With the increasing competition in the plastics industry, film blowing machines are developing towards high speed and wide width, and film blowing machines also require larger and larger film roll diameters and higher and higher roll film quality. With the development of air pressure technology, high-speed automatic film blowing machine in a very high roll film quality, film folding width up to 2.1m, speed up to 80m/min or more, roll film diameter up to 1m, the output can reach 400kg / h. The traditional change of roll mechanism in the process of changing rolls: not only the operation is troublesome, physical labor intensity, and in the slitting into multiple films (more than 3 films on one side) or do small film frequently When changing rolls, it is easy to produce scrap. In order to solve the above problems, this article introduces how to use PLC to control the reel change mechanism of high-speed film blowing machine to achieve automatic reel change.

High-speed film blowing machine

Composition of the traditional roll changing mechanism.

The traditional reel change mechanism of blown film machine consists of lower turntable device, length counting device, duplex winder, etc.

The turntable device is located on the winding roll, which is shaken by the handle of reel change and driven by the chain to make the turntable support and manipulator to do the turning movement.

The length counting device receives signals from the proximity switch to the counter and counts every meter. The film length is set by itself in advance, and when the winding reaches the set length, the alarm bell and the light will alarm.

The duplex winder consists of A winding and B winding, which adopts the passive winding form and uses the friction between the knurled big rubber roller and the winding roller to wind the film with constant tension.

The driving of A and B winding rolls is done by two vector frequency converters separately controlling the reducer motor, and the speed of A and B winding rolls is the same and the direction is opposite, so as to achieve the purpose of simultaneous winding on both sides, and the winding speed and winding tension of A and B winding rolls can be adjusted separately without affecting each other, so as to get the best winding effect. This rewinding system adopts passive rewinding, and the quality of its rewinding depends largely on the curved trajectory of the guide rail where the rewinding air expansion shaft is located.

Traditional rewinding process: when the rewinding diameter reaches the requirement, rewinding is carried out by moving the preparatory gas expansion roller to the top of the rubber roller (preparatory station), manually separating the film, moving the film roll to the bow tail of the fish belly plate, and then shaking the rewinding handle to slowly move the newly replaced rewinding gas expansion shaft to the rewinding station, and rewinding is completed.

The disadvantages of the traditional rewinding mechanism.

1. In the process of changing rolls, the operation is physically labor-intensive: when the winding is full, one person shakes the handle to change the rolls and shakes the gas expansion shaft on the turntable to the area to be changed, and two people move the full rolls to the imperial roll area at the same time, and then manually cut off the film, and the whole process needs three people to cooperate to complete.

2. When slitting into multiple films (more than 3 films on one side) or making small film change rolls, more people are needed to cooperate to complete the process, and the unskilled or improper operation will easily produce scrap.

How to solve the above problems

Manual reel change to automatic reel change: on the basis of the traditional reel change mechanism, the automatic reel change mechanism with the functions of automatic reel loading, automatic cutting, automatic reel feeding, etc. is added.

The transformation of automatic reel change system.

Automatic winding: on the basis of manual winding, the winding handle is removed and a reducer motor is modified on top of it to be controlled by PLC as the turning power source.

Automatic cutting: add a cutting cylinder (rodless cylinder) on the turning frame, the cylinder shaft and precision pressure reducing valve, shuttle valve, air lock valve, pilot check valve, flow valve and other control components of the air circuit, the use of gas force to push the rodless cylinder shaft of the flying knife for round-trip cutting movement; at the same time, each side to add a magnetic cylinder to rodless cylinder to do the control circuit of the air circuit.

Automatic roll feeding: add a magnetic cylinder and robot on each side of the winding roll, connected by the shaft into a symmetrical shape, add a precision pressure reducing valve, shuttle valve, airlock valve, pilot operated check valve, flow valve and other control components in the air circuit, when the winding is full pan cylinder release pressure, so that the pan cylinder reach forward to push out the full roll to the imperial roll area is locked by the mechanical lock, after the pan cylinder back to the position, pan cylinder to maintain pressure.