Load Cell Lift-Off Protection Using Spherical Locking Grooves
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Solution Overview
Problem
Existing load cell securing methods are inadequate in preventing tilting and falling of weighed installations under adverse conditions like earthquakes or strong winds, as they either compromise accuracy or introduce parasitic forces, and are not stable under horizontal forces.
Innovation Solution
The use of locking members, such as spherical balls or cylindrical rollers, placed in grooves on the load cell and force introduction part to secure the weighed installation without introducing parasitic forces, allowing for tilting without bending moments and ensuring accurate load measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bolts and nuts are used to secure the weighed installation to the load cell, then the installation is locked against lifting off, but parasitic forces are introduced into the load cell which lower measurement accuracy
Solution Approach 1:
A spherical intermediate element (ball or roller) is introduced between the load transmission member and the load cell. This intermediary allows the connection to accommodate movements and tilting while preventing direct parasitic forces from being transmitted to the load cell, thus maintaining measurement accuracy while ensuring securing against lift-off.
Solution Approach 2:
The invention changes the geometric parameters of the connection by using spherical surfaces instead of flat bolted connections. The spherical geometry allows for rotational movement and tilting accommodation, enabling the system to maintain both securing reliability and measurement precision under adverse conditions.
2Reliability
If long bolts are used to secure the installation, then lift-off is prevented, but the solution becomes unstable under strong horizontal forces such as during earthquakes
Solution Approach 1:
The invention employs spherical elements (balls or rollers) at the connection point between the load transmission member and the load cell. This spherical geometry provides inherent stability under horizontal forces by allowing the connection to pivot and accommodate lateral movements during earthquakes or strong winds, while still preventing tilting and lift-off through the groove constraints.
3Strength
If the load transmission member is rigidly fixed to the load cell, then structural stability is achieved, but any tilting introduces parasitic bending moments that affect measurement accuracy
Solution Approach 1:
The invention transforms the rigid fixed connection into a dynamic connection using spherical elements that can pivot and rotate. This dynamic connection maintains structural stability by preventing lift-off through the groove constraints while allowing the connection to adapt to tilting movements without generating parasitic bending moments, thus preserving measurement accuracy.
Data Source
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AI summary
Load cell lift-off protection devices with the load to be measured applied directly to the spherical upper surface of the load cell and with locking members which are locking grooves in the load cell force introducing parts to grooves in the structure of the weighed installation.