AT526711A1 - Hydraulic drive unit for a forming machine - Google Patents

Abstract

Shaping machine, in particular injection molding machine, with a hydraulic drive unit comprising a piston (4) arranged in a cylinder (3) so as to be linearly displaceable and a pressure chamber (5) in the cylinder (3) delimited by the piston (4), at least one pressure sensor (6) which is designed to detect a signal characteristic of the pressure in the pressure chamber (5), and a computing unit (7) which is signal-connected to the at least one pressure sensor (6) in order to receive the characteristic signal, wherein the computing unit (7) is designed to determine a kinematic parameter, preferably a position and/or a change in position, of the piston (4) on the basis of the signal characteristic of the pressure in the pressure chamber (5), wherein the pressure chamber (5) cooperates with a constant pressure medium mass, preferably hydraulic fluid mass, at least during the measurement of the characteristic signal.

Description

The present invention relates to a hydraulic drive unit for a forming machine with the features of the preamble of claim 1, a forming machine with such a hydraulic drive unit, a method for monitoring a hydraulic drive unit and a computer program product for monitoring a hydraulic

drive unit.

Forming machines can be understood as injection molding machines, transfer presses, presses and the like. Forming machines in which the plasticized molding compound is fed into an open mold are also quite

conceivable.

In the following, the state of the art will be outlined using an injection molding machine as an example. The same applies in general

for forming machines.

Generic hydraulic drive units for a

Injection molding machine include

- a piston arranged in a cylinder so as to be linearly displaceable and a pressure chamber in the cylinder delimited by the piston,

- at least one pressure sensor which is designed to detect a signal characteristic of the pressure in the chamber and

- a computing unit which is designed to receive the characteristic signal with the at least one sensor

In injection molding machines, drive movements are often controlled by

hydraulic drive units, which are usually

Hydraulic cylinders can be realized.

For this purpose, it is almost always necessary to determine in some way the position of the object moved by the hydraulic drive unit.

injection molding machine part.

For simple applications, it is usually sufficient to detect the end position of a movement axis via limit switches, whereby a limit switch can be used to determine exactly one position (usually the end position) of the injection molding machine part or the

drive unit is detected.

However, this only allows two functions to be implemented and monitored: on the one hand, it can be determined whether the injection molding machine part has reached a certain position and, on the other hand, whether the injection molding machine part has

ongoing monitoring remains in this position.

Such limit switches usually have to be mounted externally and are usually connected to the moving injection molding machine part

operated.

However, for many movements it is necessary to detect and monitor the constant and accurate knowledge of the absolute position, whereby the state of the art usually

different types of displacement sensors are known.

The following are measured using appropriate displacement sensors:

Feedback given to an injection molding machine control

and/or the following options for the injection molding machine

created:

- reaching a desired target position,

- Monitoring of specific positions,

- Speed regulation and/or control depending on a position, and

- Force regulation and/or control depending on the position.

Typically, such systems can be used to create clean acceleration and/or deceleration profiles as well as precise

Realize positions.

In most cases, linear position sensors must have sensor elements arranged parallel to the moving injection molding machine part (or drive unit) and over the entire length of movement in order to detect the position.

can.

However, corresponding position measuring systems are complex to install and involve high costs due to the high

Manufacturing costs and material costs are associated with this.

A further disadvantage is that corresponding position measuring systems require space for corresponding hydraulic drive units and are therefore often difficult to access in even small installation spaces, which means

they are difficult to assemble, disassemble and maintain.

In addition, these position measuring systems, which are arranged externally on the hydraulic drive units, are exposed to environmental influences, which means that the very precise measuring systems in particular are at an increased risk of damage

are exposed.

The object of the present invention is to provide a hydraulic drive unit which enables a simpler detection of a kinematic parameter of the hydraulic drive unit and/or requires less space and/or requires less maintenance, installation or dismantling work and/or is easier to manufacture and/or enables a kinematic parameter detection of the hydraulic drive unit by means of fewer components.

drive unit enables.

This object is achieved according to the invention by a hydraulic drive unit for a forming machine with the features of claim 1, a forming machine with such a hydraulic drive unit, a method for monitoring a hydraulic drive unit with the features of claim 16 and a computer program product for monitoring a hydraulic drive unit with the

Features of claim 17.

According to the invention, a hydraulic drive unit for a forming machine, in particular an injection molding machine, comprises the following:

- a piston arranged in a cylinder so as to be linearly displaceable and a piston chamber in the cylinder delimited by the piston,

- at least one pressure sensor which is designed to detect a signal characteristic of the pressure in the pressure chamber and

- a computing unit which is signal-connected to the at least one sensor for receiving the characteristic signal,

wherein the computing unit is designed to, on the basis of the

for the pressure in the pressure chamber characteristic signal

a kinematic parameter, preferably a position

and/or a change in position of the piston.

When the piston changes its position, the volume of the pressure chamber formed by the piston and the cylinder is changed, resulting in a change in the pressure of a pressure medium mass, fluid and/or hydraulic oil present in the pressure chamber. This change in pressure and the known behavior of the pressure medium present in the pressure chamber

Pressure media mass, fluids and/or hydraulic oil (e.g.

of compressibility) can be used to vary the pressure

Change in volume can be calculated.

Since the piston and the cylinder have known geometric dimensions, a linear displacement of the piston can be calculated taking into account the change in volume, whereby the kinematic parameter, preferably a position and/or a change in position, of the piston can be calculated by the computing unit.

can be determined.

It is therefore no longer necessary to provide position measuring systems, limit switches or similar sensors to record a kinematic parameter of the piston, since only the arrangement of a pressure sensor on or in the

Pressure chamber in which the kinematic parameters can be calculated.

This has the enormous advantage that significantly fewer parts, components or modules of the sensor system are required to determine the kinematic parameters of the piston, which not only reduces costs, but also the effort of assembly, disassembly and/or

Maintenance.

Furthermore, an advantage is created in that the installation space can be reduced considerably, since no separate sensors are arranged on the hydraulic drive unit.

must become.

A pressure sensor can be integrated and/or screwed into the hydraulic drive unit, which also protects the pressure sensor from environmental influences

and is not exposed to external damage.

The pressure in the pressure chamber is therefore particularly preferred

measured directly.

A hydraulic medium may be present in the pressure chamber, the pressure of which is measured by means of the pressure sensor. In other embodiments, a gas or another compressible fluid may be present in the pressure chamber, the pressure of which is detected by means of the pressure sensor (for example in embodiments where the pressure chamber itself is a

integrated hydraulic accumulator).

A device according to the invention and a method according to the invention can be used in already known embodiments of the prior art, as described for example in the introduction to the description,

are used and installed later.

Forming machines can be understood as injection molding machines, transfer presses, presses and the like. Forming machines in which the plasticized molding compound is fed into an open mold are also quite

conceivable.

The computing unit can be physically part of the hydraulic drive unit or connected to the hydraulic drive unit via a remote data transmission connection.

drive unit. The computing unit could in the latter case be a computer server or a set of computers (distributed

computing) can be realized.

The same applies to a control or regulating device of a

forming machine.

7739

Advantageous embodiments are based on the dependent

Claims defined.

It can be provided that the pressure chamber is filled with a constant pressure medium mass, preferably

hydraulic fluid mass and/or a gas.

It can be provided that the pressure medium mass is a hydraulic fluid mass, preferably a hydraulic oil, or also a gas mass (for example nitrogen, air or

other gases) are used.

Preferably, it can be provided that at least during the measurement of the characteristic signal the pressure chamber in the cylinder is closed and preferably a constant

Includes print media mass.

It can be provided that during the measurement of the characteristic signal the pressure chamber is connected to a hydraulic accumulator via a connecting line, preferably whereby a constant pressure medium mass is passed through the pressure chamber, the connecting line and the hydraulic accumulator

is included.

Thus, it can preferably be provided that during the measurement of the characteristic signal, a pressure loading or pressure relief of a precisely defined pressure medium mass is carried out, so that in a simple manner the volume variation of the pressure medium mass and thus a kinematic parameter of the

piston can be determined.

It could of course also be intended that the pressure chamber cooperates with a non-constant pressure medium mass, whereby the kinematic parameter can still be determined by precisely defining the system, whereby, however, the variations of the system can be determined through complex processes due to flow conditions for the pressure medium mass (for example, pressure variation taking into account passage cross sections and

flow velocities) can be determined.

Also versions in which reference pressures for defined kinematic parameters are first determined and stored, whereby the computing unit uses the corresponding stored kinematic parameter for a measured pressure,

are quite conceivable.

However, it can be particularly preferably provided that the pressure chamber is connected to a hydraulic accumulator, for example a bladder accumulator, whereby the pressure chamber and the hydraulic accumulator (of course together with the connecting line of these) inject a constant pressure medium mass, whereby in the event of a pressure variation of the pressure medium mass, taking into account a compression behavior of the pressure medium mass, a volume change and thus a kinematic parameter of the

piston can be deduced.

By providing a hydraulic accumulator, in particular a bladder accumulator, the compression behavior of the system can be influenced, whereby, for example, when using hydraulic fluid, the limited compression capacity of the fluid can be expanded to the extent that larger volume changes in the pressure chamber are permitted by diversion into the hydraulic accumulator, so that the method according to the invention and/or the

Device also for example for hydraulic cylinders with

high freedom of movement - drive movements - used

can be.

It can be provided that the computing unit is designed to determine the kinematic parameter by means of a relationship with the pressure stored in the computing unit, preferably taking into account a

stored compression behavior of the drive unit.

The compression behavior of the drive unit can affect the compressibility of the printing media mass, alternatively or additionally the geometric dimensions of the volumes in which the printing media mass is enclosed,

take into account.

If a hydraulic accumulator is provided, the compression behavior, the compression ratio of the system between two measurements and/or the back pressure of the hydraulic accumulator in the compression behavior of the drive unit can also

be taken into account.

It can be provided that the drive unit has a hydraulic accumulator, preferably a bladder accumulator and/or diaphragm accumulator, particularly preferably with variable

compressor ratio and/or variable back pressure.

It can be provided that the hydraulic accumulator is designed as a mechanical, preferably spring-operated, and/or

fluid-operated hydraulic accumulator.

A fluid-operated hydraulic accumulator (for example a bladder accumulator) can preferably use a gas (particularly preferably nitrogen, air or other gases) as the actuating medium.

exhibit.

Preferably, it can be provided that the piston pushes the cylinder into the (first) pressure chamber and a second

Pressure chamber divided.

It can be provided that the drive unit has a pressure source, in particular at least one pump, preferably which pressure source is connected or connectable to the second pressure source in order to supply the second pressure chamber with

to apply pressure.

It can be provided that the pressure source is connected to the second pressure chamber via a valve, preferably which valve is controlled by a control or regulating device

can be controlled or regulated.

It can be provided that the computing unit is connected in a signal-connected manner to a control or regulating device of the pressure source and/or is designed as an integral component of the control or regulating device, wherein the kinematic parameter is used by the control or regulating device for controlling or regulating the pressure source as an actual value

can be used.

It can be provided that the cylinder with the piston arranged therein is designed as a double-acting piston-cylinder unit

is trained.

Preferably, the pressure chamber can be designed as a rod-side chamber of a piston-cylinder unit

is trained.

Furthermore, protection is sought for a closing unit for a forming machine with at least one hydraulic drive unit according to the invention, preferably wherein the

at least one drive unit for driving a

Locking nut against a spar and/or as

Pressure cushion designed to build up closing force.

Protection is also sought for a forming machine, in particular an injection moulding machine, with at least one

hydraulic drive unit according to the invention.

Furthermore, protection is sought for a method for monitoring a hydraulic drive unit, preferably a hydraulic drive unit according to the invention, which hydraulic drive unit comprises a piston arranged in a cylinder so as to be linearly displaceable and a pressure chamber delimited by the piston in the cylinder, wherein a pressure in the pressure chamber is measured and via the pressure, preferably a determined pressure change, a kinematic parameter, in particular a position and/or a position change,

of the piston is detected.

Protection is also sought for a computer program product

for monitoring a hydraulic drive unit,

preferably a hydraulic

Drive unit comprising instructions that assist a computer in

Execution of the program to perform the following

Steps taken:

- Receiving a characteristic signal for a pressure in a pressure chamber and

- Determining a kinematic parameter, preferably a position and/or a change in position, of a piston of the pressure chamber on the basis of the pressure in the

Pressure chamber characteristic signal.

Further advantages and details of the invention emerge from the figures and the associated figure description.

This shows

Fig. 1 shows a first embodiment of a drive unit according to the invention, Fig. 2 shows a second embodiment of a drive unit according to the invention, Fig. 3 shows a third embodiment of a drive unit according to the invention, Fig. 4 shows a fourth embodiment of a drive unit according to the invention, Fig. 5 shows a fifth embodiment of a drive unit according to the invention, Fig. 6 shows an embodiment of a shaping machine and

Fig. 7 shows an embodiment of a closing unit.

The embodiment of a hydraulic drive unit 1 shown in Fig. 1 has a piston 4 arranged in a cylinder 3 so as to be linearly displaceable, whereby the piston 4 divides the cylinder 3 into a pressure chamber 5 and a

second pressure chamber 10.

Such a cylinder (3) - piston (4) arrangement is also

referred to as a double-acting piston-cylinder unit.

In order to supply the pressure chambers 5, 10 with a pressure medium mass, preferably a hydraulic fluid, these are connected via the connecting lines to the valve 13

tied together.

The valve 13 is designed, for example, as a 4/3-way valve, which is controlled by a control or regulating device 14

can be switched between the individual valve positions.

The valve 13 is designed to connect the pressure chambers 5, 10 optionally to the pressure source 11 or the tank 18 in order to optionally apply a pressure to the pressure chamber 5 or the pressure chamber 10 and/or to

Pressure media mass to be drained into the tank 18.

The pressure source 11 of this embodiment is formed by a pump 12, which is driven by a motor drive unit, wherein the drive unit can be controlled or regulated by the control or regulating device 14.

is adjustable.

The control or regulating device 14 further comprises a computing unit 7, which as an integral component of the control or regulating device 14 of the hydraulic

Drive unit 1 is designed.

The signal-conducting connections of the control or regulating device 14 with the individual components of the hydraulic drive unit 1 are shown in Fig. 1 as

shown by dashed lines.

The computing unit 7 is connected to the pressure sensor 6 in a signal-conducting manner (shown by the dashed line), whereby a characteristic signal for a pressure present in the pressure chamber 5 can be detected by the pressure sensor 6 and transmitted to the control device 7 via the signal-conducting connection

can be supplied.

Furthermore, a valve 17 is provided, which is designed as a shut-off valve and via which the pressure chamber 5

can be locked.

In order to carry out a measurement of a kinematic parameter of the piston 4, the pressure chamber 5 can be shut off via the valve 17 during the movement of the piston 4 and pressure medium mass can be supplied to the pressure chamber 10 via the valve 13 with the aid of the pressure source 11, whereby a higher pressure is created in the pressure chamber 10 compared to the

Pressure chamber 5 can be built up.

Alternatively or additionally, the piston 4 can of course also be moved via a machine part which is

the piston rod is connected to the piston 4.

As a result of the increasing pressure in the pressure chamber 10, the piston 4 is moved in the direction of the pressure chamber 5, whereby the closed pressure chamber 5 - more precisely: the constant pressure medium mass which is present in the pressure chamber 5 -

is compressed and the pressure in the pressure chamber 5 increases.

This pressure increase in the pressure chamber 5 can be fed to the computing unit 7 as a characteristic signal via the pressure sensor 6, whereby the computing unit 7 can determine a kinematic parameter, preferably a position and/or a change in position, of the piston 4 on the basis of the signal characteristic of the pressure in the pressure chamber 5.

In the same way, a kinematic

Parameters for piston 4 determined at a pressure drop

become.

This determination and/or calculation of the kinematic parameter of the piston 4 can be carried out by calculating the stroke volume, whereby the compression volume AVx is determined by the following formula via the pressure variation Ap and the

Initial volume Vo of the pressure chamber 5 can be calculated.

1 AV = 57 Vo: Ap

K Compression modulus of the pressure media mass Vo Output volume in the pressure chamber

AV compression volume of the pressure chamber

Ap pressure variation in the pressure chamber

The compression modulus K, which is also required in the formula, is a dependent quantity of the printing media mass and can be determined from tests and/or data sheets of the printing media mass

(e.g. the hydraulic fluid).

Subsequently, a change in the position of the piston 4 can be calculated using the compression volume AVx and the known geometrical dimensions of the piston 4 and/or the cylinder 3 and/or the pressure chamber 5, whereby, taking into account the initial position of the piston 4,

an instantaneous position of the piston 4 can be determined.

It can be provided that the computing unit 7 transfers the determined kinematic parameter of the piston 4 to the control or regulating device 14, wherein the control or regulating device 14 uses the kinematic parameter of the piston 4 as the actual size of the piston 4 in the control or regulating of the valve 13, the valve 17 and/or the pressure source 11, so that an adjustment of the

Piston 4 can be moved to a desired position.

Of course, this approach can also be applied to a

Speed and/or acceleration of piston 4.

Alternatively or additionally, it can also be provided that the determination of the kinematic parameter of the piston 4 is carried out via a calibration process, whereby firstly the position of the piston 4 is measured at different pressures in the pressure chamber 5 and, for example, a reference curve for the kinematic parameter of the piston 4 is determined as a function of a pressure in the pressure chamber 5 (and

a starting position of the piston 4).

Subsequently, as previously explained, a pressure can be measured via the pressure chamber 10 when the pressure chamber 5 is closed and, taking into account the measured pressure in the pressure chamber 5, a kinematic parameter for the piston 4

can be determined using the calibrated reference curve.

Due to the limited compressibility of common pressure media masses, only limited changes in the position of the piston 4 can be determined in the embodiment of Fig. 1, whereby only smaller strokes of the piston 4 can be determined via the pressure sensor 6 and the computing unit 7 by compressing the pressure chamber 5.

can.

However, in order to be able to determine larger travel distances of the piston 4, the procedure can be carried out several times in succession, whereby several kinematic parameters of the piston 4 are measured and calculated one after the other.

if necessary.

However, it can also be provided that the compressibility of the system is increased by connecting the pressure chamber 5 to a

Hydraulic accumulator 9 is increased, which also significantly

larger travel distances and strokes of the piston 4 can be determined

can.

Such embodiments are shown in Figures 2 and 3

shown.

In these embodiments, a pressure medium mass of a pressure source 11 can be supplied to the second pressure chamber 10 via a valve 13, whereby the pressure chamber 5 can be shut off during this time and thus a constant pressure medium mass can be maintained during the measurement with the hydraulic accumulator.

9 and the connecting line 8.

A hydraulic accumulator 9 of this or a similar type may be provided in some embodiments anyway,

for example to save energy through recuperation.

If the hydraulic accumulator 9 is designed, for example, as a bladder accumulator 10 (as shown in Fig. 2 or 3), the compression behavior can be varied considerably by a suitable choice of the counter pressure in the bladder accumulator 10, whereby higher compression volumes AV«x are also made possible in order to achieve larger

To detect position changes of piston 4.

The hydraulic accumulator 9 shown in Figures 2 and 3 is designed as a fluid-operated bladder accumulator 10, which uses a gas (for example nitrogen, air

or other gases).

The determination of the kinematic parameter in the piston 4 by the computing unit 7 can again - as previously described - be carried out via a previous calibration and determination of a reference curve or also by a

Calculation of the compression volume, whereby the

Embodiments of Fig. 2 and 3 the following formula can be used to determine not only the compressibility

the print media mass, but of the entire system

consider: n[69”- G9' Pı P2

K Ca n polytropic exponent % effective gas volume of the hydraulic accumulator AV compression volume Do gas filling pressure of the hydraulic accumulator 1 pressure at the start of the measurement in the pressure chamber 5 P2 pressure at the end of the measurement in the pressure chamber 5 Ca correction factor for adiabatic change of state

For the present case (in the case of adiabatic

Changes of state) is considered as polytropic exponent = 1.4.

The compressibility of the hydraulic fluid is negligible due to its small size and was taken into account in the calculation

not taken into account.

The embodiments of a hydraulic drive unit 1 explained by Figures 1 to 3 can, for example, be used as a hydraulic drive unit 1 for individual movements in a forming machine 2, preferably a

Injection molding machine. Preferably, an embodiment of a

hydraulic drive unit 1 according to the invention for

Driving a locking nut 19 against a beam 15

and/or as a pressure pad 20 for building up the closing force at a

Locking unit 16 can be used.

Fig. 4 shows a fourth embodiment of a hydraulic drive unit 1, which has a mechanically operated hydraulic accumulator 9, wherein the counter pressure via the spring element 33 (suitable choice of the spring element 33)

can be varied and/or adjusted.

The remaining features of the embodiment of Fig. 4

essentially correspond to those in Fig. 2.

Fig. 5 shows a fifth embodiment of a hydraulic drive unit 1, wherein the pressure chamber 5 is integrated into the piston-cylinder unit and

forms a hydraulic accumulator.

The pressure medium in the pressure chamber 5 can, for example, be

Nitrogen, air or another gas.

When the pressure medium in the pressure chamber 5 is compressed, a kinematic parameter can be determined taking into account the compressibility of the pressure medium and the pressure in the pressure chamber 5 (which can be determined via the pressure sensor 6).

of the piston 4 can be determined.

The remaining features essentially correspond to those

of Fig. 3.

The molding machine 2 shown as an example in Fig. 6 is an injection molding machine and has an injection unit 21 and a clamping unit 16, which are arranged together on a machine frame 22. The machine frame 22

could alternatively be designed in several parts.

The clamping unit 16 has a fixed mold clamping plate 23 and a relatively displaceable

movable mold clamping plate 24.

Alternatively, versions with a front plate 21 are also possible. Such locking units are also

referred to as three-platen clamping units.

The movable mold clamping plate 24 can be moved relative to the machine frame 22 via a closing drive (not shown here). The closing drive and the closing unit 16 are described in more detail by an exemplary embodiment in Fig. 6.

explained.

On the fixed mold clamping plate 23 and the movable mold clamping plate 24, mold halves of a mold

26 can be clamped or mounted (shown in dashed lines).

The fixed mold clamping plate 23 and the movable mold clamping plate 24 are connected to each other by the bars 15

stored and managed.

The mold 25 shown closed in Fig. 6 has at least one cavity. An injection channel leads to the cavity, through which a plasticized mass of the

Plasticizing unit 26 can be fed.

Fig. 6 shows a molding machine 2 with an injection unit 21, wherein the injection unit 21 shown in this embodiment has an injection screw, which is also used for plasticizing a

material is used.

The injection screw is arranged axially in the mass cylinder 27 along

mounted so as to be movable along a longitudinal axis.

21739

These movements are represented schematically

Drive unit 28 driven.

Preferably, this drive unit 28 comprises a hydraulic rotary drive for the rotary movement and a linear

hydraulic drive for the axial injection movement.

The plasticizing unit 26 (and thus the injection unit 21) is connected to the central control or regulating device 14 in

signaling connection.

The central control or regulating device 14 can therefore simultaneously control the control or regulating device 14 of the

Hydraulic system 1.

In alternative embodiments, the control or regulating device 14 of the hydraulic system 1 and the

Forming machine designed separately.

Analogously, the computing unit 7 can be operated separately or integrally with the

Control or regulating device 14 may be designed.

From the central control or regulating device 14, control commands are sent, for example, to the plasticizing unit 26, the

injection unit 21 or to the closing unit 16.

The central control or regulating device 14 can be connected to an operating unit 29 and/or a display device 30 via a signal-conducting connection or can be an integral

be part of such a control unit 29.

The computing unit 7 can be signal-connected to the central

Control or regulating device 14 of the forming machine 2

and/or as an integral part of the central control

or control device 14.

Fig. 7 shows a side view of a clamping unit 16 of a forming machine 2 - in this case a

Injection molding machine - shown.

The clamping unit 16 of the embodiment is again designed as a two-plate clamping unit, wherein a movable mold clamping plate 24 can be moved linearly on the machine frame 22 relative to a fixed mold clamping plate 23.

is.

To implement this linear movement of the movable mold clamping plate 24, on the one hand the rapid stroke drive 31 and

on the other hand, the pressure pads 20 are provided.

In the following, the usual movement sequence of such a closing unit 16 will be explained using a closing movement. The same applies in the opposite direction for the

Opening the locking unit 16.

Thus, two mold halves of a mold 25 (not shown in this figure for reasons of clarity), which are arranged on the mold clamping plates 23, 24, are first brought closer together via the rapid stroke drive 31 designed as a piston-cylinder unit, until

these are adjacent to each other or are close to each other.

The locking nuts 19 are then locked with their inner profile to a corresponding outer profile of the bars 15, whereby the locking nuts 19 firmly connect the movable mold clamping plate 24 to the bars 15 by engaging the inner profile with the outer profile of the bars 15.

connect.

After locking the locking nuts 19, the movable mold clamping plate 24 is pulled over the bars 15 towards the fixed mold clamping plate 23 via the pressure pads 20 until the mold halves of the mold 25 are in contact with each other and then additional pressure is built up between the movable mold clamping plate 24 and the fixed mold clamping plate 23 (via the mold 25 arranged between them), which pressure is referred to as

Closing force of the closing unit 26.

The actuation of the locking nuts 19 as well as the pressure pads 20 of this embodiment are implemented by embodiments of a hydraulic drive unit 1 according to the invention, whereby the kinematic parameters of the pistons 4 can be determined by a computing unit 7 and thus an actual position, a speed, an acceleration and/or a change in position of the locking nuts 19 and/or the pressure pads 20

can be determined.

List of reference symbols:

1 drive unit

2 forming machine 3 cylinder

4 pistons

5 Pressure chamber

6 Pressure sensor

7 Computing unit

8 Connecting line 9 Hydraulic accumulator 10 Second pressure chamber

11 Pressure source

12 Pump

13 Valve

14 Control or regulating device 15 Beam

16 Locking unit

17 Valve

18 tanks

19 Locking nut

20 pressure pads

21 Injection unit

22 Machine frames

23 fixed mold clamping plate 24 movable mold clamping plate 25 mold tool

26 Plasticizing unit

27 mass cylinders

28 Drive unit

29 Control unit

30 Display device

31 Rapid stroke drive

32 Spring element

Innsbruck, 14 December 2022

Claims (1)

Patent claims: Hydraulic drive unit for a forming machine (2), in particular injection moulding machine, comprising - a piston (4) arranged linearly displaceably in a cylinder (3) and a pressure chamber (5) delimited in the cylinder (3) by the piston (4), - at least one pressure sensor (6) which is designed to detect a signal characteristic of the pressure in the pressure chamber (5), and - a computing unit (7) which is signal-connected to the at least one pressure sensor (6) for receiving the characteristic signal, characterized in that the computing unit (7) is is designed based on the pressure in the pressure chamber (5) characteristic signal a kinematic parameters, preferably a position and/or a change in position of the piston (4). Drive unit according to the preceding claim, wherein the pressure chamber (5) is filled with a constant pressure medium mass, preferably hydraulic fluid mass, at least during the measurement of the characteristic signal. cooperates. Drive unit according to one of the preceding claims, wherein at least during the measurement of the characteristic signal the pressure chamber (5) in the cylinder (3) is closed and preferably a constant pressure medium mass includes. Drive unit according to claim 1 or 2, wherein at least during the measurement of the characteristic signal the Pressure chamber (5) via a connecting line (8) with a Hydraulic accumulator (9), preferably wherein a constant pressure medium mass is passed through the pressure chamber (5), the connecting line (8) and the hydraulic accumulator (9) is included. Drive unit according to at least one of the preceding claims, wherein the computing unit (7) is designed to determine the kinematic parameter by means of a relationship with the pressure stored in the computing unit (7), preferably taking into account a stored compression behavior of the drive unit. Drive unit according to at least one of the preceding claims, wherein the drive unit (1) has a hydraulic accumulator (9), preferably a bladder accumulator and/or diaphragm accumulator, particularly preferably with a variable compression ratio and/or variable counterpressure, having. Drive unit according to the preceding claim, wherein the hydraulic accumulator (9) is designed as a mechanical, preferably spring-actuated, and/or fluid-actuated hydraulic accumulator (9). Drive unit according to at least one of the preceding claims, wherein the piston (4) divides the cylinder (3) into the (first) pressure chamber (5) and a second pressure chamber (10) divided into. Drive unit according to at least one of the preceding claims, preferably according to the preceding claim, wherein the drive unit (1) has a pressure source (11), in particular at least one pump, preferably which pressure source (11) with the second pressure chamber (10) 27739 11. 12. 13. 14. 3 091177 28/h connected or connectable to the second pressure chamber (10) to apply a pressure. Drive unit according to the preceding claim, wherein the pressure source (11) is connected to the second pressure chamber (11) via a valve (13), preferably which valve (13) is controlled by a control or regulating device (14). or adjustable. Drive unit according to one of the two preceding claims, wherein the computing unit (7) is connected in a signal-connected manner to a control or regulating device (14) of the pressure source (11) and/or is designed as an integral component of the control or regulating device (14), wherein the kinematic parameter is used by the control or regulating device (14) to control or regulate the Pressure source (11) can be used as the actual value. Drive unit according to at least one of the preceding claims, wherein the cylinder (3) with the piston (4) arranged therein is designed as a double-acting piston-cylinder unit. Drive unit according to at least one of the preceding claims, wherein the pressure chamber (5) is a rod-side Chamber of a piston-cylinder unit. Closing unit for a forming machine with at least one hydraulic drive unit (1) according to one of the preceding claims, preferably wherein the at least one drive unit (1) is designed to drive a locking nut (19) relative to a spar (15) and/or as a pressure cushion (20) for building up the closing force is. 15. Shaping machine, in particular injection molding machine, with at least one hydraulic drive unit (1) according to one of claims 1 to 13 and/or a closing unit (16) according to claim 14. 16. Method for monitoring a hydraulic drive unit (1), preferably a hydraulic drive unit (1) according to one of claims 1 to 13, which hydraulic drive unit (1) comprises a piston (4) arranged in a cylinder (3) so as to be linearly displaceable and a pressure chamber (5) delimited in the cylinder (3) by the piston (4), wherein a pressure in the pressure chamber (5) is measured and via the pressure, preferably a determined pressure change, a kinematic parameter, in particular a position and/or a position change, of the piston (4) is detected. 17. Computer program product for monitoring a hydraulic drive unit (1), preferably a hydraulic drive unit (1) according to one of claims 1 to 13, comprising instructions which cause a computer to carry out the following steps when executing the program: - Receiving a characteristic signal for a pressure in a pressure chamber (5) and - Determining a kinematic parameter, preferably a position and/or a position change, of a piston (4) of the pressure chamber (5) on the basis of the Pressure in the pressure chamber (5) characteristic signal. Innsbruck, 14 December 2022