EP2303539A2

EP2303539A2 - Injection molding nozzle for an injection molding tool

Info

Publication number: EP2303539A2
Application number: EP09776589A
Authority: EP
Inventors: Herbert Günther; Siegrid Sommer
Original assignee: Guenther Heisskanaltechnik GmbH
Current assignee: Guenther Heisskanaltechnik GmbH
Priority date: 2008-06-16
Filing date: 2009-05-07
Publication date: 2011-04-06
Also published as: TW201008751A; US20110117238A1; WO2010003473A3; WO2010003473A8; DE202008007918U1; WO2010003473A2

Abstract

The invention relates to an injection molding nozzle (10) for an injection molding tool, comprising a material tube (12) in which a flow channel (16) for a flowable material is configured in the axial direction (A), a nozzle tip (26) being inserted in the material tube (12) and extending the flow channel (16). In order to reduce temperature losses, at least one thermally insulating insulation device (32) surrounds the injection molding nozzle (10) and rests against the injection molding tool and at least partially surrounds the nozzle tip (26).

Description

Injection molding nozzle for an injection mold

The present invention relates to an injection molding nozzle for an injection molding tool according to the preamble of claim 1.

Injection molding dies are used in injection molding tools to supply a flowable material, such as a plastic melt, under high pressure to a separable tool block or to a mold insert of an injection molding tool.

For optimum performance, it is important to maintain the flowable mass at a predetermined temperature until entry into the mold cavity. For this we usually heat the material pipe with the help of a heating device. It is equally important, however, that the flowable mass solidifies shortly after it enters the mold insert of the injection mold, which is why the mold insert is cooled. Especially in the transition region from the nozzle tip to the mold insert, these requirements are contradictory because the nozzle tip should have a predetermined high temperature and the mold insert should have a predetermined low temperature.

BESTATIGUNGSKOPIE To solve this problem, for example, US-A-5, 028,227 proposes an injection molding, in which at the lower end of the material tube, a nozzle insert is inserted, which is supported against the mold insert of the injection mold and made of a heat highly conductive material. Within the material tube, and enclosed by the nozzle insert, there is provided an elongate, torpedo-shaped flow body which is also made of a heat-conducting material. This flow body comprises a flange-shaped, outwardly extending ring for fixing the flow body between the material tube and the nozzle insert, and longitudinally extending ribs which form channels for the flowable mass within the material tube. This flow body is intended to compensate for the temperature loss due to heat exchange occurring at the mating contact surfaces of the nozzle insert and the mold insert by directing heat from the material tube via the flow body directly into the gate region.

A similar approach is described in DE-A-31 24 909. This discloses an injection molding in which a nozzle seal is disposed of a heat-conducting material between the material pipe and the mold insert of the injection mold. The nozzle seal has a cylindrical outer part whose peripheral surface is slightly conical. Further, the outer edge is slightly chamfered to reduce contact with the mold insert. Within the outer part, three ribs are formed, which extend radially to a longitudinal center pin. Passages for the melt are provided between the ribs. The center pin is conically formed at the end, with its tip protruding to the gate opening.

Another alternative construction of an injection molding nozzle is shown in US-A-4,450,999, which structure differs substantially from the structure described in DE-A-31 24 909 in that the center pin of the nozzle seal is formed separately from the outer part of the nozzle seal.

Based on this prior art, it is an object of the present invention to provide an injection molding of the type described above with an alternative structure, which allows a further optimization of the work result.

Main features of the invention are specified in the characterizing part of claim 1. Embodiments are the subject of claims 2 to 25. In an injection molding nozzle for an injection molding tool, with a material pipe in which a flow channel for a flowable material is formed in the axial direction, with a nozzle tip which is inserted into the material pipe and continues the flow channel in the intended state, is at least one thermally insulating insulating device provided, which at least partially surrounds the nozzle tip and rests in the intended condition of the injection mold.

In contrast to the aforementioned prior art, which aims to compensate for the heat transfer occurring between the nozzle tip and the mold insert of the injection molding tool by arranging the flow body, the present invention pursues the approach to prevent the heat loss by arranging a corresponding insulating device as far as possible. In this way at least equivalent work results can be achieved.

The insertion of the nozzle tip into the material pipe also allows a quick change of the nozzle tip during maintenance and / or repair work, with no other tools in the form of tools or the like are required to replace the nozzle tip.

Since the nozzle tip is supported in the direction of the tool against the insulating device, it is also not necessary to provide a stop for the nozzle tip within the material tube, which is why the pressure loss is correspondingly low. The melt channel provided inside the nozzle tip achieves an optimum flow behavior of the melt.

Overall, this results in a structurally simple structure that can be easily assembled and disassembled, the pressure conditions are positively influenced due to the arrangement of the nozzle tip in the material tube.

The at least one insulating device preferably comes into contact with the injection mold in a plane transverse to the axial direction, so that the insulating device and thus simultaneously the nozzle tip supporting thereon are positioned in the axial direction within the injection mold. Advantageously, the insulating device is designed to be such that it centers the nozzle tip and thus the injection molding within the injection mold. The at least one insulating device is advantageously releasably attachable to the nozzle tip. Accordingly, the insulating device and nozzle tip can be preassembled and used in the preassembled state in the injection mold. This facilitates the assembly and disassembly of the two components. The attachment of the insulating device to the nozzle tip can be done non-positively and / or positively. According to one embodiment of the present invention, the insulating device for this purpose can be fixed to the nozzle tip with at least one fixing means.

In order to define the insertion depth of the nozzle tip into the material pipe, the nozzle tip preferably has a flange edge on the circumference, wherein the nozzle tip is supported on the material pipe with the end face of the flange edge. On the outer circumference of the flange edge, the insulating device is preferably fixable. For this purpose, the flange edge is advantageously provided on its outer circumference with a recess which may be formed, for example, as a circumferential groove. In this recess can then fixative in the form of a screw, a bolt or the like. engage, so that the insulating device can be attached to the nozzle tip quickly and reliably. Due to the small footprint the screw is e.g. advantageously designed as a grub screw. Additionally or alternatively, the insulating device can also be pressed onto the flange edge or fastened to it in another way.

Advantageously, the insulating device is annular, so that it surrounds a large area of the nozzle tip and shields accordingly thermally.

The materials of the material tube and the nozzle tip are advantageously selected with regard to their thermal expansion coefficients such that contact surfaces of the material tube and the nozzle tip form a seal when the operating temperature is reached. As a result, the plastic material to be processed can not penetrate to the outside.

The material tube, the nozzle tip and the insulating device are also designed such that they can be mounted at room temperature with little play in each other. The components therefore have a clearance fit, which allows a simple and quick assembly and disassembly.

Furthermore, at least one separate seal is preferably provided between the material pipe and the nozzle tip, for example in the form of a sealing ring, so that leakage of the flowable mass between these components is additionally prevented. According to a preferred embodiment of the present invention, the nozzle tip has centrally in its passage opening a flow body, which is held by means of webs on a tubular base body of the nozzle tip. Similar to the prior art, this flow body serves to direct heat from the material pipe directly into the gate area. For this purpose, the flow body is preferably the end over the main body of the nozzle tip, so that it extends as close as possible to close to the gate or - if necessary - even in the gate opening protrudes.

The webs, which center the flow body within the nozzle tip, preferably divide the passage opening of the nozzle tip uniformly into channels, so that the flowable mass flows homogeneously through the nozzle tip. The result is an optimal flow behavior of the melt. The pressure loss inside the nozzle is extremely low.

Another important embodiment of the invention provides that the webs are formed in the upper region of the nozzle tip in such a way that the flow body projects freely through the main body in the lower region of the nozzle tip. As a result, the flow pattern of the melt within the nozzle tip is further improved; The material reaches almost perfectly into the mold cavity, whereby the so-called memory effect is almost completely eliminated. But even color changes can be carried out extremely quickly, which further has a favorable effect on the production costs.

The nozzle tip advantageously further comprises a further thermally insulating insulating device, which is preferably arranged between the material pipe and the injection mold in order to prevent a heat transfer between the material pipe and the injection mold as far as possible. The further isolating device is preferably designed such that it centers the injection molding nozzle within the injection mold.

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:

1 is a cross-sectional view of an injection molding nozzle according to an embodiment of the present invention;

FIG. 2 shows a detail enlargement of the detail designated by reference numeral 11 in FIG. 1; FIG. Fig. 3 is a bottom view of the nozzle tip of the injection molding nozzle shown in Fig. 1; 4 is an enlarged cross-sectional view of the nozzle tip.

FIG. 1 is a cross-sectional view showing an injection molding nozzle according to an embodiment of the present invention, indicated generally at 10. The injection molding nozzle 10 is intended for use in an injection molding apparatus (not shown) which serves to produce molded parts from a flowable mass, for example from a plastic melt. The injection molding apparatus usually has a platen and, in parallel thereto, a distributor plate in which a system of flow channels is formed. These open in several injection molding nozzles 10, which are mounted on the underside of the distributor plate. However, it is also conceivable to use individual nozzles, with the machine nozzle of the injection molding tool moving directly onto the injection molding nozzle 10.

In the embodiment of Fig. 1, the injection molding nozzle 10 has a material pipe 12 which is provided at its upper end with a flange-like connection head 14 through which the material pipe 12 is connected to the (not shown) distributor plate of the injection mold. Within the material pipe 12 extending in the axial direction A, a flow channel 16 for the flowable mass is formed centrally. The flow channel 16, which is preferably designed as a bore, has a material feed opening 18 in the connection head 14 which communicates with the flow channels of the distributor plate (or, alternatively, directly with the machine nozzle). To seal the material pipe 12 with respect to the distributor plate, a sealing ring 20 is provided in the connection head 14 concentric to the material supply opening 18, which, however, is omitted in the application of the individual nozzle. Also conceivable is the formation of an additional annular centering approach, which can facilitate the assembly of the material tube 12 to the injection molding.

On the outer circumference of the material tube 12, a heater 22 is arranged, which may be formed, for example, as thick-film heating, as conventional coil heating or as a cable heater. The heater 22 serves to heat the material pipe 12 and thus the melt flowing through the flow channel 16. To optimize the heat transfer to the melt, the material tube 12 is made of a heat conducting material, such as tool steel. The entire heater 22 is surrounded by a protective tube 24, which protects the heater 22 from damage and preferably thermally insulated to the outside. As shown in FIG. 2, a nozzle tip 26 is inserted into the lower end of the material tube 12. The nozzle tip 26 is made of a heat-conductive material, wherein the materials of the material tube 12 and the nozzle tip 26 are selected in terms of their thermal expansion coefficients such that the contact surfaces of the material tube 12 and the nozzle tip 26 form a seal upon reaching the operating temperature, so that the nozzle tip 26 is held firmly and fluid-tight in the material tube 12 when the operating temperature is reached. In addition, the material tube 12 and the nozzle tip 26 are formed so that they can be mounted together at room temperature with little play, so that the nozzle tip not only mounted quickly, but also can be dismantled just as easy as soon as the injection mold is cooled to room temperature.

The nozzle tip 26 has a tubular base body 27, which has a radially outwardly projecting flange edge 28 at the end. The material pipe 12 facing end face of this flange edge 28 forms a stop surface, which defines the insertion depth of the nozzle tip 26 into the material tube 12. Between the flange 28 and the material tube 12, a sealing ring 30 is still provided, which additionally seals the two components 12, 26 against each other.

As further shown in Fig. 2, between the nozzle tip 26 and the (unspecified) tool, a first insulating means 32 made of a heat poorly conductive material such as titanium is provided, which thermally separates the hot nozzle tip 26 and the cold tool from each other. It is designed as an annular sleeve which - placed on the flange edge 28 - surrounds a large part of the nozzle tube 26 projecting from the material pipe 12. It can further be seen that the sleeve 32 surrounds the peripheral region of the flange edge 28 and the end face of the flange edge 28 pointing away from the material tube 12, so that the nozzle tip 26 can not come into direct contact with the tool.

The isolator 32 is releasably secured to the nozzle tip 26 by means of grub screws 34, the grub screws 34 engaging through corresponding threaded holes (not designated) therethrough and engaging the flange 28. The threaded holes are introduced radially into the wall of the insulating device 32. In Fig. 2, two opposing screws 34 are shown. However, only one or more screws 34, for example four, can be used. In order to improve the hold of the insulating device 32 in the axial direction A further, is in the flange 28 of the Nozzle tip 26 a recess 36 is introduced in the form of a circumferential groove, which is in the amount of screws 34. The latter can thereby engage in the groove 36 and secure the insulating sleeve 32 to the nozzle tip 26.

The facing away from the material pipe 12 end face of the insulating device 32 is supported against a shoulder 38 of the injection molding tool, not shown, and is circumferentially with this paragraph 38 in direct contact, whereby the insulating device 32 is centered in the shoulder 38 of the injection mold. In this way, there is also a centering of the nozzle tip 26 and thus the entire injection molding nozzle 10 within the injection mold. As can be clearly seen in particular in FIG. 2, the insulating device 32 prevents direct contact between the nozzle tip 26 and the injection molding tool, so that both components are thermally insulated from one another.

Another insulating device 40 is arranged at the lower end on the outer circumference of the material tube 12. This further insulating device 40 is also made of a thermally poorly conductive material and serves to isolate the material tube 12 relative to the injection mold. Also via this insulating device 40, a centering of the material tube 12 can be carried out within the injection mold.

With the help of the insulating means 32 and 40, a heat transfer between the injection molding nozzle 10 and the injection mold is largely prevented. The only inserted into the material pipe 12 nozzle tip 26 can be replaced together with the preassembled insulating sleeve or the insulating ring 32 in case of need. But also the insulating ring 32 can be quickly and easily removed by loosening the screws 34 of the nozzle tip 26, for example, if only this is to be replaced.

To further compensate for the not entirely avoidable temperature loss in the nozzle tip 26, an elongated, substantially torpedo-shaped flow body 42 is formed centrally of the main body 27 of the nozzle tip 26, which is held centrally by means of webs 44 in the tubular body 27. This flow body 42 serves to direct heat directly from the material tube 12 in the region of the gate. In this case, the flow body 42 protrudes on both sides of the main body 27 with end tips 43, 45, wherein the lower end tip 43 extends to close to the gate opening or even extend into it. The webs 44, by means of which the flow body 42 is held in the nozzle tip 26 or in its base body 27, define channels 46 through which the flowable mass can flow. 4 shows a further advantageous embodiment of the invention, in particular the nozzle tip 26. Here, the webs 44 are formed shortened within the nozzle tip 26 or in the main body 27 in such a way that the webs 44 on the upper portion O of the nozzle tip 26th restrict. In contrast, in the lower region U of the nozzle tip 26, the flow body 42 projects freely through the main body 27 without any contact, so that the melt can flow in this region almost optimally. In particular, the orientation of the melt in the article surface is largely eliminated, so that the so-called memory effect can not occur. It can also be seen that the lower end tip 43 is formed significantly longer than the upper end tip 45, so that the lower end tip 43 projects relatively far beyond the flange edge 28 also.

In order to improve the flow conditions even further, the upper edge 271 and the lower edge 272 of the base body 27 is conical or funnel-shaped, so that the plastic melt as possible passes without loss of pressure from the flow channel 16 in the material tube 12 into the passage channels 46 of the nozzle tip 26.

The construction of the injection molding nozzle 10 shown in FIGS. 1 to 4 is advantageous in that, with the aid of the insulating devices 32 and 40, a heat transfer between the injection molding nozzle 10 and the injection molding tool is largely prevented. In addition, additional heat is conducted from the material tube 12 via the flow body 42 in the region of the gate, so that temperature losses that can not be prevented by the insulating device 32 in the sprue, can be compensated. Accordingly, a very good work result with the help of the injection molding nozzle 10 according to the invention can be achieved.

Since the nozzle tip 26 is merely inserted into the material tube 12 of the injection molding nozzle 10, it can be assembled and disassembled in a simple manner. Compared to a nozzle tip, which is screwed into a material pipe, also a pressure loss can be significantly reduced.

Due to the fact that the insulating device 32 is fixed to the nozzle tip 26, the insulating device and the nozzle tip can be pre-assembled, so that the arrangement of the injection molding nozzle 10 is simplified in the injection mold. It should be noted at this point that the attachment of the insulating device 32 to the nozzle tip 26 can also take place in a different manner. Thus, the insulating device 32nd Alternatively, be pressed onto the outer circumference of the flange edge 28 of the nozzle tip 26.

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

Injection nozzle 34 Grub screw

Material tube 36 recess / groove

Connection head 38 paragraph

Flow channel 40 insulation device

Feed opening 42 flow body

Sealing ring 43 end tip

Heating 44 footbridge

Protective tube 45 end tip

Nozzle tip 46 channel

body

Flange edge A axial direction

Sealing ring O upper area

Isolator U lower area

Claims

claims

1. injection molding nozzle (10) for an injection mold, with a material tube (12) in which in the axial direction (A) a flow channel (16) is formed for a flowable material, with a nozzle tip (26) in the material tube (12 ) is inserted and the flow channel (16) continues in the intended condition, and with at least one thermally insulating insulating device (32) which at least partially surrounds the nozzle tip (26) and rests in the intended condition of the injection mold.

2. Injection molding nozzle according to claim 1, characterized in that the insulating device (32) in a plane transversely to the axial direction (A) comes into contact with the injection mold.

3. Injection molding nozzle according to claim 1 or 2, characterized in that the insulating device (32) is designed such that it centers the nozzle tip (26) within the injection mold.

4. Injection molding nozzle according to claim 3, characterized in that the insulating device (32) is releasably attachable to the nozzle tip (26).

5. Injection molding nozzle according to claim 3 or 4, characterized in that the insulating device (32) non-positively and / or positively on the nozzle tip (26) is fastened bar.

6. Injection molding nozzle according to one of claims 3 to 5, characterized in that the insulating device (32) with at least one fixing means (34) on the nozzle syringe (26) is fixable.

7. Injection molding nozzle according to one of claims 3 to 6, characterized in that the nozzle tip (26) has circumferentially a flange edge (28).

8. Injection molding according to claim 7, characterized in that the nozzle tip (26) with the end face of the flange edge (28) on the material tube (12) is supported.

9. Injection molding nozzle according to claim 7 or 8, characterized in that the insulating device (32) on the flange edge (28) is fixable.

10. Injection molding nozzle according to claim 9, characterized in that the flange edge (28) is provided on its outer circumference with a recess (36).

11. Injection molding nozzle according to claim 10, characterized in that the recess (36) is formed circumferentially.

12. Injection molding nozzle according to one of claims 6 to 11, characterized in that the fixing means (34) is a screw which engages in the recess (36).

13. Injection molding nozzle according to one of claims 7 to 12, characterized in that the insulating device (32) is pressed onto the flange edge (28).

14. Injection molding nozzle according to one of claims 1 to 13, characterized in that the insulating device (32) is annular.

15. Injection molding nozzle according to one of claims 1 to 14, characterized in that the materials of the material tube (12) and the nozzle tip (26) are selected with respect to their thermal expansion coefficients such that contact surfaces of the material tube (12) and the nozzle tip (26 ) form a seal when the operating temperature is reached.

16. Injection molding according to one of claims 1 to 15, characterized in that the material tube (12), the nozzle tip (26) and the insulating device (32) are formed such that they are at room temperature with little play in each other mounted.

17. Injection molding nozzle according to one of claims 1 to 16, characterized in that between the material pipe (12) and the nozzle tip (26) at least one separate seal (30) is provided.

18. Injection molding nozzle according to one of claims 1 to 17, characterized in that the nozzle tip (26) centrally in its passage opening has a flow body (42).

19. Injection molding according to claim 18, characterized in that the flow body (42) by means of webs (44) is held on a tubular base body (27).

20. Injection molding nozzle according to claim 19, characterized in that the flow body (42) projects beyond the base body (27) at the end.

21. Injection molding nozzle according to one of claims 18 to 20, characterized in that the webs (44) subdivide the passage opening of the nozzle tip (26) into channels (46).

22. Injection molding nozzle according to one of claims 18 to 21, characterized in that the webs (44) are formed in such a way in the upper region (O) of the nozzle tip (26), that the flow body (42) the base body (27) in the lower region ( U) of the nozzle tip (26) protrudes freely.

23. Injection molding nozzle according to one of claims 1 to 22, characterized in that a further thermally insulating insulating device (40) is provided.

24. Injection molding nozzle according to claim 23, characterized in that the further insulating device (40) is arranged between the material pipe (12) and the injection mold.

25. Injection molding nozzle according to claim 23 or 24, characterized in that the further insulating means (40) centers the injection molding nozzle (10) within the injection molding tool.