Patent Publication Number: US-6986704-B1

Title: Sand belt-tensioning device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority of Taiwanese Application No. 093212220, filed on Aug. 2, 2004. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a tensioning device, and more particularly to a sand belt-tensioning device that includes a drive roller and a resilient member for tautening a sand belt on the drive roller. 
   2. Description of the Related Art 
   Referring to  FIG. 1 , a conventional grinding device is shown to include a drive roller  1  and a sand belt  2  wound around the drive roller  1 . The drive roller  1  has a roller body  11 , and two opposite end surfaces that are formed respectively and integrally with two aligned rotating shafts  12 . Two fixing members  13  are sleeved respectively and fixedly on the first and second rotating shafts  12 , abut respectively against the end surfaces of the drive roller  1 , and are connected respectively and fixedly to two opposite ends of the sand belt  2 . 
   Referring to  FIG. 2 , during use of the conventional grinding device, the roller  1  is rotated, and a wooden workpiece  3  is pressed against a bottom side of the roller  1 . The wooden workpiece  3  is also moved in a horizontal direction in such a manner that frictional contact therebetween is maintained. Therefore, a top surface of the wooden workpiece  3  is finished. During movement of the wooden workpiece  3  under the grinding device, a portion  23  of the sand belt  2  is pushed by the wooden workpiece  3  to move away from an outer surface of the roller  1 . This results in unsmooth movement of the wooden workpiece  3  and a dissatisfactory grinding effect. 
   SUMMARY OF THE INVENTION 
   The object of this invention is to provide a sand belt-tensioning device that includes a drive roller and a resilient member for tautening a sand belt on the drive roller. 
   According to this invention, a sand belt-tensioning device includes a drive roller, a fixing member, a pulling member, and a resilient member. A sand belt is wound around a roller body of the drive roller. The drive roller has opposite first and second end surfaces that are formed respectively with axially extending first and second rotating shafts. The fixing member is sleeved fixedly on the first rotating shaft, and is connected fixedly to an end of the sand belt. The pulling member is sleeved rotatably on the second rotating shaft, and is connected fixedly to the other end of the sand belt at an eccentric position. The resilient member biases the pulling member to rotate about the second rotating shaft in a direction so as to tauten the sand belt on the drive roller. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a conventional grinding device; 
       FIG. 2  is a cross sectional view of the conventional grinding device, illustrating how a wooden workpiece is finished; 
       FIG. 3  is an exploded perspective view of the preferred embodiment of a sand belt-tensioning device according to this invention; 
       FIG. 4  is an assembled perspective view of the preferred embodiment; and 
       FIG. 5  is a cross-sectional view of the preferred embodiment, illustrating how a wooden workpiece is finished. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 3 ,  4 , and  5 , the preferred embodiment of a sand belt-tensioning device according to this invention is shown to include a driven roller  4 , a fixing member  5 , a pulling member  6 , and a resilient member  7 . 
   The drive roller  4  includes a roller body  41  having opposite first and second end surfaces  411 ,  412 , and aligned first and second rotating shafts  42 ,  43  extending respectively and axially from the first and second end surfaces  411 ,  412  of the roller body  41 . A sand belt  2  for performing a finishing operation can be wound around the roller body  41  of the roller  4 . 
   The fixing member  5  is sleeved fixedly on the first rotating shaft  42 , and is adjacent to the first end surface  411  of the roller body  41 . A first end  21  of the sand belt  2  is locked on the fixing member  5  in a known manner. 
   The pulling member  6  is sleeved rotatably on the second rotating shaft  43 , and is adjacent to the second end surface  412  of the roller body  41 . A second end  22  of the sand belt  2  is locked on the pulling member  6  at an eccentric position in a known manner. The pulling member  6  has an inner side surface  61  abutting against the second end surface  412  of the roller body  41 , an outer side surface opposite to the inner side surface  61 , and a slot  63  formed through the pulling member  6  and extending along a circumferential direction of the pulling member  6 . The slot  63  has opposite first and second ends  631 ,  632 . 
   The resilient member  7  is disposed within the slot  63  in the pulling member  6 , and is configured as a coiled tension spring that has a first end  71  located at the first end  631  of the slot  63  in the pulling member  6  and fastened to the second end surface  412  of the roller body  41 , and a second end  72  fastened to a wall  64  of the pulling member  6  defining the second end  632  of the slot  63  so as to bias the wall  64  in a direction toward the first end  71  of the resilient member  7 . Thus, the pulling member  6  is biased to rotate in a counterclockwise direction shown by the arrows in  FIG. 5  so as to tauten the sand belt  2  on the driven roller  4 . 
   The pulling member  6  further has an annular outer surface  65  that is formed with a tool hole  66 . To prepare the sand belt-tensioning device for use, the first end  21  of the sand belt  2  is locked on the fixing member  5 , after which the sand belt  2  is wound around the roller body  41  of the drive roller  4 . Subsequently, a tool (not shown) is inserted into the tool hole  66  in the pulling member  6 , and is co-rotated with the pulling member  6  in a clockwise direction against the biasing action of the resilient member  7 . After reaching a desired level of tautness, the second end  22  of the sand belt  2  is locked on the pulling member  6  in a known manner. Finally, the tool is removed from the tool hole  66 . The end result is that the sand belt  2  is maintained in a tautened state on the roller  4 , thereby enabling smooth movement of the wooden workpiece, which is to be finished, relative to the roller  4 . The grinding of the wooden workpiece is also made more effective by such tautening of the sand belt  2  on the roller  4 . 
   With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims.