Radial Fit Coupling Bolt with Extrudable Ring for Jamming Prevention
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Solution Overview
Problem
Current radial fit coupling bolts face issues with jamming and high frictional engagement, making them difficult to disassemble and requiring significant force, as the sleeve often becomes locked with the central portion of the shank, leading to uneven expansion and reduced tensile load distribution.
Innovation Solution
A high-capacity radial fit coupling bolt assembly featuring a shank with inner and outer sleeves and an extrusion or compression ring, allowing for axial movement and diametrical expansion of the outer sleeve under tension, enabling the shank to move relative to the sleeves and components, with a tensioning mechanism that applies load along the full length of the shank for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sleeve is diametrically expanded to fill the bolt holes, then the bolt tension and clamping force are improved, but the sleeve becomes locked inside the external portion and difficult to remove
Solution Approach 1:
The bolt is divided into two distinct portions: an external tapered portion and an internal cylindrical portion. The sleeve engages only with the external tapered portion, allowing it to be expanded for tensioning while the internal cylindrical portion remains free to move axially for removal purposes.
Solution Approach 2:
A separate internal cylindrical portion acts as an intermediary element between the sleeve and the bolt function. This portion allows the bolt to be removed by axial movement without affecting the sleeve's expanded state or requiring forceful extraction from the bolt holes.
2Manufacturing precision
If the tapered surface is machined with a track, then the sleeve expansion is controlled, but the portions overlying the track do not expand evenly and jamming occurs
Solution Approach 1:
The bolt's engagement portion is segmented into an external tapered surface and a separate internal cylindrical portion. This segmentation allows the external tapered surface to provide controlled expansion while the internal portion remains unaffected, eliminating the jamming issue caused by tracks in the tapered surface.
3Reliability
If the sleeve is expanded to fill voids from tolerance, then slippage of coupling faces is limited, but considerable force is required to release the bolt from bolt holes
Solution Approach 1:
By segmenting the bolt into external tapered and internal cylindrical portions, the sleeve is confined to engaging only the external portion. This allows the sleeve to expand and fill tolerance voids for reliable slippage prevention, while the internal cylindrical portion provides a clear path for axial removal without requiring forceful extraction.
Solution Approach 2:
The internal cylindrical portion is extracted as a separate functional element from the traditional single-piece bolt design. This extracted portion serves as a removal aid that eliminates the need for considerable force to extract the bolt from the expanded sleeve.
4Strength
If the sleeve becomes locked with the central portion of the shank, then high frictional engagement is achieved, but disassembly becomes extremely difficult
Solution Approach 1:
The bolt is segmented into an external tapered portion that engages the sleeve for frictional engagement, and an internal cylindrical portion that remains free of sleeve engagement. This allows the sleeve to lock with the external portion for high frictional engagement while the internal portion allows easy disassembly through axial movement.
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
The solution simplifies manufacturing and operation, allows for easier assembly and disassembly, and provides consistent clamping forces, effectively addressing the issues of jamming and uneven expansion by enabling a 'one pull' bolt design that secures components with even tension distribution.
Implementation Method 1
the outer sleeve to expand diametrically into engagement with the at least two components
Implementation Method 2
relative axial movement between the inner and outer sleeves will cause the outer sleeve to expand diametrically
Implementation Method 3
the inner and outer sleeves having complimentary respective outer and inner tapered engagement faces
Data Source
AI summary
A high capacity radial-fit coupling bolt (or “expanding sleeve bolt”) has a pair of tapered sleeves about a shank of a bolt to which can be applied a tensioning load. An extrudable ring, or a compression ring, is interposed between a head nut or head flange at one end of the shank, and one end of an inner sleeve. A tensioning load is applied to the shank, the inner sleeve causing the outer sleeve to expand diametrically. At a preset load limit, the extrudable ring is extruded through at least one bore in a drive piston between the head nut and the extrudable ring, to allow shank to move relative to the inner sleeve until the tensioning load is fully applied. Alternatively, a drive member is provided between the head nut or head flange and the compression ring, and at a preset limit, the compression ring allows the shank to move relative to inner sleeve until the tensioning load is fully applied. The preset limit will typically correspond to the force required to fully expand the outer sleeve.