To provide an extrusion die for manufacturing a tube with many small hollow portions capable of suppressing under fill in a partition wall and reducing the width in a hollow part.
An extrusion die 1 for manufacturing a tube with many small hollow portions includes a female die 30 for defining an outer periphery of a tube 100 and a mandrel 2 combined with the female die. The mandrel 2 includes a body portion 21 and a plurality of columnar portions 22 protruding in a comb-tooth shape from the body portion 21 and disposed in a width direction at certain intervals. An outer periphery of the tip end portion of the columnar portion constitutes a bearing portion 25 for defining an inner periphery of a plurality of hollow portions disposed in the width direction of the tube. On the rear side in the extrusion direction of the bearing part 25, at least one of outer surface on one side in the thickness direction of the columnar portion 22 is dented inwardly in the thickness direction of the position of the bearing portion 25, thereby forming a pocket portion 27 being a space for filling molding material on at least one side in the thickness direction of the columnar portion.
YAMAZAKI HIDEYO
SHIMIZU FUMIO
Hisayoshi Shimizu
Ken Takada
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