?Phew, I?ve not gained anything!?: Aren?t you relieved whenever 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 into a path. In many 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 all cases, they are measuring instruments that determine a mass. Generally, they gauge the weight force occurring. But unlike, for example, a beam balance or perhaps a spring balance, the strain cells used 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 regarding your weight, for instance (more precisely about your bodyweight force). Sufficient reason for that, it also answers the question of whether you can still order a dessert or simply 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 stage 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.
Example 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, you can find 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 is the only supplier that you can buy. The thin-film technology supplies a consistently high quality, a precise measurement directly in the force flow, excellent temperature characteristics and a high long-term stability. With bending beams and shear beams, the standardised sensor is welded in to 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 determine the weight of small and medium-sized vessels and so are also frequently used in effect measurement. In agricultural engineering, for instance, such load cells are frequently encountered: for instance, 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 additionally 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 supplies a number of advantages:
Level and the exact mass could be measured as well.
Usage of the tank or vessel is not required (this eliminates connection 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 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, 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 required ? for instance 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 popular. When sowing or fertilising, for example, lots of money can be saved through the exact distribution of the goods. The basis because of this, as is always 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. With respect to the field of application, there are other force transducers that can be used. Our program includes load cells created for ranges between 0.3 kg and 300 t.
Single point load cells. These are found in weighing technology for platform scales with smaller and medium sizes. Also, they are known as ?single points? and are also ideal 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 simply as easy as the installation; furthermore, the look is robust.
Tension/compression force load cells. These are mainly utilized for weighing suspended loads. Quadruple 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, can be found on the WIKA website.
See also our article
Load pins: Definition and application areas