Stir-friction hot working control system

Abstract

A stir-friction hot-working or welding arrangement uses a pin tool having a ligament 22 and a shoulder 224 . The force required for incremental penetration increases markedly when the shoulder is reached. A control system for maintaining a set penetration depth includes a load cell for measuring force or pressure applied to the pin tool. The control system compares a reference signal representing the desired force with the actual force from the load cell, to produce an error signal which controls the penetration force, thereby tending to maintain a desired penetration depth. In a particular embodiment, the reference signal ramps up from a low or zero value at turn-on, to reduce forces applied upon initial penetration. In another embodiment, position signals are used to control a modulator or multiplier, which changes the error signal applied at certain positions of penetration, or at certain velocities of penetration.

1 - 8 . (Canceled)  
   
   
       9 . A stir-friction welder, comprising: 
 a frame;    a lead screw rotatably interconnected with said frame;    a first drive interconnected with said lead screw;    a first sensor located between said frame and said lead screw;    a controller interconnected with said first sensor and said first drive;    a head mounted on said lead screw; and    a pin tool interconnected with said head, wherein rotation of said lead screw by said first drive, responsive to an input by said first sensor to said controller, changes a position of said head along said lead screw, and thereby a plunge depth of said pin tool relative to a workpiece.    
   
   
       10 . A stir-friction welder, as claimed in  claim 9 , wherein: 
 said first sensor is a load cell.    
   
   
       11 . A stir-friction welder, as claimed in  claim 9 , further comprising: 
 a bearing holder and a bearing mounted in said bearing holder, wherein said lead screw is rotatably supported by said bearing, wherein said first sensor interfaces with said bearing holder.    
   
   
       12 . A stir-friction welder, as claimed in  claim 9 , wherein: 
 said head comprises a second drive interconnected with pin tool, wherein said second drive rotates said pin tool relative to the workpiece.    
   
   
       13 . A stir-friction welder, comprising: 
 a frame;    a lead screw rotatably interconnected with said frame;    a first drive interconnected with said lead screw;    a first sensor that is stationary;    a controller interconnected with said first sensor and said first drive;    a head mounted on said lead screw; and    a pin tool interconnected with said head, wherein rotation of said lead screw by said first drive, responsive to an input by said first sensor to said controller, changes a position of said head along said lead screw, and thereby a plunge depth of said pin tool relative to a workpiece.    
   
   
       14 . A stir-friction welder, as claimed in  claim 13 , wherein: 
 said first sensor is located between said frame and said lead screw.    
   
   
       15 . A stir-friction welder, as claimed in  claim 13 , wherein: 
 said first sensor is a load cell.    
   
   
       16 . A stir-friction welder, as claimed in  claim 13 , further comprising: 
 a bearing holder and a bearing mounted in said bearing holder, wherein said lead screw is rotatably supported by said bearing, wherein said first sensor interfaces with said bearing holder.    
   
   
       17 . A stir-friction welder, as claimed in  claim 13 , wherein: 
 said head comprises a second drive interconnected with pin tool, wherein said second drive rotates said pin tool relative to the workpiece.