Method for manufacturing a rotor

Abstract

To provide a method of manufacturing rotor capable of suppressing heat generation during operation of a cage-type induction motor.SOLUTION: A method of manufacturing a rotor equipped with a first short-circuit ring disposed on one end side in a direction along a rotation axis of a rotor core, a second short-circuit ring disposed oppositely to the first short-circuit ring across the rotor core, and a plurality of rod-shaped portions inserted in the rotor core to connect the first short-circuit ring and the second short-circuit ring, includes: a molding step of pressing a conductive material lump to mold the first short-circuit ring and the rod-shaped portion extending from the first short-circuit ring; an insertion step of inserting the rotor core in the rod-shaped portion from a free end portion side of the rod-shaped portion; and a machining step of providing the second short-circuit ring at the free end portion of the rod-shaped portion after the rotor core is inserted.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a rotor.

Background Art

[0002] Conventionally, a squirrel-cage induction motor having a rotor in which a short-circuit ring disposed at both ends of a rotor core and a rod-shaped portion connecting the short-circuit rings are combined in a cage shape is known. As a rotor in such a squirrel-cage induction motor, an embodiment having a short-circuit ring and a rod-shaped portion formed by casting is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the rod-shaped portion and the short-circuit ring are formed by casting, cavities called casting nests may be formed in the rod-shaped portion and the short-circuit ring. Since the casting nests increase the electrical resistance, the electrical resistance of the rod-shaped portion and the short-circuit ring is increased. Therefore, when a squirrel-cage induction motor having a rotor formed by casting the rod-shaped portion and the short-circuit ring is operated, it is conceivable that the rotor generates heat due to the casting nests.

[0005] Therefore, an object of the invention disclosed in this specification is to provide a manufacturing method capable of obtaining a rotor capable of suppressing heat generation during operation of a squirrel-cage induction motor.

Means for Solving the Problems

[0006] The manufacturing method of the rotor disclosed in this specification is a manufacturing method of a rotor including a first short-circuit ring disposed on one end side in the direction along the rotation axis of the rotor core, a second short-circuit ring disposed to face the first short-circuit ring with the rotor core therebetween, and a plurality of rod-shaped portions inserted through the rotor core to connect the first short-circuit ring and the second short-circuit ring, the method including a forming step of pressing a conductive material mass to form the first short-circuit ring and the rod-shaped portion extending from the first short-circuit ring, an inserting step of inserting the rotor core into the rod-shaped portion from the free end side of the rod-shaped portion, and a processing step of providing the second short-circuit ring at the free end of the rod-shaped portion after the rotor core is inserted.

[0007] In the manufacturing method of the rotor described above, it is possible to adopt an aspect in which the first short-circuit ring and the rod-shaped portion are formed by pressing the side wall of a conductive cylindrical material mass.

[0008] Also, in the manufacturing method of the rotor described above, the forming step can include a first step of pressing a conductive solid columnar material mass to form an intermediate body having a bottom plate portion and an annular wall portion, a second step of removing the bottom plate portion to form the first short-circuit ring, and a third step of processing the annular wall portion into a comb shape to form the rod-shaped portion.

[0009] In the manufacturing method of the rotor described above, the third step can be an aspect of removing a removal portion set adjacent to the portion formed as the rod-shaped portion.

[0010] The removal portion can be removed by cutting with a cutting tool.

[0011] In the manufacturing method of the rotor described above, the step of providing the second short-circuit ring can be an aspect of bending the free end protruding from the rotor core in the circumferential direction and providing the second short-circuit ring with the adjacent free ends in contact with each other in the circumferential direction.

[0012] Furthermore, in the method for manufacturing the rotor described above, the step of providing the second short-circuit ring may be configured such that a plate body having conductivity is placed in contact with the free end protruding from the rotor core, and the contact portion between the free end and the plate body is welded.

Advantages of the Invention

[0013] The invention disclosed in this specification can provide a manufacturing method capable of obtaining a rotor capable of suppressing heat generation during the operation of a cage-type induction motor.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be illustrated so as to exactly match the actual ones. Also, depending on the drawings, details may be omitted. Furthermore, the scales of the elements depicted in each figure may be different.

[0016] (First Embodiment) [Configuration of Cage-Type Induction Motor] First, with reference to FIG. 1, the schematic configuration of a cage-type induction motor 1 incorporating a rotor 4 manufactured by the manufacturing method of the present embodiment will be described. The cage-type induction motor 1 is used, for example, as a driving motor for hybrid vehicles equipped with an engine and a driving motor for running as driving sources of a vehicle, electric vehicles such as electric cars and fuel cell vehicles, or as a driving source for pumps and fans.

[0017] The cage-type induction motor 1 includes an annular stator 3 provided in a case 2 and a rotor 4 disposed radially opposite to the stator 3 within the stator 3. The rotor 4 is rotatably provided within the stator 3 around a rotation axis AX. The rotor 4 includes a first short-circuit ring 6 disposed on one end side in the direction along the rotation axis AX of the rotor core 5, and a second short-circuit ring 7 disposed opposite to the first short-circuit ring 6 with the rotor core 5 interposed therebetween. Further, the rotor 4 includes a plurality of rod-shaped portions 8 connecting the first short-circuit ring 6 and the second short-circuit ring 7. A rotation shaft member 9 is provided at the central portion of the rotor core 5, and this rotation shaft member 9 is supported by the case 2 by a first bearing member 10a provided on one end side of the rotor 4 and a second bearing member 10b provided on the other end side of the rotor 4. Thereby, the rotor 4 can rotate. In the present embodiment, as shown in FIG. 3(H), the rod-shaped portions 8 are arranged in the circumferential direction, and the number thereof is 12, but the number of the rod-shaped portions 8 is not limited thereto and may be other numbers.

[0018] [Manufacturing Method] Hereinafter, the manufacturing method of the rotor 4 will be described. [Extrusion Molding Step] The manufacturing method of the rotor 4 includes an extrusion molding process. FIG. 2 shows a punch 20 used in the extrusion molding process. The punch 20 is a pin-shaped tool, and a cylindrical guide portion 21 is provided at its tip. Further, the punch 20 is provided with a stepped portion 22 having a diameter larger than that of the guide portion 21 on the base end side of the guide portion 211. The height of the stepped portion 22 is set corresponding to the thickness of the first short-circuit ring 6. The punch 20 includes a plurality of protruding portions 23 protruding radially on the base end side of the stepped portion 22, and a groove-shaped portion 24 formed between the protruding portions 23 adjacent to each other in the circumferential direction. The protruding portions 23 and the groove-shaped portion 24 are alternately provided along the circumferential direction, and both extend along the longitudinal direction of the punch 20. As will be described in detail later, a part of the material mass 40 (see FIG. 3(A) etc.) flows into the groove-shaped portion 24, whereby the rod-shaped portion 8 (see FIG. 1) is formed.

[0019] Next, referring to FIG. 3(A), the extrusion molding is performed using the punch 20 and the die 30. The die 30 includes a first storage recess 31 into which the guide portion 21 provided in the punch 20 is inserted, and a second storage recess 32 into which the portion of the punch 20 where the stepped portion 22, the protruding portions 23, and the groove-shaped portion 24 are formed is inserted. The inner diameter of the second storage recess 32 is larger than the inner diameter of the first storage recess 31, and is set to a dimension such that the protruding portions 23 of the punch 20 can be in sliding contact.

[0020] The operator first sets a cylindrical material mass 40 having conductivity in the second storage recess 32 of such a die 30. The material mass 40 is cylindrical as shown in FIGS. 3(B) and 3(C). The material mass 40 in the present embodiment is formed of pure copper (tough pitch copper), but may contain a small amount of impurities. Further, the material mass 40 can be appropriately selected from materials having conductivity and workability capable of plastic deformation. In addition to copper, for example, it can be appropriately selected from aluminum, gold, silver, copper alloys, aluminum alloys, etc.

[0021] As shown in Fig. 3(A), the operator sets the material block 40 in the second storage recess 32 of the die 30, and then inserts the punch 20 into the die 30. Then, as shown by the arrow 15a in Fig. 3(D), the operator moves the punch 20 to press the material block 40. As a result, the material block 40 is expanded in the direction opposite to the pressing direction of the punch 20 as shown by the arrow 15b in Fig. 3(F), and flows into the space formed between the punch 20 and the die 30 within the second storage recess 32. Consequently, the material block 40 gradually changes its shape as shown in Fig. 3(E) and Fig. 3(F). Note that when the material block 40 is extrusion-molded, the volume of the material block 40 does not change before and after the molding.

[0022] When the operator further pushes the punch 20 as shown by the arrow 15c in Fig. 3(G) from the state shown in Fig. 3(D), the material block 40 is further expanded in the direction opposite to the pressing direction of the punch 20 as shown by the arrow 15d in Fig. 3(I). Then, when the stepped portion 22 of the punch 20 reaches the boundary portion between the first storage recess 31 and the second storage recess 32 of the die 30, as shown in Fig. 3(H) and Fig. 3(I), the annular first short-circuit ring 6 and the plurality of rod-shaped portions 8 extending in a state of being connected to the first short-circuit ring 6 at the connecting portion 8a are formed at once. The end portion of the rod-shaped portion 8 on the side opposite to the connecting portion 8a is a free end portion 8b. Since the first short-circuit ring 6 and the rod-shaped portions 8 are formed by extrusion molding, unlike the case of forming them by casting, no casting cavities are generated in these portions.

[0023] In the present embodiment, a process using plastic deformation is adopted to avoid the generation of casting cavities, and among the processes using plastic deformation, extrusion molding is adopted. As a process using plastic deformation, for example, press working is known, but in the case of press working, it becomes difficult to ensure the required length dimension of the rod-shaped portion 8. That is, in press working, a stretching process for the material is included, and in the stretching process, it is difficult to form a long portion. On the other hand, in the case of extrusion molding, the required length dimension of the rod-shaped portion 8 can be ensured.

[0024] <Insertion process> After the extrusion molding process is completed, the process proceeds to the insertion process. The insertion process is a process of inserting the rotor core 5 from the free end 8b side of the rod-shaped portion 8 formed by the extrusion molding process. The operator forms the rotor core 5 by laminating a plurality of plate-shaped electromagnetic steel sheets 5a. A plan view of the electromagnetic steel sheet 5a is shown in FIG. 4. One electromagnetic steel sheet 5a is formed in a disk shape by a silicon steel sheet, and a first insertion hole 5a1 for inserting a rotating shaft member 9 (see FIG. 1) is provided at the center thereof. Further, second insertion holes 5a2 are provided around the first insertion hole 5a1 at predetermined intervals in the circumferential direction. The rod-shaped portions 8 are respectively inserted into the second insertion holes 5a2. For this reason, the arrangement of the second insertion holes 5a2 is set according to the arrangement of the rod-shaped portions 8. Note that the electromagnetic steel sheet 5a itself is a conventionally well-known one, and for its manufacturing method, a conventionally known method can also be adopted, so the detailed description thereof is omitted here.

[0025] In the present embodiment, the second insertion holes 5a2 are provided to insert the rod-shaped portions 8, but instead of the second insertion holes 5a2, notches with the outer peripheral edge side of the electromagnetic steel sheet 5a opened may be provided.

[0026] In the insertion process, as shown in FIGS. 5(A) to 5(C), the rod-shaped portions 8 are inserted into the second insertion holes 5a2 from the free end 8b, that is, the side opposite to the side where the first short-circuit ring 6 is provided. The inserted electromagnetic steel sheets 5a are sequentially laminated on the first short-circuit ring 6. After all the electromagnetic steel sheets 5a are inserted, the free end 8b of the rod-shaped portion 8 protrudes above the uppermost electromagnetic steel sheet 5a as shown in FIG. 5(B). Note that, for convenience of drawing, a state in which six electromagnetic steel sheets 5a are laminated is depicted in FIG. 5(B), but this does not indicate the actual number of laminations.

[0027] <Short-circuit ring forming process> Next, a short-circuit ring forming process for forming the second short-circuit ring 7 will be described. As shown in FIG. 5(B), after all the electromagnetic steel sheets 5a are inserted, the free end 8b of the rod-shaped portion 8 protrudes above the uppermost electromagnetic steel sheet 5a. In the short-circuit ring forming process, an operator bends the free end 8b. Specifically, as indicated by arrow 15e in FIG. 6, the operator applies a force to the free end 8b from the lateral direction to bend the free end 8b in the circumferential direction, bringing the free ends 8b adjacent to each other in the circumferential direction into contact. As a result, the free ends 8b are folded over in a circumferential shape, and the second short-circuit ring 7 is formed. Note that brazing may be performed on the portion where the free ends 8b are in contact to improve the strength.

[0028] Since the free end 8b is originally formed by extrusion from the material mass 40 (see FIG. 3(B) etc.), no casting cavity occurs in the free end 8b either, and heat generation is suppressed in the second short-circuit ring 7 as well.

[0029] Thus, the rotor 4 is formed. The formed rotor 4 has the rotating shaft member 9 attached thereto by press-fitting, and is incorporated into the stator 3 as shown in FIG. 1. Note that for the attachment of the rotating shaft member 9, conventionally known methods such as shrink fitting, fixing with an adhesive, and welding can be employed.

[0030] According to the manufacturing method of the rotor 4 of the first embodiment, since the first short-circuit ring 6, the second short-circuit ring 7, and the rod-shaped portion 8 are formed by extrusion, for example, unlike the case where they are formed by casting, no casting cavity occurs. As a result, heat generation during the operation of the cage-type induction motor 1 is suppressed.

[0031] Note that in this embodiment, each process has been described as being performed by an operator, but each process may be automatically performed using a working machine. This point is common to the second and third embodiments described below.

[0032] (Second Embodiment) Next, with reference to FIGS. 8 to 11(B), the manufacturing method of the second embodiment will be described. Since the rotor manufactured by the manufacturing method of the second embodiment is common to the rotor 4 manufactured by the manufacturing method of the first embodiment except for the details, the same reference numerals will be used to describe the common components.

[0033] <Intermediate body forming step> The manufacturing method of the rotor 4 in the second embodiment includes an intermediate body forming step. In the intermediate body forming step, an operator forms an intermediate body 71 as shown in FIG. 9(F). The intermediate body 71 refers to a form that is formed before reaching the form including the first short-circuit ring 6 and the rod-shaped portion 8. Extrusion molding is also adopted for the formation of the intermediate body. FIG. 8 shows a punch 50 used in the extrusion molding in the intermediate body forming step. The punch 50 is a cylindrical tool and includes a cylindrical portion 51 and a tapered portion 52 formed at the base end portion thereof.

[0034] Next, referring to FIG. 9(A), the extrusion molding is performed using the punch 50 and the die 60. The die 60 includes a storage recess 61 and a stopper portion 62 provided at the upper edge end of the opening of the storage recess 61. The inner diameter of the storage recess 61 has a dimension larger than the diameter of the cylindrical portion 51 of the punch 50. The distance of the gap between the storage recess 61 and the cylindrical portion 51 corresponds to the thickness of the annular wall portion 71b of the intermediate body 71 to be described later, and thus the radial dimension of the rod-shaped portion 8. The stopper portion 62 defines the pushing amount of the punch 50 when the tapered portion 52 abuts when the punch 50 is pushed in. The pushing amount of the punch 50 is set according to the thickness of the bottom plate portion 71a of the intermediate body 71 to be described later.

[0035] First, a solid cylindrical material block 70 having conductivity is set in the storage recess 61 of such a die 60. The material block 70 is solid cylindrical as shown in FIGS. 9(B) and 9(C). The material block 70 in the present embodiment is formed of the same material as the material block 40 in the first embodiment.

[0036] As shown in Fig. 9(A), the operator sets the material block 70 in the storage recess 61 of the die 60, and then inserts the punch 50 into the die 60. Then, as shown by the arrow 15f in Fig. 9(D), the operator moves the punch 50 to press the material block 40. As a result, the material block 70 is expanded in a direction opposite to the pressing direction of the punch 50 and flows into the space formed between the punch 50 and the die 60 within the storage recess 61. Thereby, the material block 70 gradually changes its shape and finally changes into an intermediate body 71 as shown in Fig. 9(E) and Fig. 9(F).

[0037] The intermediate body 71 has a cup shape and includes a bottom plate portion 71a and an annular wall portion 71b that extends from the edge of the bottom plate portion 71a and rises up. <Punching process> Next, referring to Figs. 10(A) to 10(E), the punching process will be described. The punching process is a process of punching out a punching piece 71a1 from the bottom plate portion 71a of the intermediate body 71 to form the first short - circuit ring 6. First, as shown by the arrow 15g in Fig. 10(A), the operator brings the punching punch 80 arranged to face the bottom plate portion 71a closer to the bottom plate portion 71a. Then, as shown by the arrow 15h in Fig. 10(B), the operator presses the punching punch 80 against the bottom plate portion 71a to punch out the punching piece 71a1. As a result, an opening 71a2 is formed and an annular first short - circuit ring 6 is formed. Note that by punching out the punching piece 71a1 in the punching process, a flange - like portion 6a is formed on the first short - circuit ring 6. This flange - like portion 6a may be removed by cutting or the like, or may be left as it is. The second embodiment is different from the first embodiment in that this flange - like portion 6a is formed.

[0038] In this embodiment, punching is adopted for processing the bottom plate portion 71a, but processing methods such as cutting or blanking may also be adopted.

[0039] <Machining process> Next, the machining process will be described. The machining process is a process of machining the annular wall portion 71b of the intermediate body 71 into a comb-like shape to form the rod-shaped portion 8. Referring to FIGS. 11(A) and 11(B), a removed portion 71b1 set adjacent to the portion formed as the rod-shaped portion 8 is shown with hatching. In the present embodiment, this removed portion 71b1 is cut and removed by the cutting tool 81 shown in FIG. 11(B). Thereby, as shown in FIGS. 10(D) and 10(E), a state including the first short-circuit ring 6 and the rod-shaped portion 8 can be obtained. That is, by performing machining, in the first embodiment, a state equivalent to the state shown in FIGS. 3(H) and 3(I) can be realized.

[0040] Note that in the present embodiment, cutting is employed as the machining, but other conventionally known machining methods such as punching and blanking may be employed. Further, in the present embodiment, the machining process is performed after the punching process, but the order of these is not limited, and the order may be reversed, or both processes may be performed simultaneously.

[0041] <Insertion process> After the punching process and the machining process, the operator performs the insertion process. Since the insertion process is the same as that in the first embodiment, the detailed description thereof is omitted here.

[0042] <Short-circuit ring forming process> After the insertion process, the operator performs the short-circuit ring forming process. Since the short-circuit ring forming process is the same as that in the first embodiment, the detailed description thereof is omitted here.

[0043] Even in the manufacturing method of the second embodiment, since the first short-circuit ring 6 and the rod-shaped portion 8 are formed by extrusion molding, for example, unlike the case where they are formed by casting, no casting cavity is generated. As a result, heat generation during the operation of the cage-type induction motor 1 is suppressed.

[0044] (Third Embodiment) Next, a third embodiment will be described with reference to FIGS. 12(A) and 12(B). The manufacturing method of the third embodiment is different in the short-circuit ring forming process compared to the first and second embodiments.

[0045] In the first and second embodiments, the second short-circuit ring 7 was formed by bending the free end 8b of the rod-shaped portion 8. In contrast, the rotor 90 manufactured by the manufacturing method of the third embodiment includes a plate body having conductivity, and in this embodiment, a second short-circuit ring 91 formed of a copper plate. The second short-circuit ring 91 is formed by placing a copper plate in contact with the free end 8b of the rod-shaped portion 8 protruding from the rotor core 5 and welding the contact portion.

[0046] Even in such a rotor 90, the first short-circuit ring 6 and the rod-shaped portion 8 are formed through the same processes as in the first and second embodiments. Therefore, since the first short-circuit ring 6 and the rod-shaped portion 8 are formed by extrusion molding, for example, unlike the case where they are formed by casting, no casting cavities are generated. As a result, heat generation during the operation of the cage-type induction motor 1 is suppressed.

[0047] The above embodiments are merely examples for implementing the present invention, and the present invention is not limited thereto. Modifying these examples variously is within the scope of the present invention, and it is obvious from the above description that various other embodiments are possible within the scope of the present invention.

Description of Reference Numerals

[0048] 1 Cage-type induction motor 2 Case 3 Stator 4 Rotor 5 Rotor core 5a Electromagnetic steel sheet 5a1 First insertion hole 5a2 Second insertion hole 6 First short-circuit ring 6a Flange portion 7 Second short-circuit ring 8 Rod-shaped portion 8a Connecting portion 8b Free end 9 Rotating shaft member 10a First bearing member 10b Second bearing member 20, 50 Punch 21 Guide part 22 Step part 23 Protruding part 24 Groove part 30, 60 Dies 31 First storage recess 32 Second storage recess 40, 70 Material blocks 51 Cylindrical part 52 Taper part 61 Storage recess 62 Stopper part 71 Intermediate body 71a Bottom plate part 71a1 Punched piece 71a2 Opening 71b Annular wall part 71b1 Removed part 80 Punching punch 81 Cutting tool

Claims

1. A method for manufacturing a rotor, comprising: a first short-circuit ring disposed on one end side in a direction along the rotation axis of the rotor core; a second short-circuit ring disposed opposite to the first short-circuit ring with the rotor core therebetween; and a plurality of rod-shaped portions inserted through the rotor core to connect the first short-circuit ring and the second short-circuit ring, a forming step of pressing a conductive material mass to form the first short-circuit ring and the rod-shaped portions extending from the first short-circuit ring; an inserting step of inserting the rotor core into the rod-shaped portions from the free end side of the rod-shaped portions; a processing step of providing the second short-circuit ring at the free end of the rod-shaped portion after the rotor core is inserted; and including, wherein the forming step forms the first short-circuit ring and the rod-shaped portions by pressing the side wall of a conductive cylindrical material mass. A method for manufacturing a rotor.

2. A method for manufacturing a rotor, comprising: a first short-circuit ring disposed on one end side in a direction along the rotation axis of the rotor core; a second short-circuit ring disposed opposite to the first short-circuit ring with the rotor core therebetween; and a plurality of rod-shaped portions inserted through the rotor core to connect the first short-circuit ring and the second short-circuit ring, a forming step of pressing a conductive material mass to form the first short-circuit ring and the rod-shaped portions extending from the first short-circuit ring; an inserting step of inserting the rotor core into the rod-shaped portions from the free end side of the rod-shaped portions; a processing step of providing the second short-circuit ring at the free end of the rod-shaped portion after the rotor core is inserted; and including, wherein the forming step includes a first step of pressing a conductive solid columnar material mass to form an intermediate body having a bottom plate portion and an annular wall portion, a second step of removing the bottom plate portion to form the first short-circuit ring, and a third step of processing the annular wall portion into a comb shape to form the rod-shaped portions. A method for manufacturing a rotor.

3. The third step is removing a removal portion set adjacent to a portion formed as the rod-shaped portion The method for manufacturing a rotor according to claim 2.

4. The removal portion is removed by a cutting tool. The method for manufacturing a rotor according to claim 3.

5. The processing step is bending the free end protruding from the rotor core in the circumferential direction, and providing the second short-circuit ring with the free ends adjacent in the circumferential direction in contact with each other. The method for manufacturing a rotor according to claim 1 or 2.

6. The processing step is placing a plate body having conductivity in contact with the free end protruding from the rotor core, and welding a contact portion between the free end and the plate body. The method for manufacturing a rotor according to claim 1 or 2.

Images