?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 weight directly. Instead, the strain cell built into it converts the weight force into a path. In lots of industrial applications, bending beams and shear beams are often useful for such measurements.
Background: How is weight measured?
Whether your bathrooms scales, a finely calibrated laboratory balance or the gravimetric level monitor of a silo: In all cases, these are measuring instruments that determine a mass. Generally, they gauge the weight force occurring. But unlike, for instance, a beam balance or perhaps a spring balance, the strain cells useful 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 about your weight, for example (more precisely about your weight force). And with that, it also answers the question of whether it is possible to still order a dessert or just start thinking about a diet.
The ?core? of bending Impatience 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 attached to or mounted in the measuring bodies. In the measurement process, they become a mechanical intermediate stage.
Exemplory case of strain gauges: They 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 very 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 the field of force measurement, it’s the only supplier on the market. 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 utilizing 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 are also frequently used in force measurement. In agricultural engineering, for instance, 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 utilized 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. 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 this gravimetric level monitoring. This measurement method offers a number of advantages:
Level and the exact mass could be measured at the same time.
Access to the tank or vessel is not needed (this eliminates contact with the medium).
The measurement is independent of 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, 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 also applies in temperature-critical applications and where robustness and high durability are required ? 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 in demand. When sowing or fertilising, for example, lots of money could be saved through the exact distribution of the goods. The basis for 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. Depending on field of application, there are 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. They are found in weighing technology for platform scales with smaller and medium sizes. They are also referred to as ? Turbocharges ? and are also suitable for eccentric load introductions.
Compression force load cells. Just like heavy-duty load cells, they’re tailored to the weighing of medium and large vessels and silos. The force introduction is just as easy because the installation; furthermore, the design is robust.
Tension/compression force load cells. They are mainly utilized 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