Abstract:
An abrasive saw having an associated cutting wheel is used for cutting objects. The saw includes a base, a cutting assembly operably mounted to the base and a controller. The cutting assembly includes a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel. A flexible drive element operably connects the drive shaft and a drive wheel. The distance between the drive wheel axis of rotation and the drive shaft axis of rotation is variable to increase or decrease a tension in the flexible drive element. A feed table is operably mounted to the base and is movable forward and rearward in a direction of rotation of the associated cutting wheel. The cutting wheel is lockable in the cutting position and the feed table, with the object secured thereto, is moved, by the controller toward the associated cutting wheel to cut the object. An enclosure encloses the cutting assembly and has stationary sides and openable front and top panels hingedly mounted to one another and to a portion of one of the side panels to open as a unitary assembly for access to the cutting assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION DATA 
       [0001]    This application is national phase of PCT/US2010/029619 filed Apr. 1, 2010, and claims the benefit of priority of Provisional U.S. Patent Application Ser. No. 61/174,560, filed May 1, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an abrasive saw. More particularly, the present invention relates to an improved abrasive saw having novel blade and sample drive systems, improved working area/sample access, wear components, and sensor and control features. 
         [0003]    Abrasive saws are used in various industries, but in particular are used in the rough or gross preparation of samples/specimens for examination. For example, specimens such as metals or aggregates (concrete) are often microscopically examined to determine grain structure, composition, failures and the like. 
         [0004]    In preparing samples, the samples typically must be cut, polished and mounted for examination. The first part of that preparation process, the cutting, is carried out using a saw. Often, the saw is of the abrasive type (that is, it uses an abrasive wheel in lieu of a toothed blade) and is carried out in a wet process to lubricate, cool and flush the sample and abrasive wheel. 
         [0005]    Known saws uses a wheel that is mounted to a pivoting arm that is pulled or urged downward into the sample to perform the cut. The sample is fixedly mounted and secured to a plate or bed of the saw. Among other things, this can result in too great of a force being exerted on the sample (and the blade) which can overheat the sample and blade. This can also result in excessive stress on the saw motor. 
         [0006]    In known saws, if serial samples are required to be cut from the same specimen, the specimen must be unsecured (unclamped) from the bed, moved to a proper location beneath the saw blade, and resecured (reclamped) to the bed to carry out the next serial or sequential cut. 
         [0007]    In addition, such known saws are often belt driven, but do not have ready means for adjusting the belt to assure proper tension for blade drive. 
         [0008]    Accordingly, there is a need for an improved abrasive saw. Such a saw has novel wheel and samples drive systems to improve the mobility of the specimen on the saw bed and to assure good and smooth contact between the abrasive wheel and the sample. Desirably, such a saw also has improved working area/sample access, wear components, and sensor and control features. 
       SUMMARY OF THE INVENTION 
       [0009]    An abrasive saw has a cutting wheel for cutting objects mounted thereto, The saw includes a base, a cutting assembly operably mounted to the base and a controller. The cutting assembly includes a pivot shaft, a drive shaft operably mounted to the pivot shaft, a drive, and a drive wheel. The drive is operably connected to the drive shaft and the drive shaft is operably connected to the drive wheel by a flexible drive element or belt to rotate the drive wheel. The drive wheel has the cutting wheel mounted thereto. The pivot shaft is pivotable to move the cutting wheel between a cutting position and a disengaged position. 
         [0010]    The drive shaft has an axis of rotation and the drive wheel has an axis of rotation spaced a distance from the drive shaft axis of rotation. The flexible drive element spans the distance between the drive wheel axis of rotation and the drive shaft axis of rotation. The distance between the drive wheel axis of rotation and the drive shaft axis of rotation is variable to increase or decrease a tension in the drive belt. 
         [0011]    In a present saw, the drive shaft is disposed within the pivot shaft and rotation of the pivot shaft varies the distance between the drive wheel axis of rotation and the drive shaft axis of rotation. The pivot shaft has a longitudinal axis and the distance between the pivot shaft longitudinal axis and the drive wheel axis of rotation is fixed. The drive shaft is eccentrically disposed within the pivot shaft. Varying the distance between the drive wheel axis of rotation and the drive shaft axis of rotation varies the tension in the belt. 
         [0012]    In a present embodiment, the saw includes a feed table operably mounted to the base. A drive is operably connected to the feed table. The feed table is movable forward and rearward in a direction of rotation of the associated cutting wheel to move the object toward and away from the cutting wheel. The cutting wheel is lockable in the cutting position and the feed table, with the object secured thereto, is moved, manually or by operation of the controller, toward the cutting wheel to cut the object. 
         [0013]    The saw includes a current sensor circuit that generates a signal to the controller and, upon sensing a predetermined current, the controller slows and/or stops the drive to slow and/or stop movement of the table toward the associated cutting wheel. The controller includes an input for inputting the speed of the table moving toward the associated cutting wheel. 
         [0014]    The saw also includes a transverse drive to move the feed table transverse to the direction of rotation of the associated cutting wheel for serially cutting objects. The transverse drive is manually operated. 
         [0015]    The saw includes an enclosure enclosing the cutting assembly. A present enclosure has a fully stationary side and an openable front and top panel. A portion of one of the side panels is movable and is operably connected to the front and top panels. The front and top panels are hingedly mounted to one another to open as a unitary assembly along with the portion of the side panel. The assembly is openable to provide access to the cutting assembly. 
         [0016]    The enclosure includes at least one wear element disposed on the inside of the enclosure, aligned with the direction of rotation of the associated cutting wheel, to prevent erosion of the enclosure. 
         [0017]    One or more interlocks prevent operation of the abrasive saw when the enclosure is open. A fluid feed is provided to feed fluid to a shroud covering the cutting wheel. 
         [0018]    These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]    The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
           [0020]      FIG. 1  is a perspective front view of the improved abrasive saw embodying the present invention, the saw shown with the viewing hood removed for clarity of illustration; 
           [0021]      FIG. 2  is a side view of the saw with a portion of the cover removed to show the drive system; 
           [0022]      FIG. 3  is a perspective view of the saw wheel arm and drive components; 
           [0023]      FIG. 4  is side view of the saw wheel arm showing the eccentric relationship between the drive shaft, pivot shaft and final drive wheel; 
           [0024]      FIG. 5A  is an enlarged front view of the saw, showing the saw wheel arm in the engaged or cutting position; 
           [0025]      FIG. 5B  is a view similar to that if  FIG. 5A  with arm in the disengaged position; 
           [0026]      FIG. 6  is a view looking into the drive region and showing the actuating handle and linkage for moving the saw wheel arm between the engaged and disengaged positions; 
           [0027]      FIG. 7  is an enlarged view of the arm lock assembly; 
           [0028]      FIG. 8  is a view looking transverse along the front of the saw illustrating the feed drive system; 
           [0029]      FIG. 9  is a view looking into the saw front and showing the screw drive assembly for the table; 
           [0030]      FIG. 10  is a perspective view of the viewing/protective hood in the open position; 
           [0031]      FIG. 11  in an exploded view showing the pivot shaft, drive shaft and pivot arm linkage; 
           [0032]      FIG. 12  is an exploded view of the X-drive; 
           [0033]      FIGS. 13A-D  show an electrical line drawing for the saw; 
           [0034]      FIG. 14  is a wiring diagram for the saw showing the current sensor; and 
           [0035]      FIG. 14A  is an enlarged view of a part of  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
         [0037]    It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
         [0038]    Referring now to the figures and in particular, to  FIG. 1 , there is shown an improved abrasive saw  10  embodying the principles of the present invention. In this illustration, the saw is shown with the hood and abrasive wheel removed for clarity of illustration. The saw  10  includes, generally, a base  12 , a cutting region  14  with an abrasive wheel arm assembly  16  and a feed bed  18 , a drive region  20  and a control panel  22 . 
         [0039]    The drive region  20  is shown in  FIG. 2 . A wheel drive motor  24  (cutting wheel motor) is connected to a drive shaft  26  that is mounted within a pivot arm assembly  28 . A pair of toothed wheels  30 ,  32  (one on the motor  24  and the other on the shaft  26 ) and a toothed drive belt  34  permit the transfer of power from the motor  24  to the drive shaft  26 . A drive wheel  36  (also toothed) is mounted to the opposite end of the drive shaft  26 . 
         [0040]    Referring also to  FIGS. 2-4  and  6 , the drive shaft  26  is mounted within a pivot shaft  38 . The pivot shaft  38  is held within a set of bearings  40  to allow the shaft  38  to pivot (rotate) to move the saw wheel W between the disengaged and engaged (cutting) positions. A linkage  42  is used to move (pivot) the shaft  38 . An L-shaped arm  44  is mounted at about the heel  46  to pivot. A handle  48  is mounted to one leg  50  of the L-arm  44  and a link bar  52  is mounted to the other leg  54 . A lock or brake system  56  is mounted between the saw frame or base  12  and the handle leg  50  of the L-arm  44 . The brake  56  is used to lock the linkage  42  into any position once the brake  56  is engaged. 
         [0041]    Mounted to the opposite end of the link bar  52  is a pivot shaft clamp  58 . The pivot shaft clamp  58  is secured to the pivot shaft  38  and provides the motive force and leverage to pivot the shaft  38  (as the handle  48  is pulled or pushed to engage or disengage the abrasive wheel W, respectively). 
         [0042]    As seen in  FIGS. 6 and 7 , the lock or brake system  56  includes a split sleeve  60  that is biased (as by a spring  62 ) inward onto a shaft  64 . One end of the shaft  64  is mounted to the L-arm  44  and the other end is mounted in the split sleeve  60 . The sleeve  60  is operably mounted to the saw frame or base  12  as indicated at  66 . The lock  56  is configured so that when the sleeve  60  is urged opened, the shaft  64  slides or reciprocates within the sleeve  60  and when the sleeve  60  closes, the shaft  64  is secured in the sleeve  60  and prevented from reciprocating (moving). A trigger or grip  68  on the handle  48  is operably connected to the lock  56  to engage and disengage the lock  56 . 
         [0043]    Referring to  FIGS. 2-5 , as seen in the cutting region  14 , the drive wheel  36  is mounted to the end of the drive shaft  26 . A saw wheel arm  70  is mounted to the end of the pivot shaft  38 . A final drive toothed drive wheel  72  is mounted to an opposite end of the saw wheel arm  70  and a wheel drive belt  74  is positioned around the two drive wheels  36 ,  72  to transfer power from the drive shaft  26  to the final drive wheel  72 . The abrasive wheel W (not shown) is mounted to the final drive wheel  72 .  FIGS. 5A and 5B  show the wheel shroud or cover  76  in place on the saw wheel arm  70 . A water nozzle  78  is shown on the shroud  76  to provide a water feed to the wheel W during the cutting operation. A water pump and motor (not shown) supply water to the water nozzle  78 . 
         [0044]    The present saw  10  includes a novel arrangement for providing the proper tension in the wheel drive belt  74 . As can be seen in  FIGS. 3-4  and  11  (as indicated at  80  in  FIG. 4 ) the drive shaft  26  is eccentrically set within the pivot shaft  38 . In this arrangement, the distance d 74  from the center of the drive shaft C 26  (the position of the center of the drive shaft  26  remains fixed) to periphery of the pivot shaft P 38  varies depending upon where the eccentricity lies relative to the center C 26  of the drive shaft  26 . In effect, the eccentrically mounted shafts  26 ,  38  serve as a cam surface to increase or decrease the distance d 74  between the center of the drive shaft C 26  and the center of the final drive wheel C 72 . This variation or change in distance serves to permit adjusting the tension in the wheel drive belt  74 . 
         [0045]    The present saw  10  also includes a novel bed  18  and feed system  82  as seen in FIGS.  1  and  8 - 9 . It will be appreciated that the bed  18  is used to support specimens as they are cut. In a typical saw configuration, the bed is fixed and the saw is brought down (pivoted) into the specimen to carry out the cut. In the present saw  10 , in an auto-feed mode of operation (discussed in more detail below), the abrasive wheel W is locked in a cutting position, and the feed system  82  moves the bed  18  with the specimen mounted thereto into the wheel W. 
         [0046]    The bed  18  is set on a set of bearings  84  to move toward and away from the wheel W, or into and out of the cutting zone. A screw drive  86  provides the motive force to move the bed  18 . This is referred to as a Y-drive (the y-direction of feeding into the wheel W). A worm gear (or screw)  88  is mounted to the saw frame  12  and a receiver gearbox  90  is mounted to the bed  18 . To permit manual movement or adjustment of the bed  18  position, a hand crank  92  is mounted to the saw base  12  and is operably connected to the worm gear  88 . As will be discussed below, the saw  10  includes a motor and drive assembly  94  (wheels/gears  96  and belts  98 ) for operation in the auto-feed mode. 
         [0047]    The saw  10  also includes a transverse or X-drive  100  as seen in  FIGS. 9 and 12  that moves the bed  18  (and the specimen) transverse to the direction of cutting (as indicated by the arrow at  102 ). The X-drive assembly  100  includes a shaft  104  (that extends from the front of the saw  10 ) having a bevel gear  106  mounted to an end thereof. A second bevel gear  108  transfers power to a worm gear  110  to which a gear box  112  (on the bed  18 ) is meshed. A hand crank  114  on the front  115  of the saw  10  is used to drive or move the bed  18  in the transverse (X) direction. In this manner, sections of specimens can be serially or sequentially cut from a single sample. This eliminates the need to clamp a sample, cut the specimen, unclamp, move and re-clamp the sample, and cut the next specimen. This can be quite time consuming and labor intensive if a number of specimens are needed. The present X-drive  100  permits carrying out multiple cuts from a single clamping of the sample and also permits better and more precise control of the size of the specimen that is cut. 
         [0048]    As seen in  FIGS. 1 ,  5 A and  9 , the present saw  10  includes one or more wear strips  116  mounted to the saw case  117 . The wear strips  116  are mounted in alignment with the cutting (saw) wheel W to prevent debris that is generated and ejected from the wheel W during the cutting operation from impinging on the case or housing  117 . The wear strips  116  are replaceable and in this manner the wear strip  116  serves as a sacrificial element to prevent excessive damage to or wear of the case  117 . In the present saw  10 , the wear strip  116  extends up the rear of the case  117  and along the bottom, where debris impingement would be most severe. 
         [0049]    The viewing/protective hood  118  is shown in  FIG. 10 . The hood  118  includes a front  120  wall having a viewing window  122  and a top wall  124 . The front and top walls  120 ,  124  are hinged  126  to one another. One or more cylinders  128  extend between the hood  118  and the case  117  and are used to assist lifting and lowering, and to dampen movement of the hood  118 . 
         [0050]    The hood  118  includes guide rollers  130   a,b  on the front wall  120  that engage tracks  132   a,b  in the front/side of the case  118 . One of the rollers  130   a  (on the left-hand side) also engages a track  134  along the top of the case  117 . The tracks  132   a,b  and  134  have a T-slot (not shown) formed in them to capture their respective rollers  130   a,b . The rollers  130   a,b  are thus maintained or captured in the front/side tracks  132  to allow the front wall  120  and the top  124  to be rotated up and rearward. A recess  136  in the track  134  is positioned so that the roller guide  130   a  can reside in the recess  136  to maintain the hood  118  open for access to the cutting region  14 . An interlock system  138  (key  140  and receiver  142 ) isolates power to the saw  10  when the key  140  is removed from the receiver  142 , that is, when the hood  118  is open. A portion  152  of the left side panel is configured to slide forward and rearward (as indicated by the arrow at  154 ) along with the movement of the hood  118 . Roller  130   b , which resides in track  132   b , is, at it reaches the top of the track  132   b , captured in a receiver  156  in the panel portion  152 . As the front wall  120  is moved rearward, the roller  130   b , captured in the receiver  156 , moves the panel portion  152  rearward to provide increased access to the cutting region  14 . When the hood  118  is closed, the roller  130   b  (in the receiver  156 ) moves the panel portion  152  forward to close the panel portion  152 . 
         [0051]    The saw  10  includes a control system  144  having a touch-pad control panel  22 . The control system  144  is microprocessor based and includes a standard (e.g., USB) slot (as at  146 ) so that new/modified control schemes can be readily installed in the system  144 . The touch-pad control panel  22  is configured so that only icons that are needed for any particular mode of operation are displayed. It will be appreciated that any number of different types of control systems  144 , panels  22 , and the like can be used. 
         [0052]    Those skilled in the art will recognize the need to monitor the power that is drawn by the saw  10  (specifically, the wheel motor  24 ) as one indication of the strain on the motor  24 . The present saw  10  includes a powerless or self-powered sensor  148  for monitoring the current drawn by the motor  24 . The sensor  148  includes a circuit  150  to convert the current drawn (e.g., 0 to 15 A) to a corresponding voltage (e.g. 0-10V) and provides indication of the current. The current drawn by the wheel drive motor  24  is an indicator of whether the wheel W is being too quickly brought into contact with the specimen. 
         [0053]    In auto-feed mode, the feed rate of the specimen is programmed into the controller,  144 , as is the length or distance of the cut. In a preferred embodiment, then the sensor  148  senses that the current drawn by the motor  24  is greater than a predetermined level, the table motor  94  is slowed or stopped to prevent damage to the motor  94  or wheel W. 
         [0054]    As set forth above, the saw  10  can be operated in manual mode. The specimen is clamped to the bed  18  and the specimen position is adjusted (using the hand cranks to adjust the X and Y directions). Similar to known saws, the wheel W is manually brought down into contact with the specimen by pulling the handle  48  downward. Moving (pivoting) the handle  48  upward disengages the wheel W from the specimen. The hood  118  can then be opened and the specimen removed. 
         [0055]    In an auto-feed mode, the specimen is clamped to the bed  18  with the bed in a home position, and the wheel W is pulled downward so that the periphery of the wheel extends below the bed  18  top surface. The lock or brake  56  to maintain the wheel W in this (cutting) position. The saw  10  is set in auto-feed mode by setting the feed rate of the specimen on the control panel  22 . The brake  56  prevents the wheel W from “jumping” upward when the specimen contacts the wheel W. The bed  18  then moves from the home position toward the wheel W to feed the specimen into the wheel W. If during cutting the current drawn by the motor  24  is too high, the bed  18  can slow and/or stop (by automatic/controlled operation of the motor and drive assembly  94 ) to protect the abrasive wheel W and/or motor  24 . When the cut is complete, the bed  18  automatically returns to the home position. If the specimen is to be cut serially, the X-drive  100  can be actuated and the specimen repositioned (transversely). The auto-feed sequence can then be reinitiated to perform the next sequential cut. 
         [0056]    All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
         [0057]    In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
         [0058]    From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover all such modifications as fall within the scope of the invention.