Abstract:
A method and apparatus for producing large rolls of tubular fabric knitted on a small diameter circular knitting machine of the type having fabric takedown rollers for pulling the fabric from the knitting cylinder, and a takeup roller for winding up the fabric into a roll, including a traversing mechanism that is operatively associated with and positioned upstream of the tubular fabric takedown rollers so that the fabric is moved back and forth along the length of the take down rollers, so that the width of the fabric roll wound upon the takeup roller is substantially the length of the take down rollers. Further, the fabric leaving the takedown rollers is surface driven to provide constant speed and tension.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to tubular fabric formed on small diameter circular knitting machines and, more particularly, to an apparatus and knitting machine that produces large rolls of such material. 
     BACKGROUND OF THE INVENTION 
     Small diameter circular knitting machines have been in use for many years in the textile industry. These machines are especially designed for knitting narrow tubular single jersey and rib knit polyester and cotton fabrics, and combinations thereof, to be used as cuffs on sleeves or trousers, as liners for specialty garments, etc. 
     While there are several types and models of small diameter circular knitting machines, they each operate on the same general principles. A small diameter knitting cylinder and dial assembly equipped with latch needles (knitting needles) receives ends of polyester or other yarn that are fed from surrounding creels. A small diameter tubular knitted fabric is thus formed on the latch needles and is continuously and synchronously drawn downward by the machine&#39;s takedown assembly. The takedown assembly includes two or more takedown rollers that frictionally engage and pull downward on the tubular fabric. As is conventional in machines of this type, a windup mandrel is positioned below the takedown rollers to form a narrow roll (like a coiled fire hose) of fabric having a width corresponding to the width of the tubular, but flattened, knitted fabric. The roll is wound around the mandrel, the mandrel being independently driven and controlled by a clutch assembly. 
     There are a number of problems inherent in this system of forming rolls of fabric. First, because these rolls are formed by a buildup of concentric layers, the rolls are limited in the diameter that can be formed. Thus the length of fabric on a roll must also be limited. As a result, these narrow rolls of fabric must be “doffed”, or removed, about every 35 to 40 minutes, depending upon the production rate of the machine. This translates to a substantial labor requirement wherein machine operators must frequently remove the full rolls and ready the machine for a new roll. Similarly, the end users of the narrow fabric rolls are forced to frequently interrupt the production of apparel or the like in which the tubular fabric is being incorporated in order to get a new roll. 
     In such machines, typically the mandrel, or core, of the narrow roll is driven independently by a clutch-controlled motion. As a result, the tension created in the fabric is not uniform throughout the roll. A great deal more tension tends to be induced on the inner, or first, layers than on the outer layers because the mandrel exerts a greater force on the inner layers and less force on the outer layers. This is caused by decreasing the angular velocity of the outer layers as the clutch tends to brake. Fabric, like any other material having a substantial elastic characteristic, develops a memory when held in a certain stretched or unstretched condition for any appreciable length of time. The problem that this creates is that the end users must produce apparel with a product that does not exhibit uniform characteristics throughout its length. For example, if the tubular fabric is being cut into specified lengths for use as cuffs on garments, the first cuffs, which are stretched less, will be more loosely fitting because the less stretched fabric will have less tendency to return to a narrow, stretched shape. On the other hand, the last cuffs formed will fit more tightly as the material that is stretched during the fabric formation tends to return to its narrow, stretched shape. This presents a quality dilemma for the end user who often must discard lengths of the knitted fabric as unusable. 
     Yet another problem inherent in the production of narrow rolls is wastage resulting from knitting machine failures such as sudden stoppage, which causes the very narrow rolls to collapse and unravel, rendering them useless. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method that addresses each of the problems described above. 
     The essence of the present invention is a takeup system that forms a larger, wider, roll of tubular knitted fabric and also maintains a constant tension on the fabric wound onto the takeup package. In its simplest form, the system includes a traversing mechanism that is positioned between the knitting cylinder and the takedown rollers. The traversing mechanism moves at a controlled rate across the path of the fabric tube to build a wound package of a substantially constant diameter. Secondly, the takeup package is surface driven to ensure a constant tension on the fabric on the package. 
     The traversing mechanism is mounted between the knitting cylinder and the takedown rollers and includes a traversing control spindle that extends substantially across the width of the machine&#39;s takedown assembly. The traversing control spindle is mounted by flange bearings at each end attached to the upper takedown bracket. A reversing nut is operatively mounted on the traversing control spindle and reciprocates along tracks in the traversing control spindle. Upon reaching the end of the track, the nut reverses direction and moves back to the opposite end, and so on. If the tracks were provided with a conventional, constant pitch, the reciprocating motion would be accelerated near the ends of the spindle. Therefore, an important aspect of the spindle track pattern in the present invention is that the pitch of the track pattern is steeper at the ends of the track and is more gradual in the middle of the track. This unique design causes the reversing nut to move more slowly when it approaches the ends of the track than it does at the middle of the spindle, which actually causes a more constant traversing speed. As a result, the fabric being pulled downwardly is more evenly wound across the width of the fabric roll. 
     A traversing plate is fastened to one end of the reversing nut so that, as the traversing control spindle rotates, the traversing plate moves with the reversing nut back and forth along the spindle. A guide rod extends through a slot in the traversing plate and is attached on opposite ends to the flange bearings. The guide rod keeps the traversing plate in a constant horizontal and vertical alignment with respect to the takedown rollers. Extending outwardly from the bottom of the traversing plate is a narrow, flat guide plate that is slightly wider than the width of the tubular fabric being processed. Small rollers having rotational axes perpendicular to the takedown rollers are attached on opposite sides of the guide plate and protrude forwardly outward so that they contact the vertical side edges of the tubular fabric. To stabilizethe fabric, a separate fabric spreader plate is inserted within the tubular fabric sleeve to spread and stabilize the fabric being pulled through by the takedown rollers. Thus, as the spindle rotates, the reversing nut with attached traversing plate moves back and forth along the length of the spindle. The guide plate, with rollers, moves the fabric with the spreader plate in similar fashion back and forth substantially along the length of the takedown rollers as the fabric is pulled through the takedown rollers. 
     A second aspect of the invention is to provide constant tension on the rolled fabric. Toward this end, the takeup mandrel and clutch assembly of the conventional machine are removed and replaced by a freely rotating takeup roller that extends across a substantial width of the lower takedown bracket. Opposite ends of the takedown roller shaft are held by spring-biased arms that are each mounted on opposing walls of the lower takedown bracket. 
     The independent drive system of the conventional machine is removed from the machine of the present invention and is replaced by a knurled, cylindrical surface driving windup roller that extends across the width of the lower takedown bracket. Opposite ends of the windup roller shaft are mounted within pillow block bearings. The windup roller is interconnected with the takedown rollers by a gear chain and driven in a ratioed relationship thereto. Thus, as the takedown rollers pull the fabric downward for winding upon the takeup roller, the windup roller is driven slightly slower, relaxing some of the tension in the fabric. The biasing arms holding the takeup roller and thus the fabric roll against the windup roller. The windup roller then drives the fabric roll from the roll&#39;s outer surface at a constant speed. This constant surface speed ensures that a constant tension is induced on the knitted fabric as it is being wound around the takeup roller. Therefore, a fabric roll is formed that has a substantially uniform outer shape, holds 5 to 10 times more fabric than a conventional, narrow roll, and delivers a fabric wound at a substantially uniform tension. 
     These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of the prior art small diameter circular knitting machine; 
     FIG. 2 is a front perspective view of the apparatus and small diameter circular knitting machine of the present invention; 
     FIG. 3 is a schematic of the drive system of the present invention shown in FIG. 2; 
     FIG. 4 is a front perspective view of the traversing mechanism of the present invention; 
     FIG. 5 is a rear perspective view of the traversing mechanism of the present invention; 
     FIG. 6 is a perspective view of the traversing control spindle of the present invention; 
     FIG. 7 is a front perspective view of the rollup and winding assembly of the present invention; and 
     FIG. 8 is a front view of the windup assembly of FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, shown generally as  10  is a representative small diameter circular knitting machine known in the art. The machine shown in FIG. 1 is manufactured by Tompkins Brothers Company, Inc. of Syracuse, New York as Model No. R0508. This type of machine is used for knitting inserts, cuffs, liners, etc., and is representative of other small diameter machines manufactured by other suppliers. In operation, the knitting cylinder and dial  11  equipped with knitting needles (not shown in detail) forms a tubular rib knit fabric  25  at the top of the machine, as a takedown assembly, shown generally as  12 , mounted within a stable frame  13 , rotates below. The takedown assembly  12  comprises upper and lower takedown brackets  14   a  and  14   b,  a plurality of take down rollers  15 , and a windup mandrel  16 . A drive system  17  controls the coordinated movement of the rollers  15  and mandrel  16 . The drive system  17  is interconnected to and driven by the rotation of the knitting cylinder and dial  11 . While a detailed description is not necessary for an appreciation of the present invention, the drive system basically includes a shaft  18  that links gear and chain assemblies  19  and  22 , and pulley assembly  24 . As shaft  18  is rotably driven, gear and chain assembly  19  causes the takedown assembly to rotate. The rotation of shaft  18  also drives gear and chain assembly  22  that engages a mechanical clutch  23 . The mechanical clutch  23  controls the rotation of the mandrel  16 . 
     As the knitting cylinder and dial  11  forms the tubular knitted fabric  25  and the takedown assembly  12  rotates, the takedown rollers  15 , which are driven by pulley assembly  24 , rotate to frictionally engage and pull the fabric  25  downwardly from cylinder  11  and flatten it for rolling up. The flattened fabric  25  is wound into a roll  27  rotably by mandrel  16 . The windup of the roll  27  is thus driven from the center of the roll  27  by the mandrel  16 . The resulting roll  27 , which is the width of the flattened fabric  25 , has a relatively large diameter to width ratio. As a result, roll  27  tends to be unstable and easily collapses due to machine stoppages or handling. 
     In a preferred embodiment of the present invention, the drive system and rollup assemblies for the small diameter circular knitting machine are substantially different from the prior art. As shown in FIG. 2, the present invention provides a small diameter circular knitting machine, shown generally as  100 . Knitting machine  100  comprises a knitting cylinder and dial  111  (not shown in detail) mounted atop a stable frame  113 . Mounted within the frame  113  is the takedown mechanism, shown generally as  112 . The takedown mechanism comprises a takedown bracket  114  having upper and lower bracket portions. The knitting cylinder  111 , frame  113 , and takedown bracket  114  are functionally the same as the prior art knitting machine shown in FIG.  1 . The takedown mechanism, however, is substantially different. 
     The takedown mechanism  112  of the present invention includes a traversing mechanism  120 , takedown rollers  115 , a takeup roller assembly  130 , a windup roller assembly  140 , and a drive system. 
     As seen by comparing the prior art machine of FIG. 1 with the present invention of FIG. 2, the drive system of the present invention is best understood. A schematic of the drive system of the present invention is shown in FIG. 3, in part. The gear and chain assembly  22  and mechanical clutch  23  of the prior art machines have been removed from the machine of the present invention. As shaft  118  is rotably driven, gear and chain assembly  119  causes the takedown assembly  112  to rotate. Shaft  118  is still connected to a pulley assembly  240  that drives the takedown rollers  115 . It is the rotation of the takedown rollers  115  that drives the takedown system  112  of the present invention. The rotation of the takedown rollers  115  drives the interconnected windup roller assembly  140  (and windup roller  141 ) and the traversing mechanism  120  (and traversing control spindle  122 ), each turning at a selected rotational speed. That is, an extension  116   a  of one of the takedown roller  115  shafts has two sprockets affixed along its length. The first sprocket,  119   a,  is interconnected to sprocket  119   d  by a chain  129   a.  Sprocket  119   d  is rotably mounted to a shaft  116   b  that is held in place by a bearing sleeve  116   c  formed in the wall of the takedown bracket  114 . A second sprocket  119   c  is rotably mounted on shaft  116   b  and is interconnected by chain  129   b  to sprocket  128  that is mounted on one end of the traversing control spindle  122 . Further, the second sprocket  119   b  mounted on takedown roller shaft  116   a  is interconnected to sprocket  145  on windup roller shaft  142  by chain  129   c.  Sprocket gear ratios are selected such that the takedown roller shaft  116   a  turns approximately 4.4 times for 1 turn of the traversing control spindle  122 . Traversing control spindle  122  moves a traversing plate, described in detail below. The takedown roller  115  surface turns 1.25 times faster than the windup roller  141  surface, ensuring that some of the tension is relaxed before being wound by windup roller  141 . Thus, as the gear and chain assembly  119  is driven, the takedown rollers  115 , traversing mechanism  120 , and windup roller assembly  140  are interconnectedly driven in unison. 
     In operation, as with the conventional small diameter machines, a tubular knitted fabric  150  is formed on knitting cylinder and dial  111  atop the machine. The frame  113  and knitting cylinder and dial  111  are taken from the Model R0508 knitting machine manufactured by Tompkins Brothers Company, Inc. Whereas in the conventional machine the fabric  25  first encounters the takedown rollers  15  on its straight vertical path downward, the knitted fabric  150  of the present invention first encounters the traversing mechanism  120 . FIGS. 4 and 5 show the front and rear perspective views of the traversing mechanism  120 . The traversing mechanism  120  comprises opposed flange bearings  121   a  and  121   b,  a traversing control spindle  122 , a reversing nut  125 , a traversing plate  123 , a guide rod  126 , and a sprocket  128 . 
     As the takedown rollers  115  rotate, the takedown roller shaft extension  116   a  with sprockets  119   a  and  119   b,  and chains  129   a  and  129   b  connected thereto, drives the traversing mechanism  120  via sprocket  128 . The rotation of the traversing control spindle  122  causes reversing nut  125  to move back and forth along the length of the spindle  122  tracks  122   a.  Tracks  122   a  formed in spindle  122 , control the speed of movement of the reversing nut  125  along the spindle  122 . Conventional spindles used in other than textile operations typically have tracks that are uniformly spaced along their lengths; however, as will be understood by those skilled in the art, when the traversing nut  125  approaches and departs each end of the spindle track  122   a,  less material (fabric) is deposited at the ends of the roll than in the middle, or center, of the roll. This effect results in a “football” shaped roll of fabric, which tends to be dimensionably unstable when packaged, shipped, and stored. Thus, the tracks  122   a  formed in the spindle  122  of the present invention, are more widely spaced in the middle of the spindle  122  and are more closely spaced at the outer ends of the spindle  122 . This is best seen in FIG.  6 . The pattern of tracks  122   a  are formed so that there is a variable lead with increasing dwell time on both ends of tracks  122   a.  The optimal pattern was determined through testing and calculating the length of time the fabric  150  needed to dwell on the outer ends of the spindle track  122   a.  As those skilled in the art will appreciate, if direction is reversed too quickly at the ends of the tracks  122   a,  more fabric is deposited at the center of the roll. The spacing of the tracks at the center of the spindle  122  is 0.825 inches (see dimension A in FIG. 6) and tapers downward to a spacing of approximately 0.481 (see dimension B in FIG. 6) inches at the ends of spindle  122  tracks  122   a.  The design of the spindle  122  tracks  122   a  of the present invention effectively causes the reversing nut  125  to decrease speed at the ends of the spindle  122  track  122   a,  which in turn ensures an even surface across the width of the roll  155  of knitted fabric. As those skilled in the art will appreciate, the spacing of the tracks may be varied depending upon the rate of fabric production, the type and shape of fabric, roller lengths, etc. 
     Connected to one end of the reversing nut  125  is the traversing plate  123 . As the reversing nut  125  moves back and forth along traversing control spindle  122 , the traversing plate  123  moves with it. Traversing plate  123  has a lower guide portion  123   a  that is oriented generally parallel to the traversing control spindle  122  and parallel to the direction of travel of reversing nut  125 . Guide portion  123   a  is dimensioned to be wider than the width of the fabric  150  being pulled down. On either side of the guide portion  123   a  are guide rollers  123   b  and  123   c.  Guide rollers  123   b  and  123   c  are, in operation, configured so that they are positioned on either side of the knitted fabric tube being pulled downward by takedown rollers  115 . As the traversing plate  123  moves back and forth along the traversing spindle  122 , the guide rollers  123   b  and  123   c  urge the fabric sleeve  150  back and forth with the traversing plate  123 . To further ensure stability in this high speed knitting operation, a fabric spreader plate  127  is positioned inside the downwardly drawn knitted fabric sleeve  150 . The spreader plate is a thin, separate “floating” plate that spreads the knitted tube by approximately 10 percent so that the fabric  150  is more stable as it is engaged by the takedown rollers  115 . Further, the spreader plate  127  adds rigidity to the fabric  150  so that the fabric  150  may be more easily moved back and forth with the traversing plate  123  between guide rollers  123   b  and  123   c,  without becoming twisted or otherwise distorted. 
     As the fabric  150  is moved by the traversing plate  123  back and forth along the traversing control spindle  122 , the knitted fabric is engaged by the takedown rollers  115  along substantially the entire working length of the takedown rollers  115 . The working length of the takedown rollers  115  is approximately 4.5 inches to 5 inches. This, in turn, results in a fabric roll of approximately 4.5 inches to 5 inches in width. 
     As the takedown rollers engage the tubular knitted fabric  150 , a large, wide roll is thus formed as the fabric is wound. FIGS. 7 and 8 show the size and shape of the resulting large roll. As described above, the prior art rolls that are wound about a clutch-controlled mandrel  16  are limited to the width of a single, flattened, knitted fabric tube and weigh approximately 1.5 pounds to 2 pounds. The rolls of the present invention will hold 5 to 10 times more fabric because of their increased width. As shown in FIG. 7, a takeup roller assembly  130  replaces the mandrel  16  and clutch  23  of the conventional prior art machines. A generally cylindrical, freely rotating, takeup roller  135  that is longer than the width of the fabric roll  155  to be formed is held in place by opposed arms  131  that are pivotally attached at their ends to the lower takedown bracket  114  at points  132   a  and  132   b  ( 132   b  not shown but identical to  132   a ) with fasteners  133 , such as pins. Springs (not shown) are connected to the riser blocks  144  and arms  131  so that the arms are spring-biased downward. Notches  131   a  formed in the free ends of the arms  131  engage takeup roller extensions  134  on either end of takeup roller  135 . In operation, the arms  131  bias the empty takeup roller  135  downward against the windup roller  141 . As the windup roller  141  rotates, fabric  150  traverses from side to side to accumulate in the wide roll. As the diameter of the roll  155  increases, the takeup roller  135  moves upward aginst the bias as the arms  131  pivotally move upward as well about points  132   a  and  132   b.  In essence, then, the takeup roller  135  moves upward as the diameter of the roll  155  of fabric increases. 
     Referring to FIG. 8, the windup roller assembly  140  is shown in greater detail. As the takedown rollers  115  rotate, the shaft extension  116   a  with sprocket  119   b  and chain  129   c  that is interconnected to the sprocket  145  on windup shaft  142  causes the windup shaft to rotate, turning the windup roller  141 . Windup roller  141  has a knurled surface along its length to frictionally engage the fabric roll  155 . The ends of the windup roller shaft  142  are rigidly mounted within pillow block bearings  143 . To provide sufficient clearance between windup roller  141  and the takedown bracket base, the pillow block bearings  143  are mounted atop riser blocks  144 , or spacers, well known in the art. As those skilled in the art will appreciate, there are a number of ways that the windup roller  141  and pillow block bearings  143  may be mounted, so long as the windup roller  141  is spaced from the takedown bracket base. Because windup roller  141  is rotating at a fixed rate and is rolling the fabric  150  from the outside of the roll, a constant tension is applied to the wound fabric from the very beginning of the roll to the end. The sprocket ratios between sprocket  119   b  and sprocket  145  are fixed at a ratio of 1.25:1 so that the tension is less than the tension of the fabric  150  coming through the takedown rollers. As those skilled in the textile arts will appreciate, the amount of tension induced in the wound fabric is not critical as long as the same tension is applied throughout the entire roll of fabric. 
     Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.