Patent GB-823509-A (GB)
Title: Spinning jets and the production thereof
IPC: D01D4/02
Filed: 1958-02-27
Abstract: A spinneret or spinning jet for melt-spinning comprises a relatively thick face-plate drilled with holes consisting of an inlet portion with a cylindrical wall, an intermediate portion of smaller diameter with a cylindrical wall and an outlet portion of smaller diameter than the intermediate portion, the three cylindrical portions being connected by two frusto-conical intermediate portions having walls tapering in the outlet direction, each hole in the face-plate being provided with a pre-drilled insert member the length of which is much less than the thickness of the face-plate and which has a cylindrical outlet end portion with an external diameter somewhat smaller than the diameter of the outlet portion of the hole in the faceplate, the remaining or inlet portion of the insert having externally a frusto-conical shape which narrows towards the outlet portion with <PICT:0823509/IV (a)/1> <PICT:0823509/IV (a)/2> <PICT:0823509/IV (a)/3> <PICT:0823509/IV (a)/4> <PICT:0823509/IV (a)/5> <PICT:0823509/IV (a)/6> <PICT:0823509/IV (a)/7> a very slight taper and ha mean external diameter equal to that of the intermediate cylindrical portion of the hole in the face-plate, the hole drilled in the insert having a greater diameter in the inlet portion of the insert than that of the outlet portion of the insert, these two portions of the insert bore, if desired being joined by an intermediate frusto-conical portion of the bore tapering towards the outlet portion of the bore.  As shown in Figs. 1 and 2, inserts comprising a lower cylindrical portion 1 and an upper cylindrical portion 2 with a slight taper in a downward direction have a pre-drilled jet aperture 3 communicating with an inlet bore 4.  The external diameter of the portion 1 is 1 mm. and the diameters of the portion 2 at the top and bottom are 1.65 and 1.60 mm. respectively. As shown in Fig. 3, the hole or bore 5 drilled in a face-plate 6 has a diameter d of 3 mm., a diameter e of 1.625 mm. and a diameter f of 1.05 mm.  Since the diameter of the portion f is slightly larger than the external diameter a of the portion 1 of the insert, the portion 1 is a sliding fit in the portion of the hole 5 in the face-plate having a diameter f.  Therefore no deformation of the extrusion orifice 3 drilled in the insert occurs when the insert is pressed into the hole 5 in the face-plate.  Since the diameter of the portion e of the hole 5 is the same as the mean diameter of the tapered portion of the insert, a good seal is established between the insert and the face-plate when the insert is pressed into the hole 5 in the face-plate.  Fig. 4 shows an insert 7 in position after having been pressed into the drilled hole 5 of the face-plate 6 by a punch.  The portion 8 of the latter (see Fig. 5) is a sliding fit in the inlet portion d of the hole 5 in the face-plate 6, while the portion 9 of the punch is a cylindrical round-edged protuberance which is a sliding fit in the inlet bore 4 of the insert 7 and thus functions as a guide to prevent tilting of the insert when it is pressed into position.  Fig. 7 shows a form of punch by means of which the insert is additionally sealed into the spinneret face-plate in which the guide protuberance 10 is not cylindrical but is rounded, and the adjoining portion 11 does not have a flat horizontal lower surface but has an inclined surface 12 which is designed to promote flow of the material of the face-plate surrounding the hole 5 to the top of the insert when the latter is driven home by the punch as shown in Figs. 8 and 9. The diameter g of the portion 11 of the punch shown in Fig. 7 is somewhat larger than the diameter c of the portion of the insert shown in Fig. 1, e.g. g = 2 mm. and c = 1.65 mm.  The inserts of the invention can be pressed into the holes in the thick face-plates of melt-spinning spinnerets from the inlet side without deformation of the extrusion orifices pre-drilled in the inserts and are thus particularly suitable when the extrusion orifices are of ultra-small diameter, i.e. below 125 mm .