve nozzles are used in injection molding equipment for the production of

Injection molded parts on injection molding machines u. a. used for the following reasons:

Prevention / avoidance of melt leaks from the nozzle during plasticizing,

Shortening the cycle time by simultaneous plasticizing and carrying out tool opening and closing movements. In addition, to achieve a high process consistency, it is advantageous if the opening and closing operation of the needle valve nozzle in the cycle, which as a rule can be equated with the beginning and end of a defined flow of melt into the cavity, is always as exactly as possible at the same time ,

Needle valve nozzles in injection molding devices are usually with mechanical levers for actuating the needle either by means of hydraulic or pneumatic cylinders or, as described in DE 20 2008 000 318 Ul, with electromagnetically actuated

Solenoid carried out. These actuators are called regardless of the supplied energy form (compressed air, pressure oil flow, electric power) as actuators. As a needle, the centrally located elements are referred to in the nozzles, which z. B. as a cylinder in a hole or as a cone tips in tapered holes and thus lock a melt stream from the plasticizing and injection unit of the injection molding machine in the cavity or pass.

In the case of the needle valve nozzles known from the prior art, the design of the lever for operating the needle takes place so that the needle acts on the short lever arm and the actuator on the longer. It follows that the actuator has to cover a longer each time by the lever ratio way than the needle to the blocking or

Opening position of the nozzle to achieve. Due to the leverage results further that the applied forces for actuating the needle according to the used Lever ratio are lower than if the needle could be operated directly. The actuating forces arise from the initiation of Öffhungs- or

Closing operation of the needle prevailing static pressure in the plastic melt and the size of the acted upon by this pressure surfaces on the needle. The disadvantage, however, in these solutions that when immersing the nozzle in the solid

Tool mounting plate of the injection molding a correspondingly large installation space must be available so that there is no collision of the nozzle with the surface of the nozzle opening in the plate of the injection molding machine. Since the installation space is often very small, then the nozzle head of such an injection unit is formed correspondingly longer. The disadvantage here is mainly that a larger amount

Injection molding remains until the next cycle of a subsequent injection molding process inside the injection nozzle provided with extended nozzle head. In order to apply the necessary force and the way to actuate the needle, the actuators are dimensioned according to the nozzle size (or size of the injection molding machines).

In DE 20 2008 000 318 Ul a special lever mechanism is proposed, which requires a relatively small installation space, in comparison with the solutions of the prior art, the needle can still be operated with actuators, which apply the necessary forces to actuate the needle , However, while the actuator is only moved away from the installation space to further back, which makes the construction more complex overall. As can be seen from FIG. 1 of the specification, the state of the art - and also the solution according to DE 20 2008 000 318 Ul - does not use all the available installation space around the nozzle head. The installation space is defined as "free" volume - or

"Difference volume", which is characterized by the construction of the nozzle opening of the fixed platen of the injection molding machine and by the

Needle valve nozzle with actuator occupied space results. In order to make optimum use of the space around the nozzle which is currently available and so far unused, a technical solution known as "OBTEK nozzle" is known from a company publication of VEGA France ECI, where a ring-shaped design of a pneumatically operated actuator of a pneumatic cylinder the nozzle head of the

Injection molding arranged around and used to this disadvantage remove. This creates a compact short construction of an injection molding nozzle with directly operated needle. Likewise, an optimized space-saving utilization of the free installation space and there is a short nozzle head can be formed.

Another significant disadvantage of all lever operated needle valve nozzles is that the needle is unnecessarily enlarged away in the nozzle (needle stroke) by the lever. This results in longer switching times for the opening and closing of the needle valve nozzles, which z. B. in the expansion injection molding or injection molding of micro-parts may well be on the order of the actual injection times. In addition, the lever that moves the needle makes a circular path around the pivot point. As a result, the points for the power transmission is on a circular path. The

Force application surfaces between lever and actuator or between the lever and needle can therefore be performed crowned. It is unavoidable, however, that act in a force attack outside the axis of symmetry of the needle or the actuator additional lateral forces on the needle, resulting in increased wear and as a result of premature leaks z. b. threading in and around the nozzle.

The invention has for its object to provide a direct operated needle valve nozzle for an injection molding, which has a compact design with short

Düsenkopf allows, can be arranged in the installation space, realized very short closing and opening times, ensures a high density and also the

Actuating forces that move the needle varies and are optimally adjustable.

The solution to this problem is the subject of the invention disclosed in the independent claims. Further expedient embodiments of the invention are the subject of the dependent claims. The direct-operated needle valve nozzle according to the invention for an injection molding apparatus for the production of injection molded parts on injection molding machines is equipped with a novel actuator 1, which is known from the prior art, as in one case, annularly attached to a nozzle body and to a housing. The actuator 1 of the invention is either as a 360 ⁰ full circle or as a Partial ring or formed as a segmented annulus or as two or more circle segments. The actuator 1 is directly preferably connected by means of an annular sleeve 14 via the yoke 15 with the needle 16. The actuator 1 consists of a, of two or more individual or independently acting controllable electromagnet 10, or this consists of one, two or more permanent magnets 12 and one, two or more controllable electromagnet 10, in which case the effect of

coupled electromagnet 10 and the permanent magnet 12 with the action of the electromagnets 10 also referred to as magnet assemblies 21 is brought into line, this by means of a magnetically coupled and operable annular

Anchor disc 9, which is arranged in the region of action of the magnet assemblies 21, via the annular sleeve 14, which is connected at right angles to the needle 16, a controlled defined and adjustable axial movement of the needle 16 in the nozzle body 2 causes the Nadelverschlussdüse.

The main advantages of this inventive design of an actuator 1 in this direct-operated needle valve nozzle that less moving parts are needed for needle operation; Thus, lower masses to be moved are present, the friction in the guides of all moving parts 16 can be minimized, consuming

Joint connections for needle operation can be omitted and the needle 16, since no transverse forces act on this, is moved centrically purely linear along the axis of symmetry. This goes hand in hand with a significant reduction in the negative effect of

Thread pulling, a reduction of the Committee of injection molded parts, an improvement of the gate, especially in so-called Punktangüssen, an improvement of the entire injection cycle and an optimization of the injection molding process. The most significant advantages of the invention are significantly shorter switching times, which allows a higher dynamics of the operation of the opening and closing of the needle 16.

Another possible application of this embodiment of the actuator 1 according to the invention is to go directly to the sprue bushing in the case of injection molds with low-lying sprue bushing directly with the needle 16 actuated by the actuator 1. Thus, the volume located between the needle 16 and sprue bushing is further minimized and an extension of the needle 16 with the surrounding nozzle head or the nozzle body 2 as a whole is no longer necessary. In an economically most sensible and preferred embodiment of the actuator 1 according to the invention for a direct-operated needle valve nozzle for an injection molding apparatus according to claim 1, the actuator 1 is formed as a full rice ring and attached via a housing 6 on the nozzle body 2. Here, in the interior of the actuator 1, a U-shaped one-piece or multi-piece annular permanent magnet 13 is arranged so that the annular permanent magnet 13 in turn encloses an annular electromagnet 11 from three sides over its entire surface. In the area of action of this magnet arrangement 21, d, h. in the area of action of the permanent magnet 3 and of the enclosed annular electromagnet 1, an annular magnetically actuated armature disk 9 is arranged. With this annular armature disk 9, which in the coupled magnetic field of the

Magnetic arrangements 21 moves, an annular sleeve 14 by means of one, two or more force limiting springs 7 is connected. At this annular sleeve 14, the yoke 15 is disposed further inside, which in turn perpendicular to the needle 16 in the interior of the

Pressure chamber 4 is connected. Furthermore, the annular sleeve 14 is connected to two or more return springs 8 with the fixed housing 5.

In another embodiment of the actuator 1 according to the invention for a direct-operated needle valve nozzle for an injection molding device, instead of the return springs 7, a second controllable electromagnet 11 is arranged annularly in the stationary housing 5. The needle 16 in the interior of the pressure chamber 4 is, as already described above, connected via the yoke 15 to an annular sleeve 14, to which in turn the annular armature disk 9 is connected via two or more force-limiting springs. The advantage of this arrangement is the better controllability of the needle 16 by means of the second controllable electromagnet.

In a further improved but somewhat more complicated embodiment of the technical solution described immediately above, instead of the return springs 8, a second controllable electromagnet 11 is arranged annularly in the stationary housing 5, which is also surrounded on three sides by a U-shaped annular permanent magnet. Optionally, it makes sense between ring sleeve 14 and second

Magnet arrangement to arrange a further annular magnetically actuated armature disc 9. But it is also an embodiment possible, where the ring sleeve 14 itself is formed magnetically actuated. The advantage of this design is the possibility to build the actuator 1 even shorter than otherwise possible (with the same forces to be transmitted). This results in even shorter switching times and this also means that also lying deeper in the machine plate sprue bushing directly with this Aktor- or

Needle valve nozzle design can be achieved.

It is advantageous in the embodiment of the actuator 1 according to the invention with at least one permanent magnet, if one, two or more additionally arranged heat sink 17 are thermally coupled to or in the annular actuator 1, that the actuator 1 thermally from the melt-carrying components of the needle valve nozzle, d , H. from

Nozzle body 2, is arranged separately. Permanent magnets, depending on their material composition above relatively low temperatures, have the property that the magnetization decreases on overheating. Therefore, depending on the temperatures present in the injection molding apparatus, it may be necessary to arrange heatsinks 17 at suitable locations to dissipate the heat from the actuator 1 so that the effect of the permanent magnet (s) does not diminish over time.

In a structural design of the actuator 1 with a U-shaped annular permanent magnet 13 is on the end faces of the annular actuator 1 one or both sides a disc-like heat sink 18 and the stationary housing 5, a flange-like heat sink 19 is arranged. The flange-like heat sink 19 is so

formed so that its axial ring extends so far into the actuator 1, that the

Magnet arrangements 21 d. H. the permanent magnet 13 and the electromagnet 11 in the interior of the actuator (1) with respect to the feeds of the plastic melt 22 thermally

are shielded.

It is furthermore advantageous if the heat sinks 17 are provided and designed with additional cooling fins and / or cooling channels and / or cooling bores for supplying and removing a cooling medium. As a cooling medium depending on the design of the actuator 1 gaseous cooling media such. As air or liquid cooling media such. As water or oil are used. For certain applications, however, is sufficient

corresponding embodiment of the heat sink 17 already the normal natural

Luftkon vection for cooling the magnet assembly 21 from. By the actuator 1 according to the invention for a direct-operated needle valve nozzle for an injection molding succeeds to create a very compact small construction with short nozzle body 2, which can be arranged completely in the installation space, allows very short closing and opening times, ensures a high tightness and where both the dot matrix pressure as well as the actuating forces that move the needle 16 can be varied as needed and optimally adjusted.

The invention will be explained in more detail below in an embodiment with reference to Figures 1 and 2.

1 shows a simple schematic embodiment of an actuator 1 according to the invention. FIG. 2 shows a sectional view of an actuator 1 according to the invention with heat sinks 17

In a housing 6, which is fixed on the nozzle body 2, is an annular

Combination of a one-piece U-shaped annular permanent magnet 13 and an annular electromagnet 11 is arranged. The annular electromagnet 11 is on the three sides of the entire surface of the U-shaped annular permanent magnet thirteenth

enclosed. Following on from the U-shaped annular permanent magnet 13 and the annular electromagnet 11 existing magnet assembly 21 (in the

Drawing not benummert) is the axially movable, also annular trained anchor plate 9 is arranged. This annular, magnetically coupled and actuatable armature disk 9 is in the range of action of the magnet assembly 21, ie the armature disk 9 is penetrated by the field lines of the magnetic field and influenced in its axial direction of movement by the controllable magnetic field. A plurality of force limiting springs 7 (eg 3 or 4) are fastened to this armature disk in a uniformly rigidly distributed manner. These force-limiting springs 7 are fastened on the other side with the radially extending part of the annular sleeve 14. At the annular sleeve 14, the yoke 15 is arranged so that it can be connected at right angles to the needle 16 in the pressure chamber 4 for the plastic melt. The annular sleeve 14 is further connected to the fixed housing 5 by means of a plurality of return springs 8 (eg 3 or 4) arranged distributed over a circle. If an electric voltage is briefly applied to the electromagnet 11 as the first switching voltage, the magnetically coupled and actuatable armature disk 9 moves in the direction of the magnet arrangement 21. In this case, the armature disk increasingly reaches the effective range of the magnetic field of the permanent magnet 13. If the armature disk 9 reaches the radial outer surface The magnet assembly 21 comes to close the field lines on the armature disk 9, ie the permanent magnet unfolds its full effect.

At the same time in this position, the needle 16 is fully immersed in the nozzle opening 3 and the nozzle body 2 is closed. The electromagnet 11 is this position of

Armature plate switched off or switched off. Simultaneously with the movement of the armature disk 9, the springs 7 and 8 mounted on the housing build up a counterforce, which counteracts the force of the permanent magnet 13. The needle 16 is solely by the force of the permanent magnet 13, d. H. held without supply of additional energy against acting in the pressure chamber 4 for the plastic melt process forces (pressure in the plastic melt) in the position "nozzle opening 3 by needle 16 closed"

The forces acting on the needle 16 in the pressure chamber 4 forces, caused by the respectively acting static pressure in the plastic melt in the pressure chamber 4 in the

Nozzle position "closed", they act in a balance of forces on the needle 16 against the force of the permanent magnet 13. If the force resulting from the acting pressure in the plastic melt is greater than the force of the permanent magnet, the needle 16 opens, this is smaller, remains the needle still closed.

Thus, in the closing direction of the needle 16, only the force of the permanent magnet 13 acts. This force is counteracted by the resultant force from the pressure in the

Plastic melt and the opposing force of the return springs 8, between the

fixed housing 5 and the movable annular armature disc 9 are arranged. In order to move the needle 16 to the "open" position, it is necessary to compensate for the permanent force of the permanent magnet 13 by the force of the electromagnet 11 (again briefly applying a voltage as a second switching voltage to the electromagnet 11, this causes a short term Canceling the holding action of the permanent magnet 13, ie structure of an oppositely directed electromagnetic field), so that the return springs 8, the annular armature disc 9 of the radial Move magnetic surface away. Due to the direct connection of the annular

Armature disk 9 with the annular sleeve 14, via the yoke 15 with the needle 16, the needle 16 thus moves into the "open" position connected needle 16) is a function of the air gap, which is located between the two components magnet assembly 21 and armature disc 9.

As is known, the effect of the magnetic field when touching the armature disk with the permanent magnet is largest and decreases with increasing air gap. For a safe and process-stable function of the needle valve nozzle, it is necessary for the needle position "closed", that the armature disk 9 rests on the radial magnet surface or the air gap reaches at least minimal, ie very small, values In order to limit permanent magnets 13, it is proposed according to the invention to arrange one or more force-limiting springs 7 between the armature disk 9 and the annular sleeve 14. Advantageously, as

Force limiting springs 7 to use such springs, which build a largely independent of the spring travel acting constant spring force. This achieves the following: When the "Needle 16 closed" position is reached (before the position of the Anchor Disc 9 on the magnet surface is reached), these clamps

Force limiting springs 7, because the armature disk 9 is still moving in the direction of the two magnets, the magnet assembly 21. The force acting on the needle 16 is then the spring force of the force limiting springs and not the force through the

Permanent magnet 13 is applied. Thus, the force acting on the needle 16 force can not exceed the value preset by the force limiting springs 7. By using springs with "constant" spring force over the spring travel, the influence of manufacturing tolerances on the acting force in the mechanically moving parts is also completely compensated.An essential advantage of this actuator 1 according to the invention is that the needle 16 can be moved without supplying any energy, despite the im

Pressure chamber 4 of the plastic melt acting process forces in the position

"Düsenöffhung 3 closed" can be kept. FIG. 2 shows an actuator embodiment according to the invention for a directly actuated needle valve nozzle with heat sinks 17. This shows a sectional view of an actuator 1 according to the invention with two disc-like heat sinks 18 and a flange-like heat sink 19 as a heat sink 17. The two disc-like heat sink 18 are arranged on the left and right radially outside on the front sides of Aktots 1 and indicate the heat absorbed via pure air convection the environment. The flange-like heat sink 19, however, is provided in its interior with cooling channels and cooling holes, which preferably extend over its entire cross-section. The flange-like heat sink 19 is formed so that its axial ring extends so far into the actuator 1, so that the magnet assemblies 21 in the interior of the actuator 1 with respect to the feeds of the plastic melt 22 and the pressure chamber 4 of the nozzle body 2 by the hot melt in Direction nozzle orifice 3 flows, are formed shielded. In this case, the inner circumferential surface of the axial leg of the flange-like heat sink 19 can be arranged at a distance from the surface of the nozzle body. Here, if necessary, an additional insulating body can be arranged. Through these cooling channels and cooling holes, a cooling medium is supplied so that the magnet assemblies 21 are cooled so that they can be constantly tempered below the critical temperature limit of the permanent magnet 13.

LIST OF REFERENCE NUMBERS

1 actuator

2 nozzle body

3 nozzle opening

4 pressure chamber for plastic melt

5 fixed housing

6 housing

7 force limiting spring

8 return spring

9 annular armature disc

10 electromagnet

11 Annular electromagnet

12 permanent magnet

13 U-shaped permanent magnet

14 ring sleeve

15 yoke

16 needle

17 heat sink

18 disc-like heat sink

19 flange-type heat sink

20 cooling channels and / or cooling holes

21 magnet arrangements

22 feeds of the plastic melt

Claims

claims

1. Direct operated needle valve nozzle for an injection molding device for the production of injection molded parts on injection molding machines with an annular arrangement of the actuator around a nozzle body and attachment to a housing,

characterized,

which the actuator (1) is formed as a full circle ring 360 ^0, as a part of a circular ring, as a segmented annular ring, or as two or more segments of a circle,

the actuator (1) is connected to the needle (16) directly via a yoke (15) by means of an armature disk (9),

the actuator (1) consists of one, two or more individual or independently controllable electromagnets (10),

or one, two or more permanent magnets (12) and one, two or more controllable electromagnets (10),

wherein the armature disk (9) is arranged in the area of action of the magnet arrangements (21) and is designed to be magnetically coupled and actuated.

2. Direct operated needle valve nozzle for an injection molding apparatus according to claim 1, characterized

the actuator (1) is designed as a full ring of rice and has a housing (6) on it

Nozzle body (2) is arranged,

in the interior of the actuator (1) a cross-sectionally U-shaped one-piece or multi-piece annular permanent magnet (13) is arranged, which has an annular

Electromagnet (11) encloses,

a magnetically actuated annular armature disk (9) is arranged in the area of action of the magnet arrangements (21),

wherein the yoke (15) via an annular sleeve (14) with one, two or more

Force limiting springs (7) is connected to the annular armature disc (9), the annular sleeve (14) with one, two or more return springs (8)

is connected to a fixed housing (5) and

the yoke (15) is connected directly to the needle (16) in the interior of the pressure chamber (4).

3. Direct operated needle valve nozzle for an injection molding apparatus according to claim 2, d a a c e c e m e n c e n e,

the actuator (1) is designed as a complete circular ring and is arranged on the nozzle body (2) via a housing (6),

Electromagnet (11) encloses,

wherein the yoke (15) via an annular sleeve (14) over, one, two or more

Force limiting springs (7) with an annular armature disc (9) is connected, instead of the return springs (7), a second controllable electromagnet (11) is arranged annularly in the fixed housing (5) and

4. Direct operated needle valve nozzle for an injection molding apparatus according to claim 2, d a d e c e c e s e c e n e,

the actuator (1) is designed as a full ring of rice and has a housing (6) on it

Nozzle body (2) is arranged,

Electromagnet (11) encloses,

wherein the yoke (15) of the annular electromagnet (11) is connected via an annular sleeve (14) with one, two or more force-limiting springs (7) to an annular armature disc (9),

instead of the return springs (8), a second controllable electromagnet (11) is annularly arranged in the stationary housing (6), which is enclosed by an annular permanent magnet, and

5. Direct operated needle valve nozzle for an injection molding according to any one of the preceding claims,

characterized,

that on or in the annular actuator (1) one, two or more additionally arranged heat sinks (17) are thermally coupled so that the actuator (1) thermally from the melt-carrying components of the needle valve nozzle, d. H. separated from the nozzle body (2).

6. Direct-operated needle valve nozzle for an injection molding device according to one of the preceding claims,

characterized,

in that a disk-like heat sink (18) is arranged on one or both sides of the end faces of the annular actuator (1) and a flange-like heat sink (19) on the fixed housing (5) whose axial ring extends so far into the actuator (1) the magnet arrangements (21) are shielded in the interior of the actuator (1) with respect to the feeds of the plastic melt (22).

7. Direct operated needle valve nozzle for an injection molding according to any one of the preceding claims,

characterized,

in that the heat sinks (17) are formed with additional cooling ribs and / or cooling channels and / or cooling bores for supplying and removing a cooling medium.