| 摘要 |
PROBLEM TO BE SOLVED: To provide a mandrel that suppresses scars from occurring in a resin foamed sheet and suppresses stress strain occurring in the resin foamed sheet upon forming the resin foamed sheet using the mandrel.SOLUTION: The mandrel is disposed in front in the extruding direction of a circular die upon manufacturing the resin foamed sheet. At an end disposed on the circular die side, a diameter increased region with which a cylindrical body is increased in diameter is formed, and an irregular structure is formed in the diameter increased region by a plurality of minute projections C. Each minute projection C is formed to include a flat surface part C2 and/or a curved surface part C1 each having a radius of 0.2 mm or more at a tip end in the projecting direction. A distance LD between tip ends in the projecting direction of adjacent minute projections C is 0.2-2.0 mm. |
