Solid Self-Piercing Rivet Manufacturing via Radial Clamping
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Solution Overview
Problem
Current methods for producing punch rivets are cost-intensive and lack consistent dimensional accuracy, particularly in automated processing, due to material loss and complexity in machining and cold-forming processes.
Innovation Solution
A method involving radially adjustable shaped pieces to clamp and form a wire into a pseudo-liquid state, achieving high dimensional accuracy through pre-upsetting and axial positioning, with a tool featuring conically guided shaped pieces and spring-loaded components for precise clamping and forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If machining processes (turning) are used to produce punch rivets, then dimensional accuracy is improved, but manufacturing cost increases due to material loss
Solution Approach 1:
The invention changes the physical state parameter of the wire material by applying intense axial force to create a pseudo-liquid state, allowing the material to flow and fill the die cavity completely, thereby eliminating material loss while maintaining high dimensional accuracy
Solution Approach 2:
The invention replaces traditional mechanical machining processes (turning) with a forming process that uses axial force to plasticize and form the rivet in one step, eliminating the need for subtractive machining and associated material waste
2Loss of substance
If cold-forming technology with multiple process steps is used, then material loss is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention combines multiple process steps (upsetting, contouring, and groove formation) into a single integrated forming operation where the wire is clamped between shaped pieces and formed in one continuous action, significantly reducing device complexity
Solution Approach 2:
The die is segmented into multiple radially adjustable shaped pieces that can be independently positioned to create the complex rivet geometry including grooves and contours, allowing complex shapes to be formed without complex tooling
3Loss of substance
If cold-forming technology with multiple process steps is used, then material loss is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The shaped pieces are designed to be radially adjustable rather than fixed, allowing them to dynamically adapt to the wire material during forming and ensure precise dimensional accuracy through optimal contact and support during the forming process
Solution Approach 2:
The invention applies intense axial force to create a pseudo-liquid state in the wire material, enabling complete filling of the die cavity and precise replication of the rivet geometry, achieving high dimensional accuracy that was previously only attainable through machining
4Manufacturing precision
If radially adjustable shaped pieces are used to clamp and form the wire, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The shaped pieces are designed to be radially adjustable rather than fixed, allowing them to dynamically adapt to the wire material during forming and ensure precise dimensional accuracy through optimal contact and support during the forming process
Solution Approach 2:
The shaped pieces automatically position and clamp the wire through their radial adjustability and conical guidance, eliminating the need for complex external positioning mechanisms and achieving precision through self-alignment
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
Enables cost-effective production of solid punch rivets with consistent dimensional accuracy, reducing material loss and process complexity while ensuring precise axial positioning and clamping.
Implementation Method 1
the wire material is briefly put into a pseudo-liquid state, whereby the material in the formed by the fittings perimeter contour flows and fills them
Implementation Method 2
the shaped pieces are prestressed via spring elements in the direction of the largest cone diameter of the frame element
Implementation Method 3
the shaped pieces are moved axially in the direction of the smallest cone diameter of the frame element, as a result of which the shaped pieces are placed radially against the piece of wire via the conical shape of the passage
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~3d
AI summary
The invention relates to a method for producing a solid punch rivet, in which a trimmed wire piece (8) is deformed by means of a tool (1) comprising a punch (4) and a matrix (2), wherein the wire piece (8) is clamped between shaped parts (33) which are arranged in a jaw like manner and are radially engageable, and which form the peripheral rivet contour (321) and comprise at least one annular groove (322) forming an undercut, and subsequently an axial force is applied to the wire piece (7) at the two ends thereof via a respective pressure pin (24, 46), which results in the wire material fluently filling the peripheral rivet contour formed by the shaped pieces (33). The invention further relates to a tool for producing a solid punch rivet by said method.