EP1203161A2

EP1203161A2 - Security valve for a press

Info

Publication number: EP1203161A2
Application number: EP00960352A
Authority: EP
Inventors: Lothar GRÖTZINGER
Original assignee: Herion Systemtechnik GmbH
Current assignee: Herion Systemtechnik GmbH
Priority date: 1999-08-13
Filing date: 2000-08-11
Publication date: 2002-05-08
Anticipated expiration: 2020-08-11
Also published as: EP1203161B1; ES2243299T3; JP2003507664A; DE50010408D1; WO2001012997A3; WO2001012997A2

Abstract

The invention relates to a hydraulic valve arrangement for operating a hydraulic consumer (80). Said arrangement is connected to a hydraulic pressure source (40) by means of at least one pressure connection (30), to the hydraulic consumer (8) by means of at least one working connection (70) and to a tank (60) by means of at least one tank connection (50). The tank is provided with a hydraulic fluid. The inventive arrangement is provided with at least two working valves (90, 140) which can be actuated by means of at least one electrically controllable control valve (230). The aim of the invention is to obtain coupling and breaking operations at user level (80) which are as short as possible. To this end, the at least two working valves (90, 140) are configured as seat valves (110).

Description

Press safety valve

DESCRIPTION

Background of the Invention

The invention relates generally to hydraulic safety valves and in particular to a safety valve unit according to the preamble of claim 1, a damping valve unit according to the preambles of claims 9 and 14, and a valve arrangement comprising these units according to claim 1c and a press safety valve comprising these units. Hydraulic safety valves of the type concerned here are used, for example, to control the brake and / or clutch of a mechanical press. From DE 38 17 123 AI, a hydraulic valve for the aforementioned use has already become known, which is controlled by two electromagnetically actuated pilot valves. The valve also has two valve bodies with control pistons which can be moved in opposite directions. The connections between a pump connection, two working connections and two tank connections are controlled by means of the control pistons. In the event of a malfunction, the valve bodies go into a hydraulically locked end position. In particular, one of the two pilot valves is designed as a proportional pressure differential valve, the control pistons assigned to it being provided with fine control notches, so that the valve is controlled proportionally and thus the pressure build-up, the speed and the direction of movement of a consumer connected downstream of the valve can be controlled.

In DE 196 20 468 AI is also a

Safety valve described, in which two parallel working pistons are arranged in a housing, each of which is firmly connected to a valve plate. Both working pistons are controlled electromagnetically by means of pilot valves. An inlet is formed in the housing and is connected to a compressed air source. The inflow leads to the valve plates, which are connected to one another by means of cross-channels. A consumer, for example a piston drive of a mechanical press, can be pressurized in the switch position of the safety valve via a consumer connection. A channel branches off from the cross channels to each of the pilot valves. Furthermore, a channel runs from each pilot valve to the associated working piston. In addition, each pilot valve is provided with a solenoid, and each solenoid is connected via a power supply line to a power source that is part of a machine control.

In order to increase the productivity of mechanical consumers such as mechanical presses or the like, it is necessary to increase the speed of the piston drive.

Furthermore, there is an increasing tendency to unite entire press lines in individual large presses. However, these presses require correspondingly large clutch / brake units in order to be able to cope with the high hydraulic switching volumes, it being possible for these clutch / brake units to be arranged either as a unit or separately.

The safety valves described above, known in the prior art, are designed exclusively in piston slide valve technology, which means that maximum flow rate is limited. In addition, these valves require long switching times when coupling and braking the press due to the piston stroke required during a switching operation.

Summary of the invention

The invention is therefore based on the object of specifying a hydraulic valve arrangement and a press safety valve of the type mentioned at the beginning, which provide the shortest possible switching times of a mechanical consumer, in particular the shortest possible coupling and braking processes on a mechanical press, and yet at the same time ensure the highest possible operational reliability.

This object is solved by the features of independent claims 1 and 14. Advantageous embodiments of the invention are the subject of the dependent claims.

In the case of a safety valve unit of the type mentioned at the outset, the invention provides that the at least two working valves are designed as seat valves.

In the case of a damping valve unit that works in particular with the safety valve unit, a pressure reducing valve upstream of the first working valve is provided in a first variant. In a second variant, the damping valve unit has a directional control valve arranged on the tank connection side and designed as a seat valve.

The poppet valve design used in the aforementioned valves enables, in particular, high flow values and, at the same time, very short switching times of these valves, since, due to this design, even small piston movements lead to large valve opening cross sections with almost no time delay.

Brief description of the drawings

Exemplary embodiments of the invention are described below with reference to drawings, from which further features and advantages of the invention result. In the drawings, identical or functionally identical features are provided with the same reference numerals.

Show in detail:

La shows a hydraulic valve arrangement with a safety valve unit and a damping valve unit according to a first variant;

Fig. Lb one corresponding to Fig. La Valve arrangement with a variant of the damping valve unit that is different from FIG. 1; and

Fig. 2 is a functional flow diagram m to illustrate the operation of the valve arrangements shown in Fig. La and lb.

Detailed description of the embodiment

Fig. 1 shows a hydraulic valve assembly consisting of two assemblies, namely a safety valve unit 10 and one

Damping valve unit 20. The two units 10, 20 are 'via a pressure connection 30 with a hydraulic pump 40, via a tank connection 50 with a hydraulic fluid tank 60 and via a working connection 70 with a mechanical consumer, in the present example one for operating a (not shown here) ) mechanical press provided coupling and / or brake piston 80, hydraulically or pressure-connected. The hydraulic fluid is not important here; it can therefore be either a gas or a liquid.

The safety valve unit 10 has a first 2/2-way valve 90 designed in the manner of a seat valve, in which a piston 105 extending into a valve chamber 100 has an annular surface formed on the inside of the valve housing Valve seat 110 forms. This valve seat 110 connects or separates a pressure line 120 starting from the pressure connection 30 with a working line 130 starting from the working connection 70. The two lines 120, 130 are interrupted in the present operating state (closed).

An active movement of the piston 105 for operating the valve 90 takes place, likewise hydraulically, via a (valve) control chamber 115. The directional control valve 90 also has a proximity switch (S3) 95 designed as an inductive switch, by means of which the operating state of the directional control valve 90 is sensed can.

Furthermore, two 2/2-way valves 140, 150, which are also constructed in the manner of a seat valve, are provided, in which pistons 155, 165 which come into contact, for example, form a valve seat on an inner annular surface 170, and which are open in the currentless operating state shown by means of spring preloads 180, 190 , The directional control valves 140, 150 are therefore in the safe “open” position, in particular in the event of a power failure, in which the working line 130 is relieved. In these valves 140, 150, too, the pistons 155, 165 are moved hydraulically via control chambers 162, 175 (active). In addition, the directional control valves 140, 150 each have a proximity switch 145, 155 with the above-mentioned functionality.

Due to the design of all poppet valves 2/2-way valves together with pressure sensors (not shown here) arranged in the area of the respective valve seat, in combination with the fast valve switching times, offer high operational reliability.

Since the working line 130, parallel to the connection to the first directional valve 90, is also connected to the valve chambers 200, 210 of the two directional valves 140, 150, the working line 130 is hydraulically relieved in the present situation via a tank line 220 leading to the hydraulic fluid tank 60.

To increase the operational reliability of the entire valve arrangement, the two 2/2-way valves 140, 150 are functionally identical. Their parallel connection also means an additional increase in operational safety, which ensures that the clutch and / or brake piston 80 is braked safely.

As already mentioned, the directional control valves 90, 140, 150 are switched by movements of the pistons 105, 155, 165 driven by the control chambers 115, 162, 175, respectively. For this purpose, the control chambers 115, 162, 175 are connected to a hydraulic control line system 225 shown in dashed lines in the drawing.

The safety valve unit 10 also has two pilot valves 230, 240 designed as 4/2-way valves, which are switched by means of electromagnets 235, 245 become. The pilot valves 230, 240 either (as shown here) connect the control chamber 115 of the first directional valve 90 to the pressure line 120, and thus also the pump 40, and the control chambers 162, 175 of the directional valves 140, 150 to the tank line 220, and thus also the tank 60. In a cross position (not shown here), however, the control chamber 115 is connected to the tank line 220 and the control chambers 162, 175 to the pressure line 227.

Since all 2/2-way valves 90, 140, 150 are actuated by the same pilot valves 230, 240, the entire arrangement operates in the manner of a forced switching, as a result of which all operating states are clearly defined.

The damping valve unit 20 has a proportional pressure relief valve 250, which closes when de-energized by means of a spring preload and which is controlled or opened via a control current. This ensures that the press can be braked softly via the clutch or brake piston 80 even in the event of an electrical power failure.

A proportional pressure reducing valve 260 enables pressure modulation when soft coupling and different pressure levels when coupling the press by means of coupling piston 80.

A pressure relief valve 270 serves to ensure maximum pressure through the clutch piston 80 driven clutch. The pressure limiting valve 270 prevents an excessively high actuation pressure in the clutch, which could arise, for example, from incorrect control of the proportional pressure reducing valve 260.

Finally, the damping valve unit also has a spring accumulator 290, which ensures a permanent counter pressure in the tank line, in particular during a soft braking phase, and thus enables the press to be braked in a more controlled manner.

The functional sequence of the valve arrangement shown is described in more detail below, reference also to FIG. 2.

In the basic position shown in FIG. 1, the electromagnets 235, 245 of the pilot valves 230 and 240 are de-energized. As a result, the directional control valves 140 and 150 switch to the open position by means of the respective spring preload 180, 190, the inductive switches 145 and 155 being damped. The directional control valve 90 is closed in the basic position and its inductive switch 95 is undamped.

The pump pressure transmitted via the pressure line 120 accordingly acts on the annular surface of the valve piston 105 of the directional control valve 90. At the same time, the directional control valve 90 is held in the closed position via the pilot control valves 230, 240 due to the difference in area between the two piston sides. There is no connection between the pump connection 30 and the working connection 70 and the tank connection 50 and therefore the working connection 70 is relieved of pressure via the tank line 220 and the tank connection 50.

Before switching from the basic position to a switching position, the proximity switch 95 must have the closed, i.e. Acknowledge undamped position. Accordingly, the proximity switches 145 and 155 S2 must open the present, i.e. Acknowledge the damped position.

In the switch position, the electromagnets 235, 245 of the two pilot valves 230, 240 are energized. This relieves the part of the control line 225 leading to the directional control valve 90 to the tank 60. In addition, the directional control valves 140 and 150 are closed. In the switching position, the pump connection 30 is connected to the working connection 70. The connection between the working connection 70 and the tank connection 50, however, is blocked.

A malfunction of one of the pilot valves 230, 240 is now assumed, the electromagnet 245 of the pilot valve 240 being excited and the electromagnet 235 of the pilot valve 230 being de-energized. Therefore, only the directional valve 150 is closed, whereas the directional valve 140 remains open. As a result, the connection between the working connection 70 and the tank connection 50 also remains open. Thus, on Work port 70 do not build up pressure, which is a high safety factor. The malfunction mentioned (circuit) is also recognized as such by the uneven signaling of the proximity switches 145 and 155 in the controller (not shown here).

To detect such or similar malfunctions, the switching of the proximity switches 145, 155 and 95 is checked cyclically during a press stroke.

With the damping valve unit, smooth engagement and braking is achieved.

In the case of soft coupling, in addition to the pilot valves 230, 240, the electromagnet 265 of the proportional pressure reducing valve 260 is also excited, the latter being controlled with current in such a way that the secondary pressure corresponds to the pump pressure. This ensures that the stroke volume flows quickly to the clutch / brake combination. This means that the clutch responds quickly.

When the clutch closes, the flow at the proportional pressure reducing valve 260 is reduced again, as a result of which the secondary pressure drops to the desired soft clutch pressure. After this

Acceleration process, the current at the proportional pressure reducing valve 260 is then increased again, so that the pressure intended for the clutch increases up to a nominal pressure. In contrast, with soft braking, the electromagnets 235, 245 of the series valves 230, 240 are de-energized and the electromagnet 255 of the proportional

Pressure relief valve 250 is energized, the latter being energized so that it opens fully.

The hydraulic switching volume generated by the clutch / brake combination now flows into the tank 60 via the proportional pressure relief valve 250. Shortly before the brake closes, the current at the proportional pressure relief valve 250 is reduced again, so that a pressure builds up in the line leading to the working connection 70. This soft brake pressure acts as a counter pressure and leads to the press being braked softly. The level of the soft brake pressure is determined by the modulation of the proportional pressure relief valve 250.

The damping valve unit therefore enables the start and stop process of the press to be optimized, thus ensuring a high level of safety for the entire production facility. In addition, the operating noise level of the press can be reduced and the mechanical load on the press drive reduced, which leads to longer downtimes of the production facility.

FIG. 1 b shows a valve arrangement corresponding to FIG. 1 a with a damping valve unit that is configured differently from FIG. 1 a 20, but with a matching one

Safety valve unit 10. With regard to the features and the function (s) of the safety valve unit, reference is therefore made in full to the explanations relating to FIG.

In the exemplary embodiment according to FIG. 1b, a directional control valve 300, which is designed in a seat valve design 310 and is connected in parallel to the pressure limiting valve 250, is additionally provided. The directional control valve 300 is controlled by a pilot valve 330. Due to the seat valve design, similar to the directional control valves 140 and 150, high flow values and shorter switching times when braking, especially in the danger area of the press, are made possible. The directional control valve 300 is opened in the de-energized state via a spring force 320 and is in the open position, in particular also in the event of a power failure, in the open position. The open position is monitored by a switch position sensor system 301. The open position of the directional control valve 300 also enables a very fast switching and very effective EMERGENCY STOP or rapid braking of the press (via the piston 80), since an approximately hydraulic pressure in the working line 130 via the lines 223, the tank line 220 , and in particular can be dismantled almost without delay via the line path 222.

Another advantage of the seat valve design of the directional control valve 300 is that the Damping valve unit 20 can be monitored directly via the valve seat 310 of the directional control valve 300, which ensures a particularly high level of safety with regard to the damping behavior.

FIG. 2 illustrates the functional sequence of the valve arrangements shown in FIGS. 1 a and 1 b on the basis of the time sequence of the following variables, which are mentioned from top to bottom in the sequence according to FIG. 2:

Voltage curve 500 on the electromagnets 235, 245 of the pilot valves 230, 240;

Current curve 510 on the electromagnet 265 of the proportional pressure reducing valve 260;

Current curve 520 on the electromagnet 255 of the proportional pressure relief valve 250;

Pressure curve 530 in the clutch / brake combination of the press; such as

Speed curve 540 in the drive shaft of the press.

By actuating the pilot valves 230, 240, these change to the cross position and open the directional valve 90, since the control chamber 115 is now relieved via the tank line 220. Close at the same time the two directional control valves 140 and 150, since their control chambers 162, 175 are acted upon by the pump pressure and the pistons 155, 165 are thereby moved into the sitting position.

After a certain lead time (hydraulic settling time), the pressure at the consumer, here the clutch / brake combination, increases. After a pressure has built up there, the speed on the drive shaft of the press also increases steadily up to a nominal speed. By actuating the proportional pressure reducing valve 260, however, the pressure rise is damped, which overall results in the slow, increasing curve of the speed shown.

After the directional control valves 90, 140, 150 return to the basic position by switching the pilot control valves 230, 240 again, the proportional pressure relief valve 250 is briefly actuated, as a result of which the pressure present at the consumer 80 can be reduced more via the tank line 220. After a time delay, the speed then drops back to the original value.

The switching delay already mentioned when opening the directional valve 90 relative to the directional control valves 140, 150 prevents the formation of a hydraulic short circuit between point A of the directional control valve 90 and the points B of the directional control valves 140, 150. In addition, this starts the press without one Allows soft coupling. Furthermore, the temporal overlap and thus the soft dome pressure can be adjusted externally.

It goes without saying that the valve arrangement according to the invention can be used advantageously not only in mechanical presses, but everywhere where large masses are moved by means of a hydraulically operating clutch and / or brake.

Claims

PATENT CLAIMS

Safety valve unit for operating a hydraulic consumer (80), which is connected to the hydraulic consumer (80) by means of at least one pressure connection (30), by means of at least one working connection (70) to the hydraulic consumer (80) and by means of at least one tank connection (50) is connected to a tank (60) having hydraulic fluid and has at least two working valves (90, 140) which can be actuated by means of at least one electrically controllable control valve (230), characterized in that the at least two working valves (90, 140) are designed as seat valves (110, 170).

2. Safety valve unit according to claim 1, characterized in that the at least two working valves (90, 140) are operated in opposite directions, the first working valve (90) in the open state connecting the pressure connection (30) at least to the working connection (70) and that at least second working valve (140) connects the working connection (70) with the tank connection (50) in the open state.

3. Safety valve unit according to claim 2, characterized in that the at least second working valve (140) by means of a spring force (180) is open when de-energized.

Safety valve unit according to claim 2 or 3, characterized in that the at least two working valves (90, 140) are designed as 2/2-way valves and the at least one control valve (230) as 4/2-way valve, the at least one control valve (230 ) connects the piston chambers of the at least two working valves (90, 140) in opposite directions to the pressure connection (30) and the tank connection (50).

Safety valve unit according to one of the preceding claims, characterized in that the at least two working valves (90, 140) can be actuated by the same at least one control valve (230).

Safety valve unit according to one of the preceding claims, characterized in that at least two second working valves (140) are provided in the form of two 2/2-way valves connected in parallel.

Safety valve unit according to one of the preceding claims, characterized in that the first working valve (90) is activated with a time delay in relation to the at least second working valve (140).

Safety valve unit according to one of the preceding claims, characterized in that the at least two working valves (90, 140) each have an inductive switching position sensor system (95, 145).

9. Damping valve unit, in particular for use with a safety valve unit according to one of the preceding claims, characterized in that a pressure reducing valve (260) is connected upstream of the first working valve (90) on the pressure connection side.

10. Damping valve unit according to claim 9, characterized in that a pressure limiting valve (250) is connected upstream of the at least second working valve (140) on the tank connection side.

11. Damping valve unit according to claim 10, characterized in that the pressure relief valve (250) is closed by means of a spring force.

12. Damping valve unit according to claim 10 or 11, characterized in that a hydraulic spring accumulator (290) is arranged between the at least second working valve (140) and the pressure limiting valve (250).

13. Damping valve unit according to one of claims 9 to 12, characterized in that between the working connection (70) and the tank connection (50) Pressure relief valve (270) is arranged.

14. Damping valve unit, in particular for use with a safety valve unit according to one of claims 1 to 8, characterized by at least one directional control valve (300) arranged on the tank connection side and designed as a seat valve (310).

15. Damping valve unit according to claim 14, characterized in that a pressure limiting valve (250) is connected upstream of the at least second working valve (140) on the tank connection side and that the at least one directional control valve (300) is connected in parallel with the pressure limiting valve (250).

16. Damping valve unit according to claim 14 or 15, characterized in that the at least one directional valve (300) can be controlled by means of at least one control valve (330).

17. Damping valve unit according to one of claims 14 to 16, characterized in that the at least one directional control valve (300) is open when de-energized by means of a spring force (320).

18. Damping valve unit according to one of claims 14 to 17, characterized in that the directional valve has an inductive switching position sensor system (301).

19. Valve arrangement comprising a safety valve unit according to one of claims 1 to 8 and a damping valve unit according to one of claims 9 to 13 or according to one of claims 14 to 18.

20. Press safety valve comprising a safety valve unit according to one of claims 1 to 8 and / or a damping valve unit according to one of claims 9 to 13 or according to one of claims 14 to 18.