CN114658361A - Drill bit direction control device and directional core drill - Google Patents

Abstract

The invention discloses a drill bit direction control device, which comprises an inner eccentric ring, a clutch and a coupler, wherein the inner eccentric ring is used for being sleeved on the outer side of a central shaft of a drill bit so as to drive the central shaft to radially deviate during rotation; the input end of the clutch is in torque transmission connection with the coupler, and the output end of the clutch is in torque transmission connection with the inner eccentric ring. In the drill bit direction control device, the torque of the central shaft is selectively transmitted to the inner eccentric ring through the clutch and the coupler so as to control the inner eccentric ring to rotate, and then the eccentric adjustment of the central shaft can be realized so as to realize the direction adjustment of the drill bit. The direction can be adjusted by directly utilizing the torque of the central shaft, so that the direction adjustment is convenient and simple. In conclusion, the drill bit direction control device can effectively solve the problem that the drill bit direction control is inconvenient. The invention also discloses a directional core drill bit comprising the drill bit direction control device.

Description

Drill bit direction control device and directional core drill

Technical Field

The invention relates to the technical field of geological exploration, in particular to a drill bit direction control device and a directional core drill bit comprising the drill bit direction control device.

Background

The existing directional coring technology mainly adopts a screw drill to directionally drill holes without coring, and after the drill reaches a designed coring position, the conventional coring drill is adopted to drill the cores. The method has the advantages of limited coring length, uncontrollable coring drilling track, limited acquired geological information, complex operation and low drilling efficiency.

The invention provides a direction control device of a directional core drill, which adopts a directional rotary guide system structure, controls the deflection degree of a central shaft by adjusting the rotating angle of an inner eccentric ring, and controls the drilling direction by connecting the central shaft with a drill bit. The rotation of the central shaft can be transmitted to the inner eccentric ring through the coupler, the electromagnetic clutch and the speed reducer, and the rotation degree of the inner eccentric ring can be controlled by controlling the opening and closing of the electromagnetic clutch. The predicted track data and control command of the drill hole are pre-stored in a controller of the drilling tool, when coring drilling, the sensor can automatically detect the inclination angle, azimuth angle and tool face angle of the drill hole, compare and analyze the data with preset values in the controller, then automatically calculate and correct, and send out commands to control the opening and closing of the electromagnetic clutch, thereby controlling the drilling direction.

For example, chinese patent CN112252972A discloses an eccentric ring type horizontal directional core drill direction control device, which comprises an outer core tube and an inner core tube, wherein the inner core tube is disposed in the outer core tube, an eccentric mechanism is disposed on the outer wall of the outer core tube, and the eccentric mechanism comprises an inner eccentric ring, an outer eccentric ring and a control motor. The invention also provides an eccentric ring type horizontal directional core drilling tool provided with the direction control device, which comprises a shell, a shell clamping device, an outer tube assembly and an inner tube assembly, wherein the outer tube assembly and the inner tube assembly are arranged in the shell, and the inner tube assembly is sequentially provided with a rope fishing device, an elastic clamping mechanism, a single-action mechanism, a directional measuring device and a core inner tube from left to right. This scheme adopts 2 motors to control the rotation of inside and outside eccentric ring respectively, needs 2 power supplies, and the energy consumption is higher, and need adopt hollow motor, and the structure is complicated relatively.

For example, chinese patent publication CN109779526A discloses a water pressure driven directional deflecting device, under the pressure of high-pressure water flow, the directional slips and the deflecting slips are separated from the inner through pipe respectively, and extend out to the radial outside of the inner through pipe, the radial extension height of the deflecting slips under the impact of high-pressure water flow is greater than the radial extension height of the directional slips under the impact of high-pressure water flow, and the extended deflecting slips prop against the hole wall, so that the drill bit is tilted, and the drill bit is drilled in the tilted state, thereby achieving the deflecting effect. This scheme adopts the rotatory guidance system of formula of pushing away, compares directional formula rotatory guidance system, and the wall of a well is coarser, has spiral well, and is not suitable for softer bottom.

For example, chinese patent publication CN111173452A discloses a static offset rotary steering drilling tool with a sandwich cylinder structure, which comprises a non-rotating sleeve, an offset control mechanism, a driving shaft assembly, a central shaft, and a drill bit, wherein the direction of the drill bit is controlled by the movement of a hydraulic system driving piston. This scheme has higher to the hydraulic oil cleanliness requirement, has the flush fluid in the drilling, can not mix with oil, consequently has high pressure dynamic seal problem between shell and mandrel, and the design is more complicated, and can not realize coring action.

When the existing directional core drill is used, the direction control operation of a drill bit is very inconvenient, and the drill bit cannot be deflected very quickly.

In summary, how to effectively solve the problem of inconvenient direction control of the drill bit is a problem that needs to be solved urgently by those skilled in the art.

Disclosure of Invention

In view of the above, the first object of the present invention is to provide a drill bit direction control device, which can effectively solve the problem of inconvenient drill bit direction control, and the second object of the present invention is to provide a directional core drill including the above drill bit direction control device.

In order to achieve the first object, the invention provides the following technical scheme:

a drill bit direction control device comprises an inner eccentric ring, a clutch and a coupler, wherein the inner eccentric ring is used for being sleeved on the outer side of a central shaft of a drill bit so as to drive the central shaft to radially deviate when rotating; the input end of the clutch is in torque transmission connection with the coupler, and the output end of the clutch is in torque transmission connection with the inner eccentric ring.

In the drill bit direction control device, when the drill bit direction control device is used, the drill bit direction control device is arranged at the central shaft, the central shaft penetrates through the eccentric hole of the inner eccentric ring, and the coupler is connected with the central shaft in a torque transmission mode. When needs are transferred to, the control clutch is in the closure state, and the center pin transmits the moment of torsion to the shaft coupling this moment, and the shaft coupling transmits the moment of torsion to the clutch, and because the clutch is in the closure state, can make the clutch transmit the moment of torsion to interior eccentric ring, and interior eccentric ring rotates and can drive the center pin off-centre to the realization is transferred to. And when steering is not required, only the clutch needs to be in a disconnected state. In the drill bit direction control device, the torque of the central shaft is selectively transmitted to the inner eccentric ring through the clutch and the coupler so as to control the inner eccentric ring to rotate, and then the eccentric adjustment of the central shaft can be realized so as to realize the direction adjustment of the drill bit. The direction can be adjusted by directly utilizing the torque of the central shaft, so that the direction adjustment is convenient and simple. In conclusion, the drill bit direction control device can effectively solve the problem that the direction control of the drill bit is inconvenient.

Preferably, the clutch further comprises a speed reducer, wherein a high-speed end of the speed reducer is in torque transmission connection with the output end of the clutch, and a low-speed end of the speed reducer is in torque transmission connection with the inner eccentric ring.

Preferably, the two ends of the speed reducer respectively transmit torque with the clutch and the inner eccentric ring through a matching key and a key groove which are axially raised.

Preferably, a bushing for sleeving the outer side of the central shaft is arranged on the inner side of the inner eccentric ring.

Preferably, the inner side of the rear section of the inner eccentric ring is provided with the bushing, the inner diameter of the front section is smaller than that of the rear section, and the front section is connected with the speed reducer.

Preferably, the eccentric ring further comprises an outer eccentric ring sleeved on the outer side of the inner eccentric ring, and a window used for displaying the rotary angle scale on the inner eccentric ring is formed in the outer eccentric ring.

Preferably, the outer eccentric ring is fixedly connected with the outer eccentric ring, and a step surface which is abutted against the forward shoulder surface of the coupler is arranged on the inner side of the outer shell.

Preferably, the outer shell includes backshell and preceding shell, backshell both ends are located respectively the cover the outer eccentric ring tip and on the preceding shell tip, the rear end face protrusion of preceding shell in the backshell medial surface sets up in order to form the step face.

Preferably, a centralizer is arranged on the outer side of the outer eccentric ring.

In order to achieve the second object, the invention also provides a directional core drill which comprises any one of the drill bit steering devices, a drill bit and a central shaft with the front end connected with the drill bit. Because the drill bit direction control device has the technical effects, the directional core drill bit with the drill bit direction control device also has the corresponding technical effects.

Preferably, the drill bit steering device further comprises a shell and a drill rod, wherein the drill bit steering device is installed in the shell; the rear end of the central shaft is connected with the drill rod through a cantilever bearing.

Preferably, the drill bit steering device comprises a sensor, and a controller for controlling clutch of the drill bit steering device is further arranged in the shell; the controller is internally provided with drilling predicted track data and a control command and is used for sending a command to control the clutch to be opened and closed; the sensor can automatically detect the well inclination angle, azimuth angle and tool face angle of the drill hole during directional core drilling, and can transmit the detection data to the controller; the controller can compare and analyze the data detected by the sensor with a preset value and send an instruction to control the opening and closing of the clutch after automatic calculation and correction. .

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic axial sectional view of a drill steering device according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a cross-sectional structure along direction DD of the drill bit steering device in FIG. 1;

FIG. 3 is a schematic diagram of an external structure of a drill steering device according to an embodiment of the present invention;

fig. 4 is a schematic external structural view of a coupling according to an embodiment of the present invention;

FIG. 5 is a schematic view of a directional core drill with its central axis unbent, according to an embodiment of the present invention;

FIG. 6 is a schematic view of a directional core drill with a curved central axis according to an embodiment of the present invention.

The drawings are numbered as follows:

the drill bit comprises a drill bit 1, a central shaft 2, a fulcrum bearing 3, a controller 4, a drill bit direction control device 5, a shell 6, a cantilever bearing 7, a drill rod 8, a corer 9, an outward convex key 21, a shaft outer side surface 22, an outer eccentric ring 51, a window 511, an outer ring inner surface 512, an inner eccentric ring 52, a rear section inner side surface 521, an inner ring outer surface 522, a second matching key 523, a bushing 53, a rear shell 54, a front shell 55, a step surface 551, a reducer 56, an output end key slot 561, an input end key slot 562, a clutch 57, a matching key slot 571, a first matching key 572, a coupler 58, an inner key slot 581, a third matching key 582, a forward shoulder surface 583, a directional outer side surface 584 and a centralizer 59.

Detailed Description

The embodiment of the invention discloses a drill bit direction control device, which is used for effectively solving the problem of inconvenient direction control of a drill bit.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 6, fig. 1 is a schematic axial sectional view of a drill direction control device according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a cross-sectional structure along direction DD of the drill bit steering device in FIG. 1; FIG. 3 is a schematic diagram of an external structure of a drill steering device according to an embodiment of the present invention; fig. 4 is a schematic external structural view of a coupling according to an embodiment of the present invention; FIG. 5 is a schematic view of a directional core drill with its central axis unbent, according to an embodiment of the present invention; FIG. 6 is a schematic view of a directional core drill with a curved central axis according to an embodiment of the present invention.

In one embodiment, the present embodiment provides a drill bit steering device, which is mainly applied to directional core drills, and particularly, the drill bit steering device comprises an inner eccentric ring 52, a clutch 57 and a coupling 58, so as to drive the central shaft 2 to deflect by controlling the rotation of the inner eccentric ring 52 of the eccentric assembly.

Specifically, the inner eccentric ring 52 is configured to be sleeved outside the central shaft 2 of the drill bit so as to drive the central shaft 2 to radially deflect when rotating, and the central shaft 2 radially deflects, so that the drill bit 1 connected to the front end of the inner eccentric ring can deflect. It should be noted that, the inside of the inner eccentric ring 52 is mainly provided with an eccentric hole, the size of the eccentric hole matches with the size of the central shaft 2, wherein the inner eccentric ring 52 rotates to drive the center of the eccentric hole to change the position, and further change the radial position of the central shaft 2.

And shaft coupling 58 wherein be used for with center pin 2 between the moment of torsion transmission be connected, in practical application, can with shaft coupling 58 can with center pin 2 between fixed connection to the transmission moment of torsion, if set up the through-hole, in order to conveniently carry out screw or bolted connection, also can be that to carry out the key-type connection between shaft coupling 58 and the center pin 2, in order to carry out moment of torsion transmission.

The torque transmission connection between the input end of the clutch 57 and the coupling 58 and the torque transmission connection between the output end of the clutch 57 and the inner eccentric ring 52 may be direct or indirect torque transmission connection, and the indirect torque transmission connection is intended to illustrate that other devices, such as a speed reducer 56, are arranged between the two. The clutch 57 may specifically adopt an electromagnetic clutch, or may adopt clutches of other structures, so as to facilitate electrically controlled clutching. The torque transmission connection can be fixed connection or key connection, and the torque transmission connection can transmit torque. In practice, it is possible to select whether or not torque is transmitted between the central shaft 2 and the inner eccentric ring 52 by controlling the clutching of the clutch 57. If torque is transmitted, the torque of the central shaft 2 can be transmitted to the inner eccentric ring 52; if no torque is transmitted, the rotation of the central shaft 2 will not drive the inner eccentric ring 52 to rotate, i.e. the rotation of the central shaft 2 and the inner eccentric ring 52 will not interfere with each other.

In the drill direction controller, in use, the drill direction controller is attached to the center shaft 2, the center shaft 2 is inserted into the eccentric hole of the inner eccentric ring 52, and the coupling 58 is connected to the center shaft 2 for torque transmission. When the direction needs to be adjusted, the clutch 57 is controlled to be in a closed state, the central shaft 2 transmits torque to the coupler 58, the coupler 58 transmits torque to the clutch 57, and because the clutch 57 is in the closed state, the clutch 57 can transmit torque to the inner eccentric ring 52, and the inner eccentric ring 52 rotates to drive the central shaft 2 to be eccentric, so that the direction is adjusted. And when steering is not required, it is only necessary to leave the clutch 57 disengaged. In the drill direction control device, the torque of the central shaft 2 is selectively transmitted to the inner eccentric ring 52 through the clutch 57 and the coupling 58 to control the rotation of the inner eccentric ring 52, so that the eccentric adjustment of the central shaft 2 can be realized to realize the direction adjustment of the drill 1. The direction can be adjusted by directly utilizing the torque of the central shaft 2, so that the direction adjustment is convenient and simple. In conclusion, the drill bit direction control device can effectively solve the problem that the direction control of the drill bit is inconvenient.

Further, considering that the rotation speed of the central shaft 2 is relatively fast and the steering of the drill bit 1 needs to be fine, in order to achieve better steering, it is preferable to further include a speed reducer 56, wherein a high speed end of the speed reducer 56 is connected with the output end of the clutch 57 in a torque transmission manner, and a low speed end of the speed reducer 56 is connected with the inner eccentric ring 52 in a torque transmission manner. So that the high-speed rotation output from the clutch 57 is reduced by the reduction gear 56 and then transmitted to the inner eccentric ring 52. It is of course also possible to arrange the speed reducer 56 between the clutch 57 and the coupling 58 so as to reduce the speed by the speed reducer 56 before the rotation is transmitted to the clutch 57.

Further, for the convenience of torque transmission, it is preferable that both ends of the reducer 56 transmit torque to the clutch 57 and the inner eccentric ring 52 through a mating key and a key groove, respectively, which are axially protruded. Specifically, for example, an input end key slot 562 and an output end key slot 561 may be respectively disposed at two ends of the speed reducer 56, wherein the input end key slot 562 is matched with the first matching key 572 of the clutch 57, and the output end key slot 561 is matched with the second matching key 523 on the inner eccentric ring 52. It is of course also possible to provide the reducer 56 with a mating key and the inner eccentric ring 52 and the clutch 57 with a keyway.

Correspondingly, the torque transmission connection between the clutch 57 and the coupling 58 may also be a key and a key slot, or may also be a fixed connection by a screw, a bolt, or the like, so as to transmit torque. Specifically, the coupling 58 may be provided with a third mating key 582 protruding axially, and correspondingly, the clutch 57 may also be provided with a mating key groove 571 mating with the third mating key 582.

The inner eccentric ring 52 is sleeved on the central shaft 2, in practical application, the central shaft 2 is to be able to rotate in the eccentric hole of the inner eccentric ring 52, and for convenience of rotation, it is preferable that a bushing 53 for sleeving the outer side of the central shaft 2 is arranged on the inner side of the inner eccentric ring 52. To facilitate mounting of the bushing 53, a groove may be provided inside the inner eccentric ring 52 to fit the mounting bushing 53. Specifically, the bushing 53 may be disposed on the inner side of the rear section of the inner eccentric ring 52, the diameter of the inner side surface 521 of the rear section is equal to the outer diameter of the bushing 53, the inner diameter of the front section is smaller than the inner diameter of the rear section, and the front section is connected to the speed reducer 56, wherein the inner diameter of the front section is preferably equal to the outer diameter of the central shaft 2 or has a gap therebetween, and the inner diameter of the front section is equal to the outer diameter of the central shaft, such as being capable of being disposed in a clearance fit manner. Correspondingly, as described above, the second engagement key 523 may be provided on the front stage. The inner surface of the bushing 53 is in clearance fit with the shaft outer side surface 22 of the central shaft 2, and the material of the bushing 52 is a copper piece or other softer material.

In practical applications, the outer eccentric ring 51 is further included, and the outer eccentric ring 51 is sleeved outside the inner eccentric ring 52, and in order to better understand the rotation angle of the inner eccentric ring 52 relative to the outer eccentric ring 51, it is preferable that the outer eccentric ring 51 is provided with a window 511 for displaying the rotation angle scale on the inner eccentric ring 52, and the scale of the rotation angle of the inner eccentric ring 52 can be seen through the window 511.

Wherein the inner eccentric ring 52 and the outer eccentric ring 51 are both eccentrically arranged, if the eccentricity of the outer eccentric ring 51 and the inner eccentric ring 52 is e, the radial displacement adjustment range of the central shaft 1 at the offset assembly 5 is 0-2 e, wherein e is any appropriate value set according to requirements. Since the inner eccentric ring 52 needs to rotate relative to the outer eccentric ring 51, it is preferable that the outer ring inner surface 512 of the outer eccentric ring 51 is an eccentric circle and is in clearance fit with the inner ring outer surface 522 of the inner eccentric ring 52 for the convenience of rotation.

Further, a casing is generally disposed at the front portion, wherein the casing is fixedly connected to the outer eccentric ring 51, and the casing can be disposed around the outer eccentric ring 51. It can also be that the rear end of shell and the front end fixed connection of outer eccentric ring 51, it is concrete, the front end of outer eccentric ring 51 is provided with the external screw thread, and the rear end of shell is provided with the internal thread of aforementioned external screw thread fit, the external diameter of shell and the external diameter of outer eccentric ring 51 are preferred equal this moment, for convenient righting this moment, it is preferred wherein the outside of outer eccentric ring 51 is provided with centralizer 59, for better fixed centralizer 59, can be provided with spacing recess in the outside of outer eccentric ring 51, in order to cooperate with centralizer 59. And wherein the reducer 56, the clutch 57 and the coupling 58 are arranged between the housing and the central shaft 2. The centralizer 59 is in contact with the hole wall, and the centralizer 59 is made of wear-resistant materials and can ensure that the axis of the outer surface of the outer eccentric ring 51 is coincident with the axis of the drill hole.

For better axial positioning of the coupling 58, here a step 551 is provided on the inside of the housing against a forward shoulder 583 of said coupling 58. For better radial positioning of the coupling 58, it is preferred here that the coupling 58 has a small diameter cylinder on the front side of the forward shoulder surface 583, wherein the directed outer side 584 of the small diameter cylinder cooperates with the inner side of the housing. In order to facilitate the torque transmission connection of the coupling 58 to the central shaft 2, it is preferable here that the inside of the small-diameter cylinder is provided with an inner key groove 581, and the shaft outer side surface 22 of the central shaft 2 is provided with an outer convex key 21 which is matched with the inner key groove 581.

Among them, for convenience of installation, it is preferable that the housing includes a rear case 54 and a front case 55. Two ends of the rear shell 54 are respectively sleeved on the end of the outer eccentric ring 51 and the end of the front shell 55 and are in threaded connection, and the rear end surface of the front shell 55 protrudes out of the inner side surface of the rear shell 54 to form the step surface 551, so that during assembly, the reducer 56, the clutch 57, the coupler 58 and the rear shell 54 can be assembled firstly, and then the front shell 55 is assembled, so that the whole installation is convenient. Wherein the step surface 551 is preferably a wear-resistant surface.

Based on the bit steering device 5 provided in the above embodiment, the present invention also provides a directional core drill, which includes any one of the bit steering devices 5 provided in the above embodiments, including a bit 1 and a central shaft 2 having a front end connected to the bit 1. The directional core drill uses the bit steering device in the above embodiments, so the above embodiments are referred to for the benefit of the directional core drill.

Further, in some embodiments, a housing 6 and a drill rod 8 are also provided, wherein the drill bit steering device 5 is installed in the housing 6; the rear end of the central shaft 2 is connected with the drill rod 8 through a cantilever bearing 7. A controller 4 for controlling the clutch 57 of the drill bit steering device 5 to be engaged and disengaged is also arranged in the housing 6, wherein the controller 4 is preferably arranged at the front side of the drill bit steering device 5. Wherein the front part of the central shaft 2 is supported by a fulcrum bearing 3.

Wherein the central shaft 2 is also provided with a core taking device 9, when the core filling the core taking device 9, the core taking device 9 can be extracted out of the hole in a rope fishing mode. The power of the drilling machine is transmitted to the drill bit 1 through the drill rod 8 and the central shaft 2 in sequence. Wherein the housing 6 is in a non-rotating state during directional core drilling. The fulcrum bearing 3 rotatably supports the central shaft 2 and allows a certain degree of inclination of the central shaft 2, thereby allowing the drill bit 1 to be inclined. The cantilever bearing 7 rotatably supports the central shaft 2 without allowing the central shaft 2 to tilt, avoiding that the bending of the central shaft 2 is transferred to the drill rod 8.

The controller 4 stores drilling predicted trajectory data and a control command, and can send a command to control the electromagnetic clutch 57 to be opened and closed. The drill bit direction control device 5 applies different radial displacements to the central shaft 2, so that the central shaft 2 is bent to different degrees, the drill bit 1 is driven to incline, and directional core drilling is realized.

When the directional core drilling is carried out, the sensors can automatically detect the well inclination angle, the azimuth angle and the tool face angle of the drill hole, the controller 4 compares and analyzes the data with preset values, then the data are automatically calculated and corrected, and an instruction is sent out to control the on-off of the clutch 57, so that the directional core drilling direction is controlled.

In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (12)

1. A drill bit direction control device comprises an inner eccentric ring (52), wherein the inner eccentric ring (52) is used for being sleeved on the outer side of a central shaft (2) of a drill bit so as to drive the central shaft (2) to radially deviate during rotation, and the drill bit direction control device is characterized by further comprising a clutch (57) and a coupler (58) used for being in torque transmission connection with the central shaft (2); the input end of the clutch (57) is connected with the coupling (58) in a torque transmission manner, and the output end of the clutch is connected with the inner eccentric ring (52) in a torque transmission manner.

2. Drill bit steering device according to claim 1, further comprising a speed reducer (56) having a high speed end in torque transmitting connection with the output of the clutch (57) and a low speed end in torque transmitting connection with the inner eccentric ring (52).

3. The drill bit steering device according to claim 2, wherein the reducer (56) transmits torque at both ends thereof to the clutch (57) and the inner eccentric ring (52) through an axially protruding mating key and a key groove, respectively.

4. Drill bit steering device according to claim 3, characterized in that inside the inner eccentric ring (52) a bushing (53) is arranged for sleeving outside the central shaft (2).

5. Drill steering device according to claim 4, characterized in that the bushing (53) is arranged inside the rear section of the inner eccentric ring (52), the inner diameter of the front section being smaller than the inner diameter of the rear section and the front section being connected to the reducer (56).

6. The drill bit direction control device according to any one of claims 1-5, further comprising an outer eccentric ring (51) sleeved outside the inner eccentric ring (52), wherein a window (511) for displaying a rotation angle scale on the inner eccentric ring (52) is opened on the outer eccentric ring (51).

7. Drill bit steering device according to claim 6, further comprising a housing fixedly connected to the outer eccentric ring (51), inside of which a step surface (551) is provided against the forward shoulder surface (583) of the coupling (58).

8. The device according to claim 7, wherein the housing comprises a rear shell (54) and a front shell (55), the rear shell (54) is sleeved on the end of the outer eccentric ring (51) and the end of the front shell (55), and the rear end surface of the front shell (55) protrudes from the inner side surface of the rear shell (54) to form the step surface (551).

9. Drill bit steering device according to claim 6, characterized in that the outer side of the outer eccentric ring (51) is provided with a centralizer (59).

10. A directional core drilling tool comprising a drill bit (1) and a central shaft (2) with a forward end connected to the drill bit (1), characterized by further comprising a drill bit steering device (5) according to any one of claims 1-9.

11. The directional core drill according to claim 10, further comprising a housing (6) and a drill rod (8), the drill bit steering device (5) being mounted within the housing (6); the rear end of the central shaft (2) is connected with the drill rod (8) through a cantilever bearing (7).

12. A directional core drill according to claim 10, characterized by comprising a sensor, a controller (4) for controlling the clutch (57) of the bit steering device (5) to engage and disengage being further arranged in the housing (6); the controller (4) is internally provided with drilling predicted track data and a control instruction and is used for sending the instruction to control the opening and closing of the clutch (57); the sensors can automatically detect the well inclination angle, azimuth angle and tool face angle of the drill hole during directional core drilling, and can transmit the detection data to the controller (4); the controller (4) can compare and analyze the data detected by the sensor with a preset value, and after automatic calculation and correction, sends out an instruction to control the opening and closing of the clutch (57).

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