Patent GB-1311191-A (GB)
Title: Cooling apparatus for extruded synthetic material
IPC: B29C48/05
Filed: 1970-03-31
Abstract: 1311191 Cooling extruded strands K MES. CHER F DIEDERIX E MURSCHEL [trading as C F SCHEER & CIE] 31 March 1970 [29 March 1969] 15310/70 Heading B5A [Also in Division B8] In the stretching and cooling of hot strands 12 of synthetic material, extruded from a die head 10, during passage through a cooling medium 16 between the nip of endless belts 32, 34, from which a further endless belt pair 70, 72 effects delivery to a rotary cutter 100, the belt 32 is normally spaced away from the belt 34 at the nip inlet where it passes over a roller 21, Fig. 2, but when a strand 12 breaks it follows a vertical path to interrupt a photo-cell 64 which actuates, through a control circuit, a double acting hydraulic motor 58 to displace the roller 21 and belt 32 to grip the broken strand against the belt 34, Fig, 1, and when the broken strand is engaged by the belts 32, 34 in the region of idler roll 22 the belt 32 is returned to its spaced apart Fig. 2 position, upon reverse actuation of the motor 58 after a variable time delay determined in the control circuit thereto. In Fig. 4, the full and dotted line position of piston 230 of motor 58 correspond respectively to the Fig. 1 and Fig. 2 positions of roller 21, to the latter whereof the piston 230 is displaced when an hydraulic valve spool 244, 245, 243 is displaced, against a return spring 246, in the direction 247 upon energizing of electromagnetic means 222. The apparatus is controlled from stop and start switches 204, 206, the latter 206 whereof energizes a main relay 200 which, via relay 200c and connector 208, effects commencement, optionally after a time delay, of the endless belt and cutter drives, and also opens a discharge relay 200e, and closes a charging relay 200d to charge a capacitor 213, over a period adjustable by potentiometer 210, until the gate voltage of a thryistor 220 reaches ignition point, whereupon current flows through relay contact 200f, limit switch 226, and electromagnetic means 222, to displace the piston 230 to the dotted line position, and through relay 218 to close contact 218a and discharge the capacitor 213 through the resistor 216. This movement of piston 230 opens, via piston rod cam 228, a by-pass connection around a contact 202a of a relay 202 which is controlled by the photoelectric means 64. If the beam between source 64<SP>1</SP> and a phototransistor 64<SP>11</SP> is interrupted by a vertically descending broken strand 12, the relay 202 is de-energized to open the contact 202a to interrupt current flow through the electromagnetic means 222 (to thereby return the piston 230 to its full line position), and to extinguish the thyristor 220, and to de-energize the relay 218 to open contacts 218a to re-charge the capactor 213 for subsequent ignition of the thyristor 220. The belts 32, 34 comprise an exterior fabric layer of longitudinal rubber threads, permitting expansion of the exterior band in this direction during passage over the rollers 22, 23, 24, and an inner layer of foam which absorbs cooling medium and compresses to envelop the strands 12. One of the belts, 34, is driven by a variable speed motor 36, and water is squeezed from both belts by rollers 54, 56, the motor 36 also driving a roller 74 over which passes one belt 70 of the belt pair 70, 72 which are resiliently urged together. A pair of rotary cutters 114 are provided, selectively rotatable and mounted upon a wheeled carriage 110 for alternate location in the cutting path. In a modified embodiment, Fig. 5 (not printed), the cooling water container is divided by a transverse partition into a pair of sequential chambers, in the second whereof the co-operating endless bands follow alternate vertically descending and ascending paths, around upper and lower rows of rollers, into and out of the cooling water the level whereof is adjustable independently of the first chamber so that the cooling may be regulated to ensure that the strands, upon leaving the bath, retain sufficient heat to vaporize adhering water prior to entry to the cutter.