阅读说明：本技术 膜管输送、吹塑膜设备以及用于制造膜的方法 (Film tube transport, blown film installation and method for producing a film ) 是由 延斯·奥瑟美勒 于 2020-03-30 设计创作，主要内容包括：本发明涉及一种用于沿输送方向输送吹塑膜设备(1)的膜管(2)的系统(10),具有：用于引导膜管(2)的引导单元(51)、能够减小该膜管(2)的宽度(2.3)的缩窄部(13.1)、具有至少一个用于切断膜管(2)的切断元件(21)的切断装置(20),其中,该引导单元(51)沿膜管(2)的输送方向布置在缩窄部(13.1)的下游。本发明还涉及一种吹塑膜设备(1)和一种用于制造膜的方法(100)。(The invention relates to a system (10) for conveying a film tube (2) of a blown film installation (1) in a conveying direction, comprising: a guide unit (51) for guiding the film tube (2), a constriction (13.1) which can reduce the width (2.3) of the film tube (2), a cutting device (20) having at least one cutting element (21) for cutting the film tube (2), wherein the guide unit (51) is arranged downstream of the constriction (13.1) in the conveying direction of the film tube (2). The invention also relates to a blown film plant (1) and to a method (100) for producing a film.)

1. A system (10) for conveying a film tube (2) of a blown film plant (1) in a conveying direction, comprising:

-a processing unit (30), the processing unit (30) having a guiding unit (51) for guiding the film tube (2) and a narrowing (13.1) capable of reducing the width (2.3) of the film tube (2), and

-a severing device (20) with at least one severing element (21),

wherein the guide unit (51) is arranged downstream of the constriction (13.1) in the transport direction of the membrane tube (2),

wherein the cutting device (20) is designed in such a way that only the first tube side (2.1) of the tube section (3.1) of the film tube (2) can be cut off by means of the cutting element (21), so that air accumulated at the processing unit (30) can be released by means of the tube section (3.1).

2. System (10) according to claim 1, characterized in that a flattening device (5) is provided for flattening the film tube (2) to form two at least partially overlapping film layers, wherein the constriction (13.1) is formed by the flattening device (5).

3. System (10) according to claim 1 or 2, characterized in that the cutting device (20) has a transverse drive (22.1) for moving the at least one cutting element (21) transversely to the film tube (2) transport direction and/or

The cutting element (21) is fed at an oblique angle to the direction of transport of the film tube (2).

4. System (10) according to any one of the preceding claims, characterized in that the cutting device (20) has an advancing device (22.2) for moving the at least one cutting element (21) towards the film tube (2).

5. The system (10) as claimed in one of the preceding claims, characterized in that the cutting device (20) has a tube guide means (24), in particular in the form of a roller, by means of which tube guide means (24) the film tube (2) can be moved locally towards the cutting element (21).

6. The system (10) according to any one of the preceding claims, characterized in that the shut-off device (20) has a housing (25), wherein the shut-off device (20) can be placed in an activated state (I), in which the shut-off element (21) at least partially protrudes from the housing (25), and in a deactivated state (II); and in the deactivated state (II), the shut-off element (21) is arranged within the housing (25).

7. The system (10) according to one of the preceding claims, characterized in that the housing (25) has a displacement unit (26), by means of which displacement unit (26) the housing (25) can be moved between a release position (a) for producing the activation state (I) and a closed position (B) for producing the deactivation state (II), in particular wherein the housing (25) is pretensioned into the closed position (B) by means of the displacement unit (26).

8. System (10) according to one of the preceding claims, characterized in that the cutting device (20) is arranged in front of the guide unit (51) in the transport direction of the film tube (2) such that the film tube (2) can be cut by means of the cutting element (21) before the film tube (2) passes the guide unit (51),

preferably, the cutting device (20) is arranged in front of the constriction (13.1) in the transport direction of the film tube (2) such that the film tube (2) can be cut by the cutting element (21) before the film tube (2) passes the constriction (13.1).

9. The system (10) according to any one of the preceding claims, characterized in that the processing unit (30) has a stretching unit (52) and/or a stretching unit (52) is provided between the constriction (13.1) and the guiding unit (51), wherein the stretching unit (52) is capable of influencing the longitudinal stretching of the film tube (2), in particular wherein the cutting device (20) is arranged before the stretching unit (52) or within the stretching unit (52) in the transport direction of the film tube (2).

10. System (10) according to one of the preceding claims, characterized in that the shut-off element (21) is arranged such that the first tube side (2.1) is automatically cut through by the shut-off element (21) when a certain amount of accumulated air is present in the tube section (3.1) of the membrane tube (2) between the constriction (13.1) and the guide unit (51).

11. The system (10) according to one of the preceding claims, characterized in that the guide unit (51) has an air supply device (53), by means of which air supply device (53) an air cushion can be formed between the film tube (2) and the guide unit (51), in particular between the second tube side (2.2) of the film tube (2) and the guide unit (51).

12. The system (10) according to any one of the preceding claims, characterized in that the shut-off device (20) has an identification unit (27) for identifying the film tube (2), in particular an edge region (2.4) of the film tube (2).

13. System (10) according to any one of the preceding claims, characterized in that a mobile sensor unit (12) for detecting a membrane parameter of the membrane tube (2) is provided and that the shut-off device (20) is connected to the sensor unit (12) such that the membrane tube (2) can be shut off by means of the shut-off element (21) when the sensor unit (12) approaches the membrane tube (2).

14. Blown film plant (1) for manufacturing a film, having:

-a blowing head (4) capable of extruding a film tube (2) and

-a system (10) for conveying a film tube (2) in a conveying direction, in particular according to one of the preceding claims, the system (10) having a processing unit (30), the processing unit (30) having a guide unit (51) for guiding the film tube (2) and a narrowing (13.1) which can reduce the width (2.3) of the film tube (2), and the system (10) comprising a severing device (20) having at least one severing element (21) for severing the film tube (2),

wherein the guide unit (51) is arranged downstream of the constriction (13.1) in the transport direction of the membrane tube (2),

wherein the cutting device (20) is designed such that only the first tube side (2.1) of the tube section (3.1) of the film tube (2) can be cut off by means of the cutting element (21), so that air accumulated at the processing unit (30) can be released through the tube section (3.1) of the film tube (2).

15. Method (100) for manufacturing a film, in particular by a blown film plant (1) according to claim 14, comprising the steps of:

-extruding (101) a film tube (2) from a blow head (4),

-narrowing (102) the membrane tube (2), whereby the width (2.3) of the membrane tube (2) is reduced,

-guiding (103) the film tube (2) after the width (2.3) of the film tube (2) has been reduced,

-cutting off (104) only the first tube side (2.1) of the tube section (3.1) of the membrane tube (2) such that air accumulated after extrusion (101) of the membrane tube (2) is released through the tube section (3.1).

16. The method (100) according to claim 15, wherein the film tube (2) is flattened to form at least partially overlapping film layers when narrowing (102).

17. The method (100) according to claim 15 or 16, wherein, when cutting off (104) the first tube side (2.1), the film tube (2) is cut a plurality of times, in particular transversely to the transport direction of the film tube (2) and/or in the transport direction of the film tube (2).

18. Method (100) according to any one of the preceding claims, characterized in that, for severing (104) the first tube side (2.1), the film tube (2) is fed to a severing element (21) of a severing device (20) so that the severing element (21) performs the severing (104).

19. The method (100) according to any one of the preceding claims, wherein the severing (104) of the first tube side (2.1) is carried out before the deflection of the film tube (2), preferably before the narrowing of the film tube (2).

20. The method (100) according to any one of the preceding claims, wherein the shut-off device (20) for shutting off (104) the first pipe side (2.1) is brought from a deactivated state (II), in which a shut-off element (21) of the shut-off device (20) is arranged within a housing (25) of the shut-off device (20), into an activated state (I); and in the activated state (I), the shut-off element (21) protrudes at least partially from the housing (25).

21. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: stretching (105) the film tube (2) such that the longitudinal extension of the film tube (2) is influenced, in particular wherein the severing (104) of the first tube side (2.1) is carried out before said stretching (105).

22. The method (100) according to any one of the preceding claims, characterised in that the cutting (104) of the first tube side (2.1) is carried out automatically when a certain amount of accumulated air is present in the tube section (3.1) of the membrane tube (2) between the constriction (13.1) and the guide unit (51).

23. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: when guiding (103) the membrane tube (2), an air cushion is formed (103.1), in particular on the second tube side (2.2) of the membrane tube (2).

24. The method (100) according to any of the preceding claims, wherein the following steps are performed before cutting (104) the first pipe side (2.1): the membrane tube (2), in particular the edge region (2.4) of the membrane tube (2), is identified (104.1).

25. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: bringing a sensor unit (12) for detecting at least one membrane parameter of the membrane tube (2) into proximity (106), wherein the first tube side (2.1) is severed (104) when the sensor unit (12) is brought into proximity (106) with the membrane tube (2).

Technical Field

The present invention relates to a film tube transport system, a blown film plant for producing a film and a method for producing a film.

Background

Blown film plants are known in the prior art. Here, the film is extruded in the form of a film tube by extrusion from a blow head. The tube of film is then sent to a designated location such as, for example, a take-up device or the like. In order to make the film tube transportable, the film tube is usually flattened, i.e. a web is produced from a cylindrical tube at a specific transport section, with two flat tube sections of the film lying one on top of the other. When conveying flat film tubes, it is also usually provided to turn the film tube, i.e. to guide it, for example, over rollers, by means of which the film tube conveying direction is locally changed. The conveying direction can thus be realized, for example, by an angle. However, it can be problematic here that when the membrane tube is flattened at the constriction, air which may have collected before the deflection is entrained in the membrane tube. The deflection presses the parallel film sections against one another, so that the air originally in the tube is not entrained away during the deflection, which can lead to the formation of bubbles before the deflection and in particular after the constriction. This effect is enhanced if, after extrusion of the film tube by the blowing head, a bubble is produced by the air supply before the film tube is flattened. In particular, increased air pressure within the bubble may facilitate the entrainment of air through the constriction. But such air accumulation in the system can adversely affect the film quality characteristics. On the one hand, the film is therefore locally overstretched by the gas bubbles, so that the film is already plastically deformed during the production process. Furthermore, local interactions between the membrane and the guide unit in the air-entrainment region can cause dirt to be pressed into the membrane, so that further mass losses are also to be expected here.

Disclosure of Invention

The object of the present invention is to at least partially eliminate the above-mentioned disadvantages known from the prior art. The object of the present invention is, in particular, to avoid and/or reduce air accumulations during film production, in particular in blown film plants, preferably without adversely affecting the process safety and/or the plant safety.

The object is achieved by a system having the features of claim 1, a blown film plant having the features of claim 14 and a method having the features of claim 15. Further details and features of the invention emerge from the respective dependent claims, the description and the figures. The features and details described in connection with the system according to the invention naturally also apply to the blown film plant according to the invention and/or to the method according to the invention and vice versa in each case, so that the disclosure in connection with the various inventive aspects will always be or can be referred to one another.

According to the invention, a system for conveying a film tube of a blown film plant in a conveying direction is provided. The system has a processing unit with a guide unit for guiding the film tube, in particular during the transport of the film tube, and a narrowing that can reduce the width of the film tube. The system further comprises a cutting device having at least one cutting element, in particular for cutting the film tube. The guide unit is arranged downstream of the constriction in the direction of transport of the film tube. Furthermore, the cutting device is designed such that only the first tube side of the tube section of the membrane tube can be cut off by the cutting element, so that air which accumulates at the processing unit, in particular between the constriction and the guide unit and/or before the constriction, can be released, in particular during the transport of the membrane tube, through the tube section, which is in particular cut open.

The film tube transport system is preferably arranged in the film blowing installation downstream of a blowing head of a film blowing installation for producing a film tube in the film tube transport direction. The system can be a passive system, which has in particular no drive; or an active system that allows for active transport and/or transport of the membrane tubes. In the case of an active system, the system can have a drive unit for moving the film tube in the transport direction. In the case of a passive system, a drive unit for moving the film tube in the transport direction can advantageously be arranged downstream of the system in the transport direction. In particular, the membrane tube transport may comprise: guide the membrane tube and/or influence the direction of transport of the membrane tube. The film tube may in particular be guided through the system as a continuous material. The film tube preferably has a plastic film. It can furthermore be provided that the membrane tube extends in a cylindrical manner at least before reaching the system. During the transport of the film tube in the transport direction, the film tube can undergo a plurality of changes of direction, which can be ensured in particular by the one or more guide units.

The processing unit may in particular form a section of the system in which at least part of the film tube conveying process can take place. The processing unit can have a plurality of guide units, flattening devices and/or other components for conveying or processing the film tube. It is also conceivable that the processing unit is formed by a stretching unit for stretching and/or elongating the film material of the film tube, which stretching unit has a constriction and a guide unit. During operation of the system, air can accumulate at the processing unit, for example immediately before the constriction and/or between the constriction and the guide unit, in particular immediately before the guide unit. In particular, air can accumulate at the component parts of the processing unit. The guide unit may preferably comprise a deflection cylinder, which may be designed as a stationary or as a rotating roller. In particular, the film tube changes the transport direction due to the deflection. The "membrane tube width which can be reduced at the constriction" can in particular mean the elongation dimension and/or the diameter of the membrane tube which can be reduced at the constriction. In particular, the width can be measured perpendicular to the conveying direction. For example, the constriction may originate from a membrane tube delivery request. The "guide unit is arranged downstream of the constriction in the direction of transport of the membrane tube" can mean, in particular, that the membrane tube during transport first passes through the constriction and then passes through the guide unit. The guide unit can preferably be designed to deflect the film tube. The guide unit can thus be designed as a steering unit. However, it is also conceivable for the guide unit to guide the film tube and in particular not to influence the film tube transport direction. In particular, the guide unit can be driven in order to actively facilitate the film tube transport. It is also conceivable that the constriction is formed by a further guide unit.

The cutting element of the cutting device may be a mechanical cutting element. In particular, the severing element can be designed, for example, as a cutting knife. Preferably a cutting force of up to 10N, preferably up to 5N, can be applied to the first tube side by means of the mechanical severing element. It is also conceivable that the shut-off element is an optical and/or thermal shut-off element. For example, the severing element may comprise a laser for this purpose. In particular, the shut-off element is designed to form an opening, preferably in the form of a shut-off cut, in the first tube side. By "severing the film tube by means of the severing element" may in particular be meant that an inlet or opening into the tube is provided in the first tube side, i.e. in particular that the film material is completely severed at least in the form of perforations by the severing element. The openings are preferably introduced into the membrane tube in a chip-free manner during the cutting. Thus, the severing device may also be referred to as a cutting device, and/or the severing element may be referred to as a cutting element. The severing element can preferably be introduced at least partially into the membrane tube, wherein the membrane tube is, for example, at least partially pierced and/or cut open. In particular, the shut-off element can be designed for mechanical cutting through into the membrane tube. It is also conceivable that the cutting element has one or more needles. It can therefore be provided that the shut-off element is designed as a needle roller, which, for example, by rotation of the needle roller, introduces the needle into the film tube point by point, i.e., cuts through the first tube side. By "only the first tube side of the membrane tube section may be cut by the cutting element" it may be meant that the membrane tube is not completely cut. Thus, especially after flattening the film tube, only one of the two film layers which at least partially overlap may have a severing cut. Thus, as the shut-off element cuts through the first tube side, an access into the tube may be provided, through which a fluid communication between the inside and outside of the membrane tube may be achieved. Thus, if the pipe section passes through the constriction, the overpressure present in the membrane pipe can be reduced, in particular after the constriction. In particular, air can thus escape from the film tube through the cutting incision produced by the cutting element in the first tube side or tube section during the cutting, in particular when this tube section passes through the region between the constriction and the guide unit. The severing element is preferably designed to sever the film tube during operation of the blown film installation and/or during transport of the film tube.

In a simple manner, the air in the system can therefore be reduced, in particular during the transport of the membrane tubes, which can have an adverse effect on the membrane tube quality. It can thus be provided, for example, that the pipe section can be severed by the shut-off element when a certain amount of air has accumulated in the system or when a certain period of time has elapsed during the transport of the film tube. The cut tube sections can be removed or marked, for example, before winding and/or before further processing of the film tube.

In the system according to the invention, it can also be provided that a flattening device is provided for laying the film tube into two at least partially overlapping film layers, wherein the constriction is formed by the flattening device. In particular, it can be provided that the flattening device has a pressure roller by means of which the film tube is pressed at the constriction, so that two at least partially overlapping film layers are provided after the constriction. "film layers on top of each other" may refer to, for example, film segments that are oriented in a parallel or substantially parallel manner. The flattening device can preferably have a plurality of guide elements along which the film tube is guided in the flattening device such that the film tube width decreases in particular in a conical and/or tapered manner towards the narrowing. At the constriction, at least partial contact of the membrane layer can be achieved. By flattening the film tube, the film tube can be prepared to separate the film layers into two winding devices. The flattening device can in particular follow a film bubble which can be produced in the transport direction of the film tube after the blowing head of the blown film installation. In this way, an increased internal pressure of the film tube can be provided in the region of the film bubble, whereby in the region of the flattening device the entrainment of air into the other supply sections of the system can be promoted. Thus, it may be particularly advantageous to use a shut-off device to release the accumulated air after flattening the device.

It is also conceivable in the system according to the invention for the severing device to have a transverse drive for moving at least one severing element transversely to the film tube transport direction and/or for the severing element to be fed at an oblique angle to the film tube transport direction. The term "movement of the severing element transversely to the conveying direction" can mean, in particular, that the severing element can be moved perpendicularly to the conveying direction of the film tube. Thereby, for example, the inclination angle of the cutting cut can be obtained when the cutting piece is cut through into the film tube. If the film tube is moved simultaneously in the conveying direction, this can already be caused by a movement of the cutting element transversely to the conveying direction. If the cutting element cuts at an oblique angle relative to the direction of transport of the film tube, an oblique cut is obtained even when the cutting element is inserted shallowly into the film tube. The oblique cut-off cuts improve the escape of the accumulating air. Furthermore, during further transport, for example when passing a further constriction, further tearing of the severing cut can be reduced or prevented. Thus, further damage to the film layer can be avoided thereby improving the quality of the film product. The transverse drive can, for example, have a pneumatic drive, in particular with a unidirectional action, for example in the form of a pneumatic cylinder. The transverse drive may preferably have a resetting device, for example in the form of a spring, for resetting the severing element after severing of the first tube side of the tube section.

In addition, in the system according to the invention, it can advantageously be provided that the severing device has an advancing device for moving the at least one severing element toward the film tube. "moving the cutting element towards the membrane tube" may mean feeding the entire cutting element towards the membrane tube. In this way, for example, in the case of a mechanical cutting element, a blade can be inserted into the film tube. The propulsion device can be designed pneumatically, electrically and/or hydraulically. The transverse drive and the advancing device can preferably be integrated in a common drive in order to, for example, effect perforation of the film tube. By means of the advancing device, the severing element can advantageously be cut through the film tube point by point and/or in a local region.

In the system according to the invention, it is also conceivable for the cutting device to have a tube guide, in particular in the form of a roller, by means of which the film tube can be fed locally to the cutting element. The film tube transport direction can be locally changed by a tube guide mechanism in order to cut the film tube by means of a cutting element. Thus, for example, the cutting element of the cutting device can be constructed in a fixed form. The film tube can be severed by the severing element, in particular in the transport direction, if the film tube is fed to the severing element during transport, i.e. when the film tube is moved relative to the severing element. Whereby severing does not need to be performed by an active cutting action of the severing element. Furthermore, for example, the tube guide can be fed to the cutting element up to a predefined nominal distance. However, it is also conceivable for both the tube guide and the cutting element to be moved toward one another to achieve a predefined nominal distance. The height of the bubble inclusion in the film tube, from which the film tube is cut, can therefore be defined by a predefined nominal distance. It is therefore conceivable that the cutting is carried out automatically only from a certain size of the entrapped air bubbles, so that unnecessary damage of the membrane tube can be avoided.

In the system according to the invention, it is also conceivable for the shut-off device to have a housing, wherein the shut-off device can be brought into an activated state in which the shut-off element protrudes at least partially from the housing and a deactivated state in which the shut-off element is arranged in the housing. The housing may in particular have an opening through which the shut-off element can pass when the shut-off device is in the activated state. The safety of the system can be increased by the housing, since the shut-off element is hidden in the housing in the deactivated state and therefore cannot be accessed by the machine operator. Furthermore, the casing may protect the shut-off element from environmental influences and/or block components that might be dropped during maintenance work. The service life of the shut-off element as a whole can thereby be extended. For example, it is conceivable that the shut-off element can be at least partially removed from the housing in order to establish the activation state. The shut-off element is preferably pretensioned in the activated state, in particular so that the shut-off element can be automatically returned into the housing to bring the shut-off device into the deactivated state. The housing can be fixed or movable.

In the system according to the invention, it is also conceivable for the housing of the shut-off device to have a displacement unit by means of which the housing can be moved between a release position for producing the activated state and a closed position for producing the deactivated state, in particular wherein the housing is pretensioned into the closed position by means of the displacement unit. The displacement unit can in particular be mounted elastically in order to achieve pretensioning into the closed position. Switching between the activated state and the deactivated state can thus be achieved by the housing itself. In particular, the shut-off element can be designed to be fixed. When the housing is in the release position, the shut-off element can preferably be pushed out through an opening in the housing, wherein the opening can be designed in particular as a slit. In particular, a plurality of severing elements arranged in a row can be provided, which in the activated state protrude through the respective slot of the housing in order to effect the cutting of the film tube. As an alternative or in addition to the movement of the housing, a movement of the shut-off element can be provided in order to switch between the deactivated state and the activated state. Thus, the shut-off element may be moved through the opening in the housing. It is also conceivable that the laser is switched on to produce the active state, the laser being responsible for cutting the first tube side. The adjustability of the housing has the advantage, in particular, that no movement, in particular of the shut-off element, is required, as a result of which the safety of the system and/or of the blown film installation can be increased.

In the system according to the invention, it is also conceivable for the cutting device to be arranged in front of the guide unit in the transport direction of the film tube, so that the film tube can be cut by the cutting element before it passes through the guide unit. Preferably, it can be provided that the cutting device is arranged in front of the constriction in the transport direction of the film tube, so that the film tube can be cut by the cutting element before it passes through the constriction. By arranging the shut-off device before the guide unit, it is ensured that air can be released at this location. Alternatively, the shut-off device can be integrated, for example, into the guide unit itself, so that the air can be released, in particular immediately before the diversion. In particular, the cutting device can be arranged in the direction of transport of the film tube before the guide unit and after the constriction. By arranging the shut-off device before the constriction, the shut-off element can be introduced into the first pipe side in a simple manner. In particular, the membrane tube cannot yet be flattened before the constriction, i.e. it has a cylindrical and/or conical extension. In this way, it is possible in a simple manner to prevent the severing element from also cutting the second tube side opposite the first tube side. At the same time, if the shut-off device is arranged before the constriction, the air can be released immediately after the constriction, since the pressure between the inside and the outside of the membrane tube can already be equalized when the tube section passes the constriction.

In the system according to the invention, it is also conceivable for the processing unit to have a stretching unit and/or for a stretching unit to be arranged between the constriction and the guide unit, by means of which the longitudinal stretching of the film tube can be influenced, in particular here for the cutting device to be arranged in the transport direction of the film tube before or within the stretching unit. It is also conceivable for the cutting device to be arranged between the constriction and the drawing unit or between the drawing unit and the guide unit in the transport direction of the film tube. The stretching unit may for example be part of the guiding unit. In particular, a pretensioning of the film tube, in particular in the transport direction, can be achieved by the stretching unit. The film properties of the film tube can be influenced thereby, so that the quality of the film product can be improved. If the shut-off device is already arranged upstream of the drawing unit in the film tube transport direction, air can also be released or air accumulation can be prevented in this region. By arranging the cutting device after the stretching unit in the direction of transport of the film tube, advantageously no or little operator access is required in this area, so that system safety can be increased. Preferably, it can be provided that the drawing unit is designed to carry out a drawing method. Two guide units in the form of roller pairs can be arranged one after the other. The film tube may be introduced into the processing unit by a first roller pair. Furthermore, the second roller pair is operated at a higher rotational speed than the first roller pair to achieve longitudinal stretching of the film material of the film tube.

In the system according to the invention, it is also conceivable to arrange the shut-off element in such a way that the first tube side is automatically shut off by means of the shut-off element, in particular by cutting the shut-off element into the film tube, when a certain amount of accumulated air is present in the tube section of the film tube between the constriction and the guide unit. This can be achieved, for example, in that the film tube can be moved to the cutting element up to a predefined nominal distance or can be conveyed at a defined nominal distance from the cutting element. If a certain amount of air accumulates in the pipe section, this produces, in particular, air bubbles in the pipe section which are greater than the specified nominal distance of the shut-off element from the membrane pipe. In this case, the severing takes place by the movement of the film tube, even with a fixed severing element. The system and in particular the processing unit preferably has a bubble sensor, by means of which the actual amount of air accumulated in the membrane tube, in particular in the processing unit, can be monitored. Provision may be made here for the shut-off device to be activated when the actual quantity of air accumulated exceeds the target quantity. The target quantity may be preset or determined by the control unit based on dynamic operating parameters of the film tube as it is transported.

It is also conceivable in the system according to the invention for the guide unit to have an air supply, by means of which an air cushion can be formed between the film tube and the guide unit, in particular between the second tube side of the film tube and the guide unit. By means of the air cushion, the turning of the film tube at the guide unit can be carried out in particular in a contactless manner, i.e. without contact between the guide unit and the film tube. The air supply can be realized, for example, by a channel in the guide unit, wherein the channel can end at an opening in the deflection region of the membrane tube. The second tube side is in particular the tube side of the membrane tube which is opposite the first tube side. If the air cushion is formed on the second tube side, this has the advantage that no air can be fed again into the film tube via the tube section or the cutting slit of the cutting element by the air supply device. Instead, the closed side of the membrane tube is used to form an air cushion. Thus, the air in the membrane tube can also be kept low during the further transport of the membrane tube.

In addition, in the system according to the invention, it can be provided that the cutting device has an identification unit for identifying the film tube, in particular the edge of the film tube. The identification unit can in particular have a sensor. The sensor may in particular be an optical sensor. By identifying the film tube, in particular the edge portion of the film tube, it can be ensured that the severing device cuts only the first tube side and does not tear the film tube laterally even in the event of a change in the diameter of the film tube. This would otherwise lead to further tearing of the membrane tube during transport and/or the second tube side could be cut open. The severing of the film tube edge section can also result in, in particular, a notch, which is further torn open during the transport of the film tube, due to the film tube web tension in the transport direction. This can thus be avoided by identifying the edge portion and in particular avoiding cutting the edge portion.

In the system according to the invention, it can furthermore be advantageously provided that a movable sensor unit is provided for detecting a film parameter, in particular the thickness, of the film tube, and that the cutting device is connected to the sensor unit, so that the film tube can be cut off by means of the cutting element when the sensor unit approaches the film tube. In order to meet the quality requirements of the film products, it can be provided that film parameters, such as the thickness, transparency, etc., of the film material are detected by the movable sensor unit. The movable sensor unit may preferably be a movable optical sensor unit. The connection of the shut-off device to the sensor unit can be realized in particular by integrating the shut-off element into the sensor unit. Thus, only one drive means may be provided to move the sensor unit and the shut-off element. At least two functions can be integrated, and thus the complexity of the system structure can be reduced. Furthermore, the overall film product quality can also be improved by the sensor unit.

According to a further possibility, provision can be made in the system according to the invention for a control unit to be provided for actuating, i.e. in particular for controlling and/or regulating the shut-off device. Advantageously, the control unit (which may be a control and/or regulating unit) is in data communication with the shut-off device, which means in particular with the drive of the shut-off device and/or with the drive unit responsible for moving the film tube in the conveying direction. Preferably, the control unit may comprise a processor and/or a microcontroller. The control unit may also be part of the system and/or one of the winding stations. The automation of the blown film plant can be improved. It is also conceivable that the control unit is assigned to the blown film installation and/or the winding point.

In addition, in the system according to the invention, it can be advantageously provided that the control unit has an activation module for activating the shut-off device in order to perform a shut-off of the first tube side, in particular once, when the blown film installation is activated. When the blown film plant is started up, the cut tube sections can be simply classified as scrap, so that a continuous film tube material can subsequently be used at the winding station. Furthermore, especially at start-up of the blown film plant, it may be useful to open the film tube if the separating device has not been inserted into the film tube at start-up. The separation device may then be held in the separation position such that the membrane tubes are continuously separated. "starting the blown film plant" may particularly mean making a new film tube. In particular, the production of the blown film plant can be stopped and/or interrupted before starting up. The start-up of the blown film installation therefore provides an advantageous time for the actuation of the shut-off device. In particular, it can be provided that, during start-up, parts of the film tube are originally intended as waste material, so that tube sections, in particular with cut-out cuts, can also be disposed of without interrupting the film winding. Furthermore, the bubble can be adjusted by the internal pressure of the membrane tube at start-up, during which air can accumulate in the processing unit, in particular before the constriction. This can therefore be eliminated or reduced by cutting off the first tube side immediately upon start-up.

In the system according to the invention, it can furthermore be advantageously provided that the control unit has a winding module for detecting a reel change at least one of the winding stations and for cutting off the first tube side, in particular once, when a reel change is detected. Roll change may include a lateral separation of the entire film tube. An advantageous point in time can thus be provided when changing rolls, in order to restart the blown film installation and/or to cut off a portion of the film tube from the film tube. Thereby, the severing cut is not formed in the film product or can be arranged in a simple manner at the beginning or end of the roll. Damage to the film product of the winding station caused by the cut-off can thereby be avoided.

In the system according to the invention, it can also be advantageously provided that the control unit has a recording module for creating, in particular, a digital winding record, by means of which the cutting position of the first tube side can be assigned to the at least one film web. The digital winding record may contain information about the roll being manufactured from the film tube. By creating a winding record, the cut tube sections can be found and taken into account when the roll is further processed. It may thus for example not be necessary to remove the slit tube section from the film web prior to winding. Thereby increasing production speed and/or reducing waste.

According to a further aspect of the invention, a blown film installation for producing a film is claimed, having a blowing head which can extrude a film tube and having a system for conveying the film tube in a conveying direction, in particular a system according to the invention. The blown film apparatus has a processing unit having a guide unit for guiding the film tube, particularly when conveying the film tube, and a narrowing portion capable of reducing the width of the film tube. The blown film installation also has a cutting device with at least one cutting element for cutting the film tube. The guide unit is arranged downstream of the constriction in the direction of transport of the film tube. Furthermore, the shut-off device is designed such that only the first tube side of the tube section of the membrane tube can be shut off by the shut-off element, so that air which accumulates at the processing unit and in particular before the constriction and/or between the constriction and the guide unit can be released through the tube section of the membrane tube.

The blown film plant according to the invention therefore brings the same advantages as have been described in detail with reference to the system of the invention. The system is preferably arranged downstream of the blowing head in the transport direction of the film tube. In order to extrude the film tube from the blowing head, an extruder may be provided upstream of the blowing head. Because air may be released within the system as the film tube exits the blow head, the generation of undesirable air bubbles within the system may be reduced or avoided. Thereby reducing contamination of the resulting film product. In addition, film tearing, which may be attributable to tension in the film tube caused by air accumulation, may be reduced or avoided. The blown film device and/or system preferably has a drive unit for moving the film tube along the conveyor. In particular, the drive unit may be located downstream of the system. The film may be formed, inter alia, by dividing a film tube into one, two or more film webs. It is also conceivable, however, for the membrane tube to at least partially form the produced membrane if the membrane is provided, for example, in the manner of a hood.

According to another aspect of the invention, a method for producing a film, in particular by means of the blown film plant of the invention, is claimed. The method comprises the following steps:

-extruding a film tube from a blow head;

-narrowing the tube, in particular during its transport, by means of a constriction, so that the tube width is reduced;

after the film tube has been reduced in width, the film tube is guided and in particular deflected, in particular by a guide unit;

the first tube side of the tube section of the film tube is cut off only, in particular by a cutting element of the cutting device, so that the air accumulation is released through the tube section after the extrusion of the film tube, in particular before or after the constriction and before the guidance of the film tube, in particular during the transport of the film tube.

The method of the invention therefore has the same advantages as already described in detail with reference to the system of the invention and/or the blown film plant of the invention. For extruding the film tube, heating of the plastic pellets can be provided. The heated substance can still be at least partially liquid when the film tube is extruded from the blowing head. In particular, after extrusion from the blow head, the film tube may have a frost line where the film material of the film tube is cured. The first tube side can preferably be cut off after the frost line in the transport direction of the film tube. It is thereby ensured that the cutting incision, which is preferably produced during cutting, is defined by the cutting elements of the cutting device, in particular without severe deformation due to stickiness of the film material. The turning of the film tube can preferably comprise a change in the transport direction and/or in the angle of the transport direction of the film tube. Preferably, the film tube is turned as a lay flat film tube after it is flattened. When the membrane tube narrows, the inner region of the membrane tube, which may contain air, may be reduced in volume or at least change shape, for example, so that the membrane tube width is reduced. The membrane tube width may in particular comprise the extension width, i.e. in particular the diameter of the membrane tube. When the first tube side is severed, the severing element of the severing device is introduced into the film tube in particular in such a way that the severing cut that occurs involves and/or severs only the first tube side. The cutting off of the first tube side can also be a piercing into the first tube side. In particular, the severing of the first tube side comprises: the material bond in the region of the tube sections is released, so that an open incision is produced. The first tube side can in particular be opposite the second tube side, wherein the first tube side and the second tube side preferably form two at least partially overlapping film layers after the narrowing of the film tube. The method according to the invention thus allows air which accumulates in particular during operation and/or transport of the blown film installation, i.e. in particular during movement of the film tube, to be released. This is preferably done by the pipe section being conveyed along the region in which air accumulates, i.e. in particular before the diversion and/or before the guide device. Because the pipe sections have cut-outs, the air that accumulates, in particular when passing through this region, is released. In particular, the air that accumulates in such systems can create an overpressure within the membrane tube that is released as the slit tube segments pass through the region. Air accumulation can thereby be avoided, which can lead to a reduction in impurities and/or an improvement in the quality of the film product produced from the film tube.

Preferably, in the method according to the invention, it can be provided that the tube of film, when constricted, flattens out into two at least partially overlapping film layers. The two at least partially overlapping film layers correspond in particular to the first and second tube sides. In particular, the first tube side may form one of the two at least partially overlapping film layers, while the second tube side forms the other of the two at least partially overlapping film layers. The film tube can extend in particular in a cylindrical shape when it is extruded by means of a film blowing head. By the flattening, the cylindrical structure is changed into an approximately two-dimensional structure. The flattened film tube can be better transported, i.e. diverted and/or controlled in the device; on the other hand, the film tube can be split laterally to obtain a flat film before the winding point for winding at least one of the at least partially overlapping film layers of the flattened film tube. Other packaging and/or transport solutions can thus advantageously also be obtained for film products manufactured from film tubes.

In the method according to the invention, it can be provided that the film tube is cut off several times when the first tube side is cut off, in particular transversely to and/or in the direction of film tube transport. Perforation of the film tube can thus occur, wherein a larger area of the film tube can be covered by a plurality of severing cuts in the film tube to release air. The conveying speed of the film tube in the conveying direction can thereby be increased, since the delay in the escape of air can be reduced if the accumulated air is released through the cut tube section. In the case of a cut transverse to the conveying direction, a larger area of the film tube can thus be covered in the transverse direction. By means of the separating cut in the transport direction, it is also possible to release a large amount of accumulating air at high speed through the cut tube sections of the film tube. For the multiple severing of the first tube side, the severing element of the severing device of the blown film installation can preferably be moved transversely to and/or in the film tube transport direction.

In the method according to the invention, it can furthermore advantageously be provided that the film tube is fed to a cutting element of the cutting device for cutting the first tube side, so that the cutting element carries out the cutting. It can thereby be provided that the shut-off element is designed to be passive and/or fixed. Thus, for example, in the case of a mechanical cutting device, the knife can be designed to be immovable, so that the safety of the blown film installation can be maintained even at high-speed processing. The membrane tube may in particular be locally stretched, preferably with an elongation and/or force below the yield point of the membrane material of the membrane tube, when the membrane tube is moved towards the shut-off element.

In the method according to the invention, it is also conceivable to perform a first tube-side cut before the membrane tube is deflected, preferably before the membrane tube is narrowed. This ensures that air can escape at the correct location within the system. In particular, the film tube can be cut before it is deflected and after it has been narrowed. In this case, the air accumulation can thus escape directly when the switch is switched off. If the film tube is already cut open before the film tube is narrowed, an advantageous positioning of the cutting device, for example in a blown film installation, can be provided, wherein the first tube side can be cut in a particularly simple manner without damaging the second tube side. In particular in the region of the membrane tube before the constriction, the membrane tube can extend cylindrically, so that the first tube side and the second tube side are at least partially spaced apart from one another. If the cutting is carried out before the constriction of the membrane tube, it can be provided that air escapes after the cutting. In particular, air can also escape during the further transport of the membrane tubes in the transport direction.

In the method according to the invention, it is also conceivable for the shut-off device to be brought from a deactivated state, in which the shut-off element of the shut-off device is arranged in the shut-off device housing, into an activated state, in which the shut-off element projects at least partially from the housing, in order to shut off the first pipe side. It is thereby possible to achieve that the film tube is cut by the cutting element without access to the cutting element, in particular when the cutting element is not required. The safety of the blown film installation as a whole can thereby be further increased, since the shut-off element is not freely accessible, for example, during maintenance work. Furthermore, the shut-off element itself can be protected and thus the shut-off reliability can be improved, since for example falling parts and/or the like are caught by the housing in order to avoid damage to the shut-off element.

It is also conceivable in the method according to the invention that the method comprises the following steps: the film tube is stretched, so that the longitudinal extension of the film tube will be influenced, in particular wherein the severing of the first tube side is performed before the stretching. By stretching the film tube, the longitudinal extension of the film tube and thus in particular the film properties of the film tube can be varied. Here, since air is accumulated before the film tube is stretched, it is preferable to cut the first tube side before the stretching. The stretching can be carried out, for example, by a stretching unit, which can in particular be part of a guide unit of a blown film plant. The quality properties of the film product can thus be improved by stretching the film tube, wherein the advantage is obtained by the combination with the cutting that even when stretching the film tube, air which may accumulate does not adversely affect the quality properties, in particular in other respects.

Furthermore, in the method according to the invention it is conceivable that the first tube side is automatically shut off when a certain amount of accumulated air is present in the tube section of the membrane tube between the constriction and the guide unit. This can be achieved, for example, by arranging the cutting element at a defined nominal distance from the film tube and guiding the film tube past the cutting element. Thus, if the membrane tubes are locally charged by trapped or accumulated air, the membrane tube extension dimension changes, which increases with more and more accumulated air. In addition or alternatively, an electronic control device may be provided, which generates an activation state of the shut-off device, for example when a certain amount of accumulated air has been detected. For this purpose, for example, a sensor unit for detecting the accumulation of air and/or the internal pressure of the membrane tube can be provided. In particular, small amounts of accumulated air may be harmless in the process and can therefore be tolerated. The specific quantity of accumulated air may for example be a quantity of accumulated air that seriously affects the quality properties of the membrane product and/or the membrane tube.

Furthermore, provision can advantageously be made in the method according to the invention for the method to comprise the following steps: when the film tube is deflected, an air cushion is formed, in particular on the second tube side of the film tube. By forming the air cushion when the film tube is deflected, a particularly touchless and/or contactless film tube guidance can be achieved. This can prevent the film tube from contacting the guide unit, in particular the deflecting roller. This makes it possible to maintain the surface properties of the membrane tube particularly advantageously and/or to avoid contamination. Thus improving quality overall. If the air cushion is also formed on the second tube side, this has the advantage that no air is introduced into the membrane tube because of the air cushion, which would lead to a bubble formation again. Instead, the closed second tube side of the membrane tube may be in contact with the air cushion.

Furthermore, in the method according to the invention, provision can advantageously be made for the following steps to be carried out before the first tube side is severed: the membrane tube, in particular the edge portion of the membrane tube, is identified. By identifying the edge portion of the film tube, damage to the edge portion at the time of cutting can be avoided. Especially when the film tube is extruded from the blow head, the film tube diameter fluctuates. By identifying the film tube and/or the film tube edge section, the cutting element of the cutting device can be adjusted accordingly, for example, for cutting. This prevents the film tube from being cut in the edge section during the cutting operation, which could lead to tearing of the film tube due to tensile stress of the film tube in the transport direction of the film tube. Thus improving process safety.

Furthermore, provision can advantageously be made in the method according to the invention for the method to comprise the following steps: a sensor unit for detecting at least one membrane parameter of the membrane tube is brought into proximity, wherein the first tube side is severed when the sensor unit is brought into proximity with the membrane tube. The acquisition of the membrane parameters and the cutting off of the first tube side can thereby be carried out simultaneously. Thus, multiple production steps for making the film can be performed simultaneously and/or in coordination with each other, thereby increasing process safety and reducing the complexity of the blown film apparatus. Furthermore, the number of drives of the blown film plant can be reduced, resulting in cost advantages and/or safety advantages.

In the method according to the invention, it is furthermore conceivable for the first tube side to be cut off at the start of the blown film installation, in particular once. The start-up provides an advantageous moment for the first tube side to be cut off, in particular when the membrane tube head is produced as waste material in any case at the start-up. The start-up may be ended when the film web is wound into at least one roll.

In the method according to the invention, it can furthermore be advantageously provided that the film web is wound into at least one roll, preferably two film webs are wound into two rolls, in particular wherein the first tube side is cut off when a roll change is detected. In particular, the roll change can be carried out depending on the film product packaging of the film tube. Here, a full roll can be removed from the winding station and an empty winding roller can be provided at the winding station. For this purpose, the blown film plant can advantageously be stopped or its production speed can be reduced. The pipe section damaged by the cutting of the incision can thus be identified and/or removed in a simple manner.

In the method according to the invention, it is also conceivable to create, in particular, a digital winding report, by means of which the position of the first tube-side severing cut for the at least one film web can be assigned. This makes it possible, for example, to report the position of the severing cut and thus, in particular, the damage to the pipe section to further processing. It may not be necessary to remove the cut tube section beforehand prior to winding.

Drawings

Further advantages, features and details of the invention emerge from the following description of an embodiment of the invention with reference to the drawing. The features mentioned in the claims and the description may be of importance for the invention here, individually or in any combination, the figures showing schematically:

figure 1 shows a film blowing plant according to the invention with a system for transporting film tubes according to the invention,

figure 2 shows the steering system of the first embodiment,

figure 3 shows the cut-off device of the system of the first embodiment,

figure 4 shows a method for manufacturing a membrane according to the invention,

figure 5 shows a cut-off device according to another embodiment,

figure 6 shows a cut-off device according to another embodiment,

figures 7 and 8 show a cut-off device according to another embodiment,

figure 9 shows another embodiment of a system for transporting a membrane tube according to the invention,

figure 10 shows a cutting element for a cutting device according to another embodiment,

figure 11 shows a cut-off device according to another embodiment,

fig. 12 shows a processing unit in the form of a drawing unit.

Detailed Description

In the following description of the embodiments of the present invention, the same reference numerals are used for the same features in different embodiments.

Fig. 1 shows a schematic representation of a blown film installation 1, in which a film tube 2 is extruded from a blowing head 4 and conveyed in a conveying direction Z. The material of the film tube 2 is initially still present in the form of a melt-like extrudate. The plastic is first plasticized in the extruder 14. The formed mass is sent through a connecting line to a blow head 4, whereby a film tube 2 is formed from the mass. The blow head 4 may be assigned further extruders so that multilayer films can be produced. A method 100 for manufacturing a film by means of a blown film plant 1 according to the invention is shown in fig. 4. In the following description of the blown film installation 1, reference is also made here to this method 100.

When the film tube 2 is extruded 101 from the blow head 4, it initially exists as a film bubble with an internal pressure slightly above ambient pressure on leaving the blow head 4. As the internal pressure increases, the not yet solidified material of the membrane tube 2 bulges. Finally, the diameter and/or the film material thickness of the finished film tube 2 is influenced in this way.

Subsequently, the not yet solidified film bubble or film tube 2 enters the sizing device 15. Here, the diameter of the membrane tube 2 is limited. Inside or below the sizing device 15, the film tube 2 is cooled to a temperature at which subsequent deformation is virtually impossible, in particular only with the use of greater forces. The location where the phase change occurs is commonly referred to as the "frost line".

After leaving the sizing device 15, the film tube 2 enters the flattening device 5, in which flattening device 5 the film tube 2 is almost completely reshaped into a flat, double-layered film web. The film tube 2 is thus flattened by the flattening device 5 into a double-layered plastic film, which is connected in particular at the edge portions. For this purpose, the flattening device 5 has a guide 5.1, by means of which guide 5.1 the width 2.3 of the film tube 2 can be reduced stepwise or continuously.

In the present exemplary embodiment, blown film installation 1, in particular stretching device 5, has a pressing device 13 with pressing rollers, in particular so-called nip rollers, which prevent large amounts of air from being trapped in film tube 2 during the further transport of the film tube. Preferably, one or both of the squeeze rollers may be driven to assist in the transport of the film tube 2. The narrowing 102 of the film tube 2 is performed by the flattening device 5 and/or the pressing device 13, wherein the width 2.3 of the film tube 2 is reduced when the film tube 2 is guided past the flattening device 5 and/or the pressing device 13. In the system 10 according to the invention for transporting membrane tubes 2, at least one constriction 13.1 is thus formed by the flattening device 5 and/or the pressing device 13.

The film tube 2 is further conveyed to the two winding stations 7, 8 by means of transport rollers, parts of which are not explicitly shown, which can form further constrictions 13.1. For conveying the film tube 2, a drive unit 50 is provided, which in particular also applies a web tension to the film tube 2. The pressing device 13 and the constriction 13.1 formed thereby together with the at least one guide unit 51 and/or the deflection system 60 form a processing unit 30, by means of which processing unit 30 at least the film tube 2 is allowed to be transported and/or further processed.

However, when the membrane tubes 2 are conveyed through the constriction 13.1, small amounts of air can be entrained, which can accumulate in the membrane in the form of air bubbles 16 during the production process. The accumulated air can form, for example, bubbles 16 before the deflection system 60, in particular before the guide unit 51 for guiding 103 and in particular deflecting the film tube 2 to 103. In this case, for example, air particles from the lumen of the membrane tube 2 can be carried through the constriction 13.1 before flattening. In the region of the gas bubbles 16, the film tube 2 thus bulges locally, which already may lead to a negative effect on the film product quality. Furthermore, a pressure increase between the film tube 2 and the guide unit 51 may occur due to the gas bubble 16, so that impurities may be pressed into the film tube 2, leading to a further loss of quality.

In order to be able to release the air accumulated in the air bubbles 16, a cutting device 20 having at least one cutting element 21 for cutting 104 the film tube 2 is provided. The shut-off device 20 is designed such that only the first tube side 2.1 of the tube section 3.1 of the membrane tube 2 can be shut off by the shut-off element 21, in particular the shut-off element 21 can be introduced into the first tube side 2.1, so that the accumulated air can be released by the tube section 3.1 at the processing unit 30, i.e. in particular here before the constriction 13.1 and/or between the constriction 13.1 and the guide unit 51. In the exemplary embodiment shown here, the shut-off device 20 is arranged in the region of the flattening device 5. But here alternative arrangements of the shut-off device 20 are conceivable, as shown for example in fig. 9. Thus, by cutting the film tube 2, a cut-out tube section 3.1 with a cutting cut 3 is produced, the tube section 3.1 being moved in the transport direction of the film tube 2 with the transport of the film tube 2. If the cut-out tube section 3.1 passes through the region between the constriction 13.1 and the guide unit 51, air trapped in the air bubble 16 can escape, in particular because the cut-out 3 allows passage from the outer region into the inner region of the membrane tube 2. This makes it possible to equalize the overpressure in the membrane tube 2.

Fig. 2 shows a more detailed view of the narrowing 13.1 and the steering system 60 with a plurality of guide units 51 in a schematic illustration. One of the guide units 51 comprises an air supply 53, by means of which an air cushion 103.1 can be formed between the film tube 2 and the guide unit 51, so that a contactless deflection of the film tube 2 or of the direction of transport of the film tube 2 at the guide unit 51 can be carried out. The guide unit 51 may be provided as a rotatable roller or a fixed roller, in particular. Due to the steering, especially due to the large angle at which the steering is performed, air accumulation may be promoted. The guide unit 51 is also preferably a cooling roller, by means of which the film tube 2 can be cooled after extrusion 101 from the blow head 4. Furthermore, a stretching unit 52 can be provided between the guide unit 51 and the constriction 13.1, by means of which stretching unit 52 the stretching 105 of the film tube 2 can be carried out. The film properties of the film tube 2 can be influenced by the stretching unit 52, since an elongation force is added to the material. The stretching unit 52 may form a further guiding unit 51 and/or a narrowing 13.1. Furthermore, the system 10 for transporting the film tube 2 can have further guide units 51 and/or further stretching units 52.

When the membrane tube 2 is cut 104 by the cutting device 20, only the first tube side 2.1 of the tube section 3.1 of the membrane tube 2 is cut. Thus, a second tube side 2.2 opposite the first tube side remains as a closed membrane section. This has the advantage that, when the film tube 2 is wound at the winding points 7, 8, only the first tube side 2.1 is damaged by the severing cut 3 and the tube section 3.1 with the severing cut 3 is fed into only one of the winding points 7, 8. Provision can also be made for the air supply 53 of the guide unit 51 to be arranged in such a way that an air cushion can be formed between the film tube 2 and the guide unit 51 on the second tube side 2.2 of the film tube 2. Thereby, air is no longer introduced into the film tube 2 through the air supply device 53. In particular, a plurality of guide units 51 with a plurality of air supply devices 53 may be provided, wherein all air inlets 53 are preferably designed for forming an air cushion between the respective guide unit 51 and the second tube side 2.2.

Fig. 3 shows a further schematic view of the severing device 20 in the region of the flattening device 5. A drive 22 is provided, by means of which the cutting element 21 of the cutting device 20 can be moved relative to the film tube 2 and/or relative to the flattening device 5. In particular, the drive 22 can have a transverse drive 22.1, by means of which the cutting element 21 can be moved transversely to the transport direction Z of the film tube 2, in particular perpendicularly to the transport direction Z of the film tube 2. The cutting element 21 can preferably be moved repeatedly towards the film tube 2 and back by means of the transverse drive 22.1. This makes it possible to perforate the membrane tubes 2 in the region of the membrane tubes 2, so that the release of air in the region of the air bubbles 16 can be improved. In particular, a diagonal cut pattern can thereby be applied when the film tube 2 is moved relative to the cutting element 21 and the cutting element 21 is moved transversely. Preferably, the cutting device 20 has an identification unit 27, which is designed to identify 104.1 the film tube 2, in particular the edge section of the film tube 2. This prevents the cutting element 21 from forming a cut 3 in the edge of the film tube 2.

Fig. 5 also shows the cutting device 20 in a side view. In order to be able to form a cutting incision 3 in the first tube side 2.1 of the film tube 2, the cutting device 20 has an advancing device 22.2 for the cutting element 21. The propulsion device 22.2 can be designed, for example, to be manual, pneumatic, hydraulic and/or electric. The cutting element 21 and/or the advancing device 22.2 are preferably connected to a sensor unit 12 for detecting a membrane parameter of the membrane tube 2, so that the advancing device 22.2 can be used for both components. Thus, if the sensor unit 12 approaches the membrane tube 2, a cut-out 3 can be automatically generated in the first tube side 2.1. The shut-off element 21 can thereby be fed to the film tube 2 until the shut-off element 21 has been introduced into the film tube 2 on the first tube side 2.1. The movement of the film tube 2 during the transport process causes the film tube 2 to be subsequently cut. "arranged in the region of the flattening device 5 or at least before the constriction 13.1" has the advantage that the severing cut 3 can be formed in a simple manner only in the first tube side 2.1, in particular because the film webs are still spaced apart from one another here. In this case, the knife-like cutting element 21 has a high tolerance range when it is inserted into the film tube 2, since the second tube side 2.2 is still spaced apart from the first tube side 2.1. The cut-open tube section 3.1 thus passes first through the constriction 13.1 and then through the entire region between the constriction 13.1 and the guide unit 51 during the transport of the membrane tube 2, so that air can escape continuously during this time. The identification 104.1 of the film tube 2 and/or of the edge section of the film tube 2 is preferably carried out before the cutting element 21 is introduced into the film tube 2 by the pushing device 22.2. In particular, the identification 104.1 can be carried out by the sensor unit 12. Additionally or alternatively, the sensor unit 12 can be arranged, in particular, fixedly behind the steering system 60 and/or in front of the drive unit 50 in order to detect the film properties of the pipe section 3.1 and/or the film pipe 2.

Fig. 6 shows a cutting device 20 for cutting the film tube 2 only on the first tube side 2.1 by means of a stationary cutting element 21. If air accumulates in the film tube 2, air bubbles 16 may form, which air bubbles 16 thus locally swell the film tube 2. The stationary shut-off element 21 is arranged here at a nominal distance 21.1 from the membrane tube 2, which is designed to shut off only when a certain air accumulation volume is reached. If the gas bubble 16 thus reaches a size 16.1 which is greater than the nominal distance 21.1 of the cutting element 21 from the film tube 2, the cutting of the first tube side 2.1 can be carried out automatically during the transport of the film tube 2.

Fig. 7 and 8 also show a further exemplary embodiment of a shut-off device 20 in a schematic side view. The cutting device 20 has a cutting element 21 for cutting the film tube 2 only on the first tube side 2.1 of the film tube 2. The shut-off element 21 is arranged in the housing 25 such that the shut-off element 21 is at least partially protected from environmental influences. Provision is also made for the shut-off device 20 to be able to be brought into a deactivated state II, in which the shut-off element 21 is arranged in the housing 25. The deactivated state II is shown in fig. 7. Fig. 8 also shows the activated state I of the shut-off device 20, in which the shut-off element 21 at least partially protrudes from the housing 25. Thereby, the membrane tube 2 can be cut. Furthermore, the housing 25 has a displacement unit 26, by means of which displacement unit 26 the housing 25 can be moved between a release position a for producing the activation state I and a closed position B for producing the deactivation state II. The displacement unit 26 may elastically support the housing 25 such that the housing 25 is pre-tensioned to the closed position B. Furthermore, a roller-shaped tube guide 24 is provided, by means of which the film tube 2 can be fed to the housing 25 and the cutting element 21. The film tube 2 is thus pressed against the housing 25 when the tube guide 24 is moved, and the housing is correspondingly moved into the release position a, so that the shut-off element 21 projects through an opening, for example in the form of a slit, of the housing 25. Thereby allowing the first tube side 2.1 to be cut through the cutting element 21. Preferably, the cutting device 20 of the present embodiment may be arranged in close proximity to the guide unit 51, preferably between the guide unit 51 and the stretching unit 52. Here, it is very well possible for bubbles to form, so that, when the film tube 2 is pressed onto the housing 25 or the shut-off element 21, advantageously only the surface of the bubble 16 and thus the first tube side 2.1 of the film tube 2 are cut. For this purpose, the nominal distance 21.1 of the cutting element 21 from the film tube 2 and/or from the tube guide 24 can be designed according to the nominal distance 21.1 according to fig. 6.

Fig. 9 shows a further exemplary embodiment of the inventive system 10 with a processing unit 30 as a detail of the inventive blown film installation 1, together with different possible positioning of the cutting device 20 for cutting 104 the film tube 2. Here, the shut-off device 20 can be arranged before the constriction 13.1 which reduces the width 2.3 of the membrane tube 2. This has the advantage that only the first tube side 2.1 of the membrane tube 2 can be cut off in a simple manner, since the first tube side 2.1 is still spaced apart from the second tube side 2.2. Furthermore, the air accumulating at the processing unit 30 can escape from the membrane tube 2 already before the constriction 13.1. It is also conceivable for the shut-off device 20 to be arranged between the constriction 13.1 and the guide unit 51 for guiding, in particular deflecting, the film tube 2. It is expected that air will accumulate and can therefore be released directly in areas that may be adversely affected by it. Provision may also be made for the cutting device 20 to be arranged between the two guide units 51. For example, it can be provided that the first guide unit 51 has only a small angle for steering, so that the air still passes through the first guide unit 51. Thus, the shut-off device 20 may also be used in locations where air accumulation is expected. In particular, the constriction 13.1 can also be formed by a further guide unit 51 arranged in front of the guide unit 51, in particular in the transport direction of the film tube 2.

Fig. 10 shows a cutting device 20 of another embodiment. The cutting device 20 has a cutting element 21 in the form of a needle. The individual needles can be introduced into the film tube 2, i.e. cut into the film tube 2, in order to perforate the film tube 2. Sufficient convection between the inner region of the membrane tube 2 and the outer region of the membrane tube 2 can thereby also be achieved in order to be able to release the accumulated air.

Fig. 11 also shows another embodiment of a cutting device 20. The cutting device 20 has a plurality of, in particular two, cutting elements 21. Two parallel severing cuts 3 can thereby be obtained, so that a large area of the film tube 2 can be covered to release the accumulating air, in particular without transverse movements of the severing element 21.

Fig. 12 shows a processing unit 30 in the form of a stretching unit 52 for performing the stretching process. Thus, the two guide units 51 are arranged one after the other in the form of a roller pair. The film tube 2 is introduced into the processing unit 30 by means of the first roller pair 51, while the longitudinal stretching is carried out by means of the second roller pair 51 at a higher rotational speed than the first roller pair 51, in particular in a manner stretching in the left-right direction, as indicated by the dashed arrows. Depending on the geometry of the film tube 2, in particular the edge geometry, it is preferably possible to achieve a better adhesion of the edge portions to the roller pairs 51, so that a transverse-to-longitudinal shrinkage or a width reduction of the film tube 2 is reduced or avoided. The edge portions may be cut away after the longitudinal stretching. The cut-off edge portions can then be recovered, for example, in such a way that they are again fed into the circuit as raw material.

The above explanation of the embodiments describes the present invention only in the scope of examples. Of course, the individual features of the embodiments can be freely combined with one another as far as technically meaningful, without departing from the scope of the invention.

List of reference numerals

1 blown film plant

2 film tube

2.1 first tube side

2.2 second tube side

2.3 Width of the Membrane tube 2

3 cutting the incision

3.1 pipe section

4 blow molding head

5 flattening device

5.1 flattening guide mechanism

6 film web

7 winding station

8 winding station

9 plane of tube film

10 system

11 control unit

11.1 starting Module

11.2 winding Module

11.3 recording Module

12 sensor unit

13 extrusion device

14 extruder

15 sizing device

16 bubbles

16.1 bubble 16 size

20 cutting device

21 cutting element

21.1 nominal distance

22 drive device

22.1 transverse drive

22.2 Propulsion device

23 anti-adhesion device

24 pipe guide mechanism

25 outer casing

26 displacement unit

27 identification unit

30 processing unit

50 drive unit

51 guide unit, in particular roller

52 stretching unit

53 air supply device

60 steering system

70 auxiliary separation unit

71 transverse separating device

100 method

101 extrusion

102 narrowing

103 guiding, in particular steering

103.1 forming an air cushion

104 cutting off

104.1 identification of Membrane tubes 2

105 stretching

106 proximity of the sensor unit 12

D stretching force

H holding power

Z conveying direction