SURFACE-TREATED STEEL SHEET PART HAVING CUT END SURFACE, AND CUTTING METHOD THEREFOR

• US 20190321874A1
• Filed: 06/25/2019
• Published: 10/24/2019
• Est. Priority Date: 12/26/2016
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Nisshin Co., Ltd. (Nippon Steel Corporation)
• Inventors: SASAKI, Hirokazu, NAKAMURA, Naofumi, YAMAMOTO, Yudai
• Granted Patent: US 11,123,785 B2
• Time in Patent Office: Days
• CPC Class Codes: B21D 28/02 Punching blanks or articles with or without obtaining scrap cutting nails or pins from strips or sheet material B21G3/26; Notching
• CPC Class Codes: B21D 28/14 Dies ejecting or stripping-off devices arranged in punching machines or tools B21D45/00
• CPC Class Codes: B21D 35/007 Layered blanks B21D22/203 takes precedence; joining superposed plates B21D39/031, B21D39/034, B21D39/035
• CPC Class Codes: B26F 1/14 Punching tools; Punching dies
• CPC Class Codes: B32B 15/013 one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
• CPC Class Codes: B32B 2255/06 on metal layer
• CPC Class Codes: B32B 2255/205 Metallic coating
• CPC Class Codes: C22C 18/04 with aluminium as the next major constituent

Abstract

With regard to a part having a cut end surface using a surface-treated steel sheet as the source material, provided are a part for which the cut end surface has excellent durability, and a cutting method therefor. In this part that includes a cut end surface consisting of a surface-treated steel sheet that has been cut, the shape of the cut end surface is such that the length of a first shear droop occurring in the sheet thickness direction is at least 0.10 times the sheet thickness of the surface-treated steel sheet, and the length of a second sheer droop occurring in the planar direction is at least 0.45 times the sheet thickness of the surface-treated steel sheet. Furthermore, in the cutting process a die is used for which the clearance between the punch and the die is 1-20% of the plate thickness of the surface-treated steel plate, and the shoulder portion of the die and/or the punch is provided with a radius of curvature of at least 0.12 times the plate thickness of the surface-treated steel plate.

Claims

1. A part including a cut end-face of a surface treated steel sheet subjected to a cutting process and having excellent corrosion resistance at the cut end-face, wherein

the shape of the cut end-face is such that a first shear droop appearing in a sheet-thickness direction has a length 0.10 times or more of a sheet thickness of the surface treated steel sheet, and a second shear droop appearing in a planar direction has a length 0.45 times or more of the sheet thickness of the surface treated steel sheet, and

a surface of the cut end-face is coated and wrapped around with a plating metal layer, the plating metal layer being originally coated on a surface of the surface treated steel sheet.

2. The part having excellent corrosion resistance at a cut end-face according to claim 1, wherein the surface treated steel sheet is a Zn-based plated steel sheet.

3. A method of performing a cutting process of a surface treated steel sheet using a die apparatus comprising a die and a punch, the method including:

performing cutting using the die apparatus so that the shape of a cut end-face created by the cutting process is such that a first shear droop appearing in a sheet-thickness direction has a length 0.10 times or more of a sheet thickness of the surface treated steel sheet, and a second shear droop appearing in a planar direction has a length 0.45 times or more of the sheet thickness of the surface treated steel sheet,

the die apparatus being configured so that a clearance between the die and the punch is 1 to 20% of the sheet thickness of the surface treated steel sheet, and

a shoulder portion of either one of the die or the punch has a curvature radius 0.12 times or more of the sheet thickness of the surface treated steel sheet.

4. The method of performing a cutting process according to claim 3, wherein the surface treated steel sheet is a Zn-based plated steel sheet.