Abstract:
A multi-spindle fiber pay-out apparatus is provided that allows for fiber tension control. A frame supports a plurality of spools of fiber, with each spool of fiber being mounted on a spindle. The spindle is in rotational supporting relation to the spool of fiber and is operatively engaged with a magnetic particle brake, which is itself in control communication with an electronic controller. A fiber take-up system is mounted upon the frame in cooperative relation to the spool of fiber and is arranged so as to compensate for changes in the fiber pay-out rate from the spool of fiber that are caused by activation/deactivation of the magnetic particle brake. A load cell transducer is mounted on the frame adjacent to the fiber take-up system. The load cell transducer is at least partially engaged by a fiber, and is arranged in electrical data communication with the magnetic particle brake so as to (i) activate the magnetic particle brake when a tension in the fiber is detected below a predetermined magnitude, and (ii) deactivate the magnetic particle brake when the tension in the fiber is at or above the predetermined magnitude. A method is also provided for monitoring and adjusting the length of a fiber via monitoring of the tension in the fiber.

Description:
[0001]    This application claims priority from Provisional Patent Application Ser. No. 60/289,575, filed May 8, 2001, entitled Magna-ELC. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to an apparatus for feeding multiple fibers to a winding machine or the like and, more particularly, to such apparatus wherein the tension in each fiber is monitored and controlled so as to prevent the fiber from sagging as it traverses the distance from a spool to the winding machine.  
         BACKGROUND OF THE INVENTION  
         [0003]    Winding machines adapted to wrap a plurality of strands of fiber or wire into a completed product or onto a core member that is being drawn through a winding machine are well known in the art. The strands of fiber that are to be applied in this way are often supplied to such machines from a separate apparatus including a plurality of spools of fiber. Associated with each spool of fiber is a strand delivery assembly which often includes both a mechanical tension controlling mechanism and a clutch mechanism. The tension controlling mechanism functions to maintain a constant tension on the strand of fiber as it leaves the spool. When a constant or near constant tension is not maintained in each fiber as it makes its way to the winding machine, a difference in length is created between fibers which greatly degrades the quality of the winding on the end product.  
           [0004]    In prior art fiber pay-out apparatus, the tension control mechanism is often engaged by means of a clutch mechanism that restrains the spool from rotating and dispensing a strand of fiber and periodically releases the spool when the tension controlling mechanism reaches the limit of its operation. Release of the spool permits an additional length of fiber to be unwound from the spool. These prior art tension control mechanisms have provided less than desirable results. In particular, prior art fiber or wire pay-out systems have suffered from a lack of accurate and precise control of the tension in each fiber due, in part, to the lack of an adequate real-time control of the interaction between the tension control mechanism and the clutch mechanism. A tension control system is needed that allows for the monitoring of fiber tension, and a feed-back loop control over the release of fiber from a spool.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides a multi-spindle fiber pay-out apparatus that provides fiber tension control. In a preferred embodiment, a frame supports a plurality of spools of fiber, with each spool of fiber being mounted on a spindle having a first end and a second end. The first end of the spindle is in rotational supporting relation to the spool of fiber and the second end is operatively engaged with a magnetic particle brake, which is itself in control communication with an electronic controller. A fiber take-up system is mounted upon the frame in cooperative relation to the spool of fiber and arranged so as to compensate for changes in the fiber pay-out rate from the spool of fiber that are caused by activation/deactivation of the magnetic particle brake, or inherent irregularities in the fiber coming from the spool. A load cell transducer is also mounted upon the frame, adjacent to the fiber take-up system. The load cell transducer is at least partially engaged by a fiber, and is arranged in electrical data communication with the magnetic particle brake so as to (i) activate the magnetic particle brake when a tension in the fiber is detected below a predetermined magnitude, and (ii) deactivate the magnetic particle brake when the tension in the fiber is at or above the predetermined magnitude. A method for monitoring and adjusting the length of a fiber via monitoring of the tension in the fiber is also provided in which a continuous length of fiber is paid-out so as to continuously engage a rotating portion of a load cell transducer. The magnitude of the load applied to the load cell transducer by the fiber is compared to a standard. When a load is detected by the load cell transducer that is below the standard, means for retarding the pay-out of fiber are activated. When the load is at or above the standard the means for retarding the pay-out of fiber is deactivated. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein:  
         [0007]    [0007]FIG. 1 is a perspective view of a multi-spindle fiber pay-out apparatus, formed in accordance with the present invention;  
         [0008]    [0008]FIG. 2 is a partially exploded perspective view of a spindle assembly formed in accordance with the present invention;  
         [0009]    [0009]FIG. 3 is a front elevational view of the spindle assembly shown in FIG. 2;  
         [0010]    [0010]FIG. 4 is a perspective view of the spindle assembly shown in FIG. 2;  
         [0011]    [0011]FIG. 5 is an exploded perspective view of a load cell assembly;  
         [0012]    [0012]FIG. 6 is a broken-away, front elevational view of adjacent spindle assemblies, and including a front elevational view of a load cell assembly and wire exit guide assembly;  
         [0013]    [0013]FIG. 7 is a perspective rear view of a wire exit guide assembly;  
         [0014]    [0014]FIG. 8 is a schematic representation of a plurality of bulk supply spools arranged such that a fiber from each spool is engaged with a representation of a load cell and a fiber exit roller; and  
         [0015]    [0015]FIG. 9 is a schematic representation of a control circuit board used in connection with one embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,”“upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” or “operatively mounted” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.  
         [0017]    Referring to FIG. 1., the present invention comprises a multi-spindle pay-out stand  5  that is designed to precisely and accurately control the tension in individual strands of fiber  7  (FIG. 4) as each is paid-out from a respective bulk supply spool  9  and fed into a conventional winding machine (not shown). Very often fiber  7  is in the form of metal wire, however, other nonmetal fibers may also be used in connection with the present invention. Multi-spindle pay-out stand  5  comprises a frame  6  that is constructed to support a plurality of spindle assemblies  11 , a plurality of load cell assemblies  13 , and a plurality of wire exit guide assemblies  15 .  
         [0018]    Referring to FIGS.  1 - 4 , each spindle assembly  11  provides a fiber take-up/pay-out system during operation of multi-spindle pay-out stand  5 , and includes a spindle  21 , a baler roller  23 , a first guide roller  26 , a second guide roller  27 , a dancer assembly  29 , and a magnetic particle brake assembly  31 . Spindle  21  is often formed from an elongate cylindrical rod that is operatively mounted to a spindle assembly support plate  33  so that a first end  34  is positioned in spaced, perpendicular relation to a front surface of spindle assembly support plate  33  and a second end  35  is positioned in spaced, perpendicular relation to a rear surface of spindle assembly support plate  33 . Conventional retaining rings and ball bearings (not shown) operatively interconnect spindle  21  with spindle assembly support plate  33 . A releasable spool lock mechanism  36  operatively connects bulk supply spool  9  to spindle assembly  11  so that, as fiber  7  is pay-out from spool  9 , spindle  21  rotates in unison with spool  9 . Thus, when spindle  21  is stopped from rotating, spool  9  also ceases rotation. A magnetic particle brake  37  is positioned adjacent to the rear surface of spindle assembly support plate  33  in engaged, controlling relation to second end  35  of spindle  21 . Magnetic particle brake  37  provides means for the controlled retarding of the pay-out of fiber  7  from bulk supply spool  9 , as will hereinafter be disclosed in further detail.  
         [0019]    It will be understood that a conventional magnetic particle brake  37  of the type suitable for use with the present invention will comprise a rotor that is contained within a brake housing body and attached to end  35  of spindle  21 . A gap will exist between the rotor and the side of the brake housing body. A magnetic powder is positioned within the gap so that when this magnetic powder is acted upon by an induced magnetic field, generated by external control means of the type that are well known in the art, variations in the viscosity of the magnetic powder are created within the gap. These variations in viscosity provide for control of the torque transmission between the brake housing and end  35  of spindle  21 .  
         [0020]    Three fixed stand-off shafts  39 ,  40 ,  41  project outwardly from the front surface of spindle assembly support plate  33 . Fixed stand-off shaft  39  rotatingly supports baler roller  23 , fixed stand-off shaft  40  rotatingly supports first guide roller  26  and fixed stand-off shaft  41  rotatingly supports second guide roller  27 . Baler roller  23  is positioned above spindle  21  on fixed stand-off shaft  39 , with first guide roller  26  being positioned below spindle  21  and above second guide roller  27  along an edge of spindle assembly support plate  33 . Baler roller  23  comprises an elongate cylindrical tube that is arranged so as to rotate upon a central coaxial shaft portion of fixed stand-off shaft  39 . First guide roller  26  comprises a single, circumferentially grooved wheel or “sheave” that is mounted on the end of fixed stand-off shaft  40 , and second guide roller  27  comprises two ceramic sheaves  42 , 43  positioned, side-by-side, on a central coaxial shaft portion that projects outwardly from an end of fixed stand-off shaft  41 .  
         [0021]    Dancer assembly  29  provides an adjustably biased tensioning system that is mounted to the front surface of spindle assembly support plate  33 , and comprises a dancer arm  50 , a dancer spring clasp  53 , a dancer arm spring  57  and a spring adjustment assembly  60 . Dancer arm  50  comprises a shaft that includes a pivot hole  62  defined through a first end, and a roller shaft hole  66  defined through as second end. Pivot hole  62  and roller shaft hole  66  are arranged in spaced relation to one another. Dancer spring clasp  53  is mounted to the first end of dancer arm  50 , and includes an opening that is sized and shaped to receive and engage an end portion of dancer spring  57 . A pivot pin  68 , that projects outwardly from the front surface of spindle assembly support plate  33 , is received within pivot hole  62  of dancer arm  50  so that dancer arm  50  is pivotally mounted to spindle assembly support plate  33 , in spaced relation to spindle  21 . An end of an elongate roller shaft  70  is mounted within roller shaft hole  66  so that roller shaft  70  projects outwardly in perpendicular relation to the end of dancer arm  50 . A pair of ceramic guide rollers (sheaves)  73 ,  74  are rotatingly mounted to the free end of roller shaft  70 .  
         [0022]    Spring adjustment assembly  60  is mounted to the front surface of spindle assembly support plate  33 , and includes a tension adjust block  80 , an adjust rod  82 , and a thumb knob  84 . Tension adjust block  80  is securely mounted to spindle assembly support plate  33  above spindle  21  and typically comprises an “L” bracket or the like having a through-hole that is positioned in spaced relation to the surface of spindle assembly support plate  33 . Adjust rod  82  is an elongate, threaded shaft that includes a through-bore  89  at one end that is sized and shaped to receive and engage an end portion of dancer spring  57 . Adjust rod  82  is threadingly positioned within the through-hole of tension adjust block  80  with thumb knob  84  operatively attached to one end and dancer spring  57  engaged with through-bore  89 .  
         [0023]    Multi-spindle pay-out stand  5  utilizes a double threading technique to cushion fluctuations and maintain consistent fiber tension throughout the entire winding cycle. Each fiber  7  is threaded through spindle assembly  11  in the following manner. A bulk supply spool  9  is placed onto spindle  21  so that fiber  7  will pay-out from the top of spool  9  and over the top of baler roller  23  (FIG. 3). Fiber  7  is then wrapped over baler roller  23  and under first guide roller  26 . It is then drawn toward and around ceramic guide roller  73  on the end of dancer arm  50 . Fiber  7  is then wrapped under and around ceramic sheave  42  and drawn back toward ceramic guide roller  74  on dancer arm  50 . Fiber  7  wraps around ceramic guide roller  74  and comes off tangent to the bottom of roller  74  and out around the bottom of sheave  43  on the outside end of second guide roller  27 . The length of fiber  7  is then drawn toward load cell assembly  13 . The foregoing steps are then repeated for each of the spindle assemblies  11 . When winding less than  12  fibers from multi-spindle pay-out stand  5 , it has been found advantageous to mount spools  9  on spindles  21  starting from the inside and progressing outward, one at a time, using left and right spindles (FIGS. 1 and 8).  
         [0024]    Referring to FIGS.  5 - 7 , a plurality of load cell assemblies  13  are mounted to a central portion of multi-spindle pay-out stand  5  so that one load cell assembly  13  is associated with each bulk supply spool  9 . Each load cell assembly  13  includes a load cell mounting plate  90 , a load cell transducer  93 , and ceramic guide sheave (roller)  95 . More particularly, load cell mounting plate  90  includes a pair of support shafts  97  that project outwardly form a top surface so as to provide support for load cell transducer  93  and ceramic guide sheave  95 . Ceramic guide sheave  95  is rotatingly mounted to one end of load cell transducer  93  so as to be in spaced coplanar relation to second guide roller  27  and ceramic sheaves  42 , 43  of spindle assembly  11 . Preferably, ceramic guide sheave  95  is sized and shaped such that fiber  7  engages no more than a 90° segment. Load cell transducer  93  may comprise any of the known sensors that are capable of measuring the deflection of a central load cell shaft  98  passing through the transducer, where the magnitude of that deflection is proportional to the force being applied to the shaft. For example, one load cell transducer arrangement that has been found to provide adequate results in use with the present invention is a Cleveland Motion Controls Company transducer model No.: TNSC-IT-10 and associated differential amplifier, power supply, and power regulator forming a comparison portion of electronic control means  99 .  
         [0025]    More particularly, a PID control board designated a Merobel PLP05A, comprises a power conversion section  92 , load cell amplification section  94 , and a control regulation section  96  mounted on a single printed wiring board  101 , that utilize known electrical and electronic components such as resistors, diodes, potentiometers, LED&#39;s and transistors to provide the electronic control and communication means necessary for operation of the present invention (FIG. 9). Power conversion section  92  performs two tasks. It takes input power (24 volts, AC or DC) and reduces the voltage to a low level for the electronics in load cell amplification section  94  and control regulation section  96 . It also electronically communicates with, and provides power to magnetic particle brake  37  in accordance with results from control regulation section  96 .  
         [0026]    Load cell amplification section  94  provides the very low voltage levels required for proper functioning of load cell transducer  93 . However, these voltages need to be increased in order for control regulation section  96  to function properly. Load cell amplification section  94  takes the input from load cell transducer  93  (40 to 450 millivolts) and increases the voltage to TTL level signals (+/−5 VDC) for use by control regulation section  96 .  
         [0027]    Control regulation section  96  compares the tension setpoint (the predetermined, standard magnitude of the load applied to load cell transducer  93 ) against the actual tension applied to load cell transducer  93  by fiber  7 . In response to the result of this comparison, control regulation section  96  communicates an adjustment in the power applied to magnetic particle brake  37  so as to (i) activate magnetic particle brake  37  when the tension in fiber  7  is below the tension setpoint, and (ii) deactivate magnetic particle brake  37  when the tension in fiber  7  is at or above the tension setpoint.  
         [0028]    In operation, a desired tension setpoint is input to control regulation section  96  by an external potentiometer operated by a machine operator. The actual tension in fiber  7  is communicated to control regulation section  96  via load cell amplification section  94 , by load cell transducer  93  that is mounted in the fiber path. Also included in control regulation section  96  are a series of potentiometers that provide a means for regulating the magnitude of the incremental adjustments made in the power delivered to magnetic particle brake  37  so as to “tune the loop” to obtain the optimum performance from multi-spindle pay-out stand  5 . Too large an incremental adjustment of to magnetic particle brake  37 , and the tension in fiber  7  becomes unstable, too little adjustment and the difference between the tension and the setpoint becomes too great. Control regulation section  96  also provides a means for calibrating load cell transducer  93  to a predetermined tension level. Also control regulation section  96  may include four or more indicators, e.g., LED&#39;s, to indicate status.  
         [0029]    A Dover Flexo-FLRA-0-100-R6-6-SPR ribbon filament tension transducer connected to a Dover Flexo differential amplifier and other electronic control means  99  of the type well known in the art may also be used with adequate results for controlling and communicating with such load cell transducers  93 . Load cell transducer  93  is arranged in electrical data communication with electronic control means  99  via conventional electrical or optical data communications means of the type well known in the art for data communications between functioning portions of machinery.  
         [0030]    Multi-spindle pay-out stand  5  is preferably calibrated for a maximum fiber tension of about 2.26 kilograms (5 pounds). It will be understood that exceeding the maximum tension can and will result in damage to the machine. A recommended maximum operating tension is about 1.86 kilograms (4 pounds). Each load cell&#39;s calibration is checked and verified using the following procedure. More particularly, a fiber has a predetermined weight (2.26 kilogram) attached to one end with the other end of the fiber secured to a fixed spool spindle  21 . The fiber having a weight at the end is then threaded around its associated guide rollers, and around ceramic guide sheave  95  on the end of load cell transducer  93 . Once in this position, with the weight hanging freely from ceramic guide sheave  95 , a digital display on electronic control means  99  should indicate a load of 5 pounds. This process will then be repeated for all of the plurality of load cell assemblies  13  on multi-spindle pay-out stand  5 . Electronic control means  99  will include up to twelve such digital displays, with a set of push-button potentiometers operatively arranged so as to adjust the value displayed. The potentiometers establish the predetermined magnitude of the tension on each fiber  7  emanating from a spindle  9 . In typical bobbin winding applications, the most common strand tension is about 1 kilogram (2.5 pounds).  
         [0031]    Referring to FIGS. 1 and 7, wire exit guide assembly  15  includes a guide roller  100 , a broken wire contact bar  103 , and a wire retention means  106  all mounted to a support bracket  110 . Guide roller  100  is cylindrical, and is rotatingly mounted to the top portion of support bracket  110 . Broken wire contact bar  103  is positioned on support bracket  110  so as to be adjacent to guide roller  100 . In this way, if a metal wire is broken during operation it will engage broken wire contact bar  103  thereby completing a circuit that will either activate an alert signal or shut the machine down. Wire retention means  106  often comprises a helically wound spring  112  that is located on support bracket  110  below guide roller  100 , and facing away from multi-spindle pay-out stand  5  (not seen in FIGS. 1 and 6). Wire retention spring  112  is sized and shaped so as to allow individual fibers to be slid between adjacent turns so as to be held in place while additional fibers are threaded through multi-spindle pay-out stand  5 . Once the individual fibers from each bulk supply spool  9  are threaded through multi-spindle pay-out stand  5 , and held in place between the turns of retention spring  112 , they can be taken as a group from multi-spindle pay-out stand  5  to the winding machine that multi-spindle pay-out stand  5  is servicing (FIG. 8).  
         [0032]    Multi-spindle pay-out stand  5  operates to accurately and precisely control the tension in individual strands of fiber  7  as each is paid-out from a respective bulk supply spool  9  and fed into a conventional winding machine in the following manner. If tension in fiber  7  is allowed to vary between fibers, the fibers having a lower tension will result in a longer length between guide roller  100  and the intake mechanisms to the winding machine (not shown). Multi-spindle pay-out stand  5  operates to minimize this effect by monitoring the tension of each individual fiber  7  through plurality of load cell assemblies  13 .  
         [0033]    More particularly, as fibers  7  are drawn from multi-spindle pay-out stand  5 , each fiber engages ceramic guide sheave  95  of load cell transducer  93  and, therethrough, a measure of the force applied to load cell transducer  93  is communicated to electronic control means  99 . This measure is then compared to the predetermined, standard tension required (e.g., a 1.86 kilogram load) by electronic comparison means resident in electronic control means  99 , or other differential amplifier means. When the tension in fiber  7  is detected below that predetermined magnitude, magnetic particle break  37  is automatically activated so as to increase the viscosity of the magnetic particles, thereby retarding rotation of spindle  21 , and altering (slowing) the rate at which fiber  7  pays-out from bulk supply spool  9 . As this occurs, dancer assembly  29  is activated such that dancer arm  50  pivots about pivot pin  68  toward spindle  21 . At the same time, dancer arm spring  57  is biased between dancer spring clasp  53  on dancer arm  50  and adjust rod  82  in spring adjustment assembly  60 . This mechanism acts to increase the tension in fiber  7  paying-out from the associated bulk supply spool  9 . Once the tension in fiber  7  is at or above the predetermined magnitude, as measured by load cell transducer  93 , electronic control means  99  reduces the viscosity of the magnetic particles in magnetic particle brake  37 , thus releasing spindle  21  to continue to rotate and pay-out fiber from bulk supply spool  9 . As this occurs, dancer assembly  29  returns to its preactivation setting. Thus, each individual fiber  7  is monitored, and its tension controlled independent of the tension state in adjacent fibers and spindle assemblies. It will be understood that dancer spring  57  can be prebiased by rotation of thumb knob  84  so as to extend or to retract adjustment rod  82 . In this way, fine adjustment of the tension in fiber  7  may be accomplished with the present invention.  
         [0034]    It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.