Single-Side Temporary Fastener With Constant Clamping Pressure
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Solution Overview
Problem
Conventional single side temporary fasteners fail to maintain a consistent clamping force during assembly processes, especially when materials like adhesives or sealants are used, as they can ooze out or experience material creep, leading to reduced clamping pressure over time.
Innovation Solution
The development of a constant pressure single side temporary fastener incorporating a rotationally constrained collet body with biasing elements, such as memory rings and sleeves, which maintain clamping force by distributing pressure evenly and accommodating changes in geometry, preventing material loss and ensuring consistent attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional clamp is used to clamp work pieces, then the work pieces can be held together, but the clamp loosens and slips due to material creep and adjunct extrusion, resulting in loss of clamping force
Solution Approach 1:
The clamp incorporates a dynamic adjustment mechanism that automatically compensates for material creep and adjunct extrusion. The biasing member continuously applies force to maintain clamping pressure, and the adjustment mechanism moves the clamping surface to accommodate changing stack heights, ensuring consistent clamping force throughout the bonding process
Solution Approach 2:
The clamp includes a feedback system where the biasing member senses changes in stack height due to material displacement and automatically adjusts the clamping force. This closed-loop mechanism ensures that clamping pressure remains constant even as the material stack changes during the bonding process
2Force
If the clamp is tightened too much to prevent slipping, then clamping force is maintained, but all adhesive material oozes out leaving insufficient material to bond the work pieces
Solution Approach 1:
The dynamic adjustment mechanism allows the clamp to adapt to the actual material stack height. By continuously monitoring and adjusting to the changing stack height as adhesive is displaced, the clamp applies optimal pressure that prevents slipping while maintaining sufficient adhesive material for bonding
Solution Approach 2:
The clamp modifies the clamping pressure parameter dynamically based on the material stack conditions. The biasing member and adjustment mechanism work together to maintain clamping force within an optimal range that prevents both slipping and excessive adhesive extrusion
3Device complexity
If a conventional clamp is used, then the structure is simple, but it cannot maintain constant pressure due to material creep and adjunct extrusion
Solution Approach 1:
The clamp incorporates dynamic elements including a biasing member and adjustment mechanism that automatically respond to material creep and adjunct extrusion. These additions increase structural complexity but enable the clamp to maintain constant clamping force throughout the bonding process
Solution Approach 2:
The clamp includes self-adjusting features where the biasing member and adjustment mechanism automatically compensate for material displacement without external intervention. The system serves itself by detecting and responding to changes in stack height, maintaining reliable clamping force consistency
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 effectively maintains a consistent clamping force over time, even with material creep or extrusion, ensuring reliable attachment and preventing loss of adhesive material, thus enhancing efficiency in production environments like the aerospace industry.
Implementation Method 1
a biasing element, such as a spring or elastomeric member, which is configured to maintain the clamping force
Implementation Method 2
incorporating a rotationally constrained collet body with biasing elements, such as memory rings and sleeves, which maintain clamping force by distributing pressure evenly
Data Source
AI summary
A single side temporary fastener (SSTF) capable of maintaining a clamping force in a material stack subject to material creep or adjunct extrusion during clamp up processes is disclosed. The SSTF comprise a rotationally constrained but freely translatable collet body that is disposed within an auxiliary structure such as a fastener housing. A fastener comprises the aforementioned collet body, which at least partially translates within the aforementioned auxiliary structure, and further comprises a threaded screw for rotationally engaging with the collet body, which by way of an antirotation means associated therewith and with the auxiliary structure, is rotationally constrained but is free to axially translate. Constant clamping pressures are made possible in such embodiments by the inclusion of at least one biasing element between compression force transmitting elements and/or assemblies of the fasteners.