Method and device for packaging objects in a weldable film

Abstract

In a sealing/parting means for the side weld ( 42 ) of a film semi-tube ( 13 ) of shrink film, in which items ( 16 ) are wrapped, the film web ( 19 ) consisting of two sandwiched films is fed to a transport and supporting system ( 18 ) comprising two opposing transport belts ( 21, 22 ) where it runs along an elongated, skid-shaped contact surface area ( 34 ) of a heated sealing/parting knife ( 20 ), resulting in the immediate welding zone of the film being preheated before it is fed at the end of this contact surface area to a sealing/parting blade ( 36 ) which parts and welds the film. The sealing/parting blade ( 36 ) has a constricting cutting gap.

1 . A method of packaging items ( 14 ) by means of a weldable film ( 19 ) in which the film is transported relative to a sealing/parting device ( 12 ) in a film transport direction ( 17 ) comprising the steps of 
 feeding the film ( 19 ) to said sealing/parting device ( 12 ) in at least two plies, preheating an area of the film in said sealing/parting device ( 12 ) in a preheating zone ( 34 ) of said sealing/parting device,    subsequently parting said film by means of a heated sealing/parting blade ( 36 ) in said preheated film area, thereby creating heated parted edges of the film, and    thus simultaneously welding at least two of the plies at the parted edges.    
     
     
         2 . The method as set forth in  claim 1  wherein said film area is preheated by contact heat transfer in said preheating zone.  
     
     
         3 . The method as set forth in  claim 1 , wherein said film area is a narrow, longitudinal area of the restricted to immediate vicinity of said cut portion.  
     
     
         4 . The method as set forth in  claim 1 , wherein preheating is undertaken in a preheating zone ( 34 ) oriented elongated in said film transport direction ( 17 ).  
     
     
         5 . The method as set forth in  claim 1 , wherein said film ( 19 ) is a polyolefine film.  
     
     
         6 . The method as set forth in  claim 6 , wherein said film ( 19 ) is a shrink film between 30 and 120 □m thick of the kind as marketed by SEALED AIR CORP. CRYOVAC, Rodgers Bridge Road, Building A, Duncan, SC 129334-0464, U.S.A. designated ,,CorTuff“.  
     
     
         7 . A device for packaging items ( 14 ) by means of a weldable film ( 19 ) comprising 
 a film transport ( 16 , 18 ), with which said film is transported in a transport direction ( 17 ) relative to a sealing/parting device ( 12 ),    said film ( 19 ) includes, when passing said sealing/parting device ( 12 ), at least two layers,    said sealing/parting device ( 12 ) comprises a preheating zone ( 34 )    and, following on the preheating zone, a heated sealing/parting blade ( 36 ).    
     
     
         8 . The device as set forth in  claim 7  wherein of a sealing/parting knife ( 20 ) includes said sealing/parting blade ( 36 ) and an elongated bar ( 33 ) having, with regard to the transport direction, a leading and a tailing end the bar forming said preheating zone, at which said film ( 19 ) is guided along in contact in said film transport direction ( 17 ), the sealing/parting knife ( 20 ) being provided at the tailing end.  
     
     
         9 . A heatable sealing/parting knife ( 20 ) for a device ( 11 ) for packaging items by means of a weldable film ( 19 ), said film being guided in at least two plies in a film transport direction ( 17 ) and in a film running plane to said sealing/parting knife ( 20 ) and along thereof, resulting in said multi-ply film ( 19 ) fed to said sealing/parting knife ( 20  being parted and thereby welding at least two sandwiched film plies to each other, the knife comprising: 
 a surface portion runmning parallel to said film running plane including an elongated contact surface area ( 34 ) facing said film running plane, and  
 an adjoining sealing/parting blade ( 36 ) crossing said film running plane.  
 
     
     
         10 . The sealing/parting knife as set forth in  claim 9  wherein said contact surface area has, with reference to said film running direction, a leading end and a tailing end, and has at its leading end, an intake rounding ( 35 ) and adjoining thereto a straight strip-type, elongated contact surface area ( 34 ) of small size transversely to said film running direction ( 17 ) and wherein said sealing/parting blade ( 36 ) as compared to said contact surface area portion is short and has a cutting edge ( 38 ).  
     
     
         11 . The sealing/parting knife as set forth in  claim 9 , wherein said sealing/parting blade ( 36 ) together with said contact surface area ( 34 ) forms a constricting intake gap ( 37 ).  
     
     
         12 . The sealing/parting knife as set forth in  claim 9 , wherein said contact surface area is between 2 mm and 4 mm wide and 50 mm to 100 mm long.  
     
     
         13 . The sealing/parting knife as set forth in  claim 9  in which a heater ( 31 ) and a temperature sensor ( 32 ) are integrated.