Abstract:
An automatic depth of cut control for use with concrete saws. The control allows an operator to set a maximum depth of cut for which the concrete saw can be used at. Further, the control allows the user to move the concrete saw from one location to another without needing to reset the depth of cut.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to depth of cut control for saws, and in particular to depth of cut control for concrete saws.  
           [0003]    2. Background Information  
           [0004]    Concrete saws are used to cut grooves in concrete surfaces so as to control the cracking which inevitably occurs as the concrete cures or hardens. They are used to cut grooves to form a fracture line in the surface of the concrete such that if and when the concrete does crack, it will crack along the cut line. This is done to prevent heaving and irregular surfaces which would inevitably occur otherwise.  
           [0005]    The typical concrete saw is a self-propelled unit which has a main power engine which is used to drive a rotary, diamond-tipped saw blade, and an electrically driven hydraulic system which is used to raise and lower the saw.  
           [0006]    The typical concrete saw has a mainframe and a set of rear drive wheels which are affixed to the mainframe and can be driven at a selectable speed. Attached to the mainframe is a sub frame with a second set of wheels, which is movable, normally by means of an independent hydraulic system to raise and lower the front of the concrete saw and the saw blade. This is done so that the saw blade can be elevated above the surface either for repair or replacement of the blade, or to move the saw from one location to another. The sub frame is then lowered down until the saw blade engages the concrete, and starts to cut into it. The operator can then continue to lower the blade as it cuts into the concrete to a selected depth of cut.  
           [0007]    In selecting the depth of cut, there are a number of variables which include the diameter of the saw blade being used, depth of the concrete, the speed at which the blade is turning, and the drive speed at which the concrete saw is advanced along the line of cut. In general, the thicker the concrete surface the deeper the cut should be, yet the cut should not be so deep as to ensure complete fracturing along the cut line which subjects the concrete surface to inevitable fracture, and the possibility of heaving such as that induced by freezing of the subsurface and inevitable thawing during the change of seasons.  
           [0008]    While devising a method of measuring the depth of cut might seem to be a simple matter, it is not in that depth of cut has to be calibrated for bearing diameters of the saw blades that are used on a concrete saw. And, for the topography, for example whether or not the cut is vertical on an inclined concrete surface such as those encountered on roads, sidewalks and driveways.  
           [0009]    Accordingly, it is the object of this invention to provide a depth of cut apparatus which is adjustable in that it can be easily recalibrated for varying conditions and sizes of saw blades, and also will automatically stop at a preselected depth of cut when the saw is lowered into the concrete surface being cut.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is an apparatus/method for use with concrete saws (or other cutting devices which have elevationally adjustable means for cutting grooves, slots, or trenches in the surface of a material at a selectable depth of cut). The invented apparatus automatically resets the depth of cut after the elevation of the saw or other cutting device has been changed from a selected depth of cut to another depth or elevation. One embodiment of the invented apparatus is utilized with a concrete saw having a rotating saw attached to elevationally adjustable means which is movably attached to a frame. The invented apparatus having a means for determining the elevation of the saw blade, relative to the surface of the material to be cut attached to the elevation means. The invented apparatus further having a means for identifying the elevation of the saw or other cutting device, relative to the surface of the material being cut, when the saw or other cutting device is cutting at a preselected depth of cut. The invented apparatus further having a means for automatically stopping elevational movement of the saw or other cutting device at the elevation of the preselected depth of cut when the elevation of the saw or other cutting device is adjusted to return it to the preselected depth of cut.  
           [0011]    Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description wherein I have shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiment are to be regarded as illustrative in nature, and not as restrictive. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a sectional representational side view of a concrete saw having a first embodiment the automatic depth of cut control, said concrete saw shown in its raised position.  
         [0013]    [0013]FIG. 2 is a sectional representational side view of a concrete saw having a second embodiment of the automatic depth of cut control, said concrete saw shown in its lowered position.  
         [0014]    [0014]FIG. 3 is an exploded representational prospective view of a third embodiment of the automatic depth of cut control.  
         [0015]    [0015]FIG. 4 is a perspective representational bottom view of a fourth embodiment of the automatic depth of cut control as installed on the concrete saw.  
         [0016]    [0016]FIG. 5 is a perspective representational view of a fifth embodiment of the automatic depth of cut control, installed on the concrete saw.  
         [0017]    [0017]FIG. 6 is an exploded representational prospective view of a sixth embodiment of the automatic depth of cut control.  
         [0018]    [0018]FIG. 7 is a partial, perspective view of a seventh embodiment of the automatic depth of cut control of the present invention.  
         [0019]    [0019]FIG. 8 is a partial, end view of an eighth embodiment of the automatic depth of cut control of the present invention.  
         [0020]    [0020]FIG. 9 is a side, environmental view of a ninth embodiment of the automatic depth of cut control of the present invention.  
         [0021]    [0021]FIG. 10 is a side, environmental view of a tenth embodiment of the automatic depth of cut control of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.  
         [0023]    Referring first to FIG. 1, there is shown a representational sectional side view of a concrete saw  10  in an elevated position. FIG. 2 is a representational sectional side view of a concrete saw  10  in a lowered position. Referring again to FIG. 1, at the base of the concrete saw is mainframe  12  and sub frame  18 . Sub frame  18  is attached to sub frame shaft  82  which is attached to mainframe  12 , and is driven by means of hydraulic cylinder  24  which is attached to pivot arm  84  which is used to raise and lower the front half of the concrete saw  12  so as to adjust the height of the saw blade  34  to either elevate it for purposes of moving the concrete saw  10 , replacing saw blade  34 , or controlling the depth of cut of saw blade  34  in concrete surface  86 . It is also envisioned that the invented apparatus/method may be used with other versions of cutting devices, including those having the cutting means mounted on a pivoting arm, wherein the cutting means attached to the pivoting arm is the portion of the device which is raised and lowered. While this disclosure stresses the mainframe/sub frame style of cutting device, all other types of devices are also included.  
         [0024]    Saw blade  34  is attached to a conventional arbor, and is driven by engine  14  housed within engine shroud  16  by means of engine drive pulley  36  and a plurality of drive belts  38 . The operator of the concrete saw  10  stands behind the unit, and guides the concrete saw  10  by means of a pair of handles  32 , and controls the saw with a variety of controls conveniently positioned for the operator on control panel  56 , and which include, engine throttle  60  and saw blade clutch control  58 .  
         [0025]    Hydraulic cylinder  24  is, in a typical concrete saw  10 , controlled by means of an electrically driven hydraulic unit  26  which includes an electric motor, a hydraulic pump and an accumulator. Power is supplied to hydraulic unit  26  by means of a generator or alternator attached to engine  14  and/or battery  30 . The purpose of the independent electrically powered hydraulic unit  26  is to enable the operator to elevate the concrete saw  10  without engine  14  running. This is a standard feature which enables the operator to replace the saw blade  34  without the possibility of the saw engine  14  being inadvertently turned on. Other, nonhydraulic cylinder manners of actuation are included in this disclosure, including, but not limited to all types of linear and rotary actuation.  
         [0026]    A drive transmission  28  is used, in a conventional manner, to drive wheels  20  at a selected speed. The concrete saw  10  is supported at all times by four wheels, the first being the rear pair of drive wheels  20  and the second set being sub frame wheels  22 .  
         [0027]    In order to have automatic depth of cut control, it is necessary to have some sort of sensing mechanism which can be used to identify the elevation of the saw relative to the concrete surface  86 . There are a variety of ways of accomplishing this, which include sensing units which sense the extension of hydraulic cylinder  24 , electronic sensors which can sense the angle at which mainframe  12  is positioned, ultrasonic sensors, proximity sensors, mechanical sensors, and in the preferred embodiment, a cable arrangement. In the preferred embodiment, cable  40  is attached to cable anchor point  42  on sub frame  18 . Cable  42  is then spooled around idler pulleys  44  and  46 , and then around spool  62  on the depth of cut indicator wheel  52  and attached to spring  48 , which itself is anchored to mainframe  12  as shown in FIGS. 3 and 4. In this manner, as the front end of the concrete saw  10  is lowered down toward the concrete surface  86 , the distance between anchor point  42  and idler pulley  44  becomes shorter, causing spring  48  to take up the slack, thus translating the elevation of the saw into rotational movement of depth of cut indicator wheel  52 .  
         [0028]    In the preferred embodiment, spring  48  is sized and tensioned so as to allow the operator to override the frictional forces between cable  40  and spool  62  to so as to calibrate the zero point for depth of cut indicator wheel  52  to compensate for varying diameters and sizes of saw blades  34 . This is accomplished by lowering concrete saw  10  until concrete saw blade  34  just touches concrete surface  86  and then manually turning depth of cut indicator wheel  52  to the zero position.  
         [0029]    Now referring to FIG. 3 there is shown an exploded representational perspective view of one embodiment of the automatic depth of cut control system. It includes depth of cut indicator wheel  52  and depth of cut selector wheel  54  which interfits over depth of cut selector spool shaft  70  which is formed integral with depth of cut indicator wheel  52 , O-ring  68  is provided to provide significant frictional engagement between depth of cut selector wheel  54  and depth of cut indicator wheel  52  so that depth of cut selector wheel  54  will automatically rotate in conjunction with depth of cut indicator wheel  52  when it is rotated by means of movement of cable  40  which is in frictional engagement with spool  62  (as shown in FIG. 7), yet at the same time, not to have frictional engagement to the extent that it is possible to manually rotate either depth of cut indicator wheel  52  or depth of cut selector wheel  54  independent of each other.  
         [0030]    Referring now to FIGS. 9 and 10, the assembled automatic depth control wheels ( 52 ,  54 ) are rotatably attached to shaft  66  by means of washer  76  and bolt  74  which itself is supported by means of support plate  88  and bracket  64 . Support plate  88  and bracket  64  are preferably attached to frame components of concrete saw  10  in a conventional manner, as shown in FIG. 4. In this embodiment, the automatic depth control assembly is attached in a fixed relationship to the mainframe.  
         [0031]    As shown in FIGS. 3 and 6, a micro switch  78  is located at top dead center on support plate  88  and is in engagement with front surface  90  of depth of cut selector wheel  54 . A slot  80  is formed in depth of cut selector wheel  54  and configured for engagement with micro switch  78 . FIG. 8 further shows the switch  78  and the slot  80 . Micro switch  78 , as long as it is pressed against the surface  90  of depth of cut selector wheel  54  is in the closed position, which enables the operator to operate the hydraulic system to lower sub frame  18 . Micro switch  78  is wired into the circuit so as to be overridden for purposes of elevating concrete saw  10  irregardless of whether or not micro switch  78  is open or closed. When depth of cut selector wheel  54  rotates to a position wherein micro switch  78  drops into slot  80 , micro switch  78  switches from a closed position to an open position thereby disabling the hydraulic system in such a manner as to preclude any further lowering of the elevation of concrete saw  10 .  
         [0032]    In use, the operator first calibrates the depth of cut indicator wheel  52  by lowering concrete saw  10  to an elevation wherein saw blade  34  just touches concrete surface  86  and then manually overrides the frictional force of cable  40  by turning depth of cut indicator wheel  52  to the zero position. When the elevation of concrete saw  10  is further lowered in the preferred embodiment, depth of cut indicator wheel  52  will be rotated in the direction of arrow  92  and depth of cut selector wheel will rotate the same direction. The operator can, after calibration of depth of cut indicator wheel  52  then rotate depth of cut selector wheel  54  in the direction of arrow  94  to select a depth. When depth of cut selector wheel  94  is rotated, slot  80  will be disengaged from micro switch  78  and will be pressed against surface  90  to a closed position. Then, as the concrete saw  10  is further lowered into a cut, depth of cut selector wheel  54  will rotate with depth of cut selector wheel  52  in the direction of arrow  92  and the concrete saw will continually be elevationally lowered into the cut until again slot  80  comes into alignment with micro switch  78  to disable further lowering.  
         [0033]    The use of two wheels, the depth of cut indicator wheel  52  and the depth of cut selector wheel  54  has been selected as the preferred embodiment, primarily because of the harsh environment in which the saw is used. When sawing concrete, there is a lot of abrasive concrete dust and sometimes water droplets from the water spraying cooling system for the saw blade  34  are generated. As a result, this mechanical system is the preferred embodiment. However, it should be apparent to those skilled in the art that the same results can be achieved electronically using rather simple and basic electronic circuits to both sense the elevation of concrete saw  10  and to store electronically a selected depth of cut. While at the time that this application is filed, the applicant has not yet developed an electronic embodiment for the present invention, it should be apparent to those skilled in the art that the same can easily be done.  
         [0034]    While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims.