Abstract:
An accessory for a power hand tool including a rolling support structure for supporting and carrying the hand tool over a substrate at a user-selected or preselected working depth or height of the disc grinder or sander or similar material processor is disclosed. The accessory includes a support bracket having a longitudinal axis for attachment to a portion of the housing at an intermediate position of the support bracket, together with a pair of substrate-surface engaging rollers adjustably secured to the support bracket at mounting locations longitudinally separated from the intermediate attachment position. For a power hand tool having a housing including a cylindrical outer surface portion coaxially aligned with the drive shaft of the power tool, the attachment portion of the accessory includes a corresponding concavity for being installed about the cylindrical portion of the housing in nesting relationship with a clearance fit therebetween to allow for angular adjustment therebetween.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     not applicable 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hand tools, and more particularly, to an accessory for supporting and thereby enhancing the use and performance of hand tools during material processing of a substrate. 
     2. Description of the Related Art 
     Hand tools, especially power-assisted hand tools are well known and widely used in the construction, retrofitting or repair of solid surfaces and articles, such as by the selective removal of material in order to produce a desired contour, relief, conformation or shape as by grinding or sanding. For example, a builder may selectively grind a groove into a concrete surface to form a thermal relief, or sand some wood from a beam in order to produce a neat fit, or grind or sand away a contour to smooth or reconfigure a surface or edge. The procedure of such selective removal, particularly if carried out by abrasive means, involves the expenditure of considerable physical effort, as the required grinder or sander itself may have considerable weight, is typically awkward and clumsy to work with, without benefit of a stabilizing platform or guide not common to such hand tools, and contrary to the need for compactness and portability. Over the course of performing what is typically a physically arduous task in oftentimes challenging work environments, there is an increased possibility of reduced accuracy and consistency in providing the grinding/sanding operation because of the lack of a stabilizing or guiding platform. 
     More specifically, hand-held tools and especially power tools such as disc grinders employ grinding wheels and cut-off wheels with grinding surfaces or sharpened cutting edges or teeth for grinding, sanding, or cutting all manner of stone, masonry, wood and other material that may be provided in block, sheet, slab or other forms. For example, disc grinders may be used to cut slotted or grooved reliefs at predetermined intervals in solid surfaces such as concrete to serve as stress reliefs during curing and thereafter when the concrete may expand and contract in response to thermal loads provided internally during curing and externally in response to environmental factors. Slots and grooves may be cut through the thickness of the concrete slab to serve as expansion/contraction joints. Alternatively, the slab may be provided with grooves to a subsurface depth, but not the complete depth of the slab for several purposes. One purpose is to serve as scoring lines for separation or demolition purposes. Another purpose is to serve as localized centers for cracking and crazing within the slot so provided, thereby minimizing or preventing the appearance of thermal cracking/crazing at the surface of the slab. Such hand tools may also be used for shaping and cutting other hard and durable material in sheet, slab or other forms, both natural and artificial, including granite, marble, stone and wood, as well as artificially formed materials including slab or sheet stock of solid surfacing materials commonly used for applications including but not limited to foundations, flooring, counter tops, and roofing. Due to the nature of these applications, conventional portable, hand-held power tools are necessarily built with a strong and durable construction, and are hence heavy and cumbersome, requiring significant strength, agility and endurance by the technician or operator for continuing use especially on extended or elaborate projects. 
     An important problem in the related art, as noted above, is that the technician must continuously balance the tool while guiding it during the material processing operation for essentially the entirety of the cut, so that the grinding wheel remains in substantially the same orientation while in contact with the underlying substrate to achieve the desired cut. The nature of this work again requires considerable strength, endurance and precision, and even a slight loss of any of these attributes by the technician or operator typically results in waste and spoilage of the stock material being cut, in addition to the lost labor and commensurate losses in production time and output. This problem is especially acute in the concrete cutting industry, where the substrate being worked is often large cast-in-place slabs for which inaccurate scored relief lines and grooves can materially and negatively affect subsequent construction requirements, and wherein the cutting saws may be of commercial grade with a commensurately greater weight than those saws provided on the consumer retail level. A related problem is maintaining an accurate cut when guiding the power tool over a surface featuring undulations or other features that challenges the technician or operator in maintaining a perfect cut through the substrate. 
     Accordingly, there exists a need for an apparatus that enhances the use and performance of portable power tools used in all manner of performing cuts, slots and grooves, and overcomes the substantial shortcomings of the prior art, while maintaining portability and compactness of the portable power tool. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an apparatus for supporting and stabilizing a portable power tool saw to improve operating precision. 
     It is another object of the present invention to provide an improvement for supporting a portable power tool that may easily and conveniently be retrofitted to conventional portable power tools such as power disc grinders, sanders, and other hand-held power tools for which improved and consistent handling characteristics are desirable. 
     It is a further object of the present invention to provide an improvement for supporting a portable power tool that is easily and readily affixed and removed by the professional and amateur alike, and once properly installed with the cutting saw, provides consistent cutting results irrespective of a user&#39;s strength or endurance. 
     It is yet another object of the present invention to provide a support accessory for a power hand tool that is operably affixed to and supported by the hand tool in a manner that negligibly effects its portability and compactness. 
     It is a further object of the present invention to provide a power hand tool constructed with the present invention. 
     According to the present invention, an accessory for a power hand tool overcomes the shortcomings of the related art by providing a rolling support structure that enhances ease of handling and operation of the power hand tool for supporting and carrying the hand tool over a substrate at a user-selected or preselected working depth or height of the disc grinder or sander or similar material processor. The accessory includes a support bracket having a longitudinal axis, for attachment to a portion of the housing at an intermediate to position of the support bracket, and a pair of low-friction surface engaging devices such as rollers secured to the support bracket at mounting locations longitudinally separated from the intermediate attachment position. As is common to many power hand tools, the tool housing includes a cylindrical housing portion through which the drive shaft extends for supporting the disc grinding wheel or sanding wheel. The inventive apparatus thus includes a corresponding concavity for being installed about the cylindrical portion of the housing in nesting relationship with a clearance fit or sliding fit therebetween to allow for angular adjustment therebetween. 
     A curvilinear fastener slot is provided in the support bracket parallel to and radially outwardly spaced from the concavity of the support bracket, and is used to secure the support bracket to the housing at a desired position, when the power tool is adjusted to the desired angular position and vertical height relative to the substrate to be processed, by a fastener securing the support bracket to the housing. Additionally, the rollers are carried on axles supported by the support bracket, and axle mounting slots are provided in the support bracket, each slot being at an angle offset from the longitudinal axis for selectively adjusting the vertical processing position of the material processing disc relative to a substrate when the accessory is mounted to the housing. 
     A power hand tool constructed with the invention is further disclosed. The tool is driven by an internal (e.g. electric) or external (e.g. compressed air) power source, the tool having a housing supporting a drive shaft driven by the power source, a material processing disc such as a grinding wheel or sanding wheel supported by the drive shaft for operation about a rotational axis, and a support bracket having a longitudinal axis supported by the housing at an intermediate position of the support bracket, with a pair of surface engaging rollers secured to the support bracket at mounting locations longitudinally separated from the intermediate attachment position. 
     According to the invention, the support bracket may be removably secured to the tool, or integrally formed therewith. Furthermore, for a power hand tool having a cylindrical bearing surface incorporated in its housing, the support bracket includes a corresponding concavity having an axis of rotation for being installed in nesting relationship with the bearing surface. The invention further exploits the type and location of fasteners securing the housings of some power hand tools, whereby the support bracket is secured to the tool by a fastener common to the tool adjacent the housing portion through which the drive shaft projects, further allowing for adjustment of the support bracket in an arcuate manner to a selected position and then securing the bracket by the common fastener. Alternatively, for a power hand tool having a face through which the drive shaft extends, and a drive shaft retaining bracket offset therefrom, a portion of the support bracket is received and supported therebetween in the installed condition. 
     The rollers used with the support bracket are carried on axles extending from the support bracket, the axles being positionally adjustable in axle mounting slots provided in the support bracket, each slot provided at an angle offset from the longitudinal axis for selectively adjusting the vertical processing to position of the material processing disc relative to a substrate. According to one embodiment of the invention, the offset angle is perpendicular to the longitudinal axis, although other mounting slots with alternate configurations may be provided. Furthermore, to provide additional stability during use of the power hand tool, a pair of rollers may be supported on at least one of the shafts (or even both, if desired), wherein the shaft extends to opposite sides of the support bracket for supporting the rollers in opposing relationship and providing a relatively wide support base. 
     It should be noted and understood that with respect to the embodiments of the present invention disclosed herein, the materials and apparatus disclosed and suggested may be modified or substituted to achieve the desired protected structures without departing from the scope and spirit of the disclosed and claimed invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a power hand tool to which the support accessory of the present invention is installed, showing the disc grinding wheel of the tool being selectively applied to a substrate to form a groove at a user-selected depth. 
     FIG. 2 is an exploded view of the support accessory of the present invention to be mounted to a power tool. 
     FIG. 3 is a partial front elevational view of the support accessory of the present invention shown in FIG.  1 . 
     FIG. 4 is a side elevational view of the support accessory shown in FIG. 3, showing the positional adjustability of the inventive apparatus relative to the power hand tool to which it is mounted. 
     FIG. 5 is a perspective view of the support accessory of the present invention, further showing an alignment gauge for use therewith. 
     FIG. 6 is a partial perspective view of an additional feature of the present invention, showing a pair of rollers supported on an axle extending from one end of the support bracket to provide additional stability during operation of the power hand tool. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein like numerals designate like and corresponding parts throughout the several views, FIGS. 1-3 show the support accessory  10  of the present invention mounted to a portable power hand tool  11  such as a power disc grinder or sander or other power hand tool having a housing  12  configured to contain an internal power drive such as an electric motor energized by an electrical source connected to power conduit  13  or alternatively by a transmission for accommodating an external compressed air supply provided through power conduit  13  as is commonly known. The power drive provides a power output to a drive shaft  14  after the tool  11  is activated by switch  15 , the tool being configured to securely support, engage and drive via rotary motion a material processing disc  16  such as a grinding wheel, sanding wheel, cutoff wheel, flap wheel or other surface processing or conditioning disc for engaging and processing a substrate  17 . It will be appreciated that the disc  16  may include a peripheral cutting or processing edge  18 , or alternatively, a material processing surface provided on the exposed lateral face  20  of the disc  16 . 
     The housing  12  includes a housing extension  22  through which the drive shaft  14  extends, the housing extension  22  further including a bearing face  24  fronting a standoff portion  25  having a cylindrical periphery  27  through which the drive shaft  14  further extends to receive and support the disc  16 . Drive shaft  14  includes a base portion  26  projecting from the housing extension  22  and a threaded distal portion  28  for receiving bracketing securing nuts  30 ,  32  and thereby securing the disc  16  therebetween. According to one mode of operation, typically a grinding or cutting mode, an edge guard  33  may be secured to the housing  12  to encompass a circumferential aspect of the arc of rotation of the disc  16  opposite from the circumferential working aspect of the disc  16 . Alternatively, the edge guard  33  may be removed to enable direct application of the exposed lateral face  20  of the disc  16 . 
     Referring specifically now to FIG. 2, and according to the invention, support accessory  10  includes a support bracket  40  having a longitudinal axis  42  extending along its substantially rectilinear extent defined by two end portions  44 ,  46  bridged by a center web portion  48 . A shaped concavity  50  is provided in the center web portion  48  extending through one lateral edge  52 . Shaped concavity  50  is configured to conform with cylindrical periphery  27  of the power hand tool  11  in the manner to be more fully described below. A pair of arcuately shaped fastener slots  54 ,  56  are also provided in the support bracket  40  for securing it to the housing extension  22  by fasteners  58 ,  60  projected therethrough to engage in threaded recesses  62  also provided in the housing extension  22 . Fasteners  58 ,  60  may be provided with the tool  11  for fastening portions of the housing extension  22  to housing  12 , and these fasteners  58 ,  60  are used in common to secure the support bracket  40  to the tool  11  according to the invention, although it will be apparent to the skilled artisan that additional fasteners not included in the basic construction of the tool  11  may be optionally provided or substituted to serve the function of securing the support bracket  40  to the tool  11  according to the invention. Fastener slots  54 ,  56  share a common radius relative to the axial center of shaped concavity  50 , and may optionally be fabricated as a unitary slot (not shown) by removal of the separating structure. Support bracket  40  may be constructed of a strong, rigid material such as a stainless steel or aluminum alloy or other suitable material that can suitably absorb the shock, vibration and other loads commonly endured during reasonable use of the designated power hand tool. 
     Each of the two end portions  44 ,  46  include slots  64 ,  66 , respectively, through which is secured a shaft bolt  68  having a roller bearing surface  70  for supporting a substrate surface engaging roller  72 . The shaft bolt  68  includes a distal threaded portion  74  for receiving a retaining nut  76  thereby allowing for securing each roller  72  to a selected lateral side of support bracket  40 . Slots  64 ,  66  are provided in the support bracket  40  at an angle offset from the longitudinal axis  42  for selectively adjusting the vertical processing position of the material processing disc  16  relative to the relative to the substrate  17  in the installed position. According to the invention, and as shown in FIG. 2, the offset angle is perpendicular to the longitudinal axis  42 , although slots  64 ,  66  provided at other angles and configurations relative to the longitudinal axis  42  may be provided such as by forming or stamping in the support bracket  40 . By way of example only, slots  64 ,  66  may have an extended or articulated configuration so as to provided an element of adjustability of a roller  72  in the direction of the longitudinal axis  42 , while concurrently providing an element of adjustability transverse thereto. 
     With particular reference now to FIGS. 3 and 4, the inventive support accessory  10  is shown mounted for operation to the power hand tool  11 , further showing the adjustability of the accessory  10  to articulate the tool  11  and disc  16  to a selected operational angle and height relative to the substrate  17 . More specifically, support bracket  40  is fitted to the tool  11  by sliding the support bracket between the disc  16  and bearing face  24  while engaging the standoff portion  25  in the concavity  50  with a sliding or clearance fit between the cylindrical periphery or bearing surface  27  and the support bracket  40 . In the installed, nested position, the concavity  50  and cylindrical periphery  27  have a common an axis of rotation, and are angularly adjusted in the direction of arrow A (FIG. 4) to achieve the desired handling angle of the power hand tool  11 . The desired position is then secured by assembling and tightening fasteners  58 ,  60  in threaded recesses  62 . 
     Vertical adjustment of the assembly is achieved by raising or lowering each or both rollers  72  in slots  64 ,  66  in the direction of arrow B (FIG. 4) to achieve a selected processing depth for the disc  16 , thereby also achieving another objective of the invention, i.e., providing means for maintaining a consistent processing depth relative to a substrate, even one with undulating and inconsistent contours. Thus, angular orientation of the tool  11  relative to the longitudinal axis  42  may be achieved either by angular adjustment of the tool  11  within the concavity  50 , and/or by separate height adjustment of the rollers  72  in the manner described. Furthermore, it will be clear that although a generally cylindrical periphery  27  is shown, it will be apparent to the skilled artisan that an actual bearing relationship between the periphery  27  and concavity need not be maintained to achieve the objectives of the present invention. Indeed, it is contemplated that one or both surfaces may be proved with a plurality of spaced teeth to further engage and secure a desired angular orientation of the tool  11  relative to the longitudinal axis  42  and hence support bracket  40 . 
     According to the invention, the support accessory  10  may be provided either as an accessory to a power hand tool that may be easily and readily assembled or disassembled thereto, or alternatively provided as a feature of and manufactured with a power hand tool. More particularly, the power hand tool  11  may be driven by a power source having a housing  12  supporting a drive shaft  14  driven by an internal or external power source, a material processing disc  16  supported by the drive shaft  14  for operation about a rotational axis, a support bracket  40  being supported for articulation by the housing  12  at a position of the support bracket  40 , and a pair of surface engaging rollers  72  secured to the support bracket  40  at mounting position separated from the intermediate attachment position. 
     Referring to FIGS. 5 and 6, additional features of the present invention are disclosed. As shown in FIG. 5, an alignment/sight gage such as an extendable ruler  80  supported by an L-bracket  82  is supported by installed fastener  74  and nut is  76  at forward end portion  44  of support bracket  40  to provide measuring guidance of the disc  16  relative to a reference line or contour  84  to the power tool operator. It will be apparent to the skilled artisan that other alignment and measuring tools may be secured to the support bracket  40  as necessary and desired to assist the operator in achieving positional and depth consistency during operation of the tool. As shown in FIG. 6, to provide additional stability during use of the power hand tool  11 , a pair of rollers  72  may be supported on an extended roller supporting axle  86  to substitute for one or both shaft bolts  68  adjustably secured to slots  64 ,  66  and adjustable in the same manner previously described, the rollers  72  supported on opposite sides of the support bracket  40  to provide at least a tripod support structure to support the assembly of the tool  11  and accessory  10  in an upright position, as well as to provide a relatively wide support base for the assembly during operation and storage. In addition, and with reference to FIG. 1, a cooling water sprayer  90  for providing a directable cooling water spray  92  toward the work piece and disc  16  may be affixed to the tool  11  by a clamp  94  at the appropriate position and height. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.