Punching method, punching device, and method for manufacturing laminated iron core

Patent metadata

Field	Value
Publication number	US-10919081-B2
Application number	US-201615543077-A
Country	US
Kind code	B2
Filing date	Jan 7, 2016
Priority date	Jan 14, 2015
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

A punching method includes: punching out a plurality of electrical steel sheets in a stacked state by a mold, wherein sheet thicknesses of the electrical steel sheets are set to be 0.35 mm or less, a Vickers hardness (test force 1 kg) of the sheets is set to be 150 to 400, and an average crystal grain size of the sheets is set to be 50 to 250 μm, a clearance of the mold is set to be 7% or more of a minimum sheet thickness of the sheet thicknesses of the electrical steel sheets and equal to or lower than 7% of a total sheet thickness of the electrical steel sheets, and a pressure that a sheet presser of the mold applies to the electrical steel sheets is set to be 0.10 MPa or more.

First claim

The invention claimed is:

1. A punching method comprising:
punching out a plurality of electrical steel sheets in a stacked state by a mold, the mold including a punch, a die and a sheet presser; and
pressing the electrical steel sheets with the sheet presser when punching out the electrical steel sheets, wherein
a sheet thickness of each of the electrical steel sheets is set to be 0.35 mm or less, a Vickers hardness (test force 1 kg) of the sheets is set to be 150 to 400, and an average crystal grain size of the sheets is set to be 50 to 250 μm,
a clearance between the punch and the die, is set to be 7% or more of a minimum sheet thickness of the sheet thicknesses of the electrical steel sheets and 7% or less of a total sheet thickness of the electrical steel sheets, and
a pressure that the sheet presser of the mold applies to the electrical steel sheets is set to be 0.10 MPa or more.

2. The punching method according to claim 1 , wherein the sheet thickness of each of the electrical steel sheets is set to be 0.25 mm or less.

3. The punching method according to claim 1 , wherein the electrical steel sheets contain Si of 0.5 to 6.6%, Al of equal to or lower than 2.5%, and Mn of 0.1 to 3.0% in terms of mass ratio, and the number of inclusions having a grain size of 0.1 to 3.0 in steel is set to be in a range of 1000 to 8000 pieces/mm 2 .

4. The punching method according to claim 1 , wherein a static friction coefficient between surfaces of the stacked electrical steel sheets is set to be 0.3 or more, and static friction coefficients between the electrical steel sheets and a surface of a die plate of the mold that makes contact with the electrical steel sheets and between the electrical steel sheets and a surface of the sheet presser of the mold are set to be 0.3 to 0.8.

5. The punching method according to claim 4 , wherein the electrical steel sheets contain Si of 0.5 to 6.6%, Al of equal to or lower than 2.5%, and Mn of 0.1 to 3.0% in terms of mass ratio, and the number of inclusions having a grain size of 0.1 to 3.0 μm in steel is set to be in a range of 1000 to 8000 pieces/mm 2 .

6. The punching method according to claim 2 , wherein the electrical steel sheets contain Si of 0.5 to 6.6%, Al of equal to or lower than 2.5%, and Mn of 0.1 to 3.0% in terms of mass ratio, and the number of inclusions having a grain size of 0.1 to 3.0 μm in steel is set to be in a range of 1000 to 8000 pieces/mm 2 .

7. The punching method according to claim 2 , wherein a static friction coefficient between surfaces of the stacked electrical steel sheets is set to be 0.3 or more, and static friction coefficients between the electrical steel sheets and a surface of a die plate of the mold that makes contact with the electrical steel sheets and between the electrical steel sheets and a surface of the sheet presser of the mold are set to be 0.3 to 0.8.

8. The punching method according to claim 7 , wherein the electrical steel sheets contain Si of 0.5 to 6.6%, Al of equal to or lower than 2.5%, and Mn of 0.1 to 3.0% in terms of mass ratio, and the number of inclusions having a grain size of 0.1 to 3.0 μm in steel is set to be in a range of 1000 to 8000 pieces/mm 2 .

Assignees

• Jfe Steel Corp

Inventors

• Senda Kunihiro
• Uesaka Masanori
• Oda Yoshihiko

Classifications

• B21D28/00 Primary

  Shaping by press-cutting; Perforating · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title

• B21D28/22

  Notching the peripheries of circular blanks, e.g. laminations for dynamo-electric machines · CPC title

• B21D35/005

  characterized by the material of the blank or the workpiece (B21D26/053 takes precedence) · CPC title

• B21D35/007

  Layered blanks (B21D22/203 takes precedence; joining superposed plates B21D39/031, B21D39/034, B21D39/035) · CPC title