EP4671489A1

EP4671489A1 - Rock drilling frame and cooling method

Info

Publication number: EP4671489A1
Application number: EP24184627.8A
Authority: EP
Inventors: Pekka Anttonen; Mikko KITULA; Raimo JUNTUNEN
Original assignee: Sandvik Mining and Construction Oy
Current assignee: Sandvik Mining and Construction Oy
Priority date: 2024-06-26
Filing date: 2024-06-26
Publication date: 2025-12-31
Also published as: WO2026002428A1

Abstract

A rock drilling rig and method for providing cooling for hydraulic oil in a hydraulic system. The rock drilling rig (1) comprises a cooling arrangement (13) for cooling the hydraulic oil fed to a rock drilling machine (5) by conveying a feed flow of hydraulic oil via a water tank (14) arranged on-board a carrier (2) of the rock drilling rig.

Description

Background of the invention

The invention relates to a rock drilling rig for drilling drill holes to a rock surface. The rock drilling rig comprises a cooling arrangement for cooling hydraulic oil of a hydraulic system.
The invention further relates to a method for providing cooling in a hydraulic system of a rock drilling rig.
The field of the invention is defined more specifically in the preambles of the independent claims.
In mines and at other work sites different type of rock drilling rigs are used. The rock drilling rig is provided with one or more drilling units which comprise hydraulically operable rock drilling machines connected to a hydraulic system of the rock drilling rig. Temperature of hydraulic oil in the hydraulic system rises during drilling operations and needs to be cooled to maintain desired drilling performance. Therefore, different type of coolers are connected to the hydraulic systems for cooling the hydraulic oil. However, the known solutions have shown some disadvantages.

Brief description of the invention

An object of the invention is to provide a rock drilling rig with a novel and improved cooling arrangement and a method for cooling hydraulic oil in a hydraulic system.
The rock drilling rig according to the invention is characterized by the characterizing features of the independent apparatus claim.
The method according to the invention is characterized by the characterizing features of the independent method claim.
An idea of the disclosed solution is that a rock drilling rig comprises a cooling arrangement for cooling hydraulic oil of a hydraulic system. The hydraulic system is configured to convey a feed flow pressurized hydraulic oil from a hydraulic pump to a rock drilling machine, and to convey a return circuit of discharged hydraulic oil away from the rock drilling machine. Further, the cooling arrangement is configured cool the hydraulic oil fed to the rock drilling machine by conveying the feed flow via at least one water tank arranged on-board the carrier.
In other words, the hydraulic oil of the feed flow being at operational pressure of the rock drilling machine is cooled prior being directed as an inlet flow to the rock drilling machine. Thus, the cooling occurs in the feed circuit between the hydraulic pump and the rock drilling machine. The water tank configured to cool the feed flow is arranged in connection with the feed circuit. The disclosed solution implements an effective oil to water heat transfer principle.
An advantage of the disclosed solution is that heat is transferred effectively from the pressurized hydraulic oil of the feed flow to water of the water tank on-board the carrier of the rock drilling rig. Then the rock drilling machine can be provided with cooler hydraulic fluid which improves efficiency of the rock drilling machine. Improved efficiency means savings in energy, and in some cases possibility to increase drilling power without thermal problems.
Heat transfer occurs in the water tank between liquids i.e., between the hydraulic oil and water, and can therefore be very efficient when compared to for example oil to air heat transfer principles.
Further, volume of the water tank can be dimensioned to have sufficient cooling potential for designed drilling periods. On the carrier of the rock drilling rig there is typically enough free space for placing the water tank. Layout of the carrier can be designed so that the required one or more water tanks can be arranged on-board. A further advantage is that the cooling based on the on-board water tank can be independent on external devices and systems. This facilitates the use of the rock drilling machine and makes the use more flexible and versatile.
Still another advantage is that the cooling arrangement implementing the water tank and feed conduits passing via it may have a simple and robust structure. The configuration can also be inexpensive and can be implemented in a versatile manner in different type of rock drilling rigs and drilling situations.
According to an embodiment, the water tank consists of two or more separate spaces serving as water reservoirs which are in fluid connection with each other and form together a distributed water tank configuration.
According to an embodiment, the water tank comprises at least one water space inside the structure of the drilling boom. This way hollow frame structure of the drilling boom can be utilized for storing the cooling water.
According to an embodiment, the water tank comprises at least one water space arranged in connection with the drilling boom or the rock drilling unit. Then the water space may be a separate reservoir fastened to the drilling boom or the rock drilling unit.
According to an embodiment, the water tank is unpressurized. Then the structure of the water tank can be simple in structure.
According to an embodiment, the water tank is without water flow during the cooling. Thus, the water tank can be filled with desired amount of water and no continuous water flow is implemented in the cooling. Then the water inside the water tank is stagnant i.e., no water flow occurs.
According to an embodiment, the cooling arrangement comprises at least one cooling device for cooling the hydraulic fluid conveyed in the return circuit. Then the cooling arrangement is configured to cool down the feed flow and the return flow for enhancing the cooling.
According to an embodiment, the cooling arrangement comprises at least one control unit for controlling the devices of the cooling arrangement. The control unit can execute thermal management in accordance with gathered sensing data, such as temperature data on hydraulic oil and cooling water, and input control parameters and control strategies.
According to an embodiment, the feed circuit comprises one or more cooling channel sections arranged inside the water tank and being submerged into the water inside the water tank. In other words, the feed circuit comprising feed channels for conveying the feed flow is provided with one or more cooling channel sections serving as heat transfer elements inside the water tank. An advantage is that a tube or channel inside the water tank can have simple, durable and service free structure. The structure also tolerates well high pressures of the feed flow. Further, cross-sectional area at the cooling channel section can be dimensioned so that the cooling arrangement does not throttle the feed flow and cause pressure losses.
According to an embodiment, the cooling channel section has a simple tubular configuration and forms a tubular cooler. Inner surfaces of the tubes are heated by the hydraulic oil of the feed flow and outer surfaces of the tubes are cooled by the surrounding water inside the water tank. Then the heat transfers from the hydraulic oil through the material of the tubes to the water.
According to an embodiment, the cooling channel section has a spiral configuration. Then a cooling spiral is submerged into the water. In the cooling spiral there can be a great amount of cooling area arranged in a compact size.
According to an embodiment, the cooling channel section has a cross-section comprising several cooling fins on its outer surface side for enhancing heat transfer from the cooling channel section to the water. The cooling fins enlarge surface area of the cooling channel section.
According to an embodiment, the rock drilling machine comprises an impact device and at least the feed flow conveyed to the impact device is arranged to flow via the water tank for cooling the hydraulic flow fed to the impact device. In other words, an inlet flow of the impact device is cooled.
Rock drilling efficiency can be enhanced especially when cooler hydraulic fluid is used to power the impact device. That is because leakage flows inside the impact are lower at lower temperatures of the hydraulic fluid. At higher fluid temperatures viscosity of the fluid is low which increases the leakage flows between components of the impact device. Thus, the efficiency of an impact mechanism is known to be lower at the higher oil temperatures due to higher leakage flows.
The disclosed cooling arrangement can be considered to be a cooling booster especially for the impact device which is typically the most critical and energy consuming device in the rock drilling rig. It has been noted that 10°C degrease in hydraulic oil temperature can provide 10 % savings in energy when full power drilling is executed with same impact power.
According to an embodiment, the disclosed solution allows to operate the hydraulic pump at higher hydraulic oil temperatures since the feed flow is cooled after the hydraulic pump. The higher operational temperature can provide energy savings in the pumping due to higher oil temperature having lower viscosity. It has been noted that possibility to use higher hydraulic oil temperature in the pumping can provide 1 - 2 % savings in energy consumption. The higher temperature may also mean reduced cavitation sensitivity in the hydraulic pump.
According to an embodiment, the disclosed solution allows to use higher temperatures of hydraulic oil in the tank since cooling capacity is available after the hydraulic pump. Then improved deaeration of hydraulic oil is possible whereby smaller oil tank can be used. A further advance is that the improved deaeration means also improved oil aging due to reduced oil oxidation whereby longer oil change intervals can be implemented.
According to an embodiment, the disclosed cooling allows also to optimize the used hydraulic oil and especially its viscosity properties.
According to an embodiment, the rock drilling machine is of top hammer type comprising an impact device for providing a drilling tool with impact pulses and a rotation device for rotating the drilling tool around its longitudinal axis.
According to an alternative embodiment, the rock drilling machine is a rotary or DTH drilling machine comprising a hydraulic rotation device. In the rotary drilling no impact pulses are implemented, whereas in the DTH drilling the impact device is located inside a drilled hole. Thus, in the rotary and DTH drilling the rock drilling machine above the ground comprises only the hydraulic rotation device provided with cooled hydraulic oil in accordance with features and embodiments disclosed in this document.
According to an embodiment, volume of the water tank is at least 500 liters. In other words, the water tank needs to be large enough for providing good cooling capability and for serving as a cooling reservoir.
According to an embodiment, the water tank is of passive or static type, whereby the hydraulic oil is simply arranged to flow through the water tank inside the hydraulic conduits and to thereby utilize the water tank as a passive cooling reservoir.
According to an embodiment, the water tank is of active or dynamic type, whereby the hydraulic oil is arranged to flow through the water tank and the water inside the tank is actively cooled, and alternatively or in addition to, cooler water may be added.
According to an embodiment, the volume of the water tank is at least 1000 liters. An advantage of this embodiment is that the water tank is relatively big in volume and has thereby potential to serve as an effective cooling reservoir for a duration of a typical drilling phase wherein a plurality of designed drill holes are drilled at one drilling position.
According to an embodiment, the water tank is in fluid connection with a flushing device of the rock drilling rig whereby the water inside the water tank is utilized also for flushing purposes. Feeding of the flushing water or water mist also cools down the rock drilling machine during the drilling and thereby assist in handling heat loadings of the rock drilling machine. Thus, the water of the water tank is implemented to cool the feed flow of the hydraulic fluid and to cool the rock drilling machine by the flushing measures. The water of the water tank serves as a cooling agent and flushing agent, whereby dual use of the water is disclosed.
According to an embodiment, the water tank is heat insulated. In other words, the water tank may be shielded against external heat loadings. Then the water inside the water tank can be stored at temperatures lower than temperatures of an ambient air. The heat insulation of the water tank can significantly improve the cooling efficiency and decrease energy consumption especially when operating at hot climates and drilling sites. The heat insulated water tank is especially useful when the water inside the water tank is cooled down prior or during the drilling.
According to an embodiment, the water tank is made of material having good heat insulating properties. Then the water tank may be made of plastic or composite material, for example.
According to an embodiment, the water tank is surrounded with insulation panels made of heat insulating polymer material, such as polystyrene. Alternatively, wall structure of the water tank may be a sandwich structure comprising a middle layer with polymeric insulation material between two outer layers. The insulating middle layer may be of foamed polyurethane, for example.
According to an embodiment, the water tank is provided with at least one cooling device for cooling the water. In other words, the water tank is connectable to be in fluid connection with one or more active or passive cooling devices configured to cool the water inside the water tank by transferring heat from the water to ambient air. The cooling of the water can be executed prior to the drilling, during the drilling, at drilling breaks, or continuously during the operation of the rock drilling rig.
According to an embodiment, the cooling device for cooling the water inside the water tank comprises a first heat exchanger submerged in the water and a second heat exchanger which is in fluid connection with the first exchanger and is located outside the water tank in ambient air. The cooling device further comprises a circulation pump for circulating the water between the heat exchangers. In the second heat exchanger heat is removed from the water to the ambient air.
According to an embodiment, the cooling device for cooling the water inside the water tank comprises a chiller implementing active compressor cooling. A compressor on-board the rock drilling rig can be utilized for the compressor cooling.
According to an embodiment, the cooling arrangement comprises at least one return cooling device for cooling the hydraulic oil conveyed in the return circuit towards the tank. The return cooling device is in fluid connection with the water tank and is configured to cool the returning hydraulic oil by means of the water of the water tank. In other words, the returning fluid flow in the return circuit is cooled by utilizing oil to water cooling principle. Thus, the water tank is utilized for cooling not only the feed flow but also the return flow, whereby the overall cooling can be very effective.
According to an embodiment, the water tank is in fluid connection with a cooling circuit of at least one electrical device of the rock drilling rig. In other words, the cooling arrangement is configured to cool one or more electrical devices in addition to cooling the feed flow conveyed to the rock drilling machine. This is beneficial especially when the rock drilling rig is electrically operable.
According to an embodiment, the cooled electrical device may be for example one of the following: a power electronic controller relating to electrical drive of the rock drilling rig, a battery, an electrical drive motor, a frequency transformer, a switch cabinet, an electrical actuator such as a motor of a hydraulic pump or compressor.
According to an embodiment, the disclosed solution relates also to a method for providing cooling in a hydraulic system of a rock drilling rig. The hydraulic system provides a feed flow of pressurized hydraulic oil from a hydraulic pump to a rock drilling machine and discharges the hydraulic oil from the rock drilling machine to a tank as a discharge flow. The method comprises cooling the hydraulic oil during drilling by means of a cooling arrangement. The method further comprises cooling the feed flow prior being fed as an inlet flow to the rock drilling machine and executing the cooling in the cooling arrangement by conveying the feed flow via at least one water tank for providing oil to water heat transfer.
According to an embodiment, the method further comprises connecting the water tank to an external water supply and selectively feeding water to the water tank during the drilling. In other words, the water tank is filled with feed water during the drilling operation.
The water tank can be filled from a water supply line of a mine, or from catch basins located nearby the drilling site. The water tank may comprise a feed port and feed valves for controlling the water feeding.
According to an embodiment, the method further comprises feeding feed water with lower temperature compared to the temperature of the water inside the water tank, whereby the fed feed water is cooling down the water in the water tank. The water in the water tank can also be circulated whereby higher temperature water is discharged from the water tank and lower temperature feed water is filled into the water tank. Thus, the feed water feeding can be used for filling and cooling the water tank.
According to an alternative embodiment, the method comprises storing a designed amount of water to the water tank for executing the drilling operation. Then there is no need for filling the water during the drilling phase.
According to an embodiment, cooling the water of the water tank during the drilling. In other words, the water tank is provided with a feature "cooling while drilling".
According to an embodiment, the method comprises cooling the water of the water tank by means of an on-board cooling device.
The water of the water tank may be circulated via a chiller where heat is removed from the water and is transferred to the ambient air.
According to an embodiment, the method comprises cooling the water of the water tank by means of an external cooling device. The water tank can be connected to the external cooling device when being positioned at a drilling site.
According to an embodiment, the cooling may be continuous, or it may be controlled selectively by means of a control unit and considering for example temperature sensing data and drilling tasks to be done.
According to an embodiment, the method further comprises pre-cooling the water of the water tank prior the drilling. In other words, temperature of the water inside the water tank can be cooled in advance and in accordance with the drilling task to be executed. A control unit of the cooling arrangement may estimate the need for cooling based on input sensing and other data.
For example, when the volume of the water tank is 1 m³ and 20°C pre-cooling temperature is done, then 20 kWh cooling capacity is available for the duration of the drilling.
The water tank may be pre-cooled by means of an onboard cooling device or it may be coupled to an external cooling device.
The pre-cooling may be executed for example during transfer drives of the rock drilling rig and also during different drilling breaks and waiting times, such as when the rock drilling rig is moved away from a drilling position for a duration of blasting and hauling of rock material.
Further, when the operation of the rock drilling rig is powered by means of an onboard electric energy storage, such as a battery package, the solution may implement a principle "cooling while charging". This means that the time needed for charging the batteries is also utilized for pre-cooling the water tank. Thus, the charging time may be one of the drilling breaks utilized for the pre-cooling.
At a charging point, wherein the charging is done, there may be arranged additional cooling capacity, such as a connection to an external cooling device or system, or alternatively or in addition to, a connection to a water supply system for providing low temperature feed water. This way it is easy to implement the pre-cooling at the charging point when being provided with such cooling capacity.

Combined with a charging cooler

Further, at the charging point there may be a cooling system for cooling an electrical charging device. The cooling system of the charging device may be utilized for pre-cooling the water tank, or any other corresponding cooling reservoir, of the rock drilling rig. This way, the cooling system which is primarily designed and intended for cooling the charging device, may have a second use. Cooling capacity of such dual use cooling system can be selectively connected between the charging device and the onboard cooling reservoir. Distribution of the cooling capacity can be done in response to magnitude of charging power, for example. One more possibility is to use the onboard cooling reservoir for providing cooling capacity for cooling the charging device. Then it may be possible that no separate cooling system is needed at the charging point but instead the onboard cooling reservoir is connected to the charging device for providing needed cooling power. In a further implementation the onboard cooling reservoir is usable to assist the cooling system of the charging device. This may be beneficial when operating at hot climates and drilling sites. When the onboard cooling reservoir is used as an assisting system, then the cooling system of the charging device may in some cases be designed to be with smaller cooling capacity.

Alternative cooling reservoir

In an alternative solution, which is not in accordance with the claims of this document, it is possible to use another type of on-board cooling reservoirs than the water tank.
Then other liquids than water can also be used as storage liquids in the onboard cooling reservoir. The liquid may be oil, for example. A further possibility is to use sand, or sand-like materials, in the cooling reservoir. This type of cooler may be called as a sand cooler. Combination of the sand or the sand-like material with liquid, such as oil or petroleum product, may also be utilized in the cooling reservoir.
The above disclosed embodiments may be combined to form suitable solutions having those of the above features that are needed.

Brief description of the figures

Some embodiments are described in more detail in the accompanying drawings, in which

Figure 1 is a schematic side view of a rock drilling rig for underground drilling and being provided with a cooling arrangement,
Figures 2 - 4 are schematic views of some cooling arrangements, and
Figure 5 is a schematic side view of a rock drilling rig provided with a cooling arrangement for cooling only power electronics whereby the shown arrangement is not in accordance with claims of this document.

For the sake of clarity, the figures show some embodiments of the disclosed solution in a simplified manner. In the figures, like reference numerals identify like elements.

Detailed description of some embodiments

Figure 1 discloses a rock drilling rig 1 comprising a movable carrier 2 and one or more drilling booms 3 mounted on the carrier 2. The boom 3 comprises a rock drilling unit 4 provided with a hydraulic rock drilling machine 5. The rock drilling machine 5 may comprise an impact device 6 for providing impact pulses for a drilling tool 7, or alternatively, it comprises only a rotating device for rotating the drilling tool 7. The rock drilling machine 5 is movable on a feed beam 8 in a drilling direction and a reverse direction. There is a hydraulic system 9 for powering hydraulic actuators, such as the rock drilling machine 5. The hydraulic system 9 comprises a hydraulic pump 10 for providing pressurized hydraulic oil which is conveyed via a feed circuit 11 to the rock drilling machine 5, and there is also a return circuit 12 for conveying a return flow of discharged hydraulic oil from the rock drilling machine to a hydraulic tank 17 (shown in Figures 2 - 4). A cooling arrangement 13 is arranged to cool the hydraulic oil prior being fed to the rock drilling machine 5. There is an on-board water tank 14 on the carrier 2 and feed flow of the hydraulic oil fed to the rock drilling machine 5 is conveyed via the water tank 14. Thus, the cooling occurs between the pump 10 and the rock drilling machine 5. The feed circuit 11 comprises a cooling channel section 15 arranged inside the water tank 14 and is submerged into the water inside the water tank 14. The cooling channel section 15 may have a spiral or curving configuration, for example.
In Figures 2 - 4 there are heat exchanger drawing symbols disclosed in connection with the cooling channel sections 15 for improving understanding of the cooling arrangements 13. However, there is not necessarily need for any specific heat exchanger since the cooling channel sections inside the water tank 14 can be designed so, that desired cooling is achieved without relevant pressure losses.
Figures 1 and 3 disclose a control unit CU which may be arranged to control the cooling arrangement 13 in accordance with input control principles, manual control commands, and gathered sensing data, such as temperature sensing data.
Figure 2 discloses a cooling arrangement 13 which differs from the one shown in Figure 1 in that a water tank 14 is provided with a cooling device 16 for cooling water inside the water tank 14. The cooling device 16 may comprise heat exchangers for executing heat transfer from the water to ambient air. This kind of water-to-air cooling may be continuously operating during the operation of the rock drilling rig, or it may be operated prior initiating the drilling so that the water can be pre-cooled. Cooling off the water can also be done during breaks in the actual operation of the rock drilling rig.
Figure 2 further discloses that the water stored in the water tank 14 can also be used as a flushing agent 18 in the drilling. Then there is a flushing conduit 18 between the water tank 14 and a flushing housing, or a corresponding flushing element of the rock drilling machine 5.
Figure 3 discloses a cooling arrangement 13 wherein a return circuit 12 is provided with a return cooling device 20 for cooling the hydraulic oil conveyed in the return circuit 12 towards a hydraulic tank 17. The return cooling device 20 is in fluid connection with a water tank 14 and is configured to cool the returning hydraulic oil by means of the water of the water tank 14. The return cooling device 20 may comprise heat exchangers and a circulation pump, for transferring heat from the returning hydraulic oil to the water tank 14. Thus, there exists oil-to-water heat transfer.
The return circuit 12 may be provided with a conventional type of heat exchanger 21 for transferring heat from the returning oil to the ambient air, whereby oil-to-air heat transfer is utilized.
The water inside the water tank 14 can be cooled by means of a cooling device 16 which may be a chiller utilizing compressor cooling principles. In addition to, there may, or may not, be a passive cooling device 22 for cooling the water.
Figure 3 further discloses that the cooling arrangement 13 can be used for cooling electrical devices 23, such as batteries and power electronics. The electrical device 23 may be connected to the cooling device 16, or it may be connected in any other way to the water tank 14. The electrical device 23 may comprise a cooling system of its own and the cooling system may utilize cooling capacity of the water tank 14.
Figure 4 discloses a cooling arrangement 13 which differs from the one shown in Figure 3 in that there is a possibility to feed fresh water from a water supply 24 to the water tank 14. The water being fed may be conveyed via a feed water cooler 25 so that low temperature feed water can be provided for the water tank 14. There may also be a drain connection 26 for conveying water with higher temperature out of the water tank 14.
The water tank 14 may be heat insulated. The heat insulation feature is indicated in Figures 3 and 4 by means of thick lines in connection with the water tank 14.
In Figures 1 - 4 control valves and other control devices are not disclosed for clarity reasons.

An additional solution

A further solution which is not in accordance with the claims of this document is disclosed in Figure 5 and some of its features are presented below.
According to this additional solution, the above disclosed onboard water tank 14 is utilized as a cooling booster for power electronic components 27 during charging of batteries 28 of an electrically operable rock drilling rig.
In other words, the onboard water tank is implemented as a charging cooler.
The rock drilling rig may be fully electrically operable, or alternatively, it may comprise one or more batteries for providing operating power for one or more phases of a rock drilling task.
According to an embodiment, the system is configured to liquid cool at least one battery charger 29. The battery charger may be located outside the rock drilling rig and is connected to an electric system of the rock drilling for the duration of the charging. The rock drilling rig is provided with one or more cooling hoses 30 connectable to the battery charger so that the water of the onboard water tank can be circulated via the battery charger for providing the liquid cooling.
According to an embodiment, the battery charger may be located on the carrier i.e., onboard the rock drilling rig.
According to an embodiment, the disclosed system comprises at least one liquid cooled charging cable 31 between the rock drilling rig and the battery charger. This way over heating of the charging cable during the high power charging can be avoided and full charging capacity can be implemented.
According to an embodiment, the disclosed system comprises at least one liquid cooled charging connector 32 or cable connector between the rock drilling rig and the charging cable of the battery charger. This way over heating of the charging connector during the high power charging can be avoided and full charging capacity can be implemented.
In Figure 5 liquid cooling flows are shown by means of arrows. Figures 5 also discloses a cooling liquid connector 33 and a control device 34, which may be a charging controller or other electrical device requiring cooling. A control unit CU is arranged to control the liquid cooling process and operation of the disclosed apparatuses. Further, similar type of heat exchangers and other components belonging to cooling arrangement 13 are show as in the previous Figures 1 - 4.
Thus, the disclosed additional solution can be defined as follows:
A rock drilling rig for drilling drill holes to a rock surface,
wherein the rock drilling rig comprises:

a movable carrier;
at least one boom provided with a drilling unit comprising a rock drilling machine movable on a feed beam;
power electronic components comprising at least one battery for storing electric energy and control components for controlling usage of the electric energy and charging of the battery;
and a cooling arrangement for cooling at least one of the power electronic components;
characterized in that
the cooling arrangement comprises at least one water tank arranged on-board the rock drilling rig and wherein water of the water tank is configured to liquid cool the at least one power electronic component at least in response to charging of the battery.

According to an embodiment, the power electronic component is one of the following: battery charger, charging cable, charging connector, charging controller, battery, electrical power package, frequency converter.
According to an embodiment, the water of the water tank may, or may not, be arranged to cool hydraulic oil fed to at least one hydraulic actuator, such as to a hydraulic rock drilling machine.
The drawings and the related description are only intended to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims.

Claims

A rock drilling rig (1) for drilling drill holes to a rock surface,
wherein the rock drilling rig (1) comprises:
a movable carrier (2);

at least one boom (3) provided with a drilling unit (4) comprising a rock drilling machine (5) movable on a feed beam (8);

a hydraulic system (9) comprising a hydraulic pump (10) for providing pressurized hydraulic oil, a feed circuit (11) for conveying a feed flow of pressurized hydraulic oil from the pump (10) to the rock drilling machine (5), and a return circuit (12) for conveying a return flow of discharged hydraulic oil from the rock drilling machine (5) to a tank (17);

and a cooling arrangement (13) for cooling the hydraulic oil;

characterized in that

the cooling arrangement (13) is configured cool the hydraulic oil fed to the rock drilling machine (5) by conveying the feed flow via at least one water tank (14) arranged on-board the carrier (2).
The rock drilling rig as claimed in claim 1, characterized in that
the feed circuit (11) comprises at least one cooling channel section (15) arranged inside the water tank (14) and being submerged into the water inside the water tank (14) .
The rock drilling rig as claimed in claim 1 or 2, characterized in that
the rock drilling machine (5) comprises an impact device (6) and wherein at least the feed flow conveyed to the impact device (6) is arranged to flow via the water tank (14) for cooling the hydraulic flow fed to the impact device (6) .
The rock drilling rig as claimed in any one of the preceding claims 1 - 3, characterized in that
volume of the water tank (14) is at least 500 liters.
The rock drilling rig as claimed in any one of the preceding claims 1 - 4, characterized in that
the water tank (14) is heat insulated.
The rock drilling rig as claimed in any one of the preceding claims 1 - 5, characterized in that
the water tank (14) is provided with at least one cooling device (16) for cooling the water.
The rock drilling rig as claimed in any one of the preceding claims 1 - 6, characterized in that
the cooling arrangement (13) comprises at least one return cooling device (20) for cooling the hydraulic oil conveyed in the return circuit (12) towards the tank (17);

and wherein the return cooling device (20) is in fluid connection with the water tank (14) and is configured to cool the returning hydraulic oil by means of the water of the water tank (14).
The rock drilling rig as claimed in any one of the preceding claims 1 - 7, characterized in that
the water tank (14) is in fluid connection with a cooling circuit of at least one electrical device (23) of the rock drilling rig (1).
A method for providing cooling in a hydraulic system (9) of a rock drilling rig (1);
wherein the hydraulic system (9) provides a feed flow of pressurized hydraulic oil from a hydraulic pump (10) to a rock drilling machine (5) and discharges the hydraulic oil from the rock drilling machine (5) to a tank (17) as a discharge flow;

and wherein the method comprises cooling the hydraulic oil during drilling by means of a cooling arrangement (13);

characterized by

cooling the feed flow prior being fed as an inlet flow to the rock drilling machine (5) and executing the cooling in the cooling arrangement (13) by conveying the feed flow via at least one water tank (14) for providing oil to water heat transfer.
The method as claimed in claim 9, characterized by
connecting the water tank (14) to an external water supply (24) and selectively feeding water to the water tank (14) during the drilling.
The method as claimed in claim 9 or 10, characterized by
cooling the water of the water tank (14) during the drilling.
The method as claimed in any one of the preceding claims 9 - 11, characterized by
pre-cooling the water of the water tank (14) prior the drilling.