Memory Shape Bushings for Fastener-Free Installation
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Solution Overview
Problem
Existing bearings and bushings installation methods using press-fits, fasteners, and shrinking mechanisms often result in fit tolerance issues, increased weight, size, labor, and stress or fatigue on the components and structures.
Innovation Solution
Utilizing a memory-shaped material, such as Nitinol or Nickel-Titanium alloy, which is cooled to compress into a martensitic shape for installation and then heated to expand into an austenitic shape for secure fitting against a structure without the need for fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If press-fits, fasteners, and shrinking mechanisms are used to install bearings and bushings, then secure attachment is achieved, but weight, size, and device complexity increase
Solution Approach 1:
The patent removes fasteners and complex installation mechanisms from the bearing and bushing assembly. The memory shape material itself provides the attachment function through its expansion capability, eliminating the need for separate fastening components and reducing overall weight.
Solution Approach 2:
The patent utilizes temperature-induced parameter changes in the memory shape material. By cooling the material below its transformation temperature, it transitions to a compressed martensitic state for easy installation, then heating it above the transformation temperature causes expansion to the austenitic state for secure attachment, achieving reliable fixation without additional weight.
2Reliability
If press-fits and fasteners are used to install bearings and bushings, then secure attachment is achieved, but manufacturing precision and fit tolerance issues worsen
Solution Approach 1:
The patent employs a dynamic attachment mechanism where the memory shape material transitions between compressed and expanded states. This dynamic capability allows the bearing or bushing to adapt to slight variations in hole dimensions and surface irregularities during installation, achieving secure attachment without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The patent performs preliminary cooling of the memory shape material to its martensitic state before installation. This preliminary action reduces the material's dimensions, allowing it to be easily inserted into the bearing or bushing and against the structure surface. Subsequent heating then achieves the secure expanded attachment, compensating for any fit tolerance variations.
3Reliability
If fasteners and complex installation mechanisms are used, then secure attachment is achieved, but labor and installation time increase
Solution Approach 1:
The patent implements a self-service attachment mechanism where the memory shape material performs both the installation and securing functions. The material's inherent shape memory capability eliminates the need for external fasteners, alignment tools, or complex installation procedures. Installation simply requires cooling, positioning, and heating, dramatically reducing labor time while maintaining secure attachment.
4Ease of manufacture
If traditional installation methods are used, then bearings and bushings can be installed, but stress and fatigue damage increase
Solution Approach 1:
The patent inverts the traditional installation approach by using compression during installation rather than expansion. The memory shape material is cooled to a compressed martensitic state for easy insertion, then heated to expand and secure itself. This inversion eliminates the high installation stresses and fatigue damage associated with traditional press-fits and fastener tightening, while still achieving strong attachment.
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 lightweight, compact designs with reduced stress and fatigue, eliminating the need for additional fasteners and enabling easier maintenance by providing a secure, fastener-free attachment.
Implementation Method 1
a temperature of the memory shaped material is lowered below a first temperature to compress the memory shaped material into a martensitic shape
Implementation Method 2
the temperature of the memory shaped material is raised above a second temperature to expand the memory shaped material into an austenitic shape against the surface of the structure
Implementation Method 3
the memory shaped material is installed against a surface of a structure while the memory shaped material is in the martensitic shape. In yet another step, the temperature of the memory shaped material is raised above a second temperature to expand the memory shaped material into an austenitic shape against the surface of the structure
Data Source
AI summary
The disclosure provides bearing sleeves or bushings made of memory shape material, and processes for installing such bearing sleeves or bushings. In one process, inner and outer surfaces of a bearing sleeve, made of a memory shape material, may be compressed at least one first temperature. A bearing may be inserted in a cavity of the bearing sleeve, and the bearing sleeve may be disposed adjacent to a surface of a structure, while the bearing sleeve is at the at least one first temperature. The inner and outer surfaces of the bearing sleeve may be expanded, at least one second temperature, to abut against the bearing and the surface of the structure.