Twisted Polylobular Press-Fit Fastener for Stronger Anchoring
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Solution Overview
Problem
Conventional connecting elements with radial ribs face challenges in achieving high anchoring forces, especially in materials like aluminum, due to material displacement and misalignment of knurling grooves, leading to reduced pressing force and secure anchoring.
Innovation Solution
A connecting element with a polylobular shaft cross-section that twists along its length, featuring areas with varying radii that are angularly offset, preventing material displacement and allowing subsequent ribs to engage more effectively, thereby enhancing anchoring force and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional fasteners with radial ribs are pressed into aluminum components, then the ribs engage the material, but the material is pushed away radially and sheared off, reducing anchoring effectiveness
Solution Approach 1:
The shaft cross-section is designed as polylobular with asymmetric radius variations instead of a conventional circular or uniform cross-section. The circumferential ribs have varying distances from the shaft centerline, creating asymmetric engagement points that prevent material from being uniformly pushed away and enable continuous material flow into the knurling grooves during pressing.
Solution Approach 2:
The invention introduces a longitudinal dimension to the rib arrangement by varying the angular position of the smaller-radius regions along the shaft length. This creates a three-dimensional helical pattern of engagement points, ensuring that ribs at different longitudinal positions engage material that has not yet been displaced, thereby preventing material loss and improving anchoring.
2Force
If the shaft has a polylobular cross-section with fixed angular positions, then the structure is simple to manufacture, but the knurling grooves align and reduce extrusion force
Solution Approach 1:
The shaft cross-section employs asymmetric polylobular geometry where the smaller-radius regions are positioned at different angular locations along the shaft length. This asymmetric arrangement prevents alignment of knurling grooves while maintaining manufacturability through conventional forming processes.
Solution Approach 2:
The angular position of the smaller-radius regions varies along the longitudinal axis of the shaft, creating a dynamic pattern of engagement points rather than a static fixed pattern. This dynamic arrangement ensures continuous material flow and maximizes extrusion force while the overall polylobular structure remains suitable for standard manufacturing.
3Reliability
If conventional fasteners are pressed in, then initial ribs engage the material, but subsequent ribs find no material available due to radial displacement, reducing overall anchoring
Solution Approach 1:
The invention adds a longitudinal dimension to the rib engagement pattern by varying the angular position of smaller-radius regions along the shaft length. This creates a helical distribution of engagement points that ensures each rib encounters fresh material, preventing the material exhaustion problem and improving both anchoring reliability and pressing efficiency.
Solution Approach 2:
The polylobular cross-section geometry is pre-configured with varying angular positions of smaller-radius regions before pressing. This preliminary geometric arrangement ensures that material flow paths are optimized in advance, allowing subsequent ribs to automatically engage undisturbed material without requiring additional adjustments during the pressing process.
Data Source
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AI summary
The invention relates to a connecting element for pressing in or embedding in a component, having a shaft which extends along a center longitudinal axis of the connecting element, wherein the shaft is provided with ribs extending in the radial direction relative to the shaft, and wherein the shaft has, at least in some portions, a polylobular cross-section, the circumference of the polylobular cross-section being convexly curved over the entire length thereof, being arranged between a circumscribed circle and an inscribed circle and, viewed in the radial direction, having regions with a larger radius and regions with a smaller radius, wherein, viewed along the center longitudinal axis, an angular position of the regions with a smaller radius and of the regions with a larger radius changes along the shaft.