Fluid Dynamic Bearing Housing Bracket Adhesion Gap Control
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Solution Overview
Problem
Fluid dynamic bearing apparatuses in spindle motors face challenges with adhesive strength between the housing and bracket, particularly under increased impact from higher disk capacities, where thermal expansion during adhesive curing affects the adhesion gap, leading to insufficient adhesive strength.
Innovation Solution
The solution involves controlling the adhesion gap by matching the linear expansion coefficients of the housing and bracket between 0.5 and 2.0, using suitable adhesives like anaerobic, ultraviolet curable, or epoxy-based adhesives, and incorporating materials such as polyphenylene sulfide resin with carbon fibers and inorganic compounds to maintain high adhesive strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal expansion of housing and bracket is not controlled during adhesive curing, then adhesion gap varies leading to insufficient adhesive strength, but controlling linear expansion coefficients limits material selection
Solution Approach 1:
The patent controls the linear expansion coefficients of housing and bracket materials to maintain a specific ratio (0.5-2.0), thereby minimizing adhesion gap variation during thermal curing process. This parameter control ensures sufficient adhesive strength while allowing selection from various material combinations that meet the expansion ratio requirement.
Solution Approach 2:
The invention directly addresses thermal expansion effects by matching the linear expansion coefficients of housing and bracket materials. By ensuring their ratio falls within 0.5-2.0, the patent compensates for dimensional changes during adhesive curing, preventing adhesion gap variation that would compromise bonding strength.
2Quantity of substance
If disk capacity is increased to meet storage requirements, then more magnetic disks are integrated, but impact force from drops increases requiring higher adhesive force
Solution Approach 1:
The patent prepares the housing and bracket materials in advance with controlled linear expansion coefficients before assembly. By pre-selecting materials that meet the expansion ratio requirement (0.5-2.0), the invention ensures optimal adhesive bonding conditions are established before the component ever experiences drop impacts, thereby proactively strengthening the connection against future mechanical shocks.
Solution Approach 2:
The invention changes the material parameters (linear expansion coefficients) of housing and bracket to maintain a specific ratio range. This parameter optimization ensures that during adhesive curing, minimal gap variation occurs, resulting in stronger initial bonding that can withstand the increased impact forces from higher capacity disk configurations.
3Ease of manufacture
If adhesion gap is set to predetermined width, then mounting is simplified, but thermal expansion during curing changes the gap width affecting adhesive performance
Solution Approach 1:
The patent compensates for thermal expansion effects during adhesive curing by selecting housing and bracket materials with linear expansion coefficients in a specific ratio (0.5-2.0). This ensures that the predetermined adhesion gap width remains relatively stable during the heating process, maintaining both manufacturing simplicity and gap control precision.
Solution Approach 2:
The invention optimizes the material parameters (linear expansion coefficients) to maintain a controlled ratio, thereby minimizing thermal dimensional changes during curing. This allows the adhesion gap to be set to a predetermined width during assembly while maintaining that width throughout the curing process, achieving both ease of manufacture and manufacturing precision.
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
This approach ensures high adhesive strength between the housing and bracket, minimizing adhesion gap variations during heating, thus enhancing the reliability and durability of the fluid dynamic bearing apparatus, even under increased disk capacities.
Implementation Method 1
a radial bearing portion which supports a rotational member by a fluid membrane formed in a bearing gap
Implementation Method 2
a diametrical gap (adhesion gap) between the housing and bracket where the adhesives are provided changes because of the thermal expansion of the two components during the curing step
Data Source
AI summary
A fluid dynamic bearing apparatus with an increased adhesive strength between a component having an adhesion fixing face and a bracket is provided by appropriately controlling the adhesion gap. Materials for a bracket and a housing are selected so that the value obtained by dividing the linear expansion coefficient of the housing fixed to the inner periphery of the bracket by the linear expansion coefficient of the bracket having a portion for mounting a stator coil of a motor is not lower than 0.5 but not higher than 2.0. An adhesion fixing face formed on the outer periphery of the housing is adhesively fixed to the inner circumferential surface of the bracket with an anaerobic adhesive or an epoxy-based adhesive.