Abstract:
A drywall-cutting tool comprises a rotary blade of a thin design that cuts a very small kerf resulting in a smooth cut as well as a small amount of dust. Any dust that is generated is immediately vacuumed away by an on-board vacuum system that collects the dust in a removable dust bag. Additionally, the saw is provided with an adjustable depth mechanism for the most common thicknesses of drywall. This feature allows for accurate cuts, especially in remodeling scenarios where drywall must be cut without damaging other building components behind the drywall.

Description:
RELATED APPLICATIONS 
     The present invention was first described in and claims the benefit of U.S. Provisional Patent Application No. 61/617,116 filed on Mar. 29, 2012, the entire disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a drywall-cutting tool to minimize the amount of airborne dust by directing and trapping it in a collection bag attached to the device. 
     BACKGROUND OF THE INVENTION 
     Drywall is perhaps the most common interior wall surface used in the world today. It is easy to work with, low-cost, and looks great when finished. During new work, drywall is easily cut with a straight blade knife prior to installation in a quick and relatively dust-free manner. However, there are many instances where new drywall must be cut around obstacles or existing drywall must be cut during remodeling operations. This is most typically done with a jigsaw or saws-all, which gets the work done, but results in a rough cut and a high amount of dust. Additionally, the blades of such tools extend beyond the rear surface of the drywall where they can contact the building structure, wiring, or plumbing with disastrous results. Accordingly, there exists a need for a means by which drywall can be easily cut without the disadvantages as described above. The development of the present invention fulfills this need. 
     Prior art in this field consists of dust abatement means that render the cutting device unwieldy. Furthermore, prior art dust abatement means either consists of a specific configuration of a dust passage to generate a vortex or an elaborate vacuum system with ducts and hoods. Only elaborate vacuum systems provide an adequate filtration system to collect small particulate matter, whereas other dust collection means are not so efficient in doing so. It is an object of this invention to provide a cutting tool to make finer and more accurate cuts by way of employing thinner cutting apparatuses and an adjustment depth means. Finer cuts result in finer particulates, which require enhanced filtration and collection systems. It is a further object of this invention to provide an effective means of collecting and trapping finer particulates. It is a further object of this invention to have a cutting device that employs both a vortex generating dust collection configuration and a forced air dust collection apparatus. The employment of these methods should not compromise the compactness and portability of the device. 
     SUMMARY OF THE INVENTION 
     The device comprises a housing having a working end, a handle, an electric motor, electrical supply source, a drive conversion system, an adjustable depth guide, an auxiliary handle, and a dust collection system. The housing contains the various electrical and mechanical components of the device. Extending from the housing is a handle, which contains the electrical supply source for the electrical components. The housing is further provided with an aperture to receive an auxiliary handle to assist a user in obtaining leverage when employing the device. The handle is further provided with a control switch that is in electro-mechanical connection with the various components of the device. The drive conversion system comprises a gearing and shaft assembly in electro-mechanical connection with the electric motor to convert electrical energy to rotary motion and transmit torque to a working end of the device. This torque is employed to impart a rotary force onto a removably and interchangeable circular blade of the device. The device is also equipped with a guard positioned to substantially envelope the circular blade. An area defined as a space between the circular blade and the guard forms a dust passage. 
     The dust collection system comprises a fan mounted onto the guard, and is positioned to be directed into the dust passage. This fan generates forced air to drive dust through the dust passage and into an outlet port of the guard. The guard is further provided with a downwardly extending lip located on an inside surface, and is situated just below the outlet port. This lip serves to obviate dust particles from escaping the dust passage. The dust collection system further comprises a dust collection bag. This bag is removably connected to an outside surface of the outlet port. The bag is semi-permeable to allow air to permeate but to trap particulate matter. The guard is equipped with an adjustable depth guide for adjusting the depth of the exposed portion of the circular blade that protrudes beyond the guard. A retaining mechanism locks the depth guide at a selectable depth position. The dust collection bag is connected to an outside surface of the outlet port. If desired, the auxiliary handle is removably attached to the housing. 
     The device is specifically designed to cut drywall. The rotary blade is of a very thin design that cuts a very small kerf. The saw is provided with an adjustable depth mechanism that is pre-set for the most common thicknesses of drywall. These features allow for accurate cuts, especially in remodeling scenarios where drywall must be cut without damaging other building components behind the drywall. This results in not only a smooth cut, but a very small amount of dust as well. However, any dust that is generated is immediately vacuumed away by an on-board vacuum system that collects the dust in a removable dust bag. The cutting edge of the circular blade is engaged with a surface of the material to be cut. As cutting is performed, particulate matter is expelled creating dust. This dust is directed into the dust passage and through the outlet port, which is then directed into the dust collection bag. The use of this device provides the ability to cut drywall in a manner which is not only quick, easy, and effective, but safe and dust-free as well. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings in which like elements are identified with like symbols and in which: 
         FIG. 1  is a perspective view of a drywall-cutting tool with dust collector  10  in accordance with the preferred embodiment of present invention; 
         FIG. 2  is a section view along line A-A as seen in  FIG. 1  of a working end  21  of the drywall-cutting tool with dust collector  10  in accordance with the preferred embodiment of the present invention; 
         FIG. 3  is a side view of the drywall-cutting tool with dust collector  10  depicted with a special feature  27  in an up position in accordance with the preferred embodiment of the present invention; 
         FIG. 4  is a section view along a line B-B as shown on  FIG. 3  cut through the dust collection bag  50  of the drywall-cutting tool with dust collector  10  in accordance with the preferred embodiment of the present invention; and, 
         FIG. 5  is a schematic showing the motor  70 , drive conversion means  75 , spindle  36 , and fan  40  in accordance with the preferred embodiment of the present invention. 
     
    
    
     DESCRIPTIVE KEY 
     
         
         
           
               10  drywall-cutting tool with dust collector 
               20  housing 
               21  working end 
               22  handle portion 
               23  battery attachment end 
               24  handle aperture 
               31  saw blade 
               32  battery 
               33  switch actuator 
               34  guard cover 
               35  dust passage 
               36  spindle 
               37  outlet port 
               38  lip 
               39  intake opening 
               40  fan 
               41  fan housing 
               43  depth guide 
               44  retaining mechanism 
               50  dust collection bag 
               51  neck 
               52  neck clip 
               54  bag liner 
               56  zipper 
               65  auxiliary handle 
               70  motor 
               75  drive conversion means 
           
         
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within  FIGS. 1 through 4 . However, the invention is not limited to the described embodiment, and a person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention, and that any such work around will also fall under scope of this invention. It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention, and only one particular configuration shall be shown and described for purposes of clarity and disclosure and not by way of limitation of scope. 
     The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. 
     The present invention describes a drywall-cutting tool with dust collector (herein referred to as the “apparatus”)  10 , which provides a means to cut drywall from an existing installation while minimizing the amount of airborne dust from that process by trapping the discarded particles, both gross and fine, in a vacuum collection system contained within the working end  21  and containing said particles in an attached dust collection bag  50 . 
     Referring now to  FIG. 1 , a perspective view of the apparatus  10  according to embodiment of the present invention, is disclosed. The apparatus  10  generally housing  20  having a working end  21 , a central handle portion  22 , and a battery end  23 . The working end  21  includes any of the necessary gears, shafts, and bearings rotary motion of a motor  70  into a drive conversion means  75 , such as angle drive necessary for the rotation of a spindle  36  and a fan  40 , as well as a saw blade guards and adjustments, and the dust collection system. The drive conversion means  75  may be comprised of a worm and spur gears or a bevel gear set without limiting the invention. A thin, circular, multi-toothed saw blade  31  is mounted on the spindle  36  about a central axis defined by the spindle  36 . 
     A semi-circular guard cover  34  having sidewalls and a flat lower edge is attached to a side of the working end  21  of the housing  20  for at least partially covering an upper portion of the saw blade  31 . The area defined between the sides of the saw blade  31  and sidewalls of the guard cover  34  forms a dust passage  35  for collecting and directing particles of material in the direction of the rotation of the saw blade  31 . A centrifugal fan  40  is disposed in the sidewall of the working end  21  within the fan housing  41  disposed upon the guard cover  34  for creating a forced flow of air directed toward an outlet port  37  of the guard cover  34 . The fan  40  is driven by the motor  70  through the drive conversion means  75  which also comprises an internal transmission assembly. The transmission assembly can be belt-driven or gear-driven mechanisms without limiting the scope of the invention. 
     The central handle portion  22  houses a portion or all of an internal electric motor  70  which is operationally connected to the spindle  36 . The motor  70  is comprised of any of a variety of commercially available, copper wound, low voltage, small frame, direct current motors with a cylindrical output shaft capable of generating sufficient torque to induce the desired motion in the spindle  36 . 
     A battery  32  is connected to the battery attachment end  23  for providing electrical power to the motor  70 . The battery  32  is preferably a removable and rechargeable battery pack providing approximately between 12-VDC and 18-VDC power. A momentary-on switch (not shown) is mounted within the handle portion  22  of the apparatus  10  and completes the electrically connection between the battery  32  and the motor  70  by the depression of a spring biased switch actuator  33 . 
     The apparatus  10  also includes a detachable auxiliary handle  65 . The auxiliary handle  65 , attached in a preferably threaded handle aperture  24 , is disposed in the working end  21  of the housing  20 . The location of the auxiliary handle  65  can vary depending upon the preferred handing of the user without limiting the scope of the invention. 
     Referring now to  FIG. 2 , a cross-section of the apparatus  10 , according to the preferred embodiment of the present invention, is disclosed. The fan  40  is disposed within the guard cover  34  aligned between the dust passage  35  and the outlet port  37 . A downwardly extending lip  38  is disposed on an inside surface of the guard cover  34  below the outlet port  37  for preventing material particles from escaping from the guard cover  34 . 
     The guard cover  34  also includes an adjustable depth guide  43  for adjusting the depth of the cut. The depth guide  43  is a generally rectangular member having sidewalls, a flat bottom surface, and a central opening for the saw blade  31  to pass through. The depth guide  43  is mounted over the lower edge of the guard cover  34  and can be secured in at least two (2) different positions. A retaining mechanism  44  locks the depth guide  43  at one (1) of the selectable depth positions. The depth guide  43  is adjustable between making one-half inch (½ in.) cuts and five-eighths inch (⅝ in.) cuts. However, it can be appreciated that the depth guide  43  and retaining mechanism  44  can be adapted to be locked into various incremental cutting depths and as such should not be viewed as a limiting factor. The retaining mechanism  44  is preferably comprised of a pair of slide clamps for engaging contact surfaces of the guard cover  34  and the depth guide  43 . However, it can be appreciated that the retaining mechanism  44  can be any suitable locking mechanism such as a spring detent pin that engages one (1) of a plurality of detent apertures, a threaded tightening mechanism, or the like. 
     Referring to  FIG. 3 , a side view of the apparatus  10 , according to the preferred embodiment of the present invention, is disclosed. A dust-collection bag  50  is connectable to the exterior of the outlet port  37 . The dust collection bag  50  acts as an air filter and is preferably comprised of a fabric bag having a liner  54  with a fine weave that allows air to pass through but prevents particulate matter from passing. The dust collection bag  50  is further provided with a narrow neck  51  into which a protruding end of the outlet port  37  is inserted, and a zipper  56  which will close off an opening through which the dust may be emptied. A neck clip  52  secures the dust collection bag  50  to the outlet port  37 . 
       FIG. 5  is a schematic showing the motor  70 . The motor  70  is operably connected to the drive conversion means  75 . The drive conversion means  75  drives the spindle  36  (and attached saw blade  31 ) and the fan  40 . 
     The preferred embodiment of the present invention can be utilized by the enabled user in a simple and straightforward manner with little or no training. The method of utilizing the apparatus  10  can be achieved by performing a series of steps. It can be appreciated that the operational steps can be performed in alternative order and as such any operational description of use should not be viewed as a limiting factor. 
     During operation of the apparatus  10 , the depth guide  43  is locked into a selected and desired depth to correspond to the thickness of the drywall to be cut and the depth of the cut. The depth guide  43  is locked into position by use of the retaining mechanism  44 . The battery  32  can be charged by use of an external existing battery charger that electrically connects to an AC power source. Once charged, the battery  32  is connected to the apparatus  10  at the battery attachment end  23  of the housing  20 . The dust collection bag  50  is connected to the outlet port  37  at the neck  51 . If needed, the auxiliary handle  65  can be attached to working end  21  of the housing  20  to give the user a secondary grip during use. 
     The cutting edge of the saw blade  31  engages the surface of the material to be cut perpendicular to the rotational axis of the blade  31 . As the saw blade  31  rotates, the cutting surface cuts or grinds a thin, smooth kerf in the drywall. The dust and particles created by the cutting edge of the blade  31  are directed into the dust passage  35  through the intake opening  39  of the guard cover  34 . As the fan  40  rotates, a stream of air is drawn from the air intake opening  39  of the dust passage positioned at a front end of the lower edge of the guard cover  34 . The dust and material particles created by the saw blade  31  are directed toward the intake opening  39  where a partial vacuum is created by the pressure drop behind the fan  40 . The particles in the airflow are directed through the outlet port  37  and through the neck  51  of the dust collection bag. When the airflow encounters the much larger cross-sectional area of the dust collection bag  50 , the velocity of the air rapidly decreases and the dust is deposited in said dust collection bag  50 . 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention and method of use to the precise forms disclosed. Obviously many modifications and variations are possible in light of the above teaching. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, and to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions or substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but is intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.