Extrusion machines with brakes for regulating back pressure

Abstract

The invention relates to an extrusion plant for producing cylindrical semi-finished products made of plastic, comprising: an extruder (1) for supplying a pressurized plastic melt; at least one Extrusion die (7) at the press (1) through which the melt exits the extruder (1) as a substantially cylindrical plastic billet (8); placed in the extrusion die ( 7) the subsequent correcting part (2) passed through by the plastic blank (8) that has just been extruded, the correcting part (2) cools the plastic blank (8) and defines the outer diameter (d) of the plastic blank (8); A braking device (3) placed behind the correction element (2), by means of the braking device (3) an axial force (A) directed opposite to the feed of the plastic blank (8) is variably introduced into the plastic blank (8); and a force receiver (9), which measures the axial force (A) introduced into the plastic blank (8) by the braking device (3). The object of the present invention is to improve an extrusion system of this type in such a way that it achieves a better adjustment quality and is suitable for processing highly heat-resistant plastics. This object is achieved in that the brake device (3) comprises at least one brake shoe (16) provided with a friction surface (19) which is guided in a radially movable manner relative to the plastic blank (8), In this case, the radially movably guided brake shoe (16) can be acted upon with a radial force (R) when the friction surface (19) is in contact with the periphery of the plastic blank (8) Axial forces (A) are introduced into the plastic blank ( 8 ), and the friction surface ( 19 ) has the shape of a groove-shaped section of a cylindrical peripheral surface.

Description

technical field [0001] The invention relates to an extrusion plant for producing cylindrical semi-finished products made of plastic according to the preamble of claim 1 . Background technique [0002] An extrusion device of this type is known from document WO 1998 / 09709 A1. [0003] In lightweight construction applications in aerospace and aerospace, in machine tools (Werkzeugmaschine) and textile machines, and also in automobile construction, metal components are increasingly being replaced by components made of high-performance plastics (Hochleistungskunststoff) . Heat-resistant and highly load-resistant thermoplastics such as polyetheretherketone (PEEK) may be mentioned here in particular. [0004] From the user's point of view, the production of components made of PEEK is almost similar to conventional metal processing: standardized semi-finished products (such as tubes, profiled parts or rods) are cut into the desired shape (Gestalt) in terms of dimensions . In PEEK...

AI Technical Summary

Problems solved by technology

After correcting the parts, the temperature of PEEK is still much higher than 100°C, so that in known devices there is a concern that the PU rollers of its braking device cannot withstand thermal and mechanical loads and damage the plastic blanks

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