MULTI-LAYER BLOWING HEAD FOR A BLOWN FILM INSTALLATION, BLOWN FILM INSTALLATION, AND METHOD FOR OPERATING A BLOWN FILM INSTALLATION

Abstract

The invention relates to a multi-layer blowing head for a blown film installation, to a blown film installation, and to a method for operating a blown film installation. Specifically, according to the invention, a component is included on the opposite side of a distributor plate of a distributor plate set for a spiral distributor, wherein part of the spiral distributor is formed out of the opposite side of a distributor plate. The blowing head according to the invention for forming a multi-layer melt flow makes it possible, in the case of suitable operating parameters, to prevent the occurrence of spiral strips or at least to make said spiral strips less pronounced.

Claims

1. blowing head for a blowing film installation, for forming a multi-layered annular melt stream in a ring channel by means of several set of spirals leading in the direction of the ring channel, and for exiting the melt stream from a ring slit nozzle for forming a film hose pipe, wherein the ring channel leads in an extrusion direction to the ring slit nozzle, with a distributor plate package, which forms a pre-distributor, a set of spirals and a distribution plate channel, wherein in a distribution flow direction the pre-distribution leads over the set of spirals and the distributor plate channel into the ring channel, wherein the set of spirals comprises a spiral channel exit direction, which is arranged parallel to the extrusion direction in or against the extrusion direction, wherein a first set of spirals is arranged with respect to the extrusion direction of the blowing head is at least partially disposed upstream of a first distributor plate channel, wherein the spiral channel exit direction of this part points in the extrusion direction, or the spiral channel exit direction of a first set of spirals points radially outward with respect to the extrusion direction at least partially, characterized in that a second set of spirals is arranged with respect to the extrusion direction of the blowing head at least partly downstream of a second distributor plate channel, wherein the spiral channel exit direction of this part points in the extrusion direction.

2. Blowing head according to claim 1, characterized in that the second set of spirals is arranged in consideration of a volume predominantly, preferably completely, in relation of the extrusion direction downstream of the distributor plate channel.

3. Blowing head according to claim 1, characterized in that the second set of spirals is predominantly arranged in a channel course view, preferably completely, downstream of the distributor plate channel with respect to the direction of extrusion.

4. Blowing head according to claim 1, characterized in that the second set of spirals is arranged in a channel course view, at least a last third of the channel course, downstream of the distributor plate channel, preferably at least a second half, in particular the entire channel course.

5. Blowing head according to claim 1, characterized in that the distribution plate package consists of layered plates in extrusion direction, wherein, in any case, the plate which is arranged downstream with respect to the extrusion direction plate comprises the set of spirals as recesses.

6. Blowing head according to claim 5, characterized in that the distributor plate package consists of stacked plates in the direction of extrusion, wherein, anyway, with respect to the extrusion direction, the downstream plate of the distribution plate package comprises a set of spirals and comprises the distributor plate channel as recesses.

7. Blowing head according to claim 1, characterized in that, with respect to the extrusion direction, the downstream plate of the distribution plate package forms the outermost laying channel in relation to the ring channel.

8. Blowing head according to claim 1, characterized that the blowing head comprises in addition to the distribution plate package described above another distributor plate package.

9. Blowing head according to claim 1, characterized that the blowing head comprises in addition to the distribution plate package described above an axial spiral distributor part.

10. Blowing head according to claim 8, characterized in that the distributor plate package is arranged on top.

11. Blowing film installation with a blowing head according to claim 1.

12. Method for operating a blowing film installation for forming a multilayered annular melt stream in a ring channel by means of several, in the direction ring channel leading, set of spirals, and for exiting the melt stream through a ring slit nozzle to form a film hose pipe, wherein the ring channel leads in an extrusion direction to the ring slit nozzle, wherein the layers of the film hose pipe are produced with a distributor plate package and melt is guided through by a pre-distributor for each melt, and is guided by a set of spirals and a distributor plate channel, wherein in a distribution flow direction the pre-distribution leads over the set of spirals and over the distributor plate channel into the ring channel, wherein the melt in guided through a set of spirals in spiral channel exit direction parallel to the extrusion direction or against the extrusion direction, wherein the melt of a first layer is guided, with respect to the extrusion direction of blowing head at least in part by an upstream of a first distributor plate channel arranged set of spirals in the extrusion direction of the blown head, or the melt of a first layer is guided, at least partially, with respect to the extrusion direction of the blowing head radially outward, characterized in that the melt of a second layer is guided with respect to the extrusion direction of the blowing head, at least in part, by a downstream of a second distributor plate channel set of spirals arranged against the extrusion direction of the blowing head.

Description

[0085] The invention will be explained below with reference to an exemplary embodiment explained in more detail on the drawing. There is shown:

[0086] FIG. 1 shows schematically in a radial section one half of a plate distributor with spiral coil distributor, at which melt is fed outside in spiral channels and an annular melt stream is generated, and

[0087] FIG. 2 shows schematically in a radial section one half of a blowing head of two distribution plate packages with spiral coil distributors, in which melt is fed outside in spiral channels and an annular melt stream is generated.

[0088] The distribution plate package 1 in FIG. 1 consists essentially of a first distributor plate 2, a second distributor plate 3 and a counter plate 4. The distributor plates 2, 3 are just like the counter-plate 4 horizontally.

[0089] In the distributor plates 2, 3 a set of spirals 5, 6 (identified by way of example) are introduced.

[0090] All edges of the set of spirals 5, 6 and the edges of the distributor plates 2, 3 and the counter plate 4, which come into contact with the designated melt stream, can be rounded with respect to the risk of flow separation in the distributor plate package 1 (not shown).

[0091] At the distributor plate package 1, the plastic melt is guided in operation, starting from pre-distribution channels 7, 8 at the beginnings of set of spirals 9, 10. In a distribution flow direction 11, which is radially toward a central axis 12, while the central axis 12 is parallel with an extrusion direction 13, a channel depth of the the set of spirals 5, 6 decreases, wherein a distributor plate channel 14, 15 becomes larger in the course of the distribution flow direction 11.

[0092] A spiral channel exit direction 16 of the designated melt of the first distributor plate 2 is parallel to the direction and in the direction of the extrusion direction 13, wherein the set of spirals 5 of the first distributor plate 2 is located upstream of the distributor plate channel 14.

[0093] A spiral channel exit direction 17 of the designated melt of the second distributor plate 3 extents parallel to the direction and opposite to the direction of the extrusion direction 13, wherein the set of spirals 6 of the second distributor plate 3 is located downstream of the distributor plate channel 15.

[0094] A blowing head 30 in FIG. 2 consists essentially consists of a first distributor plate pack 31 and a second distribution plate pack 32, wherein the distribution plate packages extents horizontally.

[0095] The first distributor plate package 31 consists essentially of three distributor plates 33, 34, 35 and a counter-plate 36.

[0096] The second distributor plate package 32 also consists essentially of three distribution plates 37, 38, 39 and a counter plate 40.

[0097] In the distributor plates 33, 34, 35, 37, 38 are introduced set of spirals 41, 42, 43, 44, 45 (exemplary marked).

[0098] In the counter plate 40 are also introduced a set of spirals 46 (marked by way of example).

[0099] All edges of the set of spirals 41,42,43,44,45,46 and the edges of the distributor plates 33, 34, 35, 37, 38, 38 and the counter plates 36, 40, which with the designated melt stream comes into contact with regard to the risk of flow separation in the blowing head 30 are rounded (not shown).

[0100] In a distribution flow direction 47, which is radially toward a central axis 48, while the central axis 48 is parallel with an extrusion direction 49, a channel recess of the set of spirals 41, 42, 43, 44, 45, 46 decreases, wherein a distributor plate channel (schematically indicated, not numbered) in the course of the distribution flow direction 47 becomes larger.

[0101] The distribution plate packs 31, 32 are fed in operation with plastic melt starting from pre-distribution channels (not shown) in the distributor plates 33, 34, 35, 37, 38, 39. The designated plastic melt passes over the beginning of the set of spirals (not shown) in the set of spirals 41, 42, 43, 44, 45, 46.

[0102] A spiral channel exit direction 50 of the designated melt of the distributor plates 33, 34, 35, 37, 38 runs parallel to the direction and in the direction of the extrusion direction 49, wherein the set of spirals 41, 42, 43, 44, 45 (identified by way of example) of the distributor plates 33, 34, 35, 37, 38 is arranged upstream of the respective distributor plate channels (schematic indicated, not numbered).

[0103] A spiral channel exit direction 51 of the designated melt of the distributor plate 39 over the set of spirals 46 in the counter-plate 40 runs parallel to the direction and opposite the direction of the extrusion direction 49, wherein the set of spirals 46 (exemplary marked) of the distributor plate 39 is arranged downstream of the associated distributor plate channel 52 (indicated schematically).

LIST OF REFERENCE NUMBERS USED

[0104] 1 distribution plate package [0105] 2 first distributor plate [0106] 3 second distributor plate [0107] 4 counter plate [0108] 5 set of spirals [0109] 6 set of spirals [0110] 7 pre-distribution channel [0111] 8 pre-distribution channel [0112] 9 beginning of set of spirals [0113] 10 beginning of set of spirals [0114] 11 distribution flow direction [0115] 12 axis [0116] 13 extrusion direction [0117] 14 distribution plate channel [0118] 15 distribution plate channel [0119] 16 spiral channel exit direction [0120] 17 spiral channel exit direction [0121] 30 blowing head [0122] 31 first distributor plate package [0123] 32 second distribution plate package [0124] 33 distributor plate [0125] 34 distributor plate [0126] 35 distributor plate [0127] 36 counter plate [0128] 37 distribution plate [0129] 38 distribution plate [0130] 39 distribution plate [0131] 40 counter plate [0132] 41 set of spirals [0133] 42 set of spirals [0134] 43 set of spirals [0135] 44 set of spirals [0136] 45 set of spirals [0137] 46 set of spirals [0138] 47 distribution flow direction [0139] 48 axis [0140] 49 extrusion direction [0141] 50 spiral channel exit direction [0142] 51 spiral channel exit direction [0143] 52 distribution plate channel