Blind-Rivet Contact Element for Crack-Free Stranded Conductor Joining
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Solution Overview
Problem
Existing electrical contact elements for stranded conductors, such as those using crimping methods, often result in crack formation and increased manufacturing costs due to the need for additional machining operations, leading to potential corrosion and reduced electrical carrying capacity.
Innovation Solution
An electrical contact element with a hollow-cylindrical connection region and a blind rivet system where the contacting body is irreversibly plastically deformable, allowing the strands of the conductor to be pressed against the inner wall without deforming the connection region, thereby avoiding cracks and ensuring reliable contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connection region is deformed during the crimping process to fix the conductor, then the conductor is securely connected, but cracks occur in the connection region leading to corrosion and reduced reliability
Solution Approach 1:
The solution separates the deformation function from the connection region by introducing a dedicated contacting body (mandrel) inside the connection region. The mandrel undergoes plastic deformation to press the conductor strands against the inner wall, while the connection region itself remains undeformed and free from cracks. This segmentation of functions resolves the contradiction by allowing secure connection through mandrel deformation without compromising connection region integrity.
Solution Approach 2:
The contacting body (mandrel) acts as an intermediary element between the crimping force and the conductor strands. Instead of deforming the connection region directly, the mandrel transmits the compressive force to press the strands against the inner wall surface. This intermediary mechanism achieves secure connection while preventing crack formation in the connection region, thereby eliminating corrosion risks.
2Object-affected harmful factors
If axial slits are added to the connection region to prevent crack formation, then crack formation is reduced, but manufacturing costs increase due to additional machining operations
Solution Approach 1:
The solution extracts the crack-prevention function from the connection region structure itself and transfers it to the contacting body (mandrel). Instead of modifying the connection region with axial slits through additional machining, the mandrel is designed with appropriate structural features that prevent crack formation during its deformation process. This extraction of function eliminates the need for costly additional machining operations while maintaining crack prevention.
Solution Approach 2:
Instead of modifying the connection region to prevent cracks (traditional approach), the invention inverts the approach by using an internal contacting body that prevents crack formation through its deformation characteristics. The mandrel's design and deformation behavior inherently prevent cracks, reversing the conventional wisdom of modifying the connection region structure to achieve crack prevention.
3Reliability
If the contacting body is irreversibly plastically deformed to press strands against the inner wall, then reliable electrical contact is achieved, but the contact element cannot be recycled
Solution Approach 1:
The solution applies the disposable principle to the contacting body (mandrel). The mandrel is designed as a low-cost, single-use component that undergoes irreversible plastic deformation to achieve reliable electrical contact. After use, the mandrel is discarded rather than recycled, accepting the loss of this inexpensive component to ensure reliable connection. The high value is placed on the reliable electrical contact, while the mandrel serves as a consumable element.
4Reliability
If the connection region diameter changes during the crimping process, then the conductor is secured, but the connection region becomes susceptible to corrosion
Solution Approach 1:
The solution segments the connection functions by using the mandrel for conductor fixation while keeping the connection region diameter constant. The mandrel's deformation provides the necessary securing force without causing diameter changes in the connection region. This segmentation prevents the creation of stress concentrations and microcracks that would otherwise make the connection region susceptible to corrosion, while still achieving reliable conductor fixation.
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 solution prevents crack formation and corrosion, ensuring reliable electrical contact while maintaining a stable connection region diameter, thus enhancing the long-term performance and reducing manufacturing costs.
Implementation Method 1
the contacting body is irreversibly plastically deformed. Such electrical contacting is reliable.
Implementation Method 2
the contacting body, or its outer surface, is arranged close to the inner wall of the connection region so that the strands are clamped firmly between the contacting body and the inner wall of the connection region
Data Source
AI summary
An electrical contact element is provided that includes a connection region for connecting an electrical conductor and a contact region for contacting a counter-contact element, wherein the connection region is substantially in the form of a hollow cylinder and includes an internal wall surface and an external wall surface, and wherein, in the connection region, a contacting body is arranged with which strands of the conductor can be pressed against the internal wall surface of the connection region. A method is also provided wherein the strands of the conductor to be connected are introduced into the connection region of the contact element and a mandrel of the blind rivet is pulled out on the contact side using riveting pliers. The contacting body is compressed in the process and as a result the strands are pressed against the internal wall of the connection region. Lastly, the mandrel breaks off at a defined breaking point.