Method and a device for manufacturing of a closed profile and a profile manufactured according to said method

Abstract

The invention relates to a method and device for manufacturing a closed profile in a profile structure and a closed profile manufactured according to the method. The closed profile used and constituted by a metal material of iron, alloyed with chromium, nickel and carbon in predetermined proportions is plastically formed, wherein a strong strain hardening of the closed profile is obtained.

1 . A method of manufacturing a closed profile in a profile structure, characterised by alloying the closed profile, which is constituted by a metal material of iron, with chromium, nickel and carbon in predetermined proportions and then plastically forming the closed profile to provide a strong strain hardening thereof.  
     
     
         2 . A method according to  claim 1 , characterised in that the metal material of iron in the form of the closed profile, which is plastically worked, is alloyed with 17% chromium, 7% nickel and 0.1% carbon or closely related alloys.  
     
     
         3 . A method according to  claim 1 , characterised in that the alloyed metal material forming the profile is formed through hydroforming and/or through ballooning preferably by means of a mandrel with a suitable shape or through shrinking preferably through axial elongation with or without a matrix to increase the yield point of the metal material from an original low yield point to a final product that completely or partially obtains a high yield point.  
     
     
         4 . A method according to  claim 3 , characterised in that the original low yield point amounts to about 300 MPa and the higher yield point is preferably equal to or amounts to more than 1000 MPa.  
     
     
         5 . A method according to  claim 1 , characterised in that the wall thickness of the final closed profile is varied axially by applying two or more profiles partially into each other with the shorter profiles external on the longer profiles, by joining profiles having different wall thickness and/or different diameter through welding before the forming operation, or by varying the wall thickness in the same-cross section to achieve a strategic position of the profiled material and optimisation of the strength.  
     
     
         6 . A method according to  claim 1  or  5 , characterised in that the strength of the final profile is varied in different portions of the profile by partially more or less extending the material.  
     
     
         7 . A method according to any of the preceding claims, characterised in that the material in the profile is cooled to or is kept at a controlled temperature before and during the forming operation to achieve a controlled, maximal strength independently of the degree of deformation during the forming operation.  
     
     
         8 . A method according to any of the preceding claims, characterised in that the temperature that the material is cooled to or the temperature that is maintained during the forming operation is about −196°≦T≦70° C.  
     
     
         9 . A method according to any of the preceding claims, characterised in that the final product is cooled to or is kept at a controlled temperature for achieving a controlled maximal strength independently of the degree of deformation during the forming operation.  
     
     
         10 . A method according to  claim 9 , characterised in that the temperature at which the final product is cooled or the temperature that is maintained during a limited time after the forming operation is about −196°≦T≦70° C.  
     
     
         11 . A tool for manufacturing a closed profile according to any of the preceding claims, characterised in that the tool comprises forming means providing a varying wall thickness within one and the same-cross section of the profile.  
     
     
         12 . A closed profile manufactured according to any of claims  1 - 10 , characterised in that it is formed by hydroforming and/or mechanically formed to a yield point close to or more than 1000 MPa, has a strategically varying wall thickness axially and/or in the cross-section of the profile and is optimised in weight with respect to strength and/or deformation.