EP0289638B1 - Press, in particular for making dimensionally stabilized pressed articles from materials in powder form, and method for the operation of such a press - Google Patents

Abstract

1. Press, more especially for the production of pressed elements true to size from materials in powder form, having a press stand, in which are provided a press frame and a press table as main and guide axis, which are immovably connected to one another by a mechanical drive means, especially a toggle lever drive, and form a main press ram, characterised in that a hydraulic press part (12) with at least one additional pressing axis or with several additional pressing axes (M-pressing axis, Z-pressing axis and Y-pressing axis) is able to be installed before the main pressing ram (X-pressing axis) between press frame (5) and press table (4) of the mechanical press part (2), that the hydraulic press part (12) forms a self-contained built-in adapter for the mechanical press part (2), and that the working movement of each press shaft or axis of the hydraulic press part (12) can be controlled and regulated (22 to 33), dependent on travel and time (30), by the working movement of that main and guide shaft (X-pressing axis) of the mechanical press part (2) which consists of press frame (5) and press table (4).

Description

The invention relates to a press which can be used, in particular, for producing dimensionally stable compacts from powdery materials, but which is also suitable for other uses, for example in the fields of plastics pressing technology, deep-drawing technology and stamping technology.

The starting point of the invention is a mechanical press with a press frame, in which a press frame and a press table are provided, which are coupled to one another by a mechanical drive, primarily a toggle lever drive, and form a main press ram, which during press operation functions as a so-called main and leading axis is effective.

Hydraulic automatic presses are already known for producing dimensionally stable compacts from powdery materials, which can also be used in the production of complex molded parts, in particular those with one or more graded shapes (see e.g. DE-A 31 42 126). For each stage to be formed on the pressing part, the actual pressing tool works with its own pressing axis, to which a special hydraulic drive is assigned within the press, in such a way that each of these hydraulic drives drives another relative to the pressing tool between its filling position and its pressing position Run to work or must be controlled.

Between the individual hydraulic drives of these known hydraulic press machines, there is inevitably a relatively complicated movement sequence, which is essentially determined by the shape of the pressed articles to be produced, and which can only be effected and monitored by complex electronic control systems.

Nevertheless, in the known hydraulic automatic presses it is not guaranteed that the movements of the various hydraulic drives required during each individual pressing process are actually carried out in exact coordination. This is because it is not ensured that the supply of the hydraulic fluid to the individual hydraulic drives is always exactly constant in terms of quantity and speed, since pressure overlaps often occur. This then results in non-predeterminable superimposed movements of the hydraulic drives, which cannot be compensated for even by the electronic control and can therefore impair the work result on the compacts.

Another disadvantage of the known hydraulic automatic presses is that all hydraulic drives have to travel relatively long strokes and thus only allow low strokes which impair productivity.

The invention has for its object to provide a press of the type described at the outset, which not only ensures perfectly reproducible operation of all cooperating press axes, but can also be operated at relatively high stroke rates. A further goal is a high level of dimensional stability of the entire press system with permanently high functional reliability.

Nevertheless, flexible movement and drive options for the individual press axes should be accessible and pressure-independent path control of the same should be made possible.

The object is achieved according to the characterizing part of claim 1 in that in front of the main press ram between the press frame and the press table of the mechanical press part, a hydraulic press part with an additional press axis or several additional press axes can be used, that the hydraulic press part is a self-contained installation -Adapters for the mechanical press part, and that the working movement of the main and leading axis of the mechanical press part consisting of the press frame and press table can be controlled and regulated.

The advantage of such a press system is that it can only be achieved using an existing mechanical press, in particular a toggle press, by integrating an additional hydraulic press part.

Since, according to the proposal of claim 2, the press axis or press axes of the hydraulic press part can have determinable press paths different from the press axis of the mechanical press part, it is also achieved that the long stroke paths of the press system according to the invention can be derived from the mechanical press part with high stroke rates, while only the much smaller stroke distances have to be covered by the hydraulic press part and can therefore also be adapted to high stroke rates.

In the hydromechanical press system according to the invention, however, the mechanical press part not only determines the implementation of the long stroke distances at high stroke rates, but also performs the control and control function for all hydraulically effected working movements in a particularly advantageous manner. An optimal level of reproducibility and operational safety is therefore achieved and at the same time the possibility of flexible movements is maintained by the hydraulic press part.

According to a further feature of the invention, claim 3 proposes that each press axis of the hydraulic press part is coupled or can be coupled to the main press axis via an electrical or electronic displacement encoder. In addition, according to claim 4, the press axes of the hydraulic press part, with the interposition of a CNC path control via electronic travel ratio value specification units, can be freely programmably coupled to the travel sensors assigned to the mechanical press part, in such a way that the translation or movement ratio of the hydraulic press part can be varied relative to the mechanical press part within predetermined limits, preferably continuously, while the presses are moving frame of the mechanical press part, which acts as the main and leading axis, moves in a fixed 360 _° path-time curve.

According to claim 5, the invention provides that the hydraulic cylinders of the various press axes of the hydraulic press part can each be pressurized with their own control loops and high-pressure pumps with pressure medium, and each control loop also includes an associated travel ratio value input in addition to the displacement encoder.

These measures contribute to the fact that each press axis of the hydraulic press part is operated independently of all other press axes of the same and can thus be influenced in direct dependence on the mechanical press part. This ensures trouble-free and effective control technology for the individual press axes of the hydraulic press part.

In practical operation of the press system according to the invention, it proves useful if the control pressure and back pressure for the hydraulic cylinder of the M press axes of the hydraulic press part can be selectively adjusted, the control pressure being adjustable up to 70 bar and the back pressure up to 350 bar. The hydraulic cylinders for the Z-axis and the Y-axis can be controlled up to 350 bar via servo hydraulics. Preferably, however, the hydraulic cylinder of the M-axis is also optionally and additionally controllable up to 350 bar via servo-hydraulics.

It has also proven useful if up to 50% of the nominal press force of the mechanical press part can be applied to each individual press axis of the hydraulic press part in a press according to the invention. In this way, an optimal material and pressure distribution is achieved in the various press levels, which guarantees the creation of high-quality compacts.

The modular structure of a press according to the invention can also be favorably influenced in that the hydraulic press part - according to claim 8 - can be coupled to the press frame and the press table of the mechanical press part mechanically by means of clamping wedges, but easily detachable, so that an existing mechanical press can be passed through at any time Installation of the hydraulic press part can be tailored to different needs. Within the scope of this possibility, it also proves important that - according to claim 9 - the hydraulic press part with at least three press axes forms the self-contained built-in adapter for the mechanical press part.

A compact and at the same time highly dimensionally stable structure for the hydraulic press part can be achieved according to the features of claim 10 in that the travels of the hydraulic cylinders for the individual press axes of the hydraulic press part correspond to only a fraction of the stroke of the press axis of the mechanical press part. In most cases, the hydraulic cylinders of the hydraulic press part come with travel distances of up to 20 mm, while the stroke distance for the press axes of the mechanical press part can be up to 120 mm.

While, according to claim II, the press axes of the hydraulic press part can usually be moved in the same direction as the direction of movement of the press axes of the mechanical press part, they can optionally also be moved in opposite directions if this should be expedient for the pressing process.

In many cases it turns out to be useful or even necessary that the mechanical press part, e.g. assigned to the press table, according to claim 12, is a press ram or press ram (E-press axis) which can also be actuated by a mechanical drive, preferably a cam or cam drive.

In the context of the invention it is further proposed according to claim 13 that the electrical or electronic displacement encoder for the control and regulation of the hydraulic press part is arranged or installed between the press frame and the press table of the mechanical press part, while there are further electrical or electronic displacement transducers selective layer detection are located on the different press axes of the hydraulic press part. With the help of the CNC path control or its path ratio value input, the path encoders can be queried, compared with each other and, if necessary, readjusted proportionally, depending on the mechanical acting as the main and master axis Press part.

For many purposes of a press according to the invention, it can also prove important that the individual press axes of the hydraulic press part can be optionally locked against one another or released relative to one another, because this makes it easy to adjust the hydraulic press part to the shape of the compact to be manufactured is made possible.

For optimal functioning of the hydraulic press part, it proves to be important that, according to claim 15, the position measuring sensors of the same are directly assigned to the piston and the cylinder housing of the associated hydraulic cylinders and, according to claim 16, to the position measuring device of the mechanical press part via the CNC path control or the associated microprocessor correspond.

For the production of compacts with undercuts, an essential feature of the invention according to claim 17 is that the Y-press axis can be switched on or acted upon for the opposite direction of movement or counter-press movement after reaching the press position or the bottom dead center of the X-press axis.

A method according to the invention for operating a press for producing dimensionally stable compacts from powdery materials is distinguished according to claim 18 essentially by the fact that the mechanical pressing movement is superimposed on at least one hydraulic pressing movement and the hydraulic pressing movement is controlled and / or regulated in direct and exclusive dependence on the mechanical pressing movement. Working accuracy and working speed in this mode of operation of a press depend exclusively on the mechanical press part and can be reproduced exactly at any time.

According to claim 19, it is further contemplated that the speed of the hydraulic press movements is determined and / or influenced proportionally in a path-dependent manner by the speed of the mechanical press movements and as a result an optimal compaction of the powdery material within the press mold to the compact can be achieved.

A press according to the invention and the method for operating the same can be used in a particularly advantageous manner when it comes to the production of compacts from powdery materials by the so-called double-die method, as is described on pages 854 to 856 in the "Handbook of Forming Technology" , published in 1981 by Karl Hanser Verlag, Munich.

• Figur 1 in rein schematischer Prinzipdarstellung den Gesamtaufbau eines hydromechanischen Pressensystems,
• Figur 2 in Seitenansicht und teilweise im Schnitt den mechanischen Teil des Pressensystems im Bereich seiner mit dem Pressenrahmen gekuppelten Kniehebel-Antriebsvorrichtung,
• Figur 3 eine der Fig. 2 entsprechende Darstellung des mechanischen Pressenteils, jedoch im Bereich des Antriebs für den im Pressentisch höhenverschiebbar geführten zweiten Preßstößel für Zug- bzw. Druckbeaufschlagung (G-Preßachse),
• Figur 4 eine Ansicht in Pfeilrichtung IV der Fig. 2 und 3, wobei jedoch durch Integration eines hydraulischen Pressenteils in den mechanischen Pressenteil ein hydromechanisches Pressensystem gebildet ist,
• Figur 5 in größerem Maßstab und im Vertikalschnitt ausschließlich den hydraulischen Pressenteil des in Fig. 4 der Zeichnung dargestellten hydromechanischen Pressensystems und
• Figur 6 ein Diagramm der Arbeitsweise eines hydromechanischen Pressensystems beim Pulverpressen im Gegenpreßverfahren mit stehender Matrize.

The object of the invention is shown in the drawing. Show it

• FIG. 1 shows the overall structure of a hydromechanical press system in a purely schematic representation,
• FIG. 2 shows a side view and partly in section the mechanical part of the press system in the area of its toggle lever drive device coupled to the press frame,
• 3 shows a representation of the mechanical press part corresponding to FIG. 2, but in the area of the drive for the second press ram, which is guided in a height-displaceable manner in the press table, for the application of tension or pressure (G press axis),
• FIG. 4 shows a view in the direction of arrow IV of FIGS. 2 and 3, but a hydromechanical press system is formed by integrating a hydraulic press part into the mechanical press part,
• Figure 5 on a larger scale and in vertical section exclusively the hydraulic press part of the hydromechanical press system shown in Fig. 4 and
• Figure 6 is a diagram of the operation of a hydromechanical press system for powder pressing in the counter-pressing process with a stationary die.

1 of the drawing shows a hydromechanical press system I which has a toggle press 2 as a mechanical press part. This toggle press 2 has a press frame 3 which carries a press table 4 and in which a press frame 5 is guided so that it can be raised and lowered relative to the press table 4.

The press frame 5 is moved in the press frame 3 via a toggle lever system 6 which engages on the one hand via a joint 7 on the press frame 3 and on the other hand via a joint 8 on the press frame 5.

A push rod 10 is in drive connection with the knee joint 9 of the toggle lever system 6, which can be formed, for example, by the crank pin of a crank mechanism 11, which is accommodated in the press frame 3, but is not shown in FIG. I for the sake of simplicity.

The push rod 10 is moved by the drive in a fixed 360 _° path-time curve in such a way that the toggle lever system 6 continuously performs alternating movements between its extended position and a predetermined kink position and thus the press frame 5 relative to the press table 4 has a precisely defined one , relatively large stroke.

In the mechanical press part designed as a toggle press 2, namely between the stationary press table 4 and the liftable and lowerable press frame 5, a hydraulic press part 12 is adapted, in which the actual pressing tool 13 is in turn integrated.

The main press ram of the hydromechanical press system I is formed by the cooperation of press table 4 and press frame 5 of the mechanical press part, i.e. the toggle press 2, and is the so-called main and leading axis - the so-called X axis - for the entire hydromechanical press system I. effective.

The hydraulic press part 12 of the hydromechanical press system I also forms at least one further, but preferably several more press axes within the hydromechanical press system I. According to FIG. I of the drawing, the hydraulic press part 12 is designed, for example, so that it has three additional press axes, namely the so-called M-press axis, the so-called Z-press axis and the so-called Y-press axis. The M press axis acts on the die 15 of the pressing tool 13 via hydraulic cylinders 14, while the Z press axis acts on a piston rod 17 in the tool 13 via a hydraulic cylinder 16 and the Y press axis via a hydraulic cylinder 18 on an upper piston rod 19 in the press tool 13 acts. The upper main press ram 20 and the lower main press ram 21 are actuated via the main press ram of the toggle press 2, which is formed by the press table 4 and the press frame 5 and is effective as a so-called X press axis; they therefore carry out the main pressing movement within the hydromechanical press system I.

High-pressure pumps 22, 23, 24, which operate separately from one another and are connected to a common liquid reservoir 25, are provided for pressurizing the hydraulic cylinders 14, 16 and 18 of the hydraulic press part 12. The forward and return flow of the hydraulic fluid to and from the hydraulic cylinders 14, 16 and 18 is controlled and regulated by means of servo valve systems 26, 27 and 28, which in turn can be influenced by associated electronic travel ratio value input units 29 are.

The electronic travel ratio value input units 29 are freely programmed via a CNC path control as a reference control scale for the X press axis. The input of these displacement ratio value input units 29 lies in comparison with the electronic displacement encoder 30, which is assigned to the mechanical press part forming the main and leading axis for the hydromechanical press system I, i.e. the toggle press 2, namely between its press table 4 and its press frame 5 is installed.

By means of the travel ratio value input units 29, the relative press travel in relation to the main and leading axis, the so-called X, can be determined for each individual press axis of the hydraulic press part 12, that is to say for the M press axis, the Z press axis and the Y press axis - Press axis, specify. Via the displacement encoder 30 and the displacement ratio value input units 29, the valve systems 26 to 28 for the hydraulic cylinders 14, 16 and 18 of the M press axis, the Z press axis and the Y press axis are influenced in such a way that they correspond to the respectively set one Path ratio corresponding, proportional control and / or regulation of the pressure fluid supply to the various hydraulic cylinders 14, 16 and 18 cause.

To form closed control loops, each individual hydraulic cylinder 14, 16 and 18 is additionally assigned its own electronic position transducer 31, 32, 33, which is used for selective position sensing of these hydraulic cylinders 14, 16 and 18 and these are continuously sent to the travel ratio value input units 29 reports back. Corresponding to the displacement encoder 30 between the press table 4 and the press frame 5 of the toggle press 2, the individual valve systems 26, 27 and 28 are then influenced by the displacement ratio value input units 29 to ensure exact compliance with the specified displacement ratios in the hydraulic press part 12.

The control, the sequential control, the control control and the correction control of the hydraulic press part is optimally ensured because each of the electronic position transducers 30, 31, 32 and 33 as well as the travel ratio value input units formed by a microprocessor and the CNC path control, because each individual press axis, i.e. the M press axis, the Z press axis and the Y press axis, works together with its own closed control loop, to which the controlled variable is specified by the displacement encoder on the main press ram of the mechanical press part, i.e. the X press axis of the toggle press 2.

The valve systems 26, 27 and 28 for pressurizing the hydraulic cylinders 14, 16 and 18 with hydraulic fluid are designed or constructed so that they can be servo-controlled for the M-press axis, the Z-press axis and the Y-press axis of the hydraulic press part 12 can be set selectively, the control pressure should preferably be adjustable up to 350 bar. In addition, the M-press axis can be selectively pressure-adjusted via a special valve unit in the flow with 70 bar control pressure and 350 bar back pressure. The hydraulic cylinder 14 for the M-press axis, the hydraulic cylinder 16 for the Z-press axis and the hydraulic cylinder 18 for the Y-press axis can independently with the help of the associated valve system 26, 27, 28 with up to 50% of the nominal press force of the mechanical Press part, that is, the toggle press 2, are applied, with the result that optimal work results are obtained in the production of compacts from powdery materials.

In the hydromechanical press system it is provided that the travel paths of the hydraulic cylinders 14, 16 and 18 for the M press axis, the Z press axis and the Y press axis of the hydraulic press part 12 are only a fraction of the stroke path for the X press axis of the mechanical press part, namely the toggle press 2 correspond. The stroke of the main press ram forming the X press axis between its top dead center and its bottom dead center should be at least 120 mm, while travel paths of about 20 mm have proven to be sufficient for the hydraulic cylinders 14, 16 and 18.

An important design feature is also that the hydraulic cylinders 14, 16 and 18 assigned to the M press axis, the Z press axis and the Y press axis of the hydraulic press part 12 optionally in the same or opposite direction to the direction of movement of the X press axis on the toggle press 2 can be pressurized with hydraulic fluid. In order to enable this different mode of operation, the hydraulic cylinders 14, 16 and 18 are each designed in a double-acting design.

Furthermore, the possibility is envisaged that the individual press axes of the hydraulic press part 12, that is to say the M press axis, the Z press axis and the Y press axis, can optionally be locked against one another or released relative to one another, so that the hydromechanical press system I its operation can be easily adapted to a wide variety of manufacturing conditions.

For the operation of the hydromechanical press system I, it is essential that its mechanical press movement can be superimposed on at least one hydraulic press movement and that each hydraulic press movement is controlled and / or regulated in direct and exclusive dependence on the mechanical press movement. Here, the speed of the hydraulic pressing movements is determined and / or influenced proportional to the path by the speed of the mechanical pressing movement, and consequently the compression of the powdery materials in the manufacture of dimensionally stable compacts is achieved in an optimal manner and the formation of relaxation cracks is effectively counteracted.

2 and 3 of the drawing is a detailed representation of the basic structure of the mechanical press part, that is, the toggle press 2 in To see vertical section or in side view, while the overall structure of the hydromechanical press system is shown in FIG. 4 in front view and partly in section. Finally, only the hydraulic present part 12, which is adapted into the toggle press 2 in FIG. 4, can be seen in FIG. 5 in enlarged detail and in vertical section.

The Fig. 2 of the drawing can be seen that the press frame 5 in the press frame 3 is raised and lowered relative to the press table 4 and the press frame 5 receives its drive movement from the toggle lever system 6, that of the connecting rod 10 designed as a connecting rod 10 via the crank mechanism II is moved. The crank mechanism II is in constant drive connection with a flywheel drive with countershaft 34, which in turn is driven by an electric motor 35, which can be seen, for example, in FIG. 3.

According to FIG. 3, a cam 37 is wedged onto the bearing journal 36 of the crankshaft of the crank mechanism II, this cam 37 being easily exchangeable and can therefore be replaced if necessary. The various cam disks 37 can have different curve shapes and can optionally also be provided with double curves.

With the respective cam plate 37, a rocker 40 can cooperate either via a roller 38 or a roller 39, but in certain cases also simultaneously via both rollers 38 and 39, which is wedged onto a shaft 41 which is limitedly rotatable in the press frame 3. On the other hand, the shaft 41 carries a lever 42 which acts on a counterpressure or pull ram 43 which is guided in the press table 4 so that it can be raised and lowered. The counterpressure or pulling plunger 43 forms a further pressing axis, the so-called G-pressing axis, within the hydromechanical press system I, this G-pressing axis being moved in a rhythm predetermined by the respective cam plate 37 in direct mechanical dependence on the toggle lever press 2. 4, partially in section, the overall structure of the hydromechanical press system I with the toggle press 2 and the hydraulic press part 12 can be seen. In the press frame 3, the press frame 5 is raised and lowered and the press table 4 is supported in a stationary manner.

The hydraulic press part 12, which is designed as a self-contained installation adapter, rests on the press table 4 and is coupled to it mechanically in a form-fitting manner, but easily detachably, via clamping wedges 45. In addition, the hydraulic press part 12 is also mechanically positively connected to the upper cross yoke 44 of the press frame 5 by means of corresponding clamping wedges 46 in an easily releasable coupling connection. The rapid installation and removal of the hydraulic press part 12 into and out of the toggle press 2 is therefore possible without problems in the front area thereof.

As can be seen particularly clearly from FIG. 5, the hydraulic press part 12 has a die holder 47, in which the die 15 of the pressing tool 13, which is only shown in FIG. I, can be received. The die holder 47 is operatively connected via guide columns 48 to an upper die guide 49, which in turn is assigned to a punch support 50. Another punch support 52 rests on side supports 51, which are anchored on the press table 4 via the clamping wedges 45.

Up to four hydraulic cylinders 14 cooperate with the die holder 47, the cylinder housings 53 of which have their abutment on the side supports 51.

In the intermediate part or the plunger support 52, a plunger extension 54 is vertically displaceable, which is in coupling connection with the counterpressure or pulling plunger 43 of the G-axis of the toggle press 2. An auxiliary hydraulic cylinder 16a is accommodated within the plunger extension 54 and actuates the auxiliary axis of the hydraulic press part 12 formed therefrom with its piston rod 17a. It is mainly used for core stamp movements (auxiliary movements).

Finally, a second auxiliary hydraulic cylinder 18 is provided in the punch support 50, which acts on the piston rod 19a and can be used as a second auxiliary axis for core punch movements and punch loading movements.

So that the hydraulic press part 12 achieves a high level of working accuracy with optimal operation, it is important that the position transducers indicated in FIGS. I and 4 for the X axis, 31 for the M axis, 32 for the Z axis and 33 for the Y axis directly, ie are connected directly to the press table 4 and to the press frame 5 or to the cylinder housing and the piston rod.

5 clearly shows that the hydraulic press part 12 with all press axes, namely the M press axis, the Z press axis and the Y press axis and the associated hydraulic cylinders 14, 16 and 18 forms a self-contained installation adapter, in which the ram extension 54 for the counterpressure or pull ram 43 is also integrated. The form-fitting coupling connection of the plunger extension 54 with the counterpressure plunger 43 takes place above the press table 4 of the toggle press 2 by means of a coupling part 55.

5 that the hydraulic cylinders 14, 16 and 18 are designed for the production of relatively short strokes, for example of 20 mm each, which correspond to only a fraction of the stroke of the toggle press 2, which between the top dead center and bottom dead center should be at least about 120 mm.

FIG. 6 of the drawing shows a working diagram of the hydraulic press system I, as was explained in detail above with reference to FIGS. I to 5.

Along the abscissa of the coordinate system, the angular range from 0 _° to 360 _{° of} a full rotation of the crank mechanism 11 serving to actuate the toggle lever system 6 is plotted in the diagram according to FIG. 6. Along the ordinate of the coordinate system is the stroke between the upper one Dead center OT and the bottom dead center UT are displayed, which is run by the main press ram forming the X axis of the hydromechanical press system I and consisting of the press table 4 and the press frame 5 with a full rotation of the crank mechanism 11.

The sine curve indicated by a solid line is the movement curve of the main press ram or the X axis of the toggle press 2. The horizontal dash-dotted line indicates that the M axis or die 15 in the pressing process shown their rest position remains.

The dotted line, which runs along the sine curve shown in full line, indicates the movement sequence of the Y press axis during the pressing process, while the dashed line indicates the movement path of the G press axis and the dash-dotted line the movement path of the Z. - Press axis reproduces.

Position I within the diagram represents the filling or feeding position of the pressing tool 13, in which the latter is fed with the powdery materials. Position 2 specifies the tool position in which the distribution of the filled materials is initiated. Position 3 corresponds to the distribution position of tool 13, while position 4 indicates the pressing position and position 5 represents its ejection position.

As has already been emphasized above, the X press axis of the toggle press 2 forms the main and leading axis for the hydromechanical press system I, i.e. the working movements of all press axes of the hydraulic press part, that is to say the M press axis, the Z press axis and the Y press axis thereof, are determined by the X press axis, but they are varied according to the different requirements by means of the assigned travel ratio value input units 29 can. The working movements of the hydraulic press part 12 are then controlled and regulated by means of the valve systems 26, 27 and 28 in accordance with the specifications of the travel ratio value input units 29.

The working movements G-press axis, on the other hand, are derived from the drive system of the toggle press 2, the cams 37 being designed as alternating curves which are given different outline shapes for the pull-off, ejection and counter-pressing techniques.

The path-time ratio for the movement of the main press ram of the toggle press 2 cannot be changed, however, and therefore advantageously forms the basis for the main or leading axis of the hydromechanical press system I.

The hydraulic press part 12 is preinstalled with respect to all of its hydraulic, electrical and electronic components so that it can be easily coupled and uncoupled by means of associated quick-action couplings for the energy supply and can be integrated into the control system of the toggle press 2.

If compacts are to be produced that have undercuts, then split molds must be used, because otherwise the compacts cannot be exposed. For this purpose, it is necessary to operate the hydromechanical press system I with a reverse press movement or repressing the return pressure. Here, the movement of the X-press axis is reduced after reaching its press position, while at the same time the Y-press axis is temporarily moved. During this movement process, the working pressure of the Y press axis is supported by the backward moving press axis. The compact can then be removed in the area of the die division after the pressing operation.

Claims (19)

1. Press, more especially for the production of pressed elements true to size from materials in powder form, having a press stand, in which are provided a press frame and a press table as main and guide axis, which are immovably connected to one another by a mechanical drive means, especially a toggle lever drive, and form a main press ram, characterised in that a hydraulic press part (12) with at least one additional pressing axis or with several additional pressing axes (M-pressing axis, Z-pressing axis and Y-pressing axis) is able to be installed before the main pressing ram (X-pressing axis) between press frame (5) and press table (4) of the mechanical press part (2), that the hydraulic press part (12) forms a self-contained built-in adapter for the mechanical press part (2), and that the working movement of each press shaft or axis of the hydraulic press part (12) can be controlled and regulated (22 to 33), dependent on travel and time (30), by the working movement of that main and guide shaft (X-pressing axis) of the mechanical press part (2) which consists of press frame (5) and press table (4).

2. Press according to claim 1, characterised in that the press shaft or shafts (M-press axis, Z-press axis and Y-press axis) of the hydraulic press part (12) have pressing paths differing in determinable manner from the main pressing axis (X-pressing axis) of the mechanical press part (2).

3. Press according to one of the claims 1 and 2, characterised in that each pressing axis (M-, Z-and Y-press axis) of the hydraulic press part (12) is coupled or can be coupled by way of an electric or electronic position sensor (30) with the main pressing axis (X-press axis) (22 to 33).

4. Press according to one of the claims 1 to 3, characterised in that the pressing axes (M-, Z- and Y-press axes) of the hydraulic press part (12), by interposition of an electronic path ratio-value indicating unit (29) designed as a CNC path control means, are coupled in a freely programmable manner with the path sensors (30) associated with the mechanical section (2) of the press.

5. Press according to one of the claims 1 to 4, characterised in that the hydraulic cylinders (14, 16, 18) of the different press axes or shafts (M-, Z-and Y-press axes) of the hydraulic section (12) of the press are each able to be acted upon by pressurising medium by way of their own control circuits (31, 26; 32, 27; 33, 28) and high-pressure pumps (22; 23; 24) and in this case each control or regulating circuit includes a relate travel-ratio value-input unit (29), in addition to the position sensor.

6. Press according to one of the claims 1 to 5, characterised in that the hydraulic cylinder (14) (M-pressing axis) of the hydraulic press section (12) is selectively adjustable by way of control and return pressure, the control pressure being regulatable up to 70 bar and the return pressure up to 350 bar, while the hydraulic cylinders (16 and 18) (Z- and Y-press axis) can be regulated by means of servo hydraulics up to 350 bar and advantageously the hydraulic cylinder (14) can at will be additionally regulated up to 350 bar by servo hydraulics.

7. Press according to one of claims 1 to 6, characterised in that each separate press axis (M-, Z- and Y-press axis) of the hydraulic press section (12) can be charged with up to 50% of the nominal pressing force of the mechanical press section (2).

8. Press according to one of the claims 1 to 7, characterised in that the hydraulic press part (12), by means of chucking wedges (45, 46), can be coupled mechanically and in formlocking manner, but so as to be easily releasable, with the press frame (5) and the press table (4) of the mechanical part (2) of the press (Fig. 5).

9. -Press according to one of the claims 1 to 8, characterised in that the hydraulic press part (12), with at least three pressing axes (W-, Z- and Y-pressing axis) forms the selfcontained fitting adapter for the mechanical part (2) of the press.

10. Press according to one of the claims 1 to 9, characterised in that the operating paths of the hydraulic cylinders (14, 16, 18) for the individual pressing axes (M-, Z- and Y-pressing axes) of the hydraulic press section (12) correspond to only a fraction of the travel of the press shaft (X-pressing axis) of the mechanical press section (2).

11. Press according to one of the claims 1 to 10, characterised in that the pressing axes (M-, Z- and Y-pressing axis) of the hydraulic part (12) or the press are able at will to move in the same direction as or opposite to the direction of movement of the pressing shaft or axis (X-pressing axis) of the mechanical press part (2).

12. Press according to one of the claims 1 to 11, characterised in that the mechanical part (2) of the press, for example, the press table (4), has associated therewith a press counter-ram (43) or press withdrawal ram (G-pressing axis), which is likewise able to be actuated by a mechanical drive means (36 to 42), advantageously a cam or like drive means (Figs. 2 and 3).

13. Press according to one of the claims 1 to 12, characterised in that the electric or electronic position sensor (30) for the control and regulation of the hydraulic press section (12) is arranged or fitted between the press frame (5) and the press table (4) of the mechanical press section (2), while additional electronic position sensors (31, 32, 33) for the selective position sensing are disposed on the different pressing shafts (W-, Z- and Y-pressing shafts) of the hydraulic press section (12) (Figs. 1 and 4).

14. Press according- to one of the claims 1 to 13, characterised in that the separate pressing shafts (M-, Z- and Y-pressing axes) of the hydraulic press section (12) are designed so that they can at will be locked in relation to one another or freed relatively to one another.

15. Press according to one of the claims 1 to 14, characterised in that the position sensors (31, 32, 33) of the hydraulic press section (12), serving for positions checking are directly associated with the piston and the cylinder housing of the associated hydraulic cylinders (14, 16, 18).

16. Press according to one of the claims 1 to 15, characterised in that the position sensors (31, 32, 33) of the hydraulic press section (12) correspond with the position sensor (30) of the mechanical press section (2) by way of the CNC path control (29) or respectively the related microprocessor.

17. Press according to one of the claims 1 to 16, characterised in that the Y-pressing axis, after reaching the pressing position or respectively the lower dead-centre point of the X-pressing axis, can be switched for opposite direction of movement or counter-pressing movement.

18. Method of operating the press according to one of the claims 1 to 17, characterised in that the mechanical pressing movement has superimposed thereon at least one hydraulic pressing movement and thereby the hydraulic pressing movement is controlled and/or regulated in direct and exclusive dependence on the mechanical pressing movement.

19. Method according to claim 18, characterised in that the speed of the hydraulic pressing movements is proportionally determined and/or influenced, dependent on travel, by the speed of the mechanical pressing movement.

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