Expandable Rivet Element for Fiber Composite Attachment
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Solution Overview
Problem
Attaching rivet elements to components made of fiber composite materials often weakens the material by creating discontinuities, as existing methods require forming openings which compromise the material's strength.
Innovation Solution
A rivet element with an expandable mandrel section that can be pressed into the material without pre-drilling, using a die to expand and form a connection, eliminating the need for material openings and gluing, suitable for components in temporary 'doughy' states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If openings are formed in fiber composite materials for rivet attachment, then rivet elements can be attached, but material strength is significantly weakened due to discontinuities
Solution Approach 1:
The invention exploits temporary changes in the physical state of fiber composite materials during manufacturing processes (such as thermoplastic materials being soft or 'doughy' during forming) to enable rivet section insertion without permanent material removal. The material is in a temporarily modified state that allows deformation and rivet integration, then returns to its original strong state after cooling or curing.
Solution Approach 2:
The rivet element is inserted into the component during the component's manufacturing process, before the component fully cures or cools down. This preliminary insertion takes advantage of the material's temporarily softened state, allowing the rivet to be embedded without requiring subsequent opening formation that would weaken the cured material.
2Strength
If traditional riveting methods are used on cured fiber composite materials, then strong material is utilized, but openings must be formed which compromise material integrity
Solution Approach 1:
The invention merges the rivet attachment process with the component manufacturing process itself. The rivet element is inserted and formed simultaneously with or during the component's curing/coolidng process, eliminating the need for separate opening formation operations and subsequent attachment steps that would compromise material integrity.
Solution Approach 2:
The invention utilizes temporary parameter changes in the material state (soft/doughy state during manufacturing) to enable direct rivet insertion without opening formation. This eliminates the need for drilling, punching, or other opening creation methods that would create discontinuities in the finished component.
3Strength
If rivet elements are pressed into soft or doughy fiber composite materials, then no openings need to be formed, but the material must be in a temporary softened state
Solution Approach 1:
The rivet insertion is performed as a preliminary action during the component manufacturing process, while the material is still in its temporarily softened state. This timing ensures the material can be deformed to accommodate the rivet without requiring separate post-processing steps or compromising the final material properties.
Solution Approach 2:
The invention exploits the temporary parameter change in material state (from soft/doughy during manufacturing to cured/hard in final product) to enable rivet insertion without openings. The material's temporary deformability during manufacturing allows direct pressing, while the final cured state provides the required strength and integrity.
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 attachment of rivet elements to fiber composite materials without material weakening, providing protection against ejection forces and allowing for integration during component production, applicable to both short-fiber and long-fiber materials.
Implementation Method 1
the mandrel is expanded using a suitably shaped die to produce a rivet connection
Implementation Method 2
the rivet section of the rivet element engages behind the component with a region that has been folded at least once. In this way, particularly good protection against relatively high ejection forces can be achieved
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The element has a rivet portion (11) region-wise expandable towards a tip tapered circular cone-shaped mandrel by a mold and exhibiting a circular cross-section. The rivet portion comprises a set of tongue-shaped segments (13), and a funnel-shaped guide (17) is formed at a tip of the mandrel for guiding the mold. The rivet portion comprises a cylindrical section (19), and a flange section (21) radially extends with respect to the rivet portion and comprises a contact surface (23). The flange section comprises ribs (25) that function as anti-twist plates. Independent claims are also included for the following: (1) an assembly part (2) mold for mounting a rivet element (3) a method for mounting a rivet element.