US Patent 7575109 Rotary damper and method for manufacturing rotary damper

Described is a rotary damper comprising a partition wall to partition space formed between a rotor and a housing to house said rotor and to form a fluid chamber to be fluid-filled; and a vane to be disposed in said fluid chamber; and a plug to close an opening of said housing; wherein said plug has a flange to be used for mounting which protrudes from an outer circumferential surface of said plug and a stepped portion to enable part of a roller caulking an edge of said opening of said housing to revolve and travel along a peripheral edge of said housing so that said plug having said flange is coupled to said housing by caulking an edge of said opening of said housing.