Single-Side Temporary Fastener for Constant Pressure Clamp-Up
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Solution Overview
Problem
Conventional clamping devices fail to maintain a consistent clamping force during assembly processes, especially when dealing with materials that undergo creep or extrusion, such as adhesives or sealants, leading to reduced stack height and clamping pressure over time.
Innovation Solution
The development of single side temporary fasteners with biasing members, including a rotationally constrained collet body and threaded screw, along with a memory ring and articulating sleeves, which maintain constant pressure by translating and rotating to accommodate material changes and distribute clamping force evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional clamp is used to clamp work pieces, then initial clamping force is achieved, but clamping force decreases over time due to material creep and adjunct extrusion
Solution Approach 1:
The clamp incorporates a biasing member (spring) that provides dynamic adjustment capability. As the material stack undergoes creep or adjunct extrusion causing stack height reduction, the biasing member automatically translates the collet body to maintain constant clamping force throughout the bonding duration
Solution Approach 2:
The system changes the physical state of the clamping mechanism from static to dynamic by introducing a biasing member that converts elastic potential energy into mechanical work, allowing the clamp to adapt to changing stack height conditions and maintain force parameter stability
2Reliability
If clamp is tightened too much to prevent slipping, then clamp stability is improved, but all glue may ooze out leaving insufficient material to bond work pieces
Solution Approach 1:
The biasing member automatically adjusts the clamping force to the optimal level needed to prevent slipping without excessive force. The spring force self-regulates to maintain sufficient adhesive material in the stack, eliminating the need for operator judgment and preventing adhesive extrusion
3Stability of the object's composition
If biasing members are added to maintain constant pressure, then clamping force stability is improved, but device complexity increases
Solution Approach 1:
The biasing member is nested within the existing fastener structure, with the spring housed inside the collet body or housing. This compact arrangement adds the constant pressure function while minimizing increase in overall device complexity and size
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
These fasteners ensure consistent clamping pressure over time, minimizing material loss and maintaining the desired stack height, even with materials that creep or extrude, by using biasing elements to resist reactive translation and distribute force effectively.
Implementation Method 1
the inclusion of biasing members, whether internal, external or combinations thereof, to the basic fastener, and operate to preserve, or at least minimize, a decrease in an established clamping force in the material stack
Implementation Method 2
a threaded screw for rotationally engaging with the collet body, which by way of anti-rotation devices associated therewith and with the auxiliary structure, is rotationally constrained but is free to axially translate
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 anti-rotation 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.