Patent Application
20210380364
The invention relates to a film winding system and an assembly of a film stretching unit with such a Film winding system.
Film stretching units are used to produce a film web from a plastic melt which has certain material properties so that it can be used for specific purposes. The film stretching units comprise longitudinal and/or transverse stretching zones. The line speed is increasing more and more and is nowadays already more than 400 m/min. In the future, even faster film stretching units will be put into operation. In this context, an important aspect is also how the finished end product, namely the film web, is wound up. Film winding systems are provided for this purpose, which wind up the film web produced. When winding, however, it is important that no folds are pressed into the film web and that sufficient air is still wrapped in so that the individual layers can be separated from each other more easily later. The film web is wound up at a winding station. The winding station comprises a corresponding base body around which the film web is wound. However, the film web is fed to an internally known winding station via a contact roller to ensure optimum alignment before winding. The film web covers the contact roller over 90° or over 0°. In the case of an overlap, which is named in the following “degree of wrapping”, of 0°, the film web runs between the contact roller and the film bale (also referred to as the wrapping bale) into the film bale. Using a degree of wrapping of 90°, the film web is deflected by 90° at the contact roller before it runs into the film bale. At higher line speeds, there is definitely room for improvement for this internally known concept.
The object is therefore to create a film winding system and an assembly of a film winding system and a film stretching unit that ensures that the film web is reliably wound up.
The object is solved by the film winding system according to claim 1 and by the assembly of the film stretching unit and the film winding system according to claim 20. The dependent claims comprise further embodiments of the film winding system.
The film winding system comprises a film entry area through which a film web to be wound can be fed to the film winding system. A first winding station is also provided. The first winding station is configured in a winding position to wind the film web into a film bale. A contact roller and a measuring roller are also provided. The contact roller is arranged (directly) adjacent to the first winding station (when the latter is in the winding position) and configured to guide the film web to the first winding station. The term “directly” should be understood in such a way that the contact roller is in contact with the film bale or that only the film web, which is wound onto the film bale, runs between the contact roller and the film bale. However, a free space could also be formed between the contact roller and the film bale. This free space, namely the distance, is preferably smaller than 100 cm, 80 cm, 70 cm, 60 cm, 50 cm, 40 cm, 30 cm, 20 cm, 10 cm, 5 cm, 3 cm, 2 cm, 1 cm or smaller than 0.1 cm. The measuring roller is arranged in front of (before) the contact roller in the movement direction of the film web and is configured to guide the film web to the contact roller. The wording “in the movement direction of the film web” should be understood in such a way that a certain area of the film web first runs over the measuring roller and only then (after that) over the contact roller. Furthermore, a first adjustment device is provided and configured to move the measuring roller relative to the contact roller along a travel path in such a way that a degree of wrapping over which the film web covers (touches) the contact roller can be changed. A “degree of wrapping” is a value of how far the film web covers the contact roller. The contact roller extends over 360°. Having a degree of wrapping of 90°, the film web would only rest on a quarter of the circumferential surface of the contact roller, which is in particular cylindrical. Having a degree of wrapping of 180°, on the other hand, the film web would rest on half of the outer surface of the contact roller, which is in particular cylindrical.
It is particularly advantageous that the degree of wrapping can be varied. This is achieved by first passing the film web over a measuring roller and only then transferring it from the measuring roller to the contact roller. By changing the position of the measuring roller in relation to the position of the contact roller, the degree of wrapping can be changed because the area of impact of the film web on the contact roller can be adjusted. According to the invention, the degree of wrapping can therefore be individually amended to the requirements of the film web. The degree of wrapping can therefore be optimally adjusted to film properties, such as material thickness, material strength, material elongation or shrinkage. For each material, therefore, an optimum can be set with regard to the degree of wrapping to achieve the best film bale. For small degrees of wrapping, the contact roller can only have a minor influence on the film tension. With larger degrees of wrapping, an increasingly greater influence can be exerted on the film tension (through drive or braking torques on the contact roller). Extensive internal investigations have shown that smaller degrees of wrapping are advantageous for thick film webs, while larger degrees of wrapping are advantageous for thin film webs. Thicker film webs are less affected by film web flutter than thinner film webs. Stiffer film webs can be wound better with degrees of wrapping close to 0°, while film webs with shrink films, for example, are wound better with larger degrees of wrapping. It was found out that, in particular, a film web with a shrink film should be wound with a degree of wrapping of approximately 90° (less than 3° deviation), whereas film webs with a thick film or with a film of high strength should be wound with a degree of wrapping of approximately (less than 3° deviation) 0°.
In one embodiment of the film winding system, the first adjustment device is configured to move the measuring roller relative to the contact roller along the travel path during operation, i.e. while the film web is being wound, in order to change the degree of wrapping during operation. This makes it possible to react immediately to changing parameters of the film web. For example, it is possible that the film web to be produced changes very quickly, requiring different degrees of wrapping. Loosening screw connections and rebuilding system parts is then not necessary and would also not be helpful. The first adjustment device is configured in particular to move the measuring roller steplessly relative to the contact roller. Moving the measuring roller in discrete steps (for example via latching steps) relative to the contact roller would also be possible.
The first adjustment device is configured to move the measuring roller along the entire travel path or along the predominant part of the travel path with a first movement vector and/or a second movement vector. For this purpose, the first adjustment device comprises a first guide system. The first guide system can be used to move with the first movement vector. In addition or alternatively, the first adjustment device also comprises a second guide system. The second guide system can be used to move with the second movement vector. The first or second guide system can be in form of a slide system or a rail system, for example. The measuring roller itself can be mounted on the first guide system or the second guide system. Optionally, it is again possible for the first guide system to be mounted on the second guide system or for the second guide system to be mounted on the first guide system. In this case, it would be possible for the measuring roller to be moved via the first guide system with the first movement vector and simultaneously via the second guide system with the second movement vector. However, this is optional. In a simple embodiment, the measuring roller could be moved only with the first movement vector or only with the second movement vector. The movement of the measuring roller in order to change the degree of wrapping is always relative to the contact roller.
In one embodiment of the invention, the first movement vector comprises only one component in the X-direction. This component is unequal to zero. The other components (Y-direction, Z-direction) are zero. The X-direction runs parallel to the floor in the direction of the film entry area. The Y-direction runs in the longitudinal direction of the contact roller or the measuring roller. The Z-direction runs perpendicular to the ground away from the ground. The second movement vector comprises components in the X-direction and in the Z-direction which are unequal to zero. The component in Y-direction is zero. This means that the measuring roller only moves horizontally when moving with the first movement vector. When moving with the second movement vector, the measuring roller would move slantwise.
When the measuring roller is moved with the second movement vector, it can be moved further in the Z-direction than in the X-direction over the entire travel path. It would also be possible for the measuring roller to be moved further in the X-direction than in the Z-direction. In principle, the measuring roller could also be moved for the same distance in the Z-direction as in the X-direction over the entire travel path (45° course). When moving the measuring roller with the second movement vector, the ratio between the component in the X-direction and the component in the Z-direction would preferably be constant over most of the travel path or over the entire travel path.
Preferably, the second movement vector forms an angle with an XY-plane that is larger than 10°, 20°, 30°, 40°, 50°, 60° or that is larger than 70°, but that is further preferably smaller than 80°, 75°, 65°, 55°, 45°, 35°, 25° or smaller than 15°.
Alternatively, the travel path of the measuring roller could also be arc-shaped. In this context, it would also be possible for the travel path of the measuring roller to comprise several arcuate segments that are connected directly to one another or the use of linearly extending sections.
Particularly preferably, the first adjustment device is configured to position the measuring roller between a first position and a second position in order to adjust the degree of wrapping. In the first position, the measuring roller is only vertically spaced (above or below) from the contact roller. As a result, the film web runs between the measuring roller and the contact roller almost exclusively with a vertical component. As a result, a degree of wrapping of approximately 0° can be set at the contact roller. Furthermore, in the second position, the measuring roller is only spaced from the contact roller in the horizontal direction (in the film take-off direction between the film entry area and the contact roller). As such, the film web runs between the measuring roller and the contact roller almost exclusively with a horizontal component. As a result, a degree of wrapping of 90° can be set on the contact roller. A position of the measuring roller between the above described first and the second positions result in a degree of wrapping between 0° and 90°.
In a preferred embodiment, a control device is also provided. The control device is configured to control the first adjustment device in such a way that the first adjustment device moves the measuring roller in such a way that a predetermined setpoint for the degree of wrapping is achieved. This setpoint can be loaded by the control device from a data memory, for example, or received by the control device from an input unit (keyboard, for example). It would also be possible for the control device to calculate the setpoint. In this context, the control device could be configured to load at least one material property of the film web, such as the film type, material thickness, material strength, material elongation, shrinkage and/or film temperature from a data memory and/or to receive it from an input unit (keyboard, for example).
The control device could then calculate the setpoint for the degree of wrapping from this at least one material property. In addition or alternatively, the control device could be configured to load at least one line parameter of the film stretching unit, such as the line speed and/or the film tension, from a data memory. In addition or alternatively, the control device could be configured to receive the at least one line parameter from an input unit. Depending on this at least one line parameter, the control device could be configured to calculate the setpoint for the degree of wrapping. Depending on the setpoint, the measuring roller can then be moved accordingly. Certain positions of the measuring roller can be stored in a lookup table together with certain wrapping degrees. A corresponding formula could also be stored (for example an equation) so that the control device is configured to calculate the corresponding position of the measuring roller depending on the setpoint by using that formula.
Preferably, a force measuring device is also provided and arranged on the measuring roller. The force measuring device is then configured to measure an actual value for film tension and to transmit it to the control device. The control device is again configured to compare the actual value for the film tension with a setpoint (target value) for the film tension. Depending on this comparison, the control device is configured to increase, reduce or maintain the degree of wrapping. This prevents thin films from tearing, for example.
In a preferred embodiment, a deflection roller and a second adjustment device are also provided. The deflection roller is arranged between the film entry area and the measuring roller. The second adjustment device is configured to move the deflection roller in the vertical direction in such a way that the film web can be aligned approximately horizontally (less than 5° deviation) between the deflection roller and the measuring roller or between the deflection roller and the contact roller. By the use of the deflection roller, in particular identical conditions at the measuring roller are achieved, so that a force measuring device used there provides measurement results that can be compared with each other even with different degrees of wrapping.
To further increase the stabilization of the film web, a first and/or a second stabilizing roller are preferably also provided and can be arranged at a first edge region of the film web. The first stabilizing roller can be brought into contact with an upper side of the film web and the second stabilizing roller with an underside of the film web. The first and second stabilizing rollers are preferably only spaced apart from each other in the vertical direction and are thus arranged directly above each other so that they support each other. Furthermore, a third and/or a fourth stabilizing roller are provided, which are arranged in the same way as the first and second stabilizing rollers. However, the third and fourth stabilizing rollers can be arranged at a second edge region opposite the first edge region. The first edge region could be a right edge region of the film web and the second edge region could be a left edge region of the film web. An “edge region” is to be understood as the region of the film web which is spaced from the respective side edge preferably by less than 50 cm, 40 cm, 30 cm, 20 cm or by less than 10 cm. Instead of a stabilizing roller, it is also possible to speak of a spreader.
Preferably, a third adjustment device is also provided, wherein the contact roller is attached to the third adjustment device. The third adjustment device is configured to move the contact roller in the direction of the film entry area. This ensures that the distance between the contact roller and the increasingly thick film bale is constant and that the contact roller always bears against the film bale with a defined contact pressure. The third adjustment device preferably moves the contact roller by a movement vector that preferably has only one component in the X-direction. Preferably, the measuring roller is moved with the same movement vector as the contact roller when the contact roller is moved. This ensures that the degree of wrapping can also be kept constant during operation if required.
In a further embodiment, the film winding system also comprises at least one discharge device. The discharge device is arranged in the area of the film web and is configured to discharge an electrical charge on the film web or film bale. Such an electrical charge can otherwise be life-threatening for the operating personnel. The discharge device preferably comprises a plurality of flexible/free-moving electrically conductive metal strips (a type of tinsel strip) which can be brought into contact with the film web. These metal strips are preferably arranged over the entire width of the film web or over the predominant width of the film web. In principle, a discharge conductor (rod-like for example) could also be used. This or these discharge conductors would preferably be arranged at a distance from the film web. The distance should preferably be smaller than 30 mm, 20 mm, 10 mm or smaller than 5 mm. Preferably, however, the distance is larger than 4 mm or 5 mm. An alternating electric field is applied to this discharge conductor. This alternating electric field is a high voltage, whereby the static charge is discharged.
The assembly of the film winding system and a film stretching unit according to the invention allows the film winding system to be connected to an exit area of the film stretching unit. The film stretching unit comprises an input section at which a film or plastic meld can be fed to it. Furthermore, the film stretching unit comprises various zones in which the plastic film or the plastic meld is heated and stretched into a mono- or bi-axially oriented film web (for example, via a longitudinal stretching stage and/or via a transverse stretching stage and/or oven). The resulting film web is then fed to the film winding system.
Various embodiments of the invention are described below by way of example with reference to the drawings. The same subject-matters have the same reference signs. The corresponding figures of the drawings show in detail:
The film stretching unit 110 comprises an entry area 111, wherein a film to be stretched can be fed to the film stretching unit 110 at its entry area 111. At the end of the film stretching unit 110, i.e. at its exit area 112, the stretched film web 2 exits. The exit area 112 of the film stretching unit 110 is connected to a film entry area 3 of the film winding system 1 according to the invention.
In the following
As explained before, different types of film should be wound up differently, because only then can it be ensured that winding is carried out without folds and that sufficient air is introduced between the individual layers so that the film web 2 can be unwound without difficulty in subsequent process steps. The method of winding according to the invention also ensures that the film web 2 does not tear.
In
In
With regard to
With regard to
The diameters of the contact roller 6 and the measuring roller 8 are different. They could also be the same. In order to achieve a degree of wrapping of 0°, the film web 2 between the measuring roller 8 and the contact roller 6 preferably runs exclusively with a component in the vertical direction (perpendicular to the ground). The measuring roller 8 is in a first position in
The contact roller 6 and the measuring roller 8 rotate in the same direction. The contact roller 6 and the base body 4a, 7a of the respective winding station 4, 7 in the winding position rotate in different directions.
In principle, both the contact roller 6 and the measuring roller 8 could be tempered. Such a temperature control (cooling or heating) could be achieved by an appropriate fluid (air, liquid).
The distance between the measuring roller 8 and the contact roller 6 can be constant over the entire travel path of the measuring roller 8. Preferably, however, the distance changes. The distance can become smaller or larger over the entire travel path.
The first adjustment device 10 is configured to move the measuring roller 8 relative to the contact roller 6 even during winding of the film web 2. This allows the degree of wrapping to be changed during operation. The moving of the measuring roller 8 relative to the contact roller 6 is in particular stepless. It could also take place in discrete steps. The moving is carried out pneumatically, electrically, hydraulically and/or mechanically, for example.
The first adjustment device 10 is further configured to move the measuring roller 8 along the entire travel path or along the predominant part of the travel path with a first movement vector and/or with a second movement vector.
The first and/or second guide system 11, 12 can, for example, be a sled, rail and/or chain system. In
The first movement vector comprises only one component in the X-direction, wherein the X-direction is parallel to the ground in the direction of the film entry area 3. The component in the X-direction is larger than zero, whereas all other components are zero. The second movement vector comprises a component in the X-direction and a component in the Z-direction. The component in the Z-direction extends perpendicular away from the ground (upward) and is perpendicular to the component in the X-direction. A component in the Y-direction is zero. The component in the Y-direction would otherwise run parallel to the axis of rotation or longitudinal axis of the contact roller 6 or the measuring roller 8.
This makes it possible for the measuring roller 8 to be moved only horizontally in the X-direction (i.e. away from the first or second winding station 4, 7) via the first guide system 11. Via the second guide system 12, the measuring roller 8 can be moved slanted. The second movement vector preferably forms an angle of 45° with an XY-plane. In particular, however, the angle could also be larger than 10°, 20°, 30°, 40°, 50°, 60° or greater than 70°. Preferably, however, the angle is smaller than 80°, 75°, 65°, 55°, 45°, 35°, 25° or smaller than 15°.
In principle, the travel path of the measuring roller 8 could also be arc-shaped. This would apply in particular to the second guide system 12. In this context, the travel path of the measuring roller 8 could also comprise several arc-shaped segments that are connected directly to each other or by linear sections.
Optionally, a deflection roller 15 and a second adjustment device 16 are also provided. The second adjustment device 16 is preferably a sled, rail and/or chain system. The drive is again preferably pneumatic, electric, hydraulic and/or mechanical. The deflection roller 15 is arranged between the film entry area 3 and the measuring roller 8. The second adjustment device 16 is configured to move the deflection roller 15 in the vertical direction (Z-direction) in such a way that the film web 2 is aligned approximately horizontally (less than 5° deviation) between the deflection roller 15 and the measuring roller 8 or between the deflection roller 15 and the contact roller 6. The deflection roller 15 could also be temperature controlled (heated and/or cooled). If the measuring roller 8 is therefore moved at an angle via the second guide system 12, i.e. also with a component in the Z-direction (in the vertical direction), then the deflection roller 15 is also moved with a component in the Z-direction. The diameter of the deflection roller 15 can correspond to the diameter of the contact roller 6 or the diameter of the measuring roller 8 or deviate from these diameters.
In addition to adjusting the deflection roller 15 in the vertical direction, the deflection roller 15 could also be adjusted in the horizontal direction (X-direction). The deflection roller 15 could therefore be moved with a movement vector that comprises both a component in the X-direction and a component in the Y-direction. In the simplest case, the deflection roller 15 would be moved along a straight line, i.e. at an angle. However, it would also be possible for the travel path of the deflection roller 15 to be arc-shaped. In principle, the travel path of the deflection roller 15 could also comprise several arcuate segments that are connected directly to each other or by at least one linear section.
In principle, it would also be possible for the travel path of the deflection roller 15 to correspond to the travel path of the measuring roller 8. Preferably, both the deflection roller 15 and the measuring roller 8 would complete the same movement sequence at the same time.
Optionally, first and second stabilizing rollers 20, 21 are also provided and arranged at a first edge region of the film web. The first stabilizing roller 20 can be brought into contact with an upper side of the film web 2. The second stabilizing roller 21, on the other hand, can be brought into contact with an underside of the film web 2. The first and second stabilizing rollers 20, 21 are spaced apart from one another only in the vertical direction and are arranged directly above one another. For the second edge region of the film web, which is opposite the first edge region, there are preferably also a third and a fourth stabilizing roller (not shown). The third and fourth stabilizing rollers are preferably only offset in the Y-direction from the first and second stabilizing rollers 20, 21, respectively. The stabilizing rollers 20, 21 are preferably arranged between the deflection roller 15 and the measuring roller 8. The stabilizing rollers 20, 21 are preferably arranged closer to the measuring roller 8 or to the contact roller 6 than to the deflection roller 15.
Preferably, a third adjustment device 25 is also provided. The third adjustment device 25 is preferably again a sled, rail and/or chain system. The drive of the third adjustment device 25 can also again be pneumatic, electric, hydraulic and/or mechanical. The contact roller 6 is attached to the third adjustment device 25. The third adjustment device 25 is configured to move the contact roller 6 in the X-direction. This ensures that the distance between the contact roller 6 and the increasingly thick film bale 5 remains constant. Alternatively, the respective first or second winding station 4, 5, which is currently in the winding position, could also be moved in the X-direction via an adjustment device so that the distance from the outermost position of the film bale 5 towards the contact roller 6 remains constant.
Furthermore, a control device 30 is provided. For reasons of clarity, the control device 30 is only shown in
The setpoint can be loaded from a data memory (not shown) or received in writing or from an input unit (e.g., computer, tablet computer, external control unit, and/or mobile device). In principle, the control device 30 would also be able to determine the setpoint based on at least one material property of the film web. These material properties include, for example, film type, material thickness, material strength, material elongation, shrinkage, and/or film temperature. It would also be possible for the control device 30 to determine the setpoint from a line parameter of the film stretching unit 110. These line parameters include, for example, the line speed and the film tension. In order to be able to determine the film tension, a force measuring device (not shown) is preferably also provided, which is arranged on the measuring roller 8. The force measuring device 8 is configured to measure a current value (actual value) for the film tension and transmit it to the control device 30. Based on this actual value, the control device 30 can control the first adjustment device 10 in such a way that the degree of wrapping is increased, reduced or maintained. This prevents the film web 2 from tearing.
With reference to
The first and second stabilizing rollers 20, 21 are preferably adjustable in their position (in particular vertically) via the first adjustment device 10, as are the third and fourth stabilizing rollers. The stabilizing rollers 20, 21 are preferably coupled to the second guide system 12. If the measuring roller 8 is adjusted (moved) with the second movement vector (X-direction and
Z-direction), then preferably the stabilizing rollers 20, 21 are also changed (moved) at least in their vertical position.
This is the second position of the measuring roller 8. In this case, the measuring roller 8 is only spaced apart from the contact roller 6 in the horizontal direction. By using the control device 30, the measuring roller 8 can preferably be moved as desired between the first position (
Comparing
The first, second and/or third adjustment device 10, 16, 25 preferably also comprise a braking and/or locking device which ensures that the respective adjustment device 10, 16, 25 remains permanently in position (even in the event of a power failure of the respective adjustment device 10, 16, 25) until the braking and/or locking device is released again.
In principle, it would also be possible for the film web 2 to run completely above the contact roller 6. In this case, the measuring roller 8 and the deflection roller 15 would be arranged in mirror image.
In principle, it is also possible for the diameter of the contact roller 6 to be variable. This means that a bend-adjustable contact roller can be used. Instead of a bend-adjustable contact roller 6, a crowned contact roller 6 can also be used. Such a crowned contact roller 6 is known, for example, from DE 10 2009 048 074 A1, wherein the content regarding the crowned contact roller 6 is hereby incorporated by reference. This results in a more uniform film bale 5, even if the thickness distribution of the film web 2 is different or if very smooth surfaces are produced (for example with optical films), which tend to telescope.
The contact roller 6, the measuring roller 8 and the deflection roller 15 preferably extend over the entire width of the film web 2 (and possibly beyond). The stabilizing rollers 20, 21 extend only over (a part of) the respective edge region of the film web 2.
Furthermore, there may be additional control units which are arranged between the deflection roller 15 and the measuring roller 8 and/or between the measuring roller 8 and the contact roller 6 and/or between the contact roller 6 and the corresponding winding station 4, 7 in the winding position and detect further film properties (for example film thickness, film temperature, crack formation) and transmit these film properties to the control device 30 so that the control device 30 adjusts the degree of wrapping on the basis of the further film properties. These additional control units may be, for example, optical cameras and/or IR sensors.
In principle, it would also be possible for the measuring roller 8 and/or the deflection roller 15 and/or the contact roller 6 to be driven by a common drive device. Synchronization could, for example, take place via corresponding gear wheels and/or chains and/or belts. However, it is also possible that the measuring roller 8 and/or the deflection roller 15 and/or the contact roller 6 are each driven via their own drive device.
In the following, some features are emphasized separately.
It is very beneficial if the first adjustment device 10 is configured to move the measuring roller 8 relative to the contact roller 6 continuously or in discrete steps.
It is also very beneficial if the ratio between the component in the X-direction and the component in the Z-direction of the second movement vector is constant over most of the travel path or over the entire travel path.
It is also very beneficial if the at least one discharge device 40, 41, 42 comprises:
The invention is not limited to the embodiments described. Within the scope of the invention, all described and/or drawn features can be combined with each other as desired.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 115 007.5 | Jun 2020 | DE | national |
