METHOD OF MAKING LONG-LENGTH HOLLOW ARTICLES Russian patent published in 2016 - IPC B21K21/06 

FIELD: technological processes.

SUBSTANCE: invention relates to metal forming and may be used when manufacturing articles like cases of hydraulic and pneumatic cylinders, crystallizers jackets. Initial billet is placed into a container on a thrust and installed in holes of the guide and the working bushings. Bushing are coaxially placed in the container to form a cavity between their ends. Provided is extending of part of the initial billet at the end intended for shaping above the working bushing end by two diameters of the billet. Said end of the initial billet is placed in the hole of the guide bushing. Then the extending part of the initial billet under action of the male die at fixed working bushing is set and subjected to free piercing. After that the working bushing is unsecured and moved along the billet axis synchronously with the male die movement. Herewith metal of the initial billet released from the working bushing is subjected to swaging and piercing till formation of a bridge between the ends of the male die and the thrust. Produced article is removed from the container under action of the working bushing.

EFFECT: as the result provided is reduction of deformation forces and the article wall thickness deviation and increase of its length in one transfer, as well as obtaining a fine-grained structure of the article metal.

1 cl, 1 dwg