Printing roller

Claim 1

A printing roller comprising: a mandrel extending about a longitudinal axis and adapted to be mounted in a printing machine for rotation about said axis; a hollow cylinder slidably mounted on the mandrel and having inner and outer curved surfaces concentric with said mandrel axis; the mandrel comprising a support having a continuous cylindrical outer surface concentric with said axis and formed with a plurality of peripheral grooves spaced longitudinally of the support, and a plurality of resilient rings disposed in each of said grooves, said rings being radially expansible into frictional engagement with said inner surface of the cylinder so as to retain the cylinder against axial displacement with respect to the mandrel, and said support being formed with at least one air passageway communicating with each of said grooves inwardly of the ring therein; and one way air valve means accessible from externally of the roller and communicating with said air passageway so as to allow air to enter said passageway while preventing return flow of air therefrom, whereby the air in said passageway can be pressurized to cause outward radial expansion of said rings into frictional engagement with said cylinder; and wherein each of said grooves in the support includes: an annular outer portion of generally truncated triangular shape receiving said ring; an intermediate annular portion disposed inwardly of said outer portion and receiving an annular band disposed inwardly of said ring; and an annular inner portion disposed inwardly of said band and communicating with said air passageway, whereby pressurized air in said passageway is distributed substantially uniformly in said inner portion of the groove and acts on said ring by way of said band, so as to expand the ring substantially concentrically with the axis of the roller in use.