Self-Locking Turbine Attachment Elements
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Solution Overview
Problem
In turbomachines, the existing methods for preventing rotation of attachment elements during assembly and maintenance introduce residual stresses and weight increases, leading to potential damage and inefficiency.
Innovation Solution
A mechanical system where self-locked elements, with reduced spacing between their thread axes, cooperate in pairs to prevent rotation, minimizing the coverage area of locking means and reducing the overall weight and stress on the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stop member with a stop wall is used to prevent rotation of attachment elements, then rotation prevention is achieved, but residual stresses and crushing damage occur on the stop wall during screwing operations
Solution Approach 1:
A bearing member is introduced as an intermediary element between the attachment element and the locking member. The bearing member receives the bearing force during rotation prevention, protecting the locking member from direct stress contact while enabling effective rotation prevention through the bearing force transmitted from the attachment element.
Solution Approach 2:
The rotation prevention function is segmented into two distinct components: a locking member that provides the rotational constraint and a bearing member that absorbs the bearing forces. This segmentation separates the functions of rotation prevention and force absorption, preventing stress concentration and damage to a single structure.
2Ease of operation
If locking members are adapted to prevent rotation by bearing on adjacent attachment elements, then rotation prevention is achieved, but the accumulated length of locking members significantly increases the weight of the mechanical system
Solution Approach 1:
The bearing member serves multiple functions: it prevents rotation of the attachment element, absorbs bearing forces during tightening, and enables the locking member to be more compact. This multi-functionality reduces the overall size and weight of the rotation prevention mechanism while maintaining effective rotation prevention.
Solution Approach 2:
The design changes the geometric parameters of the locking member by introducing the bearing member, allowing the locking member to be shorter and more compact. The bearing member effectively transfers the load path, enabling a reduction in the accumulated length of locking members along the line of attachment elements.
3Ease of operation
If rotation prevention members are added to each attachment element, then full rotation prevention is achieved, but the complexity and fabrication costs of the mechanical system increase
Solution Approach 1:
The bearing member is integrated with the locking member assembly, combining the rotation prevention and force absorption functions into a unified structure. This merging reduces the number of separate components needed and simplifies the overall mechanical system while maintaining effective rotation prevention.
Data Source
AI summary
A mechanical system for a turbomachine includes a turbomachine part to be attached and a plurality of threaded attachment elements mounted on the turbomachine part in sequence along a line. The attachment elements fix the turbomachine part to the turbomachine. At least some of the attachment elements are arranged to be prevented from rotating by mutual cooperation about their corresponding thread axes, by a rotation prevention system provided on each of these attachment elements called self-locking elements. The self-locked elements cooperate in pairs, each pair including two directly consecutive self-locked elements along the line. At least one of the pairs has a distance between the thread axes of its two self-locked elements less than the distance between one of these two thread axes and the axis of either of the two attachment elements arranged along the line on each side of the at least one of the pairs.