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The working principle and application of continuous weightless scale

Categories:Technical topics
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Time of issue:2022-01-05
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(Summary description)In various fields of modern industrial production, the use of continuous feeding with dynamic weighing function to form a bulk material conveying system is expanding.

The working principle and application of continuous weightless scale

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The working principle and application of continuous weightless scale

(Summary description)In various fields of modern industrial production, the use of continuous feeding with dynamic weighing function to form a bulk material conveying system is expanding.

Categories:Technical topics
Author:
Origin:
Time of issue:2022-01-05
Views:0

Information

Overview: In various fields of modern industrial production, the use of continuous feeding with dynamic weighing function to form a bulk material conveying system is expanding. A continuous loss-in-weight scale is a continuous device that can continuously adjust the conveying rate of materials and measure the conveying quantity. Also known as loss-in-weight feeder, loss-in-weight feeder. It can be used to continuously convey powder, ball, flake, granular and various short fiber materials. Because it requires almost no maintenance, it can better adapt to the requirements of industrial environment and process conditions than other forms of continuous feeding scales. It is more and more widely used in developed countries such as Europe, the United States and Japan. The attention and attention of related industries such as plastic food and medicine.

2. Equipment composition

The continuous loss-in-weight scale is composed of main parts such as feeding device, carrier (weighing hopper), agitator, discharging device, rack, weighing sensor and weighing display controller. The structural feature of the continuous loss-in-weight scale is that the carrier and the discharge device with adjustable discharge speed installed below it are located on the load cell fixed to the frame for overall weighing and control. As shown below:

3. How it works

Continuous weight loss scales are designed according to the principle of controlling weight loss during work. Weigh the carrier and the discharge device that carry the material, and compare the actual discharge and feeding rate (instantaneous flow) with the preset discharge rate according to the weight loss per unit time. By controlling the speed of the discharge device, Make the actual discharge speed always exactly match the set value. During the short feeding process, the discharge device works according to the volume principle with the help of the control information stored during the gravity operation.

(1) Calculation of discharge rate

The discharge rate (discharge flow) of the continuous loss-in-weight scale is the weight loss value per unit time, which is theoretically expressed as:

MT=dG/dt

Among them: dG-weight loss value;

dt—Test period.

The discharge rate under the display state of the weighing indicator can be calculated by the following formula.

MT=n(d±ß·di)/(td±te)

Among them: MT - discharge rate;

d—The scale value displayed on the weighing indicator;

n—displays the number of changes in division value;

di—the internal resolution of the weighing display;

ß—Test error coefficient (usually 0.6);

td—test period;

te—timing error coefficient (usually te=0.001)

(2) Working process

The weight of the material in the carrier is converted into an electrical signal by the weighing sensor and sent to the weighing display. (PLC) controls the feeding device to intermittently feed the material into the carrier. At the same time, the weighing display compares the calculated actual discharge rate with the preset discharge rate, and adjusts the discharge device through PLC and regulator (PID), so that the actual discharge rate can accurately track the set value.

4. Main features and advantages

The calibration method of continuous loss-in-weight scale is simple; the static calibration of the carrier can be carried out by using weights; the calibration of the flow can be calculated by measuring the discharge volume and the time with a stopwatch, and then the actual material flow—the actual discharge rate can be calculated.

The advantages of continuous loss-in-weight scales are mainly reflected in their accurate weighing and stable work. Due to the adhesion of logistics, the tare weight change caused by the temperature drift of the load cell and the load display and the electrical control system, in other feeding scales, the main reason for the decline of accuracy is often caused, and the loss-in-weight scale can effectively avoid this. factor, since the determining factor for the feed rate determination is only the weight difference. It can be seen that the continuous loss-in-weight scale and the batching system composed of multiple loss-in-weight scales and computer monitoring and management systems will have broader application prospects in the continuous conveying system of bulk logistics.

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