| 摘要 |
PROBLEM TO BE SOLVED: To prevent a resin product from being deformed with the passage of time by forming a loose part in advance at a position at which the tensile stress of a sheet-shaped raw material converges when the raw material is pushed to a molding surface. SOLUTION: A protrusion part 2b, a hollow loose part having a circular cross section, which pushes a shaft body 5 of a circular cross section and protrudes toward the molding surface 3a of a mold 3 is formed in the middle 2a of a raw material 2 on which tensile stress converges during molding. The raw material 2 is pushed to the molding surface 3a of the mold 3 to crush the peripheral wall part of the protrusion part 2b, compression stress is made to act on its inside, and simultaneously tensile stress is made to act on the peripheral wall part of the protrusion part 2b to cancel each other. Therefore, no stress remains in the middle 2a of the raw material 2, preventing a resin product from being deformed with the passage of time.
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