Cutting tooth and method of designing same, pdc bit

Abstract

The application discloses a cutting tooth and a design method thereof and a PDC drill bit, relates to the technical field of drilling bits for oil and gas and geological exploration, and discloses the cutting tooth, which comprises a base with a first end face and a second end face; and a cutting piece fixedly arranged on the first end face of the base, wherein the cutting piece comprises a first cutting structure in the shape of a column, the first cutting structure has a third end face and a fourth end face, and the fourth end face is fixed with the first end face; and a second cutting structure located in the third end face, the second cutting structure is in the shape of a column, the radial cross section of the second cutting structure is smaller than that of the first cutting structure, the upper end face of the second cutting structure has a ridge line in the shape of a straight line, the first preset included angle θ is formed between the ridge line and the first end face, and the height of the two side areas of the ridge line of the upper end face of the second cutting structure gradually decreases in the direction away from the ridge line. The application can solve the problem that the cutting tooth is prone to wear and damage in soft and hard interbedded layers and strong abrasive strata.

Description

Technical Field

[0001] This invention relates to the field of drilling bits for oil and gas and geological exploration, and particularly to a cutting tooth and its design method, and a PDC drill bit. Background Technology

[0002] Currently, PDC (Polycrystalline Diamond Compact Bit) drill bits have become a major rock-breaking drill bit in the oil and gas drilling field, with over 90% of the drilling footage in oil and gas wells worldwide being completed using PDC drill bits. The cutting teeth of PDC drill bits are made of polycrystalline diamond composite plates, commonly cylindrical in shape, formed by high-temperature and high-pressure sintering of a polycrystalline diamond layer and a cemented carbide substrate. Cylindrical cutting teeth break rock through shearing during operation, offering advantages such as high drilling speed and high footage in soft to medium-hard formations. However, in formations with high hardness, strong abrasiveness, and tough interlayers, the commonly used cylindrical cutting teeth struggle to penetrate the formation, resulting in low rock-breaking efficiency, severe wear, and short service life. This leads to low mechanical drilling speed and long drilling cycles, undoubtedly increasing drilling costs.

[0003] Therefore, many researchers have made significant improvements to the shape of commonly used cylindrical cutting teeth, developing a variety of irregularly shaped cutting teeth. These improvements significantly enhance the impact resistance and wear resistance of cylindrical cutting teeth, broadening the application range of polycrystalline diamond composite sheets in hard rock formations. However, when drilling into interlayers of soft and hard materials and highly abrasive formations, existing irregularly shaped cutting teeth still exhibit varying degrees of wear and breakage, resulting in low drilling efficiency and an inability to achieve effective improvements. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a cutting tooth and its design method, and a PDC drill bit, which can solve the problem of easy wear and damage of cutting teeth in soft and hard interlayers and highly abrasive formations.

[0005] The specific technical solution of this invention is as follows:

[0006] A cutting tooth, the cutting tooth comprising:

[0007] A base having corresponding first and second end faces;

[0008] A cutting element fixedly disposed on the first end face of the substrate, the cutting element being made of polycrystalline diamond, the cutting element comprising: a first cutting structure in the shape of a column, the first cutting structure having a third end face and a fourth end face, the fourth end face being fixed to the first end face; and a second cutting structure located within the third end face, the second cutting structure being columnar, the radial cross-section of the second cutting structure being smaller than the radial cross-section of the first cutting structure, the upper end face of the second cutting structure having a straight ridge line, the ridge line having a first preset angle θ with the first end face, and the height of the two sides of the ridge line on the upper end face of the second cutting structure gradually decreasing along the direction away from the ridge line.

[0009] Preferably, the substrate is made of cemented carbide, and the cutting element is fixedly disposed on the first end face of the substrate by sintering. The cross-section of the substrate in the radial direction is exactly the same in shape and size as the cross-section of the first cutting structure in the radial direction. The cross-section of the substrate in the radial direction and the cross-section of the first cutting structure in the radial direction are circular or approximately circular or elliptical or approximately elliptical.

[0010] Preferably, the center of the second cutting structure is the same as the center of the first cutting structure, the ridge line passes through the center of the second cutting structure, and the two sides of the ridge line on the upper surface of the second cutting structure are symmetrical.

[0011] Preferably, the cutting angle α of the cutting tooth is such that the first preset included angle θ is greater than or equal to 0 degrees and α+θ is less than 90 degrees.

[0012] Preferably, the structural parameters of the cutting teeth satisfy the following relationship:

[0013] Δh=Rcosα-(L+r)·sin(α+θ),

[0014] Wherein, α represents the cutting angle of the cutting tooth, R represents the radius of the first cutting structure, r represents the radius of the second cutting structure, L represents the distance from the center of the bottom surface of the second cutting structure to the ridge line, and Δh represents the tooth height difference, that is, the distance from the end point B of the lower end of the ridge line to the edge D of the third end face of the first cutting structure in the Y-axis direction.

[0015] Preferably, the radius R of the first cutting structure is equal to 8.0 mm and the radius r of the second cutting structure is equal to 6.5 mm; or, the radius R of the first cutting structure is equal to 9.5 mm and the radius r of the second cutting structure is equal to 8 mm; or, the radius R of the first cutting structure is equal to 9.5 mm and the radius r of the second cutting structure is equal to 6.5 mm.

[0016] Preferably, the cutting angle α of the cutting teeth is between 5 degrees and 30 degrees.

[0017] Preferably, the radius R of the first cutting structure is equal to 8.0 mm, the radius r of the second cutting structure is equal to 6.5 mm, the cutting angle α of the cutting tooth is equal to 15 degrees, the distance L from the center of the bottom surface of the second cutting structure to the ridge line is equal to 1.5 mm, the first preset included angle θ is equal to 35 degrees, and the tooth height difference Δh is equal to 1.6 mm.

[0018] A PDC drill bit, the PDC drill bit comprising cutting teeth as described in any of the above descriptions.

[0019] A method for designing cutting teeth as described in any of the above descriptions, the method comprising the following steps:

[0020] Select the radius R of the first cutting structure and the radius r of the second cutting structure;

[0021] Obtain the cutting angle α formed by the cutting teeth mounted on the PDC drill bit.

[0022] Determine the distance L from the center of the bottom surface of the second cutting structure to the ridge line and the first preset angle θ between the ridge line and the first end face, such that the first preset angle θ is greater than or equal to 0 degrees and α+θ is less than 90 degrees;

[0023] The tooth height difference Δh is determined based on the radius R of the first cutting structure, the radius r of the second cutting structure, the cutting angle α, the distance L from the center of the bottom surface of the second cutting structure to the ridge line, and the first preset angle θ between the ridge line and the first end face. The specific calculation formula is as follows:

[0024] Δh=Rcosα-(L+r)·sin(α+θ).

[0025] The technical solution of the present invention has the following significant beneficial effects:

[0026] 1. The second cutting structure of the cutting tooth in this application has a concentrated load at the ridge line, which forms a stress concentration zone in the rock in front of it, making the rock more prone to shear-tensile failure, improving the ability of the cutting tooth to penetrate the formation, and improving the rock breaking efficiency of the drill bit.

[0027] 2. The cutting teeth of this application utilize the lower end region of the ridge line of the first cutting structure to the edge region of the third end face of the second cutting structure for cutting, thereby realizing the joint cutting and rock breaking of the first and second cutting structures along the same track, overcoming the shortcomings of the single first cutting structure having a small rock breaking volume and insufficient well bottom coverage.

[0028] 3. This application utilizes the characteristics of the second cutting structure with ridges, which is highly aggressive and less prone to impact damage, to pre-break the rock at the bottom of the well, release formation stress, and make it easier for the subsequent first cutting structure to cut the rock, which can significantly improve the rock breaking efficiency. In addition, the second cutting structure with ridges can limit the depth of the first cutting structure into the formation, reduce the "stick-slip effect" of the drill bit and impact damage, and improve the service life of the drill bit.

[0029] Specific embodiments of the invention are disclosed in detail below with reference to the description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description

[0030] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0031] Figure 1 This is a three-dimensional structural diagram of the cutting teeth in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram illustrating the design process of the cutting component for the cutting teeth in an embodiment of the present invention;

[0033] Figure 3 This is a front view of the cutting teeth in an embodiment of the present invention;

[0034] Figure 4 This is a three-dimensional structural diagram of the cutting component of the cutting teeth in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure of the PDC drill bit in an embodiment of the present invention;

[0036] Figure 6 This is a stress distribution diagram of the cutting teeth during the rock-breaking process in an embodiment of the present invention;

[0037] Figure 7 This is a stress distribution diagram of conventional cylindrical cutting teeth in the rock-breaking process in the prior art;

[0038] Figure 8This is a comparison diagram showing the change of cutting force over time between the cutting teeth in this embodiment of the invention and conventional cylindrical cutting teeth in the prior art during rock breaking.

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

[0040] 1. Base; 11. First end face; 12. Second end face; 2. Cutting part; 21. First cutting structure; 211. Third end face; 212. Fourth end face; 22. Second cutting structure; 221. Ridge; 100. Cutting tooth. Detailed Implementation

[0041] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "connected" should be interpreted broadly, for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] To address the problem of easy wear and damage to cutting teeth in soft-hard interlayers and highly abrasive formations, this application proposes a cutting tooth. Figure 1 This is a three-dimensional structural diagram of the cutting teeth in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the design process of the cutting component 2 for the cutting teeth in an embodiment of the present invention. Figure 3 This is a front view of the cutting teeth in an embodiment of the present invention. Figure 4This is a three-dimensional structural diagram of the cutting component 2 of the cutting teeth in an embodiment of the present invention, as shown below. Figures 1 to 4 As shown, the cutting tooth may include a base 1 and a cutting element 2. The base 1 may have corresponding first end face 11 and second end face 12, and the base 1 can be used to support the cutting element 2. The cutting element 2 is fixedly disposed on the first end face 11 of the base 1.

[0044] like Figures 1 to 4 As shown, the substrate 1 can be made of cemented carbide, which can save on the amount of polycrystalline diamond material used. Of course, it can also be made of polycrystalline diamond.

[0045] The cutting element 2 is made of polycrystalline diamond. When the substrate 1 is made of cemented carbide, the cutting element 2 is fixedly disposed on the first end face 11 of the substrate 1 by sintering.

[0046] like Figure 1 As shown, the cutting part 2 may include: a columnar first cutting structure 21, the first cutting structure 21 having a third end face 211 and a fourth end face 212, the fourth end face 212 being fixed to the first end face 11; and a second cutting structure 22 located within the third end face 211, the second cutting structure 22 being columnar, the radial cross-section of the second cutting structure 22 being smaller than the radial cross-section of the first cutting structure 21. The third end face 211 is a plane, and the fourth end face 212, when fitted with the first end face 11, can be sintered. Furthermore, the second cutting structure 22 is located in the middle region of the third end face 211 of the first cutting structure 21, and the sidewalls of the second cutting structure 22 are at a certain distance from the edge of the third end face 211 of the first cutting structure 21.

[0047] like Figure 1 and Figure 3 As shown, the cross-section of the base 1 in the radial direction is exactly the same in shape and size as the cross-section of the first cutting structure 21 in the radial direction. In this way, the edges of the first cutting structure 21 are all supported by the base 1, which can effectively prevent the edges of the third end face 211 of the first cutting structure 21 of the cutting teeth from wearing or cracking during rock breaking.

[0048] like Figure 1 and Figure 4As shown, the upper end face of the second cutting structure 22 has a straight ridge 221, which divides the upper end face of the second cutting structure 22 into left and right side regions. The length of the ridge 221 spans the entire upper end face of the second cutting structure 22. The ridge 221 can be parallel to the first end face 11 of the base 1, that is, the first preset angle θ between the ridge 221 and the first end face 11 of the base 1 is equal to 0 degrees. The ridge 221 can also have a first preset angle θ with the first end face 11 of the base 1, where the first preset angle θ is greater than 0 degrees. The two side regions of the ridge 221 on the upper end face of the second cutting structure 22 gradually decrease in height along the direction away from the ridge 221. The two side regions of the ridge 221 on the upper end face of the second cutting structure 22 can be planar, and the two side regions of the planar ridge 221 have a certain angle of inclination with the third end face 211 of the first cutting structure 21.

[0049] like Figures 1 to 4 As shown, the cross-section of the base 1 in the radial direction is circular, approximately circular, elliptical, or approximately elliptical in shape, similar to the cross-section of the first cutting structure 21 in the radial direction. The cross-section of the second cutting structure 22 in the radial direction can have the same shape as the cross-section of the first cutting structure 21 in the radial direction. Furthermore, the center of the second cutting structure 22 is the same as the center of the first cutting structure 21, the ridge line 221 passes through the center of the second cutting structure 22, and the two sides of the ridge line 221 on the upper end face of the second cutting structure 22 are symmetrical.

[0050] like Figure 2 As shown, when the cutting teeth cut the formation, they move along the X-axis, from the lower end region of the ridge 221 of the first cutting structure 21 to the edge region of the third end face 211 of the second cutting structure 22, cutting the formation. The cutting angle of the cutting teeth is α, specifically the angle between the third end face 211 of the second cutting structure 22 and the Y-axis. The sum of the cutting angle α and the first preset angle θ between the ridge 221 and the first end face 11 is less than 90 degrees, and the first preset angle θ is greater than or equal to 0 degrees.

[0051] To achieve the highest rock-breaking efficiency and service life, the structural parameters of the cutting teeth need to satisfy the following relationship:

[0052] Δh=Rcosα-(L+r)·sin(α+θ),

[0053] Wherein, α represents the cutting angle of the cutting tooth, R represents the radius of the first cutting structure 21, r represents the radius of the second cutting structure 22, L represents the distance from the center o of the bottom surface of the second cutting structure 22 to the ridge line 221A, and Δh represents the tooth height difference, that is, the distance from the end point B of the lower end of the ridge line 221 to the edge D of the third end face 211 of the first cutting structure 21 in the Y-axis direction.

[0054] In the above structure, the cross-section of the base 1 in the radial direction is circular, as is the cross-section of the first cutting structure 21 in the radial direction, and the cross-section of the second cutting structure 22 in the radial direction is also circular. The center of the second cutting structure 22 is the same as the center of the first cutting structure 21, and the ridge line 221 passes through the center of the second cutting structure 22.

[0055] In the above structure, several suitable combinations of the radii of the first cutting structure 21 and the second cutting structure 22 can be as follows: the radius R of the first cutting structure 21 is equal to 8.0 mm, and the radius r of the second cutting structure 22 is equal to 6.5 mm; or, the radius R of the first cutting structure 21 is equal to 9.5 mm, and the radius r of the second cutting structure 22 is equal to 8 mm; or, the radius R of the first cutting structure 21 is equal to 9.5 mm, and the radius r of the second cutting structure 22 is equal to 6.5 mm.

[0056] In the above structure, the cutting angle α of the cutting teeth is further controlled between 5 degrees and 30 degrees.

[0057] In one specific embodiment, the radius R of the first cutting structure 21 is equal to 8.0 mm, the radius r of the second cutting structure 22 is equal to 6.5 mm, the cutting angle α of the cutting tooth is equal to 15 degrees, the distance L from the center of the bottom surface of the second cutting structure 22 to the ridge line 221 is equal to 1.5 mm, the first preset included angle θ is equal to 35 degrees, and the tooth height difference Δh is equal to 1.6 mm.

[0058] The second cutting structure 22 of the cutting teeth in this application has a concentrated load at the ridge 221, forming a stress concentration zone inside the rock in front of it. This makes the rock more susceptible to shear-tensile failure, improving the cutting teeth's ability to penetrate the formation and increasing the drill bit's rock-breaking efficiency. The cutting teeth in this application utilize the lower end region of the ridge 221 of the first cutting structure 21 to the edge region of the third end face 211 of the second cutting structure 22 for cutting, thereby achieving joint cutting and rock breaking by the first and second cutting structures along the same track. This overcomes the shortcomings of the single first cutting structure 21, which has a small single-pass rock-breaking volume and insufficient bottom hole coverage. This application utilizes the strong attack power and low impact damage of the second cutting structure 22 with the ridge 221 to pre-break the bottom hole rock, releasing formation stress and making it easier for the subsequent first cutting structure 21 to cut the rock, significantly improving rock breaking efficiency. Furthermore, the second cutting structure 22 with the ridge 221 can limit the depth of penetration of the first cutting structure 21 into the formation, reducing the drill bit's "stick-slip effect" and impact damage, and increasing the drill bit's service life.

[0059] Figure 6 This is an experimental diagram showing the cutting force of the cutting teeth during rock breaking in an embodiment of the present invention. Figure 7 Experimental diagrams of cutting forces for conventional cylindrical cutting teeth in existing technologies, such as... Figure 6 and Figure 7 As shown, under the same cutting conditions, cutting is performed from the lower end region of the ridge 221 of the first cutting structure 21 to the edge region of the third end face 211 of the second cutting structure 22. The maximum Mises stress generated inside the rock by the cutting teeth in this application is 468.7 MPa, while the maximum Mises stress generated inside the rock by conventional cylindrical cutting teeth in the prior art is 367.5 MPa. Obviously, the cutting teeth in this application can generate greater stress inside the rock, and stress concentration is more likely to occur at the stepped tooth tip, which is more conducive to rock breaking and improves rock breaking efficiency.

[0060] Figure 8 This is a comparison diagram showing the change of cutting force over time between the cutting teeth in this invention and conventional cylindrical cutting teeth in the prior art during rock breaking. Figure 8As shown, the average cutting force of the cutting teeth in this application during rock breaking is 1882.05 N, with a standard deviation of 132.94. In contrast, the average cutting force of conventional cylindrical cutting teeth in the prior art during rock breaking is 1840.92 N, with a standard deviation of 482.98. Although the average cutting forces of the two types of cutting teeth during rock breaking are relatively close, the standard deviation of the cutting force of the cutting teeth in this application is 72.48% smaller than that of conventional cylindrical cutting teeth in the prior art. This indicates that the cutting teeth in this application exhibit less fluctuation in cutting force during rock breaking, which helps reduce torque fluctuations and harmful vibrations in the PDC drill bit, thereby improving the working stability of the PDC drill bit and extending its service life.

[0061] This application also proposes a PDC drill bit. Figure 5 This is a schematic diagram of the structure of the PDC drill bit in an embodiment of the present invention, as shown below. Figure 5 As shown, the PDC drill bit may include cutting teeth 100 as described above. The cutting teeth 100 may be distributed on the nose or shoulder of the PDC drill bit. The cutting teeth 100 installed on the nose or shoulder utilize the excellent rock-breaking performance of the second cutting structure 22 with ridges 221 to first cut the rock at the bottom of the well, breaking the original mechanical state of the rock and making it easier to break, thus improving the drill bit's rock-breaking efficiency. Similarly, the second cutting structure 22 with ridges 221 can limit the depth to which the first cutting structure 21 penetrates the formation, reducing the drill bit's "stick-slip effect" and impact damage, and improving the drill bit's service life. The cutting teeth integrate the rock-breaking advantages of the first cutting structure 21 and the second cutting structure 22. At the same time, the integrated design effectively avoids the double-row tooth design of the PDC drill bit, reduces the thickness of the PDC drill bit's blades, concentrates energy on the sharp cutting part 2, and achieves high drilling speed with low drilling pressure. In addition, the blade structure can be more open, and the chip removal groove structure can be wider, which can form a smooth hydraulic flow channel to adapt to higher mechanical drilling speeds with stronger cuttings removal capabilities.

[0062] This application also proposes a design method for the above-mentioned cutting teeth, the design method comprising the following steps:

[0063] Select the radius R of the first cutting structure 21 and the radius r of the second cutting structure 22;

[0064] Obtain the cutting angle α formed by the cutting teeth mounted on the PDC drill bit.

[0065] Determine the distance L from the center of the bottom surface of the second cutting structure 22 to the ridge line 221 and the first preset angle θ between the ridge line 221 and the first end face 11, such that the first preset angle θ is greater than or equal to 0 degrees and α+θ is less than 90 degrees.

[0066] The tooth height difference Δh is determined based on the radius R of the first cutting structure 21, the radius r of the second cutting structure 22, the cutting angle α, the distance L from the center of the bottom surface of the second cutting structure 22 to the ridge line 221, and the first preset angle θ between the ridge line 221 and the first end face 11. The specific calculation formula is as follows:

[0067] Δh=Rcosα-(L+r)·sin(α+θ).

[0068] The above method allows for the rapid design of the cutting tooth structure parameters in this application to be tailored to specific lithologies of the formation, so that the cutting tooth can achieve the highest rock-breaking efficiency and service life.

[0069] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified element, component, part, or step, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute “may” include is optional. Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The disclosure of “a” or “an” used to describe an element, component, part, or step does not imply exclusion of other elements, components, parts, or steps.

[0070] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A cutting tooth, characterized in that, The cutting teeth include: A base having corresponding first and second end faces; A cutting element fixedly disposed on the first end face of the substrate, the cutting element being made of polycrystalline diamond, the cutting element comprising: a columnar first cutting structure having a third end face and a fourth end face, the fourth end face being fixed to the first end face; a second cutting structure located within the third end face, the second cutting structure being columnar, the radial cross-section of the second cutting structure being smaller than the radial cross-section of the first cutting structure, the upper end face of the second cutting structure having a straight ridge line, the ridge line having a first preset angle θ with the first end face, the two sides of the ridge line on the upper end face of the second cutting structure gradually decreasing in height along the direction away from the ridge line; when the cutting teeth are cutting, they utilize the lower end area of ​​the ridge line of the first cutting structure to the edge area of ​​the third end face of the second cutting structure for cutting, thereby achieving joint cutting and rock breaking by the first cutting structure and the second cutting structure along the same track; The structural parameters of the cutting teeth satisfy the following relationship: △h=Rcosα-(L+r) sin(α+θ), Wherein, α represents the cutting angle of the cutting tooth, R represents the radius of the first cutting structure, r represents the radius of the second cutting structure, L represents the distance from the center of the bottom surface of the second cutting structure to the ridge line, and Δh represents the tooth height difference, that is, the distance from the end point B of the lower end of the ridge line to the edge D of the third end face of the first cutting structure in the Y-axis direction; The cutting angle α of the cutting teeth is between 5 degrees and 30 degrees, the first preset included angle θ is greater than or equal to 0 degrees, and α+θ is less than 90 degrees.

2. The cutting tooth according to claim 1, characterized in that, The substrate is made of cemented carbide, and the cutting element is fixedly disposed on the first end face of the substrate by sintering. The cross-section of the substrate in the radial direction is exactly the same in shape and size as the cross-section of the first cutting structure in the radial direction. The cross-section of the substrate in the radial direction and the cross-section of the first cutting structure in the radial direction are circular, approximately circular, elliptical, or approximately elliptical.

3. The cutting tooth according to claim 2, characterized in that, The center of the second cutting structure is the same as the center of the first cutting structure, the ridge line passes through the center of the second cutting structure, and the two sides of the ridge line on the upper surface of the second cutting structure are symmetrical.

4. The cutting tooth according to claim 1, characterized in that, The radius R of the first cutting structure is equal to 8.0 mm, and the radius r of the second cutting structure is equal to 6.5 mm; or, the radius R of the first cutting structure is equal to 9.5 mm, and the radius r of the second cutting structure is equal to 8 mm; or, the radius R of the first cutting structure is equal to 9.5 mm, and the radius r of the second cutting structure is equal to 6.5 mm.

5. The cutting tooth according to claim 1, characterized in that, The radius R of the first cutting structure is equal to 8.0 mm, the radius r of the second cutting structure is equal to 6.5 mm, the cutting angle α of the cutting tooth is equal to 15 degrees, the distance L from the center of the bottom surface of the second cutting structure to the ridge line is equal to 1.5 mm, the first preset included angle θ is equal to 35 degrees, and the tooth height difference Δh is equal to 1.6 mm.

6. A PDC drill bit, characterized in that, The PDC drill bit includes cutting teeth as described in any one of claims 1 to 5.

7. A method for designing cutting teeth as described in any one of claims 1 to 5, characterized in that, The design method includes the following steps: Select the radius R of the first cutting structure and the radius r of the second cutting structure; Obtain the cutting angle α formed by the cutting teeth mounted on the PDC drill bit. Determine the distance L from the center of the bottom surface of the second cutting structure to the ridge line and the first preset angle θ between the ridge line and the first end face, such that the first preset angle θ is greater than or equal to 0 degrees and α+θ is less than 90 degrees; The tooth height difference Δh is determined based on the radius R of the first cutting structure, the radius r of the second cutting structure, the cutting angle α, the distance L from the center of the bottom surface of the second cutting structure to the ridge line, and the first preset angle θ between the ridge line and the first end face. The specific calculation formula is as follows: △h=Rcosα-(L+r) sin(α+θ).

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