Device and Method for Calibrating a Blown Film

Abstract

The invention relates to a device and a method for calibrating a blown film (6), said device comprising: a tubular region with at least one inner wall (55), through which region the blown film can be passed; a liquid reservoir (82), which can be used to provide a liquid and which is situated above the tubular region, the liquid being guidable between the inner wall (55) and the blown film; and a suctioning device (B), situated below the tubular region, for suctioning off at least part of the liquid from the blown film. At least one liquid-permeable element (92) is provided, said element surrounding at least parts of the periphery of the blown film (6). This device permits the distance of the liquid-permeable element from the main axis of the blown film to be altered.

Claims

1.-13. (canceled)

14. A device for cooling of a blown film, with a device for delivery of liquid to the outer wall of the blown film, wherein the film can be cooled with the liquid, with at least one diversion element for diversion of at least a part of the liquid from the blown film, wherein the diversion element surrounds at least parts of the blown film, wherein the device for delivery of liquid includes at least one film guidance element with at least one inner wall, which is arranged at least in part around the blown film and along which the blown film is guidable, wherein the at least one diversion element is arranged beneath the at least one film guidance element, that the interval which the diversion element assumes to the main axis of the blown film, is alterable, and that a diversion element is provided, which in the peripheral direction overlaps itself in partial areas, or that multiple diversion elements are provided, wherein one diversion element overlaps partial elements of at least one adjoining diversion element.

15. The device of claim 14, wherein above or in the upper area of the film guidance element a liquid reservoir is provided, with which the liquid can be made available, wherein especially the liquid can be directed between the film guidance element and the blown film.

16. The device of claim 14, wherein multiple diversion elements are provided, which in their totality completely surround the blown film.

17. The device of claim 14, wherein at least one support element that is movable relative to the blown film in the radial direction is provided, on which the diversion element is attached, or on which it is braced in the radial direction.

18. The device of claim 14, wherein a rail-and-slider arrangement is provided, with which the at least one diversion element is movable in the radial direction of the blown film.

19. The device of claim 14, wherein a drive is provided, which acts on drive force transmission media, with which a drive force can be transmitted to at least one diversion element for alteration of the interval.

20. The device of claim 14, wherein the drive force transmission means include at least one chain, which especially drives at least one follower, which acts directly or indirectly on the support element.

21. The device of claim 14, wherein the diversion element includes a plate provided with apertures, especially a metal plate.

22. The device of claim 14, wherein the surface of the diverting element facing the blown film includes a material made of fleece, felt and/or a fabric.

23. A method for cooling a blown film in which with a device for application of liquid, a liquid is applied to the outer wall of the blown film, whereby the film is cooled by the liquid, with at least one diversion element for diversion at least of a part of the liquid from the blown film is diverted, wherein the diversion element surrounds at least parts of the blown film in the peripheral direction, the device for application of liquid includes at least one film guidance element with at least one inner wall, which is arranged at least in part around the blown film and along which the blown film is guided wherein with an alteration in the diameter of the blown film, the interval which the diverting element assumes to the main axis of the blown film, is altered, and that a diversion element is provided, which in the peripheral direction overlaps itself in partial areas, or that multiple diversion elements are provided, wherein one diversion element overlaps partial areas of at least one adjoining diversion element.

Description

[0042] Further advantages, features and particulars of the invention are gleaned from the specification which follows, in which various embodiments are explained in particular with reference to the figures. The features mentioned in the claims and in the specification can be essential to the invention individually per se or in whatever combinations. As part of the overall disclosure, features and particulars are valid which are described in connection with the invention-specific method, understandably also in connection with the invention-specific device and vice versa, so that as regards the disclosure to the individual aspects of the invention, reciprocal reference is made or can be made. The individual figures show:

[0043] FIG. 1: a view of a calibration device, by which the diameter of the tubular area is able to be altered

[0044] FIG. 2: a section through an invention-specific calibration device

[0045] FIG. 3: a top-down view of the suctioning device

[0046] FIG. 4: a liquid-permeable element

[0047] FIG. 5: an invention-specific blown film unit

[0048] FIG. 1 shows a calibration device 1, wherein in this embodiment the diameter of the tubular area can be altered.

[0049] Above the sheath 50 a ring 80 is provided, which includes a surrounding opening 81 on its inner side and which an annular chamber 84 encloses. Viewed in the radial direction, ring 80 projects out beyond the sheath. In this part projecting beyond sheath 50, a circumferential recess 82 is made, that can serve as a liquid reservoir. The liquid is fed via feed hose 83, which advantageously can be distributed evenly over the periphery of the ring, which is indicated by arrow A. At a sufficiently high liquid level within the annual chamber, the liquid emerges from surrounding opening 81 and runs into the inlet area between the elastically deformable, tubular area 55 and the blown film 6. Here a liquid ring is formed. The blown film carries along a part of the liquid, with the later cooling the blown film. Blown film 6 is moved in transport direction z. Blown film 6 is characterized by its axis of symmetry 85, which simultaneously is its main axis of inertia or, for short, its main axis.

[0050] To be able, after its cooling action, to again remove the liquid from the blown film, below the tubular area a suctioning device 89 is placed. This includes a ring 90, which likewise forms an annular chamber 91. The inner wall 92 is provided with openings 93, through which the water can be suctioned from the surface of the blown film. For suctioning, annular chamber 91 is attached via one or more hoses 94 to a negative pressure source. The suctioning direction is indicated by arrow B. So that blown film 6 is not damaged at the openings 93, they are covered with a porous material 95, through which however the liquid can pass, but which avoids a deformation of the material of the blown film. Something like a fabric, for example a textile fabric, can serve as the material. Many other materials which have properties suitable for the named application, are conceivable. The inner wall 92, openings 93 and material 95 together form a liquid-permeable element 100 designated as a diversion element. The device and the method for altering the inner diameter of the tubular area are disclosed in FIGS. 11 and 12 as well as the pertinent specification sections of the publication WO 2012/032128 A1. These citations hereby are deemed as being included in this patent application. However, this is only an embodiment of a calibration device with a tubular area whose diameter can be altered. Also other embodiments of such a calibration device are advantageously able to be combined with suctioning devices as are explained using FIGS. 2 and 3 and the portions of the specifications that follow.

[0051] FIG. 2 shows a part of a view through a section of an invention-specific calibration device 1 with a suctioning device 101. The blown film 6 is not shown in this view for the sake of visibility. The sheath 50 has a support ring 102 on its underside, on which, via an intermediate ring 103 and a holding device 104, an annular body 105 is braced, by which the diameter of tubular area 55 is adjustable, which does not need to be explained here in greater detail. The tubular area preferably is formed by a cylinder 107 made of a flexible material, which is drawn from the inner area via the annular body outward, and attached by means of attachment rings 106 on a suitable component, here intermediate ring 103.

[0052] Below sheath 50 a sheath catch 110 is provided, which bears a carrying plate 111 extending inward. On carrying plate 111, a rail is arranged 112, on which the slider 113 is movable, especially in the radial direction r of the blown film. The inner wall 114 is at a large interval to the main axis of the blown film, so that when the calibrating device is adjusted to the largest possible blown film guidable with the calibrating device, the carrying plate represents no limitation. On its end facing the main axis of the blown film, slider 113 carries a support element 115, on the inner surface of which liquid-permeable element 100 is arranged. In the embodiment shown, multiple liquid-permeable elements 100 are provided, of which two are depicted.

[0053] So that an annular chamber can be formed, beneath each support element 115 at least one sheet plate 116 is provided, which is able to be shifted with support element 115. Preferably this sheet plate is attached to the support element. Beneath sheet plate 116, a flat flexible ring 117, especially a rubber ring, is placed, the inner edge of which is set up to remove liquid which could not be suctioned out by means of the suctioning device from the outer surface of the blown film. So that also the inner edge of the rubber ring is adjustable in regard to the interval to the main axis of the blown film, the latter can be stretched in a radial direction, which preferably occurs simultaneous with adjustment of the interval of the liquid-permeable elements. Beneath flexible ring 117, an encircling seal 118 is arranged, which adjoins the flexible ring in sealing fashion on one side, and on the other side is admitted into a groove of the lower closing ring 119. The lower closing ring 119 is attached to sheath catch 110.

[0054] Altogether with the suctioning device described, an annular chamber 91 is formed, which is able to be impinged on by negative pressure for the purpose of suctioning the liquid out. By this means, flexible ring 117 is drawn against the at least one sheet plate, wherein flexible ring 117 especially also adjoins the bottom edge of the liquid-permeable elements. Above the liquid-permeable elements 100, chamber 91 is formed by cylinder 107, intermediate ring 103 and support ring 102. To attain an enhanced sealing effect, the annular body 105 can be braced at least in part by its weight on support element 115.

[0055] FIG. 3 is a top-down view of suctioning device 101, wherein some reference symbols already explained in FIG. 2 are also incorporated into FIG. 3.

[0056] It is clearly seen that multiple liquid-permeable elements 100 are provided, each of which overlaps the adjoining element or is overlapped by the adjoining element.

[0057] Perceived in FIG. 3 are drive force transmission means which are explained in greater detail in what follows. A toothed drive wheel 200 is driven by a drive motor not depicted, preferably by an electric motor, and transmits the drive force to the chain 201. Chain 201 is tensioned by the chain tensioners 202, so that the wear of the chain can be equalized. In the area of each support element 115, the chain is guided via an outer toothed wheel 203 and an inner toothed wheel 204, with these toothed wheels arranged in such a way that the chain runs between them essentially in a radial direction. In the area between the two toothed wheels, a follower 205 is attached, which transmits the drive force from the chain to slider 113 and thus causes a shifting of the support element and thus of the liquid-permeable element 100 relative to main axis 85.

[0058] FIG. 4 shows a liquid-permeable element 100, as is provided in an invention-specific calibrating device. It first includes a plate 92, into which numerous openings 93 are made. On a first end 96, the element 100 is attached to support element 115.

[0059] On element 100, additionally a material 95 is arranged, which advantageously is configured as a pocket-shaped covering 97. This covering 97 can be moved in or away from the peripheral direction of the blown film, so that it is possible to change out coating 97 via the free end 98 of element 100 without great expense. In addition, advantageously at least one hook 99 is provided, which is situated on the upper and/or lower edge of element 100, and by which element 100 is hooked into adjoining element 100, which is covered by element 100. What is attained in this way is that the majority of elements 100 more closely approximate a circular shape, and this is maintained also with a change in the interval.

[0060] Finally, FIG. 5 shows an invention-specific blown film unit 501. A plastic is brought to the filling sleeve 502, which then is plastified in the extruder 503. The mass that is produced is fed via a connection line 504 to the blower head 505, with which, from the mass, a blown film 6 is formed. Additional extruders can be assigned to blower head 505, so that multilayer films can be produced. The extruders can be arranged on an elevated platform 520, on which blower head 505 is also suspended. A carrying device 521 can also be arranged on this platform. This carrying device bears the calibration basket 507 described below in further detail, wherein the carrying device includes a height adjustment by which the interval of calibration basket 507 to the blower head is adjustable. This situation is clarified by the double arrow H.

[0061] Blown film 6 leaves the blower head through an annular nozzle not visible in this depiction in transport direction z. The dashed line 522 represents the axis of symmetry of blown film 6.

[0062] Upon leaving blowing head 5, blown film 6 is initially present as a foil bubble, in which counter to the ambient pressure there is a slightly elevated interior pressure. This is attained by feeding in compressed air through blower nozzle 508. Due to the elevated interior pressure, the not-yet-solidified material of blown film 6 expands. Ultimately in this way the diameter of the completed blown film 6 as well as the thickness of the film material is adjusted.

[0063] Then the not-yet-solidified film bubble 6 gets into the calibration and cooling device designated as the calibrating basket 507. Here the diameter of the blown film is limited. Within calibrating basket 507, the blown film cools down to a temperature at which it is not possible to have subsequent deformation, or only if high levels of force are applied. The position at which this phase transformation occurs is often designated as the frost line.

[0064] Calibrating basket 507 can be configured according to one or various embodiments, as it is described as part of the present patent application and shown in the figures.

[0065] After leaving calibrating basket 507, blown film 6 reaches a lay-flat device 510, in which blown film 6 is reshaped nearly or fully into a dual layer film path 509. Blown film 6 is guided between pairs of guiding elements 511, which, in the course of transport direction z assume an ever smaller distance from each other. The complete flattening is done by a squeezing device which consists of a pair of squeezing rollers 512. Squeezing rollers 512 prevent air from remaining within the blown film during its further transport.

[0066] Blown film 6 or the film path 509 derived therefrom can additionally be guided through a reversing device which is not shown, or, in the case of the device shown, directly via deflecting rollers 513 of a winding device 514, where the film path can be processed into a winding 515.

TABLE-US-00001 List of Reference Symbols 1 Calibration device 6 Blown film 50 Sheath 55 Elastically deformable tubular area 80 Ring 81 Surrounding opening 82 Surrounding recess 83 Feed hoses 84 Annular chamber 85 Axis of symmetry 89 Suctioning device 90 Ring 91 Chamber 92 Inner wall 93 Opening 94 Hoses 95 Porous material 96 First end 97 Pocket-shaped covering 98 Free end 99 Hook 100 Liquid-permeable element 101 Suctioning device 102 Support ring 103 Intermediate ring 104 Holding device 105 Annular body 107 Cylinder 110 Sheath catch 111 Support plate 112 Rail 113 Slider 114 Inner wall 115 Support element 116 Sheet plate 117 Flexible ring 118 Encircling seal 119 Closing ring 200 Toothed drive wheel 201 Chain 202 Chain tensioner 203 Outer toothed wheel 204 Inner toothed wheel 205 Follower