| 摘要 |
<p>1,223,968. Extruding foamed plastics. UGINE KUHLMANN. 25 March, 1969 [25 March, 1968], No. 15601/69. Addition to 1,184,688. Heading B5A. [Also in Division F2] The method of extruding foamed plastics rods or tubes as described in parent Specification is modified by the provision of apparatus having a further annular die orifice 216 so that a sheath of non-cellular material may be formed about a solid or hollow core of foamed plastics, the foaming which occurs within cooled sizing die 202 being radially inward, as described in the abovementioned Specification, by an amount dependent on the extrusion conditions. Mandrel 218 is provided with an axial bore through which a solid core 240, e.g. of metal, may be passed to reinforce the extruded product, see Fig. 3 (not reproduced). Die 206 is radially adjustable and heaters 229 and 245 are provided, the latter being shielded from member 210 by insulation 244. The embodiment described with reference to Fig. 1 (not shown), is the same as that described in Specification 1,184,688 except for the provision of a further annular orifice (116). In examples are described the production of a cylindrical rod having a sheath of polyethylene about a foamed polystyrene core, a cylindrical rod having a sheath of polymethyl methacrylate about a foamed P.V.C. core and a rectangular cross-sectioned bar having a sheath of polypropylene about a composite core of aluminium covered with foamed acrylonitrile - butadiene - styrene.</p> |
