Circuit Breaker Conductor Overmolding With Internal Sprue Distribution
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Solution Overview
Problem
The existing conductor overmolding process in pyrotechnic current isolators faces challenges such as distortion and weld line formation due to cooling of plastic during injection molding, particularly at the arc formation area, leading to reduced strength and complexity in separation.
Innovation Solution
The method involves injecting plastic melt through a sprue from the cavity, using a sprue distributor to ensure the plastic remains hot during merging, and employing an umbrella-shaped or partially umbrella-shaped sprue manifold for even distribution, with options for the sprue to remain or be removed post-production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plastic melt is injected through multiple sprues into the conductor overmolding, then the filling speed and productivity are improved, but weld lines form at the merging areas reducing the strength
Solution Approach 1:
The injection system is segmented into a sprue distributor with multiple channels that distribute plastic melt to different regions of the conductor overmolding. This segmentation allows controlled filling paths that avoid excessive cooling at merge points, maintaining strength while enabling efficient multi-directional filling for improved productivity.
2Productivity
If the plastic melt travels a long distance from the sprue to the inside of the conductor overmolding, then the filling capability is improved, but the material cools significantly reducing the strength at the arc formation area
Solution Approach 1:
The sprue distributor acts as an intermediary component between the sprue and the conductor overmolding cavity. It distributes the plastic melt through multiple shorter channels, reducing the travel distance and minimizing cooling before the material reaches critical areas like the arc formation zone, thereby maintaining strength while preserving filling capability.
3Ease of manufacture
If the conductor overmolding is produced using external sprues, then the manufacturing process is simplified, but distortion and warpage occur during cooling
Solution Approach 1:
Instead of using external sprues where material flows from outside inward, the invention inverts the approach by positioning the sprue inside the cavity and using a sprue distributor to flow material outward to the conductor overmolding. This inversion creates more uniform cooling patterns and reduces differential shrinkage, minimizing distortion and warpage while maintaining ease of manufacture through integrated tooling.
4Ease of operation
If the sprue is positioned to allow easy removal, then the ease of operation is improved, but the connection strength between sprue and conductor overmolding is reduced
Solution Approach 1:
The sprue is extracted as a separate removable component from the conductor overmolding assembly. The sprue distributor design allows the sprue to be easily separated after injection, improving ease of operation for mold clearing and maintenance, while the distributed connection points and cooling channels maintain sufficient connection strength during the injection and cooling process.
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 reduces warpage and enhances the strength of the conductor overmolding connection, allowing for stable separation and additional functions like centering the circuit board, while minimizing weld lines and distortion.
Implementation Method 1
the plastic melt flows from the sprue to the actual conductor overmolding through a sprue distributor... the material on the inside of the conductor overmolding, i.e., at the edge of the cavity where the arc forms, is still relatively hot when it flows together from various channels of the sprue manifold
Implementation Method 2
The difficulty with this conductor overmolding process lies in the distortion of the conductor overmolding and the formation of weld lines in the area of the conductor overmolding that is particularly subject to pressure from a possible arc. This is because the material cools significantly on its way to the inside
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 1e~2a
AI summary
The aim of the invention is to produce a conductor (14) for a circuit breaker (11), said conductor having a printed circuit board (14c) to be separated between two conductor ends and additionally having a conductor encapsulation (15) that has a cavity (20) in which the printed circuit board (14c) is located. This is achieved in that a plastic melt is injected, via at least one gate (21), into an injection mold, in which the conductor (14) is located. According to the invention, the gating process (21) is carried out from out of the cavity (20), through which the conductor passes, wherein the plastic melt flows from the gate (21) to the actual conductor encapsulation (15) through a runner (22; 24a-24d; 26a, 26b). In the process, the gate (21) can remain in the completed circuit breaker (11).