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Control of automation technology in high-precision filling production line

organic acid is an important raw material in chemical industry, food and other industries. Due to its high unit value, various varieties and specifications, and huge production investment, it has high requirements for automatic filling production line. There is no such production line in China, and it will cost millions of dollars to import from abroad. Therefore, domestic development can not only save foreign exchange, but also provide users with timely and convenient services, and greatly improve the automation level of enterprise production, which is of great significance

1. System process description

in the organic acid automatic filling production line project undertaken by us, the user has three product varieties (123), and each variety has three measurement specifications (a, B, c). Therefore, there will be nine production specifications after the combination. The variety of varieties and specifications makes the system configuration and function more complex. The organic acid is characterized by strong corrosivity, high product value, unstable density, and unstable flow rate and pressure. Therefore, in the process of design and manufacturing, users not only have high requirements for the corrosion resistance of the materials used in the production line, but also require to prevent dripping during the filling process, and put forward more stringent requirements for precision and speed

1) filling material temperature: 5 ~ 35 ℃

2) material density: organic acid about 1.2g/cm3, organic acid salt about 1.3g/cm3

3) material viscosity: organic acid about 50CP, organic acid salt about 150cp

4) inlet pressure of feed pipe: ≥ 0.2MPa, fluctuation range: ± 10%

5) layout area of filling equipment: 1200m2

6) main parameters of the system are as follows,

7) the system process is as follows (taking line I as an example):

empty barrel sorting - empty barrel entering the filling station - Detection and positioning - filling head lowering - filling valve opening - filling start - quality measurement - reaching 90% × (no fixed value? Compensation value)? The flow of regulating valve joint is small? It reaches 100% × (set value - compensation value) - closing of filling valve - vacuum adsorption - full barrel out of filling station - steering - capping - screwing - Labeling - stacking - winding - finished product output

8) process of line II (omitted)

2, control content and functional requirements

2.1 control content, see table 2

2.2 functional requirements

1) the production line includes: filling line I (applicable to 30kg filling), filling line II (applicable to 250kg or 1200kg filling)

2) filling line I and filling line II can operate independently or simultaneously. However, No. II filling line can only produce one specification (250kg or 1200kg) at a time. The operation combination modes of the whole production line include I, I + II and II; Line I has 3 filling stations (1a, 1b, 1c), and each filling station must fill 3 barrels at the same time (corresponding to 3 flow meters respectively); There are 6 filling stations (2a, 2b, 2C, 3a, 3b, 3C) in line II, and only one of them can be selected for work each time (2a and 3a share one flowmeter. 2B and 3b share one flowmeter...), while 2a, 2b and 2C (250kg specification) are placed on the pallet in a group of 4 barrels. The 4 barrels use one flowmeter. The filling process is as follows: after the first barrel is filled, fill the second barrel, the third barrel and the fourth barrel in turn; However, each station of 3a, 3b and 3C (1200kg specification) can only fill one barrel at a time:

3) when the operation mode of the whole production line is I + II, in order to save equipment investment and workshop area, public stations are adopted in the winding and finished product output parts. Therefore, when entering the public stations, programs must be prepared to avoid:

4) convenient data setting and display: one-time filling volume (65 ~ 99%), final set value (100%) Compensation amount (to prevent overshoot, which can be adjusted at will), qualification determination interval setting, qualified product count, unqualified product count, total output (barrels), total filling volume (weight), upper (lower) limit alarm setting and display of instantaneous flow:

5) to facilitate commissioning and maintenance, each conveyor is equipped with a field manual start/stop switch

6) emergency stop switch shall be set on PLC cabinet door, site and all human-computer interfaces to facilitate the operator to stop at the fastest speed in all areas of the site:

7) for program operation, it is effective when "filling station" is selected first, and then "automatic" is selected. It starts to run, otherwise it is invalid

8) in a prominent position in the workshop, set up an alarm light and "start preparation" audible and visual prompt. The "start preparation" audible and visual prompt starts from selecting "filling station" to selecting "automatic". The sound and light prompt is intermittent sound, and the alarm sound and light is continuous sound:

9) the flowmeter includes frequency counting output (FC) and analog output (FA). The frequency output is used for cumulative flow filling measurement, and the analog output is used for instantaneous flow upper and lower limit alarm:

10) "filling press key", and the status and equipment fault indication are set on the human-computer interface. There are text prompts during the filling process. After the automatic filling is completed, reset the "start filling" button, During the filling process, if you need to stop filling, you can press the "manual stop filling" button:

11) drip proof design: after filling, the viscous materials remaining on the surface of the filling head can be drained after a certain time. If they drop outside the container, they will cause pollution. The filling system adopts the vacuum generator back suction system to ensure no drip and leakage

3. System composition and control scheme

3.1 composition of control system,

3.2 description of control scheme

in order to reduce field wiring as much as possible, make the system more reasonable, more complete in function and more convenient in operation, a mb+ master station is set up at plc1, and several mb+ sub stations are set up at the place where the input and output equipment for test speed interruption verification and verification of the production line is required, as shown in Figure 1

as the filling accuracy of the system is very high, if the general flow instrument and analog data acquisition and calculation are used. It will not be able to meet the use requirements. Therefore, in the scheme design, in addition to selecting the internationally famous brand mass flowmeter as the measuring instrument, we also used the most advanced quantum series products of Schneider company as the main controller in the data acquisition and control terminal; In order to quickly collect the frequency output pulses of 12 mass flow meters, three high-speed counting modules (5 channels/module, 100kHz) are configured, which have fast collection speed, simple and convenient hardware configuration

high accuracy and stable flow are also required. On the one hand, the high-level tank is used to adjust the liquid level and pressure to keep it in a relatively constant area. On the other hand, the analog output (4 ~ 20mA) of the mass flowmeter can be used to conveniently monitor the instantaneous flow in the pipeline. Once the upper and lower limits allowed by the system are exceeded, an audible and visual alarm signal will be sent and secondary adjustment will be carried out

in order to facilitate the user to modify the data variables on site, there are three magelis man-machine interfaces on site: OP1 and op2 screens can operate and display the whole production line. OP1 is mainly used to set and display the "station selection", "one-time filling volume" (i.e. the value from filling to about 90% of the final filling volume, which can be modified at will), "final filling volume" (100%), and "compensation volume" (to prevent overshoot) Qualification determination interval setting, qualified product counting, unqualified product counting, total output (barrels), total filling volume (weight), upper (lower) limit alarm setting and display of instantaneous flow: op2 is mainly used to set and display relevant data of 250kg/1200kg filling line, the rest are the same as OP1, OP3 is used for data setting and display of labeling equipment, and can be used for category, batch number, production date, expiry date Modification and display of weight and other label data:

1) PC1 in the central control room monitors the whole production line and some key equipment on site in real time when they exceed the specified test range

2) plc1 is a quantum PLC product, plc2 is a momentum I/O base plate:

3) plc1 is configured as (64di, 128do, 12hsc, 12ai), one 10.4 "man-machine interface is connected through the MB port on the CPU, and the CPU is also connected with the momentum substation (substation 2, 32di; substation 3, 32do; substation 4, 32do; substation 5, 32do) and another 10.4" man-machine interface (substation 6) through the mb+ port

4) a 16 point analog input module is configured on plc1 to monitor the instantaneous flow:

5) three high-speed counting modules are configured on plc1 to measure the flow, Each module includes five measurement channels:

6) see Table 3 for the hardware configuration and address definition of plc1-quantum:

7) see Table 4 for the hardware configuration and address definition of mb+ stations: however, at this stage, China's universal tensile testing machine industry mainly focuses on low-end products

4. Application summary

the control system of the filling system integrates computer technology, programmable control technology, data setting and display technology, bus technology High speed counting technology, sensor technology and software programming technology. The scheme design is advanced, the software and hardware configuration is reasonable, and the project progress is extremely smooth. All parameters meet or exceed the user acceptance technical standards, especially the measurement accuracy is controlled within ± 0.1% (acceptance standard is ± 0.125%), and the speed is within 3 barrels/minute · 30kg. After two months of trial operation, the whole production line passed the user acceptance on site at one time. Now, the system has been running stably for nearly a year and has been fully affirmed by users (especially foreign technicians)

the successful development of the filling production line fills the gap in China. It is another successful application of high-end industrial control products in the field of enterprise automation production, and also provides a strong guarantee for the promotion of similar projects

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