In-situ Ring Gear Tooth Repair Using Automated Cable-Suspended Machining

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Solution Overview

Problem

The existing methods for repairing the toothing of large rotating machines' ring gears are labor-intensive, dependent on operator expertise, and lack reproducibility, leading to inconsistent results and increased maintenance costs due to manual machining operations.

Innovation Solution

A method utilizing a removable machining device with a frame and a movable cutting member, which is clamped onto the ring gear and moved automatically along a tensioned cable to machine teeth without dismantling the gear, ensuring precise machining and reproducibility by following predetermined operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If manual machining operations are used for tooth repair, then operator flexibility and adaptability are maintained, but labor intensity increases and reproducibility decreases

Engineering Contradiction:
Improveautomation of machining operationsVSAvoidcomplexity of machining device
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The machining device is divided into modular components: a movable carriage carrying cutting tools, a positioning system with scales and indicators, and a support structure. This segmentation allows the complex device to be managed through independent functional modules, reducing overall system complexity while enabling automated operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The device incorporates self-positioning mechanisms through precision scales and indicators that automatically guide the carriage to correct tooth positions. The system uses the ring gear's own geometry as a reference, eliminating the need for complex external positioning equipment and reducing device complexity.

Inventive Principle:
Principle #25Self-service

2Manufacturing precision

If automated machining is implemented, then reproducibility and precision are improved, but device complexity increases

Engineering Contradiction:
Improveprecision of tooth machiningVSAvoidcomplexity of positioning system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The positioning system uses precision scales and indicators that replicate reference measurements directly onto the ring gear surface. This copying mechanism transfers precise positional information without requiring complex computational systems, achieving high manufacturing precision through analog reference replication.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system achieves precision by changing the parameter of position measurement from manual estimation to scaled numerical indication. The scales provide quantitative positional parameters that guide the automated carriage, transforming qualitative operator judgment into quantitative automated control.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the ring gear is dismantled for repair, then complete access to teeth is achieved, but maintenance time and cost increase

Engineering Contradiction:
Improvespeed of repair operationVSAvoidease of accessing teeth
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The machining device is extracted from any requirement for ring gear disassembly. The self-contained carriage and cutting tools are brought to the ring gear in its installed position, allowing tooth repair without extracting or dismantling the gear from the machine. This eliminates downtime associated with disassembly and reassembly operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A portable machining carriage serves as an intermediary between the cutting tools and the ring gear teeth. This mediator brings the machining capability to the workpiece location without requiring the workpiece to be moved or disassembled, enabling in-situ repair while maintaining ease of operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Extent of automation

If multiple operators are used for manual machining, then complex operations can be performed, but labor costs and variability increase

Engineering Contradiction:
Improvelevel of automation in machiningVSAvoidcomplexity of control system
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The positioning system incorporates scales and indicators that provide continuous feedback on carriage position and tooth location. This feedback mechanism enables a single operator to control the automated machining process with precision, eliminating the need for multiple operators while keeping the control system relatively simple through direct visual and mechanical feedback loops.

Inventive Principle:
Principle #23Feedback

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 method allows for efficient, automated, and reproducible tooth repair on large machines, reducing the reliance on operator expertise and minimizing downtime by enabling precise machining of all teeth without disassembly, thus extending the life of the ring gear.

Implementation Method 1

said machining device being suspended and held by at least one cable under tension connected to the frame of the rotating machine

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

said machining device being suspended and held by at least one cable under tension connected to the frame of the rotating machine

Methodology Applied
Scientific EffectTension: Tension

Data Source

PatentEP3271109B1Method for repairing the teeth of a ring gear
Publication Date: 2018.12.12 FIVES FCB
  • EP3271109B1 patent drawingFigure 1~2
  • EP3271109B1 patent drawingFigure 3

AI summary

Method for repairing the teeth of a toothed ring gear (3), the method using a removable machining device (1), comprising a frame and a part moving with respect to the frame, supporting a cutting member, said process being implemented in situ without dismounting the toothed ring gear (3) from the rotating machine (2) that it is intended to drive, said method comprising the following steps for implementing the machining of each tooth: - attaching said machining device (1) to the toothed ring gear (3) by tightening the machining device (1) onto the ring gear in an attachment position on the ring gear with respect to the tooth to be machined, - performing the machining of the tooth in an automated manner by control of the cutting organ following predetermined machining operations, in which the machining device (1) is moved from an attachment position on the toothed ring gear (3) corresponding to the previously machined tooth, to an attachment position of a neighbouring tooth to be machined, while the toothed ring gear (3) is stationary, said machining device (1) being suspended and held by at least one tensioned cable (5) connected to the frame of the rotating machine (2).