Method and Device for the Production and Further Processing of a Film Tube

Abstract

The invention describes a method for the production and further processing of a film tube (6), in which method a plastic melt is transferred into a cylindrical melt by means of an extrusion die (4), the melt flow is drawn out through an annular gap (5) associated with the extrusion die (4) in order to form the film tube (6), and at least one temperature-controlled volume flow comprising at least one fluid is conducted by means of a temperature control device (8) onto the outer periphery of the film tube (6), wherein the temperature control device (8) is divided into peripheral segments, wherein a volume flow of different magnitude and/or different temperature is produced by means of each peripheral segment such that the temperature control of the film tube (6) differs over the periphery of the film tube, and wherein the film tube (6) is flattened by means of a flattening device (9), the flattening device (9) being rotated in relation to the extrusion die (4). A first volume flow in at least one peripheral segment of the temperature control device (8) differs from the volume flow of other peripheral segments so that at least one thick point (13) is produced on the film tube, wherein the first volume flow is produced by means of adjacent peripheral segments in succession, wherein the first volume flow is produced by means of the corresponding at least one peripheral segment in such a way that the first volume flow is adapted to the rotation of the flattening device (9) such that the at least one thick point (13) assumes substantially the same position in relation to the flattening device (9).

Claims

1-15. (canceled)

16. A method for the production and further processing of a film tube, in which method a plastic melt is transferred into a cylindrical melt flow by means of an extrusion die, the melt flow is drawn out through an annular gap associated with the extrusion die in order to form the film tube, at least one temperature-controlled volume flow comprising at least one fluid is conducted onto the outer periphery of the film tube by means of a temperature control device, wherein the temperature control device is divided into peripheral segments, wherein a volume flow of different size and/or different temperature is produced by means of each peripheral segment such that the temperature control of the film tube differs over the periphery of the film tube, the film tube is flattened by means of a flattening device, wherein the flattening device is rotated in relation to the extrusion die, a first volume flow in at least one peripheral segment of the temperature control device is different from the volume flow in other peripheral segments, wherein at least one thick point is produced on the film tube, wherein the first volume flow is produced by means of adjacent peripheral segments in succession, and wherein the first volume flow is produced by the corresponding at least one peripheral segment in such a way that the first volume flow is adapted to the rotation of the flattening device such that the at least one thick point assumes substantially the same position in relation to the flattening device, wherein the thickness of the thick point deviates from the nominal thickness or the actual average thickness by at least 20%, preferably by 30%, and in that lateral folds are introduced into the film tube, wherein the thick point is produced at an angular position on the film tube where an outer edge of a lateral fold is placed.

17. The method according to claim 16, wherein a first volume flow in at least one peripheral segment of the temperature control device is different from the volume flow of the directly adjacent peripheral segments.

18. The method according to claim 16, wherein, after being flattened, the film tube is conducted through a reversing device.

19. The method according to claim 16, wherein at least two thick points are introduced into the film tube.

20. The method according to claim 16, wherein when an even number of thick points are provided, two thick points are introduced opposite one another.

21. The method according to claim 16, wherein the flattened film tube is wound in a winding device to form a reel.

22. The method according to claim 16, wherein the flattened film tube is fed to a device for packaging a plurality of stacked objects, wherein the film is gripped at holding positions by pulling means and is pulled over the objects.

23. The method according to claim 16, wherein the flattened film tube is fed to a device for forming, filling and sealing bags, where it is processed to produce filled and sealed bags.

24. The method according to claim 16, wherein the flattened film tube is fed to a stretching apparatus in which it is stretched in the direction of transport.

25. The method according to claim 16, wherein the peripheral segment by means of which the first volume flow is produced deviates by an angle from the angular position assumed by the flattening device during its rotation.

26. The method according to claim 16, wherein the angle deviates from the angular position by at least 5°, in particular by at least 10°.

27. A device for producing and further processing a film tube, the device comprising: an extrusion die for transferring a plastic melt into a cylindrical melt flow, an annular gap which is associated with the extrusion die and through which the melt flow can be drawn out to form the film tube, a temperature control device for conducting at least one temperature-controlled volume flow comprising at least one fluid onto the outer periphery of the film tube, wherein the temperature control device is divided into peripheral segments, wherein a volume flow of different size and/or different temperature can be produced by means of each peripheral segment so that the temperature of the film tube can be controlled differently over its periphery, and a flattening device with which the film tube can be flattened, wherein the flattening device is rotatable relative to the extrusion die, a first volume flow can be produced in at least one peripheral segment of the temperature control device, which volume flow differs from the volume flow of other peripheral segments, wherein at least one thick point can be produced on the film tube, wherein the first volume flow can be produced by means of adjacent peripheral segments in succession, wherein the first volume flow can be produced by the corresponding at least one peripheral segment in such a way that the first volume flow is adapted to the rotation of the flattening device such that the at least one thick point assumes substantially the same position in relation to the flattening device, wherein the thickness of the thick point deviates from the nominal thickness or the actual average thickness by at least 20%, preferably by 30%, and in that lateral folds can be introduced into the film tube, wherein the thick point is produced at an angular position on the film tube where an outer edge of a lateral fold is placed.

Description

[0030] Further advantages, features and details of the invention will be apparent from the following description, in which various exemplary embodiments are explained in detail with reference to the FIGURES. The features mentioned in the claims and in the description can each be considered essential to the invention, alone or in any combination of the mentioned features. Within the scope of the disclosure as a whole, features and details that are described in connection with the method of the invention can, of course, also be applied in connection with the device of the invention, and vice versa, so that reference always is or can be reciprocal with respect to the disclosure of the individual aspects of the invention. The individual FIGURES show:

[0031] FIG. 1 a side view of a device for producing a film tube

[0032] FIG. 1 shows a device 1 for producing a film tube, which comprises firstly at least one extruder 2, with which plastic in granular form, for example, can be plasticized. The plastic melt thus produced is supplied via a line 3 to an extrusion die 4, where this melt is transferred into a cylindrical melt flow, so that this melt flow can be drawn out through an annular gap 5, not visible in this FIGURE, in take-off direction z. An as yet unsolidified film tube 6 is thus produced. This is inflated from the inside by a slight overpressure such that it has a greater diameter inside the optional calibration device 7. The film tube is solidified by means of a temperature control device 8, which is often also referred to as a cooling ring due to its ring-like configuration surrounding the film tube.

[0033] After passing through the calibration device, the film tube 6 reaches the operating area of a flattening device 9, in which the circular film tube is transferred into an ellipsoidal cross-section with increasing eccentricity, until finally, in the operating area of the take-off rollers, it forms two film webs lying one on top of the other and joined with one another along their sides.

[0034] The flattening device is arranged as rotatable, with the axis of rotation being aligned substantially with the tube axis 11, which in FIG. 1 is indicated by a dashed-dotted line. The rotatability of the flattening device is indicated by the arrow 12.

[0035] Temperature control device 8 is divided into various peripheral segments. Each peripheral segment of the temperature control device is capable of applying an individual volume flow (amount of fluid per unit of time) and/or a volume flow at an individual temperature to the film tube. Air is preferably provided as the fluid. The peripheral segment of the film tube that is associated with the peripheral segment of the temperature control device in question can thus be individually temperature controlled, in particular cooled. The peripheral segments of the film tube that no longer “run” as much due to the greater cooling action of the temperature control device form a thick point 13, which is indicated in the FIGURE by a double line.

[0036] To ensure that the thick point always arrives at a fixed position on the flattening device, it is also necessary for the thick point to move along the periphery, as indicated by arrow 14 in the FIGURE. This “migration” of the thick point is achieved by altering the parameters of the next closest peripheral segment of the temperature control device in the direction of arrow 14 in order to produce a thick point adjacent to the peripheral segment of the film tube that already has such a thick point. The current thick point is returned to the original parameters by the peripheral segment in question of the temperature control device then decreasing its cooling action on the angular segment associated with it.

[0037] FIG. 1 further shows a reversing device 15, the function of which is to guide the flattened film tube from the flattening device to the stationary roller 16 without damaging it. As indicated by arrow 17, this film tube is then conducted to further processing, which is not specified in greater detail here.

TABLE-US-00001 List of Reference Signs 1 Device 2 Extruder 3 Line 4 Extrusion die 5 Annular gap 6 Film tube 7 Calibration device 8 Temperature control device 9 Flattening device 10 11 Tube axis 12 Arrow 13 Thick point 14 Arrow 15 Reversing device 16 Roller 17 Arrow 18 19 20 21 22 23 24