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Factors affecting the accuracy of high-precision belt weighers

Time:1/15/2024  From:EACCOR

High precision belt weigher is a measuring device that continuously and automatically weighs solid bulk materials during the transportation process of belt conveyors. It has developed rapidly in recent years and has become a mainstream halo measuring system for continuous and automatic weighing of solid materials. Below are several factors that affect the accuracy of high-precision belt weighers.

1. Weighing error of high-precision leather belt scale
The weighing error of high-precision leather belt scale is inversely proportional to the cosine value of the belt slope angle. The larger the slope angle, the smaller the cosine function value, and the larger the error value. The high-precision leather belt scale weighing frame should be installed on the belt conveyor with a small slope angle as much as possible to reduce measurement errors and improve weighing accuracy

2. Belt deviation
Assuming u=30, F left and F right=209F, and friction coefficient -=0.15, of course, the belt may not always operate under a deviation condition. Therefore, the weighing error caused by belt lateral movement also depends on the ratio of the time when the lateral movement occurs to the entire material conveying time. If the belt deviation is within the requirements of the calibration regulations, the impact of belt lateral movement can be ignored.

3. Calibration error
(1) Errors caused by calibration methods
(2) There are differences in calibration between the working status of high-precision leather belt scales and belt conveyor systems and the daily measurement conditions, such as belt tension and belt rotators. Hanging weight calibration can only be used to check the linearity of high-precision leather belt scales, resulting in weighing errors generally around 4-5, while the calibration error of physical calibration is not more than 1%.

4. Installation error
The adjustment during installation The important thing is the alignment calibration and the distance calibration of the support rim. The alignment calibration requirements are: there is no height difference between the weighing support roller on the scale frame and its adjacent support rollers, and it is required that the height of the support rollers in the affected area is higher than that of the support rollers outside the weighing affected area. This height can be selected as 3 to 5mm. Who can allow errors in alignment calibration for high-precision belt scales, 0.5mm can be required, usually 1m. During the adjustment process, the error value at the weighing roller should be slightly positive, that is, slightly higher than the adjacent roller (such as 0mm). The requirement for calibrating the distance between the support rollers is that the distance between the weighing support rollers on the scale frame and the 2-3 sets of support rollers in front and behind them should be equal. More and more manufacturers are attaching importance to the installation of high-precision belt scales, and users are also more aware of the technical requirements for high-precision belt scale installation, reducing errors caused by installation errors. In daily work, it is possible to frequently detect changes in zero point readings, which can cause errors such as uneven belt weight, tension changes in unloaded belts, and initial straightness of the roller. The stability of detecting zero values can further reduce the impact of the aforementioned error sources by more than double.

5. Environmental error
The main environmental factors include temperature, humidity, wind, vibration, and electromagnetic interference. The temperature effect is generally small and may not be considered. The influence of humidity can be eliminated by adjusting the zero point of the belt scale when the belt conveyor is started.