Broach Tooth Grinding with Controlled Rake Angle and Chip Deflection

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Solution Overview

Problem

Existing methods for forming turbine engine disk slots, such as those using firtree attachment roots, suffer from inconsistent rake angles during broaching, leading to variations in chip generation, material properties, and reduced precision due to uneven cutting edge angles.

Innovation Solution

A method involving the use of a rotating quill with a lateral surface to grind broach teeth, allowing continuous reorientation to achieve a consistent rake angle of 7.5° to 8.5° over a majority of the cutting edge, forming a peripheral trench to deflect chips and improve surface finish.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional grinding methods are used to form broach teeth, then the grinding process can be completed, but the rake angle becomes inconsistent leading to variations in chip generation and reduced precision

Engineering Contradiction:

Improverake angle consistencyVSAvoidchip generation uniformity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The quill is continuously reoriented during the grinding process to dynamically adjust and maintain a consistent rake angle (7.5° to 8.5°) across the cutting edge, transforming the static grinding approach into a dynamic controlled process that ensures uniform chip generation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The grinding process changes the operational parameters by continuously adjusting the quill orientation angle during machining, maintaining the rake angle within the optimal range of 7.5° to 8.5° to achieve consistent cutting performance and uniform chip generation

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a rotating quill is used to grind broach teeth with continuous reorientation, then consistent rake angle and improved precision are achieved, but the device complexity increases

Engineering Contradiction:

Improvecutting edge angle consistencyVSAvoidgrinding mechanism complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The rotating quill mechanism serves multiple functions: it grinds the broach teeth while simultaneously maintaining the desired rake angle through continuous reorientation, eliminating the need for separate positioning and grinding operations

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The quill system automatically maintains the correct rake angle through its own rotational movement and reorientation capability, without requiring external intervention or complex additional control mechanisms

Inventive Principle:

Principle #25Self-service

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 results in uniform chip generation, reduced cutting forces, improved surface finish, and increased precision by maintaining a consistent rake angle, facilitating tighter tooth spacing and higher throughput.

Implementation Method 1

grinding the first face of each tooth of a plurality of said teeth with a lateral surface of a rotating quill

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS20250319565A1Broach Cutter Grinding with Rake Angle Control

Publication Date: 2025.10.16 RTX CORP

AI summary

A broach or broach segment has a spine. A longitudinal array of teeth protrude from the spine, each tooth having: a first face and an opposite second face; and a distal surface joining the first face and second face; and at least some of the teeth being firtree teeth and have a peripheral trench adjacent the cutting edge of the at least one tooth.