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Very applicable: Fault Maintenance Method for the Automatic Shrinking Machine

Automatic shrink packaging machine is a high degree of automation equipment, and the machines are widely used in medicine, food and beverage and household chemistry  industry, application of shrink machine can greatly reduce the use of packaging materials and labor costs, and has important economic significance.
1, equipment principle and structure
Fully automatic shrink packaging machine is a combination of pneumatic components and mechanical device, an automatic packaging equipment made by the PLC and other peripheral circuit control. The actuator of the device is a cylinder. Controlled by five bit two solenoid valve for its forward and backward. The working position of the cylinder is controlled by the magnetic switch and the proximity switch is detected and fed back to the PLC, and the solenoid valve of the cylinder is issued by the PLC.
Vacuum Packing Machine
2, fault repair
PLC fault mainly includes output point relay contact adhesion. If the point controls motor, fault phenomenon is that a signal to start the motor leads motor operation, but after the cessation of the signal, the motor does not stop running, when the PLC power failed, the motor will stop running. If the point control solenoid valve, the fault phenomenon is that the solenoid valve coil is constant and the cylinder is not reset. If an external force impact PLC is used to separate the adhesion points, a method can be used to determine the fault.
PLC output point of failure repair method has two kinds, one more convenient  method is using the programmer to modify the program, and changes the damaged output point as standby output point, meanwhile adjusting the line. If control of 1004 points of the solenoid valve is damaged, change it to 1105 points. The available programmer finds relevant statements 1004, change keep (014) 01004 to keep (014) 01105. If Control motor 1002 point is damaged, change it to point 1106, modify the relevant statement out01002 to out01106, at the same time, modify the line.
If there is no programmer, a more complex way can be chose: remove the PLC, use the  alternate output points to replace the damaged output. And then making the original installation can be OK.
Vacuum Packing Machine
Proximity switch fault
There are five proximity switches in the shrink machine packaging machine, three for the protection of the knife, two for the control of the upper and lower membrane membrane motor. The one used to control the protection of the knife will interrupt the normal operation process as for the occasional wrong actions, and because of the small number of failures occurrence, the time is short, so it brings certain difficulties to the failure analysis and the exclusion. The typical performance of the fault is the occasional unplaced drop of the knife and the automatic lift. The reason is that the welding knife doesn’t encounter the packaging material in the process of the decline, and the fuse to close the switch loses the signal, and the protection of the knife plate contact with the same as the packaging, and occurs the automatic return of the knife.
The method of fault maintenance is to fuse the fuse knife into a switch in parallel to install one of the same type of switch, double switch parallel operation to improve its reliability.
Magnetic switch failure
Magnetic switches are used to detect the position of the cylinder and the control of the cylinder. Four cylinder motions of stack, push, pack, press pack are associated with each other, and the magnetic switch is used to detect and control their positions. The failure is mainly that the follow-up of the cylinder does not move, the reason is that the too fast cylinder speed causes that the magnetic switch can not detect the signal. If the cylinder speed is too fast, the pressure pack and the cylinder does not move after the reset.
Fault maintenance method is adjusting the cylinder and its five bit two solenoid valve on the throttle valve, adjusting the compressed air flow to be smaller, reducing the operation speed of the cylinder until the magnetic switch can detect signal.
Solenoid valve malfunction
Solenoid valve failure is mainly manifested that the cylinder does not move or not reset, the reason is that the cylinder solenoid valve can not change direction or gas channeling.
If it occurs the solenoid valve gas channeling, due to the same gas output and input channel, the pressure of the machine can not reach the working pressure, the rise of the knife is not in place. Knife beam protection that closes to the switch does not work, so the first condition of the whole machine running is not set up, the machine can not run, which is very easy to be confused with the electrical fault. Electromagnetic valve gas channeling have a leak sound, so you can carefully listen Sonic Source and search leak points by hands, and it is easy to identify the the solenoid valve of gas channeling.

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