Apparatus and method for heat shrinking a film wrapping an object

Abstract

An apparatus for heat shrinking a film wrapping an object includes a housing having a heat treatment chamber, a transport device for supporting and moving the object through the heat treatment chamber. Steam, supplied from at least one supply is led to at least a first and a second fluid outlet device and directed at the transported object using one or more outlets. The fluid outlet devices are disposed on opposite sides of the transport device. According to the invention the apparatus and method further include generating a downward directed fluid flow in an area extending between the fluid outlet devices having a lower temperature than the steam supplied from the outlets. This results in improved sleeving results and higher efficiency.

1 . A heat shrink oven for heat shrinking a film wrapping an object, the heat shrink oven comprising:
 a housing having a heat treatment chamber for containing steam and for arranging a steam flow pattern,   a transport device for supporting and moving the object through the heat treatment chamber,   at least one steam supply for supplying steam to the heat treatment chamber,   at least a primary steam unit comprising a first and a second steam outlet device comprising one or more outlets for steam, the steam outlet devices connected to the steam supply, the first steam outlet device disposed in the heat treatment chamber along a first side of the transport device and the second steam outlet device disposed along a second side of the transport device, opposite the first side, the outlets directed towards the moving object,   wherein the heat shrink oven further comprises,   a secondary steam system, arranged in the heat treatment chamber, for generating a downward directed steam flow in an area extending between the steam outlet devices, the downward directed steam flow having a lower temperature than the steam supplied from the steam outlet devices, wherein the secondary steam system is arranged to be supplied with steam internal in the heat treatment chamber.   
     
     
         2 . The heat shrink oven according to  claim 1 , wherein the secondary steam system is arranged to supply secondary steam having a temperature of at least 4 degrees Celsius lower than the primary steam flow entering the heat treatment chamber through the outlets. 
     
     
         3 . The heat shrink oven according to  claim 1 , wherein the secondary steam system is arranged to supply secondary steam having a temperature of less than 88 degrees Celsius. 
     
     
         4 . The heat shrink oven according to  claim 1 , wherein the outlets are positioned to supply the primary steam directed generally horizontal. 
     
     
         5 . The heat shrink oven according to  claim 1 , wherein the secondary steam system for generating the downwardly directed steam flow is also arranged to generate a generally upward directed steam flow in the heat treatment chamber in an area outside the area between the opposite fluid outlet devices. 
     
     
         6 . The heat shrink oven according to  claim 1 , wherein the secondary steam system for generating the downwardly directed steam flow comprises a guide allowing the outward guiding of the steam flow. 
     
     
         7 . The heat shrink oven according to  claim 5 , wherein the apparatus comprises a frame received in the heat treatment chamber for mounting the steam outlet devices and wherein the secondary steam system for generating the steam flow surrounds the steam outlet devices mounted to the frame. 
     
     
         8 . The heat shrink oven according to  claim 1 , wherein the secondary steam system for generating the downwardly directed steam flow further comprises steam flow device arranged to generate the downward flow of steam. 
     
     
         9 . The heat shrink oven according to  claim 1 , wherein multiple sets of steam outlet devices are provided along the transport device and wherein the secondary steam system is positioned at the most upstream steam outlet devices or upstream from the most upstream steam outlet devices. 
     
     
         10 . The heat shrink oven according to  claim 1 , wherein the steam outlet device comprises at least three or more outlets in a straight line. 
     
     
         11 . The heat shrink oven according to  claim 1 , wherein the transport device is at least partially received in the heat treatment chamber and the object is a generally cylindrical container for a beverage and the film is a cylindrical envelope. 
     
     
         12 . The heat shrink oven according to  claim 1 , wherein the heat treatment chamber is a closed housing containing the steam, the heat treatment chamber having a tunnel-shaped space, the transport device arranged to carry objects through the tunnel-shaped space. 
     
     
         13 . The heat shrink oven according to  claim 1 , wherein the heat treatment chamber is arranged to allow circulation of the secondary steam flow. 
     
     
         14 . The heat shrink oven according to  claim 13 , wherein the heat treatment chamber and secondary steam system are arranged to maintain the flow of secondary steam continuously. 
     
     
         15 . A method of shrinking a heat shrinkable film wrapping an object, the method comprising in a heat treatment chamber of a heat shrink oven:
 transporting the upright standing object wrapped with heat shrinkable film through the heat treatment chamber,   applying primary steam onto a side of the film, and   directing secondary steam of lower temperature than the primary in a downward direction onto the object,   the heat treatment chamber containing the steam and allowing circulation of secondary steam.   
     
     
         16 . The method according to  claim 15 , wherein the method comprises maintaining the flow of secondary steam continuously in the heat treatment chamber. 
     
     
         17 . The method according to  claim 15 , wherein the secondary steam is directed onto the object upstream from the application of primary steam. 
     
     
         18 . The method according to  claim 15 , wherein the secondary steam is directed onto the object during application of the primary steam. 
     
     
         19 . The method according to  claim 15 , wherein directing the steam in the downward direction comprises generating a closed flow pattern for steam in the heat treatment chamber, in the downward direction onto the object, in an outwards direction, away from the object, followed by an upward direction and inward direction. 
     
     
         20 . The method according to  claim 15 , wherein applying the steam for heat shrinking a first part of the film comprises applying the steam to a bottom part of the object. 
     
     
         21 . The method according to  claim 15 , wherein the method comprises multiple stages of applying steam to the object being transported through the heat treatment chamber. 
     
     
         22 . The method according to  claim 15 , wherein steam is applied from two opposite sides onto the object carried through the heat treatment chamber.