The influence of lateral force on bridge and column weighing sensors and the differences in their usage scenarios
In the actual operation of weighing systems, sensors not only bear axial weighing loads perpendicular to the force-bearing surface but also often face lateral force interference along the horizontal or inclined direction. As a non-target load, lateral force disrupts the sensor’s ideal force-bearing state, leading to reduced measurement accuracy or even hardware damage. Due to inherent differences in structural design and force-bearing principles, bridge-type and column-type weighing sensors have vastly different lateral force tolerance capabilities — which directly defines their distinct boundaries in application scenarios. This article will start with the mechanism of lateral force impact, compare the anti-lateral force characteristics of the two sensors, and systematically sort out the core requirement differences in their application scenarios.
Lateral force refers to the non-target load that acts on the sensor’s elastic body along horizontal, inclined, or torsional directions (deviating from the sensor’s axial force direction, usually vertical) during weighing. It mainly includes three types: transverse pressure/pull, shear force, and torsion torque. Though not the object to be measured by the weighing system, this force is a key interference source that causes measurement errors.
Lateral force is closely related to the operation mode and equipment status of the application scenario. Common scenarios can be categorized into three types:
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Dynamic Interference During Operation
- For example: When a forklift moves a barrel onto the weighing platform, horizontal impact between the barrel and the platform generates transverse force; when a robotic arm grabs materials for weighing, the inertial force of the arm’s movement forms an inclined lateral force; when a conveyor belt transports materials, load bias caused by material displacement converts into lateral shear force.
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Equipment Installation and Calibration Errors
- If the sensor’s mounting surface is not level (has an inclination angle), axial load is decomposed into a lateral component; when multiple sensors are combined for weighing, deviations in sensor spacing or force points prevent uniform axial load transmission, forming torsion torque; during calibration, offset placement of weights causes local lateral pressure.
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Environmental and Working Condition Impacts
- In workshops with strong vibration, periodic vibration from equipment operation is transmitted to the sensor, forming transverse impact force; when weighing mixing tanks or reaction vessels, centrifugal force from rotating internal materials converts into lateral force; outdoor weighing equipment (e.g., truck scales) exposed to strong winds bears horizontal lateral force from wind loads.
The structural designs of bridge-type and column-type weighing sensors result in significant differences in their response mechanisms, error manifestations, and damage risks when exposed to lateral force. This can be analyzed from three dimensions: elastic body structure, strain gauge layout, and performance impact.
Also known as beam-type sensors, bridge-type weighing sensors feature a core structure of "I-shaped," "box-shaped," or "double-hole" elastic beams. The beams are connected to the weighing platform/pedestal via fixed ends at both sides, with strain gauges attached to the force-bearing area in the middle. This structure’s lateral force tolerance stems from two core advantages:
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Directional Adaptation of Structural RigidityThe transverse section moment of inertia of the elastic beam is far greater than its axial counterpart, giving it extremely high transverse rigidity. For example, a bridge-type sensor with a 5t rated load has a transverse load resistance of 30%–50% of the axial load (i.e., 1.5t–2.5t). When lateral force acts on it, the transverse deformation of the elastic beam is only 0.005mm–0.01mm — much smaller than the 0.1mm–0.15mm deformation under axial load — so unintended deformation is unlikely to occur.
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Directional Isolation of Strain GaugesStrain gauges are only attached to the upper and lower surfaces of the elastic beam, and the direction of their sensitive grids aligns with the axial direction. They are only sensitive to the "tensile-compressive strain" caused by axial loads. In contrast, the "shear strain" or "bending strain" induced by lateral forces (e.g., transverse shear, torsion torque) is perpendicular to the sensitive direction of the strain gauges, so it cannot be converted into valid electrical signals. Thus, the error impact of lateral force on bridge-type sensors is usually controlled within 0.1% FS (full scale), and some high-precision models can even reduce this to 0.05% FS.
It should be noted that if lateral force exceeds the load resistance limit of the bridge-type sensor (usually 50% of the axial load), the elastic beam may undergo permanent bending deformation. This manifests as increased sensor zero drift (exceeding 0.02% FS/°C) and reduced linearity, resulting in irreversible loss of measurement accuracy.
The elastic body of a column-type weighing sensor has a cylindrical or frustoconical structure, with strain gauges evenly attached along the circumferential direction of the cylinder’s side (typically 4 or 8 pieces, forming a full-bridge measurement circuit). When under force, it generates strain via axial compression of the cylinder. The core flaw of this structure lies in its "axial-transverse rigidity uniformity" — the difference in moment of inertia between the axial and transverse cross-sections of the cylindrical elastic body is small, and its transverse rigidity is only 1/3–1/5 that of a bridge-type sensor. Lateral force thus easily causes irreversible deformation of the elastic body, with specific impacts as follows:
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