Rotary die cutting

Cylindrical dies which when rotating cut along a predetermined line of severance in a web of material which comprise:

• a pair of coacting dies cylinders of metal constructed and arranged to be journaled for rotation, at least one pair of coacting elongate severing blades with each blade of said pair disposed on one of said die cylinders, each severing blade comprising an elongate land projecting generally radially outwardly from the main body of its associated die cylinder, each said elongate land having an outer face and spaced apart and generally depending side faces defining a pair of spaced apart edges, said outer face having a width between said spaced apart edges of at least 0.010 of an inch, at least the portion of said side faces adjacent said outer face of each land of each severing blade being inclined toward each other at an acute included angle and each inclined to its associated outer face at an obtuse included angle, and said coacting severing blades of each pair being constructed, arranged and positioned on their respective die cylinders such that during corotation of said pair of die cylinders the immediately adjacent edges of said coacting severing blades of each pair cut the web therebetween along a predetermined line of severance while the other edges of said coacting severing blades are on generally opposite sides of such line of severance, the line of severance in the web being a closed figure, and at least two pair of coacting crossovers each in one of said lands of said pair of severing blades, each said crossover section having a narrow segment of said outer face with a maximum width of less than one-fourth of the maximum width of adjacent portions of said outer face of its land, said narrow segment of said outer face lying immediately adjacent the line of severance and extending at least to the point where the cutting action of said coacting severing blades transfers over from one edge to the other edge of said lands of said severing blades, whereby a pair of die cylinders can be shifted generally axially with respect to each other and/or shifted in rotational phase relationship with respect to each other such that an appropriate relationship between all of the severing blades thereof can be maintained for cutting the web along the predetermined line of severance.