Abstract: The present invention relates to a method of and an apparatus for manufacturing biaxially oriented film. A tubular original film which has been extruded by an extruding die is biaxially oriented by heat and air injected to the inside portion thereof being conveyed to nip rolls each having an individual circumferential speed. The temperature of heat to be applied to the film is controlled on the basis of the detected film thickness for the purpose of obtaining a uniform film thickness distribution. Furthermore, the film can be made uniform by adjusting the outer diameter of the bubble-shaped oriented film by adjusting the distance between two sets of nip rolls on the basis of the measured width of the film. In addition, when the thus-oriented film is subjected to a heat treatment, temperature of heat is arranged to be a predetermined temperature as to prevent adhesion of the films.

Abstract: The present invention relates to a method and an apparatus for tubularly drawing a tubular raw material of thermoplastic resin. Gas for forming a bubble to heatingly draw the tubular raw material is injected into the raw material from a direction opposite to a direction for transferring the raw material through a nozzle. The raw material is cut into a plurality of web-like pieces by cutting blades provided on pinch rolls for taking up the raw material. One of the web-like pieces thus cut is separated from the others and formed with an opening into which the nozzle is inserted to inject the gas.

Abstract: A method of biaxially stretching a tubular thermoplastic resin to provide a film, wherein air is blown against a starting point for heating and stretching the tube, from the upstream side of the starting point, at a predetermined angle relative to the feeding direction of the film. An apparatus for achieving this method includes: two pairs of nip rolls being different in circumferential speed between the pairs; a heating-stretching section interposed between the pairs of nip rolls, for heating the tube to a temperature where the tube can be stretched; and an air ring device for blowing air in the feeding direction of the film.