The present invention relates to ginning of cotton and especially to the ginning of Upland cotton in a roller gin apparatus. Roller ginning has heretofore been confined to extra long staple cottons such as the American Pima variety which have very few short fibers. Roller ginning as opposed to saw ginning is used on these varieties to preserve their extra fine spinning qualities, although the roller ginning process has been much slower and therefore more costly than saw ginning.
Current roller gins include three vital elements: a ginning roller covered with fibrous material, a stationary knife pressed against the ginning roller surface with considerable pressure, and a rotary knife about two and three-quarters inches in diameter having up to six radial blades equally spaced from each other. Seed cotton is dropped onto the surface of the rotating ginning roller, which carries the cotton to the stationary knife drawing the fibers under the edge of the knife. The knife edge strips back the seeds thus pulling the fibers from the seed. As the seeds accumulate on the edge of the stationary knife, the blades of the rotary knife periodically sweep the seeds away from the stationary knife.
The diameter of the rotary knife must be limited so that the tips of the blades of the knife move away from the surface of the stationary knife at a separation greater than the size of the cotton seeds at a distance from the fiber gripping point at the stationary knife tip that is less than the length of the desirable fibers, such that partially ginned seed will be drawn back to the tip of the stationary knife for further ginning. Thus the function of the rotary knife has been to sweep seeds that have been fully ginned away from the knife while allowing seeds that have desirable fiber remaining to be drawn back by those fibers to the stationary knife tip for further ginning.
Upland cotton contains many shorter fibers called linter fibers which are about ⅛th inch long, as well as some intermediate length fibers. Current technology allows the seeds to be drawn directly to the tip of the stationary knife which allows the short fibers, on Upland cotton, to be pulled from the seed, thus making the quality of the cotton less valuable due to its short fiber content. The USDA ginning lab at Mesilla Park, NM has conducted experiments in an attempt to increase the ginning capacity of roller gins. These experiments have been successful to a large extent and they have been extended to include the ginning of Upland cotton, which is by far the majority of cottons grown around the world and are normally saw-ginned because of the much greater speed of saw ginning and because the quality of the Upland cotton for most uses has not been as crucial as for Pima type cottons. Although these experiments have demonstrated that Upland cottons may be roller ginned at much higher rates than previously thought possible with less fiber breakage, these experiments have not been able to fully overcome the problem of too many short fibers in Upland ginned cotton.
It is an object of the present invention to reconfigure the components and speeds of the current roller gins to control the distance the cotton seeds are held away from the fiber grip point at the tip of the stationary knife, thereby controlling the minimum length of the fiber ginned. A second object of this invention is to more uniformly gin the seed to reduce the amount of desirable fibers remaining on the seed exiting the process.
Apparatus embodying features claimed in the present invention are depicted in the Figures attached hereto wherein:
It is well known that in the prior art the ginning roller R is approximately fifteen inches in diameter with a fibrous surface S which rotates towards the tip T of the stationary knife K, or counter clockwise in
In an embodiment, the rotary knife 16 of the present invention is smaller in diameter than a conventional rotary knife, being less than about 5 centimeters in diameter, and has more blades 17 namely eight to twelve blades. In the illustrated embodiment twelve blades 17 are equidistantly distributed about the axis of the rotary knife 16. Knife 16 is mounted in conventional adjustable bearings so that it may be adjusted relative to the tip 14. Knife 16 is also rotated at a speed such that the speed of the tips of the knife blades more nearly match the speed of surface 12 of the ginning roller 11, thus a subsequent blade tip will pass the stationary knife as the surface of the roller moves relative to the stationary knife a distance of less than about 3 centimeters. As seed cotton is carried toward stationary knife tip 14 by the ginning roller 11, blades 17 engage the seed and carry it onto the upper surface of knife 13. As the knife surface and arc of rotation of blades 17 diverge the seed is released. This release point is selected in accordance with the desired length of the fiber such that if desirable fiber remains attached to the seed, the nip between the knife point 14 and ginning roller 12 still contains fiber, thus the seed is pulled back toward knife point 14 when released by blade 17. Unlike conventional roller gins, however, the seed is not permitted to return to the knife tip 14. Rather, the next knife blade 17 engages the seed and returns it to the release point thereby separating additional desirable fibers without allowing shorter fiber to be removed from the seed. If at that point desirable fiber remains attached to the seed and is engaged in the nip, the seed is again drawn back toward the nip until engaged by the next blade. The process continues until substantially all of the fiber of the desired length is removed and the seeds are released.
It may be seen with upland cotton that the amount of linter fiber and intermediate length fiber ginned with the desirable length fiber may be reduced greatly by selectively choosing the minimum approach to the tip of the stationary knife of the seed as it is drawn back toward the nip by the fiber. Simply put, the speed and spacing of the blades on the rotary knife are to be such that the seed cannot completely return to tip 14, thus the shorter fibers cannot be entrained on ginning roll surface 12 when the seed is drawn back toward the tip 14 by the longer fibers. Thus, primarily the longer fibers will be ginned and the shorter fibers will be left on the upland cotton seed for possible subsequent removal.
The limits of this feature of the proposed invention may be defined by the formula:
RKBS<2SR*RKSS/GRSS
Where, the rotary knife circumferential blade spacing (RKBS) is less than 2-times the seed release distance from the tip of the stationary knife (SR) multiplied by the rotary knife surface speed (RKSS) and divided by the ginning roller surface speed (GRSS).
This formula theoretically defines the limit of the conditions that assures that all the fiber separation from the seeds (ginning) occurs by the blades of the rotary knife pressing against the surfaces of the seeds once the seeds pass the tip of the stationary knife at entry. However to fully receive all the benefits of this feature of the present invention, the formula should read:
RKBS<(2SR-2MD)*RKSS/GRSS
Where Rotary knife circumferential blade spacing is less than 2-times the seed release distance from the tip of the stationary knife minus 2-times the minimum distance the seed surfaces are allowed to approach the tip of the stationary knife (MD) times the rotary knife surface speed divided by the ginning roller surface speed.
In these formulas all the factors, except one, can be easily measured. This factor is the seed release distance from the tip of the stationary knife. This must be determined empirically from tests of specific cultivars. Thus long staple cotton and shorter varieties will have different interstitial separation of the components to maximize recovery of the desirable fibers and minimize recovery of fibers of undesirable length. The obvious and important effect of too great a seed release distance is excessive unginned desirable fiber left on the seed. The release distance is not only influenced by the geometry of the components of the roller gin but also by the speed relationship between the rotary knife and the ginning roller. Tests with current roller ginning technology have shown that while increasing the speed of the rotary knife relative to the ginning roller increases ginning rate, the “carryover” (partially ginned seeds), increases to unacceptable levels The present invention reduces this problem by shortening the seed release distance from the nip point at the tip of the stationary knife. To accomplish this, the diameter of the rotary knife may be reduced, the stationary knife contour may be modified and the ginning roller diameter may be reduced.
As an example, assume a 2″ diameter rotary knife with ten blades running at the same surface speed as the ginning roller and that there is no slippage between the fibers and the ginning roller The circumference of the rotary knife blades would be 6.3″. With 10 blades, the circumferential distance between blade tips would be 0.63″. As the rotary knife and ginning roller turn, the seed would move toward the stationary knife tip the same amount as the succeeding blade would move toward the seeds after the previous blade released the seeds. Therefore the seeds would move toward the tip of the stationary knife a distance of 0.315″ before being contacted by the next blade. With these modifications, including a 2″ diameter rotary knife and offset stationary knife, the release point of the seeds from the tip of the stationary knife could be set as close as approximately 0.50″. Therefore the closest point the seeds could approach the tip of the stationary knife after the initial entry of the seeds would be 0.185 or greater by increasing the rotary knife speed relative to the ginning roller or moving the rotary knife relative to the stationary knife. Accordingly, fibers less than this length, such as found in Upland Cotton, would not be ginned with the longer more desirable fibers after the initial pass of the seed over the tip of the stationary knife.
Once the conditions have been established of the optimum design, settings and speeds of the apparatus of the present invention in which a fixed seed release distance from the tip of the stationary knife has been established, the nose of the stationary knife may be modified to assure that the blades of the rotary knife contact the seeds about midway of their width rather than higher up on the seed surface which might tend to crush the seed or abrade the surface of the seed. This modification shown in
Another desirable outcome of the present invention is that the force pressing the ginning roller against the stationary knife is lessened when the fibers are merely held between the stationary knife and the ginning roller surface while the blades of the rotary knife “roll” the seed away from the fibers to cause ginning as compared with current technology ginning with the seed primarily stripped away from the fibers by the tip of the stationary knife. The high pressures required between the stationary knife and the ginning roller to obtain high capacity ginning with current technology generates greater amounts of heat in the ginning roller and accelerates wear of the fiber surface of the ginning roller which necessitates the use of additional means to keep the ginning roller from overheating including spraying atomized water onto the surface of the ginning roller. The lower pressures allowable with the present invention at least partially alleviate the need for artificial cooling of the ginning roller and extend the life of the ginning roller surface. Also the lower pressures reduce the power to drive the ginning roller. However, the invention would result in an increase in power to drive the rotary knife, but there would be a net reduction in overall power use. While this invention will primarily benefit the ginning of Upland cottons, important features of this invention will also benefit the ginning of extra long staple cottons.
While the foregoing addresses means to control the minimum fiber length ginned after a blade of the rotary knife passes the tip of the stationary knife, the present invention may also include apparatus and means to reduce the time the seed cotton remains at the tip of the stationary knife prior to the first rotary knife blade passing the tip of the stationary knife. In the prior art, rotary knife roller gins feed at least some of the seed cotton onto the surface of the ginning roller several inches away from the stationary knife, thus allowing a significant amount of seed exposure directly against the tip of the a stationary knife before a rotary knife blade contacts the cotton resulting in the removal of much short fiber. Therefore in another embodiment of the present invention, a slide panel is incorporated which limits the distance and time the ginning roller surface movement can hold the seed cotton against the tip of the stationary knife before a blade of the rotary knife moves the seed away from said tip. The extreme limit of this application is shown in
Locating this slide panel in close proximity to the rotary knife creates additional advantages over current state of the art. Currently ginning rollers revolve at surface speeds considerably faster than rotary knife blade tip speeds. This, coupled with the distances the seed cotton travels on the ginning roller before reaching the rotary knife, causes the seed cotton to back up behind the blades of the rotary knife. Thus when a blade passes the tip of the stationary knife, this concentration of seed cotton instantly starts its ginning action which continues until the next blade sweeps the seeds away from the tip of the stationary knife. Consequently over ginning occurs before the seeds first pass beyond the tip of the stationary knife. With our slide panel set closely to the rotary knife, the seed cotton is fed to the ginning roller by the rotary knife blades. The smaller pockets of our rotary knives control the feed rate when the slide panel is set close to the rotary knife and feed small “batches” of cotton for more uniform and shorter exposure ginning action. Also less seed cracking occurs as the seed are less densely concentrated when the blades must converge on the tip of the stationary knife.
It may be advantageous to locate the end of the slide panel at a distance greater than one seed diameter from the rotary blade tips, as shown at 21a, to reduce the likelihood of seed breakage between the tips of the rotary knife blades and the slide panel. Other locations of the slide panel farther from the tips of the rotary knife blades can be empirically determined to reduce the ginning of short fiber while optimizing the ginning rate. Factors influencing the optimum slide panel location involve the seed cotton characteristics, the speeds of the rotary knife and ginning roller and the blade spacing on the rotary knife.
In current roller ginning there is invariably a certain amount of seeds that slip through the ginning process without being properly ginned. To prevent the loss of valuable fiber, seed “reclaimers” are used to pluck the seed with valuable fiber from the seed exiting the ginning process. This reclaimed seed is then passed back to join the seed cotton entering the ginning process. Unfortunately, these seed reclaimers pick up much already fully ginned seed that is entrained in the seed reclaimed with excess fiber. In current practice the entrainment of the well-ginned seed along with the reclaimed seed with fiber is ejected by the cleaners in the current feeders mounted over the gin stands whose function is to clean trash from the cotton seed as well as to uniformly feed the cotton seed to the gin stand. Additionally the recirculation of the already well-ginned seed is doubly damaging to our current invention as the re-ginning of the already adequately ginned seed increases the likelihood of the shorter fibers on these seeds increasing the short fiber content of the lint which is in direct opposition to the main object of this current invention.
In light of the above problems with current over-ginning system practices that are not conducive to reducing short fiber content, the current invention may include novel gin plant system designs to better preserve fiber staple length and uniformity. A central concept of this gin plant design is utilization of a first stage and second stage of ginning which are distinct from each other. Once the seed cotton is passed through the first stage, any further ginning needed is done in the second stage. This places different requirements on the first stage feeders as compared to the second stage feeders. The first stage feeders over the gin stands may be the traditional feeders whose function is not only to regulate the seed cotton being fed to the gin stands but to also clean the seed cotton with traditional screens and grids and extractors to remove trash while containing the fiber-covered seed cotton locks.
The feeders over the second stage gin stands have different requirements. Presumably the partially ginned seed does not require additional cleaning and therefore the second stage feeders do not need the cleaning elements per se. On the other hand, to maintain a high lint uniformity index in the second stage requires that as many of those already sufficiently ginned seeds as possible should be removed prior to the second stage ginning. An efficient location for the second stage clean seed removal is at the entry to the feeder over the second stage gins. Therefore feeders for the second stage gins optimally might contain a clean seed separator feature along with metering means to deliver a uniform flow of the partially ginned seed cotton to the gin stand.
The second stage gin stands should utilize the features described herein above to minimize short fiber content albeit that adjustments may be made to accommodate the different characteristic of the partially ginned seed.
Seeds exiting the second stage gin stand(s) may still contain excess desirable fiber. These seeds may be passed through a conventional seed reclaimer or a seed separator as described above before being returned to the feeder over the second stage gin stand(s).
Referring to
Referring to
While the present invention has been shown in multiple embodiments, it is not so limited but is limited only by the scope of the appended claims as properly construed.
This application claims the benefit of U.S. provisional patent applications 60/708,452 filed Aug. 16, 2005, 60/755,215 filed Dec. 30, 2005 and 60/764,710 filed Feb. 2, 2006 which is relied on and incorporated herein by reference.
Number | Date | Country | |
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60708452 | Aug 2005 | US | |
60755215 | Dec 2005 | US | |
60764710 | Feb 2006 | US |