Tape-Wound Toroidal Core Forming With Low-Stress Segmented Winding
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Solution Overview
Problem
Existing methods for producing tape-wound toroidal cores are inefficient and prone to mechanical damage due to the brittleness of amorphous and nanocrystalline alloys after heat treatment, limiting their use in high-frequency applications.
Innovation Solution
A novel apparatus and method involving adjustable winding mandrels, multiple tape coils, and separating devices to form multi-layer tape rolls with varying widths, accompanied by insulation and tensioning, to create a closed ring structure with minimal mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tape-wound toroidal cores are produced using conventional winding methods, then the production process is simple, but the mechanical robustness is poor due to brittleness after heat treatment
Solution Approach 1:
The core is divided into multiple segments with longitudinal gaps instead of being a continuous closed ring. This segmentation reduces mechanical stress concentration and prevents crack propagation, significantly improving mechanical robustness while maintaining magnetic circuit functionality through the gaps
Solution Approach 2:
The tape is pre-stressed and pre-formed into the toroidal shape before final heat treatment. This preliminary action ensures the core structure is already optimized to withstand thermal expansion and mechanical stresses during the heat treatment process, preventing deformation and improving mechanical robustness
2Reliability
If heat treatment is applied to achieve optimal magnetic properties, then magnetic performance is improved, but mechanical brittleness increases
Solution Approach 1:
The segmented structure with longitudinal gaps allows for controlled thermal expansion and stress distribution during heat treatment. Each segment can expand independently, reducing internal stresses and preventing catastrophic failure, thus maintaining both magnetic properties and mechanical strength
Solution Approach 2:
The heat treatment parameters (temperature, time, atmosphere) are optimized and controlled to achieve the desired magnetic properties while minimizing mechanical brittleness. The segmentation allows for more flexible parameter optimization since each segment responds independently to thermal changes
3Productivity
If continuous tape rolling is used to form closed ring cores, then production efficiency is high, but mechanical damage occurs due to stress concentration
Solution Approach 1:
Instead of forming a continuous closed ring, the tape is wound to create segments with longitudinal gaps. This segmentation eliminates stress concentration points that would occur at the joints of a continuous ring, preventing mechanical damage while maintaining production efficiency through automated winding processes
Solution Approach 2:
Rather than joining tape ends to form a continuous ring (conventional approach), the invention inverts the approach by deliberately leaving gaps and creating segments. This inverted methodology eliminates the weak joint points and stress concentrations inherent in continuous ring construction
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
Enhances the production efficiency and mechanical robustness of tape-wound toroidal cores, enabling their use in higher frequency ranges by minimizing mechanical damage and optimizing the magnetic properties.
Implementation Method 1
two rotationally drivable winding mandrels arranged at a distance from each other for winding up the tape, wherein the winding mandrels are selectively rotationally drivable about in each case a first axis of rotation or about a common second axis of rotation
Implementation Method 2
The winding is followed by a heat treatment, in which the magnetic properties of the core are adjusted or achieved, of between approx. 200° C. and 600° C., depending on the alloy
Implementation Method 3
the magnetic flux generated during current flow through the electrical conductor of the coil is bundled, guided and the inductance increased with little loss
Implementation Method 4
The magnetic flux is thus distributed across individual, mutually separate flows in the individual sheets, in which only smaller eddy currents can thus form, the total power loss of which is significantly lower than in a solid material
Data Source
AI summary
A method for producing a tape-wound toroidal core includes: ⋅providing a soft-magnetic tape on two tape reels, ⋅unwinding the tape and winding the tape onto two winding mandrels to form a multilayer first tape roll, wherein, after in each case several layers, a separating plate is inserted into the first tape rolls that have formed, ⋅reducing the distance between the winding mandrels until the first tape rolls touch each other, ⋅unwinding the tape and winding up the tape to form a multilayer second tape roll, which wraps around the first tape rolls, by rotating the winding mandrels about a common second rotation axis, ⋅severing the tape rolls in steps to form a plurality of tape sections, ⋅picking up at least one reel and placing the reel onto the tape sections, ⋅reshaping free ends of the tape sections and connecting the ends of the tape sections to form a closed ring.