Abstract:
When electric wires (joint conductors) are disposed adjacent each other in a peeled state of coatings, a gap corresponding to the total thickness of both conductors&#39; insulating films as skin layers is formed between end joined face portions of the conductors. The gap becomes larger because the conductors are tapered. Therefore, the adhesion between both conductors is impaired, with a consequent fear of occurrence of joining imperfection. In opposed joined face portions of electric wires (joint conductors), the conductors are deformed from the tips of their axes to the joined face side in such a manner that exposed portions at the tips of the conductors and insulating film faces located in the vicinity thereof are flush with each other or the exposed portions are projected. The gap formed between the electric wires (joint conductors) can be diminished, whereby the reliability of connection is improved and it becomes easier to perform the work of joint conductors, with the result that the productivity of a stator of a rotary electric machine such as an AC generator for a vehicle could be improved.

Description:
CLAIM OF PRIORITY 
     The present application claim priority from Japanese application serial No. 2005-150316, filed on May 24, 2005, the content of which is hereby incorporated by reference into this application. 
     FIELD OF THE INVENTION 
     The present invention relates to a stator of a rotary electric machine such as, for example, an AC generator for a vehicle and a method for manufacturing the same, as well as a joint structure of electric wires and a method for manufacturing the same. 
     BACKGROUND OF THE INVENTION 
     According to a known electric wire, an end portion of an electric wire (a joint conductor) which end portion extends over a predetermined range from a tip of the wire is plastically deformed so that a sectional area thereof becomes smaller than that of a main portion of the conductor, and the wire is constructed so that the main portion and a part of the end portion near the main portion are coated uniformly with an insulating film, then two such electric wires (joint conductors) are joined together in a matched state of respective end portions. 
     [Patent Literature 1] 
     Japanese Patent Laid-Open Publication No. 2002-95198 
     In the above conventional technique, since the sectional area of the end portion is decreased while preventing damage of the insulating film, a heat input quantity can be decreased. Consequently, there is no fear that an insulating material located near a joined portion may be deteriorated with heat produced a joining work, and hence the insulating performance is not impaired. 
     In the above conventional technique, however, if two electric wires (joint conductors) are positioned adjacent each other in a peeled state of respective insulating coatings, there is formed a gap with corresponding to the total thickness of both conductor&#39;s insulating coatings as skin layers in a joined face portion between end portions of the conductors. The gap becomes larger because the conductors are tapered at their tips. Therefore, the adhesion between both conductors is impaired, with a consequent fear of occurrence of joining imperfection. 
     It is an object of the present invention to minimize the gap developed between electric wires (joint conductors), thereby improving the reliability of joining, and facilitate the conductor joining work, thereby improving the productivity of a state of a rotary electric machine such as, for example, an AC generator for a vehicle. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electric wire joint structure comprising: 
     insulator-coated wires each having a portion where an insulator coating is removed to expose the conductor, wherein exposed portions of the conductors are opposed to each other to form joining faces; the joining faces of the exposed portions being flush with the surfaces of the insulator coatings of the insulator-coated wires or being projected from the surfaces of the insulator coatings of the insulator-coated wires, and the joining faces being metallurgically joined. 
     According to one aspect of the present invention, for achieving the above-mentioned object, in opposed joined face portions of electric wires (joint conductors), the axes of the conductors&#39; exposed portions are offset relative to the axes of the insulating coating in such a manner that exposed tip portions of the conductors and insulating coating faces located in the vicinity thereof are flush with each other or the conductors&#39; exposed portions are projected. 
     According to another aspect of the present invention constructed as above, since joined faces of the joined face portions at the tips of the conductors with insulating coatings removed confront each other, it is not necessary to keep the two pushed against each other with a strong force during the joining work. Besides, it is possible to diminish the likelihood of peeling-off of the joined face portion caused by spring-back after joining. As a result, not only the rationalization of the joining work can be attained, but also the reliability of the joined state of the joined face portion is improved and so are the productivity and reliability of, for example, the stator of a rotary electric machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an enlarged perspective view showing a connection between electric wires (joint conductors) to which the present invention is applied; 
         FIG. 2  is a diagram illustrating a process of cutting joined face portions into a shape easy to weld; 
         FIG. 3  is a diagram showing a welded state of the joined face portions; 
         FIG. 4  is a diagram for explaining in what state the joined face portions are Tig-welded; 
         FIG. 5  is a diagram showing a process of chipping off enamel coatings on short sides; 
         FIG. 6  is a diagram showing a process of chipping off enamel coatings on long sides; 
         FIG. 7  is an enlarged diagram of a circular frame portion in  FIG. 5 ; 
         FIG. 8  is an enlarged diagram of a circular frame portion in  FIG. 6 ; 
         FIG. 9  is an appearance diagram of a chip-off device; 
         FIGS. 10A to 10D  are diagrams for explaining a process of chipping off enamel coatings on shorts sides; 
         FIG. 11  is a perspective view showing insulated conductors after chipping-off of the short-side enamel coatings; 
         FIGS. 12A to 12F  are diagrams for explaining a process of chipping off enamel coatings on long sides; 
         FIG. 13  is a perspective view showing the insulated conductors after chipping-off of the short- and long-side enamel coatings; 
         FIG. 14  is a diagram showing a state in which the insulated conductors after chipping-off of the short- and long-side enamel coatings have been set to a cutting device; 
         FIG. 15  is a diagram for explaining another machining method; 
         FIG. 16  is a diagram showing base metals of coil conductors used in a stator of a rotary electric machine; 
         FIG. 17  is a diagram showing bent coil conductors; 
         FIG. 18  is a diagram showing an inner coil and an outer coil each formed in the hexagonal shape; 
         FIG. 19  is a diagram showing a part of a stator of a rotary electric machine according to the present invention; 
         FIG. 20  is a diagram for explaining a process to be carried out prior to a stator assembling process; 
         FIG. 21  is a diagram for explaining another process to be carried out prior to the stator assembling process; 
         FIG. 22  is a diagram for explaining a state in which a stator core has been set to a stator assembling fixture; 
         FIG. 23  is a diagram for explaining in which state inner coils are set to the stator core; 
         FIG. 24  is a diagram for explaining in which state outer coils are set to the stator core; 
         FIG. 25  is a diagram showing the stator core with inner and outer coils set thereto; 
         FIG. 26  is a diagram for explaining a process of twisting the outer coils; 
         FIG. 27  is a diagram for explaining a process of deforming and caulking the outer coils into a state necessary for joining; 
         FIG. 28  is a diagram for explaining a process of welding joined face portions of the outer coils; 
         FIG. 29  is a diagram for explaining a process of twisting the inner coils; 
         FIG. 30  is a diagram for explaining a process of deforming and caulking the inner coils into a state necessary for joining; and 
         FIG. 31  is a diagram for explaining a process of welding joined face portions of the inner coils. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described hereinunder with reference to the drawings. 
       FIG. 1  is an enlarged perspective view showing a connection between electric wires (joint conductors) to which the present invention is applied. 
     Electric wires (joint conductors)  1  and  2  respectively comprise conductors  1 A and  2 A of a rectangular section coated and insulated with enamel coatings  1 B and  2 B. 
     The enamel coatings  1 B and  2 B are chipped off at tips of the electric wires (joint conductors)  1  and  2  to form, at the tips, projecting portions  1 C and  2 C which are the smallest in sectional area. The small projecting portions  1 C and  2 C function as cutting portions when cutting a single long conductor (a detailed description will be given later) to form a conductor piece of a required length. Sectional area portions of a medium size, which function as welding portions  1 D and  2 D, are formed between the small projecting portions  1 C,  2 C and the enamel coatings  1 B,  2 B. One sides between the small projecting portions  1 C,  2 C and the welding portions  1 D,  2 D are connected together through first slant faces  1 E and  2 E having outward inclinations toward the enamel coatings  1 B and  2 B. 
     The welding face portions  1 D,  2 D and the enamel coatings  1 B,  2 B (portions of the largest sectional area) are connected together through stepped portions  1 F and  2 F. 
     Further, second slant faces  1 G and  2 G having outward inclinations toward the enamel coatings  1 B and  2 B are formed between the stepped portions  1 F,  2 F and the enamel coatings  1 B,  2 B. 
     The sides of the electric wires (joint conductors)  1  and  2  opposite to the side including the first slant faces  1 E,  2 E, and the stepped portions  1 F,  2 F are formed flat from the enamel coatings  1 B and  2 B up to tips of the small projecting portions  1 C and  2 C. 
     At the flat face portions, indicated at  1 H and  2 H, the tip portions of the joint conductors  1  and  2  are in close contact with each other. 
     This construction is characteristic in that there is no gap between joined faces formed by the flat face portions- 1 H and  2 H. As a result, the heat dissipating area of the joined face portions diminishes by about 25% and it becomes possible to effect joining to a satisfactory extent with a relatively small quantity of heat during welding. Coupled with a reduced quantity of heat because of a small sectional area of the tip portions of the conductors, it becomes possible to conduct heating more effectively. 
     The remaining two faces at the tips of the electric wires (joint conductors)  1  and  2  are formed as flat faces  1 J,  2 J and flat faces (not shown) on the back sides. 
     Also on the flat faces  1 J and  2 J the enamel coatings  1 B and  2 B are chipped off to form third slant faces  1   k  and  2 K which are inclined outwards toward the enamel coatings  1 B and  2 B. This is also true of the back faces. 
     The first slant faces  1 E,  2 E, the second slant faces  1 G,  2 G, the third slant faces  1 K,  2 K, the flat faces  1 J,  2 J and their back faces are formed with edges of a cutter (to be described later) which chips off the coatings  1 B and  2 B of the conductors. 
       FIG. 2  is a diagram explanatory of a process of cutting the joined face portions into a shape which facilitates welding. 
     Before welding, the tip portions of the electric wires (joint conductors)  1  and  2  are cut by operating cutting edges  20 A and  20 B of a cutter  20  in the directions of arrows in  FIG. 2  at intermediate positions (shown in  FIG. 2 ) of the welding face portions  1 D and  2 D as portions of a medium sectional area. 
       FIG. 3  shows a welded state of both conductors by Tig welding (Tungsten Inert Gas welding) on the cut faces. 
       FIG. 4  illustrates in what manner the joined face portions are Tig-welded. 
     By welding the cut faces, indicated at  1 L and  2 L, by Tig welding (Tungsten Inert Gas welding), the joined faces of the electric wires (joint conductors)  1 A and  2 A are joined together by molten metal  30 . 
     More specifically, a heat-resistant tungsten electrode  42  is held in a collet  41  of a torch  40  and an inert gas (argon or helium gas)  44  is introduced through a gas introducing pipe  43  around the tungsten electrode  42  and is ejected through a gas nozzle  47  to around a welding portion. A jet  48  of the inert gas cuts off the welding portion from air, creating an oxygen-free state. As a result, the material is difficult to be oxidized because there is no oxygen (air) in the welding portion. Since the electric wires (joint conductors)  1 A and  2 A are copper wires, they are used as positive electrodes, while an electrode  41 A of the collet  41  is used as a negative electrode, and a DC voltage is applied, causing an arc  40 B to be produced between the tungsten electrode  42  and the joined faces  1 L,  2 L of the electric wires (joint conductors)  1 A,  2 A. In this welding, the temperature of the arc  40 B reaches a temperature of 5000 to 30000 degrees. With the heat of the arc  40 B, the joined face portion between the joined faces  1 L and  2 L is melted and welded. 
     The smaller the heat dissipating area and the smaller the amount of heat dissipated, the earlier the temperature of the welding portion can be raised up to the metal melting temperature. 
     Besides, since there is no gap between the joined faces, there is no sump of air (oxygen), and even if a negative pressure portion occurs in the welding portion by the flow of inert gas which is blown off against the welding portion, there is no fear of air (oxygen) being introduced (flowing reverse) into the joined face portion and the welding portion is so much difficult to be oxidized, because in the welding portion there is not such a gap as serves as an air introducing passage. 
     Since the joined faces are in close contact with each other, it is not necessary push the joined faces with a strong force from the exterior during welding. The problem that the joined portion springs back (a phenomenon that the joined portion repulses the pushing force and tends to revert to the original separated state) after welding, causing separation of the welded portion, is also solved. Further, it is not necessary to retain the pushing force until the joined portion gets cold for the prevention of separation caused by such a spring-back phenomenon, and the time required for the joining can so much be shortened. 
     When the electric wires (joint conductors) are joined in a stand-up state, the stepped portions  1 F and  2 F act as receiving portions of molten metal spatter, whereby the possibility of the spatter adhering to for example of the face of the insulating film and impairing the insulating property can also be diminished. 
     Now, with reference to  FIGS. 5 and 6 , a description will be given below about a method and apparatus for manufacturing the electric wires (joint conductors)  1  and  2  described above. 
     As also described earlier, the electric wires (joint conductors)  1  and  2  according to this embodiment are rectangular conductors whose section perpendicular to the longitudinal axis of each conductor is a rectangular section comprising long and short sides. The outer peripheries of the electric wires are coated for insulation with enamel coatings  1 A and  2 A. 
     In case of welding an end portion of a conductor to another conductor, the enamel coating thereof becomes an obstacle. Therefore, it is necessary to remove the enamel coating on the end portion of each conductor which portion serves as a conductor joined face portion to facilitate welding. Besides, the machining method should be a method suitable for automation so that the enamel coating removing work and a cutting work for cutting the conductor into a specific length suitable for the purpose of use. 
       FIGS. 5 to 12  are drawings for explaining the enamel coating removing work, of which  FIG. 5  illustrates a process of chipping off the enamel coatings on short sides,  FIG. 6  illustrates a process of chipping off the enamel coatings on long sides,  FIG. 7  is an enlarged diagram of a circular frame portion in  FIG. 5 ,  FIG. 8  is an enlarged diagram of a circular frame portion in  FIG. 6 , and  FIG. 9  is an appearance diagram of a chip-off device. 
     Chip-off devices  50  and  60  comprise fixed dies  51 ,  61  and movable dies  52 ,  62 . 
     The fixed dies  51  and  61  comprise a pair of fixed clamping fixtures  51 A,  51 B and a pair of fixed clamping fixtures  61 A,  61 B, respectively, and centrally provided, combined conductor guides and fixed blades  51 C and  61 C, respectively. 
     The movable dies  52  and  62  comprise a pair of movable cutting blades  52 A,  52 B and a pair of movable cutting blades  62 A,  62 B, respectively, and centrally provided, conductor pressers  52 C and  62 C, respectively. 
     The combined conductor guides and fixed cutting blades  51 C,  61 C and the movables cutting blades  52 A,  52 B,  62 A,  62 B have respective edges  51   a ,  51   b ,  61   a ,  61   b ,  52   a ,  52   b ,  62   a , and  62   b.    
     The chip-off devices  50  and  60  are installed side by side before and after a machining line. An enamel coating  100 A on each short side is first excised and this excised portion is fed to the position of the chip-off device  60 , where the enamel coating  100 A on each long side is chipped off. In this way enamel coating  100 A-chipped off portions are formed continuously at certain intervals on the long conductor. 
     As shown in  FIG. 9 , at an inlet and an outlet of the chip-off device  50  there are provided conductor feed guides  101  and  102 , respectively, for feeding straight an insulated conductor. An insulated conductor  100  which has been fed over a certain length by means of a feeder (not shown) is guided into a groove  51 F in such a manner that long sides of the conductor  100  come into abutment against the slot, the groove  51 F ( FIG. 7 ) being formed in an end face of the combined conductor guide and fixed cutting blade SiC in the chip-off device  50 . 
     As shown in  FIGS. 5 ,  7  and  10 , the insulated conductor  100  is pressed down in the direction of the combined conductor guide and fixed cutting blade  51 C by means of the conductor presser  52 C which is disposed at a position confronting the combined conductor guide and fixed cutting blade  51 C, whereby the position of the insulated conductor  100  is fixed (see  FIGS. 10A and 10C ). 
     Next, the movable blades  52 A and  52 B move from above to below in the drawings, with the result that a shear force is developed between the edges  52   a ,  52   b  of the movable cutting blades  52 A,  52 B and the edges  51   a ,  51   b  of the combined conductor guide and fixed cutting blade  51 C. The drawings illustrate a state in which the coating is being chipped off with the shear force. The chipped-off coating and a part of the conductor (chips resulting from cutting) are held in gaps  51 D and  51 E formed between the fixed clamping fixtures  51 A,  51 B and the combined conductor guide and fixed cutting blade  51 C (see  FIGS. 10B and 10D ). 
     When the chipping-off of the enamel coating  100 A on short sides is over, the insulated conductor  100  is fed to the position of the next chip-off device  60  by means of a feeder (not shown). 
       FIG. 11  shows an appearance of the insulated conductor upon completion of chipping-off of the short-side enamel coating  100 A. The same constituent portions as in  FIG. 1  are identified by the same reference numerals as in  FIG. 11 . 
     The chip-off device  60  is disposed at a position corresponding to a 90°-rotated position of the chip-off device  50 . The movable cutting blades  62 A and  62 B of the chip-off device  60  are disposed on the same machining line so as to reciprocate perpendicularly to the movable cutting blades  52 A and  52 B of the chip-off device  50 . 
     Like the device shown in  FIG. 9 , the chip-off device  60  is also provided with conductor feed guides  101  and  102  at an inlet and an outlet, respectively, for feeding the insulated conductor straight. The enamel coating  100 A-chipped off portion on a short side of the insulated conductor  100  which has been fed a certain length by the feeder (not shown) is set to the position of a groove  61 F which is formed in an end face of the combined conductor guide and fixed cutting blade  61 C of the chip-off device  60 . In this state a gap is still present between the face of the chipped-off portion and the face of the groove  61 F (see  FIGS. 12A and 12D ). 
       FIGS. 6 and 8  show an interim state. Before reaching the state shown in  FIGS. 6 and 8 , first the movable blades  62 A and  62 B move from right to left in the figures, with the result that the edges  62   a  and  62   b  of the movable cutting blades  62 A and  62 B come into abutment against the to-be-chipped off portion of the insulated conductor  100 . As shown in  FIGS. 12B and 12E , the edges  62   a  and  62   b  of the movable cutting blades  62 A and  62 B are formed axially longer than the edges  52   a  and  52   b  of the movable cutting blades  52 A and  52 B, so that the insulated conductor can be chipped off over a longer axial portion than the portion which has been cut with the edges  52   a  and  52   b  of the movable cutting blades  52 A and  52 B in the previous process. Consequently, it is possible to solve the problem that the conductor is torn off in the portion of a small sectional area previously chipped off when the edges  62   a  and  62   b  of the movable cutting blades  62 A and  62 B come into abutment against only the said potion of a small sectional area. 
     Further, as the edges  62   a  and  62   b  of the movable cutting blades  62 A and  62   b  move toward the combined conductor guide and fixed cutting blade  61 C, the long-side portions with the sectional area not reduced yet begin to be chipped off by the edges  62   a  and  62   b . At this time, the pressing force of the movable cutting blades  62 A and  62 B is borne by abutment of an outer face of the axially outer portion of a larger sectional area with respect to the portion chipped off previously by the edges  52   a  and  52   b  of the movable cutting blades  52 A and  52 B against the fixed clamping fixtures  61 A and  61 B (see  FIGS. 12B and 12E ). 
     Then, as the edges  62   a  and  62   b  move toward the combined conductor guide and fixed cutting blade  61 C, the edges  62   a  and  62   b  reach the face of the portion of a smaller sectional area which was chipped off with the edges  52   a  and  52   b  of the movable cutting blades  52 A and  52 B in the previous process. At this time, the portion chipped off in the previous process and reduced in sectional area undergoes the pressing force of the conductor presser  62 C and that of the movable cutting blades  62 A,  62 B and is deformed leftwards in the drawings. This deformation continues until the groove  61 F-side face of the portion reduced in sectional area is pressed against the bottom face of the groove  61 F (see  FIGS. 12C and 12F ). 
     After abutment of the groove  61 F-side face of the portion reduced in sectional area against the bottom face of the groove  61 F, the conductor is excised with a shear force developed between the edges  62   a ,  62   b  of the movable cutting blades  62 A,  62 B and the edges  61   a ,  61   b  of the combined conductor guide and fixed cutting blade  61 C. 
       FIGS. 6 and 8  show an interim state, in which the chipped-off coating  100 A and a part of the conductor (chips resulting from cutting) are held in gaps  61 D and  61 E formed between the fixed clamping fixtures  61 A,  61 B and the combined conductor guide and fixed cutting blade  61 C. 
     In  FIG. 9 , the fixed and movable dies  51 ,  52  and cutting blades are positioned by positioning pins  56 A and  56 B. 
       FIG. 13  shows the insulated conductor  100  after chipping-off of the short- and long-side enamel coatings. The reference numerals described in  FIG. 13  are the same as those used for the electric wires (joint conductors)  1  and  2  in  FIG. 1 , indicating the same portions as in  FIG. 1 . 
     After the enamel coatings have been chipped off by the excising devices  50  and  60 , the pair of electric wires (joint conductors)  1  and  2  assume a state in which both are connected together through the projecting portion  1 C. 
     The portion of the smallest sectional area is formed by central edge portions of the edges  52   a  and  52   b  of the movable cutting blades  52 A and  52 B when the short-side coating is chipped off. In  FIG. 13 , the size of a short side is L 1  and that of a long side is L 2 , both being in the relation of L 1 &lt;L 2 . 
     A cutting device is disposed at a position just behind the chip-off device  60  on the machining line. When the chipping-off is completed by the chip-off device  60 , the electric wires are fed up to the position of the cutting device. 
       FIG. 14  is a sectional view taken along line P-P in  FIG. 13 , showing a state in which the insulated conductors are set to the cutting device. 
     As shown in  FIG. 14 , the cutting device includes a cutting blade  110  and cut assisting fixtures  111  disposed on both sides of the cutting blade  110 . The cut assisting fixtures  111  function not only as guides for the cutting blade  110  but also as holding fixtures for holding the conductors firmly. In a state in which the conductors are pressed against a receiving die  112  by the cut assisting clamping fixtures  111 , the cutting blade  110  is moved toward the receiving die  112 , whereby the portion of the smallest section is cut to form a projecting portion  1 C. 
     At this time, the faces of the electric wires (joint conductors)  1  and  2  which faces are in contact with the receiving die  112  form joined faces  1 H and  2 H after the cutting. As shown clearly in  FIG. 14 , the joined faces  1 H and  2 H are deformed (offset to one side from the center) so as to be flush (coplanar) with the faces of the enamel coatings  1 B and  2 B. 
     Although in the above embodiment the enamel coating-chipped off portions are thus deformed (offset to one side from the center) simultaneously with the chipping-off of the long-side enamel coating, there may be adopted a method wherein the portions in question are not deformed (offset to one side from the center), but are pressed and deformed longitudinally as indicated with broken lines by pressing fixtures  113  and  114  in the cutting process, as shown in  FIG. 15 , followed by cutting of the portion of the smallest section with use of the cutting blade  110 . 
       FIG. 16  illustrates coil conductors in a stator of a rotary electric machine which is provided with the electric wires (joint conductors) shown in  FIGS. 1 ,  13  and  14 . 
     The coil conductors, which constitute a stator in the rotary electric machine, are an inner coil  131  inserted inside a slot of the stator, an outer coil  133  inserted outside the slot, and a crossover coil  132  which provides a connection between the inner and outer coils. 
     Enamel coating-chipped off portions  131 A,  131 B,  132 A,  132 B,  133 A, and  133 B of the shape described above are formed at both ends of the coil conductors by the above process. 
     Each coil conductor is bent nearly centrally, as shown in  FIG. 17 . A description on the bending process will be described later. 
     As shown in  FIG. 18 , the inner and outer coils  131 ,  133  are each formed in a generally hexagonal shape. Twisted portions  131 C,  133 C and slant side portions  131 G,  131 F,  133 G,  133 F form crossover line portions of stator coils. 
     In the enamel coating-chipped off portions  131 A,  131 B,  133 A, and  133 B, predetermined joined face portions are joined together at their joined faces, then are cut as in  FIG. 2 , and thereafter welded as in  FIGS. 3 and 4 . 
     The coils thus formed are inserted into slots  161  of the stator indicated at  160 , as shown in  FIG. 19  and are joined by welding in the respective joined face portions to form stator coils. 
     Next, a process of forming the stator coils  131 ,  133  and a process of assembling the stator  160  will be described below with reference to  FIGS. 20 to 31 . 
     The coil conductors shown in  FIG. 16  which serve as base metals of the inner and outer coils  131 ,  133  are formed in U shape in a U shape forming process (not shown), then in the process shown in  FIG. 20 , plural U-shaped inner and outer coils  131 ,  133  are inserted and set into separate inserting fixtures  200 . 
     In the process shown in  FIG. 21 , the U-shaped portions of the plural inner and outer coils  131 ,  133  set in the inserting fixtures  200  are twisted by twisting fixtures  210 . 
     In the process shown in  FIG. 22 , a stator core  302  is set in a stator assembly fixture  300  provided with a coil guide  301 . 
     In the process shown in  FIG. 23 , the inner coils  131  are first set using the coil guide  301  into slots formed in the stator core  302  which has been set in the stator assembling fixture  300 . 
     In the process shown in  FIG. 24 , the outer coils  133  are inserted and set into slots formed in the stator core  302  with use of the coil guide  301  so as to be positioned outside the inner coils  131  which have already been set. 
       FIG. 25  shows the stator core  302  with inner and outer coils  131 ,  133  set therein. 
     In this state, joined end portions of the inner and outer coils  131 ,  133  are not ready for joining yet. 
     In the process shown in  FIG. 26 , the outer coils  133  are first pushed into the stator  302  with use of a coil pushing jig  303  and a rotary shaft  304  is rotated in e direction of arrow, causing a lower die  305  to rotate and thereby twisting the joining end portions into a predetermined shape. 
     In the process shown in  FIG. 27 , the lower die  305  is removed and terminals of the outer coils  133  are deformed into a state necessary for joining as in  FIG. 1 , followed by caulking to effect forming. Thereafter, cutting is performed by the cutting device as in  FIG. 2  and preparations are made for welding. 
     In the process shown in  FIG. 28 , the joined face portions are welded by Tig welding by the method shown in  FIGS. 3 and 4 . At this time, a welding height is measured by a sensor  306  and a check is made to see whether the measured height is an appropriate height or not. 
     In the process shown in  FIG. 29 , the inner coils  131  are pushed into the stator  302  with use of a coil pushing jig  307  and the rotary shaft  304  is rotated in the direction of arrow to rotate the lower die  305 , thereby twisting the joining end portions into a predetermined shape. 
     In the process shown in  FIG. 30 , the lower die  305  is removed and terminals of the inner coils  131  are deformed into a state necessary for joining as in  FIG. 1 , followed by caulking to effect forming. Thereafter, cutting is performed by the cutting device as in  FIG. 2  and preparations are made for welding. 
     In the process shown in  FIG. 31 , the joined face portions are welded by Tig welding by the method shown in  FIGS. 3 and 4 . At this time, a welding height is measured by the sensor  306  and a check is made to see whether the measured height is an appropriate height or not. 
     In this way the stator shown in  FIG. 19  is obtained.