Plastic Hollow Rivet Forming via Lateral Wall Heating
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Solution Overview
Problem
Existing rivet connections using plastic tubular rivets often result in insufficient linking of the rivet head to the remaining tube, leading to reduced strength, visual appeal, and functionality due to a thin molten layer and high shear rate, particularly when attempting to plasticize the entire rivet head volume.
Innovation Solution
A rivet connection method involving a hollow plastic rivet with a tubular component that is heated and compressed laterally to form an outwardly bulging region without introducing energy directly into the second component, using lasers to plasticize the tubular component's lateral wall, which then forms a strong connection with the second component, reducing thermal stress on the component, especially when used with carbon black particles for enhanced energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire rivet head volume is plasticized by heating the tubular end, then the rivet head can be formed, but a joint line with insufficient linking is created due to minor thickness of the molten layer and high shear rate
Solution Approach 1:
The patent applies local quality by heating only the lateral wall of the tubular component rather than the entire rivet head volume. This localized heating approach creates a plasticized region with sufficient material thickness that, when compressed, forms an outwardly bulging region without creating joint lines or insufficient linking. The lateral wall heating ensures the molten layer has adequate thickness to prevent shear edge formation while still achieving proper rivet head formation.
Solution Approach 2:
The patent transitions from heating the end of the tubular component (one-dimensional approach) to heating the lateral wall (two-dimensional approach). This dimensional change allows energy to be introduced into a larger volume of material, creating a more substantial plasticized region that can be compressed to form the rivet head without creating joint lines. The lateral wall heating approach fundamentally changes the geometry of the heated zone to resolve the linking strength issue.
2Temperature
If energy is introduced directly into the second component by infra-red heating of the rivet end, then the rivet can be heated, but thermal stress on the second component increases
Solution Approach 1:
The patent extracts the heating function from direct contact with the second component. Instead of heating the rivet end which would transfer thermal energy to the second component, the invention introduces energy laterally into the tubular component's wall. This extraction of the heating zone from the component interface eliminates the primary source of thermal stress on the second component while still achieving the necessary plastification for rivet head formation.
Solution Approach 2:
The lateral wall of the tubular component serves as an intermediary medium for energy transfer. By introducing laser energy into the lateral wall rather than directly heating the rivet end in contact with the second component, the patent uses the tubular material itself as a mediator to achieve plastification without directly thermalizing the second component. This intermediary approach reduces harmful thermal effects on the connected component.
3Strength
If the tubular rivet is deformed by pulling on the pin, then the two components are connected, but the rivet head may be insufficiently linked to the remaining tube
Solution Approach 1:
The patent changes the physical state parameters of the tubular component by plasticizing the lateral wall through lateral energy introduction. This parameter change (from solid to plasticized state) allows the material to flow and form an outwardly bulging region that creates superior mechanical interlocking with the second component. The plasticized state enables the material to conform and bond more effectively, improving both connection strength and linking reliability compared to cold deformation methods.
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 achieves a strong and visually appealing connection with reduced thermal stress on the second component, such as a circuit board, by ensuring uniform plastification and preventing shear edges, thereby improving the quality and simplicity of the riveting process.
Implementation Method 1
the lateral wall of the tubular part, on the circumference thereof adjacent the first opening, is heated and compressed... the tubular component, on account of the lateral introduction of energy into the lateral wall, can be plasticized directly above the second component
Implementation Method 2
The energy of the laser or lasers can be particularly well absorbed, and the plastification can be accelerated, when the plastics material contains carbon black particles
Implementation Method 3
upon compression, the plasticized material may flow and form the outwardly bulging region... part of the outwardly bulging region contacts the third surface of the second component
Implementation Method 4
When cooling down, only parts of the outwardly bulging material dissipate part of the energy stored therein on account of the plastification to the second component. The stress on the second component on account of a thermal input is thus substantially less than in the case of infra-red heating of the rivet end
Data Source
AI summary
A rivet connection has a hollow rivet composed of plastics material and connects a first component to a second component. The first component has a first surface and the second component has a second and third surface. The first surface and the second surface bear on one another. The second component has a first opening between the second and the third surface. The hollow rivet has a tubular component having a lateral wall, a cavity, a first end and a second end. Part of the tubular component is disposed in the first opening of the second component. The second end of the tubular component protrudes beyond the second component. The lateral wall of the tubular component adjacent the first opening of the second component is heated and compressed and configures an outwardly bulging region. Part of the outwardly bulging region contacts the third surface of the second component.