OVERTURNING DEVICE FOR OVERTURNING MOLTEN MATERIAL AND PURGING METHOD

Abstract

The present invention relates to an overturning device (10) for overturning a molten material (200) in a melt channel (110) comprising a melt inlet (20) and a melt outlet (30), wherein between the melt inlet (20) and the melt outlet (30) at least one melt guiding means (40) is assembled for a rearrangement of molten material (200) from the centre (22) of the melt inlet (20) to the edge (34) of the melt outlet (30) and for a rearrangement of molten material (200) from the edge (24) of the melt inlet (20) into the centre (32) of the melt outlet (30).

Claims

1. An overturning device for overturning a molten material in a melt channel comprising: a melt inlet, a melt outlet, and at least one melt guide between the melt inlet and the melt outlet for a rearrangement of the molten material from a centre of the melt inlet to an edge of the melt outlet and for a rearrangement of the molten material from the edge of the melt inlet into the centre of the melt outlet.

2. The overturning device according to claim 1, wherein the at least one melt guide comprises a separation section with a first separation channel and a second separation channel, wherein in front of the separation section a division section for separating the molten material to the separation channels and after the separation section a combination section for merging the molten material from the separation channels is arranged.

3. The overturning device according to claim 2, wherein the combination section is configured for a central merging of edge sections of the molten material.

4. The overturning device according to claim 2, wherein the separation channels are configured in form of a curve.

5. The overturning device according to claim 2, wherein the separation channels comprise an equal or mainly equal length.

6. The overturning device according to claim 2, wherein the flow direction of the molten material comprises a sharp angle in the combination section with the flow direction of the molten material in the division section.

7. The overturning device according to claim 2, wherein the separation channels comprise a curvature which alters the flow direction of the molten material at least partially in contrast to the flow direction of the molten material in the division section about more than approximately 90°.

8. The overturning device according to claim 2, wherein the separation channels comprise a separation wall which is newly emerging by the separation and an outer wall which is taken over from the separation section, wherein the outer walls of the separation channels are merged in the combination section and the separation walls are merging into the outer wall of the combination section.

9. The overturning device according to claim 2, wherein the separation channels configure at least partially a spiral form with one another.

10. The overturning device according to claim 1, wherein a shifting device is provided for a shifting of the overturning device between a first position in which the melt inlet and the melt outlet are in a fluid communicating connection with the melt channel, and a second position in which the melt inlet and the melt outlet are separated from the melt channel.

11. The overturning device according to claim 1, wherein the free flow area of the melt guide corresponds or mainly corresponds with at least a free flow area of the melt inlet or the free flow area of the melt outlet.

12. A blow head for performing a blow film extrusion method comprising: at least a melt channel for conveying of molten material to a blow output of the blow head, wherein in the at least one melt channel at least one overturning device for overturning a molten material in a melt channel comprising a melt inlet, a melt outlet, and at least one melt guide between the melt inlet and the melt outlet for a rearrangement of molten material from a centre of the melt inlet to an edge of the melt outlet and for a rearrangement of molten material from the edge of the melt inlet into the centre of the melt outlet is assembled.

13. The blow head according to claim 12, p1 wherein neighbouring separation channels of neighbouring overturning devices are newly combined to melt channels.

14. A method for the performance of a purge process in an extrusion device comprising: introducing of a molten material in a melt inlet of an overturning device, rearranging of molten material from a centre of the melt inlet to an edge of a melt outlet of the overturning device, and rearranging of molten material from the edge of the melt inlet into the centre of the melt outlet.

15. The Overturning device according to claim 4, wherein the separation channels are configured in form of a curve by configuration of a torus shape.

Description

[0037] Further advantages, features and details of the invention result from the subsequent description in which in relation to the drawings embodiments of the invention are described in detail. Thereby, the features described in the claims and in the description can be essential for the invention each single by themselves or in any combination. It is shown schematically:

[0038] FIG. 1 a schematic representation during a purge process of a known extrusion device,

[0039] FIG. 2 a situation according to FIG. 1 with the use of an overturning device according to the invention,

[0040] FIG. 3 a schematic representation of the effect of an overturning device according to the invention,

[0041] FIG. 4 a further embodiment of an overturning device according to the invention,

[0042] FIG. 5 a further embodiment of an overturning device according to the invention,

[0043] FIG. 6 an embodiment of an overturning device according to the invention,

[0044] FIG. 7 a further embodiment of an overturning device according to the invention,

[0045] FIG. 8 the embodiment of FIG. 8 in a multiple assembly,

[0046] FIG. 9 a further embodiment of an overturning device according to the invention,

[0047] FIG. 10 a further embodiment of an overturning device according to the invention,

[0048] FIG. 11 the embodiment of FIG. 10 in a further view,

[0049] FIG. 12 an embodiment of the blow head according to the invention, and

[0050] FIG. 13 a further embodiment of the blow head according to the invention.

[0051] In FIG. 1 a melt channel 110 in a flow direction from left to the right is shown like it is represented during the purge process. Within the melt channel 110 a free flow area 70 is provided through which molten material 200 flows. Here, it has to be differentiated between old molten material 220 and new molten material 210. It can be recognized that over the extended course of the melt channel 110 during the purge course a ramp- or cone-like configuration between the old molten material 220 and the new molten material 210 is configured. This cone moves during the purge time in the course towards the right until finally the greatest part of the old molten material 220 is put outwards and it can be further proceeded with the active production.

[0052] In FIG. 2 the mode of action of an overturning device according to the invention is shown. Here, a rearrangement from the edge of the molten material 200 into the centre of the molten material 200 and vice versa occurs. At the melt inlet 20 of the overturning device 10 accordingly material from the edge of the molten material 200 is received and is provided in the centre at the melt outlet 30. In an inverse manner fresh or new molten material 210 is guided from the centre of the melt inlet 20 to the edge of the melt outlet 30. Like it can be recognized therewith the adjusted amount of old molten material 220 is reduced at the right edge of the melt channel 110. The representation of FIG. 2 occurs at the same time during the purge process like FIG. 1.

[0053] FIGS. 3 and 4 show the possibility of a rearrangement provided by a separation functionality. Starting from a melt channel 110 according to FIG. 7 by the division section 47 a division of the molten material 200 to two separation channels 46a and 46b of the separation section 46 occurs. This leads schematically to a distribution according to FIG. 6. While starting from melt channel 110 completely entirely old molten material 220 encloses the new molten material 210, by the separation in the separation channels 46a and 46b only approximately half of the extent is covered with old molten material 220. The other half is provided in the separation channels 46a and 46b at the edge with already new molten material 210. In case now by skilful combining a central merging of both separation channels 46 for the edge areas with an old molten material 220 is performed, likewise a complete or at least partial rearrangement according to the invention can occur by this separation function.

[0054] FIG. 5 shows schematically a possible further embodiment of an overturning device 10 with this separation functionality. Here, a separation to in total four separation channels 46a and 46b occurs and a recombination in a combination section 48. Schematically, further the corresponding distribution of old molten material 220 and new molten material 210 is shown in a corresponding channel. After the combination or merging at the combination section 48 the edge sections with old material 220 are completely in the centre such that the extension edge in the melt channel 110 is mainly completely configured by new molten material 210. Naturally, six or more separation channels are possible within the scope of the present invention.

[0055] In FIG. 6 schematically the possibility is shown how the single overturning devices 10 can be in connection with one another. Thus, here a star-like representation is provided with which starting from the centre channel a plurality of star-like melt channels 110 are separated from downwards. Each melt channel 110 is configured with an overturning device 10 which comprises a separation section 46. Via corresponding division sections 47 each star-like melt channel 110 is separated in two separation channels 46a and 46b. Accordingly, subsequently in the respective combination section 48 a merging of the separation channels 46a and 46b occurs. The combination sections 48 however combine separation channels 46a and 46b which are previously separated in different melt channels 110. Therewith, a half separation offset in extent direction can be achieved according to the combination sections 48. This leads to an already repeatedly described particularly efficient combination possibility, wherein in the right part of FIG. 6 the rearrangement according to the invention of the old molten material 220 can be performed at the edge into the centre.

[0056] In FIG. 7 schematically a solution is shown which comprises the curved separation channels 46a and 46b. These separation channels are here configured mainly with the same length and mainly with the same curves. The separation channels 46a and 46b of the separation section 46 configure with this embodiment mainly a form of a torus. Simultaneously, it can be recognized that between the flow direction SR in front of the division section 47 and after the combination section 48 a sharp angle is adjusted. Schematically, here the distribution or the rearrangement of the old molten material 220 can be recognized with the corresponding arrows. The FIG. 8 shows the combination of an overturning device 10 in a star-like layout like it was already described according to FIG. 7.

[0057] In FIG. 9 a further solution of an overturning device 10 according to the invention is shown. Here, mainly a layout in form of a heart and combination of the single separation channels 46a and 46b occurs. Like it can be recognized, a rearrangement of the flow direction SR of the molten material between the separation section 47 and the combination section 48 of approximately 90° occurs. This leads to the compact construction such that by the mainly completely deflection of the molten material 200 the combination section 48 can be arranged between the separation channels 46a and 46b.

[0058] FIGS. 10 and 11 show a solution with which the single separation channels 46a and 46b are spirally interwoven with one another, wherein here four separation channels 46a and 46b are provided. This leads to a corresponding combination which likewise provides the old molten material 220 from the edge in the centre in the combination section 48.

[0059] In FIG. 12 it is shown how an overturning device 10 can be assembled in a melt channel 110 in a blow head 100. Thereby, here any of the described embodiments of the overturning devices 10 can be applied. Thereby, the blow head 100 comprises a ring-like blow output 112.

[0060] FIG. 13 shows a solution similar to FIG. 12, wherein however here a shifting device 60 is shown for the overturning device 10. According to FIG. 12 the turning device 10 is in the second position and therewith outside a fluid communicating intervention with the melt channel 110. This is the operation position. For the purge situation the overturning device 10 is inserted into the melt channel 110 via the shifting device 60 and therewith the functionality according to the invention for the reduction of the purge time can be provided.

[0061] The previous description of the embodiments describes the present invention only within the scope of examples. Naturally, single features of the embodiments as far as technically meaningful can be freely combined with one another without leaving the scope of the present invention.

REFERENCE SIGNS

[0062] 10 Overturning device [0063] 20 Melt inlet [0064] 22 Centre of melt inlet [0065] 24 Edge of melt inlet [0066] 30 Melt outlet [0067] 32 Centre of melt outlet [0068] 34 Edge of melt outlet [0069] 40 Melt guiding means [0070] 46 Separation section [0071] 46a First separation channel [0072] 46b Second separation channel [0073] 47 Division section [0074] 47a Separation wall [0075] 47b Outer wall [0076] 48 Combination section [0077] 48b Outer wall [0078] 60 Shifting device [0079] 70 Free flow area [0080] 100 Blow head [0081] 110 Melt channel [0082] 120 Blow output [0083] 200 Molten material [0084] 210 New molten material [0085] 220 Old molten material [0086] SR Flow direction of the molten material