Profile element pipe for hydraulic bulging, hydraulic bulging device using the element pipe, hydraulic bulging method using the element pipe, and hydraulically bulged product

Abstract

A profile element pipe for hydraulic bulging of the present invention has a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and has a parallel part formed on at least one end thereof. According to a bulging device and a bulging method using this profile element pipe, for example, even when a profile steel pipe having a cross sectional shape varying in the axial direction as in a tapered pipe is hydraulically bulged, a bulging in which an internal pressure loading and an shaft pressing are combined with each other can be performed to provide a larger expansion ratio than a conventional case and a joining and socket connection thereof to the other part can also be easily performed.

1 . A profile element pipe for hydraulic bulging, wherein said profile element pipe has a peripheral length with an outer diameter gradually increasing or decreasing from one axial side to the other thereof and a parallel part formed on at least one end thereof.  
   
   
       2 . The profile element pipe for hydraulic bulging according to  claim 1 , wherein a length of said parallel part is equal to, or more than, a total length of an amount of shaft pressing subjected in hydraulic bulging and a length necessary for sealing during hydraulic bulging.  
   
   
       3 . The profile element pipe for hydraulic bulging provided for producing a hydraulically bulged product having a rectangular cross section or a polygonal cross section according to  claim 2 , wherein a radius R of curvature of a corner part in said parallel part is varied in accordance with a change in a peripheral length in which an outer diameter of the profile element pipe is gradually increased or decreased.  
   
   
       4 . A hydraulic bulging device characterized by comprising: 
 a pair of dies, and    shaft pressing tools also serving as sealing tools, in which front end portions of the tools are inserted into both ends of said dies, for holding said profile element pipe according to  claim 1 , while sandwiching the profile element pipe with said dies,    wherein a filling hole for working liquid is provided at any one of said shaft pressing tools and parallel parts are provided on at least one end-portion inner surface of said dies and an outer surface of said shaft pressing tool corresponding to this end-portion inner surface, respectively.    
   
   
       5 . A hydraulic bulging device characterized by comprising: 
 a pair of dies, and    shaft pressing tools also serving as sealing tools, in which front end portions of the tools are inserted into both ends of said dies, for holding said profile element pipe according to  claim 2  while sandwiching the profile element pipe with said dies,    wherein a filling hole for working liquid is provided at any one of said shaft pressing tools and parallel parts are provided on at least one end-portion inner surface of said dies and an outer surface of said shaft pressing tool corresponding to this end-portion inner surface, respectively.    
   
   
       6 . A hydraulic bulging device characterized by comprising: 
 a pair of dies, and    shaft pressing tools also serving as sealing tools, in which front end portions of the tools are inserted into both ends of said dies, for holding said profile element pipe according to  claim 3 , while sandwiching the profile element pipe with said dies,    wherein a filling hole for working liquid is provided at any one of said shaft pressing tools and parallel parts are provided on at least one end-portion inner surface of said dies and an outer surface of said shaft pressing tool corresponding to this end-portion inner surface, respectively.    
   
   
       7 . The hydraulic bulging device according to  claim 4 , wherein when an amount of shaft pressing on the small diameter side is defined as δL, an amount of shaft pressing on the large diameter side of is defined as δL′, a length necessary for sealing on the small diameter side is defined as L 0 , and a length necessary for sealing on the large diameter side is defined as L 0 ′, a length of a parallel part provided on the small diameter side of said die is δL+L 0  or more, a length of a parallel part provided on the large diameter side of said die is δL′+L 0 ′ or more, and a length of a parallel part provided on the small diameter side of the shaft pressing tool is δL+L 0  or more, and a length of a parallel part provided on the large diameter side of the shaft pressing tool is L 0 ′ or more.  
   
   
       8 . The hydraulic bulging device according to  claim 5 , wherein when an amount of shaft pressing on the small diameter side is defined as δL, an amount of shaft pressing on the large diameter side of is defined as δL′, a length necessary for sealing on the small diameter side is defined as L 0 , and a length necessary for sealing on the large diameter side is defined as L 0 ′, a length of a parallel part provided on the small diameter side of said die is δL+L 0  or more, a length of a parallel part provided on the large diameter side of said die is δL′+L 0 ′ or more, and a length of a parallel part provided on the small diameter side of the shaft pressing tool is δL+L 0  or more, and a length of a parallel part provided on the large diameter side of the shaft pressing tool is L 0 ′ or more.  
   
   
       9 . The hydraulic bulging device according to  claim 6 , wherein when an amount of shaft pressing on the small diameter side is defined as δL, an amount of shaft pressing on the large diameter side of is defined as δL′, a length necessary for sealing on the small diameter side is defined as L 0 , and a length necessary for sealing on the large diameter side is defined as L 0 ′, a length of a parallel part provided on the small diameter side of said die is δL+L 0  or more, a length of a parallel part provided on the large diameter side of said die is δL′+L 0 ′ or more, and a length of a parallel part provided on the small diameter side of the shaft pressing tool is δL+L 0  or more, and a length of a parallel part provided on the large diameter side of the shaft pressing tool is L 0 ′ or more.  
   
   
       10 . A hydraulic bulging method, wherein after producing a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof by using a hydraulic bulging device according to  claim 4 , said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.  
   
   
       11 . A hydraulic bulging method, wherein after producing a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof by using a hydraulic bulging device according to  claim 5 , said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.  
   
   
       12 . A hydraulic bulging method, wherein after producing a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof by using a hydraulic bulging device according to  claim 6 , said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.  
   
   
       13 . A bulged product wherein a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof is set in a die of a hydraulic bulging device according to  claim 4 , and said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.  
   
   
       14 . A bulged product wherein a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof is set in a die of a hydraulic bulging device according to  claim 5 , and said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.  
   
   
       15 . A bulged product wherein a profile element pipe having a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and having a parallel part formed on at least one end thereof is set in a die of a hydraulic bulging device according to  claim 6 , and said profile element pipe is subjected to hydraulic bulging combined with an internal pressure loading and a shaft pressing.