Method and device for producing crimped multifilament synthetic yarn

Abstract

A method for producing at least one crimped multifilament synthetic yarn through the use of a texturing process, wherein a stream of heated gaseous medium is brought into a texturing channel (1), (2), (3), wherein synthetic filaments (4), (5), (6) are displaced and deformed by the heated gaseous medium in the texturing channel (1), (2), (3), wherein both the temperature and the flow rate of the gaseous medium are measured, and wherein the heat flow is regulated. To this end, the device comprises a regulating device (50) and, for each texturing channel (1), (2), (3), at least one temperature sensor (60), (61), (62) and a flow sensor (57), (58), (59).

Claims

1. Method for producing at least one crimped multifilament synthetic yarn through the use of a texturing process, comprising: bringing a stream of heated gaseous medium into a texturing channel, displacing and deforming a number of synthetic filaments by the heated gaseous medium in the texturing channel, and fixing the deformed filaments, so that a crimped synthetic yarn is obtained, wherein both temperature and flow rate of the gaseous medium are measured, and a heat supply per unit of time that results by introduction of the gaseous medium is regulated to achieve or maintain a predetermined target value for the heat supply by adjustment or regulation of at least one parameter which influences the heat supply.

2. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, characterized in that, in the regulation of the heat supply per unit of time, the heat supply is changed by changing or regulating the flow rate of the gaseous medium and/or the temperature of the heated gaseous medium.

3. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, characterized in that the heat supply per unit of time is regulated by regulating the flow rate of the stream of gaseous medium in order to attain a specific target value when a variance between the measured value and the target value is established, and/or by regulating the temperature of the stream of heated gaseous medium in order to attain a specific target value when a variance between the measured value and the target value is established.

4. Method for producing at least one crimped multifilament synthetic yarn, according to claim 3, characterized in that in the texturing process either only the flow rate of the stream of gaseous medium is regulated in order to attain a specific target value, wherein this target value is defined such that the stream of gaseous medium, at a flow rate with this target value and at the measured temperature, delivers a desired heat supply per unit of time, or only the temperature of the stream of heated gaseous medium is regulated in order to attain a specific target value, wherein this target value is defined such that the stream of gaseous medium, at a temperature with this target value and at the measured flow rate, delivers a desired heat supply per unit of time.

5. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, characterized in that the flow rate is regulated in order to attain a specific target value for the flow rate, and in that the flow rate is changed by changing or regulating pressure on the supplied gaseous medium.

6. Method according to claim 1, characterized in that the synthetic filaments in the texturing channel are compressed, so that a respective yarn plug is formed, and in that the yarn plugs, after having left the texturing channel, are displaced onto a moving cooling surface.

7. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, characterized in that the synthetic filaments in the texturing channel are compressed, so that a respective yarn plug is formed, wherein the compressed yarn is added at one end of the yarn plug, whilst at the other end of the yarn plug, being the take-off end, the compressed yarn is drawn off, so that the yarn plug unravels and the yarn is removed in the crimped state, in that the location of the take-off end of the yarn plug is detected, and in that in the texturing process one or more parameters are regulated on the basis of the detected location in order to prevent the locations of the take-off ends of the yarn plugs being outside a predefined take-off zone.

8. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, characterized in that at least two crimped multifilament yarns are produced simultaneously through the use of a respective texturing process, wherein in each texturing process a number of synthetic filaments are brought by a respective stream of heated gaseous medium into a respective texturing channel, in that both the temperature and the flow rate of each stream of gaseous medium are measured, and in that for each texturing channel the heat supply per unit of time that is realized by the introduction of the heated gaseous medium is regulated in order to minimize the differences between the heat supply in the different texturing channels.

9. Method for producing at least one crimped multifilament synthetic yarn, according to claim 8, characterized in that the heat supply per unit of time in the different texturing channels is regulated in order to attain or maintain a common target value.

10. Method for producing at least one crimped multifilament synthetic yarn, according to claim 8, characterized in that the heat supply per unit of time in each texturing channel is regulated by regulating the flow rate of the stream of gaseous medium in order to attain a specific target value and by regulating the temperature of the stream of heated gaseous medium in order to attain a specific target value, and in that for the different texturing channels the same target values are used.

11. Method for producing at least one crimped multifilament synthetic yarn, according to claim 8, characterized in that for each texturing channel the following parameters are measured: the pressure of the stream of gaseous medium, the flow rate of the stream of gaseous medium, and the temperature of the stream of heated gaseous medium, and in that at least the pressure and/or the temperature are regulated in order to obtain a desired heat supply per unit of time in each texturing channel.

12. Method for producing at least one crimped multifilament synthetic yarn, according to claim 8, characterized in that the synthetic filaments in each texturing channel are compressed, so that a respective yarn plug is formed, wherein the compressed yarn is added at one end of the yarn plug, whilst at the other end of the yarn plug, being the take-off end, the compressed yarn is drawn off, so that the yarn plug unravels and the yarn is removed in the crimped state, in that the locations of the take-off ends of the different yarn plugs are detected, in that in each texturing process one or more parameters are regulated on the basis of the detected location in order to prevent the distance between farthest apart locations from exceeding a predefined maximum, or to prevent the locations of the take-off ends of the yarn plugs being outside a predefined take-off zone.

13. Method for producing at least one crimped multifilament synthetic yarn, according to claim 12, characterized in that in each texturing process at least one of the following parameters is regulated on the basis of the detected location of the take-off end of the yarn plug formed in that texturing process: the temperature, the flow rate and the pressure of the gaseous medium.

14. Method for producing at least one crimped multifilament synthetic yarn, according to claim 12, characterized in that the detection of the locations of the take-off ends is effected by a capacitive detection or by, during each texturing process, making image recordings on which the take-off ends of the different yarn groups are visible, wherein each detection of the locations of the take-off ends is effected by automatic analysis and/or processing of one or more image recordings.

15. Method according to claim 12, characterized in that the locations of the take-off ends of the different yarn plugs are detected at at least two successive points in time, in that, on the basis of established changes in these locations, for each take-off end is defined what location is expected at a later point in time, and in that regulators are provided to anticipate an expected location outside the predefined take-off zone by, in the particular texturing process, regulating a parameter in order to keep the take-off end within this take-off zone.

16. Method for producing at least one crimped multifilament synthetic yarn, according to claim 1, further comprising: measuring temperature and flow rate of the gaseous medium as the gaseous medium exits the texturing channel.

17. Method for producing at least one crimped multifilament synthetic yarn, according to claim 16, characterized in that the heat supply is defined based on the temperature and the flow rate of the gaseous medium, and the temperature and the flow rate of the gaseous medium as the gaseous medium exits the texturing channel.

18. Method for producing at least one crimped multifilament synthetic yarn through the use of a texturing process, comprising: bringing a stream of heated gaseous medium into a texturing channel; measuring both temperature and flow rate of the gaseous medium; regulating a heat supply per unit of time that depends on both the temperature and the flow rate of the gaseous medium, the regulating comprising determining a target value for the heat supply and, based on the measured temperature and the measured flow rate, adjusting or regulating at least one of the temperature and the flow rate so as to achieve or maintain the target value; displacing and deforming a number of synthetic filaments by the heated gaseous medium in the texturing channel; and fixing the deformed filaments, so that a crimped synthetic yarn is obtained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to further illustrate the characteristics of the invention, there hereinafter follows a detailed description of a possible embodiment of a texturing device according to this invention. We emphasize that this is only an example of the many possible embodiments within the framework of the invention, and that this description is in no sense to be regarded as a limitation of the scope of the protection. In this detailed description, reference is made by means of reference numerals to the hereto appended FIG. 1, which is a schematic representation of a texturing device according to this invention, and

(2) FIG. 2, which is a more detailed schematic representation of the texturing unit of the texturing device of FIG. 1.

DETAILED DESCRIPTION

(3) The texturing device represented in FIG. 1 comprises a texturing unit (13) (represented in detail in FIG. 2), in which are provided three texturing channels (1), (2), (3) having a respective yarn entrance (1a, 2a, 3a), for the introduction of a multifilament synthetic yarn (4), (5), (6), and a respective yarn exit (1b), (2b), (3b), along which the textured yarn compressed into a yarn plug (7), (8), (9) can leave the texturing channels (1), (2), (3) again. In addition, the texturing device also comprises a rotatable cooling drum (20), which is drivable by a motor (22) (see also FIG. 1).

(4) From a common feed line (30), compressed air under high pressure (for example a pressure between 5 and 9 bar, preferably between 6 and 8 bar, preferably 7 bar) is brought via three separate feed lines (31), (32), (33) to the respective texturing channels (1), (2), (3) (see also FIG. 1). Each texturing channel comprises an access opening (not visible in the figure), to which is connected a feed line (31), (32), (33) and along which the compressed air can be brought into the texturing channel. Each feed line (31), (32), (33) is interrupted in the vicinity of the texturing channels (1), (2), (3) by a heating element (34), (35), (36), so that the supplied air can be heated to a high temperature (for example a temperature between 120° C. and 220° C., preferably between 130° C. and 200° C., preferably between 150° C. and 180° C.), before this is fed into the texturing channel (1), (2), (3).

(5) In addition, the device also comprises a regulating device (50) having associated sensors and regulating units as set out below.

(6) For each feed line (31), (32), (33) there is provided a pressure sensor (54), (55), (56) and a pressure regulator (51), (52), (53). Each pressure sensor (54), (55), (56) measures the pressure of the compressed air in a respective feed line (31), (32), (33) in the portion located in front of the heating elements (34), (35), (36), and is provided to send to the regulating device (50) a measuring signal (P.sub.m1), (P.sub.m2), (P.sub.m3) representing the magnitude of the pressure in this feed line (31), (32), (33).

(7) Each pressure regulator (51), (52), (53) is provided to change the pressure in the associated feed line (31), (32), (33) in accordance with a regulating signal (P.sub.r1), (P.sub.r2), (P.sub.r3) which is emitted by the regulating device (50).

(8) For each feed line (31), (32), (33) there is also provided a flow meter or flow sensor (57), (58), (59), which is provided to send to the regulating device (50) a measuring signal (D.sub.m1), (D.sub.m2), (D.sub.m3) representing the magnitude of the flow rate in the particular feed line (31), (32), (33). The flow rate is measured in each feed line, in the portion located between the pressure sensor (54), (55), (56) and the heating element (34), (35), (36).

(9) In each texturing channel (1), (2), (3), close to the opening where the compressed air is blown into the texturing channel, there is placed a temperature sensor (60), (61), (62). Each temperature sensor (60), (61), (62) is provided to send to the regulating unit (50) a measuring signal (T.sub.m1), (T.sub.m2), (T.sub.m3) representing the absolute temperature in the particular feed line (31), (32), (33). The setting of each heating element (34), (35), (36) is regulatable and is designed so that the setting thereof is changed such that the temperature of the gaseous medium in the associated feed line (31), (32), (33) is changed in accordance with a regulating signal (T.sub.r1), (T.sub.r2), (T.sub.r3) which is emitted by the regulating device (50). The temperature is thus regulated in a separate control circuit in order to attain or maintain a predefined value, this value being dependent on the base material. In this embodiment, this temperature is not regulated in order to influence the heat supply. The regulation of the heat supply is here realized purely by regulating, via the pressure, the flow rate in each feed line (31), (32), (33) on the basis of the measured temperature and the measured flow rate of the air stream.

(10) For each texturing channel, the measuring signal (T.sub.m1), (T.sub.m2), (T.sub.m3) of the temperature sensor (60), (61), (62) and the measuring signal (D.sub.m1), (D.sub.m2), (D.sub.m3) of the flow sensor (57), (58), (59) indicate what is the heat supply in the particular texturing channel (1), (2), (3).

(11) The regulating device is provided to detect on the basis of these measuring signals for each texturing channel that the heat supply changes over time. This can be a change relative to the original value or relative to a predefined target value. The regulating device is provided to change the flow rate in the associated feed line (31), (32), (33), when such changes are detected, such that the heat supply is restored to the desired level. As already stated, to this end, for the heat supply per unit of time, a specific target value can be set, but for the flow rate too there can be set a specific target value which is defined such that the compressed air stream with the measured temperature and with a flow rate which is equal to the target value realizes the desired heat supply. This target value will then in the course of the production process be automatically adjusted to the measured temperature.

(12) In an additional or an alternative setting, the regulating device (50) can also be provided to detect on the basis of the said measuring signals (T.sub.m1), (T.sub.m2), (T.sub.m3) of the temperature sensor (60), (61), (62) and the said measuring signals (D.sub.m1), (D.sub.m2), (D.sub.m3) of the flow sensor (57), (58), (59) that there are mutual differences between the heat supply in the three texturing channels (1), (2), (3), or that these differences exceed a predefined limit, and to change the flow rate in one or more feed lines, when such differences are detected, such that the heat supply in the three texturing channels (1), (2), (3) is brought back equal or is brought within the predefined limits.

(13) The changing of the flow rate in a specific feed line (31), (32), (33) is effected by changing the pressure in the particular feed line. The pressure is then changed such that the desired flow rate in the feed line is obtained. The pressure in a feed line (31), (32), (33) is thus regulated, by means of a regulating signal (P.sub.r1), (P.sub.r2), (P.sub.r3) emitted to the pressure regulator (51), (52), (53), as a function of the difference between the measured flow rate (D.sub.m1), (D.sub.m2), (D.sub.m3) in this feed line and the flow rate which is necessary to attain the desired heat supply at the temperature which is measured at a specific moment, wherein the regulation, of course, has the aim of bringing this difference to zero.

(14) With this device, crimped multifilament synthetic yarn is produced from thermoplastic materials, such as, for example, polypropylene, polyester, polyamide 6 or polyamide 6.6. As an example, the production of such synthetic yarn from polypropylene is described. For other base materials, this production proceeds in a totally analogous manner.

(15) From polypropylene, according to a known extrusion process, filaments are formed, and by joining together various of these filaments (between 120 and 288 filaments, preferably between 150 and 250) in a known manner, a multifilament yarn is formed. In order to obtain a crimped yarn having a particularly uniform quality, for example in order to make the yarn suitable for the weaving of carpets, these yarns are subjected to a texturing process with the use of the above-described device. The crimped yarn typically has a linear density (titre) which is between 1000 dtex (grams per 10 km length) and 3000 dtex.

(16) Three polypropylene multifilament yarns (4), (5), (6) are brought via the yarn entries (1a), (2a), (3a) into a respective texturing channel (1), (2), (3), whilst compressed air at a high temperature (for example a temperature between 120° C. and 220° C., preferably between 130° C. and 200° C., preferably between 150° C. and 180° C.), is blown at high velocity into these texturing channels. The compressed air is fed via the common line (30) under a pressure of between 5 and 9 bar, preferably between 6 and 8 bar, preferably 7 bar, and is brought via the feed lines (31), (32), (33) and the heating elements (34), (35), (36) to the respective texturing channels (1), (2), (3). Typical values for the flow rate of the compressed air lie between 50 litres/minute and 300 litres/minute.

(17) The pressure in the feed lines (31), (32), (33) is measured by means of the pressure sensors (54), (55), (56), which send a corresponding measuring signal (P.sub.m1), (P.sub.m2), (P.sub.m3) to the regulating device (50).

(18) The flow rate in the feed lines (31), (32), (33) is measured by means of the flow sensors (57), (58), (59), which send a corresponding measuring signal (D.sub.m1), (D.sub.m2), (D.sub.m3) to the regulating device (50).

(19) The regulatable heating elements (34), (35), (36) are regulated in a separate control circuit in order to bring the compressed air to a suitable temperature. The actual temperature of the introduced compressed air is measured in each texturing channel (1), (2), (3) by the temperature sensors (60), (61), (62), which send a respective measuring signal (T.sub.m1), (T.sub.m2), (T.sub.m3) to the regulating device (50). Via a separate control circuit, each heating element (34), (35), (36) is regulated in order to attain or maintain the desired temperature for the compressed air. To this end, the regulating device (50) sends regulating signals (T.sub.r1), (T.sub.r2), (T.sub.r3) to the respective heating elements (34), (35), (36).

(20) The air has a temperature which is sufficiently high to bring the synthetic filaments to a temperature at which the synthetic material is soft and deforms easily.

(21) The filament yarn (4), (5), (6) is transported by the hot air into the texturing channels (1), (2), (3). Each texturing channel is also provided with a ‘stuffer box’, mainly consisting of a widening of the texturing channel and a number of openings along which the air can leave the texturing channel (this in not indicated in the figure). As a result, the filaments experience a sudden retardation, whereby the yarn (4), (5), (6) is compressed into a yarn plug (7), (8), (9) and the filaments of the yarn deform. This yarn plug (7), (8), (9) is further displaced in the texturing channel (1), (2), (3) and leaves the texturing channel via the exit opening (1b), (2b), (3b).

(22) The three yarn plugs (7), (8), (9), after having left their respective texturing channels (1), (2), (3), are laid side by side on the shell surface (21) of a rotating cooling drum (20) in order to cool and in order to fix the deformations. The cooling drum is rotated by means of a motor (22), so that a specific peripheral speed is attained on the cooling drum, preferably between 40 and 100 m per minute. This speed is settable and regulatable.

(23) The crimped yarn is drawn off from the foremost ends (7a), (8a), (9a) of the advancing yarn plugs (7), (8), (9)—termed the take-off ends—at a greater speed than the said peripheral speed and led away from the surface of the cooling drum (21) in order to be wound onto bobbins (not represented in the figure).

(24) The locations (L.sub.1), (L.sub.2), (L.sub.3) of the take-off ends (7a), (8a), (9a) are detected by means of a camera (70). To this end, the image recordings of this camera (70) are automatically analysed on a continuous basis and processed in an image processing unit (not represented).

(25) On the basis of these image recordings, it is in particular determined to what degree the location (L.sub.1), (L.sub.2), (L.sub.3) of the take-off end (7a), (8a), (9a) of each yarn plug (7), (8), (9) varies from a specific target location, and/or to what degree these locations (L.sub.1), (L.sub.2), (L.sub.3) mutually differ from one another.

(26) More specifically, the distance (D) between the farthest apart locations (L.sub.1), (L.sub.2), (L.sub.3) of the take-off ends (7a), (8a), (9a), for example, is controlled (see FIG. 2), and the regulating device (50) is provided to regulate one or more parameters on the basis of the detected locations (L.sub.1), (L.sub.2), (L.sub.3) in order to prevent this distance (D) exceeding a predefined maximum. In an alternative set-up or by way of addition, the regulating device (50) can also be provided to prevent, by regulating one or more parameters, the take-off ends (7a), (8a), (9a) of the yarn plugs (7), (8), (9) being outside a predefined take-off zone (Z).