Abstract:
A semi-automated method for forming armature coils comprising a plurality of transposed wire pairs includes joining a plurality of pairs of wires having offset segments along their lengths, insulating each of the transposed pairs of wires, assembling the plurality of the insulated transposed pairs of wires with the transpositions being staggered to create a pack, and forming the pack into an armature coil in an automated coil forming machine by bending the pack in two planes. The joining of the plurality of pairs of wires having the offset segments along their lengths is effectuated at a transposition point. Each pair of wires has a transposition at a unique point relative to others of the plurality of the pairs of wires forming the coils.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The application is based upon, and claims the benefits of, U.S. Provisional Patent Application No. 60/194,537, filed Apr. 4, 2000, the entire content of which is incorporated is reference herein in its entirety. 
     
    
     
       BACKGROUND  
         [0002]    The motor building industry has maintained the traditional craft for half a century. Accordingly, making form wound armature coils was a labor-intensive operation. Lengths of insulated copper wire were formed to an approximate coil shape on crude manually run machines and then hammered into the final desired shape. One disadvantage of that process was that repeatedly hammering the lengths of wire resulted in some degradation of the properties of the copper wire and in turn the insulation on the wires. Another disadvantage was that it took as long as 15 minutes to shape the lengths of wire into the prescribed shape of the armature coil. Furthermore, it was difficult to produce armature coils within close tolerances, and poorly shaped coils were difficult to insert into the armature and often caused damage which resulted in future motor failures.  
           [0003]    Attempts have been made to construct apparatus to shape copper wire in desired coil configurations in a controlled and automated fashion. However, no such apparatus has heretofore been available, much less one that advantageously first assembles the individual wires into a single wire pack and then forms the pack into the desired armature coil configuration. Rather, assembly lines of the related art have been limited to the batch-style methods of forming individual strands and pairs, followed by the assembly of these individual components into a coil.  
         SUMMARY  
         [0004]    A semi-automated method for forming armature coils is disclosed herein. Each of the armature coils comprises a plurality of transposed wire pairs. The method for forming the armature coils includes joining a plurality of pairs of wires having offset segments along their lengths, insulating each of the transposed pairs of wires, assembling the plurality of the insulated transposed pairs of wires with the transpositions being staggered to create a pack, and forming the pack into an armature coil in an automated coil forming machine by bending the pack in two planes. The joining of the plurality of pairs of wires having the offset segments along their lengths is effectuated at a transposition point. Each pair of wires has a transposition at a unique point relative to others of the plurality of the pairs of wires forming the coils. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a plan view of a transposed pair of wires formed of two strands of copper wire and having leads on each end and a transposition formed intermediate the ends;  
         [0006]    [0006]FIG. 2 is a side view of a pack of three pairs of transposed pair of wires;  
         [0007]    [0007]FIG. 3 is a side view of a finished armature coil;  
         [0008]    [0008]FIG. 4 is a plan view of a finished armature coil;  
         [0009]    [0009]FIG. 5 is a side elevation view of copper wire being advanced from a reel and being sequentially fed into a wire straightening unit, a wire stripping unit, an offset forming unit, a cutting unit, and a sorting bin;  
         [0010]    [0010]FIG. 6 is a plan view of the offset forming unit;  
         [0011]    [0011]FIG. 7 is a side elevation view of the sorting bin;  
         [0012]    [0012]FIG. 8 is a front elevation view of the sorting bin;  
         [0013]    [0013]FIG. 9 is a side elevation view of a coil former;  
         [0014]    [0014]FIG. 10 is a front elevation view of the coil former;  
         [0015]    [0015]FIG. 11 is a side elevation view of a lead bender;  
         [0016]    [0016]FIG. 12 is a side elevation view of coil presses and trimming units;  
         [0017]    [0017]FIG. 13 is a side elevation view of a coil press die; and  
         [0018]    [0018]FIG. 14 is a side elevation view of a trim die. 
     
    
     DETAILED DESCRIPTION  
       [0019]    In the disclosed method, copper wire is continuously spooled from a reel and fed through a series of machines to form the finished armature coil having the configuration shown in FIGS. 3 and 4. The method comprises the steps of continuously advancing the copper wire fed from the reel, stripping insulating coating from the wire in selected locations along its length in preparation for cutting the wire and forming leads, offsetting the wire at one of a series of three sequential predetermined locations for the series of the wires forming the coil, cutting the offset wires from the reel such that each offset wire is of predetermined length and contains one of the offsets, sorting the offset wires according to the positions of the offsets, pressing the two corresponding offset wires together at their offsets to form transposed wire pairs, wrapping the transposed wire pairs with an insulating material to form packs, assembling three pairs of transposed wires together to form a pack, deforming and shaping the packs to form armature coils, flattening and trimming the leads of the armature coils to a predetermined length, and applying insulating tape on the formed armature coils intermediate the leads.  
         [0020]    Referring to FIG. 1, a transposed pair of wires is shown generally at  10 . Transposed pair of wires  10  comprises two strands  12 ,  14  of copper wire pressed together axially to form a transposition  18  and having leads  16  formed on each end thereof. Leads  16  are defined by areas on each end of transposed pair of wires  10  where the polymeric material has been stripped away leaving only copper wire exposed. A finished armature coil (illustrated with reference to FIGS. 3 and 4), shown generally at  20 , is constructed from a plurality of transposed pairs of wires  10  stacked together and wrapped with insulating tape to form a single pack  19  (illustrated with reference to FIG. 2). Each strand  12 ,  14  of transposed pair of wires  10  is coated with a polymeric material (not shown) that is predisposed on the copper wire. The construction of transposed pair of wires  10  from two strands  12 ,  14  of wire positioned in a parallel relationship minimizes the eddy current losses from each individual strand  12 ,  14 . The presence of fluxes between strands  12 ,  14 , however, which are not uniform and in fact vary radially in density, cause an induced voltage generated within formed armature coil  20  to vary from strand to strand when a plurality of transposed pairs of wires  10  are stacked together to form pack  19 . This variance of the induced voltage causes excessive voltage losses and heating within formed armature coil  20 . The presence of transpositions  18  introduced into the wire pairs assists in the amelioration of this variance.  
         [0021]    The finished armature coil  20 , as shown in FIGS. 3 and 4, is formed by the method disclosed herein. As can be seen in FIG. 3, finished armature coil  20  has a main body portion  22  with legs  24 ,  26  depending therefrom at an angle  28 . The free end of leg  24  is a commutator end, and the free end of leg  26  is a pinion end. Leads  16  depend from each leg  24 ,  26  and are shaped and bent to extend away from each leg  24 ,  26  at various radii and are configured to extend parallel to main body portion  22 . Each transposed pair of wires  10  used to construct armature coil  20  has transposition  18  formed therein at a point different from the points at which the transpositions  18  of the other two pairs of wire strands are formed in order to minimize the circulating electrical currents and overheating, as described above.  
         [0022]    Finished armature coil  20  is configured such that transpositions  18  in each transposed pair of wires  10  are positioned at various points along the length of formed armature coil  20 . In particular, transposed pairs of wires  10  are arranged into packs  19  such that a first transposition  18  is positioned substantially centrally on armature coil  20 . A second transposition  18  and a third transposition  18  are each positioned equidistant from first transposition  18  but are disposed on opposing sides of first transposition  18 . This staggering of the positions of transpositions  18  serves to minimize the circulating electrical currents and resultant heating of finished armature coil  20  during operation. The process of forming transpositions  18  is discussed below.  
         [0023]    Referring back to FIG. 2, it can be seen that finished armature coil  20  comprises three transposed wire pairs  10  to form pack  19 . Each individual transposed wire pair  10  has a rectangular cross sectional shape, and is arranged in a face-to-face orientation with respect to each other to form pack  19 . Leads  16  are configured on the ends of pack  19  to define a space therebetween (as can be best seen in FIG. 3) and are dimensioned to be received and frictionally retained in the sockets of a riser of a commutator (not shown). The proper shaping of leads  16  is described below with reference to FIGS. 11 through 14. In its final form, armature coil  20  is defined by pinion end that corresponds to leg  26  and its associated leads  16  and commutator end that corresponds to leg  24  and its associated leads  16 . Leads  16  associated with either end are distinct from each other, thereby rendering armature coil  20  polarized and enabling armature coil  20  to be installed in only a single orientation.  
         [0024]    Referring to FIG. 5, the assembly line method of forming armature coil  20  is shown. The assembly process comprises advancing the copper wire through a series of machines to form the finished armature coil  20 . The copper wire, which is coated with the polymeric material prior to being wound on a reel  30 , is fed from reel  30  through a straightening apparatus  32 . Because the wire has been wound on reel  30 , the wire has been axially deformed and has a tendency to return to the wound position when unsupported. Straightening apparatus  32 , which comprises a series of rollers (not shown), is configured to force the wire to bend in the opposite direction that the unsupported wire will tend to bend.  
         [0025]    Once the wire is straightened and leaves wire straightening apparatus  32 , it is fed into a wire stripping unit, shown generally at  34 . In wire stripping unit  34 , the polymeric coating is removed from portions of the copper wire that will ultimately correspond to leads  16  of the finished armature coil  20 . The portions of the wire from which the polymeric coatings are removed are about two or three inches in length and vary with respect to whether the portion of wire will be used to form the top, middle, or bottom transposed pair of wires  10  in pack  19 . The polymeric coating may be removed by a suitable abrasion mechanism, such as by brushing the copper wire with a wire brush (not shown) in the appropriate places, by passing the copper wire between wheels (not shown) having an abrasive coating disposed thereon, or by feeding the copper wire through a series of sanding drums  36  positioned to engage the wire in two planes and wherein each sanding drum  36  has an abrasive outer surface that contacts the coating. If the latter procedure is employed, as the outer surface of the polymeric coating on the wire is engaged by the abrasive outer surfaces of sanding drum  36 , the polymeric coating is removed from selected locations along the wire.  
         [0026]    Referring to both FIGS. 5 and 6, after the copper wire is stripped of its polymeric coating from the portions that will be cut and formed into leads  16 , the wire is fed into an offset assembly unit  38  where an offset is formed in the wire by a die  39  positioned on the end of a pivoting arm  41 . The position of the offset in the wire, which is eventually used to form transposition  18 , determines the position of the wire when it is assembled with other wires into pack  19 . Offset assembly unit  38 , which is shown in detail in FIG. 6, is electronically configured to vary the distance between an end stop for the wire and the transposition die, thereby varying the position of the offset placed into the wire. The lengths of wire for the three different offsets may be the same; however, three different lengths of offset wire are used to compensate for the bends of different radii in the offset wires to form leads  16 , as is illustrated in FIG. 3.  
         [0027]    Each finished armature coil  20  comprises at least three separate transposed pairs of wires  10  formed into pack  19 , and each pack  19  is used to form finished armature coil  20 . However, finished armature coil  20  forms only either a top or a bottom of a complete armature coil. A second assembly line of machines (not shown) similar to that of the first assembly line described above may be provided to form the corresponding finished armature coil needed to make a complete coil. The second assembly line machines would be programmed to account for the differences in the lengths of the copper wire, the lengths and locations of the exposed leads and the packs necessary to form the other finished armature coil for the complete coil.  
         [0028]    Returning to the first assembly line, offset wire is fed from offset forming unit  38  to a cutting unit  40 , in which the offset wire is cut at the exposed portions of the wire to yield a single offset wire terminating in leads  16  at each end. The offset wire is fed through one or more suitable wire length measurement sensors, such as a series of feed wheels coupled to encoders to measure lengths of the offset wire and to transmit an electronic signal to cutting unit  40 , the abrasion mechanism and the offset forming unit. Cutting unit  40  is configured to receive the signal from the sensor and responds to the signal by severing the offset wire in predetermined locations in register with the locations on the wire at which the polymeric coating was removed. The offset wire is thereby transformed into a single discrete wire strand  12 ,  14  having an offset formed therein. Every third offset wire formed and severed from reel  30  has an offset formed therein in substantially the same place and is joined to a second similar offset wire in the assembly of a new armature coil  20 . From cutting unit  40 , offset wires are fed to a sorting bin, shown generally at  42 .  
         [0029]    Referring now to FIGS. 7 and 8, sorting bin  42  is shown in greater detail. Sorting bin  42  comprises a series of panels  43  horizontally arranged with respect to a level plane of a flooring surface on a support stand, shown generally at  45 . Each offset wire is ejected from cutting unit  40  after being cut from reel  30  of copper wire and is received into an intake area, shown generally at  47 , on an upper portion of sorting bin  42 . Intake area  47  is pivotally mounted along a longitudinal axis  49  thereof on the upper portion of sorting bin  42 . The pivotal motion of intake area  47  causes the offset wire received therein to drop onto panels  43 .  
         [0030]    A series of mechanical gates  44  formed within panels  43  are mechanically controlled to open and close in order to channel the offset wire into a designated compartment  46 . One method of controlling gates  44  may be through the use of a pneumatic actuator. Gate operating mechanisms  51  are positioned on a back side  53  of sorting bin  42  and are pivotally connected to gates  44  through linkages  55 . Gate operating mechanisms  51  are in electronic communication with cutting unit  40  and are configured electronically to respond to the sequential cutting of the offset wires such that the offset wires having offsets located in the same area along the length of the offset wires are deposited in the same compartment  46  in sorting bin  42 . The operation of sorting bin  42  to separate the offset wires allows for the assembly line format of sequential stripping, offsetting, cutting, sorting, pressing, wrapping, assembling, forming, flattening, trimming, and re-wrapping of copper wire to construct each individual armature coil  20  while preventing the buildup of a large inventory of offset wires of a single configuration.  
         [0031]    After being deposited into its appropriate compartment  46  in sorting bin  42 , a pair of corresponding offset wires are removed from sorting bin  42 . The two offset wires are fed into a press (not shown), which forces the offset wire strands  12 ,  14  into each other to form transposed pairs of wires  10  having transposition  18 . After the transposition is formed, the wires are disconnected, an insulating spacer (not shown) is positioned between strands  12 ,  14  of each transposed pair of wires  10  proximate the point where strands  12 ,  14  contain transpositions  18 , and the wires are fitted back together. The insulating spacer defines a distance between strands  12 ,  14 , thereby serving to suppress radial fluxes generated between each strand  12 ,  14  of each transposed pair of wires  10 . Utilizing a first wrapping machine (not shown), transposed pairs of wires  10  are then wrapped with an insulating tape (not shown), which further suppresses radial fluxes between strands  12 ,  14 . The insulating tape is placed on transposed pairs of wires  10  intermediate the end portions, which will eventually be formed into leads  16 .  
         [0032]    Utilizing a second wrapping machine (not shown), three wrapped transposed pairs of wires  10 , each having their transposition  18  in different locations along the lengths thereof relative to the other two wrapped transposed pairs of wires  10 , are assembled and wrapped together with the insulating tape to form pack  19 .  
         [0033]    Referring now to FIGS. 9 and 10, pack  19  is then fed by hand to an armature coil former, shown generally at  56 , which deforms the entire pack  19  into the proper shape, thereby making it into armature coil  20 . Armature coil former  56  is essentially a hydraulically powered “shaping device” on which pack  19  is bent in two directions to form legs  24 ,  26  of the finished armature coil  20 . Armature coil former  56  comprises a pair of mounts  57  placed side-by-side, a pair of forms  59  placed side-by-side and proximate pair of mounts  57  to define a channel  61  therebetween, and lead benders  63 . Forms  59  have an arcuate surface disposed on a face  64  thereof, which corresponds with the curve of legs  24 ,  26  of armature coil  20 . Lead benders  63  are pivotally mounted at pivot point  75  proximate a lower surface of forms  59 , one lead bender  63  being positioned on each side of forms  59 .  
         [0034]    Lead benders  63 , one of which is shown in FIG. 11, comprise a first member  65  slidably positioned inside a second member  67  to form a sliding assembly  69  and a series of lead holes  71  positioned longitudinally within first member  65  at an end thereof that is proximate a pivot point  75  thereof configured to receive leads  16  protruding from the ends of transposed pairs of wires  10 . Each lead hole  71  is dimensioned and configured to provide a bend in the wire that is of the proper radius. A spring loaded handle  73  is perpendicularly attached to lead bender  63  and is in mechanical communication with both first member  65  and second member  67 . Spring loaded handle  73  is used to lock first member  65  into an extended position relative to second member  67 .  
         [0035]    When pack  19  is mounted in channel  61 , rollers  58 , which extend under hydraulic power, force pack  19  to deform and to conform to the shape of the outer edges of forms  59 . As the ends of pack  19  extend downward toward lead benders  63  and form legs  24 ,  26 , lead benders  63  are pivoted to extend coaxially with legs  24 ,  26 . The ends of legs  24 ,  26  are then inserted into lead holes  71 , and first member  65  and second member  67  are locked into position by spring loaded handle  73 . Finally, lead benders  63  are pivoted back to their original positions to form leads  16 . More accurate positioning of leads  16  in the coil forming step decreases the amount of copper wire that must be trimmed in the shaping and trimming steps (described below), thereby resulting in a better fit with the riser of the commutator.  
         [0036]    Referring now to FIG. 12, armature coils  20  are then transferred from coil former  48  to coil presses, which are shown generally at  66 , and to trim units, which are shown generally at  68 . Pinion end legs  26  and commutator end legs  24  of each armature coil  20  are flattened into thinner planar members by a flatten die (described below and shown with reference to FIG. 13) to properly shape leads  16  and are then trimmed by a trim die (described below and shown with reference to FIG. 12) to ensure that finished armature coil  20  meets desired dimensional specifications. Two separate coil presses  66  and two separate trim units  68  are utilized, each being preset to accommodate the dimensions of a corresponding pinion end leg  26  or commutator end leg  24  of armature coil  20 .  
         [0037]    In FIG. 13, a flatten die used in coil presses  66  is shown generally at  70 . Leads  16  are inserted into openings  72  between platens  74  of flatten die  70 . Platens are then pressed together by a force F acting normal to the surfaces of platens  74 . As leads  16  are pressed in the direction of force F, side surfaces  76  limit the deformation of leads  16  in lateral directions, thereby squeezing leads  16  into shapes having generally rectangular cross sections.  
         [0038]    Leads  16  protruding from the ends of armature coil  20  are then trimmed using a trimming die  78 , shown in FIG. 14, to form the finished armature coil  20  having a preselected length. Leads  16 , which have been previously shaped by coil presses  66 , are inserted into openings  80  between platens  82  of trimming die  78  in a manner similar to that used in the shaping of leads  16 . A punch  84  is positioned in an aperture  86  centrally located in trimming die  78 . The movement of punch  84  within aperture  86  in the direction of an arrow  88  then forcibly cuts any parts of leads  16  that protrude through openings  80  into aperture  86 , thereby trimming off excess material on the ends of leads  16  and ensuring that armature coil  20  is at the proper dimensions. The body portion of finished armature coil  20  intermediate leads  16  is then wrapped in insulating tape to electrically insulate the finished product.  
         [0039]    Assembly of armature coils of the related art utilize methods in which transposed wire pairs are formed into the shape of a finished armature coil and subsequently assembled. The afore-described assembly line method provides superior control capabilities over the related art while minimizing the number and magnitude of process control problems. In particular, the methods of the related art in which strands of wire are offset, transposed, shaped, and then assembled into coils mandates strict tolerances in the manufacture of the wire. Such strict tolerances impede the processes of cutting and trimming the wire to accurately form leads. Automatic electronic control of the offsetting and cutting of the wire, as described herein, enables the strict tolerances of the related art systems to be relaxed, thereby allowing for faster production with less waste generated.  
         [0040]    Further, the automated controls of the described assembly line provide significant flexibility of manufacture so that the lengths of the wire strips can be varied and controlled both as among the strips to account for the finished shape of the coil (such as the coil in FIG. 3) or overall to enable different coils to be manufactured. Moreover, the position and length of the removed portion of the insulation on the wire can be varied and controlled. In addition, the location of the offset along the length of the strands (or the elimination of the offsets altogether) can be varied and controlled to enable different coils to be manufactured, including coils without transpositions.  
         [0041]    While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.