Mandrel for printing apparatus, printing cylinder and printing apparatus

A mandrel for use in a printing apparatus, the mandrel comprising:

• a substantially cylindrical mandrel shaft extending along a mandrel shaft axis;
• a plurality of expansion rings slidably and coaxially mounted on the mandrel shaft, wherein the each expansion ring is radially outwardly expanded when axially compressed;
• a locking assembly, comprising:
• a stop ring that has an axially fixed position on the mandrel shaft adjacent a first end of the mandrel shaft;
• and
• a locking ring that is movably mounted on the mandrel shaft adjacent a second end of the mandrel shaft,
• wherein the expansion rings are mounted between the stop ring and the locking ring, and wherein the locking assembly has a locked position in which the locking ring is positioned closer to the stop ring than in an unlocked position, wherein in the locked position the expansion rings are in an axially compressed and radially expanded state, and wherein in the unlocked position the expansion rings are in a released state in which the axial compression and the radial expansion of the expansion rings are smaller than in the locked position, wherein the outer diameter of the expansion rings is larger in the locked position than in the unlocked position of the locking assembly, and wherein the locking assembly comprises a single stop ring and a single locking ring, and wherein the mandrel additionally includes:
• a plurality of spacer rings that are coaxially mounted on the mandrel shaft in between the expansion rings, such that the expansion rings are spatially separated from each other, wherein the outer diameter of the spacer rings is substantially equal to the outer diameter of the expansion rings in the released state,
• wherein the locking ring and the stop ring are substantially equidistant from a center plane that is positioned perpendicular to the mandrel shaft axis and intersects with the mandrel shaft, wherein the plurality of expansion rings is mounted substantially symmetrically with respect to the center plane, and wherein the expansion rings are made from plastic.