EP2773470B1 - Method for producing metal extrusion press products, and extrusion and tube press - Google Patents

Description

The invention relates to a method for producing metallic extruded products on extrusion and tube presses, which have a consisting of a cylinder spar and associated counter-spar press frame in which a movable, a block receiver bearing block pickup holder, which introduced a loader with a block to be pressed in Pressing position in front of the counter-spar spends with the local tool, and a movable stamping cross-member is provided, wherein in the cylinder spar a main or pressing cylinder is arranged, which receives in its cylinder housing at its front, supported by the stamping Traverse end provided with a plunger plunger, and in which the cylinder housing connected to a tank line is associated with an expansion tank supplying hydraulic oil to the plunger by means of a slide plate. Furthermore, the invention relates to extrusion and tube pressing or metal extrusion for performing the method.

An extruder of this type, in which the tool, common pressure plate, die holder and die, having counter-spar is connected via tie rods or tension lamellae and pressure supports with the cylinder spar is through the DE 102 27 488 B3 known. From the EP 1 526 930 B1 a metal extrusion press is known with a pressure vessel to the plunger or plunger attached to the master cylinder reservoir.

In order to achieve a high degree of utilization of the presses, the non-productive times must be minimized, in particular, the idler and the side of the cylinder associated with the Blockaufnehmerhalter, in which the block receiver or recipient is arranged, and the stamping cross member or strut associated idle and retreat with the highest possible speeds can handle. Here, large volume flows between the cylinders and the oil tank to move at high flow velocity, turbulent flows and as a result, air pockets in the oil and foaming can occur. These adverse operating conditions can be counteracted only with expensive measures.

In one by the EP 0 822 017 B1 Known frameless metal extruder coping with large volume flows is to be achieved by two or more plunger provided with their cylinders passing through both sides piston rods of the same diameter and the mutual piston rods are sealed against the cylinders, so that there are cylinder sides of the same effective area. These are connected to one another by a short-circuit line which can be closed by a switchable shut-off valve for working stroke. For a quick return stroke and a fast forward flow, this press provides special piston-cylinder units. About the cylinder subspaces on both sides of the plunger connecting short circuit line a faster transition of the oil from one to the other cylinder subspace with low flow resistance is possible, the short-circuit lines and arranged in this switchable shut-off valves, however, require a large design.

The invention is therefore an object of the invention to provide a method and a strand and pipe press of the type mentioned without the disadvantages described, in particular, the hydraulic effort and reduce the non-productive time with a compact, simpler construction of the extrusion and tube press or metal extrusion press.

This object is achieved by a method according to the invention that the movement and Zustellbewegungen of Blockaufnehmerhalter and stamping Traverse with plunger electromotive and pre-upsetting the loaded into the block receiver block and the subsequent pressing of the block are performed by hydraulic loading of the plunger. It can thus allow a mode of operation with a targeted interplay between electric motor and hydraulic drives. Namely, the billet holder and the stamping cross member or the strut with the plunger are moved by the electric motors, preferably servomotors, at high accelerations and speeds, wherein in addition an exact stop positioning can be ensured. The non-productive times required for the preparation of the actual pressing process can thus be reduced below 13.8 s.

As soon as the billet holder and the plunger have been moved to their final position, the electric motor drive is turned off and switched to hydraulic operation. This allows for the pressing of the loaded block to a strand required high forces for the plunger and for sealingly pressing the Blockaufnehmerhalters or Blockaufnehmers to the tool as well as for applying a stripping force to an end of the strand with a certain length or the Pressrest to be able to expose by removal of the Blockaufnehmerhalters for separation, also required high forces. As no hydraulics are used for the traversing movements, not only the required tank volume, instead of the previous approx. 10,000 liters now only approx. 400 liters, can be significantly reduced, but also a significant cost reduction of the hydraulics due to lower weights (approx. ) reach the required pipelines. The previously large-volume and Thus, bulky tank no longer needs to be placed above the master cylinder, but can be placed next to the extruder and connect via hoses. Because of the only small oil volumes, smaller pumps and valves smaller by two sizes can be used. Furthermore, no cooling power of about 160 KW, but only about 40 KW needs to be applied. The aforementioned comparison values are based on a conventional 25/27 MN standard press.

According to a preferred mode of operation, the invention proposes that for clamping the loaded block between the ram and the tool of the block receiver holder and the stamp crosshead including plunger are simultaneously moved together and electromotively in the pressing direction, wherein from the expansion tank via an integrated in the master cylinder housing, open filling valve, a first Amount of hydraulic oil is pushed into the master cylinder behind the plunger, that after clamping of the block alone the Blockaufnehmerhalter is moved by an electric motor until the block traveled by the Blockaufnehmerhalter block is eingekammert in Blockaufnehmer, whereupon then for pre-upsetting the block with the rear in the pressing direction of the Pressing piston connected, flanged to the rear wall of the expansion tank cylinder unit is acted upon, wherein a second amount of hydraulic oil via the open filling valve behind the plunger a is pushed out, and that the pressing of the block is carried out with a closed filling valve by applying pressure to the rear end of the plunger with hydraulic oil from a tank, accompanied by a third amount of hydraulic oil is expelled from the surge tank into the tank. While the known metal extrusion press with expansion tank required a pendulum volume of about 1,500 liters, now only about 45 liters are needed. The tank is always constantly filled. The injected behind the preferably hydrostatic bearing in the cylinder housing plunger oil quantity is conveyed from the surge tank accordingly in the tank.

According to one embodiment of the invention, the block picker holder is moved back hydraulically by a short distance corresponding to the pressing residual length for stripping the press residue. The press residue protrudes from the billet and can be separated, usually by means of a press shear.

It is proposed according to the invention that, after the completed pressing operation, the block pickup holder and the stamping traverse with the plunger are moved back electromotively into the initial position for loading with a filling block to be pressed with the filling valve open. The small pendulum volume thus returns to the expansion tank and is available again for a new pressing process.

The problem underlying the invention is achieved with a generic extrusion and tube press or metal extrusion, characterized in that the stamping crosshead and the Blockaufnehmerhalter electric motors, preferably servomotors, are assigned as adjusting drives and the plunger via an extending in the expansion tank linkage with an outside of the rear wall attached to the expansion tank, for pre-upsetting the loaded block hydraulically acted cylinder unit is connected, and that the linkage is formed with an integrated in the transition from the reservoir to the master cylinder provided, the local inner diameter of the cylinder housing adapted, in the opening function a large annular area cross-section releasing filling valve. The process or the delivery movements, including clamping and driving over the block, in order to introduce this into the receptacle of the billet holder take over the electric motors. For pre-upsetting or upsetting the block, the cylinder unit is then actuated when the filling valve is open, via which the compression force is thus applied. After swaging or pre-upsetting, the filling valve is closed and then pressed the only small amount of hydraulic oil is fed via a pressure oil line from the tank into the cylinder chamber behind the plunger.

According to one proposal of the invention, an electric motor is provided on each longitudinal side of the Blockaufnehmerhalters and the stamping traverse, which are advantageous via drive pinion engaged with racks. To transfer the drive power, threaded spindle arrangements or roller screw drives are optionally available, which move the block pickup holder and the stamping crosshead into the pressing position.

According to a preferred embodiment of the invention, the rod connecting the plunger with the cylinder unit consists of a mounted on the one hand in the plunger, at its opposite free end of the slide plate bearing outer tube and on the other hand, a dipping into the outer tube, rear of the cylinder unit connected push rod, wherein the immersion the push rod is formed with a temporarily to be pressed against the outer tube clamping device. The concentric nesting of push rod and outer tube makes it possible, these parts by means of the clamping device, which may have a central spline according to a proposal of the invention, which presses upon application of the cylinder unit complementary wedges to the inner wall of the tube, these parts as needed, as for upsetting or Pretending the block to connect to a rigid entity. Alternatively, a hydraulic clamping can be realized. In the clamped state, the slider plate attached to the outer tube is displaced linearly in the expansion tank and feeds a quantity of the hydraulic oil accommodated in the compensating cylinder behind the plunger. Without clamping operation, as in the case of the cylinder unit switched to pressing the block, the outer tube, with the filling valve closed, moves with the stroke of the pressing piston acted upon by the pump via the tank, relative to the fixed one Push rod forward and the slide plate displaces even then oil volume in the tank.

A proposal of the invention provides that the cylinder unit is designed to apply the force for compressing the block when the clamping device is activated via the push rod. The cylinder unit thus fulfills a dual function, namely the operation of the clamping device and the application of the compression force.

According to a preferred embodiment of the invention, the filling valve consists of a valve cover, which is arranged on the outer tube via a collar-like sliding bush, and a bushing in the pressing direction behind the valve cover enclosing annular cylinder, the cylinder piston depending on the acted upon with hydraulic oil piston side the sliding bush and thus the Move the valve cover either to the closed position or to the open position. The filling valve can thus be adjusted as needed, i. adapted to the respective phase of operation, opened over the ring cylinder, as in the ancestor of the billet holder and stamping Traverse, or be closed, as in the case of pre-upsetting presses. In the opening function, the free, large annular area cross-section offers the unhindered, free flow-through possibility to the oil volume either from the expansion tank into the pressure chamber of the plunger cylinder or the oil volume pushed back into the expansion tank after the pressing process by the returning plunger.

According to a further embodiment of the invention the Blockaufnehmerhalter is associated on each longitudinal side at least one with freedom of movement in the longitudinal direction through the cylinder spar guided tow bar, the tow bars are enclosed on a partial length between the cylinder spar and the Blockaufnehmerhalter of a combined Ringzylinder- and clamping unit. These combined units allow the tow bars to advance or move the billet holder by means of the electric motors can be taken unhindered. The clamping function is switched to seal the billet holder in the pressing position for sealing against the tool set of the counterstay. These units are also used for stripping the press residue by switching the pressure in the ring cylinder to the other side, so that the billet holder is slightly removed or withdrawn from the tool set counter to the pressing direction. The clamping device can also be formed here mechanically or hydraulically, for example with clamping pads or the like.

Fig. 1

in perspektivischer Ansicht als Einzelheit einer Strang- und Rohrpresse bzw. Metallstrangpresse deren Pressenrahmen mit darin angeordneter Stempeltraverse und Blockaufnehmerhalter;

Fig. 2

den rückwärtigen Teil der Presse der Fig. 1 einschließlich Zylindergehäuse des Haupt- bzw. Presszylinders und Stempeltraverse mit Elektromotoren und Zahnstangen in einer teilgeschnittenen Draufsicht dargestellt;

Fig. 3

eine Draufsicht wie gemäß Fig. 2, demgegenüber zum Blockstauchen mit aktivierter Klemmeinrichtung;

Fig. 4

eine Darstellung wie gemäß Fig. 2, demgegenüber mit zum Pressen geschlossenem Füllventil dargestellt;

Fig. 5

als Einzelheit der Fig. 2 bis 4 einen Querschnitt durch das im Zylindergehäuse integrierte, von einem Ringzylinder verstellbare Füllventil,

Fig. 6

als Einzelheit der Fig. 2 bis 4 in einem Querschnitt eine Ausführung einer Klemmeinrichtung in nicht aktivierter Funktion;

Fig. 7

die Klemmeinrichtung der Fig. 6 in aktiver Funktion;

Fig. 8a,b

in schematischer Seitenansicht (Fig. 8a) und Draufsicht (Fig. 8b) die Presse der Fig. 1 in der Blockladeposition;

Fig. 9a,b

in schematischer Seitenansicht (Fig.9a) und Draufsicht (Fig. 9b) die Presse in der Betriebsposition zum Klemmen eines geladenen, zu verpressenden Blockes;

Fig. 10a,b

in einer schematischen Seitenansicht (Fig. 10a) und Draufsicht (Fig. 10b) die Presse in der Betriebsposition mit über den zu verpressenden Block vorgefahrenem Blockaufnehmerhalter;

Fig. 11a,b

in einer schematischen Seitenansicht (Fig. 11a) und Draufsicht (Fig. 11 b) die Presse in der Betriebsposition zum Vorstauchen bzw. Stachen des Blockes;

Fig.12a,b

in einer schematischen Seitenansicht (Fig. 12a) und Draufsicht (Fig. 12b) die Betriebsposition beim Pressen des Blockes bis zu einer verbleibenden Pressrestlänge dargestellt;

Fig. 13a,b

in einer schematischen Seitenansicht (Fig. 13a) und Draufsicht (Fig. 13b) die Betriebsposition nach dem Strippen des Pressrestes; und

Fig. 14a,b

in einer schematischen Seitenansicht (Fig. 14a) und Draufsicht (Fig. 14b) die in die Blockladeposition zurückgefahrene Presse.

Further details and features of the invention will become apparent from the claims and the following description of exemplary embodiments illustrated in the drawings. Show it:

Fig. 1

in perspective view as a detail of a strand and tube press or metal extrusion press frame with arranged therein stamping Traverse and Blockaufnehmerhalter;

Fig. 2

the back part of the press Fig. 1 including cylinder housing of the main and stamping cylinder and stamp crosshead with electric motors and racks shown in a partially sectioned plan view;

Fig. 3

a plan view as in accordance with Fig. 2 in contrast, for block diving with activated clamping device;

Fig. 4

a representation as in accordance Fig. 2 in contrast, shown with closed for pressing filling valve;

Fig. 5

as a detail of Fig. 2 to 4 a cross section through the integrated in the cylinder housing, adjustable by a ring cylinder filling valve,

Fig. 6

as a detail of Fig. 2 to 4 in a cross section, an embodiment of a clamping device in non-activated function;

Fig. 7

the clamping device of Fig. 6 in active function;

Fig. 8a, b

in a schematic side view ( Fig. 8a ) and plan view ( Fig. 8b ) the press of Fig. 1 in the block loading position;

Fig. 9a, b

in a schematic side view ( 9a ) and plan view ( Fig. 9b ) the press in the operating position for clamping a loaded block to be pressed;

Fig. 10a, b

in a schematic side view ( Fig. 10a ) and plan view ( Fig. 10b ) the press in the operating position with over the block to be pressed Blockaufnehmerhalter;

Fig. 11a, b

in a schematic side view ( Fig. 11a ) and plan view ( Fig. 11b) the press in the operating position for pre-stitching or staking the block;

Figures 12a, b

in a schematic side view ( Fig. 12a ) and plan view ( Fig. 12b ) illustrates the operating position when pressing the block to a remaining press residual length;

Fig. 13a, b

in a schematic side view ( Fig. 13a ) and plan view ( Fig. 13b ) the operating position after stripping the press residue; and

Fig. 14a, b

in a schematic side view ( Fig. 14a ) and plan view ( Fig. 14b ) the press returned to the block loading position.

From a strand and tube press or metal extrusion press 1 is in Fig. 1 essentially the base frame shown. This consists of a cylinder spar 2 and a tensioned on tension blades 3, not shown here counter-spar 4 (see. Fig. 8a ). For frictional connection of these components continue to contribute pressure supports 5, which enclose the tension blades 3 between the cylinder spar 2 and the counter-spar 4. The pressure supports 5 are also still used to guide receiving a movable in the base frame stamping Traverse 6 and a movable Blockaufnehmerhalters 7. The a Blockaufnehmer or recipient 8 having Blockaufnehmerhalter 7 as well as the stamping crosshead 6, which is the leading end of a cylinder housing 9 in the counter-4 with hydrostatic bearing 10 guided plunger 11 is supported (see Fig. 2 to 4 ) by means of electric motors 12 and 13, in particular servomotors, method. Such an electric motor 12 or 13 is provided on each longitudinal side of the Blockaufnehmerhalters 7 and the stamping Traverse 6. At the rear end of the cylinder housing 9 of the cylinder spar 2 is a surge tank 15 and to the end wall 16 of the surge tank 15 is a cylinder unit 17 is screwed. For pressing and compressing a block 18 loaded in the block receiver 8, the pressing piston 11 has a pressing punch 19.

As in the Fig. 2 to 4 shown, integrated in the cylinder housing 9 of the main or pressing cylinder, a central filling valve 20 is formed, which consists of a large-scale valve cover 21 and a ring cylinder 22 for Füllventilbetätigung. The closer in Fig. 5 shown filling valve 20 is in the embodiment on a attached to the rear end of the plunger 11 outer tube 23 with the interposition of a collar-like sliding bushing 24, on which also the annular cylinder 22 is seated. When loading the in Fig. 5 rear, rear end of the cylinder piston 25 of the annular cylinder 22 with hydraulic oil, the sliding bushing 24 and thus the Füllventildeckel 21 is moved from its closed position shown in solid lines in the opening position indicated by dashed lines, in which the filling valve cover 21 in a contour adapted recess 26 of the plunger 11 is immersed , In the opening position, a large, free Durchströmungs- or annular area cross-section is available, via which the hydraulic oil from the surge tank 15 without much resistance in the pressure chamber of the cylinder housing 9 behind the plunger 11 - and vice versa - can flow. To retract the filling valve cover 21 in the closed position of the annular cylinder 22 is switched so that passes through the pressure oil supply lines hydraulic oil in front of the cylinder piston 25, whereupon the sliding bushing 24 is withdrawn with the filling valve cover 21 accordingly.

The outer tube 23 carrying the annular cylinder 22 with the filling valve cover 21 is here part of a linkage 27, which continues into the expansion tank 15 and is provided at its local end with a slide plate 28 which upon actuation of the plunger 11 in the pressing direction according to arrow 29 the Hydraulic oil over the opened filling valve cover 28 - the Fig. 2 and 3 show its opening position - in the pressure chamber behind the plunger 11 or when closed for pressing filling valve cover 21, as in Fig. 4 represented, in a laterally adjacent to the press tank, as indicated by the arrow pointing downward, expels. The linkage 27 further includes a dipping into the outer tube 23 push rod 31, which is in operative connection with the flanged at the rear end and the end plate 16 of the surge tank 15 cylinder unit 17. The free end of the push rod 31 is formed with a clamping device 32, via which the push rod 31, if necessary, as in the in Fig. 3 illustrated mode of operation of the extruder 1 for block diving, from the inside to the outer tube 23 can be pressed to a rigid movement unit with this. The clamping device 32 is activated by the combined cylinder unit 17 by its cylinder piston 33 is acted upon accordingly.

At one in the 6 and 7 illustrated embodiment of the clamping device 32, this has a screwed to the push rod 31, the central wedge 34 and this associated complementary wedges 35a, 35b. When not activated clamping device 32 (see. Fig. 6 ), the central slide wedge 34 has been moved left in the drawing to the front. If then via the cylinder unit 17, the clamping device 32 is activated (see. Fig. 7 ), the sliding wedge 34 is pulled by the cylinder unit 17 in the drawing to the right, so that the complementary wedges 35a, 35b are pressed against the inner wall of the outer tube 23.

The operation of the combined electric motor and hydraulic working extrusion and tube press 1 is described below with reference to the Fig. 8a, 8b to 14a . 14b described in more detail. The Fig. 8a and 8b represent the block loading position in which the block to be pressed 18 has been moved with a conventional block loader in the center of the press of the extrusion and tube press 1. As can be seen there more clearly, the extrusion and tube press 1 in addition to the already operated components also still provided on each side of the Blockaufnehmerhalters 7, preferably arranged on each side both up and down tow rods 36, with their free ends with freedom of movement the cylinder spar 2 are passed (see also Fig. 1 ). The tow bars 36 are attached to the cylinder spar 2, combined Ringzylinder- and clamping units 37 assigned. In the block loading position, all moving parts are located in the withdrawn starting position from the counter-member 4.

To the in the Fig. 9a, 9b shown terminals of the loaded block 18 between the ram 19 and the tool or tool set 38 of the Gegenholms 4 are by means of the electric motors 12, 13 of the Blockaufnehmerhalter 7 and the stamping crosshead 6 with the plunger 11 and the ram 19 in the pressing direction 29 with open filling valve 20 (FIGS. see. Fig. 2 ), wherein a first amount of hydraulic oil from the surge tank 15 is pushed into the pressure chamber behind the plunger 11. The now clamped block 18 is spent by ancestors of the billet holder 7 by means of the electric motors 13 in the billet 8, as in the Fig. 10a, 10b shown, wherein the tow bars 36 were pulled along with not activated ring cylinder and clamping unit 37. In order to seal the block receiver 8 against the tool set 37, the ring cylinder and clamping units 37 are now activated and the block pickup holder 7 or the block picker 8 is driven by the latter against the tool 37.

The subsequent upsetting or pre-dipping of the block 18 can be the Fig. 11a, 11b remove. For this purpose, the combined cylinder unit 17 is acted upon when the electric motors 12, 13 are switched off, and the clamping device 32 is activated, whereby the push rod 31 is pressed against the outer tube 23. The Zylindereineit 17 then transmits over the rigid linkage 27, consisting of pressure rod 31 and outer tube 23, the compression force on the plunger 11, wherein a second subset of hydraulic oil at even in this compression position open filling valve (see. Fig. 3 ) is pushed into the pressure chamber behind the plunger 11. The subsequent pressing of the block to a remaining Pressrest 39 show the Fig. 12a and 12b , The clamping device 32 is deactivated for pressing and the valve cover 21 of the integrated filling valve 20 is by means of the annular cylinder 22 in his in Fig. 4 shown, retracted in the cylinder housing 9 sealing closed position. The pressing force is achieved by feeding hydraulic oil from the tank 30, as with the upward arrow in FIG Fig. 4 indicated, applied in the pressure chamber behind the plunger 11. Since that Filling valve 20 is closed and the clamping device 32 is deactivated, a third amount of hydraulic oil is expelled from the surge tank 15 with the displacing in the pressing direction 29 plunger 11 of the slide plate 28 of the outer tube 23, said third amount of hydraulic oil into the tank 30 (see. Fig. 4 ) flows in.

To expose the Pressrestes 39 so that it can be sheared off before the Blockaufnehmer 8, the combined Ringzylinder- and clamping units 37 are switched. The Blockaufnehmerhalter 7 wid retracted over the clamped tow bars 36 according to the length of the Pressrestes 39. This stripping end position of the Pressrestes 39 give the Fig. 13a, 13b again.

In preparation for a new loading and pressing operation are open filling valve 20 so that the hydraulic oil can flow out of the pressure chamber behind the plunger into the expansion tank 15, and deactivated clamping device 32 and likewise deactivated Ringzylinder- and clamping units 37 of the Blockaufnehmerhalter 7 and the stamping Traverse. 6 moved back by means of the electric motors 12 and 13, as in the Fig. 14a, 14b represented, whereupon the extrusion and tube press 1 is then ready for a new working game.

LIST OF REFERENCE NUMBERS

1

Extrusion and tube press / metal extrusion press

2

cylinder beam

3

Zuglamelle

4

counter beam

5

pressure support

6

stamp Traverse

7

Billet participants Sustainer

8th

Billet / recipient

9

Master cylinder / master cylinder housing

10

Hydrostatic storage

11

plunger

12

Motor / servomotor

13

Motor / servomotor

14

rack

15

surge tank

16

End wall / rear wall

17

cylinder unit

18

block

19

press die

20

filling valve

21

Füllventildeckel / valve cover

22

ring cylinder

23

outer tube

24

sliding bush

25

cylinder piston

26

recess

27

linkage

28

slide plate

29

Pressing direction / arrow

30

tank

31

pushrod

32

clamper

33

cylinder piston

34

spline

35a, b

complementary wedge

36

tow bar

37

combined ring cylinder / clamping unit

38

Tool / tool set

39

Press remaining

Claims (12)

1. A method for manufacturing metallic extruded products on extrusion and pipe extrusion presses (1) featuring a press frame that is composed of a cylindrical strut (2) and a counter-strut (4) connected thereto, wherein a displaceable billet receptacle holder (7), which carries a billet receptacle (8) and moves a billet (18) to be extruded and introduced by means of a loading device into the extruding position in front of the counter-strut (4) with the associated extrusion die (37), as well as a displaceable plunger crosshead (6), is provided in said press frame, wherein a main or press cylinder is arranged in the cylindrical strut (2) and accommodates in its cylindrical housing (9) a press piston (11) that is connected to a plunger (19) on its front end supported by the plunger crosshead (6), and wherein a compensation tank (15) is assigned to the main cylinder housing (9), which is connected to a tank line, and feeds hydraulic oil to the press piston (11) by means of a slide plate (28),
   characterized in
   that the displacements and feed motions of the billet receptacle holder (7) and of the plunger crosshead (6) with the press piston (11) are realized in an electromotive fashion, and in that the pre-compression of the billet (18) loaded into the billet receptacle (8), as well as the subsequent extrusion of the billet (18), is realized by hydraulically acting upon the press piston (11).
2. The method according to claim 1, characterized in that the billet receptacle holder (7) and the plunger crosshead (6) with the press piston (11) are simultaneously and jointly displaced in the extruding direction (29) in an electromotive fashion in order to clamp the loaded billet (18) between the plunger (19) and the extrusion die (37), wherein a first quantity of hydraulic oil is displaced from the compensation tank (15) into the main cylinder (9) behind the press piston (11) via an opened filling valve (20) integrated into the main cylinder housing (9), in that only the billet receptacle holder (7) is displaced in an electromotive fashion after clamping the billet (18) until the billet (18) transferred by the billet receptacle holder (7) is firmly clamped in the billet receptacle (8), whereupon a cylinder unit (17), which is connected to the rear end of the press piston (11) referred to the extruding direction (29) and flanged onto the rear wall (16) of the compensation tank (15), is acted upon in order to pre-compress the billet (18), wherein a second quantity of hydraulic oil is discharged behind the press piston (11) via the opened filling valve (20), and in that the extrusion of the billet (18) is carried out while the filling valve (20) is closed by acting upon the rear end of the press piston (11) with hydraulic oil from a tank (30), wherein a third quantity of hydraulic oil is simultaneously discharged from the compensation tank (15) into the tank (30).
3. The method according to claim 2, characterized in that the billet receptacle holder (7) is hydraulically moved back opposite to the extruding direction (29) by a short distance corresponding to the residual extrusion length in order to strip the remainder (39).
4. The method according to one of claims 1-3, characterized in that the billet receptacle holder (7) and the plunger crosshead (6) with the press piston (11) are after the completed extrusion process moved back into the home position in an electromotive fashion while the filling valve (20) is opened in order to be loaded with a new billet (18) to be extruded.
5. An extrusion and pipe extrusion press (1) featuring a press frame that is composed of a cylindrical strut (2) and a counter-strut (4) connected thereto, wherein a displaceable billet receptacle holder (7), which carries a billet receptacle (8) and moves a billet (18) to be extruded and introduced by means of a loading device into the extruding position in front of the counter-strut (4) with the associated extrusion die (37), as well as a displaceable plunger crosshead (6), is provided in said press frame, wherein a main or press cylinder is arranged in the cylindrical strut (2) and accommodates in its cylindrical housing (9) a press piston (11) that is connected to a plunger (19) on its front end supported by the plunger crosshead (6), and wherein a compensation tank (15) is assigned to the main cylinder housing (9), which is connected to a tank line, and feeds hydraulic oil to the press piston (11) by means of a slide plate (28), particularly for carrying out the method according to claim 1,
   characterized in
   that adjustment drives in the form of electric motors (12, 13) are assigned to the plunger crosshead (6) and the billet receptacle holder (7), in that the press piston (11) is connected to a cylinder unit (17), which is mounted on the outside of the rear wall (16) of the compensation tank (15) and hydraulically acted upon in order to pre-compress the billet (18) to be loaded, by means of a rod assembly (27) extending in the compensation tank (15), and in that the rod assembly (27) is realized with a filling valve (20) that is integrated into the transition from the compensation tank (15) to the main cylinder, wherein said filling valve is adapted to the corresponding inside diameter of the cylinder housing (9) and opens a large annular cross section in the open position.
6. The extrusion and pipe extrusion press according to claim 5, characterized in that an electric motor (12, 13) is provided on each longitudinal side of the billet receptacle holder (7) and the plunger crosshead (6), wherein said electric motors are engaged with toothed racks (14).
7. The extrusion and pipe extrusion press according to claim 5 or 6, characterized in that the electric motors (12, 13) are servomotors.
8. The extrusion and pipe extrusion press according to one of claims 5-7, characterized in that the rod assembly (27) connecting the press piston (11) to the cylinder unit (17) consists of an outer tube (23) that carries the slide plate (28) on its opposite free end and of a pressure rod (31) that penetrates the outer tube (23) and is connected to the rear of the cylinder unit (17), wherein the penetrating end of the pressure rod (31) is realized with a clamping device (32) to be temporarily pressed on the outer tube (23).
9. The extrusion and pipe extrusion press according to claim 8, characterized in that the clamping device (32) features a central slide wedge (34) that presses complementary wedges (35a, 35b) on the inner wall of the outer tube (23) when acting upon the cylinder unit (17).
10. The extrusion and pipe extrusion press according to one of claims 5-9, characterized in that the cylinder unit (17) is designed for exerting the force for compressing the billet (18) via the pressure rod (31) when the clamping device (32) is activated.
11. The extrusion and pipe extrusion press according to one of claims 5-10, characterized in that the filling valve (20) consists of a filling valve cover (21) that is arranged on the outer tube (23) by means of a collar-like sliding bush (24) and an annular cylinder (22) that encloses the sliding bush (24) behind the valve cover (21) referred to the extruding direction (29), wherein the cylinder piston (25) of said annular cylinder either moves the sliding bush (24) and therefore the valve cover (21) into the closed position or into the open position depending on the side of the piston acted upon with hydraulic oil.
12. The extrusion and pipe extrusion press according to one of claims 5-11, characterized in that at least one drag rod (36), which extends through the cylindrical strut (2) with freedom of motion in the longitudinal direction, is assigned to the receptacle holder (7) on each longitudinal side, wherein the drag rods (36) are enclosed by a combined annular cylinder and clamping unit (37) over a section between the cylindrical strut (2) and the billet receptacle holder (7).

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