logxlogx

EN
nan4
画板 1 拷贝
TECH-EXHI
Recommendations
Weighing liquid filling machine control system
2020.02.19

Summary:The liquid filling machine adopts a two-stage adjustable filling method for large and small materials, which improves accuracy and production capacity; it is equipped with an automatic protection function for the top barrel, which is used to automatically lift the filling gun when it is not inserted into the barrel, and does not perform filling. Loading; unique anti-drip device to prevent materials from dripping on the barrel and scale platform, affecting packaging and rollers; two filling modes, net weight and gross weight, can be selected to meet the different filling needs of users.

0Introduction

Liquid quantitative filling machine usually has a volumetric and weighing type 2 methods for the requirements of the weight measurement of liquid filling, volumetric filling speed, but due to the filling volume by the specific gravity of the liquid, temperature, etc., so the filling accuracy is lower, only for the occasions that do not require a high degree of accuracy. Weighing filling machine is directly based on the weight of the weighing control, not affected by the specific gravity of the liquid, temperature, etc., can be easier to obtain a high filling accuracy, especially for high value of the liquid high-precision filling, but its filling speed is slower, weighing type filling is used to calculate the segments.

1 In order to improve the filling speed under the premise of ensuring the filling accuracy, weighing type filling mostly adopts segmented filling. The so-called segmented filling is a filling cycle is divided into several time periods, each 1 time period of the filling flow rate successively from large to small variable flow filling. To commonly used two filling, for example, always hope that in the time period can be a larger flow rate filling as much liquid to improve the filling speed, in t time period is a smaller filling flow rate to meet the accuracy requirements. Therefore, a reasonable choice of size flow rate and accurately determine the switching point of the size flow rate is the key to improve the filling speed as much as possible while ensuring the filling accuracy.

Filling valve port section design and size flow switching, due to the filling process is a dynamic process, weighing instrument in the process of any moment of the display value will certainly be affected by the liquid impact momentum, so the formula to take the size of the unchanged flow switching point is not the optimal point of switching, it is necessary to weighing liquid filling segmented filling volume design.

Filling process weighing instrument at any moment in the display value for the actual filling volume and liquid impact momentum sum, in the whole process, is a change from the maximum value tends to zero variable. If we use the unchanged switching point of the size of the flow rate, that is, the display value of the weighing instrument in the switching moment is unchanged, then in the filling volume is larger, the liquid impact momentum is larger, high-flow filling to reach the switching point at the moment of the actual filling volume is smaller, which will lead to the prolongation of the time of the small-flow filling, reducing the speed of the filling. On the contrary, in the filling volume is small, the liquid impact momentum is small, high-flow filling to reach the switching point moment of the actual filling volume is larger, which will lead to the shortening of the small-flow filling time, so that the filling accuracy is not guaranteed. Through the above analysis and research, a conclusion can be drawn, that is, the optimal switching point of the size of the flow should be a real-time adjustment. The size of the liquid material impact momentum depends on the size of the flow rate at the valve port 2 section related to the filling volume. Because the valve port 2 cross-section area has been determined by the design, so available to test the amount of change per unit of time weighing instrumentation that is the flow (indirectly reflecting the size of the impulse) to the size of the flow switching point for coarse adjustment. Also proved by the test, small flow filling time in 1.5 ~ 2s, can basically guarantee the accuracy of the filling requirements. Therefore, through the test small flow filling of the actual time, with its filling precision requirements to ensure that the difference between the small flow filling time required to fine-tune the size of the flow switching point, so that the size of the flow switching point in real time to adjust to the near-optimal value.

2 control system design

The required filling volume and filling accuracy requirements to ensure that the filling time required for small flow filling are pre-set by the human-machine interface, the initial size of the flow rate switching point to take 0.9M (M for the set weight).

Taking into account the actual filling process, in the high-flow filling and low-flow filling stop there will be a period of subsequent liquid flow, so in the programming should pay attention to make the switching point and stop the low-flow filling with an amount of advance. In addition, the final value in the control flow chart is also a reference value, after the end of the filling with the actual filling volume and the standard volume for comparison, by comparing the results of the value to be adjusted.

3Summary

Because the real-time adjustment method is adopted, individual unqualified filling products will be produced in the initial stage of filling, but through automatic adjustment, the filling requirements will soon be met. This control system was used on the weighing and filling machine to obtain relatively satisfactory results. From the beginning of the filling to produce qualified filling products only 3 filling cycle, and filling error control in 2kg within 15g (the requirement is within 20g), and to achieve the filling speed and accuracy of the best match.

Multi-station liquid filling machine
The field management and control system of liquid filling machine based on single chip microcomputer, radio frequency card and network integration technology can control the filling of materials in real time and effectively. Realize the real-time detection of filling weight and the real-time opening and closing of solenoid valve in filling process, and upload data for effective microcomputer management.
Application of liquid pumping and mixing batching system
The batching system adopts dual CPU to form a redundant system, and the STEP7MicroWin V4.0SP6 programming software provided by Siemens is used as the man-machine interface to write debugging programs and download programs. The PC and PLC experimental machine are connected by a PC/PPI cable for communication, and the corresponding parameters are set.
Automatic liquid filling machine function application
Automatic liquid filling machine is controlled by frequency converter to realize stepless speed change, set the target weight, easy operation and fast filling speed, adopting large and small feeding and filling methods, optional computer connection or real-time printing of filling parameters such as filling date, serial number, net weight, tare weight, cumulative weight and so on.
×