Patent GB-953942-A (GB)
Title: Melt spinning apparatus for the production of filaments
IPC: D01D11/00
Filed: 1962-02-01
Abstract: 953,942. Melt-spinning apparatus, MONSANTO CHEMICAL CO. Feb. 1, 1962 [Feb. 13, 1961], No. 3951/62. Heading B5B. A melt-spinning apparatus for the production of filaments of a thermoplastic filamentforming polymer comprises a spinneret for shaping the molten polymer into streams 14 in a path extending downwardly from a spinning head 11 along a vertical extrusion line through a spinning chimney 12 at a predetermined extrusion rate, while a stream of air from a manifold 17 communicating with an air source 18 is directed laterally across the spinning chimney to cool and completely solidify the filaments 14. These filaments then pass between guide pins 19 and are taken up at a predetermined constant speed by known collecting means. If the pressure of the melt in the spinning head 11 is at the proper value, the spinning melt will be extruded at a sufficiently high speed to provide enough slack in the filaments 14 to allow the air stream to deflect the filaments from a straight vertical path, as shown in the drawing. If, however, the spinning head pressure falls, the rate of extrusion of the melt will decrease and cause the take up mechanism to pull the filaments on to a straight path and into alignment with a pair of slits 22 and 23 in the spinning chimney. Because of the constant speed take-up and the decreased extrusion rate, the denier of the filaments 14 will be decreased. Thus a decrease in denier is accompanied by a movement of the filaments from the deflected or arcuate path to a straight path. A light source 26 positioned adjacent to the slit 22 directs a light beam laterally across the spinning chimney, through tho slit 23 and on to a photo-sensitive impedance 27, the value of which varies as a function of the intensity of the light beam, and which is coupled with an output means arranged to actuate an alarm or control device whereby the denier of the filaments is continuously monitored and an alarm or control signal generated whenever the denier of the filaments falls below a predetermined value. The element 27 may be a sensitive cadmium sulphide resistor of known type which varies in resistance in response to variations in the intensity of the light beam. As shown, the resistor 27 is connected between terminals 28 and 29 in series with a 2000 ohm potentiometer 33 and a 51K resistor 34, all three of these elements being connected in parallel with a series connected 100 ohm resistor 37 and a transistor 38 connected between the terminals 28 and 29. The base of the transistor 38 is connected to the tap of the potentiometer 33. while the transistor emitter is connected to the 100 ohm resistor 37. The collector of the transistor is connected through a normally closed, manually operated switch 41 to the terminal 29. A battery 42 is connected in series with a relay 43 between the terminals 28 and 29 for applying power to the circuit. The relay 43 is provided with a contactor 46 which is closable to connect an alarm lamp 47 to a battery 48 when the relay is pulled in, the relay 43 pulling in at 2.4 ma. and dropping out at 2.2 ma. When the filaments follow a normal arcuate path the intense light beam holds the resistance of the resistor 27 to a low value and the transistor will not be conductive. If the denier of the filaments 14 falls below a predetermined value and they assume a straight path and thereby partially block off the light from the source 26, the resistance of the resistor will increase and the transistor 38 will become conductive. This allows more than 2.4 ma. to flow through the relay 43, thereby closing the circuit of the alarm lamp 47 and indicates to the operator that the denier of the filaments is too low. The closing of the contactor 46 may be used to operate a control device, for example a device automatically stopping the spinning operation. The resistor 27 is so sensitive that the movement of a single 3 denier filament into the light beam will cause the transistor to become conductive.