Patent Publication Number: US-9849564-B2

Title: Backing plate for adhesive flap wheels

Description:
FIELD OF THE INVENTION 
     The present invention relates to a backing plate for abrasive flap wheels. 
     BACKGROUND OF THE INVENTION 
     A backing plate of this kind is known from German utility Patent 20 2012 100 088 to Jobra Metall GmbH, according to which aeration slots are provided in a cone shaped junction ring between the outer flange and the inner part. The slots are directed in an inclined sense with respect to the radial direction. Air deflection wings between the slots ensure a good cooling effect during operation of the grinding wheel. 
     SUMMARY OF THE INVENTION 
     Starting from such prior art, it is an object of the invention to improve even more the cooling effect of the backing plate for abrasive flap wheels in order to optimize heat dissipation during operation. 
     According to the invention, this problem is solved by a backing plate, in which the slots are formed in the outer flange such that they are radially open on its outer edge. Advantageously said slots are also inclined with respect to the radial direction. 
     These radially open slots provided in the annular outer flange ensure a better cooling and provide for a higher elasticity of the backing plate, which results in higher abrading efficiency and longer endurance of the abrasive flaps with its grains embedded therein and of the entire abrasive flap wheels. 
     In an advantageous embodiment of the invention, the slots are delimited by a plane baffle surface on their upstream side lagging with respect to the sense of rotation of the backing plate, the baffle surface forming a right angle with the annular fixing surface of the outer flange, wherein opposite to the baffle surface a curved deflection wall is formed. 
     Such embodiment has the effect that, during rotation of the grinding wheel, cooling air will be circumferentially introduced through the curved deflection wall into the slot where it abuts against the opposite baffle surface on which it is axially deflected toward the annular fixing surface. Here the cooling air abuts the abrasive flaps such that it is finally deviated outside in a radial sense. In this way the heat is dissipated directly on the abrasive flaps. 
     According to another embodiment of the invention, the outer flange is connected with the dome shaped inner part by means of a conical ring provided with circumferentially distributed aeration slots, which ensure an improved cooling effect. 
     Finally, the central location hole in the inner part may be formed as a hub having an internal thread for fastening the grinding wheel on the shaft of a driving machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be explained in more detail with reference to some embodiments shown in the drawings, in which: 
         FIG. 1  shows a plan view of a backing plate for abrasive flap wheels according to a first embodiment; 
         FIG. 2  shows a section along line A-A of  FIG. 1 ; 
         FIG. 3  shows a perspective view of the backing plate; 
         FIG. 4  shows a modified embodiment having a threaded hub for fastening on the shaft of a driving machine; 
         FIG. 5  is a section A-A of  FIG. 4 ; 
         FIG. 6  shows a perspective view of the backing plate of  FIGS. 4 and 5 ; 
         FIG. 7  shows the top view of a further embodiment of the backing plate, wherein the dome shaped inner part is provided with aeration slots; 
         FIG. 8  is a section A-A of  FIG. 7 ; and 
         FIG. 9  shows a perspective view similar to  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
       FIGS. 1 to 3  show a first embodiment of a grinding wheel  10 , the circular backing plate  12  of which is already provided with abrasive flaps  14 . The backing plate  12  is made of a single synthetic piece, e.g. of polyamide or ABS, which has the advantage of a long life, a sufficient elasticity and poison-less characteristics. 
     The backing plate  12  is composed of a dome shaped inner part  16  and of an annular outer flange  18 , which is an integral part of the inner part  16 , to which it is connected by a conical ring  20 . The inner part  16  has a central location hole  22  for fastening the backing plate  12  on the shaft of a driving machine. 
     The abrasive flaps  14  are fastened by bonding on an annular fixing surface  24  (see  FIG. 8 ) of the flange  18  on the opposite side of the inner part  16 . 
     According to the invention, the backing plate  12  is circumferentially provided with openings for the passage of cooling air, which are made of slots  26  formed in the outer flange  18  such that they are radially open on its outer edge  28 . 
     As shown in  FIGS. 1 and 3 , said slots  26  are inclined with respect to the radial direction. The slots  26  are delimited by plane baffle surfaces  30  on their edge lagging with respect to the rotation sense of the backing plate  12  (upstream) and consequently of the grinding wheel  10 . Each baffle surface  30  forms a right angle with the annular fixing surface  24  of the outer flange  18 . 
     In each slot  26 , opposite to the baffle surface  30  a curved deflection wall  32  is formed. As shown by the arrows in  FIGS. 1 to 3 , the air of the environment is drawn through the rotation of the grinding wheel  10  along the deflection wall  32  into each slot  26  where it is guided against the baffle surface  30  to abut the inner side of the abrasive flaps  14 . Here the air absorbs the heat of the flaps  14  and is finally deviated outside in a radial sense (see arrows a). 
       FIGS. 4 to 6  show a similar backing plate  10  provided with slots  26  for the passage of cooling air. The outer flange  18  is connected with its dome shaped inner part  16  by means of a conical ring  20 . The dome shaped inner part  16  is provided with a hub  34 , the central location  22  of which has an internal thread  36  for the fastening on the shaft of the driving machine. 
     In the embodiment of  FIGS. 7 and 8 , the dome shaped inner part  16  of the backing plate  12  is also provided with aeration slots  38  which, similar to the slots  26 , are circumferentially distributed and inclined with respect to the radial direction. 
       FIG. 9  shows a further embodiment, according to which the central location  22 , similar to  FIG. 6 , is provided in a hub  34  having an internal thread  36 .