?Phew, I?ve not gained anything!?: Aren?t you relieved when your bathroom scales show that? Probably ? but actually your bathrooms scales don?t measure your bodyweight directly. Instead, the strain cell included in it converts the weight force right into a path. In lots of industrial applications, bending beams and shear beams are often used for such measurements.
Background: How is weight measured?
Whether your bathroom scales, a finely calibrated laboratory balance or the gravimetric level monitor of a silo: In every cases, they are measuring instruments that determine a mass. Generally, they measure the weight force occurring. But unlike, for instance, a beam balance or a spring balance, the strain cells useful for this determine the weight force indirectly. For this purpose, these force transducers convert the weight force right into a path.
The principle: In the load cell, the weight force deforms an integral spring or perhaps a bending beam. The intensity of this deformation then gives information about your weight, for example (more precisely about your weight force). Sufficient reason for that, it also answers the question of whether you can still order a dessert or just start thinking about an eating plan.
The ?core? of bending beams and shear beams
The various design stages of force transducers in weighing technology: shear beam, bending beam, single-point and S force transducer.
How can you determine how far the measuring bodies of a bending beam or shear beam load cell deform? At this stage special strain gauges or thin-film sensors come into play. These are mounted on or mounted in the measuring bodies. In the measurement process, they act as a mechanical intermediate stage.
Exemplory case of strain gauges: These are glued to the measuring body. If the measuring body deforms, that is transferred to any risk of strain gauges. These convert the elastic deformations proportionally into electrical signals. Such changes in resistance can be easily and incredibly accurately measured: with a measurement accuracy of between 0.01 % and 0.05 % Fnom. The calibration is manufactured in grams, kilograms or tons.
As an alternative to these glued foil strain gauges, you can find force transducers with welded-in thin-film sensors: a technology that the WIKA Group excels in and with which, in neuro-scientific force measurement, it’s the only supplier out there. The thin-film technology supplies a consistently high quality, an exact measurement directly in the force flow, excellent temperature characteristics and a higher long-term stability. With bending beams and shear beams, the standardised sensor is welded in to the measuring element using a laser, which enables automated series production.
Application fields for bending beams and shear beams
Bending beams and shear beams are used in weighing technology to look for the weight of small and medium-sized vessels and so are also frequently used in effect measurement. In agricultural engineering, for example, such load cells are frequently encountered: for example, when weighing livestock, dosing animal feedstuff, in gravimetric level monitoring of vessels and silos or for weighing straw or hay bales directly in the baling press.
But also beyond these fields of application, bending beams and shear beams can be used in a wide selection of other ways: for example, in traditional weighing machine construction, platform weighing (platform scales), weighing in process and dosing systems, vessel scales, crane scales and truck scales. In particular, in applications in the building materials industry, the chemical industry, the food industry and medical technology, bending beams and shear beams tend to be installed.
Practical example: Level monitoring with bending beam or shear beam load cells
Checking fill levels by measuring the weight of the vessel and contents: The filling height of a vessel or tank can be calculated from the measured data of this gravimetric level monitoring. This measurement method supplies a number of advantages:
Level and the exact mass could be measured concurrently.
Access to the tank or vessel is not needed (this eliminates contact with the medium).
The measurement is in addition to the material, its properties and the geometry of the container.
The bending beam or shear beam can be easily replaced if necessary.
In level measurement, the strain cells must function regardless of the nature and condition of the media. Liquid or solid, aggressive, conductive or non-conductive, forming foam or dust, steaming, hot or cold, with small or large grain size, whatever the geometry of the vessel and if the medium in the vessel is evenly or unevenly distributed: Such factors should never affect the measuring result and the permanent function. This also applies in temperature-critical applications and where robustness and high durability are needed ? for instance in the steel industry.
Surprise and bending beams in the agricultural industry
In another practical example, stainless sparkles too: In the agricultural industry bending beams for weighing are very much in demand. When sowing or fertilising, for instance, a lot of cash could be saved through the precise distribution of the goods. The basis because of this, as is always the case with automation, are exact measured values, which is why high-precision shear beams (which may also be insensitive to side loads) are perfectly suited.
Bending beams, shear beams along with other load cells: versatile problem solvers
Bending and shear beams are among the most popular load cells. Based on the field of application, you can find other force transducers which you can use. Our program includes load cells designed for ranges between 0.3 kg and 300 t.
Single point load cells. These are used in weighing technology for platform scales with smaller and medium sizes. Also, they are known as ?single points? and so are also suitable for eccentric load introductions.
Compression force load cells. Exactly like heavy-duty load cells, they are tailored to the weighing of medium and large vessels and silos. The force introduction is just as easy because the installation; furthermore, the look is robust.
Tension/compression force load cells. These are mainly utilized for weighing suspended loads. Measurement is made directly in the force path; in addition, the installation is uncomplicated.
Note
Further information on the product range for force measurement, e.g. our bending beams and shear beams, are available on the WIKA website.
See also our article
Load pins: Definition and application areas