Causes And Countermeasures of Weighing Inaccuracy of Electronic Belt Scale

Electronic belt scale is a kind of electric weighing equipment which is widely used in mines, ports, grain warehouses and other places to pre weigh various materials. Electronic belt scale is a general name, which includes ICs type electronic belt scale (also known as through belt scale), quantitative feeder, DGP hanging belt scale and other dynamic weighing belt scales. Generally, electronic belt scale is a separate weighing device installed on a long conveyor belt frame, which consists of weighing frame, weighing sensor, speed sensor and integrator instrument. The electronic belt scale weighs the materials passing through the conveyor belt in a cumulative way, but does not control the flow of materials. The advantages of electronic belt scale are obvious, mainly in the following aspects: low cost, simple and convenient installation, and no need to make too much changes to the original equipment foundation site. The disadvantages are: in the dynamic weighing environment, it is easy to be affected by external environment, conveyor belt and other factors, and the measurement accuracy is not high, so it is not suitable for trade settlement weighing instrument. With the rapid development of social economy and the continuous progress of science and technology, the manufacturing technology of belt weigher has also been improved rapidly. After the technical upgrading and transformation, the electronic belt scale has developed from the original mechanical and electrical combination to the intelligent and all electronic type, and has achieved a great leap. At the same time, in the detection means and technical equipment, it is also constantly improving and innovating, especially in dynamic weighing and rapid weighing, which has been widely used, showing a broad prospect. As the leading weighing and measuring equipment, the electronic belt scale is easy to be affected by corrosion, humidity, dust, impact and other factors due to the high frequency of use and various environments. It will lead to the reduction of the use effect and even interruption of use. Therefore, it is necessary to strengthen daily maintenance and timely troubleshooting.

1. Reasons for weighing misalignment of electronic belt scale

The electronic belt scale is a dynamic electronic weighing scale which can weigh, proportion and flow of various bulk weight in the conveyor system with belt as carrier, and finally calculate the total weight quality. The structure of the belt is generally double roller weighing. The weighing frame is supported by high-precision cross torsion spring, and the belt automatic tension mechanism is set. The position and tension of the belt can be adjusted automatically according to the actual working conditions. The dynamic weighing part is composed of weighing sensor, speed sensor, weighing roller (frame), cross torsion spring, standard chain code and other parts.

The weight error of electronic belt scale is mainly shown in:

1) If the error exceeds the reasonable range, it is necessary to calibrate the electronic belt scale by material separation method many times;

2) After each calibration, the operation is slightly stable, and it still needs to be calibrated once a week or even every day;

3) When the electronic belt scale is running without load, the instantaneous flow data is not zero, and there is a positive or negative number phenomenon, and the no-load deviation is large.

2.Calibration of electronic belt scale

Electronic belt scale has many advantages such as convenient operation, stable operation, large weighing range, saving manpower and accurate data. Therefore, it is widely used in various industries of industrial and mining building materials, ports, mechanical and electrical industry, and also is also a common measuring equipment in tobacco, chemical industry, medicine, food and other industries. The accuracy of electronic belt scale is easily affected by the surrounding environment factors, so that its measurement effect cannot reach the ideal level. Therefore, it is necessary to calibrate and maintain it regularly, and monitor its operation status in real time, so as to find out the cause of the fault in time, take effective measures to eliminate it, ensure its accuracy, and make the working process smooth and smooth, Avoid measurement errors and disputes arising therefrom.

2.1 inspection of weighing area of electronic belt scale

Because the weighing error is affected by wind speed, frost, rain and snow and other external environmental factors, the electronic belt scale should be installed indoors in the place where the environmental factors are not affected, and the house shall be firm and weather resistant. If it is necessary to be installed outdoors, it is necessary to install facilities with shelter from wind and rain. The weighing roller should be lubricated regularly during daily maintenance. Since the parameters of the electronic belt scale calibration may be changed after the roller lubrication, the calibration parameters of the electronic belt scale shall be calibrated several times after lubrication to ensure accuracy.

2.2 adjustment of belt idler of electronic belt scale

Under no load or load, the belt shall be adjusted to the same as the center line of the idler. In case of partial load, the material shall be shaped. Once the belt is normal when no-load occurs, the belt deviation must be adjusted and calibrated in time. The condition of belt tension conveyor is due to the influence of external environment and weighing material, so that the belt is often sticky when running the belt material. However, the weighing material is more likely to happen in the wet or humid environment. Therefore, the belt should be cleaned in time to remove the adhesive. If there are not many adhesion materials or it is difficult to remove, zero calibration measures shall be taken to reduce errors and ensure accuracy.

3. Maintenance scheme of electronic belt scale

With the increasing popularity of digital information, emerging industries are emerging, and the related technologies of producing electronic belt scales are constantly updated, so it brings new challenges to the daily maintenance and calibration of electronic belt scales. The analysis and summary of the working principle and calibration technique of the electronic belt scale is helpful to the use and maintenance of the measuring equipment.

3.1 working principle of electronic belt scale

The electronic belt scale generally uses a separate digital weighing system. Its working principle is to convert the weighing parameters of the measured weight into analog voltage or analog current by analog weighing sensor, and simultaneously detect the instantaneous speed of the belt with the speed measuring sensor, and transmit the signal to the digital transmitter through the instantaneous speed, Then the digital signal output after the digital transmitter is converted is transmitted to the intelligent weighing display control instrument of the electronic belt scale through the integrator.

According to the working principle of electronic belt scale, the instantaneous flow and material accumulated weight displayed by the integrator are converted by computer. The measured signal value is transmitted to the distributed control system through the current isolation module, and the dynamic process of remote display and production flow control is completed. However, in the weighing process of belt scale, the load cell outputs millivolt value signal, and the pulse signal output by the speed sensor of belt scale conversion integrator is weak current signal. The signal is very easy to be interfered by external electromagnetic field, which makes its numerical output abnormal, which results in inaccurate flow value display data and large error.

3.2 maintenance of electronic belt scale

3.2.1 laying and installation of all electric wires and cables of electronic belt scale

Professional staff shall cooperate with the installation personnel of the manufacturer to prevent interference of the cable of electronic sensor. During installation, avoid parallel with power cable as much as possible. After re construction and installation, strong magnetic field interference caused by belt power cable will be eliminated.

3.2.2 requirements for belt erection of electronic belt scale

Because of the long transmission distance, the belt tends to run out of the way, which will cause uneven feeding and easy to be out of alignment. If the blanking is not on a central line, there will be deviation. The solution is: adjust and repair the deviation correction roller according to the operation rules, make the belt run normally and ensure accurate weighing.

4.Conclusion

As a dynamic, automatic and continuous weighing instrument, electronic belt scale has been widely used and plays an increasingly important role. With the deepening of the revolution of intelligent, digital and information industry, higher and stricter requirements are put forward. There are many factors of accuracy, but we should strictly follow the operation rules, understand the working principle, grasp all aspects of the measurement system, timely detect and inspect, find out the faults, find countermeasures, effectively solve them and ensure the operation of electronic belt scale can be reliable and accurate through careful daily maintenance.

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