The basic principle of forming adjustment of welded pipe

The basic principle of forming adjustment of welded pipe

1. Horizontal and vertical principles. 

This is the principle of forming adjustment. The requirement of horizontal flatness is that the upper and lower flat roller axes should be flush with the horizontal plane. One end should not be high and the other end should be low. Ensure that the two axes are parallel and cannot be tilted. They must be parallel not only when there is no load, but also when there is a load.

The verticality mainly requires that the vertical roller is perpendicular to the working table of the welded pipe unit, including the horizontal and vertical directions. The horizontal direction is related to the force of the tube blank, and the vertical direction is related to the stable operation of the tube blank.

2. The principle of correcting the roll according to the rolling line:

(1) The height of the forming lower roll and vertical roll needs to be corrected according to the rolling bottom line, so as to ensure that the lower roll pass and vertical roll pass are consistent with the elevation of the rolling bottom line;

(2) The pass symmetry of the forming lower roll and vertical roll needs to be inspected according to the rolling center line standard. Many problems and defects in the production of welded pipes have a lot to do with the misalignment of the lower roll and the deviation of the vertical roll from the rolling center line.

3. The principle of clear division of labor for vertical vertical rollers. 

The forming flat roll is responsible for power transmission and main lateral deformation tasks, and the vertical roll is mainly responsible for controlling the rebound of the tube blank after it exits the flat roll pass, and guiding the formed tube blank to enter the next flat roll pass smoothly. From the perspective of the development trend of the forming theory, the forming function of the forming vertical roll should be gradually weakened. By improving the pass design of the forming vertical roll, the control function and the introduction function of the forming vertical roll to the edge of the forming tube blank should be further strengthened.

In addition, excessive reliance on vertical roll forming will increase rolling resistance, which may lead to unstable operation of the formed tube blank, resulting in frustration, which will lead to a series of subsequent adverse consequences.

4. Equipment precision guarantee, which is the basic premise to ensure the smooth progress of forming adjustment and lasting forming adjustment results. It can be said with certainty that it is impossible to produce high-precision welded pipes with a "shaking head and tail" welded pipe unit.

5. The principle of timely solidification of the adjustment results means that the molding adjustment action is completed, and after the test run is normal, the adjusted parts should be tightened accordingly to prevent the thread from loosening again and the position changing again, resulting in wasted efforts.

6. Invalid reset principle. 

Forming adjustment in welded pipe production involves pass design, tube billet performance, geometric dimensions, equipment accuracy, operating habits and experience status of commissioning workers, and it is still impossible to quantitatively control and "standardize processing" so far. This is a typical operation where experience is more than theory. Therefore, trial and error is a commonly used debugging method in the process of molding adjustment. When implementing an adjustment measure, if the expected result is not obtained, or the opposite result is obtained, it means that the measure is not correct, and the formation state needs to be restored to the original state in time. Otherwise, a small problem will become a big problem, and the more you adjust, the more chaotic it will be, causing the corresponding disorder in the normal position.

7. The principle of choosing the lesser of two evils. In the adjustment of welded pipes, try to be as perfect as possible. However, when there is a dilemma, you must weigh the pros and cons and seek the good from the bad.

8. Systematic principles. 

It refers to the possible influence on the welding part and the sizing part when adjusting the forming, or conversely considers the influence of the welding part and the sizing part on the forming. For example, if the forming allowance is consumed too much, under the premise that the welding allowance remains unchanged, the sizing allowance will be too small, which will increase the difficulty of sizing adjustment.

To sum up, the forming adjustment of welded pipe is a complex system engineering. Only by following these basic adjustment principles can we debug qualified pipeline products. These basic principles are not only applicable to forming adjustment, but also have a guiding effect on welding adjustment and size adjustment .