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This application claims priority from U.S. patent application Ser. No. 08/989,333, filed Dec. 11, 1997, now U.S. Pat. No. 6,003,278. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the field of prefabricated concrete wall construction, and more specifically, to a prefabricated concrete stud wall panel and method of forming the same. 
     2. Description of the Prior Art 
     In response to problems with traditional block construction methods, prefabricated wall panels were developed for rapid construction of buildings. Prefabricated wall panels are shown in U.S. Pat. Nos. 4,751,803, 4,934,121, 5,055,252 and 5,313,753. Two types of prefabricated concrete walls which are commonly used are cavity walls having open pockets between spaced vertical studs and planar walls having insulation panels between the vertical studs to form a substantially planar surface. While both of these types of prefabricated wall panels are generally superior to traditional block construction in terms of costs, performance and reliability, there are still problems associated with both. 
     Many cavity walls use preformed concrete studs from a prior pour where they are formed separately from the top and base beams. A subsequent pour is then necessary to integrate the vertical studs with the top and base beams. As a result, walls formed in this manner require additional pouring and curing time and are often weaker than walls formed from a monolithic pour. Monolithic concrete cavity walls are typically formed by pouring concrete into frames which have forming channels for the vertical studs and the top and base beams. However, it is often difficult to remove the finished wall panel from the forming channels without damaging the concrete studs or beams. 
     In addition to the above, it is often necessary to provide a wood stud at the face of the concrete studs. This is often accomplished by laying wood strips in the forming channels prior to pouring. Typically, the wood strips have a series of nails projecting therefrom and the concrete cures around the nails to secure the wood studs. The process of providing nails in each of the wood strips is time consuming and adds to the manufacturing costs. Additionally, the wood strips are susceptible to cracking and warping, particularly when they are exposed to the wet concrete. 
     The planar walls are typically formed by placing wall studs, insulation, and reinforcing means in a forming assembly and filling the assembly with concrete. The studs and insulation are generally provided with projections which are surrounded by the concrete to integrate the studs and insulation into the wall. Planar walls which utilize wood studs often experience the same problems as the cavity walls do. U.S. Pat. Nos. 5,313,753 and 5,381,635 suggest mounting other common studs, metal or plastic studs, to the front faces of the concrete studs. However, these studs are merely secured to the front of the concrete studs by narrow flanges which may pull from the concrete. As the size of the flanges is increased, the chance that the concrete will fail to flow between and around the flanges also increases. Another problem associated with these metal and plastic studs on the vertical concrete face is that there is no way of passing service lines, such as, plumbing and electrical wiring, through the vertical studs. 
     Accordingly, there exists a need for a monolithic concrete wall which is easy to form, includes integral attachment stud surfaces and overcomes the disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to a stud form of a type used in forming a preformed concrete wall panel having a solid portion and a plurality of vertical concrete studs joined to the solid portion. The stud form includes a substantially U-shaped channel having a face portion that defines an elongated plane and leg portions extending along side of and away from the elongated plane to define a predetermined channel depth. The stud form further includes means for integrally connecting the stud form to the solid portion of the wall panel with the channel opened toward the solid portion. 
     The present invention also includes preformed concrete walls which incorporate the stud form and a system for forming such. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 an isometric view of a cavity wall panel made in accordance with the present invention. 
     FIG. 1A is a partial sectional view of an alternate cavity wall panel. 
     FIG. 2 is an isometric view of a planar wall panel made in accordance with the present invention. 
     FIG. 3 is an elevation view of a vertical stud form used in the wall panel shown in FIG.  1 . 
     FIG. 4 is a section view taken along the line  4 — 4  in FIG.  3 . 
     FIG. 5 is a section of a cavity wall showing an alternate vertical stud form. 
     FIG. 6 is a partial isometric view of the vertical stud form of FIG.  5 . 
     FIG. 7 is a section of a cavity wall showing an alternate vertical stud form. 
     FIG. 8 is a section of a cavity wall showing an alternate vertical stud form. 
     FIG. 9 is a partial isometric view of an alternate vertical stud form. 
     FIG. 10 is an elevation view of a vertical stud form used in the wall panel shown in FIG.  2 . 
     FIG. 11 is a section view taken along the line  11 — 11  in FIG.  10 . 
     FIG. 12 is an isometric view showing an assembly for the formation of the wall panel shown in FIG.  1 . 
     FIG. 13 is an isometric view of a portion of an assembly for formation of the wall panel shown in FIG. 1 utilizing an alternate stud form. 
     FIG. 14 is an isometric view of a portion of the top and bottom forming members. 
     FIG. 15 is an alternate embodiment of the top and bottom forming channels. 
     FIG. 16 is an isometric view of a horizontal stud form positioned in the forming assembly. 
     FIG. 17 is an isometric view showing an alternate assembly for the formation of the wall panel shown in FIG.  1 . 
     FIG. 18 is an isometric view showing an assembly for the formation of the wall panel shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments will be described with reference to the drawing figures wherein like numerals represent like elements throughout. References to orientation refer to the orientation of an installed wall panel and are for clarity only. 
     FIG. 1 shows a cavity wall panel  1  made in accordance with the present invention. The cavity wall panel  1  preferably comprises spaced vertical studs  10  extending between top beam  32  and base beam  34 . The vertical studs  10  include a filled stud channel  12  formed integral with the wall panel  1 . Insulation panels  30  are recessed from the inside face of the wall  1  and extend between the vertical studs  10  and top and base beams  32  and  34 . A concrete surface  36  extends along the back of the wall panel  1 . 
     As shown in FIG. 1A, the wall panel  1  may also include a connection plate  27  extending along the top beam  32 . The connection plate  27  is preferably a wood stud with a plurality of lag bolts  29  extending therefrom. The connection plate  27  is positioned in the frame prior to pouring and then the poured concrete cures around the lag bolts  29  to secure the connection plate  27 . The connection plate  27  permits additional framing members to be nailed directly to the wall panel  1 . 
     FIG. 2 shows a preferred planar wall panel  101  made in accordance with the present invention. The planar wall panel  101  generally comprises spaced vertical studs  110  extending between top beam  132  and base beam  134 . The vertical studs include a filled stud channel  112  which is integral with the wall panel  101 . Insulation panels  130  extend between the vertical studs  110  and with studs  110  form a planar inside face on the wall  101 . The outside face of the wall has a planer concrete surface  136 . A wire lath  138  may also be included behind the insulation panels across the entire area of the wall panel  101 . A connection plate  27  may also be provided in the planar wall panel  101 . 
     A first embodiment of a stud form  12  used in the cavity wall panel  1  is shown in FIGS. 3 and 4. It is preferably made from metal or plastic and forms an integral part of the vertical studs  10 . The stud form  12  is generally a U-shaped channel. It is preferably slightly longer than the length of a vertical stud  10  so that it extends into the top and base beams  32  and  34  of the finished wall. Rebar  20  is positioned in each of the stud forms  12  to tie the vertical studs with the top and base beams  32  and  34 . Flanges  22  extend outward from each open end of the channel and are substantially parallel to the face of the form  12 . Each of the flanges  22  has a plurality of projections  24  extending therefrom for maintaining the insulation panels  30  in position during forming of the cavity wall panel  1 , as will be described in more detail hereinafter. Insulation  14  is placed in the stud form  12  U-channel and extends the length thereof. The insulation  14  provides an area in each vertical stud  10  which is substantially concrete free and allows screws or other fasteners to be set directly into the stud forms  12  in the finished wall. Since finishing materials, such as sheet rock, can be fastened directly to the integral stud forms  12 , separate nailing strips are not required. 
     As shown in FIGS. 3 and 4, sleeves  16  extend between the sides of the stud form  12  at various positions along its length. Each end of each sleeve  16  is preferably flattened over to hold the side walls of the stud form  12  between the ends of the sleeve  16 . In the finished wall panel  1 , the sleeves  16  are enclosed in the cured concrete and thereby integrate the forms  12  with the finished wall. The sleeves  16  also provide a conduit for electrical wires, plumbing and the like. 
     A plurality of weep holes  18  are provided through each side of the stud form  12  near the front thereof. The weep holes  18  are checked during pouring of the cavity wall panel  1  to ensure that concrete is properly flowing to the front of the stud form  12 . 
     Alternate embodiments of the cavity wall stud form  212  are shown in FIGS. 5-9. Each of these alternate cavity wall stud forms  212  has a structure similar to that of stud form  12  of FIGS. 3 and 4, however, the support flange  222  extends inward and has a interconnection flange  230  extending therefrom. The support flanges  222  may be provided with projections for maintaining the insulation panels  30  in position, but are generally not required. 
     In the embodiments of FIGS. 5,  6  and  9 , each interconnection flange  230  is a generally L-shaped member with a first portion  232  extending generally parallel to the legs of the U-shaped channel and a second portion  234  extending generally perpendicular thereto. The second portion  234  extends into and embeds in the concrete vertical stud  10  to maintain the stud form  212  in position. In the embodiment shown in FIG. 7, the interconnection member  230  extends from the support flange  222  at a substantially 45° angle and embeds into the concrete stud  10  to maintain the stud form  212  in position. In the embodiment shown in FIG. 8, the interconnection member  230  extends generally perpendicular to the support flange  222 . A plurality of holes  238  are provided in the interconnection flange  230  along its length. The poured concrete flows through the holes  238  and thereby interconnects the stud form  212  with the concrete stud  10 . As shown in FIG. 6, the interconnection flanges  230  of each of these embodiments may be provided with holes  238  to further assist securing of the stud form  212 . 
     As shown in FIGS. 5-8, insulation  214  generally occupies the U-shaped channel of stud from  212 . Since electrical wires, plumbing and the like can be passed through openings  226  along the legs of the U-shaped forms  212  and directly through the insulation  214 , sleeves will generally not be required. In an alternate embodiment shown in FIG. 9, the insulation  214  may occupy only a portion of the U-shaped channel, thereby allowing concrete to flow into and provide support therein. In such an embodiment, sleeves  216  are preferably provided to allow the electrical wires, plumbing and the like to pass through the vertical stud  10 . 
     The vertical stud form  112  used to form the planar wall panels  101  is shown in FIGS. 10 and 11. The stud form  112  is generally the same as the cavity wall stud form  12  shown in FIGS. 3 and 4 except that the planar wall panel stud form  112  does not have flanges for supporting the insulation since the insulation  130  will be adjacent to the stud form  112 . The stud form  112  may be provided with projections  124  to hold the insulation panels  130 . 
     Formation of a cavity wall panels  1  will now be described with reference to FIGS. 12-17. Formation is generally the same for each of the cavity wall stud forms  12 , 212 . FIG. 14 shows the intersection of two walls of the forming assembly  50 . The forming assembly  50  preferably comprises linear side walls  52  and top and bottom forming channels  54 . The interior sides of the top and bottom forming channels  54  have a number of spaced notches  56  for receiving the vertical stud forms  12 , 212 . The notches  56  are preferably centered at sixteen or twenty-four inches depending on the desired configuration of the wall panel  1 . As can be seen in FIG. 14, the end notches  56  preferably butt against the side walls  52  to allow the end vertical stud forms  12 , 212  having a flange along only one edge or an inwardly extending flange, to be placed against the framing side walls  52 . 
     In an alternate embodiment, shown in FIG. 15, the top and bottom forming channels  54  have an interchangeable inner wall  54   b  which fits into a permanent section of the channel  54   a . This allows varying inner channel sections  54   b , having differently spaced notches, at sixteen or twenty-four inch centers for example, to be quickly interchanged to produce a cavity wall panel  1  having the desired configuration. 
     With the forming assembly  50  in its desired configuration, the vertical stud forms  12  are laid in the notches  56 . The stud forms  12  preferably extend slightly into the top and bottom channels  54  to lock them into the top and base beams  32  and  34  of the finished wall panel  1 . Alternatively, the end of each stud form  12 , 212 , or a portion thereof, extends the width of the respective channel  54  to abut the exterior wall of the channel  54  as shown in FIGS. 13 and 17. This helps to ensure that the stud form  12 , 212  maintains its position during pouring. 
     The rebar  20  in each stud form  12  also extends into the top and base channels  54 . The vertical rebar  20  is attached to horizontal rebar  60  extending in the top and bottom channels  54 . Various spacers and the like are preferably used to maintain the rebar in position prior to pouring. With the vertical stud forms  12  in place, the insulation panels  30  are placed on the flanges  22  of adjacent stud forms  12  and extend between the top and bottom channels  54  and from one stud form flange  22  to the adjacent stud form flange  22 . In this position, the insulation does not cover the top and bottom channels  54  or the vertical stud form  12  U-channels. The flange projections  24  maintain the insulation panels  30  in position during pouring of the concrete. A monolithic concrete pour is used to fill the forming assembly  50 . The concrete fills the top and bottom channels  54  to form the top and base beams  32  and  34  and the vertical stud forms  12  to form the vertical studs  10 . The concrete also provides a solid back wall  36  of approximately two inches. 
     After the concrete cures, the wall panel  1  is lifted from the forming assembly  50 . Since the vertical stud forms  12  are integral with the wall panel  1 , the likelihood that the vertical studs  10  will crack or be improperly formed is greatly reduced. Furthermore, since the sleeves  16  are integral with the wall panel  1 , there is no need for drilling or cutting conduit passages in the vertical studs  10 . 
     In an alternate embodiment of the cavity wall  1 , all of the forming members  50  are linear walls. The top and bottom channels  54  are formed by horizontal stud forms  70  placed within the forming assembly  50 , as shown in FIG.  16 . The horizontal stud forms  70  are similar to the vertical stud forms  12  and also form an integral part of the wall panel  1 . The horizontal stud forms  70  differ from the vertical stud forms  12  in that each has a side wall with notches  56  to receive the vertical stud forms  12 . Formation of the wall panel  1  is simplified since the wall panel  1  does not require lifting from the top and bottom channels. Instead, the forming members  50  can simply be disassembled. 
     Another embodiment of the cavity wall panel  1  is shown in FIG.  17 . As with the previous embodiment, the forming members  50  are linear walls. The stud forms  12 , 212  within the forming members  50  in their desired locations. Horizontal insulation panels  35  are positioned between the adjacent stud forms  12 , 212  and prevent the poured concrete from passing from the top and bottom beams  32  and  34  between adjacent stud forms  12 , 212 . Use of various size horizontal insulation panels  35  permits greater flexibility in positioning of the stud forms  12 , 212 . Once the stud forms  12 , 212  are positioned, the remaining components are placed in the frame, a monolithic concrete pour is provided and the completed wall panel  1  is removed from the forming members in manner similar to that described above. The horizontal insulation panels  35  may be maintained in the finished wall panel  1  or removed after removal of the wall panel from the forming members  50 . 
     FIG. 18 shows the formation of a planar wall panel  101 . Forming members  152  are connected to define forming assembly  150 . In the preferred embodiment, a stud form  112  is laid flat in the frame so that it extends along one of the end frame members  150 . Additional stud forms  112  are placed parallel to the first stud form  112  on sixteen or twenty four inch centers. The studs forms  112  have a length which is less than the length of forming members  152  whereby channels  154  exist at the top and bottom of the forming assembly  150 . 
     Four inch thick expanded foam insulation panels  130 , extending the length of the stud forms  112 , are placed between adjacent stud forms  112 . Reinforcing steel bars  160 , extending the length of the wall panel  101 , are placed in the top and bottom channels  154 . A wire mesh  138  is laid over the entire surface within the framing members. Conventional wet concrete is poured into the form  150 , filling all of the empty space within the form and providing a slab of at least two inch (2″) thick concrete along the entire back of the wall. The concrete will fill the top and bottom channels and form the top and bottom beams  132  and  134 . The concrete surrounds the sleeves  116  and thereby forms the integral vertical studs  110 .

Summary:
A stud form and system for forming a preformed concrete wall panel having a solid portion and a plurality of vertical concrete studs joined to the solid portion. The stud form includes a substantially U-shaped channel having a face portion that defines an elongated plane and leg portions extending along side of and away from the elongated plane to define a predetermined channel depth. The stud form further includes means for integrally connecting the stud form to the solid portion of the wall panel with the channel opened toward the solid portion.