Automatic control of the hottest high-precision fi

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Automatic control of high-precision filling production line

organic acids are important raw materials in chemical, food and other industries. Because of their high unit value, various varieties and specifications, and huge production investment, they have high requirements for automatic filling production lines. There is no such production line in China, and it will cost more than several million 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 me, there are three product varieties (1 #, 2 #, 3 #), and there are also three measurement specifications of each variety (a, B, c). Therefore, there will be nine production specifications after the combination. The variety and specifications make 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 (take 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 - 90% × (no fixed value - compensation value) - the flow of the regulating valve section is small - up to 100% × (set value - compensation value) - closing of filling valve - vacuum adsorption - full barrel out of the 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

2.2 functional requirements

1) this production line includes: filling line I (suitable for 30kg filling), filling line II (suitable for 250kg or 1200kg filling)

the shrinkage is smaller

2) filling line I and filling line II can operate independently or simultaneously. However, No. 2 filling line can only produce one specification (250kg or 1200kg) at a time. The operation combination mode of the whole production line includes I, I + II and II; Line I has three filling stations (1a, 1b, 1c), and each filling station must fill three barrels at the same time (corresponding to three flow meters respectively); There are six filling stations (2a, 2b, 2C, 3a, 3b, 3C) in line II. Each time, only machinery manufacturers in Asia and the Pacific can be selected to obtain the advantage of rapid delivery. One filling station can be selected to work (among which 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 four barrels, which use one flowmeter, The filling process is: after the first barrel is filled, fill the second barrel, the third barrel and the fourth barrel in turn; 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 use area, public stations are adopted in the winding and finished product output parts, so 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 arbitrarily), 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:

5) in order to facilitate debugging and maintenance, each conveyor is equipped with on-site manual start/stop switch

6) emergency stop switches are set on the PLC cabinet door, the site, and all human-machine interfaces, so that the operator can 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 an audible and visual prompt of "start preparation". The audible and visual prompt of "start preparation" starts with the selection of "filling station" and ends with the selection of "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-machine 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, you can press the "manual stop filling" button:

11) drip proof design: after the filling is completed, the viscous materials remaining on the surface of the filling head can flow out after a certain time. If they drip outside the container, they will cause pollution. This 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, set up an mb+ master station at plc1, and set up several mb+ sub stations at the place where the input and output equipment BVB subsystem matrix of the production line has undergone strict testing, as shown in Figure 1

since the filling accuracy of the system is very high, if general flow instruments and analog data acquisition and calculation are used. It will not meet the use requirements. Therefore, in the scheme design, in addition to selecting the mass flowmeter of international famous brand as the measuring instrument, we also used the quantum series products of Schneider company, the most advanced in the world, as the main controller on 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 also requires stable flow. 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 it exceeds the upper and lower limits allowed by the system, an audible and visual alarm signal will be sent, and secondary adjustment will be carried out

in order to facilitate users 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" (that is, the value of 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 label data such as weight:

1) PC1 in the central control room monitors the whole production line and some key equipment on site in real time

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

3) the configuration of plc1 is (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 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) configure a 16 point analog input module on plc1 as the monitoring of instantaneous flow:

5) configure three high-speed counting modules on plc1 as the flow measurement, and 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+ that can't stretch tools into the blender during operation. See Table 4 for the hardware configuration and address definition of the stripping station:

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, the project progress is extremely smooth, and all parameters meet or exceed the technical standards of user acceptance, Especially, the measurement accuracy is controlled within ± 0.1% (the 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 domestic gap, and is another successful application of high-end industrial control products in the field of enterprise automation production, which also provides a strong guarantee for the promotion of similar projects. (end)

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