WO2023182256A1

WO2023182256A1 - Stator core manufacturing method, stator core, and motor

Info

Publication number: WO2023182256A1
Application number: PCT/JP2023/010828
Authority: WO
Inventors: 信之北; 高史米山
Original assignee: ニデック株式会社
Priority date: 2022-03-24
Filing date: 2023-03-20
Publication date: 2023-09-28
Also published as: CN118339749A

Abstract

This stator core manufacturing method includes: a cut line forming step for pressing circumferential end parts of a plurality of divided core piece forming regions, at which divided core pieces are to be formed in a stator core plate forming region of a steel plate and which are arranged circumferentially, in the thickness direction of the steel plate, and thereby forming cut lines in only circumferential boundary portions of the plurality of divided core piece forming regions in the stator core plate forming region; and a push-back step for returning, to original positions of the steel plate, portions of the divided core piece forming regions pressed in the thickness direction in the cut line forming step.

Description

Stator core manufacturing method, stator core, and motor

The present invention relates to a method for manufacturing a stator core, a stator core, and a motor.

A method of manufacturing a stator core in which split cores are arranged circumferentially around a central axis is known. For example, Patent Document 1 discloses a method for manufacturing a split laminated core in which processed bodies made up of a plurality of parts lined up in the circumferential direction are stacked. In the method for manufacturing a split laminated core disclosed in Patent Document 1, in the step of obtaining the workpiece, a cutting process is performed to form a slit line and a bending line that cross a region of the workpiece that will become the annular portion. Furthermore, a caulking is formed in the bending portion, which is the portion from the slit line to the bending line.

Patent No. 6495092

As disclosed in Patent Document 1, a stator core is manufactured by laminating stator core plates cut out from steel plates. In the process of cutting out the stator core plate from a steel plate, various processes are performed on the steel plate. For example, after a part of the steel plate is pushed out in the thickness direction to form a cut line, pushback processing may be performed to return the part of the steel plate to its original position. However, in the portion of the steel plate where the cut line is formed, the steel plate may be distorted due to stress during processing. Further, when cutting out a stator core plate from the steel plate on which the cut line is formed, the shape of the steel plate may be distorted due to release of residual stress at the cut line portion.　

When the distortion of the steel plate due to the formation of the cut line in the steel plate and the release of the residual stress increases, the dimensional accuracy of the stator core plate cut out from the steel plate may decrease. When the dimensional accuracy of the stator core plate decreases in this way, the dimensional accuracy of the stator core manufactured using the stator core plate also decreases.　

Therefore, in order to manufacture the stator core with high dimensional accuracy, there is a method that can suppress the distortion of the steel plate caused by the cutting line and cut out the stator core plate with high dimensional accuracy. It has been demanded.　

An object of the present invention is to cut out a stator core plate with high dimensional accuracy by suppressing distortion of the steel plate caused by the cutting line, and to manufacture a stator core with high dimensional accuracy. The goal is to realize the following.

A method for manufacturing a stator core according to an exemplary embodiment of the present invention includes dividing a laminate in which a plurality of annular stator core plates punched from a steel plate are laminated in the thickness direction into a plurality of pieces in the circumferential direction. This is a stator core manufacturing method in which a split core is formed by stacking a plurality of plate-shaped split core pieces in the thickness direction. The stator core manufacturing method includes forming the split core pieces in a stator core plate forming region of the steel plate where the stator core plate is formed, and forming a plurality of split core pieces arranged in a circumferential direction. A cut line is formed in the stator core plate forming region only at a circumferential boundary portion of the plurality of divided core piece forming regions by pushing out a circumferential end of the forming region in the thickness direction of the steel plate. and a push-back step of returning a portion of the split core piece forming region that was pushed out in the thickness direction in the cut line forming step to its original position on the steel plate.　

Further, a stator core according to an exemplary embodiment of the present invention is a stator in which a plurality of split cores each having a plurality of plate-shaped split core pieces laminated in the thickness direction are arranged circumferentially around a central axis. It is the core. In the stator core, end surfaces of the divided core pieces adjacent to the divided core pieces of other divided cores in the circumferential direction are constituted by sheared surfaces and fractured surfaces that are aligned in the thickness direction. The split core piece has an end face that forms a part of the outer periphery of the stator core and is formed by a sheared surface.

According to the method for manufacturing a stator core according to an exemplary embodiment of the present invention, the stator core plate can be cut out with high dimensional accuracy by suppressing the distortion of the steel plate caused by the cutting line, and the stator core plate can be cut out with high dimensional accuracy. It is possible to manufacture a stator core having:

FIG. 1 is a diagram showing an example of a motor. FIG. 2 is a perspective view showing an example of a stator core. FIG. 3 is a diagram showing an example of a stator core plate. FIG. 4 is a diagram showing an example of an end surface of one circumferential end of a split core piece. FIG. 5 is a diagram showing an example of the end surface of the other circumferential end of the split core piece. FIG. 6 is a diagram illustrating an example of an end surface of a divided core piece that constitutes a part of the outer periphery of the stator core. FIG. 7 is a diagram illustrating an example of a method for manufacturing the stator core according to the first embodiment. FIG. 8 is a diagram showing an example of a steel plate before processing. FIG. 9 is a diagram showing an example of a steel plate in which a central hole is formed. FIG. 10 is a diagram showing an example of a steel plate on which cut lines are formed. FIG. 11 is an explanatory diagram of the incision line forming process. FIG. 12 is an explanatory diagram of the pushback process. FIG. 13 is an explanatory diagram of the stator core plate outer shape forming process. FIG. 14 is a diagram illustrating an example of a method for manufacturing a stator core according to the second embodiment. FIG. 15 is a diagram showing an example of a steel plate in which a first strain prevention hole and a second strain prevention hole are formed. FIG. 16 is a diagram showing an example of a steel plate on which cut lines are formed. FIG. 17 is a diagram showing an example of forming a convex cut line. FIG. 18 is a diagram showing an example of forming a concave cut line. FIG. 19 is an explanatory diagram of the stator core plate outer shape forming process. FIG. 20 is a perspective view showing an example of the stator core after cutting.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the figures are given the same reference numerals, and the description thereof will not be repeated. Further, the dimensions of the constituent members in each figure do not faithfully represent the actual dimensions of the constituent members or the dimensional ratios of each constituent member.　

In the following description, the direction parallel to the central axis P of the stator 3 will be referred to as the "axial direction," the direction orthogonal to the central axis P will be referred to as the "radial direction," and the direction along the arc centered on the central axis P will be referred to as the "axial direction." "circumferential direction". Furthermore, among the circumferential directions, when the component is viewed from a predetermined direction, the counterclockwise direction is referred to as "one circumferential direction" and the clockwise direction is referred to as "the other circumferential direction." However, this definition of direction is not intended to limit the direction in which the motor 1 according to the present invention is used.　

Furthermore, in the following description, the "radial direction" and "circumferential direction" of the electromagnetic steel sheet mean the radial direction and circumferential direction centered on the center point of the central hole 5a punched in the electromagnetic steel sheet. In addition, below, an electromagnetic steel plate is only called the steel plate 5.　

In addition, in the following explanation, expressions such as "fixing", "connecting", and "attaching" (hereinafter referred to as "fixing, etc.") are used not only when members are directly fixed to each other, but also when they are connected through other members. Including cases where it is fixed. That is, in the following description, expressions such as fixation include direct and indirect fixation of members.　

(Motor Configuration) FIG. 1 is a diagram showing an example of a motor 1 according to the first embodiment. As shown in FIG. 1, the motor 1 includes a housing 1a, a rotor 2, and a stator 3. The rotor 2 rotates about a central axis P with respect to the stator 3. The motor 1 is a so-called inner rotor type motor 1 in which a rotor 2 is rotatably disposed within a cylindrical stator 3 about a central axis P.　

The rotor 2 includes a shaft 20, a rotor core 21, and a magnet 22. The rotor 2 is located radially inward of the stator 3 and is rotatable with respect to the stator 3.　

The rotor core 21 has a cylindrical shape and extends along the central axis P. The rotor core 21 is constructed by laminating a plurality of steel plates 5 formed in a predetermined shape in the thickness direction. The shaft 20 extending along the central axis P is fixed to the rotor core 21 while passing through the rotor core 21 in the axial direction. Thereby, the rotor core 21 rotates together with the shaft 20. Further, on the outer peripheral surface of the rotor core 21, a plurality of magnets 22 are positioned at predetermined intervals in the circumferential direction. Note that the magnet 22 may be a ring magnet connected in the circumferential direction.　

Stator 3 is housed within housing 1a. The stator 3 has a cylindrical shape and is located radially outward of the rotor 2. The stator 3 includes a stator core 31, a stator coil 36, and a bracket 37. Stator core 31 has a cylindrical shape and extends in the axial direction. The stator core 31 is composed of a plurality of stator core plates 4 formed in a predetermined shape and laminated in the thickness direction.　

(Stator Core) An example of the stator core 31 according to the first embodiment will be explained using FIGS. 2 to 6.　

FIG. 2 is a perspective view showing an example of the stator core 31. As shown in FIG. 2, the stator core 31 has a plurality of teeth 31b extending radially inward from a cylindrical yoke 31a. The stator core 31 has a slot hole 31c in which a part of the stator coil 36 is accommodated between adjacent teeth 31b among the plurality of teeth 31b.　

Although not shown in FIG. 2, a bracket 37 is attached to the teeth 31b of the stator core 31. The bracket 37 is made of an insulating material. The bracket 37 is made of, for example, a resin material, but may be made of a material other than the resin material. Stator coil 36 is wound on bracket 37.　

The stator core 31 has a plurality of split cores 32 arranged annularly around the central axis P. The plurality of split cores 32 are formed by dividing in the circumferential direction a laminate in which annular stator core plates 4 punched from steel plates 5 are stacked in the thickness direction.　

Each split core 32 has a split yoke portion 32a that constitutes a part of a cylindrical yoke 31a, and one tooth 31b. The divided yoke portions 32 a of the plurality of divided cores 32 constitute an annular yoke 31 a of the stator core 31 . Hereinafter, the circumferential end of the split yoke 32a in the split core 32 will be referred to as the circumferential end of the split core 32. The circumferential ends of the split cores 32 and the circumferential ends of the split cores 32 circumferentially adjacent to the split cores 32 are in contact with each other.　

FIG. 3 is a diagram showing an example of the stator core plate 4. As shown in FIG. The stator core plate 4 has split core pieces 41 arranged in the circumferential direction. In the example shown in FIG. 3, the plurality of split core pieces 41 have the same shape when viewed in the thickness direction. The divided core piece 41 includes a divided yoke piece 41a that constitutes a part of the divided yoke portion 32a, and a tooth piece 41b that constitutes a part of the teeth 31b.　

The split core 32 is composed of a plurality of plate-shaped split core pieces 41 laminated in the thickness direction. The plurality of split core pieces 41 are stacked in the thickness direction and are connected to each other by caulking portions 33c provided on the split yoke pieces 41a and the teeth pieces 41b, respectively.　

Hereinafter, the circumferential end of the split yoke piece 41a in the split core piece 41 will be referred to as the circumferential end of the split core piece 41. An end of a split core piece 41 constituting the split core 32 is in contact with an end of a split core piece 41 forming the split core 32 adjacent to the split core 32 in the circumferential direction.　

Each split core piece 41 has a convex portion 43 projecting in the circumferential direction at one end 42 in the circumferential direction. The convex portion 43 is located at the radial center of the split yoke piece 41a. Each split core piece 41 has a recess 45 recessed in one direction in the circumferential direction at the other end 44 in the circumferential direction. The recess 45 is located at the radial center of the split yoke piece 41a.　

Each split core piece 41 has an end face 46 at one end 42 in the circumferential direction, and an end face 47 at the other end 44 in the circumferential direction. FIG. 4 is a diagram showing an example of an end surface 46 of one end 42 in the circumferential direction of the split core piece 41. FIG. 5 is a diagram showing an example of an end surface 47 of the other end 44 in the circumferential direction of the split core piece 41. As shown in FIGS. 4 and 5, in the stator core 31, the split core pieces 41 have

end surfaces

46 and 47 adjacent to the split core pieces 41 of other split cores 32 in the circumferential direction at sheared surfaces Sp aligned in the thickness direction. and a fracture surface Fp.

In addition, in each split core piece 41, the shapes of the end faces of the ends other than the circumferential ends 42 and 44 of the split core piece 41 are the end faces 46 and 47 of the circumferential ends 42 and 44 of the split core piece 41 Unlike the shape of , it is composed of only the sheared surface Sp. For example, FIG. 6 is a diagram showing an example of an end surface 48 that constitutes a part of the outer periphery of the stator core 31. As shown in FIG. As shown in FIG. 6, the end face 48 of the divided core piece 41, which constitutes a part of the outer periphery of the stator core 31, is constituted only by the sheared surface Sp.　

(Method for Manufacturing Stator Core) Next, a method for manufacturing the stator core 31 according to the first embodiment will be described in detail with reference to FIGS. 7 to 14.　

Among steps S1 to S8 shown in FIG. 7, steps S1 to S5 are steps for forming the stator core plate 4 from the steel plate 5. A steel plate processing device (not shown) performs punching, cutting line formation, and pushback processing on the steel plate 5 supplied from a steel plate supply device (not shown). As a result, the stator core plate 4 is formed from the steel plate 5.　

FIG. 8 is a diagram showing an example of the steel plate 5 before processing. As shown in FIG. 8, it is possible to cut out a plurality of stator core plates 4 from a steel plate 5. As shown in FIG. 8, the steel plate 5 includes a stator core plate forming region 6 where the stator core plate 4 is formed. Further, the stator core plate forming region 6 includes a plurality of divided core piece forming regions 7 arranged in the circumferential direction. The split core piece forming region 7 is an area where the split core pieces 41 are formed. In FIG. 8, the stator core plate forming area 6 and the split core piece forming area 7 are illustrated by broken lines. The stator core plate 4 is formed by punching the steel plate 5 along the outer periphery of the stator core plate forming region 6.　

When forming the stator core plate 4, first, by punching out the steel plate 5, a circular central hole 5a is formed in the stator core plate forming region 6. The process of forming the center hole 5a in the steel plate 5 in this manner is the center hole punching process of step S1 shown in FIG. The center of the central hole 5a coincides with the central axis P of the motor 1. FIG. 9 is a diagram showing an example of a steel plate 5 in which a central hole 5a is formed.　

The above-mentioned center hole punching process is performed by press working. The center hole punching process is the same as the conventional manufacturing method of the stator core 31, so a detailed explanation will be omitted.　

Next, a cut line 9 is formed by making a cut in the steel plate 5. The step of forming the cut line 9 on the steel plate 5 in this manner is the cut line forming step of step S2 shown in FIG.　

The cut line 9 constitutes a part of the outer periphery of the divided core piece forming region 7. In the cut line forming step, in the stator core plate forming region 6 of the steel plate 5, the circumferential ends of the plurality of split core piece forming regions 7 lined up in the circumferential direction are pushed out in the thickness direction of the steel plate 5, thereby forming the cuts. A line 9 is formed. In the stator core plate forming region 6, the cut line 9 is formed only at the circumferential boundary portion 71 of the plurality of divided core piece forming regions 7. Furthermore, in this embodiment, the cut lines 9 are formed in all the boundary portions 71 within the stator core plate forming region 6.　

Since the part where the cut line 9 is formed is limited to the boundary part 71 of the divided core piece forming region 7, the length of the cut line 9 is shorter than when the cut line 9 is formed in parts other than the boundary part. is suppressed. Therefore, the distortion of the steel plate 5 that occurs when forming the cut line 9 and the residual stress that remains in the steel plate 5 are suppressed. Therefore, it is possible to cut out the stator core plate 4 from the steel plate 5 with high dimensional accuracy. Therefore, by stacking the stator cores 31 cut out with high dimensional accuracy, it is possible to manufacture the stator core 31 with high dimensional accuracy.　

FIG. 10 shows an example of a steel plate 5 on which a cut line 9 is formed. By the cut line forming step, a plurality of cut lines 9 are formed in the stator core plate forming region 6, extending in the radial direction and aligned in the circumferential direction.　

As shown in FIG. 11, the plurality of cut lines 9 are formed using a pair of upper and lower tools W that sandwich a part of the steel plate 5 in the thickness direction, and a tool T that pushes a part of the steel plate 5 in the thickness direction. . The tool T is movable relative to the tool W in the thickness direction of the steel plate 5.　

As shown by the white arrow in FIG. 11, when the tool T moves in one direction in the thickness direction of the steel plate 5 with respect to the tool W, a part of the area of the steel plate 5 is pushed out in the thickness direction by the tool T. On the other hand, as shown in FIG. 11, at least a portion of the cut line 9 in the thickness direction is left uncut. That is, the tool T does not completely cut off the boundary portion 71 in the steel plate 5. At least some of the cut lines 9 are connected.　

By extruding a part of the steel plate 5 in the thickness direction using the tool T, a part of the steel plate 5 in the thickness direction is sheared at the boundary portion 71 . A sheared surface Sp is formed in the sheared portion. On the other hand, in the portion of the boundary portion 71 that is not separated, a fracture surface Fp is formed when the stack of stator core plates 4 is divided into a plurality of split cores 32 in a dividing step to be described later.　

Therefore, the end surfaces 46 and 47 of the circumferential ends of the split core piece 41 have a sheared surface Sp and a fractured surface Fp in the thickness direction.　

As shown in FIG. 10, the divided core piece forming area 7 included in the stator core plate forming area 6 includes a concave forming area R2 located on one side in the circumferential direction with respect to the cutting line 9, and a concave forming area R2 located on one side in the circumferential direction with respect to the cutting line 9. and a convex shape forming region R1 located on the other side of the direction. Further, as shown in FIG. 10, in the stator core plate forming area 6, there are divided core piece forming areas 7 including a concave forming area R2 and a convex forming area R1, and a concave forming area R2 and a convex forming area R1. The split core piece forming regions 7 not including the split core pieces are alternately located in the circumferential direction.　

When the tool T pushes out the convex shape forming region R1 in the thickness direction of the steel plate 5, a convex cut line 9a is formed. When the tool T pushes out the concave shape forming region R2 in the thickness direction of the steel plate 5, the concave cut line 9b is formed.　

The portion of the split core piece forming region 7 that was pushed out in the thickness direction in the cut line forming step is returned to the original position of the steel plate 5. The process of returning the portion pushed out in the thickness direction of the steel plate 5 to its original position on the steel plate 5 in this way is the pushback process of step S3 shown in FIG.　

As shown in FIG. 12, the tool S pushes the portion extruded by the tool T in one direction in the thickness direction in a direction opposite to the extrusion direction. Thereby, as shown in FIG. 12, the portion pushed out in the thickness direction is returned to its original position on the steel plate 5.　

The plurality of cut lines 9 are formed at the boundary portion 71 of the divided core piece forming region 7 . That is, the stator core plate forming region 6 includes a plurality of cut lines 9 arranged in the circumferential direction. A pushback process is performed for each boundary portion 71. As a result, all the cut lines 9 are formed by the pushback process.　

Next, a region of the steel plate 5 where the slot hole 31c in the stator core 31 will be formed is punched out in the shape of the slot hole 31c. The step of punching out the slot holes 31c in the steel plate 5 in this manner is the slot punching step of step S4 shown in FIG. The slot punching process is performed by press working.　

As shown in FIG. 13, a stator core plate forming region 6 in which the stator core plate 4 will be formed is punched out of the steel plate 5. In other words, the steel plate 5 is punched to have the outer shape of the stator core 31 when viewed in the axial direction. Thereby, an annular stator core plate 4 is formed in which the split core pieces 41 that become the split cores 32 are connected in the circumferential direction. It is possible to cut out the stator core plate 4 with less distortion in shape from the steel plate 5 with less distortion. The step of forming the outer shape of the stator core plate 4 in this manner is the stator core plate outer shape forming step of step S5 shown in FIG.　

Next, a caulked portion 33c shown in FIG. 2 is formed on the stator core plate 4. The caulking portion 33c forms a convex portion in the split core piece forming region 7, which is a portion of the stator core 31 that will become the split core piece 41, protruding in one direction in the thickness direction and having a concave portion on the other side in the thickness direction. It can be obtained by The step of forming the caulked portion 33c in this manner is the caulked portion forming step of step S6 shown in FIG.　

Thereafter, a stacked body of stator core plates 4 is obtained by laminating a plurality of stator core plates 4 in the thickness direction while caulking the caulked portions 33c of adjacent stator core plates 4 in the lamination direction. The process of stacking the stator core plates 4 in the thickness direction in this manner is the stator core plate stacking process of step S7 shown in FIG.　

By applying a force in a direction perpendicular to the stacking direction to the outer peripheral side of the stacked body of the stator core plate 4, the boundary portion 71 between the adjacent split core pieces 41 is split. That is, the laminate is divided into a plurality of divided cores 32. The step of dividing the laminated body of the stator core plate 4 into a plurality of split cores 32 in this manner is the dividing step of step S8 shown in FIG.　

In this way, the split core 32 is formed by separating the stacked stator core plates 4 at the boundary between adjacent split core pieces 41. Note that, as long as it can be divided into a plurality of split cores 32, the component of the force applied to the stacked body is not limited to the component in the direction perpendicular to the stacking direction.　

Note that a winding wire is wound around each of the divided cores 32. Thereafter, the stator core 31 having coils is obtained by rejoining the split cores 32 in the same combination as when they were split.　

As described above, the method for manufacturing the stator core 31 according to the first embodiment involves dividing a laminate in which a plurality of annular stator core plates 4 punched from a steel plate 5 are laminated in the thickness direction into a plurality of pieces in the circumferential direction. This is a method of manufacturing a stator core 31 in which a split core 32 is formed by stacking a plurality of plate-shaped split core pieces 41 in the thickness direction. The method for manufacturing the stator core 31 is such that split core pieces 41 are formed in a stator core plate forming region 6 in which the stator core plate 4 of the steel plate 5 is formed, and a plurality of split core pieces are arranged in the circumferential direction. By extruding the circumferential end of the piece forming region 7 in the thickness direction of the steel plate 5, a cut line 9 is formed only at the circumferential boundary portion 71 of the plurality of split core piece forming regions 7 in the stator core plate forming region 6. The method includes a cut line forming step S2 to form a cut line, and a push back step S3 to return the portion of the split core piece forming region 7 that was pushed out in the thickness direction in the cut line forming step S2 to its original position on the steel plate 5.　

In the cut line forming step S2, the portion of the stator core plate forming region 6 where the cut line 9 is formed is limited to only the boundary portion 71 of the split core piece forming region 7. The length of the cut line 9 is suppressed compared to the case where the cut line 9 is also formed in a portion other than the boundary portion. Therefore, the distortion of the steel plate 5 that occurs when forming the cut line 9 and the residual stress that remains in the steel plate 5 are suppressed. Therefore, it is possible to cut out the stator core plate 4 from the steel plate 5 with high dimensional accuracy. Therefore, by stacking the stator cores 31 cut out with high dimensional accuracy, it is possible to manufacture the stator core 31 with high dimensional accuracy.　

Further, in the method for manufacturing the stator core 31 according to the embodiment, after the cut line forming step S2 and the pushback step S3, the stator core plate forming region 6 in which the stator core plate 4 is formed is punched out from the steel plate 5. This further includes a stator core plate outer shape forming step S5 of forming the outer shape of the stator core plate 4.　

Thereby, it is possible to cut out the stator core plate 4 with less distortion in shape from the steel plate 5 with less distortion.　

Further, the stator core 31 according to the embodiment is a stator core 31 in which a plurality of split cores 32 each having a plurality of plate-shaped split core pieces 41 laminated in the thickness direction are arranged in a circumferential direction around a central axis. . End surfaces 46 and 47 of the split core piece 41 in the stator core 31 that are circumferentially adjacent to the split core pieces 41 of the other split core 32 are constituted by a sheared surface Sp and a fractured surface Fp that are aligned in the thickness direction. An end surface 48 forming a part of the outer periphery of the stator core 31 is formed by a sheared surface Sp.

Since the cut line 9 is formed in the steel plate 5 only at the boundary portion 71 of the circumferentially adjacent split core forming regions 7, the end surfaces 46 and 47 of the split core piece 41 that contact the circumferentially adjacent split cores 32, The sheared surface Sp and the fractured surface Fp are arranged in the thickness direction. Further, by punching out the outer shape of the stator core plate 4 from the steel plate 5, a sheared surface Sp is formed on the end face 48 of the split core piece 41, which constitutes a part of the outer periphery of the stator core 31. Therefore, the stator core 31 having these end faces is formed using the stator core plate 4 in which the distortion and residual stress of the steel plate 5 are suppressed. Therefore, the stator core 31 having the above-described configuration has high dimensional accuracy.　

Further, the motor 1 according to the embodiment includes a stator core 31. The motor 1 can be efficiently manufactured using the stator core 31 having high dimensional accuracy.　

(Embodiment 2) Next, a method for manufacturing the stator core 31 according to Embodiment 2 will be described using FIGS. 14 to 20. The manufacturing method according to the second embodiment differs from the manufacturing method according to the first embodiment in that it includes a distortion prevention hole forming step. Note that in the description of the second embodiment, detailed descriptions of parts common to the manufacturing method according to the first embodiment will be omitted.　

Specifically, among the steps shown in FIG. 14, steps S11, S14, S15, and steps S17 to S19 are the same as steps S1, S3, S4, and steps S6 to S8 in FIG. Therefore, detailed description of steps S11, S14, S15, and steps S17 to S19 will be omitted.　

In the method for manufacturing the stator core 31 according to the second embodiment, the first distortion prevention hole 81 and the second distortion prevention hole 82 are formed in the steel plate 5 between the center hole punching step and the cut line forming step. The step of forming the first strain prevention hole 81 and the second strain prevention hole 82 in the steel plate 5 in this way is the strain prevention hole forming step of step S12 shown in FIG. FIG. 15 is a diagram showing an example of the steel plate 5 in which the first distortion prevention hole 81 and the second distortion prevention hole 82 are formed.　

In the strain prevention hole forming step, the first strain prevention hole 81 is formed in the steel plate 5 at a position radially outward of the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7 and connected to the boundary portion 71. Ru. Further, the second strain prevention hole 82 is formed in the steel plate 5 at a position that is radially inward of the boundary portion 71 and connected to the boundary portion 71 . The second distortion prevention hole 82 is located within the stator core plate forming region 6. The first distortion prevention hole 81 and the second distortion prevention hole 82 are formed, for example, by press working.　

The stator core plate forming area 6 includes a plurality of split core piece forming areas 7 arranged in the circumferential direction. Therefore, the stator core plate forming region 6 includes a plurality of boundary portions 71 between circumferentially adjacent split core piece forming regions 7. In this embodiment, the first distortion prevention hole 81 and the second distortion prevention hole 82 are formed in all the boundary portions 71.　

The second distortion prevention hole 82 has a larger opening area than the first distortion prevention hole 81. Therefore, in the radially inner portion of the cut line 9 formed in the boundary portion 71, distortion of the steel plate 5 and residual stress remaining in the steel plate 5 can be efficiently suppressed.　

As shown in FIG. 15, the first distortion prevention hole 81 has an elliptical shape that is elongated in the circumferential direction. The second distortion prevention hole 82 has a circular shape. However, the first distortion prevention hole 81 may have a shape other than an ellipse, such as a circular shape or a rectangular shape. Further, the second distortion prevention hole 82 may have a shape other than a circular shape, such as a rectangular shape, for example.　

Next, in the steel plate 5 in which the first strain prevention hole 81 and the second strain prevention hole 82 are formed, as shown in FIG. A plurality of lined cut lines 9 are formed. The step of forming the cut line 9 on the steel plate 5 in this way is the cut line forming step of step S13 shown in FIG. 14.　

The cut line 9 constitutes a part of the outer periphery of the divided core piece forming region 7. Moreover, the cut line 9 is formed in the steel plate 5 at a position connecting the first distortion prevention hole 81 and the second distortion prevention hole 82. Specifically, the plurality of cut lines 9 are formed at the boundary portion 71 of the divided core piece forming region 7 .　

The first strain prevention hole 81 and the second strain prevention hole 82 formed in the steel plate 5 are used to prevent the boundary portion 71 from forming the cut line 9 at the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7. It is possible to suppress distortion from occurring in the vicinity. Furthermore, it is possible to suppress the force applied to the steel plate 5 from remaining in the vicinity of the boundary portion 71. Moreover, since the cut line 9 connecting the two distortion prevention holes 81 and 82 is formed while suppressing the length of the cut line 9, distortion of the steel plate 5 and residual stress remaining in the steel plate 5 can be suppressed. Therefore, it is possible to cut out the stator core plate 4 from the steel plate 5 with high dimensional accuracy. Therefore, by stacking the stator core plates 4 cut out with high dimensional accuracy, it is possible to manufacture the stator core 31 with high dimensional accuracy.　

In the second embodiment as well, in the stator core plate forming region 6 in which the stator core plate 4 of the steel plate 5 is formed, the circumferential end portions of the plurality of split core piece forming regions 7 arranged in the circumferential direction are is extruded in the thickness direction. As a result, the cut line 9 is formed only in the circumferential boundary portion 71 of the plurality of divided core piece forming regions 7 in the stator core plate forming region 6. Furthermore, in this embodiment, the cut lines 9 are formed in all the boundary parts 71 within the stator core plate forming region 6.　

Similar to Embodiment 1, the cut line 9 is formed using a pair of upper and lower tools W and a tool T that presses a part of the steel plate 5 in the thickness direction. The tool T is movable relative to the tool W in the thickness direction of the steel plate 5. At least a portion of the cut line 9 in the thickness direction is left uncut. That is, the tool T does not completely cut off the boundary portion 71 in the steel plate 5. At least a portion of the cut line 9 is continuous in the circumferential direction. Therefore, when the stator core 31 in which the stator core plates 4 are laminated is divided, the end surfaces 46 and 47 of the boundary portion 71 of the divided core pieces 41 have a shear surface Sp and a fracture surface Fp in the thickness direction. .　

As shown in FIG. 16, the divided core piece forming area 7 included in the stator core plate forming area 6 includes a concave forming area R2 located on one side in the circumferential direction with respect to the cutting line 9, and a concave forming area R2 located on one side in the circumferential direction with respect to the cutting line 9. and a convex shape forming region R1 located on the other side of the direction. The convex shape forming region R1 and the concave shape forming region R2 are regions pushed out in the thickness direction for forming the cut line 9 in the split core piece forming region 7.　

FIG. 17 is a diagram showing an example of forming the convex cut line 9a. As shown in FIG. 17, a tool T (not shown) pushes out the convex shape forming region R1 in the thickness direction of the steel plate 5, thereby forming a convex cut line 9a. It has a protruding part. In the convex shape forming region R1, the moving distance of the tool T in the thickness direction is such a distance that the boundary portion 71 is not completely separated.　

FIG. 18 is a diagram showing an example of forming the concave cut line 9b. As shown in FIG. 18, a tool T (not shown) pushes out the concave shape forming region R2 in the thickness direction of the steel plate 5, thereby forming a concave cut line 9b. The concave cut line 9b has a concave portion in one direction in the circumferential direction. Also in the concave shape forming region R2, the moving distance of the tool T in the thickness direction is such a distance that the boundary portion 71 is not completely separated.　

Next, a difference between the stator core plate outer shape forming process in step S16 between the first embodiment and the second embodiment, which is based on the formation of the distortion prevention holes, will be explained. After forming the slot holes 31c, as shown in FIG. 19, the stator core plate forming region 6 is punched out from the steel plate 5 at a position overlapping a part of the first distortion prevention hole 81 when looking at the steel plate 5 in the thickness direction. . In other words, the steel plate 5 is punched to have the outer shape of the stator core 31 when viewed in the axial direction. Thereby, an annular stator core plate 4 in which the split core pieces 41 are connected in the circumferential direction is formed.　

In the stator core plate outer shape forming step, a punch (not shown) punches the steel plate 5 into a circular shape, for example. In the stator core plate forming region 6, the first distortion prevention holes 81 are adjacent to all the boundary portions 71. When looking at the steel plate 5 in the thickness direction, the punch punches the steel plate 5 at a position overlapping with a portion of all the first distortion prevention holes 81 adjacent to the stator core plate forming region 6. In this respect, the manufacturing method of the second embodiment differs from the manufacturing method of the first embodiment.　

In the method for manufacturing the stator core 3 of the second embodiment, it is possible to punch out the outer shape of the stator core plate 4 from the steel plate 5 using the first distortion prevention hole 81. By the stator core plate outer shape forming process, a recess 83 that is recessed radially inward is formed on the stator core plate 4 on the radially outer side with respect to the boundary portion 71 between the circumferentially adjacent split core pieces 41. Ru.　

Therefore, as shown in FIG. 20, the stator core 31 has a recess 34 that is recessed radially inward on the outer peripheral side of the stator core 31 and at a boundary 71 between circumferentially adjacent split cores 32.　

In the stator core manufacturing method according to the second embodiment, a first strain prevention material is provided on the steel plate 5 at a position radially outward of and connected to the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7. The method further includes a distortion prevention hole forming step S12 in which the hole 81 is formed and a second distortion prevention hole 82 is formed at a position radially inward of the boundary portion 71 and connected to the boundary portion 71. In the cut line forming step S13, a cut line 9 connecting the first distortion prevention hole 81 and the second distortion prevention hole 82 is formed in the boundary portion 71.　

The first strain prevention hole 81 and the second strain prevention hole 82 formed in the steel plate 5 are used to prevent the boundary portion 71 from forming the cut line 9 at the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7. It is possible to suppress distortion from occurring in the vicinity. Furthermore, it is possible to suppress the force applied to the steel plate 5 from remaining in the vicinity of the boundary portion 71. Moreover, since the cut line 9 connecting the two distortion prevention holes 81 and 82 is formed while suppressing the length of the cut line 9, distortion of the steel plate 5 and residual stress remaining in the steel plate 5 can be further suppressed. Therefore, it is possible to cut out the stator core plate 4 from the steel plate 5 with high dimensional accuracy. Therefore, by stacking the stator core plates 4 cut out with high dimensional accuracy, it is possible to manufacture the stator core 31 with high dimensional accuracy.　

Further, in the distortion prevention hole forming step S12, a second distortion prevention hole 82 having a larger opening area than the first distortion prevention hole 81 is formed.　

The second distortion prevention hole 82 located radially inward of the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7 is larger than the first strain prevention hole 81 located radially outward of the boundary portion 71. big. Therefore, in the radially inner portion of the cut line 9 formed in the boundary portion 71, distortion of the steel plate 5 and residual stress remaining in the steel plate 5 can be efficiently suppressed.　

<Other Embodiments> Although the embodiments of the present invention have been described above, the embodiments described above are merely examples for implementing the present invention. Therefore, without being limited to the embodiments described above, the embodiments described above can be modified and implemented as appropriate without departing from the spirit thereof.　

In each of the embodiments described above, the cut lines 9 are formed in all of the circumferential boundary portions 71 of the plurality of divided core piece forming regions 7 in the stator core plate forming region 6. However, the cut line may be formed only in a part of the circumferential boundary portion of the plurality of divided core piece forming regions. In other words, the stator core plate may have a boundary portion in which no cut line is formed.　

In each of the embodiments described above, the slot hole 31c is formed after the cut line 9 is formed. However, the slotted holes may be formed prior to forming the score lines. In this case, the slot hole may be used as the second strain prevention hole.

In each of the embodiments described above, the split core piece 41 has a convex portion 43 at one end 42 in the circumferential direction, and a recess 45 at the other end 44 in the circumferential direction. However, the split core piece may have a concave portion at one end in the circumferential direction and a convex portion at the other end in the circumferential direction. Further, the split core piece may not have a convex portion at one end in the circumferential direction, and may not have a concave portion at the other end in the circumferential direction. The end portions of the divided core pieces may have a straight shape, a curved shape, or a combination of a straight line and a curved shape when the divided core piece is viewed in the thickness direction.　

In each of the above embodiments, the convex cut line 9a is formed in the steel plate 5 by extruding the convex shape forming region R1, and the concave cut line 9b is formed by pushing out the concave shape forming region R2. However, only convex cut lines may be formed in the steel plate. Alternatively, only the concave cut line may be formed on the steel plate.　

In the second embodiment, the first strain prevention hole 81 is formed in the steel plate 5 at a position radially outward of the boundary portion 71 of the circumferentially adjacent split core piece forming regions 7 and connected to the boundary portion 71. Ru. The second distortion prevention hole 82 is formed at a position radially inward of the boundary portion 71 and connected to the boundary portion 71 . However, at least one of the first distortion prevention hole and the second distortion prevention hole may be formed at a position that is not connected to the boundary portion.　

In the second embodiment, when looking at the steel plate 5 in the thickness direction, the stator core plate forming region 6 where the stator core plate 4 is formed is formed from the steel plate 5 at a position overlapping a part of the first distortion prevention hole 81. By punching, the outer shape of the stator core plate 4 is formed. However, when looking at the steel plate in the thickness direction, the outer shape of the stator core plate is formed by punching the steel plate at a position that does not overlap with the first strain prevention hole or a position where a recess that is concave inward in the radial direction is not formed at the boundary part. It's okay.　

In the second embodiment, the second distortion prevention hole 82 has a larger opening area than the first distortion prevention hole 81. However, the second distortion prevention hole may have a smaller opening area than the first distortion prevention hole. Further, the opening area of the second distortion prevention hole and the opening area of the first distortion prevention hole may be equal.　

In the second embodiment, when the stator core 31 is viewed in the axial direction, the stator core 31 is arranged radially outwardly with respect to the boundary portion 71 between the circumferentially adjacent split cores 32 in the stator core 31. It has a recess 34 that is recessed inward. However, the stator core does not need to have a concave portion that is concave radially inward on the radially outer side with respect to the boundary portion between circumferentially adjacent split cores.

INDUSTRIAL APPLICATION This invention can be utilized for the manufacturing method of a stator core, and a stator core.

1 Motor 1a Housing 2 Rotor 20 Shaft 21 Rotor core 22 Magnet 3 Stator 31 Stator core 31a Yoke 31b Teeth 31c Slot hole 32 Split core 32a Split yoke portion 33c Caulking portion 34 Recess 36 Stator coil 37 Bracket 4 Stator Core plate 41 Split core piece 41a Split yoke piece 41b Teeth piece 42 End portion 43 Convex portion 44 End portion 45 Recess 46 End face 47 End face 48 End face 5 Steel plate 5a Center hole 6 Stator core plate forming area 7 Split core piece forming area 71 Boundary Part 81 First distortion prevention hole 82 Second distortion prevention hole 83 Recess 9 Cut line 9a Convex cut line 9b Concave cut line Fp Fracture surface P Central axis R1 Convex shape formation region R2 Concave shape formation region Sp Shear surface S Tool T Tool W Tools

Claims

By dividing a laminate in which multiple annular stator core plates punched from steel plates are stacked in the thickness direction into multiple pieces in the circumferential direction, a split core is created in which multiple plate-shaped split core pieces are stacked in the thickness direction. A method for manufacturing a stator core forming a stator core comprising:

Within the stator core plate forming region of the steel plate where the stator core plate is formed, the circumferential ends of the plurality of split core piece forming regions where the split core pieces are formed and arranged in the circumferential direction are A cut line forming step of forming a cut line only in the circumferential boundary portion of the plurality of split core piece forming regions in the stator core plate forming region by extruding the steel plate in the thickness direction;

A method for manufacturing a stator core, comprising: a push-back step of returning a portion of the split core piece forming region pushed out in the thickness direction in the cut line forming step to its original position on the steel plate.
In the method for manufacturing a stator core according to claim 1,

The first strain prevention hole is formed in the steel plate at a position radially outward of the boundary portion of the circumferentially adjacent divided core piece forming regions and connected to the boundary portion, and the first strain prevention hole is formed in the radial direction of the boundary portion. further comprising a distortion prevention hole forming step of forming the second distortion prevention hole inward and at a position connected to the boundary portion,

In the stator core manufacturing method, the cut line forming step includes forming the cut line connecting the first strain prevention hole and the second strain prevention hole in the boundary portion.
The method for manufacturing a stator core according to claim 2,

The method for manufacturing a stator core includes forming the second strain prevention hole having a larger opening area than the first strain prevention hole in the strain prevention hole forming step.
In the method for manufacturing a stator core according to any one of claims 1 to 3,

After the cut line forming step and the pushback step, a stator core that forms the outer shape of the stator core plate by punching out a stator core plate forming region in which the stator core plate is formed from the steel plate. A method for manufacturing a stator core, further comprising a step of forming a plate outer shape.
A stator core in which a plurality of split cores each having a plurality of plate-shaped split core pieces laminated in the thickness direction are arranged in a circumferential direction around a central axis,

The split core piece is

In the stator core, an end surface adjacent to a split core piece of another split core in the circumferential direction is constituted by a sheared surface and a fractured surface aligned in the thickness direction,

A stator core, wherein an end face forming a part of an outer periphery of the stator core is formed by a sheared surface.
A motor comprising the stator core according to claim 5.