EP1922202A1

EP1922202A1 - Injection-moulding device with needle valve nozzle and guide bush

Info

Publication number: EP1922202A1
Application number: EP06762979A
Authority: EP
Inventors: Herbert Günther
Original assignee: Guenther Heisskanaltechnik GmbH
Current assignee: Guenther Heisskanaltechnik GmbH
Priority date: 2005-08-10
Filing date: 2006-08-04
Publication date: 2008-05-21
Also published as: KR20080041642A; CA2619440A1; WO2007017187A1; BRPI0616555A2; CN101237980A; JP2009504433A; DE202005012705U1; TW200722264A

Abstract

Injection-moulding device (1) with a feed plate (3), in which at least one flow channel (4) for a flowable material is formed, with at least one needle valve nozzle, through which the flowable material can be fed in continuation of the flow channel to a separable mould insert, with at least one shut-off needle (20), at least a portion of which passes through the flow channel in a longitudinally displaceable manner and which can be brought by means of a drive into an open position and a closed position, and with a guide bush (30) for leading the shut-off needle (20) through and sealing it. The guide bush has a region which encloses the shut-off needle with a small amount of play and at least a portion of which lies in the flow channel. The region thereby has a contact surface for the flowable material, at least a portion of which lies in the flow channel. The region and the contact surface (44) are flowed around by flowable material on all sides.

Description

INJECTION MOLDING DEVICE WITH NEEDLE CLOSURE NOZZLE AND GUIDE BUSHING

The invention relates to an injection molding apparatus with needle valve nozzles according to the preamble of claim 1.

Needle valve nozzles are used in injection molding apparatus to supply a flowable mass to a separable mold insert at a prescribable temperature under high pressure. They usually have pneumatically or hydraulically driven shut-off needles that periodically open and close the gate openings in the mold insert. This allows for the most accurate material dosages, especially with rapid firing. However, the flowable mass can also be injected segmented, e.g. at the cascade.

Each closure needle is axially displaceably mounted in the tool-side region of the injection molding device and preferably guided centrally in the nozzle-side region through a flow channel for the mass to be processed (see, for example, DE 32 49 486 C3 or DE 34 03 603 A1). The flow channel ends in a nozzle mouthpiece which forms a nozzle outlet opening at the end. In the closed position, the lower end of the locking needle engages in a sealing seat, which is formed in the nozzle mouthpiece or in the mold insert.

For tight guidance of the closure needle usually a guide bushing or a sealing sleeve is used in the distributor plate of the injection molding, which receives the cylindrical shaft of the closure needle (see, for example, DE 39 26 357 A1 or EP 1 223 020 B1). Between the locking needle and the Socket remains a cylindrical space into which flows during the operation of the injection molding flowable material, so that the needle is sealed against the flow channel. At the same time creates a lubricating effect, which reduces the friction between the locking needle and the socket.

Despite optimal design of such a sealing system, it can not be avoided due to the relatively high pressures within the tool and due to the lifting movements of the needle that the mass to be processed penetrates through the guide or sealing bushing through to the outside. Material losses are the result. Moreover, the scraps contaminate both the sealing needle and the tool, which not only affects the sealing effect, but can permanently hinder the opening and closing movement of the locking needle. Elaborate cleaning or maintenance work is inevitable.

The aim of the invention is to avoid these and other disadvantages of the prior art and to further improve the guidance and sealing of closure needles in an injection molding apparatus. The aim is in particular a seal assembly that is inexpensive and easy to handle with simple means.

Main features of the invention are specified in claim 1. Embodiments are the subject of claims 2 to 23.

In an injection molding apparatus with a distributor plate, in which at least one flow channel for a flowable material is formed, with at least one needle valve nozzle, through which the flowable material can be fed to a separable mold insert while continuing the flow channel, with at least one closure needle, which at least partially longitudinally displaces the flow channel - Lich interspersed and can be brought by means of a drive in an open and a closed position, and with a guide bushing for the implementation and sealing of the locking needle, the invention provides that the guide bushing has at least one region comprising the shutter needle with little movement play and at least partially in the flow channel.

As a result, an area of the guide bush is always in direct contact with the flowable material, which exerts pressure on the guide bush with each injection. This results in that the contact area is pressed while overcoming the slight movement play sealing against the locking needle, so that during the high pressure phase no materia! can penetrate through the guide bushing out of the injection molding device to the outside. At the same time the locking needle is fixed by the guide bush in its central position, so that during the injection printing phase no deflection movements of the needle can occur. If the injection pressure drops, the guide bush releases the needle again, which can be brought immediately into its closed position.

Advantageously, the region has at least one contact surface for the flowable material, which likewise lies at least in sections in the flow channel. The material to be processed can therefore act directly on the contact surface and actuate the guide bush in this area as a check valve.

In terms of construction, it is advantageous if the region with the contact surface projects radially or axially into the flow channel. This not only simplifies the structure of the guide bush, but also their installation, which has a favorable overall effect on the manufacturing and assembly costs.

Particular advantages arise when the area and / or the contact surface is surrounded on all sides by flowable material. The latter can thereby act evenly on the guide bushing or on the contact surface, so that the region projecting into the flow region is pressed uniformly over the entire circumference of the closure needle. The needle is sealed on all sides and centered in its central position. This also contributes, if the area has a cylindrical inner circumference, which is aligned coaxially to the closure needle. This inner circumference thus forms not only a sealing surface between the needle and the guide bush, but also a centering element for the needle.

In order for the pressure to act directly on the sealing surface or centering element, the cylindrical inner circumference and the contact surface lie substantially axially at a height, i. the cylindrical inner circumference is also directly in the flow channel.

An advantageous development provides that the region projecting into the flow channel forms an end region of the guide bush, wherein the contact surface is formed by the outer circumference of the region. This also allows a simple and inexpensive design of the guide bush, which can be preferably manufactured as a turned part. In order to ensure a uniform pressing of the guide bush, the outer periphery of the end region is preferably an inclined surface, preferably a conical surface. This not only improves the contact with the flowable material. At the same time, the wall thickness of the end region, which can always be reliably compressed radially, is reduced. It may be advantageous if the conical surface is concave or convex.

According to a further aspect of the invention, the guide bush at an axial distance from the region projecting into the flow channel has at least one further region which has a cylindrical inner circumference aligned coaxially with the closure needle, the preferably superimposed end regions receiving the closure needle with the least possible movement play. As a result, the locking needle is always held and guided exactly in a central position, so that deflections from the central position are effectively avoided, at least in the guide area.

A space formed between the end portions, the inner diameter of which is slightly larger than the outer diameter of the shutter needle, provides lubrication of the guide sleeve slidably guided in the guide needle through the material to be processed, which reduces the frictional forces in the guide bushing.

The end regions and the free space preferably form a central through-bore.

Another important embodiment of the invention provides that the guide bushing is arranged in the distributor plate. However, the guide bush can also be arranged alternatively or additionally in the needle valve nozzle. In any case, the guide bush is preferably located in a recess in the distributor plate and / or in the needle valve nozzle, wherein the guide bush is fixable in the recess.

Thus, no material can escape through the recess through the tool, the guide bush is sealed within the recess over at least one surface perpendicular to the longitudinal axis, wherein the surface preferably forms the bottom of the recess.

For handling and fixing the guide bush, it is advantageous if this has a flange which sits centrally in the recess. On the flange is a Neck portion formed, which carries or forms the ends projecting into the flow channel area.

If the wall thickness of the end region as a whole selected smaller than the wall thickness of the neck portion, the end portion is extremely uniformly radially compressed during each injection process. The inner circumference of the end portion defines like a valve positively about the outer periphery of the locking needle, so that no more material from the Strornungskanai penetrate into the socket 30 and thus can escape to the outside.

The flange and the neck portion are preferably in one piece. But you can also train them separately and from different materials.

Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. Show it:

Fig. 1 is a partial schematic representation of an injection molding apparatus with a sealing arrangement for a closure needle, partially in section, and

FIG. 2 is a separate sectional view of the seal assembly of FIG. 1. FIG.

The generally designated 1 in Fig. 1 injection molding apparatus is used for the production of moldings from a flowable material, such as a plastic melt. It has a clamping plate 2 and parallel to a distributor plate 3, in which a system of flow channels 4 is formed. These each open in a (not shown) needle valve nozzle, which is mounted on the underside 5 of the distributor plate 3.

Each needle valve nozzle has a (also not shown) preferably externally heated nozzle body, in which concentric to the longitudinal axis L, a material tube for the continuation of the flow channel 4 is formed. The latter ends in a nozzle orifice, which forms at the end a nozzle outlet opening, through which the material to be processed is fed through a gate opening to a separable (also not shown) mold insert.

In order to open and close the sprue opening, which is preferably formed in the mold insert, a closure needle 20 is provided, which seals the flow channel in the needle valve. shut-off nozzle and a portion of the flow channel 4 in the distributor plate 3 longitudinally interspersed and by a (not shown) mechanical, electric, pneumatic or hydraulic drive in a closed and open position can be brought. In the closed position, the closure needle 20 engages sealingly into the gate opening with a closure part (not shown) at the end side through the nozzle outlet opening.

In the area of the tool, the Verschiußnadei 20 through the distributor plate 3 and the platen 2 through connected to the drive, wherein the needle 20 ends end carries an adapter 22 which is provided with an angularly rectangular in cross-section end portion 23. This serves to attach a (not shown) tool to mount the needle 20 and adjust in length can. By means of a (not shown) lock nut, the needle 20 can fix rotationally fixed.

To carry out the sealing needle 20, a through hole 6 is introduced in the clamping plate 2, whose inner diameter is greater than the outer diameter of the locking needle 20th

In the platen 2, a cleaning device 10 for the locking needle 20 is further formed. This has a housing 11 with a substantially cylindrical wall and an end formed, radially inwardly recessed flange rim 13. This carries axially a plurality of disc-shaped cleaning elements 40, which are held at the edges by annular spacers 14 at regular intervals. To secure the trained as a flat body cleaning elements 40 and the intermediate spacers 14 within the cleaning device 10 is a locking ring 15, which is preferably screwed axially into the housing 1 1 is used.

Each cleaning element 40 is provided centrally with an opening (not shown) for passing the sealing needle 20. The inner diameter of the opening is chosen so that the edge formed by the opening with the outer periphery 24 of the locking needle 20 is form and frictionally in contact. On the outer circumference 24 of the closure needle 20 adhering material residues, for example, from the guide bush 30, are thereby always reliably detected by the shape-matched edges of the cleaning elements 40 and removed from the needle 20, that is, by the cleaning device 10 and by the cleaning Elements 40 guided Verschlußnadel 20 is kept clean during operation of the injection molding device 1 at each reciprocation.

In the distributor plate 3 is seated as a needle seal, a guide bush 30 with a central through hole 31 whose inner diameter corresponds to the outer diameter of the closure needle 20 in end regions 32, 33 of the beech 30 to a small movement play. The latter thus finds within the socket 30 a central guide and support.

Between the end and guide portions 32, 33, a cylindrical free space 34 is formed axially, whose inner diameter is slightly larger than the outer diameter of the closure needle 20. He takes during operation of the injection targeted a small amount of flowable material from the flow channel 4, which to seal the sealing needle 20 against the flow channel 4 and the tool environment leads. At the same time, the flowable mass within the clearance 34 acts as a lubricant, so that the friction between the locking needle 20 and the guide bushing 30 is reduced. The latter is - as well as the through hole 6 in the platen 2 - coaxial with the locking needle 20 and to its longitudinal axis L.

The guide bush 30 has a widened flange 35, which sits centrally in a recess 36 in the distributor plate 3. Above the flange 35, the bushing 30 (in the direction of the platen 2) has a smaller main body 38, which forms the (upper) guide region 32 at the end. This encloses the locking needle 20 with its cylindrical inner circumference 42 except for a slight movement play. At the same time he limits the cylindrical space 34 upwards so that the material therein can not escape to the outside.

The main part 38 is coaxially enclosed by a screw bush 37. This has an external thread 47, which engages in a corresponding internal thread 56 of the recess 36. Turning the screw bushing 37 into the recess 36 and thus into the distributor plate 3, the bush 30 is fixed in the tool. The bottom 41 of the recess 36 and the (unspecified) underside of the flange 35 lie positively against one another, so that the guide bushing 30 is not only fixed in the distributor plate 3, but at the same time is sealed over a surface perpendicular to the longitudinal axis L. Below the flange 35, the bushing 30 (in the direction of needle valve nozzle) has a neck portion 39, the outer diameter of which is also smaller than the outer diameter of the flange 35. The lower end of the neck portion 39 forms the (lower) guide region 33, which has its cylindrical inner circumference 43 the closure needle 20 encloses up to a small movement play and the cylindrical space 34 is limited accordingly downwards. Here, as FIG. 2 shows in more detail, the wall thickness W of the end or guide region 33 is preferably smaller than the wall thickness U of the shark section 39. In addition, the outer circumference 44 of the region 33 forms an inclined surface 44, preferably at the level of the inner circumference 43 a conical surface, so that the wall thickness W to the needle valve nozzle even further decreases.

For receiving the neck portion 39 in the distributor plate 3, a through bore 46 is introduced between the recess 36 and the flow channel 4, whose inner diameter substantially corresponds to the outer diameter of the neck portion 39. This extends as far as the flow channel 4, wherein the end region 33 with its locking needle 20 enclosing inner circumference 43 and its conical surface 44 projects radially and concentrically to the longitudinal axis L in the flow channel 4 inside. The guide portion 33 for the locking needle 20 is thus completely in the mass flow wherein the inclined or conical surface 44 forms a contact surface for the material, which - as well as the locking needle 20 - is lapped in the flow channel 4 on all sides of the material to be processed.

The operation of the needle seal or the guide bushing 30 is based essentially on the elastically deformable wall of the flow channel 4 lying end portion 33. If the locking needle 20 is opened, it slides first within the guide bush 30 unhindered from the closed position to the open position, the end portions 32nd , 33 slide along the outer circumference 24 of the needle 20 with little play. If this has reached its end or open position, the injection pressure is built up, that is, the melt to be processed is pressed at high pressure through the melt channel 4 into the mold cavity. The flowable mass flows around the closure needle 20 and the contact surface 44 of the end portion 33 uniformly from all sides, wherein the end portion 33 is radially compressed due to its relatively low wall thickness. The cylindrical inner circumference 43 lays like a closing or valve member positively and sealingly against the outer periphery 24 of the closure needle 20, so that no material from the flow channel 4 in the free space 34 of the guide bush 30 during the injection process can penetrate. The sealing of the closure needle 20 is thus significantly improved over conventional constructions, because at the time of high pressure load in the flow channel 4 no material can penetrate through the guide bush 30 through out of the tool to the outside. At the same time, the needle 20 is fixed concentrically to the longitudinal axis L in position. It can no longer be deflected by the flowing material from its central position, which has a favorable effect on the flow conditions in the flow channel 4.

Once the injection cycle has ended, the pressure in the flow channel 4 is reduced again. Due to its elasticity, the end region 33 returns to its original shape and the inner circumference 43 of the end region 33 separates from the outer circumference 24 of the closure needle 20. This can be moved unhindered into the closed position.

It can be seen that the wall thickness W of the preferably made of a steel material end portion 33 is selected so that it is deformable in the elastic range of the material and that while the slight movement between the locking needle 20 and the inner circumference 43 is overcome by the material pressure, so that during the high pressure phase in the tool, the needle 20 is locked in the middle and no material can escape to the outside. Nevertheless, the needle 20 is precisely guided between the individual printing cycles within the spaced-apart end regions 32, 33.

The invention is not limited to one of the above-described embodiments, but can be modified in many ways. For example, the guide bush 30 need not necessarily be arranged in the distributor plate 3. Rather, it can also be mounted in the needle valve nozzle, for example in the nozzle body, which is mounted on the underside 5 of the distributor plate 3. The latter has for this purpose a simple through hole for smooth implementation of the locking needle 20 to the drive, while the nozzle head is provided at the end with the recess 36 for receiving the guide bushing 30 and the threaded bush 37. The neck portion 39 of the sleeve 30 projects axially into the Materiairohr, while the flow channel 4 opens immediately below the side of the material pipe. As a result, the end region 33, which is preferably reduced with respect to the neck section 39 in the outer diameter, lies axially in the flow region. Whose Kontaktfiäche 44 is - as well as the sealing needle 20 - flows around on all sides of the material to be processed, so that the resulting pressure in the flow channel 4 compressively acting as a kind of check valve end portion 33 and sealingly against the outer periphery 24 of the locking needle 20th can squeeze. The flow channel 4 is thereby completely sealed during the injection process to the outside. The needle 20 is fixed in its central position.

The wall thickness W of the end or guide region 33 does not necessarily have to be smaller than the wall thickness U of the neck portion 39. Both may also have approximately the same wall thickness. It is only important that the flowing around the flowable material end portion 33 during the high pressure phase can elastically deform so far that the inner circumference 43 sealingly around the Außenurnfang 24 of the Verschieuß- needle 20 sets.

The optionally formed at the end of the end portion 33 contact surface 44 may also be concave or convex, which can also be easily and precisely finished. The surface course has a favorable effect on the pressure distribution.

To fix the guide bush 30 in the tool 1, instead of the screw bushing 37, it is also possible to use a flange ring (not shown), which is fixed by means of screws to the distributor plate 3 or to the needle valve nozzle. It is important that the guide bush 30 is sealed within the recess 36 via at least one surface 41 perpendicular to the longitudinal axis L.

The flange 35, the main part 38 and the neck portion 39 are preferably in one piece. But one can also form the main part 38 and / or the neck portion 39 separately and connect, for example by means of a screw connection with the flange 35. This would make the neck portion 39 with the end portion 33 and the remaining parts of the guide bush 30 made of different materials. Or you can replace the neck portion 39 in the processing of abrasive media at any time when needed for a new element without having to replace the entire guide bushing 30.

All of the claims, the description and the drawings resulting features and advantages, including design details, spatial arrangements and method steps may be essential to the invention both in itself and in various combinations. Reference number list

L longitudinal axis 36 recess

U wall thickness 37 threaded bush

W wall thickness 38 main part

39 neck section

-J injection molding equipment

2 clamping plate 40 cleaning element

3 distributor plate

4 flow channel 41 ground

5 bottom 42 inner circumference

6 Through hole 43 Inner circumference

44 contact surface / outer circumference / inclined surface

10 cleaning device

46 Through hole 11 Housing 47 Male thread 14 Spacer 56 Female thread 15 Circlip

20 locking needle

22 adapters

23 end section

24 outer circumference

30 guide bush

31 through-hole

32 end / leadership area

33 end / leadership area

34 free space

35 flange

Claims

protection claims

1. injection molding apparatus (1) with a distributor plate (3), in which at least one flow channel (4) is formed for a flowable material, with at least one needle valve nozzle, through which the flowable material with continuation of the flow channel (4) can be fed to a separable mold insert , with at least one closure needle (20), which passes through the flow channel (4) longitudinally displaceable at least in sections and which can be brought into an open position and into a closed position by means of a drive, and with a guide bush (30) for the passage and sealing of the closure needle (20 ), dadu rch geken nzeich net, that the guide bush (30) has at least one region (33), which comprises the closure needle (20) with little play and at least partially in the flow channel (4).

2. Injection molding apparatus according to claim 1, dadu rch geken nzeich net, that the region (33) has at least one contact surface (44) for the flowable material or forms, at least in sections in the flow channel (4).

3. Injection molding apparatus according to claim 1 or 2, dad u rch geken nzeich net, that the region (33) projects radially or axially into the flow channel (4).

4. Injection molding apparatus according to one of claims 1 to 3, dadu rch geken n draw net, that the region (33) has a cylindrical inner circumference (43) which is aligned coaxially with the closure needle (20).

5. Injection molding apparatus according to claim 4, dadu rch geken nzeich net, that the cylindrical inner circumference (43) and the contact surface (43) are axially substantially at a height.

6. Injection molding apparatus according to one of claims 1 to 5, characterized in that the region (33) forms an end region of the guide bush (30).

7. Injection molding apparatus according to one of claims 1 to 6, dad u rch geken nzeich net, that the contact surface (44) from the outer periphery of the region (33) is formed.

8. Spπtzgjeßvorrichiung according to claim 7, dad u rch geken net nets that the outer circumference (44) is an inclined surface, preferably a conical surface.

9. Injection molding apparatus according to claim 8, dad u rch geken nzeich net that the conical surface (44) is concave or convex.

10. Injection molding apparatus according to one of claims 1 to 9, characterized in that the guide bush (30) has at least one further region (32) at an axial distance from the region (33) projecting into the flow channel (4). comprising a coaxial with the closure needle (20) aligned cylindrical inner periphery (42).

1 1. Injection molding apparatus according to claim 10, dadu rch geken nzeich net that the end portions (32, 33) receive the locking needle (20) with the least possible movement play.

12. Injection molding apparatus according to claim 10 or 11, dad u rch Geken nzeichnet that between the end regions (32, 33) is a free space (34) is formed, whose inner diameter is slightly larger than the outer diameter of the closure needle (20).

13. Injection molding apparatus according to one of claims 10 to 12, dadu rch geken net nets that the end regions (32, 33) and the free space (34) form a central through hole (31).

14. Injection molding apparatus according to one of claims 1 to 13, dad u rch geken net nets that the guide bush (30) in the distributor plate (3) is arranged.

15. Injection molding apparatus according to one of claims 1 to 13, dadu rch geken nzeich net, that the guide bush (30) is arranged in the needle valve nozzle.

16. Injection molding apparatus according to one of claims 1 to 15, dadu rch geken nzeich net, that the guide bush (30) in a recess (36) in the distributor plate (33) and / or in the needle valve seat sits.

17. Injection molding apparatus according to claim 16, characterized in that the guide bushing (30) can be fixed in the recess (36).

18. Injection molding apparatus according to claim 16 or 17, dadu rch geken nzeich net, that the guide bush (30) within the recess (36) over at least one surface (41) perpendicular to the longitudinal axis (L) is sealed.

19. Injection molding apparatus according to claim 18, characterized in that the surface (41) is the bottom of the recess (36).

20. Injection molding device according to one of claims 16 to 19, dadu rch geken nzeich net, that the guide bush (30) has a flange (35), which sits centrally in the recess (36).

21. Injection molding apparatus according to one of claims 16 to 20, dadu rch gekennzeich net, that the guide bush (30) has a neck portion (39), which carries or forms the end of the region (33).

22. Injection molding apparatus according to claim 21, dadu rch geken nzeich net, that the wall thickness (W) of the end portion (33) is smaller than the wall thickness (U) of the neck portion (39).

23. Injection molding apparatus according to claim 21 or 22, dadu rch geken Nzeichnet that the flange (35) and the neck portion (39) are integral.