Friction-stir extruders and friction-stir extrusion processes

Abstract

A friction-stir mandrel includes a textured end portion integral with a body portion. The textured end portion is configured to friction-stir process a starting material forced across the textured end portion and through a die in a plasticized state to form a pipe. A pipe can be formed by forcing a starting material across a textured end of the mandrel and through a die in a plasticized state, so that the textured end of the mandrel breaks up existing grains of the starting material. The pipe is formed from material that is forced through the die. The friction-stir mandrel can be used with porthole die friction-stir extrusion, seamless tube friction-stir extrusion, and tube friction-stir drawing processes to provide tubing in which the grains are broken up by the textured portion of the friction-stir mandrel. The textured portion can include features, such as threads, ridges, studs, protrusions, and the like.

1 . A friction-stir mandrel, comprising:
 a textured end portion integral with a body portion, the textured end portion configured to friction-stir process a starting material forced across the textured end portion and through a die in a plasticized state to form a pipe.   
     
     
         2 . The friction-stir mandrel of  claim 1 , wherein the friction-stir mandrel is configured to rotate while the starting material remains rotationally stationary. 
     
     
         3 . The friction-stir mandrel of  claim 1 , wherein the friction-stir mandrel is configured to remain rotationally stationary while the starting material rotates. 
     
     
         4 . The friction-stir mandrel of  claim 1 , further comprising a smooth cap formed over an end of the textured end portion, the smooth cap configured to provide a final smooth interior surface on the formed pipe. 
     
     
         5 . The friction-stir mandrel of  claim 1 , wherein a diameter of the textured end portion is slightly larger than an inside diameter of the formed pipe and smaller than an outside diameter of the formed pipe. 
     
     
         6 . The friction-stir mandrel of  claim 1 , wherein the friction-stir mandrel is integral with the die. 
     
     
         7 . The friction-stir mandrel of  claim 1 , wherein the friction-stir mandrel is configured to pierce through the starting material. 
     
     
         8 . The friction-stir mandrel of  claim 1 , wherein the friction-stir mandrel is configured to be drawn into the die in conjunction with drawing the starting material over the friction-stir mandrel by a tube gripper. 
     
     
         9 . The friction-stir mandrel of  claim 1 , wherein the starting material comprises a metal. 
     
     
         10 . The friction-stir mandrel of  claim 9 , wherein the metal comprises aluminum or an aluminum alloy. 
     
     
         11 . The friction-stir mandrel of  claim 1 , wherein the textured end portion comprises one of threads, ridges, studs, or protrusions. 
     
     
         12 . A method of forming a pipe, comprising:
 forcing a starting material across a textured end of a mandrel and through a die in a plasticized state, so that the textured end of the mandrel breaks up existing grains of the starting material; and   forming the pipe from material forced through the die, wherein the formed pipe has fine equiaxed resultant grains in multiple orientations on an interior surface of the formed pipe than the existing grains of the starting material.   
     
     
         13 . The method of  claim 12 , further comprising:
 rotating the mandrel while the starting material remains rotationally stationary.   
     
     
         14 . The method of  claim 12 , further comprising:
 rotating the starting material while the mandrel remains rotationally stationary.   
     
     
         15 . The method of  claim 12 , further comprising:
 forming a smooth interior surface on the formed pipe via a smooth cap formed over an end of the textured end.   
     
     
         16 . The method of  claim 12 , wherein the starting material comprises a metal. 
     
     
         17 . The method of  claim 16 , wherein the metal comprises aluminum or an aluminum alloy. 
     
     
         18 . The method of  claim 12 , wherein the textured end comprises one of threads, ridges, studs, or protrusions. 
     
     
         19 . The method of  claim 12 , wherein the pipe comprises a seamless tube pipe. 
     
     
         20 . A porthole die friction-stir extrusion method, comprising:
 loading a feedstock billet into a container;   abutting one end of the feedstock billet with a ram and abutting another end of the feedstock billet against a die mandrel;   rotating the feedstock billet and the container against a die cap while pressure is applied by the ram;   extruding plasticized feedstock through passages of the die mandrel, wherein grains of the plasticized feedstock are broken up by a textured mandrel tip of the die mandrel; and   forming a hollow tube from the extruded plasticized feedstock.   
     
     
         21 . The porthole die friction-stir extrusion method of  claim 20 , further comprising:
 rotating the die mandrel while rotating the feedstock billet and the container.   
     
     
         22 . The porthole die friction-stir extrusion method of  claim 20 , further comprising:
 smoothing an interior surface of the extruded hollow tube via a mandrel bearing attached to an end of the textured mandrel tip.   
     
     
         23 . The porthole die friction-stir extrusion method of  claim 20 , further comprising:
 extruding the plasticized feedstock through a hollow punch aperture integrally formed with the die mandrel.   
     
     
         24 . The porthole die friction-stir extrusion method of  claim 20 , further comprising:
 extruding the plasticized feedstock through a rotating hollow punch aperture.   
     
     
         25 . The porthole die friction-stir extrusion method of  claim 20 , wherein the textured mandrel tip comprises one of threads, ridges, studs, or protrusions. 
     
     
         26 . A seamless tube friction-stir extrusion method, comprising:
 loading a feedstock billet into a container;   abutting one end of the feedstock billet with a ram and a concentrically-located mandrel, and abutting another end of the feedstock billet against a die;   piercing through the feedstock billet with the concentrically-located mandrel up to the die;   applying pressure to the feedstock billet by the ram;   extruding plasticized feedstock through the die and over a textured portion of the concentrically-located mandrel, wherein grains of the plasticized feedstock are broken up by the textured portion of the concentrically-located mandrel; and   forming a seamless tube from the extruded plasticized feedstock.   
     
     
         27 . The seamless tube friction-stir extrusion method of  claim 26 , further comprising:
 rotating the concentrically-located mandrel during the extruding.   
     
     
         28 . The seamless tube friction-stir extrusion method of  claim 26 , further comprising:
 forming a recrystallized microstructure in an interior wall of the seamless tube.   
     
     
         29 . The seamless tube friction-stir extrusion method of  claim 26 , wherein the textured portion comprises one of threads, ridges, studs, or protrusions. 
     
     
         30 . A tube friction-stir drawing method, comprising:
 loading a first end of a tube work piece into a die tool and tool carrier of a container;   inserting a mandrel tool at a second end of the tube work piece;   engaging the first end of the tube work piece;   drawing a textured portion of the mandrel tool inside the die tool while continuously drawing the tube work piece over the textured portion, wherein grains of the drawn tube work piece are broken up by the textured portion of the mandrel tool; and   forming a drawn tube of smaller diameter and thinner wall thickness.   
     
     
         31 . The tube friction-stir drawing method of  claim 30 , further comprising:
 rotating the mandrel tool during the drawing.   
     
     
         32 . The tube friction-stir drawing method of  claim 30 , further comprising:
 rotating the container and the tube work piece during the drawing.   
     
     
         33 . The tube friction-stir drawing method of  claim 30 , wherein the textured portion comprises one of threads, ridges, studs, or protrusions. 
     
     
         34 . The tube friction-stir drawing method of  claim 30 , wherein the engaging the first end of the tube work piece includes using a gripper at the first end.