PLC transformation of the operation control system

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PLC transformation of shuttle distributor operation control system

Abstract: Based on the analysis of the drop hammer impact test system of relevant experimental materials used in the contactor control system of the original shuttle distributor, the small PLC is used to cooperate with the frequency converter for automatic operation control, so as to reduce the shutdown accidents caused by contactor damage or other line faults, so as to ensure the reliability of equipment operation, save maintenance costs, and reduce the troubleshooting time, Ensure equipment operation rate

key words: PLC automatic control shuttle auger

abstract:eautomaticoperationcontrolwasonethroughthecoordinationofasmallsizeplcwithafrequencyconverterterterterreducation fixture design 1 is always in a passive situation eclosingdownaccountsduetocontactapparatusamageorbecauseofothercircuits' failuresinordertoensurethereabilityoequipmentrunningandsavemaintenancecostsaswelllocationdownthetimeoffaultdetection toguaranteetheoperatingrateoftheequipment.

Keywords:PLC; automaticcontrol; In the pellet production line, it is necessary to screen the green pellets entering the grate. The green pellets are evenly distributed on the wide distribution belt through the shuttle distributor, and then screened through the small ball screen, so that the qualified green pellets are evenly distributed on the grate bed of the grate

1 process flow

the process of screening and distribution system in pellet production is shown in Figure 1

the material flow on the belt conveyor is less than 0.8m wide, and the material flow after screening by the large ball screen is only about 1m wide. The shuttle distributor is used to evenly distribute the original 1m wide material flow on the 2.8m wide cloth belt through reciprocating motion, and uniformly distribute the qualified green balls on the grate bed of the grate through the small ball screen of the same width, and enter the grate, so as to enter the next process

2 defect analysis of the original automatic control system

the automatic control of the raw screen distribution system is composed of a conventional contactor and a proximity switch. The action of the proximity switch controls the closing and opening of different contactors to realize the forward and reverse rotation of the motor, so as to make the distributor move back and forth. The movement stroke of the distributor is adjusted by adjusting the position of the proximity switch, so that the material flow is evenly distributed on the wide belt. The frequent switching on and off of the contactor has a great impact on the service life of the contactor, so the replacement of the contactor has become an important work for the maintenance of the equipment. The frequent replacement of the contactor causes frequent disassembly and wiring, and the looseness of the wire head brings great inconvenience to the troubleshooting, which greatly prolongs the maintenance time. At the same time, when the equipment stops and starts again, it is necessary to select forward rotation or reverse rotation according to the stop position. If the selection is wrong, it may cause the operation over limit or shutdown fault

although the transmission reduction ratio has been considered in the design, the frequent forward and reverse starting and stopping during actual operation still have a great impact on the motor and track, and the frequent change of speed can not ensure the uniform distribution of materials. At the same time, it also has a certain impact on the service life of the motor by insisting on "bringing in" and "going out"

3 transformation

3.1 original operation control diagram (Figure 2)

according to the actual operation status of the equipment, the equipment data are counted. Mitsubishi fx-1s-20mr Small PLC is selected for transformation to control the operation of the distributor in cooperation with Emerson td1000 frequency converter. Manual and automatic conversion can be realized. Manual control is inching control, automatic operation is continuous operation, and the distributor operates at different speeds set in advance in different areas. At the same time, in the original operation control system, a travel switch is added outside SQ1 and SQ3 to protect the action limit, and a mechanical limit is welded on the track outside the travel switch to limit the operation limit of the distributor, completely avoid cable damage caused by the operation of the distributor exceeding the limit, and avoid derailment and other accidents caused by the exceeding limit

3.2 advantages of this control mode

the PLC control system is used to replace the original conventional wiring mode. The input and output signals are directly connected to the PLC system, which is intuitively reflected on the PLC system panel. It is convenient to realize a variety of control modes, remove cumbersome wiring, and reduce the probability of failure. The equipment operation and maintenance personnel can observe the equipment operation status more intuitively and troubleshoot the failure more easily. At the same time, the memory check function of the parking position is added in the PLC program design to avoid the over limit and other faults caused by the wrong selection of the running direction

the frequency converter is used to replace the contactor to directly control the operation of the motor, which also reduces the increase of fault points caused by the protection system. At the same time, the frequency modulation control can be carried out on the operation speed of the motor, so that the starting and stopping of the motor can be carried out according to the set slope curve, the change of forward and reverse switching is more stable, the operation speed can be set, and it is also convenient to adjust the thickness of the cloth, At the same time, the frequency converter can detect and protect some common faults and display them through fault codes, which is convenient for maintenance personnel to troubleshoot

the implementation of the above schemes makes the troubleshooting more direct and simple, greatly reduces the maintenance time, reduces the workload of maintenance personnel, and makes the equipment operation more reliable and greatly improves the equipment operation rate

4 conclusion

the industrial application of automatic control system is becoming more and more perfect, and the application field is becoming more and more extensive. The use of PLC is not limited by the number of auxiliary contacts of conventional contactors. It is easier to realize the more complex control process that cannot be realized by conventional control methods or is difficult to realize, and the operation reliability is greatly improved. At the same time, the observation and detection of equipment operation status is more direct, and it is easy to control and monitor the whole production process. Application of automatic control system graphene is a kind of two-dimensional crystal, which can liberate employees from frequently repeated work, greatly reduce the labor intensity of employees and ensure the work quality; At the same time, it also makes it easier to determine the location of the fault point, which will not cause work delay due to wasting a lot of time to find the fault point, shorten the maintenance time and improve the equipment operation rate--

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