Rotor Core Hydroforming with Axial Pressing for Shaft Alignment

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Solution Overview

Problem

The existing rotor manufacturing method using hydroforming results in variations in the relative positional relationship between the shaft and the rotor core due to gaps between electromagnetic steel sheets, leading to inconsistencies in thickness and end face positions.

Innovation Solution

A method and apparatus that involve pressing the rotor core with a core pressing member during hydroforming to prevent gaps between steel sheets, ensuring the thickness falls within tolerance limits by using a shaft pressing member and core pressing member to position the shaft and rotor core accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If hydroforming is performed with the laminated core positioned away from the shaping dies, then the hydroforming process can be completed, but gaps occur between electromagnetic steel sheets causing variations in thickness and positional relationship

Engineering Contradiction:

Improvehydroforming process completionVSAvoidthickness consistency and positional relationship

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by positioning support dies at predetermined locations before hydroforming begins. These support dies pre-establish the necessary contact points with the laminated core to prevent gap formation during the subsequent hydroforming process, ensuring thickness consistency while allowing the process to complete successfully

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The support dies act as intermediary elements between the hydroforming system and the laminated core. They mediate the force transmission during hydroforming by providing localized support at critical positions, preventing the electromagnetic steel sheets from separating while maintaining the overall hydroforming process

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

Prevents variations in the relative positional relationship between the shaft and rotor core, ensuring consistent product quality by maintaining the thickness within specified limits.

Implementation Method 1

fixing the shaft to the rotor core by performing, with the rotor core pressed, hydroforming that involves filling a fluid into the shaft and pressurizing the fluid so as to expand the shaft, thus pressure-welding the shaft to an inner peripheral surface of the shaft insertion hole

Methodology Applied

Scientific EffectHydroforming: Pressure Increase

Data Source

PatentEP3989419B1Rotor manufacturing method and rotor manufacturing device

Publication Date: 2026.03.25 AISIN CORP

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AI summary

This rotor manufacturing method includes the steps of: pressing a rotor core in a central axis direction by using a core pressing member; and fixing a shaft to the rotor core by performing, with the rotor core pressed, hydroforming that involves pressure-welding the shaft to an inner peripheral surface of a shaft insertion hole.