Patent Publication Number: US-6220948-B1

Title: Adjustable sanding device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to sanding and abrading devices. More particularly, it relates to an improved attachment for a sander which allow for adjustably sanding and abrading contoured surfaces. 
     STATEMENT OF THE PRIOR ART 
     Various types of sanders and abrading devices have been devised which allow for sanding and abrading contoured surfaces. These types of device are especially useful in the automotive body repair industry, as recent card designs have featured highly contoured, aerodynamic body designs. The majority of these devices are either manual devices or are designed to work with specialized actuators. 
     U.S. Pat. No. 5,700,187 issued to Balbi discloses a tool for sanding contoured surfaces having means for adjustably controlling the shape of the base to which the sanding material is applied. The adjustment means is relatively rigid and has a fairly complex mechanism, including a pair of screw adjusted journals which may be selectively raised, lowered, or spaced to adjust the curvature of the supporting base. The present invention, by contrast, recognizes that it is virtually impossible to exactly match the contour of any shaped surface. To that end, the present invention uses a plurality of interchangeable springs to adjust the flexible supporting base. The springs can be selectively applied to approximate the shape of the surface to be sanded or abraded. The springs allow the supporting base to conform to the shape of the contoured surface. 
     U.S. Pat. No. 5,387,251 issued to Rouse discloses another sanding device. The device is an endless belt sanding device which has a triangular frame to which sanding belts may be releasably attached. By contrast, the present invention contemplates a sanding device having a spring loaded support block to which individual sanding sheets may be releasably attached. 
     U.S. Pat. No. 4,823,515 issued to Blome discloses an adjustable sanding device having a flexible membrane serving as a support surface for an abrasive medium. Opposing edges of the membrane are supported by spaced plates which are selectively positioned to adjust the curvature of the membrane. The present invention contemplates a support for an abrasive medium which has both a flexible membrane and a spring loaded adjustment means allowing the membrane to more fully conform to the contours of the object being sanded or abraded. 
     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages of the prior art by providing an attachment for an oscillatory sanding or abrading device which has a pair of flexible support members for supporting the sanding or abrading material. The initial radius of curvature of the flexible support member may be adjusted by a spring loaded adjustment mechanism. An opposing pair of circular recesses formed in opposing faces of the flexible sheets allows for replacement of the springs. The recesses can be formed at both ends of the flexible sheets. Adjustment of the initial radius of curvature is accomplished by inserting springs of varying sizes into one or both pairs of recesses. The radius of curvature of the flexible support member during the sanding process is then a function of the spring constant of the spring used and the applied pressure. The device thus uses a series of discrete adjustments each of which covers a range of contoured shapes. 
     Accordingly, it is a principal object of the invention to provide a new and improved attachment for sanding and abrading devices which allows for sanding and abrading contoured surfaces. 
     It is an object of the invention to provide a new and improved attachment for sanding and abrading devices which has a layered flexible support member for supporting the sanding or abrading material. 
     It is an object of the invention to provide a new and improved attachment for sanding and abrading devices which has a spring loaded support mechanism for adjusting for the contour of the surface to be sanded. 
     It is an object of the invention to provide a new and improved attachment for sanding and abrading devices having interchangeable springs of varying heights for adjusting the radius of curvature of the sanding material. 
     It is an object of the invention to provide a new and improved attachment for sanding and abrading devices having springs of varying spring constants for adjusting the flexibility of the support mechanism for the sanding and abrading material. 
     It is an object of the invention to provide a new and improved attachment for sanding and abrading devices having a plurality of discrete adjustments each of which allow for sanding a range of contoured surfaces. 
     Finally, it is a general object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes. 
    
    
     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
     FIG. 1 shows a side view of an attachment for automatic sanding and abrading tools attached to a sander. 
     FIG.  2 . shows a perspective view of the attachment, partly in section. 
     FIG.  3 . shows a side view of the attachment in one of several discrete positions attached to a sander. 
     FIGS. 4 a - 4   d  show several different positions of the attachment illustrating the changes in the radius of curvature of the sanding material. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1-4, a sanding and abrading machine attachment formed in accordance with a first embodiment of the present invention, generally indicated by the numeral  10 , is shown. The attachment  10  is adapted for use with a handheld pneumatic or other self powered sander  12  having a flat bed (not shown) which is moved in a longitudinal or orbital path at a relatively high speed. These sanders  12  typically have a single flat bed with means for selectively releasing/securing strips of sanding material to be applied to a workpiece. Sanding contoured surfaces is typically done with some difficulty even by professionals, the results obtained thereby are mot always satisfactory and even in the event they are, much time is consumed in the process. To that end, the attachment  10  of the present invention is provided to facilitate sanding of contoured surfaces with superior results while minimizing the time spent by the worker. 
     The attachment  10  includes a lower portion and an upper portion, the upper portion comprising a flexible layered base  14  with the attachment  10  being used in place of the flat bed. Screws  16  disposed at opposing ends of the base  14  allow for connecting the attachment  10  to the sander  12 . The aluminum sheet  18  is secured to the sander mechanism in place of the flat bed. The aluminum sheet  18  has corresponding threaded apertures  20  formed therein for receiving the screws  16  which extend into threaded apertures  21  in the sander  12 . An adhesive rubber pad  22  secured to the aluminum sheet  18  has at least one recess  23  formed therein for removably receiving at least one spring  26  as will be explained in more detail later. 
     The lower portion of the attachment contains the sanding or abrading material  24  which is preferably attached using an adhesive. Preferably the sanding material  24  has an adhesive backing. A support layer  27  for the sanding material  24  may be made of a relatively hard but flexible plastic material that can be easily curved into a desired shape by springs  26 . The support layer  27  has at least one recess  28  aligned axially with and opposing recess  23 , the recess  28  sized for removably receiving the opposite end of spring  26 . 
     The adjustment of the curvature is brought about by adjusting the thickness or height of the springs  26 . A series of springs  26  sized to fit within recesses  23 ,  28  allow for a plurality of discrete curvatures. One sided curvature as shown in FIG.  4 ( d ) is accomplished by inserting spring  26  into recesses  23 ,  28  on only one side of the layers  14 ,  27 . Two sided curvature is effected by inserting springs  26  into recesses on both sides of the layers as is shown in FIG.  4 ( c ). The structure is designed for easy replacement of the springs  26  which may be contracted for removal and replacement. During replacement the user must take care to ensure that the spring  26  is positioned entirely within the recesses  23 ,  28 . 
     In operation, the existing oscillating bed of the sander  12  is replaced with the attachment  10  of the invention. Once the approximate contour of curvature of the surface to be sanded is determined, the curvature of support layer  27  is adjusted to match using springs  26 . The springs may be removed by pulling on the support layer  27  until the spring is easy to move. Care must be taken to avoid using too much force when pulling on support layer  27  to avoid damaging the support layer. Once the appropriate curvature is attained the sander  12  may then be used in the usual manner. The spring constant or stiffness of the springs  26  allow for the curvature of the support layer  27 , and therefore the sanding or abrading material  24  to conform to the contour of the working surface while the sander  12  is applied to the working surface with downward pressure. Unlike prior art adjustable sanders which use rigid mechanisms set to a predetermined curvature, the present invention contemplates a structure which allow first for approximation of the contour to be sanded, then the application of pressure can be used to more fully approximate the contour of the surface to be sanded, such approximations to be made within a predetermined discrete setting. If it is desired to limit the flexure of the support layer  27 , springs  26  having a higher spring constant may be used. Conversely, when sanding a surface having many undulations it may be desired to have a greater flexure. This is accommodated by employing springs  26  having a lower spring constant. Once the worker is familiar with the characteristics of the support layer under a wide variety of operating conditions, substitution of the appropriate springs  26  to meet various conditions is easily accomplished. 
     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. 
     It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: