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.

1 . An inner sleeve for a flat extrusion cylinder comprising an inner sleeve ring piece, an upper insert piece and a lower insert piece;
 wherein the inner sleeve ring piece is disposed in an intermediate sleeve of the flat extrusion cylinder, and   wherein 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.   
     
     
         2 . The inner sleeve for the flat extrusion cylinder according to  claim 1 , wherein each of the upper insert piece and the lower insert piece has crescent-shaped cross-section, and an arc surface of crescent-shaped cross-section matches with an arc surface of the inner sleeve ring piece. 
     
     
         3 . The inner sleeve for the flat extrusion cylinder according to  claim 1 , further comprising at least two countersunk head bolts configured to fix the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece. 
     
     
         4 . The inner sleeve for the flat extrusion cylinder according to  claim 3 , wherein the number of the countersunk head bolts is two, that is, a first countersunk head bolt and a second countersunk head bolt, respectively,
 wherein the first countersunk head bolt is configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and   wherein the second countersunk head bolt is configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.   
     
     
         5 . The inner sleeve for the flat extrusion cylinder according to  claim 3 , wherein the number of the countersunk head bolts is four,
 wherein two of the countersunk head bolts are configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and the other two of the countersunk head bolts are configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.   
     
     
         6 . The inner sleeve for the flat extrusion cylinder according to  claim 1 , wherein the inner sleeve ring piece is made by forging process. 
     
     
         7 . The inner sleeve for the flat extrusion cylinder according to  claim 6 , wherein a blank of the inner sleeve ring piece is forged by hole-enlarging shaping process or annular rolling process, so that metal streamline of the inner sleeve ring piece is regularly distributed in a circumferential direction. 
     
     
         8 . A flat extrusion cylinder comprising an intermediate sleeve and an outer sleeve,
 wherein the intermediate sleeve is disposed within the outer sleeve,   wherein the flat extrusion cylinder further comprises the inner sleeve as claimed in  claim 1 , and   wherein the inner sleeve is disposed within the intermediate sleeve.   
     
     
         9 . The flat extrusion cylinder according to  claim 8 , wherein each of the upper insert piece and the lower insert piece has crescent-shaped cross-section, and an arc surface of crescent-shaped cross-section matches with an arc surface of the inner sleeve ring piece. 
     
     
         10 . The flat extrusion cylinder according to  claim 8 , further comprising at least two countersunk head bolts configured to fix the upper insert piece and the lower insert piece on the inner wall of the inner sleeve ring piece. 
     
     
         11 . The flat extrusion cylinder according to  claim 10 , wherein the number of the countersunk head bolts is two, that is, a first countersunk head bolt and a second countersunk head bolt, respectively,
 wherein the first countersunk head bolt is configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and   wherein the second countersunk head bolt is configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.   
     
     
         12 . The flat extrusion cylinder according to  claim 10 , wherein the number of the countersunk head bolts is four,
 wherein two of the countersunk head bolts are configured to fix the upper insert piece on the inner wall of the inner sleeve ring piece, and the other two of the countersunk head bolts are configured to fix the lower insert piece on the inner wall of the inner sleeve ring piece.   
     
     
         13 . The flat extrusion cylinder according to  claim 8 , wherein the inner sleeve ring piece is made by forging process. 
     
     
         14 . The flat extrusion cylinder according to  claim 13 , wherein a blank of the inner sleeve ring piece is forged by hole-enlarging shaping process or annular rolling process, so that metal streamline of the inner sleeve ring piece is regularly distributed in a circumferential direction.