Jfe Steel Corporation

Jiro Hiramoto

Akinobu Ishiwatari

Masaki Urabe

Satoshi Sumikawa

Osamu Sonobe

Ryo Ageba

Hirotaka Kano

A press forming method according to the present invention includes: a first forming step of forming the press formed part by using the first press forming tool having a line length in the cross-sectional direction of the joining portion contacting with a flange portion subjected to stretch flange deformation or a flange portion subjected to shrink flange deformation is a line length Lin the cross-sectional direction that is shorter than a line length L, where the line length Lis a line length in a cross-sectional direction of the joining portion of the second press forming tool for making the product shape; and a second forming step of forming the press formed part in the product shape by crash forming by using the second press forming tool in which the line length in the cross-sectional direction of the joining portion is L

Press forming method and press forming tool

A press forming method for forming a press-formed product having no flange portion from a blank by performing a crash forming process while using a die and a punch, the press-formed product including at least a top portion and a side wall portion continued from the top portion via a connecting portion and being structured so that either all or a part of the side wall portion curves toward an outside of the press-formed product to form a convex shape in a planar view, the press forming method including forming the side wall portion while keeping a tip end portion of the blank in continuous contact with a side wall forming portion of the die and causing the die to impose no restraint on any part other than the tip end portion of the blank.

Press forming method and tool of press forming

A method of press forming includes: forming a trench-shaped portion into a product shape with a die and a punch until reaching a first bottom dead center, and forms at least one of: a flange portion subject to shrink flange deformation such that a linear length of the flange portion subject to the shrink flange deformation in a longitudinal direction is shorter than a linear length of a flange portion in the product shape; and a flange portion subject to stretch flange deformation such that a linear length of the flange portion subject to the stretch flange deformation in the longitudinal direction is longer than the linear length of the flange portion in the product shape; and forming the formed flange portion into the product shape with the die and a flange forming die until reaching a second bottom dead center.

Method of press forming and press forming apparatus

A method for manufacturing a press formed part, the method including specifying stretch flange limit strain in a metal sheet by using strain gradient in a radial direction and strain gradient in a sheet thickness direction. The strain gradient in the radial direction being directed from an end portion of the metal sheet at a time a press load is applied. The strain gradient in the sheet thickness direction being a direction of the metal sheet that intersects a loading direction. Additionally, the stretch flange limit strain satisfies the formula &#x3f5;=A[a&#xb7;&#x394;&#x3f5;/&#x394;r+b&#xb7;&#x394;&#x3f5;/&#x394;t]+c, where &#x3f5;represents the stretch flange limit strain in a tangential direction of the sheet edge, &#x394;&#x3f5;/&#x394;r represents the strain gradient in the radial direction, &#x394;&#x3f5;/&#x394;t represents the strain gradient in the sheet thickness direction, A, a, and b represent influence coefficients, and c represents the limit strain at a time the strain gradient is zero.

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Tokyo, Japan

Jiro Hiramoto