Tolerance Ring Slotted Sidewall Stiffness
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Solution Overview
Problem
Tolerance rings used in hard disk drives exhibit variations in stiffness and resonance due to differences in wave structure design, leading to alignment and performance issues, as the weakest waves near the gap can compromise overall performance when optimized for one parameter.
Innovation Solution
Incorporating slots in the unformed sections of the tolerance ring to reduce the stiffness of adjacent waves, ensuring consistent resonant frequency and stiffness around the ring, thereby maintaining post alignment and preventing rocking under operational loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wave structures are optimized for one parameter (e.g., stiffness), then that parameter is improved, but other parameters (e.g., resonant frequency consistency) deteriorate due to variations near the gap
Solution Approach 1:
The patent applies local quality by modifying only the unformed sections adjacent to the gap while leaving the wave structures themselves unchanged. Slots are introduced specifically in the unformed sections to reduce stiffness locally, allowing the wave structures to maintain their optimized stiffness while the overall ring achieves more uniform resonant frequency characteristics.
Solution Approach 2:
The patent changes the physical parameter of the unformed sections by introducing slots, which alters the stiffness distribution. This parameter change in the unformed sections compensates for the stiffness variations caused by the gap, resulting in more consistent resonant frequency around the entire ring without compromising the wave structure optimization.
2Ease of manufacture
If the tolerance ring includes a gap for assembly, then ease of assembly is improved, but stiffness uniformity deteriorates due to weaker waves near the gap
Solution Approach 1:
The patent maintains the gap for assembly ease while applying local quality modification to the unformed sections adjacent to the gap. Slots are introduced in these specific locations to compensate for the stiffness reduction caused by the gap, achieving both easy assembly and improved stiffness uniformity.
Solution Approach 2:
The patent extracts material from the unformed sections by introducing slots, removing the excess material that causes stiffness variations. This extraction of material in specific locations allows the gap to remain for assembly while the remaining structure achieves more uniform stiffness characteristics.
3Reliability
If slots are added to reduce stiffness of adjacent waves, then resonant frequency consistency is improved, but device complexity increases
Solution Approach 1:
The patent limits the complexity increase to only the unformed sections adjacent to the gap, applying slots only where needed. The wave structures themselves remain simple and unchanged, achieving resonant frequency consistency without unnecessarily complicating the entire structure.
Solution Approach 2:
The patent segments the modification to only the unformed sections rather than applying it to the entire ring. By introducing slots only in the unformed sections adjacent to the gap, the complexity is localized and minimized while still achieving the goal of resonant frequency consistency.
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 modified tolerance ring maintains consistent axial stiffness and resonant frequency, preventing post rocking and ensuring reliable operation by reducing stiffness variations, thus enhancing performance and alignment within the bore.
Implementation Method 1
Incorporating slots in the unformed sections of the tolerance ring to reduce the stiffness of adjacent waves
Implementation Method 2
The modified tolerance ring maintains consistent axial stiffness and resonant frequency, preventing post rocking and ensuring reliable operation by reducing stiffness variations
Implementation Method 3
the protrusions are compressed. Each protrusion acts as a spring and exerts a radial force against the shaft and the surface of the bore, providing an interference fit
Data Source
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AI summary
A tolerance ring (122) is disclosed and can include a generally cylindrical body (302) having a sidewall. The sidewall can include a plurality of wave structures (322) extending from the sidewall at regular intervals around the body, a first unformed section between a first pair of adjacent wave structures, and a second unformed section between a second pair of adjacent wave structures. The first unformed section includes a gap (314) which extends along an entire length, L, of the body to establish a split in the body. The second unformed section can include a slot (342) therein. The slot can have a length, Ls, and Ls > 80% L.