Application of the hottest PLC in synchronous driv

2022-07-24
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Application of PLC in synchronous drive system of paper machine

1 introduction K. machine size: about 720 × five hundred × 1900mm long × wide × High)

in the production of plastics, printing and dyeing, papermaking and textile, there are often many synchronous drive single units, and each unit has its own independent drive system. At the same time, it is required that the running linear speed of the processed objects (cloth, paper, etc.) between units can be consistent, that is, to achieve synchronous movement. Although there are many kinds of papermaking equipment and different transmission structures, they are all composed of pressing, drying, calendering, coiling and other parts, and each part is driven by a motor. Papermaking process requirements: when the equipment is driven, it shall ensure that the paper has a constant speed and constant tension during the transmission of each part. At present, the best control scheme for paper-making equipment to achieve this requirement is variable frequency speed regulation, and there are two main types of frequency converter control: one is PLC control, and the other is IPC or industrial computer control [1][2]. This paper uses PLC control to realize synchronous transmission of paper machine

2 synchronous drive system of paper machine

2.1 analysis on control requirements of paper production line

Figure 1 shows the panel diagram of the operation console of the paper production line. Since the system is composed of multiple units, each unit is required to keep synchronized, thus forming a synchronous drive control system. Requirements for synchronous control:

Figure 1 console layout

(1) unified commissioning: each unit shall be able to increase and decrease speed at the same time. The unified adjustment is based on the speed requirements of the main command unit (usually one unit)

(2) local fine adjustment: when the operator finds that the speed of a unit is not synchronized, he can make fine adjustment (manual intervention). During fine adjustment, the speed of each unit after the unit must be increased or decreased at the same time, rather than one by one

(3) separate fine adjustment: in the maintenance and commissioning stage, or in case of special circumstances, it must be able to perform separate fine adjustment for each unit

assuming that the production line is composed of four units, the operation of each unit can be visually displayed by its own line speed meter

2.2 synchronous operation

(1) when the unified debugging operation is carried out, switch the single/unified debugging switch to the position of the unified debugging, and synchronously control the four units through the increase/decrease of the unified debugging button

(2) when it is found that the speed of a unit is not synchronized, it can be adjusted synchronously. For example, when unit 2 needs to be adjusted, unit 2~4 will increase or decrease the speed at the same time

(3) when the speed of an individual unit cannot keep up for some reason, it needs to be tightened. For the papermaking system, it is necessary to press the tightening button to increase its speed for a short period of time to achieve the tightening effect

in order to facilitate the operator to intuitively understand the system operation, each operation has corresponding indicator light display

2.3 paper machine synchronous drive control principle

(1) the start and stop of the frequency converter

is shown in Figure 2. Taking the frequency converter control diagram of unit 1 as an example, SA13 is the start switch of the frequency converter. When SA13 is connected, the operation indicator lamp la11 is on, the stop indicator lamp la12 is off, and the frequency converter is in operation; When the frequency converter stop button SA12 is pressed, the coil ka13 loses power and the frequency converter stops running

Figure 2 1 control diagram of frequency converter

(2) system/monotone control

system/monotone switch SA11 is placed in the unified debugging position. At this time, coil ka12 is connected and the production system is in the unified debugging state. Through the synchronizer, 1-4 can be adjusted for speed up and speed down at the same time. When it is switched to the monotone position, coil ka12 is powered off, and coil KA11 is powered on to enter the synchronous fine-tuning state. At this time, the frequency converter and the following units can be adjusted

(3) tighten

when the normally open switch SA14 is closed, the coil ka14 is powered on. At this time, the frequency converter will get a momentary higher voltage from the outside to control the unit speed to the normal level; Disconnect SA14 and restore the unified debugging state of

Figure 3 shows the wiring diagram of the production system composed of four control units

Fig. 3 control system composed of four control units

2.4 PLC control of synchronous drive system of paper machine

the synchronous system of paper machine is reconstructed by using Omron's programmable controller cpm1a-40cdr-d [3][4], two digital signal input terminals X1 and X2 are selected to be used for speed up and speed down through function presets, and the tightening function is integrated into the independent fine adjustment of each unit at the same time; The control system diagram after transformation is shown in Figure 4

Figure 4 synchronous system controlled by PLC

(1) control principle

when the FWD end from vfd-1 to vfd-4 receives the input signal, it starts; Stop when the signal is lost

X1 terminal of vfd-1 gets signals when the speed is increased and monotonically increased, and X2 terminal gets signals when the speed is decreased and monotonically decreased

X1 terminal of vfd-2 gets signals when the speed of vfd-2 is increased by unified adjustment, the speed of 2~4 units is increased by synchronous fine adjustment and monotonic speed increase, and X2 terminal gets signals when the speed of vfd-2 is decreased by unified adjustment, the speed of 2~4 units is decreased by synchronous fine adjustment and monotonic speed decrease

X1 terminal of vfd-3 gets signals when the speed of vfd-3 is increased by unified adjustment, the speed of 2~4 units is increased by synchronous fine adjustment, the speed of 3~4 units is decreased by synchronous fine adjustment and monotonic speed increase, and X2 terminal gets signals when the speed of vfd-3 is decreased by unified adjustment, the speed of 2~4 units is decreased by synchronous fine adjustment, the speed of 3~4 units is decreased by synchronous fine adjustment and monotonic speed decrease

X1 terminal of vfd-4 gets signals when the speed of vfd-4 is increased by unified adjustment, the speed of 2~4 units is increased by synchronous fine adjustment, the speed of 3~4 units is decreased by synchronous fine adjustment and monotonic speed increase, and X2 terminal gets signals when the speed of vfd-4 is decreased by unified adjustment, the speed of 2~4 units is decreased by synchronous fine adjustment, the speed of 3~4 units is decreased by synchronous fine adjustment and monotonic speed decrease

(2) i/o allocation

the i/o address of the input end of this type of PLC is:; The i/o address of the output end is:

i/o allocation table is shown in the attached table. Attached table i/o distribution table

(3) ladder diagram control program

PLC control ladder diagram of synchronous system of paper machine is shown in Figure 5. The investment payback period is 3.8 years

Figure 5 PLC control ladder diagram of paper machine synchronization system

3 conclusion

according to the above design, Jinan Shijin has made great efforts to create, protect and improve the brand. We have adopted Omron's programmable controller cpm1a to test the paper machine synchronization system with its impact test equipment -40cdr-d, Delta ved-b frequency converter and SCD synchronizer. The effect in operation is good, which fully shows that it has strong function, simple structure, easy maintenance and overhaul, high reliability and waiting point, and has achieved the expected purpose and broad application space

this article is extracted from plc&fa (end)

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