The size tolerance of seamless pipe is mainly the diameter tolerance and wall thickness tolerance.
Geometric dimension accuracy and outer diameter requirements of seamless steel pipes
1. Steel pipe outer diameter accuracy
The accuracy of the outer diameter of seamless steel pipes depends on the method of determining (reducing) the diameter (including tension reducing), the operation of the equipment, and the process system. And the accuracy of the outer diameter is also related to the processing accuracy of the hole shape of the sizing (reducing) machine and the distribution and adjustment of the deformation of each frame. The precision of the outer diameter of the cold-rolled (抜) formed seamless steel pipe is related to the precision of the die or rolling pass.
2 wall thickness
The wall thickness accuracy of the seamless steel pipe is related to the heating quality of the tube blank, the process design parameters and adjustment parameters of each deformation process, the tool quality and its lubrication quality. The uneven wall thickness of the steel pipe is distributed as the uneven wall thickness in the transverse direction and the uneven wall thickness in the longitudinal direction.
Causes and solutions for seamless pipe size out of tolerance
1. The diameter is out of tolerance
The main reason for the out-of-tolerance diameter is improper mold matching or ignoring the change in the size of the extubation mold due to wear. Excessive reduction of the straightening roller during the straightening process will also cause the diameter of the steel pipe to become smaller.
2. The wall thickness is out of tolerance
The main cause of excessive wall thickness is improper mold matching, or neglect of changes in mold size due to wear. The estimation of the wall thickness change in the empty drawing pass after the fixed wall is incorrect, and the position of the mandrel is improperly adjusted when the arc-shaped outer mold and the tapered rod are used for short-shaped rod drawing--before or after. In order to prevent the wall thickness from being out of tolerance, the mold should be correctly matched and the position of the mandrel should be adjusted correctly. The wall thickness change of the steel pipe in the empty drawing pass should be accurately estimated.
Geometric dimension accuracy and outer diameter requirements of seamless steel pipes
1. Steel pipe outer diameter accuracy
The accuracy of the outer diameter of seamless steel pipes depends on the method of determining (reducing) the diameter (including tension reducing), the operation of the equipment, and the process system. And the accuracy of the outer diameter is also related to the processing accuracy of the hole shape of the sizing (reducing) machine and the distribution and adjustment of the deformation of each frame. The precision of the outer diameter of the cold-rolled (抜) formed seamless steel pipe is related to the precision of the die or rolling pass.
2 wall thickness
The wall thickness accuracy of the seamless steel pipe is related to the heating quality of the tube blank, the process design parameters and adjustment parameters of each deformation process, the tool quality and its lubrication quality. The uneven wall thickness of the steel pipe is distributed as the uneven wall thickness in the transverse direction and the uneven wall thickness in the longitudinal direction.
Causes and solutions for seamless pipe size out of tolerance
1. The diameter is out of tolerance
The main reason for the out-of-tolerance diameter is improper mold matching or ignoring the change in the size of the extubation mold due to wear. Excessive reduction of the straightening roller during the straightening process will also cause the diameter of the steel pipe to become smaller.
2. The wall thickness is out of tolerance
The main cause of excessive wall thickness is improper mold matching, or neglect of changes in mold size due to wear. The estimation of the wall thickness change in the empty drawing pass after the fixed wall is incorrect, and the position of the mandrel is improperly adjusted when the arc-shaped outer mold and the tapered rod are used for short-shaped rod drawing--before or after. In order to prevent the wall thickness from being out of tolerance, the mold should be correctly matched and the position of the mandrel should be adjusted correctly. The wall thickness change of the steel pipe in the empty drawing pass should be accurately estimated.
