METHOD FOR MAKING TUBES WITH INNER GROOVES Russian patent published in 2002 - IPC

FIELD: plastic working, namely manufacture of tubes with complex inner profile, for example with grooves by drawing. SUBSTANCE: method for drawing tubes with inner grooves comprises steps of feeding tubular blank with mandrel into die, deforming it in cone die on shaped mandrel with grooves that is fixed at rear end of blank with possibility of rotation and self-alignment; realizing drawing at deformation degree 25-50% by one pass at providing tightness 1-5 mm of deformed portion of blank on mandrel. EFFECT: enlarged manufacturing possibilities due to forming deeper grooves, enhanced quality of surface, faces and transition zones between smooth areas and grooves.