The cleaning and maintenance of the three-layer coextrusion film blowing machine are as follows:

Resin cleaning method

This method is to clean the machine with resin, such as polyester resin or epoxy resin. This method is generally used when the cleaning machine or extruder of new equipment is used for a period of time. Due to the gelatinization of some materials on the screw or screw barrel, the extrusion speed of materials becomes slow, and the color difference of color change varieties is large, this method can be used. After the resin is cleaned, the PVC resin to be produced is used, and appropriate external lubrication and calcium powder are added to further clean the machine. When it is considered that the extrudate is clean, it can be officially put into production.

Non resin cleaning method

This method uses rice, corn, sawdust, toilet paper and other substances with certain friction and easy to crush. When the extruder is heated to the normal extrusion temperature, the friction between these substances and the screw and screw barrel is used to remove the PVC resin glue attached to the surface of the screw and screw barrel. Experience shows that the shell of rice has high hardness and great friction. In contrast, the effect of cleaning machine is ideal. After cleaning with this method, it is necessary to open the screw barrel to check the cleaning condition. Under normal circumstances, it is also necessary to clean the machine with PVC resin cleaning material formula according to the above method before the production of formal products.

After the extruder is heated to the working temperature, the screw is pushed out manually or automatically to remove the easily removed materials while it is hot. After cooling, soak it in an organic solvent tank containing acetone or cyclohexanone. When the molten attachment attached to the screw swells, remove the attachment manually. The soaking time of the screw depends on the amount of attachment and the thickness of gelation. In order to use less solvent and facilitate the sealing of the container, use a steel pipe or stainless steel pipe slightly thicker than the screw diameter, and weld one end for sealing as a soaking tank. In terms of safety, the container for soaking the screw must be stored in a cool place away from the fire source and power supply. At the same time, the mouth shall be sealed to prevent solvent volatilization, and safety signs shall be attached.

If it is necessary to clean the machine thoroughly, the screw barrel can also be opened while hot, and the gelatinization attached to the inner wall of the screw barrel can be removed by manual method or solvent wiping method.

In order not to damage the surface finish of the screw and screw barrel, it is not allowed to knock with excellent things, but only remove the attachments with steel saw blades or copper brushes that are softer than the steel of the screw and screw barrel, so as not to damage the screw and screw barrel. Because the PVC ingredient in the extruder is in a long time in the extruder, plasticized gel leads to failure to start the extruder. The standard of resin dosage is to ensure that all the powder coating materials retained in the screw barrel can be pushed out of the screw barrel. In terms of the removal degree of extruded materials, it is basically based on the standard that the color of the original PVC products can not be seen or there is no paste.

When the extruder is started up for production, the materials retained in the extruder shall be pushed out with premixed materials according to strict procedures. The re extruded materials can be used as formal products only after they are confirmed to be clean.

If the extruder suddenly fails during normal operation, if the material inside the extruder can not be discharged in time, the PVC powder gel will be injected into the viscous flow state, resulting in failure to start. It is necessary to use electric heating or gas gun to heat the material of the extruder's spiral case at high temperature, which will easily damage the equipment. Therefore, immediately turn off the main machine switch of the extruder after power failure, manually rotate the extruder motor with a belt or a shaking rod, and try to discharge the materials inside the extruder to minimize the residue in the screw barrel.

If the main motor of some extruders is directly connected to the gearbox and there is no device for shaking the rod to rotate the motor, the cooling water of the cooling system can also be increased to quickly cool the temperature of the extruder screw barrel and screw, so as to prevent the plasticization and viscous aging of materials in the extruder.