Abstract:
Apparatus and method for aligning wire conductors ( 11   a,    11   b ) extending from coil members ( 11 ) inserted in slots of a core ( 10 ) of an electric dynamo machine to join the ends ( 11′   a,    11′   b ) of the wire conductors by means of a welding operation accomplished by welding means ( 30 ), comprising : a first member ( 41 ) having a plurality of passages ( 40 ); a second member ( 42 ) having a plurality of passages ( 40 ′); the first and second members ( 41,42 ) being assembled adjacent to each other to align in pairs the passages ( 40 ) of the first member ( 41 ) with the passages ( 40 ′) of the second member ( 42 ); each pair of aligned passages ( 40,40 ′) forming a single passage capable of receiving at least the end portions ( 11   a,    11   b ) of two conductors; the first member ( 41 ) and the second member ( 42 ) being relatively moved in the circumferential direction (C) of the core to cause the sides of the passages ( 40,40 ′) to engage and move the end portions ( 11   a,    11   b ) of the wire conductors in the circumferential direction (C); a thrust in the radial direction (R) of the core being exerted on inclined portions (I) of the wire conductors to cause the end portions ( 11   a,    11   b ) of the wire conductors present in a single passage to engage each other in the radial direction (R) and the portion of wire conductor most distant in the radial direction in the single passage to engage the sides of the single passage in the radial direction (R).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to apparatuses and processes adapted to weld together the ends of a pair of conductors, wherein each conductor belongs to a coil member having a fork-like shape. Said members are inserted in slots of a core of an electric dynamo machine, and are normally referred to as “hairpins” in the art. 
         [0002]    The hairpin has two straight legs connected together by a bridge-like transversal part. As a whole, the hairpin somewhat looks like an upside-down “U”, with the bridge having a cusp-like shape. Each leg has a free end for inserting the hairpin into the slots of a core, such as a stator or an armature. 
         [0003]    The insertion is done by routing the free ends through the longitudinal entrances of the slots and by sliding them past the opposite side of the core, until the legs protrude outwards to a certain extent. Therefore, the hairpin bridges stay out on one side of the core, while the free ends stay out on the opposite side. 
         [0004]    After having been inserted, the free ends are bent to be positioned in predetermined positions, where connections to other free ends are made by welding. 
         [0005]    The present invention relates to apparatuses and processes for aligning the free ends along predetermined directions, so as to ensure that the free ends stay in predetermined positions prior to welding operations. 
         [0006]    The welding operation can be carried out by resistance heating or through a laser beam that hits the heads of two free ends placed in adjacent positions in order to be connected. The material of both heads is thus melted and forms a connection joint having specified mechanic and electric characteristics, which closes the winding circuit of the core in accordance with a predetermined electric scheme. 
         [0007]    A welding apparatus wherein the free ends are welded together by using an electric current for melting the material thereof is disclosed in European patent publication no. 1,043,828. 
         [0008]    For the latest core applications, e.g. stators of electric motors or generators, the apparatuses and processes for free-end alignment have been refined in order to ensure greater accuracy in the positioning of the free ends prior to welding. 
         [0009]    In addition, the devices involved in the alignment process must take less room and must apply a greater straightening force onto the conductors to align them, without damaging the conductors&#39; insulation. 
         [0010]    The increased hourly production of these core components has led to a reduction in the time available for performing the welding operation, so that there is less time for carrying out the alignment of the free ends. 
       OBJECT OF THE INVENTION 
       [0011]    It is therefore one object of the invention to align the free ends of the hairpins while minimizing the risk that the alignment with the welding tool is not accurate. 
         [0012]    It is another object of the invention to maintain the free ends in the proper position during and after the alignment step for performing the welding operation. 
         [0013]    It is a further object of the present invention to carry out the alignment quickly for a large number of free ends. 
         [0014]    It is yet another object of the present invention to prevent the conductors from being damaged by excessive alignment stresses. 
         [0015]    Said objects are achieved by the present invention through an apparatus and a method according to the appended independent claims  1  and  10  for aligning wire conductors extending from portions of coil members inserted in the slots of a core of an electric dynamo machine to join the ends of the wire conductors by means of a welding operation. 
         [0016]    Further preferred and advantageous features of the invention are set out in dependent claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    These and other objects and advantages of the invention will become apparent from the following detailed description, which is only provided by way of non-limiting example, with reference to the annexed drawings, wherein: 
           [0018]      FIG. 1  is an elevation view of a welding machine equipped with an alignment assembly according to the principles of the invention, 
           [0019]      FIG. 1   a  is a perspective view in the direction  1   a  of  FIG. 3   a , which shows two welded free ends, 
           [0020]      FIG. 1   b  is a perspective view similar to the view of  FIG. 1   a , which shows a hairpin before it is inserted into a core, 
           [0021]      FIG. 2  is a scale view enlarged along the direction of arrows  2 - 2  of  FIG. 1 , which shows an alignment assembly positioned with respect to the free ends of a core, 
           [0022]      FIG. 2   a  is a magnified view of the area indicated in  FIG. 2 , 
           [0023]      FIG. 3  is a view similar to the view of  FIG. 2 , which shows a step wherein the free ends have been aligned, 
           [0024]      FIG. 3   a  is a magnified view of the area indicated in  FIG. 3 , 
           [0025]      FIG. 4  is a partial perspective view along the direction  4  of  FIG. 1 , which shows the alignment assembly according to the principles of the invention, 
           [0026]      FIG. 5  is an elevation view from the directions  5 - 5  of  FIG. 6 , 
           [0027]      FIG. 6  is a view from the direction  6  of  FIG. 3   a.    
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    With reference to  FIGS. 1 ,  1   a ,  1   b , welding assembly  30  is equipped with a laser device  31 , whose laser beam  31 ′ is aligned with heads  11   a ′ and  11   b ′ of two end portions of the legs of hairpins. Said end portions of the legs will be referred to hereafter as free ends  11   a  and  11   b  (see  FIG. 1   a ). 
         [0029]      FIG. 1   b  shows a hairpin  11  before it is inserted into the core, the latter consisting of stator  10  of  FIG. 1 . The hairpin has two free ends  11   a  and  11   b  belonging to respective legs joined together by bridge  11   c.    
         [0030]      FIG. 1   a  shows two free ends  11   a  and  11   b  of two different hairpins after they have been inserted into the stator and bent in order to make weld  12 , consisting of melted material. 
         [0031]    In fact,  FIG. 1   a  shows that, because of the bending, a portion of legs I is inclined as needed to reach the position where free ends  11   a ,  11   b  are arranged in order to align heads  11 ′ a  and  11 ′ b  thereof for welding. 
         [0032]    In  FIG. 1 , all the free ends of stator  10  are hidden by the external part of alignment assembly  20 , whereas the interlacement of hairpin bridges  11   c  is visible at the bottom of stator  10 . 
         [0033]    Under alignment assembly  20 , close to the top side of stator  10 , one can see the interlacement of inclined portions I of the legs. 
         [0034]    For welding, stator  10  is placed into seat  10 ′ (shown as a cross-section) of frame table  25  to be aligned with alignment assembly  20  and welding assembly  30 . 
         [0035]    Welding assembly  30  is carried by drive assembly  50 , which moves welding assembly  30  in both directions of X axis (perpendicular to the plane of the sheet that contains  FIG. 1 ), in both directions of Y axis, and in both directions of Z axis. 
         [0036]    In order to accomplish the movements in X,Y,Z axes, drive assembly  50  is fitted with a slide  51 , which carries welding assembly  30 . Slide  51  is moved in both directions of Y axis by motor  52 . Slide  51  slides on a crosspiece  51 ′, which can move along guides  53 ′ and  53 ″ in both directions of X axis. The crosspiece is moved in both directions of X axis by motor  54 . 
         [0037]    Guides  53 ′ and  53 ″ are supported by slides  55 ′ and  55 ″, which can move along guides  56 ′ and  56 ″ in both directions of Z axis. Slides  55 ′ and  55 ″ are moved in both directions of Z axis by motor  57 . 
         [0038]    By sending suitable commands to motors  52 , 54 , 57  of drive assembly  50 , it is possible to align and position laser beam  31 ′ with heads  11 ′ a  and  11 ′ b  in order to make welds  12 . The man skilled in the art may of course adopt welding means other than laser ones without departing from the application scope of the principles of the present invention. 
         [0039]    Alignment assembly  20  has two support arms  20 ′ and  20 ″ connected to the heads of shafts  21  and  22 , respectively. Shafts  21  and  22  can move in both directions of Z axis on guides  23  and  24  of frame table  25 . Shafts  21  and  22  are connected to each other by crosspiece  26  (drawn with a dashed line in  FIG. 1 ). The stem of cylinder  27  is connected to crosspiece  26  to move shafts  21  and  22  in both directions of Z axis, and thus move alignment assembly  20  in both directions of Z axis as well. 
         [0040]    The position of alignment assembly  20  along Z axis near the end of stator  10 , as shown in  FIG. 1 , causes the alignment assembly to receive the free ends within alignment passages  40 , as shown in  FIGS. 2-6 . 
         [0041]    More specifically, with reference to  FIGS. 2-6 , there are a series of alignment windows  40  on a ring  41  and a second series of windows  40 ′ on a second ring  42 , which is assembled adjacent to ring  41 . Ring  42  is hidden by ring  41  in  FIGS. 2 and 3 ; ring  42  is visible in  FIGS. 3   a ,  4 ,  5  and  6 . 
         [0042]    Alignment windows  40  and  40 ″ of the two rings  41 , 42  have the same configuration. In  FIG. 2 , alignment windows  40  and  40 ′ are perfectly aligned in pairs, thus forming through passages that can receive free ends like free ends  11   a ,  11   b ,  11   c ,  11   d , shown in the magnified detail of  FIG. 2   a . Reception occurs when the alignment assembly is brought near the stator, and when the latter is angularly aligned in seat  10 ′ to allow free ends such as  11   a ,  11   b ,  11   c ,  11   d  to get into the matching pairs of windows  40  and  40 ′, as shown in  FIGS. 1 and 2 . 
         [0043]    The number of alignment windows  40  of a series of a ring may equal the number of slots in the stator, as shown in the example of  FIGS. 2 and 3 . 
         [0044]    In the drawings, four legs of hairpins  11  are present in one slot of the stator; hence four free ends  11   a ,  11   b ,  11   c  and  11   d  are received in each passage formed by alignment windows  40  and  40 ′ when they are aligned (i.e. matched in pairs) and when alignment assembly  20  has approached the core, as shown in  FIGS. 1 and 2 . Alignment assembly  20  is made to approach the core by actuating cylinder  27  and then moving crosspiece  26  in order to move shafts  21  and  22  along Z axis towards table  25 . 
         [0045]    It is apparent from  FIG. 2   a  that free ends  11   a ,  11   b ,  11   c  and  11   d , when received in a single passage, have heads, such as  11 ′ a ,  11 ′ b ,  11 ′ c ,  11 ′ d , which are not aligned with respect to the working direction of a welding tool, such as beam  31 ′ of laser device  31 . 
         [0046]    As shown in  FIGS. 2 and 3 , rings  41  and  42  have respective control arms  41 ′ and  42 ′; at the end of each arm an idle roller  43  is mounted. Roller  43  of arm  41 ′ is housed in the seat of actuator member  44 , whereas roller  43  of arm  42 ′ is housed in the seat of actuator member  45 . Members  44  and  45  are moved towards each other in direction F and away from each other in directions G by actuator assembly  46 . 
         [0047]    With reference to  FIGS. 2 and 3 , when movement occurs in directions F, ring  41  rotates clockwise in circumferential direction C about central axis A, and ring  42  moves about A axis to the same angular extent in the opposite circumferential direction C. 
         [0048]    The rotations in directions C bring about the alignment condition shown in  FIGS. 3 and 3   a . 
         [0049]    More in particular, with reference to  FIG. 3   a , one may consider that one window  40  of ring  41  is made up of opposite faces W 1  and W 1 ′ facing in circumferential directions C of the stator and of opposite faces W 2  and W 2 ′ facing in radial directions R of the stator. 
         [0050]    Likewise, a window  40 ′ of ring  42  may be made up of opposite faces W 3  and W 3 ′ facing in circumferential directions C and of opposite faces W 4  and W 4 ′ facing in radial directions R. 
         [0051]    It follows that the rotations in directions C move first ring  41  relative to second ring  42  in circumferential directions C to reduce distance D ( FIG. 2   a ) that separates opposite faces W 1  and W 3 ′, respectively belonging to rings  40  and  40 ′, facing in circumferential directions C (see condition shown in  FIG. 3   a ). The opposite faces like W 1  and W 3 ′ engage and move the wire conductors of free ends  11   a ,  11   b ,  11   c  and  11   d  in circumferential directions C in order to reach the condition of alignment of free ends  11   a ,  11   b ,  11   c  and  11   d  in radial directions R, as shown in  FIG. 3   a.    
         [0052]    The condition in which the opposite faces like W 1  and W 3 ′ are close, i.e. separated by a distance D* in  FIG. 3 , is such that a certain margin of play is left between faces W 1  and W 2  and free ends  11   a ,  11   b ,  11   c  and  11   d . This play allows the conductors forming the free ends to move in radial direction R, as will be described below. It follows that the conductor portions forming free ends  11   a ,  11   b ,  11   c ,  11   d  are not clamped by faces W 1  and W 3 ′, so that at this stage they are not retained in the radial direction R. 
         [0053]    With particular reference to  FIGS. 3   a ,  4 ,  5 ,  6 , pusher assembly  60  can be aligned inside the stator in a manner such that push blades  61  are aligned with inclined portions I of the legs (see  FIG. 4 ). In this alignment situation, a movement of blades  61  in radial directions R, outwards from the stator, causes radial blades  61  to contact and push in the same direction inclined portions I. 
         [0054]    As a result, free ends  11   a ,  11   b ,  11   c  and  11   d  located in a narrow passage at a distance D*, like the one shown in  FIGS. 3   a ,  4 ,  5  and  6 , are pushed one against the other, outermost one  11   d  being pushed in contact with the surface of faces W 2  and W 4 ′ (see  FIGS. 5 and 6 ) of two windows  40  and  40 ′, which have been relatively rotated in circumferential directions C. 
         [0055]    The free ends, like  11   a ,  11   b ,  11   c  and lid, are thus aligned and retained in predetermined positions and directions with respect to the central A axis, as needed to ensure an accurate positioning prior to welding. 
         [0056]    The rotations in directions C, which relatively move first ring  41  with respect to second ring  42  in order to reduce distance C to distance D*, can simultaneously align free ends  11   a ,  11   b ,  11   c  and  11   d  present in all of the passages of rings  41  and  42 . In fact, all opposite faces like W 1  and W 3 ′ of various windows  40  and  40 ′ will engage and move the various free ends in circumferential directions C, resulting in a condition wherein a plurality of free ends  11   a ,  11   b ,  11   c  and  11   d  are aligned along circumferential directions C of the stator (see  FIGS. 3 and 4 ). 
         [0057]    As soon as this condition is achieved, the multiplicity of blades  61  will push inclined portions I aligned in radial directions R, resulting in free ends  11   a ,  11   b ,  11   c  and  11   d  in the various narrow passages being pushed one against the other, outermost free ends  11   d  being pushed in contact with surfaces W 2  and W 4 ′ of the various windows ( FIGS. 4-6 ). 
         [0058]    In  FIG. 4  cover  62  of the pusher assembly  60 , visible in  FIG. 3 , has been removed in order to provide a clearer view of blades  61  and their arrangement about A axis. Blades  61  can be moved in radial directions R by means of an inclined-slot solution like the one described in European patent 1,304,789, used for moving pushers in the radial directions of a stator for the purpose of forming the coil heads. 
         [0059]      FIGS. 5 and 6  illustrate how ends  11   a ,  11   b ,  11   c ,  11   d  are clamped by applying radial force near heads  11 ′ a , 11 ′ b ,  11 ′ c ,  11 ′ d . This ensures that, in order to obtain the same alignment bending, less force needs to be applied onto the conductors. Furthermore, the conductors are clamped near the welding region, thus ensuring a more stable and accurate positioning with respect to the welding tool. 
         [0060]    The fact that the windows allow some play on the conductors when they are closed at distance D* ensures that no uncontrolled force is applied along the insulation of the conductors forming free ends  11   a ,  11   b ,  11   c ,  11   d.    
         [0061]    With just one relative rotation of rings  41  and  42  it is possible to quickly align the plurality of free ends  11   a ,  11   b ,  11   c ,  11   d  in circumferential directions C. 
         [0062]    Likewise, a single movement of the actuator of radial blades  61  will cause the plurality of blades  61  to move simultaneously to rapidly obtain the alignment of the plurality of free ends  11   a ,  11   b ,  11   c ,  11   d  in radial directions R. 
         [0063]    The fact that the windows are made to receive free ends  11   a ,  11   b ,  11   c ,  11   d  through a movement of assembly  20  in direction Z towards the table, thus sliding for a short distance along the conductors, is useful to reduce the time required for aligning free ends  11   a ,  11   b ,  11   c ,  11   d  and to avoid damage to the conductors. 
         [0064]    The above description of one specific embodiment has illustrated the invention from a conceptual viewpoint, so that others, by using prior-art techniques, will be able to modify and/or adapt said specific embodiment to various applications without further research and without departing from the inventive concept. It is therefore understood that any such modifications and adaptations will be considered to be equivalent to the exemplary embodiment described herein. The means and materials necessary for implementing the various functions described herein may vary without departing from the scope of the invention. It is understood that the expressions and terminology used herein are merely descriptive and hence non-limiting.