Split Sleeve Interference Fit for Mid-Shaft Assembly
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Solution Overview
Problem
Existing methods for securing a sleeve onto a shaft in applications where the shaft end is not accessible are inefficient due to the need for machining, connectors, or welding, and often result in vibration or damage from temperature cycling and lateral movement.
Innovation Solution
A split sleeve apparatus comprising two arcuate portions with fingers and dowel rods that expand and contract to create an interference fit on the shaft without additional connectors or machining, allowing assembly on a mid-portion of the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a one-piece sleeve is heated and shrunk onto the shaft end, then the sleeve is securely connected to the shaft without connectors, but the method cannot be used where the shaft end is not accessible
Solution Approach 1:
The sleeve is divided into two separate arcuate portions that can be assembled independently onto the shaft. Each portion has fingers that interlock with the other portion, allowing the split sleeve to be installed on mid-portion of the shaft without requiring access to the shaft ends, while maintaining the secure interference fit connection
2Ease of operation
If a two-piece sleeve is assembled on a mid-portion of the shaft, then assembly is possible without shaft end access, but machining and connectors are required which increases cost and time
Solution Approach 1:
The sleeve is segmented into two arcuate portions with interlocking fingers that can be assembled on the shaft mid-portion without requiring shaft end access or additional connectors
Solution Approach 2:
The sleeve portions are heated to expand their inner diameter, allowing them to be fitted onto the shaft. Upon cooling, the sleeve portions contract to create an interference fit, securing the assembly without requiring machining or additional fasteners
3Reliability
If locking collars with set screws are used to secure the sleeve, then the sleeve can be positioned on the shaft, but the set screws vibrate loose or shear in environments with temperature cycling or lateral movement
Solution Approach 1:
The sleeve portions are heated to expand their inner diameter for assembly, then allowed to cool and contract, creating an interference fit that securely connects the sleeve to the shaft without set screws or locking collars that could vibrate loose
Solution Approach 2:
The mechanical connection method using set screws and locking collars is replaced with a thermal expansion and contraction process that creates a permanent interference fit, eliminating the need for fasteners that are susceptible to vibration and temperature cycling
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
Enables secure and efficient installation of a sleeve onto a mid-portion of a shaft without access to the ends, reducing costs and time by eliminating the need for machining and connectors, while maintaining a smooth finish for rotation against bearings.
Implementation Method 1
The first and second arcuate portions are fabricated from a material having heat expansion characteristics that allow the material to expand upon being heated and to contract upon being cooled
Implementation Method 2
Once the sleeve is properly positioned, the sleeve is allowed to cool, thereby shrinking the sleeve onto the shaft and creating an interference fit with the shaft
Data Source
AI summary
An apparatus and method for assembling a split sleeve onto a shaft. The split sleeve apparatus provides a first and second arcuate portion with each having a partial cylindrical configuration. The first and second arcuate portions have at least one finger extending circumferentially outward from their opposing ends. The at least one finger from each of the first and second arcuate portions complementarily engage one another to form a continuous cylinder. At least one aperture extends longitudinally through the at least one finger of the first and second arcuate portions. A dowel rod extends through the at least one aperture for connecting the first and second arcuate portions to form the cylinder. The first and second arcuate portions are fabricated from a material having heat expansion characteristics that allow the material to expand when heated during assembly and to contract when cooled creating an interference fit with the shaft.