Lateral position detection for friction stir systems

Abstract

A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

1 . A friction stir system for processing at least a first workpiece, comprising:
 a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing said first workpiece; and   a detection system for obtaining information related to a lateral alignment of said rotating member with respect to a selected lateral position, a selected path, or a selected direction relative to at least one force sensor signal generating feature associated with said first workpiece, comprising:
 at least one force sensor for measuring a force experienced by said rotary tool or a parameter related to said force experienced by said rotary tool during said processing, wherein said force sensor provides force sensor signals associated with said measured force or said measured parameter, and 
 a signal processing system coupled to receive and analyze said force sensor signals, to discern from said force sensor signals a distance to said signal generating feature from said rotating member, and to determine a lateral alignment of said rotating member relative to a selected lateral position, a selected path, or a selected direction based on said discerned distance to decrease a lateral distance of said rotary tool relative to said selected lateral position, said selected path, or said direction. 
   
     
     
         2 . The system of  claim 1 , wherein said rotating member comprises a shoulder and a probe extending outwardly from said shoulder. 
     
     
         3 . (canceled) 
     
     
         4 . The system of  claim 1 , wherein said force sensor comprises a dynamometer. 
     
     
         5 . The system of  claim 1 , wherein said signal processing system applies stored correlation data operable to determine lateral offset values for said rotary tool relative to said selected lateral position, said selected path, or said selected direction to decrease a lateral distance relative to said selected lateral position, said selected path, or said selected direction from said sensor signals. 
     
     
         6 . (canceled) 
     
     
         7 . The system of  claim 1 , wherein said system further comprises a backing plate under said first workpiece, wherein said signal generating feature comprises a sensor signal enhancement feature, and wherein said sensor signal enhancement feature comprises a material variation of said backing plate, a surface indentation or protrusion in said backing plate, or thickness variation of said backing plate. 
     
     
         8 . The system of  claim 1 , further comprising a closed loop control system comprising a controller coupled to said signal processing system operable to receive said lateral alignment and control a lateral position of said rotary tool. 
     
     
         9 . The system of  claim 8 , further comprising:
 a servo motor coupled to receive control signals from said controller, and   an arm driven by said servo motor coupled to said rotary tool, wherein said control signals from said controller are operable to cause said servo motor to move said arm to automatically control said lateral position of said rotary tool so that said sensor signals are within a predetermined range or said lateral alignment is maintained within a predetermined limit or range.   
     
     
         10 . The system of  claim 9 , further comprising a robotic module, wherein said arm is a robotic arm of said robotic module. 
     
     
         11 . A tracked friction stir welding system for welding at least a first and a second workpiece, comprising:
 a spindle actuator coupled to a rotary tool comprising a rotating member comprising a shoulder and a probe extending outwardly from said shoulder for contacting and processing said first and second workpiece;   a detection system for obtaining information related to a lateral alignment of said rotating member with respect to a selected lateral position, a selected path, or a selected direction relative to a joint line for said first and second workpieces, comprising:
 at least one force sensor for measuring a force experienced by said rotary tool during said processing, wherein said force sensor provides sensor signals (force sensor signals) associated with said measured force, and 
 a signal processing system coupled to receive and analyze said force sensor signals, to discern from said force sensor signals a distance of said joint line to said rotating member, and to determine a lateral alignment of said rotating member relative to said selected lateral position, said selected path, or said selected direction based on said discerned distance; and 
   a closed loop control system comprising a controller coupled to said signal processing system operable to receive said lateral alignment and control a lateral position of said rotary tool to decrease a lateral distance of said rotary to relative to said selected lateral position, said selected path, or said selected direction.   
     
     
         12 . The system of  claim 11 , further comprising:
 a servo motor coupled to receive control signals from said controller, and   an arm driven by said servo motor coupled to said rotary tool, wherein said control signals from said controller are operable to cause said servo motor to move said arm to automatically control said lateral position of said rotary tool so that said sensor signals are within a predetermined range or said lateral alignment is maintained within a predetermined limit or range.   
     
     
         13 . The system of  claim 11 , wherein said system includes at least one sensor signal enhancement feature based on said system. 
     
     
         14 . The system of  claim 13 , wherein said system further comprises a backing plate under at least one of said first and second workpiece, wherein said sensor signal enhancement feature comprises a material variation of said backing plate, a surface indentation or protrusion in said backing plate, or thickness variation of said backing plate. 
     
     
         15 - 31 . (canceled) 
     
     
         32 . A friction stir system for processing at least a first workpiece, comprising:
 a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing said first workpiece;   a detection system for obtaining information related to a lateral alignment measure of said rotating member relative to a selected reference position, path or direction with respect to a portion of said second workpiece contacting said first workpiece, comprising:
 at least one force sensor for measuring a force experienced by said rotary tool or a parameter related to said force experienced by said rotary tool during said processing, wherein said force sensor provides force sensor signals associated with said measured force or said measured parameter, and 
 a signal processing system having associated memory which includes a stored program that relates said force experienced by said rotary tool to said lateral alignment measure for said rotating member, said signal processing system coupled to receive and analyze said force sensor signals, to discern a distance of said portion of said second workpiece contacting said first workpiece to said rotating member from said force sensor signals, and determine said lateral alignment measure of said rotating member relative to said selected reference based on said discerned distance. 
   
     
     
         33 . The system of  claim 32 , further comprising:
 at least one motor configured to move said rotating member laterally over said first workpiece;   a controller having an input coupled to an output of said signal processing system, said controller operable to receive said lateral alignment measure and output control signals, said control signals coupled to said motor operable for decreasing a lateral distance of said rotating member relative to said selected reference.   
     
     
         34 . The system of  claim 1 , wherein said sensor signals are associated with at least one among an axial force, an in plane force, and a torque experienced by said rotary tool. 
     
     
         35 . The system of  claim 1 , wherein said selected lateral position, said selected path, and said selected direction are relative to at least a portion of at least a second workpiece contacting said first workpiece. 
     
     
         36 . The system of  claim 11 , wherein said sensor signals are associated with at least one among an axial force, an in plane force, and a torque experienced by said rotary tool. 
     
     
         37 . The system of  claim 11 , wherein said selected lateral position, said selected path, and said selected direction are relative to at least a portion of said second workpiece contacting said first workpiece. 
     
     
         38 . The system of  claim 1 , wherein a second workpiece is positioned in contact said first workpiece, and wherein said signal generating feature comprises contacting portions of said first and said second workpieces. 
     
     
         39 . The system of  claim 8 , wherein the controller moves said the rotary tool along said selected direction or path in a weaving pattern.