Pierce Nut Torque Load via Eccentric Ring Elevation
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Solution Overview
Problem
Existing pierce nuts face challenges in achieving high torque load capacity, especially with harder and more brittle sheet metals, due to underestimation of sheet metal flowability and limitations in current design features such as radial ribs or projections.
Innovation Solution
A pierce nut design featuring a single ring-shaped elevation around the shank circumference, which provides a higher torque load capacity by minimizing material displacement and creating a form-fitting connection with the sheet metal, with a conical or convex cross-section and specific dimensions tailored to the sheet metal's hardness, along with a polygonal outer contour and an undercut shoulder for enhanced interlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple radial ribs or projections are used on the shoulder, then torque load capacity is intended to be increased, but material displacement becomes excessive and fixation reliability decreases
Solution Approach 1:
The elevation is segmented into multiple radial ribs or projections arranged circumferentially on the shoulder. This segmentation allows the total support area to be distributed, providing sufficient torque load capacity while reducing the material displacement required compared to a single large elevation, as each rib engages with the sheet metal locally rather than requiring bulk material displacement
Solution Approach 2:
The elevation features localized protrusions (ridges or ribs) at specific positions on the shoulder rather than a uniform surface. This local quality concentrates the supporting function at discrete points where torque transmission is needed, while minimizing overall material displacement. The local elevations create form-fit connections at critical stress points without requiring extensive material flow
2Strength
If a circular ring-shaped elevation is used, then torque load capacity is improved, but form-fit connection is insufficient allowing nut rotation
Solution Approach 1:
The elevation is designed with radial ribs or projections that create an asymmetric, non-circular contact pattern with the sheet metal. This asymmetry prevents rotational movement by creating uneven engagement points around the circumference, ensuring that the nut cannot rotate freely even under torque load. The non-uniform distribution of elevation features provides both torque support and rotational constraint
3Ease of operation
If the elevation cross-section is pointed for hard sheet metal, then penetration ability is improved, but manufacturing complexity increases
Solution Approach 1:
The cross-sectional parameters of the elevation are optimized to achieve the desired penetration ability. By carefully selecting the angle and dimensions of the radial ribs or projections, the elevation can effectively penetrate hard sheet metal while maintaining manufacturability. The parameters are tuned to balance penetration effectiveness with ease of production, avoiding excessively complex geometries
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
The design significantly increases the loosening moment and torque load capacity of the pierce nut, ensuring reliable fixation and prevention of nut rotation, even with harder sheet metals, while maintaining process reliability and cost-effectiveness.
Implementation Method 1
the flow processes of the sheet metal during pressing
Implementation Method 2
the shank part of the pierce nut that is stuck in the sheet metal is equipped with a non-round, mostly polygonal outer circumference
Implementation Method 3
elevations in the surface of the shoulder of the nut, against which the surrounding sheet metal material rests
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The pierce nut has a narrow shaft part relegated about a shoulder (9), where the shaft part is provided with a polygonal outer diameter formed of polygonal surfaces. An irregular, ring-shaped elevation (16) is arranged in the shoulder, where the elevation rotates about an axial direction. The elevation is arranged non-coaxial to a longitudinal axis of the pierce nut and arranged eccentrically and rotatably about the shaft part. The irregular ring-shape of the elevation is formed as a polygon or oval. An independent claim is also included for a pierce nut device with a metal sheet.