Blank, formed article, die assembly, and method for producing blank

Patent metadata

Field	Value
Publication number	US-2017320122-A1
Application number	US-201415533737-A
Country	US
Kind code	A1
Filing date	Dec 10, 2014
Priority date	Dec 10, 2014
Publication date	Nov 9, 2017
Grant date	—

Abstract

A sheet-shaped blank ( 10 ) for press forming is produced by shearing a metal sheet ( 30 ). The blank ( 10 ) includes a sheared edge ( 14 ), which includes a sheared surface ( 14 b ) and a fractured surface ( 14 c ) in the sheet thickness direction and has a loop shape in plan view. In plan view, an edge of the sheared edge ( 14 ) includes concavely curved portions ( 20 ). The average of lengths of the fractured surface ( 14 c ) in the sheet thickness direction in the curved portions ( 20 ) is greater than the average of lengths of the fractured surface ( 14 c ) in the sheet thickness direction over the entire perimeter of the sheared edge ( 14 ).

First claim

1 . A sheet-shaped blank for press forming produced by shearing a metal sheet, the blank comprising:
a sheared edge comprising, in a sheet thickness direction, a sheared surface and a fractured surface, wherein the sheared edge has a loop shape in plan view, the sheared edge has an edge comprising, in plan view, a curved portion that is concavely curved, and an average of lengths of the fractured surface in the sheet thickness direction in the curved portion is greater than an average of lengths of the fractured surface in the sheet thickness direction over an entire perimeter of the sheared edge.

2 . The blank according to claim 1 , wherein, provided that a reference point of the curved portion is defined as a midpoint of the curved portion in a perimeter direction of the sheared edge or a point where a curvature of the curved portion in plan view is greatest, an average of lengths of the fractured surface in the sheet thickness direction within a region, which extends a predetermined length in the perimeter direction with the reference point as a center, is greater than the average of lengths of the fractured surface in the sheet thickness direction over the entire perimeter of the sheared edge.

3 . The blank according to claim 2 , wherein the average of lengths of the fractured surface in the sheet thickness direction within the region of the predetermined length is greater by 10% or more of the sheet thickness than the average of lengths of the fractured surface in the sheet thickness direction over the entire perimeter of the sheared edge.

4 . The blank according to claim 2 ,
wherein the sheared edge further comprises a shear droop portion positioned opposite from the fractured surface in the sheet thickness direction with the sheared surface interposed therebetween, and wherein an average of lengths of the shear droop portion in the sheet thickness direction within the region of the predetermined length is 20% or less of the sheet thickness.

5 . The blank according to claim 2 , wherein the predetermined length is a length of 50% of the sheet thickness of the blank.

6 . The blank according to claim 2 , wherein the predetermined length is a length of 2000% of the sheet thickness.

7 . The blank according to claim 2 , wherein the region of the predetermined length is a region where a curvature is 5 m −1 or more.

8 . The blank according to claim 1 , wherein
the metal sheet comprises a hole formed by punching, and the sheared edge is formed along an edge of the hole.

9 . The blank according to claim 1 , wherein
the metal sheet has an outer perimeter edge formed by blanking, and the sheared edge is formed along the outer perimeter edge.

10 . The blank according to claim 1 , wherein the curved portion is configured to stretch and deform during press forming.

11 . A formed article produced by subjecting the blank according to claim 1 to press forming.

12 . A die assembly comprising:
a columnar punch; and a hollow die configured to receive the punch, the die assembly being configured to shear a metal sheet placed on the die by moving the punch in a predetermined direction, the punch comprising a bottom surface and an outer perimeter surface, the bottom surface comprising a cutting edge constituted by an outer perimeter edge of the bottom surface, the outer perimeter surface extending from the outer perimeter edge in a direction parallel to the predetermined direction, the outer perimeter edge comprising, in plan view, a curved portion that is convexly curved or concavely curved, the bottom surface comprising a planar portion and a cutout portion recessed with respect to the planar portion in the predetermined direction and configured to comprise the curved portion in plan view.

13 . A die assembly comprising:
a columnar punch; and a hollow die configured to receive the punch, the die assembly being configured to shear a metal sheet placed on the die by moving the punch in a predetermined direction, the die comprising a hollow support surface and an inner perimeter surface, the support surface being configured to support the metal sheet and comprising a cutting edge constituted by an inner perimeter edge of the die, the inner perimeter surface extending from the inner perimeter edge in a direction parallel to the predetermined direction, the inner perimeter edge comprising, in plan view, a curved portion that is convexly curved or concavely curved, the support surface comprising a planar portion and a cutout portion recessed with respect to the planar portion in the predetermined direction and configured to comprise the curved portion in plan view.

14 . The die assembly according to claim 12 , wherein a cutout depth of the cutout portion in a direction parallel to the predetermined direction is 0.1 times or more a sheet thickness of the metal sheet and 0.7 times or less the sheet thickness.

15 . A method for producing a blank for press forming, the method using the die assembly according to claim 12 , the method comprising the steps of:
placing a metal sheet on the die of the die assembly, and shearing the metal sheet on the die using the punch of the die assembly.

16 . A method for producing a blank comprising:
a sheared edge comprising, in a sheet thickness direction, a sheared surface and a fractured surface, wherein the sheared edge has a loop shape in plan view, the sheared edge has an edge comprising, in plan view, a curved portion that is concavely curved, and an average of lengths of the fractured surface in the sheet thickness direction in the curved portion is greater than an average of lengths of the fractured surface in the sheet thickness direction over an entire perimeter of the sheared edge, the method using the die assembly according to claim 12 , the method comprising the steps of: placing a metal sheet on the die of the die assembly, and shearing the metal sheet on the die using the punch of the die assembly, wherein, in the step of shearing, at least a portion of the curved portion of the blank is formed by cutting a portion of the metal sheet via the cutout portion of the punch or the cutout portion of the die.

17 . The die assembly according to claim 13 , wherein a cutout depth of the cutout portion in a direction parallel to the predetermined direction is 0.1 times or more a sheet thickness of the metal sheet and 0.7 times or less the sheet thickness.

18 . A method for producing a blank for press forming, the method using the die assembly according to claim 13 , the method comprising the steps of:
placing a metal sheet on the die of the die assembly, and shearing the metal sheet on the die using the punch of the die assembly.

19 . A method for producing a blank comprising:
a sheared edge comprising, in a sheet thickness direction, a sheared surface and a fractured surface, wherein the sheared edge has a loop shape in plan view, the sheared edge has an edge comprising, in plan view, a curved portion that is concavely curved, and an average of lengths of the fractured surface in the sheet thickness direction in the curved portion is greater than an average of lengths of the fractured surface in the sheet thickness direction over an entire perimeter of the sheared edge, the method using the die assembly according to claim 13 , the method comprising the steps of: placing a metal sheet on the die of the die assembly, and shearing the metal sheet on the die using the punch of the die assembly, wherein, in the step of shearing, at least a portion

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Matsuno Takashi
• Egami Akira

Classifications

• B21D28/16 Primary

  Shoulder or burr prevention {, e.g. fine-blanking} · CPC title

• B21D28/26 Primary

  in sheets or flat parts · CPC title

• B21D28/34 Primary

  Perforating tools; Die holders · CPC title

• B21D35/001

  Shaping combined with punching, e.g. stamping and perforating · CPC title

• B21D28/14

  Dies (ejecting or stripping-off devices arranged in punching machines or tools B21D45/00) · CPC title