Device for controlling drilling parameters during extraction of the drill string

Abstract

The invention relates to a device (2) for controlling a rock drilling machine (3) during the extraction of a drill string (6) from a borehole, the rock drilling machine (3) being movably arranged on a feeder (7), the device comprising: - an actuator (10) arranged to move the rock drilling machine (3) along the feeder (7) in a direction opposite to the drilling direction; - a rotary motor (9) arranged to rotate the drill string (6); and - an actuator controller (4) arranged to control the actuator (10) during the extraction of the drill string (6) from the borehole, the actuator controller (4) being arranged to control the actuator (10) according to a first mode or a second mode on the basis of an operating parameter, such as a torque (Tq) generated by the rotary motor (9) to rotate the drill string, wherein the actuator controller (4) is arranged to control, in the first mode, a movement speed (v) of the rock drilling machine (3) moved by the actuator (10), and wherein the actuator controller (4) is arranged to control, in the second mode, a force (F) provided by the actuator (10) to move the rock drilling machine (3). The invention also relates to a rig (1).

Description

Technical Field

[0001] This invention relates to an apparatus for controlling operating drilling parameters during the removal of the drill string from the borehole. The invention also relates to a drilling rig incorporating such an apparatus. Background Technology

[0002] In the field of rock drilling technology, different drilling parameters, such as the rotational speed of the drill string, the feed force acting on the drilling machine, and the impact force, are continuously monitored and controlled throughout the drilling operation.

[0003] After drilling is completed, the drill string is retrieved from the borehole one by one, preferably in a manner that takes the least amount of time. This can be achieved by pulling the drill string backward at a constant and relatively high speed while keeping it continuously rotating.

[0004] A potential problem is that the drill string may get stuck somewhere inside the hole during drill string removal. Typically, this means the drill string will need to be re-intaken until it can be removed again by restarting the backfeed or pull-back operation. This is troublesome, not only because it is time-consuming, but also because it can create unwanted tension in the drill string and / or other parts of the drilling equipment. While the drill string is generally very strong in its axial direction, i.e., in the drilling direction, it is not equally strong in the orthogonal directions, meaning that forces that may be generated in those directions during a deadlock could damage parts of the drill string.

[0005] It would be advantageous to develop apparatus and methods that overcome or at least mitigate at least one or more of the disadvantages of the prior art. In particular, it would be advantageous to find apparatus and methods that minimize downtime caused by undesirable deadlocks. Summary of the Invention

[0006] The object of this invention is to provide an apparatus and method for retrieving a drill string from a borehole in an efficient manner that reduces the risk of downtime and / or material damage. This object is achieved by means of the invention according to the first and second aspects.

[0007] According to a first aspect, the present invention relates to an apparatus for controlling a rock drilling machine during the removal of a drill string from a borehole, the rock drilling machine being movably arranged on a feeder, the apparatus comprising:

[0008] - An actuator arranged to move the rock drilling machine along the feed in a direction opposite to the drilling direction.

[0009] - A rotary motor, arranged to rotate the drill string, and

[0010] - An actuator controller, arranged to control the actuator during the removal of the drill string from the borehole, the actuator controller being arranged to control the actuator according to a first mode or a second mode based on at least one operating parameter from a parameter set, the parameter set including: a representation of the torque generated by a rotary motor for rotating the drill string, a representation of the rotational speed of the drill string provided by the rotary motor, a representation of the force provided by the actuator for moving the rock drilling machine in a direction opposite to the drilling direction, and a representation of the movement speed of the rock drilling machine provided by the actuator.

[0011] The actuator controller is configured in a first mode to control the speed at which the actuator moves the rock drilling machine in the opposite direction to the drilling direction, and in a second mode to control the force provided by the actuator to move the rock drilling machine in the opposite direction to the drilling direction.

[0012] The advantage of this device lies in its ability to switch between a first mode and a second mode. The first mode should be used when environmental conditions allow the device to quickly remove the drill string from the borehole. Conversely, the actuator can operate in a more fail-safe second mode when preventative measures are deemed necessary based on given operating parameters. This provides overall fast and reliable operation without compromising the functionality of the drilling equipment.

[0013] According to an embodiment of the present invention, the actuator controller is configured to switch the control of the actuator from a first mode to a second mode in response to at least one operating parameter from the parameter set exceeding or falling below a first threshold.

[0014] This is an advantageous way to initialize operations according to the second mode when needed.

[0015] According to an embodiment of the present invention, the actuator controller is configured to switch the control of the actuator from a first mode to a second mode when the representation of the torque generated by the rotary motor exceeds a first torque threshold.

[0016] The torque generated by the rotary motor can be advantageously used as a trigger to control the actuator between different modes during drill string removal and to provide a way to automate the removal operation.

[0017] According to an embodiment of the invention, the actuator controller is configured to switch the control of the actuator from a first mode to a second mode in response to an increase in the representation of torque generated by the rotary motor at a rate exceeding a first threshold rate, for example, by a derivative coefficient exceeding a first derivative coefficient.

[0018] According to an embodiment of the invention, the rotation controller is arranged in a second mode to control the rotation motor of the drilling machine to maintain the rotation speed at a first rotation speed or at a speed higher than the first rotation speed.

[0019] This is advantageous because rotation will prevent the drill string from becoming blocked.

[0020] According to an embodiment of the invention, the rock drilling machine is a hydraulic rock drilling machine, and wherein the representation of the torque generated by the rotary motor is determined based on the representation of the rotational pressure of the hydraulic fluid supplied to the rotary motor to drive the rotary motor to rotate.

[0021] According to an embodiment of the present invention, the actuator controller is arranged to control the actuator at a movement speed corresponding to a first movement speed in a first mode.

[0022] A constant speed is advantageous because it allows for rapid drill string removal operations.

[0023] According to an embodiment of the invention, the actuator controller is arranged to control the actuator at a second moving speed, which is less than the first moving speed, when the take-out operation is restarted after confirming that the drill string is blocked.

[0024] This is advantageous because it reduces the risk of operational failure when sensitively restarting the take-out operation.

[0025] According to an embodiment of the invention, the actuator controller is arranged to switch the control of the actuator from a second mode to a first mode when the representation of the torque is below a second torque threshold: the torque is provided by a rotary motor and used to generate a rotational speed of the drill string corresponding to a first rotational speed.

[0026] This is advantageous because it provides the actuator controller with a reliable way to revert from operating in the second mode to the faster first mode.

[0027] According to an embodiment of the present invention, the actuator includes a hydraulic motor, and wherein the actuator controller is a control device configured to control the supply of hydraulic fluid to the actuator, and wherein the actuator controller controls the flow of hydraulic fluid supplied to the actuator in a first mode and controls the pressure of the hydraulic fluid supplied to the actuator in a second mode.

[0028] This is an advantageous way to control a hydraulic motor in either of two different modes, depending on the dominant environment.

[0029] According to a second aspect, the present invention relates to a drilling rig comprising a rock drilling machine and, as described above, means for controlling the movement of the rock drilling machine during the removal of a drill string connected to the rock drilling machine from a drilled borehole.

[0030] Further embodiments of the invention according to three aspects, as well as the advantages of the invention, will become apparent from the detailed description and accompanying drawings. Attached Figure Description

[0031] Specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0032] Figure 1 This is a very schematic view of a portion of a drilling rig according to one aspect of the invention.

[0033] Figure 2 This is a schematic diagram of a feeder having an apparatus according to one aspect of the present invention.

[0034] Figure 3 This is a schematic diagram of an apparatus according to one aspect of the present invention.

[0035] Figure 4 is a schematic diagram illustrating the progress of existing technology devices over time.

[0036] Figure 5 This is a schematic diagram illustrating the development of a device based on one aspect of the invention over time.

[0037] Figure 6 This is a schematic diagram illustrating the development of an alternative aspect of the invention over time, and

[0038] Figure 7 This is an illustrative scheme of an apparatus according to a specific embodiment of the present invention. Detailed Implementation

[0039] exist Figure 1 The image schematically shows a drilling rig 1. The drilling rig 1 includes a feeder retainer 12 disposed at the outer end of an extendable boom 11. The feeder retainer 12 is arranged to carry the feeder, which is preferably arranged in a manner that allows it to move relative to the feeder retainer 12.

[0040] The drill rig 1 shown is merely an example of a drill rig that can use the apparatus of the present invention. The apparatus of the present invention can be used in various applications, including down-the-hole drilling and in-hole drilling, wherein the impact unit is arranged at the outer end of the drill string located inside the borehole during drilling operations. A rotary unit is preferably arranged on the feeder located outside the borehole. The drill rig 1 may also include a rock drilling machine arranged on the feeder.

[0041] exist Figure 2The diagram schematically illustrates the drill rig's feeder 7. The feeder 7 is mounted on a feeder retainer 12, which is preferably located on the boom, for example... Figure 1 The extended boom 11 shown is located at its outer end. Typically, the feeder 7 is displaceable relative to the feeder holder 12 in its axial direction, and the feeder holder 12 is preferably tiltable relative to the boom 11. The rock drilling machine 3 is movably arranged on the feeder 7 such that the rock drilling machine 3 can move back and forth along the length of the elongated feeder 7.

[0042] The rock drilling machine 3 includes a rotary motor 9 arranged to provide a rotational speed R to a drill string 6 configured to drill a hole in, for example, rock, via a drill string retainer 8. Depending on the application and type of drilling rig, the rock drilling machine 3 may include both the rotary motor 9 and an impact unit; however, in some applications, the impact unit is arranged at the outer end of the drill string, such that it can be said that the rock drilling machine 3 is composed of the rotary motor 9. In this application, the term "rock drilling machine" 3 is used in a broad sense to cover any drilling machine that is movably arranged and includes any type of rotary motor arranged to drive the drill string to rock, etc.

[0043] An actuator 10 is arranged at the feeder 7 to move the drilling machine 3 in a direction opposite to the drilling direction in order to retrieve the drill string 6 from the inside of the borehole. Specifically, the actuator 10 may be a device arranged to move the rock drilling machine 3 back and forth along the elongated feeder 7, and may include one or more hydraulic motors, specifically hydraulic cylinders. Such a device can be more robust in the forward drilling direction because pushing the drill string into the rock requires more power than removing the drill string 6 from the borehole. However, given that the rock drilling machine 3 is driven forward, the opposite arrangement is also possible, where the actuator 10 can be arranged to be more robust in the direction opposite to the drilling direction. In a particular embodiment, the actuator 10 may also be a single actuator arranged to move the drilling machine 3 only in a direction opposite to the drilling direction to retrieve the drill string 6 from the borehole.

[0044] exist Figure 3 The diagram schematically illustrates a device 2 for controlling the operation of the rock drilling machine 3 during the removal of the drill string 6 from the borehole. The drilling rig 1, which includes this device, is shown as a box enclosing the entire device 2.

[0045] The device 2 includes an actuator controller 4 arranged to control the actuator 10. Conventionally, the actuator 10 is configured to extract the drill string 6 from the borehole at a constant speed. In the device of the present invention, the actuator controller 4 is arranged to control the actuator 10 according to a first mode or a second mode based on at least one operating parameter. The operating parameter is preferably one of the following: a representation of the torque Tq generated by the rotary motor 9; a representation of the rotational speed R of the drill string 6 provided by the rotary motor 9; a representation of the force F provided by the actuator 10 to move the rock drilling machine 3; and a speed v of movement of the rock drilling machine 3 in the direction opposite to the drilling direction provided by the actuator 10.

[0046] The actuator controller 4 is arranged in a first mode to control the speed v of movement of the rock drilling machine 3 caused by the actuator 10 in the opposite direction to the drilling direction, and in a second mode to alternatively control the force F provided by the actuator 10 to move the rock drilling machine 3 in the opposite direction to the drilling direction.

[0047] Under normal circumstances, the actuator 10 is preferably controlled according to the first mode, that is, the speed v of the actuator 10 that causes the rock drilling machine 3 to move in the opposite direction to the drilling direction is controlled. In other words, in the first mode, the operation of removing the drill string 6 can usually be performed relatively quickly. The second mode is intended for use when there is a risk of encountering problems in the operation of removing the drill string 6, that is, when passing through narrow passages with accumulated rock that may obstruct the drill bit located at the outer end of the drill string 6 and cause the removal operation of the drill string 6 to stop.

[0048] One aspect that may need to be considered when choosing between a first mode and a second mode is that anticipating when to switch from one mode to another may be useful. For example, obstacles or obstructions may accumulate over time or appear immediately, making the need to switch from the first mode to the second mode potentially gradual or immediate. Therefore, the invention includes the step of monitoring at least one operating parameter so that the actuator controller 4 can control the actuator 10 according to said operating parameter. The operating parameter may be selected from a set of parameters including: a representation of the torque Tq generated by the rotary motor 9, a representation of the rotational speed R of the drill string provided by the rotary motor 9, a representation of the force F provided by the actuator 10 to move the rock drilling machine 3, or a representation of the movement speed v of the rock drilling machine 3 provided by the actuator 10. The actuator controller 4 may also control the actuator 10 according to: more than one operating parameter, wherein each parameter can be compared with a separate threshold; and / or a specific combination of parameters, wherein at least two parameters are combined into a common value that can be compared with a common threshold.

[0049] The actuator controller 4 is arranged in a first mode to control the movement speed v of the rock drilling machine 3 caused by the actuator 10 to be set to a first movement speed v1 by providing a variable force F according to the resistance encountered by the actuator 10. If the resistance increases, the actuator 10 will need to provide an increased force F to keep the movement speed v at the first movement speed v1.

[0050] The actuator controller 4 is arranged to alternatively control the force F provided by the actuator 10 to move the rock drilling machine 3 in the second mode. Therefore, the moving speed v of the rock drilling machine 3 caused by the actuator 10 will vary depending on the resistance encountered by the actuator 10 in moving the rock drilling machine 3. Typically, in the second mode, the moving speed v of the rock drilling machine 3 caused by the actuator 10 will decrease, and the moving speed v will be inversely proportional to the resistance encountered by the actuator 10 in moving the rock drilling machine 3. However, in the second mode, if the drill string 6 can be removed without encountering any significant resistance, the moving speed v may also increase uncontrollably.

[0051] The device may also include a rotary drive controller 5, which is arranged to control the rotational speed R provided to the drill string 6 by the rotary motor 9 of the rock drilling machine 3. If no problems occur, the rotational speed R is controlled to a first rotational speed R1 by providing a variable torque Tq according to the resistance encountered by the drill string, the resistance being overcome by the power of the rotary motor 9, so that the rotational speed R is maintained at the first rotational speed R1.

[0052] exist Figure 3 The diagram illustrates that the actuator controller 4 can receive feedback from both the rotary motor 9 and the actuator 10 of the rock drilling machine 3. The feedback may include a representation of the force F provided by the actuator 10 and a representation of the torque Tq provided by the rotary motor 9. The feedback may also include a representation of the drill string rotational speed R provided by the rotary motor 9 and a representation of the rock drilling machine 3's travel speed v provided by the actuator 10. Sensors may be arranged to monitor the drill string rotational speed R and the rock drilling machine 3's travel speed v.

[0053] The force F and torque Tq can be represented as direct force and torque provided by actuator 10 and rotary motor 9, respectively. For hydraulic actuator 10 and hydraulic rotary motor 9, these representations can be provided by the pressure of the hydraulic fluid supplied to actuator 10 and rotary motor 9, respectively. In the illustrated embodiment, actuator 10 is illustrated as a hydraulic cylinder whose movable piston is connected to rock drilling machine 3 via connector 13 to move rock drilling machine 3.

[0054] For electric motors, these representations can be based on the delivered current that drives the actuator 10 and the rotary motor 9, respectively.

[0055] According to the present invention, the actuator controller 4 can act in the form of force F and torque Tq according to the received feedback, so as to keep the moving speed v at a desired first moving speed v1.

[0056] In the following and accompanying figures, it is assumed that the representations of different parameters, namely torque Tq, force F, rotational speed R, and translational speed v, correspond to the actual values ​​of these parameters. However, it should be noted that the actuator controller 4 will control the actuator 10 according to the representations of the relevant parameters, which can be implemented in various ways, but these representations should correspond to the actual values ​​of the relevant parameters as closely as possible.

[0057] The actuator controller 4 is arranged in a second mode to allow the movement speed v of the rock drilling machine 3 to develop below a first movement speed v1 by alternatively providing a limited force F to the actuator 10. The actuator controller 4 can be arranged to switch the drive of the actuator 10 from the first mode to the second mode in response to an increase in the torque Tq exceeding a first torque threshold Tq1. In response, the movement speed v of the rock drilling machine 3 can be reduced to below the first movement speed v1 by limiting the force F provided by the actuator 10.

[0058] Figure 4 illustrates a typical prior art scenario, where different operating parameters are shown as a function of operating time t. These different operating parameters are: the moving speed v of the rock drilling machine 3 caused by the actuator 10, the force F provided by the actuator 10 to move the rock drilling machine 3, the torque Tq generated by the rotary motor 9, and the rotational speed R of the drill string provided by the rotary motor 9.

[0059] In the first part of the diagram, there are no obstacles and the drill string can move backward at a constant speed v, i.e., in the opposite direction of drilling. This constant speed v can correspond to a desired and preset first speed. Additionally, the rotational speed R can be maintained at a constant speed corresponding to the desired and preset first rotational speed. At time t1, the drill string encounters an obstacle that hinders its movement and rotation.

[0060] In the conventional setup shown, when the drill string encounters an obstacle hindering its movement and rotation, in an attempt to maintain the travel speed v at a desired first travel speed and the rotational speed R at a desired first rotational speed, both of the following will increase: the feed force F, such as the feed pressure for a hydraulic drive; and the torque Tq, such as the rotational pressure for a hydraulic rock drilling machine. This may be successful for smaller obstacles, such as small rocks stuck between the drill string and the borehole. However, in the typical scenario shown, this will lead to an operational failure where the drill string will become stuck after both the rotational speed R and the travel speed v suddenly decrease until time t2, at which time both the feed force F and the torque Tq are at their respective preset maximum values, but the rotational speed R and the travel speed v are both zero.

[0061] This type of operational failure can typically be resolved by reversing the direction of drill string movement, i.e., by using actuator 10 to push the drill string back into the borehole while the drill string 6 is being rotated by rotary motor 9. This may or may not be successful. There is always a risk that the drill string will be immediately blocked or jammed when restarting drill string 6 removal. In all cases, operational failures will complicate operations and result in undesirable time losses, and may also create undesirable tension on the drill string, potentially damaging the rock drilling machine 3 and / or the drill rod of drill string 6.

[0062] According to embodiments of the present invention, blockage of the drill string 6 can be largely avoided. Furthermore, if the drill string becomes blocked, operation can be restarted in a more fail-safe mode, which can be considered to some extent as an anti-blockage mode that minimizes the risk of drill string blockage.

[0063] exist Figure 5 The diagram illustrates, in a very schematic manner, the operation of retrieving a drill string controlled according to an embodiment of the invention. When there are no obstructions, the operation can proceed according to a first mode; however, once an obstruction is noticed at time t1, the difference from the prior art becomes apparent. In the illustrated embodiment, torque Tq serves as a trigger, inducing actuator controller 4 to control actuator 10 according to a second mode. During operation, torque Tq is estimated based on its representation; for hydraulic drilling rigs, torque Tq can be estimated based on the rotational pressure provided by a rotary motor in the drilling rig. When the representation of torque Tq exceeds a first torque threshold Tq1, actuator controller 4 is triggered to control actuator 10 according to the second mode.

[0064] Alternatively, the actuator controller 4 can be configured to control the actuator 10 from a first mode to a second mode in response to an increase in the torque Tq generated by the rotary motor 9 at a rate exceeding a preset first rate. In other words, the derivative coefficient DTq / dt of the torque Tq generated by the rotary motor 9 exceeds a preset first derivative coefficient DTq / dt1. Figure 5 In this context, a preset first rate, for example in the form of derivative coefficient DTq / dt1, can be exceeded in the portion between time t1 and time t2 illustrated, wherein the torque Tq increases at a higher rate, such that the increase of torque Tq is accelerated and exceeds the preset first rate.

[0065] During the time period after time t1, instead of increasing the force F and torque Tq to a preset maximum level as in the prior art, the drill string will be removed according to a second mode, in which the force F is controlled and the moving speed v is allowed to be reduced to below the first moving speed v1.

[0066] In the second mode, the actuator controller 4 can control the actuator 10 by adjusting the force F provided by the actuator 10 to move the rock drilling machine 3. Specifically, the actuator controller 4 can control the movement of the rock drilling machine 3 by adjusting a first force threshold F1 that the force F should not exceed. For example, the actuator controller 4 can control the movement of the rock drilling machine 3 by lowering the first force threshold F1 in response to a change in the representation of torque Tq that is higher than the first torque threshold Tq1. In subsequent stages of operation according to the second mode, the force F is controlled in response to the representation of torque Tq, wherein an increase in the representation of torque Tq may mean a decrease in force F. In a specific embodiment, as long as the actuator controller 4 controls the actuator 10 according to the second mode, the force F remains at a low, constant level.

[0067] In the illustrated embodiment, an obstacle that causes an increase in force F and / or torque Tq will not lead to operational failure. Instead, the obstacle can be disabled, allowing operation to resume normally. Disabling is preferably achieved by keeping the rotational speed R at a constant first rotational speed R1, which is further achieved by increasing the torque Tq provided by the rotary motor 9 while limiting the force F provided by the actuator 10, thereby reducing the movement speed v of the rock drilling machine 3.

[0068] Specifically, the device 2 includes a rotary drive controller 5, which is arranged to control the rotational speed R supplied to the drill string 6 by the rotary motor 9 of the rock drilling machine 3. The rotary drive controller 5 can be arranged to maintain the rotational speed R at a first rotational speed R1 or at a speed higher than the first rotational speed R1, even when the torque Tq has reached a first torque threshold Tq1.

[0069] At time t2, the torque Tq has fallen below a second torque threshold Tq2, which is lower than a first torque threshold Tq2. This is noticed by the actuator controller 4 from a feedback signal indicating that the torque Tq has fallen below the second torque threshold Tq2. Therefore, at time t2, the actuator controller 4 will revert to controlling the actuator 10 according to a first mode, in which the actuator controller 4 controls the movement speed v of the rock drilling machine 3 caused by the actuator 10. Specifically, the actuator controller 4 controls the actuator 10 to provide a movement speed v corresponding to a first movement speed v1. Therefore, in the first mode, the rock drilling machine 3 should move at a constant movement speed v corresponding to the first movement speed v1. In the first mode, the actuator controller 4 controls the flow of hydraulic fluid supplied to the actuator 10, and in the second mode, the actuator controller 4 controls the pressure of the hydraulic fluid supplied to the actuator 10.

[0070] The rock drilling machine 3 can be a hydraulic rock drilling machine, wherein the torque Tq generated by the rotary motor 9 can be determined based on the pressure delivered to the rotary motor 9 to drive the rotary motor 9 to rotate.

[0071] Alternatively, the rock drilling machine can be an electric rock drilling machine, wherein the torque Tq generated by the rotary motor 9 is determined based on the current supplied to the rotary motor 9 to drive its rotation. In such an embodiment, the actuator controller 4 can be a control unit configured to control the power supply to the electric motor 7 arranged to move the rock drilling machine 3.

[0072] exist Figure 6 The diagram shows a very schematic representation of a second operation, which is controlled by a device according to the invention, to remove the drill string from the borehole.

[0073] In the first part of the representation, before the indicated time t1, there are no obstacles, and the drill string can move backward at a constant speed v corresponding to the desired first moving speed v1, i.e., in the opposite direction of drilling. Furthermore, the rotational speed R can be maintained at a constant rotational speed corresponding to the desired first rotational speed R1. During this phase corresponding to the first mode, both the force F provided by the actuator 10 and the torque Tq provided by the drilling machine 3 can be maintained at a fairly constant and fairly low level.

[0074] At time t1, the drill string encounters an obstacle hindering its movement and / or rotation. Therefore, at this point, both the force F provided by actuator 10 and the torque Tq provided by drill rig 3 need to increase to maintain the moving speed v at the first moving speed v1 and the rotational speed R at the first rotational speed R1. In the illustrated scenario, the actuator controller 4 does not react quickly enough, such that when the torque Tq exceeds the first torque threshold Tq1, the actuator controller 4 does not have time to limit the force F provided by actuator 10. Therefore, the result will be the same as in the prior art, i.e., the drill string will be blocked. At time t2, the drill string is blocked, and both the moving speed v and the rotational speed R are zero.

[0075] At time t3, the retraction operation is restarted "backward," that is, restarted in the normal drilling direction, to release the drill string from its blocked position. Therefore, starting at time t3, a negative force is applied to the actuator, causing the blocked drill string to be pushed further into the borehole at a negative velocity v, and at time t4, the negative force is reversed into a force F suitable for removing the drill string from the borehole again. At this point, the rotational speed R has reached the desired first rotational speed R1.

[0076] The difference in this phase is that the desired movement speed decreases to a second movement speed v2. Therefore, instead of restarting the operation in the second mode, it restarts in the first mode, but at a second movement speed v2, which is lower than the first movement speed v1. The second movement speed v2 is reached at time t5, and the movement speed v remains at the second movement speed v2 from time t5 to time t6.

[0077] When the drill string re-enters the area where the obstruction is located, resistance increases, and therefore the force F provided by actuator 10 and the torque Tq provided by drill rig 3 need to be increased to maintain the moving speed v at the second moving speed v2 and the rotational speed R at the first rotational speed R1. At time t6, the torque Tq provided by drill rig 3 reaches above the first torque threshold Tq1, which triggers actuator controller 4 to control actuator 10 according to a second mode. In the second mode, the force F provided by actuator 10 will be limited to the first force threshold F1, which decreases in response to the increase of Tq provided by drill rig 3. Therefore, starting from time t6, the moving speed v that allows the actuator to move drill rig 3 and drill string 6 will develop below the second moving speed v2.

[0078] Therefore, the second movement speed v2 set upon restarting in response to a blockage will allow the actuator controller 4 to control the actuator 10 to react promptly to any obstacles that appear. Furthermore, with the aid of the reduced second movement speed v2, the rapid switching from the first mode to the second mode allows passage through obstacles within the borehole without jamming the drill string again.

[0079] It should be noted that restarting in the second mode may have the risk of causing the movement speed v of the actuator, which moves the drilling machine 3 and drill string 6, to increase uncontrollably. This could cause problems if the drill string 6 enters a troublesome area, as it could lead to severe or at least uncontrolled impacts, potentially damaging various components of the drilling equipment. Therefore, given the obvious risk of repeated blockages due to re-entry into an area with known obstacles, the movement speed v is alternatively controlled to a second movement speed v2, which is lower than the first movement speed v1.

[0080] At time t7, the torque Tq provided by the drilling machine 3 falls below the second torque threshold Tq2. This triggers the actuator controller 4 to control the actuator 10 according to the first mode, where the actuator 10 is again speed-controlled, i.e., controlled to move the drilling machine at a specific travel speed v, which in this case should correspond to the first travel speed v1. As a more fail-safe alternative, the operation can alternatively continue according to the first mode, but at a specific travel speed v corresponding to a lower second travel speed v2. This is an operational choice that the operator can decide in the event of an accident and / or according to a preferred set of preset operating parameters.

[0081] In addition, the movement speed v can be preset to a specific value based on various operating parameters, such as the type of drill bit used and the hardness of the rock drilled out of the borehole. n .

[0082] At time t8, Tq provided by the drilling machine 3 has reached a low "steady-state" level, and both the rotational speed R and the movement speed v are at preferred levels corresponding to the first rotational speed R1 and the first movement speed v1. This steady state will be maintained as long as the actuator controller 4 does not receive feedback indicating that an obstacle has been encountered. From time t8 onwards, operation will continue according to the first mode as long as no new obstacle appears.

[0083] exist Figure 7 The diagram shows a very schematic representation of a hydraulic scheme according to an embodiment of the present invention.

[0084] In the illustrated embodiment, the device includes a first conduit 14 for a rotary motor 9 and a second conduit 15 for an actuator 10, the second conduit 15 being separate from the first conduit 14. A first pump 16 is arranged in the first conduit 14 to provide flow for driving the rotary motor 9. The first pump 16 may be arranged to provide flow to the rotary motor 9 up to a certain pressure threshold. This can be achieved by a first spring-biased bypass valve 17, which is arranged to open a bypass line 18 through the rotary motor 9 when the pressure in the first conduit exceeds a specific pressure threshold corresponding to a first torque threshold Tq1.

[0085] A second pump 19 is arranged in the second conduit 15 to provide a hydraulic flow for driving the actuator 10. The second pump 19 can be arranged to provide a flow to the actuator 10 up to a certain pressure threshold. This can be achieved by a second spring-biased bypass valve 20, which is arranged to open the bypass line 21 through the actuator 10 when the pressure in the second conduit 15 exceeds a specific pressure threshold corresponding to the first force threshold F1.

[0086] The second spring-biased valve 20, from the first conduit 14 to the second conduit 15, may be provided with a pilot line 22 to control the second spring-biased valve 20 based on the pressure in the first conduit line 14. Specifically, a pilot signal transmitted in the pilot line 22 is used to reduce the pressure threshold required to open the second spring-biased bypass valve 20. Therefore, the second spring-biased bypass valve 20 opens in response to the reduced rotational pressure, and the flow through the actuator 10 decreases, resulting in a reduction in the supply pressure through the actuator 10. Additionally, the movement speed v is thus reduced. Therefore, the pilot line 22 is used to reduce the first threshold force F1 that limits the force provided by the actuator 10.

[0087] The present invention has been described above with reference to specific embodiments. However, the present invention is not limited to these embodiments. It will be apparent to those skilled in the art that other embodiments are possible within the scope of the appended claims.

Claims

1. A device (2) for controlling a rock drilling machine (3) during the removal of a drill string (6) from a borehole, the rock drilling machine (3) being movably arranged on a feeder (7), the device comprising: - Actuator (10), the actuator (10) being arranged to move the rock drilling machine (3) along the feeder (7) in a direction opposite to the drilling direction, - A rotary motor (9), the rotary motor (9) being arranged to rotate the drill string (6), and - An actuator controller (4) is arranged to control the actuator (10) during the removal of the drill string (6) from the borehole. The actuator controller (4) is arranged to control the actuator (10) according to a first mode and a second mode based on at least one operating parameter from a parameter set, the parameter set including: a representation of the torque Tq generated by the rotary motor (9) to rotate the drill string; a representation of the rotational speed R of the drill string provided by the rotary motor (9); a representation of the force F provided by the actuator (10) to move the rock drilling machine (3) in a direction opposite to the drilling direction; and a representation of the moving speed v of the rock drilling machine (3) provided by the actuator (10). In the first mode, the actuator controller (4) is arranged to control the speed v of movement of the rock drilling machine (3) caused by the actuator (10) in the direction opposite to the drilling direction, and in the second mode, the actuator controller (4) is arranged to control the force F provided by the actuator (10) to move the rock drilling machine (3) in the direction opposite to the drilling direction. The actuator controller (4) is configured to switch the control of the actuator (10) from the first mode to the second mode in response to the representation of the torque Tq generated by the rotary motor (9) increasing at a rate DTq / dt exceeding a first threshold rate DTq / dt1.

2. The apparatus (2) according to claim 1, wherein, The actuator controller (4) is configured to switch the control of the actuator (10) from the first mode to the second mode in response to at least one operating parameter from the parameter set exceeding or falling below the first threshold.

3. The apparatus (2) according to claim 1, wherein, The actuator controller (4) is configured to switch the control of the actuator (10) from the first mode to the second mode in response to the torque Tq generated by the rotary motor (9) exceeding a first torque threshold Tq1.

4. The apparatus (2) according to claim 1, wherein, The rotation controller (5) is arranged to control the rotation motor of the drilling machine in the second mode to keep the rotation speed R at a first rotation speed R1 or at a speed higher than the first rotation speed R1.

5. The apparatus (2) according to claim 3 or 4, wherein, The rock drilling machine (3) is a hydraulic rock drilling machine, wherein the torque Tq generated by the rotary motor (9) is determined according to the representation of the rotational pressure P of the hydraulic fluid, which is delivered to the rotary motor (9) to drive the rotary motor (9) to rotate.

6. The apparatus (2) according to claim 1, wherein, The actuator controller (4) is arranged to control the actuator (10) to reach a movement speed v corresponding to the first movement speed v1 in the first mode.

7. The apparatus (2) according to claim 6, wherein, The actuator controller (4) is arranged to control the actuator (10) to reach a movement speed v corresponding to a second movement speed v2 when the take-out operation is restarted after confirming that the drill string (6) is blocked. The second movement speed v2 is lower than the first movement speed v1.

8. The apparatus (2) according to claim 1, wherein, The actuator controller (4) is arranged to switch the control of the actuator (10) from the second mode to the first mode when the torque Tq is provided by the rotary motor (9) and used to generate the rotational speed R of the drill string (6) corresponding to the first rotational speed R1.

9. The apparatus (2) according to claim 1, wherein, The actuator (10) includes a hydraulic motor, and wherein the actuator controller (4) is a control device configured to control the supply of hydraulic fluid to the actuator (10), and wherein the actuator controller (4) controls the flow of hydraulic fluid supplied to the actuator in a first mode and controls the pressure of the hydraulic fluid supplied to the actuator (10) in a second mode.

10. A drilling rig (1) comprising a rock drilling machine (3) and a device (2) according to claim 1, the device (2) being used to control the movement of the rock drilling machine (3) during the removal of a drill string (6) connected to the rock drilling machine (3) from a drilled borehole.

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