System for the Improved Introduction of a Separating Device and Blown Film Line, as Well as a Method for the Production and Supply of at Least Two Plastic Film Webs in a Blown Film Line

Abstract

The invention relates to a system (10) for improved introduction of a separating device (40) into a flattened film tube (2) of a blown film line (1), with a cutting device (20) for severing only a first tube side (2.1) of the film tube (2), in particular the film tube (2) which has not yet been flattened.

Furthermore, the invention relates to a blown film line (1), as well as a method (100) for producing and providing at least two film webs (6).

Claims

1. A system for improved introduction of a separating device into a flattened film tube of a plant, comprising a cutting device for cutting through only a first tube side of the film tube, and an opening device, which is arranged downstream of the cutting device in the transport direction of the film tube, for opening the flattened film tube along the cut film tube in order to insert the separating device into the flattened film tube.

2. The system according to claim 1, wherein the cutting device has at least one cutting element for effecting a severing cut on the film tube.

3. The system according to claim 1, wherein at least the at least one cutting element is movable transversely to the transport direction of the film tube or the cutting device has a control for moving the at least one cutting element.

4. (canceled)

5. The system according to claim 1, wherein two cutting elements are provided which are at a fixed distance from one another.

6. The system according to claim 1, wherein the opening device has at least one opening element, it being possible for the opening element to be introduced into the severing cut.

7. The system according to claim 1, wherein the at least one opening element is mounted such that it can be moved.

8. The system according to claim 7 wherein the opening element is of at least hook-like or bolt-like configuration.

9. The system according to claim 1, wherein at least the opening device comprises an opening sensor, by means of which an introduction of the opening element into the film tube can be detected or the opening device is configured to stretch a second tube side, opposite the first tube side, of the film tube in such a way that a stretching force of the second tube side exceeds a retaining force between the first and second tube sides.

10. The system according to claim 1, wherein an anti-adhesion device for locally changing an adhesion property of an inner side of the film tube is provided.

11. (canceled)

12. The system according to claim 1, wherein at least a deflection unit is provided for deflecting the film tube or a constriction point is provided, at which a width of the film tube can be reduced, wherein the deflection unit is arranged downstream of the constriction point in the transport direction of the film tube, wherein the cutting device is arranged relative to the constriction point and the deflection unit in such a way that air accumulated between the constriction point and the deflection unit can be released by the severing cut which can be effected in the film tube by the cutting element of the cutting device.

13. (canceled)

14. The system according to claim 1, wherein a contact unit is provided, it being possible for the contact unit to be brought between an active position and a passive position, the contact unit, moving the flattened film tube into a position such that reliable movement of the separating device at least into the film tube or out of the film tube is made possible.

15. The system according to a claim 14, wherein at least the contact unit can be transferred into a passive position in which the contact unit is spaced apart from the film tube or the contact unit can be brought or moved into the respective position by means of a control, the contact unit or the contact unit is arranged movably on a frame in such a way that the contact unit is oriented perpendicularly to the transport direction of the film tube and parallel to the orientation of the film tube.

16. (canceled)

17. (canceled)

18. The system according to claim 1, wherein the cutting device is configured to effect two severing cuts on the film tube, wherein the opening device has two opening elements, each opening element being insertable into a respective severing cut, the contact unit has two contact elements which are movable in such a way that, in the active position of the contact unit, the contact elements act on the flattened film tube, which has two opposite folding lines, and the first contact element is located between the first folding line and the first severing cut and the second contact element is located between the second folding line and the second severing cut.

19. A blown film line for the production and supply of several film webs made of plastic with a blow head from which a film tube can be extruded wherein the film tube can be conveyed along a transport direction, a flattening device which is arranged downstream of the blow head and by means of which the film tube can be flattened as a double-layer plastic film, a separating device which is configured in such a way that the flattened film tube can be separated into two separate film webs, a system, for improved introduction of the separating device into the flattened film tube, comprising a cutting device for cutting through only a first tube side of the film tube, and an opening device, which is arranged downstream of the cutting device in the transport direction of the film tube, for opening the flattened film tube along the cut film tube in order to insert the separating device into the flattened film tube, a control unit for causing the film tube to move along the transport direction, and with two winding points, wherein a film web can be fed to each winding point.

20. The blown film line according to claim 19, wherein at least the cutting device is arranged in the flattening device or is arranged downstream of the flattening device or the cutting device has a control for bringing the cutting device from an activation state into a deactivation state and vice versa, in which case, in the activation state, only a first tube side of the film tube is cut through by the cutting device and, in the deactivation state, the cutting device is at a distance from the film tube.

21. (canceled)

22. The blown film line according to claim 19, wherein at least the opening device has a control in order to bring the opening device from an active position into a passive position and vice versa, it being possible, in the active position, to bring about an opening action on the flattened film tube and, in the passive position, the opening device being spaced apart from the film tube or the separating device has a control for moving the separating device into the film tube which has been at least partially opened by the opening device.

23. (canceled)

24. The blown film line according to claim 19, wherein a control unit is provided for coordinating the cutting device and the opening device.

25. The blown film line according to claim 19, wherein at least the control unit has an activation module for actuating the cutting device in order to carry out, the cutting of the first tube side during an activation of the blown film line or the control unit has a winding module for detecting a winding change at at least one of the winding points and for carrying out, the severing of the first tube side when the winding change is detected or the control unit has a record module for producing a winding record, by means of which a position of severance of the first tube side for at least one film web can be assigned.

26. (canceled)

27. (canceled)

28. The blown film line according to claim 19, wherein an additional separating unit is arranged upstream of the winding points in the transport direction of the film tube, which additional separating unit has a further opening device for at least detaching the first tube side from a second tube side or at least one transverse separating means for separating a head region of the flattened film tube.

29. The blown film line according to claim 19, wherein a sensor unit checks the moving film tube along the transport direction and is in communication with at least the control unit or with the control of the cutting device or with the control of the opening device or with the control of the separating device.

30. The blown film line according to claim 19, wherein the separating device has separating elements for cutting through the flattened film tube at two positions.

31. The blown film line according to claim 30, wherein the separating device has at least one guiding element for guiding a severed section of the first tube side to at least one of the separating elements.

32. The blown film line according to claim 19, wherein at least the separating elements can be moved perpendicularly to the transport direction of the flattened tube film parallel to the flattened tube film level or the opening elements can be moved obliquely to the tube film level.

33. The blown film line according to claim 19, wherein a contact unit is provided which can be brought or moved between an active position and a passive position, wherein in the active position the contact unit contacts the flattened film tube in such a way that a reliable movement of the separating device at least into the film tube or out of the film tube is made possible.

34. The blown film line according to claim 19, wherein the separating device is arranged downstream of the contact unit and the opening device in the transport direction of the film tube.

35. The blown film line according to claim 19, wherein in the activation state of the cutting device, the flattened film tube has at least one severing cut on the first tube side.

36. The blown film line according to claim 19, wherein the system can be operated in a retraction process and in an extension process, it being possible, in the retraction process, for the separating device to be transferred automatically from a parking position, in which the separating device does not effect severing of the film tube, into an operating position, in which the separating device effects severing of the film tube at least its folding line or folding lines.

37. The blown film line according to claim 19, wherein a central region of the film tube and two side regions of the film tube are formed between the two severing cuts, the side region being bounded by a folding line of the film tube and the facing severing cut.

38. The blown film line according to claim 19, wherein at least the separating device can be moved into a central position for the retraction process and the extension process, in which the separating device is located at least partially in the central region within the film tube, the opening device or for the retraction process and for the extension process, the contact unit acts on the side region of the film tube in order to ensure reliable movement of the separating device.

39. (canceled)

40. The blown film line according to claim 19, wherein an additional cutting device is provided which can be brought into an operating mode and a sleep mode, is positioned at a distance from the film tube in the sleep mode and makes an additional cut through both tube sides of the film tube in the operating mode.

41. The blown film line according to claim 19, wherein a frame is provided, on which the separating device and the opening device are arranged, the separating device being arranged downstream of the opening device in the transport direction of the film tube or a detection means is provided which detects at least one of the positions of the separating device, wherein, in the event of an incident in which the separating device moves from the operating position to the parking position, the additional cutting device changes from the sleep mode to the operating mode.

42. The blown film line according to claim 19, wherein the additional cutting device is arranged downstream of the separating device in the transport direction of the film tube.

43. (canceled)

44. A method for producing and providing at least two film webs of plastic comprising the following: Extrusion of a film tube, Cutting of only a first tube side of the film tube, Flattening the film tube to form a double-layer plastic film, Opening of the flattened film tube along the cut of the first tube side, Separation of the flattened film tube into two separate film webs.

45. The method according to claim 44, wherein at least for cutting the first tube side, a cutting device is first brought into an activation state, in which the first tube side of the film tube is cut by the cutting device, and is then brought into a deactivation state, in which the cutting device is at a distance from the film tube or in order to open the flattened film tube, the opening device is brought into an active position, in which an opening action is effected on the flattened film tube, and is then brought into a passive position, in which the opening device is spaced apart from the film tube or a separating device with separating elements is provided for separating the flattened tube film into two separate film webs, the separating elements being movable perpendicularly to the transport direction of the flattened tube film parallel to the flattened tube film level.

46. (canceled)

47. The method according to claim 44, wherein at least the cutting of the first tube side and the opening of the flattened film tube are carried out at different positions along the transport direction of the film tube and are automatically coordinated or when the film tube flattened is opened, at least one opening element is introduced into the severing cut or the flattened film tube is cut at two positions when the first tube side is cut or after extrusion, the film tube is deflected by a deflection unit for deflecting the film tube.

48. (canceled)

49. (canceled)

50. (canceled)

51. (canceled)

52. The method according to claim 44, wherein an adhesive property of an inner side of the film tube is locally changed to facilitate opening of the film tube flattened at the severing cut.

53. The method according to claim 44, wherein in order to open the flattened film tube, a second tube side, opposite the first tube side, of the film tube is stretched in such a way that a stretching force of the second tube side exceeds a retaining force between the first and second tube sides.

54. The method according to claim 44, wherein the severing of the first tube side is carried out during an activation of the blown film line.

55. The method according to claim 44, wherein winding of at least one film web onto at least one, preferably two film webs onto two winders takes place.

56. The method according to claim 44, wherein a winding record, is produced, by means of which a position of severance of the first tube side for at least one film web can be assigned or before the winding, a further opening of the film tube is carried out by at least detaching the first tube side from a second tube side or by separating a head region of the flattened film tube.

57. (canceled)

58. The method according to claim 44, wherein in a retraction process, the separating device is automatically transferred from a parking position, in which the separating device does not effect severing of the film tube, into an operating position, in which the separating device effects severing of the film tube at least its folding line or folding lines.

59. The method according to claim 44, wherein in the retraction process the following takes place: a) Transfer of the cutting device to the activation state at the start of the introduction process, so that at least one severing cut or two severing cuts are made on the first tube side of the film tube, b) Transfer of the opening device from the passive position into the active position, wherein in the active position at least one opening element, c) Transfer of the separating device from a parking position, in which the separating device does not cut through the film tube, into an operating position, in which the separating device cuts through the film tube at least its folding line or folding lines.

60. The method according to claim 44, wherein at least in a) or in h), a central region of the film tube and two side regions of the film tube are formed between the two severing cuts, the side region being bounded by a folding line of the film tube and the facing severing cut.

61. The method according to claim 44, wherein during c), the separating device is moved to a central position in which the separating device is located at least partially in the central region inside the film tube, the opening device being in the active position, wherein in g) the separating device moves from the central position to the operating position.

62. The method according to claim 44, wherein in c), a contact unit moves from a passive position, into an active position, the contact unit acting on the side region of the film tube in the active position in order for the separating device to move reliably from the parking position into the central position.

63. The method according to claim 44, wherein after the separating device has reached the central position, the following steps are carried out: d) Transfer of the opening device from the active position to the passive position e) Transfer of the contact unit from the active position to the passive position.

64. The method according to claim 44, wherein in f), the cutting device is transferred from the activation state to the deactivation state.

65. The method according to claim 44, wherein g) is carried out after at least one of d), e) or f).

66. The method according to claim 44, wherein in an extension process, the separating device is automatically transferred from an operating position, in which the separating device effects severing of the film tube at least its folding line or folding lines, to a parking position, in which the separating device does not effect severing of the film tube.

67. The method according to claim 44, wherein the following takes place in the extension process: h) Transfer of the cutting device to the activation state at the start of the extension process, so that at least one severing cut or two severing cuts are made on the first tube side of the film tube, i) Transfer of the opening device from the passive position into the active position, wherein in the active position at least one opening element, j) Transfer of the separating device from an operating position, in which the separating device effects a severing of the film tube at least its folding line or folding lines, into a parking position, in which no severing of the film tube is effected by the separating device.

68. The method according to claim 44, wherein during j), the separating device is moved to a central position in which the separating device is located at least partially in the central region within the film tube, the opening device being located in the active position, wherein in k) the separating device moves from the central position to the parking position.

69. The method according to claim 44, wherein in i), a contact unit is transferred or moves from a passive position, into an active position, the contact unit acting on the side region of the film tube in the active position in order for the separating device to move reliably from the operating position into the central position and into the parking position.

70. The method according to claim 44, wherein while the separating device leaves the central position in the direction of the parking position, the opening device remains in the active position.

71. The method according to claim 44, wherein after the separating device has reached the parking position, the following takes place: m) Transfer of the opening device from the active position to the passive position n) Transfer of the cutting device from the activation state to the deactivation state.

72. The method according to claim 44, wherein a detection means is provided which, during the production of the film webs, detects a malfunction in which the separating device, moves from the operating position into the parking position, as a result of which an additional cutting device is activated in p), which additional cutting device, in an operating mode, makes an additional cut through both tube sides of the film tube, the additional cut being arranged downstream of the separating device in the transport direction of the film tube.

73. The method according to claim 44, wherein after p), the malfunctioning separating element is replaced by a functioning separating element and then the steps of the retraction process are carried out for the functioning separating element.

74. The method according to claim 44, wherein before the separating device, moves from the central position in the direction of the operating position, the cutting device moves into the deactivation state, the following steps are then carried out: Movement of the separating device, Transfer of the additional cutting device from the operating mode to the sleep mode, in which an introduction of an additional cut is omitted.

Description

[0110] FIG. 1 a schematic view of a blown film line according to the invention with a system for improved introduction of a separating device into a flattened film tube,

[0111] FIG. 2 An opening device according to the invention as shown in FIG. 1, wherein the opening elements of the opening device are in a passive position,

[0112] FIG. 3 an opening device according to FIG. 2, with the opening elements in an active position,

[0113] FIG. 4 the opening device according to FIG. 2, whereby the separating device is moved into the film tube,

[0114] FIG. 5 the opening device according to FIG. 2, whereby the separating device is located inside the film tube,

[0115] FIG. 6 an enlarged view according to FIG. 1, whereby the cutting device has two cutting elements,

[0116] FIG. 7 in enlarged view of FIG. 1, wherein the cutting device comprises a cutting element,

[0117] FIG. 8 a further embodiment of a control unit which can be integrated as shown in FIG. 1,

[0118] FIG. 9 a schematic view of a separating device of a system according to the invention,

[0119] FIG. 10 a cutting device of a system according to the invention in a further embodiment,

[0120] FIG. 11 an opening process in an opening device of a system according to the invention in a further embodiment,

[0121] FIG. 12 an additional separating device of a system according to the invention in a further embodiment, and

[0122] FIG. 13 a schematic representation of the process according to the invention,

[0123] FIG. 14a-c pattern of an opening device according to the invention in further embodiments,

[0124] FIGS. 15-22 a possible embodiment for a retraction process to insert the separating device into the flattened film tube,

[0125] FIGS. 23-30 a possible embodiment of an extension process to transfer the separating device from the flattened film tube,

[0126] FIGS. 31-40 a possible embodiment in which an additional cutting device can act on the flattened film tube.

[0127] In the following figures, the identical reference signs are used for the same technical features even of different embodiments.

[0128] FIG. 1 shows a sketch of a blown film line 1, in which a film tube 2 is extruded by a die head 4 and conveyed away in the conveying direction Z. The material of the film tube 2 is initially still present as a melt-like extrudate. Plastic is first plasticized in the extruder 14. The resulting mass is fed via a connecting line to the blow head 4, with which the film tube 2 is formed from the mass. Further extruders may be associated with the blow head 4, so that multilayer films can be produced. A method 100 according to the invention for producing a film by the blown film line 1 is shown in FIG. 13. In the following description of the blown film line 1, reference is also made to the method 100.

[0129] During extrusion 101 of the film tube 2 from the blow head 4, the film tube 2 is initially present as a film tube when leaving the blow head 4, in which there is a slightly increased internal pressure compared to the ambient pressure. Due to the increased internal pressure, the not yet solidified material of the film tube 2 expands. Ultimately, both the diameter of the finished tube film 2 and the thickness of the film material are adjusted in this way.

[0130] Subsequently, the not yet solidified film tube 2 passes into the calibration device 15. Here, the diameter of the film tube 2 is limited. Within the calibration device 15, the film tube 2 cools down to a temperature at which subsequent deformation is no longer possible or is only possible with the use of greater forces. The position at which this phase transition occurs is often referred to as the “frost line”.

[0131] After leaving the calibrating device 15, the tube film 2 passes into a flattening device 5, in which the tube film 2 is almost completely formed into a flattened, double-layered film web which lies substantially in a tube film level 9. In particular, a flattening 103 of the film tube to form a double-layered plastic film, which is connected in particular in edge regions, thus takes place by the flattening device 5. For this purpose, the flattening device 5 has guiding elements 5.1 by means of which a stepwise or continuous reduction of a width 2.3 of the film tube 2 is made possible.

[0132] In the present embodiment, the blown film line 1 has a constriction device 13 with squeezing rollers, in particular so-called nip rollers, which prevent larger amounts of air from remaining inside the film tube 2 during its further transport.

[0133] The film tube 2 is further conveyed over transport rollers, which are not explicitly shown, in the direction of two winding points 7,8.

[0134] Referring to FIG. 1, the blown film line 1 comprises a system 10 for improved introduction of a separating device 40 into the flattened film tube 2. Here, the system 10 comprises a cutting device 20 and an opening device 30. According to FIG. 1 as well as FIG. 6 and FIG. 7, only a first tube side 2.1 of the film tube 2 is cut by the cutting device 20. In particular, the cutting device 20 may be configured according to FIG. 6 and/or FIG. 7. According to FIG. 6 and FIG. 7, the cutting device 20 has cutting elements 21 to effect a severing cut 3 on the film tube 2. FIG. 6 shows two cutting elements 21, whereas FIG. 7 shows only one cutting element 21. According to FIG. 7, the cutting element 21 is movable transversely to the transport direction Z of the film tube 2. According to the embodiments shown, the cutting device 20 comprises a control 22 for moving the at least one cutting element 21. On the one hand, the movement may be transverse to the transport device Z of the film tube 2. On the other hand, the control 22 may be provided to move the cutting device 20 from an activation state to a deactivation state and vice versa. In the activation state, only a first tube side 2.1 of the film tube 2 is cut by the cutting device 20. In particular, this means that a second tube side 2.2 opposite the first tube side 2.1 remains undamaged or is merely scratched. In particular, however, the second tube side 2.2 is not cut through. In the deactivation state, the cutting device 20 has a distance to the film tube 2.

[0135] Preferably, an anti-adhesion device 23 for locally changing an adhesion property of an inner side of the film tube 2 may be integrated into the cutting device 20. For this purpose, at least one of the cutting elements 21 of the cutting device 20 may comprise the anti-adhesion device 23, as shown in FIG. 10. When the cutting element 21 for cutting 102 the first tube side 2.1 is at least partially introduced into the film tube 2, an anti-adhesion agent can be introduced, preferably sprayed, into the film tube 2. The anti-adhesion agent may comprise, for example, an oil or a silicone spray. This may reduce adhesion of the first tube side 2.1 to the second tube side 2.2 when the film tube 2 is flattened 103, so that opening 104 by the opening device 30 may be facilitated, particularly at a later stage in the process.

[0136] The constriction device 13 further forms a constriction point 13.1 at which the width 2.3 of the film tube 2 can be reduced. This can be understood to mean, in particular, that a diameter of the film tube 2 is reduced in at least one direction. This can be done, for example, when the film tube 2 is flattened. However, in particular due to an overpressure in the film tube, it may happen that at least a few air particles are entrained and pass the constriction point 13.1. In the course of the production of the film, the entrained air can accumulate in front of a deflection unit 51, in particular in the form of a roller, for deflecting the film tube 2, if the deflection unit 51 is arranged downstream of the constriction point 13.1 in the transport direction of the film tube 2. This can cause an air bubble to form locally at the deflection unit 51. Due to the air bubble, the film tube 2 is stretched and/or pressed against the deflection unit 51, which can lead to a deterioration of quality properties of the film product. In order to avoid or reduce this effect, the cutting device 20 is arranged relative to the constriction point 13.1 and the deflection unit 51 in such a way that air accumulated between the constriction point 13.1 and the deflection unit 51 can be released by the severing cut 3 effected by the cutting element 21. The deflection unit 51 further comprises, in particular for contactless deflection of the film tube 2, an air supply 52. By means of the air supply 52, an air cushion can be formed between the film tube 2 and the deflection unit 51. Due to the resulting contactless deflection, damage to a surface of the film tube 2 can be reduced or avoided. Advantageously, the film tube 2 is thereby guided in such a way that the air cushion is formed between the deflection unit 51 and the closed second tube side 2.2. In this way, it can be avoided that air is blown into the film tube 2 through the air supply 52.

[0137] Moreover, an opening device 30 is provided which is arranged downstream of the cutting device 20 in the transport direction Z of the film tube 2. The opening device 30 serves to open the flattened film tube 2 along the cut film tube 2, in order to improve and simplify the introduction of the separating device 40 into the flattened film tube. This is shown schematically in FIG. 2 to FIG. 5. According to FIG. 6, both cutting elements 21 have a fixed distance to each other.

[0138] In the illustrated embodiment, the opening device 30 has two opening elements 31, wherein the opening elements 31 can be inserted into a respective severing cut 3 which has previously been created by the cutting device 20. According to FIG. 2 to FIG. 5, the opening elements 31 can be activated by a control 32. Moreover, the separating device 40 comprises separating elements 41 which are movable by means of a control 42. In particular, the separating elements 41 can have guiding elements 43, as shown in FIG. 9. Furthermore, opening elements 31 may have different geometries. For example, the opening elements 31 can be hook-like, which is not explicitly shown. In the illustrated embodiment, the opening elements 31 are of bolt-like configuration. In FIG. 2, the opening elements 31 are located at a distance from the flattened film tube 2. According to FIG. 3, the opening elements 31 are in their active position and are located at least partially inside the film tube 2. During the movement of the opening elements 31 from their passive position according to FIG. 2 into their active position according to FIG. 3, the opening elements 31 each penetrate the severing cut 3 which is present on the upper, first tube side 2.1, as a result of which an opening 104 of the film tube 2 is effected.

[0139] In order to enable a guiding of a film tube 2 when a separating device 40 is inserted into an opened severing cut 3 of the film tube 2, a separating element 41 may advantageously comprise guiding elements 43 for guiding the film tube 2. In particular, if the separating element 41 is formed as a knife, it may be advantageous that the film tube 2 is guided so that one end of the severing cut 3 meets the separating element 41 during transport of the film tube 2 and the severing cut 3 can be continued through the separating element 41. The guiding elements 43 may be arranged in a V-shape and oriented opposite to a transport direction of the film tube 2.

[0140] The fact that the opening elements 31 are located in the active position at least in regions below the first tube side 2.1 can preferably be detectable by opening sensors 33. For this purpose, the opening elements 31 may each comprise an opening sensor 33 in the form of an optical sensor through which an inner side of the first tube side 2.1 can be detected when the opening element 31 has moved sufficiently far between the first and the second tube sides 2.1, 2.2.

[0141] A possible opening process for opening 104 the flattened film tube 2 is also shown schematically in FIG. 11. In this case, an opening element 31 of the opening device 30 penetrates through the severed section 3 and presses against the second tube side 2.2. In this case, there is an adhesive effect of the first and second tube sides 2.1, 2.2 and there is a retaining force H which can result, for example, from an electrostatic attraction. Due to the retaining force H, the first tube side 2.1 initially remains adhered to the second tube side 2.2 even when the first tube side 2.1 is stretched by the opening element 31. Further stretching of the second tube side 2.2 increases a stretching force D of the second tube side 2.2, at least until the stretching force D exceeds the retaining force H. When the stretching force D exceeds the retaining force H, the first tube side 2.1 separates from the second tube side 2.2 at least in some regions at the severing cut, allowing the opening element 31 to pass between the first and second tube sides 2.1, 2.2. This may result from the fact that the film tube 2 is pre-tensioned in the transport direction of the film tube 2, i.e. the two tube sides 2.1, 2.2 are under tension stress. Therefore, the first and second tube sides 2.1, 2.2 each have a tendency to return to the tube film level 9 from a stretched state.

[0142] Subsequently, a movement of the separating elements 41 of the separating device 40 in the direction of the opening elements 31 takes place via a control 42 in order to enable a separation 105 of the film tube 2 into two separate film webs 6. Through the opened film tube 2, the separating device 40 with its separating elements 41 can be inserted into the film tube 1. In FIG. 5, the inserted state of the separating device 40 within the film tube 2 is shown. When the separating device 40 is inside the film tube 2, the film tube 2 flattened is cut on both sides at its folding lines into two film webs 6. One film web 6 is fed to the winding point 7, and the second film web 6 is fed to the winding point 8. At the winding points 7, 8, in particular, a winding 108 onto the film webs 6 takes place to form windings which can be further processed and/or further transported.

[0143] As FIG. 5 illustrates, there is then a movement of the opening elements 31 to their passive position. The cutting device 20 also moves to its deactivation state when the separating device 40 is inserted inside the film tube 2 and cuts it on both sides.

[0144] For coordinating the slitting device 20 and the opening device 30, the blown film line 1 comprises a control unit 11. Preferably, the control unit 11 can be associated with at least one of the winding points 7, 8 in order to enable a winder-controlled operation of the blown film line 1. In particular, the control unit 11 comprises an activation module 11.1 by means of which the cutting device 20 can be controlled in dependence on a activation of the blown film line 1 in order to introduce the severing cut 3, in particular once, into the first tube side 2.1 during the activation of the blown film line 1. Additionally or alternatively, the control unit 11 may comprise a winder module 11.2 for detecting a change of winding at at least one of the winding points 7, 8. This allows the control unit 11 to initiate the severing cut 3 by the cutting device 20 when the winding change has been detected. In particular, at least one severing cut 3 can be generated at each winding change. Furthermore, the control unit 11 preferably comprises a record module 11.3 for generating a digital or analog winding record. By means of the winding protocol, it can also be traced during further processing of a winding at which position in the winding the severing cut 3 is located. This can enable the film webs 6 to be wound up without the winding being interrupted when a tube section in which the severing cut 3 is inserted reaches the winding points 7, 8.

[0145] In order that during the production and transport of the film tube 2, the film tube 2 has the required web tension from the flat laying device 5 to the opening device 30, a control unit 50 is provided which may have one or more deflection units 51 in the form of rollers. Also a positioning in the last third of the film tube with respect to the transport direction Z can be arranged the cutting device 20.

[0146] Referring to FIG. 8, it is shown that the control unit 11 may be in communication with one or all of the controls 22, 32, 42. In addition, a sensor unit 12 as shown in FIG. 1 may be provided which can detect, for example, material properties of the film or the cut 3. On the basis of all data, the control unit 11 can control the system 10 accordingly, so that an optimized production of several film webs 6 can be carried out within the blown film line 1.

[0147] Referring to FIG. 1, the cutting device 20 may be arranged in the flat laying device 5 or downstream of the flat laying device 5.

[0148] Advantageously, the blown film line 1 according to FIG. 1 can further comprise an additional separating unit 70, as shown in FIG. 12. The additional separating unit 70 is arranged in front of the winding points 7, 8, in order to enable a renewed opening of the film tube 2, in particular during the activation of the blown film line 1 and/or during a winding change at at least one of the winding points 7, 8, and to distribute the film webs 6 to the winding points 7, 8. For this purpose, the additional separating unit 70 has a further opening device 30 for further opening 106 of the film tube 2 with opening elements 31 which can be introduced into the severing cut 3 of the film tube 2, in particular extended by the separating device 40, in order to open the film tube 2 and to separate the film webs 6 from one another, at least in regions. Furthermore, the additional severing unit 70 comprises a transverse severing means 71 by which the film tube 2 can be cut completely, i.e. with the first and second tube sides 2.1, 2.2, transversely to the transport direction of the film tube 2. Thus, a separating 107 of a head region of the film tube 2 lying in front of the severing cut 3 in the transport direction of the film tube 2 can take place. The head region can be formed during the activation of the blown film line 1 and, in particular, forms an accumulation of coherent film material. As a result, the film webs 6 are spaced apart from each other after passing the additional separating unit 70 and can be fed in a simple manner by an operator to the winding points 7, 8.

[0149] FIGS. 14a to 14c show exemplary advantageous cut patterns which can be introduced into a film tube 2 by the separating device 40 in order to sever the film tube 2. FIG. 14a shows separation cuts 3.1 in two edge regions of the film tube 2, so that the first and second tube sides 2.1, 2.2 are each separated into a film web 6. FIG. 14b shows separation cuts 3.1 in a central region of the film tube 2, so that two individual film webs 6 can be formed from the film tube 2 by unfolding the film tube 2. FIG. 14c further shows a possibility of separating or cutting a film tube 2 folded in sections into two film webs 6.

[0150] Advantageously, the blown film line 1 according to FIGS. 1 to 14 can further be operated as follows, which is described in FIGS. 15 to 40. In this case, the system 10, in particular the cutting device 20 as well as the opening device 30 can be operated in a retraction process I according to FIG. 15 to FIG. 22 or in an extension process II according to FIG. 23 to FIG. 30.

[0151] Here, the system 10 comprises a contact unit 60 which can be brought or moved between an active position 61 and a passive position 62. In the retraction process I, the separating device 40 with the two separating elements 41 is automatically transferred from a parking position P according to FIG. 15, in which the separating device 40 is spaced apart from the flattened film tube 2, to an operating position B according to FIG. 22. In the operating position B, the separating elements 41 are located at the folding line 16 of the flattened film tube 2 and effect a severing of the film tube 2, so that a separate film web 6 can be fed to each winding point according to FIG. 1 in each case. The above-mentioned retraction process I has the starting position according to FIG. 15. In a first step, according to FIG. 16, a transfer of the cutting device 20 according to FIG. 1 into the activation state 24 takes place, so that two severing cuts 3 are made on the first tube side 2.1 of the film tube 2. According to FIG. 16, the contact unit 60, which can be operated via a control 63, is in a passive position 62, i.e. at a distance from the film tube 2, in particular from the first tube side 2.1.

[0152] Subsequently, the opening device 30 is transferred from its passive position 34 to the active position 35 shown in FIG. 17, whereby in the active position 35 the opening elements 31 each protrude into a severing cut 3 of the film tube 2. The opening elements 31 have the effect that the separating device 40 with its separating elements 41 can reliably pass through the resulting opening, formed by the separation cuts 3, into the film tube 2 and be moved. In order that a reliable movement of the separating elements 41 from the parking position P in the direction of the interior of the film tube 2 can take place, the contact unit 60 acts with its two contact elements 65 on the first tube side 2.1 and presses it in the direction of the second tube side 2.2. This creates a necessary distance between the travel path of the separating elements 41 and the film tube 2, or the first tube side 2.1.

[0153] While the cutting device 20 is in the activation state 24, two severing cuts 3 are formed, as shown in FIG. 17 for example, wherein a central region 17 of the film tube 2 is formed between the two severing cuts 3. In addition, two side regions 18 of the film tube are formed, each side region 18 being bounded by a folding line 16 of the film tube and the facing severing cut 3, respectively. By means of the control 63, the contact unit 60 is transferred from its passive position 62 as shown in FIG. 16 to its active position 61, which is shown in FIG. 17 as well as in FIG. 18.

[0154] In the subsequent step, the separating device 40 is transferred from its parking position P of FIG. 17 to a central position M of FIG. 18. In the central position M, the separating device 40 is located at least partially in the central region 17 within the film tube 2, the opening device 13 still being located in the active position 35. As shown in FIG. 18, the contact unit 60 acts with one contact element 65 at a time on a side region 18 of the film tube 2. The central region 17 of the film tube 2 remains unaffected by the contact unit 60. After the separating device 40 has reached the central position M, the opening device 30 is first transferred from its active position 35 to the passive position 34, which is shown in FIG. 19. Subsequently, or in parallel, a transfer of the contact unit 60 from its active position 61 to its passive position 62 may take place, which is shown in FIG. 19. In the next step, the cutting device 20 is transferred from its activation state 24 to its deactivation state 25, so that the film tube 2 no longer has any severing cuts 3. Starting from FIG. 20, the separating device 40 can move from its central position M to the operating position B, which is shown in FIG. 21 and FIG. 22. In FIG. 22, the separating device 40 assumes its operating position B, in which it makes a severing cut at the foldinging line 16 in each case, so that a film web 6 is fed to each winding point as shown in FIG. 1.

[0155] As indicated in FIG. 22, it is conceivable that the contact unit 60 is arranged and/or supported on a frame 64, wherein the frame 64 can also act as a fastening means for the separating device 40 and/or the opening device 30. For example, it is conceivable that the separating device 40 can be moved to the respective position via a linear track system connected to the frame 64. The opening device 30 as well as the contact unit 60 can be moved to their respective locations or positions via a common control 63. The contact elements 65 of the contact unit 60 may, for example, be formed as elongated bars extending transversely to the transport direction Z. Alternatively, it is also conceivable that a deflection roller, which primarily serves to transport the film tube 2, acts as the contact unit 60, which can be brought into its active or passive position 61, 62 as a function of the retraction process I or extension process II.

[0156] FIGS. 23 to 30 show the extension process II according to the invention, which automatically transfers the separating device 40 from the operating position B shown in FIG. 23 to the parking position P shown in FIG. 30. In the operating position B, the film tube 2 is cut at its two folding lines 16. Starting from FIG. 23, in a first step of the extension process II, the cutting device 20 is first transferred to the activation state 25, so that two severing cuts 3 are made on the first tube side 2.1 of the film tube 2, which is shown in FIG. 24. According to FIG. 25, a transfer of the opening device 30 from the passive position 34 to the active position 35 takes place, whereby the opening elements 31 each protrude into a severing cut 3 of the film tube 2. In addition, a transfer of the contact unit 60 from the passive position 62 to the active position 61 takes place. The movement of the opening device 30 is coupled with the movement of the contact unit 60 in this embodiment, since both elements 30,60 are arranged on a common frame or are at least mechanically in operative connection. According to FIG. 26, the separating elements 41 leave their operating position B and move towards the central position M, which is reached in FIG. 27. According to FIG. 30, the opening device 30 is moved from the active position 35 to the passive position 34, and the contact unit 60 is moved from the active position 61 to the passive position 62. Likewise, the cutting device 20 is transferred from the activation state 24 to the deactivation state 25.

[0157] FIG. 31 to FIG. 40 now show an embodiment for counteracting a malfunction during the production of the film webs 6. In special cases it can happen that one of the two separating elements 40, which in particular can be configured as a knife, can fail, in particular move unintentionally from its operating position B into a parking position P. The reason for this can be of different nature. The causes for this can be of a wide variety of nature. For this purpose, a detection means 90 is provided which can effectively detect this failure. In order to avoid a complete production failure, an additional cutting device 80 is provided which is controlled in said failure case to be transferred from a sleep mode 82 to an operating mode 81 by the additional cutting device 80 making an additional cut 83 through both tube sides 2.1, 2.2. of the film tube 2. The additional cutting device 80 is connected to a control 84. The additional cutting device 80 is controlled as a function of the detection means 90, whereby for example a pressure sensor, position sensor, optical sensor can be used to detect the extent to which a malfunction of the type mentioned is present. Likewise, the worker can manually control the additional cutting device 80.

[0158] According to FIG. 32, the production can continue, whereby here it does not lead to a loss of flat web, since in this case of malfunction two film webs 6 continue to be fed to the respective winder according to FIG. 1. In FIG. 33, it is shown schematically that the malfunctioning separating element 41 has been replaced by a functioning separating element 41, whereby the retraction process I according to the invention can now be carried out automatically for the separating element 41 on the left in FIG. 33: First, the cutting device 20 is transferred to the activation state 24, so that two severing cuts 3 are made on the first tube side 2.1 of the film tube. Likewise, it is conceivable that only one severing cut 3 takes place, which preferably faces the disrupted separating element 41. This means that also only the left severing cut 3 would be sufficient for the retraction process I.

[0159] Subsequently, the opening device 30, which is not explicitly shown, is actuated according to FIGS. 34-40 in order to move it into the active position 35 so that the left separating element 41 can be reliably inserted into the film tube 2. Furthermore, the contact unit 60 not explicitly shown is also provided here, which is brought from its passive position 62 to its active position 61 in order to bring about a reliable movement of the separating element 41 into the central position M according to FIG. 35.

[0160] When the separating element 41 is in the central position M, as shown in FIG. 35, the transfer of the cutting device 20 to the deactivation state 25 takes place, so that no more severing cut 3 takes place. Subsequently, it is followed by:

[0161] Movement of the separating device 40, in particular of the left cutting element 41 from the central position M towards the operating position B, which is shown in FIGS. 36 to 39. Referring to FIG. 38, the additional cutting device 80 is then moved from its operating mode 81 to its sleep mode 82, so that no more additional cut 83 is introduced into the film tube 2. Finally, in FIG. 40, the separating device 40 with both cutting elements 41 is in its operating mode 81.

[0162] The control of the cutting device 20, the opening device 30, the separating device 40, the contact unit 60, the additional cutting device 80 can be effected via separate control units or also via a common control unit 11 as shown in FIG. 8. The detection means 90 can also be signal-technically connected to the control unit 11. The detection means 90 as well as the additional cutting device 80 may also be attached to said frame 64. Alternatively, separate attachment points independent of the frame 64 are conceivable.

[0163] According to a further alternative, the contact unit 60 in its active position 61 can act without contact on the flattened film tube 2, in particular on the side region 18 of the film tube 2, both for the described retraction process I and for the extension process II, so that all embodiments are also applicable to this alternative.

[0164] The foregoing explanation of the embodiments describes the present invention solely in the context of examples. Of course, individual features of the embodiments can be freely combined with each other, provided that this is technically reasonable, without leaving the scope of the present invention.

LIST OF REFERENCE SIGNS

[0165] 1 Blown film line [0166] 2 Film tube [0167] 2.1 First tube side [0168] 2.2 Second tube side [0169] 2.3 Width of 2 [0170] 3 Severing cut [0171] 3.1 Separation cut [0172] 4 Blow head [0173] 5 Flattened device [0174] 5.1 Guiding elements [0175] 6 Film web [0176] 7 Winder [0177] 8 Winding point [0178] 9 Tube film level [0179] 10 System [0180] 11 Control unit [0181] 11.1 Activation module [0182] 11.2 Winding module [0183] 11.3 Record module [0184] 12 Sensor unit [0185] 13 Constriction device [0186] 13.1 Constriction point [0187] 14 Extruder [0188] 15 Calibrating device [0189] 16 Folding line [0190] 17 Central region of the film tube [0191] 18 Side region of the film tube [0192] 20 Cutting device [0193] 21 Cutting elements [0194] 22 Control [0195] 23 Anti-adhesion device [0196] 24 Activation state [0197] 25 Deactivation state [0198] 30 Opening device [0199] 31 Opening element [0200] 32 Control [0201] 33 Opening sensor [0202] 34 Passive position [0203] 35 Active position [0204] 40 Separating device [0205] 41 Separating elements [0206] 42 Control [0207] 43 Guiding element [0208] 50 Control unit [0209] 51 Deflection unit, especially a roller [0210] 52 Air supply [0211] 60 Contact unit [0212] 61 Active position [0213] 62 Passive position [0214] 63 Control [0215] 64 Frame [0216] 65 Contact elements [0217] 70 Additional separation unit [0218] 71 Transverse severing means [0219] 80 Additional cutting device [0220] 81 Operating mode [0221] 82 Sleep mode [0222] 83 Additional cut [0223] 84 Control [0224] 90 Detection means [0225] 100 Method [0226] 101 Extrude [0227] 102 Cut [0228] 103 Flattening of 2 [0229] 104 Open from 2 [0230] 105 Separation of 2 [0231] 106 Solve from 6 [0232] 107 Separating head region from 2 [0233] 108 Winder [0234] B Operating position [0235] D Stretching force [0236] H Retaining force [0237] M Central position [0238] P Parking position [0239] Z Transport direction [0240] I Retraction process [0241] II Extension process