METHOD FOR DIRECT OR REVERSE PRESSING OF METAL PIPES, MANDREL FOR PRESSING OF METAL PIPES, PRESS FOR EXTRUSION OF METAL PIPES AND EXTRUDED METAL PIPE Russian patent published in 2017 - IPC B21C23/08 B21C23/21 B21C23/20 B21C25/08 

FIELD: metallurgy.

SUBSTANCE: method involves the use of the mandrel having a transition region (66), between said two pressing surfaces (63, 64) on which a support surface (62) is made, wherein when the mandrel (6) is moved relative to a press matrix (2) from its first pressing position to its second pressing position for said blank, the support is provided along the axis of the press matrix (2) by means of said support surface (62). The mandrel (6) contains two pressing surfaces (63, 64) which have different radii oriented at the same angle relative to the axis of the mandrel, and the radius of the support surface (62) is oriented at the same angle with respect to mandrel axis (68) and has value exceeding 5% of difference of said radii of two pressing surfaces (63, 64), but smaller than the larger one of the two said radii or the radius of the additional support surface (62) oriented at the same angle with respect to mandrel axis (68).

EFFECT: production of extruded metal pipes in which the negative effect of redrawing is minimised.

22 cl, 5 dwg