Twisted Polylobular Press-In Fastener for Higher Press-Out Force
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Solution Overview
Problem
Conventional connecting elements for pressing into components, especially in materials like aluminum, face low press-out force due to material being pushed away and not available for subsequent ribs, leading to incomplete anchoring and low retention.
Innovation Solution
A connecting element with a shank featuring a polylobular cross-section that is twisted along its length, where regions with smaller and larger radii are offset, preventing material displacement and allowing for improved anchoring by maintaining material availability for all ribs, enhancing press-out force and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional connecting elements with straight shanks are pressed into aluminum components, then the material flows into transverse knurling, but the material is largely sheared off and pushed away, resulting in low press-out force
Solution Approach 1:
The shank is given an asymmetric polylobular cross-section with lobes of different sizes (first lobe larger than second lobe) that creates an asymmetric material displacement pattern during pressing, allowing material to flow into knurling without being completely pushed away from subsequent anchoring zones
Solution Approach 2:
The invention introduces a new dimension by varying the cross-sectional shape along the length of the shank through the polylobular design with different lobe sizes at different positions, creating zones with different material displacement characteristics that work together to improve both material flow and anchoring
2Reliability
If conventional connecting elements are pressed into components, then the first transverse-knurling turns are taken up by material, but subsequent ribs cannot access material that has been pushed away, resulting in incomplete anchoring
Solution Approach 1:
Different sections of the shank are given different cross-sectional characteristics through the polylobular design, with specific lobe sizes and positions optimized for local material displacement and anchoring requirements, ensuring each rib can effectively engage material in its specific zone
3Force
If the press-out force depends on the tolerance of the core hole in conventional connecting elements, then manufacturing precision requirements increase, but the press-out force remains insufficient
Solution Approach 1:
The invention changes the geometric parameters of the shank cross-section by implementing a polylobular design with varying lobe sizes and positions, fundamentally altering the material interaction mechanics to achieve higher press-out force that is less sensitive to core hole tolerance variations
Data Source
AI summary
The invention relates to a connecting element for pressing into or embedding in a component, having a shank which extends along a longitudinal central axis of the connecting element, wherein the shank is provided with ribs extending in a radial direction with respect to the shank and wherein the shank has, at least partially, a polylobular cross section, wherein the periphery of the polylobular cross section is convexly curved along its entire length, is arranged between a circumscribed circle and an inscribed circle, and, as seen in the radial direction, has regions with a larger radius and regions with a smaller radius, wherein an angular position of the regions with a smaller radius and of the regions with a larger radius changes along the shank, as seen along the longitudinal central axis.