JP2016111895A - Method of manufacturing rotor core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a rotor core such that sufficient fastening force for a bridge and the rotor core can be secured.SOLUTION: The present invention relates to a method of manufacturing a rotor core 1 comprising a gap 14, a movable part 30 positioned outside the gap 14 in a radial direction of the rotor core 1, a fixed part 31 positioned inside the gap 14 in the radial direction of the rotor core 1, and a bridge B including a first expansion part B1 inserted into a first fitting hole 15 and a second expansion part B2 inserted into a second fitting hole 16. This manufacturing method includes diffusion joining of the first expansion part B1 to a wall surface of the first fitting hole 15 by pressing the wall surface of the first fitting hole 15 and the first expansion part B1 against each other by moving the movable part 30 radially outward with centrifugal force during rotation of the rotor core 1, and also heating the bridge B by supplying a pulse current to the bridge B. Similarly, the manufacturing method includes diffusion joining of the second expansion part B2 to a wall surface of the second fitting hole 16.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a rotor core in a motor.

  When manufacturing a rotor core of a motor, it is necessary to attach a magnet for generating torque to the rotor core. When a pair of magnets is attached to the rotor core, a technique is disclosed in which a bridge formed of a non-magnetic material is provided between the magnets in order to block the magnetic flux generated between the two magnets.

  For example, the rotor core described in Patent Document 1 is provided with a permanent magnet hole for fitting a permanent magnet, and a bridge is disposed at a position sandwiched between the permanent magnets, and the end of the bridge is fitted. A fitting hole for mating is provided in the rotor core. In Patent Document 1, a motor is manufactured by fitting one permanent magnet into each permanent magnet hole and fitting a non-magnetic bridge into the fitting hole. Here, in Patent Document 1, after the rotor core is heated and thermally expanded, the bridge is fitted into the fitting hole, and after the bridge is fitted, the rotor core is cooled and the fitting hole is contracted, so that the bridge is attached to the rotor core. It is connected.

JP 2009-201269 A

  In the method of connecting the rotor core and the bridge disclosed in Patent Document 1, the bridge is not sufficiently pressed against the wall surface of the fitting hole, and the fastening force between the bridge and the rotor core cannot be secured sufficiently. It was.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for manufacturing a rotor core that can sufficiently secure a fastening force between a bridge and the rotor core.

  A method for manufacturing a rotor core according to the present invention includes: a gap formed between an outer periphery and an inner circumference of the rotor core in a radial direction of the rotor core; and a movable portion positioned on the outer side of the gap in the radial direction of the rotor core. A fixed portion located on the inner side of the gap in the radial direction of the rotor core, and a first enlarged portion provided on one end side and inserted into a first fitting hole formed in the movable portion And a bridge having a second enlarged portion provided on the other end side and inserted into a second fitting hole formed in the fixed portion. In this manufacturing method, the movable portion is moved outward in the radial direction by a centrifugal force when the rotor core is rotated, so that the wall surfaces of the first and second fitting holes and the first and second fitting holes are moved. Pressing the second enlarged portion and applying a pulse current to the bridge to heat the bridge, and the first and second enlarged portions are connected to the first and second fitting holes. Diffusion-bonded to the wall surface.

  In this manufacturing method, the movable part is moved outward in the radial direction by centrifugal force. Therefore, a crimping force that crimps the wall surfaces of the first and second fitting holes and the first and second enlarged portions is applied. Furthermore, by supplying a pulse current to the bridge to heat the bridge, the wall surfaces of the first and second fitting holes and the first and second enlarged portions are heated. The joint surface of the first and second enlarged portions by the pressure generated by the centrifugal force applied to the wall surfaces of the first and second fitting holes and the first and second enlarged portions and the heat generated by the pulse current. Then, diffusion of atoms occurs between the wall surfaces of the first and second fitting holes, and the first and second enlarged portions are diffusion bonded to the wall surfaces of the first and second fitting holes. Therefore, the wall surfaces of the first and second fitting holes and the first and second enlarged portions are sufficiently crimped, and a fastening force between the bridge and the rotor core can be sufficiently secured.

  Moreover, the outer periphery of the movable part is located inside a reference circle having the radius of the rotor core. With this configuration, even if the movable part moves outward in the radial direction, the outer periphery of the movable part can be prevented from exceeding the reference circle on the outer periphery of the rotor core, so the rotor core does not interfere with the stator core.

  Further, during diffusion bonding, when the outer periphery of the movable part reaches the reference circle, the application of the pulse current to the bridge is stopped. As the bridge is heated, the movable part is also heated and softened, so that the outer periphery of the movable part reaches the reference circle with time. And by monitoring that the outer periphery of the movable part has reached the reference circle, the first and second enlarged parts can be sufficiently crimped to the wall surfaces of the first and second fitting holes by diffusion bonding. It can be determined that time has passed. Therefore, since the wall surfaces of the first and second fitting holes and the first and second enlarged portions can be securely crimped, the bridge and the rotor core can be securely fastened.

  According to the present invention, it is possible to provide a method for manufacturing a rotor core in which a sufficient fastening force between the bridge and the rotor core can be secured.

It is a front view of the rotor core concerning an embodiment. It is a principal part enlarged view of FIG. It is a principal part enlarged view at the time of inserting the both ends of a bridge in a fitting hole in FIG. It is an enlarged view of the 1st fitting hole in FIG. It is an enlarged view of the 2nd fitting hole in FIG. It is an enlarged view of a blocking hole and its periphery. It is the schematic of the rotor core in the case of bridge joining. It is a graph which shows the pattern of the pulse current which flows from a power supply. It is an enlarged view of the 1st fitting hole in case an inner side gap is small. It is an enlarged view of the 1st fitting hole at the time of rotating a rotor core from the state shown to FIG. 8A. It is an enlarged view of the 1st fitting hole at the time of heating by a pulse current from the state shown in FIG. 8B. It is an enlarged view of the 1st fitting hole in case an inner side gap is large. It is an enlarged view of the 1st fitting hole at the time of rotating a rotor core from the state shown to FIG. 9A. It is an enlarged view of the 1st fitting hole at the time of heating by a pulse current from the state shown in FIG. 9B. It is a principal part enlarged view after magnet insertion. In related technology, it is sectional drawing of a fitting hole at the time of inserting a bridge into a fitting hole.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in the rotor core 1, a total of eight magnetic poles 2 to 9 are arranged in the circumferential direction between the outer periphery P and the inner periphery I of the rotor core 1. Each of the magnetic poles 2 to 9 is an area obtained by equally dividing the rotor core 1.

  In each of the magnetic poles 2 to 9, magnet holes 11, 12, and 13 are provided. A gap 14 is provided between the magnet holes 12 and 13. Further, a first fitting hole 15 is provided on the outer periphery P side of the gap 14, and a second fitting hole 16 is provided on the inner periphery I side of the gap 14. Details of the components of these magnetic poles 2 to 9 will be described below.

  FIG. 2 is an enlarged view of a main part of the magnetic pole 2 in FIG. 3 shows that the first enlarged portion B1 provided on one end side of the non-magnetic bridge B is inserted into the first fitting hole 15 in the magnetic pole 2 of FIG. The state where the second enlarged portion B2 provided on the other end side of the nonmagnetic bridge B is inserted into the hole 16 is shown. In FIG. 3, the first enlarged portion B <b> 1 and the wall surface of the first fitting hole 15 are not joined. Further, the second enlarged portion B2 and the wall surface of the second fitting hole 16 are not joined. That is, the bridge B is not joined to the rotor core 1. 2 and 3, the magnets M1, M2, and M3 inserted into the magnet holes 11, 12, and 13 after the bridge B is joined to the rotor core 1 are indicated by two-dot chain lines.

  Hereinafter, the detailed configuration of the magnetic pole 2 will be described with reference to FIGS. 2 and 3. The magnetic poles 3 to 9 have the same configuration as that of the magnetic pole 2 shown below.

  The magnet hole 11 includes a magnet insertion hole 21 and blocking holes 22 and 23. The magnet insertion hole 21 extends in the circumferential direction of the rotor core 1, and the magnet M <b> 1 is inserted into the magnet insertion hole 21. Here, one end of the magnet M1 is expressed as a right end Ma, and the other end is expressed as a left end Mb.

  Further, a blocking hole 22 is provided facing the right end Ma of the magnet M1, and a blocking hole 23 is provided facing the left end Mb of the magnet M1. The blocking holes 22 and 23 are holes for blocking a magnetic flux path for blocking the magnetic flux from the right end Ma and the left end Mb of the magnet M1.

  Note that the opening width of the blocking hole 22 facing the right end Ma of the magnet M1 is smaller than the width of the right end Ma. Therefore, it is possible to suppress the magnet M1 from moving to the blocking hole 22 side. For the same reason, the opening width of the blocking hole 23 facing the left end Mb of the magnet M1 is smaller than the width of the left end Mb.

  Further, an adjustment hole 24 is provided in the vicinity of the blocking hole 22, and an adjustment hole 25 is provided in the vicinity of the blocking hole 23. The adjustment hole 24 and the adjustment hole 25 are holes for adjusting the magnetic flux path for adjusting the path of the magnetic flux coming out from the surface of the magnet M1.

  The magnet hole 12 includes a magnet insertion hole 26 and a blocking hole 27. The magnet insertion hole 26 extends in the radial direction of the rotor core 1, and the magnet M <b> 2 is inserted into the magnet insertion hole 26. Here, one end on the outer circumference P side of the magnet M2 is denoted as an outer end Mc, and the other end on the inner circumference I side of the magnet M2 is denoted as an inner end Md.

  Further, a blocking hole 27 is provided facing the outer end Mc of the magnet M2. The blocking hole 27 is a hole for blocking a magnetic flux path for blocking the magnetic flux from the outer end Mc of the magnet M2.

  The magnet hole 13 includes a magnet insertion hole 28 and a blocking hole 29. The magnet insertion hole 28 extends in the radial direction of the rotor core 1, and the magnet M <b> 3 is inserted into the magnet insertion hole 28. Here, in the magnet M3, one end located on the outer circumference P side is denoted as an outer end Me, and the other end located on the inner circumference I side is denoted as an inner end Mf. Magnets M <b> 2 and M <b> 3 are a pair of magnets, and are arranged in pairs in the circumferential direction of rotor core 1 by being inserted into magnet insertion holes 26 and 28, respectively.

  Further, a blocking hole 29 is provided facing the outer end Me of the magnet M3. The blocking hole 29 is the same as the blocking hole 27.

  The opening width of the blocking hole 27 facing the outer end Mc of the magnet M2 is smaller than the width of the outer end Mc. Therefore, it is possible to suppress the magnet M2 from moving to the blocking hole 27 side. For the same reason, the opening width of the blocking hole 29 facing the outer end Me of the magnet M3 is smaller than the width of the outer end Me.

  A gap 14 is formed between the magnet insertion hole 26 and the magnet insertion hole 28 on the inner circumference I side. The air gap 14 blocks a magnetic flux path generated between the magnet M2 and the magnet M3 (that is, a magnetic flux path generated between the inner end Md and the inner end Mf). The air gap 14 extends in the circumferential direction of the rotor core 1 and is formed in a straight line.

  The opening width of the gap 14 facing the inner end Md of the magnet M2 is smaller than the width of the inner end Md. Therefore, it is possible to suppress the magnet M2 from moving to the gap 14 side. For the same reason, the opening width of the gap 14 facing the inner end Mf of the magnet M3 is smaller than the width of the inner end Mf.

  The magnetic pole 2 is divided into a movable portion 30 and a fixed portion 31 with the gap 14 as a boundary. The movable part 30 is a fan-shaped part arranged between the gap 14 and the outer periphery P, and the fixed part 31 is a part arranged between the gap 14 and the inner circumference I.

  The movable portion 30 is provided with a first fitting hole 15, and the fixed portion 31 is provided with a second fitting hole 16. As shown in FIG. 3, the first fitting hole 15 is inserted with the first enlarged portion B <b> 1 provided on one end side of the non-magnetic bridge B and the second fitting hole 16 is inserted into the first fitting hole 15. The second enlarged portion B2 provided on the other end side of the non-magnetic bridge B is inserted. Thereby, the bridge B is provided on the magnetic pole 2 so as to extend in the radial direction of the rotor core 1 across the gap 14. By providing the bridge B on the magnetic pole 2, the movable part 30 and the fixed part 31 are connected by the bridge B. The first enlarged portion B1 and the second enlarged portion B2 are formed wider than the main body portion B3 of the bridge B.

  Further, since two bridges B are joined to the rotor core 1, two first fitting holes 15 and two second fitting holes 16 are provided in the magnetic pole 2 corresponding to the number of bridges B. Yes. The dimensional accuracy of the bridge B in the radial direction of the rotor core 1 is about ± 10 to 20 μm.

  Here, as shown in FIG. 4A, the radial length of the first fitting hole 15 is larger than the radial length of the first enlarged portion B1. Therefore, a gap is generated in the radial direction between the first fitting hole 15 and the first enlarged portion B1. In FIG. 4A, as this gap, an outer gap 32 located on the outer circumference P side and an inner gap 33 located on the inner circumference I side are shown.

  Further, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 face each other with the inner gap 33 interposed therebetween. The joint surface B4 is configured by a curved surface, and the wall surface 34 is configured by a curved surface corresponding to the joint surface B4. For this reason, when the bonding surface B4 and the wall surface 34 are pressure-bonded, the stress applied to the bonding surface B4 is dispersed throughout the bonding surface B4 and does not concentrate on a specific portion of the bonding surface B4. Therefore, damage to the first enlarged portion B1 can be prevented.

  Further, as shown in FIG. 4B, the radial length of the second fitting hole 16 is larger than the radial length of the second enlarged portion B2. Therefore, a gap is generated in the radial direction between the second fitting hole 16 and the second enlarged portion B2. In FIG. 4B, as this gap, an outer gap 35 located on the outer circumference P side and an inner gap 36 located on the inner circumference I side are shown.

  Further, the joint surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16 face each other with the outer gap 35 interposed therebetween. The joining surface B5 is configured by a curved surface, and the wall surface 37 is configured by a curved surface corresponding to the joining surface B4. The reason why the bonding surface B5 and the wall surface 37 are formed of curved surfaces is the same as that of the bonding surface B4 and the wall surface 34.

  Next, the outer periphery P of the movable part 30 will be described. As shown in FIG. 5, the outer periphery P of the movable portion 30 is located inward in the radial direction by a length r from the reference circle C having the radius of the rotor core 1. For this reason, the outer periphery P of the rotor core 1 is not a perfect circle. The length r is, for example, 20 to 30 μm and is larger than the dimensional accuracy of the bridge B. The outer periphery P of the fixed portion 31 is located on the reference circle C.

  A concave portion 38 is formed on the outer periphery P of the movable portion 30 at one end in the radial direction. The recess 38 is located between the adjustment hole 24 and the blocking hole 27 in the circumferential direction, and is provided in the vicinity of the blocking hole 27 at the right end 40 a of the outer periphery P of the movable portion 30. The recess 38 adjusts the path of the magnetic flux from the magnet M2.

  On the outer periphery P of the movable portion 30, the end surface portion 40 </ b> A between the recess 38 and the right end 40 a is close to the blocking hole 27. Since the space between the end face portion 40A and the blocking hole 27 is a thin portion N, the deformation at the portion N can be facilitated.

  Further, a concave portion 39 (see FIGS. 2 and 3) is formed on the outer periphery P of the movable portion 30 at the other end in the radial direction. The recess 39 is located between the adjustment hole 25 and the blocking hole 29 in the circumferential direction, and is provided in the vicinity of the blocking hole 29 at the left end 40 b of the outer periphery P of the movable portion 30. The recess 39 adjusts the path of the magnetic flux from the magnet M3. Further, a portion between the recess 39 and the left end 40 b is close to the blocking hole 29, and a thin portion is formed between this portion and the blocking hole 29.

  Next, a method of joining the bridge B to the rotor core 1 will be described with reference to FIG. In the rotor core 1 shown in FIG. 6, as shown in FIG. 3, the first enlarged portion B1 of the bridge B is inserted into the first fitting hole 15, and the second enlarged portion B2 of the bridge B is the first enlarged portion B2. 2 are inserted into the two fitting holes 16. In FIG. 6, the detailed configuration of the rotor core 1 shown in FIG. 3 is not shown.

  A rotor shaft S is inserted inside the inner periphery I of the rotor core 1. Since the inner peripheral I side surface of the rotor core 1 and the outer peripheral surface of the rotor shaft S are fitted by a key, the rotor core S is rotated by rotating the rotor shaft S about the central axis A of the rotor shaft S. 1 can be rotated.

  The bridge B is connected to a power line D1 extending from the rotary power feeder R, and the rotor shaft S is connected to a power line D2 extending from the rotary power feeder R. Note that a clip F is attached to the tip of the power line D1, and the power line D1 and the bridge B are connected by the clip F sandwiching the bridge B. Further, the power line D <b> 1 is connected to all the bridges B joined to the rotor core 1.

  The rotary power feeder R can cause a pulse current to flow through the rotor core 1 and the bridge B by the power source E. In FIG. 6, when a pulse current flows between the rotor core 1 and the bridge B, electrons flow from the power line D1 to the power source E, and electrons flow from the power source E to the power line D2. Therefore, the bridge B serves as an anode and the rotor core 1 serves as a cathode.

  Further, the laser sensor G monitors the shape of the outer periphery P by outputting the laser H to the outer periphery P of the rotor core 1 and receiving the laser H reflected by the outer periphery P.

  Here, the power supply E and the laser sensor G are connected to a computer (not shown). Based on the detection result of the laser sensor G, the computer can control the pulse current so as to change the current value and frequency of the pulse current flowing from the power source E, and to switch on / off the pulse current. The computer can also control the rotation of the rotor shaft S.

  When joining the bridge B to the rotor core 1, the computer first rotates the rotor core 1 by rotating the rotor shaft S. The computer rotates the rotor core 1 at about 1000 rpm. Due to the centrifugal force at the time of rotation, the movable portion 30 of the rotor core 1 is moved outward in the radial direction of the rotor core 1. Since the movable portion 30 moves outward in the radial direction due to the centrifugal force during rotation, the inner gap 33 shown in FIG. 4A gradually decreases after the rotation starts.

  Next, a pulse current is supplied from the power source E to the rotor core 1 and the bridge B under the control of the computer. FIG. 7 shows a pattern of a pulse current flowing from the power source E. The current value of the pulse current is about 800 to 1000 A, the frequency is 700 Hz, and the duty ratio is 70%. In FIG. 7, one unit pulse output pattern is composed of two continuous pulses (1) and (2) and a 1 msec pulse pause period. One unit of pulse output pattern is repeated eight times and a pulse rest period of 5.4 msec constitutes one set of pulse output pattern. This set of pulse output patterns is repeated while the pulse current is on.

  When the pulse current shown in FIG. 7 flows through the rotor core 1 and the bridge B, discharge plasma is generated between the rotor core 1 and the bridge B. More specifically, discharge plasma is generated between the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15. Therefore, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are heated. Further, when the bridge B is heated, the first enlarged portion B1 expands.

  Here, specific changes in the size of the inner gap 33 will be described with reference to FIGS. 8A, 8B, 8C, 9A, 9B, and 9C. FIG. 8A shows an enlarged view of the first fitting hole 15 before the rotor core 1 rotates. FIG. 8B shows a state when the rotor core 1 is rotated from the state shown in FIG. 8A. In FIG. 8B, the joint surface B4 of the first enlarged portion B1 is pressure-bonded to the wall surface 34 of the first fitting hole 15 due to the centrifugal force during rotation, and the inner gap 33 disappears.

  When heating by the pulse current is performed from the state shown in FIG. 8B, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are pressed by the centrifugal force during rotation. At the same time, it is heated by a pulse current. Therefore, in FIG. 8B, diffusion of atoms occurs between the joint surface B4 of the enlarged portion B1 and the wall surface 34 of the first fitting hole 15, and the joint surface B4 of the first enlarged portion B1 is the first fitting. It is diffusion bonded to the wall surface 34 of the hole 15. FIG. 8C shows a state where the bonding surface B4 of the first enlarged portion B1 is diffusion bonded to the wall surface 34 of the first fitting hole 15 by heating with the pulse current from the state shown in FIG. 8B. It is shown.

  9A shows a state before the rotor core 1 rotates, and the first fitting hole 15 different from FIG. 8A is enlarged. Here, the inner gap 33 shown in FIG. 9A is larger than the inner gap 33 shown in FIG. 8A. FIG. 9B shows a state when the rotor core 1 is rotated from the state shown in FIG. 9A. In FIG. 9B, the joint surface B <b> 4 of the first enlarged portion B <b> 1 comes close to the wall surface 34 of the first fitting hole 15 due to the centrifugal force during rotation. Therefore, the inner gap 33 shown in FIG. 9A is smaller than the inner gap 33 shown in FIG. 9B.

  When the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are heated by the pulse current from the state shown in FIG. 9B, the first enlarged portion B1 expands. Therefore, the joint surface B4 of the first enlarged portion B1 comes into contact with the wall surface 34 of the first fitting hole 15 and is crimped. That is, in FIG. 9B, the joint surface B4 of the enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are pressed by the centrifugal force during rotation and simultaneously heated by the pulse current. For this reason, diffusion of atoms occurs between the joint surface B4 of the enlarged portion B1 and the wall surface 34 of the first fitting hole 15, and the joint surface B4 of the first enlarged portion B1 becomes the first fitting hole 15. It is diffusion bonded to the wall surface 34. 9C shows a state in which the bonding surface B4 of the first enlarged portion B1 is diffusion bonded to the wall surface 34 of the first fitting hole 15 by heating with the pulse current from the state shown in FIG. 9B. It is shown.

  Thus, not only the centrifugal force during rotation but also the heat generated by the pulse current causes the joint surface B4 of the first enlarged portion B1 to be crimped to the wall surface 34 of the first fitting hole 15. Therefore, in all the bridges B in the rotor core 1, the joining surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 can be securely diffusion-bonded.

  The rotor core 1 continues to rotate even when the bonding surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are being diffusion bonded. Thereby, the movable part 30 moves outward in the radial direction of the rotor core 1 by centrifugal force during rotation. Since the first enlarged portion B1 of the bridge B is diffusion-bonded to the movable portion 30, the bridge B moves outward in the radial direction of the rotor core 1 together with the movable portion 30. That is, the second enlarged portion B <b> 2 moves outward in the radial direction of the rotor core 1. Therefore, the joint surface B5 of the second enlarged portion B2 is pressed against the wall surface 37 of the second fitting hole 16, and the outer gap 35 disappears. Further, the plasma caused by the pulse current is generated between the joint surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16, whereby the joint surface B5 and the wall surface 37 are heated. . For this reason, the bonding surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16 are diffusion bonded.

  As described above, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are undergoing diffusion joining and at the same time the joint surface B5 of the second enlarged portion B2 and the second fitting. When the wall surface 37 of the hole 16 is being diffusion bonded, the movable portion 30 is heated and softened as the bridge B is heated. And the outer periphery P of the movable part 30 reaches the reference | standard circle C with progress of time.

  The laser sensor G monitors that the outer periphery P of the movable part 30 has reached the reference circle C by outputting the laser H to the outer periphery P of the rotor core 1 and receiving the laser H reflected by the outer periphery P. Based on the monitoring result indicating that the outer periphery P has reached the reference circle C, the computer sufficiently bonds the bonding surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 by diffusion bonding. It is determined that a sufficient time has passed for the bonding surface B5 of the second enlarged portion B2 and the wall surface 34 of the second fitting hole 16 to be sufficiently bonded by diffusion bonding. Based on this determination, the computer turns off the pulse current supplied by the power source E. Further, the computer stops the rotation of the rotor shaft S based on the monitoring result indicating that the outer periphery P has reached the reference circle C. Thereby, rotation of the rotor core 1 stops.

  After the rotor core 1 stops rotating, the rotor core 1 can be generated by inserting the magnet M1 into the magnet insertion hole 21, the magnet M2 into the magnet insertion hole 26, and the magnet M3 into the magnet insertion hole 28, respectively. As shown in FIG. 10, in the generated rotor core 1, the first enlarged portion B1 of the bridge B is joined to the wall surface of the first fitting hole 15, and the second enlarged portion B2 of the bridge B is obtained. Is joined to the wall surface of the second fitting hole 16. In addition, since the outer periphery P of the movable portion 30 reaches the reference circle C, the outer periphery P of the rotor core 1 has a perfect circle shape except for the concave portions 38 and 39.

  By the way, in the connection method of the bridge and the rotor core according to Patent Document 1, after the rotor core is heated and thermally expanded, the bridge is fitted into the fitting hole, and after the bridge is fitted, the rotor core is cooled to shrink the fitting hole. By doing so, the bridge is connected to the rotor core. Here, as shown in FIG. 11, the wall surface 100a of the fitting hole 100 of the rotor core has a saw blade shape due to the influence of cutting. Therefore, when the cooling cycle is repeated in a state where the rotor core is mounted on the vehicle, the bridge B is drawn out to the rotation axis direction side of the rotor core. Therefore, the fastening force between the bridge B and the rotor core 1 cannot be secured sufficiently.

  On the other hand, in the manufacturing method according to the embodiment, the movable portion 30 is moved outward in the radial direction by the centrifugal force during rotation. Therefore, a crimping force that crimps the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 is applied. Further, by supplying a pulse current to the bridge B and heating the bridge B, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are heated. The joint surface B4 of the first enlarged portion B1 is generated by the pressure generated by the centrifugal force applied to the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 and the heat generated by the pulse current. Then, diffusion of atoms occurs between the first fitting hole 15 and the wall surface 34 of the first fitting hole 15, and the bonding surface B 4 of the first enlarged portion B 1 is diffusion bonded to the wall surface 34 of the first fitting hole 15. The joining surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16 are also diffusion joined by the same mechanism. Therefore, the joint surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 and the joint surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16 are sufficiently crimped. Thus, the fastening force between the bridge B and the rotor core 1 can be sufficiently secured.

  In the manufacturing method according to the embodiment, a pulse current of 800 to 1000 A is used to heat the bridge B. When a steady current having the same current value is used to heat the bridge B, excessive plasma discharge occurs between the wall surface 34 of the first fitting hole 15 and the joint surface B4 of the first enlarged portion B1. As a result, the wall surface 34 of the first fitting hole 15 and the bonding surface B4 of the first enlarged portion B1 are immediately melted, and the wall surface 34 and the bonding surface B4 are lost. A similar phenomenon occurs on the joint surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16. Further, since the rotor core 1 is excessively heated, the insulating film of the rotor core 1 is also deteriorated.

  In the manufacturing method according to the embodiment, a pulse current of 800 to 1000 A is used to heat the bridge B. Therefore, it is possible to prevent the wall surface 34 and the joint surface B4 from being lost or the insulating film of the rotor core 1 from being deteriorated due to excessive heating. Further, since heating is performed at a high current value, diffusion bonding can be performed in a short time. Further, the computer can control the degree of heating by changing the current value and frequency of the pulse current according to the position of the outer periphery P.

  Further, in the manufacturing method according to the embodiment, the outer periphery P of the movable portion 30 is located inside the reference circle C having the radius of the rotor core 1. With this configuration, even if the movable part 30 moves outward in the radial direction, the outer periphery of the movable part 30 can be prevented from exceeding the reference circle C of the outer periphery P of the rotor core 1, so that the rotor core 1 interferes with the stator core. No longer.

  Further, in the manufacturing method according to the embodiment, the computer stops energization of the pulse current to the bridge B when the outer periphery of the movable part 30 reaches the reference circle during diffusion bonding. As the bridge B is heated, the movable part 30 is also heated and softened, so that the outer periphery of the movable part 30 reaches the reference circle C as time passes. Then, by monitoring that the outer periphery of the movable portion 30 has reached the reference circle C, the joining surface B4 of the first enlarged portion B1 is sufficiently crimped to the wall surface 34 of the first fitting hole 15 by diffusion joining. It can be determined that a sufficient time has elapsed for the bonding surface B5 of the second enlarged portion B2 to be sufficiently crimped to the wall surface 37 of the second fitting hole 16 by diffusion bonding. Accordingly, the bonding surface B4 of the first enlarged portion B1 and the wall surface 34 of the first fitting hole 15 are crimped, and the bonding surface B5 of the second enlarged portion B2 and the wall surface 37 of the second fitting hole 16 are Therefore, the bridge B and the rotor core 1 can be securely fastened.

  The length of the bridge B in the radial direction differs depending on the bridge B by the dimensional accuracy. Therefore, in the rotor core 1 before rotation, when the first enlarged portion B1 of the bridge B is inserted into the first fitting hole 15 and the second enlarged portion B2 is inserted into the second fitting hole 16, Variations in size occur in the gap 33 and the outer gap 35. However, the difference in length r between the outer diameter of the reference circle C having the radius of the rotor core 1 and the outer diameter of the movable part 30 is larger than the dimensional accuracy of the bridge B. Therefore, even in the first fitting hole 15 having the largest inner gap 33 in the rotor core 1, when the outer periphery P reaches the reference circle C, the joint surface B4 of the first enlarged portion B1 is the first fitting hole. Diffusion bonded to 15 wall holes. Similarly, also in the second fitting hole 16 having the largest outer gap 35 in the rotor core 1, when the outer periphery P reaches the reference circle C, the joint surface B5 of the second enlarged portion B2 is the second fitting. It is diffusion bonded to the wall hole of the hole 16. For this reason, the fastening force between the bridge B and the rotor core 1 can be sufficiently secured in all the bridges B of the rotor core 1.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, the current value and frequency of the pulse current can be appropriately changed according to the situation.

DESCRIPTION OF SYMBOLS 1 Rotor core 2, 3, 4, 5, 6, 7, 8, 9 Magnetic pole 11, 12, 13 Magnet hole 14 Space | gap 15 1st fitting hole 16 2nd fitting hole 30 Movable part 31 Fixed part 34, 37 Wall B Bridge
B1 1st expansion part B2 2nd expansion part I Inner circumference P Outer circumference C Reference circle

Claims (3)

A gap formed between the outer periphery and the inner periphery of the rotor core in the radial direction of the rotor core;
A movable part located on the outer side of the gap in the radial direction of the rotor core;
A fixing portion located on the inner side of the gap in the radial direction of the rotor core;
A first enlarged portion provided on one end side and inserted in a first fitting hole formed in the movable portion, and a second fit provided on the other end side and formed on the fixed portion. A bridge having a second enlarged portion inserted into the joint hole;
A rotor core comprising:
By moving the movable part outward in the radial direction by centrifugal force when the rotor core is rotated, the wall surfaces of the first and second fitting holes and the first and second enlarged parts And heating the bridge by applying a pulse current to the bridge, and diffusion bonding the first and second enlarged portions to the wall surfaces of the first and second fitting holes. Let
A method for manufacturing a rotor core. The outer periphery of the movable part is located inside a reference circle having a radius of the rotor core,
The method for manufacturing a rotor core according to claim 1. During the diffusion bonding, when the outer periphery of the movable part reaches the reference circle, the energization of the pulse current to the bridge is stopped.
A method for manufacturing a rotor core according to claim 2.

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