Abstract:
A joint for metallic members including a body portion and extending portion in one member and an opening in a second member. The body portion of one member at least partially overlaps the opening in the second member to create a joined opening. A bonding agent, e.g. adhesive, is applied in the joined opening to create a strong joint relying on the sheer strength of the cured bonding agent rather than its peel strength. Slot-to-slot and tab-to-slot joints using joined openings are provided. A drum and mechanical structure constructed using laser cutting techniques on metallic plates and utilizing the disclosed joints are also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present application claims the benefit of the filing date of U.S. Provisional Application No. 60/194,081 filed Apr. 3, 2000, the teachings of which are incorporated herein by reference.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to joints formed in metal parts and to structures formed using the same.  
         BACKGROUND OF THE INVENTION  
         [0003]    A commonly used method of providing high strength and lightweight characteristics is to construct a structure using a cellular web extending between respective plates. The web may be typically honeycomb shaped with each honeycomb cell having a hexagonal shape. The honeycomb shapes may be formed of corrugated metal strips laterally displaced from one another and joined to have the appearance of natural honeycomb. The web is usually welded, brazed, or otherwise fastened to the face sheets.  
           [0004]    The applications for these types of honeycomb structures are numerous. A main difficulty with the structures, however, is that they are cumbersome and inefficient to manufacture. For example, a honeycomb drum for use in the non-woven industry, e.g. to make baby diapers, has been formed using heavy aluminum castings which must be extensively machined. Framed honeycomb segments composed of cells of classic six-sided honeycomb are bolted to the machined castings and the outer diameter surface of the honeycomb is machined. A micro-etched screen is welded to the exposed outer honeycomb surface to create the desired vacuum-forming surface. The drum typically includes ribs traversing its width that may be as much 0.150″-0.200″ thick in a typical drum of about 2′ diameter to support loads imposed upon the drum. Because of this, the drum may weigh as much as 250 lbs., making it cumbersome for handlers.  
           [0005]    Accordingly, there is a need in the art for lightweight cell structure that may be constructed by simple fabrication techniques.  
         SUMMARY OF THE INVENTION  
         [0006]    A joint consistent with the present invention includes a first metallic member with a first opening having a body portion and extending portion. A second metallic member having a second opening is disposed in the first opening of the first member so that the second opening at least partially overlaps the body portion to create a joined opening. A bonding agent, e.g. adhesive, is applied in the joined opening so that when cured, it forms an integral part of the joint.  
           [0007]    A slot-to-slot joint consistent with the invention includes each metallic member equipped with a slot. Each slot has a body portion and extending portion. The two members are slid together so that their respective body portions at least partially overlap to define a joined area where a boding agent may be applied. Alternatively, each member may be additionally equipped with a cutout aligned with each slot so that the cutout from the first member at least partially aligns with the body portion from the second member and vice versa.  
           [0008]    A tab-to-slot joint consistent with the present invention includes a first metallic member with a tab having a cutout at least partially disposed within the tab. A second member has a slot that includes a body portion and extending portion. The tab of the first member is inserted into the slot of the second member so that the cutout at least partially overlaps the body portion to define a joined opening where bonding agent may be applied.  
           [0009]    A drum laser cut from metallic sheets includes a plurality of annular members joined by a plurality of ribs via different joints such as slot-to-slot and tab-to-slot joints. A mechanical housing includes a cell structure sandwiched between first and second metallic plates. Methods of forming joints are also disclosed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Advantages of the present invention will be apparent from the following detailed description of exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is a perspective view of an exemplary drum consistent with the present invention;  
         [0012]    [0012]FIG. 2 is an interior perspective view of a portion of the exemplary drum of FIG. 1;  
         [0013]    [0013]FIG. 3 is a cross-sectional line view taken along the line  3 - 3  of FIG. 1;  
         [0014]    [0014]FIGS. 4A and 4B are perspective views of slotted plates illustrating an exemplary slot-to-slot connection consistent with the present invention;  
         [0015]    FIGS.  5 A- 5 C are perspective views of a slotted and tabbed plate illustrating an exemplary tab-to-slot connection consistent with the present invention;  
         [0016]    [0016]FIG. 6 is a plan view of an exemplary first annular A-plate with one set of radial slots for accepting primary rib members in a tab-to-slot connection;  
         [0017]    [0017]FIG. 7 is a plan view of an exemplary second annular B-plate with two sets of radial slots for accepting primary and secondary rib members in tab-to-slot connections;  
         [0018]    [0018]FIG. 8 is a plan view of an exemplary third annular C-plate with radial slots for accepting primary rib members in a slot-to-slot connection;  
         [0019]    [0019]FIG. 9 is a plan view of an exemplary fourth annular D-plate with radial slots for accepting secondary rib members in a slot-to-slot connection;  
         [0020]    [0020]FIG. 10 is an elevation view of a cellular support structure;  
         [0021]    [0021]FIG. 11 is a cut away perspective view illustrating connection of a screen to the scalloped edge cellular support structure of FIG. 10;  
         [0022]    [0022]FIG. 12 is a cross section view of a second embodiment of the present invention;  
         [0023]    FIGS.  13 A- 13 D are plan views of exemplary plates for use in the second embodiment of FIG. 12;  
         [0024]    FIGS.  14 A- 14 D are plan views of exemplary ribs for use in the second embodiment of FIG. 12; and  
         [0025]    [0025]FIG. 15 is a plan view of a cell like rib structure for use in the second embodiment of FIG. 12. 
     
    
     DETAILED DESCRIPTION  
       [0026]    Referring to FIG. 1, there is shown an exemplary flow through drum consistent with the present invention. The drum  1  includes an interior surface  3  that defines a large aperture  7  and an exterior surface  5 .  
         [0027]    The exemplary drum  1  is generally comprised of four annular slotted plates, the A-plate  10 , B-plate  12 , C-plate  14 , and D-plate  16 , which are coupled via a plurality of primary slotted ribs  18  and secondary slotted ribs  20  arranged orthogonal to the annular plates and generally parallel with the axis of rotation A. The connections between the ribs and the plates are either slot-to-slot connections or tab-to-slot connections.  
         [0028]    Generally, rib connections to the outermost plates are tab-to-slot connections while rib connections to the inner plates are slot-to-slot connections. More particularly, the primary rib  18  may be connected to the C-plate  14  via a slot-to-slot connection, to the B-plate  12  via a tab-to-slot connection, and to the A-plate  10  via a tab-to-slot connection. Similarly, the secondary rib  20  may be connected to the D-plate via a slot-to-slot connection, and to the B-plate  12  via a tab-to-slot connection.  
         [0029]    Turning to FIG. 2, a cut away perspective view of the interior side  3  of the exemplary drum  1  of FIG. 1 is illustrated to show the relationship between the various plates and ribs. As illustrated, the A-plate  10  is the outermost annular plate having a radial length LA slightly less than the radial length LB of the B-plate  12 . The A-plate is the outermost plate on both the first side  9  and second side  11  of the drum  1 . The A-plate may include a plurality of slots  22  having a radial length LA 1  and width WA 1  to accept the narrower tab  61  (FIG. 6) of the primary rib  18  in a tab-to-slot connection. The A-plate  10  may also be equipped with a plurality of holes  24  for accepting bolts or other such fastening means to affix the A-plate to the C-plate  14 , which may include a nut for receiving both.  
         [0030]    The B-plate  12  is the next outermost plate on both the first  9  and second ends  11  of the drum  1 . The B-plate may also be equipped with a plurality of slots having a radial length longer than the radial length LA 1  of the A-plate slots for accepting the wider slot end  63  (FIG. 6) of the primary ribs  18  in a tab-to-slot connection.  
         [0031]    The C-plate  14  is an interior annular plate. Generally, the radial length LC of the C-plate  14  is greater than the radial length of the A-plate LA and B-plate LB. In the exemplary drum  1 , there are two C-plates  14 , which are coupled to a plurality of generally rectangular shaped primary ribs  18  via slot-to-slot connections  19 . The ends of the primary ribs are also joined to the A-plates  10  and B-plates  12  on the first  9  and second  11  end of the drum via tab-to-slot connections. Hence, the A-plate  10 , the B-plate  12 , and the C-plate  14  are all coupled to the plurality of primary ribs  18 . It should be understood by those skilled in the art that there may be any number of plates and ribs based on the particulars of the desired application without departing from the scope of the present invention.  
         [0032]    Turning to FIG. 3, a cross sectional view of the exemplary drum taken along the line  3 - 3  of FIG. 1 is illustrated. A primary rib  18  is connected to two interior C-plates  14  via slot-to-slot joints. Both sides of the primary rib  18  include a wide and narrow tab structure for connecting to the outer B-plates  12  and A-plates  10  respectively via tab-to-slot connection. A plurality of D-plates  16  are disposed above the primary rib  18  and engage secondary ribs  20  via slot-to-slot joints.  
         [0033]    Turning to FIGS. 4A and 4B, an exemplary slot-to-slot joint is illustrated. Only a piece of each member to be joined is illustrated for clarity. The representative members to be joined are the primary rib  18  and the C-plate  14 . Since only a small section of the C-plate is shown for ease of reference, it is shaped generally rectangular as opposed to the true annular C-plate shape as illustrated in FIGS. 1 &amp; 8. Alternatively, the secondary rib  22  and the D-plate  16  may also be joined in similar fashion. Those skilled in the art will recognize that a host of other varying members may be joined using the exemplary slot-to-slot configuration illustrated in FIGS.  4 A- 4 B without departing from the spirit and scope of the present invention.  
         [0034]    A slot  40  may be cut using laser sheet cutting technology in the primary rib  18 . Laser sheet cutting of metallic parts is a conventional technology.  
         [0035]    The slot  40  comprises a first narrow extending section  26 , a second wider body section  28 , and a third narrow extending section  30  of substantially equal dimensions as the first section  26 . The first section may have a width W 1  substantially equal to the width W 4  of the C-plate  16  to be coupled thereto.  
         [0036]    The width W 2  of the second body section  28  is greater than the width of the first extending section  26 . A cutout  32  has a width W 3  that may be substantially similar to the width W 2  of the second body section  28 . The length of the first extending section  26 , second body section  28 , third extending section  30 , and the cutout  32  may all be substantially equal to LC/6.  
         [0037]    Turning to FIG. 4B, the primary rib  18  and C-plate  14  are aligned at right angles to each other and the primary rib  18  is inserted into the C-plate using this slot-to-slot configuration. The C-plate has a slot and cutout structure to match the earlier structure described with reference to the primary rib  18 . The primary rib may be inserted into the C-plate  16  until the uppermost portion  33  of the third slot section  30  abuts with the same corresponding section of the C-plate slot.  
         [0038]    As such, the cut out  32  of the primary rib  18  is juxtaposed with the second body section  28  of the C-plate  16  at right angles to each other to form a cross-shaped open area  34 . Similarly, the second body section  28  of the primary rib  18  is juxtaposed with the cutout  32  of the C-plate  16  at right angles to each other to form a second cross-shaped open area  36 . Each of the cross-shaped open areas  34 ,  36  have four extensions with a length substantially equal to LC/6, a width substantially equal to the difference between W 2  and W 1 , and a thickness substantially equal to W 4 .  
         [0039]    Advantageously, each of these two cross-shaped open areas  34 ,  36  permits a bonding agent to be inserted thereto. Those skilled in the art will recognize adhesive may be utilized as such bonding agent or any number of materials may be soldered to act as the bonding agent. When allowed to dry or cure, the bonding agent acts as an integral part of the joined members. As such, the resulting slot-to-slot joint relies upon the generally higher shear strength of the bonding agent as opposed to generally lower peel strength.  
         [0040]    Turning to FIGS.  5 A- 5 C, an exemplary tab-to-slot joint that also creates an open area for bonding agent to be applied is illustrated. The tab-to-slot connection may be used to join primary ribs  18  and secondary ribs  20  to outermost plates such as A-plates  10  and B-plates  12 . The illustrated members to be joined in FIGS.  5 A- 5 C are the A-plate  10  and the primary rib  18 . Only a small section of the A-plate is shown for ease of reference and hence it is shaped generally rectangular as opposed to the true annular A-plate shape as illustrated in FIGS. 1 &amp; 6. Those skilled in the art will recognize that a host of other members may be joined using the exemplary tab-to-slot configuration illustrated in FIGS.  5 A- 5 C without departing from the spirit and scope of the present invention.  
         [0041]    [0041]FIG. 5A illustrates a slot  50  having a first extending portion  52 , a second body portion  54 , and third extending portion  56  slot with respective widths W 1 , W 2 , and W 3 . The length L 1  of the slot  50  may be substantially equal to the length L 2  of the tab  59  so that the tab securely fits in the slot. The width W 5  of the tab  59  may also be substantially equal to the width W 6  of the A-plate  10  so that the tab  59  is flush with the A-plate  10  after insertion. The tab  59  may also be equipped with a cutout  58 . The length of the cutout  58  on the primary rib  18  may be substantially equal to the length of the second body portion  54  on the A-plate  10 .  
         [0042]    Turning to FIG. 5C, the primary rib  18  may be orientated at a right angle to the A-plate  10  so that the tab  59  may be coupled to the slot  50 . The coupling of the tab into the slot results in the cutout  58  being juxtaposed with the second body portion  54  of the slot  50  at right angles to each other to form a cross-shaped open area  57 . The cross-shaped open area  57  has four extensions with a length substantially equal to L1/3, a width substantially equal to the difference between W 2  and W 1 , and a thickness substantially equal to W 6 . Those skilled in the art will recognize that a plurality of open areas with varying geometries and dimensions may be employed in a slot-to-slot connection or tab-to-slot connection without departing from the scope and spirit of the present invention. Although the width of the slots may also vary, the laser cutting function can permit the width of the slots to be as narrow as 0.06 inches.  
         [0043]    Advantageously, the cross-shaped open area  57  permits a bonding agent to be inserted thereto and allowed to cure. The cured bonding agent then acts as an integral part of the joined members. As such, the resulting tab-to-slot joint relies upon the generally higher shear strength of the cured bonding agent as opposed to generally lower peel strength.  
         [0044]    Turning to FIG. 6, the A-plate  10  may be cut from a sheet of material  60 . The A-plate  10  may have a plurality of radial slots  22  for accepting the narrower tabbed ends  61  of a plurality of primary ribs  18 . The A-plate may also have apertures  24  for accepting bolts or other such fastening means to attach the C-plate to the A-plate. Primary ribs  18  may be cut from the mid area of the sheet  60  or another separate sheet. The primary ribs may also have a wider tab portion  63 . The wider tab  63  accepts the B-plate  12  up against the abutting edge  65  of the wider tab  63 .  
         [0045]    Turning to FIG. 7, the annular B-plate  12  may be cut from a sheet  62 , and primary ribs  18  may be cut from the center of the sheet. The B-plate  12  may have a first set of radial slots  70  and a second set of concentric radial slots  72 . The first set of interior slots  70  may be sized to accept the wider tab  63  from the primary ribs  18 . The second set of exterior slots  72  may be sized to accept tabs from the smaller secondary ribs  20 . The secondary ribs  20  form a cell structure with the D-plates  16  as described more fully with reference to FIG. 10 and illustrated generally in FIG. 1.  
         [0046]    Turning to FIG. 8, the annular C-plate  14  may be cut from a sheet  80  and primary ribs  18  may be cut from the center of the sheet. A plurality of radial slots  82  may be cut in the C-plate  14  to present openings along the outside circumference  84  of the C-plate. The radial slots  82  may be sized to accept the slots  86  cut into the primary ribs  18  for establishing a slot-to-slot connection between the C-plate and the primary ribs  18 . The slot-to-slot connection may also be as described earlier with reference to FIGS. 4A &amp; 4B.  
         [0047]    Turning to FIG. 9, the annular D-plate  16  may be cut from a sheet  90  and secondary ribs  20  may be cut from the center of the sheet. The D-plate may be cut with a plurality of radial slots  98 . The radial slots  98  may be arranged in an alternating pattern having two radial slot openings on the outside circumference  96  of the D-plate followed by a radial slot opening on the inside circumference  99 .  
         [0048]    The secondary ribs may include secondary B ribs  20   a  and secondary C ribs  20   b  each having a plurality of slots  94  sized to engage corresponding radial slots  98  of the D-plate in a slot-to-slot configuration. The secondary B-ribs  20   a  couple to the D-plate via insertion over the outer circumference  96  while the secondary C ribs  20   b  couple to the D-plate via insertion by the inner circumference  99 .  
         [0049]    Turning to FIG. 10, a small section of a modified cell structure  100  is illustrated. The cell structure  100  is comprised of pieces of the annular D-plates  16  and secondary ribs  20 , each having scalloped edges  102 , connected via slot-to-slot joints  19 . A screen  104  may be affixed to the scalloped edges as can be best seen in FIG. 11. The screen may be resistance welded to the scalloped edges. In this instance, the cell structure that is snapped together utilizing a slot-to-slot joint would not require any bonding agent to be used in the slot-to-slot joints. The scalloped edges  102  maximize the open area between the cellular structure  100  and the screen  104 .  
         [0050]    Turning to FIG. 12, a second embodiment consistent with the present invention is illustrated. The second embodiment is a housing  1200  made up of a plurality of sandwiched structures with brazed joints, where each structure may include an exterior plate and an interior plate sandwiching a plurality of ribs. Such housing structures are strong and lightweight and may be utilized in the aircraft industry to enclose sensitive equipment, e.g. electronic equipment. Those skilled in the art will also recognize that a single sandwiched structure may be utilized to form various support structures used in a variety of applications, e.g. floors and wall support in aircraft.  
         [0051]    A perspective cross sectional view of one corner of an exemplary housing  1200  is illustrated in FIG. 12. One wall  1201  is joined to a ceiling  1203  at a corner. Similarly, a plurality of different walls, ceilings, and floors may be joined at different corners to create an enclosed housing. The wall  1201  may include an exterior wall plate  1202  connected to an interior wall plate  1206  via a plurality of ribs. Similarly, the ceiling  1203  may include an exterior ceiling plate  1204  connected to an interior ceiling plate  1208  via a plurality of ribs. Advantageously, the exterior ceiling plate  1204  includes a plurality of notches  1302  to accept corresponding tabs  1304  from the exterior wall plate  1202  to form an integrated exterior edge. Similarly, the interior ceiling plate  1208  includes a plurality of notches  1306  to accept corresponding tabs  1308  from the interior wall plate  1206 .  
         [0052]    Turning to FIGS.  14 A- 14 D and FIG. 15, the plurality of ribs and an exemplary cell configuration of ribs that may be sandwiched between the exterior and interior plates is illustrated. For ease of explanation, the plurality of ribs includes a set of vertical ribs  1502  and horizontal ribs  1504  with respect to the plates of FIGS.  13 A- 13 D.  
         [0053]    The set of vertical ribs  1502  includes a standard vertical rib  1212  and a tabbed vertical rib  1210 , while the horizontal ribs  1504  includes a standard horizontal rib  1216  and a tabbed horizontal rib  1214 . Due to laser cutting, the ribs may be only 0.006 inches thick aluminum in this embodiment and the exterior and interior plates may be 0.063 inches thick aluminum.  
         [0054]    The slots  1404  of the standard vertical rib  1212  engage corresponding slots  1410  of the horizontal ribs  1214 ,  1216 . One set of tabs  1402  of the tabbed vertical rib  1210  protrude at right angles with respect to the length of the rib. These right angle tabs  1402  engage corresponding slots  1312  in the exterior plates  1202 ,  1204  (FIGS.  13 A- 13 B). The other tab  1406  of the tabbed vertical rib  1210  engages a separate slot  1314  on the exterior plates  1202 ,  1204  when adjacent exterior plates are joined together at right angles.  
         [0055]    Turning to FIGS. 14C and 14D, the horizontal set of ribs  1504  is illustrated. The standard horizontal rib  1216  includes a plurality of slots  1410  that engage corresponding slots  1404  in the vertical ribs. The tabbed horizontal rib  1214  may include a plurality of tabs  1408  that engage corresponding slots  1314  in the interior plates.  
         [0056]    Turning to FIG. 15, the horizontal ribs  1504  and the vertical ribs  1502  may be arranged orthogonal to form a square cell like structure. Those skilled in the art will recognize that other structures such as honeycomb structures may also be utilized without departing from the spirit and scope of the present invention.  
         [0057]    The tabbed horizontal rib  1214  is arranged periodically among the standard horizontal ribs  1216  so that its tabs  1408  properly engage slots  1314  in the interior plates. Similarly, the tabbed vertical rib  1210  is periodically arranged among the standard vertical ribs  1212 .  
         [0058]    Advantageously, the entire housing structure may be assembled with slot-to-slot joints and tab-to-slot joints as earlier described. Again, generally the horizontal ribs  1504  and the vertical ribs  1502  engage each other in slot-to-slot joints  1506 , while the exterior and interior plates are joined to the cell like structure via tab-to-slot joints. The joints may be brazed through techniques known to those skilled in the art.  
         [0059]    The embodiments that have been described herein, however, are but some of the several which utilize this invention and are set forth here by way of illustration but not of limitation. It is obvious that many other embodiments, which will be readily apparent to those skilled in the art, may be made without departing materially from the spirit and scope of the invention as defined in the appended claims.