# US 2008/0184764 A1 · Press forming die set and method

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- Number: US 2008/0184764 A1
- Document ID: US20080184764A1
- Status: Published application
- Kind: A1
- Application number: 12/025,204
- Filed: 2008-02-04
- Published: 2008-08-07
- Earliest claimed: 2007-02-05
- Assignees: Honda Motor Co., Ltd.
- Inventors: Tsuyoshi Nakamura; Yasuhiko Kitano; Yoshimitsu Ishihara; Shingo Maeda
- Web page: https://patentgrep.com/patent/US20080184764A1

## CPC

- B21D 22/22: with devices for holding the edge of the blanks (B21D22/24 - B21D22/30 take precedence; shaping over a die without external former B21D11/02)
- B21D 25/04: Clamping arrangements
- 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 die set for press-forming a blank of thin metallic sheet. The die set has a punch and a blank holder. The blank holder has a first bead for restraining an edge of the blank with a constant force. The first bead is disposed further to an inside than a second bead for restraining the edge of the blank with a force that varies during pressing of the blank.

## Claims

### Claim 1

A die set for press-forming a blank, comprising:
a die having a concave part;
a punch disposed in confronting relation to the die and having a convex part for penetrating into the concave part; and
a blank holder disposed to surround the punch and having a first bead for restraining an edge of the blank with a constant force during pressing of the blank and a second bead, disposed further to an outside than the first bead, for restraining the blank edge with a force that varies during pressing of the blank.

### Claim 2

A method for press-forming a blank using a press-forming die set comprising: a die having a concave part; a punch disposed in confronting relation to the die and having a convex part for penetrating into the concave part; and a blank holder disposed to surround the punch and having a first bead for restraining an edge of the blank with a constant force during pressing of the blank and a second bead, disposed further to an outside than the first bead, for restraining the blank edge with a force that varies during pressing of the blank, the method comprising the steps of:
forming while restraining the blank using the second bead that is controlled to an intermediate restraining force which is sufficient to prevent wrinkling from occurring during forming of the blank;
forming while restraining the blank using the second bead that is controlled to a small restraining force which is smaller than the intermediate restraining force and that does not impede a flow of the blank into the concave part; and
forming while restraining the blank using the second bead that is controlled to a large restraining force which is larger than the intermediate restraining force and which inhibits the blank from flowing into the concave part.

### Claim 3

A die set for press-forming a blank, comprising:
a die having a concave part;
a punch disposed in confronting relation to the die and having a convex part for penetrating into the concave part;
a first blank holder disposed to surround the die and having a first bead for restraining an edge of the blank with a constant force during pressing of the blank and a first holder surface, disposed adjacent to the first bead, for supporting the blank edge;
a second blank holder disposed further to an outside than the first holder surface and having a second bead for restraining the blank edge with a force that varies during pressing of the blank and a second holder surface, disposed adjacent to the second bead, for supporting the blank edge; and
a pad, disposed on the die, for elastically pushing on the second holder surface via the blank.

### Claim 4 (depends on 3)

The die set of claim 3, wherein the second bead is provided in a position nearer the convex part than the second holder surface, at an edge of the second blank holder.