| 摘要 |
1,159,561. Extruding foamed thermoplastics. T. W. WINSTEAD. 26 July, 1966 [29 July, 1965], No. 33523/66. Heading B5H. Foamed thermoplastics sheeting S is produced by passage of material through a fanshaped reservoir 22, Fig. 1, an arcuate extrusion orifice 22a and over an arcuate support 27, such passage allowing lateral expansion of the material. Support 27 may be a tube through which a cooling fluid is passed and may be coated with PTFE to reduce friction. It is adjustably mounted on a column 29 and is vertically reciprocable by rotation of a screw 32 and rotatable about a bolt 34. Reservoir 22 is principally formed by an adaptor 20, Fig. 2, seated in end cap 16, and a die-plate 14 which is flexible and adjustable to alter the orifice width on rotation of screw 14a. A valve 36 is provided to divert material from reservoir 22, e.g. during change of adaptor 20 and a spacer 26. Band heaters 39, 40 are provided. It is preferred to draw sheet S away from support 27 in a direction between 90 and 180 degrees to the direction of extrusion between orifice 22a and the support. Specific thermoplastics mentioned are PVC, polystyrene, polyethylene and polypropylene. |
