Stator Bar Mold Insert With Low Friction Lining

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Solution Overview

Problem

The existing methods for inserting and joining stator bars in alternating current dynamoelectric machines face challenges such as porosity in brazed joints, resin accumulation, and damage during mold removal, leading to manufacturing delays and increased costs.

Innovation Solution

A stator bar mold insert with low friction inlays in the lug area, featuring a central cavity lined with PTFE or similar materials, facilitates easy removal of stator bars by reducing friction and minimizing resin accumulation, thereby preventing damage to the bars and molds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If stator bars are removed from the mold after impregnation, then the impregnation process is complete, but damage may occur to the mold or stator bar due to high friction and resin accumulation

Engineering Contradiction:
Improveintegrity of stator bar and moldVSAvoiddifficulty of removing stator bar from mold
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A release agent is applied to the mold surface before impregnation to act as an intermediary layer between the mold and the stator bar. This release agent prevents excessive resin accumulation and reduces friction, allowing the stator bar to be removed easily without damaging the mold or the bar itself.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

A flexible release film or coating is applied to the mold surface. This thin film layer provides a low-friction interface that allows the stator bar to be extracted smoothly from the mold after impregnation, preventing damage while maintaining the integrity of both the mold and the stator bar.

Inventive Principle:
Principle #30Flexible shells and thin films

2Manufacturing precision

If excess resin accumulates on the stator bar ends, then the impregnation process may be thorough, but the stator bar must be reworked and removal from mold becomes complicated

Engineering Contradiction:
Improvequality of impregnationVSAvoidcomplexity of removal process
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The release agent serves as a mediator that prevents excess resin from bonding the stator bar to the mold. By applying this intermediary substance to the mold surface, the stator bar can be removed easily without requiring rework, even after thorough impregnation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the surface area of the joint is large, then the brazing process is more challenging, but complete sound brazes are difficult to achieve regardless

Engineering Contradiction:
Improvequality of brazed jointVSAvoiddifficulty of brazing process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The mold and stator bar surfaces are prepared in advance by applying a release agent before the brazing process. This preliminary action ensures that the surfaces are clean and free from excess resin accumulation, creating optimal conditions for achieving sound brazed joints without requiring complex brazing procedures.

Inventive Principle:
Principle #10Preliminary action

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

The solution enables safe and efficient removal of stator bars from molds, reducing the risk of damage and porosity in brazed joints, thus improving manufacturing efficiency and reducing costs associated with rework and scrapping.

Implementation Method 1

A low friction material, typically PTFE, lines the central cavity and substantially surrounds the stator bar when the bar is located inside the mold

Methodology Applied
Scientific EffectFriction reduction: Lubrication

Data Source

PatentEP3419150B1Stator bar mold insert
Publication Date: 2020.02.19 GENERAL ELECTRIC CO
  • EP3419150B1 patent drawingFigure 1
  • EP3419150B1 patent drawingFigure 2
  • EP3419150B1 patent drawingFigure 3

AI summary

A stator bar mold insert (200) includes an upper portion (210) and a lower portion (220). A central cavity (230) is disposed between, and defined by, the upper portion and the lower portion. The central cavity is configured for use with a stator bar (10). A low friction material (240-244) lines the central cavity, and the low friction material substantially surrounds the stator bar located inside the stator bar mold insert.