60/411,460 filed September 16,2002.

FIELD OF THE INVENTION [0001] The present invention relates to methods and apparatus for winding material on a spool, and more particularly to a method and apparatus that automatically detects winding layer diameters and adjusts winding to maintain an even, level material layer.

DESCRIPTION OF THE PRIOR ART [0002] Methods of determining turn around points when winding material on spools have been the subject of design efforts and patents. U. S. Pat. 4,738, 406 by Lothamer describes a method of determining spool turn-around points by measuring the winding diameter at the center of the spool for each layer, and calculating the intersection with the flange of a straight line passing through a point on the calculated radius, with the straight line running parallel with the spool core surface. The core surface is also assumed to be located according to available flange construction drawings. In actual practice, manufacturing tolerances, stress and wear on parts generally only allow nominal turn around points to be calculated from designed dimensions. Therefore, variations in the actual layer optimum turn around point will vary from the calculated values of Lothamer.

[0003] U. S. Pat No. 4,629, 145 by Graham describes the use of a position detector and revolution counter to determine when winding reaches an end of a spool being wound in order to generate a signal for activating the reversal of direction of winding. The settings of the position detectors and number of revolutions are determined manually.

[0004] U. S. Pat No. 4,928, 904 by Watts describes sensing the position of optical fiber being wound on a bobbin by illuminating the fiber with an energy and detecting energy

that is reflected within a portion of the fiber. The patent states that the detected signal can be input to a controller for adjusting the winding mechanism. Further details of how this is done i. e. , what data is used and what is done to correct a problem are not described.

[0005] U. S. Pat No. 5,590, 846 by Dekel describes a method for monitoring the winding of fiber. When an irregularity is noted, the operator can stop the winding process and make the necessary corrections.

SUMMARY [0006] It is an object of the present invention to provide an improved method and apparatus for evaluating winding quality near spool edges.

[0007] It is a further object of the present invention to provide a method and apparatus for automatically evaluating winding quality and correcting winding parameter variations.

[0008] It is a still further object of the present invention to provide a method and apparatus for automatically calculating spool winding surface slope near spool edges.

[0009] Briefly, a preferred embodiment of the present invention includes a method wherein nominal spool edge positions for each winding are calculated and used to initiate winding. During winding, measurements and calculations are automatically performed to determine the shape of the winding surface near the spool edges. Preferably, an average spool radius is calculated over every two revolutions near the spool edge. The spool radii are then automatically plotted as a function of position along the spool axis, and a linear regression is performed to fit a line to the radii data. The resultant slope data is then used to correct the spool edge/turnaround points. If the slope is negative, indicating a reduced spool radius at the spool edge, the turnaround point is adjusted outward toward the flanges an amount proportional to the slope. If the slope is positive, indicating a greater spool radius at the edges, the turnaround points are adjusted inward, away from the flanges.

IN THE DRAWING [00010] Fig. 1 is a symbolic diagram for illustrating the method and apparatus of the present invention; [00011] Fig. 2 illustrates the build-up and roll-off encountered in spool winding; [00012] Fig. 3 illustrates turn-around point adjustment and visual display of data; [00013] Fig. 4a illustrates the rotational position parameter of the spool; [00014] Fig. 4b illustrates the rotational position parameter of the capstan;

[00015] Fig. 5a shows further details of an accumulator apparatus; [00016] Fig. 5b is a perspective view of the accumulator apparatus; [00017] Fig. 6 is a chart illustrating set data stored in the controller; [00018] Fig. 7 is a chart illustrating calculated radii stored in the controller; [00019] Fig. 8 is a flow chart of the method of the present invention; and [00020] Fig. 9 illustrates calculation of nominal edge turn around values.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [00021] A preferred embodiment of the present invention will now be described in reference to Fig. 1 of the drawing. In a system 10, material 12 is wound on a spool 14, being guided by a distributor apparatus 16 from a turn-around point 18 on one end of the spool 14 to a turn-around point 20 on the opposite end of the spool 14. The distributor apparatus 16 moves a distributor sheave 86 along an axis in a direction as indicated by arrow 52 parallel to the axis of rotation 44 of the spool 14 using a ball screw or belt driven linear shuttle 88 and servo motor 90. By moving the distributor sheave relative to the spool 14, the distributor is able to direct the way in which the fiber 12 is wound onto the rotating spool 14. In a typical application, the distributor is translated along the direction 52 towards one of the flanges 38 or 40 until the fiber 12 that is being wound on the spool also known as the fiber package 92, reaches the spool flange 38 or 40. At this point, known as the turn-around point 18 or 20, the distributor 16 reverses direction and begins to wind fiber in the opposite direction until it reaches the other spool flange where it again reverses direction. In this way, fiber is evenly wound onto the rotating spool creating a nearly cylindrical fiber package shape. Another possible configuration for the distributor mechanism consists of a spool and distributor like that described above where the spool is moved relative to the distributor sheave. In either case, the present invention performs as described below.

[00022] The nominal positions of turn around points 18 and 20 are initially programmed into a controller 22 for directing the operation of the material feed apparatus 27, including the distributor 16 via bus 24, capstan wheel apparatus 26 via bus 25 and accumulator apparatus 28 via bus 29, and for communication with a spool apparatus 30 via bus 31. An example of a calculation method for programming the controller for determination of nominal turn around points on the sloped surfaces 34 and 39 of the flanges 38 and 40 of the spool 14 will be described fully in the following text in reference to the drawing.

[00023] According to the present invention, the apparatus 10 of Fig. 1 is configured to determine the radii of windings 42 on the spool 14 over at least a pre-determined distance L. The controller is programmed to calculate the radii of the windings, and the slope of the winding surface over the length"L"and display the result visually for an operator, for example on a computer monitor system 51. The controller is further programmed to re-direct the distributor to alter the turn around points 18 and 20 so as to correct for positive and negative slopes and thereby keep the winding layer surface flat. A preferred calculation of radii and slope will be fully described in the following text in reference to the figures of the drawing. The edge conditions over a length"L"discussed above are illustrated in Fig. 2.

The spool 14 shown in Fig. 1 is used for illustration and has a flange 38 with a sloped edge 34. The present invention also applies to other spool configurations. Dashed line 56 illustrates an ideal, linear surface of the windings. Due to tolerances as described above, the winding surface is not always linear/level. Fig. 2 illustrates what will be referred to as a negative slope of the windings at 58, indicating that the edge turnaround point 60 needs to be adjusted outward, in the direction shown by arrow 62. Line 64 illustrates an average slope of the winding layer surface over a predetermined distance L. Dashed line 66 illustrates a spool winding layer surface that would have a positive slope caused by the winding turnaround point 68 being too far outward. In this case, the turnaround point would be adjusted inward in the direction indicated by arrow 70.

[00024] According to a preferred method of the present invention, in order to determine/calculate the radii and slope, the controller collects data from the material feed apparatus 27 in order to calculate spool material feed data indicating lengths of material fed to the spool 14 for a particular spool rotation/measurement period. The spool feed data is calculated from data including rotational position data from the capstan wheel apparatus 26 indicating the amount of material 12 transferred for a given measurement period, and material storage data including data from the accumulator apparatus 28 and the distributor apparatus 16 to indicate the amount of material accumulated (stored) during the period of the measurement. The difference between the capstan feed data, i. e. material feed apparatus 27 input data and the material stored data is calculated by the controller, and indicates the amount of material fed to the spool during the same period i. e. spool material feed data. The controller also collects data from the spool apparatus 30 providing spool rotational position/angle data for determining the number of spool rotations during the measurement period. The period of measurement is preferably 180 degrees i. e. 1/2 of a spool rotation.

From the data set, including the capstan 26, accumulator 28 and distributor 16 data, and the

number of spool 14 rotations"N", the controller can determine the radius of the winding.

This is expressed in mathematical form in equation (1) for the spool 14.

(1) 2RN = Length fed by Capstan 26-change in lengtlz stored in accunzulator and distributor (28, 16) 1---------------I v-I I lelgthof material wonnd on spool dttring the (reme) t period [00025] The quantity 211RN is equal to the length of material in N turns of the spool, which is the length of material wound on the spool during the period of measurement. The capstan feed is the length of material fed by the capstan as measured by the rotation of the capstan during the measurement period. The accumulated/dispensed material is the change in length of material stored in the accumulator and distributor which can be an accumulation which would be a positive number and subtract from the capstan feed, or it can be a negative number indicating a decrease in the amount of material accumulated which would add to the amount fed by the capstan feed. The change in the length of material stored in the accumulator results from changes in the lengths b, c, d, e, and f shown in figure 5a. The change in the length of material stored in the distributor is caused by changes in the length h shown in figure 1.

[00026] A particular embodiment of the control system uses the data described above to calculate an average fiber package radius (Rp) over a group of two turns i. e. two revolutions of the spool. The radii Rp calculation is performed every 1/2 revolution of the spool over a length L from each of the two spool turn-around points i. e. from each of the two flanges 38 and 40. The spool radii Rp are calculated and stored as a function of the winding distributor position along the spool radial axis 44. A linear regression is performed to determine an average slope to the plot of Rp v. s. L as illustrated in the plot of Fig. 3. The slope of the line, roll off or build up, is representative of the angle of the fiber package at the edges of the spool. The machine controller 22 uses this information to automatically make corrections to the spool edge turn around positions, thereby keeping the spool package as flat as possible at the edges. If the slope is positive (a build-up), the turn-around points are moved inward as indicated by arrows 46, and outward as indicated by arrows 48 if the slope is negative (a roll-off).

[00027] In the particular embodiment performing calculations at spool axial positions every 1/2 revolution, the controller calculates radii by collecting and storing one set of data every 1/2 revolution of the spool 14. This collection of data is referred to as a data

set. This data set contains information from which the length of material fed to i. e. wound on the spool can be calculated. The data set includes rotational positions of the spool 14 and capstan wheel 50, data from the accumulator 28, and a distance moved by the distributor shuttle 88 or sheave 86. The data set also includes the distributor 16 material feed position i. e. axial position of material on the spool, relative to a predetermined reference point, along the direction of the axis 52 which is parallel to the spool axis 44. Prior to each edge turn around, the controller collects n data sets. Each set of data is then used by the controller to calculate a spool winding radius. After a turn-around is completed, the data sets are analyzed. The data set which has a fiber distribution position along the spool axis closest to, and prior to, the spool turn-around position is designated with the index i = 1. In a particular embodiment, steps are taken to insure that this data set is taken when the spool's rotational position is within a pre-determined distance, such as 1/6 of a rotation of its position when the turnaround occurs. The next prior data set (going backwards in time) is designated with the index i = 2, then i = 3, and so on. In a still further embodiment, two of the data sets occur after the turn around occurs. These are designated i = 0 and i =-1.

[00028] Each data set consists of the information discussed in the previous paragraph, provided by feedback devices mounted on each of the mechanisms including the capstan apparatus 26, the accumulator apparatus 28, the distributor apparatus 16, and the spool apparatus 30, and is stored by the machine controller 22. With the n data sets collected, the controller calculates the corresponding average radius of the fiber package at each of the same distributor positions. Each distributor position Li is selected for calculation in turn. In a particular embodiment, data for an axial position on one side of the selected position (a first position) and data for an axial position on an opposite side of the selected position (a second position) are used in the calculation. The data from the two positions are used to calculate the length of material wound on the spool between the two positions, and it determines the number of turns of the spool between the two positions. The average radius for each of the distributor (axial) positions Li is calculated by equation (2). In the particular embodiment exemplified, the data sets two index positions before (first position) and two index positions after (second position) each index i are used to calculate the radius at index i and no radius is calculated for the indexes-1,0, (n-2), and (n-3).

( (Ct+z-C-z) p)- (Dt+z-Da-z)<BR> (2) 2z (Si+2-Si-2)

[00029] In equation (2), the quantity 27r Rpi (Si+2-Si 2) is the length of material wound on the spool in terms of the average radius Rpi for a number of turns equal to (Si +2- Si 2) of the spool during the measurement period. The quantity Si represents the angular position expressed numerically to indicate the number of a turn, such as turn 14.5 so that the difference between Si+2 and Si-2 equals the number of turns in the measurement i. e. the number of turns between data sets i+2 and i-2. If a data set is taken every 1/2 turn, and two data sets prior to and after each index i are used as shown in equation (2) by inclusion of the i+2 and i-2 terms, then (Si+2-Si-2) includes two full rotations/turns i. e. , two half turns before and two after the index i. The increment"2"in equation (2) indicating two data sets each side of the index i is preferred, but other quantities of increment/data sets can also be used, and are included in the present invention. With the controller having calculated and stored the quantity of (n-4) average radii Rpi, the controller can calculate an average slope of a plot of Rpi v. s. Li, where Li is a distance of the position of each of the (n-4) points along the axis of the spool. The calculation of this distance will be more fully described in the following text in reference to the figures of the drawing.

[00030] Similarly, "P"is the perimeter of the capstan wheel 50 (Fig. 1) and (Ci+2- Ci 2) is the number of turns the capstan wheel rotates over the same time interval that the spool rotates (Si+2 Si 2) turns. (Ci+2-Ci 2) P is therefore the length of material transferred by the capstan wheel in the same interval. Further clarification of the terms"S"and"C"is provided in reference to Figs. 4a and 4b. Fig. 4a shows a core 70 of the spool 14 with windings 72 having a surface 74 at a radius Rp. The term"S"is shown, illustrating that it is a value indicative of spool rotation. Fig. 4b similarly shows capstan wheel 50 with a perimeter "P"and shows the term"C"indicating that it is a value reflecting the amount of rotation of the wheel 50. (Di+2-Di-2) is the length of material stored in the accumulator and distributor, which can either be positive or negative for a given interval. Referring to Figs. 5a and 5b, a typical accumulation mechanism 28 is shown. The accumulation or distribution depends on the movement of the dancer wheel 80. The accumulator 28 consists of several grooved pulleys (also known as sheaves) arranged as shown in the perspective view shown in Fig. 5b.

The two lower sheaves (74-76) (also known as load cell sheaves) are fixed in space and attached to a load cell (78) which can detect the tension in the fiber 12. The upper sheave 80, also known as a dancer, is mounted to a dancer arm 82 that is attached to a servo motor 84 or some other device which can provide a torque on the arm and information regarding the position of the arm. As the shaft of the servomotor rotates, the dancer sheave is translated along a radial path defined by the dancer arm. Lettered arrows (a through g) indicate the path

of the fiber 12 through the accumulation mechanism. The fiber is wound on one of the load cell sheaves before it is wound onto the dancer sheave and it is wound on the other load cell sheave after the dancer. Using the feedback provided by the load cell 78 and the ability to vary the distance between the dancer and the load cell sheaves provided by the dancer, nearly constant tension in the fiber can be maintained and any slack in the fiber that may be generated in the system can be accumulated. This is a typical accumulation mechanism.

Other configurations of accumulation mechanisms will be apparent to those skilled in the art, and these are also included as part of the present invention i. e. any accumulator will serve the purpose that is capable of measuring the length of fiber accumulated. Referring again to Figs. 5a and 6b, if the dancer wheel 80 moves downward towards the wheels 74 and 76 during the interval, more material will be transferred to the spool 14 than is passed by the capstan wheel 50 in that interval. If the wheel 80 moves up during the interval, the accumulator absorbs/accumulates material from the capstan wheel 50, and less material is transferred to the spool 14 than what is fed by the capstan wheel 50. Referring to Fig. 1, the distributor mechanism 16 can also accumulate or transfer material based on the motion of sheave 86 in the direction indicated by arrow 52. If the position of sheave 86 in Figure 1 moves towards the flange 40 during the time interval, more fiber is being accumulated in the length h which is the length of fiber between sheave 86 and the stationary sheave 87 upstream. If the position of sheave 86 in Figure 1 moves towards the flange 38 during the time interval, the length h is decreasing and the distributor is transferring additional fiber to the spool.-(Di+2-Di2) therefore represents the length of material stored in such an accumulator and such a distributor. If Di+2 = Di 2, then no material is added to or subtracted from the accumulator and distributor, and the material sent to the spool is the same as that passed by the capstan wheel, which is (Ci+2-Ci 2) P.

[00031] The controller calculates Rpi for the programmed position"i"of the (n-4) positions along the axial length of spool over the pre-programmed end zone length. The distance of the position"i"from a pre-programmed reference point, such as a flange edge is noted as Li. The controller can then be programmed to calculate the slope at (n-8) of the positions using adjacent zone data as indicated by equation (3). <BR> <BR> <P>(3) Slope ;-RP+2-Rp-2 = ORp<BR> Li+2-L-2 AL ; The angle of the material winding is given by equation (4).

(4) Angle ; = arctan (slope ;)

An example of set data collected and stored is illustrated in the charts of Figs. 6 and 7.

The data may be graphically displayed to the operator in the form of an x-y plot of Rpi versus Li for data sets i = 1 to n, as shown in the graph of Fig. 2 illustrating both material build up and material roll-off. The figure is showing only one half of the datasets, those which correspond to the radiuses at each of the same rotational position of the spool. The other points correspond to radiuses at rotational positions 1/2 a revolution away and could be displayed at the bottom of the spool if both halves of the spool cross-section were shown.

[00032] These are simple examples of ways to calculate and display the slope. In the preferred embodiment, the controller calculates the average edge angle over the whole edge area, by performing a linear regression on the edge data to calculate the slope of a line that best fits the data (least squares linear regression). This can be done with matrix manipulation or direct mathematical computation using standard least-squares linear regression formulas. Other non-linear regressions can also be used to determine the overall average edge quality.

[00033] The controller 22 of the present invention also includes programming of a PID control algorithm, or alternatively or in addition other possible closed loop control algorithms, to make appropriate corrections to the calculated turnaround points. The error input to the PID control loop is the average edge angle (desired angle is zero) of equation (4).

The PID calculates a correction based upon the proportional, integral and derivative gain values and the magnitude of the input error. The output of the PID loop is a position correction added to the nominal edge turnaround position to calculate the corrected edge turnaround position. In this way, the machine controller can automatically adjust the edge turn around point to minimize the amount of fiber build up or roll off at the spool flange.

[00034] A preferred method of the present invention is illustrated in the flow chart of Fig. 8. Initially, the controller 22 is pre-programmed with data for setting the spool winding turn around points. These points are nominal because they are calculated from design data of spool and other equipment, and these dimensions are not precisely accurate due to manufacturing tolerances and wear and stress. The controller directs the initial winding process to begin based on the nominal end points, but then begins measurement to correct the end points to minimize edge build up or roll off. Block 94 indicates that the system is operating, and winding material on the spool, with turn around points as directed by the controller, which are either the original"nominal"points or adjusted points. The controller receives and records the data (S, C, D, L), preferably for each 1/2 revolution of the spool in the pre-programmed area (spool axial distance) adjacent each turn around point

(block 96). Each 1/2 revolution measurement interval has an index number"i"assigned, indicating its position relative to the turn around point. The quantity of measurement intervals is noted in this description as"n", and it is a pre-programmed number. The controller then uses the set data to calculate the winding radius Rpi for each of the"n"1/2 revolution intervals (block 98). Block 100 summarizes the controller's next task of calculating the slope. Following this, the controller evaluates the slope (block 102). If the slope is zero 104 and is at a steady state, no adjustment in the turn around points is required (block 106), and the winding and measurement process continues, as indicated by return line 108. If the slope is not zero 110, the controller determines if it is positive or negative (block 112). If it is positive 114, build up is occurring and the turn around points are adjusted <BR> <BR> (block 116) in the negative i. e. , inward/away from the spool ends using a PID control algorithm and the winding process continues 118. If the slope is negative 120, a roll off is occurring and the turn around points are adjusted (block 122) in a positive direction i. e., outward/toward the spool ends using a PID control algorithm, and the winding process continues 124.

[00035] Fig 9 will now be referred to for explanation of a method for determining the nominal edge turn around points in the slope areas 34 of the spool 14. Using flange 38 edge 124 as a reference point, marked with a"0", equations for the location of the turnaround points 126 and 128 are as follows: [00036] Let A = position of the turnaround at 126 B = position of the turnaround at 128 Rw = winding radius near center of the spool.

Rs = spool core radius e = flange offset A = d,-b, = d,-ai tan , = d,-R, y- (RS + e,)] tan ,<BR> B=d2 +b2 =d2 +a2tan t92 =d2 + [RW-(Rs + e2)] tan 02 Assuming the spool is accurately symmetrical, it follows that al = a2, e, e.,, and b, =b2 [00037] In order to further summarize the operation according to the present invention as described above, the following description is provided. The method provides for adjusting a turn around point during winding of material on a spool. As material is wound on the spool, the apparatus of the invention collects the data as described above for a plurality of n data sets collected near the turn around point. Each data set is a set of data including:

(1) the rotational position of the spool, (2) the rotational position of the capstan, (3) the axial position of the distributor, and (4) the length of fiber currently being stored in the accumulator and distributor mechanisms. The controller then estimates the average radii corresponding to each data set where i = 1 to (n-4) using data from nearby data sets. The controller then calculates the average slope of the plot of the (n-4) average radii v. s. the axial position data of each data set along the spool axis i. e. over the distance from the turn around point. With this slope determined, the controller then moves the turn around points in or out as described above for the purpose of achieving an axially level spool winding surface.

[00038] Although the present invention has been described above in terms of a specific embodiment, it is anticipated that alternations and modifications thereof will no doubt become apparent to those skilled in the art. It is therefore intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.

What is claimed is: