Cutting Tool Angular Correction for Accurate WEDM Feature Machining

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Solution Overview

Problem

Existing machining methods for aircraft engine components, such as firtree slots and splines, face challenges due to misalignment between the machining wire and the component, leading to unsuitable feature angles and dimensions, particularly when using wire electrical discharge machining (WEDM).

Innovation Solution

A method and machine system that determine the coordinates of three circumferentially offset points on a component's reference surface, calculate an angular correction, and adjust the cutting tool's angle to ensure it is parallel to the component's central axis, allowing precise machining of features like firtree slots and teeth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional wire electrical discharge machining (WEDM) is used without alignment correction, then the machining process can proceed, but the cutting tool (wire) and component become misaligned resulting in unsuitable feature angles and dimensions

Engineering Contradiction:
Improvefeature angle and dimension accuracyVSAvoidalignment system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary probing of reference surfaces and calculation of angular correction values before the actual machining operation. This preliminary measurement and computation phase enables the cutting tool to be pre-aligned with the component, preventing misalignment issues during machining without requiring complex real-time alignment mechanisms

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical alignment systems with a computational approach. Instead of using elaborate mechanical fixtures and alignment devices, the system uses coordinate measurement, mathematical computation of angular corrections, and software-controlled tool positioning to achieve precise alignment, thereby reducing mechanical complexity while improving precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If expensive fixture systems with tight tolerances are used to ensure alignment, then manufacturing precision improves, but device complexity and cost increase

Engineering Contradiction:
Improvealignment accuracyVSAvoidfixture system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system creates a digital copy or representation of the component's reference surfaces through coordinate probing. By measuring and storing the coordinates of reference points, the system builds a digital model that is then used to calculate the appropriate angular correction, eliminating the need for expensive physical fixtures with tight tolerances

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system changes the approach from maintaining fixed mechanical tolerances to dynamically calculating and applying angular correction parameters. Instead of relying on rigid fixture tolerances, the system measures actual component geometry, computes the deviation from ideal alignment, and applies a calculated angular correction to the cutting tool, thereby achieving high precision without expensive fixtures

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the cutting tool is not angled with angular correction, then the machining process is simpler, but the resulting features have incorrect angles and dimensions

Engineering Contradiction:
Improvefeature angle accuracyVSAvoidmachining operation simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The system enables the machining process to self-correct for misalignment through automated probing and calculation. The component itself provides the reference surfaces for measurement, and the system automatically computes and applies the angular correction without requiring manual intervention or complex operator skills, thereby maintaining operational simplicity while achieving precision

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 enables accurate machining of features without the need for expensive fixture systems with tight tolerances, optimizing alignment and reducing calibration inaccuracies, resulting in correctly angled and sized components suitable for aircraft engines.

Implementation Method 1

determining coordinates of at least three points on a reference surface of the component

Methodology Applied
Scientific EffectPhysical contact probing:

Implementation Method 2

Wire electrical discharge machining (WEDM) is a process by which a wire is fed through a component to be machined

Methodology Applied
Scientific EffectWire electrical discharge machining: Electrical Discharge Machining

Data Source

PatentEP4216007A1Method of determining an angular correction to apply to a cutting tool and cutting machine
Publication Date: 2023.07.26 PRATT & WHITNEY CANADA CORP
  • EP4216007A1 patent drawingFigure 1
  • EP4216007A1 patent drawingFigure 2
  • EP4216007A1 patent drawingFigure 3

AI summary

A method of machining a feature in a component (C) using a machine (40) having a support (47) rotatable about a rotation axis (R) and having a cutting tool (44) movable relative to the component (C), the component (C) being mounted on the support (47) for rotation about a central axis of the component (C), the method includes: determining coordinates of at least three points on a reference surface of the component (C), the at least three points being circumferentially offset from one another relative to the central axis; determining an angular correction to apply to the cutting tool (44) based on the coordinates of the at least three points; and machining the feature in the component (C) using the cutting tool (44) angled with the angular correction.