Introduction

The first time I came into contact with the technology of modular belt scale was in the article "Modular Belt Scale Technology and the National Type Evaluation Program (NTEP)" published by Norman R. Johnson and Robert. A. Epperson in the 1992 Annual Technical Conference in Nashville, Tennessee. I have briefly introduced the content of the article.

1  About the module "Modular"

The word "Modular" in English means that it is made of standard components and designed (manufactured) according to standard types (sizes). That is, it has a modular, modular, and building block design. In fact, this single roller weighing belt scale is the prototype and foundation of the lever type and suspended multi-roller belt scale that was developed later. It is just that in the above article, the author put forward new ideas and contents about the weighing device of the single roller belt scale. I introduced the modular belt scale (Modular Belt Scale), domestic belt scale manufacturers are mainly concerned about the development of suspended belt scales. Compared with the previous lever belt scale, the suspended belt scale eliminates the influence of the use of blades, bearings, reeds and rubber seals, and the structure of the load carrier is similar to that of the traditional scale. Therefore, it is widely used in belt scale manufacturers, while the application of modular belt scales is ignored.

2  Differences and similarities between traditional belt scales and modular belt scales

The early single roller belt scales were rarely used due to their low accuracy. The modular belt scale has made some important technical improvements on the basis of the single roller belt scale, and introduced the concept of modularization to the structure of the belt scale on the basis of the traditional belt scale.

The author of the article believes that the influence of the belt conveying the material on the weighing result is the main cause of the measurement error. In order to reduce the influence of "belt reaction" on the belt tension, "Working to knowledgethat major weighing error contributor is scale reaction to belt tension fluctuations caused to Misalignment." (And it is mainly caused by inaccurate values), for which the following technical measures have been taken. The roundness eccentricity of the transmission roller of the traditional belt scale is 0.040", and the roundness eccentricity of a better belt scale can reach 0.012"~0.015". In order to reduce the influence of eccentricity, the roundness eccentricity of the roller is increased to 0.004", which is nearly 10 times higher. In addition, a screw that can precisely adjust the alignment is installed on the weighing roller, as shown in Figure 1. This allows the roller on each weighing platform to be accurately aligned with the front and rear rollers, so that the belt reaction error can be minimized. Compared with traditional belt scales, the number of front and rear guide rollers on the weighing platform can also be reduced, as shown in Figure 2, which shows that the front and rear guide rollers can be reduced from four to two.

Another important improvement of the modular belt scale to improve measurement accuracy is the use of a parallelogram loading frame (Parallelogram Type Loading Frame) to replace the previous lever belt scale and suspension belt scale loading structure (Figure 2). The parallelogram structure has no moving parts and therefore does not require maintenance. The lack of friction improves the stability of weighing and can cope with adverse belt loading. This structure makes the modular belt scale unaffected by the eccentricity and position of the loading. As long as the load is applied within half the radius of the belt width at the front end of the parallelogram, as shown in Figure 3, the load is always equal to the load indication of the sensor.