Pierce Nut Groove Segmentation for High-Strength Sheet Metal
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Solution Overview
Problem
Existing pierce nuts fail to provide sufficient torque resistance and pull-through resistance when used with high-strength sheet metal, leading to increased punching force requirements, tool damage, and alignment errors.
Innovation Solution
A pierce nut design featuring an abutment surface with an undercut pilot and a countersunk groove without active undercuts, optimized with specific angles and geometries to reduce sheet deformation and enhance form-fit interlock, along with anti-rotation means for improved torque resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing pierce nut designs are used with high-strength sheet metal, then the structure is simple and easy to manufacture, but torque resistance and pull-through resistance are insufficient
Solution Approach 1:
The grooves in the pierce nut are divided into multiple segments (first groove, second groove, third groove) with different orientations and functions. The first groove has an inclined surface for initial deformation, the second groove has a vertical surface for form-fit interlock, and the third groove provides additional locking. This segmentation allows the nut to achieve high strength through coordinated action of multiple simplified groove structures rather than a single complex structure.
Solution Approach 2:
Different portions of the grooves have different local geometries optimized for specific functions. The inclined surfaces in the first groove facilitate sheet metal deformation, while the vertical surfaces in the second and third grooves provide form-fit interlock. This local quality differentiation enables each groove segment to perform its specific function efficiently, achieving high overall strength without requiring the entire structure to be complex.
2Force
If existing pierce nut designs are used with high-strength sheet metal, then the manufacturing process is simple, but punching force requirements increase and tool damage risk increases
Solution Approach 1:
The first groove with its inclined surface performs preliminary deformation of the sheet metal during the punching process. By gradually deforming the metal along the inclined surface before final insertion, the required punching force is reduced compared to direct insertion. This preliminary action prepares the metal for easier insertion into the subsequent grooves, lowering the overall punching force requirement and reducing tool damage risk.
3Manufacturing precision
If existing pierce nut designs are used with high-strength sheet metal, then the design is straightforward, but alignment errors between pierce nut and punching die increase
Solution Approach 1:
The angles and geometries of the groove surfaces are specifically optimized parameters. The inclined surfaces are designed with specific angles that facilitate controlled deformation, while the vertical surfaces provide precise form-fit interlock. These parameter optimizations improve alignment precision by ensuring the sheet metal deforms and locks in the correct position, reducing alignment errors between the pierce nut and punching die without requiring complex alignment mechanisms.
4Strength
If existing pierce nut designs are used with high-strength sheet metal, then the structure is simple, but the joint strength and resistance to pull-through forces are insufficient
Solution Approach 1:
The locking mechanism is segmented into multiple grooves with different functions: the first groove for initial deformation, the second groove for primary form-fit interlock, and the third groove for additional locking. This segmentation distributes the load-bearing function across multiple simpler structures rather than requiring a single complex locking mechanism, achieving high joint strength through coordinated action of multiple groove segments.
Solution Approach 2:
Each groove segment has locally optimized geometry for its specific function. The inclined surfaces in the first groove facilitate deformation, while the vertical surfaces in the second and third grooves provide form-fit interlock. This local quality differentiation enables efficient load distribution across the joint, achieving high overall joint strength without requiring the entire groove structure to be uniformly complex.
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 achieves increased joint strength and resistance to pull-through forces while reducing punching force requirements and minimizing tool damage, maintaining high torque resistance and pull-through resistance even with high-strength sheet metal.
Implementation Method 1
the sheet is plastically deformed and pressed into the groove and beneath the two undercut portions, thereby to achieve a form-fit interlock between the nut and metal sheet
Implementation Method 2
Pierce nuts should be attached to the metal sheet in such manner that they resist both pull-through forces and torque
Data Source
AI summary
A pierce nut (1) for attachment to a plastically deformable metal sheet (4) has an abutment surface (14) adapted to abut against the metal sheet (4), an undercut pilot (11) protruding relatively to the abutment surface (14), and a countersunk groove (16a, 16b) which is formed in the abutment surface (14) and at least partly surrounds the pilot (11). The groove (16a, 16b) is without active undercuts facing the pilot (11). The groove comprises an inner groove (16a) and an outer groove (16b) and a ridge (17) located therebetween.