Laminated Core Bonding with Separated Pressing and Heating

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Solution Overview

Problem

The existing method for producing laminated cores results in the generation of compressive residual stress and increased iron loss due to concurrent pressurization and heating of iron core sheets.

Innovation Solution

A production apparatus and method that involves cutting core sheets from a steel strip with an adhesive layer, laterally pressurizing the outer peripheral portion using a first holding part, and heating the core sheets while being held in a separate second holding part, ensuring pressurization and heating occur at different stages to prevent adhesive softening and residual stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pressurization and heating of iron core sheets occur concurrently, then production efficiency is improved, but compressive residual stress is generated and iron loss increases

Engineering Contradiction:
Improveproduction efficiencyVSAvoidcompressive residual stress and iron loss
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent divides the holding part into a first holding part and a second holding part that are separate from each other. The first holding part applies lateral pressurization to the outer peripheral portion of core sheets, while the second holding part supports the core sheets during heating. This segmentation allows pressurization and heating to occur at different locations without interfering with each other, preventing the generation of compressive residual stress while maintaining production efficiency.

Inventive Principle:
Principle #1Segmentation

2Reliability

If lateral pressurization is applied to outer peripheral portion during heating, then adhesive softening is prevented, but device complexity increases

Engineering Contradiction:
Improveadhesive bonding qualityVSAvoidholding part structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The holding part is segmented into two independent parts: the first holding part that applies lateral pressurization and the second holding part that supports during heating. This segmentation enables the system to maintain adhesive bonding quality by preventing softening while keeping each component's function simple and well-defined.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first holding part acts as an intermediary that applies controlled lateral pressurization to the outer peripheral portion of core sheets during heating. This intermediary action prevents adhesive softening without requiring complex integrated systems, as the first holding part can be a simple pressurization mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach inhibits the generation of compressive residual stress and reduces iron loss in the laminated core, allowing for efficient adhesion without excessive pressure.

Implementation Method 1

heating the plurality of core sheets pressurized downward by the punch by the heating part while being held in the second holding part

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP4712120A1Apparatus and method for manufacturing laminated core
Publication Date: 2026.03.18 NIPPON STEEL CORPORATION
  • EP4712120A1 patent drawingFigure 1
  • EP4712120A1 patent drawingFigure 2
  • EP4712120A1 patent drawingFigure 3

AI summary

A production apparatus 100 includes a punch 12, a blanking die 14 arranged below the punch 12, a first holding part 16 arranged below the blanking die 14, a second holding part 18 arranged below the first holding part 16 and formed of a separate member from the first holding part 16, and a heating part 20 arranged around the second holding part 18 below the first holding part 16. A plurality of core sheets 1a is cut out from a steel strip 1 by the punch 12 and the blanking die 14, an outer peripheral portion of a plurality of core sheets 1a, which has been cut out, is pressurized laterally by the first holding part 16 and the plurality of core sheets 1a is pressurized downward by the punch 12, and the plurality of core sheets 1a pressurized downward by the punch 12 is heated by the heating part 20 while being held in the second holding part 18.