Extruder and tube extruder or metal extrusion press

Abstract

A tube or metal extrusion press has a stationary press frame formed by a main housing, a counter housing, a billet support carrying a billet holder, and a ram cross-member movable in the press frame between the housings. A piston-cylinder unit has a cylinder on the main housing, a piston in the cylinder, and a ram stem extending between a front end of the piston and the ram cross-member. An equalizing reservoir supplies hydraulic fluid to the piston, and a transfer passage extends between the reservoir and the cylinder rearward of the piston. A fill valve has a displacement sleeve on a rod and carries a ring piston and a fill valve body movable centrally of the cylinder in the transfer passage between an open position in which the passage has a large annular flow cross-section and a closed position in which the valve body blocks the passage.

Claims

1. A tube or metal extrusion press comprising: a stationary press frame formed by a main housing and a counter housing attached thereto and spaced therefrom; a billet support carrying a billet holder and a ram cross-member movable in the press frame between the main housing and the counter housing; a piston-cylinder unit having a cylinder on the main housing, a piston in the cylinder, and a ram stem extending between a front end of the piston and the ram cross-member; an equalizing reservoir associated with the cylinder and supplying hydraulic fluid to the piston; a transfer passage extending between the reservoir and the cylinder rearward of the piston; a piston disk in the reservoir; a rod extending between a rear end of the piston and the disk and extending in the equalizing reservoir; a fill valve having a displacement sleeve carried on the rod and carrying a ring piston and a fill valve body integrated centrally in the cylinder and movable in the transfer passage between an open position in which the passage has a large annular flow cross-section and a closed position in which the valve body blocks the passage; and feed lines effective on opposite faces of the ring piston for pressurizing the ring piston alternately and thereby shifting the displacement sleeve, ring piston, and fill valve body between the open position and the closed position, whereby in the open position the cylinder can fill rapidly from the reservoir or empty rapidly into the reservoir and in the closed position the cylinder can be pressurized for extrusion of a billet in the holder.

2. The press according to claim 1, further comprising: electric motors for shifting the ram cross-member and the billet support in the press frame for rapid filling and emptying of the cylinder in the open position of the valve.

3. The press according to claim 1, further comprising: means for pressurizing the cylinder rearward of the piston in the closed position of the valve for extrusion of the billet in the holder.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Additional features and details of the invention are revealed in the claims and in the following description of embodiments shown in drawing. Therein:

(2) FIG. 1 is a perspective view showing a detail of a tube or metal extrusion press showing its press frame including a ram cross-member and billet support;

(3) FIG. 2 is a partial cutaway view of the rear end of a tube/extrusion press, without the ram cross-member and billet support; and

(4) FIG. 3 is a sectional detail from FIG. 2 showing the fill valve integrated into the cylinder of the piston-cylinder unit in the transfer passage to the equalizing reservoir.

SPECIFIC DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows essentially the basic frame of a tube or metal extrusion press 1. This frame is formed by a cylinder housing 2 and a counter housing that is spaced therefrom, fixed relative thereto by lamellar tie rods 3, and not shown here but indicated at the end of lamellar tie rods 3 only by reference numeral 4. Compression beams 5 furthermore contribute to creating the positive connection between these components and surround the lamellar tie rods 3 between the cylinder housing 2 and the counter housing 4. These compression beams 5 also act as guides for a ram cross-member 6 that is movable within the base frame, and of a movable billet support 7. The ram cross-member 6 that supports the front end of a piston 11 guided inside a cylinder 9 in the counter housing 4 in a bushing 10 (see FIG. 2) and the billet support 7 that has a billet holder 8 are here moved in an extrusion direction 14 by respective electric motors 12 or 13, in particular servomotors. One electric motor 12 or 13 of this type is provided on each longitudinal side of the billet support 7 and the ram cross-member 6. Pinions of the electric motors 12 or 13 engage gear racks in order to transmit force or create movement.

(6) An equalizing reservoir 15 is bolted onto the rear end of the cylinder 9 of the cylinder housing 2, and a cylinder or hydraulic connector 17 is bolted onto the end or rear wall 16 of the reservoir that is constructed for example as disclosed in EP 1,526,930. Optionally, the press 1 can be fitted with known hydraulically actuated and laterally mounted cylinders and container displacement cylinders instead of the electric motors 12 and 13, in order to effect the travel and feed motions of the ram cross-member 6 and the billet support 7. The piston 11 has a stem 18 responsible for the upsetting and extruding a billet in the billet holder 8.

(7) FIG. 2 illustrates that a central fill valve 19 is integrated in the cylinder 9 of the piston-cylinder unit, the fill valve being formed by an extended valve body 20 and a ring cylinder 21 that actuates the fill valve. FIG. 3 is an enlarged detail showing that the fill valve 19 is provided on a rod 23 that is attached to the rear end of the piston 11, extends into the equalizing reservoir 15, and there supports a piston disk 22, a collar-like displacement sleeve 24 being provided that is surrounded by the ring cylinder 21. When the rear end of a ring piston 25 in the ring cylinder 21 is acted upon by hydraulic fluid, a displacement sleeve 24 and the fill-valve body 20 are moved from a closed position shown by solid lines and resting on a valve-seat seal 26 into an open position indicated by broken lines in which the valve body 20 fits into a complementary recess 27 of the piston 11.

(8) When the fill valve 19 is in the open position, a large free flow cross-section or annular cross-section is provided through which the hydraulic fluid can flow with little resistance from the equalizing reservoir 15 into the pressure chamber of the cylinder 9 in back of the piston 11, as well as flow in the reverse direction. To move the fill valve 20 into the closed position, pressurization of the ring cylinder 21 is reversed so that hydraulic fluid is pressurized in front of the ring piston 25 to retract the displacement sleeve 24 together with the fill valve body 20. The hydraulic fluid lines connected to an unillustrated supply for delivering hydraulic fluid in front of and in back of the ring piston 25 are indicated at 28, 29, and 30 in FIG. 3, an end-position buffer 31 being associated with the hydraulic fluid line 28 as shown in FIG. 2.

(9) In response to the in-feed motions, i.e. travel of the ram cross-member 6 and/or the billet support 7 in the extrusion direction 14, hydraulic fluid is forced by simultaneously moving the piston disk 22 by the opened fill valve body 20 and through the thereby exposed large flow cross-section from the equalizing reservoir 15 into the pressure chamber in back of the piston 11 until the piston 11 has moved into an intermediate position for the extrusion process. For the actual subsequent extrusion, the fill valve 19 is closed and the extrusion force is applied by feeding hydraulic fluid from a tank 32 indicated by the upward-pointing arrow in FIG. 2 into the pressure chamber in back of the piston 11. Since the fill valve 19 is closed, the piston 11 moves it in the extrusion direction 14 to pull the piston disk 22 by the rod 23 out of the equalizing reservoir 15 to force additional fluid into the tank 32 as indicated by the downward-pointing arrow in FIG. 2.

(10) In order to prepare for a new loading and extrusion operation, the hydraulic fluid flows in response to rearward motion of the piston 11 through the fill valve 19, now re-opened by the ring cylinder 21, back into the equalizing reservoir 15, i.e. the hydraulic fluid is forced back and forth with little resistance when the tube/extrusion press 1 is operating. It is obvious that the drives (electric motors or displacement cylinders) of the ram cross-member 6 and of the billet support 7 are actuated accordingly.