Improvements in an extrusion head for the simultaneous application of two layers of thermoplastic material to an inner core

摘要

892,302. Extrusion heads. FAWCETT PRESTON & CO. Ltd. Dec. 22, 1960 [Dec. 29, 1959], No. 44154/59. Class 87(2). An extrusion head for the simultaneous application of two layers of an extrudible material to an inner cylindrical core, includes an inner tip unit j, a combined tip and die unit e, and a die k and sleeve means for varying the eccentricity of the inner tip unit and the die. The eccentricity of the inner tip unit j may be varied by rotation of the tip unit in the screw threads o and h1 which are slightly eccentrically mounted on the tip unit j, and in the sleeve h respectively. When the desired degree of eccentricity has been obtained the tip unit j may be locked in position by means of a nut p acting on a sleeve g acting on a shoulder on the tip unit. The parts g, h, and j when locked together may be rotated in the holder f. The thickness of the inner coating on the core may be varied by adjustment of a nut s on a fixed stud t, the nut bearing against a gland ring u screw threaded on the sleeve g and locked in position by a screw u1. The eccentricity of the die k may be varied by means of radial screws m acting on the die holder l and serving also to lock it in position. The thickness of the outer covering on the core may be varied by adjustment of an annular screw threaded ring q bearing on the die holder l. Thermoplastic material to provide the inner layer covering is fed from an extruder screw through passages b, b1 to the annular space between the tip unit j and unit e, and material to form the outer covering is fed through passage a to the annular space between the unit e and the die k. The core tube holders d, fare held in position by a retaining ring v, their rotation being prevented by a key w.