SE7608250L - HARDENING FOR STRENGTHENED FOREMAL - Google Patents

Abstract

1533007 Heat setting of extrudate A HEGGENSTALLER 9 Aug 1976 [12 Aug 1975] 33127/76 Headings B4-B5 A mixture of waste of wood particles or textile fibre with a binder, which is extruded by a piston extruder, is heat set downstream of the extruder die under pressure, during sliding passage through a channel defined between at least one pair of opposed elements 2, 3, of which one 2 is fixed against displacement transversely of the extrudate, and the other, 3 is transversely displaceably urged against the extrudate, by a loading means 24, 25, which may comprise compression springs, or an hydraulically or pneumatically operated piston, to a location which is peripherally spaced from the element 2, to permit escape of moisture from the extrudate, and permit the loading to be maintained constant, or varied. Preferably, the extruder piston and the means 24, 25 are hydraulically actuated from a common pressure source, with an overload protection afforded by a control which, when an adjustable extrusion pressure is attained, reduces the operating pressure of the means 24, 25 to a level which is also adjustable. The element 3 may exert a lower pressure during an extrusion then during a retraction stroke of the extrusion piston when stress relaxation of the extrudate is accordingly prevented. The elements 2, 3, may comprise a single pair engaging a cylindrical extrudate, Fig. 2 (not shown), or two pairs of plates 5 as in Fig. 1, which, with the means 24, 25, are preferably supported on a plurality of pairs of frames 11 spaced apart in the direction of extrusion with each frame of a pair comprising a member 12 carrying the stationary elements 2, and a member 13 releasably clamped thereto at 15, 16 and pivotable apart therefrom at 14, e.g. for releasing defective extrudate. One frame 11 of each pair is fixed, and the other 11 is slidable under thermal expansion at 18 in a guide 17, and each frame 11 is also vertically and horizontally adjustable for alignment with the extrusion die. Each element 3 is mounted for its transverse displacement to the frame member 13 by bolts 19 which support a plate 10 of the element 3 at heads 22 and are loaded on the other side of the member 13 by adjustable springs 20. To prevent the transversely displaceable element 3 being displaced with the extrudate by frictional contact, each element is also supported to the frame by a transversely spaced pair of tie rods 29, Fig. 4, engaging both the frame member 13 and lugs 27 of the element 3, at pivots 30 which permit the transverse displacement of the element 3.