Cylindrical Bonded Magnet Molding for Near-Sine Flux Waveforms
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Solution Overview
Problem
Existing methods struggle to produce cylindrical magnets with a magnetic flux density waveform close to a sine waveform, particularly for two-pole magnets, due to differences between the intended and actual magnetic field waveforms during orientation.
Innovation Solution
A mold design incorporating non-magnetic components and orientation magnets, where the first distance between the orientation magnets is shorter and tangent to the inner surface, and the second distance passes through the center, ensures a uniform magnetic field for molding a cylindrical bonded magnet with anisotropic rare earth magnetic powder and resin, achieving a sine or near-sine magnetic flux density waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional molding methods are used with standard mold configurations, then the manufacturing process is simple, but the magnetic flux density waveform cannot achieve a sine waveform due to field distortion
Solution Approach 1:
The patent applies local quality by creating non-uniform magnetic field distribution through specifically positioned orientation magnets. The first and second orientation magnets are placed at different distances from the mold center, generating a controlled magnetic field gradient that compensates for the natural field distortion in cylindrical geometries. This localized field adjustment enables sine waveform achievement without requiring complete redesign of the entire molding system.
Solution Approach 2:
The patent employs asymmetry in the mold structure by positioning the orientation magnets asymmetrically relative to the mold center. The first orientation magnet is located at a first distance from the center while the second orientation magnet is at a second distance, creating an intentionally asymmetric magnetic field configuration. This asymmetric arrangement counteracts the symmetric distortion that naturally occurs in cylindrical bonded magnets, enabling the production of sine waveforms that would be impossible with symmetric magnet placement.
2Manufacturing precision
If the distance between orientation magnets is reduced to achieve better field distribution, then the magnetic field uniformity improves, but the magnetic field strength decreases
Solution Approach 1:
The patent applies parameter changes by systematically varying the distances between orientation magnets and the mold, as well as the currents applied to each magnet. By optimizing these parameters, the patent achieves a balance where the magnetic field is sufficiently strong to orient the bonded magnet material properly while simultaneously maintaining uniform distribution across the mold cavity. This parameter optimization enables both high field strength and uniform distribution to coexist.
Solution Approach 2:
The patent employs dynamics by applying different currents to the first and second orientation magnets during the molding process. Rather than using a static, uniform current throughout, the system dynamically adjusts the magnetic field contribution from each magnet based on its position and the required field distribution. This dynamic current control allows the system to maintain both adequate field strength and uniform field distribution simultaneously.
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 method effectively produces cylindrical bonded magnets with a distortion factor of less than 15% relative to a sine curve, facilitating the production of magnets with a sine magnetic flux density waveform or a waveform close to it, suitable for various applications like small motors.
Implementation Method 1
performing molding to obtain a cylindrical bonded magnet by filling a region between the outer surface of the inner mold portion and the inner surface of the outer mold portion with a resin composition and molding the resin composition, while applying a magnetic field using the first orientation magnet and the second orientation magnet
Data Source
AI summary
A method of producing a cylindrical bonded magnet includes providing a mold including an inner mold portion, an outer mold portion, a first orientation magnet, and a second orientation magnet, and performing molding to obtain a cylindrical bonded magnet by filling a region between the outer surface of the inner mold portion and the inner surface of the outer mold portion with a resin composition. When viewed in a cross-section, a first distance is shorter than a second distance, the first distance is a straight line distance along a magnetic field application direction and is tangent to a circle defined by the inner surface of the outer mold portion, and the second distance is a straight line distance along the magnetic field application direction and passes through a center of a circle defined by the outer surface of the inner mold portion.