| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive lightweight bumper core material and an easy manufacturing method for the bumper core material by arranging through holes penetrating in the bumper core material longitudinally in a boundary part between an energy absorbing part and a molding part. SOLUTION: A bumper core material 1 is formed of a polyolefinic resin foam granular molding body, in which an energy absorbing part 2 and a molding part 3 are integrally formed. In a boundary part 4 between the energy absorbing part 2 and the molding part 3, through holes 5 are arranged. The through holes 5 positioned between the energy absorbing part 2 and the formation part 3 penetrate the bumper core material 1 in the longitudinal direction. In a molding die, a partition plate separating the boundary between a cavity forming the molding part and a cavity forming the energy absorbing part is divided into a plurality of pieces in the width direction, so that a mold member is arranged between the divided partition plates and molding can be carried out while preventing the respective partition plates from mutual contact. Therefore, the inexpensive lightweight bumper core material 1 can be produced with stable quality by means of simple equipment.
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