Shearing method

• US 10,639,698 B2
• Filed: 02/25/2016
• Issued: 05/05/2020
• Est. Priority Date: 02/25/2015
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Yasutomi, Takashi, Matsuno, Takashi, Yonemura, Shigeru, Yoshida, Tohru
• Primary Examiner(s): Sullivan, Debra M
• Assistant Examiner(s): Kresse, Matthew
• Application Number:
  US15/552,552
• Publication Number:
  US 20180333760A1
• Time in Patent Office: 1,531 Days
• Field of Search: 83514, 83515, 83517, 83518, 83618-622, 83670, 83681, 83682, 83684-686
• CPC Class Codes: B21D 28/14 Dies ejecting or stripping-off devices arranged in punching machines or tools B21D45/00
• CPC Class Codes: B21D 28/16 Shoulder or burr prevention , e.g. fine-blanking

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.

Claims

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 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 arranged at the first surface side of the workpiece at a further peripheral side from the punch,

the workpiece is sheared at a clearance between the additional punch and the pushing punch by moving the additional punch relative to the pushing punch to obtain a burnished surface, and

the clearance setting, the shearing and the pushing are conducted while the burnished surface is being constrained by the additional punch.

12. The shearing method according to claim 11, wherein, in the process (A), the clearance between the die and the punch is set between 10% to 30% of the sheet thickness.

13. The shearing method according to claim 11, 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.

14. The shearing method according to claim 11, wherein the workpiece is a metal sheet having a 980 MPa class or more tensile strength.

15. The shearing method according to claim 11, wherein the workpiece is a steel material.

16. 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 making a clearance between the die and the punch in 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, 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 a punched out portion of the worked material created in the workpiece during the shearing process so that the lunched 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 die is arranged at the second surface side of the workpiece at a further peripheral side from the pushing punch,

the workpiece is sheared at a clearance between the punch and the additional die by moving the additional die relative to the punch to obtain a burnished surface, and

the clearance setting, the shearing and the pushing are conducted while the burnished surface is being constrained by the additional die.

17. The shearing method according to claim 16, wherein, in the process (A), the clearance between the die and the punch is set between 10% to 30% of the sheet thickness.

18. The shearing method according to claim 16, 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.

19. The shearing method according to claim 16, wherein the workpiece is a metal sheet having a 980 MPa class or more tensile strength.

20. The shearing method according to claim 16, wherein the workpiece is a steel material.

21. 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, 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 a punched out portion 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 on 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,

the workpiece is sheared at a clearance between the punch and the additional die by moving the additional die relative to the punch to obtain a burnished surface, and

the clearance setting, the shearing and the pushing are conducted while the burnished surface is being constrained by the additional die or the additional holder.

22. The shearing method according to claim 21, wherein, in the process (A), the clearance between the die and the punch is set between 10% to 30% of the sheet thickness.

23. The shearing method according to claim 21, 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.

24. The shearing method according to claim 21, wherein the workpiece is a metal sheet having a 980 MPa class or more tensile strength.

25. The shearing method according to claim 21, wherein the workpiece is a steel material.