Improvements in and relating to the manufacture of flexible bands, foils or tubes

摘要

The method of the parent Specification for producing bands and foils of polymerization products of aryl olefines or similar brittle artificial substances such as polystyrol which are flexible and yielding in every direction according to which the artificial mass is squirted from a nozzle and the formed product subjected both to longitudinal and transverse stretching is applied to tubular extrusion, the artificial material being extruded from an annular nozzle and thereupon longitudinally tensioned and transversely stretched by drawing, at a greater speed than the speed of extrusion, over a spreading device provided on the centre piece of the nozzle, or inside a constraining member wherein it is inflated by compressed air. The artificial mass b in the press a is extruded at a raised temperature from the annular nozzle c, and the formed tube f is drawn over the two curved guides e at the middle part d of the nozzle. The outer sides of the curved guides are preferably provided with rollers g. The finished tube is drawn off by means of the rolling up device h. If desired, the tube may be cut at the sides to form two bands. The curve guides are rotatable, and their spread is regulable by the force of a spring device i. Preferably, the spreading arms have the form of a logarithmic curve. In a modification shown in Fig. 2, the flexible tube passes inside a constraining piece 5, and compressed air supplied by a passage 4 passing through the centre of the nozzle, expands the tube to stretch it transversely. After emerging from the member 5, the tube is pressed flat by two rubber rollers 7, and is then cut at the edges by a device 8 to produce two foils 9 which are rolled up on drums 10.