WO2007138170A1

WO2007138170A1 - Rock drilling rig and method of controlling thereof

Info

Publication number: WO2007138170A1
Application number: PCT/FI2007/050310
Authority: WO
Inventors: Markus Salonen
Original assignee: Sandvik Mining And Construction Oy
Priority date: 2006-06-01
Filing date: 2007-05-30
Publication date: 2007-12-06
Also published as: FI20065369A; EP2021580A1; FI118778B; FI20065369A0

Abstract

A method for controlling the operation of a rock drilling rig (1), and a rock drilling rig (1 ), comprising setting the set value (p_FEEDsετ) of the feeding pressure (p_FEED) of the feeding apparatus (17) on the basis of the difference variable (Δp_ROT) between the set value (P_ROTSET) and the current value (P_ROTMEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16), and affecting the difference variable (Δp_ROT) between the set value and the current value of the rotating pressure (p_ROT) of the rotating apparatus (16) on the basis of the difference variable (ΔFLOW) between the set value (FLOWSET) and the current value (FLOWMEAS) of the volume flow (FLOW) of the flushing medium.

Description

ROCK DRILLING RIG AND METHOD OF CONTROLLING THEREOF

BACKGROUND OF THE INVENTION

[0001] The invention relates to a method for controlling the operation of a rock drilling rig, which rock drilling rig comprises a feeding apparatus for feeding a tool in a hole to be drilled, a rotating apparatus for rotating a tool in the hole to be drilled, and means for feeding flushing medium into the hole to be drilled to remove from the hole to be drilled the drill cuttings generated in the hole during the drilling, the method comprising setting the set value of the feeding pressure of the feeding apparatus on the basis of the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus.

[0002] Further, the invention relates to a rock drilling rig, which comprises a feeding apparatus for feeding a tool in a hole to be drilled, a rotating apparatus for rotating a tool in the hole to be drilled, and means for feeding flushing medium into the hole to be drilled to remove from the hole to be drilled the drill cuttings generated in the hole during the drilling, and in which rock drilling rig the set value of the feeding pressure of the feeding apparatus is arranged to be set on the basis of the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus.

[0003] Rock drilling rigs and rock drill machines arranged in them are used for drilling and quarrying rock, for example in underground mines, open pit mines and excavation work sites. In the drilling, there are typically four different functions in use simultaneously, i.e. rotating the drill bar in the hole to be drilled, striking rock with a percussion device at a drill bit via a drill shank and drill rods that are extensions to the drill shank, as well as feeding the drill forwards in the hole to be drilled, and flushing with which drilling waste, i.e. drill cuttings, is removed from the hole to be drilled. By contrast, in what are called rotary applications only three functions are in use, because these applications lack the striking of rock by striking it with a percussion device at the drill shank. Further, what are called DTH (Down-The-Hole) applications are used in which the percussion piston is positioned in a drill hole, at the bottom of the hole, and strikes directly at the drill bit instead of the drill shank. Breaking of rock therefore takes place mainly by the effect of the percussion, and the purpose of the rotating is mainly to ensure that the buttons of the bit or other working parts of the drill bit at the outer end of the drill rods always strike rock at a new point. By means of the feed, the contact between the drill bit and the rock is kept sufficient.

[0004] In connection with controlling rock drilling rigs, what is called torque adjustment drilling may be used in which the intention is to keep the rotating torque, i.e. the rotating pressure, of a rotating apparatus of a rock drill machine of a rock drilling rig at its set value by means of the feed force, i.e. the feeding pressure, of the feeding apparatus of the rock drill machine. In torque adjustment drilling, the momentary current value of the rotating pressure of the rotating apparatus is subtracted from the set value of the rotating pressure of the rotating apparatus, which gives the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus. On the basis of this difference variable, the control and adjustment unit sets the set value for the control and adjustment unit of the feed device, on the basis of which value the control and adjustment unit of the feed device adjusts the feeding pressure.

[0005] Nowadays, the torque adjustment applied to the control of drilling does not take the flush of the drilling into consideration in any way. When the monitoring of the flushing medium is activated, the control of the drilling with torque adjustment is interrupted, and the control takes place in accordance with separate exceptional control. In practice, the implementation in use today may allow the flush channel system to clog before any corrective measures are taken, as a result of which the efficiency of the drilling will suffer.

BRIEF DESCRIPTION OF THE INVENTION

[0006] An object of this invention is to achieve a new type of solution for controlling the operation of torque adjustment drilling of a rock drilling rig.

[0007] The method according to the invention is characterized by determining the difference variable between the set value and the current value of the volume flow of the flushing medium and by affecting the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus of the rock drilling rig on the basis of the difference variable between the set value and the current value of the volume flow of the flushing medium.

[0008] The rock drilling rig according to the invention is characterized in that the rock drilling rig further comprises means for determining the difference variable between the set value and the current value of the volume flow of the flushing medium, and at least one control unit for controlling the operation of the rock drilling rig by affecting the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus of the rock drilling rig on the basis of the difference variable of the set value and the current value of the volume flow of the flushing medium.

[0009] The operation of the rock drilling rig, which comprises a feeding apparatus for feeding a tool in a hole to be drilled, a rotating apparatus for rotating a tool in the hole to be drilled and means for feeding flushing medium into the hole to be drilled to remove from the hole to be drilled the drill cuttings generated in the hole during the drilling and in which the set value of the feeding pressure of the feeding apparatus is set on the basis of the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus, can be controlled by determining the difference variable between the set value and the current value of the volume flow of the flushing medium and by affecting the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus of the rock drilling rig on the basis of the difference variable between the set value and the current value of the volume flow of the flushing medium.

[0010] According to an embodiment, a particular amplification coefficient of the difference variable between the set value and the current value of the volume flow of the flushing medium is used to affect the weight value with which the difference variable between the set value and the current value of the volume flow of the flushing medium affects the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus.

[0011] According to an embodiment, the difference variable between the set value and the current value of the volume flow of the flushing medium or information corresponding to it is subtracted from the difference variable of the set value and the current value of the rotating pressure of the rotating apparatus to decrease the feeding pressure of the feeding apparatus when the current value of the volume flow of the flushing medium falls below the corresponding set value.

[0012] By controlling the operation of the rock drilling rig by affecting the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus on the basis of the difference variable between the set value and the current value of the volume flow of the flushing medium, a blockage about to be generated in the flush channel system of the rock drilling rig can be opened before the flush channel system gets completely clogged. As it is possible to actively affect the prevention of the clogging of the flush channel system as early as when the clogging begins to develop, improved efficiency in the long run can be achieved in the drilling. At the same time, functioning of the flushing and an improved quality of the hole are guaranteed and stresses directed at the drilling equipment are reduced. The amplification coefficient of the difference variable between the set value and the current value of the volume flow of the flushing medium enables determination of the weight value with which the difference variable between the set value and the current value of the volume flow of the flushing medium affects the difference variable between the set value and the current value of the rotating pressure of the rotating apparatus in each drilling situation.

BRIEF DESCRIPTION OF THE FIGURES

[0013] Some embodiments of the invention are explained in greater detail in the attached drawings, in which

Figure 1 shows schematically a side view of a rock drilling rig;

Figure 2 shows schematically a principled view of different functions of the rock drilling rig; and

Figure 3 shows schematically an arrangement for controlling the operation of the rock drilling rig.

[0014] For the sake of clarity, some embodiments of the invention are shown simplified in the figures. Similar parts are denoted with the same reference numerals in the figures.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0015] Figure 1 shows schematically the structure of a rock drilling rig 1. The rock drilling rig 1 comprises a movable carrier 2, which is provided with a boom 3, at the free end of which a feeding beam 4 is arranged. Further, the feeding beam 4 is provided with a rock drill machine 5, which can be moved relative to the feeding beam 4. The rock drilling rig 1 and the devices connected to it are operated by means of the power generated by an engine 6 arranged on the carrier 2, whereby the rock drilling rig 1 is a unit moving and functioning independently. The engine 6 is typically an combustion engine, such as a diesel engine. The rock drilling rig 1 according to Figure 1 further comprises a compressor 7 operated by the engine 6, the compressed air generated by the compressor being used for flushing a drill hole 8 to remove the drilling waste, i.e. drill cuttings, from the drill hole 8. Thus, the compressed air used as the flushing medium is fed along a flush channel system from the compressor 7 via the rock drill machine 5 and a tool 10 to the drill hole 8, whereby the drill cuttings detached from the rock are pushed out of the drill hole 8 by means of compressed air. The flush channel system comprises a flush line 9 leading from the compressor 7 to the drill machine 5, and in the drill machine 5 flush channels going through the drill shank, drill bar and drill bit, which channels are not, for the sake of clarity, shown in Figure 1 but whose basic structure and principle are obvious to a person skilled in the art. From the mouth of the drill hole 8, the drill cuttings are sucked along hoses of a collecting system to a dust separator 11. The basic structure and operation of the rock drilling rig 1 and the rock drill machine 5 are known as such to a person skilled in the art, so they are not dealt with in more detail in this context.

[0016] When the rock to be drilled is hard, the need for flushing is rather low. By contrast, in soft rock the need for flushing is great, particularly when a great hole size is used for the drilling, because a lot of drill cuttings are detached from the rock, whereby there is a risk that the flush channel system will be clogged. Further, this may quickly result in clogging of the flushing channels of the drilling equipment and typically of the drill bit, in particular. In addition to the rock quality and the hole size, for example the type of the drill rod and drill bit and the depth of the hole to be drilled affect the need for flushing.

[0017] Figures 2 and 3 show schematically an embodiment implementing the solution. Figure 2 shows schematically, at a general level, arrangement of different functions of the rock drilling rig 1 without the percussion apparatus and parts belonging to it. Figure 3 shows schematically a control arrangement based on torque adjustment. Figure 2 illustrates a flow measuring arrangement 12 arranged in connection with the flush line 9 of the rock drilling rig 1 for measuring the volume flow FLOW of the flushing medium flowing in the flush channel system, i.e. in practice the current value FLOWMEA_S of the volume flow of the flushing medium, in other words in the case of the rock drilling rig 1 shown in Figure 1 , for measuring the volume flow of compressed air. The flow measuring arrangement 12 can also be positioned at a point other than the flush line 9 in the flush channel system. The measuring arrangement 12 of the volume flow FLOW of the flushing medium may comprise, for example, a measuring device based on a Venturi tube and measuring the residual pressure difference of the Venturi tube in a manner known as such. The flow measuring arrangement 12 can be, however, implemented in very many different ways as far as the volume flow FLOW of the flushing medium flowing in the flow channel system or variables comparable with it can be measured in some way. Instead of using a Venturi tube, the difference between the pressures measured at any two different points in the flush channel system may be used for measuring the amount of flow of the flushing medium. Thus, the amount of flow of the flushing medium may be determined for example on the basis of the difference between the pressures on the opposite sides of a directional control valve, or on the basis of the difference between the pressures at the extreme ends of the flush channel system. Typically, the unit used for the volume flow of the flushing medium is m³/min. The information FLOWMEAS expressing the volume flow of the flushing medium is transmitted to a control unit 13 in the rock drilling rig 1. Further, Figure 2 shows schematically a pressure regulating valve 14, which is positioned in the flush channel system and may be used for controlling the pressure of the flushing medium, and a directional control valve 15 for switching the flush on and off.

[0018] When torque adjustment drilling is used in connection with the rock drill machine 5 of the rock drilling rig 1 , the intention is to keep the rotating torque, i.e. rotating pressure p_ROT, of the rotating apparatus 16 of the rock drill machine 5 at its set value P_ROT_SET by means of the feed force, i.e. feeding pressure p_FEED, of the feeding apparatus 17 of the rock drill machine 5. Thus, the rock drilling rig 1 further comprises a pressure measuring arrangement 18, for example a pressure sensor, for determining the current value P_ROTMEAS of the rotating pressure p_ROT of the rotating apparatus 16. In Figure 2, the pressure measuring arrangement 18 is positioned in a pressure medium channel 20 of the rotating device 16 between the rotating apparatus 16 and the directional control valve 21 , which pressure medium channel 20 comes from a rotating pump 19 and conveys pressure medium to the rotating device 16. When the current value P_ROT_MEAS of the rotating pressure falls below the set value p_ROTsετ of the rotating pressure of the rotating device 16, the set value p_FEEDsετ of the feeding pressure of the feeding apparatus 17 is raised, and vice versa.

[0019] The measurement of the current value FL0W_MEAS of the volume flow of the flushing medium can be connected to the adjustment of torque adjustment drilling in such a way that the difference variable between the set value FLOWSET and the current vallue FLOWMEA_S of the volume flow of the flushing medium, determined with a calculating member 30, affects the difference variable Δp_ROT between the set value P_ROTSET and the current value P_ROTMEAS of the rotating pressure. This may be implemented for instance with a calculating member 28 in the manner schematically shown in Figure 3, in such a way that the difference variable ΔFLOW between the set value FLOWSET and the current value FLOWMEAS of the volume flow of the flushing medium or the variables individually are directly subtracted from the set value p_ROTsετ of the rotating pressure p_ROT. If the units of the set value P_ROTSET and the current value P_ROTMEAS of the rotating pressure and the set value FLOWSET and the current value FLOWMEAS of the volume flow of the flushing medium are such that they are not directly comparable with each other, the variables are converted in a manner obvious as such to a person skilled in the art in such a way that they can be processed together, whereby information corresponding to the variables can be processed for example by subtracting them from each other. Alternatively, the difference variable ΔFLOW between the set value FLOWSET and the current value FLOWMEA_S of the volume flow of the flushing medium or the variables individually may naturally be subtracted from the difference variable Δp_ROT between the set value P_ROTSET and the current value P_ROT_MEAS of the rotating pressure. Naturally, it is also possible to use some other calculation order, which gives a corresponding result and is obvious as such to a person skilled in the art, to subtract the difference variable ΔFLOW between the set value FLOW_SET and the current value FLOWMEA_S of the volume flow of the flushing medium or the variables individually either directly or indirectly from the set value P_ROT_SET of the rotating pressure, and thus to affect the difference variable Δp_ROT between the set value P_ROT_SET and the current value P_ROTMEAS of the rotating pressure. When the difference variable Δp_ROT of the adjustment of the rotating pressure p_ROT obtains a negative value, a control and adjustment unit 26 of the rotating apparatus 16 gives a control and adjustment unit 27 of the feeding apparatus 17 a control command CTRL for decreasing the feeding pressure p-FEED. In practice, therefore, the control and adjustment unit 26 of the rotating apparatus 16 thus decreases the set value P_FEEDSET of the feeding pressure p_FEED, as a result of which the control and adjustment unit 27 of the feeding apparatus 17 decreases the feeding pressure p_FEED. The feeding pressure p_FEED can be decreased for example by controlling the adjustment value of the pressure regulating valve 22 of the feeding apparatus. For the sake of clarity, Figure 2 further shows schematically a feeding pump 23 and a pressure medium channel 24 of the feeding apparatus 17 feeding pressure medium to the feeding apparatus 17, as well as a directional control valve 25 of the feeding apparatus 17.

[0020] For clarity, Figure 3 thus shows for both the rotating apparatus 16 and the feeding apparatus 17 separate control and adjustment units 26 and 27, respectively, but these control and adjustment units 26 and 27 may naturally be a part integrated into the control unit 13 of the whole rock drilling rig 1 , as may also calculating means 28 and 30, and an amplification element 29 shown in Figure 3. Hereby, the control unit 13 transmits, in a manner shown schematically in Figure 2, a control variable CTRL to the pressure regulating valve 22 of the feeding apparatus 17 to decrease the feeding pressure p_FEED.

[0021] According to a second embodiment of the solution, the difference variable ΔFLOW between the set value FLOWSET and the current value FLOWMEAS of the volume flow of the flushing medium can be conveyed through a particular amplification element 29, in which amplification or an amplification coefficient K is determined, by means of which the effect of the difference variable ΔFLOW of the set value and the current value of the volume flow FLOW of the flushing medium on the difference variable Δp_ROT between the set value and the current value of the rotating pressure p_ROT can be changed. The amplification coefficient K may be at least partly comparable with the difference variable ΔFLOW of the set value and the current value of the volume flow FLOW of the flushing medium, but the value of the amplification coefficient K may also be affected by other features of the drilling situation. The coefficient K may obtain different values during, for example, start, full-power and finishing drillings. When the coefficient K obtains a negative value, the effect of the difference variable ΔFLOW between the set value and the current value of the flushing medium on the difference variable Δp_ROT of the rotating pressure p_ROT of the rotating apparatus 16 can be set to be reverse. Thus, the coefficient K may obtain any possible positive and negative values, including the value zero. The coefficient K can be set to be zero in cases where it is not desirable that the flush flow affects the adjustment. One such case may be, for example, escaping of the flush flow in fragmented rock, which pould, without management of exceptional cases of the type described above, lead to an undue increase in the feeding pressure, for instance. The amplification coefficient K can, if required, be used for converting the unit of the difference variable ΔFLOW between the set value FLOW_SET and the current value FLOWMEAS of the volume flow of the flushing medium such that it is subtractable from the set value P_ROT_SET of the rotating pressure.

[0022] As the feeding pressure decreases, the drill - rock contact between the drill bit and the rock decreases, which facilitates the functioning of the flushing and thus contributes to opening the flush channel system about to be clogged. Since the measurement information on the flush flow is actively connected to the control of drilling, it is possible to react very quickly to a blockage about to be generated in the flush channel system, before the blockage has a greater effect on the drilling. At the same time, continuous functioning of the flushing and the high quality of the hole are ensured, and stresses directed at the drilling equipment are reduced.

[0023] The rock drilling rig 1 may thus comprise one or more control units, whereby one control unit may control the operation of the whole rock drilling rig, or whereby there may be a separate control unit for each part of the drilling. The control unit may be, for example, a device comprising a microprocessor and/or signal processor and possibly some memory capacity external to them, the device carrying out the required calculation and comparison steps by means of its software. The control unit may also be a device comprising only different electronic circuits, having members required for generating the difference between two or more variables, for example for generating the difference variable Δp_ROT of the rotating pressure determined on the basis of the set value p_ROTsετ of the rotating pressure, the real momentary value, i.e. current value P_ROT_MEAS of the rotating pressure, and the difference variable ΔFLOW between the set value FLOW_SET and the real momentary value, i.e. current value FLOWMEAS, of the volume flow of the flushing medium. The control unit may thus comprise the calculating member 28 as well as the calculating member 30 for generating the difference variable ΔFLOW of the set value and the current value of the volume flow of the flushing medium. The general structure and operating principle of control units and devices of this type are known as such to a person skilled in the art.

[0024] In the figures, the solution is shown in connection with a rock drilling rig in which compressed air is used as the flushing medium, this compressed air being produced by means of the compressor 7 or another device applicable to producing compressed air. The solution can, however, be correspondingly utilized in rock drilling rigs in which the flushing medium is hydraulic fluid, which may be for instance water, a mixture of water and air or a mixture of a chemical. When hydraulic fluid is used as the flushing medium, the compressor is replaced with a pump or another corresponding device which, by means of the power generated directly or indirectly by the engine 6, feeds flush fluid along the flush channel system to the rock drill machine 5 and further to through the tool 10 of the rock drill machine 5 to the drill hole 8, whereby the drill cuttings detached from the rock are pushed out of the drill hole 8 by means of the flush fluid. Naturally, a special container or connection for supplying flush fluid to the rock drilling rig is thus to be added to the rock drilling rig. The changes caused to the apparatus when the air used as the flushing medium is replaced with fluid are obvious as such to a person skilled in the art.

[0025] In some cases, features presented in this application can be used as such, irrespective of other features. On the other hand, features presented in this application can, if required, be combined to produce various combinations.

[0026] The drawings and the related description are only intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims.

Claims

1. A method for controlling the operation of a rock drilling rig (1), which rock drilling rig (1) comprises a feeding apparatus (17) for feeding a tool (10) in a hole (8) to be drilled, a rotating apparatus (16) for rotating a tool (10) in the hole (8) to be drilled, and means for feeding flushing medium into the hole (8) to be drilled to remove from the hole (8) to be drilled the drill cuttings generated in the hole (8) during the drilling, the method comprising setting the set value (P_FEED_SET) of the feeding pressure (p_FEED) of the feeding apparatus (17) on the basis of the difference variable (Δp_ROT) between the set value (P_ROT_SET) and the current value (P_ROTMEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16), characterized by determining the difference variable (ΔFLOW) between the set value (FLOWSET) and the current value (FLOWMEAS) of the volume flow (FLOW) of the flushing medium and by affecting the difference variable (Δp_ROT) between the set value (P_ROTSET) and the current value (P_ROTMEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16) of the rock drilling rig (1) on the basis of the difference variable (ΔFLOW) between the set value and the current value of the volume flow (FLOW) of the flushing medium.

2. A method according to claim 1, characterized by determining an amplification coefficient (K) and multiplying the difference variable (ΔFLOW) between the set value and the current value of the volume flow (FLOW) of the flushing medium by an amplification coefficient (K) to change the effect with which the difference variable (ΔFLOW) between the set value and the current value of the volume flow (FLOW) of the flushing medium affects the difference variable (Δp_ROT) between the set value and the current value of the rotating pressure (p_ROT) of the rotating apparatus (16).

3. A method according to claim 2, characterized by the amplification coefficient (K) being a variable-value amplification coefficient, which can obtain any possible positive and negative values, including the value zero.

4. A method according to any one of the preceding claims, characterized by determining the current value (P_ROT_MEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16); subtracting from the set value (p_ROTsετ) of the rotating pressure (p_ROT) of the rotating equipment (16) the current value (P_ROTMEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16) and the difference variable (ΔFLOW) between the set value (FLOWSET) and the current value (FLOWMEAS) of the volume flow (FLOW) of the flushing medium or information corresponding to it to decrease the feeding pressure (p_FEED) of the feeding apparatus when the current value (FLOWMEAS) of the volume flow (FLOW) of the flushing medium falls below the set value (FLOWSET); and setting the set value (P_FEED_SET) of the feeding pressure (p_FEED) of the feeding apparatus (17) on the basis of the difference variable (Δp_ROT) of the set value and the current value of the rotating pressure of the rotating apparatus (16).

5. A method according to claim 4, c h a r a c t e r i z e d by decrasing the feeding pressure (p_FEED) of the feeding apparatus (17) by affecting the adjustment value of the pressure regulating valve (22) of the feeding apparatus (16).

6. A method according to any one of the preceding claims, c h a r a c t e r i z e d by the flushing medium being compressed air or hydraulic fluid.

7. A rock drilling rig (1 ), which comprises a feeding apparatus (17) for feeding a tool (10) in a hole (8) to be drilled, a rotating apparatus (16) for rotating a tool (10) in the hole (8) to be drilled, and means (7, 9) for feeding flushing medium into the hole (8) to be drilled to remove from the hole (8) to be drilled the drill cuttings generated in the hole (8) during the drilling, and in which rock drilling rig (1) the set value (p_FEEDsετ) of the feeding pressure (p_FEED) of the feeding apparatus (16) is arranged to be set on the basis of the difference variable (Δp_ROT) between the set value (P_ROT_SET) and the current value (P_ROT_MEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16), c h a r a c t e r i z e d in that the rock drilling rig (1) further comprises means (30) for determining the difference variable (ΔFLOW) between the set value (FLOWSET) and the current value (FLOWMEA_S) of the volume flow (FLOW) of the flushing medium, and at least one control unit (13) for controlling the operation of the rock drilling rig (1 ) by affecting the difference variable (Δp_ROT) between the set value (p_ROT_SEτ) and the current value (P_ROT_MEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16) of the rock drilling rig (1) on the basis of the difference variable (ΔFLOW) of the set value and the current value of the volume flow (FLOW) of the flushing medium.

8. A rock drilling rig according to claim 7, c h a r a c t e r i z e d in that the control unit (13) of the rock drilling rig (1) further comprises an amplification element (29) comprising amplification or an amplification coefficient (K), with which the amplification element (29) is arranged to change the effect of the difference variable (ΔFLOW) between the set value and the current value of the volume flow (FLOW) of the flushing medium on the difference variable (Δp_ROT) between the set value and the current value of the rotating pressure (p_ROT) of the rotating apparatus (16).

9. A rock drilling rig according to claim 8, c h a r a c t e r i z e d in that the amplification coefficient (K) of the amplification element (29) is a variable-value amplification coefficient, which is arrangeable to obtain any possible positive and negative values, including the value zero.

10. A rock drilling rig according to any one of claims 7 to 9, c h a r a c t e r i z e d in that the rock drilling rig (1 ) comprises means (18) for determining the current value (P_ROTMEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16), and that the control unit (13) of the rock drilling rig (1) is arranged to subtract from the set value (P_ROTSET) of the rotating pressure (p_ROT) of the rotating apparatus (16) the current value (P_ROT_MEAS) of the rotating pressure (p_ROT) of the rotating apparatus (16) and the difference variable (ΔFLOW) between the set value (FLOWSET) and the current value (FLOWMEA_S) of the volume flow (FLOW) of the flushing medium or information corresponding to it to decrease the feeding pressure (p_FEED) of the feeding apparatus when the current value (FLOWMEAS) of the volume flow (FLOW) of the flushing medium falls below the set value (FLOWSET); and to set the set value (p_FEED_Sετ) of the feeding pressure (p_FEED) of the feeding apparatus (17) on the basis of the difference variable (Δp_ROT) of the set value and the current value of the rotating pressure of the rotating apparatus (16).

11. A rock drilling rig according to any one of claims 7 to 10, c h a r a c t e r i z e d in that the control unit (13) is arranged to decrease the feeding pressure (p_FEED) of the feeding apparatus (17) when the difference variable (Δp_ROT) of the adjustment of the rotating apparatus (16) obtains negative values.

12. A rock drilling rig according to claim 11, characterized in that the feeding pressure (p_FEED) of the feeding apparatus (17) is arranged to be decreased by affecting the set value of the pressure regulating valve of the feeding apparatus (17).

13. A rock drilling rig according to any one of claims 7 to 12, characterized in that the flushing medium is compressed air or hydraulic fluid.