Application of Bellows Weighing Sensor in Belt Scale Industry

Electronic belt weigher refers to an automatic weighing instrument that continuously weighs the bulk materials on the conveyor belt without subdividing the quality or interrupting the movement of the conveyor belt. It is mainly classified by the carrier: weighing bench type carrier, conveyor type carrier; Classification by belt speed: single speed belt scale, variable speed belt scale.

The electronic belt scale is composed of a scale frame, a speed sensor, a high-precision weight sensor, an electronic belt scale control display instrument, etc. It can continuously and dynamically measure solid materials.

The weighing bridge of the electronic belt scale is installed on the conveying frame. When materials pass by, the measuring idler detects that the weight of the materials on the belt conveyor acts on the weighing sensor through a lever to generate a voltage signal proportional to the belt load. The speed sensor is directly connected to the large diameter speed measuring cylinder to provide a series of pulses. Each pulse represents a belt movement unit, and the frequency of the pulse is proportional to the belt speed. The weighing instrument receives signals from the weighing sensor and speed sensor, obtains an instantaneous flow value and an accumulated weight value through integral calculation, and displays them separately.

Application of load cell in electronic belt scale:

For the industrial production process of mining, metallurgy, chemical industry, building materials and other enterprises, as well as the material collection and distribution operation of ports and docks, for bulk materials such as coal, ore, salt, etc., belt conveyors are often used for continuous transmission. According to statistics, 90% of the underground transportation and 40-50% of the underground transportation are carried out by belt conveyors.

At the same time of conveying, it is undoubtedly an advanced measuring method to continuously and automatically measure materials with electronic belt weigher. Especially in port terminals, where solid materials are transported with large flow, the electronic belt weigher has incomparable advantages in measuring speed compared with any other weighing method.

In the 1950s, the electronic belt weigher has been popularized in relevant industrial departments abroad. China began to develop it in 1965, and began to produce it professionally by manufacturers at the end of the 1970s. It has developed rapidly in recent decades. It is an electronic conveyor with the largest demand for electronic scales in China.

The electronic belt weigher is not only simple in structure and wide in scope of application, but also can realize automatic detection and recording of instantaneous conveying capacity and total conveying capacity, as well as automatic batching.

In the late 1970s, the popularization and application of microprocessors made a new development of electronic belt weighers. The microcomputer belt scale has been able to automatically peel, calibrate, speed compensation, timing printing and power failure memory. If the instrument part is equipped with a certain interface, it can also form a closed loop system of automatic customized batching with the regulating devices and actuating devices of the production system to achieve automatic control of the production process. This greatly improves the production efficiency and production quality, and can play a very important role in saving energy and materials.

How to judge whether the weighing sensor of electronic belt scale is good or not?

The weighing sensor is the heart part of the electronic belt scale. As a necessary device in weighing control, we need to pay attention to the selection of the weighing sensor. How to judge whether the weighing sensor of the electronic belt scale is good or not? We can judge by the characteristics of the sensor of the electronic belt scale:

Impedance judgment method: remove the two output lines and input lines of the sensor of the electronic belt scale, and use a multimeter to test the output and input impedance and the insulation resistance between each core wire of the signal cable and the shielding layer. If the result of such a test cannot reach the value on the sensor certificate, it can be judged as a faulty sensor;

Judgment method of sensor signal output: when the resistance method cannot be used to judge whether the belt scale sensor is good or bad, the signal output method can be used for further detection; The electronic belt scale instrument can be powered on first, the sensor output wire is removed, and its output value is measured with a multimeter under an empty scale. The calculation is conducted according to the rated voltage, sensor sensitivity, and rated load. If the output value of one of the electronic belt scales exceeds the calculated value too much or is unstable, it can be judged that the electronic belt scale weighing sensor is faulty, because it should be equal when there is no bias load under ideal conditions;

Selection of load cell for electronic belt scale:

The electronic belt weigher can complete the continuous, dynamic and automatic weighing and measuring work in the conveyor transportation process, and can be used in many occasions such as cement plants, building materials plants, environmental protection, steel, grain, etc. Due to the special application occasions and poor application conditions, and the electronic belt weigher itself relies on highly sensitive weighing sensors and speed sensors to collect terminal information, its measurement accuracy and working stability are also greatly affected. In the actual application process, the electronic belt scale will have inaccurate and unstable measurement accuracy.

First of all, we know that the belt scale is mainly used for measuring and weighing equipment, which is widely used in the market. The belt scale is mainly composed of three parts: scale body, weighing sensor and display instrument. As the belt weigher is mainly a weighing and measuring equipment, the selection of weighing sensor is particularly important. It can be said that the weighing sensor is equivalent to the brain of the belt weigher and plays a key role in the accuracy and stability of the belt weigher. Its role is to convert the quality signal to be measured into the corresponding electrical signal output and connect it to the display instrument to display the weight. Therefore, the selection of the weighing sensor of the belt weigher is very important; How to select the load cell of the belt scale correctly?

In addition to the requirements for high accuracy (0.03%~0.05% FS) of technical indicators such as nonlinearity, non repeatability, hysteresis, temperature drift of zero point and temperature drift of sensitivity coefficient, there are also the following special requirements for weighing sensor, which must be paid attention to when selecting weighing sensor.

1: The deformation of the sensor shall be small after loading. Because the vertical displacement D after bearing will change the belt tension, thus introducing measurement error. Therefore, the deformation of the sensor after loading should be set as an important technical index for selecting the sensor. The sensor quantity for electronic belt weigher is generally less than 300kg, and double hole and single hole sensors are generally preferred.

2: The sealing performance shall be good. Because of the bad site conditions and large dust of the belt conveyor, especially the transportation of corrosive materials, the sensor is required to have superior sealing performance, and the sealing performance should be paid attention to as well as the accuracy.

3: It shall have large overload capacity. Generally, 1.5~2 times of the calculated load is selected as the selected range of the sensor, and overload protection device is set on the scale frame. Overload may be caused by uneven stacking or large pieces of materials.

When selecting the type of the load cell of the belt scale, it is necessary to consider the type of the scale body and the installation space to ensure proper installation and safe and reliable weighing. When selecting the load cell of the belt scale, it is necessary to first select the type and configuration with the technicians of the manufacturer of the belt scale to ensure that the load cell can get the maximum use value; On the other hand, it should also be noted that under special environmental conditions, the electronic belt weigher weighing sensor with high airtightness, that is, the bellows type weighing sensor, should be selected. Its characteristics are: high precision, good high bias load capacity, and strong overload protection capacity. Specific models include: LC338, LC339, LC332, etc. of Ningbo Chenbang. Generally speaking, the closer the measuring range of the weighing sensor of the electronic belt scale is to the load distributed to each weighing sensor of the electronic belt scale, the higher the weighing accuracy will be. The high temperature resistant load cell is often used for the load cell of the belt scale working in the high temperature environment; In addition, heat insulation, water cooling or air cooling devices must be added. When selecting the load cell of the belt scale, we should not only pursue the high-grade load cell, but also consider meeting the accuracy requirements of the belt scale and its cost. The actual working environment of the sensor shall be taken into consideration when selecting the load cell of the belt scale. This is crucial to the correct selection of the load cell of the belt scale. It is related to whether the sensor of the electronic belt scale can work normally, its safety and service life, and even the reliability and safety of the entire scale.

For the belt weighers in the current market, more and more people choose the bellows type weighing sensor, because the superior performance of the bellows type weighing sensor<anti eccentric load, anti overload, full laser sealing welding>enables the belt weigher to operate stably for a long time. Because of this, more and more belt weigher manufacturers will choose the bellows type weighing sensor with higher cost performance ratio.