Spring-Loaded Threaded Fastener for Adjustable Preload Access
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Solution Overview
Problem
Conventional threaded fasteners face challenges in providing adjustable preload and easy access for applications where fasteners are not readily accessible, and they often require tools for disassembly, which can be cumbersome or damaging to delicate components.
Innovation Solution
A fastener assembly comprising a headed stud, a threaded sleeve, and a compression spring, where the sleeve can move relative to the stud, allowing for adjustable preload and easy disassembly without tools, with features like rotational locking and a depth stopper to prevent sleeve movement during torque application, and a method for setting preload by rotating the fastener assembly to align marks indicating the desired torque angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional threaded fasteners are used, then the connection is secure and preload can be applied, but the fasteners are difficult to access and adjust when not readily accessible
Solution Approach 1:
The fastener is divided into separate components: a headed stud that remains fixed in the workpiece, and a removable threaded sleeve that can be independently accessed and manipulated. This segmentation allows the threaded portion to be accessed for adjustment without requiring access to the head of the fastener, resolving the accessibility problem while maintaining structural integrity.
Solution Approach 2:
The threaded sleeve acts as an intermediary element between the headed stud and the external environment. It provides the threaded interface for adjustment and preload control while being removable and accessible, allowing operators to adjust the fastener without direct access to the stud head or internal components.
2Ease of operation
If conventional threaded fasteners are used, then the connection is secure, but disassembly requires tools that can be cumbersome or damaging to delicate components
Solution Approach 1:
The threaded sleeve is extracted as a separate, removable component from the headed stud. This allows the threaded portion to be removed and replaced without applying torque or force to the headed stud or the workpiece, eliminating the risk of damaging delicate components during disassembly and reassembly operations.
Solution Approach 2:
The threaded sleeve incorporates self-contained adjustment mechanisms including ribs that engage with slots in the workpiece to prevent rotation during torque application, and visual indicators that show when proper preload is achieved. This self-service design eliminates the need for external tools or complex adjustment procedures, allowing simple hand-operated installation and removal.
3Ease of operation
If the sleeve is made removable for easy access, then accessibility improves, but the connection stability may be compromised
Solution Approach 1:
The headed stud is permanently installed and secured in the workpiece before the threaded sleeve is attached. This preliminary action ensures that the fixed reference point is established first, and the removable sleeve is then configured relative to it. The sleeve includes pre-formed ribs that engage with pre-drilled slots in the workpiece, ensuring proper alignment and rotational prevention before the final tightening operation.
Solution Approach 2:
The threaded sleeve combines multiple functions into a single component: it provides the threaded interface for engagement, incorporates ribs for rotational locking, includes visual indicators for preload verification, and serves as the interface for torque application. This merging of functions maintains connection stability while enabling easy removal and reinstallation without compromising the integrated performance of the fastening system.
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 assembly and disassembly of components without tool access, providing adjustable preload and visual indication of torque, suitable for applications requiring temporary separation, vibration resistance, and pressure management, such as in pressure relief valves.
Implementation Method 1
a compression spring positioned around the shaft, between the first head and the second head
Implementation Method 2
a compression spring positioned around the shaft, between the first head and the second head
Implementation Method 3
The threaded sleeve includes at least one slot configured to receive the rib of the second head, for rotationally locking the threaded sleeve
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A fastener assembly (10,10a,10b,110,210) includes a stud (12,12a,12b), a threaded sleeve (16,16a,116,216), and a compression spring (18,18a). The stud includes a shaft (28,28a) with a first head (20,20a) at one end and a second head (46) at an opposite end of the shaft, both heads with opposing bearing surfaces (32,34). The threaded sleeve (16,16a,116,216) is disposed about the shaft (28,28a). The threaded sleeve (16,16a,116,216) includes external threads and a tubular interior with an inwardly projected shoulder (49). The compression spring (18,18a) is disposed about the shaft (28,28a) inside the threaded sleeve (16,16a,116,216), with a first end bearing against a shoulder (49) of the threaded sleeve and a second end bearing against a bearing surface (34) of the second head (46). The spring (18,18a) urges the sleeve against the bearing surface (32) of the first head (20,20a). The assembly (10,10a,10b,110,210) can maintain a preload between two components (1,2) while allowing the components (1,2) to be separated, and can also be used as a pressure limiter.