A core drill

Abstract

This invention belongs to the field of coring tool technology, specifically, it relates to a coring drill bit. The coring drill bit includes: a body with a coring channel coaxially disposed within the body; circumferentially spaced cutting wings disposed on the body; circumferentially spaced straightening blocks disposed on the outer surface of the body, the straightening blocks being connected to the cutting wings; and circumferentially spaced flow channels disposed on the body, the flow channels being located between adjacent cutting wings; each cutting wing includes a tooth-spreading surface and a front surface, a leading edge being formed between the tooth-spreading surface and the front surface by a chamfer, and a plurality of cutting teeth being disposed on the leading edge, the cutting teeth not all being of the same size, at least one of the cutting teeth having a size greater than 13 mm.

Description

Technical Field

[0001] This invention belongs to the field of coring tool technology, specifically, it relates to a coring drill bit. Background Technology

[0002] A core drill bit is a hollow drill bit used in drilling operations to break rocks and form a wellbore and core. The cutting structure and hydraulic structure of a core drill bit both influence its rock-breaking efficiency. Typically, the drilling industry increases the mechanical drilling speed of the core drill bit to improve the efficiency of core drilling operations. However, with the emergence of unconventional oil and gas resources and deep and ultra-deep oil and gas resources, simply increasing the mechanical drilling speed of the core drill bit is no longer sufficient to further improve the efficiency of core drilling operations.

[0003] Existing core drill bits lack sufficient attack power when used in some mudstone and shale formations and deep hard formations; the flow channel design of core drill bits results in insufficient hydraulic power, which cannot fully flush away the rock cuttings generated by the core drill bit cutting the formation, causing repeated cutting and mud packing; the core drill bits have too many cutting teeth, and the high tooth density reduces the specific pressure of the cutting teeth, resulting in insufficient penetration depth into medium-hard to hard formations; the crown structure of the core drill bit has low wear resistance, and the cutter blade body wears frequently, resulting in insufficient support for the cutting teeth of the core drill bit, leading to breakage or even detachment; the tungsten carbide retainer blocks cannot be repaired after wear, resulting in waste of the core drill bit body. Summary of the Invention

[0004] In view of the technical problems described above, the present invention aims to provide a core drill bit that can solve at least one of the aforementioned technical problems.

[0005] According to the present invention, a core drill bit is provided, comprising:

[0006] The main body has a core extraction channel coaxially arranged within it.

[0007] Blade wings are arranged circumferentially on the body;

[0008] A straightening block is arranged circumferentially on the outer side of the body, and the straightening block is connected to the blade wing;

[0009] Circumferentially spaced flow channels are arranged on the body, and the flow channels are located between adjacent blades;

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

[0011] In one specific embodiment, the toothed surface includes an inclined surface located at the end of the blade near the central axis of the body, which serves to straighten it.

[0012] In one specific embodiment, the toothed surface includes a parabolic surface connected to the inclined surface, and impact teeth are provided at the intersection of the inclined surface and the parabolic surface.

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

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

[0015] In one specific embodiment, the body includes a cylindrical body and a crown coaxially disposed on the top of the cylindrical body. The inner diameter of the crown is smaller than the inner diameter of the cylindrical body. The flow channel includes a water eye disposed on the crown. A nozzle is disposed in the water eye. A limiting step for restricting the movement of the nozzle is disposed in the water eye. The limiting step is located outside the nozzle.

[0016] In one specific embodiment, a boss for straightening the rock core is provided on one side of the cutter wing near the central axis. The inner diameter of the boss is smaller than the inner diameter of the crown. A drill bit flow channel groove is formed between adjacent bosses, and the drill bit flow channel groove is connected to the flow channel.

[0017] In one specific embodiment, the inner wall of the cylinder is provided with circumferentially spaced straightening ridges for straightening the core cutting assembly, and a guide groove is formed between adjacent straightening ridges. A conical groove is provided circumferentially spaced on the inner side of the crown, and the conical groove connects the guide groove, the water eye and the drill bit inlet channel groove.

[0018] In one specific embodiment, a plurality of first diameter-maintaining teeth are provided on the blade wing. The first diameter-maintaining teeth are located on both sides of the setting direction of the cutting teeth, and the first diameter-maintaining teeth are PDC composite sheets.

[0019] In one specific embodiment, the first diameter-protecting tooth includes an inner diameter-protecting tooth disposed inside the cutting tooth and an outer diameter-protecting tooth disposed outside the cutting tooth, wherein the outer diameter-protecting tooth has a downward tilt angle to provide a reverse-scraping function.

[0020] In one specific embodiment, a second diameter-protecting tooth is provided on the outer surface of the straightening block. The second diameter-protecting tooth protrudes from the straightening block by 0.5 to 1 mm, and the second diameter-protecting tooth is a PDC composite sheet.

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

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

[0023] The present invention has four blades, which reduces the overall number of cutting teeth, increases the specific pressure of the cutting teeth, and improves the attack power.

[0024] The toothed surface of the blade and the front side are arc-shaped, which is beneficial for chip removal. The cutting teeth are larger than the conventional 13mm, specifically using 16mm PDC composite blades. This increases the height of the cutting teeth exposed on the blade, improves the depth of cut, and reduces the number of cutting teeth on a single blade, increasing the specific pressure per tooth, which is beneficial for improving the depth of cut.

[0025] The multiple cutting teeth of the cutter blade are configured with a mix of different sizes, specifically using 13mm and 16mm PDC composite plates. When the core drill bit rotates, the large and small teeth on the same track provide a stepped cutting effect, improving the cutting efficiency of the cutting teeth in formations that are difficult to penetrate.

[0026] The blades have inclined surfaces on their toothed surfaces. When the core drill bit rotates, the inclined surfaces can come into contact with the formation, which plays a certain role in straightening the drill bit and improving its stability.

[0027] The inner and outer diameter protection teeth of the cutting blade are provided to improve the stability of the drill bit.

[0028] The cutting teeth can be configured with various shapes and irregular shapes. For example, the cutting teeth can be configured as conical teeth to increase the rock-breaking function brought by impact, while controlling the depth of the cutting teeth into the formation.

[0029] The drill bit body features a conical groove. This conical structure facilitates the flow of drilling fluid from the guide groove to the water inlet. The conical groove is treated for erosion and wear resistance, improving drill bit safety. A water nozzle is installed inside the water inlet; its size can be changed based on formation predictions.

[0030] Conventional drill bits have their nozzles fixed inside the waterhole via a threaded connection. Due to the structure of core drill bits, the nozzles are not securely fixed and often fall off. This application incorporates a limiting step inside the waterhole, allowing the nozzle to be inserted from the inside of the drill body outwards, effectively preventing the waterhole from detaching from the drill body.

[0031] PDC composite discs are used as gauge protection teeth, facilitating drill bit repair at the factory. Wear-resistant material is welded onto the cutter wings and crown to improve the drill bit's erosion resistance. Attached Figure Description

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

[0033] Figure 1 This is a schematic diagram of an embodiment of the core drill bit proposed according to the present invention;

[0034] Figure 2 This is a schematic diagram of an embodiment of the core drill bit proposed according to the present invention;

[0035] Figure 3 This is a schematic diagram of an embodiment of the core drill bit proposed according to the present invention;

[0036] Figure 4 This is a cross-sectional schematic diagram of the core drill bit proposed according to the present invention;

[0037] Figure 5 This is an axial schematic diagram of the core drill bit proposed according to the present invention;

[0038] Figure 6 This is a schematic diagram of the internal structure of the core drill bit proposed according to the present invention.

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

[0040] 1. Body; 11. Cylindrical body; 12. Crown;

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

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

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

[0044] 5. Straighten the block;

[0045] 6. Heart extraction channel;

[0046] 7. Connecting thread;

[0047] 8. Core;

[0048] 10. Heart-cutting assembly;

[0049] 100. Core drill bit.

[0050] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

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

[0052] It should be noted that the directional terms or qualifiers used in this application, such as "up," "down," "left," and "right," are all specific to the referenced material. Figure 1 In this application, directional terms or qualifiers such as "axial direction," "circumferential direction," "central axis," and "radial direction" are all relative to the body 1, that is, the axial direction of the body 1, the circumferential direction of the body 1, the central axis of the body 1, and the radial direction of the body 1.

[0053] Figure 1 The structure of the core drill bit 100 according to the present invention is shown. For example... Figure 1 As shown, the core drill bit 100 mainly includes a body 1, a blade 2, cutting teeth 3, a flow channel 4, and a straightening block 5.

[0054] In this embodiment, a core-taking channel 6 is coaxially arranged within the main body 1. For example... Figure 4 As shown, during the core removal process, the core removal assembly 10 is coaxially arranged within the core removal channel 6 inside the body 1, and a flow channel 4 is formed in the annular space between the core removal assembly 10 and the body 1. The core removal 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 conventional core drills, 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 attack power.

[0056] It is easy to understand that, depending on the formation and the applicable wellbore size, the number of cutter wings 2 can be changed. It is preferable to reduce one cutter wing or add 1 to 2 cutter wings, while keeping the shape of the cutter wings unchanged.

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

[0058] Cutting teeth 3 are disposed on the toothed surface 21 of the blade 2. In this embodiment, the size of the cutting teeth 3 is greater than 13mm, that is, the diameter of the cutting teeth 3 is greater than 13mm. Specifically, in this embodiment, the cutting teeth 3 are configured as PDC composite sheets with a diameter of 16mm. By increasing the size of the cutting teeth 3, the height of the cutting teeth 3 protruding from the blade 2 can be increased, thereby improving the depth of cut.

[0059] Increasing the size of the cutting teeth 3 improves the firmness of the connection between the cutting teeth 3 and the blade wing 2. In this embodiment, a leading edge 23 is formed between the toothed surface 21 and the front side surface 22 by setting a chamfer, and multiple cutting teeth 3 are provided on the leading edge 23. The multiple cutting teeth 3 are arranged sequentially along the direction of the boundary line between the toothed surface 21 and the front side surface 22, thus being set on the leading edge 23. By setting the leading edge 23, the cutting teeth 3 can be embedded deeper into the blade wing 2, increasing the support force of the blade wing 2 on the cutting teeth 3. In addition, the leading edge 23 facilitates the exposure of the cutting teeth 3, ensuring that the formation does not come into contact with the blade wing 2 during the cutting process of the cutting teeth 3, thereby avoiding wear on the blade wing 2 and preventing the cutting teeth 3 from falling off. The leading edge 23 also ensures a smoother connection between the working surface of the cutting teeth 3 and the front side surface 22 of the blade wing 2.

[0060] In a preferred embodiment, the leading edge 23 at the junction of the toothed surface 21 and the front side surface 22 is set as 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, the cutting teeth 3 are arranged alternately with diameters of 13mm and 16mm. With this arrangement, when the core drill bit 100 rotates, the cutting teeth 3 of different sizes on the cutter blade 2 can provide a stepped cutting effect, improving the cutting efficiency of the cutting teeth 3 in formations that are difficult to penetrate.

[0062] In one embodiment, the working surface of the cutting tooth 3 can be configured as any shape, such as a plane, concave surface, or chisel shape. That is, the cutting tooth 3 can adopt an irregular tooth structure. For example... Figure 3 As shown, the cutting tooth 3 in this embodiment includes a 16mm irregular tooth 31 and a 13mm irregular tooth 32.

[0063] In one specific embodiment, the back tilt angle of the cutting tooth 3 is 9–18°, and the side rotation angle is generally set to 3–8° depending on the formation.

[0064] like Figure 3 As shown, multiple first caliber protection teeth are provided on the blade wing 2. These first caliber protection teeth are located on both sides of the cutting teeth 3, meaning they are sequentially arranged on the blade wing 2 along the arrangement direction of the cutting teeth 3. In this embodiment, the first caliber protection teeth include an inner caliber protection tooth 33 located inside the cutting teeth 3 and an outer caliber protection tooth 34 located outside the cutting teeth 3. Here, "inner" refers to the direction of the leading edge 23 of the blade wing 2 closer to the central axis, and "outer" refers to the direction of the leading edge 23 away from the central axis. The inner caliber protection tooth 33 is located on the leading edge 23 of the inclined surface 211. Both the inner caliber protection tooth 33 and the outer caliber protection tooth 34 are made of PDC composite sheet with a diameter of 13mm.

[0065] In one embodiment, the outer diameter tooth 34 is tilted downwards to provide a reverse eye function.

[0066] In a specific embodiment, such as Figure 2 and Figure 3 As shown, a trailing edge 26 is formed between the toothed surface 21 and the rear side surface 25 by setting a chamfer. By setting the trailing edge 26, the excess part of the toothed surface 21 is removed while ensuring that the blade 2 can sufficiently support the cutting teeth 3, thereby reducing the possibility of the blade 2 directly contacting the formation.

[0067] In this embodiment, the rear edge 26 at the connection between the toothed surface 21 and the rear side surface 25 is set as an unequal-sided straight chamfer.

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

[0069] In this embodiment, the anti-wear tooth 35 is a flat tooth without a bearing.

[0070] In one specific embodiment, the top of the rear side 25 is connected to the rear edge 26 by rounding the corners. That is, the rear side 25 and the rear edge 26 are connected to each other by a rounded transition. This further reduces the possibility of the blade 2 directly contacting the formation.

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

[0072] Among them, after the toothed surface 21 is projected onto the rear side 25, the inclined surface 211 is projected as an inclined straight line, with one end closer to the central axis lower than the other end. 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 and play 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 is easy to understand that impact teeth 36 can be embedded on individual blades 2. In this embodiment, the impact teeth 36 are conical PDC composite pieces. Depending on the formation, controlling the height of the impact teeth 36 protruding from the blade 2 controls the depth of the cutting teeth 3 into the formation, while simultaneously serving to hammer the formation and assist in rock breaking.

[0075] In one specific embodiment, the axial projection of the front side 22 is an arc, the center of which is located in the opposite direction of rotation of the core drill bit 100 cutting the formation. In this configuration, the front side 22 is constructed as an arc-shaped section that bulges away from the rear side 25 from the radial direction relative to the two radial sections. This configuration allows rock cuttings generated during cutting to be more easily discharged from the gaps between adjacent blades 2.

[0076] In this embodiment, the axial projection of the rear side 25 is a straight line, that is, the rear side 25 is constructed as a plane. This arrangement allows it to be distinguished from the front side 22, preventing the cutting teeth 3 from being 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 spaced along the circumferential direction on the outer surface of the body 1. The number of straightening blocks 5 is the same as the number of blade wings 2 and they correspond one-to-one. Each straightening block 5 is connected to its corresponding blade wing 2, and the straightening block 5 is connected to the lower part of the blade wing 2.

[0078] The two circumferential sides of the straightening block 5 are adapted to and connected to the front side 22 and the rear side 25 of the blade wing 2. That is, one side of the straightening block 5 is flush with the rear side 25 of the blade wing 2; the other side of the straightening block 5 is constructed as an arc surface with the same curvature as the front side 22 of the blade wing 2, and the two are smoothly connected.

[0079] In a preferred embodiment, such as Figure 3As shown, a second diameter-maintaining tooth 37 is provided on the outer surface of the straightening block 5. The outer surface 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 diameter-maintaining tooth 37 is embedded in the hole of the straightening block 5. The second diameter-maintaining tooth 37 serves to prevent wear, maintain diameter, and crush rock cuttings.

[0080] In one specific embodiment, the second diameter-maintaining tooth 37 installed on the straightening block 5 adopts a 13mm PDC composite plate arc surface tooth, protruding from the straightening block 5 and extending radially by 0.5 to 1mm, so as to play the roles of anti-wear, diameter maintenance and crushing rock chips.

[0081] The connection points between the blade wing 2 and the straightening block 5 and the main body 1 are rounded. That is, as shown... Figure 2 As shown, the front side 22 of the blade wing 2 and the body 1 are rounded to form the front root 24 of the blade wing, and the rear side 25 of the blade wing 2 and the body 1 are rounded to form the rear root 27 of the blade wing. The same applies to the straightening block 5.

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

[0083] In a specific embodiment, such as Figure 1 As shown, the main body 1 includes a cylindrical body 11 and a crown 12 coaxially disposed on the top of the cylindrical body 11. The cylindrical body 11 is generally cylindrical in shape, and the inner side of the lower end of the cylindrical body 11 is provided with a thread for connecting with the outer core cylinder (not shown in the figure). The crown 12 is coaxially disposed on the upper end of the cylindrical body 11. The top of the crown 12 is spherical.

[0084] like Figure 4 As shown, the inner diameter of the crown 12 is smaller than the inner diameter of the cylinder 11, and the flow channel 4 includes a water eye 41 disposed on the crown 12. A nozzle 42 is disposed within the water eye 41, and a limiting step 411 for restricting the movement of the nozzle 42 is disposed within the water eye 41. The limiting step 411 is located outside the nozzle 42; here, "outer side" refers to... Figure 4 The lower side of the nozzle 42. In this configuration, the nozzle 42 can enter the water eye 41 from inside the body 1, and the nozzle 42 will not detach from the water eye 41 due to the action of the limiting step 411.

[0085] like Figure 2 As shown, a boss 28 for centering the core is provided on one side of the cutter wing 2 near the central axis. The inner diameter of the boss 28 is smaller than the inner diameter of the crown 12. With this configuration, the boss 28 can limit the core column during core drilling, reduce the circumferential offset during the rotation of the core drill bit 100, and ensure that the core is not ground down. It is easy to understand that the inner surface of the boss 28 is constructed as an arc-shaped surface that matches the outer diameter of the core.

[0086] A drill bit flow channel groove 45 is formed between adjacent bosses 28, such as Figure 4 As shown, the drill bit inlet flow channel 45 is connected to the flow channel 4. In this configuration, the drilling fluid can flush the core through the drill bit inlet flow channel 45, washing away the deposits on the core and cooling the inner diameter teeth 33 at the same time.

[0087] like Figure 4 and Figure 5 As shown, centering ridges are spaced circumferentially along the inner wall of the cylinder 11 to center the core cutting assembly 10, facilitating core entry into the core sampling tool. A flow channel 43 is formed between adjacent centering ridges, the number of which is the same as the number of water holes 41. Conical grooves 44 are spaced circumferentially along the inner side of the crown 12, connecting the flow channels 43, water holes 41, and drill bit inlet flow channel 45. The conical grooves 44 serve as a transition between the flow channels 43 and the water holes 41, preventing fluid energy loss and providing better flow guidance.

[0088] The drilling fluid flows along the nozzles in the guide channel 43, the conical groove 44, and the water eye 41, as well as the channel between the adjacent cutter wings 2 between the main body 1 and the wellbore.

[0089] When the core bit 100 is performing core drilling, the drilling fluid flows along two flow channels 4, namely the flow channel 4 formed by the guide groove 43, the conical groove 44, the nozzle in the water eye 41, and the channel between the adjacent cutter wings 2 between the body 1 and the wellbore, and the flow channel 4 formed by the guide groove 43, the conical groove 44, the drill bit inlet flow channel 45, and the channel between the adjacent cutter wings 2 between the body 1 and the wellbore.

[0090] In one specific embodiment, the nozzle 42 is installed inside the water inlet 41 by means of embedding or threaded connection. To prevent leakage of the steel body, the nozzle 42 is made of hard alloy material, with an arc-shaped flow surface design, and the size of the outlet can be changed as needed, generally 12-14mm. The tilt angle of the nozzle 42 (water inlet 41) is set to 8-9°.

[0091] In one 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 for wear prevention and chip removal.

[0092] In the description of this invention, 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0093] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0094] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions 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 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 on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A core drilling bit, characterized in that, include: The body (1) has a core-taking channel (6) coaxially arranged inside the body (1); Blade wings (2) are arranged circumferentially on the body (1); A straightening block (5) is arranged circumferentially on the outer side of the body (1), and the straightening block (5) is connected to the blade (2); The flow channels (4) are arranged circumferentially on the body (1), and the flow channels (4) are located between adjacent blades (2); The blade (2) includes a toothed surface (21) and a front side (22). A front edge (23) is formed between the toothed surface (21) and the front side (22) by setting a chamfer. Multiple cutting teeth (3) are provided on the front edge (23). The dimensions of the cutting teeth (3) are not all the same, and at least one of the cutting teeth (3) has a size greater than 13mm.

2. The core drill bit according to claim 1, characterized in that, The toothed surface (21) includes an inclined surface (211), which is located at the end of the blade (2) near the central axis of the body (1) and serves to straighten it.

3. The core drill bit according to claim 2, characterized in that, The toothed surface (21) includes 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 (22) is an arc, and the center of the arc is located in the opposite direction of the rotation of the core drill bit cutting the formation.

5. The core drill bit according to claim 1, characterized in that, The blade (2) includes a rear side (25), and a rear edge (26) is formed between the toothed surface (21) and the rear side (25) by setting a chamfer. Anti-wear teeth (35) are provided at the end of the rear edge (26) near the central axis. The top of the rear side (25) is connected to the rear edge (26) by setting a rounded corner.

6. The core drill bit according to claim 1, characterized in that, The main body (1) includes a cylindrical body (11) and a crown (12) coaxially disposed on the top of the cylindrical body (11). The inner diameter of the crown (12) is smaller than the inner diameter of the cylindrical body (11). The flow channel (4) includes a water eye (41) disposed on the crown (12). A nozzle (42) is disposed in the water eye (41). A limiting step (411) for restricting the movement of the nozzle (42) is disposed 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 rock core is provided on one side of the blade (2) near the central axis. The inner diameter of the boss (28) is smaller than the inner diameter of the crown (12). A drill bit flow channel groove (45) is formed between adjacent bosses (28). The drill bit flow channel groove (45) is connected to the flow channel (4).

8. The core drill bit according to claim 7, characterized in that, The inner wall of the cylinder (11) is provided with circumferentially spaced straightening ridges for straightening the core cutting assembly (10), and a guide groove (43) is formed between adjacent straightening ridges. A conical groove (44) is provided circumferentially spaced on the inner side of the crown (12), and the conical groove (44) connects the guide groove (43), the water eye (41) and the drill bit flow channel groove (45).

9. The core drill bit according to claim 1, characterized in that, Multiple first diameter-maintaining teeth are provided on the blade (2). The first diameter-maintaining teeth are located on both sides of the setting direction of the cutting teeth (3). The first diameter-maintaining teeth are PDC composite sheets.

10. The core drill bit according to claim 9, characterized in that, The first diameter protection tooth includes an inner diameter protection tooth (33) disposed inside the cutting tooth (3) and an outer diameter protection tooth (34) disposed outside the cutting tooth (3). The outer diameter protection tooth (34) has a downward tilt angle and provides a reverse eye function.

11. The core drill bit according to claim 1, characterized in that, A second diameter-protecting tooth (37) is provided on the outer surface of the straightening block (5). The second diameter-protecting tooth (37) protrudes from the straightening block (5) by 0.5 to 1 mm. The second diameter-protecting tooth is a PDC composite sheet.

12. The core drill bit according to claim 6, characterized in that, The blade (2) and crown (12) are coated with wear-resistant material.

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