# US 11,298,739 B2 · Method for manufacturing iron core

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- Number: US 11,298,739 B2
- Document ID: US11298739B2
- Status: Granted
- Kind: B2
- Application number: 16/552,135
- Filed: 2019-08-27
- Published: 2020-03-26
- Granted: 2022-04-12
- Earliest claimed: 2018-09-20
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Kenta Shikii; Hiroshi Ishikura
- Web page: https://patentgrep.com/patent/US11298739B2

## CPC

- B21D 28/22: Notching the peripheries of circular blanks, e.g. laminations for dynamo-electric machines
- B21D 24/02: Die-cushions
- B21D 35/007: {Layered blanks (B21D22/203 takes precedence; joining superposed plates B21D39/031, B21D39/034, B21D39/035)}
- B21D 37/16: Heating or cooling
- H02K 15/02: of stator or rotor bodies
- B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F)
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

Provided is a method for manufacturing an iron core that enables reduction of variations in dimension of a plurality of metal plates that occur during pressing of the laminate of these metal plates. The method includes: a laminate preparation step of stacking a plurality of metal plates to prepare a laminate; a pressing step of giving a temperature gradient to the laminate and pressing the laminate with a pressing machine having a punch and a die; and a temperature-gradient removal step of removing the temperature gradient from the laminate. The pressing step gives the temperature gradient to the laminate so that the temperature rises from the punch-side to the die-side in the stacking direction of the laminate.

## Claims

### Claim 1

A method for manufacturing an iron core operatively associated with a press device comprising a punch and a die, comprising steps of:
a laminate preparation step of stacking a plurality of metal plates for iron core to prepare a laminate;
a pressing step of giving a temperature gradient to the laminate and pressing the laminate with the punch device; and
a temperature-gradient removal step of removing the temperature gradient from the laminate,
wherein
the pressing step gives the temperature gradient to the laminate so that a temperature rises from a part close to the punch to a part close to the die in a stacking direction of the laminate.

### Claim 2 (depends on 1)

The method for manufacturing the iron core according to claim 1, wherein the metal plates for iron core include amorphous metal.

### Claim 3 (depends on 1)

The method for manufacturing the iron core according to claim 1, wherein the die includes a heater, and
the pressing step gives the temperature gradient to the laminate with the heater.

### Claim 4 (depends on 1)

The method for manufacturing the iron core according to claim 1, wherein the temperature gradient is controlled based on a linear expansion coefficient of the metal plates for iron core and a contact area between the metal plate for iron core and an upper face of the die.

### Claim 5 (depends on 1)

The method for manufacturing the iron core according to claim 1, wherein the temperature-gradient removal step returns a temperature of the laminate to a room temperature.