# US 10,500,624 B2 · Press forming method and tool of press forming

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- Number: US 10,500,624 B2
- Document ID: US10500624B2
- Status: Granted
- Kind: B2
- Application number: 15/552,615
- Filed: 2016-01-27
- Published: 2018-01-25
- Granted: 2019-12-10
- Earliest claimed: 2015-03-18
- Assignees: Jfe Steel Corporation
- Applicants: Jfe Steel Corporation
- Inventors: Ryo Ageba; Akinobu Ishiwatari; Jiro Hiramoto
- Web page: https://patentgrep.com/patent/US10500624B2

## CPC

- B21D 19/08: by single or successive action of pressing tools, e.g. vice jaws
- B21D 22/02: Stamping using rigid devices or tools
- B21D 22/20: Deep-drawing (special deep-drawing arrangements in, or in connection with, presses B21D24/00)
- B21D 22/21: without fixing the border of the blank
- B21D 22/30: to finish articles formed by deep-drawing
- B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F)

## Abstract

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.

## Claims

### Claim 1

A tool of press forming for forming a press-formed product having no flange portion, 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 the press-formed product 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 tool of press forming comprising:
a punch that has: (i) a forming top portion that is configured to support a blank, (ii) a punch shoulder portion that is continued from the forming top portion and that is configured to extend along a curvature of the press-formed product, and (iii) a forming wall portion continued from the punch shoulder portion; and
a die that has a side wall forming portion that is configured to form the side wall portion of the press-formed product by moving the die relative to the punch,
wherein:
in an X-Y coordinate system in which an origin is a point serving as a center of a radius curvature of a curvature on the forming top portion: (i) an X-axis corresponds to a horizontal direction, (ii) a Y-axis corresponds to a vertical direction, (iii) an optimal curve is a curve drawn by a formula presented below, and (iv) an optimal inclination angle is an inclination angle of a tangential line of the optimal curve at an arbitrary X-coordinate position,
the side wall forming portion of the die has a cross-sectional shape expressed with a curve where an inclination angle of a tangential line at the arbitrary X-coordinate position with respect to the horizontal direction is equal to or greater than the optimal inclination angle, and
the formula of the optimal curve is:
X
=
pr
-
R
+
(
R
+
t
)
⁢
sin
⁢
⁢
θ
+
{
br
-
(
pr
-
R
)
-
(
R
+
t
2
)
⁢
θ
}
⁢
cos
⁢
⁢
θ
Y
=
-
∫
0
θ
⁢
[
t
2
⁢
sin
⁢
⁢
θ
-
{
br
-
(
pr
-
R
)
-
(
R
+
t
2
)
⁢
θ
}
⁢
sin
⁢
⁢
θtan
⁢
⁢
θ
]
⁢
d
⁢
⁢
θ
⁢
}
where:
pr: a radius [mm] of the punch;
R: a radius curvature [mm] of the punch shoulder portion;
br: a radius [mm] of the blank;
t: a thickness [mm] of the blank; and
θ: a contact angle (0≤θ≤π/2) [rad] of the blank with respect to the punch shoulder portion.