Abstract:
A weldment that is embedded in a concrete slab-type structural member. There is a central plate having a planar, weldable surface and disposed along an outer edge of the concrete slab. A pair of divergingly extending arms extends from the weldable surface and is embedded in the concrete slab. One or both of the extending arms has an irregular upper edge to engage the surrounding concrete. The irregular edge may be a series of v-shaped notches or v-shaped raised portions or any combination forming a saw tooth configuration. A method of manufacturing the weldment in the concrete slab is accomplished by locating the weldment in a mold and fastening a cap around the central plate. The weldment and cap are attached to the mold. After the concrete is poured and hardens into the slab, the cap is removed exposing a clean weldable surface.

Description:
FIELD OF THE INVENTION 
     This invention relates to a metal weldable piece that is embedded into a concrete slab type structure and the method of manufacturing the slab so that the weldable piece is properly positioned in the slab. The weldable piece is used to join adjacent concrete structures or slabs by welding together the weldable piece embedded in each of the concrete structures. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Precast concrete slab type structures are commonly used in constructing walls, floors, and concrete decks. They generally take the shape of concrete slabs which may have a t-shape in cross section. There is a horizontal portion of the slab which is the load bearing surface and there is generally reinforcing mesh or bars within the slab. There is at least one generally flat surface or edge that adjoins a flat surface or edge of a confronting adjacent slab. 
     When the concrete slabs are placed next to each other to form the wall or deck, it is possible for the slabs to move with respect to each other. This is due to wind forces or thermal expansion. In order to prevent or minimize the relative movement and to increase the strength of the final structure, metal inserts, often called “weldments” are place within the concrete slabs with a portion of the weldment extending out from an edge of the slab. When the slabs are positioned for final assembly, the metal weldment of one slab is aligned with and opposite to a complementary metal weldment in an adjacent slab. The metal complementary weldments are welded to each other to join the two weldments. This results in a unitary structure that is much stronger and less prone to movement than if no method of joining the slabs were used. 
     Various types of weldments have been used in the past. One such type is a U-shaped cylindrical reinforcing bar that had the arms of the “U” embedded within the concrete and the base of the “U” exposed along the edge of the concrete slab. Because the exact position of the arms could not be maintained when the concrete slab was poured, and the “U” shaped reinforcing bar did not have adequate means to keep it secured within the concrete slab, the reinforcing bar oftentimes pulled out from the slab when under load. Obviously this was unacceptable as it substantially weakened the overall structure. 
     An improved weldment is illustrated in U.S. Pat. No. 5,402,616. This weldment provides a weldment that has arms that support a reinforcing mesh within the concrete mold during the molding operation. The mesh is accurately positioned and retained in the proper position during the molding operation so that it buried in the concrete slab at a proper depth and a predetermined distance from the edge of the slab. However, a problem with this particular weldment, which is similar to the problem in the other prior art weldments, is securing the weldment within the concrete slab at all times. Horizontal and vertical forces tend to loosen the weldment within the slab which can eventually cause the weldment to be pulled out from the slab. 
     Another problem in the past was positioning the weldment into the mold that is used to form the concrete slab. Not only must the weldment be accurately positioned and have that position maintained when the concrete is poured, but the face of the weldment that is to be welded, must be kept relatively clean from concrete so that it is ready for welding. This presents additional problems during the casting process. 
     Thus, there is the need for a concrete weldment having improved securing properties over the weldments illustrated in the prior art that causes the weldment to be more securely retained within the concrete slab even when the weldment is subjected to vertical and horizontal forces. It is an object of the invention to provide a concrete having these properties, yet are not more expensive to manufacture than weldments of the prior art. There is also a need for an improved positioning mechanism to maintain the weldment in the proper position during the concrete casting process and further to keep the weldable face of the weldment as clean as possible. This results in an increased weldable area, at the proper angle to the concrete surface, and allows for thermal expansion of the weldment without cracking and spalling of the concrete. 
     Applicant&#39;s invention solves the problem stated above by designing a weldment that comprises a central plate which defines the weldable surface. The central plate is at an acute angle with respect to the horizontal plane of the concrete slab. There is a pair of outstanding arms extending out from the each of the ends of the central plate. Each of the outstanding arms has a top edge and a bottom edge. In one embodiment there is an irregular surface along the top edge of one or both of the outstanding arms. The irregular surface can be a v-shaped cut or a saw-tooth cut in the top edge. This irregular surface provides a locking or high friction surface against which the weldment locks into the concrete slab as the poured concrete hardens. The resulting locking edges of the arms further increases the force required to pull the weldment from the concrete slab as compared to those of the prior art. 
     Applicant&#39;s invention also provides for a cap or cover that is attached to the central plate prior to the casting process. The cap is further attached to the steel mold that defines the concrete slab. This cap covers the weldable surface and top and bottom edges of the central plate and accurately positions the weldment within the mold. After the concrete slab is poured and hardens, the cap is removed from the central plate, which presents a clean weldable surface. A recess is also formed in the concrete slab around the central plate to allow for thermal expansion when it is welded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is top plan view of the inventive weldment. 
         FIG. 2  is an end view of the weldment shown in  FIG. 1 . 
         FIG. 3  is a front elevation view of the weldment. 
         FIG. 4  is an enlarged view of the saw tooth edge. 
         FIG. 5  is a perspective view of the weldment. 
         FIG. 6  is a side view of two concrete slabs each having a weldment embedded within, with the exterior face of the central portions facing each other. 
         FIG. 7  is an isometric view of two adjacent concrete slabs illustrating the position of the weldments in each slab with respect to each other. 
         FIG. 8  is side view with portions removed of the weldment mounted to the mold with the cap covering the front surface of the central portion of the weldment. 
         FIG. 9  is a perspective view of the cap. 
         FIG. 10  is a front view of the cap. 
         FIG. 11  is a bottom view of the cap. 
         FIG. 12  is top plan view of the cap. 
         FIG. 13  is a left end view of the cap. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning first to  FIG. 1  there is illustrated a weldment  10  of the present invention. It is designed to be embedded in a concrete slab-type structural member or slab  12 . The slabs  12  are generally designed having an extended length as compared to its width. The slabs  12  are generally positioned so that the long edges of the slabs are abutting each other to form a building element such as a wall or deck surface. The weldments  10  are placed at predetermined distances along the long edge of the slab  12 . When the slabs are placed adjacent to each other, the weldments  10  are in close proximity to each other such that they can be welded together thereby increasing the strength overall wall or deck surface. Furthermore the horizontal shear capacity of the weldment will provide the shear requirement to make the slabs  12  act as one diaphragm when welded together. 
     The weldment  10  has a central plate  14 . There is a top edge  15  that is preferably not embedded in the slab  12 . Opposite the top edge  15  is a bottom edge  16 , the top and bottom edges  15  and  16  defining the height H 1  of the central plate  14 . The central plate  14  has a width W 1  which terminates in opposite ends  17  from which extend diverging arms  18 ,  20 . The arms  18 ,  20  have a bottom have a bottom edge  21  which is in the same plane as the bottom edge  16 . The arms  18 ,  20  also have a top edge  23  with irregular surface portions  25  and  27  respectively. Out-turned flanges  22 ,  24  are connected to the ends of the arms  18 ,  20  opposite ends  17 . The plane of the flanges  22 ,  24  are substantially parallel to plane of the central plate  14 . 
     As seen in  FIG. 3  there are holes  34  which receives a fastener such as a rivet or self-tapping screw which accurately positions and holds the weldment  10  during the concrete slab manufacturing process. The weldment  10  is positioned in a mold and held in place so that when the concrete is poured into the mold, the weldment  10  remains in its proper position so that it is accurately embedded within the concrete. This will be more fully described herein when the casting process is described. 
     The irregular portions  25  or  27  can take numerous shapes and configurations. As illustrated in  FIGS. 3 and 4 , the irregular portions  25 ,  27  can be a v-shaped notch or elevated v portion or any saw tooth configuration in the top edge  23 . The irregular portion can be on the top edge  23  of one or both of the diverging arms  18 ,  20 . The purpose of the irregular portions  25  or  27  is to provide a locking or resistance portion on the arms  18 ,  20  which interacts with and interlocks with the concrete after it is poured and hardens. These irregular portions make it much more difficult for the weldment  10  to loosen from the concrete  12  as the horizontal tensile capacity of the weldment is significantly increased due to the saw tooth edge at one or both arms. 
       FIG. 5  is a perspective view of the weldment  10 . Dimples or raised portions  29  may be added along the arms  18 ,  20 . The dimples  29  provide additional means to anchor the weldment  10  in the concrete slab  12  by providing an additional raised surface to interact with the concrete slab  12 . This makes it more difficult to pull the weldment  10  out of the slab  12 . 
     Turning to  FIG. 6 , there are illustrated two concrete slabs  12  in face to face orientation. Each slab  12  has a weldment  10  embedded within the slab  12 . The central plate  14  of each weldment  10  faces the other. With the two slabs  12  slightly separated by approximately ½ inch, a welding plate  30  is placed between the two central plates  14 . A weld  32  is made between the plate  30  and the central plate  14  so that a unitary structure is created by the two central plates  14 , the welding plate  30  and the weld  32 . After the weld  32  cools, a sealant  36  is placed in the void between the two concrete slabs  12 , above the welding plate  30  and up to the top surface of the concrete slabs  12 . 
       FIG. 7  is similar to  FIG. 6  except it is an isometric view with portions removed illustrating the position of the weldments  10  when the two concrete slabs  12  are facing each other. The welding plate  30  is positioned between the two slabs  12  and supported by the central plate  14 . Once the weld  32  is made, the two concrete slabs  12  act as one unitary structure. It resists horizontal shear in both horizontal directions as illustrated by arrows F 1 , F 2 , F 3 , and F 4 . Furthermore this configuration increases the vertical shear capacity of the weldment  10  as the outturned flanges  22 ,  24  assist in distributing the vertical load from one concrete slab to another without spalling the concrete. The result is the entire floor structure of the joined concrete slabs acts as one unit. 
     To illustrate the concrete slab manufacturing process we turn to  FIG. 8  which illustrates a mold or steel form  38  used to make the concrete slab  12 . The mold  38  has a mold bottom  40  which defines the edges and outer dimensions of the length and width of the concrete slab  12 . To manufacture the concrete slab  12 , the weldment  10  is first attached to a cap or cover  42 . The cap  42  is illustrated in detail in  FIGS. 10-13 . As seen in  FIG. 13 , the cap  42  has a front  44 , a back  46 , a top  48  and a bottom  50 . The top  48  terminates on one side at a top ledge  49  and the bottom terminates at on one side at a bottom ledge  51 . Between the top ledge  49  and bottom ledge  51  is a recessed area  52 . A height H 2  of the recessed area  52  is slightly larger than the height H 1  of the central plate  14 . It is dimensioned to closely receive the central plate  14  as seen in  FIG. 8 . A width W 2  of the recessed area  52  is slightly greater than the width W 1  of the central plate  14 . 
     In  FIG. 13  it is seen that there are cap rivet holes  54  that extend from the back  46  to the front  44 . When the weldment  10  is located between the top ledge  49  and bottom ledge  51 , with the central plate  14  placed in the recessed area  52 , the rivet holes  34  area aligned with the cap rivet holes  54 . Furthermore, the mold  38  has receiving holes  56  that align with holes  54 . Thus, when a fastener or rivet  58  is placed through the river holes  34 , through aligned cap holes  54  and then into the mold holes  56 , the weldment  10  is properly placed and oriented within the mold  38 . As can be seen in  FIG. 13 , the back wall of the recessed area  53  is at an acute angle with respect to the front  44 . When the cap  42  is attached to the mold  38 , the angle of the back wall  53  causes the weldment  10  to be disposed at an acute angle A with respect to the horizontal. This results in the weldment  10  being disposed at the acute angle A with respect to the bottom of the mold as illustrated in  FIG. 8 . This angular displacement of the weldment  10  with respect to a horizontal plane increases the shear forces necessary to dislodge the weldment from the concrete slab  12 . Furthermore this orientation allows greater room for other concrete slab reinforcements as are commonly used in the art to be placed on the arms  18  and  20  then if the arms are in a horizontal position with respect to the concrete slab  12 . 
     Once the weldment  10  is properly positioned within the mold  38  as described above, concrete is poured into the mold  38  to the proper height of the concrete slab. In the preferred embodiment, it is preferable for the weldment to be approximately ¾ inches from the top of the concrete slab for ease of welding. Once the concrete hardens, the slab  12  is removed from the mold  38 . The cap  42  is pulled off the central plate  14  exposing the fasteners or rivets  58 . These are then sheared off flush with the surface of the central plate  14 . The result is a clean weldable surface on the central plate  14 . As the rivets  58  remain in the holes  34  during the concrete pouring, no concrete fills the holes, or is there concrete coming through the holes  34  toward the surface of the central plate  34  such as found in the prior art. This is advantageous as it minimizes spalling or cracking of the concrete during the welding process. Furthermore, it can be seen that when the cap  42  is removed from the central plate  14 , there is a recess or void area around the top edge  15  and bottom edge  16 . This is advantageous in that this void area allows for expansion and contraction of the central plate  14  during the welding operation without spalling or cracking the surrounding concrete. The cap  42  is reusable as no destruction of the cap takes place during the manufacturing of the concrete slabs. 
     Thus there has been provided a weldment to be embedded within a concrete slab and a method of manufacturing the concrete slab that fully satisfies the objects set forth above. While the invention has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.