Injection molding manner and its die null of molding box material for concrete structure

摘要

PROBLEM TO BE SOLVED: To obtain a mold frame being lightweight, moreover, capable of withstanding the use of nails, and also being cut by a common saw by forming it with a skin layer at its surface and synthetic resin being the same skin layer as the foamed porous skin layer in its inner part. SOLUTION: Molten resin filling the cavity part 10 is cooled on each surface of a stationary side mold plate 7 and slide core 15 facing the cavity part 10 and forms thin skin layers 40a, 40b. After molten resin fills the cavity part 10 to form a skin layer, compressed air is introduced into a cylinder, and an inner layer 41 held between the skin layer 40a and the skin layer 40b is formed with larger air holes than the ordinary air foam by withdrawing of the slide core 15. After the completion of sufficient foaming, by slightly moving the slide core in the direction of compressing the sliding core 15 again, the volume in the cavity part 10 is compressed so as to cancel the internal distortion and allow it to foam equally.