Shear Nut Failure Point Calibration for Accurate Torque Release
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Solution Overview
Problem
Existing torque transmission elements, such as expansion anchors and shear nuts, experience significant deviations in transmitted torque due to material strength variations, leading to tolerances of ±10% or more, which can result in either excessive or insufficient torque application.
Innovation Solution
The method involves determining material parameters, such as strength, before or during production, and adapting the geometry of the failure point to ensure it transmits a planned torque and fails when exceeded, thereby reducing torque transmission deviations to less than ±5% by adjusting the cross-section or geometry of the failure point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If material strength values are used as specified in manufacturing, then torque transmission elements can be produced with standard geometry, but the actual torque transmitted deviates by ±10% or more due to material property variations
Solution Approach 1:
The patent changes the geometric parameters of the failure point (cross-sectional area, shape dimensions) based on the actual measured material strength of each individual blank. By adjusting these geometric parameters in response to material property variations, the torque transmission accuracy is improved from ±10% to within ±5% of the target torque value.
Solution Approach 2:
The patent performs preliminary measurement of material strength characteristics before manufacturing the failure point geometry. This preliminary action allows the geometry to be pre-adapted to the specific material properties of each blank, ensuring accurate torque transmission from the outset rather than relying on standard tolerances.
2Manufacturing precision
If the cross-section of the failure point is reduced to compensate for high material strength, then the intended torque can be transmitted, but the failure point may become too weak and fail below the intended torque
Solution Approach 1:
The patent dynamically adjusts the cross-sectional parameters of the failure point based on the measured material strength. For blanks with higher than intended strength, the cross-section is reduced; for blanks with lower strength, the cross-section is increased or maintained. This parameter adaptation ensures that each failure point has the appropriate strength to transmit the intended torque without premature failure.
3Manufacturing precision
If the geometry of the failure point is adapted to each blank's material properties, then torque transmission accuracy improves to within ±5%, but additional measurement and manufacturing steps are required
Solution Approach 1:
The patent employs a self-service approach where the manufacturing process automatically measures the material strength of each blank and uses this information to determine the appropriate failure point geometry. This self-regulating process eliminates the need for complex external calibration procedures and integrates the adaptation directly into the manufacturing workflow.
Solution Approach 2:
The patent implements a feedback mechanism where the measured material strength characteristics are fed back into the manufacturing process to adjust the failure point geometry. This closed-loop approach ensures that each component is manufactured with geometry specifically suited to its material properties, achieving high torque transmission accuracy.
Data Source
Figure 1~2
Figure 3~4
AI summary
To calibrate, for example, a circumferential groove (5) as a failure point (6) of a screw nut (2), the invention proposes determining a strength characteristic, for example, a hardness of the screw nut (2) or a shear strength of a blank from which the screw nut (2) is manufactured, and adapting a geometry of the failure point (6), for example, a depth of the groove (5), to the determined strength characteristic such that the failure point (6) is destroyed when a planned torque is exceeded. The invention allows for small tolerances of the planned torque of ±5% or ±4% and less.