PQF mill, the world’s most advanced continuous steel pipe rolling equipment
PQF mill is the latest and advanced steel pipe rolling mill to improve product quality, reduce cost and improve economic benefits.
From the perspective of technology, PQF mill has the following advantages compared with MPM mill.
(1) Closed-type pass design makes rolling more stable
The roll frame of the PQF continuous pipe rolling machine adopts the three-roll closed-type pass design, as shown in FIG. 1.
In the rolling process, the metal deformation is stressed in three directions at the same time, so that the metal deformation is more uniform in the same section. The three rollers are arranged in 120 degree angles, and the front and rear stand rollers are arranged in 60 degree angles each other, to ensure the mandrel in the groove better alignment, so as to make the rolling process more smooth and stable.
(2) Unique mandrel circulation system and fewer holes in the spare mandrel
After the end of rolling, the mandrel stops. After the tube is extracted from the mandrel by the tube stripper, the mandrel is not sent back, but runs forward. After the tube stripper is put through, the mandrel is pulled out and then sent back, cooled and lubricated.
It retain the original advantage of MPM process, that is high precision characteristics of wall thickness. On the premise of better wall thickness precision than MPM, It reduces the mandrel line to be rolled (non-rolling) time, thus effectively shortens the rolling cycle, speeds up the rolling rhythm, and the fastest speed can reach 24s per piece.
The three-roll geometry can be adjusted to a larger range under the same mandrel without large tolerance effect.
As a result, the range of the wall thickness that can be rolled on the mandrel of one specification is increased, which greatly reduces the number of mandrel specifications (by 50%) and the frequency of tool replacement, and the production organization is also more flexible.
(3) It can improve the quality of steel tube and wall thickness precision, rolling thinner wall thickness steel tube.
Because of the small difference of linear velocity between the bottom and the edge of the roll pass of PQF continuous rolling pipe mil, the pass with smaller opening can be adopted, therefore, the metal deformation of the rolled piece is more uniform when the pipe is rolled by PQF continuous rolling pipe mill, and the transverse flow of the metal is less, which is better than that of the steel tube rolled by the two-roll MPM continuous rolling pipe mill in the following four aspects:
- wall thickness tolerance significantly improved;
- the surface of the pipe is much smoother;
- the D/S value of finished pipe can be increased without affecting the quality;
- mandrel continuous rolling pipe technology enters the field of small diameter steel pipe production;
Using the three-roll closed-type pass design, metal deformation on the same cross section is uniform, three roll can be simultaneously or separately adjusted under single drive and separate servo hydraulic pressure, realizing the roll gap adjustment model, so as to improve the wall thickness accuracy and reduce the wall thickness difference between end and the central part of the waste pipe.
The 120 degree angle arrangement of the three rollers ensures a better alignment of the mandrel in the pass, which results in a significant improvement in the tolerance of the wall thickness of the wasted tube after rolling.
Three roll sealing groove design, reducing the rolling roll bending moment, can achieve uniformity and stability of metal deformation, and rolling pressure, especially peak pressure decreases. Cracks and concave defects caused by uneven deformation in the process of rolling, has been basically eliminated, that means it can make rolling thin wall pipe and high grade varieties, such as rolling of 159 mm x4.0 mm, 463.0 mm x4mm thin wall steel tube, etc.