Turbomachine Rotor Balancing via Chemical Dissolution

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Solution Overview

Problem

The manufacturing process of turbomachine rotors, particularly low-pressure compressor drums, faces inefficiencies in material removal and balancing due to the need for multiple workshop interactions and underutilization of costly machines, leading to disruptions in the manufacturing flow and reduced profitability.

Innovation Solution

A method involving chemical machining is employed to determine and correct unbalancing masses by using a nitric-acid and hydrofluoric-acid based bath for selective material removal, allowing precise balancing without departing from dimensional tolerances, utilizing the facilities in situ and avoiding the need for dedicated machining equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional mechanical balancing machining is used, then balancing precision can be achieved, but it requires dedicated machining equipment and multiple workshop interactions which disrupt manufacturing flow and reduce productivity

Engineering Contradiction:

Improvebalancing precisionVSAvoidmanufacturing flow efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges the balancing operation with the existing blue etch inspection process by integrating chemical machining into the same workflow. The rotor is chemically machined in the blue etch bath after inspection, eliminating the need for separate mechanical machining operations and dedicated balancing workshops, thereby maintaining precision while improving manufacturing flow efficiency

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional mechanical balancing machining with chemical machining using acid baths. Instead of using mechanical cutting tools to remove material for balancing, the process uses chemical dissolution in controlled acid environments, eliminating the need for dedicated mechanical machining equipment and reducing workshop interactions

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If dedicated balancing machines are used, then precise material removal can be achieved, but costly machinery remains underutilized negatively impacting profitability

Engineering Contradiction:

Improvematerial removal precisionVSAvoidprofitability

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent makes the blue etch inspection facility multi-functional by adding chemical machining capability to it. The same bath and handling system used for inspection now also performs balancing operations, eliminating the need for dedicated balancing machines and ensuring full utilization of existing costly equipment, thereby improving profitability while maintaining precision

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing blue etch inspection facility serves itself by performing both inspection and balancing functions. The facility uses its own infrastructure (bath, handling system, heating capability) to perform the balancing operation, eliminating dependency on external dedicated machines and maximizing the utility of existing investments

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If multiple workshop interactions are required for finishing machining and balancing, then precise dimensional control can be achieved, but the manufacturing process fluidity is disrupted

Engineering Contradiction:

Improvedimensional tolerance controlVSAvoidprocess fluidity

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent combines finishing machining and balancing operations into a single integrated process at the blue etch facility. Both operations are performed in sequence within the same workshop during the same workflow cycle, eliminating the need for parts to be moved between workshops and maintaining precision through controlled chemical machining while restoring process fluidity

Inventive Principle:

Principle #5Merging (Combining)

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 the precision and repeatability of material removal, reduces the need for costly machinery, and streamlines the manufacturing process by integrating balancing operations directly into existing inspection workflows, improving the fluidity and profitability of the manufacturing process.

Implementation Method 1

chemical machining of the rotor... immersion of the rotor in a bath containing a chemical machining agent... acid attack in a bath of acid salts which is used to remove a thickness of material

Methodology Applied

Scientific EffectChemical dissolution:

Data Source

PatentUS8974681B2Method for balancing a turbomachine rotor

Publication Date: 2015.03.10 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A method for balancing a rotor, notably of a turbomachine, includes a step of determining an unbalancing mass, and a step of balancing by chemical machining of the rotor. The chemical machining includes arranging a bath containing a chemical machining agent so that the bath has a capacity of heterogeneous material removal as a function of the depth in the bath, an amount of material removal at a first depth in the bath is greater than an amount of material removal at a second depth in the bath; immersing the rotor in the bath; and orienting the rotor in the bath taking account of the capacity of heterogeneous material removal so that the quantity of material removed from the rotor in a zone of the unbalancing mass is sufficient to balance the rotor.