DE3015411C2 - Stamp control - Google Patents

Description

a) a pressure-controlled 3/2 way filling valve (5) with two switching pistons, which is switched on in front of the check valve (7) in a filling line (6) leading from the high pressure line (P) to the pressure chamber of the stamp (1) , can be acted upon by the setting valve (2) on a switching piston;

b) a pressure-controlled 3/2 way shut-off valve (8) with two switching pistons is shunted on the filling valve (5) is connected and during the setting process in the open position via » a control line (12) connected to the second switching piston of the filling valve (5);

c) a pressure-controlled 2/2-way shut-off valve (9) in the discharge line (11) leading from the pressure relief valve (10) to the return line (R ) is connected with the switching piston in the bypass to the filling valve (5) and during the Setting process held in the closed position;

d) a switching piston of the shut-off valve (8) is with liquid from the drain line (11) of the Pressure relief valve (10) can be acted upon;

e) the valves (5) and (8) are each connected to a connection with the return line (R) .

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3. Control for a hydraulic ram according to claim I and 2, characterized in that the second switching piston of the filling valve (5) connected to the shut-off valve (8) to a specific Minimum switching pressure is set.

4. Control for a hydraulic ram according to claim 1 to 3, characterized in that the Robbery line (13) connected to the robbery valve (3) in shunt with the second switching piston of the shut-off valve (8) is connected.

5. Control for a hydraulic ram according to claim 1 to 4, characterized in that the Pressure relief valve (10) is set to a lower pressure than the set pressure in the High pressure line (PJt f> 5

The invention relates to a control for a hydraulic ram according to the preamble of Claim 1.

DE-OS 28 30 510 discloses a method for controlling the setting pressure of the hydraulic ram Schreitausbau known to be used to achieve that the setting pressure corresponds to the setting pressure. With the help of this procedure, the punches should already be at Set the maximum possible load given by the pressure relief valve to the hanging wall to be able to control it better through even support. The pressure relief valve is used for this during the setting process by means of a pressure-controlled which can be acted upon by the ram valve in the bypass 2/2 way shut-off valve separated from the pressure chamber of the ram and after the end of the setting process reconnected to the stamp pressure chamber. In this way, the flow through the pressure relief valves during the setting process by a pressure above the set pressure in the High pressure line can be avoided. However, the set pressure of pressure relief valves varies in a certain spread. As a result, those stamps whose pressure relief valves are relative are set low, absorb too high a pressure during setting and when switching on again the pressure relief valve after the completion of the setting process, hydraulic fluid will flow out. on the other hand If the pressure relief valves are set too high, the punches will not match the ones set Achieve pressure. In order to prevent hydraulic fluid from flowing out after setting, the Stamp can be set with a pressure below the mean setting pressure. In which proposed method assumes that the pressure in the high pressure line is constant and that the The setting valve remains open until the stamp is fully loaded. However, these requirements are in an ongoing mining operation hardly achievable. In the pressure supply network of a step support equipment there are often considerable pressure fluctuations because a large number of pressure medium consumers are involved connected is often several of which are operated at the same time. It is also to be expected that not all setting valves are held in the open position by the operating team until the stamp have absorbed the full set pressure.

The aforementioned control can according to Glückauf 114 (1978), No. 19, pages 859 to 860 to one automatic readjustment control can be expanded. A control valve is used to connect to the high-pressure line connected post-flow valve is applied and switched to the opening position. The stamp printing room is then connected to the high pressure line in parallel with the punch set line, so that the The setting process is continued even after the manual control via the post-flow valve has ended. At the same time, the pressure-controlled 2/2 way valve, which is the pressure relief valve from the ram pressure chamber separates during the replenishment process, via a shuttle valve connected in the bypass applied. The pressure relief valve remains inoperative until the control valve for the Make-up valve is switched back to the return line. But since there is no guarantee that this will be the case is carried out, the ram can be relieved of pressure when the pressure relief valve is switched off from the hanging wall can be damaged.

In DE-OS 30 29299, which is not part of the prior art, there is already one automatic stamp control has been proposed, which makes the stamp independent of pressure fluctuations in the high pressure line and the duration of the actuation of the plunger setting valve by the operator can be set with the prescribed setting test. Through a shunt in the stamp set line When the punch post-setting device is switched on, a setting valve that can be actuated manually and under pressure control becomes after a predetermined minimum setting pressure has been built up in the pressure chamber of the stamp so long automatically in Open position held until the specified setting pressure is reached. That to the pressure chamber of the stamp connected pressure relief valve can flow through if the pressure in the high pressure line until the pressure relief valve is raised to the set pressure.

The control device known from DE-AS 21 46 502 is connected to an operating pressure line with approximately 300 bar and connected to another high pressure line with about 400 bar. The stamp is first set by the ram control valve with the operating pressure at the same time on a switching piston the sequence valve connected to the 400 bar line is effective. As soon as there is a certain pressure in the stamp has built up, the sequence valve opens so that up to Shutdown of the stamp control valve from both supply sources at the same time pressure medium to Stamp - flows. This control device requires a second pressure relief valve, the overflow of which is open a second, the first opposing Schah piston of the sequence valve is passed. When on pressure equilibrium is reached on both switching pistons, the sequence valve switches under the action of a Spring off the pressure line.

Another control device, referred to as automatic reset, for tightening the stamp A predetermined stamp setting pressure is known from DE-OS 27 49 312. One to the stamp set line The connected switching valve switches to the high pressure line and at a minimum pressure of 50-150 bar acts on the switching piston of an adjustment valve, which also opens to the high pressure line and the Pressure fluid is applied to the ram pressure chamber via a second setting line opening into the first setting line. The stamp set lines branch off to a second switching piston, which is opposite to the first of the add-on valve. As soon as there is pressure equilibrium on the two switching pistons, the adjustment valve should switch back and cut off the further pressure supply from the high pressure line. This assumes that the pressure on the first switching piston can flow off via a further pressure relief valve, or the switching valve open to the high pressure line switches to the return line.

The invention is based on the object of providing a control for hydraulic rams of the initially introduced to train specified genus so that each stamp regardless of the duration of operation of the Set valve can be set exactly with the set pressure of the pressure relief valve assigned to it can.

This object is achieved with the means specified in the characterizing part of the main claim. the advantageous embodiment of the invention is the subject of the subclaims.

In the punch control according to the invention the setting process of each stamp is regulated via the pressure relief valve assigned to it. Of the The pressure chamber of the ram remains independent of the duration of the actuation of the setting valve as long as the High pressure line connected until the set pressure is reached on the pressure relief valve and the Stamp has absorbed the greatest possible pressure. The setting valve creates a hydraulic circuit applied, which remains open in the hydraulic self-holding function so ίο until the shutdown occurs Liquid overflows from the pressure relief valve. A small amount is sufficient for this Amount of liquid that emerges from the pressure relief valve when it is opened briefly

is set high pump pressure, which is above the Set pressure of the pressure relief valves is the guarantee that all stamps of a longwall equipment be set with the greatest possible pressure. The stamp control according to the invention works automatically and independently of temporary pressure fluctuations in the high-pressure line. For safety reasons the control can be set so that the automatic repositioning of the stamp on the full set pressure only begins when the stamp already has a certain minimum load of, for example 200 bar. This avoids the ram extending in an uncontrolled manner and that stone falling from the hanging wall is caused by the resetting process. The initiated setting process can be switched off immediately by briefly activating the robbery valve.

The invention is explained further below with reference to the drawing. It shows
F i g. 1 a circuit diagram of the stamp control in the unpressurized state,

2 shows a circuit diagram of the stamp control during the automatic setting,

3 shows a circuit diagram of the stamp control during the robbery.

• »ο The ram control is connected to a high pressure line P , which is fed from a pump station (not shown) with a relatively high pressure of 400 bar, for example. The control valves to be described below are still connected to a return line R leading back to the pump station.

The setting process of the punch 1 is triggered with a 3/2 way setting valve 2, which forms a structural unit with a 3/2 way robbery valve 3. Both valves 2 and 3 are alternately either hydraulically piloted or manually operated with a common control lever in what is known as dead man's control. From the setting valve 2, a setting line 4 leads to one of two parallel switching cams of a pressure-controlled 3/2-way filling valve 5 to which a triple-branching filling line 6 is connected. Via branch 6a of the filling line 6, pressure fluid is fed from the high pressure line P to the pressure chamber of the stamp 1, which is protected by a hydraulically releasable check valve 7 located in the filling line 6. Branch Sb leads to a connection of a 3/2-way shut-off valve 8 provided with two switching pistons. Branch 6c acts on the switching piston of a pressure-controlled 2/2-way shut-off valve 9. The pressure chamber of the stamp 1 is protected by a pressure berry valve 10. The overflow from the pressure relief valve 10 opens into the drain line 11

branches with 11a to one of the two switching pistons of the shut-off valve 8 and with u to the input of the shut-off valve 9. The outlet of the shut-off valve 9 is connected to the return line R. The second switching piston of the filling valve 5 is connected to the cut-off valve 8 via a control line 12. It is designed so that it only brings the filling valve 5 into the switching position when it is subjected to a certain minimum pressure of, for example, 200 bar. From the robbery valve 3, a branching robbery line 13 leads with 13a to the annular space of the plunger 1, with 13b to the unlocking piston of the check valve 7 and with 13c to the second switching piston of the shut-off valve 8.

In the case of the FIG. 1, the plunger 1 can be set in the unpressurized state because the pressure chamber is secured by the check valve 7 and the pressure limiting valve 10. The multi-way valves 2, 3, 5 and 9 are open to the return line R. The control line 12 is also depressurized via the shut-off valve 8 which is open to the filling valve 5.

The in F i g. The setting process shown in FIG. 2 is triggered by actuating the setting valve 2. When the setting valve 2 is open, a pressure pulse from the high pressure line P is applied to the first switching piston of the filling valve 5 via the setting line 4. The filling valve 5 is opened to the high pressure line P and pressure fluid flows via the filling line 6 or 6a through the opening check valve 7 into the pressure chamber of the stamp 1. The fluid displaced from the annular space of the stamp 1 when it is set passes via the Lines 13 through the robbery valve 3 into the return line R. During the setting process, the pressure fluid branches further via the line 6b through the open shut-off valve 8 into the control line 12 to the second switching piston of the filling valve 5 and via the line 6c to the switching piston of the shut-off valve 9. This switches to the closed position and separates the overflow of the pressure relief valve 10 released into the line 11 from the return line R. However, the second sound piston of the filling valve 5 only responds when the specified minimum pressure in the pressure chamber of the stamp 1 and in the line system 6 and 12 of, for example, 200 bar is reached. The filling valve 5 is then automatically held in the open position by the second switching piston, so that the setting process is continued even if the setting valve 2 is closed again in the meantime. While the minimum setting pressure in the pressure chamber of the plunger is built up after a relatively short period of actuation of the setting valve 2, the further loading of the plunger to the set pressure of 370 bar, for example, usually requires a longer time, because the pressure in the high-pressure line Pin is due to a simultaneous reduction in operation The pressure taken from several working cylinders often drops considerably and only gradually builds up to the full pressure level.

As soon as the pressure set on the pressure valve 10 of the stamp 1 is reached, hydraulic fluid begins

in to flow from the pressure chamber of the stamp 1 via the opening pressure relief valve 10 into the line 11. Since the shut-off valve 9 is closed, the outflowing liquid reaches the first switching piston of the shut-off valve 8 via the line 11a. The control line 12 to the return line R is opened with the switching process that is triggered. As a result, the second switching piston of the filling valve 5 is relieved, so that it returns to the closed position and the line system 6 also to the return line R

- "opens. This ends the setting process. To switch off the control line 12, very small ones are sufficient Cross-sections and a correspondingly small amount of liquid that is lost when the Pressure relief valve 5 from the pressure chamber of the

When the pressure in the line 6c is relieved, the shut-off valve 9 switches to the open position and connects the line 116 from the pressure relief valve 10 to the return line R. If the stamp is further increased due to the pressure of the rock, the liquid flowing off at the pressure relief valve 10 now flows into the return line R.

The in F, i g. The robbery process shown in FIG. 3 is triggered with the robbery valve 3. The line 13 is connected to the high pressure line P. The incoming pressure fluid is routed via branches 13a to the annular space of the plunger 1, via 13b to unlock the check valve 7 and via 13c to the second switching piston of the shut-off valve 8, whereby the two valves 7 and 8 to the return line Λ are opened. The liquid displaced from the pressure chamber when the ram 1 is screwed in flows through the line 6a via the check valve 7 and the filling valve 5 to the return line R.

The automatic setting process can be interrupted if necessary by a short robbery impulse. By acting on the switching piston of the shut-off valve 8 connected to the line 13a, the control line 12 , which activates the setting process, is connected to the return line R , so that the filling valve 5 goes into the closed position, in which the filling line 6 for the return flow Line R is open.

For this purpose 3 sheets of drawings

Claims (2)

Patent claims: 1. Control for a hydraulic ram of a step extension with a 3/2-way setting valve and a 3/2-way robbery valve for alternately loading the two piston sides of the ram with hydraulic fluid from a high-pressure line and for connecting the loaded piston side to a return -Line, where the load-bearing> o pressure chamber of the ram is secured against the high-pressure line by a hydraulically releasable check valve and against the return line by a spring-loaded pressure relief valve, characterized in that the supply of pressure fluid from the high-pressure line (P) to the pressure chamber of the ram (1) can be regulated with the liquid flowing from the pressure relief valve (10) to the return line (R). 2. Control for a hydraulic ram according to claim 1, characterized by the following features: