Articulating constant force finishing tool actuator

Abstract

An apparatus for maintaining constant force engagement between a finishing tool and a workpiece. The apparatus includes a biasing device that can be coupled to a robotic manipulator, and a support arm having a tool holder disposed at one end. The biasing device is actuated by a pressure source to cause the support arm to rotate a finishing tool into engagement with a workpiece. A counterweight disposed on a second end of the support arm offsets the mass of the finishing tool, whereby constant force engagement between the finishing tool and workpiece may be maintained as the finishing tool is articulated to move relative to the workpiece.

What is claimed is:  
     
         1 . An apparatus for maintaining constant force engagement between 
 a finishing tool and a workpiece, the apparatus comprising:    a biasing device couplable to a robotic manipulator for articulation about and along at least two orthogonal axes relative to the workpiece;    a support arm extending from said biasing device and having an inner end operatively coupled to said biasing device for movement in at least two orthogonal directions toward the workpiece, and having a distal end; and    a tool holder disposed on a distal end of said support arm and configured to support the finishing tool;    said biasing device configured to move said support arm to engage the finishing tool against the workpiece at a constant force.    
     
     
         2 . The apparatus of  claim 1 , wherein said biasing device comprises: 
 a rotary actuator having an output shaft; and    a bearing assembly operatively coupled to said support arm and engaging said output shaft, whereby rotation of said output shaft moves said support arm to engage the workpiece with a constant force.    
     
     
         3 . The apparatus of  claim 1 , further comprising a counterweight disposed on said support arm, generally opposite said tool holder, to offset the mass of said tool holder and the finishing tool supported by said support arm.  
     
     
         4 . The apparatus of  claim 2 , wherein said rotary actuator comprises: 
 at least one piston member actuatable by a pressure source;    a rack gear coupled to said piston for movement in response to actuation of said piston; and    a pinion gear coupled to said output shaft and engaging said rack gear, whereby actuation of said piston causes said output shaft to rotate.    
     
     
         5 . The apparatus of  claim 2 , wherein said rotary actuator includes at least one vane coupled to said output shaft, whereby said output shaft is rotated by placing said vane in communication with a source of pressurized fluid.  
     
     
         6 . The apparatus of  claim 1 , further comprising a robotic manipulator adapted to be coupled to said biasing device and to articulate said biasing device, said support arm, and said tool holder relative to the workpiece while said biasing device moves said support arm to engage the finishing tool against the workpiece at a constant force.