Planet Carrier Web Layout for Defect-Tolerant Casting

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Solution Overview

Problem

Existing casting methods for planet carriers in planetary gears require expensive and time-consuming use of cooling tools, leading to material defects and reduced mechanical strength due to hot cracking and solidification issues.

Innovation Solution

A planet carrier design with a web connecting circular closure walls, where the greatest material accumulation is in an area of reduced mechanical stress, allowing for solidification without external cooling tools and minimizing material weaknesses, ensuring high resilience and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If cooling tools (chills or external molds) are used to ensure solidification quality, then manufacturing quality is improved, but production time and cost increase

Engineering Contradiction:
Improvesolidification qualityVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The planet carrier geometry is pre-designed with strategic material accumulation zones positioned in advance during the casting process. These zones act as built-in solidification control features that guide the solidification front without requiring additional cooling tools, thereby maintaining manufacturing quality while improving productivity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The planet carrier structure serves its own solidification control needs through its geometric design. The material accumulation zones create natural solidification patterns that ensure quality without external intervention from cooling tools, making the component self-sufficient for its own solidification requirements

Inventive Principle:
Principle #25Self-service

2Manufacturing precision

If cooling tools are used to control solidification, then material quality is improved, but production complexity and cost increase

Engineering Contradiction:
Improvematerial qualityVSAvoidproduction complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The planet carrier features localized material accumulation zones with specific geometries tailored to different regions. These local geometric variations create targeted solidification control at critical areas without requiring complex external cooling systems, thereby improving material quality while reducing production complexity

Inventive Principle:
Principle #3Local quality

3Strength

If material accumulation is placed in high-stress areas, then structural strength is improved, but solidification quality deteriorates due to hot cracking tendency

Engineering Contradiction:
Improvestructural strengthVSAvoidsolidification quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The design creates different material characteristics in different locations: material accumulation zones are strategically placed in low-stress areas to control solidification, while high-stress areas maintain optimized geometries for strength. This local differentiation resolves the conflict between structural strength and solidification quality

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The design accepts that material accumulation zones will have reduced mechanical properties but converts this potential harm into a benefit by positioning these zones in low-stress areas. The 'defective' material characteristics become advantageous for controlling solidification without compromising overall structural integrity

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 planet carrier is produced quickly and cost-effectively with high material quality, reducing the risk of mechanical failure by placing material weaknesses in low-stress areas and ensuring uniform stress distribution, thus enhancing the component's strength and reliability.

Implementation Method 1

During a solidification process in the production of the planetary carrier using a casting process

Methodology Applied
Scientific EffectSolidification: Freezing

Implementation Method 2

a solidification front drives faulty materials in front of it, which locally reduces the quality of the material used in a solidified cast component

Methodology Applied
Scientific EffectSolidification front movement: Freezing

Data Source

PatentEP3421843B1Planet carrier, casting method and planetary gear
Publication Date: 2021.08.04 FLENDER GMBH
  • EP3421843B1 patent drawingFigure 1
  • EP3421843B1 patent drawingFigure 2~3
  • EP3421843B1 patent drawingFigure 4~5

AI summary

The invention relates to a planet carrier (10) comprising a first hub (12) with an adjacent first sealing wall (16) and a second hub (14) with an adjacent second sealing wall (18). The first and second sealing walls (16, 18) are arranged opposite each other. The planet carrier (10) has a web (20) for connecting the first sealing wall (16) to the second sealing wall (18). According to the invention, the largest material concentration (30) of the planet carrier (10) is located in a region (42) of the web (20) that is subject to reduced mechanical stress in an operating state of the planet carrier (10).