Movable U-bar sealing device and a method for shrink wrapping a load with a flexible material

Abstract

The present invention comprises a movable, heated U-bar sealing device for a shrink wrap apparatus and a method for rapidly and continuously shrink wrapping a load with a flexible material such as a film. The movable, heated U-bar moves with the load as it seals the corners of the load with a film without creating multiple layers of film on the corners of the load.

1 . A movable, heated U-bar sealing device comprising: 
 (a) a heated cross-sealing bar,    (b) a perpendicular first heated side sealing bar having two ends, a proximate end and a distal end, the proximate end is in contact with the heated cross-sealing bar and is facing a conveyor device,    (c) said perpendicular first-heated side sealing bar having two sides, an inner side and an outer side, the inner side facing the conveyor device,    (d) a second perpendicular heated side sealing bar having two ends, a proximate end and a distal end, the proximate end is in contact with the heated cross-sealing bar and is facing the conveyor device,    (e) said first perpendicular heated side sealing bar having two sides, an inner side and an outer side, the inner side facing the conveyor device,    (f) said first perpendicular heated side sealing bar comprising a bar having two ends, a curved bracket end and a distal end wherein the first curved bracket end is joined with said heated cross-sealing bar and is facing the conveyor device, and    (g) the second perpendicular heated side sealing bar comprising a bar having two ends, a second curved bracket end and a distal end, wherever the second curved bracket end is joined with said heated cross-sealing bar and is facing the conveyor device.    
   
   
       2 . The movable, heated U-bar sealing device of  claim 1  wherein the heated cross-sealing bar and the two perpendicular heated side sealing bars are operationally programmed to move back and forth with the direction of a load to provide a uniform high-speed seal of the load.  
   
   
       3 . The movable, heated U-bar sealing device of  claim 2  wherein said U-bar sealing device adjusts to the peripheral side of the load.  
   
   
       4 . The movable, heated U-bar sealing device of  claim 1  wherein the temperature of the movable, heated U-bar sealing device is in the range of 200 to 600 degrees Fahrenheit.  
   
   
       5 . The movable, heated U-bar sealing device of  claim 1  wherein the temperature is in the range of 350 to 375 degrees Fahrenheit.  
   
   
       6 . The movable, heated U-bar sealing device of  claim 1  wherein a plurality of film rolls are provided and are welded together to form a curtain.  
   
   
       7 . The movable, heated U-bar sealing device of  claim 1  wherein a shrink tunnel is provided for shrinking film on a load at elevated temperatures.  
   
   
       8 . The movable, heated U-bar sealing device of  claim 7  wherein said shrink tunnel temperature is in the range of 200 to 600 degrees Fahrenheit.  
   
   
       9 . The movable, heated U-bar sealing device of  claim 7  wherein said shrink tunnel temperature is in the range of 350 to 375 degrees Fahrenheit.  
   
   
       10 . The movable, heated U-bar sealing device of  claim 6  wherein the film has a thickness in the range of 1.5 to 18 mils.  
   
   
       11 . The movable, heated U-bar sealing device of  claim 6  wherein the film has a thickness in the range of 1.5 to 6 mils.  
   
   
       12 . The movable, heated U-bar sealing device of  claim 6  wherein the film is a polyolefin.  
   
   
       13 . The movable, heated U-bar sealing device of  claim 12  wherein the film is polyethylene.  
   
   
       14 . The movable, heated U-bar sealing device of  claim 1  wherein an air circulating system after the shrink wrap tunnel cools the shrink wrapped film.  
   
   
       15 . A high-speed continuous method for wrapping and binding a load with a flexible film, said process comprising: 
 (a) feeding the film from a plurality of sources to a curtain welding device,    (b) welding together the film from the plurality of sources to form a film curtain,    (c) passing the load through the film curtain and covering the load with the film curtain,    (d) spreading the film curtain over the load prior to sealing and avoiding bunching of the film curtain at the corners of the load,    (e) sealing the film curtain to the load at a temperature of about 200 to 600 degrees Fahrenheit, and    (f) shrink wrapping the film curtain to the load at a temperature in the range of 200 to 600 degrees Fahrenheit.    
   
   
       16 . The method of  claim 15  wherein the sealing and shrink wrapping of the film curtain to the load is conducted at a temperature of about 350 to 375 degrees Fahrenheit.  
   
   
       17 . The process of  claim 15  wherein the film is a polyolefin.  
   
   
       18 . The process of  claim 15  wherein the film is polyethylene.