What are the automatic weighing devices for conveyor belts, and what are their respective advantages and disadvantages?

Conveyor belts are automated material handling equipment commonly used for short-distance transport of various bulk materials. Belt conveyors, in particular, are widely used in industries such as building materials, cement, agriculture, and fertilizers. With the development of industrial, electronic information, and dynamic weighing technologies, automatic weighing devices for conveyor belts have gradually emerged and been applied. These devices can be installed on conveyor belt systems to automatically, continuously, and dynamically weigh materials during operation.

Currently, the main automatic weighing devices for conveyor belts are electronic belt scales, mechanical belt scales, and nuclear scales. All three can be used for automatic weighing on conveyor belt systems, but each has its own advantages and disadvantages.

1. Electronic Belt Scales

Electronic belt scales are the most widely used weighing devices for conveyor belts, with a simple principle. They use weight sensors to capture material load signals and speed sensors to capture belt speed signals. The instrument receives these signals and calculates the instantaneous flow rate and cumulative weight of the material.

Electronic belt scales can be selected in different structures based on the actual application site and conveyor system conditions. They can be classified into single-idler and multi-idler types based on the number of idlers, and into lever and suspension types based on the force transmission method. Lever types use the lever principle for force transmission, further divided into single-lever and double-lever. Suspension types directly transmit the force of the material on the belt to the weight sensor through idlers, reducing force transmission links and improving weighing accuracy. Additionally, the number of sensors can vary, with more sensors leading to higher weighing accuracy.

The characteristics of electronic belt scales as automatic weighing devices for conveyor belts include simple structure, ability to meet most weighing accuracy requirements with different structures, high cost-effectiveness, easy installation and maintenance, simple calibration, high degree of informatization, ability to provide weighing data, customizable according to user needs, and wider application scope.

2. Mechanical Belt Scales

Mechanical belt scales consist of a gravity transmission system, rollers, a counter, and a speed dial. The angular velocity of the rolling roller is proportional to the amount of material passing on the belt, and the position of the roller rolling on the speed dial is adjusted by the gravity of the material. These mechanical belt scales have low weighing accuracy, poor stability, and cumbersome maintenance, and are gradually being phased out.

3. Nuclear Scales

Both electronic and mechanical belt scales belong to contact-type automatic weighing devices, while nuclear scales are a non-contact automatic measuring device. They calculate the conveyor belt load based on the attenuation ratio of material to γ-ray intensity and multiply it by the conveyor belt speed to obtain the material flow rate and cumulative amount.

The advantage of nuclear scales as automatic weighing devices lies in their non-contact nature, which facilitates easy installation without modifications to the conveyor system and provides data for users. However, the disadvantage is their relatively low measuring accuracy, especially for irregular materials. Furthermore, nuclear scales emit radiation, significantly impacting the environment and personnel on site, making it difficult to meet environmental standards. Therefore, their application scope is limited.

Through the analysis of these common automatic weighing devices for conveyor belts, it is evident that electronic belt scales are the more ideal choice in terms of practical application, installation and operation, maintenance and repair, calibration and verification, and data functionality.