Helical Stator Core Finishing via Radial Coining

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Solution Overview

Problem

Conventional methods for manufacturing helically stacked stator cores in rotating electrical machines face issues such as misalignment, gaps between core sheets, and deformation, leading to inefficiencies in finishing processes that require extensive manual labor and result in suboptimal dimensions and magnetic losses.

Innovation Solution

A manufacturing method that incorporates a coining process to correct the inner and outer diameters of the helically stacked core by using a coining punch divided in a circumferential direction, arranged around the core to deform the core-back part and teeth, ensuring coaxial alignment and reducing gaps, while also applying simple bending to reduce processing load and prevent rust.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a helical core is formed by winding and stacking core sheets with rolled core-back parts, then the core can be manufactured with slots and teeth, but gaps are produced between stacked core sheets on the outer circumferential side and misalignment occurs in inner and outer circumferences

Engineering Contradiction:

Improvecore sheet stackingVSAvoidcore sheet alignment

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The core-back part is preliminarily formed with a tapered shape by rolling before stacking, creating a structure that facilitates winding while anticipating the need for subsequent finishing processes to correct the resulting misalignment and gaps

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The core-back part thickness is intentionally varied (thinner than the slot and tooth side) to enable spiral winding, and the finishing process modifies the inner and outer circumferential dimensions to correct misalignment, accepting parameter changes as part of the manufacturing sequence

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a finishing process is applied to correct misalignment and reform inner and outer circumferential surfaces, then dimensional precision is improved, but processing time and complexity increase

Engineering Contradiction:

Improveinner and outer circumferential surface precisionVSAvoidfinishing process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The ironing process and deburring process are merged into a single finishing operation, where the ironing punch simultaneously corrects the inner and outer circumferential surfaces to predetermined sizes and removes burrs, reducing the number of separate processing steps

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ironing process continuously presses the inner and outer circumferential surfaces through the die to correct misalignment and reform surfaces in a single continuous motion, maintaining productive action throughout the process

Inventive Principle:

Principle #20Continuity of useful action

3Ease of operation

If oil is applied to reduce friction during the ironing process, then processing ease is improved, but cleaning requirements and additional processing steps increase

Engineering Contradiction:

Improveironing process friction reductionVSAvoidcleaning process requirements

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

Oil is introduced as an intermediary substance to reduce friction between the ironing punch and the core sheets during the ironing process, enabling smoother deformation and reducing processing resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The oil applied during ironing is subsequently removed through a cleaning process that washes away the lubricant and any debris, restoring the core to a clean state for final assembly or use

Inventive Principle:

Principle #34Discarding and recovering

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 method effectively corrects the helical core's dimensions to predetermined sizes, reduces processing energy, prevents distortion and rust, and enhances productivity by minimizing gaps and magnetic losses, thus improving the manufacturing efficiency and quality of stator cores.

Implementation Method 1

a coining process that simultaneously moves a coining punch divided in a circumferential direction and arranged around the helically stacked core to a center side in a radial direction to press an outer surface of each core-back part

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

pressing down an end side of the helically stacked core by a holding device

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS8516682B2Manufacturing method of a stator core of rotating electrical machine

Publication Date: 2013.08.27 DENSO CORP

AI summary

A manufacturing method of a stator core of a rotating electrical machine includes a finishing process that simultaneously moves a coining punch divided in a circumferential direction and arranged around a helically stacked core to a center side in a radial direction and presses an outer surface of a core-back part of the helically stacked core while pressing an end side of the helically stacked core in an axial direction by a holding device.