Leaf Spring Sag Resistance Evaluation Using Pre-Loading
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Solution Overview
Problem
Conventional leaf spring load measuring devices are unable to accurately evaluate the sag resistance of leaf springs, particularly those corrected by laser beams, which is crucial for ensuring shock resistance in hard disc drives.
Innovation Solution
A load measuring device comprising a weighing mechanism that applies a load heavier than the working load to bend the leaf spring in its thickness direction, a measuring mechanism to record the load value within the working load range, and a metering mechanism to measure displacement, all controlled by a computer program that stores and displays the data on a time-series basis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser beam is used to correct the load of a leaf spring, then the load precision is improved, but the sag resistance is reduced due to residual stress removal
Solution Approach 1:
The patent applies preliminary action by subjecting the leaf spring to a heavy load (exceeding working load) for a predetermined hold time before measurement. This pre-loading process intentionally removes residual stress and induces controlled sag, ensuring that subsequent load measurements reflect the spring's performance in its actual working condition after stress relief, rather than measuring an unrepresentative initial state.
2Measurement precision
If a conventional load measuring device is used, then the load value can be measured, but the sag resistance cannot be evaluated
Solution Approach 1:
The patent implements multi-functionality by integrating both load measurement and sag resistance evaluation capabilities into a single measuring device. The device measures load values while simultaneously monitoring displacement over time, enabling it to assess both the spring's load-bearing capacity and its sag resistance under heavy load conditions, thereby eliminating the need for separate evaluation processes.
3Reliability
If the leaf spring is subjected to heavy load for sag evaluation, then the sag resistance can be assessed, but the measurement time increases
Solution Approach 1:
The patent applies continuity of useful action by continuously measuring displacement at multiple time points during the hold period while the heavy load is applied. This continuous monitoring captures the complete sagging process and stress relaxation behavior, enabling comprehensive sag resistance assessment within a standardized, efficient time frame rather than requiring extended observation periods.
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
Enables accurate and efficient evaluation of leaf spring sag resistance, reducing operator dependency and improving the durability of hard disc drives by uniformly sagging the leaf spring without significant displacement variation.
Implementation Method 1
a weighing mechanism for applying a load heavier than a working load to a leaf spring (12) to bend the leaf spring (12) in a thickness direction
Implementation Method 2
a measuring mechanism for measuring a load value of the leaf spring (12) in a manner such that the leaf spring (12) is subjected to a load within a range of the working load
Implementation Method 3
a metering mechanism for metering a displacement of the leaf spring (12) when the load value is measured
Data Source
AI summary
A leaf spring load measuring device of the present invention comprises a weighing mechanism, a measuring mechanism, a metering mechanism, and a control mechanism. The weighing mechanism applies a load heavier than a working load to a leaf spring, thereby bending the leaf spring in its thickness direction, and maintains the resulting state for a predetermined hold time. The measuring mechanism measures a load value of the leaf spring in a manner such that the spring is subjected to a load within a range of the working load. The metering mechanism meters a displacement of the spring when the load value is measured. The control mechanism controls the weighing mechanism, the metering mechanism, and the measuring mechanism, and has a timer function to meter the hold time.