GB1520571A - Apparatus for the granulation of strands of thermoplastic material - Google Patents

Abstract

1520571 Cutting filaments AUTOMATIK APPARATE-MASCHINENBAU H HENCH GmbH 28 Jan 1976 [28 Jan 1975] 03266/76 Heading DIF Strands 2 extruded from a row of nozzles 1 are drawn along a delivery channel 5 by rollers 8, 9 and granulated by cutter roller 18, water being supplied to the delivery channel, said channel projecting from the straight line joining the row of nozzles to the nip of rollers 8, 9 at least downstream of the nozzles and upstream of the nip so that the strands are pressed against the base of the channel 5. Water from reservoir 12 flows down the channel to cool the strands and prevent them sticking to it. Further water is applied by sprays 16. The base of the channel may have 6 longitudinal grooves or corrugations to guide and separate the strands. These grooves may be confined to the top and bottom of the channel containing the line 10 at which the strand path bends and the line 11 at which the strands leave the base of the channel. Between these portions the channel may have transverse grooves to reduce the flow of water and induce turbulence. One or more of the rolls 8, 9 may have circumferential grooves to guide the strands and one or more rolls may have longitudinal grooves to facilitate gripping of the strands. The extent to which the delivery channel projects can be varied by moving it horizontally. The angle it makes with the vertical can be varied by rotating it about one pivot 25, 26 and moving the other pivot. The tension applied to the strands is thereby varied. In the embodiment of (Fig. 4, not shown) the channel is convex with respect to the strands. Flap 15 is pivoted about 29. When strand extrusion begins the flap is in the position shown in dashed lines so that the initial length of each strand is diverted along channel 27. When the strand thickness has stabilised the flap is moved to its full line position in which it collects the strands and feeds them to the delivery channel. A further pivoted flap (32, Fig. 4, not shown) may be positioned part way along and close to the delivery channel. When it is pivoted so that its free, upper, end contacts the channel the strands are diverted from the channel and are thus conveniently observable. A mirror image apparatus including a channel and cutting wheel may be provided, Fig. 10, not shown. The second channel and cutter may be moved into position below the row of orifices 1 if the first cutter has to be serviced. Cooling water is supplied tangentially to the cutting wheel 18 via valve 24 and pipe 23 which merges into a collection channel 21. The channel 21 may have an upward bend (38, Fig. 9, not shown). Figure 11 shows how a cutter roller 101 cooperates with a counterblade 104 to cut granules 105 from strands 2. Cooling water flows over the top of housing wall 106. It is divided into a main stream 111 tangential to the cutter roller and a second stream 112 by an adjustably positioned bar 110 or roughly triangular cross section. The granules 105 are thus wetted soon after they are cut and before they contact housing 106 or any other part of the apparatus.