Cutting device

Claim 1

In a cutting device of the type having rotary vane knives which cooperate with stationary knives, for making patterned cuts in the longitudinal edges of a paper web fed therepast, for the preparation of envelopes or envelope blanks, the improvement comprising: at least one cooperating knife pair, including one rotary knife made of an aluminium alloy and one stationary knife made of hardened steel, disposed for cooperative engagement, for making patterned cuts in the edges of paper webs moving therepast, said blades being made of materials differing from one another in hardness to an extent such that the softer knife can have material removed from it without damage to the latter, and at least one of the knives of said cooperating knife pair being mounted for feeding movement toward its associated cooperating knife, while the cutting device is operated, said knife which makes the infeeding movement, being mounted on a frame pivotable around a pivot, which pivot is positioned such that, irrespective of its infeed, the rotary knife, when in the cutting position, always takes up the same angular position relative to the paper web fed therepast.