GB820918A - Improved method and apparatus for the manufacture of artificial threads by melt-spinning - Google Patents

Abstract

<PICT:0820918/IV (a)/1> <PICT:0820918/IV (a)/2> In melt-spinning artificial threads by supplying a fusible filament-forming polymer in particulate form to a heated melting grid and pumping the melt thereby obtained to a spinneret plate by means of a heated pump block or unit, the pump block is maintained in a heated condition when the melting grid is replaced by another. As shown in Fig. 1, granular polymer from a rigidly mounted feed hopper drops through a rotary valve 36, a guide tube 39 and a fall pipe 9 on to a melting grid 1 which comprises an annular jacket 2 connected through nipples 3, 4 (Figs. 1 and 2) with a heating device (not shown) and with a spiral tube 5 in such a manner that a heating fluid circulates through the jacket and the spiral tube. The polymer melted on the grid falls into a collecting hopper 12 in the jacket 2 and flows through an outlet 15, inlet 20 and suction line 21 to the spinning pump 22 in the pump block 18. Thence it is pumped through the pump discharge pipe 23 and sand filter 24 and is extruded through the spinneret plate 25. The pump block 18 is surrounded by a heating jacket 26 through which extends the pump shaft 27. The hopper 12 (the walls of which may be solid, instead of hollow, as shown) has a flat underface 16 which mates with the flat upper face 17 of the pump block 18 to permit heat transfer between the hopper 12 and the pump block. The outlet 15 of the hopper 12 is so dimensioned that the melt only just flows out of the hopper under its own weight. When the melting grid 1 has become fouled with polymer deposits the valve 36 is closed and spinning is continued until the hopper 12 is empty, whereupon the pump drive is switched off. Next the bolts 19 holding together the melting grid 1 and the pump block 18, and the bolts 34 holding together the flange 33 and the flange 35 of the rotary valve, are unscrewed and removed. As a result the flange 33 descends freely, as the upper portion 31 of the fall pipe 9 is a rubber sleeve, and the melting grid 1 rests freely on the pump block 18. The grid may then be removed, after bolts 10 have been unscrewed and removed, and is immediately replaced by a clean grid which preferably has been preheated. The apparatus is then bolted up, air is expelled from pipe 9 by connecting the nipple 11 with a supply of nitrogen and the pipe 9 is refilled with granular polymer by opening valve 36. Spinning is then resumed as soon as the hopper 12 becomes refilled with melt. During the replacement of the fouled melting grid 1 by a clean grid, the pump block with the pump remains in situ and is uninterruptedly maintained at the spinning temperature.