JP2019009908A - Squirrel-cage induction rotary electric machine and short-circuit ring support method - Google Patents

Abstract

To secure bond strength while facilitating gap dimension management in bonding between a secondary conductor bar and a short-circuit ring in a squirrel-cage induction rotary electric machine.SOLUTION: A squirrel-cage induction rotary electric machine is provided with: a rotor 10 having a rotor shaft 11, a rotor core 12, a plurality of secondary conductor bars 13, and two short-circuit rings 15 which are bonded to the respective ends of the plurality of secondary conductor bars 13 on both ends thereof; and a stator. Secondary conductor bar side bonding surfaces 14 having at least one recess radially extending along end surfaces are formed on the respective end surfaces of the plurality of secondary conductor bars 13. Each of a short-circuit ring side bonding surface 15b and the secondary conductor bar side bonding surface 14 is bonded by a material for bonding filled between the short-circuit ring side bonding surface 15b and the secondary conductor bar side bonding surface 14.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a squirrel-cage induction rotating electric machine and a short-circuit ring support method.

  In the squirrel-cage induction rotating electric machine, the rotor includes a rotor shaft that is rotatably supported at both ends, a rotor core provided on the radially outer side of the rotor shaft, and a plurality of secondary conductor bars.

  The plurality of secondary conductor bars are electrical conductors. Each of the plurality of secondary conductor bars is embedded in the rotor core, is arranged at intervals in the circumferential direction, extends in the axial direction, and both ends protrude from the rotor core.

  The respective end portions of the plurality of secondary conductor bars are joined by an annular short-circuited ring and are electrically short-circuited, and are configured to resist centrifugal force generated when the rotor rotates (patent) Reference 1).

Japanese Patent No. 3650351

  FIG. 9 is a longitudinal sectional view showing an example of a conventional short-circuited ring connection structure. The short ring 15 and each of the plurality of secondary conductor bars 13 are joined by brazing. That is, the short-circuit ring 15 is arranged at the end of the secondary conductor bar 13, and the end surface in the longitudinal direction of the secondary conductor bar 13 is used as a contact surface, or the radially inner side surface of the end of the secondary conductor bar 13 is used as the contact surface. As a contact surface, the short ring 15 and the secondary conductor bar 13 are joined by brazing on the contact surface.

  Taking the case where the end surface in the longitudinal direction (Z direction) of the secondary conductor bar 13 is a contact surface as shown in FIG. make. For this reason, the end portion of the secondary conductor bar 13 is formed with a surface 13m that is slightly inclined outward in the radial direction. At this time, if the amount of wax that enters the gap is small, sufficient bonding strength cannot be obtained. For this reason, the management of the gap dimension between the end of the secondary conductor bar 13 and the short-circuit ring 15 is important.

  The present invention has been made to solve the above-described problems, and in a squirrel-cage induction rotating electrical machine, it is possible to ensure bonding strength while facilitating management when joining a secondary conductor bar and a short-circuit ring. With the goal.

  In order to achieve the above-described object, the present invention extends in the axial direction and extends in the axial direction, and a rotor shaft that is rotatably supported on both sides in the axial direction, and is fixed to a radially outer side of the rotor shaft. A rotor core, a plurality of secondary conductor bars penetrating the rotor core in the axial direction, and opposite ends of the plurality of secondary conductor bars at both ends of the plurality of secondary conductor bars A rotor having two short-circuit rings formed with a short-circuit-ring-side joint surface, a stator core disposed radially outside the rotor core, and a plurality of stators disposed in the stator core A squirrel-cage induction rotating electrical machine having a stator having a winding, and each end face of the plurality of secondary conductor bars is parallel to the short-circuit ring side joint face and radially along the end face Secondary conductor bar side with at least one recess extending A joining surface is formed, and each of the short-circuiting ring-side joining surface and the secondary conductor bar-side joining surface is filled between the short-circuiting ring-side joining surface and the secondary conductor bar-side joining surface. It is characterized by being joined by a material.

  Further, the present invention provides a rotor shaft that extends in the axial direction and is rotatably supported on both sides in the axial direction, a rotor core that is fixed radially outside the rotor shaft and extends in the axial direction, A plurality of secondary conductor bars penetrating the rotor core in the axial direction, and two short-circuiting rings joined to respective ends of the plurality of secondary conductor bars at both ends of the plurality of secondary conductor bars In a squirrel-cage induction rotating electrical machine having a rotor, a short-circuit ring support method for joining each of the two short-circuit rings and the plurality of secondary conductor bars, each of the plurality of secondary conductor bars at each end portion A secondary conductor bar side joint surface forming step for forming a secondary conductor bar side joint surface having a recess extending along the end face in the circumferential direction on a surface parallel to the short circuit ring side joint surface; The plurality of secondary conductor bars Temporary fixing step of temporarily fixing the two short-circuiting rings in close contact with each of the plurality of secondary conductor bars in a state where the two short-circuiting rings are incorporated in the rotor core; A bonding step of forming a bonding member by allowing a bonding material to flow in and bonding the short-circuit ring and each of the plurality of secondary conductor bars.

  According to the present invention, in the squirrel-cage induction rotating electrical machine, it is possible to ensure the bonding strength while facilitating the management when the secondary conductor bar and the short-circuit ring are bonded.

It is a longitudinal cross-sectional view which shows the structure of the cage induction rotating electrical machine which concerns on 1st Embodiment. FIG. 4 is a partial vertical cross-sectional view taken along the line II-II in FIG. 3, showing an end portion of a secondary conductor bar and a portion of a short-circuit ring of the rotor of the squirrel-cage rotary electric machine according to the first embodiment. FIG. 3 is a partial plan view taken along line III-III in FIG. 2, showing an end portion of a secondary conductor bar and a portion of a short-circuit ring of the rotor of the squirrel-cage induction rotating electric machine according to the first embodiment. It is a perspective view showing the short circuit ring connection structure concerning a 1st embodiment. FIG. 5 is a partial cross-sectional view taken along line VV in FIG. 2 showing a short-circuit ring side joint surface and a secondary conductor bar-side joint surface of the short-circuit ring connection structure according to the first embodiment. It is a flowchart which shows the procedure of the short circuit ring support method which concerns on 1st Embodiment. It is a partial cross-sectional view which shows the short circuit ring side joint surface and secondary conductor bar side joint surface of the short circuit ring connection structure which concerns on 2nd Embodiment. It is a fragmentary cross-sectional view which shows the short circuit ring side joint surface and secondary conductor bar side joint surface of the short circuit ring connection structure which concerns on 3rd Embodiment. It is a longitudinal cross-sectional view which shows the example of the conventional short circuit ring connection structure.

  Hereinafter, a squirrel-cage induction rotating electrical machine and a short-circuit ring supporting method according to embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a configuration of a squirrel-cage induction rotating electrical machine according to the first embodiment. The cage induction rotating electric machine 100 includes a rotor 10 and a stator 20.

  The rotor 10 includes a rotor shaft 11, a rotor core 12, a plurality of secondary conductor bars 13, and two short-circuit rings 15.

  The rotor shaft 11 extends in the axial direction and is rotatably supported by bearings 30 on both sides in the axial direction. At one end of the rotor shaft 11, a coupling portion 11a for joining with a joining target such as a drive target device is formed. An inner fan 18 for circulating a cooling gas such as air in the machine is provided in a portion of the rotor shaft 11 between the rotor core 12 and one bearing 30.

  The rotor core 12 has a cylindrical shape that is fixed on the radially outer side of the rotor shaft 11 and extends in the axial direction. Since the magnetic flux in the rotor core 12 is induced by alternating current, the rotor core 12 has a laminated structure in which electromagnetic steel plates are laminated in order to reduce loss due to eddy current, and end plates 12a ( It is the structure tightened in FIG.

  The plurality of secondary conductor bars 13 penetrate the rotor core 12 in the axial direction in parallel to each other at intervals of the same radius from the axial center in the circumferential direction. The plurality of secondary conductor bars 13 protrude from both ends of the rotor core 12 in the axial direction. The protruding portions of the plurality of secondary conductor bars 13 are electrically connected to each other by the short-circuit ring 15. That is, each of the two short-circuit rings 15 is arranged on both outer sides in the axial direction of the rotor core 12 and is electrically connected between the plurality of secondary conductor bars 13 by connecting to the plurality of secondary conductor bars 13. Connect and short circuit.

  The stator 20 has a stator core 21 and a stator winding 22. The stator iron core 21 has a cylindrical shape and is arranged on the outer side in the radial direction of the rotor iron core 12 via a gap 19. The stator winding 22 penetrates through a plurality of slots (not shown) formed in the radial inner surface of the stator core 21 so as to penetrate in the axial direction in parallel with each other in the circumferential direction. 21 is connected outside in the axial direction in a coil shape.

  Rotor core 12, secondary conductor bar 13, short-circuit ring 15, and stator 20 are housed in frame 40. A plurality of fins (not shown) are provided on the outer surface of the frame 40 in order to promote heat dissipation from the frame 40 to the outside air. Both ends of the frame 40 in the axial direction are closed by bearing brackets 35, respectively. Each bearing bracket 35 supports the bearing 30 stationary.

  2 is a partial vertical cross-sectional view taken along the line II-II in FIG. 3 showing the end of the secondary conductor bar and the portion of the short-circuit ring of the rotor of the squirrel-cage induction rotating electric machine according to the first embodiment. FIG. 3 is a partial plan view taken along line III-III in FIG. FIG. 4 is a perspective view showing a short-circuited ring connection structure.

  Here, the direction along the rotation axis is defined as the Z direction, and the direction toward the axially outer side of the rotor core 12 is defined as positive. The direction from the center of the rotation axis toward the radially outer side in the plane perpendicular to the rotation axis is the R direction, and the direction around the point corresponding to the rotation axis center in the same plane is the Θ direction.

  The short-circuit ring 15 is annular, and the material is an electrically good conductor such as copper or aluminum. The short-circuit ring 15 is joined to the end surface of each secondary conductor bar 13 on the surface facing the rotor core 12. The surface of the short-circuiting ring 15 facing the rotor core 12 includes a short-circuiting ring inner end surface 15a in a plane perpendicular to the rotation axis, and a short-circuiting ring-side joint surface 15b formed so as to be further inclined from this surface. Have. The short-circuiting ring-side joining surface 15b is formed in a radially inner portion from the short-circuiting ring inner end surface 15a.

  The short-circuiting ring-side joint surface 15b is formed so as to have an inclination of an angle Φ with respect to the R-axis direction perpendicular to the Z-axis on a plane passing through the rotation axis center. The direction of the inclination of the short-circuit-ring-side joint surface 15b is a direction that moves away from the rotor core 12 and the secondary conductor bar 13 from the outside in the R direction toward the inside in the R direction.

  A holding ring 17 is provided on the outer side of the short-circuit ring 15 in the radial direction. The holding ring 17 is made of a material having excellent mechanical strength compared to the material of the short-circuiting ring 15 such as steel. In addition, the retaining ring 17 does not need to be an electrical conductor, and for example, a compound semiconductor such as silicon carbide and other insulators may be used.

  Each secondary conductor bar-side joining surface 14 of the plurality of secondary conductor bars 13 is formed to face the short-circuiting ring-side joining surface 15b. In other words, on the plane passing through the center of the rotation axis, it is formed so as to be inclined at an angle Φ with respect to the R-axis direction perpendicular to the Z-axis and in the same direction as the inclination of the short-circuit ring side joint surface 15b. The joint surface 14 and the short-circuit ring side joint surface 15b are parallel to each other.

  The secondary conductor bar side joining surface 14 and the short-circuiting ring side joining surface 15b are formed by injecting a brazing material filled in a space 14c between them or a joining material such as solder or adhesive in some cases. They are joined by the joining member 16. In addition, joining may be performed by performing welding while supplying a welding material. In this case, each of the secondary conductor bar-side joining surface 14 and the short-circuiting ring-side joining surface 15b partially forms a new layer by melting part of the surface.

  FIG. 5 is a partial cross-sectional view taken along line VV in FIG. 2 showing the short-circuit ring side joint surface and the secondary conductor bar side joint surface. The short-circuit-ring-side joining surface 15b and the secondary conductor bar-side joining surface 14 are in contact with each other without a gap therebetween. Here, being in contact means that the surfaces are in contact with each other at least two points or two lines, and are not brought closer to each other, rather than being in close contact with each other. .

  Three concave portions 14b arranged in the Θ direction are formed on the secondary conductor bar side joint surface 14 of each secondary conductor bar 13. Each recess 14b is formed so as to penetrate the secondary conductor bar 13 in the R direction along the end face. The cross-sectional shape of the recess 14b is a semicircle. Convex portions 14a are formed between the end portion in the circumferential direction of the end surface and the concave portion 14b, and between the adjacent concave portions 14b. The concave portions 14b are arranged in the circumferential direction without being spaced apart from each other, and the convex portions 14a are linear ridge lines.

  The short-circuiting ring-side joining surface 15b is not a perfect plane because it is formed in the annular portion so as to have a width in the Z-axis direction. On the other hand, the secondary conductor bar side joining surface 14 is normally inclined at the end face to form the concave portion 14b, so that the short-circuit ring side joining surface 15b and the secondary conductor bar side joining surface 14 are in contact with each other. The part which touches becomes the convex part 14a of both ends. Therefore, although the convex part 14a other than both ends leaves | separates slightly from the short circuit ring side joint surface 15b, there is no problem in particular.

  Here, although the case where the short-circuiting ring-side joining surface 15b and the secondary conductor bar-side joining surface 14 are in contact with each other without a gap is shown, the present invention is not limited to this. The case where it is slightly away from the state which touches may be sufficient. That is, it may be carried out while managing the gap so that the bonding strength does not vary. However, it is a great advantage to perform groove alignment in contact with each other in that special gap management is not required.

  Here, the number of the recesses 14b is not necessarily three as long as it is at least one. The number and shape of the recesses 14b, the width w, and the depth d are determined based on the volume of the space 14c that is sandwiched between the short-circuited ring-side joining surface 15b and the secondary conductor bar-side joining surface 14; That is, it determines the amount of brazing material or soldering material to be injected and affects the workability at the time of joining. For example, when the number of the concave portions 14b is one, not only the amount of the material for bonding is increased, but also when the injection amount is increased, there is a possibility that the material will drip and fall without being solidified in the middle. It is necessary to consider the point that becomes larger. In this respect, it may be better to provide a plurality of recesses 14b.

  As described above, the number of the recesses 14b may be set in consideration of the processing of the secondary conductor bar 13 and the work at the time of joining.

  FIG. 6 is a flowchart showing the procedure of the short-circuit ring supporting method according to the first embodiment. That is, the procedure for joining the short-circuit ring 15 and the secondary conductor bar 13 in the process of assembling the cage induction rotating electric machine 100 is shown.

  First, the short-circuit ring side joint surface 15b is formed on the short-circuit ring 15 (step S01). Further, the secondary conductor bar-side joining surface 14 is formed at the end of each of the plurality of secondary conductor bars 13 protruding in the axial direction (step S02).

  Next, the rotor shaft 11, the rotor core 12, and the secondary conductor bar 13 are assembled (step S03). As a result, the rotor core 12 incorporating the secondary conductor bar 13 is attached to the outer side in the radial direction of the rotor shaft 11.

  The short-circuit ring 15 in which the short-circuit ring-side joint surface 15b is formed in step S01 is temporarily fixed so as to be in contact with the secondary conductor bar-side joint surface 14, and groove alignment is performed (step S04).

  Next, a bonding material such as brazing material, solder, or adhesive is injected into the space 14c between the short-circuiting ring-side bonding surface 15b and the secondary conductor bar-side bonding surface 14, and the short-circuiting ring-side bonding surface 15b and the secondary surface Joining is performed by setting the joining member 16 between the conductor bar-side joining surfaces 14 (step S05). The joining may be performed by performing welding while supplying the molten material. By performing the bonding, the short-circuit ring 15 is bonded to each of the plurality of secondary conductor bars 13 via the bonding member 16.

  After the joining of the short-circuit ring 15 and the plurality of secondary conductor bars 13 is completed, the rotor 10 and the cage induction rotating electrical machine 100 are further assembled (step S06).

  Next, the effect of this embodiment will be described. The first effect is as follows.

  The short-circuit ring-side joining surface 15b and the secondary conductor bar-side joining surface 14 are aligned with each other by performing groove alignment in a state where they are in contact with each other at two convex portions 14a without being spaced apart from each other. Management is easy without requiring special gap management, and workability is improved. Also, quality variations such as bonding strength can be reduced.

  Next, the second effect will be described. In the present embodiment, the concave portion 14b is formed in the secondary conductor bar side joining surface 14. For this reason, when injecting the bonding material, the bonding material easily penetrates into the space 14c formed by the recess 14b.

Next, the third effect will be described. In this embodiment, the short-circuited ring-side joining surface 15b and the secondary conductor bar-side joining surface 14 which are groove surfaces are inclined by an angle Φ with respect to a direction perpendicular to the axial direction. Now, assuming that the cross-sectional area of the secondary conductor bar 13 is S, the area S1 of the groove surface is larger than the cross-sectional area S as shown in the following equation (1).
S1 = S / cosΦ (1)

  The joining force between the short-circuited ring-side joining surface 15b, which is the groove surface, and the secondary conductor bar-side joining surface 14 is proportional to the area of the opposing joining surface. Therefore, the joining force larger than before can be obtained by the short-circuit ring supporting method according to the present embodiment.

  As described above, according to the first embodiment, in the squirrel-cage induction rotating electric machine, it is possible to ensure the bonding strength while facilitating the management when the secondary conductor bar and the short-circuit ring are bonded.

[Second Embodiment]
FIG. 7 is a partial cross-sectional view showing a short-circuit ring side joint surface and a secondary conductor bar-side joint surface of the short-circuit ring connection structure according to the second embodiment.

  The second embodiment is a modification of the first embodiment. The secondary conductor bar side joining surface 14 is formed so that the tip of the convex portion 14a has a width t. Other points are the same as those of the first embodiment.

  If the width t becomes too large, the bonding strength decreases by the amount that the total value of the width of the joining member 16 in the Θ direction decreases. Therefore, the total value of the width t is within an appropriate range that is less than a margin for the required bonding strength. There must be. If it is within this appropriate range, the width t of the tip of the convex portion 14a may be processed as a guide value so as to form a tip portion of about the width t, and even if the width of each convex portion 14a is different. Good.

  When the convex portion 14a is to be formed linearly as in the first embodiment, the height of the convex portion 14a may change due to a slight shift in the formation position of the concave portion 14b in the Θ direction. For example, when it deviates at the end portion in the circumferential direction, a part of the wall from the outside of the secondary conductor bar 13 holding the bonding material is missing. Therefore, the precision at the time of cutting for forming the recess 14b becomes severe.

  On the other hand, in the second embodiment, such a problem does not occur even if the processing position of the recess 14b is shifted in the range of the width t. Therefore, the accuracy of positioning in the Θ direction in the cutting process for forming the recess 14b may not be as severe as in the first embodiment.

[Third Embodiment]
FIG. 8 is a partial cross-sectional view showing a short-circuit ring side joint surface and a secondary conductor bar-side joint surface of the short-circuit ring connection structure according to the third embodiment.

  The third embodiment is a modification of the first embodiment. In this embodiment, the cross-sectional shape of the recessed part 14d formed in the secondary conductor bar side joining surface 14 differs from the cross-sectional shape of the recessed part 14b in 1st Embodiment. Other points are the same as in the first embodiment.

  The cross-sectional shape of the recess 14d formed in the secondary conductor bar-side joining surface 14 in the third embodiment is a shape in which a semicircle is connected to the end of the rectangle extending in the Θ direction in the Θ direction. For this reason, even if the circumferential width w of the recess 14d increases, the depth d does not increase accordingly. The depth d can be set separately, and the volume of the space 14c is almost proportional to the width w of the recess 14d. As a result, the consumption of the joining material can be suppressed to an appropriate amount.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, embodiment is shown as an example and is not intending limiting the range of invention. For example, in the embodiment, a squirrel-cage induction rotating electric machine in which one internal fan is provided in the machine and naturally dissipates heat to the outside air with a finned frame is shown as an example. Other cooling methods such as a forced cooling method by using a forced air cooling method with an external fan may be used.

  In the embodiment, the first feature that the concave portion 14b is formed in the secondary conductor bar side joint surface 14, and the shorted ring side joint surface 15b and the secondary conductor bar side joint surface 14 are inclined parallel to each other. The case of having both of the second features to be formed has been shown as an example, but a form having only the first feature is also effective.

  Further, the features of the second embodiment and the features of the third embodiment may be combined.

  Furthermore, the embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention.

  The embodiments and the modifications thereof are included in the scope of the invention and the scope of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Rotor, 11 ... Rotor shaft, 11a ... Coupling part, 12 ... Rotor core, 12a ... End plate, 13 ... Secondary conductor bar, 14 ... Secondary conductor bar side joining surface, 14a ... Convex part, 14b , 14d ... concave portion, 14c ... space, 15 ... short-circuit ring, 15a ... short-circuit ring inner end surface, 15b ... short-circuit ring side joint surface, 16 ... joining member, 17 ... holding ring, 18 ... inner fan, 19 ... gap, 20 ... Stator, 21 ... stator core, 22 ... stator winding, 30 ... bearing, 35 ... bearing bracket, 40 ... frame, 100 ... squirrel-cage induction rotating electric machine

Claims (6)

A rotor shaft that extends in the axial direction and is rotatably supported on both sides in the axial direction, a rotor core that is fixed radially outward of the rotor shaft and extends in the axial direction, and the inside of the rotor core A plurality of secondary conductor bars penetrating in the axial direction, and two short circuits in which short-circuited ring-side joint surfaces facing the respective end portions of the plurality of secondary conductor bars are formed at both ends of the plurality of secondary conductor bars A rotor having a ring;
A stator core having a stator core disposed radially outside the rotor core, and a plurality of stator windings disposed in the stator core;
A squirrel-cage induction rotating electric machine comprising:
Each end surface of the plurality of secondary conductor bars is formed with a secondary conductor bar side joint surface having at least one recess that is parallel to the short-circuit ring side joint surface and extends in the radial direction along the end surface,
Each of the short-circuit ring side joint surface and the secondary conductor bar side joint surface is joined by a joining material filled between the short-circuit ring side joint surface and the secondary conductor bar side joint surface. ,
A squirrel-cage induction rotating electrical machine. The short-circuit ring-side joining surface is formed on at least a part of a surface of the short-circuit ring that faces each of the ends of the plurality of secondary conductor bars, and the plurality of secondary conductors become radially inward from the radially outer side. Formed to have a slope away from the bar,
The squirrel-cage induction rotating electric machine according to claim 1, wherein the secondary conductor bar side joint surface has an inclination so as to face the short-circuit ring side joint surface in parallel.   The squirrel-cage induction rotating electric machine according to claim 1 or 2, wherein the recess has a semicircular cross-sectional shape.   The cross-sectional shape of the recess is a combination of a rectangle and a quarter circle on both sides in the circumferential direction and having a radius equal to the depth of the rectangle opened toward the short-circuit ring side joint surface. The squirrel-cage induction rotating electric machine according to claim 1 or 2, characterized by the above-mentioned. A rotor shaft that extends in the axial direction and is rotatably supported on both sides in the axial direction, a rotor core that is fixed radially outward of the rotor shaft and extends in the axial direction, and the inside of the rotor core A cage having a plurality of secondary conductor bars penetrating in the axial direction, and a rotor having two short-circuited rings joined to respective ends of the plurality of secondary conductor bars at both ends of the plurality of secondary conductor bars In the induction rotating electrical machine, a short-circuit ring support method for joining each of the two short-circuit rings and the plurality of secondary conductor bars,
A secondary conductor bar side joint surface having a recess extending along at least one radial direction in the circumferential direction on a surface parallel to the short circuit ring side joint surface at each end portion of the plurality of secondary conductor bars. Forming a secondary conductor bar side joint surface forming step;
In the state where the plurality of secondary conductor bars are incorporated in the rotor core, the two shorting rings are temporarily fixed by closely contacting the respective shorting ring side joint surfaces with the plurality of secondary conductor bars. A fixed step;
A bonding step of forming a bonding member by injecting a bonding material into each of the recesses and bonding the short-circuit ring and each of the plurality of secondary conductor bars;
A method for supporting a short-circuited ring, comprising:   Before the secondary conductor bar side joint surface forming step, with respect to the short circuit ring, the short circuit ring side joint surface facing each end of the plurality of secondary conductor bars is in a direction perpendicular to the axial direction. 6. The short-circuiting ring support method according to claim 5, further comprising a short-circuiting ring-side joint surface forming step of forming a short-circuiting ring-side joint surface so as to be inclined.

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