Control system, rock drilling rig and method for controlling a connecting means

Abstract

A control system, a rock drilling rig and a method for controlling a coupling means. The control system (CS) is for controlling the coupling and decoupling means of a threaded joint of a rock drilling tool (7). The control system is configured to detect an initial minimum feed force (Ffmin) required to move the rock drilling equipment (6) in a forward direction (FA) and to implement the detected minimum feed force during coupling.

Description

[Background technology]

[0001] The present invention relates to a control system for controlling the coupling and decoupling means of a threaded joint of a rock drilling tool.

[0002] The invention further relates to a rock drilling rig and to a method for connecting threaded joints of a drilling tool.

[0003] The field of the invention is more particularly defined in the preambles of the independent claims.

[0004] In mines and other work sites, different kinds of rock drilling rigs are used to drill drill holes into the rock surface. The drilling rig comprises a rock drill machine with a drilling tool. The drilling tool may comprise several drill rods or tubes and a drill bit at the free end of the drilling tool. The above-mentioned drilling tool components can be connected to each other by means of a threaded joint. Furthermore, the drilling tool can be connected to a shank adapter or a corresponding connection element of the rock drill machine by means of a threaded joint. There are different solutions for implementing the coupling means of the drilling tool. However, the known solutions show some drawbacks. Summary of the Invention

[0005] It is an object of the present invention to provide a new and improved control system and method for controlling the fastening means of a threaded joint of a rock drilling tool. A further object is to provide a new and improved rock drilling rig implementing such a control system and method.

[0006] The control system according to the invention is characterized by the characterizing features of the first independent device claim.

[0007] The rock drilling rig according to the invention is characterised by the characterising features of the second independent equipment claim.

[0008] The method according to the invention is characterized by the characterizing features of the independent method claim.

[0009] The concept of the disclosed solution is that a rock drilling rig is provided with a control system for controlling the coupling and decoupling means of the screw joint of the rock drilling tool. The control system is configured to control the operation of a rotating device and a feeding device of the rock drilling equipment. The rotating device is then rotatable in a coupling and decoupling direction under the control of the control system, and further the feeding device is configured to create a feed movement in a forward direction and a backward direction to perform the coupling and decoupling means. The control system determines a minimum feed force required to move the rock drilling equipment in the forward direction, and then the control system controls the feeding device to feed the rock drilling equipment in the forward direction by utilizing the detected minimum feed force. In other words, only the lowest possible feed force is implemented during the coupling means.

[0010] An advantage of the disclosed solution is that due to the forward motion occurring at a low force level, wear and damage to the screw caused by too strong feed forces can be reduced.

[0011] According to one embodiment, the coupling can be performed downwards, inclined or upwards depending on the drilling situation and the drilling process implemented. The minimum feed force therefore depends on the drilling method used, since gravity will of course have different effects on the minimum feed force in different drilling and coupling directions.

[0012] According to one embodiment, the rock drilling equipment or rock drill may be a rotating head intended for rotary drilling, down-the-hole drilling (DTH), in-the-hole drilling (ITH) or alternatively a tophammer rock drill equipped with an impact device together with a rotating device. Thus, the disclosed solution can be implemented with different drilling methods.

[0013] According to one embodiment, the determined minimum feed force can be considered as a compensation force for forces that impede free movement in the forward direction, which compensates for phenomena such as gravity and static friction that tend to prevent the drilling machine from moving.

[0014] According to one embodiment, the determined minimum feed force may be the support force for supporting the drilling machine when drilling downwards, or the so-called holdback force. It may then be necessary to support the machined hole with a negative feed force against gravity. Also in this case, it is necessary to determine the minimum feed force according to this document.

[0015] According to one embodiment, the feeding device is a hydraulic actuator, such as a hydraulic cylinder or a hydraulic motor. The hydraulic feeding device is connected to a hydraulic circuit for powering it with a flow and pressure of hydraulic fluid. The feeding force is then controlled by adjusting the pressure of the hydraulic fluid supplied to the feeding device, and the feeding rate is controlled by adjusting the magnitude of the fluid flow supplied to the feeding device.

[0016] According to one embodiment, the control system is configured to provide the feed device with a speed request to keep the feed rate at a required level during the coupling procedure. In other words, only one single feed rate request may be implemented for the entire coupling phase. The speed request submitted to the feed device may be a high speed request. The rock drill can then perform a fast and free approaching movement with a low feed force towards the drilling tool, since the forces resisting the feed rate may be low before the actual screwing. However, once the actual screwing starts, the feed rate is automatically determined by the rotation speed and pitch of the threaded flank of the connecting thread. Due to the low feed force, no damage is caused despite the possible high feed rate request. The rotation speed and pitch determine the feed rate during the screwing phase. The advantage of this embodiment is that the free axial movement before screwing can be performed quickly so that the coupling process can be performed quickly. Moreover, due to the low feed force used, there is no risk of damaging the mating threaded parts when they come axially against each other.

[0017] According to one embodiment, the control system is configured to generate a constant rotational speed in the coupling direction during the coupling process and to provide the rotational device with a rotational request for a feed movement in the forward direction. Since the rotation is already on when approaching the threaded contact and the feed force is low, it is not necessary to determine the exact axial position at which the screwing of the threaded parts begins, but instead the approach phase can be smoothly switched to the screwing phase without a separate control means. In that case, the process is simple to control and avoids unnecessary stops. When the threads are in contact, the feed rate is dictated by the pitch and the rotational speed of the threads, i.e. the natural feed rate is added. There is no need to match the rotational speed and the feed rate. This allows the rotational speed to be set freely.

[0018] According to one embodiment, the control system is further configured to initially determine a minimum feed force at the start of the coupling, monitor the forward movement of the rock drilling device until the start of the screwing of the connection screw, and increase the magnitude of the feed force depending on the detected cessation of the forward movement. In other words, a feed-sensing coupling is provided, in which the control system adds an increased magnitude of the feed force to the initially detected minimum feed force depending on the movement monitoring data. This control principle with monitoring and feed force increase is implemented only in the approaching phase. During the screwing phase, a similar control is not necessary, since the feed force is generated automatically due to the torque and pitch used. The advantage of this embodiment is that the system ensures that the required axial movement occurs during the approach, and the lowest possible level of feed force is implemented to generate the forward movement. The control may be automatic without the need for manual control means of the operator. This allows to avoid human errors and allows the operator to concentrate on controlling other issues during the coupling process.

[0019] According to one embodiment, the above mentioned initially determined minimum feed force is implemented as base feed force data to which an increased feed force value is added.

[0020] According to one embodiment, the control system increases the magnitude of the feed force only until forward axial motion occurs and is detected. Thus, the control system continues the forward motion at a resultant feed force that includes the initial minimum feed force and the detected increase in feed force. In other words, the control system ramps up the feed force to generate forward motion, and once motion is detected, the ramp-up ends and forward motion continues at the feed force level determined to maintain motion.

[0021] According to one embodiment, the control system is configured to determine the movement of the rock drilling rig in response to the motion detection data received from the at least one motion detection device. In other words, there may be one or more sensors arranged in association with the feed device or the feed beam for sensing the movement of the rock drilling rig.

[0022] According to one embodiment, the control system is configured to determine the forward motion by calculation. The control system can determine the motion by monitoring the motion of the feeding device and the characteristics of the hydraulic fluid, or possible other driving energy, supplied to the feeding device, and performing comparisons and calculations. For example, the motion detection device can comprise one or more pressure sensors configured to sense the pressure setpoint and the realized pressure value, whereby the control unit can detect the motion by comparing the received pressure sensing data. In this solution, the pressure sensing data serves as the aforementioned motion detection data.

[0023] According to one embodiment, the feeding device controlled by the control system is a hydraulic actuator connected to a hydraulic circuit for supplying pressurized hydraulic fluid to the feeding device to actuate the feeding movement. Furthermore, the control system is configured to detect a minimum pressure of hydraulic fluid supplied to the feeding device required to move the rock drilling rig in the forward direction and implements the detected minimum pressure as a minimum feed force. In other words, the control of the feed force sensing coupling utilizes the lowest possible feed pressure to move the drilling rig in the forward direction during the coupling phase.

[0024] According to one embodiment, the feeding device controlled by the control system is a hydraulic actuator connected to a hydraulic circuit for supplying pressurized hydraulic fluid to the feeding device for actuating the feeding movement. Furthermore, the control system comprises at least one dedicated control device for controlling the pressure of the hydraulic fluid supplied to the hydraulic feeding device during feeding in the forward direction. In other words, the pressure can be controlled by the dedicated control device independently when moving in the forward direction.

[0025] According to one embodiment, the control system comprises a dedicated control device for independent control of the hydraulic pressure supplied to the hydraulic feeding device during feeding in the forward and reverse directions.

[0026] According to one embodiment, the control device mentioned above is a control valve.

[0027] According to one embodiment, the above mentioned control device comprises one or more control elements or actuators for controlling the characteristics of a hydraulic pump or pump unit powering the feed device.

[0028] According to one embodiment, the control system can calculate or determine an additional feed force depending on the detected minimum feed force and can utilize a combination of the minimum and additional feed forces in controlling the feed device. In other words, the control system can add the determined additional or excess feed force to increase the utilized force slightly above the minimum feed force. The advantage of this embodiment is that a continuous movement in the forward direction is guaranteed, e.g. even in situations of changing friction forces.

[0029] According to one embodiment, the above-mentioned additional feed force is calculated in the processor of the control system and is 2-10% of the minimum feed force, so that the implemented feed force is 1.02-1.1 times the minimum feed force.

[0030] According to one embodiment, the disclosed solution relates to a rock drilling rig for drilling drill holes. The rock drilling rig comprises a mobile carrier and at least one rock drilling unit comprising a feed beam and a rock drilling tool movably arranged on the feed beam. The rock drilling tool comprises a rotation device for rotating a drilling tool connectable to the rock drilling unit. A feeding device is arranged for feeding the drilling tool in the drilling direction and in the reverse direction. There is at least one control system for controlling at least the feeding device and the rotation device. The rock drilling tool and the drilling tool are releasably connected to each other by a threaded joint. Furthermore, the control system of the rock drilling rig is in accordance with the features and embodiments disclosed in the present document.

[0031] According to one embodiment, the disclosed solution relates to a method for connecting a threaded joint of a drilling tool, the drilling tool being connectable to a rock drilling apparatus comprising at least a feed device and a rotation device. The method comprises connecting the joint by feeding the rock drilling apparatus in an advance direction by the feed device and performing a simultaneous rotation in the connection direction by the rotation device. The method further comprises determining a minimum feed force required to provide a movement in the advance direction and feeding the rock drilling apparatus in the advance direction with the determined minimum feed force during coupling.

[0032] According to one embodiment, the method includes controlling the feeding device by the control device to maintain a constant feedrate request during the entire joining, in other words, the method includes providing a single feedrate request for the joining to the feeding device.

[0033] According to one embodiment, the method includes performing a rotation in the coupling direction during the entire coupling, in other words, the rotation is already on during the approaching movement, so that the screwing can smoothly start when the connecting threads meet axially.

[0034] According to one embodiment, the method comprises monitoring the forward approaching movement before starting the actual screw tightening and updating the required minimum feed force. The method further comprises implementing the updated minimum feed force to ensure the approaching movement. In other words, if the forward movement stops in the approach phase, a new minimum feed force required to continue the movement is determined. The new minimum feed force then represents an updated compensation force that is implemented in the control of the feeding device. During the screw tightening phase, this control is not implemented.

[0035] According to one embodiment, the method includes using the minimum feed force detected during the tightening phase of the joint as a compensation force, the implemented rotational speed and pitch of the joint's threads defining a nominal feed rate when the threaded elements of the joint are connected to one another.

[0036] The above disclosed embodiments can be combined to form a suitable solution having the above mentioned characteristics required.

[0037] Some embodiments are explained in more detail in the accompanying drawings. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic side view of a rock drilling rig for surface drilling. [Diagram 2] FIG. 1 is a schematic diagram of a rock drill implementing the DTH drilling method. [Diagram 3] FIG. 2 is a schematic side view showing the coupling step for connecting the drilling pipe to the rock drilling rig. [Figure 4] FIG. 2 is a schematic side view showing the coupling step for connecting the drilling pipe to the rock drilling rig. [Diagram 5] FIG. 2 is a schematic side view showing the coupling step for connecting the drilling pipe to the rock drilling rig. [Figure 6] FIG. 2 is a schematic diagram showing some features related to the coupling means; [Figure 7] FIG. 2 is a schematic side view of a portion of a coupling screw, illustrating the principle of determining the nominal feed rate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] For clarity, the figures show some embodiments of the disclosed solutions in a simplified manner.In the drawings, like reference numbers indicate like elements.

[0040] FIG. 1 shows a rock drilling rig 1 intended for surface drilling. The rock drilling rig 1 comprises a mobile carrier 2 and at least one drilling boom 3 connected to the carrier 2. At the distal end of the drilling boom 3 there is a drilling unit 4 provided with a feed beam 5 and a rock drilling device 6 supported thereon. A drilling tool 7 is connectable to the drilling device 6. The rock drilling device 6 may comprise, at the front end of the rock drilling device 6, a shank adapter 8 for connecting the tool 7. The rock drilling device 6 further comprises a rotation device 9 for rotating the shank adapter 8 and the connected drilling tool 7. If the rock drilling device 6 is of the tophammer type, it may further comprise an impact device 10. The rock drill 6 can be moved in a forward direction A and in a reverse direction B on the feed beam 5 by means of a feed device 11.

[0041] The drilling tool 7 may comprise one or more drilling tubes or rods 12 and a drill bit 13 at the distal end of the drilling tool 7. The drilling tool 7 may thus comprise several drilling components connected to each other by connecting threads. There may be a connecting thread between the shank adapter 8 and the drilling tool 7. The coupling of the threaded joints may be controlled under the control of the control system CS according to the features and means disclosed in this document. Figure 1 further discloses a hydraulic system HS comprising one or more hydraulic circuits for powering the hydraulically operable actuators.

[0042] Figure 2 discloses an alternative drilling method in which the disclosed solution can be implemented to couple threaded connections of drilling components. Figure 2 discloses a DTH drilling unit 4 in which an impact device 10 is arranged adjacent to the drill bit 13 and a rotation device 9 or a rotating head is mounted on a feed beam 5. The drilling tool 7 may be connected to the rotation device 9 by a connection screw and there may also be a threaded connection between the drill tube and the other drilling components. The disclosed coupled control system is therefore useful for DTH drilling and also for rotary drilling without an impact device.

[0043] 3 to 5 disclose in a very simplified manner some fastening means of the drilling tool 7.

[0044] The drilling tool 7, in this case the drilling tube, may be supported on the feed beam 5 by one or more support elements 14 such that the drilling tube is aligned on the drilling axis 15. The support means may comprise a holding device or clamp, a manipulator for moving the drilling component between the drilling axis and the drilling component magazine, or any other element or device suitable for providing the necessary support for the drilling component until it is coupled to the rock drilling device 6. The shank adapter 8 or a corresponding rotatable connecting member is provided with a connecting thread and the drilling tool 7. At a first end closest to the shank adapter 8 there is a female end 16 with an internal thread and at a second opposite end there is a male end 17 with an external thread. In FIG. 3 the drilling tool 7 is arranged at an axial distance from the rock drilling device 6, therefore the coupling means comprises axially moving the rock drilling device 6 in the forward direction FA such that the thread and the female end 16 of the shank adapter 8 face each other. This forward movement can be called approaching movement or approaching. The approaching movement is performed with the lowest possible feed force Ffmin. Thus, the magnitude of the minimum feed force Ffmin is determined by detecting the force required to move the rock drilling equipment 6 in the forward direction FA before executing the approach movement. The movement sensing device S may be configured to detect the actual physical movement of the rock drilling equipment and the sensed data may be submitted to a control system CS arranged to control the coupling process and the associated actuators and devices.

[0045] The control system CS is able to generate control commands or requests to the feed device 11 to execute an approaching movement towards the drilling tool 7 with the detected minimum feed force Ffmin. If the approaching movement is stopped due to an increase in the magnitude of the force resisting the approaching movement, the control system CS is able to update the magnitude of the feed force so that the movement can be resumed. Furthermore, the approaching movement can be executed at high speed during the approach and the shank adapter 8 can be rotated in the coupling direction CD already during the approach.

[0046] The control system CS may comprise a processor or data processing device for executing the automatic coupling means. The control system may comprise one or more computers or control units. The control system CS may communicate with a user interface and may receive sensory data from one or more sensing devices S. The sensors S may be, for example, motion detection devices, speed sensors, or position sensors. The control system CS may generate control commands and requests to control elements 18, 19 for controlling properties of the hydraulic fluid directed to the rotating device 9 and the feeding device 11, which may be hydraulic actuators.

[0047] The movement of the rock drilling rig 6 may alternatively or additionally be determined by monitoring characteristics of the hydraulic fluid, such as pressure and flow rate, and performing calculations or comparisons in a processor of the control system. Thus, the hydraulic circuit may comprise, for example, a pressure sensor.

[0048] In Figure 4 the approach movement is completed and the rock drilling device 6 can move in the forward direction FA to start the thread tightening between the shank adapter 8 and the female end 16. When the threads are in contact the feed rate is defined by the pitch and rotational speed of the thread.

[0049] In the disclosed solution, the lowest possible feed force is implemented during the approach movement and the mating faces are not damaged in case of collision, so there is no need to detect the relative position of the shank adapter 8 and the female end 16. The transition from the approach movement or phase to the screwing phase is smooth.

[0050] In Fig. 5 the screw tightening is completed and the drilling tool 7 is properly connected to the rock drilling equipment 6. Fig. 5 further discloses the rotational direction in the uncoupling direction UCD and the feed in the opposite or backward direction FB required when uncoupling the threaded connection between the drilling component and the rock drilling equipment.

[0051] In Figures 3 to 5 a connection between a rock drilling rig 6 and a drilling tool 7 is disclosed, but it can be appreciated that the same principles and means can be implemented, for example, when connecting screws between two drill tubes and between a drill tube and a drill bit.

[0052] Figure 6 is a simplified diagram of the steps of the bonding process and some additional features. These issues have already been extensively disclosed herein above.

[0053] 7 discloses a portion of a coupling thread having a thread surface 20 of pitch P. The coupling thread is rotated in the coupling direction at a rotational speed Rs. A nominal feed rate Nfs, i.e. the natural thread speed, then occurs which depends on the pitch P and the rotational speed Rs.

[0054] The drawings and the associated description are intended only to illustrate the concept of the invention. In its details, the invention may vary within the scope of the claims.

Claims

1. A control system (CS) for controlling the coupling and decoupling means of a threaded joint of a rock drilling tool (7), comprising: the control system (CS) is configured to control the operation of a rotating device (9) and a feeding device (11) of a rock drilling apparatus (6), whereby the rotating device (9) is rotatable in a coupling direction (CD) and a decoupling direction (UCD) and the feeding device (11) is configured to generate a feed movement in a forward direction (FA) and a backward direction (FB); the control system (CS) is configured to determine a minimum feed force (Ffmin) required to move the rock drilling device (6) in the forward direction (FA), the control system (CS) is configured to apply the minimum feed force (Ffmin) when controlling the feeding device (11) to feed the rock drilling equipment (6) in the forward direction (FA); The control system (CS) configured to determine an additional feeding force and configured to add the determined additional feeding force to the minimum feeding force (Ffmin) in the control of the feeding device (11). characterized in that Control System (CS).

2. The control system (CS) is configured to provide a speed request to the feeding device (11) to keep the feeding speed at a required level during the coupling step.

2. The control system of claim 1 .

3. The control system (CS) is configured to determine the movement of the rock drilling device (6) in response to motion detection data received from at least one motion detection device (S).

2. The control system of claim 1 .

4. the feeding device (11) controlled by the control system (CS) is a hydraulic actuator connected to a hydraulic circuit for supplying pressurized hydraulic fluid to the feeding device (11) to actuate the feeding movement, the control system (CS) is configured to detect a minimum pressure of the hydraulic fluid supplied to the feeding device (11) required to move the rock drilling equipment (6) in the forward direction (FA), The control system (CS) is configured to implement the detected minimum pressure as the minimum feed force (Ffmin).

2. The control system of claim 1 .

5. the feeding device (11) controlled by the control system (CS) is a hydraulic actuator connected to a hydraulic circuit for supplying pressurized hydraulic fluid to the feeding device (11) to actuate the feeding movement, The control system (CS) comprises at least one dedicated control device (19) for controlling the pressure of the hydraulic fluid supplied to the hydraulic feeding device (11) during feeding in the forward direction (FA).

2. The control system of claim 1 .

6. The additional feed force is 2 to 10% of the minimum feed force (Ffmin).

2. The control system of claim 1 .

7. A rock drilling rig (1) for drilling drill holes, comprising: The rock drilling rig (1) comprises: a movable carrier (2); At least one rock drilling unit (4) comprising a feed beam (5) and a rock drilling device (6) movably arranged on said feed beam (5), The rock drilling equipment (6) comprises a rotation device (9) for rotating a drilling tool (7) connectable to the rock drilling unit (4) and a feeding device (11) for feeding the rock drilling equipment (6) in the drilling direction (A) and in the reverse direction (B), at least one rock drilling unit (4); at least one control system (CS) for controlling at least said feeding device (11) and said rotating device (9); Equipped with said rock drilling device (6) and said drilling tool (7) being releasably connected to each other by a threaded joint; The rock drilling rig (1) comprises: The control system (CS) of the rock drilling rig (1) is in accordance with any one of claims 1 to 6. characterized in that Rock drilling rig (1).

8. A method for connecting a threaded joint in a drilling tool (7), comprising the steps of: the drilling tool (7) is connectable to a rock drilling device (6) comprising at least one rotation device (9), the rock drilling device (6) being movable by a feed device (11); The method comprises: - connecting the coupling by feeding the rock drilling equipment (6) in an advance direction (FA) by means of the feeding device (11) and performing a simultaneous rotation in a connection direction (CD) by means of the rotating device (9); determining a minimum feed force (Ffmin) required to provide movement in said forward direction (FA); applying the determined minimum feed force (Ffmin) when feeding the rock drilling device (6) in the forward direction (FA) during coupling; Including, The method comprises:

10. A method, comprising: determining an additional feed force; and adding said determined additional feed force to said minimum feed force (Ffmin) when feeding said rock drilling device.

9. performing a rotation in the connection direction (CD) during the entire coupling; The method of claim 8, characterized by:

10. characterized by using the determined minimum feed force (Ffmin) as a compensation force during the tightening phase of the joint, wherein the rotational speed (Rs) and pitch (P) implemented in the threads of the joint define a nominal feed rate (Nfs) when the thread elements of the joint are connected to one another; 10. The method of claim 8 or 9.

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