Abstract:
A concrete panel system comprising a plurality of concrete panels arranged in side-by-side fashion on a substantially vertical supporting wall, each of the panels comprising a rectangular body having a front surface and a rear surface and beveled side edges, the side edges each forming an angle of between eighty-five and ninety degrees with the rear surface, and a concave caulking groove lying between and connecting each of the beveled side edges with the front face, the side edges of adjacent panels forming a V-joint between the adjacent panels, a flexible sealant material in a portion of the caulking grooves of adjacent panels and a portion of the V-joint for providing a seal between adjacent panels, and a hanger element embedded in the rear of the panels for securing the panels to the supporting wall.

Description:
This application is a continuation-in-part of U.S. application Ser. No. 08/603,243, filed Feb. 20, 1996 now abandoned. 
    
    
     This invention relates to an improved building panel, as well as a method and apparatus for producing the building panels, and in particular to concrete building panels for exterior use on buildings. This new cladding system is a radical departure from any commonly used systems. 
     FIELD OF THE INVENTION 
     Thin panels of the type produced in accordance with the present invention are used to simulate natural stones. Because the panels are relatively thin, the cost of producing a simulated stone finish is substantially less expensive than when using artificial or real stones. Panels of the type described herein are typically produced in separate molds which is both time consuming and expensive. 
     BACKGROUND OF THE INVENTION 
     Cladding systems such as stucco, brick, stone and artificial stone veneer are typically manufactured off-site and installed on a building using mortars which are prepared on the building site. Such systems often encounter a great number of potential problems related to the particular systems. For example, the quality of the mortar materials is often impaired due to the fact that monitoring of accurate formulas on the building site is difficult. Moreover, variations in weather and temperature can affect the mortars significantly. 
     The installation of typical masonry products is often hindered by weather conditions, such as rain and freezing conditions which usually force a work stoppage unless measures are taken to shield the work area. 
     The quality of these materials is further impaired due to the fact that typically these mortar materials are allowed to air dry without attempting to seal these cementitious products for proper curing. Sealing during curing greatly improves cementitious products thus making them denser and reducing a condition known as efflorescing, a process that allows calcium to migrate from the material and deposit on the surface. Efflorescence is extremely difficult to prevent in presently known masonry cladding installation systems. 
     Typically with presently known masonry cladding systems it is necessary to provide mixing equipment on job sites for preparing the cementitious mortar products that are required for installation. 
     In the case of stucco it becomes necessary to carry out the installation in three or four steps such as: wire installation, first layer of stucco (scratch coat) second layer (float coat) and top layer (finish coat). Often with stucco or artificial stone, an inferior cladding system is achieved due to the fact that no venting space is provided in behind the cladding. 
     Brick and stone cladding systems are generally very heavy, and special consideration must be given, especially in the areas of the foundation and over window and door openings, to supporting this weight. 
     Generally speaking all existing masonry cladding systems are plagued with cracking problems. It is virtually impossible to prevent this condition. Furthermore, all existing masonry cladding systems require unsightly expansion joints, both laterally and vertically. Concealing these joints is virtually impossible. 
     It is also difficult to maintain a uniform minimum thickness with presently known masonry cladding systems. 
     Presently known artificial stone cladding systems require surface preparation such as a stucco base coat. This adds greatly to their expense. 
     Finally, known masonry cladding systems are prone to dirt entrapment. 
     As is evident from the above discussion of the prior art, what is needed is a cladding system where these above mentioned conditions are eliminated or at least minimized. 
     OBJECTS OF THE INVENTION 
     The object of the present invention is to solve the above mentioned problems by providing a relatively simple, efficient method and apparatus for producing concrete panels. 
     An object of the present invention is to provide a panel with a peripheral shoulder that, with an adjoining panel forms, a channel that is most conducive for receiving caulking. 
     Another object of the invention is that a V-groove between panels is formed that offers a maximum surface for caulking adhesion. 
     Another object of the invention is to eliminate the need for unsightly expansion joints. 
     Another object of this invention is to provide concrete panels having beveled side edges which provide a limited crush zone that absorbs thermal expansion without damage to the panel itself. 
     Another feature of this invention is that each panel has a molded center mark. This feature greatly assists in centering the panels during installation. This mark is located in the side shoulder and becomes covered by the flexible grout. 
     Another object of this invention is to provide a masonry product which can be installed without mortars, glues, nails, or additional brackets. 
     Another feature of the invention is that each panel has two cast-in-place hangers that provide several advantages. 
     A feature of the hanger allows the panel to be simply screwed to a wall. 
     Another feature of the hanger is that it provides a vent or draining space behind the panel preventing any water from ever contacting the building itself. 
     Another feature of the hanger is that a kink in the end of the nails prevent pull out and that the point of the nails prevent surface spotting that are normally caused by minor temperature differences of metal and curing concrete. 
     Another feature of this invention is that the plural leg sets of the hangers have spring action and are shaped in such a way that concrete break out during installation is avoided, and that proper panel tension is provided and that adequate strength against cyclonic conditions exists. 
     It is another feature of the hangers that four syphoning bridges are provided on each hanger. These bridges help to prevent of concrete from traveling into the hanger positioning cavities. 
     Another feature of the hanger is that the center section can be cut away and when horizontally screwed to the wall it can be used as a stabilizing bracket for a single hangered smaller panel. 
     Another object of the invention is that an unusually thin but relatively rigid thermoformed plastic form is used to greatly reduce mold costs. 
     Another feature of the form is that hanger positioning cavities are built in allowing the hangers to remain accurately positioned during vibration. 
     It is a feature of this invention that the forms feature releasing strips, back-up panels, stacking strips and a thin membrane that prevents thermal cracking. These thin fragile forms can be stacked in an unusually small space and support in excess of one ton of loading capacity. 
     It is a feature of this invention that a multi-layered form stack can be demolded or removed from the mold simultaneously by lifting and pivoting the complete stack  180  degrees. The mold releasing strips gently push on the edges of the form thus releasing all the panels and allowing them to rest on the bottom of the back-up panel, ready for bundling and shipping. 
     Another object of the invention is to provide a masonry product that can be installed during freezing temperatures without the need for hording, which is the practice of building a temporary enclosure of canvas, plastic, etc. around the work area to keep out weather, and to enable heating of the work area within the enclosure. 
     Another object of this invention is to provide panels which are compact and can be installed with great speed. 
     Another object of the invention is to provide an improved “mortar” which is crack resistant. This is achieved through the use of urethane caulking that is then coated with silica sand, giving the caulking an aesthetically pleasing mortar appearance. This silica sand coating now greatly improves the resistance to ultraviolet radiation damage of the urethane caulking. An additional coating of dolomite dust avoids the caulking becoming soiled from airborne dust particles. 
     Another feature of the invention is the bottom and top “J” channels have perforations to allow the vent space to function and also retain the bottom of the bottom panel and the top of the top panel. 
     Another feature of the invention is a dispensing apparatus with lateral rollers and tracks and an adjustable chamber equal in volume to a panel. 
     Another object of the invention is to provide a molding method which utilizes lateral shock vibration, jarring air bubbles free instantly and allowing them to travel away from what will be the panel face virtually eliminating all surface air voids. 
     Another object of the invention is to provide a tilting stretch wrap bundler which greatly reduces shipping breakage. 
     Another object of this invention is to provide concrete panels which can be complimented with a comprehensive line of concrete architectural component that are produced with the same method as described above resulting in a dramatic new look that simulates European architecture at a great cost saving. 
     It is another feature of this invention to easily obtain a number of different surface profiles that will offer an unlimited choice of design alternatives. 
     It is another object of the invention to provide panels which have a glossy concrete surface that is resistant to any surface dirt entrapment. The glossy surface is achieved by high gloss plastic molds. 
     It is another object of the invention to obtain better quality control by providing panels which are prefabricated under controlled conditions dissimilar to other masonry cladding systems like stucco, artificial stone, brick and real stone. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the invention relates to a method of producing a concrete building panel of the type including a thin concrete body and metal hangers embedded in the body for mounting the panel, said method comprising the steps of: 
     (a) placing hangers for the panel on a form; 
     (b) loading a transfer dispenser with sufficient concrete to fill the form; 
     (c) placing the transfer dispenser over the form, to release the concrete into the form; and 
     (d) applying shock vibration to the form to release air bubbles and settle the concrete in the form. 
     The invention also relates to an apparatus for producing a concrete building panel of the type including a thin, concrete body and metal hangers embedded in the body for mounting the panel, said apparatus comprising: 
     (a) thin plastic form means defining a cavity including bottom wall means, side wall means and an open top for receiving concrete; 
     (b) hanger positioning cavity means on said side wall means for supporting said metal hangers in the open top of the form; 
     (c) transfer dispenser means for receiving and dispensing a predetermined volume of concrete into said form means; and 
     (d) vibrator means for applying shock vibration to said form to eliminate air pockets in the concrete. 
     The invention also relates to an improved concrete building panel which comprises a thin concrete body having metal hangers embedded in the rear of the body for mounting the panel, and a decorative front face. The front face may be textured, smooth, colored or otherwise finished to provide a decorative appearance according to the design tastes of the designer or owner. 
     The front and the rear faces of the body are substantially parallel, and the sides of the panel comprise a beveled edge which adjoins the rear face at an angle slightly less than ninety degrees, and extends toward the front face. A caulking ledge or groove extends around the periphery of the panel and joins the beveled edge and the front face. The caulking ledge or groove is a concave recessed groove which will receive a caulking material for sealing the space between adjacent panels. 
     The adjacent panels will be in contact with each other at the back edge of the panels, but because of the slight bevel, the adjacent panels do not contact each other at the front face. In this manner, any expansion of the panels will cause compression cracking or crushing of the panel only at the rear of the panel, and only in a localized area. The caulking material, such as a urethane caulk, will seal the space between the panels and prevent intrusion of moisture. 
     As noted above, a silica sand may then be applied over the caulking if desired, to alter the aesthetic appearance of the structure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described, by way of example only, reference being had to the accompanying drawings in which: 
     FIG. 1 is a front view of a textured concrete panel produced using the method and apparatus of the invention; 
     FIG. 2 is a side view of the panel of FIG. 1; 
     FIG. 3 is a front view of a beveled concrete panel; 
     FIG. 4 is a side view of the panel of FIG. 3; 
     FIG. 5 is a view of a range of planar and contoured panels and moldings: 
     FIG. 6 is a rear view of the panels of FIGS. 1 and 3; 
     FIG. 7 is a perspective view of a hanger used in the panels of FIGS. 1 to  6 ; 
     FIG. 8 is a perspective view of the top portion of the hanger of FIG. 7; 
     FIG. 9 is a perspective view of a stabilizing clip; 
     FIG. 10 is a perspective view of the bottom portion of hanger of FIG. 7; 
     FIG. 11 is a bottom view of the hanger of FIG. 7; 
     FIG. 12 is a top view of the hanger of FIG. 7; 
     FIG. 13 is an end view of the hanger of FIGS. 7 and 11 as seen from the left of FIG. 11; 
     FIG. 14 is an end view of the hanger of FIGS. 7 and 11 as seen from the right of FIG. 11; 
     FIG. 15 is a perspective view of a section of the form and back-up panel and the hanger positioning cavities; 
     FIG.  15 ( a ) is a partially sectional perspective view of the form referencing the formation of the caulking grooves; 
     FIG. 16 is a perspective view of a form filled with concrete complete with hangers located in the hanger positioning cavities; 
     FIG. 17 is a perspective view of the vibrating table and the shock vibrator; 
     FIG. 18 is a cross section of a filled form of FIG. 15; 
     FIG. 19 is a cross section of the form of FIG. 15 with focus on stacking strips and the releasing strips; 
     FIG. 20 is a top view cross section of two panels as of FIG. 1 installed on a wall; 
     FIG. 21 is a side view cross section of two panels as of FIG. 1 installed on a wall, showing special focus on interlocking hangers of FIG. 7; 
     FIG. 22 is an enlarged cross-sectional view of two adjoining panels of FIG. 1 showing in detail the crush zone and the flexible grout in the V-joint and the caulking shoulders; 
     FIG. 23 is a cross section of filled forms as of FIG. 15 in a stacked formation; 
     FIG. 24 is a perspective view of a top and bottom installation channels as part of the present invention; 
     FIG. 25 is a perspective view of a stack rotating device used for multiple simultaneous demolding; 
     FIG. 26 shows a perspective view of the rotating demolder as of FIG. 25 in a loaded state as part of this invention; 
     FIG. 27 shows a tilting bundle stretch wrapper as part of this invention. Shown tilted and ready for loading; 
     FIG. 29 shows long cross section of concrete extruder shown here while extrusion cavity is being filled; 
     FIG. 30 shows extruder with closed doors and full extrusion cavity; 
     FIG. 31 shows extruder during form filling cycle; 
     FIG. 32 shows short cross section of concrete extrude of FIG.  29 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 to  6 , the method and apparatus of the present invention are designed to produce a concrete panel generally indicated at  1 . The panel includes a thin rectangular body  2 , typical dimensions of which are 12″×18″×⅝″, however, irregular shapes as shown in FIG. 5 may also be formed. The body  2  has a textured, beveled or irregular outer or front surface  3 , sloping, tapered sides  5  and  6  and a rough, planar inner or rear surface  7 . A groove  9  or caulking ledge extends around the side periphery of the panel  1 . FIGS. 3 and 4 show a similar panel  1 A to that of FIGS. 1 and 2 but with smooth face  3 A &amp;  2 A. A pair of hangers  10  are embedded in the rear surface  7  of the panel  1 A. The hangers  10  (FIG. 6) are used to mount the panel  1  on plywood backing or other suitable backing shown in FIGS. 20 and 21 when finishing a wall. A flexible grout is provided between the panels to complete the exterior wall. 
     As shown in FIGS. 7 to  10 , each hanger  10  includes an elongated, galvanized metal body  12  (or other suitable materials such as plastic) defining a central channel  13  with a generally U-shaped cross section extending outwardly from the edges of the channel  13 . A locating hole  16  (FIGS. 11 and 12) is provided in one end of the body  12 , and a pair of diverging spring arms  17  are provided on the other end of the body. The arms  17  are extensions of the flanges  14 . Slits are cut in the flanges  14  near each end thereof, and the thus formed prongs  18  are bent at approximately 45 degrees to the flanges  14  for anchoring the hanger  10  in the concrete body  2  of the panel  1 . Prongs  18  also include sharp pointed tips  23  which are also bent at  24 ; this prevents surface spotting; also shown in FIG. 7 are bottom and top syphoning bridges  19  and  19 A respectively, these aid in transfer of concrete around hangers  10  and more specifically prevent concrete from flowing into hanger positioning cavities  40  and  41 . 
     Numerals  25  and  26  (FIGS. 8 and 10) indicate top and bottom hanger parts, which when separated from the main hanger body  12  permit use as separate hanger part portions. Numeral  28  (FIG. 11) indicates the cut, to sever top and bottom hanger parts, and numeral  29  indicates cut to sever stabilizing clip (FIG.  9 ). 
     Referring to FIGS. 15 to  19 , and FIGS. 29 to  32 , panels  1  are produced using a form  30  and an extruder  100  generally indicated at FIGS. 29 to  32 , respectively. The form  30  shown in part section in FIG.  15 ( a ) is defined by a thin, molded, polystyrene sheet  34 , which includes a plurality of cavities  35  for receiving concrete. A flat ledge  34  (FIG. 15) is provided around the top periphery of each cavity  35 . Pairs of hanger positioning cavities  40  and  41  are molded, these cavities  40  and  41  formed in the ledge  34  on opposite sides of each cavity are intended to support the ends of the hangers  10  during vibration. 
     The finished panel  1  as shown in FIGS. 1-4, and more clearly in FIG. 22, has beveled or tapered edges  9 ( a ) and a further groove or recess  9  which is referred to here as a caulking groove. The edges  9 ( a ) are beveled so as to form an angle of between eighty-five and ninety degrees with the rear surface  7  of the panel. In FIG.  15 ( a ) it will be seen that the mold as form  30  is configured to provide the tapered sides and the groove the latter being formed by the projection  37   a.    
     As best shown in FIGS. 15 and 23, each form  30  includes releasing strips  38  and stacking strips  39 . 
     As best shown in FIGS. 19 and 23, the vertical formation in stacking strips  39  are separated by the releasing strips  38  and form edges  34 , thus causing the back-up panels  32  to become load bearing, and allow curing concrete panels to be stacked in this suspended position, the releasing strip  38  being bonded to form  30 . The stacking strip  39  is bonded to the back-up panels  32 . 
     The extruder  100  shown in FIGS. 29 to  32  is used to transfer concrete from a source thereof to the cavities  35  in the form  30 . 
     In order to produce panels  1  of the type shown in FIGS. 1 to  6 , concrete is poured into form  30  and hangers  10  are placed over each form cavity  35 . 
     As best shown in FIG. 16, the hangers  10  rest in the hanger positioning cavities  40  and  41  and are aligned end to end to adjacent cavities. The form  30  with the hangers  10  hereon is placed on a vibrating table which includes motor  47 , table frame  48 , shown in FIG. 17, the top surface of which should be as clean as possible to avoid damage to the form by hard particles. 
     A center mark  42  (FIG. 15) is positioned in the form side wall  37 . This center mark  42  becomes cast into each concrete panel making installation much easier. As best shown in FIG. 17 the form  30  is placed on top  46  of the vibrating table  45 . The table is equipped with four rubber shock absorbers, or dampeners  54 , a vibrator motor  47 , and frame  48 . 
     A shock vibrator  50  with hydraulic motor  52  is also mounted to the frame  48 . Lateral vibrating shock action is produced by an eccentric wheel  53  and transferred to the vibrating table  45  through the shock vibrator connector arm  51 . This lateral shock action of approximately 200 shocks per minute jars air bubbles free from the form cavity bottom  36  instantly and allows them to travel to the surface or the back of the panel  7 . As part of this invention it was discovered that rotary vibrating action at high RPM&#39;s, e.g. 10000 RPM and the lateral shock action is extremely effective in a speedy air bubble elimination. 
     As best shown in FIG. 18, the syphoning bridges  19  and  19 A aid in minimizing the undesirable effect of concrete liquids traveling along the hanger body  12  during vibration and settling in the hanger positioning cavities  40  and  41 . 
     As best shown in FIG. 20, when panels  1  are installed over the building substrate  56  a venting or draining gap  55  is formed by the space between the substrate  56  and the rear surface  7  of the panel  1 , preventing water from accumulating behind the panels  1 . 
     As best shown in FIG. 21, when installing the next row of panels  1  the arms  17  interlock behind the previously installed row of panels  1  and hold the panels  1  firmly to the building substrate. The spring action of arms  17  have the dual purpose of holding the bottom panel  1  firmly into place and also reducing the risk of over tension which would result in concrete breakout. 
     As best shown in FIG. 22 a crush zone  60  is formed at the rear of the panels  1  at the point of contact between two adjoining panels  1  installed on a house wall. This crush zone  60  absorbs thermal expansion pressures of installed panels  1  without harm to the individual panels  1  and without resulting in compounded expansion. Because of the bevel at the edge, the two adjacent panels  1  only contact at the rear edge corner, thus limiting the crush zone  60 , and preventing cracking of the entire panel. The thermal expansion pressure exerted on the concrete panel  1  only occurs one time when the maximum temperature is reached for the area in which the panels  1  are installed. Thereafter, all thermal expansion is absorbed by the caulking material  59 . This crush zone  60  eliminates the need for expansion joints which are required in prior systems. The crush zone  60  also prevents thermal cracks from developing around openings such as windows and doors. Even the presence of expansion joints in prior systems has not completely eliminated such cracks as does the present system with the crush zone  60  and flexible caulking  59 . 
     As best shown in FIG. 22 a V-joint  61  results when two adjoining panels  1  are installed adjacent to each other. The apex of the V-joint  61  lies in the plane of the rear surface of the panels  1 , and the beveled edges  9   a  extend from the rear of the panel toward the front where the caulking shoulder  9  is formed. Thus, the V-joint  61  opens from the rear of the panels toward the front, and the V-joint  61  enables maximum caulking adhesion and minimum caulking  59  usage as the caulking is applied into the joint. The caulking gun applicator coacts with the caulking shoulders  9  which guide the tip of the applicator to provide a contour which is most conducive to installing a good quality and speedy caulking joint. The caulking material  59  or sealant extends slightly into the V-joint  61  and in part of the caulking groove in order to ensure the maximum adhesion and minimum usage of sealant material  59 . The concave caulking shoulders  9  also greatly assist in guiding the caulking gun tip (not shown), and result in caulking beads  59  that require no tooling except for minor tooling at V-joint  61  intersections. The V-joint  61  has an angle of eight degrees maximum, formed from the bevel on each side of the panels  1 . An added benefit of this bevel is that the bevel facilitates removal of the panel from the mold. 
     Also shown in FIG. 22 is a silica sand coating  58  which is applied on the surface of the caulking bead, or flexible grout  59 . This silica sand coating is applied with a mini spray hopper or brush (not shown), and the result is a flexible grout seam that is crack resistant and U.V. light resistant. 
     As best shown in FIG. 23, forms  30  can be stacked preferably to a minimum height of 5 feet. In practice, each form located at the bottom is capable of load bearing weight in excess of one ton. A thin watertight membrane  63  is collated between each form and thus serving a triple function of sealing the concrete and preventing thermal shrinkage cracks, preventing the back up panel from warping due to water absorption and protecting the underside of the back-up panel from scratches during the demolding process. 
     As best shown in FIG. 24, a bottom  65  and a top  64  galvanized J-channel are utilized to assist installation of the panel  1  on a building. The face  67  of these J-channel are coated with silica sand to match other flexible grout seams  59 . The bottom J-channel  65  features bottom perforations  66  allowing for air circulation behind the panels  1  and also water is allowed to drain from these holes. Panels  1  installed in the top channel  64  have adequate air spaces and no further perforations are required. 
     As best shown in FIGS. 25 and 26, a multi-layered form demolder  70  is provided which receives a stacked  20  pallet of full forms  30  between upper movable forks  71  and lower fixed forks  74 . The movable forks  71  are lowered and the locking side doors  73  hinged at  72  are firmly locked in place. The lifting mechanism  75  is activated to gain clearance for a 180 degree turn of the  25  rotating back plate  76 . This action results in the simultaneous demolding of a multi-layer stack. 
     As best shown in FIGS. 27 and 28, a tiltable bundle shrink wrapper  80  is part of this invention. Unlike other building panels  1 or tiles, the panels  1  have metal protruding at the top and bottom resulting in an unchallenged difficulty in transporting these panels  1 . The device  80  is placed in its tilting position by activating foot pedal  87  which allows the device to tilt. A locking pin  89  aided by a spring  88  holds the device firmly when tilted. 
     Panels  1  are loaded against the retention forks  81  on the turntable  83 . The stacking guides  82  aid in achieving an orderly bundle. The device is now placed in its level position by simply pulling it forward. The stretch wrap  90  is started as best shown in FIG.  28 . The knee switch  85  activates the motor  84  and turns the turntable  83 . 
     As best shown in FIGS. 29 to  32 , concrete is filled from a continuous concrete source  92  into the extruder hopper  93 . The hopper slides on wheels  91  horizontally. Two augers  94  moves the concrete to the prefill cavity  95 . The telescope door  96  is then opened and the concrete falls into the adjustable extruder cavity  97 . The telescoping door is then closed again. The extruder cavity door  99  is actuated by an hydraulic cylinder  98 . 
     Finally, FIG. 31 shows the extrusion of concrete from the cavity  97  into form cavities  35 . Upon completion of the vibration and shock vibration step, the concrete is allowed to cure, completing a panel. 
     While this invention has been described as having certain preferred features and embodiments, it will be understood that it is capable of still further variation and modification with out departing from the spirit of the invention, and this application is intended to cover any and all variations and modifications of the invention as may be apparent from the foregoing description and claims, and as may be within the spirit of the invention and the scope of the appended claims.