JP2024159330A - Rotor manufacturing method - Google Patents

Abstract

To prevent a gate position from being shifted from a slot position.SOLUTION: A rotor 10 includes a plurality of bonded magnets 12 and a rotor core 14. The rotor core is formed by stacking a plurality of core sheets 18 each having a plurality of slots 22 that respectively accommodate the plurality of bonded magnets, and has a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to the stacking position. The plurality of core sheets include a core sheet 18A having a plurality of gates 26 respectively communicating with the plurality of slots. Of a mold 34 having a first die 36 and a second die 38, the first die has a runner 46. The runner is formed in an annular shape along the circumferential direction of the rotor core, and when the first die and the second die are clamped, communicates with each gate, and a magnet material is injected into each slot through each gate.SELECTED DRAWING: Figure 6

Description

The technology disclosed herein relates to a method for manufacturing a rotor.

Patent Document 1 discloses a rotor that is applied to an interior permanent magnet synchronous motor (IPM). The rotor includes a plurality of bonded magnets and a rotor core. The rotor core is formed by laminating a plurality of core sheets each having a plurality of slots that each accommodate a plurality of bonded magnets.

The manufacturing method of this rotor includes an inserting process in which a rotor core is inserted into the second die of a mold having a first die and a second die, a clamping process in which the first die and the second die are clamped together, and a molding process in which a magnet material that will become a bonded magnet is injected into multiple slots and a bonded magnet is molded from the magnet material.

The first mold has multiple runners extending radially, and an opening is formed at the tip of each runner. During the molding process, magnet material is injected from the runners through the openings into each slot.

JP 2017-34763 A

There are rotor cores with a skew structure in which multiple core sheets are shifted in the circumferential direction depending on the stacking position. Here, if there is variation in the thickness of the multiple core sheets, the number of core sheets is adjusted to make the axial length of the rotor core the desired length.

However, in a rotor core having a skew structure, when the number of core sheets is adjusted, the circumferential position of the core sheets located at the ends of the rotor core changes depending on the number of core sheets. For this reason, if a gate is formed in the runner, the position of the gate may become misaligned with respect to the position of the slot. In this case, there is a risk of affecting the quality of the bonded magnet formed from the magnet material. Therefore, in a rotor core having a skew structure, it is desirable to be able to avoid the position of the gate becoming misaligned with respect to the position of the slot, even when the number of core sheets is adjusted.

The technology disclosed herein has been developed in consideration of the above problems, and aims to provide a rotor manufacturing method that can adjust the number of core sheets in a rotor core having a skew structure, thereby preventing the gate position from being misaligned with the slot position, even when the circumferential position of the core sheets located at the end of the rotor core changes depending on the number of core sheets.

In order to solve the above problem, the manufacturing method of a rotor according to the first aspect of the technology disclosed herein is a manufacturing method of a rotor (10) having a rotor core (14) formed by stacking a plurality of bonded magnets (12) and core sheets (18) each having a plurality of slots (22) for accommodating the plurality of bonded magnets, the rotor core (14) having a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to the stacking position, the manufacturing method of the rotor (10) includes an inserting step of inserting the rotor core into the second die of a mold (34) having a first die (36) and a second die (38); The method includes a mold clamping process for clamping the second mold, and a molding process for injecting the magnet material that will become the bonded magnet into the slots and molding the bonded magnet from the magnet material, and the core sheets include a core sheet (18A) having a plurality of gates (26) that respectively communicate with the plurality of slots, and the first mold is formed in an annular shape along the circumferential direction of the rotor core, and has a runner (46) that communicates with each of the gates and injects the magnet material into each of the slots through each of the gates when the first mold and the second mold are clamped.

In order to solve the above problem, the rotor according to the second aspect of the disclosed technology has a rotor core (14) formed by stacking a plurality of bonded magnets (12) and core sheets (18) each having a plurality of slots (22) that respectively accommodate the bonded magnets, and has a skew structure in which the core sheets are shifted in the circumferential direction according to their stacking positions, and the core sheets include a core sheet (18A) having a plurality of gates (26) that each communicate with the slots.

According to the rotor manufacturing method according to the technology disclosed herein, in a rotor core having a skew structure, by adjusting the number of core sheets, it is possible to avoid misalignment of the gate position relative to the slot position even if the circumferential position of the core sheets located at the end of the rotor core changes depending on the number of core sheets.

FIG. 2 is a perspective view of a rotor according to one embodiment of the disclosed technology; FIG. 2 is a perspective view of a core sheet according to one embodiment of the technology of the present disclosure. FIG. 13 is a perspective view of another core sheet according to an embodiment of the technology of the present disclosure. FIG. 1 is a perspective view of a rotor core according to an embodiment of the technology of the present disclosure. FIG. 2 is an enlarged perspective view of a rotor core according to an embodiment of the technology of the present disclosure. 1 is a vertical cross-sectional view showing a schematic diagram of a mold according to an embodiment of the technology of the present disclosure. FIG. 2 is a perspective view showing a positional relationship between a rotor core and a runner according to an embodiment of the technology of the present disclosure. 1 is a longitudinal cross-sectional view illustrating a state in which one recess among a plurality of recesses is sealed by a first sealing portion according to an embodiment of the technique of the present disclosure. FIG. 5A to 5C are explanatory diagrams illustrating the first half of the process of a rotor manufacturing method according to an embodiment of the technology of the present disclosure. 10A to 10C are explanatory diagrams illustrating a latter half of a process of a rotor manufacturing method according to an embodiment of the technology of the present disclosure.

Below, one embodiment of the technology disclosed herein is described.

First, we will explain the rotor 10 according to this embodiment.

The rotor 10 according to this embodiment shown in FIG. 1 is a rotor applied to an IPM motor. The rotor 10 has a plurality of bonded magnets 12, a rotor core 14, and a shaft 16. The rotor core 14 has a plurality of core sheets 18. Each core sheet 18 is formed in a disk shape. The rotor core 14 is formed by stacking a plurality of core sheets 18. The core sheets 18 are formed, for example, from electromagnetic steel sheets.

An insertion hole 20 is formed in the center of each core sheet 18. The insertion hole 20 penetrates the core sheet 18 in the thickness direction. The thickness direction of the core sheet 18 is the same as the axial direction of the rotor core 14. The shaft 16 is press-fitted into the insertion hole 20 of each core sheet 18.

A plurality of slots 22 are formed radially outward of the insertion hole 20 in each core sheet 18. The plurality of slots 22 are formed around the insertion hole 20. The plurality of slots 22 are formed in a line in the circumferential direction of the core sheet 18. Each slot 22 penetrates the core sheet 18 in the thickness direction. Each slot 22 is formed in a U-shape when viewed in the thickness direction of the core sheet 18. The slot 22 is formed so that the lower part of the U-shape is located on the insertion hole 20 side and the upper part of the U-shape is located on the outer periphery side of the core sheet 18. A bond magnet 12 is accommodated in each slot 22. The shape of the slot 22 may be a shape other than a U-shape, such as an I-shape.

The multiple core sheets 18 forming the rotor core 14 include two types of core sheets: core sheet 18A shown in FIG. 2 and core sheet 18B shown in FIG. 3. Both core sheet 18A and core sheet 18B have multiple recesses 24. The multiple recesses 24 are formed on the inner circumferential surface 20A of the insertion hole 20. In other words, the multiple recesses 24 are each formed in a concave shape that opens to the inner circumferential surface 20A. The multiple recesses 24 are formed side by side in the circumferential direction of the core sheet 18. Each recess 24 penetrates the core sheet 18 in the plate thickness direction. The multiple recesses 24 are parts that play a role in assisting the deformation of the inner circumferential surface 20A when the shaft 16 is pressed into the insertion hole 20.

As shown in FIG. 2, the core sheet 18A has a plurality of gates 26. Each gate 26 is formed for each slot 22. Each gate 26 is connected to each slot 22. Specifically, each gate 26 is formed in a groove shape extending from the center of each slot 22 (i.e., the lower part of the U-shape of each slot 22) toward the insertion hole 20. Each gate 26 penetrates the core sheet 18 in the plate thickness direction. On the other hand, the core sheet 18B shown in FIG. 3 does not have a gate 26.

As shown in Figures 4 and 5, core sheets 18A are used for some of the core sheets 18 located at one axial end, and core sheets 18B are used for the remaining core sheets 18. The rotor core 14 has a skew structure in which the multiple core sheets 18 are shifted in the circumferential direction depending on the stacking position.

In a rotor core 14 having a skewed structure, the slots 22 formed in the core sheets 18 are connected in the axial direction of the rotor core 14 in a skewed state. Similarly, the recesses 24 formed in the core sheets 18 are connected in the axial direction of the rotor core 14 in a skewed state, and the gates 26 formed in the core sheets 18A are connected in the axial direction of the rotor core 14 within the range of the core sheets 18A in a skewed state.

Next, we will explain the molding device 30 used in the manufacturing method of the rotor 10 according to this embodiment.

As shown in FIG. 6, a molding device 30 is used in the manufacturing method of the rotor 10 according to this embodiment. The molding device 30 includes an injection facility 32 and a mold 34. The mold 34 includes a first mold 36 and a second mold 38. As an example, the first mold 36 is an upper mold, and the second mold 38 is a lower mold. A boundary 40 indicates the boundary between the first mold 36 and the second mold 38. The second mold 38 has a cavity 42 into which the rotor core 14 is inserted. The cavity 42 is formed by a space similar to the outer shape of the rotor core 14. The second mold 38 also has an orientation magnetic field body 44. The orientation magnetic field body 44 has a magnet for orientation. The orientation magnetic field body 44 is arranged around the cavity 42.

The first die 36 has a runner 46 and a sprue 48. The runner 46 and the sprue 48 are configured separately from the die body of the first die 36. The runner 46 is formed in an annular shape along the circumferential direction of the rotor core 14. The runner 46 has an annular flow passage 46A formed in an annular shape along the circumferential direction of the rotor core 14.

The sprue 48 is connected to a portion of the runner 46 in the circumferential direction. The injection equipment 32 is connected to the sprue 48. The sprue 48 has a communication flow path 48A that connects the annular flow path 46A formed in the runner 46 to an injection port formed in the injection equipment 32.

The first die 36 has a first sealing portion 52 and a second sealing portion 54. The first sealing portion 52 is formed by a region of the surface of the first die 36 facing the second die 38 that is more inward than the runner 46. The first sealing portion 52 is formed at a position corresponding to the multiple recesses 24. The first sealing portion 52 is formed in an annular shape along the circumferential direction of the rotor core 14. The first sealing portion 52 seals the multiple recesses 24 when the first die 36 and the second die 38 are clamped. The first sealing portion 52 is an example of a "sealing portion" in the technology disclosed herein.

The second sealing portion 54 is formed by a region on the surface of the first die 36 facing the second die 38 that is more inward than the first sealing portion 52. The second sealing portion 54 is formed at a position corresponding to the insertion hole 20. The second sealing portion 54 is formed in a circular shape. The second sealing portion 54 seals the insertion hole 20 when the first die 36 and the second die 38 are clamped.

Figure 7 shows the positional relationship between the rotor core 14 and the runner 46. As shown in Figures 6 and 7, the runner 46 communicates with each gate 26 when the first mold 36 and the second mold 38 are clamped. The injection equipment 32 injects the magnet material that will become the bonded magnet 12. The magnet material is a material in which magnet powder is mixed with binder resin. The binder resin is formed, for example, from a thermoplastic resin, and the magnet powder is formed, for example, from rare earth anisotropic magnet powder. The magnet material injected from the injection equipment 32 is injected into each slot 22 through the sprue 48, the runner 46, and the gate 26.

The runner 46 is formed with a plurality of protruding portions 50. The protruding portions 50 are formed at intervals in the circumferential direction of the runner 46. The protruding portions 50 protrude on the opposite side to the second die 38. The protruding portions 50 are used when separating the molded product, which is molded integrally with the bonded magnets 12 by the runner 46 and the sprue 48, from the bonded magnets 12 using a jig. Specifically, the jig is shaped to cover the entire runner 46 including the protruding portions 50, and engages with the protruding portions 50. The jig is then rotated around the axis of the rotor core 14, whereby the molded product is separated from the bonded magnets 12.

Figure 8 shows a schematic diagram of one of the recesses 24 being sealed by the first sealing portion 52. The mold 34 has a nest 56 that is inserted into the recesses 24 formed in the core sheets 18. Because the rotor core 14 has a skew structure, a gap 58 is generated between the nest 56 and the side of the recess 24 formed in the core sheet 18A located at the end of the rotor core 14, but the entire recess 24 including the gap 58 is sealed by the first sealing portion 52.

Next, we will explain the manufacturing method for the rotor 10 according to this embodiment.

As shown in Figures 9 and 10, the manufacturing method for the rotor 10 according to this embodiment includes a preparation process A, an insert process B, a mold clamping process C, a molding process D, a mold opening process E, and a removal process F.

In the preparation process A, the first die 36 and the second die 38 are opened. In the insertion process B, the rotor core 14 is inserted into the second die 38. In the clamping process C, the first die 36 and the second die 38 are clamped. When the first die 36 and the second die 38 are clamped, the multiple recesses 24 are sealed by the first sealing portion 52, and the insertion hole 20 is sealed by the second sealing portion 54 (see FIG. 6).

In molding process D, the magnet material that will become the bonded magnet 12 is injected from the injection equipment 32. The magnet material injected from the injection equipment 32 is injected into each slot 22 through the sprue 48, runner 46, and gate 26. The magnetic powder contained in the magnet material injected into each slot 22 is aligned by the alignment magnetic field body 44. The binder resin contained in the magnet material solidifies, and the bonded magnet 12 is formed from the magnet material. The bonded magnet 12 and the rotor core 14 are then integrated together.

In the mold opening process E, the first mold 36 and the second mold 38 are opened. In the removal process F, the rotor core 14, the runner 46, and the sprue 48 are removed from the second mold 38. The runner 46 and the sprue 48 removed from the second mold 38 are demagnetized. In addition, the molded product formed integrally with the multiple bonded magnets 12 by the runner 46 and the sprue 48 is separated from the multiple bonded magnets 12 using a jig. Then, although not shown, the shaft 16 (see FIG. 1) is pressed into the insertion hole 20. Through the above processes, the rotor 10 shown in FIG. 1 is obtained.

Next, we will explain the effects of this embodiment.

In this embodiment, core sheet 18A of the multiple core sheets 18 has multiple gates 26 that each communicate with multiple slots 22 (see Figures 2 and 5). In other words, the gates 26 are formed in the core sheet 18, not in the runner 46. Therefore, in a rotor core 14 having a skew structure, by adjusting the number of core sheets 18, it is possible to prevent the position of the gate 26 from being misaligned with the position of the slot 22, even if the circumferential position of the core sheet 18A located at the end of the rotor core 14 changes depending on the number of core sheets 18.

In addition, the gate 26 is connected to the center of the slot 22. Therefore, the moldability of the bonded magnet 12 can be improved compared to, for example, a case in which the gate 26 is connected to a position offset from the center of the slot 22.

The runner 46 is formed in an annular shape along the circumferential direction of the rotor core 14, and communicates with each gate 26 when the first die 36 and the second die 38 are clamped (see FIG. 6). Therefore, even if the circumferential position of the core sheet 18A located at the end of the rotor core 14 (and thus the position of each gate 26 of the core sheet 18A) changes depending on the number of core sheets 18, the runner 46 can maintain communication with each gate 26.

The core sheet 18 has an insertion hole 20 into which the shaft 16 is inserted and a number of recesses 24 formed on the inner circumferential surface 20A of the insertion hole 20, and the first die 36 has a first sealing portion 52 that seals the multiple recesses 24 when the first die 36 and the second die 38 are clamped (see FIG. 6). Here, the first sealing portion 52 is formed in an annular shape along the circumferential direction of the rotor core 14. Therefore, even if the circumferential position of the core sheet 18A located at the end of the rotor core 14 (and thus the position of each recess 24 of the core sheet 18A) changes depending on the number of core sheets 18, the first sealing portion 52 can maintain the state in which each recess 24 is sealed.

In particular, because the rotor core 14 has a skew structure, even if a gap 58 (see FIG. 8) occurs between the side of the recess 24 formed in the core sheet 18A located at the end of the rotor core 14 and the insert 56, the entire recess 24 including the gap 58 can be kept sealed by the first sealing portion 52.

The configuration in which the multiple recesses 24 formed on the inner circumferential surface 20A of the insertion hole 20 are sealed by the first sealing portion 52 may also be applied to rotor cores that do not have a skew structure.

Although the present embodiment has been described above, the present invention is not limited to the above, and can of course be modified in various ways without departing from the spirit of the present invention.

The features of this embodiment will be described below.
(Appendix 1)
A plurality of bonded magnets (12);
a rotor core (14) formed by stacking a plurality of core sheets (18) each having a plurality of slots (22) for accommodating the plurality of bonded magnets, the rotor core having a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to their stacking positions;
A method for manufacturing a rotor (10) having
an inserting step of inserting the rotor core into the second die of a die (34) having a first die (36) and a second die (38);
a mold clamping step of clamping the first mold and the second mold;
a molding step of injecting a magnet material to be the bonded magnet into the plurality of slots and molding the bonded magnet from the magnet material;
Equipped with
The plurality of core sheets include a core sheet (18A) having a plurality of gates (26) respectively communicating with the plurality of slots;
the first die is formed in an annular shape along the circumferential direction of the rotor core, and has a runner (46) that communicates with each of the gates and injects the magnet material into each of the slots through each of the gates when the first die and the second die are clamped;
A method for manufacturing a rotor.
(Appendix 2)
The core sheet has an insertion hole (20) into which a shaft is inserted, and a plurality of recesses (24) formed on an inner peripheral surface (20A) of the insertion hole,
The first die is formed in an annular shape along the circumferential direction of the rotor core, and has a sealing portion (52) that seals the multiple recesses when the first die and the second die are clamped.
2. A method for manufacturing the rotor described in claim 1.
(Appendix 3)
The gate communicates with a central portion of the slot.
A method for manufacturing a rotor according to claim 1 or 2.
(Appendix 4)
A plurality of bonded magnets (12);
a rotor core (14) formed by stacking a plurality of core sheets (18) each having a plurality of slots (22) for accommodating the plurality of bonded magnets, the rotor core having a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to their stacking positions;
having
The plurality of core sheets includes a core sheet (18A) having a plurality of gates (26) respectively communicating with the plurality of slots.
Rotor (10).

10...rotor, 12...bonded magnet, 14...rotor core, 16...shaft, 18...core sheet, 20...insertion hole, 20A...inner surface, 22...slot, 24...recess, 26...gate, 30...molding device, 32...injection equipment, 34...mold, 36...first mold, 38...second mold, 40...boundary, 42...cavity, 44...alignment magnetic field body, 46...runner, 46A...annular flow path, 48...spur, 48A...communicating flow path, 50...projection, 52...first sealing portion, 54...second sealing portion, 56...nesting, 58...gap

Claims (4)

A plurality of bonded magnets (12);
a rotor core (14) formed by stacking a plurality of core sheets (18) each having a plurality of slots (22) for accommodating the plurality of bonded magnets, the rotor core having a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to their stacking positions;
A method for manufacturing a rotor (10) having
an inserting step of inserting the rotor core into the second die of a die (34) having a first die (36) and a second die (38);
a mold clamping step of clamping the first mold and the second mold;
a molding step of injecting a magnet material to be the bonded magnet into the plurality of slots and molding the bonded magnet from the magnet material;
Equipped with
The plurality of core sheets include a core sheet (18A) having a plurality of gates (26) respectively communicating with the plurality of slots;
the first die is formed in an annular shape along the circumferential direction of the rotor core, and has a runner (46) that communicates with each of the gates and injects the magnet material into each of the slots through each of the gates when the first die and the second die are clamped;
A method for manufacturing a rotor. The core sheet has an insertion hole (20) into which a shaft is inserted, and a plurality of recesses (24) formed on an inner peripheral surface (20A) of the insertion hole,
The first die is formed in an annular shape along the circumferential direction of the rotor core, and has a sealing portion (52) that seals the multiple recesses when the first die and the second die are clamped.
A method for manufacturing the rotor according to claim 1 . The gate communicates with a central portion of the slot.
A method for manufacturing a rotor according to claim 1 or 2. A plurality of bonded magnets (12);
a rotor core (14) formed by stacking a plurality of core sheets (18) each having a plurality of slots (22) for accommodating the plurality of bonded magnets, the rotor core having a skew structure in which the plurality of core sheets are shifted in the circumferential direction according to their stacking positions;
having
The plurality of core sheets includes a core sheet (18A) having a plurality of gates (26) respectively communicating with the plurality of slots.
Rotor (10).