Abstract:
A saw apparatus for sawing paving slabs has a frame mounted on a ground contacting propulsion member such that the frame may move above a slab to be cut. A saw support assembly has an engaged position and a removed position; the engaged position disposing a blade of a saw in cutting engagement with a top surface of a slab to be cut. The saw is mounted on the saw assembly and the saw assembly is mounted on the frame and the frame is mounted on the ground contact propulsion members such that no part of said frame need contact the slab during cutting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The field of the present invention is in paving equipment. 
         [0004]    2. Related Art 
         [0005]    Poured concrete roadways are known to expand and contract in response to seasonal temperature variations. This expansion and contraction will cause uncontrolled cracking in random patterns that will disrupt the surface, provide a rough ride for vehicles traveling over the road and shorten the lifespan of the roadway. The traditional response has been to deliberately cut controlled expansion joints as slots in the roadway slab in order to provide room for expansion in a controlled fashion. These expansion joints in concrete roadways are cut in straight lines, have short metal dowel bars embedded in the concrete underneath them for strength and are typically sealed by a compressible yet waterproof material to keep ice from forming in the cracks. Usually the expansion joints are cut perpendicular to the direction of travel on the roadway, although angled variants are known. 
         [0006]    During construction, there are frequent circumstances, for example, hot, windy conditions, when the contractor pouring a new roadway slab faces the possibility of the concrete drying quickly enough that uncontrolled cracking in random patterns on the surface of the slab may begin quickly, sometimes within the space of a few hours. A new slab for a roadway or a runway at an airport having uncontrolled cracking will not meet the specifications of the Department of Transportation or other authority responsible for the new paving. Accordingly, if such uncontrolled cracking appears in newly poured slab, contractor will be required to tear out the slab and start over. 
         [0007]    Controlled expansion joint slots are cut into newly poured paving slabs by concrete saws. Concrete saws are comprised of a rotary disk having a cutting edge, a power supply such as an engine to turn the blade and a height adjustment apparatus. Prior art concrete saws, particularly those powerful enough for the paving industry, were heavy, sometimes up to a ton in weight. This weight was supported by wheels, typically four. The wheels on the prior art machines were small metal wheels in order to support the weight of the saw. The small size of the wheels consequently delivered a heavy loading factor to the surface of the slab being cut due to the small area of the wheels touching the slab surface. Accordingly, prior art saws could only work on slabs that were already dry. If the slab was not thoroughly dry, the weight of the concrete saw would cause the saw wheels to sink into the insufficiently dry slab surface, thereby creating unacceptable indentations in it. Hence prior art saws could not be used to cut expansion slots in slabs that were drying too quickly to avoid rapid cracking, because such slabs were still too wet to support the saw&#39;s weight. 
         [0008]    It is also required that the concrete saws cut the expansion joints in the proper location, and to be as straight as possible. This is done in the prior art by chalk lines. The chalk line was followed by a guide arm on prior art concrete saws that would extend ahead of the rotating blade. A workman would physically move the entire saw as necessary to keep the guide arm on the chalk line. The expansion joint, once cut, was thereafter flushed to remove dust and other debris from it by air pressure, sand blasting or water flushing. The expansion joint was thereafter filled with a material such as silicon and/or caulk to seal it. 
       SUMMARY OF THE INVENTION 
       [0009]    A saw apparatus for sawing paving slabs has a frame mounted on a ground contacting propulsion member such that the frame may move above a slab to be cut without touching it. A saw support assembly has an engaged position and a removed position; the engaged position disposing a blade of a saw in cutting engagement with a top surface of a slab to be cut. The saw is mounted on the saw assembly and the saw assembly is mounted on the frame and the frame is mounted on the ground contact propulsion members such that no part of said frame need contact the slab during cutting. 
         [0010]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of the concrete saw in the present invention in an engaged position. 
           [0012]      FIG. 2  is a perspective view of the concrete saw in a retracted position. 
           [0013]      FIG. 3  is a perspective view of the concrete saw. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0014]    Referring now to the drawings wherein like numbers indicate like elements, a transverse frame  10  comprised of transverse frame beams  12  is provided for supporting the elements of the concrete saw. The entire apparatus is supported by ground contacting propulsion members, which in the depicted embodiment are a pair of tracks  14 . Tracks  14  support the frame  10  in a position that does not contact the roadway slab being created. The tracks  14  are spaced sufficiently far apart so that the entire apparatus  10  straddles the roadway slab without the necessity of contacting it. The tracks of course may advance the frame  10  and the elements mounted on it along the length of the roadway in a continuous fashion without requiring disassembly and reassembly of the frame in each successive sawing location and without requiring other pieces of equipment to move the frame  10 . Frame beams  12  may be unbolted and widened or shortened and re-assembled at the selected width in order to accommodate the dimension of the roadway to be paved before paving begins. Alternatively, hydraulic slides may be used to adjust width. Frame  10  is supported by support elements  16  which, in the depicted embodiment, are substantially vertical telescoping hydraulic cylinders  16 . 
         [0015]    Saw support assembly  20  is comprised of fixed support members  22  which in the depicted embodiment are longitudinal beams, and moving support members  24 , which in the depicted embodiment are also longitudinally extending beams. These are attached by hinges  26  in the depicted embodiment. Transverse beam  28  is supported by moving support members  24  and fixedly attached to them. In the depicted embodiment, the attachment of the transverse beam  28  to moving support members  24  may be with adjustable attachments  30  so that a user can set a preferred level of elevation for transverse beam  28  when it is to be deployed in an engaged position. 
         [0016]    Mounted on transverse beam  28  is at least one concrete saw  32 . The concrete saw  32  is comprised of a rotating disk  34  having a cutting edge. The rotating disk is mounted on an axle  36  which is in turn mounted on a saw support element  38  which may be raised and lowered to a user selected depth. Adjusting the depth of the cut in the depicted embodiment is achieved by adjusting the hydraulic height adjuster  40 . The support element  38  and height adjuster  40  are pivotally mounted on a saw frame  42 . Height adjustment may be controlled by an elevation wand  52 , which may signal a movement of the saw above or below user selected thresholds for an acceptable height range. 
         [0017]    The saw frame  42  is mounted on transverse beam  28  in a manner to allow for transverse travel of the saw assembly  32  along the transverse beam  28 . In the depicted embodiment, travel is mediated by a rack and pinion assembly  44 . The saw must be powered and, in the depicted embodiment, power is via a hydraulic motor  46 . Hydraulic motors for the saws  46  and other hydraulic motors  48  powering the tracks are powered by an engine  50  ( FIG. 3 ). Two saws  32  may be mounted on the transverse beam  28  to further speed cutting, and/or to more accurately cut a crowned road. 
         [0018]    A control system for the saw may include a servo controlled motor  46  to actuate translation. Saw speed may be controlled to respond to varying degrees of resistance encountered, as for example in response to the oil pressure in the hydraulic motor  46 . Sawing speeds may be increased using the present invention, as the concrete may be less resistant due to the fact that it may be cut before it is entirely hardened. Spalling may be advantageously controlled for the same reason. 
         [0019]    The saw may also have an anti-spalling device  100  used in conjunction with its cutting, which may be mounted with the saw. The depicted anti-spalling device  100  may be a template, or, alternatively a small track assembly  102 . Either may be mounted on the saw assembly  32  or not. 
         [0020]    The entire saw engagement assembly  20 , is movable between an engaged position, such as shown in  FIG. 1 , that places the rotating disk  34  in cutting engagement with the surface of a poured slab, without any other portion of the apparatus touching the slab. The saw engagement assembly  20  also has a retracted position, such as depicted in  FIG. 2 . In the depicted embodiment, retraction is achieved by rotating the moving supported elements  24  around hinges  26  such that the transverse beam  28  and saw assemblies  32  lift away from engagement with the slab. Retraction may be actuated as depicted by a telescoping member  110 . 
         [0021]    In an alternative embodiment, each moveable support arm  24  may be extendable in a longitudinal direction along the direction of travel of the paving machine. By extending one or more support arms  24  varying degrees, the slab may be cut at an angle non-perpendicular to the roadbed, which is required to meet some construction specifications. 
         [0022]    The concrete saw apparatus may incorporate a guidance system, thereby advantageously avoiding the short comings of the chalk line system. These shortcomings include the difficulty in cutting a straight line at the end of each cut as the guide arm extends off the edge of the poured slab. The guidance system may be a guide string wand feeler or a laser non ground contact system. 
         [0023]    The depicted wand guidance system  54  is mounted to the frame  10  and disposed to engage a guide string  58  previously placed to parallel and indicate the direction and proper elevation of the roadway on one or both sides. The wands  56  may extend horizontally to engage the string vertically, top and/or bottom, to guide elevation. The wands  57  may extend vertically to engage the string horizontally, on either or both sides, to guide direction. An alternatively depicted laser guidance system  60  may have receptors mounted on the frame and disposed to receive guiding laser signals from lasers placed in positions in the field preconfigured to guide elevation and direction. 
         [0024]    Guidance systems are available to assist in the sometimes preferred practice of cutting expansion joint slots twice. This includes making a first pass to make a first narrower cut, and returning to that cut later with a second, wider saw blade to widen the cut. This practice controls the spalling characteristics of concrete, which vary over drying time. The retractability of the concrete saw support assembly  20  also facilitates this procedure which is advantageous in some circumstances. 
         [0025]    The saw apparatus as depicted may be further deployed to advantageously execute other steps in the formation of expansion joints. This includes cooling the saw blade, which in the prior art was done by an extra worker hosing down the saw blade with water. In the depicted embodiment, a water reservoir  70  is provided, and a hose(s)  72  is disposed to spray cooling water on the saw blade. The hose  72  may be disposed to travel with the saw along the transverse beam  28 . 
         [0026]    The slot may be cleaned out by air pressure, water flushing or sand blasting, as selected by a user, with the use of the appropriate compressor  80 , nozzle  82 , and reservoir  70 . The nozzle  82  may be disposed to travel along the transverse beam  28 . In the alternative, the slot may be cleaned by vacuuming it out, in which case elements  80  and  82  may represent a vacuum and vacuum nozzle, respectively. The ability to immediately deploy a vacuum after applying cooling water or flushing water advantageously removes the resulting slurry of water and concrete dust, which is considered toxic in some circumstances. 
         [0027]    Finally sealing equipment for injecting caulk, silicon, foam or other sealing material into the slot may be advantageously deployed on the frame, again with a reservoir  90  and injector  92 . The injector  92  may be disposed to travel along the transverse beam  28 . 
         [0028]    In operation, a slab pour operation is set up with a roadbed, guidance system and paver provided. The saw of the present invention follows the paver along and over a poured slab by propelling itself on its tracks and supporting itself by ground contact only, without touching the slab. The saw is advanced to a preconfigured position for an expansion joint slot and the saw support assembly is moved from its retracted position to an engaged position with only the saw blade  34  contacting the surface of the slab. Sawing begins and proceeds to a user selected depth. The saw(s) move across the slab by translating along transverse beam  28 . Supplementary procedures such as cooling the saw with water and flushing the slot may be done. When the slot is completely cut, the saw support assembly is retracted, the entire apparatus travels down the roadway as guided to the next preconfigured position for a slot to be cut and the process repeats. The apparatus may be returned to the slot positions for further supplemental procedures such as making a widening cut, flushing the slot or sealing it. It is within the scope of the present invention that the saw may be used to cut concrete, and also other paving materials. 
         [0029]    As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.