GB562771A - Improvements in or relating to extrusion processes - Google Patents

Abstract

562,771. Extruding thermosetting resins &c. CELLOMOLD, Ltd., DAVIES, D. N., and CHURCHMAN, F. H. Dec. 14, 1942, Nos. 17772/42 and 17370/43. [Class 87 (ii)] [Also in Group XXII] A method of producing curved extruded shapes from thermosetting resins and other extrudable substances which are deformable on issuing from the extrusion aperture but rapidly become rigid, comprises guiding a rigid part of the extruded material in a curved path, the rigid part acting as a lever which bends the still deformable material progressively at or near. the extrusion aperture. After the deformable material has been bent it becomes rigid and forms part of the lengthening lever which is bending the material issuing from the extrusion aperture. Fig. 1 shows an arrangement in which the rigid open end A of a tube of thermosetting material issuing from an extrusion nozzle 16 is attached to a block 20 having a plug which engages in the open end. The block carries rollers 21 which run in cam tracks 23, 35, 30 to produce, respectively, curved part BC, straight part CD and curved part DE. The block 20 may be in the form of a collar which fits over the end A. Jets of compressed air from an apertured ring 18 cool the issuing material to render it rigid. Fig. 4 shows a modification in which a clamp 45 having two hinged jaws is fixed to the end of a lever 44 pivoted at 43. The clamp rests on a wooden base 42. When a curved part H-H<1> has been extruded the clamp may be released and swung back, a further short straight length being then extruded and the curved part being in position H-H<2>, when it mav be sawn off. The arm or pivot or both may be adjustable and may be moved to vary the curvature. The material may be bent in more than one plane. Fig. 6 shows a flexible mandrel which is disposed within a tube to preclude flattening of the latter as it bends. The mandrel comprises a flexible wire rope carrying discs 71 separated by rings 72. The plates and rings are held together by a spring 75 located in a bore in a collar 73 in which one end of the rope is sweated, the other end being sweated in a small block 76.