Abstract:
Apparatus and methods for reducing the likelihood of damage to wire leads of undulated coils for dynamo-electric machine stators are provided. The invention provides a rotating winding head equipped with a coil former that has a wire gripper and an initial wire lead slot. The gripper retains the initial wire lead. The slot permits the initial wire lead to be fed to the gripper from a stationary wire source. The gripper maintains the initial wire lead in a predetermined plane of the coil and can secure the initial wire lead in the plane in which the final lead wire will eventually be disposed. The gripper also rotates the initial wire lead into radial alignment with a lobe of the undulated coil. Once installed in a stator, the initial and final wire leads can both be disposed along the outer radius of the coil and are thus protected from interference with a rotor that is destined to rotate within the stator.

Description:
[0001]    This application claims the benefit of provisional application No. 60/129,094, filed Apr. 13, 1999, which is hereby incorporated by reference herein in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to winding coils for lamination stacks of a stator. More particularly, the solutions of the invention are concerned with winding coils of alternator stators, and forming the relative end leads. The coils that become wound by the solutions of the invention have an undulated shape, like those that are formed by the apparatus and functioning principles described in U.S. Pat. No. 4,512,376 (herein referred to as “Barrera &#39;376”) assigned to the same assignee of this application. (Barrera &#39;376 is hereby incorporated by reference herein in its entirety.)  
           [0003]    As shown in FIG. 1, which is a perspective view of a traditional undulated coil  10  formed according to the principles of Barrera &#39;376, coil  10  has a central axis O, which is substantially perpendicular to the various wire turns  20  of the coil, each of the wire turns defining a plane P. (Those skilled in the art will appreciate that a reference to a “plane” in connection with a helical coil is an approximation used for convenience herein.) Initial lead  11  of the coil is contained in lowermost plane A of the planes P, while final lead  12  is contained in uppermost plane B of the planes P. Coil  10  becomes inserted in respective slots  13  of stator stack  14  as shown in FIG. 2. This is done by means of an insertion operation requiring pushing of the coil in the longitudinal direction  15 , parallel to axis O, with the stator stack in an overhead position, aligned with axis  0 . The coil is placed on an insertion tool (not shown) to accomplish such an operation. In pushing the coil into the stator stack, radial arms  16  of the coil become inserted in the slots  13 , while bridging sections  17  form the end portions of the coils, and are located outside the extreme faces of the stack. As shown in FIG. 2, leads  11  and  12  have been rotated to become practically parallel to axis O. In FIG. 2 the stator stack has been turned upside down with respect to the position which it would have when pushing in direction  15  of FIG. 1 during the insertion operation. The distances of leads  11  and  12  from axis O after the coil has been inserted in the stator stack are particularly pertinent to presentation of this invention. As shown in FIG. 2, initial lead  11  is nearer to axis O than final lead  12 .  
           [0004]    Usually, at least three coils (often referred to as phase coils) like coil  10  are inserted in the stator stack to form the final product. These can be inserted into the stator stack simultaneously or separately. Each coil will be inserted in respective and different sets of slots. When inserted, the coils will be at different radial distances from center axis O of the stack, as shown by references R 1 , R 2  and R 3  in FIG. 3, corresponding to coils  8 ,  9 , and  10 . FIG. 3 is a partial view of the stator, as seen from direction  3 - 3  of FIG. 2, but with all three coils inserted, as would be required in the final product. For sake of clarity only one coil has been shown in FIG. 2.  
           [0005]    It is clear from FIG. 3 that initial lead ii of coil  10  (the nearest to axis O) can be very near to central opening  10 ′ of the stack. This is also evident from FIG. 3 a , which is a view from direction  3   a - 3   a  of FIG. 3. (The location of axis O is not shown accurately in FIG. 3 a  or FIG. 11 to avoid unduly enlarging these FIGS.) Furthermore, initial lead  11  does not have bridge portions  17  between itself and central opening  10 ′. This renders initial lead  11  more unstable to lateral displacements (in particular, in the radial direction with respect to the central axis) compared to the other leads. Because of this, small accidental displacements of initial lead  11  toward center axis O can cause it to enter central opening  10 ′ of the stator stack. Such a situation can cause a physical interference of the initial lead  11  with the rotor that is destined to rotate in central opening  10 ′. A frequent consequence of this is damage to the initial lead.  
           [0006]    In view of the foregoing, it would be desirable to provide improved methods and apparatus for winding undulated coils for dynamo-electric machine stators. It would also be desirable to provide methods and apparatus for winding undulated coils for dynamo-electric machine stators that reduce the likelihood of damage to lead wires. It would further be desirable to provide an undulated coil whose wire leads are less susceptible to damage.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of this invention to provide improved methods and apparatus for winding undulated coils for dynamo-electric machine stators. It is also an object of this invention to provide methods and apparatus for winding undulated coils for dynamo-electric machine stators that reduce the likelihood of interference between lead wires and rotors of dynamo-electric machines. It is a further object of this invention to provide an undulated coil whose wire leads are less susceptible to damage.  
           [0008]    These and other objects are accomplished by providing a wire coil winding head which includes, among other features, a gripper configured to hold an initial lead of the wire; a receiver structure configured to receive the wire extending from the gripper and to form a coil of the wire having successive turns that are substantially disposed in respective planes that are substantially perpendicular to a central longitudinal axis of the coil and laterally spaced from one another along that axis; a forming structure configured to produce undulations in the turns of wire in their respective planes while the turns are on the receiver structure, the undulations giving the turns portions that are substantially radial of the axis; and a gripper positioning structure configured to position the gripper relative to the receiver structure so that the initial and final leads can be placed substantially in the same plane as each other and each lead can also be substantially aligned with a respective portion of the coil that is substantially radially disposed with respect to the longitudinal axis. Accordingly, the invention permits both initial and final leads, as installed in a stator, to be disposed at a safe distance from the rotor destined to rotate within the stator.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a perspective view of a traditional undulated coil showing initial and final leads disposed on opposite faces of the coil  
         [0010]    [0010]FIG. 2 is a perspective view of the undulated coil of FIG. 1 inserted in a stator stack.  
         [0011]    [0011]FIG. 3 is a partial perspective view of the stator stack of FIG. 2 loaded with three undulated coils as viewed from the direction  3 - 3  in FIG. 2.  
         [0012]    [0012]FIG. 3 a  is a partial top plan view of the loaded stator of FIG. 3 as viewed from the direction  3   a - 3   a  in FIG. 3.  
         [0013]    [0013]FIG. 4 is a top plan view of a winding head for winding an undulated coil according to the principles of the invention.  
         [0014]    [0014]FIG. 5 is a partial perspective view of a coil wound according to the invention.  
         [0015]    [0015]FIG. 6 is a partial top plan view of a stator similar to that of FIG. 3 a , but having been loaded with the undulated coil of FIG. 5.  
         [0016]    [0016]FIG. 7 is a side elevational view from direction  7  of FIG. 4 showing the forming member of the winding head of FIG. 4 that is provided with an implementation of the invention.  
         [0017]    [0017]FIG. 8 is an elevational view of the forming member of FIG. 7 from direction  8 - 8  in FIG. 7.  
         [0018]    [0018]FIG. 9 is a cross-sectional view taken along the line  9 - 9  in FIG. 7 showing a wire engaged by a gripper and passing through an aperture of the forming member of FIG. 7.  
         [0019]    [0019]FIG. 10 is a cross-sectional view similar to FIG. 9 showing the wire, the gripper, and the forming member of FIG. 7 after the winding head of FIG. 4 has begun to rotate.  
         [0020]    [0020]FIG. 11 is an elevational view along direction  11 - 11  of FIG. 4 showing wire turns disposed on the forming member of FIG. 7 and an adjacent forming member.  
         [0021]    [0021]FIG. 12 is a simplified elevational view, partly in section, showing portions of an illustrative alternative embodiment of apparatus in accordance with the invention.  
         [0022]    [0022]FIGS. 13 a  and  13   b  are simplified sectional views taken along the line  13 - 13  in FIG. 12 showing two different operating conditions of a portion of the FIG. 12 apparatus.  
         [0023]    [0023]FIG. 14 is a simplified sectional view taken along the line  14 - 14  in FIG. 12.  
         [0024]    [0024]FIGS. 15 a  and  15   b  are simplified sectional views taken along the line  15 - 15  in FIG. 12 showing two different operating conditions of another portion of the FIG. 12 apparatus.  
         [0025]    [0025]FIG. 16 is a view similar to FIG. 13 a  or  13   b , but showing two different operating positions and conditions of a portion of the apparatus.  
         [0026]    [0026]FIG. 17 is a view similar to FIG. 16 showing a later stage in the operation of the apparatus.  
         [0027]    [0027]FIG. 18 is another view similar to FIG. 17 showing a still later stage in the operation of the apparatus.  
         [0028]    [0028]FIG. 19 a  is a simplified elevational view showing another illustrative alternative embodiment in accordance with the invention.  
         [0029]    [0029]FIGS. 19 b - d  are views similar to FIG. 19 a  showing successive stages in the operation of the FIG. 19 a  embodiment.  
         [0030]    [0030]FIG. 20 a  is a simplified elevational view showing still another illustrative alternative embodiment in accordance with the invention.  
         [0031]    [0031]FIGS. 20 b - e  are views similar to FIG. 20 a  showing successive stages in the operation of the FIG. 20 a  embodiment.  
         [0032]    [0032]FIGS. 21 a  is a simplified elevational view showing yet another illustrative alternative embodiment in accordance with the invention.  
         [0033]    [0033]FIGS. 21 b - e  are views similar to FIG. 21 a  showing successive stages in the operation of the FIG. 21 a  embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    [0034]FIG. 4 shows an apparatus for forming an undulated wire coil according to the principles of the invention. Wire gripper  43  secures the end of a wire W to forming member  40 ′ of support structure  42 . Support structure  42  is a winding head according to Barrera &#39;376, although modified according to this invention, and carries a plurality of forming members  40  that are arranged in a polygon.  
         [0035]    Support structure  42  is rotated around axis O while initial lead  11  is gripped by gripper  43 . Wire W is thus pulled from the source and wound on forming members  40  to accumulate a plurality of polygonal wire turns that, together, form a polygonal coil. During rotation of support structure  42 , wire W is guided toward the winding head by stationary wire feeding guide  41 , which is preferably a nozzle. The end of wire W becomes initial lead  11  of initial wire turn  30 .  
         [0036]    A second plurality of forming members  45  is also present on support structure  42 , external to the polygonal wire coil formed on forming members  40 . Forming members  45  can push inwardly on the lateral segments, or sides, of the polygonal wire coil. This pushing action, together with a simultaneous radial movement of the forming members  40  toward central axis O, produces undulations in a coil, for example coil  26 , as shown in FIG. 5.  
         [0037]    After undulations have been formed, initial lead  11  is released from gripper  43  and wire W is severed from the source wire to form final wire lead  12 . Final wire lead  12  extends from final wire turn  32  and is arranged in plane B with initial lead  11 . Then, coil  26  is stripped off forming members  40  to be placed on an insertion tool (not shown) for successive insertion into the stator stack with initial and final leads,  11  and  12 , respectively, substantially equidistant from central axis O as shown in FIG. 6.  
         [0038]    From FIG. 6 it is evident that initial lead  11  is more exterior with respect to opening  10 ′ than its counterpart in the prior art discussed above. Also, lead  11  has bridge portions  17  between itself and opening  10 ′. These conditions make initial lead  11  less vulnerable to displacements that would bring it into or over interior opening  10 ′.  
         [0039]    The formation of a coil such as coil  26  will now be explained in greater detail with reference to FIGS.  7 - 11 . FIG. 7 is a view along  7 - 7  of FIG. 4, showing forming member  40 ′ with an implementation of this invention at the initial loading stage. According to the principles of this invention, gripper  43  has been placed at level L 1  of forming member  40 ′. Prior to this invention, a gripper was located at level L 2 , as shown by the dashed line representation of the gripper&#39;s contour, referenced  43 ″. Additionally, forming member  40 ′ is provided with initial lead aperture  44  adjacent gripper  43  for receiving initial lead  11  while gripper  43  grips initial lead ii.  
         [0040]    Prior to winding a new coil, gripper  43  and initial lead aperture  44  are aligned with feed device  46  by means of a controlled and predetermined rotation of support structure  42 . After alignment, feed device  46  pulls the end of wire W from the source and feeds it through gripper  43  and into initial lead aperture  44 , as shown in FIG. 7.  
         [0041]    [0041]FIG. 8 is a view from directions  8 - 8  of FIG. 7 showing that initial lead aperture  44  passes right through forming member  401 . Also evident from FIG. 8 is that initial lead aperture  44  has an open side  441 . Gripper  43  has been omitted in FIG. 8 to more clearly show initial lead aperture  44 . However middle axis  43 ′ of gripper  43  has been shown. FIG. 9 shows the initial position of initial wire lead  11  in initial wire lead aperture  44  along the line  9 - 9  of FIG. 7.  
         [0042]    Once the end of wire W has been passed through initial lead aperture  11  and gripped by gripper  43 , support structure  42  is rotated in direction  421 . FIG. 10 shows that as rotation of support structure  42  occurs, gripper  43  rotates around axis  43 ′ due to torque from tension in wire W. The rotation of gripper  43  causes initial lead  11  to rotate, or pivot, about axis  431  (see arrow A in FIG. 10). Initial lead  11  moves substantially in a plane perpendicular to central axis O, passes laterally through open side  44 ′, and rotates into an orientation tangential to an apex of the polygon form (resistance in the rotation of gripper  43  causes wire W to bend around gripper  43 ). Ultimately, as forming members  45  create undulations in the coil, initial lead  11  is aligned substantially parallel to radial arm  36  (see FIG. 5).  
         [0043]    The side of forming member  40 ′ on which open side  44 ′ is disposed, and the corresponding side of gripper  43  on which initial lead  11  is gripped, depends on the direction of rotation of support structure  42 . The side which has been shown here is consistent with direction  42 ′ as chosen for the rotation of support structure  42 .  
         [0044]    [0044]FIG. 11 is a view from direction  11 - 11  of FIG. 4 showing how the turns of the polygon coil dispose themselves. The wire for first turn  30 , starting from initial lead  11 , is deposited on forming member  40 ′ and on immediately adjacent forming member  40 ″. It is seen, with reference also to FIG. 7, that the wire just leaving the nozzle during rotation of support structure  42  is received by curved seats  47 .  
         [0045]    Curved seats  47  extend from slanted sides  48  of forming members  40 . As additional turns are deposited, the additional turns are allowed to urge the a previously wound turns in a progressive and orderly descent out of curved seats  47  and onto inner end portions  48 ″ of slanted sides  48 . As winding continues, wire turns are urged further downward along slanted side  48 , toward outer end portions  48 ′ until slanted sides  48  support a plurality of wire turns  21  shown in FIG. 11 (inner end portions  48 ″ are radially closer to central axis O than are outer end portions  48 ′).  
         [0046]    Wire turns  21  form a helical coil that has turns that are placed on various planes P, including initial turn plane A and final turn plane B. The accumulation of wire turns  21  grows toward plane B as more turns are deposited. At any stage during the winding, last deposited wire turn  32 ′ defines a last deposited turn plane, B′, which is closer to initial turn plane A than is final turn plane B. Initial lead  11  in final turn plane B extends from gripper  43  to initial turn plane A on forming member  40 ″ of FIG. 11, by means of slanted transitional wire portion  11 ′. When coil  26  is removed from support structure  42 , initial wire lead  11  is placed flush against last deposited turn  32 ′. Consequently, planes B and B′ merge with each other and last deposited turn  32 ′ of FIG. 11 becomes final wire turn  32  of FIG. 6.  
         [0047]    It will be appreciated that curved seats  47  have apices  47 ′ that, taken together, define an apical plane substantially perpendicular to central axis O. Gripper  43  is disposed on one side of the apical plane and slanted sides  48  are disposed on the other side. This configuration permits initial lead  11  to be held adjacent the plane in which final lead  12  is destined to be deposited while turns  21  are accumulated. Initial lead  11  and final lead  12  can therefore be arranged in the same plane in the final coil.  
         [0048]    After the helical coil is formed, forming members  45  form undulations as discussed above. Then, gripper  43  releases initial lead  11  so that coil  26  can be stripped off the winding head in order to transfer the coil to an insertion tool. As soon as initial lead  11  has been released, gripper  43  grasps the wire extending from the nozzle to final turn  32 . Then, cutter device  50  of FIG. 7 cuts wire W between feed device  46  and forming members  40  to form final lead  12 .  
         [0049]    Cutter device  50  cuts wire W after forming member  40 ′ is aligned with cutter device  50 . More precisely, the side of forming member  40 ′ which is opposite the side on which initial lead  11  is ultimately positioned will be aligned with cutter device  50 . Like initial lead  11 , final lead  12  of coil  26  is contained in plane B. Bridge portion  17 ′ of the coil, between initial lead  11  and final lead  12  is formed by forming member  40 ′ as shown in FIG. 5.  
         [0050]    [0050]FIG. 12 shows an alternative illustrative embodiment of a forming structure  140 ′, a gripper  143 , and associated apparatus in accordance with the invention. The apparatus shown in FIG. 12 can take the place of forming structure  40 ′ in FIG. 4, with the remainder of the apparatus shown in FIG. 4 being substantially unaltered if desired. FIG. 12 is an elevational view from the center (FIG. 4) of support structure  42 .  
         [0051]    Support member  110  is a portion of or is fixedly mounted on support structure  42  (FIG. 4). Support member  110  has a downwardly projecting dovetail key  110   a  on its lower surface. Key  110   a  extends radially relative to the center O of support structure  42  (FIG. 4). Forming structure  140 ′ is mounted for movement along key  110   a  via a dovetail keyway  112  in the upper surface of a main body portion  111  of forming structure  140 ′.  
         [0052]    The actual coil-forming portion of forming structure  140 ′ is the lower portion of structure  113  as viewed in FIG. 12. This portion of the structure (which extends up into main body portion  111 ) is supported by main body portion  111  and is selectively rotatable about axis  101 ′ relative to the main body portion. The thus-rotatable elements (sometimes referred to generically or collectively by reference number  113 ) include shaft  118  and clamp structure  120 , both described in more detail below. In addition to being generally rotatable with structure  113 , vertically aligned shaft  118  is mounted for limited rotational motion relative to structure  113  about axis  101 ′ as will be described in greater detail below.  
         [0053]    Rotatable structure  113  may have a releasable detent connection (not shown) relative to main body portion  111  (e.g., to releasably hold rotatable structure  113  in the rotational orientation shown in FIG. 12). Rotatable structure  113  may also be releasably locked in this orientation (or in an operationally similar orientation 180° from the FIG. 12 orientation) by use of the features shown in FIG. 14. In particular, FIG. 14 shows that at the vertical location shown in that FIG. the outer surface of rotatable structure  113  includes surfaces  123 ′ that are inclined relative to axis  103 ′. Locking block  123  is mounted in main body  111  for movement (e.g., by a hydraulic or pneumatic actuator which is not shown) along axis  103 ′ toward ( 123 ″) or away from ( 123 ′″) rotatable structure  113 . When rotatable structure  113  has the orientation (or approximate orientation) shown in FIG. 14 and locking block  123  is reciprocated toward axis  101 ′, inclined surfaces  126  on locking block  123  engage with surfaces  123 ′ on rotatable structure  113  and prevent rotation of structure  113  relative to main body  111 . (Such reciprocation of locking block  123  also has another effect on the apparatus which will be described below.) When locking block  123  is retracted to the position shown in FIG. 14, locking block  123  releases structure  113  for rotation about axis  101 ′. of course, structure  113  may also have the above-mentioned releasable detent association with main body  111  to releasably maintain structure  113  in a particular rotational orientation such as the one shown in FIG. 14 even when locking block  123  is not engaged.  
         [0054]    Shaft  118 , which is vertically disposed in rotatable structure  113  substantially concentric with axis  101 ′, has different exterior surface shapes at various locations along its length. As shown in FIGS. 13 a  and  13   b , for example, the lower portion of shaft  118  has an elongated cross section. At this level in the apparatus (and also below this level) rotatable structure  113  is shaped to define four downwardly extending fingers  113   a ,  113   b ,  113   c , and  113   d  disposed around shaft  118 . (The pin  119  shown in dotted lines in FIGS. 13 a  and  13   b  is actually at a higher level in the apparatus as will be discussed in more detail below.) Fingers  113   a - d  and the side surfaces of shaft 0.118 cooperate to define two substantially parallel slots  114  and  115  that are vertically aligned and that extend across the lower portion of rotatable structure  113  on respective opposite sides of axis  101 ′. Below the lower end of shaft  118  slots  114  and  115  continue (as wider slots  114 ′ and  115 ′, respectively (see FIG. 12)) and open out the bottom of rotatable structure  113 .  
         [0055]    Returning to FIGS. 13 a  and  13   b , at the level of the lower portion of shaft  118 , it is seen that shaft  118  has an outer peripheral surface portion that has nonuniform spacing from axis  101 ′ in a direction annularly around axis  101 ′. (Axis  101 ′ substantially coincides with a central longitudinal axis of shaft  118 .) At this level, slots  114  and  115  are wide enough when shaft  118  has the orientation shown in FIG. 13 a  to easily and relatively loosely receive a lead L (see FIG. 13 b ) of the wire to be wound. After a slot  114  or  115  has received such a lead L, shaft  118  can be rotated about axis  101 ′ relative to structure  113  to the orientation shown in FIG. 13 b  to pinch the lead against the adjacent finger, or anvil structure,  113   a  or  113   b  and thereby securely hold the lead in the gripper portion  143  (FIG. 12) of forming structure  140 ′. Lead L can be released from gripper  143  by rotating shaft  118  back to the position shown in FIG. 13 a . Lead L can be inserted in a slot  114  or  115  by extending the lead wire axially across the slot. Lead L is typically removed from a slot  114  or  115  by moving the lead downwardly via the associated slot  114 ′ or  115 ′ as the associated coil is stripped from forming structure  140 ′ and the other forming structures of the apparatus.  
         [0056]    The elements that are used for rotationally positioning shaft  118  relative to rotatable structure  113  are perhaps best seen in FIGS. 14, 15 a , and  15   b , with the aid of FIG. 12. FIG. 14 has already been partly described, but it will now be further described with particular reference to pin  119  and related elements. Pin  119  extends transversely across shaft  118  and is fixedly mounted therein. At the level of pin  119 , rotatable structure  113  has windows  122  which allow the ends of the pin to pass out through structure  113  without contacting structure  113  even when shaft  118  is rotated relative to structure  113 . The “normal” position of pin  119  is the one shown in dotted lines in FIG. 14. This corresponds to the position of pin  119  shown in FIG. 13 b  and also in FIG. 15 a.    
         [0057]    When locking block  123  is reciprocated toward axis  101 ′ as described earlier in connection with FIG. 14, surfaces  124  on locking block  123  contact the ends of pin  119  and rotate the pin about axis  101 ′ from the dotted line position shown in FIG. 14 to the full line position shown in that FIG. This occurs while surfaces  126  and  123 ′ are cooperating to prevent rotation of structure  113 . Accordingly, rotation of pin  119  causes shaft  118  to rotate about axis  101 ′ relative to structure  113 .  
         [0058]    At the level of the apparatus indicated by line  15 - 15  in FIG. 12 and accordingly shown in FIGS. 15 a  and  15   b , shaft  118  has a square cross section. Blocks  127  of resilient material surround shaft  118  and are clamped between shaft  118  and upper portions of rotatable structure  113  by clamp structure  120 . The relatively relaxed condition of blocks  127  is the condition shown in FIG. 15 a . When shaft  118  is rotated to the position shown in FIG. 15 b , blocks  127  are elastically deformed and exert torque on shaft  118  which resiliently urges the shaft to return to the position shown in FIG. 15 a . Once again, the condition shown in FIG. 15 b  corresponds to the solid line position of pin  119  in FIG. 14 and the position of pin  119  in FIG. 13 a . This is the condition in which locking block  123  in FIG. 14 has rotated pin  119  and therefore shaft  118  relative to structure  113 . This is also the condition (shown in FIG. 13 a ) in which slots  114  and  115  are relatively open and therefore able to receive or release wire lead L. When locking block  123  is retracted from contact with pin  119  (as shown in FIG. 14), blocks  127  are able to rotate shaft  118  (relative to structure  113 ) back to the condition shown in FIG. 15 a . This corresponds to the dotted line pin  119  position shown in FIG. 14 and the condition shown in FIG. 13 b . In this condition of the apparatus, blocks  127  resiliently urge shaft  118  to rotate relative to structure  113  to produce the clamping of lead L shown in FIG. 13 b . This clamping can be released by again reciprocating locking block  123  (FIG. 14) toward axis  101 ′ and thereby rotating pin  119  back to the full line position shown in FIG. 14 (corresponding to the condition shown in FIGS. 13 a  and  15   b ).  
         [0059]    In connection with FIG. 12 it should be noted that the lead-clamping region of the apparatus is preferably deep enough to clamp several wire leads L if desired. Four leads L are shown in FIG. 12 by way of illustration.  
         [0060]    [0060]FIG. 16 shows additional aspects of the operation of forming structure  1401 . When forming structure  140 ′ is in the “A” location relative to wire feeding guide  41 , slot  115  is aligned with wire emanating from guide  41 . Slot  115  is also open to receive wire. Accordingly, wire can be axially extended from guide  41  (e.g., by elements such as  46  in FIG. 7) to enter slot  115  as shown on the left in FIG. 16. Forming structure  1401  can then be operated (as described in the immediately preceding paragraphs) to clamp wire lead L in slot  115 . Support structure  42  (FIG. 4) can then be rotated relative to guide  41  to cause forming structure  140 ′ to begin to pull additional wire from guide  41  as shown in FIG. 16 by the movement of forming structure  140 ′ from the “A” position shown on the left to the “B” position shown on the right. Because slot  115  does not pass through rotational axis  101 ′, the use of forming structure  140 ′ to pull wire from guide  41  causes the resulting tension in the wire to exert a rotational torque (about axis  101 ′) on forming structure  140 ′. Because locking block  123  is in the retracted position shown in FIG. 14 after lead L has been inserted in slot  115  and clamped therein, this tension in the wire causes forming structure to rotate approximately 90° about axis  101 ′ as it moves from the “A” position in FIG. 16 to the “B” position in that FIG. Shaft  118  rotates with the remainder of structure  113  and therefore continues to clamp the wire after forming structure leaves the “A” position shown in FIG. 16.  
         [0061]    After the “B” condition shown in FIG. 16 is reached, support structure  42  (FIG. 4) continues to rotate relative to guide  41 , drawing additional wire from the guide and causing that wire to deposit in a coil on forming structure  140 ′ and the other forming structures  40  as described earlier in this specification (see also FIG. 17, which shows wire W that has been deposited around forming structure  140 ′). The shape of the outer surface of the lower portion of rotatable structure  140 ′ (on which the turns of wire forming this coil are partly deposited) is generally like the shape described earlier for surfaces  47 / 48  (FIG. 8), except that in forming structure  140 ′ this shape is “in the round” or a surface of revolution, concentric with axis  101 ′. Forming structure  140 ′ therefore operates on the coil in the manner generally described earlier, and it operates in this manner regardless of its rotational orientation about axis  101 ′.  
         [0062]    After the desired number of wire turns have been deposited on forming structures  40  and  140 ′, rotation of support structure  42  is stopped with forming structure  140 ′ again adjacent to wire guide  41 . Forming members  45  are then moved radially inward as shown in FIG. 18 to produce undulations in the coil of wire. Forming structures  40  and  140 ′ may also move radially inward to a lesser extent. The radially inward motion of forming members  45  pulls in on lead L, which is still gripped by forming structure  140 ′. This produces a torque on forming structure  140 ′, which causes it to again rotate about axis  101 ′ by approximately 90° to the position shown in FIG. 18. Finish lead F is then cut by cutter  50 . The coil is now ready to be stripped off forming members  40  and  140 ′. Accordingly, shaft  118  is rotated to release start lead L and the coil is stripped off the forming members and further processed to place it on a stator as described earlier in this specification. Elements  40 ,  45 , and  140 ′ are thereafter returned to their radially outer positions.  
         [0063]    It will be noted in FIG. 18 that slot  114  in forming structure  140 ′ is now opposite guide  41 . A new start lead can therefore be fed into slot  114  (e.g., by elements like elements  46  in FIG. 7). The rotation of shaft  118  can then be released in order to clamp this new start lead and the above-described coil winding process can begin again. Slots  114  and  115  are thus used alternately in successive coil winding operations.  
         [0064]    Because gripper  143  for start lead L is located near the top of the structure on which the turns of wire are formed and gradually moved down, the start and finish leads L and F in FIG. 18 are in approximately the same transverse plane of the finished coil. The apparatus shown in FIGS.  12 - 18  therefore produces coils having the same characteristics and advantages as are described above for the coils and apparatus shown in FIGS.  4 - 11 .  
         [0065]    In some applications of the invention it may be desirable to be able to produce some coils with start and finish leads in the same transverse plane (as described above), and to produce other coils with start and finish leads in respective start and finish planes that are spaced from one another at respective opposite axial ends of the finished coil. If that is desired, the apparatus of this invention can include a second forming structure generally like  40 ′ or  140 ′ but with the gripper for the start lead farther down and therefore able to hold the start lead in a plane different from the plane in which the finish lead will be disposed. When it is desired to produce a coil with co-planar start and finish leads, the coil is started using the forming structure  40 ′ or  140 ′ with the higher start lead gripper  43  or  143 . When it is desired to produce a coil with start and finish leads in axially spaced transverse planes, the coil is started using the forming structure  40 ′ or  140 ′ with the lower start lead gripper  43  or  143 . If forming structures of type  140 ′ are being used, the above-mentioned anti-rotation detent (or, alternatively, engagement of locking block  123 ) prevents rotation of the forming structure that is not currently being used to grip the start lead.  
         [0066]    As another example of possible modifications within the scope of this invention, instead of elements  41  and  42  being substantially fixed in the vertical direction during the operations relevant to the invention, elements  41  and  42  can be relatively movable in the vertical direction as shown in the sequence of FIGS. 19 a - d . In these FIGS. the entire wire-receiving and coil-forming structure is indicated generally by the reference number  42 . As shown in FIG. 19 a  wire source  41  is initially relatively high relative to structure  42  so that initial lead  11  (or L in embodiments like those shown beginning with FIG. 12) can be gripped by relatively high gripper  43 / 143 . As winding of the coil begins, wire source  41  moves down relative to structure  42  as shown in FIG. 19 b . Thereafter, as winding continues, wire source  41  gradually moves up again relative to structure  42  as shown progressively in FIGS. 19 c  and  19   d . Thus the turns of wire W are deposited on structure  42  from the bottom to the top of that structure. The final turn is deposited in approximately the same relatively high plane in which initial lead  11  (or L) is held by gripper  43 / 143  throughout the winding operation. Final lead  12  is severed from wire source  41  by cutter  50 . The coil undulation steps can be performed as described earlier in this specification and are not shown in the FIG. 19 series. Either or both of structures  41  and  42  can be moved to produce the relative vertical and rotational motions shown in FIGS. 19 a - d . This type of embodiment can be used to avoid the need for successive turns of wire to slide down the coil forming surfaces as the turns are formed.  
         [0067]    [0067]FIGS. 20 a - e  show another example of modifications within the scope of this invention. In this embodiment gripper  43 / 143  for initial lead  11  is movable vertically relative to wire-receiving and coil-forming structure  42 . Gripper  43 / 143  is initially relatively low relative to structure  42  and receives and holds the end of wire from wire source  41  as shown in FIG. 20 a . Wire source  41  is shown rotating around structure  42  and also gradually moving up relative to structure  42  as turns of wire are deposited on structure  42  (see FIGS. 20 b ,  20   c , and  20   d ). The final turn of wire is severed from source  41  by cutter  50  as shown in FIG. 20 d  to produce final lead  12  in a relatively high, final turn plane. Gripper  43 / 143  then moves up relative to structure  42  to place initial lead  11  in approximately the same plane as final lead  12 . The coil undulation steps can be performed as described earlier in this specification and are not shown in the FIG. 20 series. Any of elements  41 ,  42 , and  43 / 143  can be moved vertically to produce the relative vertical movements shown in FIGS. 20 a - e . Additionally, any of elements  41 ,  42 , and  43 / 143  can be rotated about central axis O to wind wire onto structure  42 .  
         [0068]    [0068]FIGS. 21 a - e  show a modification of the invention in which the final lead is placed in the same plane as the initial lead. Accordingly, gripper  43 / 143  for initial lead  11  is movable vertically relative to wire-receiving and coil-forming structure  42 . Gripper  43 / 143  is initially relatively high relative to structure  42  and receives and holds the end of wire from wire source  41  (FIG. 21 a ). Wire source  41  is rotated around structure  42  and also gradually moves down relative to structure  42  as turns of wire are deposited on structure  42  (FIGS. 21 b - d ). Wire source  41  then moves gradually up relative to structure  42  to place a final turn in approximately the same plane as initial lead  11  (FIG. 21 e ). The final turn of wire is then severed from source  41  by cutter  50  to produce final lead  12  in a relatively high, final turn plane. The coil undulation steps can then be performed as described earlier in this specification.  
         [0069]    Although embodiments in which initial lead  11  and final lead  12  are disposed in a relatively high position relative to structure  42  have been emphasized, it will be appreciated that it also may be desirable to have both initial lead  11  and final lead  12  disposed in a relatively low position with respect to structure  42 . In particular, initial lead  11  and final lead  12  can be disposed in the lowermost plane of the coil relative to structure  42 . This alternative results in a coil that, once installed in a stator in the position of external (outermost) coil  8  of FIG. 6, will have both initial leads disposed at the inner radius of the outer coil. Leads thus disposed, in an external coil, are more insulated from mechanical damage than leads disposed at the outer radius of the outermost coil.  
         [0070]    An external coil configured to have both initial and final leads disposed along the inner radius when the coil is installed in a stator can be formed using a winding structure having a gripper  43  at lower level L 2  as shown in FIG. 7. Accordingly, initial lead  11  is held at level L 2  while wire turns are accumulated on structure  42 . After the desired number of wire turns is deposited on structure  42 , wire guide  41  is moved vertically relative to structure  42  to bring the final turn (destined to terminate in final lead  12 ) into substantially the same plane as initial lead  11 .  
         [0071]    Additionally, external coils having both leads disposed at the inner radius can be formed using a winding structure having a forming structure, such as forming structure  140 ′, provided with a gripper  143  disposed in a lower position with respect to forming structure  140 ′ as discussed above. Accordingly, the wire is gripped in the lower position, wire turns are accumulated on structure  42 , and wire guide  41  and structure  42  are moved vertically relative to one another to allow a final lead  12  to be placed in substantially the same plane as initial lead  11 .  
         [0072]    Whether using forming member  40 ′ with gripper  43  or using forming member  140 ′ with gripper  143 , the relative vertical displacement of structure  42  with respect to guide  41  may be accomplished by movement of either of elements  42  and  41  or both may be moved in concert.  
         [0073]    Alternatively, an innermost coil having both initial and final leads disposed along the outer radius of the installed coil, such as coil  10  of FIG. 6, may be formed by placing both leads  11  and  12  in the lowermost plane of the coil relative to structure  42 . However, such a coil requires the use of an intermediate tool in addition to the insertion tool mentioned above if the coil is to be installed with the leads positioned in the radially outer position such as in coil  10  of FIG. 6  
         [0074]    The principles of the invention can be applied to forming undulated semi-phase coils like those described in European application No.  97110542 . 4  and in forming uninterrupted semi-phase coils like those described in U.S. Pat. No.  5 , 881 , 778 , both of which are hereby incorporated by reference herein in their entireties.  
         [0075]    One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for the purpose of illustration and not of limitation.