The existing cold drawing methods of DIN 17172 STE415.7 seamless steel pipe mainly include long mandrel drawing method, short mandrel drawing method, air drawing method and core expanding method.
1, Pull out the long mandrel.
Long mandrel drawing is to put the pipe material on the long mandrel and pull the pipe together with the long mandrel, so that the DIN 17172 STE415.7 seamless steel pipe can be reduced and the wall thickness compressed in the annular pass composed of mandrel and die hole.
2, Short top drawing method.
Short top pipe drawing is to pull out DIN 17172 STE415.7 seamless steel pipe from the pipe drawing die, and obtain reducing diameter and reducing wall through the annular pass formed by die hole and fixed plug.
3, No top drawing.
That is, hollow compression is carried out on the pipe through the drawing die to reduce the diameter of the pipe and increase the wall thickness. The increase varies with the size of DIN 17172 STE415.7 seamless steel pipe, which is generally 1% of the compression of the pipe diameter. However, when the inner diameter of the pipe is less than the secondary wall thickness, the wall thickness will be reduced.
