Abstract:
In accordance with the present invention, an improved chop saw is employed. The chop saw includes a base, a rotatable table rotatably disposed on said base, and a saw unit pivotably connected to the table. The saw unit including a blade, a motor for driving the blade, and a housing for covering the motor. The saw unit is movable downwardly towards the table in order to cuttingly engage a workpiece. In addition, the chop saw includes a battery connected to said motor. Preferably, the battery is attached to the housing.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to chop saws and, more particularly, to a cordless chop saw.  
         BACKGROUND OF THE INVENTION  
         [0002]    Chop saws are used in jobsites for cutting wood planks, wood boards, moldings, metal bars, etc. Accordingly, chop saws typically have high power requirements in order to cut the work pieces. Thus, chop saws have been typically been connected to a gas-powered generator or to the jobsite&#39;s electrical wiring.  
           [0003]    There are times, however, when none of these options are available. In such circumstances, users have not been able to use their chop saws until someone brought a gas generator, etc. This would mean delays in construction schedules, etc., which raise labor and building costs, lowering the profit of a contractor or builder. Accordingly, it is an object of the present application to provide a chop saw that resolves the prior art problems.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with the present invention, an improved chop saw is employed. The chop saw includes a base, a rotatable table rotatably disposed on said base, and a saw unit pivotably connected to the table. The saw unit including a blade, a motor for driving the blade, and a housing for covering the motor. The saw unit is movable downwardly towards the table in order to cuttingly engage a workpiece. In addition, the chop saw includes a battery connected to said motor. Preferably, the battery is attached to the housing.  
           [0005]    Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The accompanying drawings illustrate preferred embodiments of the invention according to the practical application of the principles thereof, and in which:  
         [0007]    [0007]FIG. 1 is a front perspective view of an exemplary chop saw according to the present invention;  
         [0008]    [0008]FIG. 2 is a front elevational view of the chop saw of FIG. 1;  
         [0009]    [0009]FIG. 3 is a rear elevational view of the chop saw of FIG. 1;  
         [0010]    [0010]FIG. 4 is a left end elevational view of the chop saw of FIG. 1;  
         [0011]    [0011]FIG. 5 is a rear elevational view of a second embodiment of a chop saw according to the present invention;  
         [0012]    [0012]FIG. 6 is a left end elevational view of the chop saw of FIG. 5;  
         [0013]    [0013]FIG. 7 is a front perspective view of a third embodiment of a chop saw according to the present invention;  
         [0014]    [0014]FIG. 8 is a side elevational view of a pivot bearing for the saw of FIG. 7; and  
         [0015]    [0015]FIG. 9 is a partially sectioned view of a housing for saw assembly without the blade guard and the saw blade.  
     
    
     DETAILED DESCRIPTION  
       [0016]    The invention is now described with reference to the accompanying figures, wherein like numerals designate like parts. FIGS. 1 through 4 illustrate an exemplary chop saw, which can be mitered. One skilled in the art will readily recognize from the following description that the principles of the invention are equally applicable to compound miter saws, sliding miter saws, non-mitering chop saws, etc.  
         [0017]    The exemplary chop saw  10  according to the present invention typically includes a base  12 , including a table  13 , which is preferably rotatable about an axis perpendicular to the top surface plane of table  13 . The saw  10  also includes a saw unit  100  pivotably attached to the table  13 . The saw unit comprises a saw blade  14 , at least partially enclosed by a blade guard  16  and driven by a motor  17 , and a handle  18 , which allows the operator to move the saw blade  14  and the blade guard  16  from a clear position free of a workpiece (not shown) to a downward cutting position with the saw blade  14  in cutting engagement with a workpiece (not shown). The motor  17  is covered by a housing  17   h.    
         [0018]    As shown in FIGS.  1 - 4 , the blade  14  is perpendicular to the plane including the top surface of the table  13 . Persons skilled in the art will recognize that the saw unit  100  can also be pivotably attached to the table  13  so that the angle of the blade  14  relative to the top surface plane, i.e., the bevel angle of the blade  14 , can be changed.  
         [0019]    As is conventional in this type of equipment, a fence assembly, indicated generally by reference numeral  20 , is interconnected with the base  12  and extends laterally across the table  13 , against which the workpiece (not shown) is fixedly positioned and supported for performing a cutting operation thereon. As shown in FIGS.  1 - 4 , the fence assembly  20  includes a fixed fence portion  22  and a movable fence portion  24 , respectively, extending in a mutually aligned lateral direction, with the movable fence portion  24  being laterally spaced away from the fixed fence portion  22 . Such lateral spacing or gap between the fixed and movable fence portions  22  and  24 , respectively provides clearance for the saw blade to perform a cutting operation completely through the workpiece, regardless of the mode or type of cutting operation being performed. Accordingly, a user can laterally move the movable fence portion  24  toward and away from the fixed fence portion  22  in order to selectively adjust the clearance gap therebetween and thus accommodate the particular cutting operation being performed. For further information on the fence assembly  20 , persons skilled in the art are directed to U.S. Pat. No. 5,297,463, assigned to Black &amp; Decker Inc., which is incorporated herein by reference.  
         [0020]    The chop saw  10  also has a battery  200  connected to the motor  17 . The battery  200  may be mounted on housing  17   h,  as shown in FIGS. 3 and 4, preferably in a manner that does not interfere with the chopping action of the saw unit  100 . The battery  200  is preferably a rechargeable nickel cadmium (NiCd), nickel metal hydride (NiMH), lithium, or lead-acid battery. Such batteries can support the high-current, high-power requirements needed for a cordless chop saw. Preferably, such batteries have a voltage rating of at least 14 volts.  
         [0021]    Persons skilled in the art will also recognize that the battery  200  may also be installed on the base  12  of the chop saw  10 , decreasing the weight of the saw unit  100  and facilitating the chopping action. As shown in FIGS. 5 and 6, the battery  200  can be connected to the motor  17  via a cable  201 .  
         [0022]    A third embodiment is shown in FIGS.  7 - 9 . FIG. 7 shows a workpiece support table  1  which may be equipped with adjustable support legs  2 . A round table  3  may be pivotably mounted to the workpiece support table  1  in an appropriately dimensioned opening or recess  4  between a bottom  1   a  of the workpiece support table and a stop ledge  5  extending transversely over the round table. The round table  2  may be provided integrally with a bracket arm  6 , which during the pivoting of the round table  3 , moves within a recess  8  bounded by a pair of mutually oblique lateral walls  7 . The position of the bracket arm  6  may be immobilized by engaging a locking device  9  within suitable notches  10 , whereby the position of the round table  3  is also locked in.  
         [0023]    A support plate  110  may be fixedly connected with the round table  3 . A pivot bearing  120  for a saw assembly  130  may be mounted on the support table  110 , and is capable of executing cross-cut, miter and draw cuts as will be explained. For this purpose, a saw blade  160  (located behind an upper blade guard  140  and a lower blade guard  15 ) is immersed into an insertion slit  170  comprising two mutually aligned portions  170   a  and  170   b.  The portion  170   a  extends approximately from the center of the round table  3  to its periphery, and the portion  170   b  l disposed in the bracket arm  6 .  
         [0024]    A bearing yoke  240  is rotatably supported on the swivel axis  230  and comprises two sleeve-like bearing bodies  25  fro receiving the round rods  26 . The bodies  25  may be mutually parallel and interconnected by means of transverse braces  27  and  28 . The upper round rod  26  may extend through the body  25  and project therefrom to the rear. A tension spring  29  may be hooked into the end of the rod  26 , the other end whereof may be fixedly connected with the bearing block  180  by means of a holding bolt  30 . The spring  29  insures that the round rods  26  and the yoke  24  are always brought into the position indicated in FIG. 7, i.e., rotated counterclockwise about axle  230  in FIG. 8, wherein the rods  26  occupy their upper terminal position. The saw assembly  130 , which moves freely on the rods  26 , is normally held by the force of gravity in a left-hand terminal position wherein the saw housing (to be described below) abuts against the frontal sides  25   a  of the sleeve-like bearing bodies  25 . In the position shown in FIG. 7, the saw assembly  13  is in its right-hand terminal position, in which it must be held by manual actuation with a handle  31 .  
         [0025]    It is seen in FIG. 9 that the saw housing  32 , equipped with the manual handle  31 , may comprise a pair of cylindrically-shaped longitudinal guide passages  33  and  34 , the internal diameter whereof may be coordinated with the outer diameter of the round rods  26  to slidingly receive the latter. End sections of each of the longitudinal passages  33 , 34  may be provided with low friction guide bushings  35 , abutting against the rods  26  and assuring an accurate guidance. The longitudinal passages  33 ,  34  may be long enough to assure that the round rods  26  remain within the passages  33 ,  34  over the entire draw length h. In a manner not shown in detail, the rods  26  may be equipped on their free ends with stops abutting against frontal side  35   a  of the guide bushings  35  and preventing the extraction of the guide rods  26  from the longitudinal passages  33 ,  34 .  
         [0026]    The guide bushings  35  may be each spaced laterally with respect to a bearing bore  36  for the saw blade  160  which is provided in the housing  32  and defines the axis of rotation of the blade. The bushings  35  may extend directly above and below a position of the collector and brush holder components of the drive motor. The motor may be bearingly supported within a housing section  37  laterally projecting from the housing  32 . The motor output shaft may be disposed within a bore  38 . This layout of the longitudinal passages  33 ,  34 , which may also extend directly adjacent to the saw blade  160 , yields an exact guidance of the saw housing  32 . Cutting inaccuracies may be excluded almost entirely.  
         [0027]    When using the saw, the workpiece to be processed is placed against fence  5 . Subsequently the bearing block  21  of the pivot bearing  120  is set so that the saw blade  160  is either perpendicular to the surface of the workpiece support table  1  or at an angle to it. The miter angle may be adjusted by setting the position of the rod table  3  and subsequently processing may be initiated by a lowering of the saw assembly (accompanied by a rotation of the yoke  240  about the axle  230 ) by means of the handle  31 . Following the immersion of the saw blade  160  into the slit  170 , the entire saw assembly  130  may be displaced (to the left of FIG. 7) by means of the handle along the round rods  26 , i.e., along the axis  220 , so that a draw cut is possible. After cutting, the handle  31  is released. The spring  29  lifts the round rods  26  and the saw assembly upwards, into the position shown in FIG. 7. By its own weight, the saw assembly  13  slides into the left-hand position until it abuts against the frontal surfaces  25   a  of the sleeve-like bearing bodies  25 .  
         [0028]    As shown in FIGS. 7 and 9, the saw also has a battery  200  connected to the motor. The battery  200  may be mounted on housing  37 , as shown in FIGS. 7 and 9, preferably in a manner that does not interfere with the chopping action of the saw unit  130 . Persons skilled in the art will recognize, however, that battery  200  may also be mounted on the table  3 , etc. Again, the battery  200  is preferably a rechargeable nicked cadmium (NiCd), nickel metal hydride (NiMH), lithium, or lead-acid battery. Such batteries can support the high-current, high-power requirements needed for a cordless chop saw. Preferably, such batteries have a voltage rating of at least 14 volts.  
         [0029]    Persons skilled in the art may also recognize other alternatives to the means disclosed herein. However, all these additions and/or alterations are considered to be equivalents of the present invention.