CONTINUOUS EVALUATION OF YARN CRIMP
United States Patent 3762220
Yarn is caused to travel at a velocity w1 under a constant tension sufficient to straighten but insufficient to stretch the yarn. Downstream of the point of application of this tension, a second constant tension is applied to the yarn, the second tension being small enough to allow any crimp in the yarn to be re-formed. The velocity w2 of the yarn traveling past the point of application of the second constant tension is continuously measured, and the crimp along the length of the yarn is continuously evaluated by means of the relationship Crimp (%) = [(w1 - w2)100./w1 ] If desired, measurement of latent crimp may be obtained according to this invention by developing the crimp (e.g., by the application of steam or boiling water to the yarn) between the two points where tension is applied to the yarn.
US Patent References:
Method and apparatus for evaluating crimp uniformity
Hoskins - August 1967 - 3333467
Method and apparatus for evaluating crimp uniformity
Hoskins - August 1967 - 3333467
Inventors:
Gusack, James A. (Williamsburg, VA)
Stephens, Bernard B. (Anderson, SC)
Stevens, James A. (Williamsburg, VA)
Stephens, Bernard B. (Anderson, SC)
Stevens, James A. (Williamsburg, VA)
Application Number:
05/216835
Publication Date:
10/02/1973
Filing Date:
01/10/1972
View Patent Images:
Export Citation:
Assignee:
Don Badische Company (Williamsburg, VA)
Primary Class:
Other Classes:
28/281
International Classes:
B65H51/30; G01B21/32; B65H51/00; G01D21/00
Field of Search:
73/160,159,95.5
Primary Examiner:
Queisser, Richard C.
Assistant Examiner:
Corr, Denis E.
Claims:
What is claimed is
1. A continuous process for evaluation of the crimp along the length of a yarn, which process comprises the following sequential steps:
2. The process according to claim 1, wherein the yarn is subjected to an environment which affords the development of any latent crimp in the yarn between the points where tension is applied to the yarn.
3. A device for the continuous evaluation of crimp along the length of a yarn, which device comprises:
4. A device according to claim 3, including means for developing latent crimp in the yarn between the points where tension is applied to the yarn.
1. A continuous process for evaluation of the crimp along the length of a yarn, which process comprises the following sequential steps:
2. The process according to claim 1, wherein the yarn is subjected to an environment which affords the development of any latent crimp in the yarn between the points where tension is applied to the yarn.
3. A device for the continuous evaluation of crimp along the length of a yarn, which device comprises:
4. A device according to claim 3, including means for developing latent crimp in the yarn between the points where tension is applied to the yarn.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to textiles and particularly to a textile yarn testing method and apparatus.
2. Prior Art
As a result of the recent and rapid development of technology in the texturizing of synthetic textile yarns, it has become increasingly evident to the industry that test devices and methods once adequate fall far short of providing the information required to control today's processes. Standard methods and devices for measuring the crimp in a texturized yarn comprehend the taking of measurements on an isolated segment of the yarn and yield only average values for the amount of crimp therein. Instantaneous fluctuations in the amount of crimp, which may be periodic or non-periodic, and which result from the nature and treatment of the yarn prior to texturizing as well as inadequacies and disturbances in the texturizing procedure itself, can be evaluated only by means of a continuous method or device which operates upon a traveling yarn.
Accordingly, a continuous method and device have been eagerly sought after by the industry. As of late some continuous test methods have been proposed, as exemplified by those specified and defined in U.S. Pats. Nos. 3,333,467 and 3,471,702. In these prior methods, however, crimp is indirectly determined by measurement of related properties of the crimped yarn--e.g., tensile strength, or diffuse and specular light reflectance, or the amount of relaxation of tension on a band of crimped tow at a point between its passage through tensioning and relaxing rolls. In fine, a method and apparatus combining simplicity and economy of operation with directness of crimp measurement were heretofore unobtainable.
SUMMARY OF THE INVENTION
The direct method and the device of the present invention have basis in the observation that the amount of crimp in an isolated segment of yarn is generally determined by the following fundamental relationship:
Crimp (%) = [(l 1 -l 2 )/l 1 ] 100,
Wherein l 1 is the measured length of the yarn segment held under a tension sufficient to completely straighten the yarn but insufficient to elongate it; and l 2 is the measured length of the same yarn segment held under a tension which allows full development of the crimped or crinkled condition therein.
According to the present invention, adaptation of this fundamental principle to a yarn in motion is made as follows:
Yarn is made to travel under a first constant tension which is sufficient to completely straighten the yarn but insufficient to stretch it. The length of this yarn passing a given point per unit time is proportional to l 1 in the fundamental relationship. The yarn is then caused to travel under a tension which allows full development of the crimped or crinkled condition. The length of yarn passing a given point per unit time under these conditions is proportional to l 2 in the fundamental relationship. Since the length of a yarn segment passing a point per unit time equals the velocity of the yarn, the following relationship for a traveling yarn can be written:
Crimp (%) = [(w 1 -w 2 )/w 1 ] 100,
wherein w 1 is the velocity of the yarn traveling under a tension sufficient to straighten but insufficient to stretch it, and w 2 is the velocity of the yarn traveling under a tension which allows full development of the crimped or crinkled condition therein.
These velocities are continuously determined in the measurement phase of a preferred embodiment according to the present invention, and the crimp (in percent) is continuously calculated and recorded in the computation phase of the same embodiment.
Use of this invention affords a direct and instantaneous evaluation of the uniformity of a texturized yarn, and comprehends prompt quality control by immediate modification of process parameters to compensate for undesired variations in the crimp of a texturized yarn.
BRIEF DESCRIPTION OF THE DRAWING
For a more complete understanding of the present invention, reference should be made to the detailed description of the preferred embodiments thereof, which is set forth below. This description should be read together with the accompanying drawing, wherein:
FIG. 1 schematically depicts the measurement phase of a method and device according to the present invention; and
FIG. 2 diagrammatically represents the evaluation (computation) phase of the same method and device according to the present invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS
With particular reference to FIG. 1 of the drawing, a texturized continuous-filament nylon carpet yarn (11) having a denier of 2,460 was taken from package (12) at a velocity of 40 meters/minute by means of driven rolls (13), constant tension device (14) applying a constant tension to yarn (11). This constant tension, which was sufficient to straighten but not substantially stretch the yarn, was 0.1 gram/denier.
As yarn (11) exited from driven rolls (13), it was passed through a bath of water (15) having a temperature of 95° C., in order that latent crimp in the yarn might be developed and subsequently evaluated. Idler pulley (19) kept yarn (11) below the surface of the water in the bath (15). Yarn (11) was carried through the bath (15) by means of pulley (16), which applied a second constant tension to yarn (11), this second tension being small enough to allow crimp in the yarn to develop fully. This second tension, which was 0.0004 gram/denier, was applied to yarn (11) by pulley (16) through magnetic coupling (17), which was driven by fixed speed motor (18). Thereby pulley (16) applied a constant tension to yarn (11), independent of its velocity.
Tachometer (20) sensed the velocity w 1 of yarn (11) as it passed driven rolls (13), and tachometer (21) sensed the velocity w 2 of yarn (11) as it passed over pulley (16).
Crimp in greige yarn was evaluated by passing yarn (11) directly from driven rolls (13) to pulley (16) as indicated by the dotted lines in FIG. 1.
After passing over pulley (16), yarn (11) was carried to waste disposal. If desired, yarn (11) could be re-entered into the process line.
With reference now to FIG. 2, there is illustrated a device and method for the continuous evaluation (computation) of crimp according to the present invention. Velocities w 1 and w 2 of the yarn were converted to voltages by means of tachometers (20) and (21), and the resulting signals were applied to the input of difference amplifier (22). The output of difference amplifier (22) was directed to the input of analog divider (23), along with the signal from tachometer (20). The output of analog divider (23) was applied to the input of variable gain amplifier (24), the output of which was directed to one channel of two-channel recorder (25), affording an instantaneous, visual recordation of the crimp (in %) along the length of the yarn. The output of variable gain amplifier (24) was also fed to the input of active low pass filter (26), the output of which was directed to the second channel of two-channel recorder (25), affording a recordation of average crimp (in %) along the length of the yarn.
The output of variable gain amplifier (24) could also be applied to a wave length discriminator (27), affording the determination of characteristic wave lengths of abnormal yarn variability, useful in diagnosing defects in the process by which the yarn is texturized. The output of variable gain amplifier (24) could also be applied to process controller (28), in order to control the crimp as the yarn is being texturized, thereby effecting a greater uniformity therein.
Although the present invention has been specified in detail with respect to certain preferred embodiments thereof, it is apparent to those of skill in the art that variations and modifications in this detail may be effected without any departure from the spirit and scope of the present invention, as defined in the hereto-appended claims.
1. Field of the Invention
This invention relates generally to textiles and particularly to a textile yarn testing method and apparatus.
2. Prior Art
As a result of the recent and rapid development of technology in the texturizing of synthetic textile yarns, it has become increasingly evident to the industry that test devices and methods once adequate fall far short of providing the information required to control today's processes. Standard methods and devices for measuring the crimp in a texturized yarn comprehend the taking of measurements on an isolated segment of the yarn and yield only average values for the amount of crimp therein. Instantaneous fluctuations in the amount of crimp, which may be periodic or non-periodic, and which result from the nature and treatment of the yarn prior to texturizing as well as inadequacies and disturbances in the texturizing procedure itself, can be evaluated only by means of a continuous method or device which operates upon a traveling yarn.
Accordingly, a continuous method and device have been eagerly sought after by the industry. As of late some continuous test methods have been proposed, as exemplified by those specified and defined in U.S. Pats. Nos. 3,333,467 and 3,471,702. In these prior methods, however, crimp is indirectly determined by measurement of related properties of the crimped yarn--e.g., tensile strength, or diffuse and specular light reflectance, or the amount of relaxation of tension on a band of crimped tow at a point between its passage through tensioning and relaxing rolls. In fine, a method and apparatus combining simplicity and economy of operation with directness of crimp measurement were heretofore unobtainable.
SUMMARY OF THE INVENTION
The direct method and the device of the present invention have basis in the observation that the amount of crimp in an isolated segment of yarn is generally determined by the following fundamental relationship:
Crimp (%) = [(l 1 -l 2 )/l 1 ] 100,
Wherein l 1 is the measured length of the yarn segment held under a tension sufficient to completely straighten the yarn but insufficient to elongate it; and l 2 is the measured length of the same yarn segment held under a tension which allows full development of the crimped or crinkled condition therein.
According to the present invention, adaptation of this fundamental principle to a yarn in motion is made as follows:
Yarn is made to travel under a first constant tension which is sufficient to completely straighten the yarn but insufficient to stretch it. The length of this yarn passing a given point per unit time is proportional to l 1 in the fundamental relationship. The yarn is then caused to travel under a tension which allows full development of the crimped or crinkled condition. The length of yarn passing a given point per unit time under these conditions is proportional to l 2 in the fundamental relationship. Since the length of a yarn segment passing a point per unit time equals the velocity of the yarn, the following relationship for a traveling yarn can be written:
Crimp (%) = [(w 1 -w 2 )/w 1 ] 100,
wherein w 1 is the velocity of the yarn traveling under a tension sufficient to straighten but insufficient to stretch it, and w 2 is the velocity of the yarn traveling under a tension which allows full development of the crimped or crinkled condition therein.
These velocities are continuously determined in the measurement phase of a preferred embodiment according to the present invention, and the crimp (in percent) is continuously calculated and recorded in the computation phase of the same embodiment.
Use of this invention affords a direct and instantaneous evaluation of the uniformity of a texturized yarn, and comprehends prompt quality control by immediate modification of process parameters to compensate for undesired variations in the crimp of a texturized yarn.
BRIEF DESCRIPTION OF THE DRAWING
For a more complete understanding of the present invention, reference should be made to the detailed description of the preferred embodiments thereof, which is set forth below. This description should be read together with the accompanying drawing, wherein:
FIG. 1 schematically depicts the measurement phase of a method and device according to the present invention; and
FIG. 2 diagrammatically represents the evaluation (computation) phase of the same method and device according to the present invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS
With particular reference to FIG. 1 of the drawing, a texturized continuous-filament nylon carpet yarn (11) having a denier of 2,460 was taken from package (12) at a velocity of 40 meters/minute by means of driven rolls (13), constant tension device (14) applying a constant tension to yarn (11). This constant tension, which was sufficient to straighten but not substantially stretch the yarn, was 0.1 gram/denier.
As yarn (11) exited from driven rolls (13), it was passed through a bath of water (15) having a temperature of 95° C., in order that latent crimp in the yarn might be developed and subsequently evaluated. Idler pulley (19) kept yarn (11) below the surface of the water in the bath (15). Yarn (11) was carried through the bath (15) by means of pulley (16), which applied a second constant tension to yarn (11), this second tension being small enough to allow crimp in the yarn to develop fully. This second tension, which was 0.0004 gram/denier, was applied to yarn (11) by pulley (16) through magnetic coupling (17), which was driven by fixed speed motor (18). Thereby pulley (16) applied a constant tension to yarn (11), independent of its velocity.
Tachometer (20) sensed the velocity w 1 of yarn (11) as it passed driven rolls (13), and tachometer (21) sensed the velocity w 2 of yarn (11) as it passed over pulley (16).
Crimp in greige yarn was evaluated by passing yarn (11) directly from driven rolls (13) to pulley (16) as indicated by the dotted lines in FIG. 1.
After passing over pulley (16), yarn (11) was carried to waste disposal. If desired, yarn (11) could be re-entered into the process line.
With reference now to FIG. 2, there is illustrated a device and method for the continuous evaluation (computation) of crimp according to the present invention. Velocities w 1 and w 2 of the yarn were converted to voltages by means of tachometers (20) and (21), and the resulting signals were applied to the input of difference amplifier (22). The output of difference amplifier (22) was directed to the input of analog divider (23), along with the signal from tachometer (20). The output of analog divider (23) was applied to the input of variable gain amplifier (24), the output of which was directed to one channel of two-channel recorder (25), affording an instantaneous, visual recordation of the crimp (in %) along the length of the yarn. The output of variable gain amplifier (24) was also fed to the input of active low pass filter (26), the output of which was directed to the second channel of two-channel recorder (25), affording a recordation of average crimp (in %) along the length of the yarn.
The output of variable gain amplifier (24) could also be applied to a wave length discriminator (27), affording the determination of characteristic wave lengths of abnormal yarn variability, useful in diagnosing defects in the process by which the yarn is texturized. The output of variable gain amplifier (24) could also be applied to process controller (28), in order to control the crimp as the yarn is being texturized, thereby effecting a greater uniformity therein.
Although the present invention has been specified in detail with respect to certain preferred embodiments thereof, it is apparent to those of skill in the art that variations and modifications in this detail may be effected without any departure from the spirit and scope of the present invention, as defined in the hereto-appended claims.