Laminated Iron Core Feeding for Stable Multi-Strip Punching

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Solution Overview

Problem

The conventional manufacturing process of laminated iron cores faces challenges with thin sheet thickness, where the base steel strips tend to droop inside the die, leading to instability and shifting during the punching process, which disrupts continuous production and increases the risk of collisions with the die's inner wall.

Innovation Solution

The implementation of a laminated iron core manufacturing method using a pair of upper and lower feed rolls with a surface roughness of 0.3 µm or more and an upper-and-lower-roll drive system, combined with a shift correction mechanism installed within 700 mm from the biting position, to prevent width direction shifting by ensuring synchronized and uniform feeding force transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a plurality of base steel strips are superposed and fed into the die simultaneously, then productivity is improved, but the base steel strip droops inside the die causing instability and shifting

Engineering Contradiction:
Improvepunching efficiencyVSAvoidbase steel strip stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The base steel strips are joined together before being fed into the die for punching. This preliminary joining action prevents the strips from drooping and shifting during the punching process, maintaining stability while enabling multi-strip simultaneous processing for high productivity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Multiple base steel strips are joined together to form a combined structure that maintains rigidity and stability during feeding and punching. The joining merges the strips into a single stable unit that can be processed simultaneously without individual strip deformation

Inventive Principle:
Principle #5Merging (Combining)

2Strength

If the base steel strips are joined together before punching, then rigidity is improved preventing droop, but shifting in width direction may occur during feeding

Engineering Contradiction:
Improvebase steel strip rigidityVSAvoidwidth direction positioning accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The surface roughness of the feed rolls is specifically controlled to be 0.3 µm or more. This parameter change in surface roughness increases friction between the rolls and steel strips, preventing width direction shifting during high-speed feeding while maintaining the rigidity benefits of joined strips

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The feed rolls are designed with specific surface roughness characteristics that provide friction-based feedback control. This friction prevents lateral shifting of the joined strips during feeding, automatically maintaining width direction positioning accuracy without additional active control systems

Inventive Principle:
Principle #23Feedback

3Force

If the surface roughness of feed rolls is increased to 0.3 µm or more, then friction is improved preventing strip shifting, but unevenness on steel strip surface increases

Engineering Contradiction:
Improvefriction forceVSAvoidsteel strip surface uniformity
Core Design Contradiction:
ForceVSShape

Solution Approach 1:

The surface roughness is optimized to a specific range (0.3 µm or more) that provides sufficient friction force to prevent shifting during high-speed feeding, while the controlled roughness level is managed to minimize excessive surface unevenness on the steel strips

Inventive Principle:
Principle #35Parameter changes

4Productivity

If high-speed feeding is implemented for continuous punching, then productivity increases, but the risk of collision with die inner wall increases due to shifting

Engineering Contradiction:
Improvecontinuous punching speedVSAvoidcollision-free operation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The base steel strips are joined together before high-speed feeding into the die. This preliminary joining prevents width direction shifting that would cause collision with the die inner wall, enabling reliable continuous punching at high speeds without operational interruptions

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The feed rolls with specific surface roughness act as an intermediary that controls the friction between the joined steel strips and the feeding mechanism. This intermediary friction control prevents lateral shifting during high-speed feeding, ensuring collision-free operation while maintaining high productivity

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 allows for stable and continuous punching of laminated iron cores by preventing base steel strip shifting, enhancing the rigidity and positional accuracy, thereby increasing production efficiency and reducing the likelihood of mechanical issues during high-speed feeding.

Implementation Method 1

a pair of upper and lower feed rolls with a surface roughness of 0.3 µm or more and an upper-and-lower-roll drive system, combined with a shift correction mechanism installed within 700 mm from the biting position, to prevent width direction shifting by ensuring synchronized and uniform feeding force transmission

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3427856B1Method and device for manufacturing laminated iron core
Publication Date: 2023.09.20 JFE STEEL CORP
  • EP3427856B1 patent drawingFigure 1~2
  • EP3427856B1 patent drawingFigure 3~4\

AI summary

A laminated iron core manufacturing method for manufacturing a laminated iron core by inserting a plurality of electrical steel strips in a superposed state to a pair of upper and lower feed rolls such that the electrical steel strips in a superposed state are fed into a die having a plurality of punching processes in sequence, and by simultaneously punching the electrical steel strips in a superposed state in the die. The method performs joining a part or all of the superposed electrical steel strips 1a and 1b together before entering the die or at an upstream stage portion of the die, after the electrical steel strips 1a and 1b are fed out from the pair of upper and lower feed rolls 2a and 2b by using feed rolls for which both upper and lower feed rolls are driven by a drive device as the pair of upper and lower feed rolls 2a and 2b.