Bucket-type quantitative packaging scales are commonly used in granular material quantitative packaging systems in the NPK fertilizer production line industry, which are divided into two types: pneumatic and electric.
1. Pneumatic quantitative packaging scale and electric quantitative packaging scale
Pneumatic quantitative packaging scale has a wide range of applications. The advantage is that the packaging speed is fast, the electronic components are few, and the fault judgment is simple. The disadvantage is that the ambient temperature is required. Especially in the cold area in winter without heating, the air pipeline is prone to icing, which affects the braking system. Therefore, anti-icing measures should be taken in the cold area.
Electric quantitative packaging scales have only appeared in recent years, and the manufacturers are mainly concentrated in Harbin. The original intention of the design is to adapt to the use of alpine regions. The advantage is that there is no need to take anti-icing measures. The disadvantage is that there are many electronic components, complex circuits, and it is difficult to judge the failure. Compared with the pneumatic quantitative packaging scale, the packaging speed is relatively slow.
2. Selection of the suspension mode of the weighing bucket of the quantitative packaging scale
Regardless of the quantitative packaging scale, the 3-point upper suspension weighing hopper has good stability, but the price is relatively high. It requires 3 sensors. If there is a failure, it is necessary to judge which sensor has the problem. The side-mounted weighing hopper The stability is worse (it may also be due to the design of the side-mounted packaging scale I used), but the price is relatively cheaper. Only 1 sensor is used. The stability of the 2-point hanging weighing hopper is average. For high-speed packaging not recommended.
3. Selection of control table for quantitative packaging scale
There are not many types of small quantitative packaging scales for NPK fertilizer production process. Generally, pneumatic scales perform well in the F701 series, with fast speed, high accuracy, and easy-to-master adjustment methods. Although the price is high, they are value for money. Manufacturers are free and vary.
4. The overall design and detailed design of the quantitative packaging system
The overall design and detailed design of the packaging system are more efficient to use in NPK fertilizer manufacturing process. After years of use, some good design methods have been found: (1) the quantitative packaging control cabinet should be placed in a closed space as much as possible and not exposed to the production workshop, which can reduce the corrosion of the electrical components caused by the fertilizer dust. If possible, the quantitative packaging system can be isolated from the production workshop, which can reduce the failure rate of the quantitative packaging system and increase the life of components. (2) The finished product silo and the quantitative packaging scale should adopt a soft connection to prevent the vibration of the silo from affecting the measurement accuracy. (3) The bag clamping type of the quantitative packaging scale is better, the bag clamping control switch is preferably a magnetic switch, and the sewing machine switch uses a photoelectric switch, which can make it easy for the production staff to master. (4) For the small belt conveyor for finished product packaging under the quantitative packaging scale, it is better to use a stainless steel mesh belt machine, which will not run off. (5) The seam is well folded manually, and the automatic folding machine is expensive and has a high failure rate.