Water-abrasive cutting system

Abstract

A water-abrasive cutting system includes a cutting head (2) which includes a fixing device (16, 18, 20) for fixing the cutting head (2) on the wall to be cut as well as a nozzle head (10) disposed on the cutting head (2). At least one cutting nozzle (12), for an application of a cutting jet (14), is disposed in the cutting head (2). A cutting monitoring device (26) includes at least one hydrophone (30) and at least one further sensor. The cutting monitoring device (26) is configured to detect a complete penetration and/or cutting-through of the wall on the basis of the sensor signals of the hydrophone (30) and the at least one further sensor.

Claims

1. A water-abrasive cutting system comprising: a cutting head which comprises a fixing device for fixing the cutting head on the wall to be cut and a nozzle head disposed on the cutting head, in which at least one cutting nozzle for application of a cutting jet is disposed; and a cutting monitoring device which comprises at least one hydrophone and at least one further sensor and is configured to detect a complete penetration or cutting-through of the wall on the basis of sensor signals of the hydrophone and the at least one further sensor, the hydrophone being disposed on an outer side of the cutting head such that the hydrophone can come in contact with a liquid surrounding the cutting head, the further sensor measuring a characteristic different from a characteristic measured by the hydrophone.

2. The water-abrasive cutting system according to claim 1, wherein the cutting system is configured for cutting pipes and the cutting head is configured for insertion into a pipe or for arrangement on an outer circumference of the pipe.

3. The water-abrasive cutting system according to claim 1, wherein the nozzle head is disposed rotatably on the cutting head.

4. The water-abrasive cutting system according to claim 1, wherein the at least one further sensor is at least one acoustic emission sensor or at least one acceleration sensor or at least one pressure sensor or any combination of at least one acoustic emission sensor and at least one acceleration sensor and at least one pressure sensor.

5. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is a combination of an acceleration sensor and an acoustic emission sensor, wherein the acceleration sensor and the acoustic emission sensor are configured as an integrated acoustic emission acceleration sensor.

6. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is a combination of an acceleration sensor and an acoustic emission sensor, wherein the acceleration sensor and the acoustic emission sensor are arranged on the cutting head such that the acceleration sensor and the acoustic emission sensor can be brought into a vibration-transmitting communication with a wall to be cut.

7. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is a combination of an acceleration sensor and an acoustic emission sensor, wherein the acceleration sensor and the acoustic emission sensor are disposed in a contact element of the fixing device which is provided for contact against the wall.

8. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is an acceleration sensor, wherein the acceleration sensor is a 3D acceleration sensor.

9. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is a pressure sensor, wherein the pressure sensor is disposed on the cutting head such that the pressure sensor can detect the pressure of a liquid surrounding the cutting head.

10. The water-abrasive cutting system according to claim 3 wherein the fixing device comprises three contact elements distributed over a circumference of the cutting head, which can come in contact with a pipe wall for fixing.

11. The water-abrasive cutting system according to claim 10, wherein one of the contact elements is movable in a radial direction.

12. The water-abrasive cutting system according to claim 10, wherein two of the contact elements are configured to be rigid in a radial direction and are fastened exchangeably on the cutting head.

13. The water-abrasive cutting system according to claim 10, wherein at least one of the contact elements comprises engagement means on a surface provided for contact with the pipe wall, for positive engagement in the pipe wall.

14. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is an acceleration sensor, wherein the cutting monitoring device is configured such that the cutting monitoring device detects a cutting-through of the wall of a pipe from an increase in accelerations detected by the acceleration sensor.

15. The water-abrasive cutting system according to claim 1, wherein the cutting monitoring device is configured such that the cutting monitoring device detects that the cutting jet contains abrasive agent from a change in the sensor signal of the hydrophone.

16. The water-abrasive cutting system according to claim 4, wherein the at least one further sensor is a combination of a pressure sensor and an acoustic emission sensor, wherein the cutting monitoring device is configured such that the cutting monitoring device detects a piercing of the wall from a reduction of the pressure detected by the pressure sensor, a change in the sensor signal of the acoustic emission sensor, or from both a reduction of the pressure detected by the pressure sensor and a change in the sensor signal of the acoustic emission sensor.

17. The water-abrasive cutting system according to claim 1, wherein the cutting monitoring device cooperates with a control device for controlling a drive of the nozzle head in such a manner that an advance movement of the nozzle head is controlled as a function of a signal of the cutting monitoring device.

18. A water-abrasive cutting system for cutting in a liquid environment, the system comprising: a cutting head including a fixing device for fixing the cutting head on a wall to be cut, a nozzle head disposed on the cutting head, in which at least one cutting nozzle for application of a cutting jet is disposed, the cutting head being configured to operate in a liquid of the liquid environment, the liquid surrounding the cutting head during a cutting process; and a cutting monitoring device including a hydrophone and a further sensor, the cutting monitoring device with the hydrophone and the further sensor being configured to detect complete penetration or cutting-through of the wall on the basis of sensor signals of the hydrophone and the further sensor, the hydrophone being arranged on the cutting head and configured to be in contact with the liquid surrounding the cutting head during the cutting process, the further sensor measuring a characteristic different from a characteristic measured by the hydrophone.

19. The water-abrasive cutting system according to claim 18, further comprising: a control unit receiving sensor signals from the hydrophone and the further sensor, the control unit being configured to evaluate the sensor signals in combination to determine cutting through of the wall, said control unit controlling the cutting head based on the sensor signals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a sectional view of a pipe with a water-abrasive cutting system according to the invention;

(3) FIG. 2 is a cross-sectional view of the cutting head in the pipe according to a first embodiment of the invention;

(4) FIG. 3 is a cross-sectional view of the cutting head in the pipe according to a second embodiment of the invention; and

(5) FIG. 4 is an enlarged detail view showing a system element according to FIGS. 1 to 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) Referring to the drawings, the shown water-abrasive cutting system is a water-abrasive suspension cutting system, that is a cutting system in which the abrasive agent is added to the water in the high-pressure region upstream of a cutting nozzle. The cutting system according to the invention comprises a cutting head 2 which is configured for insertion into a pipe 4. The cutting head 2 is connected via a pressure line 6 to a supply unit 8. The supply unit 8 comprises in particular a high-pressure pump which provides water at high pressure, for example, a pressure of 2500 bar or higher. Furthermore the supply unit 8 has an abrasive agent supply. The suspension at high pressure, that is a water-abrasive agent mixture, is supplied via the pressure line 6 to the cutting head 2. During operation the supply unit 8 remains outside the pipe. In offshore applications the supply unit 8 preferably remains above the water surface whilst the cutting head 2, for example, is introduced so far into an oil carrying pipe that it can make a cut below the seabed.

(7) At its front end in the insertion direction in which the cutting head 2 is inserted into the pipe 4, the cutting head 2 has a nozzle head 10 on which a radially directed cutting nozzle is disposed. A radially directed high-pressure cutting jet 14, that is a water-abrasive agent mixture, emerges from the cutting nozzle 12. The nozzle head 10 is rotatable with respect to the cutting head 2 about the longitudinal axis X of the cutting head 2 which corresponds to the longitudinal axis X of the pipe 4. For this purpose, a suitable drive not shown here in detail, for example, a hydraulic drive or an electrical drive, is provided in the cutting head 2. The cutting head 2 furthermore has a fixing device which enables it to be braced in the interior of the pipe 4. The fixing device has three contact elements 16, 18 and 20 in this case. The contact elements 16, 18 and 20 are configured in such a manner that they can come to rest non-positively and/or positively against the inner wall of the pipe 4 and thus brace and fix the cutting head 2 in the pipe 4. In the exemplary embodiment shown in FIGS. 1 and 2, for this purpose only the contact element 18 is fitted with a hydraulic drive 22 acting in the radial direction relative to the longitudinal axis X. The contact elements 16 and 20 are configured to be rigid in this example, that is, they have a fixed radial length relative to the longitudinal axis X. For bracing the cutting head 2 in the interior of the pipe 4, the hydraulic drive 22 is extended in the axial direction so that the contact element 18 is pressed against the inner wall of the pipe 4. As a reaction, the rigid contact elements 18 and 20 are also pressed accordingly against the inner wall of the pipe. The contact elements 16 and 20 are preferably exchangeable so that contact elements 16, 20 of different radial length can be attached to the cutting head 2 to achieve an adaptation to different pipe diameters. In the alternative embodiment shown in FIG. 3, all three contact elements 16, 18, 20 are provided with a corresponding hydraulic drive 22 where all three hydraulic drives are driven radially outwards for bracing. With a uniform movement of the three hydraulic drives of the three contact elements 16, 18, 20, a centering of the cutting head 2 is made possible in the interior of the pipe 4.

(8) As shown in the enlarged view according to FIG. 4, the contact elements 16, 18, 20 can additionally have engagement elements 24 on their surface facing the inner wall of the pipe 4, that is directed radially outwards, which are shown here, for example, in the form of prongs. These engagement elements 24 provide for a positive engagement in the inner wall of the pipe 4 and for a better fixing of the cutting head in the pipe 4. It should be understood that the contact elements 16 and 20 can be configured in a corresponding manner.

(9) The shown cutting system furthermore has a cutting monitoring device. This comprises an evaluation or control unit 26 which is provided, like the supply unit 8, for arrangement outside the pipe 4. The control unit 26 can be integrated in the supply unit 8. Preferably the control device 26 also controls the supply unit 8 and the complete cutting process, that is also the movement of the nozzle head 10 to form the cut in the pipe wall of the pipe 4. Furthermore, the control unit 26 can also control the actuation of the hydraulic drive 22 for bracing the cutting head 2 in the pipe 4. The control unit 26 is connected via a line connection 28 to the cutting head 2. This can be an electrical or, for example, also an optical connection which allows a transfer of data from the control unit 26 to the cutting head 2 and in the converse direction. The line connection 28 can be integrated with the pressure line 8 into one line.

(10) The cutting monitoring device has four different sensors in the cutting head 2. This is on the one hand a hydrophone 30 which is disposed on an outer wall of the cutting head 2 close to the nozzle head 10 and the cutting nozzle 12. This hydrophone 30 detects noise in the liquid which is located in the interior of the pipe 4 during the cutting process. This is in particular liquid emerging from the cutting nozzle 12, that is preferably water. On the other hand, a pressure sensor 32 is disposed on the outer side of the cutting head 2 also in contact with the liquid in the pipe 4. This records the water pressure in the interior of the pipe 4 during the cutting process.

(11) Furthermore, two sensors are provided in the contact element 18 which come in direct contact with the inner wall of the pipe 4 when the contact element 18 is brought in contact with the inner wall of the pipe 4. These are an acoustic emission sensor 34 and an acceleration sensor 36 which are shown here as two separate sensors, but can also be combined in an integrated sensor. The acceleration sensor 36 is preferably configured as a multi-axial, particularly preferably as a tri-axial acceleration sensor. When bracing the cutting head 2 in the interior of the pipe 4, the acceleration sensor 36 is thus brought into a fixed positioning relative to the pipe 4 so that it can detect movements and accelerations of the pipe 4. The acoustic emission sensor 34 detects vibrations in the pipe, in particular those vibrations which are caused by the cutting jet 14. In particular, the vibrations change when the ambient conditions change, i.e. for example, the pipe wall is completely penetrated, the pipe wall is completely separated or cut through etc. The various states can be recognized from the change in the vibrations.

(12) In this example, the pipe 4 is configured to be three-shelled, that is, it comprises three metal pipes 38, 40 and 42 disposed inside one another, where the metal pipe 42 forms the inner wall of the pipe 4 and the metal pipe 38 forms the outer wall of the pipe 4. The free spaces between the pipe 38 and 40 as well as the pipe 40 and 42 are each filled with concrete 44. In the example shown here, the metal pipes 38, 40, 42 are arranged concentrically with respect to one another about the longitudinal axis X and the free spaces are completely filled with concrete 44. It is to be understood however that in practice, the metal pipes 38, 40, 42 can also be arranged non-concentrically with respect to one another and the free spaces can optionally not be completely filled with concrete 44. It can thus be the case that the pipe 4 has a varying wall thickness over the circumference and different consistency of the pipe wall. This makes the monitoring of the cutting process difficult, where this is possible by combining the signals from the four sensors, that is the hydrophone 30, the pressure sensor 32, the acoustic emission sensor 34 and the acceleration sensor 36 in combination. The control unit 26 evaluates the sensor signals in combination.

(13) The cutting process and the cutting monitoring in this case takes place as follows. After inserting the cutting head 2 into the pipe in a desired axial position along the longitudinal axis X, the cutting head 2 is fixed in the pipe 4 by extending the hydraulic drive or drives 22. After fixing, the cutting process is started by initially starting the high-pressure water supply and then the abrasive agent supply via the supply unit 8. This process can particularly preferably be monitored by the hydrophone 30. From the noise in the water which fills the interior of the pipe 4, it can be detected whether only water or a water-abrasive agent mixture is emerging from the cutting nozzle 12. When the emergence of the water-abrasive agent mixture is detected, the cutting process begins, where the nozzle head 10 is initially not turned until the cutting jet 14 has completely penetrated the pipe wall, that is, has penetrated completely through the metal pipes 38, 40 and 42 as well as the concrete 44 in the intermediate spaces. This can be detected by means of the acoustic emission sensor 34, with the signal of the hydrophone 30 and the pressure sensor 32 being used at the same time. The signals are evaluated in combination. Thus, for example, the pressure sensor 32 detects a pressure drop in the interior of the pipe 4 and the acoustic emission sensor 34 and the hydrophone 30 must detect, for example, a change of the vibration pattern which it has detected, so that the control unit 26 can conclude from this that the pipe wall of the pipe 4 has been completely cut through. The signal of the pressure sensor 32 alone, for example, would not be sufficient since, after cutting through of the inner metal pipe 42, when for example the free space between the metal pipes 40 and 42 is not completely filled, a pressure drop can already occur without the pipe wall being completely cut through. Conversely, for example, a complete cutting-through of the pipe wall can be concluded from a signal change of the hydrophone 30 and the acoustic emission sensor 34 alone, even when a pressure drop does not occur in the interior of the pipe 4. This can be the case, for example when the outer metal pipe 42 is surrounded by a dense material so that even when the outer metal pipe 38 is completely cut through, this does not result in a pressure drop in the interior of the pipe 4. After completely cutting through the pipe wall of the pipe 4 at a circumferential position, the nozzle head 10 is set in motion where it executes a rotation through 360. The rotational movement is executed slowly in such a manner that the cutting jet 14 always cuts through the total wall thickness of the pipe 4. This is monitored by monitoring the sensors signals of the four said sensors in combination. The rotational speed can be varied in this case by the control unit. For example, the rotational speed can be slowed when regions having thicker wall thickness are reached. A no longer complete cutting-through of the pipe wall is in turn detected from a variation of the signals of the sensors, in particular the vibration signal of the hydrophone 30 and the acoustic emission sensor 34. In particular, an automatic control of the rotation or rotational speed of the nozzle head 10 as a function of the detected sensor signals is possible. The rotational movement or rotational speed is regulated in this case so that the speed of advance is executed as rapidly as possible but as slowly as necessary to ensure a complete penetration of the pipe wall. The complete cutting-through of the pipe can in turn be detected in particular with the assistance of the acceleration sensor 36. When the pipe wall is completely cut through, this can result in a movement of the separated part of the pipe 4 in which the cutting head 2 is fixed, where this movement is detected by the acceleration sensor 36, since this is firmly connected to the pipe 4 via the cutting head 2.

(14) Thus a more reliable detection of the complete cutting-through of the pipe wall can be achieved through the combined evaluation of the sensor signals.

(15) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.