The batching scale is a kind of weighing controller that batches and measures several substances in the object to be weighed according to a predetermined mass ratio. It has a wide range of uses. It can be used for the batching of various materials, and it can also be used for the measurement of one material (hopper scale/quantitative feeder). If it is matched with a packaging and sealing machine, it will be a quantitative packaging scale.
The batching scale is suitable for automatic batching of granular and powdery materials, and is widely used in construction, feed, smelting and other industries. With the development of computer control technology, the batching scale control system gradually adopts automatic control technology to realize automatic batching and automatic mixing, so as to improve the accuracy of batching and improve product quality and output.
The accuracy of the batching scale is directly related to the quality of the product. How to ensure the accuracy and reliability of the batching scale is an important issue. Batching scales often encounter the following problems during use:
1. Verification problem of batching scale
The weighing method of the batching scale is non-continuous cumulative automatic weighing, and the accuracy grade mark of the batching scale is usually +/-0.2%, +/-0.5%, +/-1%, +/-2%. In the daily verification work, the weighing process of the batching scale still needs the intervention and operation of the human body, which belongs to non-automatic weighing, and in the general verification procedures, the static verification with the standard load accounts for the vast majority of the total verification content, so It should be verified according to JJG539-97 digital indication verification regulations.
Generally speaking, the accuracy level of automatic scales +/-0.2%, +/-0.5% corresponds to non-automatic scale accuracy level III, and the accuracy level of automatic scales +/-1%, +/-2% corresponds to Non-automatic scale accuracy class IV.
In the verification, there is still a problem with the selection of the verification division value e. In the author’s work practice for several years, it is rare to see the Chengde sign or the verification division value indicated in the manual, which poses a problem for the verification personnel. The problem is that if you directly take the verification division value e = the actual division value d, not to mention the general batching scale, even some advanced and imported batching scales are difficult to meet this tolerance requirement.
2. Calibration problem of batching scale
There are three main reasons for the error of the batching scale:
One is mechanical components, including force transmission, temperature-induced expansion and friction between components;
The second is the circuit and display instrument, which are mainly affected by temperature, power supply, electromagnetic field, etc.;
The third is the weighing sensor. The quality of the sensor directly determines the weighing accuracy of the batching scale.
After adjusting the eccentric load error, put the standard weight into the bin, and adjust it to match the quality value of the standard weight. Procedural calibration and segmental calibration should be adopted.