Die assembly and method for manufacturing wound motor laminated article

Abstract

A metal article, such as a stator core, is formed from a continuous strip of wound sheet stock material including winding slot cutouts. The winding slot cutouts are maintained at a substantially constant width throughout most of the radial extent of the winding slots in the finished article, except that one or more of the first and/or last wound layers (i.e., the radially innermost and radially outermost layers) may define winding slot cutouts that are wider than the other winding slot cutouts. Several radial layers may define cutout widths that are progressively expanded such that the resulting winding slot has terminal ends with edges that defining a stair-step profile that approximates a “radiused” or rounded edge. This rounded edge profile protects windings projecting radially into or outwardly from the winding slots near the edge of such slots.

What is claimed is: 
     
         1 . A stator core comprising:
 a central opening bounded at its periphery by an innermost layer having at least one innermost winding slot cutout defining an innermost cutout width;   an outermost layer radially spaced from said innermost layer and having at least one outermost winding slot cutout defining an outermost cutout width; and   a main stator body comprising a plurality of intermediate layers between said innermost layer and said outermost layer, each of said plurality of intermediate layers having at least one intermediate winding slot cutout defining an intermediate cutout width,   said innermost layer, said outermost layer and said intermediate layers formed from a continuous strip of wound material such that said innermost winding slot cutout, said outermost winding slot cutout and said intermediate winding slot cutouts are respectively aligned with one another to form a winding slot, and   at least one of said innermost cutout width and said outermost cutout width is larger than said intermediate cutout width, whereby said winding slot defines a stair-step profile approximating a rounded edge at a radial end of said winding slot.   
     
     
         2 . The stator core of  claim 1 , wherein:
 said innermost cutout width is larger than said intermediate cutout width; and   said outermost cutout width is larger than said intermediate width,   such that each radial end of said winding slot defines said stair-step profile approximating a rounded edge.   
     
     
         3 . The stator core of  claim 1 , further comprising a plurality of outer layers disposed between said outermost layer and said plurality of intermediate layers, wherein:
 each of said plurality of outer layers respectively defining a plurality of outer cutouts aligned with and forming a portion of said winding slot, and   said plurality of outer cutouts defining progressively smaller outer cutout sizes as said plurality of outer layers progresses radially inwardly, such that said stair-step profile more closely approximates a rounded edge at the radial outer end of said winding slot.   
     
     
         4 . The stator core of  claim 3 , wherein a width difference between neighboring pairs of said outer cutouts along said winding slot is one of:
 progressively smaller than a corresponding width difference between each other neighboring pair of said outer cutouts;   progressively larger than a corresponding width difference between each other neighboring pair of said outer cutouts; and   substantially equal to a corresponding width difference between each other neighboring pair of said outer cutouts.   
     
     
         5 . The stator core of  claim 1 , further comprising a plurality of inner layers disposed between said innermost layer and said plurality of intermediate layers, wherein:
 each of said plurality of inner layers respectively defining a plurality of inner cutouts aligned with and forming a portion of said winding slot, and   said plurality of inner cutouts defining progressively smaller inner cutout sizes as said plurality of inner layers progresses radially outwardly, such that said stair-step profile more closely approximates a rounded edge at the radial inner end of said winding slot.   
     
     
         6 . The stator core of  claim 5 , wherein a width difference between neighboring pairs of said inner cutouts along said winding slot is one of:
 progressively smaller than a corresponding width difference between each other neighboring pair of said outer cutouts;   progressively larger than a corresponding width difference between each other neighboring pair of said outer cutouts; and   substantially equal to a corresponding width difference between each other neighboring pair of said outer cutouts.   
     
     
         7 . The stator core of  claim 1 , wherein said innermost cutout width and said outermost cutout width are both larger than said intermediate cutout width, whereby said winding slot defines a stair-step profile approximating a rounded edge at both an inner and outer radial ends of said winding slot. 
     
     
         8 . The stator core of  claim 1 , wherein said innermost winding slot cutout, said outermost winding slot cutout and said intermediate winding slot cutouts each define a cutout geometry substantially equivalent to one another, whereby sidewalls at respective sides of each said cutout have a corresponding sidewall profile. 
     
     
         9 . A production machine comprising:
 a punch and die assembly comprising:
 an upper punch assembly comprising a plurality of punches longitudinally arranged with respect to one another along a first direction; 
 a lower die assembly configured to cooperate with said plurality of punches of said upper punch assembly to punch a plurality of lamina features into a strip of material, said lamina features substantially within the plane of the strip of material; 
 a material feed path passing between the upper punch assembly and the lower die assembly, such that the plurality of punches are selectively engageable with the material feed path to selectively punch one of the plurality of lamina features into the strip of material as the strip of material moves along a material feed path direction; 
   a rewinding apparatus positioned downstream of said punch and die assembly, said rewinding apparatus rotatable to take up material from said material feed path after the lamina features are punched into the strip of material.   
     
     
         10 . The production machine of  claim 9 , wherein said first direction is transverse to said material feed path direction. 
     
     
         11 . The production machine of  claim 9 , wherein said first direction is aligned with said material feed path direction. 
     
     
         12 . The production machine of  claim 9 , wherein each punch of said plurality of punches is sized differently from every other punch in said plurality of punches. 
     
     
         13 . The production machine of  claim 12 , wherein each punch defines a width, each said width differing from every other said width. 
     
     
         14 . The production machine of  claim 13 , wherein a difference between each neighboring pair of widths is one of:
 progressively smaller than a corresponding difference between each other neighboring pair of said widths;   progressively larger than a corresponding difference between each other neighboring pair of said widths; and   substantially equal to a corresponding difference between each other neighboring pair of said widths.   
     
     
         15 . The production machine of  claim 13 , wherein each said width is defined by a respective pair of opposing die sides of a plurality of dies, each said pair of opposing die sides defining a cutout profile substantially equivalent to a corresponding cutout profile defined by each other said pair of opposing die sides. 
     
     
         16 . A method of producing a wound article from a strip of material, the method comprising:
 feeding a strip of bulk material to a punch and die assembly;   punching a plurality of winding slot cutouts into the strip of material to create a formed material; and   winding the formed material around itself such that a substantially cylindrical structure is created, the plurality of winding slot cutouts selectively aligned with one another to create at least one winding slot in the substantially cylindrical structure,   wherein said step of punching the plurality of winding slot cutouts comprises punching a cutout having a first cutout size at intermediate radial layers of the substantially cylindrical structure and a second cutout size for at least one of a radially innermost and radially outermost layers of the substantially cylindrical structure,   the second cutout size greater than the first cutout size such that at least one axial end of the winding slot defines a stair-step profile approximating a rounded corner.   
     
     
         17 . The method of  claim 16 , wherein said punch and die assembly comprises a movable punch and die assembly having at least a first die and a second die, and said punching step further comprises:
 aligning the first die with the strip of material;   punching a first series of winding slot cutouts having the first cutout size defined by said first die;   moving the movable punch and die assembly such that said second die becomes aligned with the strip of material; and   punching a second series of winding slot cutouts having the second cutout size defined by the second die.   
     
     
         18 . The method of  claim 17 , wherein:
 said step of feeding the strip of bulk material comprises feeding the strip of material in a first direction; and   said step of moving of the punch and die assembly comprises moving the punch and die assembly in a second direction transverse to the first direction.   
     
     
         19 . The method of  claim 17 , wherein:
 said step of feeding the strip of material comprises feeding the strip of material in a first direction; and   said step of moving of the punch and die assembly comprises moving the punch and die assembly in a second direction aligned with the first direction.   
     
     
         20 . The method of  claim 16 , wherein the first cutout size defines a first cutout profile that is substantially equivalent to a corresponding second cutout profile defined by the second cutout size.