Spiral steel pipe (SSAW steel pipe) is a welded pipe made by rolling low-carbon carbon structural steel or low-alloy structural steel strip into a tube blank at a certain helical angle (called forming angle), and then welding the pipe seams. Different spiral welded pipes should have different cutting methods, and the cutting methods of thick-walled spiral welded pipes are as follows:
(1) Cutting method
The shearing machine has high productivity and no metal consumption during shearing. However, due to the flattening phenomenon at the fracture, it is easy to cut obliquely, and at the same time, the shearing machine is also easy to cut when cutting high-alloy steel. Therefore, the shearing machine is generally only used on small units with a large number of shears and products made of low alloy steel and carbon steel.
(2) Sawing method
The end surface of the rust-cut tube blank of the sawing machine is straight, which is convenient for centering and easy to operate when piercing. The wall thickness of the hollow blank (capillary tube) is relatively uniform. At the same time, the tube blanks of various steel grades can be sawed by the cold rust machine. But its disadvantage is that the productivity is low and the loss of the saw blade is large.
(3) breaking method
The productivity of the breaking machine is high, but the section of the tube blank after breaking is extremely uneven, which may easily cause uneven wall thickness when piercing. At the same time, for low carbon steel and alloy steel, it is also difficult to break. Therefore, the breaking machine is generally used on the old units, and the new units are generally not used.
(4) flame cutting method
The section of the flame-cut spiral welded pipe billet is flat, the slit is about 6-7mm, and the investment cost is relatively low. At the same time, the production of flame cutting machine is flexible. It can cut both round and square billets, and it can cut the tube blanks of most steel grades of spiral welded pipes. Its disadvantage is that the general flame cutting method is not suitable for carbon steel and some alloy steels with a carbon content of more than 0.45%. At the same time, there will be problems such as metal consumption, oxygen and gas consumption, and workshop pollution.
(1) Cutting method
The shearing machine has high productivity and no metal consumption during shearing. However, due to the flattening phenomenon at the fracture, it is easy to cut obliquely, and at the same time, the shearing machine is also easy to cut when cutting high-alloy steel. Therefore, the shearing machine is generally only used on small units with a large number of shears and products made of low alloy steel and carbon steel.
(2) Sawing method
The end surface of the rust-cut tube blank of the sawing machine is straight, which is convenient for centering and easy to operate when piercing. The wall thickness of the hollow blank (capillary tube) is relatively uniform. At the same time, the tube blanks of various steel grades can be sawed by the cold rust machine. But its disadvantage is that the productivity is low and the loss of the saw blade is large.
(3) breaking method
The productivity of the breaking machine is high, but the section of the tube blank after breaking is extremely uneven, which may easily cause uneven wall thickness when piercing. At the same time, for low carbon steel and alloy steel, it is also difficult to break. Therefore, the breaking machine is generally used on the old units, and the new units are generally not used.
(4) flame cutting method
The section of the flame-cut spiral welded pipe billet is flat, the slit is about 6-7mm, and the investment cost is relatively low. At the same time, the production of flame cutting machine is flexible. It can cut both round and square billets, and it can cut the tube blanks of most steel grades of spiral welded pipes. Its disadvantage is that the general flame cutting method is not suitable for carbon steel and some alloy steels with a carbon content of more than 0.45%. At the same time, there will be problems such as metal consumption, oxygen and gas consumption, and workshop pollution.
