Coring drill bit

Abstract

The utility model belongs to the technical field of coring tools, and particularly relates to a coring drill bit. The coring drill bit comprises a body, wherein a coring channel is coaxially arranged in the body; the blades are arranged on the body at intervals in the circumferential direction; the centralizing blocks are arranged on the outer side face of the body at intervals in the circumferential direction, and the centralizing blocks are connected with the blades; the flow channels are arranged on the body at intervals in the circumferential direction, and the flow channels are located between the adjacent blades; the blade comprises a tooth distribution face and a front side face, a front edge is formed between the tooth distribution face and the front side face in a chamfering mode, a plurality of cutting teeth are arranged on the front edge, the sizes of the cutting teeth are not all the same, and the size of at least one cutting tooth is larger than 13 mm.

Description

Technical Field

[0001] The utility model belongs to the technical field of coring tools, and in particular relates to a coring drill bit. Background Art

[0002] A core drill bit is a hollow drill used to break rock and form a wellbore and core during coring operations in drilling projects. The cutting and hydraulic structures of a core drill bit play a role in its rock-breaking efficiency. Typically, the drilling industry increases the ROP of a core drill bit to improve the efficiency of coring operations. However, with the emergence of unconventional oil and gas resources and deep and extra-deep oil and gas resources, simply increasing the ROP of a core drill bit is insufficient to further improve the efficiency of coring operations.

[0003] Existing core drill bits are not aggressive enough when used in some mud shales and deep hard formations; the core drill bit flow channel design leads to insufficient water horsepower, which cannot fully flush the rock chips generated by the core drill bit cutting the formation, resulting in repeated cutting and mud packing; the core drill bit has too many cutting teeth, the tooth density is high, the cutting tooth pressure drop is low, and the penetration depth into medium-hard to hard formations is not deep enough; the crown structure of the core drill bit has low wear resistance, and the blade body is often worn, resulting in insufficient support for the core drill bit's cutting teeth, resulting in breakage or even falling off; the tungsten carbide welded gauge block cannot be repaired after wear, resulting in waste of the core drill bit body. Utility Model Content

[0004] In response to the above-mentioned technical problems, the present invention aims to provide a coring drill bit that can solve at least one of the above-mentioned technical problems.

[0005] According to the utility model, a coring drill bit is provided, comprising:

[0006] a body, wherein a coring passage is coaxially disposed within the body;

[0007] Blades are arranged on the body at intervals along the circumferential direction;

[0008] Centralizing blocks are arranged on the outer side surface of the body at intervals along the circumferential direction, and the centralizing blocks are connected to the blades;

[0009] flow channels are arranged on the body at intervals along the circumferential direction, and the flow channels are located between adjacent blades;

[0010] The blade includes a tooth surface and a front side surface, and a leading edge is formed between the tooth surface and the front side surface by setting a chamfer. A plurality of cutting teeth are set on the leading edge, and the sizes of the cutting teeth are not all the same. The size of at least one cutting tooth is greater than 13 mm.

[0011] In a specific embodiment, the tooth-distributing surface includes an inclined surface, and the inclined surface is located at the end of the blade close to the central axis of the body, playing a straightening role.

[0012] In a specific embodiment, the tooth-laying surface includes a parabolic surface connected to the inclined surface, and an impact tooth is provided at the junction of the inclined surface and the parabolic surface.

[0013] In a specific embodiment, the axial projection of the front side surface is an arc, and the center of the arc is located in the opposite direction of the rotation of the coring drill bit in cutting the formation.

[0014] In a specific embodiment, the blade includes a rear side surface, a rear edge is formed between the cloth tooth surface and the rear side surface by setting a chamfer, anti-wear teeth are provided at the end of the rear edge close to the center axis, and the top of the rear side surface is connected to the rear edge by setting a rounded corner.

[0015] In a specific embodiment, the main body includes a cylinder and a crown coaxially arranged on the top of the cylinder, the inner diameter of the crown is smaller than the inner diameter of the cylinder, the flow channel includes a water eye arranged on the crown, a nozzle is arranged in the water eye, and a limiting step for limiting the movement of the nozzle is arranged in the water eye, and the limiting step is located on the outside of the nozzle.

[0016] In a specific embodiment, a boss for straightening the core is provided on one side of the blade close to the central axis, the inner diameter of the boss is smaller than the inner diameter of the crown, and a drill mouth flow channel groove is formed between adjacent bosses, and the drill mouth flow channel groove is connected to the flow channel.

[0017] In a specific embodiment, straightening edges for straightening the cutting core assembly are arranged at intervals along the circumference on the inner wall of the cylinder, and guide grooves are formed between adjacent straightening edges. Conical grooves are arranged at intervals along the circumference on the inner side of the crown, and the conical grooves connect the guide grooves, the water holes and the drill mouth flow channel grooves.

[0018] In a specific embodiment, a plurality of first gauge teeth are provided on the blade, the first gauge teeth are located on both sides of the setting direction of the cutting teeth, and the first gauge teeth are PDC composite pieces.

[0019] In a specific embodiment, the first gauge teeth include inner gauge teeth arranged on the inner side of the cutting teeth and outer gauge teeth arranged on the outer side of the cutting teeth. The outer gauge teeth have a downward rake angle to provide a back-marking function.

[0020] In a specific embodiment, a second gauge tooth is provided on the outer surface of the straightening block, the second gauge tooth protrudes from the straightening block by 0.5 to 1 mm, and the second gauge tooth is a PDC composite piece.

[0021] In a specific embodiment, the blade and the crown are surface-welded with wear-resistant material.

[0022] Compared with the prior art, the advantages of this application are as follows.

[0023] The utility model has four blades, which is a small number of blades, thereby reducing the overall number of cutting teeth, increasing the cutting tooth pressure ratio, and improving the aggressiveness.

[0024] The blade's tooth surface and front side are curved, facilitating chip removal. The cutting teeth are larger than the conventional 13mm, utilizing 16mm PDC composite inserts. This increases the height of the cutting teeth above the blade, improving engagement depth. The number of cutting teeth on a single blade is reduced, increasing the specific pressure per tooth and contributing to greater engagement depth.

[0025] The multiple cutting teeth of the blade are set to be mixed in different sizes, specifically using 13mm and 16mm PDC composite pieces. When the core drill bit rotates, the large and small teeth on the same track provide high and low step cutting effects, improving the cutting efficiency of the cutting teeth in difficult-to-penetrate formations.

[0026] The tooth surface of the blade is provided with an inclined surface. When the core drill bit rotates, the inclined surface can contact the formation, play a certain straightening role, and improve the stability of the drill bit.

[0027] Inner and outer diameter-maintaining teeth are provided on the inner and outer sides of the cutting teeth of the blade to improve the stability of the drill bit.

[0028] The cutting teeth can be set to various shapes of special-shaped teeth. For example, the cutting teeth can be set to conical teeth to increase the auxiliary rock breaking function brought by the impact and control the depth of the cutting teeth into the formation.

[0029] The drill bit body is equipped with a tapered groove. The conical surface structure helps guide the drilling fluid in the diversion groove to the water hole. The tapered groove is treated to prevent erosion and wear, improving the safety of the drill bit. The water hole is equipped with a nozzle, and the nozzle size can be adjusted according to the expected formation to be drilled.

[0030] The nozzle of a conventional drill bit is fixed in the water hole from the outside to the inside through a threaded connection. Due to the structure of the core drill bit, the nozzle is not firmly fixed and often falls off. The present application provides a stop step in the water hole, and the nozzle is inserted into the water hole from the inside to the outside from the inside of the body, which can effectively prevent the water hole from detaching from the body.

[0031] The use of PDC composite sheets as gauge cutters facilitates repairs when the drill bit is returned to the factory. Wear-resistant materials are welded on the blades and crown to improve the drill bit's erosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be described below with reference to the accompanying drawings.

[0033] Figure 1 A schematic diagram of an embodiment of a core drill bit proposed according to the present utility model;

[0034] Figure 2 A schematic diagram of an embodiment of a core drill bit proposed according to the present utility model;

[0035] Figure 3 A schematic diagram of an embodiment of a core drill bit proposed according to the present utility model;

[0036] Figure 4 Schematic cross-sectional view of the core drill bit proposed according to the utility model;

[0037] Figure 5 Schematic diagram of the axial direction of the core drill bit proposed by the present invention;

[0038] Figure 6 The figure is a schematic diagram of the internal structure of the core drill bit proposed according to the utility model.

[0039] The reference numerals in the figures are as follows:

[0040] 1. Main body; 11. Cylinder; 12. Crown;

[0041] 2. Blade; 21. Toothed surface; 211. Inclined surface; 212. Parabolic surface; 22. Front side; 23. Leading edge; 24. Blade front root; 25. Rear side; 26. Rear edge; 27. Blade rear root; 28. Boss;

[0042] 3. Cutting teeth; 31. 16mm special-shaped teeth; 32. 13mm special-shaped teeth; 33. Inner gauge-keeping teeth; 34. Outer gauge-keeping teeth; 35. Anti-wear teeth; 36. Impact teeth; 37. Secondary gauge-keeping teeth;

[0043] 4. Flow channel; 41. Water hole; 411. Limiting step; 42. Nozzle; 43. Guide groove; 44. Conical groove; 45. Drill mouth flow channel groove;

[0044] 5. Straightening block;

[0045] 6. Coring channel;

[0046] 7. Connecting thread;

[0047] 8. Core;

[0048] 10. Cutting heart assembly;

[0049] 100. Core drill bit.

[0050] In this application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0051] The present invention will be described below with reference to the accompanying drawings.

[0052] It should be noted that the directional terms or qualifiers "upper", "lower", "left", "right" etc. used in this application are all relative to the referenced Figure 1 They are not intended to limit the absolute positions of the components involved, but may vary according to specific circumstances. The directional terms or qualifiers used in this application, such as "axial direction," "circumferential direction," "center axis," and "radial direction," are all relative to the body 1, i.e., the axial direction of the body 1, the circumferential direction of the body 1, the center axis of the body 1, and the radial direction of the body 1.

[0053] Figure 1 FIG. 1 shows the structure of the core drill bit 100 according to the present invention. Figure 1 As shown, the core drill bit 100 mainly includes a body 1, blades 2, cutting teeth 3, flow channels 4 and straightening blocks 5.

[0054] In this embodiment, a coring channel 6 is coaxially provided in the body 1. Figure 4 As shown, during the coring process, the core cutting assembly 10 is coaxially arranged in the coring channel 6 in the body 1, and the flow channel 4 is formed in the annular space between the core cutting assembly 10 and the body 1. The core cutting assembly 10 is well known to those skilled in the art and will not be described in detail here.

[0055] like Figure 1 As shown, multiple blades 2 are evenly spaced along the circumferential direction on the body 1. In this embodiment, four blades 2 are provided on the body 1. The number of blades 2 is less than that of a conventional core drill bit, thereby reducing the overall number of cutting teeth 3 on the blades 2, increasing the specific pressure of the cutting teeth 3, and improving the aggressiveness.

[0056] It is easy to understand that for different formations and applicable wellbore sizes, the number of blades 2 can be changed, preferably reducing one blade or increasing 1 to 2 blades, while the shape of the blade remains unchanged.

[0057] In a specific embodiment, Figure 2As shown, the blade 2 includes a tooth surface 21, a front side 22, and a rear side 25. The front side 22 is the side of the blade 2 facing the formation during the drilling process of the core drill bit 100. The rear side 25 is the side of the blade 2 facing away from the formation during the drilling process of the core drill bit 100. The tooth surface 21 is the surface between the front side 22 and the rear side 25.

[0058] The cutting teeth 3 are located on the tooth surface 21 of the blade 2. In this embodiment, the cutting teeth 3 are larger than 13 mm, meaning their diameter is greater than 13 mm. Specifically, the cutting teeth 3 in this embodiment are constructed from PDC composite sheets with a diameter of 16 mm. This increased size increases the height of the cutting teeth 3 protruding from the blade 2, thus improving their penetration depth.

[0059] Increasing the size of the cutting teeth 3 will improve the firmness of the connection between the cutting teeth 3 and the blade wing 2. In this embodiment, a front edge 23 is formed between the tooth surface 21 and the front side 22 by setting a chamfer, and a plurality of cutting teeth 3 are provided on the front edge 23. The plurality of cutting teeth 3 are arranged in sequence along the direction of the boundary line between the tooth surface 21 and the front side 22, and are thus provided on the front edge 23. By providing the front edge 23, the cutting teeth 3 can be buried deeper in the blade wing 2, thereby improving the support force of the blade wing 2 on the cutting teeth 3. In addition, the front edge 23 facilitates the exposure of the cutting teeth 3, and can ensure that the stratum will not contact the blade wing 2 during the process of the cutting teeth 3 cutting the stratum, thereby preventing the blade wing 2 from being worn and preventing the cutting teeth 3 from falling off. The front edge 23 can also ensure that the working surface of the cutting teeth 3 is more smoothly connected to the front side 22 of the blade wing 2.

[0060] In a preferred embodiment, the front edge 23 where the tooth surface 21 and the front side surface 22 are connected is set to an unequal-sided straight chamfer, and the size of the chamfer is adapted to the size of the corresponding cutting tooth 3.

[0061] In a preferred embodiment, the cutting teeth 3 are not all the same size. In this embodiment, two types of cutting teeth 3 are used, with diameters of 13 mm and 16 mm, arranged alternately. With this arrangement, as the core drill bit 100 rotates, the different sizes of cutting teeth 3 on the blades 2 can provide a stepped cutting effect, improving the cutting efficiency of the cutting teeth 3 in difficult-to-penetrate formations.

[0062] In one embodiment, the working surface of the cutting tooth 3 can be set to any shape such as a flat surface, a concave surface, a chisel shape, etc. That is, the cutting tooth 3 can adopt a special-shaped tooth structure. Figure 3 As shown, the cutting teeth 3 in this embodiment include 16 mm special-shaped teeth 31 and 13 mm special-shaped teeth 32 .

[0063] In a specific embodiment, the back rake angle of the cutting teeth 3 is 9-18 degrees, and the side turning angle is generally set to 3-8 degrees according to the formation.

[0064] like Figure 3 As shown, a plurality of first gauge teeth are provided on the blade 2, and the first gauge teeth are located on both sides of the setting direction of the cutting teeth 3, that is, the first gauge teeth are sequentially provided on the blade 2 along the arrangement direction of the cutting teeth 3. In this embodiment, the first gauge teeth include inner gauge teeth 33 provided on the inner side of the cutting teeth 3 and outer gauge teeth 34 provided on the outer side of the cutting teeth 3. The inner side here refers to the direction of the front edge 23 of the blade 2 close to the central axis, and the outer side refers to the direction of the front edge 23 away from the central axis. Among them, the inner gauge teeth 33 are provided on the front edge 23 of the inclined surface 211. Both the inner gauge teeth 33 and the outer gauge teeth 34 use PDC composite sheets with a diameter of 13 mm.

[0065] In one embodiment, the outer gauge teeth 34 are tilted downward to provide a back-ream function.

[0066] In a specific embodiment, Figure 2 and Figure 3 As shown, a chamfer is provided between the tooth surface 21 and the rear side surface 25 to form a trailing edge 26. By providing the trailing edge 26, while ensuring that the blade 2 can adequately support the cutting teeth 3, the excess portion of the tooth surface 21 is removed, thereby reducing the possibility of direct contact between the blade 2 and the formation.

[0067] In this embodiment, the rear edge 26 where the tooth surface 21 and the rear side surface 25 are connected is set to be an unequal straight chamfer.

[0068] Anti-wear teeth 35 are provided at the end of the trailing edge 26 close to the central axis of the body 1. The end of the trailing edge 26 close to the central axis of the body 1 is the part of the top of the blade 2 that is easily worn. By providing the anti-wear teeth 35, the cutting coverage of the cutting teeth 3 can be supplemented to prevent the blade 2 from being worn.

[0069] In this embodiment, the anti-wear teeth 35 are flat teeth without support.

[0070] In a specific embodiment, the top of the rear side surface 25 is connected to the rear edge 26 by setting a rounded corner. In other words, the rear side surface 25 and the rear edge 26 are connected to each other by a rounded transition, further reducing the possibility of the blade 2 directly contacting the formation.

[0071] In a preferred embodiment, the tooth surface 21 includes an inclined surface 211 and a parabolic surface 212. The inclined surface 211 is located at the end of the tooth surface 21 close to the central axis of the body 1, and the portion of the tooth surface 21 excluding the inclined surface 211 is set as the parabolic surface 212.

[0072] When the tooth surface 21 is projected onto the rear side surface 25, the inclined surface 211 is projected as an inclined straight line, with one end closer to the central axis lower than the other. The parabolic surface 212 is projected as a parabola, with one end connected to the inclined surface 211 and the other end connected to the straightening block 5.

[0073] Under the action of the inclined surface 211 , when the core drill bit 100 drills into the formation, the inclined surface 211 can form a cone surface in the formation. The inclined surface 211 and the cone surface formed by the formation fit together, which plays a role in straightening the core drill bit 100 .

[0074] In one embodiment, impact teeth 36 are provided at the intersection of the inclined surface 211 and the parabolic surface 212. It will be readily appreciated that impact teeth 36 can be embedded in individual blades 2. In this embodiment, impact teeth 36 are conical PDC composite pieces. Depending on the formation, the depth of the impact teeth 36 protruding from the blade 2 can be controlled to control the penetration depth of the chip teeth 3 into the formation, thereby simultaneously hammering the formation and assisting in rock breaking.

[0075] In one specific embodiment, the axial projection of the front side surface 22 is an arc, with the center of the arc located in the direction opposite to the rotation of the core drill bit 100 when cutting the formation. In this configuration, the front side surface 22 is configured as an arc with the middle portion convex away from the rear side surface 25 relative to the radial portions. In this configuration, rock cuttings generated by cutting the formation can be more smoothly discharged from the gaps between adjacent blades 2.

[0076] In the present embodiment, the axial projection of the rear side 25 is a straight line, that is, the rear side 25 is configured as a plane. By this arrangement, it can be distinguished from the front side 22 and the cutting teeth 3 can be installed in the wrong position during the production of the core drill bit 100.

[0077] like Figure 1 As shown, multiple straightening blocks 5 are evenly arranged on the outer surface of the main body 1 in an interval manner along the circumferential direction. The number of straightening blocks 5 is the same as the number of blade wings 2 and corresponds one to one. Each straightening block 5 is connected to its corresponding blade wing 2, and the straightening blocks 5 are connected to the lower part of the blade wing 2.

[0078] The circumferential side surfaces of the straightening block 5 are adapted to be connected to the front side surface 22 and the rear side surface 25 of the blade 2. In other words, one side surface of the straightening block 5 is flush with the rear side surface 25 of the blade 2; the other side surface of the straightening block 5 is configured as an arc-shaped surface with the same curvature as the front side surface 22 of the blade 2, and the two are smoothly connected.

[0079] In a preferred embodiment, Figure 3As shown, a second gage cutter 37 is provided on the outer side of the straightening block 5. The outer side of the straightening block 5 refers to the side of the straightening block 5 away from the central axis. Specifically, a hole is drilled in the straightening block 5, and then the second gage cutter 37 is inserted into the hole. The second gage cutter 37 provides wear protection, maintains gage, and crushes rock debris.

[0080] In a specific embodiment, the second gauge teeth 37 installed on the straightening block 5 are 13 mm PDC composite sheet cambered teeth, protruding from the straightening block 5 and extending 0.5 to 1 mm radially, playing the role of anti-wear, gauge maintenance and crushing rock debris.

[0081] The parts where the blade 2 and the straightening block 5 are connected to the body 1 adopt arc transition. Figure 2 As shown, the rounded corner between the front side surface 22 of the blade wing 2 and the body 1 forms the blade wing front root 24, and the rounded corner between the rear side surface 25 of the blade wing 2 and the body 1 forms the blade wing rear root 27, and the same applies to the straightening block 5.

[0082] In this embodiment, the flow channels 4 are arranged on the body 1 at intervals along the circumferential direction. The number of the flow channels 4 is the same as the number of the blades 2 , and a flow channel 4 is provided between adjacent blades 2 .

[0083] In a specific embodiment, Figure 1 As shown, the body 1 includes a barrel 11 and a crown 12 coaxially arranged on the top of the barrel 11. The barrel 11 is constructed in a generally cylindrical shape. The inner side of the lower end of the barrel 11 is provided with a thread for connecting to the coring outer barrel (not shown in the figure). The crown 12 is coaxially arranged on the upper end of the barrel 11. The top of the crown 12 is configured as a spherical surface.

[0084] like Figure 4 As shown, the inner diameter of the crown 12 is smaller than the inner diameter of the barrel 11, and the flow channel 4 includes a water hole 41 provided on the crown 12. A nozzle 42 is provided in the water hole 41, and a limiting step 411 for limiting the movement of the nozzle 42 is provided in the water hole 41. The limiting step 411 is located outside the nozzle 42, and the outside here refers to Figure 4 Under this arrangement, the nozzle 42 can enter the water eye 41 from the inside of the body 1, and under the action of the limiting step 411, the nozzle 42 will not be separated from the water eye 41.

[0085] like Figure 2 As shown, a boss 28 for stabilizing the core is provided on one side of the blade 2, near the central axis. The inner diameter of boss 28 is smaller than that of crown 12. This arrangement allows boss 28 to position the core column during core drilling, reducing circumferential offset during rotation of the core drill bit 100 and ensuring that the core is not ground down. As will be readily understood, the inner surface of boss 28 is configured as an arcuate surface that matches the outer diameter of the core.

[0086] A drill bit flow channel groove 45 is formed between adjacent bosses 28. Figure 4 As shown, the drill bit mouth flow channel groove 45 is connected to the flow channel 4. Under this arrangement, the drilling fluid can flush the core through the drill bit mouth flow channel groove 45, flushing the attachments on the core and cooling the inner gauge cutter 33 at the same time.

[0087] like Figure 4 and Figure 5 As shown, straightening ridges for straightening the core cutting assembly 10 are provided at intervals along the circumference of the inner wall of the barrel 11. This helps center the core cutting assembly 10 and facilitates the entry of the core into the coring tool. Diversion grooves 43 are formed between adjacent straightening ridges, and the number of diversion grooves 43 is the same as the number of water holes 41. Conical grooves 44 are provided at intervals along the circumference of the inner side of the crown 12. These connect the diversion grooves 43, the water holes 41, and the drill head flow channel 45. Serving as a transition between the diversion grooves 43 and the water holes 41, the conical grooves 44 can prevent fluid energy loss and provide better diversion.

[0088] The drilling fluid flows along the guide groove 43, the tapered groove 44, the nozzle in the water hole 41, and the channel between the adjacent blades 2 between the body 1 and the wellbore.

[0089] When the coring drill bit 100 is performing coring work, the drilling fluid flows along two flow channels 4, which are the flow channels 4 formed by the guide groove 43, the tapered groove 44, the nozzle in the water eye 41, and the channel between the adjacent blades 2 between the main body 1 and the wellbore, and the flow channel 4 formed by the guide groove 43, the tapered groove 44, the drill bit mouth flow channel groove 45, and the channel between the adjacent blades 2 between the main body 1 and the wellbore.

[0090] In one embodiment, nozzle 42 is embedded or threaded within water hole 41. To prevent puncture of the steel body, nozzle 42 is made of carbide and features a curved flow surface. The outlet size can be adjusted as needed, typically 12 to 14 mm. The inclination angle of nozzle 42 (and water hole 41) is set at 8 to 9 degrees.

[0091] In a specific embodiment, the surfaces of the blade 2 and the crown 12 are welded or sprayed with wear-resistant materials, such as tungsten carbide microparticles, to improve hardness and smoothness, which is beneficial to wear prevention and chip removal.

[0092] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0093] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0094] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0095] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A coring drill bit, characterized in that: include: A body (1), wherein a coring channel (6) is coaxially arranged in the body (1); Blades (2) are arranged on the body (1) at intervals along the circumferential direction; A straightening block (5) is arranged on the outer side surface of the body (1) at intervals along the circumferential direction, and the straightening block (5) is connected to the blade (2); flow channels (4) are arranged on the body (1) at intervals along the circumferential direction, and the flow channels (4) are located between adjacent blades (2); The blade (2) comprises a tooth-laying surface (21) and a front side surface (22); a front edge (23) is formed between the tooth-laying surface (21) and the front side surface (22) by arranging a chamfer; a plurality of cutting teeth (3) are arranged on the front edge (23); the sizes of the cutting teeth (3) are not all the same; and the size of at least one of the cutting teeth (3) is greater than 13 mm.

2. The core drill bit according to claim 1, characterized in that The tooth-laying surface (21) comprises an inclined surface (211), and the inclined surface (211) is located at the end of the blade (2) close to the central axis of the body (1), and plays a straightening role.

3. The core drill bit according to claim 2, characterized in that The tooth-distributing surface (21) comprises a parabolic surface (212) connected to the inclined surface (211), and an impact tooth (36) is provided at the junction of the inclined surface (211) and the parabolic surface (212).

4. The core drill bit according to claim 1, characterized in that The axial projection of the front side surface (22) is an arc, and the center of the arc is located in the opposite direction of the rotation of the core drill bit in cutting the formation.

5. The core drill bit according to claim 1, characterized in that The blade (2) includes a rear side surface (25), a rear edge (26) is formed between the tooth-closing surface (21) and the rear side surface (25) by arranging a chamfer, an anti-wear tooth (35) is arranged at the end of the rear edge (26) close to the central axis, and the top of the rear side surface (25) is connected to the rear edge (26) by arranging a fillet.

6. The core drill bit according to claim 1, characterized in that The body (1) comprises a cylinder (11) and a crown (12) coaxially arranged on the top of the cylinder (11); the inner diameter of the crown (12) is smaller than the inner diameter of the cylinder (11); the flow channel (4) comprises a water eye (41) arranged on the crown (12); a nozzle (42) is arranged in the water eye (41); a limiting step (411) for limiting the movement of the nozzle (42) is arranged in the water eye (41); the limiting step (411) is located outside the nozzle (42).

7. The core drill bit according to claim 6, characterized in that A boss (28) for straightening the core is provided on one side of the blade (2) close to the central axis, the inner diameter of the boss (28) is smaller than the inner diameter of the crown (12), and a drill mouth flow channel groove (45) is formed between adjacent bosses (28), and the drill mouth flow channel groove (45) is connected to the flow channel (4).

8. The core drill bit according to claim 7, characterized in that Straightening ridges for straightening the cutting core assembly (10) are arranged at intervals along the circumference on the inner wall of the cylinder (11), and guide grooves (43) are formed between adjacent straightening ridges. Conical grooves (44) are arranged at intervals along the circumference on the inner side of the crown (12), and the conical grooves (44) connect the guide grooves (43), the water holes (41) and the drill mouth flow channel groove (45).

9. The core drill bit according to claim 1, characterized in that A plurality of first gauge teeth are provided on the blade (2), the first gauge teeth are located on both sides of the arrangement direction of the cutting teeth (3), and the first gauge teeth are PDC composite pieces.

10. The core drill bit according to claim 9, characterized in that The first gauge teeth comprise inner gauge teeth (33) arranged on the inner side of the cutting teeth (3) and outer gauge teeth (34) arranged on the outer side of the cutting teeth (3); the outer gauge teeth (34) have a downward tilt angle to provide a back-marking function.

11. The core drill bit according to claim 1, wherein: A second gauge tooth (37) is provided on the outer surface of the straightening block (5), the second gauge tooth (37) protruding from the straightening block (5) by 0.5 to 1 mm, and the second gauge tooth is a PDC composite piece.

12. The core drill bit according to claim 6, characterized in that The surfaces of the blade (2) and the crown (12) are welded with wear-resistant materials.

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