Title: Method and apparatus for determining parameters of a staple length distribution of fibers in yarn slivers

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1. An improved method for determining parameters of a staple length distribution of fibers in a yarn sliver wherein an elongate length of yarn sliver is being fed to and through a first pair and a second pair of drafting rolls each spaced apart from each other and the second pair rotating at a greater speed than said first pair, and wherein also a signal representative of the drafting force exerted upon the sliver at any one time is continuously generated and fed as an input of measurement to a recorder; the improved method comprising:

1. initially spacing the pairs of drafting rolls apart from each other at a distance greater than the longest fiber lengths in said yarn sliver;

2. then moving one of the pairs of drafting rolls toward the other pair of drafting rolls until first the longer fibers and then the shorter fibers in the yarn sliver extending between said drafting roll pairs bridge the gap between the nips of the two pairs of drafting rolls;

3. feeding the signal representative of the drafting force to the Y-axis of a X-Y recorder;

4. continuously measuring the continuing changing distance between the drafting roll pairs and generating as a consequence a signal representative of said continuing changing distance and feeding said signal as an input to the X-axis of said X-Y recorder; and

5. drawing a drafting force curve representative of said parameters on said X-Y recorder from said Y-axis and X-axis signal inputs.

2. An improved method as defined in claim 1, wherein a tangential line is drawn through the linear portion of the ascending curve, which results from the bridging of the gap by first the longer and then the shorter fibers in said yarn sliver, the X-coordinate of the intersection of the tangential line with the X-axis thereby determining the parameter of average effective staple length of the fibers in the yarn sliver.

3. An improved method as defined in claim 1, wherein a tangential line is drawn through the linear portion of the ascending curve as drawn and as resulting from the bridging of the gap by first the longer and then the shorter fibers in said yarn sliver;

said tangential line then being extended back and thus extrapolated to zero distance on the X-axis between said two pairs of drafting rolls, said tangential line thus intercepting with the resulting re-located Y-axis; and

determining the square of the coefficient of variation from the ratio of the area between said drawn, extended tangential line and the drafting force curve to the total area under the drafting force curve including the area under the extended tangential line.

4. An improved method as defined in claim 2, said tangential line then being extended back and thus extrapolated to zero distance on the X-axis between said two pairs of drafting rolls, said tangential line thus intercepting with the resulting re-located Y-axis;

designating the intercept of the drawn extended tangential line with the re-located Y-axis as 100% value and constructing a line from the location of 50% value on the re-located Y-axis and forming a tangent of said constructed line with the drafting force curve, the intersection of the thus constructed tangential line with the X-axis thereby determining the upper half mean length of the fibers in the yarn sliver, the ratio of the average effective staple length to the upper half mean length being the index of length uniformity.

5. An improved method as defined in claim 2, said tangential line then being extended back and thus extrapolated to zero distance on the X-axis between said two pairs of drafting rolls, said tangential line thus intercepting with the resulting re-located Y-axis;

designating the intercept of the drawn extended tangential line with the re-located Y-axis as 100% value and constructing a horizontal line from the location of the 2.5% value on the re-located Y-axis to where the horizontal line intersects with the drafting force curve and thereby determining from the X-coordinate of such intersection the 2.5% span length of the fibers in the yarn sliver.

6. Improved apparatus for determining parameters of a staple length distribution of fibers in a yarn sliver being fed through the apparatus, the apparatus including

a. a recorder;

b. a first and second pair of drafting rolls, each pair spaced apart from the other pair;

c. drive means for rotating the first and second pair of drafting rolls with the second pair of drafting rolls being rotated faster than the first pair of drafting rolls; and

d. means for continuously measuring the drafting force exerted at any one time upon a yarn sliver being fed to and between the two pairs of drafting rolls and generating a signal representative of the measured drafting force at any one time and for feeding said signal as an input to said recorder;

the improved apparatus in combination comprising:

1. means for moving one of the pairs of drafting rolls toward the other pair while a yarn sliver is being fed to and between the two pairs of drafting rolls;

2. said recorder defining a X-Y recorder;

3. means for feeding said drafting force signal to the Y-axis of said X-Y recorder; and

4. means for continuously measuring the continuing changing distance between the two pairs of drafting rolls and generating a signal representative of the continuing changing distance and for feeding the signal as an input to the X-axis of said X-Y recorder;

5. said X-Y recorder including means for drawing a drafting force curve representative of said Y-axis and X-axis signal inputs.

7. Improved apparatus as defined in claim 6, wherein said means for continuously measuring the continuing changing distance between the two pairs of drafting rolls and generating a signal comprises a rectilinear potentiometer and signal conditioning circuit means operatively connected to said rectilinear potentiometer and said X-Y recorder.

Other info:

Inventors: Watson, Robert L. (Kingsport, TN, US)
Finley, Donald L. (Mt. Carmel, TN, US)

Application Number: 814563
Filing Date: 1977-07-11
Publication_date: 1978-05-09
Assignee: Eastman Kodak Company (Rochester, NY)
Primary Class(es): 73/160 19/261
Other Classes:
US Patent Ref:

1130880	Mar, 1915	Blackwood	19/261.
2885740	May, 1959	Thompson et al.	19/261.
3354711	Nov, 1967	Sevey	73/160.

Other Refs:
Primary Examiner: Queisser, Richard C.
Assistant Examiner: Gorenstein, Charles
Attorney: Dunn; Malcolm G., Reece, III; Daniel B.