The basic reasons for defects in cold drawn seamless tube are:
1. The quality of the pipe material or the intermediate pipe is not good, including the geometric size does not meet the requirements, the longitudinal and transverse wall thickness is seriously uneven, the curvature and ellipse are too large, the chemical composition is inconsistent, and the mechanical properties are inconsistent or uneven.
2. Failure to comply with the operating procedures for each preparation process before drawing. The main ones are incorrect hammer head technology, improper chemical treatment and heat treatment, burrs on the pipe end, low grinding quality, defects during transportation, etc.;
3. Failure to follow the operating procedures of the extubation process. It is manifested in the inconsistency between the center line of the pipe and the drawing line, improper installation of the drawing die, too fast drawing speed, improper selection of tools, too large or too small diameter of the mandrel rod, too much deformation, and untimely feeding of the mandrel, etc. ;
4. The quality of the extubation mold and mandrel is the worst, including poor finish, low hardness and strength, inconsistent size, incorrect inlaying of the cemented carbide mold, etc.;
5. The extubation machine is in disrepair. For example, the extubation trolley is tilted, the mold base or the extubation mold itself is not installed correctly on the center frame, etc.
1. The quality of the pipe material or the intermediate pipe is not good, including the geometric size does not meet the requirements, the longitudinal and transverse wall thickness is seriously uneven, the curvature and ellipse are too large, the chemical composition is inconsistent, and the mechanical properties are inconsistent or uneven.
2. Failure to comply with the operating procedures for each preparation process before drawing. The main ones are incorrect hammer head technology, improper chemical treatment and heat treatment, burrs on the pipe end, low grinding quality, defects during transportation, etc.;
3. Failure to follow the operating procedures of the extubation process. It is manifested in the inconsistency between the center line of the pipe and the drawing line, improper installation of the drawing die, too fast drawing speed, improper selection of tools, too large or too small diameter of the mandrel rod, too much deformation, and untimely feeding of the mandrel, etc. ;
4. The quality of the extubation mold and mandrel is the worst, including poor finish, low hardness and strength, inconsistent size, incorrect inlaying of the cemented carbide mold, etc.;
5. The extubation machine is in disrepair. For example, the extubation trolley is tilted, the mold base or the extubation mold itself is not installed correctly on the center frame, etc.
