Method and apparatus for removing slag and burrs from a metal surface

Abstract

A tool for removing slag from a flame-cut edge of metal includes a downwardly facing cup containing a plurality of steel balls. Only a portion of each ball extends from the lower end of the cup. A radially outer wall of the cup slants from a first position at its upper end to a second radially outer position at its lower end. As a result, when the cup rotates, centrifugal force urges the balls downwardly with a force that is proportional to the speed of rotation. As the cup moves over slag, lateral impact from the balls remove the slag. Because the balls are not connected to surrounding structure, they are free to rapidly move upwardly in the cup in response to hitting the edge of the cut. Consequently neither the edge nor the surface of the metal is peened or otherwise marred or disfigured.

1 . An apparatus for removing irregularities from the surface of a substantially planar workpiece comprising:
 a head including a cavity that communicates with a substantially planar surface of the head;   a rotary drive for rotating the head about a first axis thereby creating centrifugal force along a second axis substantially normal to the first axis;   at least one ball contained within the cavity;   a retainer for retaining a portion of the ball within the cavity while permitting a portion of the ball to extend from the cavity; and   a substantially planar surface defining a wall of the cavity, the ball being forced into the wall and against the retainer with a force substantially proportional to such a centrifugal force, the ball sliding across the surface of the workpiece when said apparatus is in operative condition.   
   
   
       2 . The apparatus of  claim 1  wherein the cavity is sufficiently large to permit the ball to be received entirely within the cavity responsive to a force urging the ball away from the workpiece when said apparatus is in operative condition. 
   
   
       3 . The apparatus of  claim 1  further comprising a guard surrounding the head and having a lower surface that engages the substantially planar surface of the workpiece when said apparatus is in operative condition. 
   
   
       4 . The apparatus of  claim 1  wherein the cavity contains a plurality of balls. 
   
   
       5 . The apparatus of  claim 4  wherein the cavity includes a central post and the retainer is mounted on the end of the post. 
   
   
       6 . The apparatus of  claim 5  wherein the retainer comprises a substantially round disc. 
   
   
       7 . The apparatus of  claim 4  wherein the cavity comprises an annular groove in which the balls are received, the centrifugal force maintaining at least two balls in at least one opposing pair when the apparatus is in operative condition. 
   
   
       8 . The apparatus of  claim 7  wherein the retainer is operatively connected to the head radially inwardly from the annular groove. 
   
   
       9 . A method for removing surface irregularities from a substantially planar workpiece comprising:
 rotating a downwardly directed cup over the work piece;   providing a plurality of balls within the cup;   restraining the balls so that only a portion of each ball extends beneath the lower surface of the cup during rotation; and   urging the balls against the surface of the workpiece.   
   
   
       10 . The method of  claim 9  wherein the method further comprises:
 rotating the cup at a first speed at which the balls exert a first amount of downward pressure; and   rotating the cup at a second faster speed at which the balls extend a second greater amount of downward pressure.   
   
   
       11 . The method of  claim 9  wherein the cup includes a sloping side and wherein the method further comprises substantially restraining the balls to predefined radial positions on the cup side. 
   
   
       12 . The method of  claim 11  further comprising permitting substantially vertical movement of each ball along the cup side. 
   
   
       13 . An apparatus for removing irregularities from the surface of a substantially planar workpiece comprising:
 a downwardly directed cup constructed and arranged for rotation over the workpiece;   a plurality of balls contained within the cup; and   a retainer associated with the cup for retaining the majority of each ball within the cup.   
   
   
       14 . The apparatus of  claim 13  wherein the balls are urged against the surface of the workpiece when said apparatus is in operative condition, the cup being sufficiently large to permit the balls to be received entirely within the cup responsive to a force urging the ball away from the workpiece. 
   
   
       15 . The apparatus of  claim 13  further comprising a guard surrounding the cup and having a lower surface that engages the substantially planar surface of the workpiece when said apparatus is in operative condition. 
   
   
       16 . The apparatus of  claim 13  wherein the cup includes a central post and the retainer is mounted on the end of the post. 
   
   
       17 . The apparatus of  claim 16  wherein the retainer comprises a substantially round disc. 
   
   
       18 . The apparatus of  claim 13  wherein a centrifugal force maintains at least two balls in at least one opposing pair when the apparatus is in operative condition.