Headbox (front box) installation is important for aluminum liquid level control accuracy, it is one of the key factors affecting the quality of ultra-thin fast aluminum plate casting and rolling mill products.
When installing and adjusting the casting nozzle and the front box, the action should be rapid, and it should not exceed 3h from the lifting of the tool heating furnace to the vertical plate. The machine must be shut down during the adjustment and installation of the front box.
Pad 2cm thick aluminum silicate fiber between the headbox and the casting tips nozzle, and then tighten it with bolts. After headbox installation, it should be heated, and the temperature should be above 200℃.
The aluminum liquid enters the gas refining device through the launder, continues to remove the hydrogen, and then enters the front box through the next launder, and then enters the casting and rolling mill through the nozzle to produce aluminum plates, which are coiled by the coiler to form cast coils. The technological process has strict requirements on the liquid level.
The headbox liquid level control has the following characteristics:
- There is a lagging link. The controlled object is a long and narrow launder. The outlet and the inlet are respectively at the two ends of the launder. The control requirement is that the liquid level at the outlet is stable, so a large lag will be introduced to the system.
- The flow trough volume brings greater inertia.
- There are many disturbances in the system, such as unstable liquid level in the upper tank, uneven casting speed, turbulent flow in the water tank, and irregular flow in the outlet channel.
- The thickness of the aluminum plate is thin and the production speed is fast, so the requirements for the accuracy of liquid level control are very high.
The problem of rising liquid level in the front tank of the melting and casting workshop has been around for a long time. Due to the rise of the liquid level, the vertical plate of the continuous caster broke soon after. For this reason, the production output of the continuous casting machine has been on the low side and cannot reach the rated capacity of the production line.
Front box liquid level control: The front box liquid level control adopts a floating type. When the liquid level is high, the float floats up, the blockage increases the pouring, and the ceramic tube flow decreases. When the liquid level is low, the float floats down, the blockage reduces the pouring, and the pipe flow increases.