| 摘要 |
PROBLEM TO BE SOLVED: To provide a prestress device that can apply appropriate prestress even when changing intervals of housings and reduce the diameter of a prestress rod, a stand expanding/shrinking mill comprising the same and a method for applying prestress using the same.SOLUTION: A prestress device 13 is used for a stand expanding/shrinking mill 10, and comprises a cylinder casing 19, a piston 20 which can be slid in an axial direction in the cylinder casing 19, a prestress rod 21 which has a head part 28 inserted into the piston 20 and applies prestress between housings 11 and 12 and a spacer 22. The head part 28 has a protruding part 29 protruding in a radial direction. The piston 20 has a plurality of boss parts 36 and 37 provided separately in an axial direction therein. In the plurality of boss parts 36 and 37 are formed recessed parts 40 and 41 for passing the head part 28 therethrough at a predetermined passing angle. |
