Process and equipment for the commercial indirect extrusion of long lengths of metal, in particular long as-cast billets into sections or the like

A process for the extrusion of billets into sections or the like with the help of a container and an extrusion die, which comprises:

• dividing the container in contact with the billet to be extruded into at least two segments which can be opened and closed radially to the long axis (A) of the container and the billet wherein said container when closed clamps that part of the billet of length (La) to be extruded at least up to the die area;
• providing on opening said segments a relative movement in the direction along said axis (A) between the billet and the container, as a result of which the container is filled by the billet essentially over its whole length (L);
• producing after closing said segments a relative movement between a die mounted on a hollow stem and the closed container, whereby said die is forced into the billet inside the container so that said part of the billet of length (La) inside the container is extruded through the opening in the die thus forming at least one section;
• transmitting a force which is at least equal to the force required to extrude said at least one section to the length (Le) of said billet inside the container not extruded by means of the friction between the inner wall of the closed container and the surface of the billet;
• filling the container by applying a force which is small compared with the extrusion force and which is borne by a part of the billet projecting out of the container;
• and
• opening said segments at the end of an extrusion sequence, whereupon a relative movement between the container and the die returns them to their starting position and a relative movement between the container and the billet of distance (La) fills the container again, so that after closing said segments a new length (La) of said billet can be extruded.