Magnetic Core Insulation via Composite Powder and Thermal Curing
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Solution Overview
Problem
Magnetic cores for induction hardening apparatuses have insufficient electrical insulating properties, leading to potential electric shorts and heat generation, limiting their use in applications requiring high durability.
Innovation Solution
An iron-based soft magnetic powder with an inorganic insulator coating and an epoxy resin containing a latent curing agent is compression molded and thermally cured, enhancing the magnetic core's electrical insulating properties by increasing its volume resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnetic cores are made from powder-metallurgy techniques with resin consolidation, then mass-production capacity is improved, but material strength deteriorates causing cracks and breaks
Solution Approach 1:
The patent uses composite magnetic powder particles consisting of magnetic powder particles consolidated with fluororesin particles. This composite structure combines the advantages of both materials: the magnetic powder provides necessary magnetic properties while the fluororesin provides binding and structural integrity, enabling both mass production and adequate strength.
Solution Approach 2:
The patent specifies precise particle size ranges for both magnetic powder particles (0.001-100μm) and fluororesin particles (1-100μm), and controls the consolidation ratio. By optimizing these parameters, the invention achieves a balance between mass-producible density and mechanical strength sufficient for cutting and mounting operations.
2Ease of manufacture
If magnetic cores use conventional resin consolidation, then manufacturing ease is improved, but electrical insulating properties deteriorate causing electric shorts and heat generation
Solution Approach 1:
The patent introduces fluororesin particles as an intermediary material between magnetic powder particles. The fluororesin serves dual functions: it consolidates the magnetic powder for easy manufacturing while simultaneously providing excellent electrical insulation properties, preventing electric shorts and heat generation.
Solution Approach 2:
The patent uses fluororesin in small quantities (1-100μm particles) as a sacrificial binding agent that provides necessary electrical insulation and structural consolidation during manufacturing and service, without compromising the overall magnetic properties or requiring additional insulation layers.
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 magnetic core exhibits improved electrical insulating properties, with a volume resistivity of 10^5 Ω·cm, maintaining high magnetic properties and mechanical strength, enabling broader application in induction hardening processes.
Implementation Method 1
the thermal curing is carried out at a temperature equal to or greater than the thermal curing initiation temperature of the thermosetting resin
Implementation Method 2
A magnetic core has the effect of accelerating induction heating by concentrating magnetic force lines on a workpiece
Implementation Method 3
has the effect of preventing a part requiring no hardening operation from being heated by shielding the part against magnetic force lines
Implementation Method 4
induction hardening apparatus
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
The present invention provides a magnetic core having insulating properties, and a method for manufacturing the magnetic core. Provided is a magnetic core manufactured by compression molding and subsequent thermal curing of an iron-based soft magnetic powder having a resin coating formed on particle surfaces thereof. The iron-based soft magnetic powder is one in which the particle surfaces have been coated with an inorganic insulator; the resin coating is an uncured resin coating formed by dry blending the powder with a thermosetting resin at a temperature equal to or greater than the softening point of the thermosetting resin and lower than the thermal curing initiation temperature of the resin; the compression molding is carried out by using a mold to produce a compression molded body; and the thermal curing is carried out at a temperature equal to or greater than the thermal curing initiation temperature of the thermosetting resin.