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US 10,538,354 B2Granted
Method and apparatus for wrapping a film around an object
AssigneeMsr-Verpackungs-Systeme GmbH
InventorsReiner Hannen, Norbert Vermeulen
Life of this patent
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Abstract
An object is first wrapped with a strip of thermoplastic film such that upper edges of the strip project upward past a top face of the object and fold inward onto outer edge regions of the top face of the object. Then a cover sheet is laid on the top face over the folded-in edges of the strip with outer edges of the cover sheet projecting outward past and hanging down around the wrapped object outside the film strip. A heated plate is then pressed down against the cover sheet and hot air is blown against the strip on the side faces so as to shrink the strip against the side faces and such that the hot air rises and welds the outer cover-sheet edges sheet to the strip around upper regions of the side faces.
Claims8
A method of shrink packaging an object having outwardly directed side faces and an upwardly directed top face, the method comprising the steps of sequentially:
- wrapping a strip of thermoplastic film around the side faces of the object such that an upper edge of the strip projects upward past the top face of the object and folds inward onto outer edge regions of the top face of the object;
- laying a cover sheet of thermoplastic film on the top face of the object over the folded-in upper edge of the strip with an outer edge of the cover sheet projecting outward past and hanging down outside the film strip along upper edge regions of the side faces of the object;
- forming a downwardly open and downwardly extendable shrinking chamber between a vertically shiftable heated plate having outer edges and a plurality of vertically extendable side walls movable independently of the plate, extending downward from the outer edges along and spaced horizontally outwardly from respective side faces of the object, and having lower ends carrying an annular shrink frame vertically displaceable with the walls;
- moving the plate, walls, and shrink frame down over the object wrapped in the strip of film and cover sheet to enclose the top face and to press the heated plate down against the cover sheet to flatten same and the folded-in upper edge of the strip against the top face;
- maintaining the plate at a temperature sufficient to soften the cover sheet but below a melting point of the cover sheet such that the cover sheet is heated by the plate only to a temperature sufficient to soften the cover sheet but not to melt and weld the cover sheet to the top face;
- and thereafter,
- while holding the cover sheet down on the top face with the heated plate, blowing hot air from the shrink frame between the side faces and the side walls of the chamber while the walls are moving downward from an upper position with the shrink frame level with the upper regions of the side faces so as to first lift the outwardly projecting edge of the cover strip, then, as the walls and shrink frame move downward to a lower position with the shrink frame level with lower edges of the side faces, cause the lifted outwardly projecting edge to drop back against the strip at upper regions of the side faces and shrink against and weld to an outer face of the strip around the upper regions of the side faces with the hot air trapped between the side walls and side faces while pressing and shrinking the strip against the side faces of the object as the shrink frame moves into the lower position, the walls laterally closing the chamber between the shrink frame and plate when in and between the upper and lower positions.
4 more elements
An apparatus for shrink packaging an object having outwardly directed side faces and an upwardly directed top face, the apparatus comprising:
- a support for holding the object with the side faces vertical and the top face horizontal;
- means for wrapping a strip of thermoplastic film around the side faces of the object such that an upper edge of the strip projects upward past the top face of the object and folds inward onto outer edge regions of the top face of the object;
- means for laying a cover sheet of thermoplastic film on the top face of the object over the folded-in upper edge of the strip with outer edges of the cover sheet projecting outward past and hanging down outside the film strip along upper edge regions of the side faces of the object;
- a vertically displaceable heat-controlled plate above the upper face and having an outer edge projecting horizontally outward past the side faces of the object;
- respective vertically extendable side walls projecting downward from the outer edge of the plate, movable vertically independently of the plate, each spaced horizontally outward from a respective one of the side faces of the object, and forming with the plate a downwardly open and downwardly expandable shrink chamber spacedly surrounding the object;
- an annular shrink frame carried on lower ends of the side walls;
- means for maintaining the plate at a temperature below a melting point of the cover sheet but sufficient to soften the cover sheet;
- means for downwardly moving the heated plate, side walls, and shrink frame from an upper position with the shrink frame level with the upper regions of the side faces toward a lower position with the shrink frame level with a lower edges of the side faces while the walls laterally close a space between the shrink frame and the plate to press the heated plate down against the cover sheet to flatten same and the folded-in upper edge of the strip against the top face while the heated plate softens the cover sheet without welding it to the top face;
- and
- means for blowing hot air between the side walls and the side faces while the plate is pressed down against the cover sheet so the hot air is trapped in the shrink chamber between the side walls and the side faces and first lifts the outer edge of the cover lift with the hot air and then as the walls and shrink frame move to the lower position lets the lifted outer edge drop back against and weld to an outer side of the strip around upper regions of the side faces while pressing the strip against the side faces.
7 more elements
Dependencies are inferred from the claim text.