Sintered Gear Toothing with Undercut Root Transition

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Solution Overview

Problem

Sintered internal gears face material defects and warpages due to deformation during post-compaction in the tooth root region, especially at the fillet area, leading to reduced strength and increased costs for machining.

Innovation Solution

The method involves forming an undercut transition region between the tooth flanks and roots, limiting post-compaction to this region, and producing tooth roots without allowances, allowing for improved tooth root strength and reduced deformation, with post-processing focused on the tooth flanks to minimize tool contact and deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If post-compaction is applied to the tooth root region to improve strength, then tooth root strength is improved, but material defects and micro-cracks occur due to great deformation

Engineering Contradiction:

Improvetooth root strengthVSAvoidmaterial defects and micro-cracks

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The tooth root region is segmented into a compacted zone and a non-compacted zone separated by an undercut transition region. The undercut structure allows the compaction tool to engage the tooth flanks while preventing deformation in the critical root fillet area, thus improving strength without creating defects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the tooth are treated differently: tooth flanks receive post-compaction to improve strength, while tooth roots are protected from deformation. The undercut transition region creates a localized boundary that preserves the quality of the root region while allowing compaction elsewhere.

Inventive Principle:

Principle #3Local quality

2Strength

If case hardening is used to achieve desired strength, then tooth strength is improved, but warpages occur requiring additional machining

Engineering Contradiction:

Improvetooth strengthVSAvoidwarpages

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The undercut transition region is formed during the pressing stage before sintering and hardening. This preliminary geometric feature prevents subsequent warpages from affecting the tooth root region, eliminating the need for additional machining to correct shape deviations.

Inventive Principle:

Principle #10Preliminary action

3Strength

If post-compaction is performed on internal gears to improve strength, then component strength is improved, but machining costs increase due to hard fine machining requirements

Engineering Contradiction:

Improvecomponent strengthVSAvoidmachining costs

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The internal gear tooth root region is segmented from the tooth flank region through the undercut structure. This segmentation allows the tooth roots to be produced without allowance during pressing, eliminating the need for costly hard fine machining while maintaining strength requirements.

Inventive Principle:

Principle #1Segmentation

4Strength

If tooth roots are produced with allowances to ensure strength, then tooth root strength is improved, but production complexity increases

Engineering Contradiction:

Improvetooth root strengthVSAvoidproduction complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Instead of producing tooth roots with allowances and then removing material through machining, the invention inverts the approach by producing tooth roots without allowances. The undercut transition region ensures that the full pressing force is applied to the tooth flanks while the tooth roots are formed directly to their final dimensions, simplifying the production process.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enhances tooth root strength, prevents defects like pore structures and micro-cracks, and simplifies the production of internal gears with small fillet radii, reducing machining costs and improving tool longevity.

Implementation Method 1

pressing a powder to form a green compact

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

sintering the green compact

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 3

hardening is carried out by means of plasma nitriding or plasma nitrocarburizing

Methodology Applied

Scientific EffectPlasma nitriding: Nitriding

Implementation Method 4

hardening is carried out by means of plasma nitriding or plasma nitrocarburizing

Methodology Applied

Scientific EffectPlasma nitrocarburizing: Carbonitriding

Implementation Method 5

the tooth flanks and possibly the tooth tips are post-compacted

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS12013022B2Method for producing a sintered component with a toothing

Publication Date: 2024.06.18 MIBA SINTER AUSTRIA GMBH

AI summary

A method for producing a sintered component, in particular an annular sintered component, with a toothing, having teeth with tooth roots, tooth tips and tooth flanks, includes the steps of pressing a powder to form a green compact, sintering the green compact, and hardening the sintered component, wherein after sintering, the tooth flanks and possibly the tooth tips are post-compacted and subsequently undergo post-processing by machining, and wherein a transition region between the tooth flanks and the tooth roots has an undercut design, and post-compaction of the tooth flanks is carried out only up to this transition region.