METHOD AND DEVICE FOR CONTINUOUS TWO-AXIS STRETCHING OF FILM BASED ON TRANSITION THROUGH SADDLE-SHAPED SURFACE

摘要

The present invention discloses a method and device of film stepless biaxial tension based on saddle-shaped surface transition. In the film surface biaxial stretching process, with the lateral and longitudinal tensile forces applied to a different tangent plane, the film is subjected to smooth transition in a three-dimensional space from a narrow plane via a saddle-shaped surface to a wide plane, with the thickness uniformity of the biaxial tension film regulated by controlling the shape of the saddle-shaped surface; the device comprises a herringbone wheel unit and a parallel wheel unit, the angle between the two lateral tension wheels in the herringbone wheel unit being adjustable, the two longitudinal tension wheels in the parallel wheel unit being arranged in parallel; the lateral tension of the film is achieved by the rotation of the lateral tension wheel, and the longitudinal tension of the film is achieved by the linear velocity difference between the lateral tension wheel and the longitudinal tension wheel. The present invention, adopting the binding wheel structure, effectively uses the saddle-shaped surface to regulate the bowing phenomenon, and reduces the contact surface between the film and the tension element, thus preventing the surface performance from deteriorating by friction, which is advantageous for improving the thickness uniformity of the film product.