Cold drawn seamless steel tube production method?

1. without mandrel drawing (only when drawing pipe die don't have to pull mandrel);
2. the short mandrel drawing (when drawing with the length of the pipe die and axial fixed pull small short mandrel);
3. long mandrel drawing (used when drawing pipe die and pull with the steel tube pull move slightly larger than the length of the tube length long mandrel);
4.winding mandrel drawing (used when drawing pipe die and not to pull the axial fixed and can self steady short mandrel in deformation zone). During the first two application on yield and especially throughout; Without mandrel drawing is used to reduce the outer diameter of steel pipe; The other three with mandrel drawing first used for tightening steel pipe wall thickness, also must be reducing deformation together.