How to clean extruder screw? How to deal with sudden power failure?
How to clean extruder screw? How to deal with sudden power failure?
For manufacturing thermosetting powder coatings with extruder, the replacement of coating resin varieties or color varieties, must be clear machine, to prevent interference between varieties of powder coatings, guarantee the quality of products. When extruder machine is not complete, the most obvious effect is the color of powder coating, which can be directly observed. In addition, the previous production without flow ping agent type powder coating of fine arts, reproduction without clear clean extruder highlights powder coating, because the material in front of the interference, behind the product to produce coating is easy to produce the ills such as shrinkage cavity. Therefore, it is very important to clean the machine when changing the variety of paint resin and variety. There are many methods of cleaning machine, which can be used as follows:
Resin cleaning process
This method is made of resin, such as polyester resin or epoxy resin. This method usually used in cleaning machine of new equipment or extruder use after a period of time, because some material remaining on the screw or the spiral tube gel, material extrusion speed slow, and varieties of color change color color difference is bigger, can use this method. After the resin-cleaning machine, the machine can be further cleaned with resin, no curing agent or curing resin. When it is thought that the extruder is clean, it can be formally put into production. If the change of powder coating variety of color difference is small, the thorough cleaning machine time is not too long, use only to be able to produce the powder coating to use the resin cleaning machine. In order to increase the friction of the resin, the machine can be used to clean the machine.
Non - resin cleaner method
This method is to use a certain friction, and easily crushed rice, corn, saws, such as toilet paper, at the end of the heat when extruder to normal after the extrusion temperature, the use of these substances and the friction between the screw and screw tubes remove adhesion on the surface of the screw and screw tubes, rubber compound powder coatings. Experience shows that rice husk has a high hardness and high friction, which is ideal compared with the cleaner. After cleaning machine in this way, it is necessary to open the screw tubes check cleaning machine, under normal circumstances also need according to the above method is to use a powder coating with the resin again after cleaning machine, to a formal production.
Remove screw and screw manger
This method is to heat the extruder to the working temperature, and then use manual or automatic method to introduce the screw to remove the easily removed materials. After cooling, soak in an organic solvent tank containing acetone or cyclohexanone, and after the melt attached to the screw is dissolved, the attachment is removed manually. The immersion time of the screw is determined by the amount of the attachment and the thickness of the gel. In order to reduce the solvent and the sealing of the container, a steel tube or stainless steel tube with a slightly thicker diameter than a screw rod can be used as a soaking tank. For safety reasons, the container must be kept in a cool place, away from the source and power source, while sealing the mouth to prevent the solvent from volatilization and marking the safety mark.
If you need to clean the machine thoroughly, the screw can also be used to remove the glue that attaches to the inner wall of the screw after it is opened. In order not to damage the screw and screw barrel surface finish, can't use good things, can only use than the screw and the screw tubes steel soft metal saw blade or steel brush, wipe out the attachments, so as not to damage the screw and screw tubes.
Because the extruder of thermosetting powder coating long retention time in extruder, prone to curing reaction and gel, in become a particle of the coating in the coating powder coating, if there is a cure even extruding machine cannot be started. So before extrusion machine downtime, must use no curing performance, and is no pure resin, curing agent and curing of the resin powder coating material out of the extruder, to prevent these materials remaining in extruder curing reaction. The standard of resin adding material is to ensure that the powder coating materials retained inside the screw can be fully introduced to prevent the material from solidifying into principle in the extruder. In terms of the removal of the extruded material, the color of the original powder coating is basically the standard.
In extruder on production, according to strict procedure with premixed material retained in the extruder of pure resin, when after confirmation of pure resin its clean, can squeeze another material as a formal product. In order to prevent the pure resin from being brought into the product, the pure resin and some mixture of the pure resin and some mixture can be used when the mixture is premixed. But it can't be brought into the next step.
Extruder in the normal operation of all of a sudden power failure, if not timely the extruder screw tubes inside the material discharge outside, will make some powder coating curing reaction and gel, a long time even serious curing, unable to boot, need electricity heating or gas torch tools such as high temperature heating processing of the material of extruder screw tubes, so easy to damage the equipment. , therefore, should immediately turn off after blackout extruder host switch, plate belt by hand or with great artificial rotating mechanical extrusion machine, try to dump the material within the extruder, residue, at least in the screw tubes at the same time, add a small amount of pure resin with some residual powder coating material, because at this time can only using residual heat of extruder, so add the amount of pure resin cannot too much.
If some of the extruder main motor connected directly to the gearbox, and no rocking bar motor turning device, also can increase the cooling water of the cooling system, make the temperature of the extruder screw barrel and screw quickly cooled down, to prevent materials react in the extruder.
