Method of forming a closed cross-sectional structure

Patent metadata

Field	Value
Publication number	US-10160031-B2
Application number	US-201715825953-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	May 28, 2012
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

A method of forming a closed cross-sectional structure press-forming the plate-shaped workpiece into portions corresponding to bottom portion and left and right side wall portions; and providing bend-facilitating lines at the plurality of bend lines; bending the workpiece in a direction that the portions corresponding to the left and right side wall portions approach each other by pressing a punch into a space between a pair of dies while clamping the portion corresponding to the bottom portion between the punch and a pad in a plate thickness direction; and bending the corresponding portions along the bend-facilitating lines by pressing the corresponding portions against an outer periphery of a plug having an outer peripheral shape the same as a final shape of the closed cross-sectional structure while the plug is placed on the portion of the workpiece corresponding to the bottom portion.

First claim

The invention claimed is:

1. A method of forming a closed cross-sectional structure by bending a plate-shaped workpiece at positions of a plurality of bend lines extending in a longitudinal direction, the structure including a bottom portion formed in a central part of the workpiece in a width direction and left and right side wall portions located on both sides of the bottom portion in the width direction, comprising:
a first step of:
press-forming the plate-shaped workpiece into a shape including portions corresponding to the bottom portion and the left and right side wall portions such that the plurality of bend lines are formed at boundaries therebetween; and
providing bend-facilitating lines at the plurality of bend lines;

a second step of bending the workpiece, which has been formed in the first step, in a direction that the portions corresponding to the left and right side wall portions approach each other; and
a third step of bending the portions corresponding to the bottom portion and the left and right side wall portions along the bend-facilitating lines by pressing the portions corresponding to the bottom portion and the left and right side wall portions against an outer periphery of a plug having an outer peripheral shape the same as a final shape of the closed cross-sectional structure while the plug is placed on the portion of the workpiece corresponding to the bottom portion, which has been formed in the second step, and wherein the plug is placed only on end portions in the longitudinal direction of the portion of the workpiece corresponding to the bottom portion.

2. The method according to claim 1 , wherein each of the bend-facilitating lines is a portion of the workpiece where a groove is formed in one surface thereof and a protrusion corresponding to the groove is formed on the other surface thereof, wherein a depth of the groove is greater than or equal to 0.05 times and less than or equal to 0.3 times a plate thickness of the workpiece and wherein a width of the groove is greater than or equal to 0.2 mm and less than or equal to 3.0 mm.

3. The method according to claim 1 , wherein:
the left and right side wall portions of the closed cross-sectional structure rise in a height direction;
in the first step, the plate-shaped workpiece is press-formed such that the portion corresponding to the bottom portion includes a first bottom portion and a second bottom portion that incline in a height direction toward one of the bend lines formed at the boundary therebetween; and
in the second step, clamping the portions corresponding to the bottom portion between the punch and the pad makes the first and second bottom portions incline in a direction opposite to the height direction toward the one of the bend lines.

4. The method according to claim 3 , wherein each of the bend-facilitating lines is a portion of the workpiece where a groove is formed in one surface thereof and a protrusion corresponding to the groove is formed on the other surface thereof, wherein a depth of the groove is greater than or equal to 0.05 times and less than or equal to 0.3 times a plate thickness of the workpiece and wherein a width of the groove is greater than or equal to 0.2 mm and less than or equal to 3.0 mm.

5. A method of forming a closed cross-sectional structure by bending a plate-shaped workpiece at positions of a plurality of bend lines extending in a longitudinal direction, the structure including a bottom portion formed in a central part of the workpiece in a width direction and left and right side wall portions located on both sides of the bottom portion in the width direction, comprising:
a first step of:
press-forming the plate-shaped workpiece into a shape including portions corresponding to the bottom portion and the left and right side wall portions such that the plurality of bend lines are formed at boundaries therebetween; and
providing bend-facilitating lines at the plurality of bend lines;

a second step of bending the workpiece, which has been formed in the first step, in a direction that the portions corresponding to the left and right side wall portions approach each other; and
a third step of bending the portions corresponding to the bottom portion and the left and right side wall portions along the bend-facilitating lines by pressing the portions corresponding to the bottom portion and the left and right side wall portions against an outer periphery of a plug having an outer peripheral shape the same as a final shape of the closed cross-sectional structure while the plug is placed only on end portions in the longitudinal direction of the portion of the workpiece corresponding to the bottom portion, which has been formed in the second step.

6. An apparatus that forms a closed cross-sectional structure by bending a plate-shaped workpiece at positions of a plurality of bend lines extending in a longitudinal direction, the structure including a bottom portion formed in a central part of the workpiece in a width direction and left and right side wall portions located on both sides of the bottom portion in the width direction, comprising:
a pressing die including an upper die and a lower die that press-forms the plate-shaped workpiece into a shape including portions corresponding to the bottom portion and the left and right side wall portions such that the plurality of bend lines are formed at boundaries therebetween and to provide bend-facilitating lines at the plurality of bend lines;
a bending die that bends the workpiece, which has been formed using the pressing die, in a direction that the portions corresponding to the left and right side wall portions approach each other by pressing a punch into a space between a pair of dies while clamping the portion corresponding to the bottom portion between the punch and a pad in a plate thickness direction; and
a final-closed-cross-section bending die including a plug, a pair of pressure cams and support pad, the plug having an outer peripheral shape the same as a final shape of the closed cross-sectional structure and disposed on the portion of the workpiece corresponding to the bottom portion, which has been formed using the bending die, the support pad supporting the portion of the workpiece corresponding to the bottom portion, the pair of pressure cams being disposed outside of the plug in the width direction, the final-closed-cross-section die bending the portions corresponding to the bottom portion and the left and right side wall portions along the bend-facilitating lines by pressing the portions corresponding to the bottom portion and the left and right side wall portions against an outer periphery of the plug using the support pad and the pair of pressure cams.

7. The apparatus according to claim 6 , wherein the plug is disposed only on end portions in the longitudinal direction of the portion of the workpiece corresponding to the . bottom portion.

Assignees

• Jfe Steel Corp

Inventors

• Higai Kazuhiko
• Shinmiya Toyohisa
• Yamasaki Yuji

Classifications

• B21D51/16

  characterised by the use of the objects (making heat exchangers B21D53/02) · CPC title

• B21D26/033

  Deforming tubular bodies (corrugating tubes by applying fluid pressure B21D15/03, B21D15/10) · CPC title

• B21D11/08

  Bending by altering the thickness of part of the cross-section of the work (B21D11/06 takes precedence) · CPC title

• B21D5/015 Primary

  for making tubes · CPC title

• B21D9/08

  in press brakes or between rams and anvils or abutments; Pliers with forming dies · CPC title