HYDRAULIC SYSTEM FOR A MOLDING MACHINE

Abstract

A hydraulic system for a molding machine with a hydraulic valve, includes an actuator for positioning the hydraulic valve, a machine control system realized separate from the hydraulic valve, a first signal connection between the machine control system and the hydraulic valve, and a sensor. The sensor is signal-connected to the machine control system via a second signal connection, and the machine control system is formed to carry out a valve regulation of the hydraulic valve on the basis of measured values of the sensor.

Claims

1. A hydraulic system for a molding machine with at least one hydraulic valve, which contains an actuator for positioning the at least one hydraulic valve, a machine control system realized separate from the at least one hydraulic valve, a first signal connection between the machine control system and the at least one hydraulic valve, as well as at least one sensor, characterized in that the at least one sensor is signal-connected to the machine control system via at least one second signal connection and the machine control system is formed to carry out a valve regulation of the at least one hydraulic valve on the basis of measured values of the at least one sensor.

2. The hydraulic system according to claim 1, wherein the machine control system is formed to generate and output an actuation signal for the actuator of the at least one hydraulic valve from a correcting variable resulting from the valve regulation, with the result that the actuator can be actuated by the actuation signal transmitted via the signal connection.

3. The hydraulic system according to claim 2, wherein the machine control system is formed to generate and output an analog actuation signal for the at least one hydraulic valve.

4. The hydraulic system according to claim 1, wherein the hydraulic system has at least one fluid pump and a drive coupled to it, wherein the drive and/or the at least one fluid pump is preferably signal-connected to the machine control system with a further signal connection.

5. The hydraulic system according to claim 4, wherein the at least one fluid pump is formed adjustable with respect to its displacement volume, preferably is formed as an axial piston pump with adjustable swivel angle.

6. The hydraulic system according to claim 5, wherein at least one hydraulic actuator, preferably a piston-cylinder unit, connected in a fluid-carrying manner to the hydraulic valve is provided, which is formed to set a displacement volume of the at least one fluid pump.

7. The hydraulic system according to claim 1, wherein the machine control system is formed to set a displacement volume of the at least one fluid pump on the basis of a correcting variable resulting from the valve regulation by means of the at least one hydraulic valve and/or hydraulic actuator.

8. The hydraulic system according to claim 4, wherein the machine control system is formed to generate and output the actuation signal for the actuator of the at least one hydraulic valve taking into account a displacement volume of the at least one fluid pump and/or an operating state of the drive of the fluid pump.

9. The hydraulic system according to claim 1, wherein the at least one sensor is formed as a pressure sensor and/or flow sensor, wherein a signal representative of the pressure and/or flow can be provided to the machine control system.

10. The hydraulic system according to claim 1, wherein the at least one sensor is formed as a position sensor, preferably a swivel angle sensor.

11. The hydraulic system according to claim 1, wherein the hydraulic system has at least one drive unit for driving at least one machine component, preferably a clamping unit and/or plasticizing unit, of the molding machine, wherein the machine control system is formed to control or regulate a movement, speed and/or position of the at least one machine component.

12. A molding machine, preferably an injection-molding machine, with at least one hydraulic system according to claim 1.

13. A computer program product suitable to operate a hydraulic system, in particular according to claim 1, and suitable to be executed on a machine control system of a molding machine, comprising commands which, when executed by the machine control system, prompt the latter to receive measured values of at least one sensor and to carry out a valve regulation of at least one hydraulic valve on the basis of measured values of the at least one sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0108] Further details and advantages of the present invention are explained in more detail below with the aid of the description of the figures with reference to the embodiments represented in the figures, in which:

[0109] FIG. 1 shows a first embodiment of a hydraulic system according to the invention,

[0110] FIG. 2 shows a detail of the hydraulic system from FIG. 1,

[0111] FIGS. 3a, 3b show known embodiment variants of the state of the art,

[0112] FIG. 4 shows an embodiment according to the invention, and

[0113] FIG. 5 shows an embodiment of a molding machine.

DETAILED DESCRIPTION OF THE INVENTION

[0114] FIG. 1 shows a first embodiment of a hydraulic system 1 according to the invention.

[0115] The hydraulic system 1 has a fluid pump 8, by means of which a required pressure and/or volume flow of hydraulic fluid can be fed into the hydraulic system 1, for example from a reservoir or tank for hydraulic fluid.

[0116] With the aid of this hydraulic system 1, a drive unit of a molding machine 15—such as for example a clamping unit 22, an injection unit 16 or a plasticizing unit 25—can be driven (reference may be made to FIG. 5 at this point).

[0117] The hydraulic system 1 represented in FIG. 1 furthermore has a drive 9, which is coupled to the fluid pump 8, in order to drive the fluid pump 8.

[0118] The drive 9 is formed by a variable-speed servomotor, which is connected to the machine control system 4 via the signal connection 10.

[0119] The machine control system 4 can be formed to control or regulate the drive 9 with respect to the rotational speed, in order thus to be able to control or regulate a drive power via the rotational speed of the drive 9 of the fluid pump 8.

[0120] The fluid pump 8 provided is formed adjustable with respect to its displacement volume. The fluid pump 8 represented here is implemented for example as an axial piston pump with adjustable swivel angle.

[0121] This swivel angle can be set via the hydraulic actuator 11, wherein the hydraulic actuator 11 can be controlled or regulated via the hydraulic valve 2 and the actuator 3 associated with the hydraulic valve 2.

[0122] This actuator 3 and/or the hydraulic valve 2 are connected to the machine control system 4 via the first signal connection 5.

[0123] The swivel angle of the fluid pump 8 can be detected by means of the sensor 6—here the swivel angle sensor 14 for example—wherein a measurement signal of the swivel angle sensor 14 can be supplied to the machine control system 4 via the second signal connection 7.

[0124] Moreover, a sensor 6 is provided in order to measure a pressure and/or flow of the hydraulic system 1, wherein the sensor 6 is formed as a pressure sensor 12 and/or flow sensor 13 and can provide a measurement signal to the machine control system 4 via the second signal connection 7.

[0125] In this embodiment of the hydraulic system 1, it is provided that the sensors 6, 12, 13, 14 are signal-connected to the machine control system 4 via the second signal connections 7 and the machine control system 4 is formed to carry out the valve regulation of the hydraulic valve 2 on the basis of measured values of the sensors 6, 12, 13, 14.

[0126] It can be provided that the machine control system 4 takes into account a pressure and/or flow prevailing in the hydraulic system 1 and/or a prevailing swivel angle of the fluid pump 8, in order to adjust the swivel angle of the fluid pump 8 and thus to regulate or control a pressure and/or flow of the hydraulic system 1 with respect to a predefined or calculated target value.

[0127] Furthermore, it can be provided that the machine control system 4 takes a rotational speed of the drive 9 into account in the control or regulation of the hydraulic valve 2 and/or even uses the rotational speed of the drive 9 as further control or regulating variable in addition to the hydraulic valve 2 for controlling or regulating the hydraulic system 1.

[0128] It can particularly preferably be provided that the machine control system 4 itself generates a preferably analog actuation signal and outputs it to the hydraulic valve 2 via the signal connection 5, wherein the actuator 3 actuates the hydraulic valve 2 according to the actuation signal of the machine control system 4.

[0129] As can be seen in FIG. 2, the hydraulic system 1 can be formed in such a way that, via the hydraulic valve 2, a position of the swivel angle of the fluid pump 8 is set via the hydraulic actuator 11.

[0130] The hydraulic actuator 11 for setting the swivel angle of the fluid pump 8 is formed as a spring-return piston-cylinder unit.

[0131] The hydraulic valve 2 of the embodiment of FIG. 2 (which represents a detail view of the hydraulic system 1 of FIG. 1) is formed as a magnetically-operated, spring-return 3/2-way valve, wherein the actuator 3 of the hydraulic valve 2 is to be configured as the magnet operation represented, which can be actuated directly via an analog actuation signal of the machine control system 4.

[0132] It is hereby made possible that a correcting variable—more precisely: an actuation signal—of the machine control system 4 is known and this can be taken into account by the machine control system 4 in further control processes.

[0133] Thus, it is possible that the machine control system 4, by means of the hydraulic valve 2 and the hydraulic actuator 11, sets a displacement volume of the fluid pump 8 on the basis of a correcting variable resulting from the valve regulation.

[0134] It can be provided that the machine control system 4 is formed to generate and output the actuation signal for the actuator 3 of the hydraulic valve 2 taking into account a displacement volume of the fluid pump 8 and/or an operating state of the drive 9 of the fluid pump 8.

[0135] FIGS. 3a, 3b on the other hand show known control or regulation methods from the state of the art, wherein valve electronics separate from the machine control system 4 are provided on the hydraulic valve 2 in order to perform a control or regulation of the hydraulic valve 2.

[0136] The valve electronics accept sensor signals of the sensors 6, 12, 13, 14 and use these for analog (FIG. 3a) or digital (FIG. 3b) control or regulation of the valve until a target value of the hydraulic valve 2 is set.

[0137] However, the valve electronics communicate with the machine control system 4 only via target and actual values, wherein the valve electronics can for example receive a target value for a pressure of the fluid pump 8 transmitted by the machine control system and can return an actual value.

[0138] However, it is not possible or known from the state of the art that the machine control system 4 itself receives information learned or provided via correcting variables of the hydraulic valve 2, sensor signals of the sensors 6, 12, 13, 14 or other control parameters of the hydraulic valve 2, whereby it is not possible for the machine control system 4 to use these parameters or sensor signals in the regulation or control of further machine components.

[0139] In the case of a digital control or regulation of the state of the art, as represented by FIG. 3b, it is provided that the valve electronics are connected to the machine control system 4 via a fieldbus system, wherein further (diagnostic) parameter values can additionally also be transmitted to the valve electronics.

[0140] As can be seen on the other hand from FIG. 4 and the embodiment variant according to the invention represented in FIG. 4, it is provided according to the invention that the machine control system 4 communicates directly with the hydraulic valve 2, wherein, preferably analog, actuation signals can be sent directly to the hydraulic valve 2 by the machine control system 4 and thus these actuation signals are also present as actual values of the machine control system 4.

[0141] Furthermore, sensor measurement signals can be transmitted directly to the machine control system 4, wherein the machine control system 4 can adapt the calculation or output of the actuation values to the hydraulic valve 2 on the basis of the measured values of the sensors 6, 12, 13, 14.

[0142] The molding machine 15 represented by way of example in FIG. 5 is an injection-molding machine and has an injection unit 16 and a clamping unit 17, which are arranged together on a machine frame 18. The machine frame 18 could alternatively also be formed multi-part.

[0143] The clamping unit 17 has a fixed platen 19, a movable platen 20 and an end plate 21.

[0144] Alternatively, embodiment variants without end plate 21 are also possible. Such clamping units are referred to as two-plate clamping units.

[0145] The movable platen 20 is movable relative to the machine frame 18 via a symbolically represented clamping drive 22. The clamping drive 22 can be formed as a hydraulic drive unit which is operated via a hydraulic system 1 described previously.

[0146] Mold halves of a mold 23 can be clamped or fitted (represented dashed) on the fixed platen 19 and the movable platen 20.

[0147] The fixed platen 19, the movable platen 20 and the end plate 21 are mounted and guided relative to each other by the rails 24.

[0148] The mold 23 represented closed in FIG. 5 has at least one cavity. An injection channel, via which a plasticized material can be supplied by the plasticizing unit 25, leads to the cavity.

[0149] The injection unit 16 of this embodiment has an injection cylinder 26 and an injection screw arranged in the injection cylinder 26. This injection screw is rotatable about its longitudinal axis and movable along the longitudinal axis axially in the conveying direction.

[0150] These movements are driven via a schematically represented drive unit. This drive unit preferably comprises a hydraulic rotary drive for the rotational movement and a linear hydraulic drive for the axial injection movement, wherein the hydraulic drives can be operated via a hydraulic system 1 described previously.

[0151] The plasticizing unit 25 (and thus the injection unit 16) is in signaling connection with the central machine control system 4. Control commands are output for example to the plasticizing unit 25 by the central machine control system 4.

[0152] The central machine control system 4 can be connected to an operating unit 27 and/or a display device 28 via a signal-carrying connection 29 or can be an integral constituent of such an operating unit 27.

LIST OF REFERENCE NUMBERS

[0153] 1 hydraulic system [0154] 2 hydraulic valve [0155] 3 actuator [0156] 4 machine control system [0157] 5 signal connection [0158] 6 sensor [0159] 7 signal connection [0160] 8 fluid pump [0161] 9 drive [0162] 10 signal connection [0163] 11 hydraulic actuator [0164] 12 pressure sensor [0165] 13 flow sensor [0166] 14 swivel angle sensor [0167] 15 molding machine [0168] 16 injection unit [0169] 17 clamping unit [0170] 18 machine frame [0171] 19 fixed platen [0172] 20 movable platen [0173] 21 end plate [0174] 22 clamping drive [0175] 23 mold [0176] 24 rail [0177] 25 plasticizing unit [0178] 26 injection cylinder [0179] 27 operating unit [0180] 28 display device [0181] 29 signal-carrying connection