GB780743A - Melt spinning - Google Patents

Abstract

<PICT:0780743/IV (a)/1> <PICT:0780743/IV (a)/2> <PICT:0780743/IV (a)/3> <PICT:0780743/IV (a)/4> <PICT:0780743/IV (a)/5> <PICT:0780743/IV (a)/6> <PICT:0780743/IV (a)/7> A melt-spinning apparatus comprises a spinning pack wherein at least one deformable sealing ring seals a joint in the spinning pack assembly as the result of the melt pressure, the surface area of the ring in contact with the melt being greater than that in contact with the spinning pack. As shown in Fig. 1, the melt is pumped at a high pressure through an inlet channel 4 in the externally threaded spinning pack closure 3 on to which is screwed the cylindrical spinning pack housing 1 provided with a thread 2 at the top. The melt flows through the sand filter bed 11, pack plug 10 and spinneret plate 9 to form filaments 13. The hydraulic pressure of the melt inside the spinning pack acts on the inside face 6A of the sealing ring 6, of bi-convex lens section, between the circular flange 5 of the pack closure 3 and the circular flange or shoulder 7 of the pack housing 1, and forces the sealing ring radially outward. The initially curved sides of the sealing ring, which initially made a line contact with the flange 5 and the shoulder 7, are thereby deformed and flattened, so that the cross-section of the ring becomes wedge-shaped and closely fits the flange 5 and the shoulder 7, with the result that no melt leaks through to the thread 2 between the pack closure 3 and the housing 1 and the housing can be readily unscrewed from the pack closure. Although the curved upper and lower sides of the ring 6 are somewhat flattened as the result of the hydraulic pressure of the melt on the inner face 6A of the ring, the deformation of the ring is not so great that the area of the face 6A and the other surfaces of the ring exposed to the hydraulic pressure of the melt becomes less than the area of the ring in contact with the shoulders 5, 7. The pack plug 10 and spinneret plate 9 are encircled by a sleeve 12 of a soft metal, such as aluminium foil, the lower portion of which is bent over the edge of the spinneret plate 9 to form an inwardly-extending flange 12A which serves as a gasket sealing the filter and spinneret plate assembly against the pack housing 1 and shoulder 8. The upper portion of the sleeve 12 is also bent over the upper edge of the pack plug 10 to form an upper inwardly extending flange 12B. Instead of the metal sleeve a sealing gasket may be used between the shoulder 8 and the lower face of the spinneret plate 9 and a second sealing gasket between the lower face of the pack plug 10 and the upper face of the spinneret plate. As shown in Fig. 2, the spinning pack assembly is held in place by screw bolts 15 which are screwed into a flange in the spinning pack closure 16, and the joint between the spinning pack closure 16 and the spinning pack housing 18 is sealed by a ring 17 in the same manner as shown in Fig. 1. The joint between the spinneret plate and the shoulder 18A of the spinning pack housing 18 is sealed by means of a gasket 17A. Fig. 3 shows a spinning pack assembly which can be assembled from the underside of the spinning apparatus and has an externally screw-threaded bottom closure 19 which can be screwed into the internally threaded portion 25 of the spinning apparatus, the joint between the parts 19 and 25 being sealed by the sealing ring 24 in the same manner as is shown in Figs. 1 and 2. The sealing ring may have the shape shown at 29 in Fig. 5 or the tapered section shown at 30 in Fig. 6, the seats 31, 32 for the ring in this case being tapered and serrated, so that the ring maintains line contacts even under pressure. The sealing ring may have a channel-shaped cross-section of V-, U- or W-shape, the channel being on the inner surface of the ring, as shown at 33 in Fig. 7. The sealing ring may be hollow and of circular cross-section and may be composed of hard elastic material so shaped and used that it is not deformed beyond its elastic limit, but is preferably made of material of such a nature that in use it is permanently deformed, e.g. nickel steel, duraluminium, stainless steel, bronze or copper. The Provisional Specification refers to Specification 755,954.