Abstract:
A machine for imprinting patterns onto uncured concrete in an elongated bed includes a frame for positioning the finishing machine over the bed. A lower patterning unit suspended from the frame is movable backward and forward of the concrete bed and a press assembly moves the pattern in and out of contact with uncured concrete on the elongated bed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a concrete finishing machine for use in concrete casting system. Such casting systems typically have either a moving bed or a fixed bed on which the concrete panels or planks are formed. In the moving bed systems, a long bed moves on a track past each of the various stations that form the panels. See for example, U.S. Pat. No. 4,369,153. In a fixed bed, the various stations themselves move, such as a hopper that pours concrete onto the bed. 
     Prior art approaches have used hand laid patterns which are very labor intensive. Very simple longitudinal ribbing is relatively easy to accomplish as shown in U.S. Pat. No. 4,457,682. Brick imprinting on surfaces has been tried with a number of different approaches, including U.S. Pat. No. 5,318,426 which is commonly owned, the disclosure of which is incorporated herein by reference. 
     The existing machine approaches allow either brick imprinting or raking to be laid down as patterns. It is very desirable to be able to produce panels that have a variety of patterns on them, such as a lower brick imprint with a raked section above the bricks, or rakes with gaps in the raking or bands in addition to longitudinal raking. 
     The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a concrete finishing machine which may be positioned over a casting bed, whether fixed or movable. The description herein will refer to use with a moving bed, but the finishing machine may be readily used in a fixed bed system by simply moving the finishing machine as with all other components of such systems. 
     The concrete finishing machine is described in conjunction with an automated system for casting concrete. However, the advantages of the finishing machine are also obtained on non-automated casting systems. 
     Typically, an entire casting bed will have a detailed drawing, often on CAD (Computer Assisted Drafting) which shows the workers where each feature throughout the bed must be placed. This involves giving each of the plant workers the required prints of the bed to be cast so they know exactly where each feature must be added. 
     It is also very desirable in either system to be able to accurately and easy imprint the upper surface of the still uncured concrete with a variety of patterns, such as a simulated brick or raked lines for surface decorations. Tying in with the CAD drawings and the position of the bed with a concrete finishing machine ensures that imprinted patterning may be accurately made with a minimum of cost and personnel. 
     This disclosure shows an automated system for casting concrete panels which takes CAD drawings for a casting bed that covers the features throughout the length of the bed and accurately projects a laser generated image of the drawings over the bed at the exact location corresponding to the CAD drawings. This enables the workers to perform whatever functions are needed at that location on the bed, such as placement of lifting lug points, openings, insulation, and surface finishes. 
     An automated system utilizes laser projectors such as those available from LAP GmbH Laser Applikationen of Lueneburg, Germany in combination with its CAD drawings and a positioning system on its concrete casting bed to relate the precise position on the casting bed to the CAD which is tied to the laser projector. This allows the CAD drawings to be projected onto the casting bed as a visible drawing representation such that the workers can immediately see precisely where each and every feature to be included in the concrete which they are about to cast. 
     The finishing machine of the invention is situated over the casting bed and includes a readily changeable lower pattern unit attached to a press assembly. The press assembly is carried on a framework that allows it to be moved up and down in order for the pattern unit to impress its pattern into the uncured concrete. It also includes tracks and actuators to allow the unit to move back and forth relative to the length of the casting bed such that the pattern may be applied, lifted, moved to the next position and then be applied again. 
     The finishing machine includes distance measuring sensors which detects the height of the concrete surface relative to the machine in order to automatically adjust the patterning to the desired depth, even as the concrete below has minor alterations in thickness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A detailed description of the invention is hereafter described with specific reference being made to the drawings in which: 
         FIG. 1  is a top view of the finishing machine over a concrete casting bed; 
         FIG. 2  is an end, partially perspective view showing the finishing machine over a moving bed; 
         FIG. 3  is an end view showing a bed positioning mechanism; 
         FIG. 4  is a partial perspective view of the finishing machine; 
         FIG. 5  is a top view of the finishing machine; 
         FIG. 6  is a side view of the finishing machine showing the press patterning; 
         FIG. 7  is an end view of the finishing machine showing the press; and 
         FIG. 8  is an end view showing the press pattern detached. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , the form of the finishing machine used in connection with a moving casting bed  10  is employed is shown. Moving casting beds  10  are well known in the art, and typically include a concrete form  12  that may be 900 feet long. The bed  10  has tracks  14  that ride on rails such that the entire bed  10  may be moved down the rails. This allows the bed  10  to be moved to each of the fixed stations, such as for pouring concrete on the bed from an overhead hopper. 
     The underside of a typical casting bed  10  is shown in  FIGS. 2-4  in which it will be seen that a mechanism to precisely indicate the exact position on the bed  10  may be generated. The bed position device  20  is used to provide a signal that indicates the exact position of the bed to a known position in the plant. As shown, it involves the addition of a rack  22  to the underside of the casting bed  10 . The rack  22  engages with a pinion  24  which is attached to an encoder  26 . The rack  22  has a fixed rack anchor  28 . The bed  10  includes a bed fixture bracket  30  which together with a linear decoder post  32  and a vemeer code readable scale  34  and linear encoded track monitor  36  is able to accurately gauge and report any differences in length of the bed due to tension of the prestressing cables or temperature changes. This allows variations in the casting bed  10  length to be accounted for due to seasonal temperature changes, and stress changes due to prestressing in the bed which over a very long casting bed  10  can be significant. The fixed encoder  26  is fed the bed length information and transmits the exact position on the bed as read by the rack  22 . 
       FIGS. 1 and 2  show a finishing machine  60  over the bed that can apply rake finishes, brick imprints or any other surface patterning desired.  FIG. 2  shows a surface finishing machine  60  situated over casting bed  10 . It carries a lower fragmentary pattern unit  62  which may receive information from a control station  84  which may receive bed position information, any temperature compensation and information on the CAD drawing requirements and imprints the uncured concrete surface accordingly. Alternatively, the pattern unit may be manually operated or may simply receive position information without a tie-in to CAD drawings and a laser projection system. The lower pattern unit  62  is readily removable such that another unit with a different pattern may be attached. Thus, the bed may be imprinted exactly where needed, to the depth needed with whatever patterns are desired, from varying brick patterns to rake finishes and the like. 
     As best shown in  FIGS. 4-8 , the finishing machine  60  includes a frame  64 , which in the case of a moving bed  10  positions the machine  60  over the bed without contact. A press assembly  66  carries the lower pattern unit  62  which may be readily swapped out with a different pattern. The press assembly  66  is raised and lowered by vertical actuators  70  which are controlled to imprint the pattern to the desired depth on the uncured concrete surface  72 . The entire press assembly  66  may move lengthwise with relation to the bed  10  by virtue of tandem linear tracks  76  to which it is mounted by rollers  78 . The side view of  FIG. 6  shows that the press assembly  66  is able to move back and forth along the direction of the casting bed  10  by virtue of the tandem tracks  76  via linear actuators  80 . 
     Distance measuring sensors  82  as shown in  FIG. 6  may be advantageously employed to detect the distance between a fixed known position and the upper surface  72  of the concrete below the sensor. When the distance varies, it means that the thickness of the uncured concrete has varied slightly. With this information, the depth of the pattern may be kept constant by automatically adjusting the depth the lower patterning unit  62  descends to by the press assembly  66 . Otherwise, the finished pattern could be too deep or too shallow and the aesthetics of the design could be less than optimal. The distance measuring sensors  82  may be the widely available laser emitters which are used to measure distance and which distance information can be fed to the machine in order to adjust the depth of the pattern as to concrete depth varies. 
     A control station  84  is connected to finishing machine  60  and bed positioning device  20 . Thus, the information on the exact bed position relative to the finishing machine may be transmitted and the press assembly may be controlled accordingly. 
     The invention has been shown in the figures in connection with a moving casting bed. The invention is also usable in fixed bed casting, in which the bed is stationary but the various components used in making the concrete panels move about the bed. The laser would simply be on a track above and along the entire length of the bed. The bed positioning device would also be above the bed and relative to the moving components, such as the concrete hopper, etc. The finishing machine would then be mounted to be movable along the length of the casting bed. 
     While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
     This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.