JP2012175726A - Rotor for use in induction motor, induction motor, and method for manufacturing rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor that allows rotor bars and a short-circuit ring to be favorably joined together.SOLUTION: A first end 16 of each of rotor bars 15 projects from a first end surface of a rotor core 12. A plurality of fitting holes 18 are penetrated through a short-circuit ring 13 in an axial direction of the short-circuit ring 13. Each of the fitting holes 18 has: a guide hole portion 181 that opens in a first end surface of the short-circuit ring 13; a bonding hole portion 182 that opens in a second end surface of the short-circuit ring 13; and a step portion 183 that connects the guide hole portion 181 and the bonding hole portion 182. In a process of the first end 16 of each of the rotor bars 15 being pressed into the bonding hole portion 182, an electric current is passed between a first electrode 23 and a second electrode 25. The second electrode 25 and the first electrode 23 form a capacitor-type resistance welding device that uses instantaneous discharge current as welding energy.

Description

  The present invention relates to a rotor used for an induction motor in which an end of a rotor bar protruding from an end face of a rotor core is fitted into a fitting hole of a short-circuit ring, an induction motor, and a method for manufacturing the rotor.

  A rotor in which a rotor bar is fitted in a fitting hole of a short-circuit ring is disclosed in Patent Document 1, for example. In the rotor disclosed in Patent Document 1, an aluminum die-cast end ring (short-circuit ring) is attached to the ends of a plurality of copper conductors (rotor bars) that are passed through insertion holes provided in a laminated iron core (rotor core). ) And is joined to the end of the conductor by electric resistance welding.

JP-A-57-80250

  However, in the case of a metal having a low electrical resistance such as aluminum or copper, the electrical resistance welding is performed so that the electrode is applied in a state where the conductor and the end ring are set at the joining position as shown in FIG. Large power consumption is required to obtain the necessary heat generation.

  An object of this invention is to provide the rotor, the induction motor, and the manufacturing method of a rotor which can join a rotor bar and a short circuit ring suitably.

  According to the first to seventh aspects of the present invention, the rotor bar is inserted through the insertion hole of the rotor core, and the end portion of the rotor bar protruding from the end surface of the rotor core is fitted into the fitting hole of the short-circuit ring. In the invention according to claim 1, the fitting hole includes a joining hole portion into which the end portion is fitted, and a guide hole portion that is continuous with the joining hole portion through a stepped portion. The guide hole portion has a cross-sectional area larger than a cross-sectional area of the joint hole portion and includes the joint hole portion when viewed in the axial direction of the rotor core, and the end portion of the rotor bar is While being press-fitted into the joint hole, electric resistance welding is performed and the joint hole is fitted.

  A current is passed between the rotor bar and the short-circuit ring in a state where the peripheral edge of the end portion of the rotor bar is in contact with the stepped portion. In electrical resistance welding performed while the end of the rotor bar is pressed into the joint hole, the joint between the rotor bar and the short-circuiting ring plastically flows while destroying the oxide film on the surface layer, and plastic flow between the rotor bar and the short-circuiting ring. Solid phase diffusion bonding is performed when the joint is in pressure contact.

In a preferred example, the fitting hole is a through-hole penetrating from the first end face of the short-circuit ring to the second end face of the short-circuit ring.
Employment of the fitting hole penetrating allows direct contact between the electrode and the tip of the end of the rotor bar. Such direct contact is effective for suppressing excessive heat generation in the short-circuited ring.

In a preferred example, the rotor bar is provided with an insulating coating on a peripheral surface located in the insertion hole.
If the current flow (transverse current flow) from the rotor core to the rotor bar without passing through the short-circuit ring is allowed, the output of the induction motor is lowered. The insulating coating prevents the occurrence of a lateral current flow, but when the insulating coating is broken by heat, a lateral current flow occurs. In projection welding, the heat input is limited to the vicinity of the step portion and the vicinity of the joint hole portion, so that the insulating coating is not destroyed.

In a preferred example, the edge portion of the insulating coating reaches the guide hole.
Since the insulating coating is not destroyed by heat input, water does not enter the guide hole, and galvanic corrosion between the short-circuit ring and the rotor bar due to water entering the guide hole is avoided. The

In a preferred example, the end surface of the end portion of the rotor bar is covered with an insulating member.
The insulating member covering the tip surface of the end portion of the rotor bar prevents galvanic corrosion between the tip surface and the short-circuit ring.

  In a preferred example, the fitting hole is a through-hole penetrating from the first end surface of the short-circuit ring to the second end surface of the short-circuit ring, and the insulating member deforms an opening periphery of the joint hole portion. The deformed portion is fixed to the tip surface of the end portion.

The insulating member can be easily fixed.
In a preferred example, the stepped portion has a forming peripheral surface having a tapered peripheral surface shape whose diameter decreases from the guide hole portion side toward the joint hole portion side.

Such a tapered peripheral surface shape is advantageous for facilitating the entry of the end of the rotor bar into the joint hole.
The invention of claim 8 is an induction motor using the rotor according to any one of claims 1 to 7.

  In the invention of claim 9 and claim 10, the rotor bar is inserted through the insertion hole of the rotor core, the end of the rotor bar protruding from the end surface of the rotor core is fitted into the fitting hole of the short-circuit ring, The rotor bar is directed to a method of manufacturing a rotor for use in an induction motor in which an insulating film is applied to a peripheral surface located in the insertion hole. In the invention of claim 9, the rotor bar is inserted into the rotor core. A first positioning step of positioning by inserting a peripheral edge of one end portion into a guide hole portion of the first fitting hole of the first short-circuit ring; and a transverse area smaller than a transverse area of the guide hole portion of the first fitting hole A first electric resistance welding process in which the first end is press-fitted into the joint hole and a current is passed between the rotor bar and the first short-circuit ring, and a first of the rotor bar inserted into the rotor core is inserted. The edge of the two ends A second positioning step of inserting and positioning in the guide hole portion of the second fitting hole of the two short-circuiting ring, and the joint hole portion having a transverse area smaller than the transverse area of the guide hole portion of the second fitting hole; A second electric resistance welding step of press-fitting two end portions and causing a current to flow between the rotor bar and the second short-circuit ring.

  The first electric resistance welding process and the second electric resistance welding process are processes for instantaneous heating and instantaneous press fitting. The joint portion between the rotor bar and the short-circuiting ring plastically flows while destroying the oxide film on the surface layer thereof, and the joint portion that plastically flows is subjected to solid-phase diffusion bonding by press contact.

  In a preferred example, after the second electric resistance welding process, an insulating member is disposed and fixed on the distal end surface of the first end portion, and an insulating member is disposed on the distal end surface of the second end portion. And a second insulating step for fixing.

  The present invention has an excellent effect that the rotor bar and the short-circuit ring can be suitably joined.

Sectional drawing of the induction motor which shows 1st Embodiment. The perspective view of a rotor. (A) is a sectional side view of a rotor. (B), (c) is a partial expanded side sectional view. (A) is a sectional side view for demonstrating the manufacturing method of a rotor. (B) is a partial expanded side sectional view. The sectional side view for demonstrating the manufacturing method of a rotor. (A) is a sectional side view for demonstrating the manufacturing method of a rotor. (B) is a partial expanded side sectional view. The sectional side view for demonstrating the manufacturing method of a rotor. (A) is a sectional side view for demonstrating the manufacturing method of a rotor. (B), (c) is a partial expanded side sectional view. (A) is a sectional side view for demonstrating the manufacturing method of a rotor. (B), (c) is a partial expanded side sectional view. The exploded side sectional view showing a 2nd embodiment.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a rotor 11 is rotatably provided in a cylinder of a cylindrical stator 101 constituting the induction motor 10. The rotor core 12 constituting the rotor 11 has a plurality of insertion holes 121 penetrating in the axial direction of the rotor core 12. The plurality of insertion holes 121 are annularly arranged around the shaft hole 122 of the rotor core 12 through which the rotating shaft 111 passes, and the copper rotor bar 15 is fitted and fixed to each insertion hole 121.

As shown in FIG. 2, aluminum short-circuit rings 13 and 14 are joined to both ends of the rotor core 12.
As shown in FIG. 3A, an enamel insulating coating 20 is applied to the peripheral surface of the rotor bar 15 located in the insertion hole 121. The insulating coating 20 provides electrical insulation between the rotor bar 15 and the rotor core 12.

  One first end 16 of the rotor bar 15 protrudes from one end face 123 of the rotor core 12, and the other second end 17 of the rotor bar 15 protrudes from the other end face 124 of the rotor core 12. A plurality of fitting holes 18 are provided in the short-circuiting ring 13 in the axial direction of the short-circuiting ring 13, and the first end 16 of the rotor bar 15 is fitted and fixed to each fitting hole 18. . A plurality of fitting holes 19 are provided in the short-circuiting ring 14 in the axial direction of the short-circuiting ring 14, and the second end 17 of the rotor bar 15 is fitted and fixed to each fitting hole 19. .

  As shown in FIG. 3B, the fitting hole 18 includes a guide hole portion 181 that opens on one first end surface 131 (side facing the end surface 123) of the short-circuit ring 13, and the other first end surface 131 of the short-circuit ring 13. It consists of a joint hole 182 that opens to the two end faces 132 and a step 183 that connects the guide hole 181 and the joint hole 182. The cross-sectional area of the guide hole 181 (cross-sectional area on the plane perpendicular to the axial direction of the rotor core 12) is larger than the cross-sectional area of the joint hole 182 (cross-sectional area on the plane perpendicular to the axial direction of the rotor core 12). It is large and includes a joint hole 182 when viewed in the direction of the axis of the rotor core 12. The formation peripheral surface 184 that forms the stepped portion 183 is formed in a tapered peripheral surface shape whose diameter decreases from the guide hole portion 181 side toward the joint hole portion 182 side.

  One end edge 201 of the insulating coating 20 is slightly bonded from the insertion hole 121 to the formation peripheral surface forming the guide hole 181, and is not covered by the insulating coating 20. This part is joined to the joint hole 182 and fixed to the short-circuit ring 13. The front end surface 161 of the first end portion 16 is covered with a thin plate-shaped insulating member 21 made of resin and located inside the second end surface 132. The insulating member 21 is fixed on the distal end surface 161 by a deformed portion 28 obtained by deforming the opening periphery of the joint hole 182 on the second end surface 132 side.

  As shown in FIG. 3C, the fitting hole 19 is formed in the guide hole portion 191 that opens on one end surface 141 (the side facing the end surface 124) of the short-circuit ring 14 and the other end surface 142 of the short-circuit ring 14. It consists of a joint hole 192 that opens and a step 193 that connects the guide hole 191 and the joint hole 192. The cross-sectional area of the guide hole 191 (cross-sectional area on a plane perpendicular to the axial direction of the rotor core 12) is larger than the cross-sectional area of the joint hole 192 (cross-sectional area on a plane perpendicular to the axial direction of the rotor core 12). It is large and includes a joint hole 192 when viewed in the direction of the axis of the rotor core 12. The stepped portion 193 is formed in a tapered peripheral surface shape whose diameter is reduced from the guide hole portion 191 side toward the joint hole portion 192 side.

  The other end portion 202 of the insulating coating 20 is slightly joined from the insertion hole 121 to a formation peripheral surface that forms the guide hole 191, and is not covered by the insulating coating 20. These portions are fixed to the short-circuit ring 14 by being bonded to the formation peripheral surface forming the bonding hole portion 192. The distal end surface 171 of the second end portion 17 is covered with the resin-made thin plate-shaped insulating member 22 inside the end surface 142. The insulating member 22 is fixed on the distal end surface 171 by a deformed portion 29 obtained by deforming the opening peripheral edge of the joint hole portion 192 on the end surface 142 side.

Next, the manufacturing method of the rotor 11 is demonstrated based on FIGS. In this production, a capacitor type resistance welding machine is used.
The rotor bar 15 is fixed to the rotor core 12 by returning the rotor core 12 to room temperature after inserting the rotor bar 15 into the insertion hole 121 of the rotor core 12 thermally expanded by heating.

  As shown in FIG. 4A, a plurality of alignment convex portions 231 that are convex upward are arranged in a ring shape in the circumferential direction of the first electrode 23 in the lower disk-shaped first electrode 23. The rotor core 12 that is inserted and fixed through the rotor bar 15 is supported by a first protection ring 24 that is disposed above the first electrode 23 so as to be movable up and down. The initial insertion depth of the rotor bar 15 is such that when the rotor core 12 comes into contact with the short-circuit ring 13, the peripheral edges 162 of the front end surfaces 161 of the first end portions 16 of the plurality of rotor bars 15 are fitted as shown in FIG. It is arranged in the guide hole 181 of the hole 18. In this case, the peripheral edge 162 is arranged so as to be separated from the guide hole 181. The step of disposing the peripheral edge 162 in the guide hole 181 includes the first protective ring 24 and the second protective ring 26 disposed so as to be movable up and down above the rotor core 12 together. This is a first positioning step in which the leading edge of the first end portion 16 of the rotor bar 15 is inserted into the guide hole portion 181 of the short-circuit ring 13 for positioning.

  Next, as shown in FIG. 4A, the second electrode 25 disposed above the rotor core 12 is moved downward, and the second electrode 25 contacts the second end 17 of the rotor bar 15. Here, the second electrodes 25 are electrically independent corresponding to each of the rotor bars 15 and are energized by individual power supply devices. When the second electrode 25 is further moved downward, the rotor bar 15 is further inserted into the insertion hole 121, the peripheral edge 162 of the first end 16 of the rotor bar 15 comes into contact with the formation peripheral surface of the stepped portion 183, and the rotor bar 15 A current flows between the short circuit ring 13.

  The second electrode 25 and the first electrode 23 constitute a capacitor type resistance welder that uses the instantaneously discharged current as welding energy. Since the second electrode 25 is electrically independent and is energized by an individual power supply device, it can be controlled in accordance with variations in the shape and resistance value of the rotor bar 15 and each fitting hole 18, and the welding current can be biased. It can be reduced.

  When the rotor bar 15 is further moved downward while a current flows between the rotor bar 15 and the short-circuit ring 13, the first end portion 16 is press-fitted into the joint hole 182. Then, as shown in FIG. 5, when the tip surface 161 of the rotor bar 15 contacts the alignment convex portion 231 of the first electrode 23, the downward movement of the second electrode 25 is stopped. The elapsed time from the contact of the peripheral edge 162 of the first end portion 16 of the rotor bar 15 with the stepped portion 183 until the press-fitting is completed is a short time.

  The step of moving the rotor bar 15 downward and causing a current to flow between the first electrode 23 and the second electrode 25 presses the first end portion 16 into the joint hole portion 182 of the fitting hole 18, and 15 is a first electric resistance welding process in which a current is passed between 15 and the short-circuit ring 13.

  Next, as shown in FIG. 6A, the shorting ring 14 is placed on the second end 17 of the rotor bar 15 after removing the second protection ring 26. In the state where the short-circuit ring 14 is placed on the second end portion 17, the peripheral edge 172 of the distal end surface 171 of the second end portion 17 of the plurality of rotor bars 15 is the guide hole portion of the fitting hole 19 as shown in FIG. 191. In this case, the peripheral edge 172 is disposed so as to be separated from the guide hole portion 191 and contacts the stepped portion 183. The step of disposing the peripheral edge 172 in the guide hole portion 191 is a second positioning step of positioning the tip peripheral edge of the second end portion 17 of the rotor bar 15 by inserting it into the guide hole portion 191 of the short-circuit ring 14.

Next, when the second electrode 25 disposed above the short-circuit ring 14 is moved downward, the second electrode 25 comes into contact with the short-circuit ring 14, and a current flows between the rotor bar 15 and the short-circuit ring 14.
When the rotor bar 15 is moved downward while a current flows between the rotor bar 15 and the alignment projection 231 of the first electrode 23, the second end 17 is press-fitted into the joint hole 192. When the rotor bar 15 and the alignment protrusion 231 are in direct contact, almost no current flows through the current path via the short-circuit ring 13. Then, when the short-circuit ring 14 is moved down to a position where the end edge 202 of the insulating coating 20 enters the guide hole 191 as shown in FIG. 7, the downward movement of the second electrode 25 is stopped. The elapsed time from the contact of the peripheral edge 172 of the second end portion 17 of the rotor bar 15 to the stepped portion 183 until the press-fitting is completed is a short time.

  The step of moving the short-circuiting ring 14 and flowing a current between the first electrode 23 and the second electrode 25 is to press-fit the second end 17 into the joint hole 192 of the fitting hole 19, This is a second electric resistance welding process in which a current is passed between the rotor bar 15 and the short-circuit ring 14.

  After the short-circuit ring 14 is fixed to the second end portion 17 of the rotor bar 15, the front end surfaces of the first and second end portions 16, 17 of the rotor bar 15 as shown in FIGS. 161 and 171 are covered with insulating members 21 and 22.

As shown in FIG. 9A, the insulating members 21 and 22 covering the front end surfaces 161 and 171 are fixed on the front end surfaces 161 and 171 using caulking jigs 27A and 27B.
As shown in FIGS. 9B and 9C, the caulking jigs 27 </ b> A and 27 </ b> B are provided at the peripheral edges (joining hole portions 182) of the fitting holes 18 and 19 on the second end surfaces 132 and 142 side of the short-circuit rings 13 and 14. , 192 of the opening periphery). The insulating members 21 and 22 are fixed on the distal end surfaces 161 and 171 by deformed portions 28 and 29 obtained by deforming the opening peripheral edges of the fitting holes 18 and 19 (opening peripheral edges of the joint hole portions 182 and 192). In the step of covering the distal end surface 161 of the first end portion 16 with the insulating member 21 and fixing the insulating member 21 on the distal end surface 161, the insulating member 21 is disposed and fixed on the distal end surface 161 of the first end portion 16. It is a first insulation process. In the step of covering the distal end surface 171 of the second end portion 17 with the insulating member 22 and fixing the insulating member 22 on the distal end surface 171, the insulating member 22 is disposed and fixed on the distal end surface 171 of the second end portion 17. It is a second insulation process.

Next, the operation of the first embodiment will be described.
When the second electrode 25 is moved downward and the peripheral edge 162 of the first end 16 of the rotor bar 15 comes into contact with the stepped portion 183, a current flows between the rotor bar 15 and the short-circuit ring 13. When the rotor bar 15 is further moved down from this state, the heat generated by the current flowing between the peripheral surface of the first end 16 and the joint hole 182 causes the peripheral surface of the first end 16 and the joint hole 182 to be heated. Plastic flow occurs between them. In this plastic flow, the oxide film on the surface layer of the peripheral surface of the first end portion 16 and the joint hole 182 is destroyed, and the new surfaces of the peripheral surface of the first end portion 16 and the joint hole portion 182 generated by the plastic flow are Is subjected to solid phase diffusion bonding by contact with pressure.

  In a state where the tip surface 161 of the first end portion 16 is in contact with the tip surface of the alignment convex portion 231 of the first electrode 23, the end edge portion 201 of the insulating coating 20 is formed on the formation peripheral surface that forms the guide hole portion 181. Surface bonding is performed, and the guide hole portion 181 is sealed by the edge portion 201 of the insulating coating 20. This sealed state prevents moisture around the short-circuit ring 13 from entering the guide hole 181.

  Similarly, when the second electrode 25 is moved downward and the peripheral edge 172 of the second end portion 17 of the rotor bar 15 contacts the stepped portion 193, a current flows between the rotor bar 15 and the short-circuit ring 13. When the second electrode 25 is further moved down from this state, the peripheral surface of the second end 17 and the joint hole 192 are generated by the heat generated by the current flowing between the peripheral surface of the second end 17 and the joint hole 192. Plastic flow occurs between the two. In this plastic flow, the oxide film on the surface layer of the peripheral surface of the second end 17 and the joint hole 192 is destroyed, and the new surfaces of the peripheral surface of the second end 17 and the joint hole 192 generated by plastic flow are Is subjected to solid phase diffusion bonding by contact with pressure.

  In a state where the press-fitting of the second end portion 17 into the joint hole portion 192 of the fitting hole 19 is completed, the end edge portion 202 of the insulating coating 20 is surface-bonded to the formation peripheral surface forming the guide hole portion 191, and the guide The hole 191 is sealed by the edge 202 of the insulating coating 20. This sealed state prevents moisture around the short-circuit ring 14 from entering the guide hole 191.

In the first embodiment, the following effects can be obtained.
(1) Electrical resistance welding in which electricity is passed between the end portions 16 and 17 of the rotor bar 15 and the short-circuit rings 13 and 14 is performed while the end portions 16 and 17 of the rotor bar 15 are press-fitted into the joint hole portions 182 and 192. Ring projection welding. Therefore, it is possible to reduce the electric power for obtaining the necessary heat generation.

  (2) The end portions 16 and 17 of the rotor bar 15 are press-fitted into the joint hole portions 182 and 192 while the oxide film at the joint portion between the rotor bar 15 and the short-circuit rings 13 and 14 is broken. Therefore, variation in conductivity at the junction between the rotor bar 15 and the short-circuit rings 13 and 14 due to the presence of the oxide film is suppressed.

  (3) If current flow (transverse current flow) from the rotor core 12 to the rotor bar 15 without passing through the short-circuit rings 13 and 14 is allowed, the output of the induction motor will be reduced. The insulating coating 20 prevents the occurrence of a lateral current flow. However, when the insulating coating 20 is broken by heat, the insulation between the rotor core 12 and the rotor bar 15 is impaired, and the lateral current flow is reduced. appear.

  In ring projection welding performed by bringing the peripheral edges 162 of the end portions 16 and 17 into contact with the stepped portions 183 and 193, the heat input area is limited to the vicinity of the stepped portions 183 and 193 and the vicinity of the joint hole portions 182 and 192. Therefore, the insulation between the rotor core 12 and the rotor bar 15 is not impaired by heat input.

  (4) The stepped portions 183 and 193 having tapered circumferential surfaces whose diameters are reduced from the guide hole portions 181 and 191 toward the joint hole portions 182 and 192 are provided at the end portions 16 of the rotor bar 15 toward the joint hole portions 182 and 192. , 17 is advantageous in facilitating the entry of.

  (5) The fitting holes 18 and 19 are through holes penetrating from the first end surfaces 131 and 141 of the short-circuit rings 13 and 14 to the second end surfaces 132 and 142. The adoption of the fitting holes 18 and 19 that pass through enables direct contact between the first electrode 23 and the front end surface 161 of the first end 16 of the rotor bar 15. Such direct contact is caused by the short-circuit ring 13 when a current is passed between the first electrode 23 and the second electrode 25 while the second end 17 of the rotor bar 15 is press-fitted into the fitting hole 19 of the short-circuit ring 14. It is effective for suppressing excessive heat generation.

  (6) Since the heat input area is limited to the vicinity of the stepped portions 183 and 193 and the joint hole portions 182 and 192, there is little possibility that the guide hole portions 181 and 191 are thermally deformed, and the heat input by ring projection welding The insulating coating 20 is not destroyed. Therefore, water does not enter the guide hole portions 181 and 191, and galvanic corrosion between dissimilar metals (the short-circuit rings 13 and 14 and the rotor bar 15) caused by water entering the guide hole portions 181 and 191 does not occur. Absent.

  (7) If water adheres to both the front end surfaces 161 and 171 of the end portions 16 and 17 of the rotor bar 15 and the formation peripheral surfaces of the joint holes 182 and 192, galvanic corrosion occurs. The insulating members 21 and 22 covering the tip surfaces 161 and 171 of the end portions 16 and 17 of the rotor bar 15 adhere to water on both the peripheral surfaces of the joint surfaces 182 and 192 with the tip surfaces 161 and 171. To prevent. Therefore, galvanic corrosion due to adhesion of water to both the front end surfaces 161 and 171 of the end portions 16 and 17 and the formation peripheral surfaces of the joint hole portions 182 and 192 does not occur.

  (8) The structure in which the insulating members 21 and 22 are fixed on the front end surfaces 161 and 171 by caulking and deforming the opening peripheral edges of the joint holes 182 and 192 of the fitting holes 18 and 19 is impossible to drop off the insulating members 21 and 22. It is easy to fix to the.

Next, a second embodiment of FIG. 10 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
The fitting hole 18A includes a guide hole portion 181, a joint hole portion 182, and a step portion 183A between the guide hole portion 181 and the joint hole portion 182, and the fitting hole 19A includes the guide hole portion 191, It consists of a joint hole portion 192 and a step portion 193A between the guide hole portion 191 and the joint hole portion 192. The tip peripheral edge of the first end portion 16 </ b> A of the rotor bar 15 is formed on the tapered peripheral surface 163, and the front end periphery of the second end portion 17 </ b> A of the rotor bar 15 is formed on the tapered peripheral surface 173.

  The maximum cross-sectional area of the first end portion 16A is smaller than the cross-sectional area of the guide hole portion 181 and larger than the cross-sectional area of the joint hole portion 182, and the maximum cross-sectional area of the second end portion 17A is the guide hole. It is smaller than the cross-sectional area of the portion 191 and larger than the cross-sectional area of the joint hole 192.

  When the first end portion 16A is press-fitted into the fitting hole 18A, the minimum diameter portion 185 of the stepped portion 183A comes into contact with the tapered peripheral surface 163, and current flows between the first end portion 16A and the short-circuit ring 13. Flowing. When the first end portion 16A is press-fitted into the joint hole portion 182, plastic flow and solid phase diffusion bonding occur as in the case of the first embodiment, and the first end portion 16A is within the joint hole portion 182. Fixed.

  When the second end portion 17A is press-fitted into the fitting hole 19A, the minimum diameter portion 195 of the stepped portion 193A comes into contact with the tapered peripheral surface 173, and current flows between the second end portion 17A and the short-circuit ring 14. Flowing. When the second end 17A is press-fitted into the joint hole 192, plastic flow and solid phase diffusion bonding occur as in the case of the first embodiment, and the second end 17A is within the joint hole 192. Fixed.

In the second embodiment, the same effect as in the first embodiment can be obtained.
In the present invention, the following embodiments are also possible.
The fixing between the rotor core 12 and the rotor bar 15 may be performed by an insulating resin mold. This insulating resin can also be used as the insulating coating 20.

A cooling fin may be integrally formed on the short-circuit rings 13 and 14 by die casting.
A metal other than aluminum may be used as the material of the short-circuit rings 13 and 14, and a metal other than copper may be used as the material of the rotor bar 15.

  10: Induction motor. 12 ... Rotor core. 121 ... insertion hole. 123, 124 ... end faces. 13, 14 ... Short circuit ring. 131, 141 ... first end face. 132, 142 ... second end face. 15 ... Rotor bar. 16 ... 1st edge part. 17 ... 2nd end part. 161, 171... 18, 19 ... fitting holes. 181, 191 ... guide holes. 182, 192: Joint hole. 183, 193 ... steps. 184, 194 ... Formation peripheral surface. 20: Insulating coating. 201 ... an edge part. 21, 22 ... insulating members. 28, 29 ... Deformation part.

Claims (10)

In the rotor used for the induction motor in which the rotor bar is inserted through the insertion hole of the rotor core, and the end of the rotor bar protruding from the end surface of the rotor core is fitted into the fitting hole of the short-circuit ring,
The fitting hole includes a joining hole portion into which the end portion is fitted, and a guide hole portion connected to the joining hole portion via a stepped portion,
The guide hole has a cross-sectional area larger than the cross-sectional area of the joint hole and includes the joint hole when viewed in the direction of the axis of the rotor core;
An end portion of the rotor bar is a rotor used for an induction motor that is fitted into the joint hole by electrical resistance welding while being press-fitted into the joint hole.   The rotor used for the induction motor according to claim 1, wherein the fitting hole is a through-hole penetrating from a first end face of the short-circuit ring to a second end face of the short-circuit ring.   The rotor used for the induction motor according to any one of claims 1 and 2, wherein the rotor bar is provided with an insulating coating on a peripheral surface located in the insertion hole.   The rotor used for the induction motor according to claim 3, wherein an edge portion of the insulating coating reaches the guide hole.   The rotor used for the induction motor according to any one of claims 1 to 4, wherein a front end surface of an end portion of the rotor bar is covered with an insulating member.   The fitting hole is a through-hole penetrating from the first end face of the short-circuit ring to the second end face of the short-circuit ring, and the insulating member deforms the opening peripheral edge of the joint hole portion of the short-circuit ring. The rotor used for the induction motor according to claim 5, wherein the rotor is fixed to a distal end surface of the end portion by a deforming portion.   The induction motor according to any one of claims 1 to 6, wherein the stepped portion has a forming peripheral surface having a tapered peripheral surface shape whose diameter decreases from the guide hole portion side toward the joint hole portion side. Rotor used.   An induction motor using the rotor according to any one of claims 1 to 7. The rotor bar is inserted into the insertion hole of the rotor core, the end of the rotor bar protruding from the end surface of the rotor core is fitted into the fitting hole of the short-circuit ring, and the rotor bar is located in the insertion hole. In the method of manufacturing a rotor used for an induction motor whose surface is coated with an insulating film,
A first positioning step of inserting and positioning the peripheral edge of the first end of the rotor bar inserted through the rotor core into the guide hole of the first fitting hole of the first short-circuit ring;
The first end portion is press-fitted into a joint hole portion having a cross-sectional area smaller than the cross-sectional area of the guide hole portion of the first fitting hole, and a current is passed between the rotor bar and the first short-circuit ring. A first electric resistance welding process;
A second positioning step of inserting and positioning the peripheral edge of the second end of the rotor bar inserted through the rotor core into the guide hole of the second fitting hole of the second short-circuit ring;
The second end portion is press-fitted into the joint hole portion having a cross-sectional area smaller than the cross-sectional area of the guide hole portion of the second fitting hole, and a current is passed between the rotor bar and the second short-circuit ring. The manufacturing method of the rotor used for the induction motor including a 2nd electrical resistance welding process.   After the second electrical resistance welding step, a first insulating step of disposing and fixing an insulating member on the front end surface of the first end, and a first insulating step of disposing and fixing an insulating member on the front end surface of the second end portion. The manufacturing method of the rotor used for the induction motor of Claim 9 including 2 insulation processes.

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