Roll product and winding method

Abstract

An improved roll product is proposed in which a long strip of film or sheet is wound on a core without using a conventional paper tube. The core used can be discarded without difficulty. The core is formed by bending a flat board of cardboard into a cylindrical shape. The side edges of the flat board may be spaced apart, butted together or overlapped. The side edges may or may not be joined together. The end of the film gets caught between the side edges of the flat board. This arrangement allows the film wound to be used up to the last inch while applying a tension thereto and without breakage of the core or winding displacement. A cap may be fitted into both ends of the core to increase the shape retainability of the core.

What is claimed is:  
     
         1 . A roll product formed by winding a long strip of sheet or film on a core, characterized in that said core is formed by bending a flat board into a cylindrical shape, said core being made of a material which can be developed into a flat board after use.  
     
     
         2 . A roll product as claimed in  claim 1  wherein said flat board has its side edges joined together after bending.  
     
     
         3 . A roll product as claimed in  claim 1  wherein said core is formed with a gap provided between side edges of said flat board after bending.  
     
     
         4 . A roll product as claimed in  claim 1  wherein said core is formed with side edges of said flat board overlapping each other after bending.  
     
     
         5 . A roll product as claimed in  claim 1  wherein said core is formed with side edges of said flat board abutting each other after bending.  
     
     
         6 . A roll product as claimed in  claim 1 ,  3  or  4  wherein the end portion of said film or sheet is caught into said core through between side edges of said bent flat board.  
     
     
         7 . A roll product as claimed in any of claims  1 - 6  wherein said flat board is formed of cardboard.  
     
     
         8 . A roll product as claimed in any of claims  1 - 7  wherein the film is a stretch film and wherein the film is wound with the tension to the film during winding restricted such that when a cut having a depth of 10 mm is formed in the surface of the wound film roll over the entire width, the width of widening of said cut caused due to residual stress in the stretch film will be 5 mm or less.  
     
     
         9 . A roll product as claimed in any of claims  1 - 8  wherein caps each having a fitting portion and a flange portion are fitted in both ends of said core.  
     
     
         10 . A roll product as claimed in  claim 9  wherein both ends of said core protrude from both ends of said wound sheet or film.  
     
     
         11 . A roll product as claimed in any of claims  1 - 10  wherein a plurality of said flat boards are used to form said core.  
     
     
         12 . A method of winding a long strip of sheet or film into a roll product, comprising the steps of placing a flat board along a mandrel of a winding machine, bending said flat board with a gap present between side edges of said flat board to form a core, and winding said sheet or film on said core with its end portion fastened to said core.  
     
     
         13 . A method of winding a long strip of sheet or film into a roll product, comprising the steps of placing a flat board along the outer periphery of a mandrel of a winding machine, bending said flat board with its side edges abutting each other to form a core, and winding said sheet or film on said core with its end portion fastened to said core.  
     
     
         14 . A method of winding a long strip of sheet or film into a roll product, comprising the steps of placing an end portion of said sheet or film on the outer periphery of a mandrel of a winding machine, feeding a flat board to the inner side of said sheet or film so as to contact the outer peripheral surface of said mandrel to simultaneously wind said flat board and said sheet or film, bending said flat board into a cylindrical shape to form a core, and getting one end of the sheet or film caught into said core through between side edges of the bent flat board.