Rotary knife holder with means for damping its natural frequency oscillations

A knife holder, particularly for use in apparatus for subdividing a running web of paper or the like into discrete sheets, comprising a hollow rotary carrier which tends to oscillate at a given natural frequency, said carrier having an axial passage, at least one peripheral recess extending in substantial parallelism with the axis thereof, and at least one knife, a portion of which extends into and is retained within said at least one peripheral recess;

• means for damping the oscillations of said carrier, including a dynamic damping unit disposed in the passage of said carrier and having a natural frequency which is attuned to said given frequency, said unit comprising a mass and means for coupling said mass to said carrier so that the mass is free to oscillate relative to said carrier, said mass comprising a cylinder and said coupling means comprising a plurality of elastic elements interposed between said cylinder and said carrier, said coupling means further comprising a sleeve coaxial with and installed in the interior of said carrier, said cylinder being installed in, being normally coaxial with and being freely oscillatable relative to said sleeve and said elastic elements being interposed between said sleeve and said cylinder.