Abstract:
A laminated plate assembly in which the laminations in a stack are secured together by means of one or more interlocks or tabs that project from the uppermost lamination in the assembly through holes or slots in all the other laminations in the assembly, or around the periphery of the other laminations in the assembly, with each tab being bent or pressed against the underside of the bottom lamination in the assembly. This secures all the laminations in the stack together, much like a staple secures papers in a stack together, allowing for additional handling and processing of the laminated plate assembly without concern that the laminated plates in the stack will become misaligned or even become removed from the stack.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates generally to interlocking laminations used in electrical devices, such as those used in the windings for D.C. motor armatures or A.C. rotors and stators.  
           [0002]    Typically, laminations are stacked, or piled together to achieve a required thickness of laminations. Because the laminations undergo further processing, such as being wound to form a motor core, it is desirable to retain the laminations together in a stack of a desired height so that the stack of laminations can be moved together to a subsequent manufacturing process.  
           [0003]    Various methods and apparatuses have been used to fasten laminations together, including the use of tabs in the laminations which extend below the lower surface of the lamination and are inserted into a slot formed in a next adjacent lamination. Typically, the lowest lamination in the stack has the interlock tabs removed because there is no need to secure the lowest lamination in the stack to anything else.  
           [0004]    A drawback with the foregoing method of securing laminations together is that sometimes, in the course of further processing of the laminations, a lamination may come out of the slot on the next lower lamination. When this happens, the integrity of the stack is lost, and production must be stopped to realign the stack, or the part must be rejected. In one attempt to resolve this drawback, a wrapper of some sort is placed around the stack of laminations, but because the stack of laminations undergoes further processing, such as winding, such a wrapper may interfere with the additional processing. Also, because these stacks of laminations are used in electrical equipment, care must be taken that the material of any such wrapper does not interfere with the electrical and magnetic properties of the laminations.  
           [0005]    Accordingly, a continuing search has been directed to the development of a system and method by which laminations in a stack may be more securely interlocked to each other without decreasing the throughput of lamination stacks, and without affecting the electrical and magnetic properties of the resultant stack of laminations.  
         SUMMARY OF INVENTION  
         [0006]    Accordingly, the system of the present invention provides for interlocking the upper lamination in a stack to the lowest lamination in the stack such that a tab of the upper lamination is inserted in an opening in the lower lamination(s) and then bent so that it is locked against the underside of the lowest lamination in the stack, securing all the laminations in the stack together. This interlocking is performed as part of the process of manufacturing the lamination, eliminating the need for additional tooling.  
           [0007]    One aspect of the present invention is a laminated plate assembly that comprises a first lamination that defines at least one hole. A second lamination that defines at least one hole corresponding in number and position to the hole(s) of the first lamination is positioned adjacent to the first lamination. At least one interlocking tab extends from each hole in the second lamination through the corresponding hole in the first lamination, and is bent against the side of the first lamination that is opposite to the side adjacent to the stack to secure the stack together.  
           [0008]    Another aspect of the present invention is a laminated plate assembly that comprises a first lamination and a second lamination positioned adjacent to the first lamination. At least one interlocking tab extends beyond the periphery of the second lamination. This tab is wrapped around the periphery of the first lamination and is crimped against the side of the first lamination that is opposite to the side adjacent to the stack to secure the stack together.  
           [0009]    Yet another aspect of the present invention is a method of securing adjacent laminations in a stack, wherein at least one hole is formed in each lamination in the stack, corresponding in number and position thereof with the hole(s) of each other lamination in the stack. The material is removed from the hole(s) of each lamination in the stack except the top lamination. The material from the hole in the top lamination in the stack forms an interlocking tab that projects through the corresponding hole in each other lamination in the stack. Each tab is bent against the side of the bottom lamination that is opposite to the side adjacent to the stack, securing the laminations in the stack together.  
           [0010]    Another aspect of the present invention is method of securing adjacent laminations in a stack together, wherein at least one interlocking tab is formed in the top lamination in the stack that projects beyond the periphery of the top lamination. Each tab is wrapped around the periphery of each lamination in the stack and is crimped against the side of the bottom lamination in the stack that is opposite to the side adjacent to the stack, securing the laminations of the stack together.  
           [0011]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0012]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: FIG. 1 is a flow chart showing a method of assembling and interlocking laminations in a stack; FIG. 2 is perspective bottom view of a lamination blank; FIG. 3 is a perspective bottom view of a lamination in one of the embodiments of the present invention; FIG. 4 is a perspective bottom view of the uppermost lamination in one of the embodiments of the present invention; FIG. 5 is a perspective view of a stack of typical laminations secured together with interlock tabs in one of the embodiments of the present invention; FIG. 6 is a cross-sectional view of the lamination stack of FIG. 5 taken along the line  6 - 6  of FIG. 5, showing the interlock tabs securing the laminations in the stack together; FIG. 7 is a perspective bottom view of a lamination blank; FIG. 8 is a perspective bottom view of one of the laminations in an alternative embodiment of the present invention; FIG. 9 is a perspective bottom view of the uppermost lamination in an alternative embodiment of the present invention; FIG. 10 is a perspective view of an alternative embodiment of a stack of typical laminations secured with interlock tabs; FIG. 11 is a cross-sectional view of the lamination stack of FIG. 10 taken along the line  11 - 11  of FIG. 10, showing the interlock tabs securing the laminations in the stack together; and FIG. 12 is a flow chart showing a method of assembling and interlocking laminations in a stack; FIG. 13 is a perspective bottom view of a lamination blank; FIG. 14 is a perspective bottom view of one of the laminations in another alternative embodiment of the present invention; FIG. 15 is a perspective bottom view of the uppermost lamination in another alternative embodiment of the present invention; FIG. 16 is a perspective view of an another alternative embodiment of a stack of typical laminations secured with interlock tabs on the periphery of the laminations; and FIG. 17 is a cross-sectional view of the lamination stack of FIG. 16 taken along the line  17 - 17  of FIG. 16, showing the interlock tabs securing the laminations in the stack together. 
     
    
     DETAILED DESCRIPTION  
       [0013]    In the discussion of the FIG. S, the same reference numerals will be used throughout to refer to the same or similar components. In the interest of conciseness, various other components known to the art, such as dies, punches, and the like necessary for the manufacture of laminations, have not been shown or discussed. Even though numerous characteristics and advantages of the present invention have been described in the drawings and accompanying text, the description is illustrative only, and changes may be made, especially in matters of arrangement, shape and size of the parts, within the principles of the invention to the full extent indicated by the broad general meaning of the terms used in the claims. The words “top,” “uppermost,” “bottom,” and “lowermost,” as used in this document, are used in reference to a stack of laminations as it would appear when it is placed on a horizontal surface and the lamination to which an interlock tab is attached is at the “top,” or furthest away from the horizontal surface, and the lamination to which the interlock tab is crimped is at the “bottom” or closest to the horizontal surface.  
         [0014]    [0014]FIG. 1 depicts a method of assembling and interlocking laminations in a stack  1 . Each step in the method is described further below.  
         [0015]    [0015]FIG. 2 depicts a blank  10  used to create a lamination in the stack as described below and depicted in FIGS. 3 through 6.  
         [0016]    At step  2  in FIG. 1, holes are cut in each lamination to be used in the lamination stack. FIG. 3 depicts a first lamination  20  cut from a blank  10  to be used in an embodiment of a lamination stack. One or more holes  22  are cut out of each first lamination  20 . The material (not shown) which was in these holes  22  before they were cut is removed from the first lamination  20 , as described in step  3  of FIG. 1.  
         [0017]    [0017]FIG. 4 depicts a second lamination  40  cut from a blank  10  to be used in an embodiment of a lamination stack, as described in step  2  of FIG. 1. One or more holes  42  are cut out of the second lamination  40  that are of a corresponding size and in a corresponding location as the holes  22  in the first lamination  20 . As described further below, the material which was in these holes  42  in the second lamination  40  forms an interlock tab  44  that remains secured to the second lamination  40  on at least one side  44   a  of the hole  42 . In this depiction, the interlock tab  44 ′ in one hole  42  remains attached to the lamination  40  on one side  44   a.  The interlock tab  44 ′ in another hole  42  remains attached to the lamination  40  on two sides,  44   a  and  44   b.    
         [0018]    The laminations are stacked together at step  4  in FIG. 1. Referring to FIG. 5 of the drawings, the reference numeral  50  generally designates a stack of laminations embodying features of one embodiment of the present invention. The lamination stack  50  includes a first lamination  20  and a second lamination  40 . Optionally, one or more interior laminations  30  (only one of which is shown) are interposed between the first lamination  20  and the second lamination  40 . If the embodiment of the invention includes any interior laminations  30 , one or more holes  32  are cut out of the lamination  30  that are of a corresponding size and in a corresponding location as the holes  22  in the first lamination  20 . The material (not shown) which was in the holes  32  before they were cut is removed from the interior lamination  30 . The interlock tab  44  is bent at securing point  44   a,    44   b  in such a manner that it protrudes through the corresponding hole  32  in any interior laminations  30 , and through the corresponding hole  22  in the first lamination  20 . This process is described at step  5  in FIG. 1. The interlock tab  44  is then bent against the side of the first lamination  20  that faces away from the stack  50 , thereby interlocking all the laminations in the stack  50  together, much as a staple secures papers in a stack together. This process is described in step  6  of FIG. 1.  
         [0019]    In FIG. 6, a cross-section of the lamination stack  50  is shown. In the example shown, it can be clearly seen that holes  22 ′,  22 ″,  32 ′,  32 ″, have been cut from the first lamination  20  and the interior lamination  30 , and the material (not shown) has been removed. Holes  42 ′,  42 ″, have been cut out of the second lamination  40  that are of a corresponding size and in a corresponding location as the holes  22 ′,  22 ″ in the first lamination  20 , and  32 ′,  32 ″ in the interior lamination  30 .  
         [0020]    The material which was in the holes  42 ′,  42 ″ in the second lamination  40  forms interlock tabs  44 . The material from hole  42 ′ remains secured to the second lamination  40  on one side  44   a,  forming a single interlock tab  44 ′. The material from hole  42 ″ remains attached to the lamination on two sides,  44   a,    44   b,  forming two interlock tabs  44 ″. The interlock tabs  44 ′,  44 ″ are bent at the attached side(s)  44   a,    44   b  in such a manner that they will protrude through the corresponding holes  32 ′,  32 ″ any interior laminations  30 , and through corresponding holes  22 ′,  22 ″ in the first lamination  20  in the stack  10 . That portion of each interlock tab  44  that extends below the first lamination  20  in the stack  10  is bent against the underside of the first lamination  20  in the stack  10  like a staple, thereby interlocking all the laminations in the stack together.  
         [0021]    [0021]FIG. 7 depicts a blank  100  used to create a lamination in the stack as described further below and depicted in FIGS. 8 through 11.  
         [0022]    At step  2  in FIG. 1, holes are cut in each lamination to be used in the lamination stack. FIG. 8 depicts a first lamination  120  cut from a blank  100  to be used in this embodiment of a lamination stack. The hole  122  can be clearly seen at the periphery of the first lamination  120  with material (not shown) that had filled the hole removed from the first lamination  120 , as described in step  3  of FIG. 1.  
         [0023]    [0023]FIG. 9 depicts a second lamination  140  cut from a blank  100  to be used in this embodiment of a lamination stack as described in step  2  of FIG. 1. One or more holes  142  are cut out of the periphery of the lamination  140  in a corresponding location as any holes  122  in the first lamination  120 . The material which was in these holes  142  in the second lamination  140  forms an interlock tab  144  that remains secured to the second lamination  140  on at least one side  144   a.    
         [0024]    The laminations are stacked together at step  4  in FIG. 1. FIG. 10 depicts this embodiment of the stack of laminations  150  of the present invention. The lamination stack  150  includes a first lamination  120  and a second lamination  140 . Optionally, one or more interior laminations  130  (only one of which is shown) are interposed between the first lamination  120  and the second lamination  140 . If the embodiment of the invention includes any interior laminations  130 , one or more holes  132  are cut out of the lamination  130  that are of a corresponding size and in a corresponding location as the holes  122  in the first lamination  120 . The material (not shown) which was in the holes  132  before they were cut is removed from the interior lamination  130 . In this embodiment, the holes  122 ,  132 , and  142  through the first lamination  120 , any interior laminations  130 , and the second lamination  140  are cut at the periphery of each lamination. The interlock tab  144  is bent at the securing point  144   a  in such a manner that it protrudes through the hole  142  in the second lamination, the corresponding hole  132  in any interior laminations  130 , and the corresponding hole  122  in the first lamination  120 . This process is described at step  5  in FIG. 1. The interlock tab  144  is then bent against the side of the first lamination  120  that faces away from the stack  150 , like a staple, thereby interlocking all the laminations in the stack  150  together. This process is described in step  6  of FIG. 1.  
         [0025]    In FIG. 11, a lamination stack  150  of the embodiment of the present invention shown in FIG. 10 is shown in a cross-sectional view. In this embodiment, it can be clearly seen that the first lamination  120  and, in this case the interior lamination  130 , have holes  122 ,  132 , on the periphery of the laminations, from which the material (not shown) has been removed. Holes  142  are cut in the second lamination  140  that are of a corresponding size and in a corresponding location as the holes  122  in the first lamination  120 , and holes  132  in the interior lamination  130 .  
         [0026]    The material which was in the holes  142  in the second lamination  140  form interlock tabs  144 , which are secured to the second lamination  140  on at least one side  144   a.  The interlock tab  144  is bent at the attached side(s)  144   a  in such a manner that it fits into the corresponding holes  132  in any interior laminations  130 , and through the corresponding hole  122  in the first lamination  120  in the stack  150 . That portion of the interlock tab  144  that extends below the first lamination  120  in the stack  150  is bent against the underside of the first lamination  120  in the stack  150 , thereby interlocking all the laminations in the stack together, like a staple securing papers in a stack together.  
         [0027]    [0027]FIG. 12 depicts a method of assembling and interlocking laminations in a stack  201 . Each step in the method is described further below.  
         [0028]    [0028]FIG. 13 depicts a blank  200  used to create a lamination in the stack as described further below and depicted in FIGS. 14 through 17. .  
         [0029]    [0029]FIG. 14 depicts a first lamination  220  from a blank  200  to be used in another alternative embodiment of a lamination stack. As can be clearly seen, there are no holes needed in the lamination  220  for securing the laminations of a stack  250  together.  
         [0030]    [0030]FIG. 15 depicts a second lamination  240  from a blank  200  to be used in another alternative embodiment of a lamination stack  250 . The second lamination  240  has one or more interlock tabs  246  that extend beyond the periphery of the second lamination  240  as described in step  203  of FIG. 12. These interlock tabs  246  are attached to the second lamination  240  on one side  246   a.    
         [0031]    In FIG. 16, the stack of laminations  250  used in another alternative embodiment of the present invention is shown. The lamination stack  250  includes a first lamination  220  and a second lamination  240 . Optionally, one or more interior laminations  230  (only one of which is shown) are interposed between the first lamination  220  and the second lamination  240 . In this embodiment, the first lamination  220 , and any interior laminations  230  have no holes. The second lamination  240  has an interlock tab  246  which extends beyond the periphery of the second lamination  240 , and the interlock tab  246  is bent at the securing point  246   a  such that it goes around the periphery of any interior laminations  230  and the first lamination  220 . This process is described at step  204  in FIG. 12. The interlock tab  246  is then is bent against the side of the first lamination  220  that faces away from the stack  250  like a staple, thereby interlocking all the laminations in the stack  250  together. This process is described in step  206  of FIG. 12.  
         [0032]    In FIG. 17, a lamination stack  250  of another alternative embodiment of the present invention shown in FIG. 16 is shown in a cross-sectional view. It can be clearly seen that the there are no holes in the first lamination  220  or any interior laminations  230 . Instead, the second lamination  240  has at least one interlock tab  246  that projects beyond the periphery of the second lamination  240  and is secured to the second lamination  240  on at least one side  246   a.  The interlock tab  246  is bent at the attached side  246   a  so that it is secured against the edges of all the laminations in the stack  250 . That portion of the interlock tab  246  that extends below the first lamination  220  in the stack  250  is bent against the underside of the first lamination  220  in the stack  250 , thereby securing all the laminations in the stack  250  together, like a staple securing papers in a stack together.  
         [0033]    Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.