Inner sleeve for a flat extrusion cylinder and a flat extrusion cylinder

Abstract

An inner sleeve for a flat extrusion cylinder includes an inner sleeve ring piece, an upper insert piece and a lower insert piece. The inner sleeve ring piece is positioned in an intermediate sleeve of the flat extrusion cylinder. The upper insert piece and the lower insert piece are symmetrically disposed on an inner wall of the inner sleeve ring piece to form an inner sleeve working die cavity of the flat extrusion cylinder. Arc surfaces of two insert pieces match with the arc inner wall of the inner sleeve ring piece, so as to improve the stress distribution at interface portions between the flat surface and the arc surface of the inner sleeve working die cavity. When the flat extrusion cylinder is operated, the insert pieces will make a minor displacement in upward and downward direction due to the pressure from the inner sleeve working die cavity, such that the inner sleeve ring piece is elastically deformed in a circumferential direction, thereby generating a resisting force against the peak stress in the cylinder. In the flat extrusion cylinder according to the present invention, concentrated internal stress is uniformly transmitted to the inner sleeve ring piece, which decreases the peak stress in dangerous sections and achieves cylinder-type stress distribution in the flat extrusion cylinder. Thus, the stress received by the inner sleeve ring piece is distributed uniformly, thereby increasing the lifespan of the entire flat extrusion cylinder.

Dependencies are inferred from the claim text.