Automatic shrink packaging machine control principle and maintenance

Automatic shrink packaging machine is a highly automated equipment. The product is widely used in the pharmaceutical, food and beverage and home chemical industries. The application of shrinking machine can greatly reduce the material and labor costs of the middle box packaging, which has important economic significance.

1, the device principle and structure

Automatic shrink packaging machine is a kind of automatic packaging equipment that combines pneumatic components and mechanical devices and is controlled by plc and other peripheral circuits. The actuator of this equipment is the cylinder. The two-position five-way solenoid valve controls its forward and backward movements. The working position of the cylinder is detected by the magnetic switch and the proximity switch and fed back to the plc. The plc sends a control command to the solenoid valve of the corresponding cylinder through the program, thereby controlling the action of the cylinder.

2, fault repair

2.1, plc fault

Plc faults are mainly output relay contact junctions. If this point controls the motor, the fault phenomenon is that the motor is running after the signal has started the motor. However, after the stop signal is issued, the motor does not stop running. When the plc power fails, the motor stops operating. If this point controls the solenoid valve. The fault phenomenon is that the coil of the solenoid valve is not energized and the cylinder is not reset. If you use external force to hit plc to separate the sticking points, you can help determine the fault.

There are two kinds of maintenance methods for plc output point faults. One of the more convenient ones is to use a programmer to modify the program, modify the damaged output point to the standby output point, and adjust the line at the same time. If the 1004 point of the control solenoid valve is damaged, it is changed to 1105 points of the standby point. The rotor pump can use the programmer to find the relevant statement of 1004 points, keep(014)01004 is keep(014)01105. The 1002 point damage of the control motor is changed to the standby point 1106, and the outbound statement out01002 of the 1002 point is modified to out01106, and the line can be adjusted at the same time.

If you do not have a programmer, you can use the second kind of trouble, remove the plc, open the plc to remove the output relay of the standby point and replace it with the damaged output point. Then press the original line number to install.

2.2, proximity switch failure

The shrink wrapper has five proximity switches. Three are used for knife protection and two are used to control the upper and lower film discharge motors. Among them, for controlling the knife protection, the occasional one or two wrong actions will interrupt the normal operation process, and due to the small number of failures and the short time, it will bring certain difficulties to the failure analysis and elimination. Failures are typically characterized by the occasional fall of the fuser and its automatic lifting. The reason for the failure is that the melting knife does not encounter the packaged material during the descending process, and the fusion knife raises the proximity switch and loses the signal. As soon as the knife guard plate contacts the packaged object, the welding knife automatically returns upward.

The fault repair method can be used to increase the reliability of the fusion knife up-position proximity switch by installing a switch of the same type in parallel and the two switches working in parallel.

2.3, magnetic switch failure

The magnetic switch is used to detect the position of the cylinder and control the stroke of the cylinder. Stacking, pushing, pressing, and cutting the four cylinder movements are related to each other and magnetic switches are used to detect and control their position. The failure is mainly manifested as the following cylinder does not move, because the cylinder speed is faster, resulting in the magnetic switch can not detect the signal. If the pushing cylinder speed is too fast, after the push pack is reset, the press pack and the fuser cylinder will not move.

The fault repair method can adjust the throttle valve on the cylinder and the two-position five-way solenoid valve, reduce the compressed air flow, and reduce the cylinder operation speed until the magnetic switch can detect the signal.

2.4, solenoid valve failure

The failure of the solenoid valve is mainly manifested as the cylinder does not act or not reset because the solenoid valve of the cylinder cannot be reversed or helium.

If the solenoid valve is helium, the air pressure of the machine will not reach the working pressure due to the access to the air path, and the cutter beam will not rise. Knife beam protection proximity switch does not work, the preconditions for the whole machine operation are not established, the machine can not run, it is easy to be confused with electrical faults. Electromagnetic valve helium leak sound, carefully listen to the source and search for leaks by hand, you can usually easily find the helium solenoid valve.