Patent Application
20160222552
Fiber length measurement is a longstanding problem in textile and para-textile materials characterization. It is a particularly challenging task in applications using natural fibers, such as cotton. Among all measured characteristics of cotton and most other fibrous materials, length has typically been considered the most crucial. The market value and end-use of the fiber along with the processes adopted for its transformation are largely determined by its length properties. Unfortunately, reliably characterizing the length distribution in a bulk fiber sample is rather challenging, and existing solutions present multiple biases and shortcomings. One major challenge stems from the intrinsic variability of single fiber lengths, which is typically determined by complex interactions involving genetic, environmental, and processing factors. As a result, obtaining a representative sample from a bulk fiber lot can be troublesome.
Currently, there are two major approaches for addressing this problem. One approach is fiber bundle sampling, and the other approach is single fiber measurement. Fiber bundle sampling includes clamping a bundle, or “beard,” of parallel fibers by using a set of combs and brushes. The beard is scanned for length measurement, or to determine the “fibrogram.” Due to the sample clamping, the shortest fibers are not scanned, which leads to a bias of the length distribution toward the long fibers. In a single fiber measurement approach, fibers are individualized using an aeromechanical opener or separator and individually conveyed through a set of optical sensors that generate electrical signals proportional to the fiber length. One major shortcoming of current methods using the single fiber measurement approach is that in the process of measuring fibers, breakage typically occurs at the mechanical opening, which biases the measured length distribution toward the shorter fibers.
Accordingly, systems and methods are needed for individualizing fibers and measuring the individual fibers without breaking the fibers or biasing the measurements.
Various implementations include systems and methods of using electrostatic forces to separate samples into individual fibers with minimal to no breakage and align the individual fibers with minimal handling. These systems and methods allow for testing, such as measuring the length, of individual fibers without the biases caused by breakage or bundling that are present in prior art systems and methods. These systems and methods may also be useful in applications requiring fiber alignment with minimal material handling.
For example, various implementations include a pair of nip rollers and a collector that are spaced apart from each other to define an air gap therebetween. The nip rollers are grounded or negatively charged, for example, and the collector is positively charged to create an electrostatic field in the air gap. The electrostatic field separates the fibers, elongates the fibers end to end, and urges the fibers toward the collector. In other implementations, the nip rollers may be positively charged and the collector grounded or negatively charged to create the electrostatic field in the air gap. In certain implementations, the system may also include a power supply (e.g., a high voltage DC power supply) for creating a voltage difference between the nip rollers and collector.
In certain implementations, the collector is a collection roller that has an axis of rotation that is parallel to the first and second axes of rotation, and the direction of rotation of the collection roller is the same as the direction of rotation of the second nip roller, which is disposed below the first nip roller. The collector may also include a plate or other suitable collection device, according to other implementations.
In addition, the system may also include an imaging system that has a field of view that includes at least a portion of the air gap between the exit side of the nip rollers and the collector. The imaging system receives image signals of each fiber passing through the air gap, and the image signals may be used to measure a length and/or diameter of each fiber or to inspect each fiber. The imaging system may further include one or more digital cameras and one or more light sources, for example.
The system may also include a suction device, such as a vacuum collection device, that is disposed adjacent an exit side of the collector. The suction device urges each fiber passing over or through the collector from an entry side of the collector to the exit side of the collector to enter the suction device for collection after one or more images of each fiber is received.
Furthermore, the system may also include additional pairs of nip rollers disposed upstream of the first and second nip rollers that receive a beard of fibers and feed the fibers toward the entry side of the first and second nip rollers.
Various implementations further include a method of separating and aligning fibers. The method includes: (1) rotating a pair of nip rollers, an exit side of the nip rollers being spaced apart from an entry side of a collector to define an air gap therebetween; (2) creating an electrostatic field in the air gap; and (3) feeding a beard of fibers between the nip rollers. The electrostatic field separates the fibers, elongates the fibers end to end between the exit side of the nip rollers and the entry side of the collector, and urges the fibers toward the collector. A width of the air gap from the exit side of the nip rollers to the entry side of the collector is larger than a maximum length of any fiber within the beard of fibers.
In certain implementations, the method also includes capturing image signals of the separated and elongated fibers in the air gap with an imaging device that has a field of view that comprises at least a portion of the air gap. In addition, the method may also include identifying a length and/or a diameter of each separated fiber using the image signals.
Other systems, methods, features, and/or advantages will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be protected by the accompanying claims.
The components in the drawings are not necessarily to scale relative to each other and like reference numerals designate corresponding parts throughout the several views:
Various implementations include systems and methods of using electrostatic forces to separate samples into individual fibers with minimal to no breakage and align the individual fibers with minimal handling. These systems and methods allow for testing, such as measuring the length, of individual fibers without the biases caused by breakage or bundling that are present in prior art systems and methods. These systems and methods may also be useful in applications requiring fiber alignment with minimal material handling.
In particular,
Furthermore, the system 10 may also include additional pairs of nip rollers 16a, 16b, 19a, 19b disposed upstream of the upper 12a and lower nip rollers 12b. The nip rollers 16a, 16b, 19a, 19b receive a beard of fibers B and feed the fibers toward the entry side 11 of the upper 12a and lower nip rollers 12b. In other implementations, more or less than three pairs of nip rollers may be used in the apparatus. Implementations having more than one pair of nip rollers may provide better fiber individualization than implementations having only one pair of nip rollers.
The nip rollers 12a, 12b, 16a, 16b, 19a, 19b are physically coupled to one or more support rails that support the axis of rotation of each of the nip rollers 12a, 12b, 16a, 16b, 19a, 19b. For example, in the implementation shown in
In addition, in some implementations, the rail(s) includes an electrically conductive material, such as aluminum, such that the nip rollers are electrically coupled to each other through the rails and/or through contact with each other. The collection roller 14 is mounted separately from the nip rollers 12a, 12b, 16a, 16b, 19a, 19b with sufficient electrical insulation to prevent electrostatic discharge between the nip rollers 12a, 12b, 16a, 16b, 19a, 19b and the collection roller 14.
The power supply 17 is in electrical communication with at least one of the nip rollers 12a, 12b, such as the lower nip roller 12b, and the collection roller 14. The power supply 17 creates a positive electrical charge on the collection roller 14 and a negative electrical charge on the lower nip roller 12b. The voltage difference between the nip rollers 12a, 12b and the collection roller 14 creates an electrostatic field in the air gap 13. As the fibers F pass through the nip rollers 12a, 12b, the electrostatic field causes the fibers F to separate from each other in the air gap 13, elongate end to end between the exit side 15 of the nip rollers 12a, 12b and an entry side 21 of the collection roller 14, and move toward the positively charged collection roller 14. The power supply 17 may be, for example, a DC high voltage power supply, according to certain implementations.
In some implementations, the power supply 17 may be electrically coupled to the support rail(s) physically coupled to the nip rollers 12a, 12b, 16a, 16b, 19a, 19b and/or to one or more of nip rollers 12a, 12b, 16a, 16b, 19a, 19b. In addition, in other implementations, one or more of the nip rollers and/or rails may be grounded (instead of negatively charged). And, in other implementations, the collector may be grounded or negatively charged, and the nip rollers and/or rails may be positively charged. In one such implementation, the motor and control board are insulated and protected from being influenced by the positive charge.
Furthermore, as shown in
The width of the air gap 13 is selected such that it is greater than the maximum expected length of a fiber F to be passed through the system 10. This allows the fiber F to be elongated, or extended, to its full length and oriented end to end between the exit side 15 of the nip rollers 12a, 12b and the entry side 21 of the collection roller 14. In addition, the size of the air gap 13 may be based on the minimum length that allows a fiber F to travel through the air gap 13 and be captured by the imaging system 16 and that allows for proper installation of the imaging system 16 and light source 24, according to some implementations. For example, in certain implementations, the air gap 13 may be between about 90 and about 100 millimeters.
The imaging system 16 has a field of view that includes at least a portion of the air gap 13 between the nip rollers 12a, 12b and the collection roller 14. The imaging system 16 receives image signals of each fiber F passing through the air gap 13, and these image signals may be used to measure a length or diameter of or inspect each fiber F. The imaging system 16 may include one or more digital cameras, according to certain implementations. In other implementations, the imaging system 16 may include one or more line scan cameras or optical sensor arrays. In addition, the system 10 may include one or more light sources 24 to illuminate at least a portion of the field of view of the imaging system 16, according to certain implementations. Light sources 24 may include one or more light emitting diodes (LEDs) or other suitable light source.
The suction device 18 is disposed adjacent an exit side 23 of the collection roller 14. The suction device 18 urges fibers F passing over the collection roller 14 from the entry side 21 of the collection roller 14 to the exit side 23 to enter the suction device 18 for collection after one or more images of each fiber F is collected. According to certain implementations, the suction device 18 may include a vacuum collection device. For example, the vacuum collection device may include a Venturi suction device.
In certain implementations, the computer processing unit 22 may also be configured for controlling the speed of rotation of one or more motors 25 driving the rotation of one or more of the nip rollers 12a, 12b, 16a, 16b, 19a, 19b and the collection roller 14, the suction power of the suction device 14, the voltage difference between the nip roller 12a, 12b and the collection roller 14, and/or the light intensity of the light source 24. For example, the processing unit 22 may be configured to adjust these parameters based on the image signals received from the imaging device 16. For example, if the image signals indicate that the fibers F are not passing through the air gap 13 individually or aligned as expected, the computer processing unit 22 may adjust the voltage and/or speed of the rollers 12a, 12b, 16a, 16b, 19a, 16b, 14 and/or the suction power of the suction device 18. In other implementations (not shown), one or more additional computer processing units may be provided to perform one or more of these functions.
A second motor (not shown) is configured for driving rotation of the fringe roller 210, and the processing unit 22 is configured for controlling the rotation of the second motor. To process a fiber F through the system 200, the processing unit 22 instructs motor 25 to rotate the nip rollers 12a, 12b until a leading end of fiber F exits the nip rollers 12a, 12b at a length sufficient to be controlled by the fringe roller 210. For example, this length may include the leading end being in contact with a surface of the fringe roller 210 or in contact a certain amount of the surface of the fringe roller 210. The processing unit 22 then stops rotation of nip rollers 12a, 12b and directs the second motor to rotate the fringe roller 210 a half revolution to capture the leading end of fiber F and another half revolution to present the leading end of fiber F into the air gap 13. The cycle repeats after image signals for the fiber F have been received by the imaging device 16. In some implementations, motor 25 may control the rotation of fringe roller 210 (not shown). In addition, in some implementations, motor 25 and/or the second motor may be controlled by another processing unit (not shown).
In addition, the collector in system 200 shown in
In some implementations, motor 25 may control the rotation of nip rollers 314a, 314b, and the nip rollers 12a, 12b may be driven by the aprons 301a, 301b.
The air gap 13 is defined between an exit side 315 of nip rollers 314a, 314b and collection plate 214. In this system 300, nip rollers 12a, 12b are not charged, but at least one of the nip rollers 314a, 314b are grounded or negatively charged, and the collection plate 214 is positively charged. As noted above in relation to
The above-described implementations create an electrostatic field within an air gap, and the electrostatic field separates, aligns, and allows for inspection and collection of fibers passing through the air gap. However, it should be understood that the systems and methods described above may be used with other types of materials other than fibers, such as dust particles and impurities.
Various modifications of the devices and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative devices and method steps disclosed herein are specifically described, other combinations of the devices and method steps are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein. However, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms.
This application claims priority to U.S. Provisional Patent Application No. 62/109,996 entitled “Systems and Methods for Electrostatically Individualizing and Aligning Fibers,” filed Jan. 30, 2015, which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62109996 | Jan 2015 | US |
