Door beam

Abstract

A door beam includes an aluminum alloy extrusion body extended in a longitudinal direction and having a pair of webs and a pair of flanges to be positioned on an inner side and an outer side in a width direction of a vehicle body. The pair of webs connect the pair of flanges at joint portions of each of the pair of webs such that the pair of webs and the pair of flanges form a closed cross section in a direction perpendicular to the longitudinal direction, and the pair of webs do not have a welded portion.

What is claimed is: 
     
         1 . A door beam, comprising:
 an aluminum alloy extrusion body extended in a longitudinal direction and having a pair of webs and a pair of flanges to be positioned on an inner side and an outer side in a width direction of a vehicle body,   wherein the pair of webs connect the pair of flanges at joint portions of each of the pair of webs such that the pair of webs and the pair of flanges form a closed cross section in a direction perpendicular to the longitudinal direction, and the pair of webs do not have a welded portion.   
     
     
         2 . The door beam according to  claim 1 , wherein each of the pair of flanges has a welded portion between the joint portions connected to the pair of webs. 
     
     
         3 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body has an intermediate rib connecting the pair of flanges and positioned between the pair of webs, and
 the intermediate rib does not have a welded portion.   
     
     
         4 . The door beam according to  claim 2 , wherein the aluminum alloy extrusion body has an intermediate rib connecting the pair of flanges and positioned between the pair of webs, and
 the intermediate rib does not have a welded portion.   
     
     
         5 . The door beam according to  claim 1 , wherein each of the pair of flanges has a welded portion in a middle of joint portions connected to the pair of webs. 
     
     
         6 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body is bent along the longitudinal direction such that the aluminum alloy extrusion body is curved in a convex form toward an outer side in a width direction of a vehicle body. 
     
     
         7 . The door beam according to  claim 2 , wherein the aluminum alloy extrusion body is bent along the longitudinal direction such that the aluminum alloy extrusion body is curved in a convex form toward an outer side in a width direction of a vehicle body. 
     
     
         8 . The door beam according to  claim 3 , wherein the aluminum alloy extrusion body is bent along the longitudinal direction such that the aluminum alloy extrusion body is curved in a convex form toward an outer side in a width direction of a vehicle body. 
     
     
         9 . The door beam according to  claim 5 , wherein the aluminum alloy extrusion body is bent along the longitudinal direction such that the aluminum alloy extrusion body is curved in a convex form toward an outer side in a width direction of a vehicle body. 
     
     
         10 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body includes an end portion in the longitudinal direction where a distance between the pair of the flanges is narrowed. 
     
     
         11 . The door beam according to  claim 2 , wherein the aluminum alloy extrusion body includes an end portion in the longitudinal direction where a distance between the pair of the flanges is narrowed. 
     
     
         12 . The door beam according to  claim 3 , wherein the aluminum alloy extrusion body includes an end portion in the longitudinal direction where a distance between the pair of the flanges is narrowed. 
     
     
         13 . The door beam according to  claim 5 , wherein the aluminum alloy extrusion body includes an end portion in the longitudinal direction where a distance between the pair of the flanges is narrowed. 
     
     
         14 . The door beam according to  claim 6 , wherein the aluminum alloy extrusion body includes an end portion in the longitudinal direction where a distance between the pair of the flanges is narrowed. 
     
     
         15 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body comprises a 7000-series aluminum alloy. 
     
     
         16 . The door beam according to  claim 1 , wherein each of the pair of the flanges has a thickness greater than a thickness of each of the webs. 
     
     
         17 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body has an intermediate rib connecting the pair of flanges and positioned between the pair of webs, and
 each of the pair of flanges has a welded portion at a position not connected to the intermediate rib and between the joint portions connected to the pair of webs.   
     
     
         18 . The door beam according to  claim 1 , wherein the aluminum alloy extrusion body comprises an aluminum alloy including Al, 3-8 mass % of Zn, 0.4-2.5 mass % of Mg, 0.05 to 2.0 mass % of Cu, and 0.005 to 0.2 mass % of Ti, and further including at least one of 0.01 to 0.3 mass % of Mn, 0.01 to 0.3 mass % of Cr, and 0.01 to 0.3 mass % of Zr. 
     
     
         19 . A method of producing the door beam of  claim 1 , comprising:
 pressing an aluminum billet into a porthole die having a plurality of portholes such that pressed aluminum billet is divided by the portholes; and   welding divided aluminum billets to one another such that the aluminum alloy extrusion body is formed.