Forming adjustment is the basis for used roll forming machines to adjust welded pipes; it is recognized by the industry that welded pipe adjustment is an art, among which, forming adjustment is the pearl in the art palace. Some people can't find the essentials in their entire life. It is not an exaggeration to describe the adjustment of welded pipes as full of mystery and impermanence. This art is concentrated in that the adjustment process and results vary from person to person, unit to crew, material to material, and even to environment. Nonetheless, there are some common basic principles, basic operation methods and basic requirements for molding adjustment.

Basic principles of molding adjustment

Horizontal and vertical principle: This is the first principle of forming adjustment. Hengping has three requirements:

(1) The upper and lower flat roller shafts should be level with the horizontal plane, and one end should not be higher than the other;

(2) Make sure that the two axes are parallel and cannot be inclined;

(3) Not only should it be parallel when it is not loaded, but it should be parallel when there is a load.

Vertical mainly requires vertical rollers to be vertical to the working table of the welded pipe unit, including 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.

According to the principle of calibrating rolls on the rolling line, there are two connotations:

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

(2) The symmetry of the forming bottom roll and the vertical roll must be checked according to the rolling center line. Many problems and defects in the production of welded pipes are closely related to the misalignment of the bottom roll and the deviation of the vertical roll from the rolling center line.

(3) The principle of clear division of labor for vertical and horizontal rollers. The forming flat roll is responsible for power transmission and the main lateral deformation tasks; the vertical roll is mainly responsible for controlling the springback of the tube blank after it leaves the flat roll pass, and is responsible for guiding the forming tube blank into the next flat roll pass smoothly. From the perspective of the development trend of forming theory, the forming function of the forming vertical roll should be gradually weakened, and the control function and import function of the forming vertical roll to the edge of the forming tube blank should be further strengthened by improving the design of the forming vertical roll pass.

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

(4) Equipment accuracy guarantee. This is the basic premise to ensure the smooth progress of the molding adjustment and the lasting results of the molding adjustment. It can be said with certainty that it is impossible to produce high-quality and high-precision welded pipes with a "shaking and swinging tail" welded pipe unit.

(5) The principle of timely curing of adjustment results. It means that after the forming adjustment action is completed and the trial operation is normal, the adjusted part should be tightened accordingly to prevent the thread from loosening again and the position changing again, which will lead to the failure of all previous efforts.

(6) The principle of invalid reset. Forming adjustment in welded pipe production involves pass design, tube blank performance, geometric dimensions, equipment accuracy, as well as commissioners' operating habits, experience status, and human-machine mutual recognition. There are still many aspects that belong to the category of silent technology, which is comprehensible and inexpressible, and still cannot be quantitatively manipulated and "normalized", which is a typical operation with more experience than theory. Therefore, the trial and error method is the most commonly used debugging method in the adjustment and forming process of the used roll forming machine. When an adjustment measure is implemented, if the expected result is not obtained, or the opposite result is obtained, it means that the measure is not correct, and the forming state must be restored to the original state in time. Otherwise, the small problem will be turned into a big problem, and the more it is adjusted, the more chaotic it will be, causing corresponding confusion in the normal position.

(7) The principle of the lesser of two evils. Welded pipe adjustment should strive for excellence as much as possible, but when there is a dilemma, it is necessary to weigh the pros and cons and seek the best from the bad.

(8) Systematic principles. It means that when adjusting the forming, it is necessary to consider the possible influence on the welding part and the sizing part; or conversely, consider the influence of the welding section and the sizing section on the forming. For example, excessive consumption of forming allowance will inevitably lead to small sizing allowance under the premise of constant welding allowance, which will increase the difficulty of sizing adjustment.

In summary, adjusting the welded pipe forming of the used roll forming machines is a complex system engineering. Only by following these basic adjustment principles can we avoid detours and debug qualified pipe products. These basic principles are not only suitable for forming adjustment, but also have a guiding role for welding adjustment and sizing adjustment.