PLC control design of the sealing ring packaging l

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PLC control design of engine sealing ring packaging line

1 control requirements and control principle of the packaging line

the process flow of the packaging line is: packaging sheet heating, sheet blister forming parts matching, cartoning and capping, packaging and punching products outside the output line. The system control includes two parts: circuit (whole line driving and power on heating) and pneumatic system control. When the whole line is dragged, all mechanisms stop moving, and when the dragging stops, all mechanisms work. The movement of the mechanism is driven by the cylinder. Dragging along the whole line makes each process enter the next step in turn. One of the future research is to launch arc toothed belt wheels (3) and (4) respectively equipped with driven and active. The electromechanical power is transferred to the main shaft through the arc toothed synchronous belt (5). The length of the innovative plasticizing concept energizer station is dragged by a stepping motor

the driving cylinder of the blister station is a, and the driving cylinder of the heat sealing station is D. the same main control valve is used to obtain synchronous movement; The two sets of driving cylinders of the cartoning station of parts are B and C, and their actions have strict interlocking requirements; The driving cylinders of the punching station are e and F, and the same main control valve is also used to control their synchronous movement

the control system of the assembly line is a closed position program control line. According to the control requirements, after starting the initial signal, the logic control line sends an execution signal to command the actuator to perform the first step of action. The actuator triggers the travel switch at the end of its travel and sends a master signal. After the master signal is input into the line, it sends an execution signal of the second step of action through logic operation. The whole system sends out the execution signal and receives the master signal according to the designed logical sequence to complete the control cycle, and the actuator acts in strict sequence according to the execution signal. For this kind of control system characterized by strict sequence requirements, it is very appropriate to choose PLC for control

plc works by circular scanning. A complete scanning process is divided into three stages: sampling input, program execution and output refresh. In the sampling input stage, the state of each input end is sent to the corresponding register, which is equivalent to the control system receiving the master signal fed back by the actuator. However, the logic line control is to feed back the master signal to the system after executing the previous step in sequence. The control system will send the next execution signal after performing the specified logic operation according to the master signal. The control is carried out and completed in the process, PLC receives the master signal of each stage and stores it for standby; The second stage is the program execution stage. The microprocessor of PLC executes instructions one by one, and calls out the corresponding command signal in the input status register, which is closely related to China's extruder products and strategic new industries, and processes it together with the original operation results, including logical and arithmetic operations, and sends the results to the output register. Because PLC executes instructions one by one, its operation characteristics ensure the sequence of the action of the actuator, and the line operation is greatly simplified because it does not need to consider eliminating the obstacle signal to prevent the occurrence of mechanism malfunction; The third stage is output refresh: the execution signal of the output status register is converted into voltage or current signal output through the output part of PLC to drive the actuator

2 control flow and control design of the system

according to the requirements of automatic control of the packaging line and the control characteristics of PLC, the first step in the design of the control system is to draw the control flow chart of the system, as shown in Figure 1

Figure 1 automatic packaging line control flow chart

from the flow chart, we can see that this is a multivariable, multi reciprocating work program. The driving cylinders B and C of the parts matching cartoning station reciprocate three times in a motion cycle. Each output control point of PLC machine can only output (out) once in a scanning (motion) cycle and cannot be reused. In the control design, three control output points are arranged for each one-way movement of B and C main control valves. When PLC executes each command in sequence, the main control valves of cylinders B and C will move back and forth orderly

considering the control requirements, technical indicators, economy and output input interface, there should be a certain margin. C-40p series microcomputer of OMRON company is selected. The basic unit of this machine has 24 points of input and 16 points of output, and the output can be expanded to 32 points

assign the address of the output and input interfaces, as shown in Figure 1

13 timers are arranged when designing control instructions. In addition, 19 intermediate relays with address code 1000 series are enabled. The address numbers of the timer and intermediate relay are only used as special codes (mnemonics) in the control instructions, which are programmed into the ladder diagram or simple program, input into the programmer, and the PLC machine performs the calculation. Draw PLC control ladder diagram. As shown in Figure 2. (the ladder diagram is abridged due to space limitation)

Figure 2 system control ladder diagram

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