DE102014105111A1 - Pressure control device and method for controlling a pressure to be output for a ceramic and / or metal powder press - Google Patents

Abstract

The invention relates to a pressure control device (11) and a method for controlling a pressure to be output for a ceramic and / or metal powder press. The pressure control device (11) has at least one drive cylinder (15) and at least two, in particular at least three or more further cylinders (18-23), and a piston carrier (24) with at least one drive piston (26) and at least two , in particular at least three or more further pistons (27-32), wherein the at least one drive piston (26) in the at least one drive cylinder (15) is arranged and the further piston (27-32) in each case in a cylinder chamber of the further cylinders (18-23) are arranged, and wherein a pressure (P18, P19) in at least a part of the cylinder chambers of the further cylinders (18, 23, 19, 22) is designed to be switched on and wegzuschaltbar.

Description

The invention relates to a pressure control device and a method for controlling a pressure to be issued for a ceramic and / or metal powder press.

In particular, ceramic and / or metal powder presses have a plurality of cylinders which comprise a press drive and / or components disposed thereon, e.g. Adjusting punch-carrying punch carrier or plates or a die receiving female die relative to each other. In particular, when pressing a low pressure to apply to a rapid traverse cylinder to adjust the components quickly and with little force to an introductory press position. Thereafter, one or more cylinders are each subjected to increasingly higher pressure in order to press the pressed material into a shaped body.

To provide different compression pressures and volumes, therefore, a pressure supply and pressure control device is often used which has a very large pressure source. It is disadvantageous that different volumes and pressures are needed in different phases during a press cycle, the pressure sources, e.g. However, a motor-pump unit must be dimensioned to the required maximum pressure and volume.

The pressure source can be a very large pump. The disadvantage, however, is that driving a pump is not sufficiently dynamic, because when reaching desired pressure levels due to control influences pressure peaks.

The pressure source can also be a constant pressure accumulator with a pressure to be dispensed, e.g. 300 bar. Limiting valves provide lower pressures as needed.

Can be used with correspondingly very high construction costs and high costs and multiple sources of pressure, i. several independent constant pressure pumps and / or constant pressure accumulator, which are connected in chronological succession to the pressure cylinder to be supplied with pressure.

In practice, therefore, only a very high pressure and a contrast lower pressure are provided for cost and space reasons and achieved further pressure levels required by the use of limiting valves. When pressures between such provided actual pressures are required, there is a high energy loss resulting from the difference between the actual pressure provided and the required target pressure.

As an alternative to constant-pressure pump systems, there are variable-pressure variable-rate control pumps, but for a given maximum power, pressure and volume are indirectly proportional because the product of pressure and volume is constant and corresponds to the installed hydraulic power. As a result, only a low delivery volume is available at high pressures required. This deficiency must be remedied in turn with a pressure accumulator and the associated and already described disadvantages or with correspondingly large-sized pressure sources.

In addition, such Druckbereitstellungs- and pressure control devices with pressures, such as are required in the field of ceramic and metal powder presses, very loud, so that extensive noise protection measures are to be taken.

The object of the invention is to provide a pressure control device and a method for controlling a pressure to be output for a ceramic and / or metal powder press such that a provision of different pressure levels is made possible with little constructive effort. In particular, a low, constantly pending primary pressure should be sufficient to provide different, higher secondary pressures. In particular, a section-wise constant volume flow on the primary side should lead to a substantial increase in energy efficiency at a constant low pressure level. In particular, a loss of energy in the overall system of pressure control device and the pressure-reducing device should be kept as low as possible, in particular reduced.

This object is achieved by a pressure control device having the features of patent claim 1 and a method having the features of patent claim 12. Advantageous embodiments are the subject of dependent claims.

Accordingly, a pressure control device for controlling a pressure to be output, in particular for a ceramic and / or metal powder press, comprising at least one drive cylinder and at least two, in particular at least three or more further cylinders, and a piston carrier with at least one drive piston and at least two, in particular at least three or more further pistons, wherein the at least one drive piston is arranged in the at least one drive cylinder and the other pistons each in a cylinder chamber of the other Cylinders are arranged, and wherein a pressure in at least one part of the cylinder chambers of the further cylinder is designed to be switched on and wegzuschaltbar.

In particular, in such an embodiment, a section-wise constant volume flow on the primary side at a constant low pressure level leads to a substantial increase in energy efficiency, because briefly required pressure or volume peaks are covered by this storage function.

An embodiment consists in a device in which in a first cylinder chamber on the drive piston, a drive pressure - in particular a within a tolerance of less than 2 to 3% fluctuating drive pressure - can be applied or applied. The larger with use of e.g. Constant pressure accumulator as a pressure source whose volume is in proportion to the volume of the pressure medium to be transported, the lower pressure fluctuations are up to a negligible for the pressure control purposes fluctuation.

One embodiment of this consists in a device in which the drive piston in an opposite second cylinder chamber of the drive cylinder ambient pressure or applied by several orders of magnitude lower pressure.

Advantageously, hardly or ideally no pressure is lost from this pressure source since, according to a preferred development, a pressure medium is merely moved back and forth between the pressure source and the first cylinder chamber of the drive cylinder.

An embodiment consists in a device which is designed such that a / the drive pressure to the at least one drive piston can be applied or applied and to the cylinder chambers of at least one or more of the other cylinders, a drive counter-pressure can be applied or applied.

The drive back pressure can be provided in particular by a further pressure source than the pressure source, which provides the drive pressure.

An embodiment thereof is a device configured to generate a drive force generated by the drive pressure and to generate a drive counterforce generated by the drive backpressure, the drive counterforce being larger than the drive force particularly in a first pressure state of the pressure to be output ,

In a basic position so the piston carrier is moved with the piston a piece of the cylinders and increases the volume of the cylinder chambers of the other cylinders, so that in the cylinder chambers sufficient pressure medium can be accommodated for subsequent operation of the pressure consumer, especially the press. After a pressure decrease cycle - in a press as a pressure consumer, in particular after a press cycle - the pressure control device is in particular again in the normal position or in a position between the basic position and the position of the first pressure state. Before a next pressure decrease cycle, new pressure medium is again pumped into the cylinder chambers. If one, e.g. the particular first pressure stage in a special pressure drop case is not needed, if necessary. Less pressure medium can be filled into the cylinder chambers or remain the piston carrier at the end of the cycle in a position not adjusted to the normal position.

The movement takes place up to a point at which either the pressurized medium under the drive pressure is too strongly compressed or a stop prevents further movement of the piston carrier with the piston from the cylinders beyond.

Such a stop may be constructive e.g. be formed by the outside on the piston carrier and the cylinder base or by a wall directed against the driving force in the first cylinder chamber of the drive cylinder.

The piston carrier with the pistons is preferably moved to its maximum possible stroke, d. H. except for the inner, the stroke limiting stop. This advantageously results in a maximum storage volume of the pressure medium and thus the maximum possible coverage of the short-term peak demand of the pressure medium within a press cycle.

In particular, a level of the set pressure of the drive pump, which provides the drive back pressure, to the effect matched to the applied drive pressure, that for this possible maximum stroke of the piston carrier, the force is sufficient.

Specifically, the preset pressure of the accumulator is chosen so that the resulting necessary drive pressure is in a low energy efficient range.

An embodiment consists in a device with at least one valve, in particular directional control valve, wherein such valves with the part of Cylinder chambers of the other cylinders are for deriving the pressure.

For switching off, the pressure or the pressure medium from these cylinder chambers is thus reduced in e.g. a discharge line and a container for the pressure medium derivable by the valves are switched by means of a control device in accordance with passage-through positions.

An embodiment consists in a device, wherein in a pressure line between the connection of at least one, in particular each of the first cylinder chambers of the further cylinder is inserted in each case a valve with a flow passage in the direction of only the connection for the pressure to be dispensed.

In the case of only two cylinder chambers, which can be switched independently by pressure, there is thus at least one such valve which prevents backflow of the pressure medium from the connection or the second cylinder chamber back in the direction of the first cylinder chamber or a pressure source supplying it. In the case of three pressure-technically independently switchable cylinder chambers, there are thus at least two such valves which prevent backflow of the pressure medium from the port or the third cylinder chamber back toward the first and second cylinder chambers or a pressure source supplying them. Particularly in the case of a leakage compensation pump connected to the connection, such a valve is connected downstream of the connection of the last cylinder chamber in the pressure line.

One embodiment consists in a device in which the further piston and the at least one drive piston are formed integrally with the piston carrier or fixedly connected to the piston carrier.

Verstellfest means in particular that during a movement of the piston carrier, the other piston and the drive piston all perform a rectified movement as the piston carrier.

According to a preferred development, the at least one drive cylinder and the at least two further cylinders are formed in a common cylinder housing. According to another embodiment, the drive cylinder and the cylinder can also be formed in a cylinder base, which has a plurality of separate cylinder housing. In such a case, however, the cylinder housings are at least in a pressurized state of their cylinder chambers arranged relative to each other adjustable or stationary.

One embodiment consists of a device which has at least one such additional cylinder per switchable pressure stage, wherein the pressure in all but one of the cylinder chambers of the other cylinder or in all but the cylinder chambers of a connected to a pressure step group further cylinder and switched off is designed.

One embodiment consists in a device in which a pump for compensating a loss of leakage is connected to a port for outputting the pressure to be output.

One embodiment consists in a device in which a part of the cylinder chambers of the other cylinder has different cross sections to each other.

As a result, different pressure attack actuating surfaces are formed, which is also exploitable for setting different pressure levels.

Accordingly, a method for controlling a pressure to be dispensed, in particular for a ceramic and / or metal powder press for pressing an at least powdered or granular pressed material, in which in a pressure control device with a piston carrier with at least one drive piston and at least two, in particular at least three or more further pistons in a first cylinder chamber of a drive cylinder, a drive pressure is applied to a drive piston is and a drive back pressure in cylinder chambers at least two further cylinders is set differently sized depending on a set pressure level of the pressure to be output.

The term pressure level is in particular equivalent to a certain pressure value to be set of the pressure to be dispensed.

One embodiment is that of the pressure level to be set differently many cylinder chambers of the other cylinders are switched off. The removal of surfaces which act opposite to the driving force increases the pressure to be delivered.

An embodiment consists in a device with a control device for performing such a method.

Can be used such a procedure and such a pressure control device particularly advantageous for providing a pressure with different pressure levels in a ceramic and / or metal powder press, the plurality of cylinders which, relative to one another, adjust a press drive and / or components arranged thereon, for example punch carriers or plates bearing pressing ram or plates or a die receiving female part. This is especially true when the cylinder (s) are / are subjected to different pressures in chronological succession. In principle, the use can also be used advantageously in other pressure consumers than ceramic and / or metal powder presses.

It is only necessary to provide a pressure source, which is preferably large in terms of volume, for the drive pressure, which is to be kept as constant as possible, in particular during operation. However, this pressure source only provides a lower pressure, for example of 50 bar. It is thus necessary to provide a drive pressure with a comparatively low pressure level, which is smaller, in particular smaller by more than a power, than the highest pressure required at the pressure consumer. Accordingly, the requirements for the stability of the pressure accumulator as such a pressure source and to a pump for maintaining the pressure therein are lower than in the case of a pressure accumulator for providing the maximum pressure requested by the pressure consumer.

In particular, by the pump, which has to apply the drive backpressure, to provide only a pressure which is on the order of the drive pressure or only slightly greater than the drive pressure. In particular, the maximum pressure to be provided by this pump is lower in comparison to the maximum required pressure to be output, in particular by more than an order of magnitude or decimal power is lower.

In particular, this pump, in that it only has to provide a constant preset pressure, can be carried out in a simpler design without pressure control. Corresponding constant pressure pumps offer, by design, above all advantages with respect to e.g. Volume, wear behavior and efficiency.

Can be achieved so the required energy consumption, since only a correspondingly low pump power is required. An initial estimate suggests that energy consumption could be reduced by 80%.

By using small-sized pumps, a reduction in the volume in their environment can be achieved, with a volume reduction of 20 dB should be achieved for the pressure supply of typical ceramic and / or metal powder presses according to first estimates. This reduces the requirements for noise protection.

An embodiment will be explained in more detail with reference to the drawing. The same reference numbers will be used in the various figures for the same components or functions. In particular, what applies to such components is what is described for the further figures. Show it:

1 schematically, components of a pressure control device for a ceramic and / or metal powder press in a preparation or first printing state;

2 the components according to 1 in a second printing condition;

3 the components according to 1 in a third printing condition;

4 the components according to 1 in a fourth printing condition; and

5 a pressure diagram of a pressure output by the pressure control device over a time course.

The 1 to 4 show a ceramic and / or metal powder press 1 which is a die 2 and from above and below into a die opening of the die 2 immerse the stamp 3 having. With the stamps 3 becomes a pressed material located in the die opening 4 made of ceramic and / or metallic powder and / or granules pressed into a structured shaped body. For adjusting at least one of the punches 3 and for pressing is a printing cylinder 5 , The printing cylinder 5 is via at least one pressure line 6 can be acted upon with pneumatic or preferably hydraulic pressure.

A pressure control device 11 is configured and controllable, to the pressure line 6 a print medium 37 , in particular hydraulic oil, with different pressure levels PA, PB, PC create, which exemplifies in 5 are sketched. Instead of the strongly schematically outlined press structure has such a press 1 Usually a plurality of pressure cylinders, which are driven with pressures of such different pressure levels PA, PB, PC. Accordingly, for example, at the pressure line 6 from also several branches or control / regulating or valve devices for different pressure consumers of the press 1 be educated.

To drive the pressure control device 11 and possibly also the press 1 serves a control device 7 in particular having a processor for driving various components and functions depending on software algorithms. The pressure control device 11 can be an independent component, but can also be in the press 1 be integrated.

The pressure control device 11 has a pressure control piston-cylinder arrangement 12 and a pressure source 13 on. The pressure source 13 is in particular a constant-pressure accumulator, which, for example, has a first constant pressure P0 in a bubble which presses on a second space with a hydraulic medium, in particular hydraulic oil. At an outlet of the pressure source 13 is a drive pressure P1 of the particular hydraulic oil to a pressure line 33 created.

The pressure control cylinder assembly 12 has a cylinder base, in particular a cylinder housing 14 on. The cylinder housing 14 has a variety of cylinders 15 . 18 - 23 or cylinder chambers 16 . 17 on. Instead of a single cylinder housing 14 In particular, however, such a cylinder base may also be formed from a plurality of separate cylinder components or cylinder housings. These are especially when they are actively used or switched are fixed relative to each other.

In addition, the pressure control cylinder assembly 12 a piston carrier 24 on, on which a multiplicity of drive pistons 26 and pistons 27 - 32 directly or via piston rods 25 is arranged. The piston carrier 24 is relative to the cylinder housing 14 arranged so adjustable that each of the drive piston 26 or piston 27 - 32 in a respective assigned to the cylinder 15 . 18 - 23 or its cylinder chambers 16 . 17 back and forth is adjustable. In particular, axes of movement of the drive piston run 26 or the piston 27 - 32 and axes of movement of the cylinders 15 . 18 - 23 overlapping each other or parallel to each other.

The drive piston 26 is particularly central to the piston carrier 24 arranged. The drive piston 26 is reciprocally adjustable arranged in one of the cylinders, which serves as a drive cylinder 15 serves. The drive piston 26 is about a piston rods 25 with the piston carrier 24 connected. The piston rods 25 leads through a first drive cylinder chamber 16 the drive cylinder 15 to the drive piston 26 , The pressure line 33 leads from the pressure source 13 in these first drive cylinder chambers 16 , This is due to the first drive cylinder chamber 16 always the drive pressure P1, which the piston carrier 24 together with the piston arranged thereon 27 - 32 in the direction of the cylinder base or in its cylinder 18 - 23 pushes in.

On the side of the drive piston 26 , which is the first drive cylinder chamber 16 is opposite, is in the drive cylinder 15 a second drive cylinder chamber 17 educated. This is outside the drive cylinder 15 open or through a pipe 59 connected to the outside. As a result, prevails in the second drive cylinder chamber 17 preferably an ambient pressure so that on the drive piston 26 active only the drive pressure P1 acts.

A driving force F0, which on the piston carrier 24 in the direction of the cylinder housing 14 acts, is accordingly dependent on the drive pressure P1 and a surface A0 of the drive piston 26 to which the drive pressure P1 in the first drive cylinder chamber 16 acts. We have F0 = P1 · A0. Under these conditions, a constant pressure source as the pressure source 13 and the second drive cylinder chamber open to ambient pressure 17 prevails a preferred or substantially constant driving pressure P1, for example, 150 bar. Variations in the drive pressure P1 depend in particular on the dimensioning of the pressure source 13 from.

Instead of a single central drive piston 26 It is also possible for a plurality of such drive pistons to be formed on or in the piston carrier or to be fastened together so as to be more adjustable. Such several drive pistons are then assigned corresponding cylinders in the cylinder base.

The remaining pistons 27 - 32 and the associated cylinder or cylinder chamber 18 - 23 are exemplary three pairs of groups of first piston shown in pairs 27 . 32 and cylinders 18 . 23 , second piston 28 . 31 and cylinders 19 . 22 and third piston 29 . 30 and cylinders 20 . 21 assigned. Such a grouping with two or more pairs of pistons and cylinders avoids jamming, but is not mandatory. In the cylinders 18 - 23 are the faces of these pistons 27 - 32 each cylinder chambers formed opposite, which via lines 34 . 35 . 36 can be acted upon with a hydraulic medium, in particular hydraulic oil under appropriate pressures P18, P19 and P20. For in these lines 34 . 35 . 36 prevailing pressures P18, P19, P20 and transferable forces are the corresponding piston or cylinder cross-sections effective areas A1, A2 and A3, if not other sources of pressure on these lines 34 . 35 . 36 be created.

These lines 34 . 30 . 36 lead into a pressure line 38 , The pressure line 38 leads either directly or via a connection 39 to a print consumer. At the connection 39 or in the downstream end of the pressure line 38 becomes a printing medium 37 , In particular a hydraulic medium, in particular hydraulic oil provided with a pressure P for a pressure consumer. Pressure consumer is in this case the ceramic and / or metal powder press 1 , At the other end leads the pressure line 38 to a pump 43 a hydraulic unit 45 , Under the connection 39 is if necessary. Only a single point to understand, which in a corresponding pressure line between the pressure control device 11 and the consumer or the press 1 is definable.

The pump 43 is in particular a constant pressure pump for low pressure and is formed, the pressure medium 37 from a container 44 with a drive back pressure P43 in the pressure line 38 to pump. Via the pressure line 38 and the wires 34 - 36 becomes the print medium 37 into the cylinder chambers of the cylinders 18 - 23 pumped. In the cylinder chambers thereby dominates the drive back pressure P43, which on the surfaces A0-A3 of the piston 27 - 32 acts. The pistons 27 - 32 therefore exert a drive counterforce F43 on the piston carrier 24 ,

The power of the pump P43 and / or a limiting pressure of a valve serving as a pressure limiter 46 is set so that the driving counterforce F43 is greater than the driving force F0. Additionally or alternatively, also the effective effective areas A0 of the drive piston or pistons 26 be dimensioned accordingly.

As a result, the cylinder chambers are initiated by an in 1 Outlined basic position with the print medium 37 filled so that the piston carrier 24 with the pistons 27 - 32 against the driving force F0 from the cylinders 18 - 23 up to a position according to 2 is partially pushed out. In this state, the pressure control device is located 11 in a first pressure state, in which at the high pressure side of the pressure line 38 the drive back pressure P43 as the output pressure P of a first pressure stage PA for the press 1 ready.

In the embodiment shown by way of example, the valve 46 with an input connection to the pump 43 and with an outlet port to a relief line 47 set. The relief line 47 preferably leads back into the container 44 to get out of the pressure line 38 discharged print medium 37 to transport back to them. The print medium 37 in the container 44 is in particular free of pressure compared to a low pressure L - in particular the ambient pressure than the low pressure L. The relief line 47 can optionally have a connection 48 for a low pressure side or for a return from the consumer, here the press 1 exhibit.

The relief line 47 or another such relief line is via a first switchable valve, in particular directional control valve 49 with the first of the wires 34 , which into the cylinder chambers of the first group of cylinders 18 . 23 leads, connected. The relief line 47 or another such relief line is via a second switchable valve, in particular directional control valve 50 with the second of the wires 35 , which into the cylinder chambers of the second group of cylinders 19 . 22 leads, connected. In the operating state according to 1 and 2 are both directional valves 49 . 50 closed, so no pressure medium 37 from the pipes 34 . 35 into the relief line 47 escapes.

In the pressure line 38 is between the connection of the first line 34 and the second line 35 a valve 40 , in particular non-return valve used. This valve 40 is switched or designed so that there is a pressure reduction or a return flow of the pressure medium 37 from the direction of the connection 39 for the pressure to be output P and from the second and third of the lines 35 . 36 in the direction of the first line 34 and in the direction of the pump 43 prevented.

In the pressure line 38 is between the connection of the second line 35 and the third line 36 a valve 41 , in particular non-return valve used. This valve 41 is switched or designed so that there is a pressure reduction or a return flow of the pressure medium 37 from the direction of the connection 39 for the pressure to be output P and from the third of the lines 35 . 36 towards the first and second of the lines 34 . 35 and in the direction of the pump 43 prevented.

In the pressure line 38 is between the connection of the third line 36 and the connection 39 for the output pressure P a valve 42 , in particular non-return valve used.

This valve 42 is switched or designed so that there is a pressure reduction or a return flow of the pressure medium 37 from the direction of the connection 39 in the direction of the lines 34 . 35 . 36 and in the direction of the pump 43 prevented.

In particular, connects the terminal 39 for the pressure to be output P and another pump 52 a pressure line 51 for a leakage compensation. The pump 52 is designed and / or controllable that at at the connection 39 In particular over a longer period applied pressure with this applied pressure in particular small amounts of the pressure medium in the pressure line 38 are pumpable. The pump 52 promotes the pressure medium 37 in particular from the container 44 , The pump 52 can be designed as a controllable or controllable pump and / or as a constant pressure pump with continuous pressure performance. In particular, in the pressure line 51 and / or in the area of the connection 39 for the output pressure P a valve 53 be used, which surplus as a limiting valve a derivative print media 37 or pressure in eg the container 44 back causes.

Advantageously, by such a pump 52 and pressure line 51 for a leakage compensation a leakage loss can be compensated, for example, in a the connection 39 downstream control valve 55 can arise. Such a control valve 55 can in turn also to the relief line 47 be connected.

For controlling and / or regulating the various valves 47 . 49 . 50 . 53 and pumps 43 . 52 and, if appropriate, further such components, in particular the control device 7 or a separate control device to the pressure control device 11 be provided or connected.

In the exemplary embodiment is in the normal position or when starting the system from the pressure source 13 at the pressure line 6 a drive pressure P1 of 150 bar, which is on the piston carrier 24 and its piston 27 - 32 the force acting in the direction of the cylinder base F0 with in particular F0 = P1 · A0 exerts. This results in the cylinder chambers and ultimately in the pressure line 38 at their connection 39 for the output pressure P, a pressure P18, P19, P20 with the first pressure stage PA equal to the drive back pressure P43 of the pump 43 , The pressure in this example can be determined according to P = F0 / (A1 + A2 + A3).

Ready for outputting the pressure P is the pressure control device 11 in particular when reaching the operating state according to 1 , In particular, in this operating state by continuous pumping by the pump 43 so much pressure medium 37 been pumped into the cylinder chambers, that a removal of the pressure medium 37 over the connection 39 for the output pressure P does not lead to a pressure drop.

At the exit 39 To provide the pressure P to be output with a second pressure stage PB, becomes the first of the directional control valves 49 switched to a passing state, as shown 3 outlined. As a result, flows in the cylinder chamber or the cylinder chambers of the first group of cylinders 18 . 23 located pressure medium 37 in or, if necessary, another discharge line 47 , In addition, flows - if the pump 43 continues to pump - through the pump 43 in the pressure line 38 pumped pressure medium 37 also through the multi-way valve 49 into the relief line 47 and in particular back into the container 44 , This is the cylinder 18 . 23 the first group of cylinders 18 . 23 on the pressure P18 of the relief line 47 , ie in particular pressure-free and in particular P43 = 0 bar applies.

The at the connection 39 applied pressure P now corresponds to a second pressure stage PB and can be determined in particular according to P = F0 / (A2 + A3). Thus, the entirety of the surfaces P 1, A 2, A 3 effective for the pressure P has been changed, in particular reduced, by switching off a part of the surface or surfaces A influencing the pressure P and the associated cylinder (s) 18 . 23 and the associated piston (s) 27 . 32 no longer affect the pressure P. In particular, the drive backpressure P43 is no longer effective.

At the exit 39 To provide the pressure to be output P with a third pressure level PC, in addition, the second of the directional control valves 50 switched to a passing state, as shown 4 outlined. As a result, also flows in the cylinder chamber or the cylinder chambers of the second group of cylinders 19 . 22 located pressure medium 37 in or, if necessary, another discharge line 47 , It could also - provided the pump 43 continues pumping and a valve 40 should still have letting pressure - through the pump 43 in the pressure line 38 pumped pressure medium 37 additionally through the second multiway valve 50 into the relief line 47 and in particular back into the container 44 flow. This is the cylinder 18 . 19 . 22 . 23 the first and the second group of cylinders 18 . 19 . 22 . 23 on the pressure of the relief line 47 , ie in particular pressure-free and in particular P18 = P19 = P43 = 0 bar. The at the connection 39 applied pressure P now corresponds to a third pressure level PC and can be determined in particular according to P19 = P = F0 / (A3). Thus, the totality of the surfaces A 2, A 3 effective for the pressure P has been changed, in particular reduced, by switching off a part of the surface or areas A influencing the pressure P and the associated cylinder (s) 19 . 22 and the associated piston (s) 28 . 31 no longer affect the pressure P.

5 shows an exemplary pressure curve of the pressure P to be output. According to some preferred embodiments, the pressure P should be at the port 39 connected pressure collector continuously increase and follow a setpoint pressure PS. It is provided at the connection 39 with time t but successively as actual pressure PI, the pressure P with increasingly higher pressure levels PA, PB, PC. It is advantageous to provide in particular three or more pressure levels PA-PC with such a pressure control device 11 in that with increasing number of pressure levels PA-PC an energy loss E at the print buyer, eg the press 1 can be reduced in a simple manner by eg pressure-reducing limit valves.

The pressure and force values and their relations to each other are given purely by way of example. In particular, the formulas are also adapted when the pressure control device 11 has more than three so controllable groups of cylinders and pistons.

In addition, constructive modifications between the various cylinders and pistons are feasible, such as e.g. different sized frontal or active for the pressure influencing piston surfaces or cylinder cross sections.

In particular, embodiments can be implemented in which, instead of the pumps for applying the drive counterpressure (P43) and for replacing the leakage loss, appropriately sized pressure accumulators, in particular constant pressure accumulators, are used. The pressure lost from these during operation into the pressure lines may then be e.g. be replaced by connected as needed einschaltbare or constantly pumping pumps. In essence, therefore, these pumps are in particular other sources of pressure.

In this sense, a pressure source for providing the drive backpressure can also be realized, whereby the drive pressure is also reduced by means of an energy loss, for example. a limiting valve is generated from this drive backpressure.

For use in the field of ceramic and / or metal powder presses especially pressure control devices with more than three pressure levels are advantageously used. For example, a pressure control device may be equipped with five such cylinder-piston groups having 5 pressure levels with e.g. Provide 50, 100, 150, 200 and 250 bar pressure to be dispensed. The finer tuning to particular pressures actually required, the energy loss can be further reduced.

LIST OF REFERENCE NUMBERS

1

Ceramic and / or metal powder press

2

die

3

stamp

4

pressed material

5

pressure cylinder

6

pressure line

7

control device

11

Pressure control device

12

Pressure control cylinder assembly

13

Pressure source, in particular constant pressure accumulator

14

cylinder housing

15

Drive cylinder

16

first drive cylinder chamber

17

second drive cylinder chamber

18

Cylinder or cylinder chamber

19

Cylinder or cylinder chamber

20

Cylinder or cylinder chamber

21

Cylinder or cylinder chamber

22

Cylinder or cylinder chamber

23

Cylinder or cylinder chamber

24

piston carrier

25

piston rod

26

drive piston

27

piston

28

piston

29

piston

30

piston

31

piston

32

piston

33

pressure line

34

management

35

management

36

management

37

print media

38

Pressure line as a high pressure line

39

Connection for high pressure or high pressure side

40

Valve, in particular check valve

41

Valve, in particular check valve

42

Valve, in particular check valve

43

Pump, in particular constant pressure pump for low pressure

44

container

45

hydraulic power unit

46

Valve as a pressure relief valve

47

Relief line as low pressure line

48

optional connection for relief line

49

first way valve

50

second way valve

51

Pressure line for leakage compensation

52

Pump, in particular flow-leakage equalization pump

53

Valve as a pressure relief valve

54

management

59

Lead to the outside

A0

Surface of the drive piston

A1

Area of the first cylinder 18 . 23

A2

Area second cylinder 19 . 22

A3

Surface of third cylinder 20 . 21

e

energy loss

F0

driving force

F43

Drive counterforce

L

low pressure

P

Pressure on high pressure side

P0

Pressure of the pressure source

P1

Drive pressure in pressure line from pressure source

P18

Pressure in first cylinders 18 . 23

P19

Pressure in second cylinders 19 . 22

P20

Pressure in third cylinders 20 . 21

P43

Drive back pressure

PA

first pressure level

PB

second pressure level

PC

third pressure level

PI

actual pressure

PS

set pressure

t

Time

Claims (14)

Pressure control device for controlling a pressure (P) for a ceramic and / or metal powder press ( 1 ), comprising - at least one drive cylinder ( 15 ) and at least two, in particular at least three or more further cylinders ( 18 - 23 ), and - a piston carrier ( 24 ) with at least one drive piston ( 26 ) and at least two, in particular at least three or more further pistons ( 27 - 32 ), Wherein the at least one drive piston ( 26 ) in the at least one drive cylinder ( 15 ) is arranged and the other piston ( 27 - 32 ) in each case in a cylinder chamber that of the further cylinder ( 18 - 23 ), wherein - a pressure (P18; P19) in at least a part of the cylinder chambers of the further cylinders ( 18 . 23 ; 19 . 22 ) is designed to be switched on and off. Apparatus according to claim 1, wherein in a first cylinder chamber ( 16 ) on the drive piston ( 25 ) a drive pressure (P1) - in particular a within a tolerance of less than 2 to 3% fluctuating drive pressure (P1) - can be applied or applied. Device according to Claim 2, in which on the drive piston ( 25 ) in an opposing second cylinder chamber ( 17 ) of the drive cylinder ( 15 ) Ambient pressure or applied by several orders of magnitude lower pressure. Device according to any preceding claim, which is designed such that - a drive pressure (P1) on the at least one drive piston ( 25 ) can be applied or abutting and - on the cylinder chambers of at least one or more of the further cylinders ( 18 . 23 ; 19 . 22 ) a drive back pressure (P43) can be applied or applied.  An apparatus according to claim 4, which is configured to generate a driving force (F0) generated by the driving pressure (P1) and generate a driving reaction force (F43) generated by the driving reaction pressure (P43), the driving reaction force (F43) in particular in a first pressure state of the pressure to be output (P) is greater than the driving force (F0). Device according to any preceding claim with at least one valve, in particular a directional control valve ( 49 . 50 ), such valves ( 49 . 50 ) with the part of the cylinder chambers of the further cylinders ( 18 . 23 ; 19 . 22 ) are connected to derive the pressure (P18; P19). Device according to any preceding claim, wherein in a pressure line ( 38 ) between the connection of at least one, in particular each of the first cylinder chambers of the further cylinder ( 18 . 23 ; 19 . 22 ) one valve each ( 40 . 41 . 42 ) with a flow passage in the direction of only the connection ( 39 ) is used for the output pressure (P). Device according to any preceding claim, wherein the further pistons ( 27 - 32 ) and the at least one drive piston ( 26 ) in one piece with the piston carrier ( 24 ) trained or adjustable with the piston carrier ( 24 ) are connected. Device according to any preceding claim, comprising at least one such additional cylinder per switchable pressure stage (PA, PB, PC) ( 18 . 23 ; 19 . 22 ; 20 . 21 ), wherein the pressure (P18; P19) in all but one of the cylinder chambers of the further cylinders or in all but the cylinder chambers is interconnected by a further cylinder (FIG. 18 . 23 ; 19 . 22 ) is designed to be switched on and off. Device according to any preceding claim, wherein a pump ( 52 ) to compensate for leakage loss to a port ( 39 ) for outputting the pressure to be output ( 39 ) connected. Device according to one of the preceding claims, in which a part of the cylinder chambers of the further cylinders has mutually different cross-sections. Method for controlling a pressure (P) to be output for a ceramic and / or metal powder press ( 1 ) for pressing an at least powdered or granular pressed material ( 4 ), in which in a pressure control device ( 11 ) with a piston carrier ( 24 ) with at least one drive piston ( 26 ) and at least two, in particular at least three or more further pistons ( 27 - 32 ) - in a first cylinder chamber ( 16 ) of a drive cylinder ( 15 ) a drive pressure (P1) to a drive piston ( 25 ) is or is applied and - a drive backpressure (P18, P19, P20; P43) in cylinder chambers of at least two further cylinders ( 18 . 21 ; 19 . 22 ; 20 . 23 ) is set differently sized depending on a pressure level to be set (PA, PB, PC) of the pressure to be output (P). Method according to Claim 12, in which the number of cylinder chambers of the further cylinders (PA, PB, PC) to be set is different ( 18 . 21 ; 19 . 22 ) are switched off. Device according to one of claims 1 to 11 with a control device ( 7 ) for carrying out a method according to one of claims 12 or 13.

Images