REEFING UNDER STRETCH

Abstract

The present invention relates to a method for gathering-up a tubular film portion on at least two gathering fingers of a packaging machine and to a gathering apparatus of a packaging machine for carrying out the method as claimed in the invention. The method is distinguished in that the tubular film portion is expanded at least in a part region when being gathered-up onto the gathering fingers. The gathering apparatus as claimed in the invention is distinguished in that the gathering fingers can be driven into a gathering-up position for gathering-up the tubular film portion, in which gathering-up position the tubular film portion is expanded at least in a part region.

Claims

1. A wrapping machine for wrapping an object with tubular film, the tubular film having an unstretched perimeter length, the wrapping machine comprising: multiple gathering fingers each including a contact roller, wherein the gathering fingers are movable laterally outward relative to one another from a gathering configuration to a wrapping configuration, wherein when the gathering fingers are in the gathering configuration, the contact rollers define a gathering perimeter having a gathering perimeter length greater than the unstretched perimeter length of the tubular film, and wherein when the gathering fingers are in the wrapping configuration, the contact rollers define a wrapping perimeter having a wrapping perimeter length greater than the gathering perimeter length; multiple gathering rollers, each gathering roller operatively connectable to one of the contact rollers; multiple gathering drives, each gathering drive operatively connected to one of the gathering rollers to drive that gathering roller, and a controller configured to: when the gathering fingers are in the gathering configuration, control the gathering drives to drive the gathering rollers to gather the tubular film onto the gathering fingers; after the tubular film is gathered onto the gathering fingers, control the gathering fingers to move to the wrapping configuration; and after the gathering fingers have reached the wrapping configuration, control the gathering drives to drive the gathering rollers to discharge the tubular film from the gathering fingers and onto the object.

2. The wrapping machine of claim 1, wherein the contact rollers are mounted to their respective gathering fingers such that an axis of rotation of each contact roller is external to its respective gathering finger.

3. The wrapping machine of claim 1, wherein the gathering perimeter and the wrapping perimeter are rectangular.

4. The wrapping machine of claim 3, wherein the gathering fingers are positioned so as to form the corners of the rectangular gathering and wrapping perimeters.

5. The wrapping machine of claim 1, wherein the gathering fingers each comprise a contact region below their respective contact rollers.

6. The wrapping machine of claim 5, wherein the contact regions define a contact region perimeter having a contact region perimeter length.

7. The wrapping machine of claim 6, wherein the contact region perimeter length is a first contact region perimeter length when the gathering fingers are in the gathering configuration and a second contact region perimeter length greater than the first contact region perimeter length when the gathering fingers are in the wrapping configuration.

8. The wrapping machine of claim 7, wherein the contact rollers are mounted to their respective gathering fingers such that an axis of rotation of each contact roller is external to its respective gathering finger so the gathering perimeter length is greater than the first contact region perimeter length and the wrapping perimeter length is greater than the second contact region perimeter length.

9. The wrapping machine of claim 8, wherein the first contact region perimeter length is less than the unstretched perimeter length.

10. The wrapping machine of claim 8, wherein the first contact region perimeter length is greater than the unstretched perimeter length.

11. The wrapping machine of claim 5, wherein each gathering finger further comprises a supporting means in its respective contact region.

12. The wrapping machine of claim 1, wherein the controller is further configured to move the gathering fingers downward relative to the object while controlling the gathering drives to drive the gathering rollers to discharge the tubular film from the gathering fingers and onto the object.

Description

[0026] The invention is to be explained in more detail below by way of further exemplary embodiments shown in the drawing, in which in a schematic manner:

[0027] FIG. 1 shows a known gathering finger in a gathering-up position known from the prior art;

[0028] FIG. 2 shows a first exemplary embodiment of the invention using a conventional gathering finger in a gathering-up position as claimed in the invention;

[0029] FIG. 3 shows a second exemplary embodiment of the invention using a first variant of a gathering finger modified as claimed in the invention in a first gathering-up position as claimed in the invention;

[0030] FIG. 4 shows a third exemplary embodiment of the invention using a second variant of a gathering finger modified as claimed in the invention with a shortened installation height in a second gathering-up position as claimed in the invention;

[0031] FIG. 5 shows a fourth exemplary embodiment of the invention using a third variant of a gathering finger modified as claimed in the invention with a supporting means; and

[0032] FIG. 6 shows a top view of a packaging machine with the gathering fingers shown in FIG. 5.

[0033] FIGS. 1 to 5 show, in each case in the manner of cutouts, the side view of a gathering finger 1 of a gathering apparatus 2 of a packaging machine which is used to gather a tubular portion film 3. Four gathering apparatuses 2, which are arranged in the corners of a rectangular frame and each have one gathering finger 1, are used in a typical manner in the case of a packaging machine, as is also shown in FIG. 6.

[0034] As contact means, the gathering finger 1 has a contact roller 4 which is mounted at its upper end with an axis of rotation 5. The contact roller 4 can be moved into operative connection with a gathering roller 6 of a gathering drive unit and thus encloses the tubular film portion 3. The gathering drive unit can have an electric motor, for example, to drive the gathering roller 6. Said electric motor drives each of the gathering rollers 6 in such a manner that the tubular film portion 3 is gathered-up onto the gathering finger 1, as indicated by the movement arrows of the contact roller 4 and gathering roller 6. Consequently, the tubular film portion is gathered-up in the manner of a film store 7 in the contact region 8 of the gathering finger 1.

[0035] FIG. 1 shows a gathering finger 1 of a gathering apparatus 2, which is known per se from the prior art, in a conventional gathering-up position HAP. The axis of rotation 5 of the contact roller 4 is arranged as usual inside the gathering finger 1 such that the largest part of the contact roller 4 is inside the gathering finger 1.

[0036] The gathering finger 1 shown in FIG. 1 is located as mentioned in a conventional gathering-up position in which the tubular film portion 3 is not expanded, that is to say is slack. This is also indicated by the size specification (100x1)%. For example, the relative value for x1 can amount to between 2% and 5% or more. This means that the tubular film portion, which is unfolded by the driving of the gathering fingers 1 into the usual gathering-up position, is not yet fully unfolded. Rather, on account of the adhesive effect of the film in the delivery state, it has a size which could amount to approximately between 95% and 98% of the actual size of the tubular film portion 3.

[0037] During the gathering-up process a film store 7 is now created in the known manner, said film store extending in the vertical direction along the contact region 8. It has an irregular fold formation which is substantially inclinedly vertical. Using the gathering finger 1 shown in FIG. 1 along with the gathering-up position HAP shown, vertically aligned folds in the tubular film portion 3 can, however, be incorporated as far as into the tubular film store, which can lead to the mentioned difficulties when the film is ungathered.

[0038] FIG. 2 shows the gathering finger 1 represented in FIG. 1 once again. However the gathering finger 1 is situated in a gathering-up position EAP as claimed in the invention, in which gathering-up position the tubular film portion 3 is expanded in the region between the contact roller 4 and the gathering roller 5 by the relative size difference x2 (for example between 3% and 5%). As a result of the expanding of the tubular film portion 3 in the region of the contact roller 4, almost all the folds caused by the production process are removed from the tubular film portion 3.

[0039] FIG. 3 shows a second exemplary embodiment of the invention with a first variant of a gathering finger 1 modified as claimed in the invention where the axis of rotation 5 of the contact roller 4 is arranged outside the contact region 8 of the gathering finger 1. The gathering finger 1 is situated in the identical gathering-up position HAP as the gathering finger 1 shown in FIG. 1. In contrast to this, the tubular film portion 3, however, is expanded in the region between the contact roller 4 and the gathering roller 5, as is indicated by the size specification (100+x2)%. For example, the tubular film portion 3 is expanded by approximately between 3% and 5% such that its size in this region would be enlarged to between 103% and 105% of its size when produced. As a consequence, there is the identical effect here as in the case of the gathering finger 1 shown in FIG. 2, namely the removal of folds in the tubular film portion 3 produced during the production process.

[0040] FIG. 4 shows a third exemplary embodiment of the invention using a second variant of a gathering finger 1 as claimed in the invention. This latter corresponds substantially to the gathering finger 1 shown in FIG. 3, but has a smaller installation height than the gathering finger 1 shown in FIG. 3. The gathering finger 1 is situated here too in a gathering-up position EAP which is modified as claimed in the invention. The tubular film portion 3 is consequently expanded over the entire contact region 8 by the relative size difference x3, it could be possible for x3, for example, to be within the region of between 3% and 20% or even more. In addition, the tubular film portion 3 is expanded in the region of the contact roller 4 by the relative size difference x4, which, for example, could be in the region of in excess of 5%. Consequently, folds caused in the production process are removed from the tubular film portion 3 during the gathering-up process.

[0041] The combination of the modified gathering-up position and the modified gathering finger 1 shown in FIG. 4 results in it being possible to create a film store 7 which has a substantially vertical fold formation and which extends substantially in the horizontal direction away from the contact region 8. This means that it is possible to realize a smaller installation height of the gathering finger 1 than up to now as the film store 7 grows widthwise and no longer downward as usual up to now. To elucidate the effect, the finger shown in FIG. 1 is also shown in FIG. 4, however by a broken line. It is clear to see that the installation height of the gathering finger 1 differs by the amount .sub.H.

[0042] FIG. 5 shows a fourth exemplary embodiment of the invention using a third variant of the gathering finger 1 as claimed in the invention. The gathering finger 1 differs from the gathering finger 1 shown in FIG. 4 in that the contact roller 4 is arranged completely outside the gathering finger 1, or has been moved out from the same. In addition, the gathering finger 1 has a supporting means 9 on which the film store 7 is supported in the vertical direction. The supporting means 9 can be moved in the horizontal and vertical direction in order, in this manner, to enable adaptation during the gathering-up process to the various products to be wrapped. In the representation according to FIG. 5, the tubular film portion 3 is expanded in the entire contact region 8 by the relative size difference x5, and in the region of the contact roller 4 by the relative size difference x6, it could be possible for x5 and x6 to be within the range of, for example, between 3% and 20% or more.

[0043] FIG. 6 shows a top view of a packaging machine for wrapping a product 10, said wrapping machine having four gathering fingers 1 as claimed in the invention and as are shown in FIG. 5. As the figure clearly shows, it is possible to move the gathering fingers relatively close to the product 10.

[0044] In general it is also conceivable for the gathering finger 1 to be moved in dependence on the progress of the gathering process in such a manner that the relative size difference continuously increases. In addition, it is conceivable for the position of the contact roller 4 on the gathering finger 1 to be modified in dependence on the progress of the gathering process at least in the horizontal but also in the vertical direction. As a consequence, a continuous increase in the relative size difference is achieved. Consequently, it is possible to control the crease or the horizontal extent of the film store 7.

LIST OF REFERENCES

[0045] 1 Gathering finger [0046] 2 Gathering apparatus [0047] 3 Tubular film portion [0048] 4 Contact roller/contact means [0049] 5 Axis of rotation of the contact roller [0050] 6 Gathering roller [0051] 7 Film store [0052] 8 Contact region [0053] 9 Supporting means [0054] 10 Product [0055] HAP Conventional gathering-up position [0056] EAP Gathering-up position as claimed in the invention [0057] x1-x6 Relative size difference [0058] .sub.H Installation height difference