Aluminijske zavojnice are cleaned, chemically converted, and painted to form coatings of various colors and properties on the coils. The aluminum coil is coated by advanced roller coating process, and baked by infrared or hot air circulating baking process. According to the major process points, the process flow is: uncoiling – pre-treatment – roller coating – post-treatment – winding.
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(1) Unwind. The uncoiling of the aluminum coil roll coating production line is realized by the uncoiler. The uncoiler of the coating unit is a cantilever type, which is used to tension and support the coil, open the coil or roll the coil into a coil by rotating operation, and establish the tension and alignment of the coil during the operation of the machine train. middle.
After the aluminum coil is uncoiled, it is passed to the pinch roller through the feeding plate, and is fed from the pinch roller to the cutting head. , thick tape for suture). After the seam has to be flattened by flattening rollers, the strip is fed into the pretreatment section.
The coating machine train usually has two looper towers. Since the production of the coating process section must be carried out continuously, and the inlet and outlet have pauses when winding up and down, the strip operation is carried out by the inlet and outlet looper towers at this time. adjust.
In order to ensure the normal and stable operation of the production line, the tension of the uncoiler must be adjusted according to the different width and thickness of the coil to make the coil tension.
(2) Suture. Coil stitching is mainly to stitch the head and tail of the front and rear strips in the direction of the vertical strip by the mechanical stamping method, so as to make the production continuous. The methods of stitching aluminum coils are generally divided into: welding, bonding, and mechanical stitching. The common suture method is mechanical suture. Stitching must be done quickly to keep the process section functioning properly. If the sewing time is too long, the material stored in the looper tower will be emptied, which will cause the production line to stop. and other defects.
For thin coils with a thickness of ≤ 0.4mm, spacers should be added during sewing to prevent the thin coils from being unable to withstand the sewing pressure and fracturing the coils. Under normal circumstances, the gasket is added to the outer side of the seam by a thin coil with a thickness of ≤ 0.4mm. The shim width should match the width of the production roll. The head of the latter strip should be placed above the tail of the former coil to avoid the head of the latter strip hitting the road and rollers. When stitching, the tape and dirt adhered to the head and tail of the material should be removed to avoid foreign matter being brought into the road to damage the roller and cause defects such as wear marks and scratches.
The stitched web is introduced into the coating line by means of traction belts to be coated. Its length must be greater than the length of the entire production line in order to pass through the production line. The traction belt cannot have obvious defects such as creases, skirts, cracks, waves, itd., to prevent scratches or broken belts on the production line, resulting in missed coating during parking.
(3) Selection of train running speed. The running speed of the machine train is determined according to the different specifications and coating varieties of the aluminum coil. The selection of train running speed should follow the following basic principles:
1) Depends on the thickness of the substrate. Thin materials with a thickness of less than 0.2mm are prone to breakage and should be produced at low speed; aluminum coils with a thickness of more than 1.0mm are prone to breakage, and the production time is relatively short. When the production line stops, it is advisable to use low-speed production.
2) Depends on the length of the oven. When the furnace temperature is constant, the longer the length of the baking furnace, the faster the production speed; otherwise, the slower it is.
3) Depends on the type of paint. Polyester and epoxy resin have good fluidity in the coating pan, and the surface is not easy to produce defects such as orange peel, stripes, bright stripes, itd., and a faster production speed can be selected. The fluidity of fluorocarbon coatings in the coating pan is relatively poor, and the surface is prone to defects such as orange peel, streaks, bright stripes, itd., and a slower production speed should be used.
4) Depends on the width of the substrate. Under normal circumstances, when the width of the coil is greater than 90% of the width of the coating roller, it is easy to leak coating on both sides of the coil, and a slower production speed should be used; if the width of the strip is less than 90% of the width of the coating roller, a faster coating can be used. Production speed.
5) Coils of the same color, similar thickness, and different widths can use the same machine speed.