| 摘要 |
PURPOSE:To reduce the number of work processes by making it possible to mold a platen roller main body so as to make the diameters of the end surface part and central part thereof the same, by providing a step part, which reduces the diameter of the platen roller main body on the side of each of the end surface parts thereof, on the core metal of said main body at the position in the vicinity of each of the end surface parts thereof. CONSTITUTION:A platen roller is composed of a platen roller main body 1 and a core metal 2 provided with step parts, and the interior thereof is composed of a low density core layer 1a and the surface part thereof is composed of a high density skin layer 1b and each of the step parts is calculated on the basis of formulae l= lA-lB...(1), lAXalpha=lBXbeta...(2) (wherein lA is the thickness of each end surface part 3, lB is the thickness of a central part, alphais the molding shrinkage ratio of the end surface part and beta is the molding shrinkage ratio of the central part). By this method, the molding shrinkage quantity (=shrinkage ratio X wall thickness) of the end surface part 3 of the platen roller and that of the central part thereof can be made uniform and the outer diameter dimension of the platen roller can be restricted within a tolerant value. |
