Abstract:
A system for crimping metal sheets and a female die designed for use in crimping metal sheets. According to the present invention, a female die for use by interaction with a male die to join metal sheets together by interaction of the dies to cut or slice through the sheets to form portions of the metal sheets which are spread by material flow by the interaction of the dies to prevent separation of the metal sheets is disclosed. The female die comprises an anvil member having a first and a second end and including an anvil surface at its first end, and a base at its second end; at least two side plates positioned on the anvil member to restrict movement of the side plates toward the second end during interaction of the dies, the side plates being resiliently biased toward the anvil surface to permit movement of the side plates away from the anvil surface during the spreading of the portions of the metal sheets, and extending a selected distance beyond the anvil surface in a direction away from the base; and, at least one spring member supported by the base and in biasing engagement with each of the side plates to resiliently bias the side plates toward the anvil surface.

Description:
FIELD OF THE INVENTION 
     This invention relates to a system for crimping metal sheets and more particularly to a female die designed for use in crimping metal sheets. 
     BACKGROUND OF THE INVENTION 
     It is well known that metal sheets can be joined by devices for joining the metal sheets by a riveting type method utilizing mating dies in which the counter edges provided by the female die are yieldable. Such devices have been shown in U.S. Pat. No. 4,614,017, “Device For Joining Metal Sheets By A Riveting-Type Method”, issued Sep. 30, 1986, to Gerd—Gürgen Eckold and Hans Maass. This patent discloses in general that female dies having edges, which are yieldable, can be used with a male die to form joints. These joints are generally formed by cutting the metal sheets by interaction of the male die and the edges of the female die with the edges of the female die then yielding outwardly so that by further interaction of the dies, a portion of the cut material is spread by material flow to form a strong joint in the vicinity of the cuts and the material flow. Such techniques are referred to generally as “crimping”. Crimping is widely used to join thin metal sheets of a variety of types for a variety of applications. Considerable effort has been directed to the development of effective and economical tools for use for this purpose. 
     Unfortunately, the fabrication of the female dies is relatively expensive and many of the dies currently in use are not readily repairable, nor are they readily adjusted to accommodate various thicknesses of metal sheets and the like. Accordingly, a continuing effort has been directed to the development of a better system for joining metal sheets by crimping, and in particular, a considerable effort has been directed to the development of an improved female die. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a female die for use by interaction with a male die to join metal sheets together by interaction of the dies to cut or slice through the sheets to form portions of the metal sheets which are spread by material flow by the interaction of the dies to prevent separation of the metal sheets is disclosed. The female die comprises an anvil member having a first and a second end and including an anvil surface at its first end, and a base at its second end; at least two side plates positioned on the anvil member to restrict movement of the side plates toward the second end during interaction of the dies, the side plates being resiliently biased toward the anvil surface to permit movement of the side plates away from the anvil surface during the spreading of the portions of the metal sheets, and extending a selected distance beyond the anvil surface in a direction away from the base; and, at least one spring member supported by the base and in biasing engagement with each of the side plates to resiliently bias the side plates toward the anvil surface. 
     The present invention further includes a system for joining metal sheets together by interaction of a male die and a female die to cut or slice through the sheets to form portions of the metal sheets which are spread by material flow by the interaction of the dies to prevent separation of the metal sheets, the system comprising: 
     a) a female die including an anvil member having a first and a second end and including an anvil surface at its first end, and a base at its second end; at least two side plates secured to the anvil member to restrict movement of the side plate toward the second end during interaction of the dies, the side plates being resiliently biased toward the anvil surface to permit movement of the side plates away from the anvil surface during the spreading of portions of the metal sheets, and extending a selected distance beyond the anvil surface in a direction away from the base; and, at least one spring member supported by the base and in biasing engagement with each of the side plates to resiliently bias the side plates toward the anvil surface; 
     b) a male die comprising a punch having cutting edges and configured to interact with the side plates of the female die to cut the metal sheets to form portions of the metal sheets which are spread between the punch and the anvil surface; and, 
     c) a device for moving the male die toward the female die at sufficient pressure and velocity for interaction with the female die to cut or slice through the metal sheets to form portions of the metal sheets which are spread by material flow by the interaction of the dies. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of an embodiment of a female die according to the present invention; 
     FIG. 2 is an exploded view of the female die of FIG. 1; 
     FIG. 3 is an isometric view of a further embodiment of the female die according to the present invention; 
     FIG. 4 is a further embodiment of a female die according to the present invention; 
     FIG. 5 is an exploded view of the female die shown in FIG. 4; 
     FIG. 6 is a side view of a female -die according to the present invention; 
     FIG. 7 is an end view of the female die shown in FIG. 6; 
     FIG. 8 shows an embodiment of a side plate; 
     FIG. 9 is an end view of the side plate of FIG. 8; 
     FIG. 10 shows an alternate embodiment of a side plate; and, 
     FIG. 11 is an end view of the side plate shown in FIG.  10 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the discussion of the Figures, the same numbers will be used throughout to refer to the same or similar components. 
     In FIGS. 1 and 2, a female die  10  is shown. Die  10  comprises an anvil member  12 , which includes an anvil surface  14  at its first end  16  and a base  18  at its second end  20 . Side plates  22  and  24  are positioned against the sides of anvil surface  14 . Anvil surface  14  is supported by an anvil support  32 , which has at its upper end an enlarged portion  34  with the anvil support member being slightly smaller beneath enlarged portion  34 . An inset  36  is shown at the bottom of enlarged portion  34  in FIG.  2 . This reduced section is desirable to permit fine metal particles to move downwardly and out of die  10  without holding side plates  22  and  24  away from anvil surface  14 . Anvil member  12  includes a shoulder  30 , which, as shown, supports side plates  22  and  24  in position. Receptacles  38  are positioned in base  18  to receive spring members  28  which are configured to have a protrusion  40  on their upper ends  44 . Spring members  28  as shown are spring wire. Any suitable spring wire may be used. Some suitable spring wires are coiled spring wires for tension or compression springs and the like, of a size suitable to maintain the desired force against the side plates. The wire is bent at a radius  42  from about 1.0 to about 2.0 wire diameters to form the protrusion  40 . Protrusion  40  is positioned in an opening  46  in each of side plates  22  and  24 . The spring wire is positioned in base  18  to impose a slight tension on side plates  22  and  24  toward anvil surface  14 . While desirable, it is not necessary that the springs maintain a biasing force toward anvil  14  at rest so long as the springs are positioned to maintain the side plates against the anvil surface. As indicated, it is desirable that there be a slight biasing toward anvil surface  14  at all times. As shown, side plates  22  and  24  include a beveled surface  50 , which facilitates positioning side plates  22  and  24  on shoulder  30  which may also include a bevel surface at the junction of anvil support members  32  and shoulder  30 . 
     In the operation of the female die to crimp metal sheets and form connections there between, a male die is passed downwardly into engagement with a pair of metal sheets positioned over the female die. The male die may comprise a rectangular surface and may include cutting edges configured to interact with the side plates of the female die The male die is moved toward anvil surface  14  with sufficient force to cut the metal sheets at the edges of side plates  22  and  24 . This cut material between side plates  22  and  24  is engaged by further interaction of the male die and the female die so that the material is spread by material flow to form a strong joint between the two sheets. As the material flow occurs, side plates  22  and  24  are forced apart to facilitate the material flow. When the joint is complete and removed from the female die, it is important that side plates  22  and  24  be urged back into contact with anvil surface  14 . 
     The die shown in Figures and  1  and  2  is readily assembled by positioning the side plates against the sides of anvil  14  with the spring members engaged. The second ends  52  of the spring members are then directed into receptacles  38  which are shown as drilled holes in base  18 . The side plates are then pushed downwardly to move the springs into receptacles  38  in base  18 . Receptacles  38  are oriented to result in the thus positioned spring members maintaining plates  22  and  24  in contact with the sides of anvil  14 . Side plates  22  and  24  may be made of any suitably hard material, which will be effective to shear the metal sheets. For instance, any suitable oil-hardened or air-hardened die steel may be used for this purpose. Similarly, commonly available spring wire may be used as string members  28 . It is not necessary that spring members  28  be formed of wire. Alternatively, these wires could be formed of a suitable spring metal in any desired shape. It is believed that the use of spring wire will be more economical and is preferred since it is easier to position round holes in base  18  than receptacles of other shapes. Notwithstanding this consideration, other configurations of springs could be used provided the springs have a suitable protrusion on their upper ends for engaging side plates  22  and  24  and so long as the lower portion of the springs are configured for support in base  18  to provide the desired biasing of side plates  22  and  24  toward anvil surface  14 . 
     It is desirable that the top of side plates  22  and  24  be at a selected distance  26  above anvil surface  14 . Desirably, this distance is selected to represent about 50 to about 60 percent of the thickness of the two metal layers. This distance is shown by the dimension  26  in FIG.  1 . 
     In FIG. 3, a further embodiment of the present invention is shown. This embodiment is similar to the embodiment as shown in FIGS. 1 and 2 except that a round base is used. Further, second ends  52  of springs  28  extend beyond second end  20  of anvil member  12 . This wire may be used as a positioning member and the like. Of course, when spring end  52  of one of these spring members extends beneath base  18  it is convenient to extend the second end of the other spring member below the second end anvil member  12  also. 
     The use of either a square or a round base or a base of any other convenient shape is considered to be within the scope of the present invention. The base may include on second end of  20  of the base any suitable male, female or pinning arrangement to position female die  10  in position. Such variations are considered to be well known to those skilled in the art. In general, the use of female dies and crimping techniques are considered to be well known to those skilled in the art, however, the female die of the present invention is considered to afford unique advantages to those skilled in the art as discussed hereinafter. 
     In FIGS. 4 and 5, alternate embodiments of the present invention are shown. In these embodiments, two spring members are used with each of side plates  22  and  24 . 
     In other respects, the embodiment shown in FIG. 4 is similar to the embodiment shown in FIGS. 1 and 2. Certain variations, however, have been shown in the embodiments shown in FIG.  4 . In particular, openings  51  are shown in base  18  for positioning female die  10  by use of a pin or rod arrangement by use of bolts, screws or the like. Further it should be noted that spring members  28  are positioned in receptacles  38  in base  18  which have been opened on their sides by recesses  39  to permit spring members  28  to deform. This arrangement, while effective, could be substituted by an arrangement which positions a second shoulder, not shown, at the bottom of the recesses shown in FIGS. 4 and 5. Such variations are considered to be well known to those skilled in the art. 
     In FIG. 6, a side view of a female die according to the present invention is shown. Side plate  24  is held in position by spring member  28  which is positioned with a protrusion on first end  44  of spring member  28  extending into and in engagement with an opening  46  in plate  24 . A second shoulder  54  is shown and as a result, no open slots at the side of receptacles  38  have been shown. Receptacles  38  are shown through base  18  by a dotted line. It will be noted by reference to FIG. 6, that anvil surface  14  is of a lesser length than side plates  22  and  24 . This is desirable since the cuts in the metal sheets are no greater than the length of the tops of side plates  22  and  24 . The deformation of these sheets will be restrained to some extent by the ability of the cut portions of the sheets to bend downwardly to anvil surface  14  where the material flow is accomplished. Accordingly, it is unnecessary for anvil surface  14  to be as wide as the tops of side plates  22  and  24 . 
     In FIG. 7, a side view of the female die shown in FIG. 6 is shown. The distance of the tops of side plates  22  and  24  above anvil surface  14  is shown by the numeral  26 . As discussed previously, this distance is typically about 50 to about 70 percent of the combined thickness of the metal sheets. As shown, protrusions  46  on spring members  28  basically engage openings  46  in side plates  22  and  24  and are positioned to urge plates  22  and  24  toward anvil surface  14 . 
     In FIG. 8, a view of side plate  22  is shown including an opening  46  to receive a protrusion on the end of a spring member. Side plate  22  includes a bevel  50  at its lower edge  62 . As shown in FIG. 9, bevels can be placed on each side of side plate  22  so that side plate  22  if desired can be reversed. 
     In FIG. 10, a side plate  22  is shown having two spring openings. Side plate  22  in FIG. 10 does not include a bevel on its bottom  62 . In FIG. 11, an end view of side plate  22  is shown. It will be understood that side plate  22  could be manufactured with only one bevel or with no bevels if the seating arrangement on shoulder  30  is such that no bevel is required. 
     In the operation of the die of the present invention, the metal pieces are placed over the female die and then engaged by a male die which presses downwardly to interact with the female die to shear the two metals pieces at the edges of the side plates. The male die is then further urged toward anvil member  14  under sufficient pressure or impact conditions to result in a material flow of the metal sheets to form a joint, which is not readily separated. The joint is then removed from the female die and side plates  22  and  24  are returned by the spring members to their former position. The anvil surface includes a recessed area beneath an enlarged portion which forms anvil surface  14  so that small metal flakes and the like can fall between side plates  22  and  24  and anvil support member  32  and ultimately out of die  10 . It is well known in the art that it may be desirable in some instances to simply blow fine metal particles from the die with an air hose or the like to prevent their interference with operation of the die. The dies of the present invention can be positioned for use in a clamp-like device for bringing a male die into interaction with a female die in a press or other suitable device for moving a male die into interactive engagement with the female die. This interaction may be achieved by pressure, by impact or any combination thereof. Typically, a device is provided which is capable of moving the male die toward the female die at sufficient pressure and velocity for interaction with the female die to cut or slice through the metal sheets to form portions of the metal sheets which are spread by material flow. The device may be a press, which may be air or hydraulically activated, or it may be a hand gun which functions basically as a clamp to bring the dies and metal pieces into proper engagement and thereafter bring the dies and metal piece sheets into proper position and thereafter achieves interaction of the dies to form the crimped joint and the like. 
     As previously noted, the side plates may be formed of any suitable oil-hardened or air-hardened die steel. Typically the spring members are wire which may be of any suitable size but is typically about 0.093 to about 0.125 inches in diameter and of any suitable tempered compression spring or coiled spring stock. The spring members could be formed of a flat wire or other configurations if desired. 
     It should be noted that particularly with the embodiment utilizing a single wire to maintain the desired biasing pressure on side plates, that the side plate may be rotatable so that all four sides may be usable as cutting edges, if no bevel is used, until they become damaged or otherwise unusable. If a bevel is used the unbeveled sides may be used as cutting edges. This provides for use of multiple sides of each side piece. Further, the side pieces can be reversed to provide fresh cutting edges. When two springs are used with each side plate, the side plates can be reversed so that each side of the top of the side plates can be used as a cutting edge, and if no bevels are used, the bottoms of the side plates can be similarly used as cutting edges. By the use of a second set of holes, all four sides can be used. 
     In the event that one or more of the spring members becomes damaged, these are readily replaced. The entire die is readily disassembled by simply placing it in a suitable vice or press and pushing the spring members out of receptacles  38  in base  18 . This permits the replacement of any or all of the spring members and the repositioning or replacement of either of the side plates. This also permits the replacement of the side plates for a particular task with other side plates. In particular, if different thicknesses of metal sheets are to be crimped, it may be desirable to change the distance  26  between the top of side plates  22  and  24  and anvil surface  14 . This is readily accomplished as discussed. With most existing dies, the die must be replaced when the cutting edges have been worn out or broken or when different thickness metal sheets are crimped. 
     Also please note in FIGS. 6 and 7, that a pin  56  may be positioned through anvil support member  32  to maintain side plates  22  and  24  in position relative to anvil support member  32 . Pin  56  is positioned in anvil support member  32  in an opening  58  and extends into an opening  60  in side plates  22  and  24 . The use of this pin is optional. It results in maintaining side plates  22  and  24  more precisely in position, but has been found to be unnecessary for most applications. 
     Accordingly, the die of the present invention is economical to assemble initially, economical and easy to disassemble and repair, and permits the flexibility to use the same die for different thicknesses of metal sheets. These are important advantages, and when coupled with the durability and easy repairability of the die, represent a substantial improvement in the construction of female dies for use in crimping. The present invention further comprises a system for crimping using the female die of the present invention with a suitable male die and a device for moving the male die toward the female die at a sufficient pressure and velocity for interaction with the female die. 
     Having thus described the invention with respect to certain of its preferred embodiments, it is pointed out that the embodiments described are illustrative rather than limiting and that many variations and modifications are possible within the scope of the present invention. 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.