Radial Unscrewing Tool for Gas Turbine Connecting Nut
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Solution Overview
Problem
The existing methods for dismantling the connecting nut in gas turbine engines, particularly in twin-spool turbojet engines, face challenges such as limited accessibility, risk of damaging the nut during unscrewing, and increased likelihood of nut seizing due to factors like coking, deformation, and oxidation, often requiring cutting which is costly and messy.
Innovation Solution
A tool is developed that includes a tubular element with retractable fingers for lateral contact with the nut's teeth, combined with a heating process to soften stuck components and distribute torque evenly, allowing for increased torque application without damaging the nut, and a mechanism to apply controlled rotational force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard unscrewing tool is used through the central passage, then accessibility is maintained, but the torque applied is limited and the nut may seize or deform
Solution Approach 1:
The invention transitions from axial approach (through central passage) to radial approach (through bearing hub). By changing the dimension of access from longitudinal to radial, the tool can engage the nut's teeth laterally and apply torque more effectively without being constrained by the narrow central passage geometry.
Solution Approach 2:
The invention introduces a specialized unscrewing tool with lateral tooth engagement as an intermediary between the operator and the connecting nut. This tool features protrusions that engage the nut's teeth from the side, allowing torque application without direct axial insertion, thus overcoming both accessibility and torque limitations.
2Reliability
If greater torque is applied to loosen a seized nut, then the chance of successful unscrewing increases, but the risk of damaging the nut teeth or deforming the nut increases
Solution Approach 1:
The unscrewing tool divides the torque application across multiple discrete engagement points (protrusions engaging individual teeth). This segmentation distributes the mechanical stress evenly across all nut teeth rather than concentrating it on one or two points, allowing higher total torque to be applied without damaging individual teeth or causing nut deformation.
Solution Approach 2:
The invention changes the engagement parameter from axial contact to lateral contact with the nut teeth. By engaging the teeth on their broad face rather than at the tip, the tool increases the contact area and distributes forces more evenly, enabling higher torque application while maintaining tooth integrity and preventing nut deformation.
3Force
If the nut is heated before unscrewing, then the seizing is reduced and torque requirement decreases, but additional process time and equipment are required
Solution Approach 1:
The invention applies thermal treatment as a preliminary action before mechanical unscrewing. By heating the connecting nut beforehand, the seized interfaces are softened and expanded, reducing friction and bonding strength. This preliminary thermal preparation significantly decreases the torque needed for subsequent unscrewing operations, making the overall process more efficient despite the added heating step.
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 reduces the need for cutting the nut, minimizes damage, and increases the chances of successful unscrewing by distributing force evenly across all teeth, thus avoiding deformation and seizing issues.
Implementation Method 1
a device for heating a connecting nut (20) of a rotor (35) of a gas turbine engine module
Data Source
Figure 1
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AI summary
The present invention concerns loosening, in particular, the nut connecting the HP rotor to the intermediate housing of a twin-shaft turbojet engine and forward fan comprising an LP turbine module, an HP module with an upstream journal of the HP rotor, and an intermediate housing with a support bearing of the HP rotor journal, said journal being held in said bearing by said connecting nut, the method comprising a step of inserting a tool for loosening the connecting nut after having cleared access to the nut. The loosening tool (200) comprises a tube (201) and a plurality of fingers (212) retractable between a position in which they are housed in the tube and a position in which they are deployed radially. Said tool (200) is installed with said retractable fingers (212) deployed and in contact with all of the teeth of the nut, and an unscrewing rotational torque is then applied to the tool.