Apparatus and method for controlling the amount of trash in lint
An apparatus and algorithm for controlling the operation of a lint cleaner in a cotton gin having motorized grid bars, in which any one of the grid bars can be positioned in an engaged or disengaged position. When the grid bar is in the engaged position it functions as a lint cleaning instrument on a lint cleaning machine. When it is in the disengaged position it does not participate in the active cleaning process.
This invention relates to the lint cleaning process and machinery used in cotton processing facilities such as cotton gins. The invention provides an apparatus and methods for controlling the amount of cleaning performed during the lint cleaning process, thus optimizing the cotton producer's income by reducing waste and damage to the lint.
BACKGROUND OF THE INVENTIONLint cleaning machines, used in cotton processing facilities, employ stationary grid bars to remove trash, leaves and other particles from the lint during the cleaning process, as described in W. S. Anthony and William D. Mayfield; Cotton Ginners Hand Book United States Department of Agriculture; Agricultural Research Service Agricultural Handbook Number 503; Copyright December 1994 . The lint cleaner uses a bank of circular saws to propel a thin preconditioned layer of lint through the lint cleaning machine. The lint fibers, which may contain leaf fragments, seed fragments, sticks and other particles designated herein as trash, are fed onto the fine teeth of the saws, which are rotating at the speed of a few hundred revolutions per minute. During one half of a revolution around the cleaner, the lint fibers pass by a set of five or more closely positioned bars with sharp edges, referred to as grid bars. These grid bars are positioned perpendicular to the rotation of the saws, with the edges very close to the saws. As the lint passes by the grid bars, most of the trash in the lint is dislodged by the grid bars and sucked into a trash air pipe, which then feeds the trash to a trash heap outside the gin house. The saws continue pulling the lint through most of the revolution. The lint is then separated from the saws by a cylindrical brush and from there is conveyed to a bale press for packing. The bale press packages the lint into 500 pounds bundles of pressed lint called bales.
The grid bars are long metal bars with a sharp leading edge used to remove the trash from the lint upon contact. It has been demonstrated that during the cleaning process the grid bars also remove some usable lint from the rotating saws, causing a loss of lint to the producer. It has been further determined that the amount of trash and lint removed during the cleaning process is dependent on many factors. These include the mechanical positioning of the grid bars, the sharpness of the cleaning edge, the condition of the lint, the lint properties, the mechanical properties of the saws, their speed and other factors. It has been demonstrated that the loss of useable lint can decreased by reducing the amount of cleaning the machine performs. It has also been demonstrated that reducing the amount of cleaning results in longer fibers and reduction in short fibers. Reduction in the lint cleaning thus results in the improvement of the quality of the cotton. In many situations, the cotton producer is interested in minimizing the loss of lint during the cleaning process, even if it will result in higher trash content. Existing lint cleaners do not provide a method to vary the amount of cleaning the machine performs.
U.S. Pat. No. 5,909,786 by Anthony, describes an apparatus to reduce fiber waste by lint cleaners. Anthony's invention describes a method where the space between the grid bars is closed by shroud members, while the grid bars themselves remain stationary during the cleaning process. The disadvantage of Anthony's invention is that it does not remove sheet metal edges from contacting the lint, thus continuing to cause damage to the fibers. Also, Anthony's invention is complex to build and operate.
Some trash particles are not removed by the lint cleaner. They remain with the lint through out the remainder of the cleaning process. The amount of trash remaining in the lint will be measured as a leaf count. The leaf count is one of the parameters used to determine the quality of the lint.
SUMMARY OF THE INVENTIONAn apparatus and algorithm for controlling the operation of a lint cleaner in a cotton gin having motorized grid bars, in which any one of the grid bars can be positioned in an engaged or disengaged position. When the grid bar is in the engaged position it functions as a lint cleaning instrument on a lint cleaning machine. When it is in the disengaged position it does not participate in the active cleaning process. The grid bars can be engaged or disengaged in the cleaning operation by electrical, pneumatic or hydraulic actuators, which are activated by the system processor. The operator interface device, which contains at least a trash level indicator and a data entry device, allows the operator to enter the desired cotton gin output trash level. An imaging device, such as a digital camera or a scanner, measures the amount of trash present in the lint before cleaning plus another imaging device, like a digital camera or a scanner, measures the amount of trash remaining in the lint at the cotton gin output after the lint cleaning process. The signal received from the imaging devices is analyzed and the trash content is determined. The invention algorithm determines which grid bars should be engaged in the cleaning process to obtain the operator's desired output trash content. An alternate algorithm can be used to calculate the most cost effective cleaning process based on commodity pricing, trash discount or quantity of lint wasted.
This invention further comprises an automatic control for lint cleaning machines where the cleanliness of the lint is monitored by an imaging device such as a camera or scanner, and an assembly of motorized bars. The motorized grid bars are dynamically configured by the invention's algorithm to produce the desired level of cleaning.
The inventive system is represented in
The grid bars may also be equipped with a lint-retaining member such as retention bars or retention brushes or both, as shown in
This invention also includes a user interface terminal where the operator has the ability to set the desired output trash level, and also to adjust other system parameters. They can also view the condition of the cleaning process in regards to the position of each of the grid bars. The operator can reposition the grid bars in a manual mode by commanding the processor to engage or disengage any selected grid bar at any time.
This invention includes a processor, which executes a sequence of commands, embedded in its memory, constituting the algorithm of the invention. The processor receives inputs from the optical sensing devices, it also receive instructions and or set point from the operator. It uses these inputs to determine if it is necessary for one or more of the grid bars to be repositioned to the engaged or disengaged position. If there is a need the processor can use these inputs to tell which of the grid bars need repositioning.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention of lint cleaning machine in a cotton processing facility such as cotton gin, is illustrated in
As part of this invention shown in
As shown in
Part of this invention is the design of the grid bar motors and actuators as illustrated in
The angle of rotation ι of the grid bar 7 is calculated in the following equation (1):
ι=(w/360)*360/N (1)
where N is the number of teeth on the gear 34, and w is the rotation angle of the step motor 38.
The tangent distance of travel for the cleaning edge 25 is R times the angle of rotation in radians, when R is the distance of the cleaning edge from center of rotation.
The position of the grid bar in
Grid bar deployment Table A, or similar, is constructed experimentally in a cotton gin of similar lint cleaner properties as that of the gin where the system and the table is to be utilized. While the gin is operating at a given steady, not varying significantly, input trash level, the operator deploys any number of grid bars combination possible such as one grid bar, two grid bars, three grid bars, etc., at a time, and records the output trash level obtained as the result of each combination. He enters the results into a table of the sort designated as Table A where the columns designated as Desired Output Trash Level (Ts) represent the actual trash level achieved. The operator repeats the procedure for different input trash levels so it covers all the expected range of trash levels expected to be fed into the gin.
In order to reduce the number of alteration the grid bars undertake, the grid bar processors 75 and 77 utilize a rolling averaging formula (2) which outputs the results once every user selectable output deployment time interval.
GB(Drive)=int(a0*GB(t)+a1*GB(t−1)+ . . . +ai*GB(t−2)+ . . . an*GB(t−n)+a) (2)
Where:
-
- GB(Drive) is the averaged grid bar deployment figure to be output to grid bar driver,
- GB(t) is the grid bar deployment figure from the current calculation cycle,
- GB(t−1) is the grid bar deployment figure from the previous calculation cycle,
- . . .
- GB(t−n) is the grid bar deployment figure from the nth previous calculation cycle
- a0 through an are coefficients of weight which can be adjusted to increase or decrease the affect of the averaging. a0 through an are smaller then 1 and greater or equal to 0 except of a0 which should always be greater then 0. The sum of the coefficients a0 through an should be equal to 1. a is a constant used to round up to the nearest integer; 0<a<1.
The number and coefficients ai can be chosen to be any number greater then 1. at least a0 should be greater than 0. The number and the value is determined based on the stability and responsiveness of the system during operation. When the final grid bar deployment figure GB(Drive) is varying too often then the system shall include more coefficients, averaging the calculation over longer sequence of grid bar deployment figures. When greater responsiveness is required due to fast changing conditions of the lint, a smaller number of coefficients should be used, but more than 0, so the average will be of shorter history.
Grid bar deployment Table B is constructed experimentally in a cotton gin of similar lint cleaner properties as that of the gin where the system and the table is to be utilized. While the gin is operating at a given steady, not varying significantly, input trash level, the operator records the trash removal error defined as Ts-To and then he engages or disengages one or more grid bars to bring this error to zero or close to it within half of a point. The proper correction is then recorded in the corresponding column on the same line. It should be noted that at different input trash levels there may be different corrections to grid bar schedule thus requiring the creation of multiple tables of type B, one for each level of input trash level.
Since most gins require two or more lint cleaners in order to clean the lint to the commonly specified level, the system described in this invention can utilize three way flow valves to route the lint through multiple cleaners, or bypass any one or more of them, in any desired order. Illustrated in
As part of this invention, the trash image processors 69 and 72 calculate the amount of trash present in the lint. The image must be clipped so it does not include area which is not fully covered by the lint. This can be determined by calculating the amount of dark areas in different areas of the image. Portions which contain dark spots in excess of 5% are suspected of being poorly covered by the lint and should be excluded from the trash estimation process. The images are converted to a black and white image with the threshold set to 50 percent. This threshold level can be adjusted permanently or dynamically for lighting variation present during the taking of the images.
Table A provides the deployment schedule for grid bars. For every input trash level, also known as input leaf count, and for every output trash level, or leaf count, the operator can determine the number of grid bars to be deployed by reading the cell in the Table A which crosses the line and column of the corresponding trash figures. The table itself can be generated empirically by cleaning lint of different level of trash contents with the different grid bar deployment, starting with one bar through the entire set of grid bars in the cleaner, and measuring the effect in every case.
Table B provides the deployment correction for the lint cleaner's grid bars when an output imaging sensor is available to measure the output trash contents. The table can be used in the manual mode when the output leaf count figure is obtained from a qualified inspector. The table can be used in automatic mode where the output leaf count is fed to the grid bar processor 77 shown in
In the manual mode the operator can enter the output trash contents, into the operator terminal 66. The data is then transmitted to the grid bar processor 77 where the final grid bar deployment correction is determined based on Table B.
In the automatic mode the output trash content is calculated by the output image processor 74 and the result is transmitted to the secondary grid bar processor 77. The processor uses Table B to determine the correction to the grid bars deployment based on the output trash level To and the desired trash level set by the operator as a input set point Ts. The processor calculates the difference Ts-To and determines the correction schedule according to the number appearing in the right column of the Table B. A positive number designates an increase in the number of grid bars to be engaged, and a negative number designates a decrease in the number of grid bars to be deployed. The result is sent to the grid bar driver as the final deployment. It should be mentioned that this correction determination based on Table B should be performed after the initial deployment determined by Table A and the input trash level content as executed by the first grid bar processor 75 of
[1] Anthony; U.S. Pat. No. 5,909,786 Apparatus and method for reducing fiber waste.
[2] Mayfield et al.; Effects of Grid Bars On Lint Cleaners Performance; The Cotton Gin and Oil Mill Press; Jun. 13, 1992.
Claims
1. A variable rate lint cleaner for a cotton lint cleaning machine with rotating saws, comprising:
- at least one grid bar with a cleaning edge, and
- an actuator coupled to the grid bar, for moving the grid bar between an engaged position in which the cleaning edge is near the teeth of the saws and a disengaged position in which the cleaning edge is farther from the saws.
2. The apparatus of claim 1, further comprising a driver for the actuator, which on command sends signals to the actuator to move the grid bar between the engaged and disengaged position.
3. The apparatus of claim 2, further comprising an operator interface terminal which enables the use of said lint cleaner to command the driver to position the grid bar into the engaged or disengaged position.
4. The apparatus of claim 1, further comprising means for activating the grid bar to a desired position.
5. The apparatus of claim 4, wherein the means for activating comprises means for using an input trash level measurement to determine the bars to engage with the lint.
6. The apparatus of claim 5, wherein the input trash level is measured using imaging means.
7. The apparatus of claim 6, wherein the means for activating further comprises a lookup table that is employed in response to the input trash level.
8. The apparatus of claim 7 wherein the means for activating further comprises using an output trash level measurement to determine the bars to engage with the lint.
9. The apparatus of claim 8, wherein the output trash level is measured using imaging means.
10. The apparatus of claim 9, wherein the means for activating further comprises a lookup table that is employed in response to at least the output trash level.
11. The apparatus of claim 1, further comprising a lint retaining member coupled to the grid bar.
12. The apparatus of claim 1, further comprising a lint retaining brush coupled to the grid bar.
13. The apparatus of claim 1, further comprising a movement limiting stop for the grid bar.
14. The apparatus of claim 1, further comprising a stop switch for the grid bar.
15. The apparatus of claim 1 comprising more than one lint cleaner in series and at least one bypass valve used to bypass one or more of the lint cleaners to reduce the amount of lint lost in the cleaning process.
16. The apparatus of claim 1, wherein the actuator is responsive to an input trash level, an output trash level, and a desired output trash level.
17. An apparatus for a variable rate lint cleaner used in cotton gins comprised of:
- at least one lint cleaning machine with rotating saws and at least one grid bar,
- an actuator coupled to the grid bar, for moving the grid bar such that its cleaning edge is either in the engaged position near the teeth of the saws or disengaged from cleaning operation such that its cleaning edge is moved away from the teeth of the saws,
- a driver for the actuator which on command sends signals to the actuator to move the grid bar to the engaged or to disengaged position, and
- an operator interface terminal which enables a user of said lint cleaner to command the driver to position the grid bar into the engaged or disengaged position.
18. The apparatus of claim 17, further comprising means for activating the grid bar to a desired position.
19. The apparatus of claim 18, wherein the means for activating comprises means for using an input trash level measurement to determine the bars to engage with the lint.
20. The apparatus of claim 19, wherein the input trash level is measured using imaging means.
21. The apparatus of claim 20, wherein the means for activating further comprises a lookup table that is employed in response to the input trash level.
22. The apparatus of claim 21 wherein the means for activating further comprises using an output trash level measurement to determine the bars to engage with the lint.
23. The apparatus of claim 22, wherein the output trash level is measured using imaging means.
24. The apparatus of claim 23, wherein the means for activating further comprises a lookup table that is employed in response to at least the output trash level.
25. The apparatus of claim 17, further comprising a lint retaining member coupled to the grid bar.
26. The apparatus of claim 17, further comprising a lint retaining brush coupled to the grid bar.
27. The apparatus of claim 17, further comprising a movement limiting stop for the grid bar.
28. The apparatus of claim 17, further comprising a stop switch for the grid bar.
29. The apparatus of claim 17 comprising more than one lint cleaner in series and at least one bypass valve used to bypass one or more of the lint cleaners to reduce the amount of lint lost in the cleaning process.
30. The apparatus of claim 17, wherein the driver for the actuator is responsive to an input trash level, an output trash level, and a desired output trash level.
31. An apparatus for a variable rate lint cleaner used in cotton gins comprised of:
- at least one lint cleaning machine with rotating saws; and
- a plurality of grid bars for cleaning lint that is carried by the saws, wherein the grid bars are movable between an engaged position in which the cleaning edges of the bars are close to the teeth of the saws so that they participate in cleaning the lint, and a disengaged position in which the cleaning edges of the bars are farther from the teeth of the saws, so that they do not participate in cleaning the lint.
32. The apparatus of claim 31, further comprising means for automatically moving the grid bars between the engaged and disengaged positions.
33. The apparatus of claim 32, wherein the means for automatically moving the grid bars is responsive to an input trash level, an output trash level, and a desired output trash level.
Type: Application
Filed: Apr 2, 2004
Publication Date: Oct 6, 2005
Inventors: Michael Gvili (Wayland, MA), Stanisslav Mezhebovsky (Sudbury, MA), Martin Northern (Wolfforth, TX), Robert Lucus (Lubbock, TX)
Application Number: 10/817,383