Production process of aluminum plate and strip: flat ingot milling - flat ingot heating - hot roughing (reversible) - hot finishing (irreversible) - cold rolling (trimming, intermediate annealing, etc.) - finishing (cleaning, cross cutting, stretch bending straightening, etc.) - production process of heat treatment; The production process of medium and thick plates: flat ingot heating - hot roughing (reversible) - hot finishing (irreversible) - finishing (sawing, etc.).

1、 Hot rolling process

1. Raw material specifications

Flat ingot specifications: (420-460mm) × (1000-2000mm) × (3600-6800mm).

Alloy grades for flat ingots: 1xxx, 3xxx, 5xxx, 8xxx, etc.

2. Equipment composition

1 flat spindle milling machine

2 sets of vertical push flat ingot heating furnaces

One 2400mm four roll reversible double coil hot rolling production line

3. Process flow and parameters

⑴ Flat ingot milling surface

Flat ingot milling is used to remove surface segregation nodules, slag inclusions, scars, and surface cracks, reduce metal and non-metal indentation defects on the plate, and improve surface quality. A flat ingot with a specification of 480 * 1500 * 6000 (weight 11.66T) is pushed into the milling machine to mill both sides of the flat ingot. The operating speed of the milling machine is 0.2m/s, and the maximum thickness of the flat ingot that needs to be milled off is 6mm. The weight of aluminum chips milled off from one flat ingot is 383Kg, and 32.8Kg of aluminum chips are produced per ton of aluminum in the flat ingot.

⑵ Flat ingot heating

The qualified flat ingots for milling are heated in a vertical push heating furnace at a temperature of 350 ℃ to 550 ℃ for 5-8 hours. The heating furnace has 5 zones, each zone is equipped with a large flow air circulation fan installed on the top of the furnace. The fan operates at a speed of 10-20m/s and consumes 20m3/min of compressed air; There are a total of 20 natural gas burners in 4 zones, installed on both sides of the upper half of the furnace body, with a natural gas consumption of approximately 1200Nm3/h.

⑶ Hot rough rolling

Push the heated flat ingot with a specification of 480 * 1500 * 6000 into a four roll reversible hot rolling mill for hot roughing, with a maximum rolling speed of 230m/s. After 5-13 passes of rolling, the flat ingot is finally rolled into a 20-160mm slab.

⑷ Hot precision rolling: The hot rough rolled slab is subjected to precision rolling operation in the hot precision rolling unit, with a maximum rolling speed of 480m/s. After 10-18 passes of rolling, coils with a thickness of 2.5-16mm are produced.

2、 Cold rolling process

1. Inlet raw material specifications

Roll thickness: 2.5-15mm

Roll width: 880-2000mm

Roll diameter: φ610～φ2000 mm

Roll weight: 12.5t

2. Equipment composition

Two sets of 2000mm non four roll reversible cold rolling mill units

6 sets of 40t intermediate and finished annealing furnaces

Two sets of 20m precision sawing machines for medium and thick plates

Two MK84180 × 8000 CNC roll grinders

3. Process flow and parameters

⑴ Cold rolling

Aluminum hot-rolled coils with a thickness of 2-15mm are rolled through 3-6 passes in a four roll irreversible cold rolling mill to a finished thickness of 0.25-0.7mm. The computer is used to implement comprehensive automatic control of flatness (AFC), thickness (AGC), tension (ATC), etc. for rolling, with a rolling speed of 5-20m/s. During continuous rolling, it can reach 25-40m/s, and the reduction rate is generally between 90% and 95%.

⑵ Intermediate annealing

To eliminate work hardening phenomenon after cold rolling, some intermediate products need to undergo intermediate annealing operation. The annealing temperature during intermediate annealing is 315-500 ℃, and the holding time is 1-3 hours. The intermediate annealing furnace is heated by electricity, and the top of the furnace is equipped with three high wind turbines with a wind speed of 10-20m/s. The total power of the heater is 1080Kw, and the consumption of compressed air is 20Nm3/h.

⑶ Finished product annealing

After cold rolling, the product needs to be annealed at a temperature of 260-490 ℃ for 1-5 hours. The cooling rate of the aluminum foil should be less than 15 ℃/h, and the discharge temperature should not exceed 60 ℃. The discharge temperature of other thicknesses of rolled coils should not exceed 100 ℃.

3、 Finishing process

1. Finished product specificatio

Roll width: 880-1900mm

Roll diameter: φ610～φ1800 mm

Roll weight: 12.5t

2. Equipment composition

2000mm cross cutting unit (2-12mm) 2 sets

2000mm straightening unit (0.1-2.5mm) 2 sets

2000mm cross cutting unit (0.1-2.5mm) 2 sets

2 sets of 2000cm thick plate straightening units

2 sets of 2000mm roll automatic packaging units

Two MK8463 × 6000 CNC roll grinders

3. Process flow and parameters

Cross cutting production line

The aluminum strip cross cutting unit is a device used for accurately cutting aluminum and aluminum alloy coils with a thickness of 2-12mm horizontally, and stacking them neatly according to product requirements. The maximum cutting length can reach 11m.

Straightening production line

Under the tension of 2.0-20 kN applied by the tension roller group, the aluminum coil continuously passes through multiple sets of small diameter bending rollers arranged alternately up and down. Under the combined action of stretching and bending, plastic extension occurs along the length direction, making the length of each longitudinal fiber of the strip tend to be consistent and improving the flatness of the strip. The operating speed of the unit can reach 200m/min.

Thick plate straightening production line

The position of the rollers is at a certain angle to the direction of movement of the straightened product. Two or three larger rollers are the active pressure rollers, which are driven by an electric motor to rotate in the same direction, while several smaller rollers on the other side are the passive pressure rollers, which are rotated by the frictional force of a rotating round rod or pipe. In order to achieve the compression required by the rollers for the products, these small rollers can be adjusted forward or backward at the same time or respectively. After being bitten by the roller, the product continuously undergoes linear or rotational motion, thus subjecting the product to various forms of compression, bending, flattening, and other deformations, ultimately achieving the purpose of straightening. The straightening force of this production line is 30MN.

4、 Deep processing technology

1. Wire drawing processing technology

The main process of the technology is divided into three parts: de esterification, sand mill, and water washing. In the aluminum plate drawing process, the special coating technology after anodizing is generally achieved by using a stainless steel wire brush or scouring pad brush with a diameter of 0.1 millimeters, or by processing with a nylon sand belt. This can create a coating layer containing the metal component on the surface of the aluminum plate, clearly showing every fine wire trace, thus giving the metal matte a fine hair like luster. In recent years, an increasing number of aluminum plate products have adopted metal wire drawing technology for their metal shells, in order to achieve aesthetic and corrosion-resistant effects.

2. Etching treatment process

First, grind with jujube charcoal to remove grease and scratches, and grind to a matte surface. Then use screen printing to print the pattern, with ink models such as 80-39, 80-59, 80-49, etc. After printing the pattern, put it in an electric furnace for drying, then seal the back with instant tape, seal the edges with adhesive tape, and enter the corrosion process. The formula for the corrosion solution of aluminum plate is as follows: 50% ferric chloride, 50% copper sulfate, an appropriate amount of water, and a temperature between 15-20 ° C. When the aluminum plate is corroded, it should be placed flat. During the corrosion process, reddish brown slag overflows from the pattern and should be removed with a brush at any time. A large number of bubbles will appear on the aluminum surface, and the slag will float up with the bubbles. The corrosion time of aluminum plate can be completed in about 15-20 minutes.

3. Electrophoretic coating process

Process flow: degreasing → hot water washing → water washing → neutralization → water washing → anodizing → water washing → electrolytic coloring → hot water washing → water washing → electrophoresis → water washing → drying.

On the basis of anodic oxidation, a water-soluble acrylic paint film is uniformly covered on the oxide film through electrophoresis, forming a composite film of anodic oxide film and acrylic paint film on the surface of the profile.

Aluminum sheet with a solid content of 7% to 9% and a temperature of 20-25 ℃ pH8.0～8.8、 An electrophoresis cell with a resistivity (20 ℃) of 1500-2500 Ω cm, a voltage (DC) of 80-25OV, and a current density of 15-50 A/m2 can be coated with a film thickness of 7-12 μ m after 1-3 minutes of electrophoresis.

Article source: Internet

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