GB540747A - Improvements in or relating to the manufacture of tubular film-like bodies - Google Patents

Abstract

540,747. Tubular films. HEAVEN, H. S. April 26, 1940, No. 7569. [Class 2 (ii)] Tubular films, e.g. sausage casings are formed by extruding a cellulosic solution such as viscose from an annular die into contact with a setting liquid, passing the film in a partly set condition over a mandrel adjustable in respect of shape and of position in the apparatus and thereafter subjecting it, while still in the partly set condition, to regulated inflation by the controlled admission or removal of fluid to or from the interior thereof ; the fluid may be admitted and removed. The inflation may be maintained until the tubular film has been set substantially completely, the setting liquid, which for viscose solution may be an aqueous solution of ammonium sulphate, may be supplied to the interior of the tubular film between the die and the mandrel, the mandrel may be expansible and adjustable to regulate the diameter of the tubular film, and the diameter of the mandrel is preferably somewhat greater than the diameter of the die orifice. As shown the cellulosic solution is supplied through a pipe 15 to the annular orifice 14 of the die 13 disposed in the setting solution 12 and the tubular core 20 of the mandrel is slidably and adjustably mounted in the inner tube 18 of the die and carries the expansible member 21 formed of inflatable rubber or other flexible material bound to the core by clips 22, 23. Water is supplied from a pipe 24 to the inside of the member 21 to expand it, setting solution is supplied to the space between the inner lip of the orifice 14 and the member 21 through a pipe 25 and conduits 26, 27 and a pipe 28 passing through the core 20 and terminating above the level of the setting liquid is connected through a two-way cock 29 with an air pressure pipe 30 and an exhaust or vacuum pipe 31. The setting liquid supplied through the pipe 25 is maintained under a pressure slightly greater than that of the surrounding bath so that the extruded tube 32 is stretched while it is being set and guided on to the member 21 the inflation of which is adjusted to stretch the tube the desired extent; the end of the tube as it leaves the Member 21 is sealed and the tube is inflated by air supplied through the pipe 30 until the gases evolved-in the tube during the process attain sufficient pressure, when the cock is turned to bring the pipe 28 into communication with the pipe 31. The tube 32 passes from the member 21 in a slightly inclined upward direction, through the regenerating and washing apparatus, to a pair of nip rollers which draw the tube through the apparatus. The core may be made of glass or stainless steel. Specification 408,774 is referred to.