Magnetic Circuit Loop Cutting to Reduce Burrs and Material Waste
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Solution Overview
Problem
The existing methods for manufacturing magnetic circuit loops for three-phase transformers result in material waste and high production costs due to the generation of burrs and irregularities during the cutting process, which lead to short circuits and undesirable spaces between layers.
Innovation Solution
A method involving the cutting of a magnetic strip into half-rollers with complementary shapes, followed by unwinding and rewinding to form loops with specific orientation adjustments, reducing material waste and costs by optimizing the machining process to create frustoconical delimitation surfaces and transitioning from circular to rectangular contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser cutting is used to adjust strip width upstream of winding, then the strip can be pre-cut to fit the mandrel, but burrs and irregularly formed excess material appear along the cutting edge causing short circuits and unwanted spaces between layers
Solution Approach 1:
The harmful cutting operation is extracted and relocated from the strip processing stage to the finished loop stage. Instead of cutting the strip to width before winding, the patent winds the full-width strip around the mandrel first, then removes excess material after winding. This separates the winding operation from the cutting operation, eliminating burr formation during the critical pre-winding cutting stage.
Solution Approach 2:
The strip is prepared in advance by winding it around the mandrel at full width before any cutting occurs. This preliminary winding action establishes the correct geometric relationship between the strip and mandrel, allowing subsequent cutting to be performed on the already-positioned loop rather than on the loose strip, thereby avoiding burr formation.
2Manufacturing precision
If chamfering edges by machining, electroerosion, or water jet cutting is performed after winding, then surface defects from laser cutting are avoided, but expensive material waste is induced and the process becomes time-consuming
Solution Approach 1:
The cutting parameters are changed by performing the cutting operation at a different stage in the process. Instead of cutting the strip before winding or chamfering after winding, the patent cuts the loop at its natural position after winding, using the mandrel itself as a guide. This eliminates the need for additional chamfering operations and minimizes material waste while maintaining edge quality.
Solution Approach 2:
The mandrel serves multiple functions: it guides the winding of the strip, defines the final loop geometry, and serves as a reference for the cutting operation. This multi-functionality eliminates the need for separate chamfering tools and operations, reducing both material waste and process time while maintaining edge surface quality.
3Reliability
If chamfering operations are performed after winding to remove excess material, then edge compatibility is improved, but production time and costs increase
Solution Approach 1:
The cutting operation is merged with the winding operation by performing cutting immediately after winding while the loop is still on the mandrel. This combines two operations that were previously separate (winding then chamfering), eliminating the need for additional production steps and improving efficiency while maintaining edge compatibility through the mandrel-guided cutting process.
Data Source
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AI summary
A method for manufacturing magnetic circuit loops for a multi-phase transformer from a magnetic strip, the method comprising the steps of: a) providing a magnetic strip of constant width in the form of a roll wound around a first circular mandrel and extending along a longitudinal axis; b) producing a first and a second half-roll by cutting the roll into sections, the two half-rolls having a longitudinal axis each comprising a respective boundary surface which is formed once it is separated from the other half-roll, the roll being cut slantwise at an angle θ relative to the longitudinal axis, such that the first half-roll constitutes a first loop having its boundary surface outwardly oriented relative to its longitudinal axis, while the boundary surface of the second half-roll is oriented opposite to the boundary surface of the first half-roll; c) aligning the first and second half-rolls to form two loops, including at least one sub-step of reversely unwinding and rewinding the second half-roll on a mandrel.