This application claims priority of European patent application no. 22 154 626.0, filed Feb. 1, 2022, the entire content of which is incorporated herein by reference.
The disclosure relates to a film transportation plate and to a film transportation system having such a film transportation plate.
In a widely used embodiment, packaging units are frequently produced in that first of all films are thermoformed. A product is introduced into the resultant cavities, this being followed by sealing with a cover film. A double-layered film strip is produced, in which part-quantities of the product are delimited from one another. These part-quantities are finally separated in a cutting station.
In particular in the domestic sector, single doses of detergent or rinsing agent are packaged in the abovementioned manner via two webs of water-soluble film. For industrial mass production, packaging machines are used in continuous, non-cyclic operation, as are known for example from US 2021/0276754. In that case, a conveyor in the form of a chain runs continuously about a fixed machine frame, wherein the conveyor passes along a straight, horizontal path on the top processing side. Together with the conveyor, transportation plates with so-called format plates are continuously carried along in circulation. Synchronously with the movement of the format plates, a first film web is continuously fed and placed on the top side of the transportation plates and carried along with the latter from station to station. A plurality of mold impressions are formed in the format plates, the film web being thermoformed in the mold impressions following thermal plasticizing. The cavities that arise in the film web in this way remain supported by the mold impressions and are filled with the desired product in a subsequent filling station. In ongoing operation, a further film web is fed as a cover film and sealed, such that mutually separated single quantities of the product are produced in a cohesive sachet web. Finally, single packs are cut out of this sachet web.
A partial problem to be solved here is to fix the first film web to the transportation plates such it is retained reliably and yet can be deformed freely during thermoforming. To this end, retaining means for the film web are arranged on the two lateral edges of the transportation plates, the retaining means being used to clamp the peripheral regions of the film web to the transportation plates, while the central region of the film web rests loosely and can be thermoformed. The lateral clamping ensures uniform plastic deformation of the film web during thermoforming, without the film edges being pulled inward. As a rule, the clamping takes place via two round belts that circulate on both sides of the transportation plates and are pressed, together with the respective peripheral region of the film web, into lateral belt receptacles of the transportation plates. In order that the film web can be clamped securely, the cross section of the round belt has to be wrapped at least to an extent of 180° by the film web. To achieve this, of the available film width, a considerable proportion has to be reserved for the clamping, and this cannot be used for the actual process of thermoforming and packaging. The effective usable width of the film web is accordingly reduced, this being accompanied by associated waste generation and with associated costs.
Furthermore, in the case of the round belts that are used, certain operating faults cannot be ruled out. The belts tend to stretch, and this can result in them jumping out of the belt guide. The stretching also entails a reduction in the retaining force, this resulting in faults in particular during thermoforming. It is even possible for a belt to tear.
It is an object of the disclosure to provide a film transportation plate such that improved lateral clamping of the film web is possible.
This object is, for example, achieved by a film transportation plate for transporting a film web through a plurality of processing stations of a film packaging machine, wherein the film transportation plate includes: a plate body having a first lateral edge and a second lateral edge disposed opposite to the first lateral edge; the plate body defining at least one mold impression for thermoforming the film web between the first lateral edge and the second lateral edge; a first retainer for the film web arranged at the first lateral edge; a second retainer for the film web arranged at the second lateral edge; the first retainer being formed by a first fixed clamping surface and at least one first clamping jaw; the second retainer being formed by a second fixed clamping surface and at least one second clamping jaw; the at least one first clamping jaw being configured to be moveable relative to the first clamping surface for pressing the film web so as to clamp the film web against the first clamping surface; the at least one second clamping jaw being configured to be moveable relative to the second clamping surface for pressing the film web so as to clamp the film web against the second clamping surface; the first retainer including at least one first retaining magnet configured to attract the at least one first clamping jaw against the first clamping surface and a first actuating extension for lifting the first clamping jaw off the at least one first clamping surface; and, the second retainer including at least one second retaining magnet configured to attract the at least one second clamping jaw against the second clamping surface and a second actuating extension for lifting the at least one second clamping jaw off the second clamping surface.
It is a further object of the disclosure to provide a film transportation system which allows edge holding of the film web with improved operational reliability.
This object is, for example achieved by a film transportation system for transporting a film web through processing stations of a film packaging machine. The film transportation system includes: a plurality of film transportation plates configured to be moved in circulation; each of the film transportation plates having a first lateral edge and a second lateral edge disposed opposite to the first lateral edge; each of the film transportation plates defining at least one mold impression for thermoforming the film web between the first lateral edge and the second lateral edge; each of the film transportation plates having a first retainer for the film web arranged at the first lateral edge and a second retainer for the film web arranged at the second lateral edge; the first retainers each being formed by a first fixed clamping surface and at least one first clamping jaw; the second retainers each being formed by a second fixed clamping surface and at least one second clamping jaw; the at least one first clamping jaw of each of the film transportation plates being configured to be moveable relative to the first clamping surface for pressing the film web so as to clamp the film web against the second clamping surface; the at least one second clamping jaw each of the film transportation plates being configured to be moveable relative to the second clamping surface for pressing the film web so as to clamp the film web against the first clamping surface; each of the first retainers including at least one first retaining magnet configured to attract the at least one first clamping jaw against the first clamping surface and a first actuating extension for lifting the at least one first clamping jaw off the first clamping surface; each of the second retainers including at least one second retaining magnet configured to attract the at least one second clamping jaw against the second clamping surface and a second actuating extension for lifting the at least one second clamping jaw off the second clamping surface; and, a fixed actuator configured to act on the first and the second actuating extensions.
The disclosure provides that the retainers or retaining means on the two lateral edges of the film transportation plate are each formed by a fixed clamping surface and at least one movable clamping jaw for pressing the film web so as to clamp it against the clamping surface. In this case, the retaining means also each have at least one retaining magnet for attracting the clamping jaw against the clamping surface, and an actuating extension for lifting the clamping jaw off the clamping surface. The film transportation system, which is likewise according to the disclosure, additionally includes fixed actuating means, that is, ones that do not circulate with the film transportation plates, which act on the actuating extensions of the clamping jaws.
In conjunction with the magnetic retaining force, the clamping jaws allow reliable holding of the film web on an in particular planar clamping surface, without material-intensive wrapping of a belt cross section being necessary. For secure film fixing, only a very narrow clamping region is required, in which a likewise narrow peripheral strip of the film web is retained. Thus, a greater proportion of the width of the film web is available for forming packaging cavities. More freedoms are created in the geometric configuration and distribution of the cavities. The achievable increase in the output quantity results in a proportional reduction in the machine and operating costs with regard to the individual products. The reduced peripheral strips bring about less film waste. The mechanism of the clamping jaws is more reliable with the creation of fewer faults. Furthermore, the achievable retaining forces are greater with an increased uniformity of the force distribution compared with a round belt.
The clamping jaws can be opened and closed in a linear movement. In an embodiment, the clamping jaws are mounted so as to be pivotable about pivot axes, wherein the pivot axes are parallel to the lateral edges of the film transportation plate. This results, with a small overall volume, in a precise, play-free and simple movement mechanism, which applies clamping forces without fault and also releases them again as required.
It may be expedient to configure the actuating extension as a mandrel or the like and to guide it in a sliding manner. Preferably, the actuating roller is provided with a run-on roller. As a result, as a result of a rolling movement, high actuating forces can be introduced with little wear into the moved clamping jaws.
In an embodiment of the disclosure, a plurality of and in particular four clamping jaws are arranged on each lateral edge of an individual film transportation plate. The clamping jaws that are formed in this way and are as narrow as possible ensure that only a small region covered by few clamping jaws has to be opened in order to apply the film web to the plates. As a result, there is only a small region in which the film web is free and unfixed.
It may be advantageous to arrange one or more retaining magnets on the clamping jaws. Preferably, however, the at least one retaining magnet is positioned in the clamping surface. In this way, the individual clamping jaws can be configured in a simple and lightweight manner such that they can be opened and closed again at a high cycle rate without mechanical considerations.
In an embodiment, suction openings for drawing the film web against the clamping surface are formed in the clamping surface. It is thus possible, where a negative pressure is available along the movement path of the transportation plates, for the retaining force at the edges of the film web to be significantly increased, such that it is not just the magnetic force that needs to be used for fixing. In particular in the region of the thermoforming station, where, as a result of the thermoforming operation, the highest forces act on the film, highly loadable film fixing can be achieved. However, even in the subsequent stations, for example in the filling station, where an admittedly low, but still present negative pressure acts on the film web, it is possible for the retaining force to be increased via the suction openings.
In addition, it may also be expedient for each clamping jaw to be assigned at least one closing spring, wherein the clamping jaw is pressed spring-elastically against the clamping surface via the closing spring. The closing springs not only increase the contact pressure and thus the retaining force. They can also bring about automatic closing of the clamping jaws from their completely open position, without a separate closing drive being absolutely necessary.
Various concepts come into question as actuating means of the clamping jaws.
Preferably, the actuators or actuating means can be in the form of a slotted guide which guides the actuating extensions, wherein the slotted guide includes at least one opening portion that lifts the clamping jaw off the clamping surface. The slotted guide thus acts with its opening portion on the actuating extension running thereon such that the clamping jaw is lifted or pivoted up counter to the holding force of the retaining magnet and possibly also counter to the preloading force of the closing spring. The subsequent closing of the clamping jaw can then be brought about without the slotted guide being influenced by the closing spring. Alternatively or additionally, an embodiment provides that the slotted guide includes a closing portion that guides the clamping jaw onto the clamping surface. This then brings about—with or without a closing spring—positively controlled closure of the clamping jaw. Overall, a reliable actuating mechanism with a simple structural configuration has been found.
The invention will now be described with reference to the drawings wherein:
In addition to the machine frame 3 mounted in a fixed position, the packaging machine includes a continuously driven conveyor 7. The conveyor 7 is formed by film transportation plates 10 which are connected together in an articulated and chain-like manner and on which format plates 11 (
At the two lateral edges 13, 14, the film transportation plate 10 is provided in each case with at least one clamping jaw 19. In the embodiment shown, the film transportation plate 10 has, at the two lateral edges 13, 14, a plurality of, here in each case four, clamping jaws 19. The clamping jaws 19 are movable relative to the clamping surfaces 15 and are illustrated in the open state in the present case. To this end, the clamping surfaces 15 are formed fixedly at the lateral edges 13, 14, while the clamping jaws 19 are pivotable about pivot axes 21 extending parallel to the direction of movement 8. The fixed configuration of the clamping surfaces 15 means that they do not carry out any relative movement with respect to the film transportation plate 10, and only undergo a movement along the arrow 8 together therewith. However, it may also be expedient for the clamping surfaces 15 to be embodied in a movable manner. What is most important is that a relative movement between the clamping jaws 19 and clamping surfaces 15 can take place. Additionally or alternatively to the abovementioned pivotability of the clamping jaws, movability in translation may also be expedient.
On viewing
The kinematic actuation of the clamping jaws 19 is apparent from the phase images according to
A respective slotted guide 23 is fixedly mounted on the side of the machine frame 3 (
According to
In the following phase, shown in
After this has taken place, the clamping jaws 19 are closed again in order to clamp and retain the film web 1 according to
After the packages have been completed and separated in the packaging machine according to
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
22 154 626.0 | Feb 2022 | EP | regional |