?Phew, I?ve not gained anything!?: Aren?t you relieved when your bathroom scales show that? Probably ? but actually your bathroom scales don?t measure your weight directly. Instead, the load cell built into 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, these are measuring instruments that determine a mass. As a rule, they gauge the weight force occurring. But unlike, for example, a beam balance or perhaps a spring balance, the load cells used for this determine the weight force indirectly. For this purpose, these force transducers convert the weight force into a path.
The principle: In the load cell, the weight force deforms an integral spring or a bending beam. The intensity of the deformation then gives information regarding your weight, for instance (more precisely about your bodyweight force). And with that, in addition, it answers the question of whether it is possible to still order a dessert or just start thinking about a diet.
The ?core? of bending beams and shear beams
The different design stages of force transducers in weighing technology: shear beam, bending beam, single-point and S force transducer.
How can you regulate how far the measuring bodies of a bending beam or shear beam load cell deform? At this point 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, this is transferred to any risk of strain gauges. These convert the elastic deformations proportionally into electrical signals. Such changes in resistance could be easily and incredibly accurately measured: with a measurement accuracy of between 0.01 % and 0.05 % Fnom. The calibration is made in grams, kilograms or tons.
Instead of these glued foil strain gauges, there are force transducers with welded-in thin-film sensors: a technology that the WIKA Group excels in sufficient reason for which, in neuro-scientific force measurement, it’s the only supplier available to buy. The thin-film technology offers a consistently high quality, an exact measurement directly in the force flow, very good temperature characteristics and a high long-term stability. With bending beams and shear beams, the standardised sensor is welded into the measuring element using a laser, which enables automated series production.
Smug for bending beams and shear beams
Bending beams and shear beams are employed in weighing technology to determine the weight of small and medium-sized vessels and are also frequently used in force measurement. In agricultural engineering, for example, such load cells are generally 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 instance, 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 meals industry and medical technology, bending beams and shear beams are often 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 could be calculated from the measured data of the gravimetric level monitoring. This measurement method offers a number of advantages:
Level and the precise mass could be measured at the same time.
Access to the tank or vessel is not needed (this eliminates connection with the medium).
The measurement is independent of the material, its properties and the geometry of the container.
The bending beam or shear beam could be easily replaced if necessary.
In level measurement, the load cells must function whatever 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, regardless of 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 applies in temperature-critical applications and where robustness and high durability are required ? for example in the steel industry.
Shear beams and bending beams in the agricultural industry
In another practical example, stainless steel 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 products. The basis because of this, as is always the case with automation, are exact measured values, which explains why high-precision shear beams (which are also insensitive to side loads) are perfectly suited.
Bending beams, shear beams and other load cells: versatile problem solvers
Bending and shear beams are being among the most popular load cells. With regards to the field of application, you can find other force transducers which you can use. Our program includes load cells created for ranges between 0.3 kg and 300 t.
Single point load cells. They are found in weighing technology for platform scales with smaller and medium sizes. Also, they are known as ?single points? and are also suitable for eccentric load introductions.
Compression force load cells. Just 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 as 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