With the development of electronic technology and computer technology, the quantitative control of products is widely used in various industries and synchronized measurement by means of microcomputer system. Especially small scale quantitative control, requires high measurement accuracy, container out close to or slightly larger than the calibration value of the best calculated value as the output of the material. Conventional quantitative control scale is a single scale, for uniform and small particles of bulk materials, can still barely quantitative weighing, but the fastest container speed of 5 to 15 boxes / min, for uneven items if weighed with a single scale, both the weighing accuracy and speed are more difficult to meet the production requirements. Computerized hopper scales based on combined weighing technology can effectively improve the measurement accuracy and speed, and solve the problem of measuring containers for uneven items. Computerized hopper scales according to the number of hopper head points, there are 8, 10, 14, 16, 20, 24, 28 head, the more commonly used for the 10 head and 14 head. Each head usually includes a buffer hopper and a weighing hopper, hopper capacity of 300L, the minimum scale ± 0.1kg, the fastest weighing speed up to the box / 20min. Computerized hopper scales are an intelligent combination of quantitative and automatic container scales in the weighing industry, the combination of weighing technology will be a simple weighing of the weight of the items to the weight of the product to adjust to meet the needs of large-scale production, expanding the function of the weighing and the scope of application, adding to the concept of weighing, weighing and weighing. Scope of weighing, for the concept of weighing to add new content.

First, the working principle of the hopper scale weighing

Material through the elevator falls in the hopper scale cross-cut hopper, through the main feeder vibration, so that the material in the conical funnel to the product evenly distributed to the linear feeder disk. When there is no material or not enough material in the cross-cut hopper will be measured by the horizontal photoelectric detector, it will send a signal to the main board, and then through the main board to the conveyor to send a feeding signal to add material. The material passes through the linear feeder vibration, through the amplitude and vibration machine time to send the product to each buffer hopper. Then the driving device, i.e. stepping motor, opens the buffer hopper and sends the material into the weighing hopper. Products in the weighing hopper, through the weighing module to produce weight signals, and then through the lead to the main board of the control equipment, the CPU on the main board to read up and record the weight of each weighing hopper, and then through the calculation, analysis, and combination, selected the closest to the target weight of the combination of the weighing hopper, in the CPU receives the container machine to allow the discharge signal issued by the CPU to issue a command to start the drive to open the hopper unloading the product into the container machine, and to the container machine to issue a container signal. and sends a container signal to the container machine. Feeding process in general obeys normal distribution, although the dispersion is large, but if there are enough combinations of the number of units, the combination of multiple units can be obtained as a whole with high precision, the result of feeding is a combination of weighing and calculation, which is fundamentally different from the traditional way of measurement. Utilizing this high-tech working principle, the speed and accuracy can be superior to that of ordinary automatic dosing devices. Moreover, not only irregular lumps can be measured, but all flowable materials can be quantified by computerized hopper scales.

General single-head scale is about to reach the target weight, in order to ensure accuracy, feeding speed can not be too fast, while the computerized hopper scales can be fed quickly, each hopper is usually set at 1/3 to 1/5 of the target weight of the amount of material. hopper scales for the combination of the combination of calculations using only part of the combination of the computer according to the number of heads involved in the combination, according to the following formula can be calculated by the number of combinations: n=Cim=m!/i!(m-i)! , where: m is the total number of weighing buckets, I is the number of buckets involved in the combination. Usually m, I increase, the number of possible combinations increases, the greater the possibility of obtaining qualified products. However, in spite of the fast computing speed of the microcomputer, an excessive number of combinations leads to a reduction in the speed of the container and an increase in cost. From the point of view of rationality and economy, m is usually taken from 8 to 16, while I is generally taken from 3 to 5.

Second, the combination of weighing control system

Hopper scales at work, to complete the 7 boxes/140min (1 box/20s) above the ability to complete the weight detection, combination of calculations, find the best combination, etc., at least in 20s clock, so as to complete a container, which combination of calculations is relatively more time-consuming, high-performance microcontroller or PLC, can be directly completed detection, calculation, control output, not only to meet the hopper scales, the real-time control of the accuracy requirements The control system is a more effective way of control, which can meet the requirements of real-time control accuracy of the hopper scale, and can also meet the requirements of the container speed. When the control system works, the microcontroller or PLC sends signals to the multi-switch, selects 10 weighing modules by time, the signal is amplified, A/D converted and input to the microcontroller or PLC, and performs a combination of the 10 input values to get the number of a group of weighing hoppers where the best combination is located, and according to the number, controls the rotational speed and direction of the corresponding stepping motor, so that the group of material door opens to complete the unloading of material, and then closes the material door The material level in the hopper is detected by a photoelectric detection switch. In addition, the system is also designed with display, alarm and keyboard circuits to make the system function more complete.

Combined weighing technology with its high precision, high speed represents the highest level of today's weighing technology and the direction of development, before our country mainly rely on imports from Japan, Australia and other countries, due to the high price, hindering the widespread use of computerized hopper scales and popularity, but with China's commodity containers to the direction of high-speed, high-accuracy rapid development of the computerized hopper scales will be quickly into the country's commodity processing, container industry. The container industry can be said that the development of the container industry to promote the development of the container industry. It can be said that the development of the container industry to promote the development of weighing technology, at the same time, weighing technology also improves the level of containers to promote the development of the container industry.