Methods and Devices for Connecting Two Dissimilar Materials

Abstract

Methods are provided for connecting two dissimilar materials. The methods can include: placing a first material within a groove of a second material, the first material leaving at least a portion of the groove vacant; and placing a third material upon the first material and over the groove; heating the second and third materials to a temperature sufficient to plasticize the second and third materials within the groove and form a mixture of the second and third materials within the groove. Friction stir welding tools are also provided that can include a frusta conical tip having an upper portion defining smooth sidewalls and a lower portion defining a roughened structure.

1 . A method for connecting two dissimilar materials having different melting points, the method comprising:
 placing a first material within a groove of a second material, the first material leaving at least a portion of the groove vacant; and   placing a third material upon the first material and over the groove; heating the second and third materials to a temperature sufficient to plasticize the second and third materials within the groove and form a mixture of the second and third materials within the groove.   
     
     
         2 . The method of  claim 1  wherein said heating is obtained by friction. 
     
     
         3 . The method of  claim 1  wherein said heating is controlled to prevent overheating. 
     
     
         4 . The method of  claim 1  wherein the heating is performed using a friction stir welding device that extends beyond the thickness of the third material into the groove to a plunge depth greater than a thickness of the second material. 
     
     
         5 . The method of  claim 1  wherein said groove defines a dovetail. 
     
     
         6 . The method of  claim 1  wherein the second material is extruded into the groove. 
     
     
         7 . The method of  claim 1  wherein the second material is removed from the groove to form the void. 
     
     
         8 . The method of  claim 1  wherein the first material is loosely placed in the groove of the second material. 
     
     
         9 . The method of  claim 8  wherein the first material is provided in the form of a bar within the groove of the second material. 
     
     
         10 . The method of  claim 8  wherein the void occupies either or both lateral edges of the first material. 
     
     
         11 . The method of  claim 1  wherein the material is heated with a friction stir weld tip. 
     
     
         12 . The method of  claim 8  wherein the tip is frusta conical, wherein an upper portion of the sidewalls of the tip are smooth and a lower portion of the tip define roughened structure. 
     
     
         13 . The method of  claim 8  wherein the friction stir welding tool has a scrolled shoulder and a frustum shaped threaded and flatted pin. 
     
     
         14 . The method of  claim 10  wherein the friction stir welding is performed using a tool rotational speed between 50 and 5000 RPM and a welding speed ranging between 1-5000 mm/min. 
     
     
         15 . The method of  claim 11  wherein the friction stir welding is performed using a tool rotational speed between 200 and 400 RPM and welding speed ranging between 25-50 mm/min. 
     
     
         16 . The method of  claim 11  wherein the temperature of the shoulder of the friction stir welding tool is less than the temperature of the tip of the friction stir welding tool. 
     
     
         17 . A friction stir welding tool comprising a frusta conical tip having an upper portion defining smooth sidewalls and a lower portion defining a roughened structure. 
     
     
         18 . The tool of  claim 16  wherein the friction stir welding tool has a scrolled shoulder and a frustum shaped threaded and flatted pin. 
     
     
         19 . The tool of  claim 16  further comprising a WC tip. 
     
     
         20 . The tool of  claim 18  wherein the upper portion is between the tip and the lower portion.