Fastening Element With Free-Wall Guide Recess for Low Insertion Force
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Solution Overview
Problem
Existing fastening elements for connecting a carrier part to an add-on part face challenges with maintaining high clamping effect and pull-out force, especially with larger tolerances in the carrier part's clamping recess, while requiring low insertion force and being prone to inward bending of expanding cheeks.
Innovation Solution
The fastening element features expanding cheeks with radially outward free walls between the guide recess and slide-on beads, allowing the shank section to enter freely and enabling a favorable lever ratio for high clamping forces with low insertion forces, even if the expanding cheeks bend inward, and includes a locking part with a foot section acting at a distance from the support plate for enhanced clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the expanding cheeks are tightly dimensioned to achieve high clamping effect, then the pull-out force increases, but the insertion force required increases significantly
Solution Approach 1:
The fastening element is divided into functional segments: a holding part with expanding cheeks for clamping, a locking part for actuation, and a guide recess for controlled insertion. This segmentation allows the insertion path to be guided freely through the holding part, reducing insertion force while maintaining clamping effectiveness.
Solution Approach 2:
The guide recess acts as an intermediary structure that mediates between the locking part and the expanding cheeks. It provides a force-free insertion path for the locking part, allowing the expanding cheeks to be actuated without requiring excessive insertion force, thus resolving the contradiction between tight dimensioning and low insertion force.
2Ease of manufacture
If the expanding cheeks are made with larger tolerances to ease manufacturing, then the clamping effect decreases, but the insertion force required also decreases
Solution Approach 1:
The expanding cheeks are designed with elastic properties, allowing them to dynamically adapt to tolerance variations in the clamping recess. The cheeks can elastically deform to accommodate larger tolerances while still achieving effective clamping, thus maintaining manufacturing ease without sacrificing clamping performance.
Solution Approach 2:
The design allows for parameter changes in the expanding cheeks, particularly in their radial dimension, to accommodate tolerance variations. By allowing the cheeks to vary within a tolerance range and still achieve functional clamping, the design prioritizes ease of manufacture while maintaining adequate clamping effect.
3Manufacturing precision
If the shank section passes through a tightly dimensioned through-hole, then the positioning precision increases, but the expanding cheeks may bend inward reducing clamping effectiveness
Solution Approach 1:
The guide recess is designed to provide a force-free insertion path for the locking part before the expanding cheeks are actuated. This preliminary action allows the locking part to be inserted without causing the expanding cheeks to bend inward, preventing deformation while still achieving precise positioning through the guide structure.
Solution Approach 2:
The design converts the potential harm of tight through-hole dimensioning (which could cause cheek bending) into a benefit by providing a guided, force-free insertion path. The guide recess ensures that the locking part passes through without exerting harmful forces on the expanding cheeks, while still achieving the positioning precision needed for effective clamping.
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 design achieves a high clamping effect and pull-out force with relatively low insertion force, maintaining stability even with inward bending of the expanding cheeks and larger tolerances, while providing a favorable lever ratio for effective engagement.
Implementation Method 1
the shank section also enters between the expanding cheeks essentially free of forces after passing through the guide recess if this is due to a relatively tightly dimensioned through-hole are bent inwards compared to their rest position
Data Source
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AI summary
In the case of a fastening element (1) which has a holding part (2) formed by a support plate (4) and by expanding cheeks (5), and a locking part (3) which is guided displaceably in the holding part (2), free walls (16) which are adjacent to the support plate (4) are formed, said free walls being set back radially outwards from a guide wall (13) which, in order to guide the locking part (3), bears flush against the shaft section (6). As a result, the locking part (3) can be pushed along in a manner substantially free from forces, even when the expanding cheeks (5) are bent inwards, and with use being made of a better lever ratio to expand the expanding cheeks (5) as far as radially inwardly projecting slide-on beads (14) formed on the expanding cheeks (5).