The industrial production of large straight seam pipes (LSAW steel pipe
) can be divided into the following types according to different steel pipe forming methods.
1. UOE process
The so-called "UOE" process is that the steel plate is first U-shaped, then O-shaped and mechanically expanded. It uses three hydraulic forming to obtain an open tube body, and then sends it to the welding process.
The steel plate is first trimmed and chamfered on both sides in the longitudinal direction, positioned and welded on the four side fillet welding, and then sent to the edge press to gradually pre-press both sides into an arc in the longitudinal direction, and then transported to the hydraulic press The flat steel plate is pressed into a U shape, and then transported to the O forming hydraulic press, where the upper and lower semi-circular pressure molds are pressed into an open tube body. The pressing procedure is carried out in precise hydraulic control, so that the open pipe body has a consistent tolerance accuracy.
UOE unit has the largest production capacity and good product quality. It is currently the world's most important LSAW pipe unit for producing high-precision line pipes.
2. RBE (three-roller bending) process
The edge of the plate is also first trimmed and chamfered along the longitudinal direction on both sides, and then the flat steel plate is repeatedly rolled into a circular open tube on the three-roller bending machine. The tube enters the edge rolling machine, and both sides are repeatedly Rolling makes the arc match the pipe diameter. This forming method limits the thickness of the formed tube and the possibility of producing small diameter and thick-walled tubes.
3. JCOE (compression molding) process
The prepared steel plate is transported to the molding press, and the steel plate is moved to the molding station by the manipulator, and is pressed into a tube body by a curved mold indenter through a series of steps.
The hydraulic press is operated by two manipulators, first press one side to form a semicircle, that is, a "J" shape, and then the second manipulator transposes the steel plate to perform bending forming on the other half. The thickness of the die affects the roundness of the open tube, and the thickness is best kept to a minimum. The edge rolling is similar to the three-roll process.
4. C (pressure forming) process
The C pressure forming process was first adopted by the French company Pont-A-Mousson S.A. It is also an effective method for producing large longitudinally welded pipes, especially thick-walled steel pipes.
Forming relies on high control accuracy and high pressure. After the steel plate is pre-curved by the roller bending machine, it is sent to the C press forming machine. Similarly, two operators formed half of the steel plate on the first C press, and then formed the other half on the other press. That is, it is first pressed into a "C' shape, and then pressed into an "O" shape to form an open circular tube body. Both the tool and the pressing plate have hydraulic cushions and stably suppress small arcs, while ensuring neatness over the entire length .
5. CFE (roller forming) process
Roll forming can be divided into full roll forming and half roll forming. The so-called half-row roller molding is to replace the idle rollers between the transmission roller racks (ie, flat roller racks) in general roller molding machines with rows of small rollers to improve the molding conditions. The position of the small roller can be adjusted, and it is suitable for a certain range of steel pipe sizes without replacement. For full-row roll forming, in addition to leaving the first transmission roll frame in a general roll machine, all other frames are replaced by small rows and small rolls, especially the outer small rolls, which can be applied to all The steel pipe does not need to be replaced, so this method is beneficial to increase productivity.