Method and apparatus for shrinking a heat-shrink film applied around an, in particular palletized, goods stack

Abstract

The invention relates to a shrinking a heat-shrink film around palletized goods. The heat-shrink film projects beyond the top edge of the goods stack. Firstly the heat-shrink film is shrunk in the region of a first lateral surface sub-region of the four lateral surface sub-regions of the goods stack. The shrinkage direction is from bottom to top and then the shrinkage direction is changed 90°. In a further step either, the shrinkage direction is changed a further 90°, the heat-shrink film is shrunk from top to bottom in the region of that lateral surface sub-region of the goods stack, or, the shrinkage direction is changed a further 90°, and the heat-shrink film is preheated from top to bottom in the region of that lateral surface sub-region which is located oppositely from the first lateral surface sub-region, and is then shrunk in the opposite direction from bottom to top.

I claim: 
     
         1 . A method for shrinking a heat-shrink film ( 4 ) applied around an, in particular palletized, goods stack ( 2 ) that comprises a bottom surface, a cover surface, and a circumferential lateral surface that is made up of four lateral surface sub-regions, with at least one heating device ( 5 ) for shrinking the heat-shrink film ( 4 ) by heating, the heat-shrink film ( 4 ) covering the lateral surface of the goods stack ( 2 ) at least in its top region, preferably the entire height of the lateral surface, and the heat-shrink film ( 4 ) projecting at the top, at least with a heat-shrink film sub-region ( 4   a ), beyond the top edge of the goods stack ( 2 ) for formation of a top shrink,
 wherein firstly the heat-shrink film ( 4 ) is shrunk in the region of a first lateral surface sub-region of the four lateral surface sub-regions of the goods stack ( 2 ), the shrinkage direction ( 12 ) being from bottom to top; then, the shrinkage direction ( 12 ) being changed approximately 90°, that heat-shrink film sub-region ( 4   a ) of the heat-shrink film ( 4 ) which projects at the top beyond the top edge of the goods stack ( 2 ) is shrunk, beginning from the top edge of the first lateral surface sub-region along the cover surface; and in a further step   
       either, the shrinkage direction ( 12 ) being changed approximately a further 90°, the heat-shrink film ( 4 ) is shrunk from top to bottom in the region of that lateral surface sub-region of the goods stack ( 2 ) which is located oppositely from the first lateral surface sub-region, 
       or, the shrinkage direction ( 12 ) being changed approximately a further 90°, the heat-shrink film ( 4 ) is preheated from top to bottom in the region of that lateral surface sub-region of the goods stack ( 2 ) which is located oppositely from the first lateral surface sub-region, and is then shrunk in the opposite direction from bottom to top. 
     
     
         2 . The method according to  claim 1 , wherein the goods stack ( 2 ) is stationary during shrinking; and at least one, preferably vertically adjustable, heating device ( 5 ) is guided along the goods stack ( 2 ). 
     
     
         3 . The method according to  claim 1 , wherein in the context of shrinkage, the goods stack ( 2 ) is moved in a conveying direction ( 3 ) by means of a conveying device ( 1 ) whose conveying speed is preferably regulatable, the first of the four lateral surface sub-regions of the goods stack ( 2 ) facing in the conveying direction ( 3 ); and at least one heating device ( 5 ) is arranged pivotably around an axis ( 6 ) oriented parallel to its lengthwise dimension but in stationary fashion in relation to the conveying direction ( 3 ). 
     
     
         4 . The method according to  claim 1 , wherein in the context of the relative displacement between the goods stack ( 2 ) and at least one, preferably vertically adjustable, heating device ( 5 ) in the context of shrinkage, a narrow marginal region ( 13 ) of the heat-shrink film ( 4 ) on at least one of the two lateral surface sub-regions oriented parallel to the shrinkage direction ( 12 ) during shrinking of the cover surface, which region adjoins the edge to the first lateral surface sub-region of the goods stack ( 2 ) and/or adjoins the edge to the top side of the goods stack ( 2 ) and/or adjoins the edge to that lateral surface sub-region of the goods stack ( 2 ) which is located oppositely from the first lateral surface sub-region, is additionally shrunk. 
     
     
         5 . The method according to  claim 1 , wherein the heat-shrink film ( 4 ) is embodied as a heat-shrink film wrapper. 
     
     
         6 . The method according to  claim 5 , wherein a cover sheet film, preferably projecting beyond at least one lateral edge of the cover surface of the goods stack ( 2 ), is arranged on the top side of the goods stack ( 2 ), which film is heat-sealed to that heat-shrink film sub-region ( 4   a ) of the heat-shrink film ( 4 ), embodied as a heat-shrink film wrapper, which projects beyond the top edge of the goods stack ( 2 ). 
     
     
         7 . The method according to  claim 6 , wherein simultaneously with or after shrinking of that heat-shrink film sub-region ( 4   a ) of the heat-shrink film ( 4 ) which projects at the top beyond the top edge of the goods stack ( 2 ), the cover sheet film is also at least partly shrunk in the region that is not in contact with the heat-shrink film sub-region ( 4   a ) applied as a consequence of shrinking. 
     
     
         8 . The method according to  claim 1 , wherein the heat-shrink film ( 4 ) is embodied as a heat-shrink film hood pulled over the goods stack ( 2 ). 
     
     
         9 . The method according to  claim 1 , wherein at least during shrinking of the first of the four lateral surface sub-regions, the goods stack ( 2 ) is at least partly, preferably completely, covered at the top by a planar thermal conduction and/or thermal reflection device ( 7 ) arranged above the goods stack ( 2 ) at a distance from the cover surface and oriented parallel thereto. 
     
     
         10 . The method according to  claim 1 , wherein at least during shrinking of the cover surface, the goods stack ( 2 ) is at least partly, preferably completely, covered at the top by a planar thermal conduction and/or thermal reflection device ( 7 ) arranged above the goods stack ( 2 ) at a distance from the cover surface and oriented parallel thereto. 
     
     
         11 . The method according to  claim 1 , wherein the heat-shrink film ( 4 ) is preheated in the region of the first lateral surface sub-region, preferably from top to bottom, prior to shrinking. 
     
     
         12 . An apparatus for shrinking a heat-shrink film ( 4 ) applied around an, in particular palletized, goods stack ( 2 ) that comprises a bottom surface, a cover surface, and a circumferential lateral surface that is made up of four lateral surface sub-regions, having at least one heating device ( 5 ) for shrinking the heat-shrink film ( 4 ) by heating, the heat-shrink film ( 4 ) covering the lateral surface of the goods stack ( 2 ) at least in its top region, preferably the entire height of the lateral surface, and the heat-shrink film ( 4 ) projecting at the top, at least with a heat-shrink film sub-region ( 4   a ), beyond the top edge of the goods stack ( 2 ) for formation of a top shrink,
 wherein the apparatus encompasses a conveying device ( 1 ) for moving the goods stack ( 2 ) in a conveying direction ( 3 ) during shrinking; and for heat impingement, at least one heating device ( 5 ) is embodied in oblong fashion and is oriented above the conveying device ( 1 ) horizontally and orthogonally to the conveying direction ( 3 ), and the lengthwise dimension of the heating device ( 5 ) extends at least approximately over the width of the goods stack ( 2 ), the heating device ( 5 ) being arranged vertically adjustably and mounted pivotably around an axis ( 6 ) oriented parallel to its lengthwise dimension, and furthermore a control system being provided by means of which firstly the heat-shrink film ( 4 ) is shrunk in the region of a first lateral surface sub-region of the four lateral surface sub-regions of the goods stack ( 2 ), the shrinkage direction ( 12 ) being from bottom to top, then, the shrinkage direction ( 12 ) being changed approximately 90°, that heat-shrink film sub-region ( 4   a ) of the heat-shrink film ( 4 ) which projects at the top beyond the top edge of the goods stack ( 2 ) is shrunk, beginning from the top edge of the first lateral surface sub-region along the cover surface, and in a further step   either, the shrinkage direction ( 12 ) being changed approximately a further 90°, the heat-shrink film ( 4 ) is shrunk from top to bottom in the region of that lateral surface sub-region of the goods stack ( 2 ) which is located oppositely from the first lateral surface sub-region,   or, the shrinkage direction ( 12 ) being changed approximately a further 90°, the heat-shrink film ( 4 ) is preheated from top to bottom in the region of that lateral surface sub-region of the goods stack ( 2 ) which is located oppositely from the first lateral surface sub-region, and is then shrunk in the opposite direction from bottom to top.   
     
     
         13 . The apparatus according to  claim 12 , wherein at least one heating device ( 5 ) comprises different mutually independently controllable heating regions. 
     
     
         14 . The apparatus according to  claim 12 , wherein at least one heating device ( 5 ) is embodied as a gas burner strip. 
     
     
         15 . The apparatus according to  claim 12 , wherein that side of at least one heating device ( 5 ) which faces toward the goods stack ( 2 ) is embodied to be flat. 
     
     
         16 . The apparatus as recited in  claim 12 , wherein at least one heating device ( 5 ) protrudes beyond the width of the goods stack ( 2 ), so that the heating device ( 5 ) projects beyond the goods stack ( 2 ) at least on one side, preferably on both sides, of the goods stack ( 2 ). 
     
     
         17 . The apparatus according to  claim 12 , wherein at least one region, projecting laterally with respect to the goods stack ( 2 ), of at least one heating device ( 5 ) is arranged pointing toward the goods stack ( 2 ) at an angle. 
     
     
         18 . The apparatus according to  claim 16 , wherein at least one region projecting laterally with respect to the goods stack ( 2 ) comprises at least one device for modifying the discharge direction of the hot air. 
     
     
         19 . The apparatus according to  claim 12 , wherein at least one planar thermal conduction and/or thermal reflection device ( 7 ) is provided, which device: at least partly, preferably completely, covers the goods stack ( 2 ) at the top at least during shrinking of the first of the four lateral surface sub-regions; is arranged above the goods stack ( 2 ) at a distance from the cover surface; and is oriented parallel to the latter. 
     
     
         20 . The apparatus according to  claim 19 , wherein at least one thermal conduction and/or thermal reflection device ( 7 ) is arranged vertically adjustably. 
     
     
         21 . The apparatus according to  claim 19 , wherein at least one thermal conduction and/or thermal reflection device ( 7 ) completely covers the cover surface of the goods stack ( 2 ), or is embodied to be even bigger with an overhang. 
     
     
         22 . The apparatus according to  claim 19 , wherein at least one thermal conduction and/or thermal reflection device ( 7 ) is equipped laterally, on its two lateral edges oriented parallel to the conveying direction ( 3 ), with a respective downward-pointing angled piece ( 8 ). 
     
     
         23 . The apparatus according to  claim 19 , wherein at least one thermal conduction and/or thermal reflection device ( 7 ) is equipped, on its lateral edge oriented oppositely to the conveying direction ( 3 ), with a downward-pointing end-face angled piece ( 9 ).