| 摘要 |
1,166,954. Extruding foamed plastics. G. G. SMALL. 6 Oct., 1967 [8 March, 1967], No. 10987/67. Heading B5A. [Also in Division E1] In a method of forming a solid, tongued and grooved board wholly of expanded plastics material, powdered plastics material and a blowing agent introduced into a heated extruder are extruded as a viscous plastics material through a hot die, this extrudate being cooled in a cooled former which is so shaped as to form on the extrudate the tongue and groove profile. The cooled former may be provided with vacuum suction arrangements whereby the cooling contractions of the material are counteracted. Modifications to the shape of the extrudate in addition to the tongue and groove formations may be imparted by the cooled former. Alternative cross-sections of the board are described with reference to Figs. 5, 6 and 7 (not shown). |
