METHOD OF MAKING TUBES WITH USE OF STATIONARY MANDREL Russian patent published in 1996 - IPC

FIELD: metal pressure forming. SUBSTANCE: method comprises steps of securing ends of a tube blank in movable clamps; performing deformation upon reverse motion of the blank along an axis in a gap between a stationary die and the stationary mandrel; successively changing the mandrels with increase of their diameter, realizing deformation of the blank with use of the first mandrel along a length L=(0.97-0.99)/ L=(0,97...0.99)•1/μ(A-B), (A-B), where A-a length of a ready tube, mm; B - a total length of portions, having thickened wall, mm; μ - a total elongation value upon deformation on the mandrels, beginning from the second one; after deformation on mandrels had been over, performing plastic extension of the blank until its predetermined length. Such combination of operations provides a possibility of making especially thin wall tubes with thickened wall on its end portions and with strict allowances for the whole length of the tube and also for its thickened wall portions. EFFECT: enhanced quality of thin-wall tubes. 1 cl, 1 dwg