Non-Projecting Blind Rivet Nut With Radial Setting Expansion
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Solution Overview
Problem
Existing blind rivet nuts with countersunk heads project and create interfering edges when set in smooth bores, which is undesirable and requires additional effort, especially in thin workpieces, and existing solutions to avoid this, such as countersinking, are disadvantageous due to increased complexity and instability.
Innovation Solution
A blind rivet nut design with a setting region that can be enlarged radially when a force is applied, allowing for a non-projecting or almost non-projecting setting by forming a friction-fit or form-fit with the workpiece, eliminating the need for a projecting head and reducing the risk of interfering edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blind rivet nut with a countersunk head is used, then the setting is secure, but the head projects and creates an interfering edge on the workpiece surface
Solution Approach 1:
The setting region of the blind rivet nut is designed to be dynamically deformable under setting force. When the blind rivet nut is set, the setting region plasticaily deforms and enlarges radially to form a friction-fit or form-fit with the workpiece, securing the connection while eliminating the projecting head that would create an interfering edge.
Solution Approach 2:
The external dimensions of the setting region are changed during the setting process through radial enlargement. This parameter change allows the setting region to adapt to the workpiece bore, creating a secure fit without maintaining a fixed projecting head geometry that would interfere with the workpiece surface.
2Object-generated harmful factors
If a countersinking is provided prior to setting the blind rivet nut, then the interfering edge is avoided, but additional effort and complexity are required
Solution Approach 1:
The function of creating a recess to accommodate the head is extracted from the pre-setting process (countersinking) and transferred to the setting process itself. The setting region of the blind rivet nut performs the dual function of both the fastener and the head-recess creator, eliminating the need for separate countersinking operations.
Solution Approach 2:
The blind rivet nut performs its own head accommodation function through the deformable setting region that enlarges radially during setting. This self-service mechanism eliminates the need for external preparation (countersinking) and integrates the head-recess creation into the fastening operation itself.
3Object-generated harmful factors
If a countersinking is provided prior to setting the blind rivet nut, then the interfering edge is avoided, but stability is reduced in thin workpieces
Solution Approach 1:
The setting region undergoes parameter change through radial enlargement during setting, adapting to the actual bore dimensions in the thin workpiece. This dynamic adaptation provides stability by creating a secure friction-fit or form-fit without requiring material removal (countersinking) that would compromise the structural integrity of thin workpieces.
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 enables the blind rivet nut to be securely fixed in a workpiece without projecting edges, improving stability and reducing the need for additional preparation like countersinking, while maintaining efficient production and flexibility in material choice.
Implementation Method 1
The compression region (115) is configured so that, when a first force acting on the compression region (115) is exceeded, the compression region (115) forms a closing bead (116)
Implementation Method 2
The setting region (110), on the free axial portion (112) which faces away from the thread region (120), is configured so that, with respect to an external dimension of the setting region (110), the setting region (110) is enlarged at least in a radial direction when a second force acting on the setting region (110) is exceeded
Data Source
AI summary
A blind rivet nut for incorporating a thread in a clearance of a workpiece and/or for connecting two workpieces. The blind rivet nut includes a setting region, a thread region having an internal thread in portions of the thread region, and a compression region arranged between the thread region and the setting region. The compression region forms a closing bead when a first force acting on the compression region is exceeded. The setting region has an axial portion which faces the compression region and a free axial portion which faces away from the compression region and from the thread region. When a second force acting on the setting region is exceeded, the free axial portion which faces away from the thread region is enlarged at least in a radial direction with respect to an external dimension of the setting region.