METHOD FOR MAKING SEAMLESS STEEL TUBES Russian patent published in 2001 - IPC

FIELD: manufacture of steel seamless tubes. SUBSTANCE: method of making tube of solid blank by hot piercing and extrusion for one working cycle of press comprises steps of heating blank, lubricating it, successively piercing blank, extruding tube and separating tube from remainder of blank. Tube is made in vertical hydraulic tube extrusion press having apparatus for cutting off remainder of blank at using pressure pad non-coupled with extrusion ram and technological lubricant of glass material. Lubricant is applied onto lateral surface of heated blank at rolling the last on glass powder and it is applied also onto die and upper end of blank in the form of preliminarily compacted discs at using turned blank having recess for glass disc on its one end and radially rounded edge on its opposite end. Before piercing blank is upset in container by means of extrusion ram , the last is then lifted over blank in order to create free space for increased height of blank at piercing. It is possible to use blank with preliminarily drilled central opening having cone flared portion near its upper end and with reduced outer diameter providing increased annular gap between blank and wall of container cavity. Such blank is pierced by expanding method with use of needle having special expanding tip without preliminary upsetting of blank by extrusion ram and without lifting extrusion ram over blank. EFFECT: lowered investment for building tube production plant, reduced labor consumption, operational cost of making tubes, favorable conditions for building metallurgical mini-shops and organization of tube manufacture process in storage shops of machine engineering plants, enhanced quality of tubes, significantly improved ecological characteristics of tube manufacture process. 2 cl