| 摘要 |
PURPOSE:To inexpensively control a foaming thereby to manufacture a foamed product having a preferable skin layer by foaming a foamable material by a frictional heat generated when the material passes an injection nozzle. CONSTITUTION:A foamable material is charged in a cylinder 11. When the material is introduced to the midway of a passage 17 of a nozzle tip 15, a screw 12 is moved forward, and the material of the quantity responsive to the forward stroke is injected. When the material passes very narrow second passage 17b, a frictional heat is generated, and it raises to a foaming temperature or higher. As a result, the material is foamed in the passage 17b of the tip 15. Since it is high pressure, foams are small. The foamed material is introduced into a cavity 27 at a high speed, cooled and solidified. Since the material becomes low pressure in the cavity 27, the foaming is reactivated to enlarge the foams. Thus, a foamed product 42 composed of a skin layer 44 having small foams and a cushion layer 43 having large foams is obtained. |
