Hot Crimp Segment Control for Stable Wire-to-Terminal Bonding
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Solution Overview
Problem
Existing methods for producing hot crimp connections face challenges such as inaccurate resistance and temperature measurements, inability to monitor the connection zone temperature directly, and unreliable control of contact force and sinking distance, leading to unstable and potentially weak electrical connections.
Innovation Solution
A method that divides the hot crimping process into multiple segments with specific parameter sets for current, contact force, and cut-off height, using height-dependent and energy/charge-dependent switching to ensure a stable and material-tight connection, including pre-forming and hot crimping phases with controlled thermal expansion and diffusion bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance measurement is used to monitor the connection zone, then electrical connection quality can be assessed, but the measurement is distorted by contact resistances and electrode resistances making direct measurement impossible
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring voltage at accessible points outside the connection zone and using it to calculate resistance indirectly. Instead of directly measuring the connection zone resistance (which is inaccessible), the system measures voltage across known resistances and uses these measurements to infer the connection quality through calculation, effectively using intermediate measurements to access the target parameter.
2Measurement precision
If temperature measurement is performed externally, then thermal state can be monitored, but the measurement spot is too large and covers both component and electrode making correction difficult
Solution Approach 1:
The patent extracts the temperature measurement function from the bulk material into the surface region by using surface-mounted thermocouples or infrared measurement. Instead of measuring temperature throughout the entire component volume (which would require a large measurement spot), the system isolates and measures only the surface temperature at the connection interface, extracting the relevant thermal information from the larger system.
3Measurement precision
If the entire sinking distance is recorded, then total electrode insertion can be measured, but no information is available about the temporal progression of the movement
Solution Approach 1:
The patent applies preliminary action by pre-defining switching heights for different process segments before the crimping operation begins. These predetermined height thresholds are established in advance to trigger segment transitions, allowing the system to capture temporal progression information by monitoring when specific height milestones are reached during the dynamic crimping process, rather than only measuring the final total distance.
4Reliability
If hot crimping is performed with high current and force, then stable electrical connection is achieved, but excessive melting may occur reducing connection quality
Solution Approach 1:
The patent segments the hot crimping process into multiple phases with different current and force levels. Instead of applying high current and force continuously (which would cause excessive melting), the system divides the process into sequential segments where parameters are optimized for each stage: initial contact establishment, heating phase, and final bonding phase. This segmentation allows achieving stable connections while preventing overheating and material degradation.
5Reliability
If multiple measurement parameters are monitored, then comprehensive process control is achieved, but the complexity of the control system increases
Solution Approach 1:
The patent implements multi-functionality by using a single integrated control system that simultaneously monitors multiple parameters (voltage, current, temperature, height, force) and performs multiple functions (process control, quality assessment, segment management). Instead of separate dedicated systems for each measurement, the control system universally handles all parameters through a unified architecture, reducing overall system complexity while maintaining comprehensive monitoring capabilities.
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 approach ensures a long-term stable and material-tight connection by optimizing each segment's parameters, compensating for material and power fluctuations, and preventing excessive melting, resulting in high manufacturing quality and traceability.
Implementation Method 1
The temperature development in the connection zone depends significantly on the force curve (1), the current curve (2), the starting height (4), the heat input in the pre-crimping phase (14)
Implementation Method 2
From the height difference between the thermal expansion stroke (5) and the starting height of the hot crimp (4), the energy input in segment 1 (10) can be deduced
Implementation Method 3
Current (2) and force (1) are adjusted in segments 2a + b (20 + 21) upon reaching the switching heights (7 + 8) to meet the requirements of creating a diffusion bond and/or partial melt bond
Data Source
Figure 1
AI summary
The invention relates to a method for producing a hot-crimp connection which is to be improved so that electrical connections between electrical conductors and an electrical terminal which are stable in the long term can be produced and fluctuations in quality can be precluded as far as possible. In order to achieve this aim the following metallurgically different steps are run through sequentially: segment 1: producing a first connection between the shaped part and the outer layer of the wires and/or stranded wires by a complete and/or partial eutectic melting process of the outer wires which have been freed by the concurrently proceeding compaction and/or predeformation of an insulating layer; segment 2: producing a diffusion bond and/or an at least partial fusion bond between the inner wires of the strand which have been freed from the insulating layer by the compaction; segment 3: currentless cooling of the hot-crimped bond, a switchover taking place between at least two successive segments after a segment-specific height position has been reached and/or energy/charge has been fed in.