To manufacture an inner box of a heat insulating box body of high quality by using a mold more inexpensive in comparison with a mold for vacuum molding to manufacture the inner box, without affected by dimension accuracy as a result, while suppressing leakage of a heat insulating material from the inner box.
An inner box 12 is formed by combining a plurality of foam bodies of prescribed shape having foam skin layers 12a as resin layers on surface sections, by at least thermal welding out of adhesion and thermal welding, then a heat insulating layer 13 is formed by carrying out a foam heat insulating material injection step, and a prescribed shape formation step by thermal molding which needs dimension accuracy, is carried out, or a flat heat insulating plate is used as an interlaid heat insulating layer 13A as a substitute for carrying-out of the foam heat insulating material injection step.
INUI HITOSHI
NAKANISHI YASUTETSU
Takaaki Yasumura
Takeshi Oshio
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