Belleville Disk Clamp Nonlinear Clamping Force
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Solution Overview
Problem
Existing disk clamps in data storage systems exhibit variation in clamping force due to deflection, leading to issues like disk surface curvature and slippage during mechanical shocks, which can interfere with data retrieval.
Innovation Solution
A disk clamp with an annular and conical deflection portion and a disk contact portion that exerts a nonlinear clamping force, similar to a Belleville spring, where the inner extent is offset from the outer extent by a height ranging from 2 to 2.6 times the material thickness, reducing sensitivity to clamp deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the clamp deflection is increased to apply clamping force, then the clamping force on the disk is improved, but the sensitivity to fastener tightening variation increases leading to part-to-part variation
Solution Approach 1:
The patent changes the geometric parameters of the clamp, specifically introducing a conical deflection portion with a specific height-to-thickness ratio (2 to 2.6 times). This geometric modification transforms the linear force-deflection relationship into a nonlinear one, where the spring rate decreases with increasing deflection, thereby reducing sensitivity to fastener tightening variations and improving clamping force consistency across parts.
Solution Approach 2:
The patent introduces a conical curvature in the deflection portion of the clamp, transitioning from a straight cross-section to a curved geometry. This curvature creates a nonlinear elastic response where the stiffness varies with deflection amount, allowing the clamp to maintain consistent clamping force despite variations in fastener tightening, thus resolving the contradiction between force application and force consistency.
2Reliability
If the clamp deflection is increased to secure the disk, then the disk attachment is improved, but the disk surface curvature and slippage during mechanical shocks occur
Solution Approach 1:
By modifying the geometric parameters of the clamp to include a conical deflection portion with controlled height (2 to 2.6 times the thickness), the patent creates a nonlinear spring rate characteristic. This allows the clamp to provide sufficient deflection for secure disk attachment while distributing the clamping force more uniformly, preventing disk surface curvature and slippage during mechanical shocks.
3Manufacturing precision
If the fastener tightening is increased to reduce clamp deflection sensitivity, then the clamping force consistency is improved, but the device complexity and installation difficulty increase
Solution Approach 1:
The patent achieves clamping force consistency through geometric parameter optimization of the clamp itself (conical deflection portion with specific height-to-thickness ratio), rather than through complex fastening mechanisms or control systems. This passive geometric solution maintains simplicity in device structure while improving precision, avoiding increased device complexity.
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 nonlinear clamping force reduces part-to-part variation and minimizes deflection-related issues, ensuring consistent disk attachment and improved data retrieval by decreasing the spring rate with increasing deflection.
Implementation Method 1
A Belleville spring 205, also referred to as a disk spring or conical deflection portion, is coupled to the clamp 204 at the inner extent 210... The Belleville spring 205 exerts a force in a direction opposite to the deflection of the clamp 204... the force exerted by the Belleville spring 205 is nonlinearly related to a deflection of the clamp 204 such that a spring rate of the clamp decreases with increasing deflection of the clamp
Data Source
AI summary
A disk clamp for clamping an information storage disk to a rotating spindle in a disk drive includes a deflection portion that is annular and conical in shape, and which has a material thickness, an outer extent, and an inner extent. In certain embodiments, the inner extent is offset from the outer extent by a particular height measured parallel to an axis of rotation of the disk clamp. The disk clamp may further include a disk contact portion that is disposed radially outboard from the deflection portion, and which may include a curvature radially outboard of the outer extent that departs from a projection of the deflection portion, and a surface for contacting the information storage disk.