Patent Publication Number: US-8528141-B2

Title: Dressing device for power brush

Description:
FIELD OF THE INVENTION 
     The present invention relates to a brush. More particularly this invention concerns a brush which is rotatably driven. 
     BACKGROUND OF THE INVENTION 
     A standard power brush had an arbor that extends along an axis and that is rotated at high speed about the axis. A brush has a sleeve fitted to the arbor and a multiplicity of bristles that extend radially outward from the arbor. 
     In use the brush is rotated at high speed while outer ends or tips of the bristles are pressed against a workpiece so as to strip paint, descale, deflash, roughen, or otherwise surface treat the workpiece. The bristles can be made of natural or synthetic fibers, or of metal. 
     With time the outer ends of the bristles often bulk up or become quite blunt, in particular when working hard materials such as metal castings or stripping paint. There is frequently a buildup on the rear sides of the bristles, that is the sides facing rearward in the peripheral rotation direction. This thickening and buildup reduces the effectiveness of the power brush by imparting a blunt shape to the bristles with an outer end providing little abrasive or scraping action. Once such a brush gets clogged in this manner, it is normally so difficult to clean it that it is simply discarded and replaced. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved power brush. 
     Another object is the provision of such an improved power brush that overcomes the above-given disadvantages, in particular whose effectiveness can be restored. 
     SUMMARY OF THE INVENTION 
     A power-brush apparatus has according to the invention a housing, a brush rotatable on the housing about a brush axis and having bristles extending generally radially of the axis, and a drive that rotates the brush in a working direction about the axis and thereby orbits tips of the bristles about the axis. Thus when in use the brush is rotated in this working direction. In accordance with the invention a support immediately adjacent the housing carries a rigid grinding wheel having an abrasive outer surface. This wheel is biased radially against the bristle tips to sharpen and clean them while a drive relatively displaces the bristle tips and the grinding-wheel surface while the wheel is urged against the bristle tips such that the grinding wheel surface primarily engages rear sides of the bristle tips turned away from the working direction. 
     Furthermore according to the invention the drive rotates the grinding wheel about a wheel axis in a rotation direction opposite the brush direction while the brush is rotating in the brush direction about the brush axis and displaces the outer surface of the wheel at a peripheral speed greater than a peripheral speed of the bristle tips. Alternately according to the invention, the stone can be stationary and the brush can be reverse rotated to grind the back sides of the bristle tips. 
     The stone axis according to the invention is substantially parallel to the brush axis. In addition the drive can rotate the stone about the stone axis in either of two opposite directions. Similarly the brush drive can rotate the brush about the brush axis in either of two directions, so that one way or another the back sides of the bristle tips are passed over the surface of the grinding stone. 
     The support according to the invention is mounted on the brush housing. Furthermore the support includes a base carried on the brush housing and an pivot interconnecting the base and the support for relative pivoting about a support axis. The support is provided with a handle projecting generally radially of the support axis. 
     A spring can be provided between the support and the base to press the stone radially against the brush. This ensures a constant pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
         FIG. 1  is a side view of the power brush according to the invention; 
         FIG. 2  is a top view of a detail of  FIG. 1 ; and 
         FIG. 3  is a schematic end view illustrating operation of the instant invention. 
     
    
    
     SPECIFIC DESCRIPTION 
     As seen in  FIG. 1  a power brush  1  according to the invention has a housing  14  on which is mounted a wire brush wheel  3 . More particularly the brush  3  has a central sleeve  4  fitted snugly over a cylindrical arbor  2  rotatable about and centered on an axis  2 A. Bristles  5  extend radially from the sleeve  4 , and an electric or pneumatic motor  13  in the housing  14  normally rotates the arbor  2  and brush  3  about the axis  2 A in the working direction D. The bristles  5  are normally pressed against a workpiece (not illustrated here) to remove corrosion, scale, flashing, or the like from its surfaces or to roughen it. 
     In accordance with the invention a cylindrical grinding wheel or stone  6  also shown in  FIG. 2  is mounted on an arm  7  for rotation about an axis  6 A by a motor  11 . The arm  7  can in turn be pivoted on a shaft  9  having an axis  9 A parallel to the axes  6 A and  2 A by a handle  10  to press the cylindrical outer surface of the stone  6  against forwardly tipped outer ends or tip  12  ( FIG. 3 ) of the bristles  5 . The arm  7  is carried on a support  8  here shown to be fixed to the housing  14  of the power brush  1 . A torque spring shown partially schematically at  15  between the arm  7  and base  8  urges the stone  6  radially against the brush  3  with a predetermined constant force. 
     The wheel  6  here is a standard composition ceramic grinding stone formed as a cylindrical plinth. It could be some other rigid structure, for instance a drum with an abrasive surface, e.g. a sandpaper sleeve. 
     In the illustrated embodiment the drive motor  11  rotates the grinding stone  6  about the axis  6 A in a stone direction D′ opposite to the working direction D but at such a speed that the peripheral speed of the stone  6  is greater than that of the brush  3  so as to back sharpen the forwardly inclined bristle tips  12 . This urges or bends these tips  12  somewhat forward  12  so that they are most effective in material removal. The stone  6  can be swung in and rotated for periodic sharpening, or can be left in place to continuously dress the bristles  5 . 
     This restoration of the sharpened outer ends to the bristles  5  can be done periodically. Alternately, the drive motor  11  can run whenever the brush  3  is in use, with the stone  6  engaging the tips  12 , so that the brush  3  is continuously refreshed and always has a like-new abrasiveness. In such a system the motor  11  can be dispensed with and replaced with some sort of transmission, e.g. a belt drive, that connects to the main drive motor  13  that rotates the brush  3 . 
     The motor  11  is reversible so that, in a system where the peripheral speed of the stone  6  is equal to zero or less than that of the brush  3 , the brush  3  can be reverse rotated to stroke the back sides of the tips  12  over the stone  6 .