?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 into a path. In many industrial applications, bending beams and shear beams tend to be useful 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 all cases, they are measuring instruments that determine a mass. As a rule, they gauge the weight force occurring. But unlike, for instance, a beam balance or a spring balance, the load 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 strain cell, the weight force deforms an integral spring or perhaps a bending beam. The intensity of this deformation then gives information regarding your weight, for instance (more precisely about your bodyweight force). And with that, it also answers the question of whether it is possible to still order a dessert or simply 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 point special strain gauges or thin-film sensors enter 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: They are glued to the measuring body. If the measuring body deforms, this is transferred to the strain gauges. These convert the elastic deformations proportionally into electrical signals. Such changes in resistance could be easily and very accurately measured: with a measurement accuracy of between 0.01 % and 0.05 % Fnom. The calibration is manufactured 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 and with which, in neuro-scientific force measurement, it’s the only supplier that you can buy. The thin-film technology offers 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 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 instance, such load cells are frequently encountered: for instance, when weighing livestock, dosing animal feedstuff, in gravimetric level tabs on 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 utilized 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. Specifically, 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 can be calculated from the measured data of the gravimetric level monitoring. This measurement method supplies a number of advantages:
Level and the precise mass could be measured as well.
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 strain 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 must not 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.
Shear beams and bending beams in the agricultural industry
In another practical example, stainless sparkles too: In the agricultural industry bending beams for weighing have become much popular. When sowing or fertilising, for instance, a lot of money can be saved through the precise distribution of the goods. The basis because of this, as is definitely the case with automation, are exact measured values, which explains 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 commonly used load cells. Depending 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. Inferior are also known as ?single points? and are also suitable for eccentric load introductions.
Compression force load cells. Exactly like heavy-duty load cells, they’re tailored to the weighing of medium and large vessels and silos. The force introduction is simply as easy as the installation; furthermore, the look is robust.
Tension/compression force load cells. They are mainly used for weighing suspended loads. Measurement is manufactured directly in the force path; furthermore, 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