Cold Heading Semi-Tubular Rivet Manufacturing
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Solution Overview
Problem
The manufacturing of semi-tubular rivets with a peripheral groove and docking surface requires costly machining, which can damage the metal fibers and reduce fatigue strength.
Innovation Solution
A method involving cold heading operations to create a rivet with a countersunk head, tubular portion, and truncated cone external surface without machining, ensuring fiber orientation and improved metallurgical state, using heat treatment and plastic deformation to form docking surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If machining operations are used to create peripheral groove and docking surface, then manufacturing precision and surface quality are improved, but manufacturing cost increases and metal fiber integrity deteriorates
Solution Approach 1:
The patent combines multiple operations (creating peripheral groove, forming docking surface, and shaping the rivet body) into a single cold heading process. The matrix simultaneously forms the peripheral groove, creates the docking surface, and shapes the rivet in one operation, eliminating the need for separate machining steps and reducing manufacturing cost while maintaining surface quality.
Solution Approach 2:
The patent replaces traditional machining operations (mechanical removal of material) with cold heading (plastic deformation). Instead of using cutting tools to machine the groove and docking surface, the invention uses a forming matrix that plastically deforms the metal to create the desired geometry, preserving metal fiber integrity and reducing manufacturing complexity.
2Manufacturing precision
If machining operations are used to create peripheral groove and docking surface, then surface quality is improved, but fatigue strength deteriorates due to fiber breakage
Solution Approach 1:
The patent replaces machining operations with cold heading plastic deformation. The forming matrix plastically deforms the metal to create the peripheral groove and docking surface without removing material or breaking fibers. This substitution of forming for machining preserves the continuity of metal fibers, maintaining fatigue strength while achieving the required surface geometry.
Solution Approach 2:
The patent changes the physical state and properties of the metal during processing. By controlling the cold heading process parameters (temperature, pressure, deformation rate), the metal is plastically deformed into the desired shape without fiber breakage. The parameter changes in the forming process allow creation of complex geometries while preserving material integrity and fatigue properties.
3Ease of manufacture
If cold heading operations are used to create all features, then manufacturing cost decreases and fiber integrity is maintained, but manufacturing precision may deteriorate
Solution Approach 1:
The patent merges multiple precision-forming operations into a single cold heading process using a specially designed matrix. The matrix simultaneously creates the peripheral groove, forms the docking surface, and shapes the rivet body in one operation. This integration maintains precision because all features are formed concurrently under controlled conditions, avoiding the need for subsequent machining while ensuring consistent geometry.
Solution Approach 2:
The cold heading process is self-finishing in that it directly produces the final geometry without requiring additional machining operations. The forming matrix is designed to create the exact final shape including the peripheral groove and docking surface, eliminating the need for secondary operations and ensuring that the cold-headed features meet the required precision specifications.
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
This method reduces manufacturing costs, maintains fiber integrity, and enhances the rivet's fatigue strength by eliminating machining, allowing for efficient assembly of various materials like titanium and steel.
Implementation Method 1
by deformation of the material (cold heading) the following operations: creation of a portion with less diameter starting at the free end, creation of a substantially cylindrical hollow core in order to form a tubular portion
Implementation Method 2
The method is furthermore remarkable in that it comprises softening the material used by heat treatment. The hard metals used thus undergo a softening operation.
Implementation Method 3
A non-negligible technical effect of this method resides in the pre-orientation of the fibres of the metal which favours the deformation of the rivet during its installation.
Data Source
AI summary
The invention relates to a method for making a rivet (R), of the type comprising, by deformation of the material of a substantially cylindrical metal segment, the operations of preforming a milled head (100) at the end of a rod (200), characterised in that it comprises, by deformation of the material (cold stamping) the following operations: creating a portion with a lower diameter (210) from the free end; creating a substantially cylindrical hollow core (220) for forming a tubular portion; preforming the hollow core (220) as a truncated cone; performing the lower diameter outer surface as a truncated cone. The invention also relates to the rivet obtained by said method.