Machine structure, taking 80 blown film machine as an example: (different models, different specifications)
The first part of the feed heating zone is divided into 5 zones:
Mast (6CM diameter), housing 8, 7CM, 11kw motor (host) drive. The heating zone is divided into one, two and three from the inlet.
Next turn up, it is a four heating zone, the machine is called three links, one pass three zones, two pass net export, three pass five zones
The fifth heating zone, which is the discharge zone, is turned from the flat to the top through the 3-port, called the membrane head, which is the most critical part of the machine. The accessory is a blower.
The second part is the traction zone, which is blown up and compressed, and the total height is about 3 or 5 meters. The fitting is an air pump.
The third part is the winding area.
The main materials are: low pressure polyethylene HPPE with high pressure polyethylene LLDPE mixed materials, low pressure material is mainly about 80%, the higher the pressure is added, the better the tension, the disadvantage is that there is no stiffness, too much will cause the film to blow back and forth Swinging, the film that is blown out is not trimmed, and even the last can not be blown.
The next step is to start the blown film process:
First, after the first, second and third districts are preheated, the area should be lower, generally about 170 degrees, and the other areas should be about 200 degrees. If the temperature is high, it is impossible to send it from the mast or even burnt.
Next is the four districts, namely the three links. The three-way 160-mesh filter is used to prevent impurities from entering the five zones. The larger the mesh, the finer the mesh, and the thinner the film, including the transparency of the film, the smoothness of the handle, the tension, etc. However, if too much is too fine, it will stop the passage of the material. If it is too much, it will not blow out. Generally, 3-5 sheets are suitable, and the thickness is determined according to the requirements.
It is expected to be in the five zones, and the discharge port will become 7CM diameter round and sticky paste through the film head, the temperature of the material is basically stable, and the appropriate temperature of the whole heating process should be controlled according to the discharge condition, too high film instability. And burnt discoloration, too low to pull the film. The unevenness of the film thickness of the film must be adjusted by the film head twist.
Then there is the traction zone. After the air is blown into the air bubble of the film head, the gas is added to the middle of the round film, and the film is linearly upward. The size of the plastic bag is controlled by the amount of blowing, and then the film is stabilized by the film stabilizer. The thickness is controlled by the main engine and the traction speed. It can be understood that the faster the main engine speed, the faster the feeding speed and the thicker the film; the traction is just the opposite. The faster the pulling, the thinner the film, which is the most important link.
In order to achieve the horizontal and vertical tensile force of the blown film, it is necessary to achieve a certain ratio of blow-up ratio BUR and traction ratio DDR. Blowing Machine
If the proportional misalignment will lead to a decrease in the transverse pulling force, if the existing die and the folding diameter are used, the bubble is stable, that is, there is no problem with the BUR, and if the bubble is unstable, the BUR is too large;
DDR = die gap / (film thickness × BUR)
Solution: To reduce the DDR, you need to reduce the die gap, and reducing the BUR will only make the DDR bigger (Wang Wang, the objective point of the treasure)
If the film is unstable when the film is blown, it means that the film head is too small, and the fixing frame can be used to stabilize the film.
Finally, the winding is carried out. The film is taken down from a high-altitude angle and wound up by a winder. The speed of the winder can be adjusted according to the speed of the film. After winding, the film becomes the film roll of the required size and thickness. Next is the procedure for the bag making machine.
The film blowing machine can be divided into the upper blowing method (introduced), the flat blowing method, and the lower blowing method according to the direction of the blowing film.