Patent Publication Number: US-2019190330-A1

Title: Stacked core, device for manufacturing stacked core, and method of manufacturing stacked core

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from Japanese Patent Application No. 2017-240979, filed on Dec. 15, 2017, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a stacked core, a device for manufacturing the stacked core, and a method of manufacturing the stacked core. 
     BACKGROUND 
     Japanese Unexamined Patent Publication No. 2007-014122 discloses a method of manufacturing a stacked core including a first step of forming a through hole or a connector at a predetermined position of a belt-like metal sheet (workpiece sheet) wound in a coiled shape while sequentially feeding a coiled material of the metal sheet at a predetermined pitch from an uncoiler on an intermittent basis. Additionally, the method includes a second step of blanking the metal sheet with a punch to form a blanked member having the through hole or the connector, and a third step of stacking and fastening together a plurality of blanked members by a through hole and connectors to form the stacked core. 
     The connector has a groove formed in the corresponding blanked member on its upper-surface side and a protrusion formed on the blanked member on its lower-surface side. The protrusion of the connector of one blanked member is fitted into the groove of the connector of another blanked member. Additionally, the protrusion of a connector of a blanked member adjacent to the lowermost layer of the stacked core is fitted into the though hole. When a plurality of stacks are successively manufactured, the through hole has the function of preventing a subsequently manufactured stack from being fastened by the connector to an already manufactured stack. 
     SUMMARY 
     A stack formed by stacking a plurality of blanked members includes a first blanked member forming an outermost layer of the stack and a second blanked member located adjacent to the first blanked member. A through is hole formed in the first blanked member, and an area of the through hole has a length that is greater than a width. A connecting tab having a chevron shape is formed in the second blanked member so as to be fitted into the through hole of the first blanked member. On opposite sides of the through hole, notches are recessed outward from an inner-wall surface of the through hole in opposing directions that correspond to the width of the area of the through hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating an example stacked rotor core; 
         FIG. 2  is a sectional view taken along line in  FIG. 1 ; 
         FIG. 3  is an exploded perspective view illustrating a state in which a connecting tab is fitted into a through hole of a blanked member 
         FIG. 4  is a schematic diagram illustrating an example device for manufacturing a stacked rotor core; 
         FIG. 5A  is a perspective view illustrating an example punch configured to form a through hole; 
         FIG. 5B  is a perspective view illustrating an example die hole corresponding to the punch of  FIG. 5A ; 
         FIG. 6A  is a perspective view illustrating an example punch configured to form a connecting tab; 
         FIG. 6B  is a perspective view illustrating an example die hole corresponding to the punch of  FIG. 6A ; 
         FIG. 7A  is a schematic sectional view illustrating an example process of forming a through hole: 
         FIG. 7B  is a schematic sectional view illustrating an example process of forming a connecting tab; 
         FIG. 8  is a sectional view schematically illustrating a mechanism to stack blanked members and a mechanism to discharge a stack from a die, as a diagram for explaining a process of blanking, with a punch, a blanked member from an electrical steel sheet; 
         FIG. 9  is an enlarged sectional view illustrating an example pressing protrusion of the punch of  FIG. 8 ; 
         FIG. 10  is a sectional view schematically illustrating an example mechanism to stack blanked members and an example mechanism to discharge a stack from a die; and 
         FIG. 11  is an enlarged sectional view illustrating part of an example stacked core having a burr. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. 
     Stacked Rotor Core 
       FIG. 1  to  FIG. 3  illustrates an example configuration of a stacked rotor core  1  (stacked core). The stacked rotor core  1  is part of a rotor. The rotor may be formed by attaching end lace plates and a shaft to the stacked rotor core  1 . By assembling the rotor with a stator, a motor is formed. 
     As depicted in  FIG. 1 , the stacked rotor core  1  includes a stack  10 , a plurality of permanent magnets  12 , and a plurality of solidified resins  14 . 
     The stack  10  has a cylindrical shape as depicted in  FIG. 1 . A shaft hole  10   a  penetrating the stack  10  in a height direction of the stack  10  (hereinafter, simply called “height direction”) is formed in a central portion of the stack  10 . In some examples, the shaft hole  10   a  extends along a central axis Ax of the stack  10 . The stack  10  is rotated about the central axis Ax, and thus the central axis Ax is also a rotation axis. A shaft may be inserted into the shaft hole  10   a.    
     A plurality of magnet insertion holes  16  are formed in the stack  10 . As depicted in  FIG. 1 , the magnet insertion holes  16  are aligned along the outer periphery of the stack  10  at predetermined intervals. As depicted in  FIG. 2 , the magnet insertion holes  16  penetrate the stack  10  so as to extend along the central axis Ax. In some examples, the magnet insertion holes  16  extend in the height direction. 
     Each magnet insertion hole  16  has the shape of an oblong hole extending along the outer periphery of the stack  10 . The number of the magnet insertion holes  16  may be six in some examples. The positions, the shapes, and the number of the magnet insertion holes  16  may be changed based on intended use and/or to selectively vary the performance, for example, of the motor. 
     The stack  10  is formed by stacking a plurality of blanked members W Each blanked member W is a plate-like member obtained by blanking an electrical steel sheet ES (described in further detail later) in a predetermined shape, and has a shape corresponding to the shape of the stack  10 . In some examples, a blanked member located at the lowermost layer of the blanked members W forming the stack  10  may be referred to as “blanked member W 2 ” or “first blanked member”, and the blanked members located at layers other than the lowermost layer of the blanked members W forming the stack  10  may be referred to as “blanked member(s) W 1 ” or “second blanked member(s)”. 
     The stack  10  may be formed by what is called a rotational stack. The term “rotational stack” may be understood to refer to stacking a plurality of blanked members W while relatively shifting the angle between the blanked members W. The rotational stack may be performed to compensate for variations in thickness of the stack  10 . The angle of rotational stack may be set at any angle. 
     Blanked members W adjacent to each other in the height direction are fastened together by interlocking parts  18  as depicted in  FIG. 1  to  FIG. 3 . For example, each interlocking part  18  includes tabs (connecting tabs)  20  formed in the blanked member W 1  and a through hole  22  formed in the blanked member W 2  as depicted in  FIG. 2  and  FIG. 3 . 
     Each connecting tab  20  has a depression  20   a  formed in a blanked member W 1  on its upper-surface side and a projection  20   b  formed on the blanked member W 1  on its lower-surface side. When viewed from the X-axis direction in  FIG. 3 , each connecting tab  20  as a whole has a chevron shape. For example, the swaged area of the connecting tab  20  has a tip  24  where the protruding height of the projection  20   b  is greatest and shoulders  26  that are located on both sides of the tip  24  in the Y-axis direction, as shown in  FIG. 3 . In some examples, the tip  24  has a flat shape. The protruding height of each shoulder  26  gradually decreases from the tip  24  to the outside in the Y-axis direction, as shown in  FIG. 3 . The connecting tab  20  having such a shape may be referred to as “V-shaped tab”. 
     Each depression  20   a  of one blanked member W 1  is joined to the corresponding projection  20   b  of another blanked member W 1  that is adjacent to the one blanked member W 1  on its upper-surface side. Each projection  20   b  of the one blanked member W 1  is joined to the corresponding depression  20   a  of still another blanked member W 1  that is adjacent to the one blanked member W 1  on its lower-surface side. 
     Each through hole  22  may have a rectangular shape as depicted in  FIG. 3 . In some examples, the through hole  22  has the shape of an oblong hole extending in the Y-axis direction in  FIG. 3 . The length A 1  of the longer sides (in the Y-axis direction) of the through hole  22  may be approximately 3 millimeters to 5 millimeters, for example. The width B 1  of the shorter sides (in the X-axis direction) of the through hole  22  may be approximately 0.5 millimeter to 2 millimeters, for example. 
     In respective central portions of the pair of longer sides of the through hole  22 , notches  28  are formed. The notches  28  are recessed from the central portions of the through hole  22  outward in the X direction in  FIG. 3 . For example, the through hole  22  formed in a first blanked member may include an area having a length that is greater than a width, and the connecting tab  20  having a chevron shape may be formed in a second blanked member so as to be fitted into the through hole  22  of the first blanked member. On opposite sides of the through hole  22 , the notches  28  may be recessed outward from an inner-wall surface of the through hole  22  in opposing directions that correspond to the width of the area of the through hole  22 . Each notch  28  may have a rectangular shape. The length A 2  of the notch  28  in the longitudinal direction (Y-axis direction in  FIG. 3 ) of the through hole  22  is set shorter than the length A 1 . The length A 2  may be substantially the same as or greater than the length A 3  of the tip  24  of the connecting tab  20 , or may be set to about ⅓ of the length A 1 . The width B 2  of the notch  28  in the lateral direction (X-axis direction in  FIG. 3 ) of the through hole  22  may be set equal to or greater than a distance that is the sum of a clearance CL between a die hole D 2   a  and a punch P 2  (described later in further detail) and 5 micrometers. For example, the width B 2  may be equal to or greater than 15 micrometers, or may be approximately 15 micrometers to 20 micrometers. 
     The corresponding projection  20   b  of a blanked member W 1  adjacent to the blanked member W 2  is fitted into each through hole  22 . When stacks  10  are successively manufactured, the through hole  22  may be configured to prevent a subsequently formed blanked member W from being fastened by the corresponding connecting tab  20  (projection  20   b ) to an already manufactured stack  10 . 
     As depicted in  FIG. 3 , outer surfaces of the shoulders  26  of the connecting tab  20  are brought into contact with partial areas R (areas shaded with dots in  FIG. 3 ) of inner-wall surfaces of the through hole  22 , whereby the connecting tab  20  is fitted into the through hole  22 . When the connecting tab  20  is fitted into the through hole  22 , the tip  24  of the connecting tab  20  passes by the notches  28 . Thus, outer surfaces of the tip  24  do not come in contact with the inner-wall surfaces of the through hole  22 . 
     The permanent magnets  12  may be individually inserted into the magnet insertion holes  16  as depicted in  FIG. 1  and  FIG. 2 . Each permanent magnet  12  may be formed in a variety of different shapes, for example, a rectangular parallelepiped shape. The type of the permanent magnet  12  that is selected for the stacked rotor core  1  may be determined according to the applications of the motor, and/or to selectively vary the performance of the motor, and the like. The permanent magnets  12  may include, for example, sintered magnets or bonded magnets. 
     The solidified resin  14  is produced by charging a resin material in a melted state (melted resin) into the magnet insertion, hole  16  having the permanent magnet  12  and then solidifying the melted resin. The solidified resin  14  may be configured to fix the permanent magnet  12  in the magnet insertion hole  16  and to bond adjacent blanked members W in the height direction. Examples of resin material forming each solidified resin  14  include a thermosetting resin and a thermoplastic resin. Specific examples of the thermosetting resin include resin compositions containing an epoxy resin, a curing initiator, and an additive. Examples of the additive include a filler, a flame retardant, and a stress-lowering agent. 
     Manufacturing Device for Stacked Rotor Core 
     An example manufacturing device  100  for the stacked rotor core  1  is described with reference to  FIG. 4  to  FIG. 10 . 
     As depicted in  FIG. 4 , the manufacturing device  100  may be configured to manufacture the stacked rotor core  1  from an electrical steel sheet ES (workpiece sheet) that is a belt-like metal sheet. The manufacturing device  100  includes an uncoiler  110 , a feeder  120 , a blanking device  130 , a magnet mounting device (not depicted), and a controller  140  (control unit). 
     The uncoiler  110  rotatably supports a coiled material  111  that is a belt-like electrical steel sheet ES wound in a coiled shape, with the coiled material  111  being mounted thereon. The feeder  120  has a pair of rollers  121  and  122  configured to sandwich the electrical steel sheet ES from above and below. The pair of rollers  121  and  122  rotates and stops rotating in response to instruction signals from the controller  140 , thereby sequentially feeding the electrical steel sheet ES toward the blanking device  130  on an intermittent basis. 
     The blanking device  130  operates in response to instruction signals from the controller  140 . The blanking device  130  may be configured to sequentially blank, with a plurality of punch units, the electrical steel sheet ES that is fed by the feeder  120  on an intermittent basis to form a blanked member W and to sequentially stack blanked members W obtained by the blanking to produce a stack  10 . 
     The blanking device  130  includes a base  131 , a lower die  132 , a die plate  133 , a stripper  134 , an upper die  135 , a top plate  136 , a press machine  137  (drive unit), and a plurality of punches. 
     The base  131  is installed on a floor, and supports the lower die  132  placed on the base  131 . The lower die  132  holds the die plate  133  placed on the lower die  132 . The lower die  132  includes discharge holes at predetermined positions. The discharge holes discharge materials (e.g., blanked members W, waste materials) that have been blanked from the electrical steel sheet ES. 
     The die plate  133  may be configured to form a blanked member W in conjunction with the punches. The die plate  133  includes dies at positions corresponding to the respective punches. Each die has a die hole into which the corresponding punch can be inserted. 
     The stripper  134  may be configured to clamp the electrical steel sheet ES between the stripper  134  and the die plate  133  when the electrical steel sheet ES is blanked with the respective punches and to remove the electrical steel sheet ES sticking to the respective punches from the respective punches. The upper die  135  is positioned above the stripper  134 . On the upper die  135 , base end portions of the respective punches are fixed. Thus, the upper die  135  holds the respective punches. 
     The top plate  136  is positioned above the upper die  135 . The top plate  136  holds the upper die  135 . The press machine  137  is positioned above the top plate  136 . A piston of the press machine  137  is connected to the top plate  136 , and operates in response to instruction signals from the controller  140 . When the press machine  137  operates, the piston elongates and contracts, thereby moving all of the stripper  134 , the upper die  135 , the top plate  136 , and the respective punches up and down. 
     The magnet mounting device operates in response to instruction signals from the controller  140 . The magnet mounting device may be configured to insert the permanent magnets  12  into the respective magnet insertion holes  16  of a stack  10  obtained by the blanking device  130  and to charge melted resin into the magnet insertion holes  16  into which the permanent magnets  12  have been inserted. 
     For example, based on a program stored in a recording medium or based on an operation input from an operator, the controller  140  generates an instruction signal for operating one or more of the feeder  120 , the blanking device  130 , and the magnet mounting device, and transmits the instruction signal to the corresponding one of the feeder  120 , the blanking device  130 , and the magnet mounting device. 
     The punches and the dies included in the blanking device  130  are described in more detail with reference to  FIG. 5A  to  FIG. 9 . The blanking device  130  includes punch units P 10 , P 20 , and P 30 , for example. 
     The punch unit P 10  (first punch unit) may be configured to form a through hole  22  in the blanked member W 2 . The punch unit P 10  includes a combination of a punch Pi (first punch) and a die D 1  (first die) as depicted in  FIG. 5A ,  FIG. 5B  and  FIG. 7A . 
     In the die D 1 , a die hole D 1   a  (first die hole) is formed as depicted in  FIG. 5B . The die hole D 1   a  may have a rectangular shape. In some examples, the die hole D 1   a  has the shape of an oblong hole extending in the Y-axis direction in  FIG. 5B . The length A 11  of the longer sides of the die hole D 1   a  is substantially the same as the length A 1  of the longer sides of each through hole  22 , and may be approximately 3 millimeters to 5 millimeters, for example. The width B 11  of the shorter sides of the die hole D 1   a  is substantially the same as the width B 1  of the shorter sides of the through hole  22 , and may be approximately 0.5 millimeter to 2 millimeters, for example. 
     In respective central portions of this pair of longer sides of the die hole D 1   a , notches D 1   b  are formed. The notches D 1   b  are recessed from the central portions of the die hole D 1   a  outward in the X direction in  FIG. 5B . For example, the die hole D 1   a  formed in the die D 1  may include an area having a length that is greater than a width. On opposite sides of the die hole D 1   a , the notches D 1   b  may be recessed outward from an inner-wall surface of the die hole D 1   a  in opposing directions that correspond to the width of the area of the die hole D 1   a . Each notch D 1   b  may have a rectangular shape. The length A 12  of the notch D 1   b  in the longitudinal direction (Y-axis direction in  FIG. 5B ) of the die hole D 1   a  is substantially the same as the length A 2 , and is set shorter than the length A 11 . The length A 12  may be set to about ⅓ of the length A 11 . The width B 12  of the notch D 1   b  in the lateral direction (X-axis direction in  FIG. 5B ) of the die hole D 1   a  may be set equal to or greater than a distance that is the sum of the clearance CL between the die hole D 2   a  and the punch P 2  (described later in further detail) and 5 micrometers. The width B 12  is substantially the same as the width B 2 , and may be equal to or greater than 15 micrometers, for example, or may be approximately 15 micrometers to 20 micrometers. 
     As depicted in  FIG. 5A , the punch P 1  has a rectangular parallelepiped shape corresponding to the shape of the die hole D 1   a . The punch P 1  has a pair of ridges P 1   a  located on opposite sides of the punch P 1 . The pair of ridges P 1   a  is positioned in the respective central portions of the opposite sides in the lateral direction of the punch P 1 . Each ridge P 1   a  has a rectangular parallelepiped shape corresponding to the shape of notch D 1   b . As depicted in  FIG. 7A , the punch P 1  is configured to be insertable into and removable from to the die hole D 1   a  through a through hole  134   a  of the stripper  134 . 
     The punch unit P 20  (second punch unit) may be configured to form a connecting tab  20  in a blanked member W 1 . As depicted in  FIG. 6A ,  FIG. 6B  and  FIG. 7B , the punch unit P 20  includes a combination of the punch P 2  (second punch) and a die D 2  (second die). 
     As depicted in  FIG. 6B , the die hole D 2   a  (second die hole) is formed in the die D 2 . The die hole D 2   a  has a rectangular shape. The size of the die hole D 2   a  may be substantially the same as the size of the die hole D 1   a.    
     As depicted in  FIG. 6A , the punch P 2  has a rectangular parallelepiped shape corresponding to the shape of the die hole D 2   a . As depicted in  FIG. 7B , the punch P 2  is configured to be insertable into and removable from the die hole D 2   a  through a through hole  134   b  of the stripper  134 . As depicted in  FIG. 7B , the outer shape of the punch P 2  is set slightly smaller than the outer shape of the die hole D 2   a . The clearance CL between the die hole D 2   a  and the punch P 2  can be set to various values depending on fitting force intended to be generated between each connecting tab  20  and the corresponding through hole  22 , and may be approximately 10 micrometers to 20 micrometers, or may be approximately 10 micrometers to 15 micrometers, for example. A clearance CL exceeding 20 micrometers may complicate fitting of the projection  20   b  of the connecting tab  20  into the depression  20   a.    
     A distal-end portion P 2   a  of the punch P 2  as a whole has a chevron shape. In some examples, the distal-end portion P 2   a  has a tip P 2   b  where the protruding height is greatest and shoulders P 2   c  that are located on both sides of the tip P 2   b  in the Y-axis direction in  FIG. 6A . The tip P 2   b  may have a flat shape. For example, the length A 12  of the notch D 1   b  may be substantially the same as or greater than the width A 13  of the tip P 2   b  in the Y-axis direction, as illustrated in  FIG. 5A . The protruding height of each shoulder P 2   c  gradually decreases from the tip P 2   b  to the outside in the Y-axis direction in  FIG. 6A . 
     The punch unit P 30  (third punch unit) may be configured to blank the electrical steel sheet ES to form a blanked member W. As depicted in  FIG. 8 , the punch unit P 30  includes a combination of a punch P 3  (third punch) and a die D 3  (third die). 
     In the die D 3 , a die hole D 3   a  (third die hole) is formed. The die hole D 3   a  has a shape corresponding to the outer shape of the blanked member W. 
     The punch P 3  has a shape corresponding to the shape of the die hole D 3   a . The punch P 3  is configured to be insertable into and removable from the die hole D 3   a  through a through hole  134   c  of the stripper  134 . As depicted in  FIG. 9  and  FIG. 10 , on a distal-end surface of the punch P 3 , a plurality of pressing protrusions P 3   a  are formed. The pressing protrusions P 3   a  protrude from the distal-end surface in a direction intersecting the distal-end surface. The pressing protrusions P 3   a  are each formed at positions corresponding to the connecting tabs  20  formed in the electrical steel sheet ES. 
     In some examples, a cylinder  132   b , a stage  132   c , and a pusher  132   d  are disposed in a space  132   a  below the die D 3 . The cylinder  132   b  is configured to be vertically movable in response to instruction signals from the controller  140 . For example, the cylinder  132   b  moves downward intermittently every time a blanked member W is staked on the cylinder  132   b.  When a predetermined number of blanked members W have been stacked on the cylinder  132   b  to form a stack  10 , the cylinder  132   b  moves to a position where a surface of the cylinder  132   b  is flush with a surface of the stage  132   c  as depicted in  FIG. 10 . 
     In the stage  132   c , the cylinder  132   b  passes through a hole  132   e . The pusher  132   d  is configured to be horizontally movable on the surface of the stage  132   c  in response to instruction signals from the controller  140 . With the surface of the cylinder  132   b  having moved to a position where the surface of the cylinder  132   b  is flush with the surface of the stage  132   c , the pusher  132   d  pushes out the stack  10  from the cylinder  132   b  to the stage  132   c . The stack  10  pushed out to the stage  132   c  may be conveyed to a subsequent step by a conveyor, for example. 
     Method for Manufacturing Stacked Rotor Core 
     An example method for manufacturing a stacked rotor core  1  is described with reference to  FIG. 4  and  FIG. 7A  to  FIG. 10 . 
     As depicted in  FIG. 4 , the electrical steel sheet ES is fed by the feeder  120  to the blanking device  130 , and when a portion of the electrical steel sheet ES to be processed has reached a predetermined punch, the method may include the formation of a through hole corresponding to the shaft hole  10   a  (e.g., stamping at the inner circumference), and the formation of through holes corresponding to the respective magnet insertion holes  16 . Additionally, the method may include the formation of the connecting tabs  20  or through holes  22 , and blanking of a blanked member W from the electrical steel sheet ES (e.g., stamping at the outer circumference). 
     The connecting tabs  20  and the through holes  22  are selectively formed. For example, in an area of the electrical steel sheet ES where a blanked member W 1  is to be formed, the connecting tabs  20  are formed, and in an area of the electrical steel sheet ES where a blanked member W 2  is to be formed, the through holes  22  are formed. 
     An example formation of the through hole  22  is described with reference to  FIG. 7A . When the blanking device  130  operates in response to instruction signals from the controller  140 , the stripper  134  moves down toward the die plate  133 , and the electrical steel sheet ES is clamped by the die plate  133  and the stripper  134 . In this state, when the blanking device  130  further operates, the punch P 1  moves down through the through hole  134   a  of the stripper  134 , and the distal-end portion of the punch P 1  extrudes the electrical steel sheet ES into the die hole D 1   a  of the die D 1  held by the die plate  133 . Thus, the through hole  22  is formed in the electrical steel sheet ES by the punch P 1 . 
     An example formation of the connecting tab  20  is described with reference to  FIG. 7B . When the blanking device  130  operates in response to instruction signals from the controller  140 , the stripper  134  moves down toward the die plate  133 , and the electrical steel sheet ES is clamped by the die plate  133  and the stripper  134 . In this state, when the blanking device  130  further operates, the punch P 2  moves down through the through hole  134   b  of the stripper  134 , and the distal-end portion of the punch P 2  extrudes the electrical steel sheet ES into the die hole D 2   a  of the die D 2  held by the die plate  133 . Thus, the connecting tab  20  is formed in the electrical steel sheet ES by the punch P 2 . 
     An example blanking operation of the blanked member W from the electrical steel sheet ES is described with reference to  FIG. 8  to  FIG. 11 . When the blanking device  130  operates in response to instruction signals from the controller  140 , the stripper  134  moves down toward the die plate  133 , and the electrical steel sheet ES is clamped by the die plate  133  and the stripper  134 . In this state, when the blanking device  130  further operates, the punch P 3  moves down through the through hole  134   c  of the stripper  134 , and the distal-end portion of the punch P 3  is inserted into the die hole D 3   a  of the die D 3  held by the die plate  133 . Thus, the blanked member W is blanked from the electrical steel sheet ES by the punch P 3 . 
     When a blanked member W 2  is blanked from the electrical steel sheet ES by the punch P 3 , the pressing protrusions P 3   a  are inserted into the through holes  22 , and the electrical steel sheet ES is not processed. In contrast, when a blanked member W 1  is blanked from the electrical steel sheet ES by the punch P 3 , each pressing protrusion P 3   a  presses the depression  20   a  of the corresponding connecting tab  20  (see  FIG. 9 ). Thus, the projection  20   b  of the connecting tab  20  is press-fitted into the depression  20   a  of a connecting tab  20  or the through hole  22 , whereby both of them are fitted together. 
     Blanked members W blanked from the electrical steel sheet ES by the punch P 3  are stacked on the cylinder  132   b , whereby a stack  10  is formed as depicted in  FIG. 8 . As depicted in  FIG. 10 , the stack  10  is pushed out by the pusher  132   d  from the cylinder  131   b  to the stage  132   c . Subsequently, the magnet mounting device charges permanent magnets  12  and melted resin into the magnet insertion holes  16  of the stack  10 , and the permanent magnets  12  are fixed in the magnet insertion holes  16  by the solidified resins  14 . Thus, a stacked rotor core  1  is completed. 
     It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted. 
     For example, the notches D 1   b  formed in the die hole D 1   a  may have a shape (e.g., triangular shape, trapezoidal shape, semispherical shape, or arched shape) other than the rectangular shape. 
     A group of magnets including two or more permanent magnets  12  in combination may be inserted into one magnet insertion hole  16 . For example, a plurality of permanent magnets  12  may be arranged in the longitudinal direction of one magnet insertion hole  16 . Additionally, a plurality of permanent magnets  12  may be arranged in the height direction of the one magnet insertion hole  16 . Still further, a first set of permanent magnets  12  may be arranged in the longitudinal direction of the one magnet insertion hole  16  and a second set of permanent magnets  12  may be arranged in the height direction. 
     One or more of the methods, procedures, steps or operations described here may be applied not only to the stacked rotor core  1  but also a stacked stator core. In some examples, the stacked stator core may be a segmented stacked stator core formed with a plurality of core pieces in combination, or may be an unsegmented stacked stator core. 
     Additional Examples 
     If the notches  28  are not formed in the through hole  22 , as depicted in  FIG. 11 , when the projection  20   b  of a connecting tab  20  is fitted into the through hole  22 , the projection  20   b  may rub on an inner-wall surface of the through hole  22 , thereby causing a burr Wa to be formed inside the through hole  22 . When a motor is configured with a stacked rotor core  1  including a blanked member W having such a burr Wa, vibrations and centrifugal force, for example, are applied to the burr Wa when the motor operates, which may cause the burr Wa to fall off. Consequently, the, burr Wa may hit components of the motor, whereby an unusual noise may be generated from the motor, and performance of the motor may be adversely affected. As the development of hybrid vehicles and electric vehicles has progressed, the number of vehicles having a motor as a drive source is rapidly increasing. Thus, there is an increasing demand for vehicle-mounted motors having a higher level of safety. 
     An example stacked core ( 1 ) may include a stack ( 10 ) formed by stacking a plurality of blanked members (W). The plurality of blanked members (W) include a first blanked member (W 2 ) forming an outermost layer of the stack ( 10 ) in a height direction and a second blanked member (W 1 ) adjacent to the first blanked member (W 2 ). A through hole ( 22 ) having the shape of an oblong hole is formed in the first blanked member (W 2 ). Additionally, a connecting tab ( 20 ) having a chevron shape formed so as to be fitted into the through hole ( 22 ) and protruding toward the through hole ( 22 ) is formed in the second blanked member (W 1 ). Notches ( 28 ) that are recessed outward in an opposing direction of a pair of longer sides of the through hole ( 22 ) are formed in respective central portions of the longer sides of the through hole ( 22 ). For example, the through hole ( 22 ) formed in a first blanked member may include a through hole area having a length that is greater than a width, and the connecting tab ( 20 ) having a chevron shape may be formed in a second blanked member so as to be fitted into the through hole ( 22 ) of the first blanked member. On opposite sides of the through hole ( 22 ), the notches ( 28 ) may be recessed outward from an inner-wall surface of the through hole ( 22 ) in opposing directions that correspond to the width of the through hole area. When this V-shaped tab ( 20 ) is press-fitted into the through hole ( 22 ), a vicinity of a tip ( 24 ) of the connecting tab ( 20 ) passes by the notches ( 28 ), and is accordingly less likely to come into contact with the inner-wall surfaces of the through hole ( 22 ). Thus, the protrusion of the connecting tab ( 20 ) becomes less likely to substantially rub against the inner-wall surfaces of the through hole ( 22 ), whereby the formation of burrs can be reliably prevented. Additionally, when V-shaped tab ( 20 ) is press-fitted into the through hole ( 22 ), the shoulders ( 26 ) and vicinity of a projection ( 20   b ) of the connecting tab ( 20 ) come into contact with the inner-wall surfaces of the through hole ( 22 ). This causes the connecting tab ( 20 ) and the through hole ( 22 ) to be fitted together. Accordingly, the connecting tab ( 20 ) and the through hole ( 22 ) can be fitted together, and also the formation of burrs can be prevented in a very simple manner with the notches ( 28 ). 
     In some examples, the tip ( 24 ) of the connecting tab ( 20 ) may have a flat shape, and the length (A 2 ) of each notch ( 28 ) in a longitudinal direction of the through hole ( 22 ) may be equal to or greater than the width (A 3 ) of the tip ( 24 ) of the connecting tab ( 20 ) in a direction corresponding to the longitudinal direction. In this case, a vicinity of the tip ( 24 ) of the connecting tab ( 20 ) is still less likely to come in contact with the inner-wall surfaces of the through hole ( 22 ). Thus, the formation of burrs can be more reliably prevented. 
     In some examples, the width (B 2 ) of each notch ( 28 ) in the opposing direction may be equal to or greater than 15 micrometers. Additionally, the clearance (CL) between a die hole (D 2   a ) and a punch (P 2 ) that are used for forming the connecting tab ( 20 ) may be set equal to or greater than 10 micrometers. In some examples, the width (B 2 ) of the notch  28  is set to a distance exceeding the clearance (CL). Thus, even if a vicinity of the tip ( 24 ) of the connecting tab ( 20 ) is pushed out into the notches ( 28 ) when the connecting tab ( 20 ) is press-fitted into the through hole ( 22 ), this vicinity is less likely to come into contact with the inner-wall surfaces of the notches ( 28 ). Thus, the formation of burrs can be more reliably prevented. 
     In some examples, each notch ( 28 ) may have a rectangular shape when viewed from the height direction e.g., when viewed from above). A punch (P 1 ) having a shape corresponding to contours of the through hole ( 22 ) and the notch ( 28 ) can be easily formed. 
     An example device ( 100 ) for manufacturing a stacked core may include a first punch unit (P 10 ) configured to form a through hole ( 22 ) in a belt-like metal sheet (ES), a second punch unit (P 20 ) configured to form a connecting tab ( 20 ) in the metal sheet (ES), and a third punch unit (P 30 ) configured to blank the metal sheet (ES) to form a blanked member (W). Additionally, the example device ( 100 ) may include a drive unit ( 137 ) configured to drive the first to third punch units (P 10  to P 30 ), and a control unit ( 140 ). The first punch unit (P 10 ) includes a first die (D 1 ) in which a first die hole (D 1   a ) having the shape of an oblong hole is formed. Additionally, the first punch unit (P 10 ) may include a first punch (P 1 ) having a shape corresponding to the shape of the first die hole (D 1   a ) and configured to be insertable into and removable from the first die hole (D 1   a ). In some examples, notches (D 1   b ) recessed outward in an opposing direction of a pair of longer sides are formed in respective central portions of the longer sides of the first die hole (D 1   a ). The second punch unit (P 20 ) includes a second die (D 2 ) in which a second die hole (D 2   a ) having the shape of an oblong hole is formed. Additionally, the second punch unit (P 20 ) may include a second punch (P 2 ) having a shape corresponding to the shape of the second die hole (D 2   a ) and configured to be insertable into and removable from the second die hole (D 2   a ). The second punch (P 2 ) has a chevron shape tapering toward its distal end. The third punch unit (P 30 ) includes a third die (D 3 ) in which a third die hole (D 3   a ) having a shape corresponding to the outer shape of the blanked member (W) is formed. Additionally, the third punch unit (P 30 ) may include a third punch (P 3 ) having a shape corresponding to the shape of the third die hole (D 3   a ) and configured to be insertable into and removable from the third die hole (D 3   a ). The control unit ( 140 ) is configured to control the first punch unit (P 10 ) to form the through hole ( 22 ) in the metal sheet (ES), and to control the third punch unit (P 30 ) to blank a first blanked member (W 2 ) having the through hole ( 22 ) from the metal sheet (ES). Additionally, the control unit ( 140 ) may be configured to control the second punch unit (P 20 ) to form the connecting tab ( 20 ) in the metal sheet (ES), and to control the third punch unit (P 30 ) to blank a second blanked member (W 1 ) having the connecting tab ( 20 ) from the metal sheet (ES) and also to fit the connecting tab ( 20 ) into the through hole ( 22 ), thereby stacking the first and second blanked members (W 2 , W 1 ). 
     In some examples, a tip (P 2   b ) of the second punch (P 2 ) has a flat shape, and the length (A 12 ) of each notch (D 1   b ) in a longitudinal direction of the first die (D 1 ) may be equal to or greater than the width (A 13 ) of the tip (P 2   b ) of the second punch (P 2 ) in a direction corresponding to the longitudinal direction. 
     In some examples, the width (B 12 ) of each notch (D 1   b ) in the opposing direction may be equal to or greater than the sum of a clearance (CL) between the second die hole (D 2   a ) and the second punch (P 2 ) and 5 micrometers. 
     In some examples, each notch (D 1   b ) may have a rectangular shape when viewed from an insertion direction of the first punch (P 1 ) into the first die hole (D 1   a ). 
     An example method for manufacturing a stacked core ( 1 ) may include forming a through hole ( 22 ) in a belt-like metal sheet (ES) by inserting, into a first die hole (D 1   a ) having the shape of an oblong hole, a first punch (P 1 ) having a shape corresponding to the shape of the first die hole (D 1   a ). Additionally, the example method may include forming a connecting tab ( 20 ) in the metal sheet (ES) by inserting, into a second die hole (D 2   a ) having the shape of an oblong hole, a second punch (P 2 ) having a shape corresponding to the shape of the second die hole (D 2   a ) and having a chevron shape tapering toward its distal end. A first blanked member (W 2 ) having the through hole ( 22 ) may be blanked from the metal sheet (ES) by inserting, into a third die hole (D 3   a ) having a predetermined shape, a third punch (P 3 ) having a shape corresponding to the shape of the third die hole (D 3   a ). Additionally, by inserting the third punch (P 3 ) into the third die hole (D 3   a ), a second blanked member (W 1 ) having the connecting tab ( 20 ) may be blanked from the metal sheet (ES) and the connecting tab ( 20 ) may be fitted into the through hole ( 22 ) to stack the first and second blanked members (W 2 , W 1 ). In some examples, notches (D 1   b ) recessed outward in an opposing direction of the pair of long sides are formed in respective central portions of a pair of the long sides of the first die hole (D 1   a ). 
     In some examples, a tip ( 24 ) of the second punch (P 2 ) may have a flat shape, and the length (A 12 ) of each notch (D 1   b ) in a longitudinal direction of the first die (D 1 ) may be equal to or greater than the width (A 13 ) of the tip (P 2   b ) of the second punch (P 2 ) in a direction corresponding to the longitudinal direction. 
     In some examples, the width (B 12 ) of each notch (D 1   b ) in the opposing direction may be equal to or greater than the sum of a clearance (CL) between the second die hole (D 2   a ) and the second punch (P 2 ) and 5 micrometers. 
     In some examples, each notch (D 1   b ) may have a rectangular shape when viewed from an insertion direction of the first punch (P 1 ) into the first die hole (D 1   a ). 
     We claim all modifications and variations coming within the spirit and scope of the subject matter claimed herein.