Atomized Additive Injection for Oxidation-Safe NdFeB Jet Milling
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Solution Overview
Problem
Conventional methods for adding liquid additives during the jet milling process of sintered NdFeB alloy magnet production face issues such as oxidation of the powder, aggregation of additives, blockages, and poor mixing uniformity, leading to inconsistent magnetic properties and reduced efficiency.
Innovation Solution
A device and method involving a storage barrel, weighing bucket, and fluid atomization nozzle with a blind flange for precise addition of liquid additives as a spray, minimizing oxidation and ensuring better mixing homogeneity by using inert gas for air replacement and precise control of additive dosage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional funnel addition method is used, then device complexity is reduced, but oxidation of powder occurs and mixing uniformity deteriorates
Solution Approach 1:
The patent introduces an inert gas (nitrogen or argon) atmosphere in the powder container to prevent oxidation of the magnetic alloy powder during the additive addition process. The inert gas displaces oxygen, creating a protective environment that eliminates the harmful oxidation effect while maintaining a relatively simple sealed container structure.
Solution Approach 2:
The patent uses a fluid atomization nozzle as an intermediary device to add liquid additives. The nozzle atomizes the liquid additive into fine droplets that are carried by inert gas flow directly into the powder, enabling uniform distribution without direct contact between the additive and external environment, thus preventing oxidation while achieving good mixing uniformity.
2Device complexity
If conventional funnel addition method is used, then device complexity is reduced, but mixing uniformity deteriorates
Solution Approach 1:
The patent changes the physical state and distribution parameters of the additive by using fluid atomization. The liquid additive is transformed into fine droplets through atomization, dramatically increasing the surface area and improving dispersion uniformity in the powder. This parameter change achieves superior mixing uniformity while the overall device structure remains relatively simple.
Solution Approach 2:
The patent employs pneumatic principles by using inert gas flow to carry and distribute the atomized liquid additive throughout the powder container. The gas flow pattern ensures uniform distribution of additives, achieving high mixing precision through fluid dynamics rather than complex mechanical mixing devices.
3Ease of operation
If additives are added through opening hole, then ease of operation is improved, but blockage of opening occurs and cleaning difficulty increases
Solution Approach 1:
The fluid atomization nozzle serves as an intermediary that prevents direct contact between the additive and the container wall. The nozzle is designed to spray additives into the center of the powder mass, avoiding wall contact and subsequent blockage. The nozzle itself can be easily removed and cleaned due to its simple tubular structure with a spray hole.
Solution Approach 2:
The addition operation is extracted from the container wall opening and moved to a removable nozzle inserted through the opening. This allows the nozzle to be easily detached, cleaned, or replaced without disassembling the container, significantly improving maintenance ease while maintaining operational simplicity.
4Manufacturing precision
If mixing time is extended to improve uniformity, then mixing precision is improved, but productivity deteriorates
Solution Approach 1:
The liquid additive is pre-atomized into fine droplets before being introduced to the powder. This preliminary atomization action creates a distribution pattern that requires minimal mixing time to achieve uniformity. The additives are already in an optimal state for rapid dispersion, eliminating the need for extended mixing periods and thus maintaining high productivity.
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 solution achieves improved mixing uniformity and reduced oxidation, resulting in higher-quality sintered NdFeB magnets with lower C element content deviation, increased yield, and simplified maintenance, while shortening the mixing cycle and enhancing the mechanical and magnetic properties.
Implementation Method 1
a fluid atomization nozzle (19) located at the end of the connection pipe (4)
Implementation Method 2
The blind flange (5) further includes openings (5-1) for air replacement, and an inert gas is introduced into the interior of the powder container (6) via the openings (5-1) of the blind flange (5)
Data Source
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AI summary
The present invention refers to a device and a method for the addition of liquid additives in the form of a spray during a jet milling step in a process for the manufacture of sintered NdFeB alloy magnets. The device comprises: a storage barrel for the liquid additive; a weighing bucket which is in fluid communication with the storage barrel and is adapted for weighing a predetermined amount of the liquid additive; a powder container to accommodate NdFeB alloy material prior to or after jet milling, wherein the powder container includes an opening that is plugged with a blind flange; a connecting pipe, which is in fluid communication with the weighing bucket and passes through an opening of the blind flange into the interior of the powder container; and a fluid atomization nozzle located at the end of the connection pipe.