Rotary Die Board

Abstract

An arcuate die board formed as a multi-layered paperboard structure. The die board is initially produced as a full cylindrical paperboard tube, which is subsequently cut lengthwise to form two or more part-cylindrical portions each of which is used to fabricate a die board. The die board is then cut to form the slots in its outer surface for mounting die tools. The multi-layered paperboard tube can be spirally wound, convolutely wound, or formed by a linear draw process. The part-cylindrical wall is formed predominantly, substantially entirely, or entirely of paperboard plies adhesively laminated together.

1 . A die board for a rotary die, comprising:
 an arcuate part-cylindrical wall having an outer part-cylindrical surface and an inner part-cylindrical surface; and   wherein the part-cylindrical wall is formed at least predominantly of a plurality of paperboard plies adhesively laminated together.   
     
     
         2 . The die board of  claim 1 , further comprising a plurality of slots formed in the outer part-cylindrical surface of the wall for receiving die tools. 
     
     
         3 . The die board of  claim 1 , wherein the part-cylindrical wall is formed substantially entirely of a plurality of paperboard plies adhesively laminated together. 
     
     
         4 . The die board of  claim 1 , wherein the inner part-cylindrical surface has a diameter of approximately 482 to 489 mm. 
     
     
         5 . The die board of  claim 4 , wherein the part-cylindrical wall has a thickness of approximately 12.6 to 13.3 mm. 
     
     
         6 . The die board of  claim 1 , wherein the plurality of paperboard plies include paperboard plies of at least two different types. 
     
     
         7 . The die board of  claim 1 , wherein an outermost ply of the die board is substantially thinner than at least some of the other plies. 
     
     
         8 . The die board of  claim 1 , wherein the plies include at least a first moisture-barrier ply. 
     
     
         9 . The die board of  claim 8 , wherein the first moisture-barrier ply comprises a laminate of at least one paper layer and at least one substantially moisture-impervious layer. 
     
     
         10 . The die board of  claim 8 , wherein the first moisture-barrier ply is proximate a radially outer surface of the die board. 
     
     
         11 . The die board of  claim 10 , further comprising a second moisture-barrier ply proximate the radially outer surface of the die board. 
     
     
         12 . The die board of  claim 9 , wherein the first moisture-barrier ply is proximate a radially inner surface of the die board. 
     
     
         13 . The die board of  claim 12 , further comprising a second moisture-barrier ply proximate a radially outer surface of the die board. 
     
     
         14 . The die board of  claim 13 , further comprising a third moisture-barrier ply located radially inwardly of the first and second moisture-barrier plies. 
     
     
         15 . The die board of  claim 13 , wherein there is a substantially greater number of paperboard plies than moisture-barrier plies. 
     
     
         16 . The die board of  claim 1 , comprising approximately 15 to 25 paperboard plies ranging in thickness from about 0.01 inch to about 0.03 inch, the die board having a wall thickness of about 0.4 to 0.6 inch. 
     
     
         17 . A method for making die boards for a rotary die, comprising the steps of:
 wrapping a plurality plies, predominantly made up of a plurality of paperboard plies, one atop another about a cylindrical mandrel and adhering the plies to one another to form a hollow predominantly paperboard tube on the mandrel;   removing the tube from the mandrel; and   cutting the tube lengthwise to form at least two part-cylindrical portions each formed by a part-cylindrical wall having a part-cylindrical inner surface and a part-cylindrical outer surface.   
     
     
         18 . The method of  claim 17 , further comprising the step of:
 forming a pattern of slots in the part-cylindrical outer surface of each of the part-cylindrical portions, the slots being configured to hold die tools.   
     
     
         19 . The method of  claim 17 , wherein the wrapping step comprises helically wrapping the plies about the cylindrical mandrel. 
     
     
         20 . The method of  claim 17 , wherein the wrapping step comprises wrapping plies of at least two different types. 
     
     
         21 . The method of  claim 17 , wherein the wrapping step includes wrapping at least one moisture-barrier ply. 
     
     
         22 . The method of  claim 17 , wherein the wrapping step includes wrapping at least one moisture-barrier ply in the form of a laminate having at least one paper layer and at least one substantially moisture-impervious layer. 
     
     
         23 . The method of  claim 22 , wherein the wrapping step includes wrapping at least two of said moisture-barrier plies each in the form of said laminate. 
     
     
         24 . The method of  claim 17 , wherein the wrapping step includes wrapping a plurality of paperboard plies having a moisture content not greater than about 4%. 
     
     
         25 . The method of  claim 24 , wherein the wrapping step further comprises wrapping at least one moisture-barrier ply in the form of a laminate having at least one paper layer and at least one substantially moisture-impervious layer.