Combination weigher analyzes the factors of the
The combination said that since its advent in the 1970s, it has been widely used in food, medicine, chemical and other industries. It solves the problem of measurement and packaging of uneven materials. It has the characteristics of high measurement accuracy, fast packaging speed and high reliability. For some high-value granules or block products, fast and accurate quantitative packaging can be achieved, the accuracy can be controlled within ± 1.5 grams, and the weighing speed is as fast as 240 bags / min. The import portfolio says its price is very expensive, which limits its application.
Combined weighing is a kind of industrial weighing scale with fast measuring speed and high accuracy, which is made by the principle of combined weighing. The measurement accuracy and speed of the combination scale are related to the combination calculation model, mechanical structure, control system and other factors. The combination calculation model is an extremely important factor. The material weight distribution has a direct relationship. Since a large part of the material weighed by combination weighing is poor in fluidity, the electromagnetic vibration feeder is selected as its feeding device. This article aims to analyze the performance of the electromagnetic vibration feeder and establish a digital control method on this basis to prepare for the combination calculation model of high precision and high speed for the combination scale.
Combination scale The combination scale of the manufacturer needs to complete the ability of more than 70 packs / min (1 pack / s) when working, that is, at least 1s to complete the weight detection, combination calculation, find a better combination, etc., so as to complete a packaging Among them, the combination calculation is relatively time-consuming. The high-performance single-chip or PLC can directly complete the detection, calculation, and control output. It can not only meet the accuracy requirements of the combined scale real-time control, but also meet the packaging speed requirements. It is a more effective control method.
When the control system is working, the single-chip or PLC sends a signal to the multi-way switch, time-sharing selects 10 weighing sensors, the signal is amplified, A / D converted, input to the single-chip or PLC, and the 10 input values ??are combined and calculated. Obtain a group of weighing hopper numbers where the better combination is located, and control the speed and direction of the corresponding stepper motor according to the numbers to open the material door of the group, complete the discharge, and then close the material door; the material level in the storage hopper is detected by photoelectric Switch detection. In addition, the system has also designed display, alarm and keyboard circuits to make the system more complete.
The main factors affecting the feeding quality of the electromagnetic vibration feeder are: the vibration angle of the electromagnetic vibration feeder, the effective value and frequency of the excitation voltage, etc., the thickness of the material, the feeding time, etc., the greater the thickness, the longer the feeding time, each feeding The greater the quality. In the combination scale, also because the feeding quality of each hopper is not too large, the material thickness should be smaller if it meets the requirements. In addition, because there are multiple electromagnetic oscillating feeders feeding at the same time, there will also be some interference between each other, affecting the weight of the material. At work, it is also very important to strengthen vibration isolation measures.