Weighing cells or load cells measure the weight of the mixing goods and the mixer
Wherever bulk solids are manufactured or processed, we want to know their weight. This is the only way to reliably control the quality of intermediate and end products.
A powder mixer is used to refine materials and usually plays a significant role in the value-added chain. But it is only one link in the process chain. The more information is known in connection with dosing, mixing, discharging and the degree of emptying, the better the interaction of the entire plant can be optimized.
Simple load cells can reliably weigh large masses. This also applies when the masses are blended in the mixer. Weighing data is provided in analog or digital form. However, within a plant system, more is needed. The measurement data must be interpreted in process automation. amixon® discusses just one detail in this context that is frequently questioned by customers.
Question from a customer: How exactly can the contents of a 5m³ mixer be weighed when the mixer rests on load cells as shown here?
Answer from amixon®: The amixon® mixer shown on the right rests on four load cells. The component depicted in blue shows the mounting plate and the bending beam of such a load cell. In its round recess, strain gauges are mounted (hidden for us). Depending on the load, the beam deforms elastically. If the strain gauges stretch, the electrical resistance increases; if they compress, the electrical resistance decreases. Digital load cells have integrated evaluation electronics that measure the current flow and output it as a digital signal. The load is applied via a sphere. This ensures that only vertical loads are measured.
In this case, the data is approximately :
(One kg mass causes a vertical force of 9.80665 N at rest)
- Empty weight of the mixer 50 kN.
- The mix may have a bulk density of up to 1.2 kg/dm³.
- The mix then weighs a maximum of 60 kN.
- The total load is 110 kN.
- This constellation results in a weighing accuracy of 5 N, which corresponds to a powder mass of approx. 500 g.
The display then shows a very accurate value when the mixing tool is stationary. With the aid of electronic attenuation, a reasonably accurate value can be displayed even when the mixing tool is rotating.
Before the weighing function is put into operation, the scale must be parameterized with the display electronics. For this purpose, it is necessary to load or fill the mixer symmetrically with a precisely defined minimum load. The electronic signal generated in this way is used to tare the scale.
Question from a customer: Can the contents of the mixer be filled into big bags or containers with sufficient accuracy using the weighing device?
Answer from amixon®: In principle, this is possible if the flow suitability of the mixing goods allows it and if the discharge fitting of the mixer is suitable for this. If you would like to find out more about “Container filling or big bag filling directly from the mixer”, please also read our article on our new development DosiFlap®.
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