Patent Publication Number: US-2016248305-A1

Title: Production method for large rotor/stator laminations

Description:
BACKGROUND 
     In the prior art, electrical steel in core form is available in widths up to 48 inches. Motor or generator cores have a stator and a rotor, each formed from a plurality of stack laminations referred to also herein as lamination layers. Core from widths of up to 48 inches allows for state of production in a complete round form up to that size. For larger stators, like those typically seen in large generator or motor applications, each of the lamination layers of the stator must be produced in an arc segment form. 
     In U.S. Pat. No. 8,082,654, incorporated herewith by reference, issued Dec. 27, 2011, inventor—Mark Bender, it was known to manufacture a lamination for a motor or generator by using a plurality of laminations to form a core of the stator, or rotor, or both stator and a rotor of a motor or generator. A material strip was provided of electrical steel having a width substantially corresponding to half of the outer diameter of the lamination to be created. Slant cuts were made along the material strip to form oppositely facing trapezoids of substantially a same area. Two of the trapezoids were joined together along a side edge of each to form a hexagon. The joining could be accomplished by a welding process. The lamination was then stamped from the hexagon. 
     SUMMARY 
     It is an object to improve upon the process of the aforementioned &#39;654 patent to provide a manufacturing method which utilizes relatively narrow steel strips to manufacture relatively large stator and rotor laminations and to minimize scrap in the manufacturing method. 
     In a method for forming at least one of a circular rotor or stator lamination, at least one or two electrical strips of lamination material are provided. At least one or two of the strips are cut into segments. At least three of the segments are connected together to form a polygon having all equal sides. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1F  illustrate a first exemplary embodiment of an improved production method for large rotor/stator laminations; 
         FIGS. 2A-2F  illustrate a second exemplary embodiment of an improved production method for large rotor/stator laminations; 
         FIGS. 3A-3E  illustrate a third exemplary embodiment of an improved production method for large rotor/stator laminations; 
         FIGS. 4A-4D  illustrate a fourth exemplary embodiment of an improved production method for large rotor/stator laminations; and 
         FIGS. 5A-5D  illustrate a fifth exemplary embodiment of an improved production method for large rotor/stator laminations. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to preferred exemplary embodiments/best mode illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and such alterations and further modifications in the illustrated embodiments and such further applications of the principles of the invention as illustrated as would normally occur to one skilled in the art to which the invention relates are included herein. 
     A first embodiment method for the improved production method for large rotor/stator laminations will now be described in connection with  FIGS. 1A-1F . 
     As shown in  FIG. 1A , a first strip of electrical steel  10  is cut such as by shearing to create individual equal size rectangles  11  at cut lines  12  running perpendicular to longitudinal extent of the strip  10 . 
     An additional electrical steel strip  9  having a same or similar electrical characteristics as strip  10  is also provided. Strip  9  is cut into individual oppositely facing triangles  13  and  14  which are all identical by cutting along cut lines  15  and  16 . 
     As illustrated in  FIG. 1C , one of the rectangles  11  is attached such as by welding with two of the triangles  13  and  14  at opposite long sides of the rectangle  11 . Although triangles  13  and  14  are indicated, two of the identical triangles  13  or two of the identical triangles  14  could also be used at the opposite sides. The triangles are welded together, or attached by some other technique (as is also true for the second through fifth embodiments described hereafter), to the rectangle along joint lines  7  and  8 . The triangles have respective angles  16  and  17  of 30° and a large angle  18  of 120°. 
     An electrical steel hexagon  19  is thus formed where the six sides  20  all have an equal length. This equal length results from an appropriate choice of the dimensions of the rectangle  11  and the dimensions of the triangles  13 ,  14  to achieve the hexagon  19  having the equal side lengths  20 . By providing equal side lengths, the hexagon  19  can accommodate a circular stamping where edges of the hexagon are substantially tangent at six edge points of the circle. Thus when stamping occurs, scrap is minimized. It should be further noted that in cutting the strips  9  and  10  substantially no scrap is created. Thus the method minimizes manufacturing cost. It should further be noted that only three pieces are used to construct the hexagon  19 . 
     As shown in  FIG. 1D , the hexagon  19  is stamped to create a stator  21  by stamping along dashed line circles  23  and  24  to create the stator  21  of  FIG. 1E , and along an additional dashed line circle  25  to create a rotor  22  as shown in  FIG. 1F . In this explanation it will be understood by those skilled in the art that other features of the rotor and stator such as the teeth  21 A and  22 A are also created by the same or separate stamping steps not described in detail here since such stamping to create teeth is well known to those skilled in the art. Waste material  26  at the center is indicated by slant lines and additional waste material  27  outwardly of the peripheral edge of the outer circle  23  is also illustrated by slant lines. The rotor has a central aperture  22   b  created by removal of the scrap  26  as shown in  FIG. 1F . 
     In summary, for the first method embodiment both the rotor and the stator are created with minimal scrap and using three pieces. Although two strips  9  and  10  are shown to create the rectangles  11  and the triangles  13 ,  14 , it is of course possible that a single strip could be used wherein both the triangles and the rectangles are cut from the same strip. However, the use of two strips as illustrated in  FIGS. 1A and 1B  is preferred for simplicity and for minimal or substantially no scrap. It should further be noted that the width W 1  of the strip  10  is defined by the length of the rectangle  11  used to create the hexagon  19 , and the width W 2  of the strip  9  is defined by the height of the triangles  13 ,  14  used to form the hexagon  19 . Thus relatively thin strips can be used to create a large rotor and large stator. 
     As further shown in  FIGS. 1E and 1F , the rotor  21  has weld lines  28 A,  28 B and  29 A,  29 B corresponding to portions of the weld lines  7  and  8  in the hexagon  19 . 
     A second embodiment of the method will now be described with respect to  FIGS. 2A-2F . Because of similarities between the first embodiment and the second embodiment method, many of the features already described in connection with the first embodiment will not be repeated for the second embodiment, also not for the third through fifth embodiments also described hereafter. 
     In  FIG. 2A , a first strip  30  is provided which is cut to create individual segments each comprising a trapezoid  31  by cutting along cut lines  32  and  33 . Cut lines  32  are parallel to each other and cut lines  33  are parallel to each other. 
     As shown in  FIG. 2B , a second strip  34  is cut or sheared to create segments comprising individual trapezoids  35 . Trapezoids  35  are longer than the trapezoids  31 . The trapezoids  35  are created by cut lines  36 ,  37 . Cut lines  36  are parallel to each other and cut lines  37  are parallel to each other. The width of strip  30  and the width of strip  34  are the same as indicated by width W 3  in  FIG. 2A . 
     In  FIG. 2C , two of the trapezoids  31  and two of the trapezoids  35  are shown welded along weld lines  36 ,  37 , and  38 . All of the trapezoids have the same height and the two central trapezoids  35  are longer than the two top and bottom trapezoids  31 . A hexagon  6  is thus formed having six sides  39  all of equal length. The trapezoids all have internal angles  40  and  41  of 60° and 120°. 
     As illustrated in  FIG. 2D , stamping circles indicated by dashed line circles  40 ,  41 , and  42  are defined, with a central area within circle  42  being scrap  43 . Outside the circle  40  are additional scrap areas  44  indicated by slant lines. 
     As indicated in  FIG. 2E  and  FIG. 2F , a stator  45  is formed by stamping dashed circles  40  and  41 , and rotor  46  is formed by stamping dashed line circles  41  and  42 . Parts of the weld lines  36 ,  37 , and  38  are visible in  FIGS. 2E and 2F . 
     A third embodiment shown in  FIGS. 3A-3E  will now be explained. As shown in  FIG. 3A , the strip  47  is slit or cut to create a plurality of equal segments comprising triangles  48  and  49 . As shown in  FIG. 3B , each triangle has equal internal angles of  60 ° as shown at  50 A,  50 B, and  50 C. The triangles are created by cutting along cut lines  51  and  52 . Cut lines  51  are all parallel to each other and cut lines  52  are all parallel to each other. The height of the triangles  48  or  49  defines the width W 4  of the strip  47 . As may be observed, there is substantially no waste in cutting the strip  47 . 
     As illustrated in  FIG. 3B , a hexagon  53  is formed of six equal length sides  54 . Six triangles  48  are used to form the hexagon  53 . The triangles used to form hexagon  53  may be a mixture of triangles  48  or  49  or all of the triangles could be triangles  49 . The triangles are welded together to form hexagon  53  along weld lines  55 ,  56 , and  57 . 
     As illustrated in  FIG. 3C , stamping occurs along dashed line circles  58 ,  59 , and  60 . A central scrap piece  61  results along with peripheral scrap pieces  62  indicated by slant lines. 
     As shown in  FIGS. 3D and 3E , a stator  63  and a rotor  64  result from stamping on the aforementioned dashed line circles  58 ,  59 , and  60 . Parts of the weld lines  55 ,  56 , and  57  may be observed in the stator  63  and rotor  64 . 
     A fourth embodiment will now be described with reference to  FIGS. 4A-4D . As illustrated in  FIG. 4A , a strip  65  has slant cuts  66  and  67  to create segments comprising trapezoids  68  which are identical to each other. Relatively small scrap regions  69  are discarded. The width W 5  of strip  65  corresponds to a height of the trapezoids  68 . 
     As shown in  FIG. 4B , the trapezoids  68  are arranged in a circle to form a hexagon  70  having six equal length sides  71 . Unlike the previous embodiments, a central open aperture is formed inside of the hexagon by the short equal length sides  72 . 
     Weld lines  5  resulting from the slant cuts  66  and  67  are also shown in  FIG. 4B . The six hexagons are thus welded together at the weld lines  5 . 
     As illustrated in  FIG. 4C , two dashed line circles  73  and  74  are defined to create the stator  75  illustrated in  FIG. 4D . Scrap regions  3  and  4  result. Unlike the first three embodiments, only a stator is stamped out of the hexagon  70 . 
     A fifth embodiment is illustrated in  FIGS. 5A-5D . Here a strip  76  is provided in which segments comprising equal size trapezoids  77  result from cut lines  78  and  79 . A width W 6  of the strip  76  matches a height of the trapezoids  77 . Resulting scrap regions  2  are discarded. 
     As shown in  FIG. 5B , a hexagon  80  having six equal length sides  81  is formed by welding together the six trapezoids at weld lines  1  formed at cut lines  78  and  79 . A central blank region is formed bounded by short equal length sides  82  of the trapezoids  80 . 
     As shown in  FIG. 5C , dashed line stamping circles  83  and  84  are provided to create a rotor  85  as shown in  FIG. 5D . Weld lines in the finished rotor  85  resulting from the weld lines  1  can be seen. Outer scrap regions  86  and inner scrap regions  87  are also illustrated. 
     As may be observed in the above five embodiments, in each case an equal side hexagon was formed. It is of course possible, and within the scope of this invention, to use other polygons instead of a hexagon. Thus such as eight-sided, ten-sided, twelve-sided, etc. polygons could be formed in an analogous manner as indicated above. 
     It should further be appreciated that in the five exemplary embodiments, at least three or more pieces are used to form the hexagons, which may be generically described herein as polygons. 
     Although preferred exemplary embodiments are shown and described in detail in the drawings and in the preceding specification, they should be viewed as purely exemplary and not as limiting the invention. It is noted that only preferred exemplary embodiments are shown and described, and all variations and modifications that presently or in the future lie within the protective scope of the invention should be protected.