METHOD AND DEVICE FOR MANUFACTURING BIAXIALLY ORIENTED TUBING FROM THERMOPLASTIC MATERIAL

摘要

Method and device for manufacturing biaxially oriented tubing from thermopla stic material. The method comprises forcing the tube over a mandrel (3) at an orientation temperature of the plastic material, wh ich mandrel comprises an expansion part (5) which produc es expansion in the circumferential direction of the tube. Downstream of the ma ndrel and axial pulling force is exerted on the tube, an d the biaxially oriented tube is cooled down. At a distance downstream of the mandrel the tube is drawn through a calibration opening (12) bounded by calibration means, the calibration opening being such that i t produces a reduction in the external dimensions of the tube. Accurate regulation of the external dimensions of the tube is provided by re gulating the distance between the mandrel (3) and the ca libration means (12), in particular depending on the external dimensions of the tube m easured downstream of the calibration means.