Advantages of headless welding of lsaw steel pipe headless welding and rolling has the characteristics of increasing production, improving finished product rate and rolling mill operation rate, reducing cost, facilitating production management and adaptability.
Under normal circumstances, the straightening of the straight seam welded pipe is mostly straightened one time to achieve the required straightening accuracy. The literature has proposed the use of 2 straight seam welded pipe straightening to improve the straightening accuracy (that is, using ordinary straightening machine for 2 straightening, can achieve high straightening accuracy), the author through the vertical seven-roll straightener, One straightening and two straightening tests on the straight seam welded pipe on the six-roll full-drive straightening machine, which proved that the selection of excellent models, good roll profile, reasonable straightening scheme and improved straightening On the basis of accuracy, the linear accuracy of the straightening of the pipe can be made up to not more than 0.1 mm/m by two straightening process schemes.
This is a simple and straightforward straightening process, which can reduce costs, improve efficiency and be practical for straighteners that are not frequently used. However, this method is not suitable for precision straightening machines used in high frequency or in-line precision straightening processes.
The straightening roll profile is an important factor affecting the straightening accuracy and straightening quality. However, there is a certain degree of disagreement among different researchers in the roll design of straight welded pipe. The literature believes that the traditional hyperbolic roll type is not desirable as a precision straightening machine roll type. This is because the hyperbolic roll type and the pipe contact line are too short, and the roll bottom does not touch and the two sides are in contact with each other during the straightening process. .
In addition, in the process of flattening and straightening, the lsaw steel pipe produces three-point bending on the hyperbolic roll type, so that the pipe is bent, which does not meet the requirements of high-precision straightening, that is, the reasonable roll type should be increased as much as possible. The length of contact between the surface of the straightening roller and the pipe.
However, the literature believes that it is impossible to make the pipe and the straightening roller have a long contact line. He proposed to adopt the principle of “rolling effect”, design the roller shape with a small inclination angle, and increase the inclination angle to reduce the contact line. The length, the reduction of the rolling force, the improvement of the surface of the straightening rolls, and the reduction of the negative action of the straightening rolls are completely different from the conventional ones and are exactly the opposite of what is described in the literature.