Method for grinding a workpiece

Abstract

A method of modifying a workpiece such as a geared member includes grinding the workpiece with a rotating grinding wheel, and superimposing a primary motion of the axis of rotation of the grinding wheel with a secondary, oscillatory motion of the axis of rotation. The primary motion is oriented perpendicular to the axis of rotation. A motorized apparatus for modifying a workpiece includes a workpiece holding device, a grinding wheel which rotates about a first axis, and the first axis rotating about a second axis, wherein the workpiece holding device and the grinding wheel are moved toward each other in a direction of feed normal to the first axis and permitting a radial face of the grinding wheel to grind against the workpiece via intermittent contact.

1 . A method of modifying a workpiece comprising: 
 grinding the workpiece via a plurality of passes with a rotating grinding wheel, including moving an axis of rotation of the grinding wheel back and forth relative to the workpiece; and    while grinding the workpiece, moving the axis of rotation of the grinding wheel relative to the workpiece in a primary motion along a path oriented perpendicular to the axis, wherein moving the axis of rotation includes superimposing onto the primary motion a secondary, oscillatory motion of the axis relative to the workpiece.    
   
   
       2 . The method of  claim 1  wherein superimposing onto the primary motion a secondary, oscillatory motion comprises superimposing onto a linear motion a non-linear motion of the axis of rotation of the grinding wheel.  
   
   
       3 . The method of  claim 2  wherein grinding the workpiece comprises urging an outer radial portion of the grinding wheel against the workpiece.  
   
   
       4 . The method of  claim 3  wherein the grinding wheel includes a driveshaft, the method further comprising reacting primary loads on the driveshaft via journal bearings disposed about the driveshaft.  
   
   
       5 . The method of  claim 3  wherein the outer radial portion comprises at least one dihedral edge pointing outwardly from the axis of rotation of the grinding wheel, and wherein grinding the workpiece comprises contacting the at least one dihedral edge therewith.  
   
   
       6 . The method of  claim 5  wherein the workpiece comprises a geared member having at least two gear teeth, and wherein grinding the workpiece comprises contacting the at least one dihedral edge with the workpiece along an arcuate contact path between the at least two gear teeth having a path length defined at least in part by a radius of a circular path of the axis of rotation defining the secondary, oscillatory motion.  
   
   
       7 . The method of  claim 6  wherein grinding the workpiece further comprises intermittently contacting the at least one dihedral edge simultaneously with side walls of a groove between the at least two gear teeth.  
   
   
       8 . The method of  claim 3  further comprising dressing the grinding wheel while grinding the workpiece.  
   
   
       9 . A method of grinding a profiled form member comprising: 
 grinding at least one groove in the member via a plurality of passes with a rotating grinding wheel, including moving an axis of rotation of the grinding wheel back and forth relative to the member; and    moving the axis of rotation of the grinding wheel relative to the member in a feed direction oriented perpendicular to the axis, including moving the axis via an oscillatory motion thereof relative to the member.    
   
   
       10 . The method of  claim 9  wherein the profiled form member comprises a geared member, and wherein moving the axis of rotation comprises moving the axis of rotation of the grinding wheel via an oscillatory, non-linear motion of the axis superimposed onto a linear motion parallel the feed direction.  
   
   
       11 . The method of  claim 10  wherein the at least one groove includes a preformed groove between adjacent gear teeth, and wherein grinding the workpiece further comprises urging at least one dihedral edge of the grinding wheel pointing outwardly from the axis against the geared member.  
   
   
       12 . The method of  claim 11  wherein grinding the workpiece comprises intermittently contacting walls of the groove simultaneously with the at least one dihedral edge to form a plurality of adjacent facets along each of the contacted walls.  
   
   
       13 . The method of  claim 11  wherein grinding the workpiece comprises grinding a plurality of preformed grooves of the geared member via a plurality of dihedral edges of the grinding wheel pointing outwardly from the axis of rotation.  
   
   
       14 . The method of  claim 13  wherein grinding the workpiece comprises contacting the plurality of dihedral edges of the grinding wheel each with one of the respective grooves along an arcuate contact path having a path length defined at least in part by an eccentricity of the axis of rotation of the grinding wheel.  
   
   
       15 . The method of  claim 14  wherein the geared member comprises a gear rack, the method further comprising moving the arcuate contact path of each of the dihedral edges along a length of the grooves, and wherein grinding the at least one groove comprises grinding a plurality of grooves and moving the axis of rotation of the grinding wheel back and forth relative to the profiled form member while contacting the plurality of grooves with the rotating grinding wheel.  
   
   
       16 . A motorized apparatus for grinding a workpiece comprising: 
 a workpiece holding device which holds thereon a workpiece to be modified;    a grinding wheel which rotates about a first axis, the grinding wheel having a radial face and two opposed axial faces, each of the axial faces having a circumferential edge, each circumferential edge being joined to the other by the radial face;    the first axis rotating about a second axis that is generally parallel to and offset from the first axis, defining an oscillatory motion of the first axis relative to the workpiece; and    wherein the workpiece holding device and the grinding wheel are moved together in a direction of feed, defining a primary motion of the first axis upon which the oscillatory motion is superimposed, that is normal to the first axis permitting the radial face to grind against the workpiece.    
   
   
       17 . A motorized apparatus according to  claim 16  wherein the grinding wheel rotates about the first axis in a first direction, and the first axis rotates about the second axis in a second direction opposite the first.  
   
   
       18 . A motorized apparatus according to  claim 17  wherein the ratio of the rotational speed of the grinding wheel about the first axis to the rotational speed of the first axis about the second axis is in the range of 0.8 to 1.6.  
   
   
       19 . A motorized apparatus according to  claim 18  wherein the ratio of the rotational speed of the grinding wheel about the first axis to the rotational speed of the first axis about the second axis is in the range of 1.0 to 1.4.  
   
   
       20 . A motorized apparatus according to  claim 19  wherein the ratio of the rotational speed of the grinding wheel about the first axis to the rotational speed of the first axis about the second axis is about 1.2.  
   
   
       21 . A motorized apparatus according to  claim 16  wherein the first axis is offset from the second axis by a distance less than 0.02 inches.  
   
   
       22 . A motorized apparatus according to  claim 21  wherein the first axis is offset from the second axis by a distance less than 0.01 inches.  
   
   
       23 . A motorized apparatus according to  claim 16  wherein the radial face is a generally flat surface whereby each point on the surface is located at generally the same radius from a central axis of the grinding wheel.  
   
   
       24 . A motorized apparatus according to  claim 16  wherein the radial face is profiled.