EP2640552B1 - Water abrasive suspension jet cutting system - Google Patents

Description

The invention relates to a water-abrasive suspension jet cutting system according to the preamble of claim 1.

In waterjet cutting, a high pressure water jet with added abrasive is commonly used to cut materials, such as metal. In principle, two different systems are known. The first system is Water Abrasive Injection Cutting. In these systems, water is discharged from a nozzle under high pressure and an abrasive is added directly to the nozzle to the water jet. For this purpose, the water emerging from the nozzle enters a mixing chamber, in which the abrasive is sucked into the liquid jet by injector action. Subsequently, the water-abrasive-air mixture is passed through a Fokussierrohr and strikes the workpiece. This method is used in particular for cutting metal sheets in metalworking. In this process, it is possible to turn on and off the abrasive supply to the nozzle very precisely and quickly, so that accurate contours can be cut. However, since air is added to the high-pressure water jet in the process when adding the abrasive to the abrasive, the cutting performance is limited, in particular for larger cutting dimensions.

The second known system is the water-abrasive suspension jet cutting, by means of which higher cutting performance can be achieved, ie in particular larger material thicknesses and almost all materials can be cut. In this system Also, water is discharged under high pressure from a cutting nozzle. However, the abrasive is not added to the nozzle but the abrasive is added under exclusion of air under system pressure, ie under high pressure, the water well before entering the nozzle. Ie. a water-abrasive mixture, ie a suspension, exits the cutting nozzle under high pressure. Although large material thicknesses can be cut through with this system, starting and stopping the cutting process is associated with a certain delay since the abrasive agent feed can not be switched on and off as quickly as during injection cutting. This is disadvantageous when cuts are to be made with great precision. A water-abrasive suspension cutting machine of this kind is z. B. off US 4,707,952 known.

It is an object of the invention to improve a water-abrasive suspension jet cutting system to the effect that the cutting process can be started and stopped as possible without delay. This object is achieved by a water-abrasive suspension jet cutting machine having the features specified in claim 1. Preferred embodiments will become apparent from the subclaims, the following description and the accompanying figures.

The water-abrasive suspension jet cutting device according to the invention has, like known suspension cutting systems, a high-pressure pump which provides water at high pressure on the output side. Furthermore, the system has a cutting nozzle, which is connected to the high-pressure pump and forms the high-pressure suspension jet for cutting. Ie. a high-pressure suspension jet (water-abrasive suspension) exits this cutting nozzle and is then used to cut a wide variety of materials, for example metal. The cutting nozzle is connected to the high pressure pump a main flow path and a branched off from this Nebenströmungsweg. The secondary flow path passes through an abrasive pressure vessel in which the abrasive is below the system pressure of the system, ie the water pressure generated by the high pressure pump. The water in the bypass passage is passed through and carries the abrasive in the pressure vessel, thus conveying the abrasive into the main flow path. In this way, a suspension is formed under high pressure, which then exits the cutting nozzle.

According to the invention, it is now provided that the secondary flow path opens into the main flow path at a mixing point which is located in a line section adjoining the cutting nozzle and, in particular, is located directly adjacent to the cutting nozzle or in the cutting nozzle itself. This has the advantage that the part of the main flow path through which the suspension flows is kept as short as possible. In such a suspension cutting system, the abrasive agent supply is hitherto stopped by closing a shut-off valve in the bypass passage, so that the water flow passing through the abrasive fluid pressure vessel is interrupted and thus no abrasive is fed into the main flow path. However, the abrasive agent still remaining in the main flow path downstream of the junction of the bypass flow path will be discharged from the cutting nozzle by the continuing main flow, so that the cutting process can not be stopped immediately. By shortening the part of the main flow path through which the suspension is conveyed, the abrasive center part remaining in the main flow path is minimized when turning off the flow through the bypass flow path, so that the follow-up time when shutting off the abrasive supply is shortened and the cutting process can be stopped faster. In this respect, it is preferable to the mixing point between Nebenströmungsweg and main flow path as possible close to the cutting nozzle, in particular immediately adjacent to this or integrated into this, provide. However, the mixture between the main and secondary flow must be upstream of the actual nozzle or outlet, so that the suspension formation takes place under high pressure without air supply in order to achieve the maximum cutting performance.

Preferably, the mixing point of the cutting nozzle upstream is arranged less than 100 cm, preferably less than 50 cm and in particular less than 30 cm apart. In this way, the part of the main flow path through which the suspension is conveyed, d. H. the flow path between the mixing point and the cutting nozzle, shortened, whereby the Abrasivmittelmenge which remains when switching off the Nebenströmungsweges in the main flow path is reduced, and thus the follow-up time when switching off the Abrasivmittelzufuhr is shortened.

More preferably, the mixing point is movable together with the cutting nozzle. Usually, the cutting nozzle is connected to the other plant components, in particular the high-pressure water supply and the Abrasivmittelzufuhr via a hose which allows the mobility of the cutting nozzle in the cutting process. In conventional water-abrasive suspension jet cutting machines, the mixing point at which the secondary flow with the abrasive is mixed with the main flow in the main flow path is upstream of this hose while the cutting nozzle is downstream of the hose, ie, the distance between the mixing point and the cutting nozzle may be several tens or one hundred meters. According to the preferred embodiment of the invention is now provided, the mixing point also downstream of the hose, which allows the mobility of the cutting nozzle to arrange. Ie. in this embodiment, the main flow path and the sub flow path become guided in each case as a hose or movable pipe to the cutting nozzle at least in a section so that it is compared to the rest of the system, in particular the abrasive fluid pressure vessel and the high-pressure pump, movable, but the mixing point between Nebenströmungsweg and main flow can be arranged near the cutting nozzle.

In order to be able to switch the abrasive agent supply into the main flow path faster and more quickly, according to a preferred embodiment, means for generating a back pressure are present at the mixing point. In this case, the means generate such a back pressure at the outlet of the first bypass flow path in the main flow path, that the backpressure prevents the suspension from flowing out of the secondary flow path into the main flow path. Ie. due to the pressure conditions is achieved that a passage of the flow is prevented from the first Nebenströmungsweg in the main flow path.

According to the invention, a second secondary flow path is provided for establishing the counter-pressure at the mixing point, which branches off from the main flow path, preferably upstream of the branch point, to the first secondary flow path. In this second bypass flow path, a check valve is disposed and the second bypass flow path also opens into the main flow path at the mixing point at which the first bypass flow path opens into the main flow path. This embodiment allows a very rapid shutdown of Abrasivmittelzufuhr in such a way that not the flow through the first Nebenströmungsweg is interrupted by means of a downstream of Abrasivmittel-pressure vessel located shut-off valve, but in that in the region of the mixing point, a back pressure is built up, which the outlet of the Abrasive agent suspension from the first Nebenströmungsweg in the main flow path in derogation. Ie. to stop the cutting operation, the shut-off valve is opened in the second Nebenströmungsweg so that it is built up at the mixing point a back pressure, which prevents the flow from the first Nebenströmungsweg can enter the main flow path.

In this way, the shutdown time of the abrasive supply is shortened. In conventional systems in which a shut-off valve is closed upstream of the abrasive pressure vessel, there is still a pressure reduction in the abrasive pressure vessel, which still causes the abrasive supply to run to the main flow path. Such overrun is prevented by stopping the abrasive supply by establishing a back pressure at the exit point of the first bypass flow path.

Further, the second Nebenströmungsweg opens at the mixing channel relative to the first Nebenströmungsweg in the main flow path, so that a rapid build-up of the back pressure at the outlet of the first flow path to prevent the further flow outlet can take place from the first flow path.

Furthermore, the water-abrasive suspension jet cutting system is preferably set or adjustable such that substantially the same or a lower pressure prevails in the first secondary flow path than in the second secondary flow path when the shut-off valve is open. This ensures that, when the shut-off valve in the second bypass flow path is opened to stop the abrasive supply, the flow in the second bypass flow path at the mixing point builds up such a pressure which inhibits the exit of the suspension from the first bypass flow path into the main flow path.

The abrasive pressure vessel has an exit line which is part of the first bypass path and is connected to the mixing point. Through this outlet line, the suspension under high pressure is led to the mixing point, where the suspension then enters the main flow path.

According to a further preferred embodiment, the outlet line is additionally connected in the region of its end facing the abrasive-pressure container via a shut-off valve to the main flow path. Ie. there is a connection between the first bypass flow path and the main flow path in addition to the described mixing point. This connection branches off from the first secondary flow path on the outlet side of the abrasive pressure vessel as close as possible adjacent to the outlet from the abrasive pressure vessel. Furthermore, a shut-off valve is provided in this connection. This connection with the stop valve disposed therein forms a purge line or a purge valve, which is used to reduce the pressure in Abrasivmittel-pressure vessel can. While the pressure in the abrasive canister is reduced by closing the water supply in the bypass flowpath upstream of the abrasive fluid pressure vessel and shutting off the main flow in the main flowpath, in conventional systems, abrasive in the discharge line between the abrasive fluid pressure vessel and the mixing point at which the discharge line or the first Nebenströmungsweg is connected to the main flow path remain. This can lead to an accumulation of abrasive, which can then lead to a clogging of the cutting nozzle when restarting the system. To prevent this, when the system shuts down, the connection between the upstream end of the discharge line and the main flow path can be opened by opening the shutoff valve or purge valve located in that connection be so that pure water from the main flow path in the upstream end of the discharge line, that is preferably introduced immediately adjacent to the outlet opening of the abrasive pressure vessel and thus the outlet line is flushed. In this way, existing abrasive is rinsed in the outlet line so that it can not come to deposits or accumulations of abrasive here. Also, a pressure reduction in the pressure vessel during shutdown of the system can be done via this connection between the outlet line and main flow.

In addition, the compound can also be used to prevent an uncontrolled discharge of abrasive from the abrasive fluid pressure vessel during startup of the system. Ie. the pressure build-up in the abrasive fluid pressure vessel may be at least partially accomplished by opening the connection between the discharge line and the main flow path by opening the shut-off valve disposed therein, thereby forcing high pressure water into the exit side of the abrasive fluid pressure vessel and there contributes to pressure build-up. At the same time the discharge of abrasive from the pressure vessel is prevented. Before the start of the cutting process, the valve is then closed in the connection between the discharge line and the main flow path, so that a transfer of suspension through this connection in the main flow path is prevented and the suspension enters the main flow path near the cutting nozzle only at the mixing point described above.

As described above, it is further preferred in the first Nebenströmungsweg upstream of the Abrasivmittel-pressure vessel, that is arranged upstream of the Abrasivmittel-pressure vessel, a shut-off valve or by-pass valve, through which the flow in the first Flow path can be switched on and off. By interrupting the flow, the Abrasivmittelzufuhr can be interrupted in the main flow path and thus the cutting process, unless a back pressure at the mixing point in the manner described above is used. In such a case, however, the shut-off valve can be used to start up and shut down the system.

The cutting nozzle is also preferably attached to a positioning system and movable over this in at least one direction. The positioning system may be part of a cutting system that can move the cutting nozzle in different directions relative to a workpiece. The cutting system may, for example, have a robot which carries the cutting nozzle and can move by appropriate control in desired paths to perform along these cutting operations in a material. In particular, the nozzle can be movable in at least one plane in two directions, so that it can perform any cutting operations in a flat workpiece. The plant parts for abrasive agent supply, in particular the abrasive fluid pressure vessel and the high-pressure pump are expediently arranged fixed so that they are not movable with the cutting nozzle and the movable cutting nozzle, as described above, via two pressure lines, one for the main flow and one for the first Nebenströmungsweg, connected to the fixed system parts. In the event that a second Nebenströmungsweg should be provided, could still be provided a third pressure line in the form of a flexible hose. Thus, the mixing point described above can be arranged directly on the movable nozzle in order to start and stop the supply of abrasive as quickly as possible. However, it is also conceivable to move the pressure vessel together with the cutting nozzle. Then a solid casing is possible.

Fig. 1

schematisch eine Wasser-Abrasiv-Suspensionsstrahl-Schneidanlage gemäß einer ersten Ausführungsform der Erfindung,

Fig. 2

schematisch eine Wasser-Abrasiv-Suspensionsstrahl-Schneidanlage gemäß einer zweiten Ausführungsform der Erfindung und

Fig. 3a, 3b

eine Detailansicht des Mischpunktes in Fig. 2, wobei in Fig. 3a die Abrasivmittelzufuhr ein- und in Fig. 3b die Abrasivmittelzufuhr ausgeschaltet ist.

The invention will now be described by way of example with reference to the accompanying drawings. In these shows:

Fig. 1

FIG. 2 schematically shows a water-abrasive suspension jet cutting system according to a first embodiment of the invention, FIG.

Fig. 2

schematically a water-abrasive suspension jet cutting machine according to a second embodiment of the invention and

Fig. 3a, 3b

a detailed view of the mixing point in Fig. 2 , where in Fig. 3a the abrasive supply on and in Fig. 3b the abrasive supply is switched off.

The structure of the cutting devices according to the first and second embodiments, which in Fig. 1 and 2 are shown, is largely identical, so that the identical parts are described together below.

The cutting system has a pressure source in the form of a high-pressure pump 2, which provides water under high pressure for the system. In the flow direction, a check valve 4 connects to the high-pressure pump. Downstream of the check valve 4, the flow path branches into a main flow path 6 and a first bypass 8. The main flow path continues through a high pressure hose 10 to a mixing chamber 12 which is disposed adjacent to the cutting nozzle 14. Instead of a hose 10, a pipe could also be used. Through the main flow path 6, only water is passed. The Nebenströmungsweg 8 passes through a check valve or bypass valve 16 to the abrasive pressure vessel. By the Shut-off valve 16, the Nebenströmungsweg 8 can be opened to the Abrasivmittel-pressure vessel 18 and closed. In the Abrasivmittel-pressure vessel 18 is the abrasive and the flow through the Nebenströmungsweg 8 is passed with open shut-off valve 16 through the abrasive and exits on the output side through the discharge line 20 then together with the abrasive as a suspension from the abrasive pressure vessel 18. The first Nebenströmungsweg 8 then runs downstream of the pressure vessel 18 through a high-pressure hose or hose 22 also to the mixing chamber 12, in which then at a mixing point 24, the flow from the first Nebenströmungsweg 8 flows into the flow in the main flow path 6, so there is a diluted suspension is formed, which then flows on to the cutting nozzle 14. From the cutting nozzle 14 then exits a high-pressure water jet with abrasive, which is used for cutting a workpiece 26.

The cutting nozzle 14 is movable relative to the workpiece 26 via a positioning system 28, which is indicated here only by the directions of movement, to perform the desired cutting movements for forming cuts in the workpiece 26. In order to ensure the mobility of the cutting nozzle 14, the fixed equipment parts are connected via the high-pressure hoses 10 and 22 with the mixing chamber 12 and the cutting nozzle 14. In the example shown, the mixing chamber 12 and the cutting nozzle 14 are fixedly arranged relative to one another, in particular fixedly connected to each other or optionally also integrated into a component.

Characterized in that the abrasive is passed through the first Nebenströmungsweg 8 via a separate hose 22 to the mixing chamber 12, it is achieved that the mixing point 24 in the mixing chamber 12 as close as possible to the cutting nozzle 14, preferably directly adjacent thereto or only minimally spaced can be. In this way, the line section between the mixing point 24 and the outlet opening of the cutting nozzle 14 is shortened. This has the advantage that when closing the shut-off valve 16, when the flow through the first Nebenströmungsweg 8 and thus the supply of abrasive is prevented in the Hauptströmungsweg 6, only little abrasive is discharged by the continuing flow through the main flow path 6, namely in Essentially only the abrasive, which is located when switching off the flow in the first Nebenströmungsweg 8 between the mixing point 24 and the outlet opening of the cutting nozzle 14. In this way, a faster shutdown of the cutting process can be achieved by interrupting the Abrasivmittelzufuhr.

An even faster shutdown can in the embodiment according to Fig. 2 be achieved. In the embodiment according to Fig. 1 there is still a certain amount of caster when the shut-off valve 16 is closed, ie, a portion of abrasive agent is still discharged from the hose 22 into the mixing chamber 12 and thus the main flow path due to pressure reduction, in particular in the pressure vessel 18. Conversely, when opening the shut-off valve 16, the tube 22 must first be completely filled with abrasive again until a stable cutting process is achieved. This lead and lag can in the embodiment according to Fig. 2 be shortened. In the embodiment according to Fig. 2 In addition, a second Nebenströmungsweg 30 is provided, which branches off from the main flow path 6 upstream of the check valve 4 and is provided with a shut-off valve 32. The second secondary flow path 30 leads via a further high-pressure hose or hose 34 to the mixing chamber 12, where it also opens into the main flow path 6 at the mixing point 24. In this embodiment, not only by closing the shut-off valve 16 in the second bypass passage 8 upstream of the pressure vessel 18, the abrasive supply can be inhibited, but also This is done by the shut-off valve 32 is opened in the second Nebenströmungsweg 30, whereby additionally high-pressure water is fed to the mixing point 24 and there a back pressure to that from the first Nebenströmungsweg 8 and builds up the tube 22 exiting suspension, which then prevents the exit of the suspension at the mixing point 24.

This is in the schematic representation of the mixing chamber 12 in the Fig. 3a, 3b shown closer. Fig. 3a shows the opened abrasive supply. In this, a flow through the Nebenströmungsweg 8, which passes through the Abrasivmittel-pressure vessel 18 and thus promotes abrasive to the mixing point 24. At the mixing point 24, the suspension from the first Nebenströmungsweg 8 enters the flow of the main flow path 6 and the thus diluted suspension is passed on to the cutting nozzle 14. The check valve 32 in the second bypass flow path 30 is closed in this state, ie, there is no back pressure at the junction 36 of the second bypass flow path 30 in the main flow path 6, so that the flow from the bypass flow path 8 can freely enter the main flow through the main flow path 6. Now, when the check valve 32 is opened in the second Nebenströmungsweg 30, is at the junction 36, as in Fig. 3b produces a flow and a back pressure which pushes the suspension into the secondary flow path 8 or prevents its exit at the mixing point 24 by the higher pressure generated in the main flow path 6 by the second secondary flow path. As a result of the main flow in the main flow path 6 and the second bypass flow in the second bypass flow path 30, an at least equal or preferably higher pressure is built up at the mixing point 24 than prevails in the secondary flow path 8, so that the exit of the suspension is prevented. At the same time, the suspension in the Nebenströmungsweg 8 and held in particular in the tube 22, so that the cutting operation can be resumed very quickly by the back pressure is prevented by closing the shut-off valve 32 and then very quickly back abrasive from the second flow path to the main flow in the first flow path 6 is supplied.

Another detail is according to both embodiments Fig. 1 and 2 present, namely an additional connection 38 between the discharge line 20 and the main flow path 6. In the example shown here, the connection 38 is connected to the first Nebenströmungsweg 8 upstream of the check valve 16. Ie. this connection is independent of the position of the shut-off valve 16. The connection 38 opens into the discharge line 20 at the end adjacent to the abrasive-pressure container 18, ie, upstream of the hose 22. In the connection 38, a purge valve 40 is arranged through which the connection 38 can be opened or closed. When shutting down the system when the pressure in the pressure vessel 18 is reduced, this purge valve 40 can be opened, so that pure water from the main flow path 6, the abrasive pressure vessel is bridged into the outlet line 20 and the hose 22 is passed to flush it. In this way, abrasive residues, which remain in the tube 22 at shutdown, are flushed out of this. During normal operation of the system, the purge valve 40 is closed, so that a backflow of suspension from the abrasive pressure vessel in the main flow path 6 via the connection 38 is not possible. Even when starting up the system, the purge valve 40 can be opened, so that via the connection 38 in the outlet line 20, a pressure is built up, via which the abrasive-pressure container 18 is pressurized. When the abrasive fluid pressure vessel 18 is pressurized via the exit side, unwanted discharge of abrasive is prevented when the system is started up. The Pressurization can be done simultaneously by opening the shut-off valve 16 via the inlet side, so that a Abrasivmittelaustrag can be prevented in both directions when starting the system from the abrasive pressure vessel.

LIST OF REFERENCE NUMBERS

2

- High pressure pump

4

- Check valve

6

- Main flow path

8th

- first secondary flow path

10

- Tube

12

- mixing chamber

14

- Cutting nozzle

16

- shut-off valve

18

- abrasive pressure vessel

20

- outlet pipe

22

- Tube

24

- Mixture point

26

- Workpiece

28

- Positioning system

30

- Second bypass flow path

32

- shut-off valve

34

- Tube

36

- confluence

38

- Connection

40

- Purge valve

Claims (8)

1. A water abrasive suspension jet cutting installation with a high-pressure pump (2), a cutting nozzle (14), a main flow path (6) which connects the high-pressure pump (2) to the cutting nozzle (14) and with a first auxiliary flow path (8) which branches from the main flow path (6) and which leads through an abrasive means pressure container (18), wherein
   the first auxiliary flow path (8) runs out into the main flow path (6) at a mixing point (24) which is situated on a conduit section (12) adjacent the cutting nozzle (14),
   characterised in that a second auxiliary flow path (30) branches from the main flow path (6), in which second auxiliary flow path at least one shut-off valve (32) is arranged and which at the mixing point (24) runs out into the main flow path (6) in a manner lying opposite to the first auxiliary flow path (8).
2. A water abrasive suspension jet cutting installation according to claim 1, characterised in that the mixing point (24) is distanced by less than 100 cm, preferably less than 50 cm from the cutting nozzle (14) in the flow direction.
3. A water abrasive suspension jet cutting installation according to claim 1 or 2, characterised in that the mixing point (24) is movable together with the cutting nozzle (14).
4. A water abrasive suspension jet cutting installation according to one of the preceding claims, characterised in that means are present for building up such a counter-pressure at the mixing point (24), that this counter-pressure prevents an exit of the flow out of the first auxiliary flow path into the main flow path (6).
5. A water abrasive suspension jet cutting installation according to one of the preceding claims, characterised in that the cutting installation is set or can be set, in a manner such that essentially the same or a lower pressure prevails in the first auxiliary flow path (8) than in the second auxiliary flow path (30), given an opened shut-off valve (32).
6. A water abrasive suspension jet cutting installation according to one of the preceding claims, characterised in that the abrasive means pressure container (18) comprises an exit conduit (20) which is part of the first auxiliary flow path (6) and is connected to the mixing point (24), wherein the exit conduit (20) in the region of its end facing the abrasive means pressure container (18) is connected to the main flow path (6) via a shut-off valve (40).
7. A water abrasive suspension jet cutting installation according to one of the preceding claims, characterised in that a shut-off valve (16) is arranged in the first auxiliary flow path (8) at the entry side of the abrasive means pressure container (18).
8. A water abrasive suspension jet cutting installation according to one of the preceding claims, characterised in that the cutting nozzle (14) is fastened on a positioning system (28) and via this can be moved in at least one direction.

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