| 摘要 |
PROBLEM TO BE SOLVED: To maintain always specific spring characteristics while yielding of the spring is little by a method wherein a resin spring is manufactured by releasing preliminary compression after applying the preliminary compression to crystalline thermoplastic resin, a recessed part is preliminarily formed before preliminary compression, to a part which is especially largely deformed in compression. SOLUTION: A cylindrical resin material 1 composed of polyester elastomer being crystallin thermoplastic resin is annealed after molding in a mold, a peripheral wall 3 is formed with a through hole 3 passing vertically through an inside, and an almost cylindrical shape is formed. Though an outer shape of the cylindrical resin material 1 is uniform over in an axial direction, an inner diameter of the throughhole 2 is gradually increased from upper and lower opening ends toward a center, and a recessed part 4 of an axial central part wherein a central part expands is formed. When preliminary compression is carried out by applying specific compression force axially, stress is concentrated to an axial central part, the cylindrical resin material 1 is deformed flatly, the axial central part is largely bent, and then though released by unfastening press, the resin spring which is deformed in almost such the shape is obtained as it is. |
