AT526506B1 - Film carriage for a winding device - Google Patents

Abstract

A film carriage (1) for a winding device is described. The film carriage comprises several deflection rollers (2, 3, 4, 5, 6), a drive roller (7) and a brake roller (8) arranged upstream of the latter in the film withdrawal direction (F), the drive roller (7) and brake roller (8) each having a separate drive (9, 10). According to the invention, it is proposed that an adjustable pressure roller (11, 12) is assigned to both the drive roller (7) and the brake roller (8), and that a pendulum roller (15) is provided downstream of the drive roller (7) in the film withdrawal direction (F), which is arranged at the free end of a lever arm (16) which is articulated on the film carriage (1) and can be actuated by means of at least one actuator (18), wherein the at least one actuator (18) and the respective drives (9, 10) of the drive roller (7) and the brake roller (8) are connected to a control device to adjust the film tension, forming a common control circuit for controlling the position of the pendulum roller (15).

Description

Description

[0001] The invention relates to a film carriage for a winding device, with several deflection rollers and with a drive roller and a brake roller arranged upstream of the latter in the film withdrawal direction, wherein the drive roller and the brake roller each have a separate drive.

[0002] There are various winding devices, for example ring winders or rotary arm winders, which unwind a plastic stretch film from a film roll via a film carriage, so that the film web that has been pulled off is fed to the packaged goods to be wrapped. Such film carriages usually have, in addition to several deflection rollers, a drive roller and a brake roller arranged upstream of these in the film withdrawal direction, each of which is driven separately.

[0003] For an optimal winding result, it is crucial that the film is pre-stretched in the film carriage, whereby this can usually be adjusted depending on the speed ratios of the drive roller and brake roller. On the other hand, care must be taken during the winding process to maintain the film tension as even as possible. However, since any packaged goods can vary in terms of shape, size and geometry, this inevitably leads to undesirable film tension peaks due to, for example, sharp corners of the respective packaged goods. In order to compensate for this, depth sensor systems (US20180257802A1) for detecting the contour of the packaged goods, or force measurement-based sensor systems (see US20210309401A1) have already been proposed. The disadvantage, however, is that control concepts based on such sensor systems for adjusting the film tension are severely limited with regard to the possible drive power of the winding device or the possible throughput rates, since the underlying control circuits would act too slowly at the higher winding speeds that are now common to effectively compensate for sudden film tension peaks.

[0004] In addition, in the packaging industry, against the background of sustainable developments, films based on bio-based polymers are to be used more frequently. However, in connection with the use in winding processes, these differ significantly from previous petroleum-based plastic films, not least in their surface properties and in the force-strain diagram. For example, the increased film slippage that occurs with such bio-based materials during film removal also means that the possible throughput rates are severely limited.

[0005] The invention is therefore based on the object of designing a film carriage of the type described at the outset in such a way that, despite the use of bio-based film material that is prone to film slippage, and in particular at higher winding speeds, a problem-free in-situ film tension adjustment is possible during the winding process, largely independent of the geometry of the packaged goods to be wrapped.

[0006] The invention solves the problem in that both the driver roller and the brake roller are assigned a pressure roller each, which can be adjusted to the driver roller or brake roller, and in that a pendulum roller is provided downstream of the driver roller in the film withdrawal direction, which is arranged at the free end of a lever arm which is articulated on the film carriage and can be actuated by means of at least one actuator, wherein the at least one actuator and the respective drives of the driver roller and the brake roller are connected to a control device to adjust the film tension, forming a common control circuit for position control of the pendulum roller.

[0007] The invention is based on the consideration that a reliable film tension adjustment is achieved by controlling the position of a pendulum roller. As a result of the features according to the invention, in contrast to a force measurement-based control, a quickly responding film tension adjustment is achieved during the winding process, in particular

at higher winding speeds. The pendulum roller is therefore subjected to a corresponding pre-tensioning force by the actuator, regardless of a winding speed specified by the winding device drive, e.g. the ring drive, whereby the position of the pendulum roller can be determined and the position of the pendulum roller can subsequently be influenced depending on the rotational speed of the driver roller. The adjustment to both the driver roller and the brake roller, each with the help of a separate pressure roller, means that the film web is pressed against the driver and brake rollers to achieve a higher coefficient of friction that improves the force transmission. This is a crucial prerequisite for the fact that, on the one hand, the force applied to the pendulum roller by a change in the film tension can be converted into a quickly responding control behavior, and, on the other hand, that the use of film material that is prone to film slippage, in particular bio-based film material, is also possible without any problems at higher winding speeds. Overall, the features according to the invention make it possible for the tension forces required for reliable film tension adjustment to be kept as constant as possible by means of a sensitive and quickly responding control system, regardless of the contour of the packaged goods, i.e. even in the case of any sharp corners, eccentricities and conicities.

[0008] In order to further improve the control behavior and consequently a reliable film tension adjustment even at higher winding speeds, it is recommended that the lever arm includes a counterweight at a free end opposite the pendulum roller with respect to the lifting alarm joint axis. In this way, the centrifugal and acceleration forces arising during the winding process, which would prevent reliable position control of the pendulum roller, can be largely compensated.

[0009] From a design perspective, it is recommended that the pressure rollers can each be moved against the force of a return element, in particular a return spring. Preferably, the respective axes of the drive roller, the brake roller and the two pressure rollers lie on a common imaginary connecting line running transversely to the respective axes, which is in particular parallel to the film pull-off direction. As a result, the line of action of the force of the two pressure rollers in relation to the drive roller or brake roller can advantageously coincide with that imaginary connecting line.

[0010] Particularly favorable conditions arise when, on the one hand, the pressure roller which is assigned to the drive roller can be adjusted thereto against the film withdrawal direction, and, on the other hand, the pressure roller which is assigned to the brake roller can be adjusted thereto in the film withdrawal direction.

[0011] Reliable operating conditions with a compact design can be achieved by mounting exactly one deflection roller between the driver roller and the brake roller, as well as between the driver roller and the pendulum roller, in relation to the film withdrawal direction. In particular, the fact that only one deflection roller is mounted between the driver roller and the brake roller enables both the driver roller and the brake roller to wrap around the same roller side due to the associated film path, which has a beneficial effect on the pre-stretching of the film. Overall, the measures according to the invention thus create the prerequisite for reducing the size of the film carriage in such a way that the interference ring resulting from the circumferential winding movement, i.e. the ring that depicts the course of the winding circumferential movement of the film carriage, has a smaller ring width than known film carriages. Consequently, in comparison with the winding devices equipped with known film carriages, packaged goods with a comparatively larger cross-section can be wrapped with the same footprint. The film carriage according to the invention can basically be used equally without restrictions on a wide variety of winding device concepts, e.g. ring winders or rotary arm winders.

[0012] In order to ensure a film web movement that is as clean as possible over a wide speed range with a robust design, both the drive roller, the

The brake roller and the pendulum roller are each supported on both sides. In contrast to one-sided roller bearings, this largely avoids any roller axis movements caused by transverse forces, which can lead to oscillations, particularly at higher roller speeds, and are therefore detrimental to a cleanly guided film web path. For an even more robust design, it is recommended that the pressure rollers and/or all deflection rollers are also supported on both sides. This allows high film tensile forces to be achieved.

[0013] In practice, changing the film is often challenging, especially since the newly inserted film web has to be adjusted exactly over the path specified by the film carriage. In order to enable the easiest possible roll change, it is proposed that the film carriage has two carriage halves that can be detachably connected to one another, with the driver roller and the brake roller being assigned to the first carriage half and the pressure rollers to the second carriage half, and with respect to the carriage width, one side of the carriage for inserting a film web section is open over its long side. As a result of these measures, when changing the film, the film web section to be inserted no longer has to be threaded through from the beginning to the end of the film carriage in accordance with the specified roller and roll arrangement, so that the cord formation of the film web section that is usually required for this can also be omitted. Apart from the improved handling when changing the film, this also results in a reduction in lost film material as a result of cord formation. The detachable connection of the two carriage halves can, for example, be carried out manually or automatically, in particular via a manual or automated locking bolt device.

[0014] In this context, particularly favorable conditions arise when changing the film if the two carriage halves can be displaced relative to one another, preferably in a direction of displacement running essentially transversely to the direction of film removal, between a closed position and an open position. In combination with the feature that the drive roller and the brake roller are assigned to the first carriage half and the pressure rollers are assigned to the second carriage half, when changing the film, after the corresponding film section has been inserted laterally into the film carriage in the open position, the optimal film web path is inevitably achieved by the displacement into the closed position. Due to the rollers and deflection rollers that rest against the inserted film web section in the closed position, the film web is also automatically pre-tensioned, so that after the film has been changed, no additional readjustments to the film web or the film carriage are generally required.

[0015] In order to be able to open and close the two-half film carriage reliably despite its compact design, it is recommended that a guide device that can be actuated by an actuator is arranged on the side of the carriage opposite the open side for the relative displacement of the two halves of the carriage between the closed position and the open position. The guide device can in particular comprise extendible guide rails that extend in a guide direction that runs transversely to the film withdrawal direction or in a guide direction that runs transversely to the respective axes of the rollers and deflection rollers.

[0016] In order to make automated film changes even easier, it is proposed that a bearing arm be attached to one side of the slide, at the free end of which a bearing pin for receiving a film roll is rotatably mounted. This creates the prerequisite that, during an automated film change, the new film roll provided on a corresponding change slide can be easily picked up by the bearing pin, while a film web section that has already been pulled off the new film roll on a corresponding change slide is provided in such a way that it can be easily inserted laterally into the film slide that is in the open position. In order to enable the bearing pin to be inserted easily into the film roll sleeve and subsequently to enable the film roll sleeve to be mounted in a rotationally fixed manner on the bearing pin, which is itself rotatably mounted on the bearing arm, radially extendable and retractable fastening elements can be provided on the bearing pin casing, which enable the formation or release of a frictional connection between

between the bearing pin and the inside of the film roll sleeve. The bearing pin itself can be braked in its rotational movement preferably by means of a friction brake. In a further variant, it can also be provided that the friction brake acts directly on the film roll sleeve.

[0017] The invention also relates to a method for in-situ film web tension adjustment when wrapping packaged goods with a device according to the invention. In this case, a speed target value for the driver roller is continuously determined depending on an actual rotation speed value and a detected position value of the setting position of the actuator for the pendulum roller, and the drive of the driver roller is adjusted according to the continuously determined speed target value. In this case, according to the underlying control circuit, a position sensor, preferably located on the actuator, supplies an analog output signal which is transmitted directly to the converter of the driver roller. The pendulum roller is thus always held in a neutral position that is as central as possible depending on the rotation speed of the driver roller. Conversely, the tensile force applied by the film web acts against the counterforce applied by the actuator. The film web tension during the wrapping process, i.e. during the packaging of the packaged goods with the film, is therefore only based on the specified force for applying pressure to the actuator. In the simplest case, the actuator can comprise a pneumatic cylinder. Preferably, two actuators are provided, each comprising a pneumatic cylinder.

[0018] The subject matter of the invention is shown by way of example in the drawing.

[0019] Fig. 1 is a schematic sectional view of a film carriage according to the invention in an open position,

[0020] Fig. 2 is a representation of the film carriage corresponding to Fig. 1 in a closed position and

[0021] Fig. 3 is a plan view of a film carriage according to the invention with the film web not removed.

[0022] A film carriage 1 according to the invention for a winding device comprises, in addition to various deflection rollers 2, 3, 4, 5, 6, a drive roller 7 and a brake roller 8 arranged upstream of the latter in the film withdrawal direction F. The drive roller 7 and the brake roller 8 are each connected to separate drive devices 9 and 10 via belts.

[0023] Both the drive roller 7 and the brake roller 8 are each assigned a pressure roller 11, 12. The pressure roller 11 can be adjusted against the drive roller 7 against the film removal direction F against the force of a return spring 13, whereas the pressure roller 12 can be adjusted against the brake roller 8 in the film removal direction F against the force of a return spring 14.

[0024] A pendulum roller 15 is arranged downstream of the driver roller 7 in the film withdrawal direction F. In this case, with respect to the film withdrawal direction F, exactly one deflection roller 2 is arranged between the driver roller 7 and the brake roller 8, and exactly one deflection roller 3 is arranged between the driver roller 7 and the pendulum roller 15. The pendulum roller 15 is arranged at the free end of a lever arm 16 which is articulated on the film carriage 1 and which is operatively connected to an actuator 18 with respect to a lifting alarm joint axis 17 on the arm section opposite the pendulum roller 15. In addition, the lever arm 16 has a schematically indicated counterweight 19 at its free end opposite the pendulum roller 15 with respect to the lifting alarm joint axis 17.

[0025] The actuator 18 comprises a pneumatic cylinder 20. Preferably, two actuators are provided, each comprising a pneumatic cylinder 20. Due to the sectional view selected in Fig. 1 and 2, however, only a single actuator 18 comprising a pneumatic cylinder 20 is shown.

[0026] To adjust the film tension, the pneumatic cylinder 20 of the actuator 18 and the drives 9, 10 are connected to a control device (not shown in detail) to form a common control circuit for controlling the position of the pendulum roller 15. It goes without saying that a control device in the sense of the invention has a control circuit for forming

The pendulum roller 15 is therefore subjected to a corresponding pre-tensioning force by the pneumatic cylinder 20 when a packaged item P, indicated in Fig. 2, is wrapped in a winding direction W as a function of a winding speed predetermined by a winding device drive, e.g. a ring drive, whereby the position of the pendulum roller 15 can be determined and, as a result, the position of the pendulum roller 15 can be influenced as a function of the speed of the driver roller 7. On the basis of the control loop according to the invention, a speed target value for the driver roller 7 can be continuously determined as a function of an actual rotation speed value and a detected position value of the setting position of the pneumatic cylinder 20, whereby the drive 9 of the driver roller 7 is set in accordance with this continuously determined speed target value.

[0027] The film carriage 1 has two carriage halves 21, 22 that can be detachably connected to one another. The drive roller 7, the brake roller 8 and the deflection rollers 3, 4, 5 are assigned to the first carriage half 21, whereas the pressure rollers 11, 12 and the deflection rollers 2, 6 are assigned to the second carriage half 22. The lever arm 16 is hinged to the second carriage half 22, so that the pendulum roller can also be assigned to the second carriage half 22.

[0028] For a simple film change, the two carriage halves 21, 22 can be displaced relative to one another between an open position according to Fig. 1 and a closed position according to Fig. 2 using a guide device 23 having guide rails in a displacement direction V running essentially transversely to the film removal direction F. The guide device 23 can be actuated by means of an actuator 25 comprising a further pneumatic cylinder 24. To detachably connect the two carriage halves 21, 22, a locking bolt device 26 is arranged on one carriage half 22, the locking bolt of which can engage in a corresponding locking eyelet 27 of the other carriage half 21.

[0029] As indicated in Fig. 3, with respect to the carriage width, a bearing arm 29 is attached to one side of the carriage 28, apart from the drives 9, 10 and the guide device 23, at the free end of which a bearing pin 30 is rotatably mounted for receiving a film roll 31. The opposite side of the carriage 32, on the other hand, is open so that when changing the film, a film web section 33 can be introduced into the film carriage 1 via its long side.

[0030] The driving roller 7, the braking roller 8, the pendulum roller 15, as well as the pressure rollers 11, 12 and the deflection rollers 2, 3, 4, 5, 6 are each mounted on both sides, as is also indicated in Fig. 3.

Claims (10)

Patent claims 1. Film carriage (1) for a winding device, with several deflection rollers (2, 3, 4, 5, 6) and with a driver roller (7) and a brake roller (8) arranged upstream of the latter in the film withdrawal direction (F), the driver roller (7) and the brake roller (8) each having a separate drive (9, 10), characterized in that both the driver roller (7) and the brake roller (8) are each assigned a pressure roller (11, 12), which can be adjusted to the driver roller (7) or brake roller (8), and that a pendulum roller (15) arranged downstream of the driver roller (7) in the film withdrawal direction (F) is provided, which is arranged at the free end of a lever arm (16) which is articulated on the film carriage (1) and can be actuated by means of at least one actuator (18), the at least one actuator (18) and the respective drives (9, 10) of the driver roller (7) being used to adjust the film tension. and the braking roller (8) are connected to a control device to form a common control circuit for controlling the position of the pendulum roller (15). 2. Film carriage (1) according to claim 1, characterized in that the lever arm (16) comprises a counterweight (19) at a free end opposite the pendulum roller (15) with respect to a lifting alarm joint axis (17). 3. Film carriage (1) according to claim 1 or 2, characterized in that on the one hand the pressure roller (11) which is assigned to the drive roller (7) can be adjusted thereon against the film withdrawal direction (F), and that on the other hand the pressure roller (12) which is assigned to the brake roller (8) can be adjusted thereon in the film withdrawal direction (F). 4. Film carriage (1) according to one of claims 1 to 3, characterized in that with respect to the film withdrawal direction (F) between the driver roller (7) and the brake roller (8) and/or between the driver roller (7) and the pendulum roller (15) exactly one deflection roller (2, 3) is mounted. 5. Film carriage (1) according to one of claims 1 to 4, characterized in that the drive roller (7), the brake roller (8) and the pendulum roller (15) are each mounted on both sides. 6. Film carriage (1) according to one of claims 1 to 5, characterized by two carriage halves (21, 22) which can be detachably connected to one another, the drive roller (7) and the brake roller (8) being assigned to the first carriage half (21), and the pressure rollers (11, 12) being assigned to the second carriage half (22), and with respect to the carriage width, one carriage side (32) being open over its long side for introducing a film web section (33). 7. Film carriage according to claim 6, characterized in that the two carriage halves (21, 22) are displaceable relative to one another between a closed position and an open position, preferably in a displacement direction (V) running substantially transversely to the film withdrawal direction (F). 8. Film carriage according to claim 7, characterized in that on the carriage side (28) opposite the open carriage side (32) there is arranged a guide device (23) which can be acted upon by means of an actuator (25) for the relative displacement of the two carriage halves (21, 22) between the closed position and the open position. 9. Film carriage according to one of claims 1 to 8, characterized in that a bearing arm (29) is attached to one side of the carriage (28), at the free end of which a bearing pin (30) for receiving a film roll (31) is rotatably mounted. 10. Method for in-situ film web tension adjustment when wrapping packaged goods with a device according to one of the preceding claims, characterized in that depending on an actual rotation speed value and a detected position value of the setting position of the actuator (18) for the pendulum roller (15), a speed target value for the driver roller (7) is continuously determined and the drive (9) of the driver roller (7) is adjusted according to the continuously determined speed target value. Here 3 sheets of drawings