METHOD OF FINAL MOLDING OF LARGE DIAMETER PIPES OF U-SHAPED BILLET AND DEVICE FOR ITS REALISATION Russian patent published in 2008 - IPC B21D5/10 

FIELD: technological processes, pipes.

SUBSTANCE: U-shaped billet is bent in press for giving cylindrical shape to it for one passage of press with the help of stamping tool, upper and lower stamp holders with inserts that form cylindrical shape-generating surface during coupling. For this purpose mandrel is used arranged in the form of bar and segments symmetrically installed in relation to it, which are located higher than the plane of inserts seat. Mandrel is installed into U-shaped billet vertically to its axis. In process of bending upper stamp holder is lowered with inserts and at the same time mandrel segments are spaced until the pipe is completely clamped. Device contains two symmetrically installed stamp holders and set of inserts installed in contact with them along support surfaces, which are installed with the possibility of coupling with creation of internal shape-generating surface. Perimeter of internal shape-generating surface is less than the billet perimeter. There is also mandrel available arranged in the form of bar and segments that are symmetrically installed in relation to it with the possibility of its spacing and permanent contact with the walls of U-shaped billet. At that radius of segment is less than internal radius of the pipe.

EFFECT: higher quality of pipes and reduction of expenses for their manufacture.

5 cl, 3 dwg