| 摘要 |
1529370 Sizing stress-free extrudates DYNAMIT NOBEL AG 16 Dec 1975 [1 Feb 1975] 51503/75 Heading B5A A tubular thermoplastics extrudate 7, e.g. of rigid P.V.C., is sized in being drawn from an extrusion die through a sizing die with minimized axial stretching and consequential latent stresses, by externally cooling the extrudate in the entry region to the die, to a greater extent at peripherally spaced apart locations of the extrudate than at intermediate locations, so that the spaced apart locations act as reinforcements against stretching. In the embodiment, the extrudate 7 comprises a plurality of bores 7a-7d and projecting lugs 71, 72, and is cooled to the greater extent adjacent the lugs 71, 72 by water circulated through recesses 11 in the sizing wall of the die, via inlet passages 5a, 5b, 11 and vacuum slots 12 which draw the water through the recesses in the same direction as the extrudate. |
