Patent Application
20250091832
The invention relates to a film store for a strip-like continuous film and to a method for dynamically storing the same.
A generic film store is known from EP 2 923 981 B1. Such film stores serve for continuously providing a continuous film in that film webs wound onto, for example, two supply rolls are automatically alternately joined together and are thus fed continuously to a treatment machine for labeling or packaging containers. The task of the film store is to compensate for changes in the film transport both on the input side when the film webs are joined together and on the output side depending on the film consumption in the treatment machine.
In the generic film store, the continuous film is guided in a meandering manner between deflection rollers which are fastened to an upper roller carrier and a lower roller carrier. The latter are coupled to one another in a mutually weight-compensating manner by a cable pull so that the continuous film is tensioned by a weight difference between the upper and lower roller carriers. During the size adjustment of the film store in working operation, the upper and lower roller carriers then move in opposite vertical directions toward one another and away from one another.
The strip transport of the continuous film through the film store takes place by means of conveyor units which are arranged upstream and downstream of the deflection rollers. Such conveyor units are preferably based on servomotors, as is known, for example, from EP 0 989 084 A2. It is also proposed therein that the force for moving the roller holders in opposite directions is not applied by a weight difference but by means of a pneumatic drive.
The disadvantage in this case is that the film tension at the individual runs of the transport path formed between the deflection rollers cannot be controlled with the desired accuracy and flexibility by means of weights or pneumatics since the maximum permissible film tension can vary considerably in a format-specific manner depending on the material, thickness and width of the continuous film, and the actual film tension in the individual phases of increasing and decreasing the film store can also vary considerably. This generally makes it more difficult to adjust the film store to a particular machine performance and transport dynamics downstream thereof.
In particular with a high machine performance and comparatively short start-up/stop time, such film stores usually cannot respond quickly enough. The interaction of the conveyor units with the comparatively inert tensioning mechanism of the film store then leads to strongly fluctuating forces and longitudinal tensions in the continuous film. For example, excessively small or excessively large strip tension in the continuous film can trigger downstream problems, such as an undesired slippage of the continuous film, an incorrect control of the film transport, an undesired film expansion, a film tear, or the like.
The actual strip tension of the continuous film also varies with the force to be applied by the tensioning mechanism to overcome the friction and inertia of the components moved during the size adjustment. For example, when the output-side conveyor unit of the film store is being emptied, it accelerates relative to the input-side conveyor unit. Consequently, the roller carriers of the film store are to be moved toward one another and to be accelerated for this purpose. This temporarily causes additional strip tension in the continuous film. The dynamics of the size adjustment are thus limited by the permissible strip tension of the continuous film.
It is also limiting in this case that the forces/strip tensions occurring in individual runs of the film store can be very different. As is known, the latter are separated from one another by the deflection rollers attached to the carriages. In order for a run to be able to pass the strip tension to the respectively adjacent run and to thereby produce a force equilibrium, the deflection roller therebetween must be moved. This is counteracted in a limiting manner by the friction and inertia of the deflection rollers. The strip tension in the individual runs then differs the more, the farther they are from one another. For example, when the film store is emptied, the strip tension in the output region thereof increases in comparison to the input region. As a result, with increasing storage size, the storage dynamics of the film store are limited to an undesired extent.
There is therefore a need for a film store and a method for dynamically storing a strip-like label film, with which film store and method at least one of the described problems can be eliminated or at least reduced.
The object posed is achieved with a film store and a method according to this disclosure.
The film store is designed to store a strip-like continuous film which, for example, serves for labeling or packaging containers. For this purpose, the film store comprises at least one storage region with an upper carriage and a lower carriage as well as deflection rollers, which are fastened to the carriages in such a way that the deflection rollers guide the continuous film along a transport path extending in each case in a meandering manner between the upper carriage and the lower carriage. The upper and lower carriages are mutually weight-compensating and are coupled to one another, for example by means of a cable pull deflected above the upper carriage, so as to move in opposite vertical directions in order to adjust the size of the film store.
According to the invention, the respective storage region comprises a torque-controlled or force-controlled servo motor for moving the upper and lower carriages in opposite direction and/or for tensioning the continuous film between the deflection rollers.
The torque control or force control of the servo motor enables a limitation of the strip tension occurring on the continuous film during the size adjustment, i.e., during the emptying or filling of the film store, for example by maintaining a maximum permissible force or a maximum permissible torque of the servo motor.
Damage to the continuous film can thereby be reliably prevented. At the same time, the storage dynamics of the storage region and/or the machine performance of the film store can be adjusted overall and in particular maximized.
Preferably, the servo motor is designed as a direct drive for a toothed belt which is fixedly connected to the carriages in terms of drive technology, or as a direct drive for at least one of the carriages, in particular in the form of a rotation servomotor for driving the toothed belt or in the form of at least one linear servomotor rigidly coupled to one of the carriages.
For example, a toothed belt can be integrated into a cable pull for the weight-compensating suspension and movement of the carriages in opposite directions or can form such a cable pull and be driven directly by a rotation servomotor. The rotor of a linear servomotor could, on the other hand, be rigidly coupled to one of the carriages, wherein the carriages can then also be suspended on a cable pull in a weight-compensating manner.
A rotation servomotor is particularly suitable for a torque control in the described sense; a linear servomotor is particularly suitable for a corresponding force control.
Preferably, the film store furthermore comprises an electronic control device which is programmed to calculate frictional resistances and/or moments of inertia of the carriages occurring during the movement of the carriages in opposite directions and to calculate therefrom a portion of a target torque/a target force of the servo motor associated with the size adjustment of the film store.
The control device can continuously update this portion of the target torque/the target force during the control of the servo motor and, for example, add it to a portion for generating the strip tension, and thus continuously adjust the target torque/the target force of the servo motor in such a way that a permissible strip tension in the continuous film is not exceeded.
It is also conceivable to continuously adjust the movement in opposite directions such that the portion of the target torque/the target force calculated for this purpose, i.e., for the size adjustment, does not exceed a maximum value specified specifically for the continuous film.
The dynamics of the movements in opposite directions for emptying and filling the film store can thereby be maximized without damaging the continuous film. Likewise, the size of the film store can consequently optimize the performance ability of the film store overall with regard to the possible storage dynamics and the machine performance.
Preferably, the electronic control device is programmed to calculate the target torque/the target force of the servo motor from the portion associated with the size adjustment and a portion associated with the strip tension of the continuous film. As a result, the torque of a rotation motor or the force of a linear motor can be maximized depending on the permissible strip tension of a particular continuous film in order to optimize the storage dynamics and the machine performance of the film store, optionally in a format-specific manner. The strip tension can also be optimized in each case with regard to transport problems to be avoided, such as undesired slippage, film expansion, or the like.
The above-described adjustment of the target torque allows relatively large changes in the target value of the torque and the strip tension per label/run. Although this is generally advantageous, such a fixedly specified target value, which is, for example, associated with a particular label type, can also be sufficient.
The film store preferably comprises an output-side storage region and a further storage region serially connected upstream thereof by means of at least one conveyor unit, wherein the conveyor unit is then designed to convey the continuous film while simultaneously decoupling the strip tension prevailing in the storage regions. This means that the continuous film is guided in the region of the conveyor unit during transport in such a way that substantially no strip tension is transmitted from one storage region to the other. As a result, the storage dynamics and storage size of the storage regions can be optimized independently of one another and/or adjusted to one another.
The output-side storage region is then preferably smaller than the storage region serially connected upstream. Relatively large storage dynamics, which can follow transport dynamics specified downstream of the film store, are thereby possible in the output-side storage region. In contrast, as a result of the decoupling of the strip tension, the storage capacity upstream of the output-side storage region can be optimized and in particular maximized by means of reduced storage dynamics in comparison to the output-side storage region.
Preferably, the storage region comprises an input-side conveyor unit for the continuous film, and the film store also comprises an electronic control device, by means of which the conveying speed of the input-side conveyor unit can be adjusted to an output-side conveying speed of the storage region. This enables a size adjustment of the film store as a function of storage dynamics/transport dynamics specified on the output side of the respective storage region.
The control device is then preferably programmed in such a way that the input-side conveying speed follows the associated output-side conveying speed with a reduced acceleration or deceleration with respect thereto and/or with a reduced jerk with respect thereto. As a result, the storage dynamics can be advantageously reduced with regard to the stress of the continuous film toward the input of the film store, which occurs in a jerky manner during load changes, for example.
Preferably, the film store furthermore comprises an output-side conveyor unit arranged downstream of the storage regions. The control device is then designed to adjust the conveying speeds of the input-side conveyor units overall to one another in a cascading manner, starting from the conveying speed of the output-side conveyor unit counter to the strip running direction. This is to be understood in that a control cascade is provided, which can adjust the input-side conveying speed of a particular storage region to the output-side conveying speed thereof or to the input-side conveying speed of the downstream adjoining storage region.
This enables a successive decrease in the storage dynamics counter to the strip running direction, whereby the storage capacity of individual storage regions can be successively increased counter to the strip running direction. As a result, film stores with optimized output-side storage dynamics and optimized input-side storage capacity can be combined, optionally in a modular manner, by serially connecting such storage regions and can be flexibly adjusted to specified transport dynamics and machine performances.
The film store according to at least one of the described embodiments is preferably a component of a device for providing a continuous film, with a device for automatically alternately feeding film from supply rolls connected in parallel. Continuous films, for example for packaging or for labeling containers, such as bottles, can thus be provided continuously and at comparatively high machine performance.
The method described serves to dynamically store a strip-like continuous film in a film store, which comprises at least one storage region with an upper carriage and a lower carriage as well as deflection rollers fastened thereto for the continuous film. Accordingly, the continuous film is guided along a transport path extending in each case in a meandering manner between the upper carriage and the lower carriage, and the size of the film store changes in store operation by the upper carriage and the lower carriage moving in opposite directions while mutually compensating for weight.
According to the invention, for this purpose, the upper and lower carriages are moved toward one another or away from one another by a torque-controlled or force-controlled servo motor. Additionally or alternatively, the continuous film between the deflection rollers is tensioned by the servo motor.
Preferably, the control of the servo motor proceeds as follows: frictional resistances and/or moments of inertia of the carriages occurring during the movement of the carriages in opposite directions are calculated automatically; based thereon, a portion of a target torque or of a target force of the servo motor associated with the size adjustment of the storage region is calculated automatically; and the servo motor is controlled based thereon. In particular, for this purpose, the portion associated with the size adjustment is, for example, added to a portion of the target torque/the target force associated with the strip tension of the continuous film.
Alternatively, a fixed specification of the target torque or of the target force, which depends, for example, on the label strip type, is also conceivable.
Preferably, the conveying speeds of conveyor units for the continuous film, which delimit the respective storage region, are adjusted to one another starting from an output-side conveying speed of the film store by means of a control cascade running counter to the strip running direction. The control cascade is to be understood to mean that the control of the conveyor units is organized in a cascade-like or step-like manner in such a way that machine parameters of a particular conveyor unit are in each case adjusted to the machine parameters of at least one conveyor unit arranged downstream thereof, in particular to the conveyor unit respectively directly following downstream. This principle preferably continues in a cascade-like/step-like manner counter to the strip running direction.
As a result, the transport dynamics/storage dynamics specified on the output side can be successively reduced in a step-like/cascade-like manner counter to the strip running direction, and the storage capacity of the film store can thus be maximized overall while maintaining a maximum permissible strip tension in the continuous film.
Preferably, a maximum strip tension in the continuous film is limited as a result of the torque control or force control of the servo motor, in particular as a result of the specification of format-specific maximum values and/or minimum values. The maximum values can, for example, be maximum torques or forces of the servo motor or maximum permissible strip tensions, or the like, forces occurring in the continuous film. The same applies to the minimum values. As a result, the operation of the film store with regard to permissible storage dynamics and storage capacity can be optimized, optionally also in a format-specific manner, i.e., for different types of continuous films.
The output-side conveying speed of the film store preferably follows a speed profile of the continuous film specified downstream thereof. Furthermore, storage dynamics caused thereby in the output-side storage region of the film store are reduced by means of a control cascade in at least one upstream-arranged storage region of the film store so that more continuous film can be stored there while maintaining a maximum permissible strip tension than in the output-side storage region. This also serves to optimize the storage dynamics and the storage capacity of the film store overall.
A preferred embodiment of the invention is illustrated in the drawing. In the figures:
As can be seen in
The carriages 6 to 9 are shown in
The deflection rollers 3 accordingly define a first transport path 10 of the first storage region 4 extending between the first upper carriage 6 and the first lower carriage 8 in a meandering (loop-like) manner, the deflection rollers 3 of the second upper carriage 7 and of the second lower carriage 9 accordingly define a second transport path 11 of the output-side storage region 5 that is independent thereof.
The storage regions 4, 5 can also be understood as storage levels of the film store 1. More than two storage regions/storage levels can also be connected one behind the other in the described manner in the film store 1 (not shown).
The size of the input-side storage region 4 is defined by the distance between the deflection rollers 3 of the first upper carriage 6 and of the first lower carriage 8. Accordingly, the size of the output-side storage region 5 is defined by the distance between the deflection rollers 3 of the second upper carriage 7 and of the second lower carriage 9. The capacity of the storage regions 4, 5 results in each case at maximum distance (not shown).
As can also be seen in
Accordingly, the output-side storage region 5 comprises a second servo motor 13, by means of which the upper and lower carriages 7, 9 of the output-side storage region 5 can be moved accordingly and the continuous film 2 stored therein can be tensioned.
The input-side storage region 4 comprises an input-side conveyor unit 14 with respect thereto for feeding the continuous film 2 into the first storage region 4. Furthermore, the second storage region 5 comprises an input-side conveyor unit 15 with respect thereto, which pulls the continuous film 2 out of the first storage region 4 and feeds it to the second storage region 5.
The film store 1 furthermore comprises an output-side conveyor unit 16, which pulls the continuous film 2 out of the output-side storage region 5 and provides it for further processing downstream of the film store 1, for example in a packaging machine or labeling machine (not shown).
An electronic control device 17 for controlling the servo motors 12, 13 and for controlling the conveyor units 14 to 16 is also indicated schematically.
As can also be seen in
Each cable pull 18, 19 is separately driven directly by one of the servo motors 12, 13. For this purpose, the cable pulls 18, 19 in each case comprise a toothed belt 18b, 19b which is fastened to the upper and lower carriages 6 to 9 and is directly driven by the associated servo motor 12, 13 by means of a gear wheel. In principle, chains, support cables, belts, or the like (not shown) could also be present, instead of or in combination with toothed belts 18b, 19b, for direct torque transmission from the servo motors 12, 13 to the cable pulls 18, 19.
The direct drive of the cable pulls 18, 19 on the toothed belts 18b, 19b by the servo motors 12, 13 minimizes drive play and thus enables a particularly precise control. For this purpose, the servo motors 12, 13 are preferably designed as torque-controlled rotation servomotors.
However, it would in principle also be possible to design at least one functionally corresponding servo motor 20 as a force-controlled linear servomotor, the rotor 20a of which is coupled directly to one of the carriages 6 to 9 in terms of drive technology. Carriages 6 to 9 moved in this way could then likewise be suspended pairwise on a respective cable pull 18, 19 in a weight-compensating manner. This is only schematically indicated in
The servo motor control is described below with reference to the embodiment shown with rotation servomotors in the sense of a torque control. If, instead, at least one linear servomotor is used, this servo motor 20 would be force-controlled in a corresponding manner. This means that, instead of torques, it would be corresponding forces.
The electronic control device 17 is preferably programmed in such a way that a target torque MS1, MS2 for the servo motors 12, 13 can be specified in each case, which target torque is in each case composed of a first portion for size adjustment of the film store 1, i.e., for moving the carriages 6 to 9 pairwise toward one another or away from one another, and a second portion for tensioning the continuous film 2 between the deflection rollers 3 of the carriages 6 to 9 associated with one another.
In order to determine the first torque portion of the storage region 4, 5, value tables and/or algorithms are preferably stored in the electronic control device 17 and make it possible to calculate a frictional resistance and/or a moment of inertia of the carriages 6 to 9 for the movement in opposite directions carried out in each case. On this basis, the control device 17 then continuously calculates a portion of the target torque MS1, MS2 currently required for size adjustment.
Furthermore, values for the second portion of the target torque MS1, MS2 can be stored in the control device 17, which values are required or maximally permissible for a specified strip tension of the continuous film 2 in the respective storage region 4, 5.
For example, individual values for the strip tension can be stored in the sense of a target value and/or a maximum permissible value and/or a minimum permissible value in a format-specific manner for different types of the continuous film 2.
Depending on the type of continuous film 2 to be processed, the electronic control device 17 can optionally fixedly specify the second torque portion for tensioning the continuous film 2 and dynamically add it in each case to the first torque portion currently required for size adjustment. Target torques MS1, MS2 for the servo motors 12, 13 that are format-specific and adjusted to the required storage dynamics of the storage regions 4, 5, can thus be continuously updated and specified for the control thereof.
In other words, on the one hand, the dynamics of size adjustments can be maximized depending on the type of the continuous film 2 used, and damage to the continuous film 2 can thereby be avoided. On the other hand, the storage capacity of the storage regions 4, 5 can be optimized to match the storage dynamics to be managed therein and depending on the load-bearing capacity of the continuous film 2.
The control device 17 is configured/programmed such that the servo motors 12, 13 can be controlled independently of one another in each case in a manner matching the size changes of the storage regions 4, 5.
For this purpose, the storage regions 4, 5 are decoupled from one another with regard to the strip tension of the continuous film 2 by means of the conveyor units arranged therebetween in each case, in the example by means of the input-side conveyor unit 15 of the output-side storage region 5.
This means that the continuous film 2 is conveyed by the input-side conveyor unit 15 of the output-side storage region 5 such that strip tensions across the conveyor unit 15 cannot add up. This can be effected there, for example, by a film guide between conveyor rollers and counterpressure rollers. In particular, it can thus be avoided that strip tension is transmitted to the output-side storage region 5, which must manage comparatively large storage dynamics without damaging the continuous film 2.
In the example shown, the conveyor unit 15 functions both as an input-side conveyor unit for the output-side storage region 5 and as an output-side conveyor unit for the input-side storage region 4. In principle, separate input-side and output-side conveyor units could instead be connected directly one behind the other in order to achieve corresponding tension decoupling between the storage regions 4, 5 of the film store 1.
The mode of operation of the film store 1 is generally such that the storage dynamics overall thereof are specified on the output side by a treatment unit supplied downstream with the continuous film 2, wherein the output-side conveyor unit 16 then directly follows the transport dynamics, thus specified downstream, in the sense of output-side storage dynamics.
Accordingly, the control device 17 is designed as a counterflow control cascade which starts from the conveying speed V3 of the output-side conveyor unit 16 and adjusts the conveying speeds V1, V2 of the upstream-connected conveyor units 14, 15 thereto.
This means that the conveying speed V2 of the conveyor unit 15 at the input of the output-side storage region 5 is first adjusted to the output-side conveying speed V3 of the second storage region 5 depending on the size adjustment of said second storage region to be carried out. The conveying speed V1 of the input-side conveyor unit 14 of the input-side storage region 4 is then in turn adjusted to the conveying speed V2 prevailing there on the output side, i.e., to the conveyor unit 15 connected directly downstream thereof.
The described cascading counter to the flow direction/strip running direction causes the transport and storage dynamics to be managed to decrease from the output-side storage region 5 to the input-side storage region 4 and thus counter to the strip running direction of the continuous film 2. In principle, this also applies to further storage regions/storage levels (not shown) optionally arranged therebetween, so that a step-like successive reduction of the storage dynamics toward the input of the film store 1 is possible. The capacity of individual storage regions 4, 5 can then increase successively counter to the strip running direction, wherein a maximum or minimum permissible strip tension in the continuous film 2 can in each case be maintained.
By a targeted control-related cascading of storage regions 4, 5 counter to the strip running direction, an optimization of the storage capacity and of the machine performance, which is adjusted to the transport dynamics/storage dynamics specified downstream of the film store 1, can thus be configured depending on the maximum permissible strip tension in the continuous film 2. This means that the film store 1 can optionally be flexibly adjusted to different production conditions in the sense of a modular control cascade by a corresponding combination of storage regions 4, 5 serially connected one behind the other.
The control cascade is then preferably constructed such that the input-side conveying speeds V1, V2 of the storage regions 4, 5 follow the respectively associated output-side conveying speeds V2, V3 with reduced acceleration or deceleration with respect thereto and/or with a reduced jerk with respect thereto. This means that jerky loads/accelerations of the continuous film 2 are successively reduced counter to the strip running direction.
This also has the consequence that the storage regions 4, 5 can have increasingly greater storage capacity as seen counter to the strip running direction since dynamic loads of the continuous film 2 decrease with increasing distance from the output of the film store 1 and permissible strip tensions can thus be maintained in the individual storage regions 4, 5 even with a correspondingly greater capacity of the individual storage region 4, 5.
The film store 1 can thus overall be tailored by the described cascading of storage regions 4, 5/storage levels to particular properties of the continuous film 2 to be processed, and/or to the requirements of the treatment units (not shown) supplied by the film store 1.
s a result of the torque control/force control, the storage dynamics can also be maximized in each individual storage region 4, 5 within the scope of the mechanical load-bearing capacity of the continuous film 2 since load peaks can be reduced or largely avoided by the torque/force limitation effected in this way. This means that the continuous film 2 can be loaded relatively uniformly as a result of the torque control of the servo motors 12, 13 (as a result of the force control of the servo motor 20) even in the case of movements of the carriages 6 to 9 in opposite directions for emptying or filling the film store 1.
In other words, the individual movement sequences of the carriages 6 to 9 during emptying and filling of the film store 1 can be optimized overall with regard to speed and acceleration and thus storage dynamics. On this basis, the modular cascading also enables a targeted capacity adjustment of the film store 1 without restricting the storage dynamics and with great flexibility and efficiency in design and manufacture.
For the sake of completeness, vertical linear guides 21, 22 for the carriages 6 to 9 are shown in
The film store 1 is preferably part of a device (not shown) for continuously providing the continuous film 2. The latter is produced therein in a manner known in principle, in that film strips are automatically unwound alternately from supply rolls connected in parallel and are joined together by adhesive bonding or welding of their ends to form the continuous film 2, which is then fed directly subsequently to the downstream film store.
At the start of work of the film store 1, the carriages 6 to 9 are moved together in a manner known in principle, and as shown in
Subsequently, the upper and lower carriages 6 to 9 are moved pairwise to a suitable distance from one another and the conveyor units 14 to 16 are operated at a suitable speed in order to successively store the continuous film 2 in the film store 1 and to thus fill the latter.
In subsequent store operation, the size change of the film store 1 is based in the described manner on the production requirements downstream of the film store 1, wherein the storage dynamics, starting from the output-side conveyor unit 16, are reduced by a cascading of the control of individual storage regions 4, 5 counter to the strip running direction, and material-compatible film storage and a flexible modular design are thus made possible.
Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as falling within the scope of the claims.
The present disclosure should not be read as implying that any particular element, step, or function is an essential element, step, or function that must be included in the scope of the claims. Moreover, the claims are not intended to invoke 35 U.S.C. § 112(f) unless the exact words “means for” are followed by a participle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 112 777.7 | May 2021 | DE | national |
This application is a 371 National Stage of International Application No. PCT/EP2022/059149, filed Apr. 6, 2022, which claims priority to German Patent Application No. 102021112777.7, filed May 18, 2021, the disclosures of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/059149 | 4/6/2022 | WO |
