Laser drilling method and apparatus

Abstract

The invention relates to a method of laser drilling using a laser beam generator outside the borehole. Liquid nitrogen is supplied to the laser drill head via the drill string, which is converted into a gaseous state in the laser drill head area and separated into a protective gas stream (18) flowing through the laser conduit (19) in the direction of the earth's surface and a transport gas stream (15) which removes the removed rock material through the annular space. A heated gas stream (10) is heated in an electric heating device (11) and directed to the bottom of the borehole which is bombarded by the laser beam.

Description

Technical Field

[0001] This invention relates to a method for drilling a hole in rock formation by bombarding the bottom of the hole with a laser beam generated by a laser beam generator located outside the hole and guided by suitable auxiliary devices to a laser drill bit located at the bottom of the hole and coupled to a drill string, wherein nitrogen supplied to the laser drill bit via the drill string branches within the region of the laser drill bit:

[0002] - Used as a shielding gas branch to protect the transmitted laser beam from interference by suspended particles;

[0003] - An alternative branch used for transporting airflow, which transports rock material separated from the bottom of the borehole to the outside of the borehole through the annular space between the drill pipe and the borehole wall. Background Technology

[0004] Such a device is illustrated in, for example, patent document US 2010 / 0044102 A1. In existing drilling methods of the above type, a flexible tube is used as an auxiliary device to guide the laser beam and supply nitrogen, required as a protective gas and transport gas. For example, a spiral tube has a fiberglass cable arranged within its internal space for transmitting the laser beam, while sufficient unobstructed space is maintained within the tube for adequate nitrogen passage. The protective gas flow and the laser beam are emitted together through an opening on the underside of the laser drill bit towards the bottom of the borehole and reach the bottom of the borehole together. The energy of the laser beam reaching the bottom of the borehole separates the rock material present there, which is achieved, depending on the rock material, through melting, evaporation, and / or spalling. Then, the protective gas flow, simultaneously reaching the bottom of the borehole, pushes the thermally separated rock material along the periphery of the bottom of the borehole, where the rock material is picked up by suction according to the transport gas flow guided in the outward transport direction. This transport gas flow transports the rock material separated from the bottom of the borehole to the outside of the borehole through an annular space between the drill rod and the borehole wall.

[0005] Such methods and devices contain a series of conflicting requirements, which leads to many problems in actual implementation.

[0006] This method, which involves thermally separating rock from the bottom of the borehole, obviously requires a large amount of energy, primarily supplied by the laser beam. Corresponding experiments show that using a laser beam to thermally separate rock from the bottom of the borehole in normal rock formations requires more than 400 W / cm². 2The power density is high. To achieve this power density, the laser beam in existing equipment must be guided in a properly focused, continuous manner above the bottom of the borehole, extending into the region up to the bottom of the borehole. This requires the integration of complex mechanisms into the laser drill bit and / or support tools to achieve sufficient drilling. In contrast, it would be better if the entire bottom of the borehole could be bombarded simultaneously and densely, for example, by means of a beam expander in the laser drill bit, but the laser beam power required for a normal borehole diameter would exceed 500 kW, preferably 600 kW to 700 kW.

[0007] However, such high-powered laser beams can no longer be easily transmitted through fiber optic cables, especially when the cables are 2,000 to 10,000 meters long due to the required drilling depth. This is because fiber optic cables exhibit relatively high attenuation, meaning that at such lengths, the emitted laser beam can no longer reach the laser drill bit with sufficient intensity.

[0008] Furthermore, the necessary increase in laser beam power leads to heat problems, as the energy input from the laser beam and the energy released as heat at the bottom of the borehole cause unacceptable overheating of the laser drill bit and drill rod. Given the extremely high power of the laser beam, the amount of gaseous nitrogen supplied for both the protective and transport airflows is insufficient to adequately remove residual heat. It has also been shown that the intense stress exerted by the cold protective airflow on the bottom of the borehole can cause thermal short circuits in this region, interfering with the process of thermally separating rock from the bottom of the borehole. Summary of the Invention

[0009] In view of this, the object of the present invention is to further develop methods of the type described above, which can achieve sufficiently fast drilling even in extremely deep boreholes without causing harmful overheating at the laser drill bit or drill rod.

[0010] To achieve the above objectives, based on the methods of the type described above, this invention proposes:

[0011] - The laser beam is guided to the laser drill bit via a laser guide tube extending along the length of the drill rod, ensuring that the airflow is flowing through the unobstructed cross-section of the laser guide tube;

[0012] - Nitrogen is supplied to the laser drill bit in liquid form via the drill pipe and turns into a gaseous substance within the laser drill bit's region;

[0013] - An additional branch is branched off from the supplied nitrogen to serve as a heating gas stream, which is heated by an electrothermal device associated with the laser drill bit and directed toward the bottom of the borehole where the laser beam is bombarded.

[0014] By using the laser conduit with protective gas flow as proposed according to the present invention instead of the conventional fiberglass cable in the prior art, a very high-power laser beam can be propagated in a simple manner with almost no loss along the entire length of the drill pipe, due to the extremely low attenuation effect of clean gaseous nitrogen. To deflect the laser beam direction and perform any necessary corrections within the laser conduit, a suitable lens and / or mirror system can be arranged at appropriate intervals within the conduit in a simple manner, naturally without interrupting the passing protective gas flow.

[0015] Furthermore, in the method of this invention, nitrogen is supplied to the laser drill bit as a liquid substance and only becomes a gaseous substance within the region of the laser drill bit. Sufficient coolant can be used to cool the laser drill bit, protect the airflow, transport the airflow, and the drill rod. In particular, the change of state of matter is extremely endothermic, which greatly increases the supply, thereby providing a sufficient amount of cold nitrogen gas, which can be distributed to the laser drill bit region as needed to avoid overheating.

[0016] Finally, according to the present invention, the electrically preheated heating gas flow is guided to the bottom of the borehole, thus ultimately preventing the aforementioned thermal short circuit. This allows the heating gas flow to be easily and arbitrarily strengthened to support the laser beam separation process, while simultaneously supporting the outward transport of the separated rock material from the bottom of the borehole along the direction of the delivery gas flow. Preferably, the temperature of the heating gas flow is even close to the melting temperature of the corresponding adjacent rock.

[0017] Another problem with the method of the present invention is that the molten or evaporated rock material contained in the rising conveying gas flow must be cooled as much as possible below the solidification temperature of the rock material before entering the annular space between the drill pipe and the borehole wall, so that the rock material does not settle on the drill pipe and / or borehole wall. To this end, the present invention also proposes to additionally use liquid nitrogen as the conveying gas, wherein the liquid nitrogen is injected within the region of the laser drill bit into the conveying gas flow that flows back from the bottom of the borehole and carries rock material separated from the bottom of the borehole, and becomes a gaseous substance in the conveying gas flow as the conveying gas flow and the rock material contained therein cool. The liquid nitrogen used for this purpose branches off from the liquid nitrogen flow supplied to the laser drill bit via the drill pipe.

[0018] Advantageously, the invention also proposes to branch off a separate stream from the nitrogen supplied to the laser drill bit, which serves as a cooling airflow. This stream flows through the drill string and out of the borehole, cooling the drill string from the inside in the process. This further ensures that heat from the supply airflow is not unnecessarily supplied to the internal space of the drill string.

[0019] Finally, the method of the present invention also proposes to branch off a separate stream from the nitrogen supplied to the laser drill bit as a cleaning airflow, so as to keep the laser beam exit aperture of the laser drill bit (directed to the bottom of the borehole and covered with a beam expander) clean. This prevents suspended particles of the separated rock from rising through the borehole and contaminating the laser beam exit aperture covered by the light transmission relationship, thus preventing a decrease in the transmittance of the laser beam.

[0020] The present invention also relates to an apparatus for performing the above-described method. The apparatus is characterized primarily by a special configuration of the drill pipe. This drill pipe has:

[0021] - A laser guide tube used to transmit the laser beam, protecting the airflow passing through the laser guide tube;

[0022] - A double tube, concentrically surrounding the laser guide tube with a radial gap, through which liquid nitrogen flows.

[0023] - Insulating tubes, concentrically surrounding the double tubes with radial gaps;

[0024] -Outer protective tube, concentrically surrounding the insulating tube with radial gaps;

[0025] in,

[0026] - Evacuate the annular space surrounding the two tubes;

[0027] - The annular space between the outer sheath and the insulating tube is connected to the cooling airflow returning from the laser drill bit;

[0028] - The outer sheath surrounds one or more tubes equipped with electrical conductors for transmitting electrical energy and signals to the laser drill bit.

[0029] This compact drill pipe configuration allows for the widest possible, attenuation-free transmission of a high-power laser beam through the laser guide tube. Liquid nitrogen passes through the annular space in a thermally insulated and potentially vacuum-like manner. The entire drill pipe effectively insulates against heat from the delivery airflow, transmitting electrical energy and signals to the laser drill bit.

[0030] Advantageously, the present invention also proposes that the outer sheath be made of steel, and the tubes arranged inside the outer sheath be made of carbon fiber reinforced plastic (CFP). The steel outer sheath provides the integral drill pipe with the necessary stability and insensitivity to unintentional overheating from external sources. The material used for the inner tube is extremely lightweight yet extremely strong, and in addition, provides good thermal insulation and a wide range of electrical insulation properties.

[0031] Furthermore, the apparatus for performing the method of the present invention is characterized in that the laser drill bit has a housing, the top of which is fastened to the outer sheath of the drill rod, wherein the housing is further equipped with:

[0032] - A transmission channel through the housing allows the laser beam to extend through the housing and connect to the laser guide tube of the drill pipe. A beam expander takes a light-transmitting relationship in the bottom region of the housing to cover the outlet aperture of the transmission channel.

[0033] - A device for propagating and / or evaporating the arriving liquid nitrogen and for storing and branching the gaseous nitrogen into various streams, arranged in the annular space of the inner space of the shell and connected to the drill pipe of the double tube;

[0034] - A delivery gas nozzle for injecting liquid nitrogen into the delivery gas flow is arranged in the housing and extends obliquely in the direction of the delivery gas flow;

[0035] - Heating gas nozzles for heating the airflow are arranged in the bottom of the housing and point towards the bottom of the borehole;

[0036] - An electric heating device for heating the airflow is arranged inside the housing;

[0037] - Solenoid valves and volumetric flow regulators used to control all nitrogen branches.

[0038] Using such a laser drill bit, a laser beam arriving through the laser guide tube of the drill rod can be supplied to the bottom of the borehole in a way that is as wide as possible without attenuation, evaporates the liquid nitrogen supplied through the dual tubes of the drill rod, and branches the liquid nitrogen into various branches under the adjustment of volume flow rate.

[0039] More advantageously, the branch flow used for cooling airflow passes through the internal space of the casing, and the annular space between the internal space of the casing and the outer protective tube and the insulating tube of the drill pipe. Thus, the cooling airflow responsible for cooling the casing also serves to ensure adequate cooling of the outside of the drill pipe.

[0040] During the use of the device of the present invention, there is a risk that rock particles rising from the bottom of the borehole may contaminate the beam expander in the laser beam emission area. To prevent this, the present invention also proposes that a cleaning nozzle, serving as a branch for cleaning airflow, is arranged in the bottom of the housing, extending parallel to the lower side of the bottom of the housing and aligned with the beam expander covering the transmission aperture of the laser beam.

[0041] In order to provide a sufficient supply of clean protective airflow to the laser guide tube along its entire length, starting from the housing of the laser drill bit, the present invention also proposes that the transmission channel of the laser beam be equipped with an air inlet inside the housing of the laser drill bit as a branch of the protective airflow.

[0042] Finally, the present invention proposes that holding devices spaced apart from each other be arranged inside the transmission channel of the laser beam or inside the laser guide tube to hold the lens and / or mirror system that deflects the laser beam. These holding devices are formed in a manner that prevents gas in the gas flow from passing through. Such devices may be used when the borehole and the corresponding drill rod deviate from their linear shape and require realignment and / or refocusing of the laser beam. Attached Figure Description

[0043] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0044] Figure 1 A schematic longitudinal cross-sectional view is shown with the laser drill bit fastened to the drill rod and positioned above the bottom of the borehole.

[0045] Figure 2 A schematic cross-sectional view of the drill pipe is shown. Detailed Implementation

[0046] In the attached drawing, the laser drill bit is marked with reference numeral 1, and the drill rod supporting the laser drill bit 1 is marked with reference numeral 2. The laser drill bit 1 and the drill rod 2 are located in a borehole 4 drilled in the rock stratum 3, which has a borehole wall 4a and a borehole bottom 4b.

[0047] The laser drill bit 1 maintains a small gap above the bottom 4b of the borehole in its working position and has a generally cylindrical housing 5, the top 5a of which is connected to the drill rod 2.

[0048] In addition, the bottom 5b of the housing 5 is spaced apart from the bottom 4b of the borehole, and a transmission aperture 6 for the laser beam 7 is centrally located. The laser beam 7 is supplied via the drill rod 2 and propagates through the housing 5. A beam expander 8 is provided in the transmission aperture 6 to broaden the arriving laser beam 7 so that the laser beam 7 bombards the bottom 4b of the entire borehole.

[0049] In addition, a heating jet nozzle 9 is provided in the bottom 5b of the housing to generate a heating airflow 10 pointing towards the bottom 4b of the borehole, and to allow heating gas from the electric heating device 11 arranged in the internal space of the housing 5 to enter.

[0050] In addition, a cleaning nozzle 12 is provided in the bottom 5b of the housing, which is parallel to the lower side of the bottom 5b of the housing in the direction of the centrally arranged beam expander 8. Clean gaseous nitrogen is supplied as a cleaning airflow 14 through the nitrogen collection tank 13 located inside the housing 5 to keep the beam expander 8 clean.

[0051] Additionally, the housing 5 of the laser drill bit 1 has a housing cover 5c, which leaves an annular space around the borehole wall 4a to allow the passage of a conveying airflow 15 carrying separated rock material and rising from the bottom of the borehole 4b. This conveying airflow 15 originates from the peripheral region of the bottom of the borehole 4b subjected to the stress of the heated airflow 10, and delivers the rock material separated from the bottom of the borehole 4 out of the borehole 4.

[0052] To support this rising airflow 15, delivery jet nozzles 16 and 17 are arranged in the outer casing 5c ​​of the housing 5 of the laser drill bit 1. These nozzles extend obliquely in the direction of the airflow 15 and allow liquid nitrogen and / or gaseous nitrogen from inside the housing 5 to enter. The extent to which liquid nitrogen is introduced via the delivery jet nozzles 16 particularly strongly contributes to cooling the rock contained in the delivery airflow 15.

[0053] In order to guide the laser beam 7 to the laser drill bit 1 with minimal attenuation and to supply sufficient nitrogen to the laser drill bit 1, a specially constructed drill rod 2 is provided, which will be described in detail below.

[0054] The drill pipe 2 consists of several concentrically arranged and nested tubes, namely:

[0055] - An inner laser guide 19 for transmitting the laser beam 7, through which a protective gas flow 18 flows. This protective gas flow 18, composed of clean nitrogen, is supplied to the inside of the laser guide 19 above the transmission aperture 6 within the housing 5 of the laser drill bit 1, specifically through an air inlet 20 located inside the housing 5.

[0056] - A double tube 21 is concentrically arranged around the laser guide tube 19 with a radial gap, through which liquid nitrogen flows through the annular space 21a of the double tube 21;

[0057] - Insulating tube 22, concentrically surrounding double tube 21 with radial gap;

[0058] - Outer protective tube 23, concentrically surrounding insulating tube 22 with radial gaps.

[0059] These annular spaces surrounding the dual tubes 21 are evacuated relative to the laser guide tube 19 and the insulating tube 21 to ensure that the liquid nitrogen flowing through the annular spaces of the dual tubes 21 remains adequately insulated.

[0060] The annular space between the outer protective tube 23 and the insulating tube 22 is connected to the cooling airflow 24 that returns from the housing 5 of the laser drill bit 1 and fully cools the outside of the drill rod 2.

[0061] The outer casing 23 is made of steel, ensuring good stability and load-bearing capacity of the overall drill pipe 2. In contrast, the tubes located inside the casing 23 (i.e., the laser guide tube 19, the double tube 21, and the insulating tube 22) are made of carbon fiber reinforced plastic (CFP).

[0062] In addition, one or more tubes surrounded by the outer sheath 23 are equipped with electrical conductors (not shown in detail in the figure) for transmitting electrical energy and electrical signals in the direction of the laser drill bit 1.

[0063] To simplify the operation of drill pipe 1, it is subdivided into longitudinal sections that can be joined together at their ends via threaded socket joints 25 and 26. The adjacent portions of the laser guide tube 19, the annular space of the double tube 21, and the annular space between the outer sheath 23 and the insulating tube 22 are joined together in an aligned and pressure-sealed manner within the areas of these threaded socket joints 25 and 26. Furthermore, the adjacent portions of the electrical conductors are electrically connected to each other. In contrast, to isolate the double tube 21, the annular spaces present in each section of drill pipe 2 are evacuated, individually sealed by pressure sealing, and not connected to each other.

[0064] Finally, holding devices 27 are arranged at intervals inside the transmission aperture 6 of the laser beam 7 and / or inside the laser guide tube 19 to hold the lens or mirror system that deflects the laser beam 7. These holding devices 27 are formed in a way that protects the airflow 18 from passing through, i.e., they are equipped with corresponding through holes around the periphery.

[0065] The housing 5 of the laser drill bit 1 is equipped with several solenoid valves and a volumetric flow regulator, which can be activated by a signal conductor contained in the drill rod 2. These valves, as needed, distribute liquid nitrogen supplied to the housing 5 via the dual tubes 21 to the delivery jet nozzles 16 and 17, the gaseous nitrogen collection tank 13, the heating device 11 of the heated gas flow 10, and the internal space of the housing. During this process, regulation occurs, ensuring that the system maintains thermodynamic equilibrium despite being powered by the laser beam.

[0066] The system shown in the diagram works as follows:

[0067] A high-power laser generator located outside the borehole 4 directs a laser beam 7, with a power of 500kW to 700kW, into a laser guide tube 19 and guides it to the laser drill bit 1. Simultaneously, a protective gas flow 18 composed of clean nitrogen enters the laser guide tube 19 from below, ensuring that the laser beam experiences almost no attenuation on its journey to the laser drill bit 1. Within the laser drill bit 1, the laser beam 7 is then expanded by a beam expander 8 to cover the entire bottom 5b of the borehole.

[0068] While the laser beam 7 is expanding, the bottom 4b of the borehole is subjected to stress from the heated airflow 10. The heating device 11 pre-heats the airflow 10 to a temperature close to, or even exceeding, the melting temperature of the rock at the bottom 4b of the borehole. Under the action of the laser beam 7 and the heated airflow 10, the rock material on the surface of the bottom 4b of the borehole is peeled off through melting, evaporation, or spalling, and is pushed to the outer periphery of the bottom 4b of the borehole by the heated airflow 10.

[0069] During this process, an upward airflow 15 containing stripped rock material is formed in the outer peripheral region, pushing upward through the annular space between the outer shell 5c and the borehole wall 4a.

[0070] Liquid nitrogen and / or gaseous nitrogen are then blown into the rising conveyor airflow through the conveyor jet nozzles 16 and 17, thereby cooling and simultaneously intensifying the conveyor airflow 15. This rock-loaded conveyor airflow 15 is then delivered out of the borehole 4 through the annular space between the drill pipe 2 and the borehole wall 4a.

[0071] Figure Labels

[0072] 1. Laser drill bit

[0073] 2 Drill pipe

[0074] 3. Rock strata

[0075] 4. Drilling

[0076] 4a Drill hole wall

[0077] 4b Bottom of the drill hole

[0078] 5. Housing

[0079] 5a Top of the casing

[0080] 5b Bottom of the casing

[0081] 5c Housing Cover

[0082] 6. Transmission aperture

[0083] 7. Laser beam

[0084] 8. Beam expander

[0085] 9. Heating gas nozzle

[0086] 10 Heated airflow

[0087] 11 Heating device

[0088] 12 Clean the nozzle

[0089] 13 Nitrogen Collection Tank

[0090] 14 Clean airflow

[0091] 15. Transporting airflow

[0092] 16. Delivery jet nozzle

[0093] 17. Conveying jet nozzle

[0094] 18 Protective airflow

[0095] 19 Laser guide tubes

[0096] 20 Air Intake

[0097] 21 Dual-tube

[0098] 22 Insulating tubes

[0099] 23 Protective pipe

[0100] 24 Cooling airflow

[0101] 25 / 26 Socket joint

[0102] 27 Holding device

Claims

1. A method for drilling a borehole (4) in a rock stratum (3) by bombarding the bottom (4b) of the borehole with a laser beam (7), said laser beam being generated by a laser beam generator located outside the borehole and guided by appropriate auxiliary means to a laser drill bit (1) located at the bottom (4b) of the borehole and coupled to a drill rod (2), wherein, The nitrogen supplied to the laser drill bit (1) via the drill rod (2) is branched into: Used as a branch for protecting the airflow (18), protecting the transmitted laser beam (7) from interference by suspended particles; An additional branch, used for conveying airflow (15), transports rock material separated from the bottom (4b) of the borehole to the outside of the borehole (4) via the annular space between the drill rod (2) and the borehole wall (4a). Its features are, The laser beam (7) is guided to the laser drill bit (1) via a laser guide tube (19) extending along the length of the drill rod, and the protective airflow (18) is flowing through the unobstructed cross section of the laser guide tube (19). The nitrogen, in liquid form, is supplied to the laser drill bit (1) via the drill rod (2) and becomes a gaseous substance within the region of the laser drill bit (1); An additional branch is branched off from the supplied nitrogen to serve as a heating gas flow (10), which is heated by an electric heating device (11) associated with the laser drill bit (1) and directed toward the bottom (b) of the borehole where the laser beam (7) is bombarded.

2. The method according to claim 1, characterized in that, Liquid nitrogen is used as a transport gas, wherein the liquid nitrogen is injected into the area of ​​the laser drill bit (1) into a transport gas flow (15) that flows back from the bottom of the borehole and carries rock material separated from the bottom of the borehole, and becomes a gaseous substance in the transport gas flow (15) as the transport gas flow (15) and the rock material contained therein cool.

3. The method according to claims 1 and 2, characterized in that, A separate branch of the nitrogen supplied to the laser drill bit (1) branches off to serve as a cooling airflow (24), flows through the drill rod (2) and out of the borehole (4), cooling the drill rod (2) from the inside in the process.

4. The method according to any one of the preceding claims, characterized in that, A separate branch is branched off from the nitrogen supplied to the laser drill bit (1) to serve as a cleaning airflow (14), thereby keeping the laser beam exit aperture of the laser drill bit (1) at the bottom of the borehole (4b) clean.

5. An apparatus for performing the method according to claim 1, characterized in that, The drill pipe (2) has: A laser conduit (19) for transmitting the laser beam (7), through which the protective gas flow (18) flows. A double tube (21) is concentrically positioned around the laser guide tube (19) with a radial gap, through which liquid nitrogen flows. An insulating tube (22) is concentrically surrounding the double tube (21) with a radial gap. The outer sheath (23) concentrically surrounds the insulating tube (22) with radial gaps. in, The annular space surrounding the double tubes (21) is evacuated; The annular space between the outer protective tube (23) and the insulating tube (22) is connected to the cooling airflow (24) returning from the laser drill bit (1). The outer sheath (23) surrounds one or more tubes equipped with electrical conductors for transmitting electrical energy and electrical signals to the laser drill bit (1).

6. The device according to claim 5, characterized in that, The outer sheath (23) is made of steel, and the tubes arranged inside the outer sheath (23) are made of carbon fiber reinforced plastic (CFP).

7. The device according to claim 5 or 6, characterized in that, The drill pipe (2) is subdivided into longitudinal sections that are connected to each other at their ends by threaded socket joints (25, 26), wherein in the area of ​​these socket joints (25, 26); The adjacent portions of the laser conduit (19), the annular space of the double tube (21), and the adjacent portions of the annular space between the outer sheath (23) and the insulating tube (22) are joined together in an aligned and pressure-sealed manner. The adjacent portions of the electrical conductors are electrically connected to each other. The continuous portions of the evacuated annular space surrounding the double tubes (21) are closed by pressure sealing and do not connect with each other.

8. The device according to claim 5 or 6, characterized in that, The laser drill bit (1) has a housing (5), the top (5a) of which is fastened to the outer sheath (23) of the drill rod (2), wherein the housing (5) is also equipped with: A transmission channel is provided, through which the laser beam extends through the housing (5) and connects to the laser guide (19) of the drill rod (2), and a beam expander (8) is provided in the area at the bottom (5b) of the housing to cover the outlet aperture of the transmission channel. Devices for propagating and / or evaporating the arriving liquid nitrogen and for storing and branching gaseous nitrogen into various streams are arranged in the internal space of the housing and connected to the annular space of the double tube (21) of the drill pipe (2); Delivery jet nozzles (16, 17) for injecting liquid nitrogen and / or gaseous nitrogen into the delivery gas flow (15) are arranged in the housing cover (5c) and extend obliquely in the flow direction of the delivery gas flow; The heating gas nozzle (9) of the heating gas flow (10) is arranged in the bottom (5b) of the housing and points in the direction of the bottom (4b) of the borehole; The electric heating device (11) of the heating airflow (10) is arranged in the internal space of the shell; Solenoid valves and volumetric flow regulators used to control all nitrogen branches.

9. The device according to claim 8, characterized in that, The branch used as cooling airflow (24) passes through the internal space of the housing, wherein the internal space of the housing and the annular space between the outer protective tube (23) of the drill rod (2) and the insulating tube (22) are in communication.

10. The device according to claim 8, characterized in that, A cleaning nozzle (12) is arranged in the bottom (5b) of the housing as a branch of the cleaning airflow (14), extending parallel to the lower side of the bottom (5b) of the housing and aligned with a beam expander (8) covering the transmission aperture (6) of the laser beam.

11. The device according to claim 8, characterized in that, The transmission aperture (6) of the laser beam (7) is provided with an air inlet (20) inside the housing (5) of the laser drill bit (1) for the branch flow used as a protective airflow (18).

12. The device according to claim 5 or 6, characterized in that, The interior of the transmission aperture (6) of the laser beam (7) and / or the interior of the laser guide tube (19) are provided with spaced-apart retaining devices (27) for holding the lens and / or mirror system that deflects the laser beam (7), wherein the retaining devices (27) are formed in a manner permeable to the gas in the protective gas flow (18).

Images