Spindle Motor Rotor Hub Reinforcing Flange Design
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Solution Overview
Problem
Conventional spindle motors face challenges in maintaining the flatness of recording discs due to deformation and vibration issues during manufacturing, which affect the electromagnetic conversion efficiency and increase production costs, while also requiring high-energy consumption and environmental concerns related to adhesive use.
Innovation Solution
The spindle motor design includes a rotor hub with an annular non-contact surface and a reinforcing flange, where the yoke is press-fitted around an annular projection with a smaller outer diameter, reducing bending moments and deformation, and a tubular yoke main body with a fixing part that minimizes leakage flux and axial vibrations, allowing for simpler cutting tools and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the yoke is press-fitted around the outer circumference of the annular projection of the rotor hub, then the assembly strength is improved, but the disc mount portion may be deformed depending on the positional relationship between the annular projection and the disc receiving face
Solution Approach 1:
The patent introduces a reinforcing flange that extends in the axial direction (another dimension) from the disc mount portion. This flange provides additional structural support to prevent deformation of the disc receiving face during press-fitting, while not interfering with the radial press-fit operation between the yoke and annular projection.
Solution Approach 2:
The rotor hub is segmented into distinct functional portions: the disc mount portion for mounting the disc, the annular projection for yoke attachment, and the reinforcing flange for structural support. This segmentation allows each portion to be optimized independently - the flange reinforces the disc mount area without interfering with the press-fit operation between the yoke and projection.
2Manufacturing precision
If the outer diameter of the annular projection is reduced to improve flatness, then the bending moment on the disc mount portion is reduced, but the yoke fixation strength may be compromised
Solution Approach 1:
The reinforcing flange extends in the axial dimension to provide additional leverage and distribution of forces during press-fitting. This allows the annular projection to have a smaller radial dimension (improving flatness) while the axial flange compensates for the reduced radial contact area, maintaining adequate fixation strength.
Solution Approach 2:
The reinforcing flange is designed to contact the jig or support structure before or during the press-fitting operation, providing preliminary support to the disc mount portion. This preliminary action prevents excessive bending moment from being applied to the disc receiving face during the subsequent yoke press-fit operation.
3Manufacturing precision
If adhesive is used to fix the yoke to the rotor hub, then the deformation of the disc mount portion is reduced, but the manufacturing complexity and energy consumption increase due to additional equipment and processes
Solution Approach 1:
The patent replaces the chemical bonding method (adhesive) with a mechanical reinforcement approach. The reinforcing flange provides structural support through mechanical means, eliminating the need for adhesive application equipment, clean rooms, and baking ovens, thereby simplifying the manufacturing process while maintaining flatness 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 design effectively prevents deformation of the disc mount portion, maintains the flatness of recording discs, improves electromagnetic conversion efficiency, reduces manufacturing costs, and minimizes environmental impact by avoiding adhesive use and energy-intensive processes.
Implementation Method 1
a hydrodynamic bearing provided on the base plate for rotatably supporting the rotor hub relative to the base plate
Implementation Method 2
the yoke is press-fitted around an annular projection
Data Source
AI summary
A spindle motor rotatably drives recording discs, and includes a base plate, a stator, a rotor hub, a yoke, a rotor magnet, and a hydrodynamic bearing. The hub includes a disc support cylindrical portion for supporting the recording discs in the radial direction, an annular disc mount portion formed on an outer circumference of the cylindrical portion for mounting the recording discs thereon, and an annular projection formed on the lower portion of the disc mount portion in the axial direction and having an outer circumference to which the yoke is fixed. The disc mount portion is formed with an annular non-contact surface formed on the upper portion in the axial direction, and an annular disc receiving face formed around an outer circumference of the non-contact surface and upward of the non-contact surface in the axial direction for being in contact with the recording disc in the axial direction.