Magnetic Encoder Manufacturing with High-Density Ferrite Rubber
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Solution Overview
Problem
Magnetic rubber molded articles with high coercivity and residual magnetic flux density are challenging to produce due to the deterioration of magnetic properties when a large amount of ferrite magnetic powder is added, leading to reduced moldability and coercivity during the vulcanization process.
Innovation Solution
A method involving the vulcanization of a magnetic rubber composition comprising nitrile rubber and ferrite magnetic powder with a compressed density of 3.5 g/cm3 or more, mixed and kneaded within specific temperature and time ranges, and molded in a magnetic field to enhance coercivity and residual magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of ferrite magnetic powder is added to improve magnetic properties, then residual magnetic flux density is improved, but coercivity deteriorates due to intense shear force during long-term kneading
Solution Approach 1:
The patent changes the physical parameters of the ferrite magnetic powder by specifying a compressed density of 3.5 g/cm³ or more. This parameter change allows the magnetic powder to maintain high coercivity even when present in large amounts (700-1500 parts by mass) during the vulcanization process, resolving the contradiction between improving residual magnetic flux density and maintaining coercivity
Solution Approach 2:
The patent applies a magnetic field during the vulcanization molding process as a preliminary action to orient the ferrite magnetic powder particles before the rubber matrix fully sets. This preliminary orientation prevents the intense shear force during kneading from randomizing particle alignment, thereby preserving coercivity while allowing high magnetic powder content
2Quantity of substance
If a large amount of ferrite magnetic powder is added to improve magnetic properties, then residual magnetic flux density is improved, but moldability deteriorates
Solution Approach 1:
The patent specifies a compressed density of 3.5 g/cm³ or more for the ferrite magnetic powder, which optimizes the particle packing and flow characteristics. This parameter change enables the rubber composition to maintain favorable moldability even with high magnetic powder content (700-1500 parts by mass), resolving the contradiction between improving residual magnetic flux density and maintaining moldability
3Adaptability or versatility
If nitrile rubber is used to balance oil resistance, heat resistance and price, then cost-performance is improved, but magnetic properties deteriorate compared to other rubber types
Solution Approach 1:
The patent creates a composite material system combining nitrile rubber with high-compressed-density ferrite magnetic powder (3.5 g/cm³ or more). This composite approach compensates for the inherently lower magnetic properties of nitrile rubber by optimizing the magnetic powder characteristics and formulation, achieving both cost-performance balance and improved magnetic properties including high coercivity and residual magnetic flux density
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 magnetic encoders with high coercivity and residual magnetic flux density, improving sensor precision and reducing size while maintaining favorable moldability.
Implementation Method 1
molding and vulcanizing the magnetic rubber composition in a mold to which a magnetic field is applied to provide the magnetic rubber molded article
Implementation Method 2
vulcanizing a magnetic rubber composition having favorable moldability
Data Source
AI summary
Provided is a method for a magnetic encoder having a magnetic body comprised of a magnetic rubber molded article, comprising a mixing step of mixing and then kneading a nitrile rubber (A), a ferrite magnetic powder (B) and a vulcanizing agent (C) to provide a magnetic rubber composition; and a molding step of molding and vulcanizing the magnetic rubber composition in a mold to which a magnetic field is applied to provide the magnetic rubber molded article, wherein a content of the ferrite magnetic powder (B) is 700 to 1500 parts by mass based on 100 parts by mass of the nitrile rubber (A); and a compressed density of the ferrite magnetic powder (B) is 3.5 g/cm3 or more. According to this method, a magnetic encoder having a magnetic body with high coercivity and residual magnetic flux density can be produced by vulcanizing a magnetic rubber composition having favorable moldability.