Clinch-In Fastener Installation for Thin Sheet Assembly
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Solution Overview
Problem
Existing fastening methods for thin sheets, such as in consumer electronics, are inefficient and costly, as they require machining away material to achieve the necessary thickness for self-clinching fasteners, or involve impractical methods like laser welding or adhesives, which can cause material burn through or long cure times.
Innovation Solution
A clinch-in fastener system using novel tooling and installation methods that allows fasteners to be installed in very thin workpieces by displacing sheet material against structural features, minimizing marking, and utilizing a spring-loaded plate to stabilize the fastener during installation, reducing the need for separate equipment and operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known self-clinching fasteners are used, then the fastener can be securely installed, but the sheet material must be relatively thick to accommodate the displacer, undercut, and shank
Solution Approach 1:
The fastener is divided into separate components: a fastener body with internal threads and a separate displacer member. This segmentation allows the displacer to be removed after installation, leaving only the compact fastener body in the thin sheet material, thereby reducing the required material thickness while maintaining secure installation.
Solution Approach 2:
The displacer member, which is necessary for installation but increases the required thickness, is extracted from the final assembled state. The displacer is used only during installation to deform the sheet material around the fastener, then removed, allowing secure fastener installation in thinner materials.
2Weight of moving object
If material is machined away to reduce thickness everywhere except fastening locations, then the component weight and stature are reduced, but the manufacturing cost increases
Solution Approach 1:
The fastener installation process itself creates the necessary localized deformation in the sheet material without requiring preliminary machining operations. The displacer member deforms the material during installation, eliminating the need for separate machining steps to create recesses or thickenings at fastening locations.
3Manufacturing precision
If the fastener shank interferes with the hole side, then tight tolerances are required for proper installation, but manufacturing complexity increases
Solution Approach 1:
The installation tool performs preliminary actions to prepare for fastener installation: it holds the fastener in position, applies initial forcing to overcome interference fit, and maintains positioning during the deformation process. This preliminary action by the tool compensates for tolerance variations without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The installation tool acts as an intermediary that mediates between the fastener and the sheet material. It applies controlled forcing to overcome the interference between the shank and hole, and holds the fastener in position during material deformation, thereby accommodating tolerance variations.
4Ease of operation
If installation force is applied to press the fastener in, then the fastener can be installed, but marking or blemishes may appear on the opposite side of the panel
Solution Approach 1:
The displacer member, which concentrates installation force, is extracted from the final assembled state. During installation, the displacer applies force locally to deform material around the fastener body, but once removed, no displacer remains to create marking on the opposite side. The fastener body itself is compact and does not extend far enough to cause marking.
Solution Approach 2:
Instead of applying continuous axial force through the fastener length (which would cause marking), the installation process inverts the approach: force is applied locally at the installation location by the displacer to deform material around the fastener body, while the fastener body itself remains compact and does not transmit marking-causing forces to the opposite side.
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 system enables efficient assembly of thin sheets with minimal material deformation and no visible blemishes, reducing costs and improving aesthetic appearance by eliminating the need for secondary finishing operations and separate installation equipment.
Implementation Method 1
a spring-loaded plate within an installation tool... The force also holds the fastener in the hole during clinching
Implementation Method 2
the installation tool rotationally presses material surrounding the hole and deforms it onto a top surface of the shank to clinch the fastener to the workpiece
Data Source
AI summary
A clinch-in fastener with a cylindrical body having a top, a bottom, sides and an axial internal bore. The fastener has a single shank at the bottom end of the body having a top surface orthogonal to the bore and a chamfer tapering to the bottom of the body. The top surface of the shank is adapted for receiving the cold flow of material surrounding a receiving hole of a workpiece. The shank may have a plurality of notches in its outermost edge that extend through both the top surface of the shank and the chamfer. The bore of the fastener extends completely through the fastener body from top to bottom and may be threaded. A fastener installation system having a tool with means for affixation to a rotary and vertically reciprocal element of an industrial machine. The tip of the tool has a distal end face with at least one arcuate displacer adapted for deforming a workpiece as the tool rotates and is pressed against the workpiece. A bore within the tip holds a fastener installed by the tool. The displacer is vertically and radially tapered along an arcuate ridge centered about the axial bore. The width of the displacer is also tapered to a point.