Reefing under stretch
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.
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.