At present, the most common pipe-cutting method for
spiral steel pipe manufacturers is plasma cutting, which will generate a large amount of metal vapor, ozone, and nitrogen oxide smoke during cutting, which will seriously pollute the surrounding environment. The key to solving the smoke problem is how to suck all the plasma smoke into the dust removal equipment, to prevent air pollution. For plasma cutting of spiral steel pipe, the difficulty of dust removal is:
1. The cold air around the suction inlet enters the suction inlet from the outside of the machining gap and the air volume is very large, so that the total amount of smoke and cold air in the steel pipe is greater than the effective air volume sucked by the dust collector, so it becomes impossible to completely absorb cutting smoke and dust.
2. The nozzle of the plasma gun blows out the air in two opposite directions at the same time during cutting, so that the smoke and dust emerge from both ends of the steel pipe, and it is difficult to recover the smoke and dust well from the suction port installed in one direction of the steel pipe.
3. Since the cutting part is far away from the dust removal inlet, it is difficult for the wind to reach the suction inlet to pump the smoke and dust.
For this reason, the design principles of the dust extraction hood are:
1. The air volume inhaled by the dust collector should be greater than the total amount of smoke and dust generated by plasma cutting and the air inside the pipe. It should form a certain amount of negative pressure chamber inside the steel pipe, and try not to let a large amount of outside air enter the steel pipe, to effectively Suction the fumes into the dust collector.
2. Block the smoke and dust at the position after the cutting point of the steel pipe. Try to prevent cold air from entering the inside of the steel pipe at the suction port, and form a negative pressure chamber in the inner space of the steel pipe so that the smoke and dust will not come out. The key is to design the facilities to block the smoke and dust. The production is reliable, does not affect normal production, and is convenient to use.
3. The shape and installation position of the suction port. The effect must be achieved by allowing the suction port to suck more smoke and dust inside the steel pipe into the pipe. Add a baffle at the position behind the cutting point of the plasma gun to keep the smoke and dust inside the steel pipe. After a period of buffering, it can be completely sucked away.
specific measure:
Install the smoke and dust baffle on the accompanying trolley inside the steel pipe and place it at about 500mm from the cutting point of the plasma gun, and stop for a while after the steel pipe is cut to absorb all the smoke and dust. Note that the smoke baffle must be accurately positioned at the position after cutting. In addition, to make the accompanying trolley supporting the dust baffle and the rotation of the steel pipe coincide with each other, the running wheel angle of the accompanying trolley must be consistent with the angle of the inner roller.
For plasma cutting of large-diameter spiral welded pipes with a diameter of about 800mm, this method can be used; for diameters, less than 800mm, smoke and dust with small pipe diameters cannot emerge from the direction of the pipe, and internal baffles do not need to be installed. However, at the fume suction of the former, there must be an external baffle to keep out the cold air.
