EP1302256B1 - Control apparatus for a hydraulic cylinder - Google Patents

Abstract

Arrangement comprises a control block arranged between a hydraulic pump and a cylinder. The control block has channels for hydraulic lines and electrically controlled hydraulic valves that have sensors for monitoring their positions. To guarantee hydraulic safety an electrical circuit arrangement (30) is provided that supplies safety input signals (X) corresponding to an algorithm for valve setting signals (y18a, y18b, y19a) to the valves (18, 19). The electrical circuit is hard-wired to the control block.

Description

The invention relates to a device for controlling a hydraulic cylinder of a forming machine, in particular a press, with one between a pump and the cylinder arranged control block, with channels for hydraulic Pressure medium is provided and on the by electrical control signals controlled hydraulic valves are held that provided with sensors for switching position monitoring are, wherein the control block is designed so that hydraulic Security is guaranteed (see e.g. DE-A-19515640).

In metalworking forming machines, especially in Presses are used to operate the forming tools hydraulic Cylinder supplied with pressure medium by a pump become. To control the amount of pressure medium supplied to the cylinder serves one with pressure medium channels and electromagnetic Actuable valve-provided control block, which between Pump and cylinder is arranged. The valves are in screwed the control block and / or flanged to it. The valves are actuated by electrical Control signals. The valves are with sensors for one Switch position monitoring provided. The output signals these sensors are further along with the output signals Sensors that e.g. B. the position and movement of the Piston of the cylinder, the closing of protective grilles and Monitor security doors, feed them to a central control, which convert these signals into control signals for actuation the valves linked. On such forming machines great security requirements, the Compliance with the responsible organizations, such as z. B. the professional association, be closely monitored.

The manufacturers of such forming machines provide the for the control of the forming machines required assemblies, such as z. B. hydraulic control blocks, central safety control and sensors, not yourself, but get them from usually different external suppliers and integrate the assemblies in their forming machine. This leads to one great effort in the safety-related acceptance of the Forming machines by the responsible monitoring organization. A certain simplification of the safety-related Decrease brings the use of hydraulic to already Safety-certified control blocks with redundantly designed Valves, of which the safety-relevant ones Directional valves with non-contact switch position monitoring are equipped. With such control blocks ensures that in the event of a failure of the electrical Activation of the valves no movement of the piston of the Cylinder held tool, especially no sinking of the tool due to its own weight. The safe operation of a forming machine in the sense of the professional association with such certified hydraulic Control blocks is only in connection with a safety-related suitable electrical control guaranteed. This also includes safety monitoring the position of the slide of the valves via corresponding Sensors with a to the slide movement before opening an oil-carrying control edge to check whether the slide moves in the desired direction. To do this Central safety controls specially developed for this purpose used. These safety controls are in in the form of a programmable logic controller known under the short name PLC Control realized. The manufacturer of the Forming machines must have every valve and sensor on the control block wire with the safety controller. Furthermore must for safety control depending on the version and Application of the control block a special sequence program to be written. The safety-relevant Information from the slide position monitoring on the control block and other safety-relevant sensors, such as two-hand operation, Emergency stop, protective grille, security doors, be safely evaluated to an uncontrolled movement of the tool held on the piston of the cylinder prevent. The effort for the safety-related acceptance the forming machine is therefore still very large.

The invention has for its object a control device of the type mentioned at the beginning, which create the safety-related Requirements both in terms of hardware as well as in terms of software and that as complete assembled and tested unit to the machine manufacturer is delivered.

This object is characterized by those in claim 1 Features solved. In addition to hydraulic safety of the control block through the redundancy of the valves are the Valves firmly with the electrical held directly on the control block Wired circuit arrangement. The electrical Circuit arrangement contains, among other things, the necessary PLC functionality with the appropriate software to get the Forming machine in a simple way with appropriate start commands to control. The electrical circuitry is with the necessary safety components equipped, d. H. the start and stop functions are in the safety-related parts of the forming machine control hard-wired, redundant and self-monitoring. They therefore meet the requirements for safety-related Parts for controlling and monitoring a hydraulic Forming machine. The invention breaks through the previous one Philosophy of an independent of the concept of the forming machine universal central security control in favor one decentrally individually on the respective hydraulic Control block tailored control concept that is independent from a higher-level control all safety-related Requirements for a hydraulic forming machine met. The manufacturer of the forming machine receives both regarding the hardware of the hydraulic control block and the electrical circuit arrangement as well the software of the electrical circuitry from the Monitoring organization of fully certified automation solution. This leads to a considerable simplification in the Commissioning of the forming machine and thus contributes to one Minimization of development and commissioning costs at.

Advantageous developments of the invention are in the subclaims characterized.

Figur 1

eine Steuereinrichtung gemäß der Erfindung, bei der die externen Sensoren über mit mechanisch kodierten Steckern versehene elektrische Anschlußleitungen angeschlossen sind, und

Figur 2

Teilbereiche einer Steuereinrichtung gemäß der Erfindung mit einem hydraulischen Steuerblock entsprechend Figur 1, bei der die externen Sensoren über ein AS-Interface-Bussystem angeschlossen sind.

The invention is explained in more detail below with its further details using exemplary embodiments illustrated in the figures. Show it

Figure 1

a control device according to the invention, in which the external sensors are connected via electrical connection lines provided with mechanically coded plugs, and

Figure 2

Subareas of a control device according to the invention with a hydraulic control block according to Figure 1, in which the external sensors are connected via an AS-Interface bus system.

The same components have the same reference numerals Mistake.

FIG. 1 shows a schematic representation of an electrohydraulic control device 10 with a hydraulic control block 11, which controls the pressure medium supply from a pump 12 to a hydraulic cylinder 13 of a forming machine, in this exemplary embodiment a press. A forming tool of the press, not shown in FIG. 1, is held on the piston rod of the cylinder 13, designated 14. The chambers of the cylinder 13 are designated by the reference numerals 15 (for the bottom-side chamber) and 16 (for the rod-side chamber). The piston of the cylinder 13 is provided with the reference number 17. Channels for hydraulic pressure medium are arranged in the control block 11. On the control block 11, two valves 18 and 19 are held, which control the flow of the pressure medium. The valves 18 and 19 can be actuated by electrical signals y _18a , y _18b and y _19a , which are fed to two solenoid coils 18a and 18b of the valve 18 and a solenoid coil 19a of the valve 19, respectively. The valves 18 and 19 can be both directly controlled valves and pilot operated valves. Furthermore, three pressure limiting valves 20, 21 and 22 and a check valve 23 are held on the control block 11. The control block 11 has four hydraulic connections, which are labeled P, T, A and B. The pressure medium is supplied to the control block 11 via the port P. The ports A and B of the control block 11 are connected to the chambers 16 and 15 of the cylinder 13, respectively. If the forming tool is actuated by a plurality of cylinders, the corresponding chambers of the further cylinders are likewise connected to the connections A and B of the control block 11. The control block 11 is connected to a tank 25 via the connection T.

An electrical circuit arrangement 30, which is held firmly on the hydraulic control block 11, forms with the latter. a structural unit. The circuit arrangement 30 is provided with interfaces 31e, 31i, 32 and 33 for electrical connecting lines. A number of electrical input signals are supplied to the circuit arrangement 30 via the interfaces 31e and 31i. Via the interface 32, which is permanently wired to the magnetic coils 18a, 18b and 19a by means of electrical lines 18a *, 18b * and 19a *, the circuit arrangement 30 outputs the electrical actuating signals y _18a , y _18b , y _19a for the valves 18 and 19 out. The circuit arrangement 30 communicates with a higher-level sequence control 35 via the interface 33 and a control bus 34. The circuit arrangement 30 shown in FIG. 1 is provided with mechanically coded plug connections 41 which are connected within the circuit arrangement 30 by electrical lines 41 * to the interface 31e , A number of external sensors are connected to the plug connections 41 via correspondingly coded mating plugs. The external sensors are sensors that are considered safety-relevant in accordance with the regulations that apply to metal forming machines, and sensors that are not considered safety-relevant in this context. As safety-relevant sensors in FIG. 1 - as in FIG. 2 - a press two-hand control 43, an emergency stop switch 44 and a protective grille 45 are shown. For reasons of clarity, the security-relevant sensors also include security doors in FIG. 1, which secure access to a hazardous area. The two-hand press actuation 43 only allows the forming tool held on the piston rod 14 to be lowered if the operator actuates the two-hand press actuation 43 with both hands. Like the protective grille 45, the two-hand press actuation 43 is intended to prevent the operator from reaching into the press while the forming tool is moving. When the emergency stop switch 44 is actuated, the forming tool should be moved into a safe position as quickly as possible and should remain securely held there. 1 and 2, a displacement sensor 48 and two limit switches 49 and 50 are shown as non-safety-relevant sensors. The displacement sensor 48 supplies an electrical signal which is a measure of the position of the piston 17 and thus also of the forming tool held on the piston rod 14. The limit switches 49 and 50 emit an electrical switching signal when the piston rod 14 reaches a predeterminable position. Both limit switches can be moved along the direction of movement of the piston rod 14 and can be set to the desired position values. The limit switch 49 is assigned to an upper position and the limit switch 50 to a lower position. The reference symbols of the connecting lines leading from the external sensors 43 to 45 and 48 to 50 to the plug connections 41 are formed from the reference symbol of the respective sensor and a "*" supplementing this reference symbol. The reference symbols of the electrical signals of the sensors are formed from the letter "x" and an index consisting of the reference symbols of the respective sensor. So z. B. the leading from the press two-hand operation 43 to the plug connections 41 with 43 * and the electrical signal of the press two-hand operation is designated with x ₄₃ .

The hydraulic control block 11 is constructed so that it Requirements of the regulations for hydraulic safety equivalent. In particular, the safety-relevant valves 18 and 19, through which a directional control of the movement of the piston 17 of the cylinder 13 takes place, so connected to one another, that in the absence of electrical control of the solenoids 18a, 18b, 19a relieves the chamber 15 to the tank 25 is and the pressure medium located in the chamber 16 below the weight of the forming tool held on the piston rod 14 is not displaced from the chamber 16. So that is ensures that the forming tool is not uncontrolled can sink. The pressure relief valve 20 limits in the usual way Way the outlet pressure of the pump 12. The pressure relief valve 21 limits the pressure in the chamber 16 of the cylinder 13. The pressure relief valve 22 ensures connection with the check valve 23 so that the piston 17th only moves down when the pressure in chamber 16 - due to a corresponding pressurization of the chamber 15 - exceeds a predeterminable value. The response pressure the pressure relief valve 22 is dimensioned so that the Dead weight of the piston 17, the piston rod 14 and the this held forming tool does not yet sink of the forming tool. The piston 17 only moves then down when the chamber 15 is additionally pressurized is applied. This is only the case if that Valve 19 is switched to the working position and the valve 18 is actuated in the direction in which the chamber 15 Pressure medium is supplied. To the piston 17 upwards move, the valve 19 must be switched to its working position be and the valve 18 operated in the direction in which is a pressure medium supply to the chamber 16, wherein at the same time pressure medium from chamber 15 via valve 18 is displaced to the tank 25.

The valve 18 is provided with a displacement sensor 55, which emits an electrical signal x ₅₅ , which is a measure of the position of the control slide of the valve 18. The output of the displacement sensor 55 is hard-wired to the interface 31i via an electrical line 55 *. The valve 18 is provided with a positive overlap. Due to this measure, a pressure medium flow only takes place when the control slide has covered a minimum distance. This makes it possible to detect the direction of movement of the control slide when the valve 18 is actuated by the displacement sensor 55, without pressure medium already flowing through the valve 18. If the control slide moves in the desired direction, the valve 18 is actuated further. In contrast, the control slide of the valve 18, z. B. due to a fault, in the wrong direction, the circuit arrangement 30 stops the control of the valve 18.

The valve 19 is provided with a displacement sensor 57 which emits an electrical signal x ₅₇ . The output signal x _{57 of} the displacement sensor 57 is a measure of the position of the control slide of the valve 19. The output of the displacement sensor 57 is hard-wired to the interface 31i of the circuit arrangement 30 via an electrical line 57 *.

The linking of the electrical signals to that of the circuit arrangement 30 from the control block 11 via the interface 31i and from external sensors 43 to 45 and 48 to 50 supplied via the plug connections 41 and the interface 31e are done in digital form by a microprocessor 60. The microprocessor 60 is together with memory chips 61 and other electronic not shown Blocks arranged on a circuit board 62. The Signal linking takes place according to an algorithm that works accordingly the structure and purpose of the control block 11 is formed. Details of digital signal linking by the microprocessor 60 are as follows not described, since such signal links are fundamentally are known. For the control device according to the invention it is essential that the control block 11 as such is certified for hydraulic safety and that the electrical connections 18a *, 18b *, 19a *, 55 *, 57 * between the electrical held on the control block 11 Components and the interfaces 31i and 32 of the circuit arrangement 30 as well as the electrical connections 41 * between the interface 31e and the mechanically coded Plug connections 41 are hard-wired at the factory. This Measures allow the control block 11 and the Circuit arrangement 30 existing control device 10 together with the algorithm for signal linking in the To certify circuit arrangement 30. So there is one Type-tested device for controlling a hydraulic Cylinders of a metal forming machine that are complete assembled and tested. The mix-up safe Connections prevent errors when connecting the external sensors. The circuit arrangement 30 contains the for PLC functionality required for the respective application. In addition, all are in the circuit arrangement 30 safety components integrated. I.e. the Start and stop functions in the safety-related parts the control of the forming machine are hardwired and self-monitoring. The control device thus corresponds 10 the requirements for safety-related Parts of control and monitoring devices for hydraulic Forming machines. The bus 34 is used for communication Circuit arrangement 30 with the higher-level sequence control 35. The sequence control 35 is used to specify setpoints and parameters, to release processing steps and for visualization. Because there are no security-related issues Data transmitted over bus 34 is for data transmission between the sequencer 35 and the circuit arrangement 30 of the control unit 10 - unlike one central safety control - no safety bus required.

FIG. 2 shows a partial area of that shown in FIG. 1 Control device. For connecting the external sensors 43 to 45 and 48 to 50 with the circuit arrangement 30 Another bus 66 serves as the AS-Interface bus EN 50295 is formed. With one designated as "Safety at Work" Design of the AS-Interface bus for safety-relevant Use cases, it is possible both security-relevant Sensors, such as sensors 43 to 45, as well sensors not relevant to safety, such as sensors 48 to 50 to be connected to the AS-Interface bus. The connection of the Sensors on the bus 66 take place via interfaces 43s, 44s, 45s, 48s, 49s and 50s. As a mix-up safe connection an interface serves the bus 66 to the circuit arrangement 30 68, which has an internal bus section 69 the interface 31e is wired. To the bus section 69 is a safety monitor via a further interface 70 72 connected. The safety monitor 72 detects the safety-relevant ones Signals, d. H. the signals of the safety-relevant Sensors 43 to 45, and leads them to the Interface 31e via a line 73 to. The not security relevant Signals, d. H. the signals of the non-safety-relevant Sensors 48 to 50 are the interface 31e fed directly via the bus section 69. At this The configuration of the control device 10 only requires the bus 66 to be connected to the interface 68. In particular the trapezoidal cross-section ensures the AS-Interface bus system of the two-wire connecting the individual interfaces Cable for a connection of the external sensors to the interface 68. The safety-relevant Safety monitor 72 evaluating signals arranged within the circuit arrangement 30 and with the other components hard-wired. The security monitor 72 and its wiring can therefore be included in the safety test the control device 10 are included.

Another alternative, the electrical signals from the external To supply sensors to the electrical circuit arrangement 30, consists of connecting the safety-relevant external sensors 43 to 45 (as in FIG. 1) via mechanically coded plug connections with the circuit arrangement 30 to connect and the non-security external sensors 48 to 50 (as in FIG. 2) via a Data bus, e.g. B. an AS-Interface data bus with the electrical Circuit arrangement 30 to connect. In this case the safety monitor 72 shown in FIG. 2 is not required, since only the signals of the safety-relevant external sensors are transmitted. In this embodiment, too, not only the signals of the external safety-relevant sensors but also the signals of the external non-safety-relevant sensors of the electrical circuit arrangement 30 via confusion-proof Connections fed.

Claims (14)

1. A device for the control of a hydraulic cylinder (13) of a forming machine, in particular of a press, having, arranged between a pump (12) and the cylinder (13), a control block (11) which is provided with ducts for hydraulic pressure medium and on which are held hydraulic valves (18, 19) controlled by electrical command signals and equipped with sensors (43, 44, 45) for monitoring of the switching position, the control block being developed such that hydraulic safety is assured, characterized by the fact that held on the control block (11) is an electric circuit arrangement (30) which links safety-related input signals (x55, x57, x43, x44, x45) according to a predetermined algorithm to form command signals (y18a, y18b, y19a) for the valves (18, 19), the electrical connections (18a*, 18b*, 19a*) between electrical components (18a, 18b, 19a) held on the control block 11) and the circuit arrangement (30) are permanently wired up in-factory and the electrical signals (x43, x44, x45) from external safety-related sensors (43, 44, 45)are fed to the circuit arrangement (30) via polarized connections (41; 68).
2. A control device according to claim 1, characterized by the fact that electrical signals (x48, x49, x50) from non-safety-related external sensors (48, 49, 50) are included in the linkage of the safety-related input signals (x43, x44, x45) by the electrical circuit arrangement (30).
3. A control device according to claim 1 or claim 2, characterized by the fact that the connection lines (x43, x44, x45, x48, x49, x50) of the external sensors (43, 44, 45, 48, 49, 50) are connected to the circuit arrangement (30) via mechanically coded plug-in connectors (41).
4. A control device according to any of the preceding claims, characterized by the fact that the external safety-related sensors (43, 44, 45) are connected to the circuit arrangement (30) via a data bus (66).
5. A control device according to claim 4, characterized by the fact that the external non-safety-related sensors (48, 49, 50) are connected to the circuit arrangement 830) via the data bus (66).
6. A control device according to claim 4 or 5, characterized by the fact that a safety monitor (72) is connected to a section (69) of the data bus (66) running inside the circuit arrangement (30), which registers the signals of the safety-related sensors (43, 44, 45).
7. A control device according to claim 1 or claim 2, characterized by the fact that the connection lines (x43, x44, x45) of the external safety-related sensors (43, 44, 45) are connected to the circuit arrangement (30) via mechanically coded plug-in connectors and by the fact that the external non-safety-related sensors (48, 49, 50) are connected to the circuit arrangement (30) via a data bus.
8. A control device according to any of the preceding claims, characterized by the fact that the signal linkage in the circuit arrangement (30) is performed digitally.
9. A control device according to claim 8, characterized by the fact that the signal linkage in the circuit arrangement (30) is performed via a microprocessor.
10. A control device according to any of the preceding claims, characterized by the fact that the algorithm for linking the input signals is stored in the circuit arrangement (30).
11. A control device according to claim 10, characterized by the fact that the algorithm for linking the input signals in the circuit arrangement (30) is designed according to the structure of the control block (11) and is type tested in conjunction with the control block (11).
12. A control device according to any of the preceding claims, characterized by the fact that the electrical connections (18a*, 18b*, 19a*, 55*, 57*) between the circuit arrangement (30) and the control block (11) and the electrical connections (41*; 69) within the circuit arrangement (30) to the polarized connections (41; 68) for the external sensors (43, 44, 45, 48, 49, 50) are executed in a type-tested fashion.
13. A control device according to any of the preceding claims, characterized by the fact that the circuit arrangement (30) is provided with an interface (33) for connection with a control bus (35).
14. A control device according to claim 13, characterized by the fact that command values and parameters can be fed to the circuit arrangement (30) via the control bus (35).

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