Shearing method

Patent metadata

Field	Value
Publication number	US-10639698-B2
Application number	US-201615552552-A
Country	US
Kind code	B2
Filing date	Feb 25, 2016
Priority date	Feb 25, 2015
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

Provided is a steel material shearing method that enables highly productive and low-cost production of a steel material with a sheared surface having excellent hydrogen embrittlement resistance, fatigue strength, and stretch flangeability. The shearing method comprises making a clearance between a die and a punch 5 to 80% of a sheet thickness of a workpiece, shearing the workpiece using the punch, and, by utilizing a punched material punched out by the punch, pressing an end face of the punched out material against the sheared surface of the worked material on the die to produce a steel sheet with a sheared edge having excellent hydrogen embrittlement resistance and fatigue strength.

First claim

The invention claimed is:

1. A shearing method in which a workpiece having a first surface and a second surface on an opposite side of the first surface is arranged on a die so that the second surface is arranged at a die side and the workpiece is sheared from the first surface toward the second surface in a sheet thickness direction of the workpiece by a punch arranged at the first surface side, wherein the shearing method comprises:
(A) a clearance setting process of snaking a clearance between the die and the punch in a direction perpendicular to the sheet thickness direction of the workpiece which is set between 5% to 80% of the sheet thickness of the workpiece,
(B) a shearing process of using the punch to shear the workpiece to obtain a punched out material and a worked material having a punched hole, wherein the punched out material and the worked material respectively have a first surface and a second surface corresponding to the first surface and the second surface of the workpiece, and
(C) a pushing process of using a pushing punch arranged at the second surface side of the worked material so as to be opposed to the punch, and pushing the second surface of the punched out material towards the punched hole of the worked material created in the workpiece in the shearing process so that the punched out material is pushed against a sheared edge of the worked material, wherein
the die, the punch, and the pushing punch are arranged so that the punch and the pushing punch are disposed at a peripheral side of the workpiece, and the die is disposed at an inner side relative to the punch and the pushing punch of the workpiece,
an additional punch is linked to the punch so that the additional punch is disposed at the first surface side of the workpiece at a further peripheral side from the punch,
an additional pushing punch is linked to the pushing punch so that the additional pushing punch is disposed at the second surface side of the workpiece and opposed to the additional punch across the workpiece,
at least one of a punching surface of the additional punch and a pushing surface of the additional pushing punch has a projecting part, and
the shearing process and the pushing process are conducted while the workpiece is gripped and fastened between the punching surfaces of the punch and the additional punch and the pushing surfaces of the pushing punch and the additional pushing punch.

2. The shearing method according to claim 1 , wherein, in the process (A), the clearance between the die and the punch is set between 10% to 30% of the sheet thickness.

3. The shearing method according to claim 1 , wherein, in the process (C), the punched out material is pushed to a position where the second surface of the punched out material does not pass the first surface of the worked material, so as to coin the sheared edge of the worked material.

4. The shearing method according to claim 1 , wherein the workpiece is a metal sheet having a 980 MPa class or more tensile strength.

5. The shearing method according to claim 1 , wherein the workpiece is a steel material.

6. A shearing method in which a workpiece having a first surface and a second surface on an opposite side of the first surface is arranged between a die provided on a side of the second surface and a holder provided on a side of the first surface and the workpiece is sheared from the first surface toward the second surface in a sheet thickness direction of the workpiece by a punch arranged at the first surface side while the die and the holder are fastening the workpiece, wherein the shearing method comprises:
(A) a clearance setting process of making a clearance between the die and the punch in a direction perpendicular to the sheet thickness direction of the workpiece which is set between 5% to 80% of the sheet thickness of the workpiece,
(B) a shearing process of using the punch to shear the workpiece to obtain a punched out material and a worked material having a punched hole, wherein the punched out material and the worked material respectively have a first surface and a second surface corresponding to the first surface and the second surface of the workpiece, and
(C) a pushing process of using a pushing punch arranged at the second surface side of the worked material so as to be opposed to the punch, and pushing the second surface of the punched out material towards the punched hole of the worked material created in the workpiece during the shearing process so that the punched out material is pushed against a sheared edge of the worked material, wherein:
the die, the punch, and the pushing punch are arranged so that the punch and the pushing punch are disposed at a peripheral side of the workpiece, and the die is disposed at an inner side relative to the punch and the pushing punch of the workpiece,
an additional holder is arranged at the first surface side of the workpiece at a further peripheral side from the punch,
an additional die is arranged at the second surface side of the workpiece at a further peripheral side from the pushing punch so as to be opposed to the additional holder across the workpiece,
at least one of a fastening surface of the additional holder facing the first surface of the workpiece and a fastening surface of the additional die facing the second surface of the workpiece has a projecting part, and
the shearing and the pushing are conducted while the workpiece is gripped and fastened between the fastening surface of the additional holder and the fastening surface of the additional die.

7. The shearing method according to claim 6 , wherein, in the process (A), the clearance between the die and the punch is set between 10% to 30% of the sheet thickness.

8. The shearing method according to claim 6 , wherein, in the process (C), the punched out material is pushed to a position where the second surface of the punched out material does not pass the first surface of the worked material, so as to coin the sheared edge of the worked material.

9. The shearing method according to claim 6 , wherein the workpiece is a metal sheet having a 980 MPa class or more tensile strength.

10. The shearing method according to claim 6 , wherein the workpiece is a steel material.

11. A shearing method in which a workpiece having a first surface and a second surface on an opposite side of the first surface arranged on a die so that the second surface is arranged at a die side and the workpiece is sheared from the first surface toward the second surface in a sheet thickness direction of the workpiece by a punch arranged at the first surface side, wherein the shearing method comprises:
(A) a clearance setting process of making a clearance between the die and the punch in a direction perpendicular to the sheet thickness direction of the workpiece which is set between 5% to 80% of the sheet thickness of the workpiece,
(B) a shearing process of using the punch to shear the workpiece to obtain a punched out material and a worked material having munched hole, wherein the punched out material and the worked material respectively have a first surface and a second surface corresponding to the first surface and the second surface of the workpiece, and
(C) a pushing process of using a pushing punch arranged at the second surface side of the worked material so as to be opposed to the punch, and pushing the second surface of the punched out material towards the punched hole of the worked material created in the workpiece during the shearing process so that the punched out material is pushed against a sheared edge of the worked material, wherein
the die, the punch, and the pushing punch are arranged so that the punch and the pushing punch are disposed at a

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Nippon Steel Corp

Inventors

• Yasutomi Takashi
• Matsuno Takashi
• Yonemura Shigeru
• Yoshida Tohru

Classifications

• B21D28/16 Primary

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

• B21D28/14 Primary

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