Down-the-hole drill bit

Abstract

The utility model discloses a down-the-hole drill bit, and relates to the technical field of down-the-hole drilling tools, the down-the-hole drill bit comprises a drill bit body, a plurality of rock debris grooves, diamond plane composite teeth, two air holes and two debris discharging grooves, the head end of the drill bit body is provided with a large plane, and the periphery of the large plane is provided with an annular inclined plane; the rock debris grooves are evenly distributed in the peripheral surface of the drill bit body. The diamond plane composite teeth comprise a plurality of side teeth which are uniformly distributed on the annular inclined plane and double rows of inner teeth which are reversely arranged on the large plane; each row of inner teeth comprises a central tooth and an outer edge tooth which are horizontally arranged on the same radius axis, and a cutting auxiliary tooth which is horizontally arranged on one side of the outer edge tooth; the two air holes and the two chip grooves are symmetrically formed in the large plane, one ends of the two chip grooves are correspondingly communicated with the two air holes respectively, and the other ends of the two chip grooves are correspondingly communicated with any two of the multiple rock debris grooves respectively. According to the down-the-hole drill bit, full-coverage cutting of a drill bit contact rock layer surface is achieved, the impact rock crushing efficiency of a soft rock stratum is greatly improved, and the drilling speed is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of down-the-hole drilling tools for geological exploration and mineral engineering, and particularly relates to a horizontal diamond flat composite tooth down-the-hole bit that can meet the requirements of efficient impact rock breaking in soft rock formations. Background Technique

[0002] Down-the-hole bits are often used in combination with percussion drilling tools and are mainly applied to mineral resource exploration, such as underground mines, quarries, and water well projects.

[0003] The diamond composite teeth on the crown of traditional down-the-hole bits often use diamond "ball" type composite teeth or cemented carbide teeth as cutting teeth, and rely on the impact rotation of the percussion drilling tool as the main rock breaking method, becoming an important equipment for drilling in hard strata during mine resource exploration.

[0004] However, the traditional diamond "ball" type composite teeth are all used for hard rock, and the rock breaking method is mainly impact. Since the "ball" type teeth themselves do not have sharp cutting edges, impact in soft strata may cause drilling jamming. If the drainage is not smooth, it will lead to problems such as poor drilling efficiency and the inability to grind out the cutting edge of the diamond layer. In addition, the impact effect of traditional down-the-hole bits to a certain extent ignores stability and rock cutting efficiency, resulting in problems such as easy generation of impact cracks and large vibration deflection of conventional diamond composite teeth, which not only affect the drilling efficiency, but also the bit life and borehole quality cannot be guaranteed.

[0005] Finally, down-the-hole bits are widely used in hard strata in mineral development, but there is little research on down-the-hole bits suitable for rock breaking in soft strata. Content of the Utility Model

[0006] In view of this, the main purpose of the utility model is to propose a down-the-hole bit to solve the above problems.

[0007] To achieve the above purpose, the utility model proposes a down-the-hole bit, including:

[0008] A bit body, the head end of the bit body is provided with a large plane, and a circular inclined plane is arranged on the outer periphery of the large plane;

[0009] A number of chip grooves are evenly arranged on the outer peripheral surface of the bit body;

[0010] Diamond flat composite teeth, including a number of edge teeth evenly arranged on the circular inclined plane and two rows of inner teeth arranged in opposite directions on the large plane; each row of the inner teeth includes a center tooth and an outer edge tooth lying horizontally on the same radius axis and a cutting auxiliary tooth lying horizontally on one side of the outer edge tooth;

[0011] Two air holes are symmetrically arranged on the large plane;

[0012] Two chip removal grooves are symmetrically arranged on the large plane. One end of each of the two chip removal grooves is correspondingly connected to one of the two air holes, and the other end of each of the two chip removal grooves is correspondingly connected to any two of the several chip grooves.

[0013] Optionally, the cutting edges of adjacent center teeth, outer edge teeth, and cutting auxiliary teeth in the same row have the same direction. The center teeth, outer edge teeth, and cutting auxiliary teeth all include a diamond wear-resistant layer and a cemented carbide layer. The tooth pitch of the center teeth does not exceed 5 mm, and the tooth pitch of the outer edge teeth is 3 mm.

[0014] Optionally, the distribution circle diameter of the center teeth is smaller than the distribution circle diameter of the outer edge teeth, and the outer edge teeth and the cutting auxiliary teeth are on the same distribution circle. The included angle between adjacent outer edge teeth and cutting auxiliary teeth in the same row is 60°.

[0015] Optionally, the air holes are symmetrically distributed at the center teeth, and the openings of the chip grooves on the side close to the annular inclined surface are evenly distributed between the side teeth.

[0016] Optionally, the center line of the chip removal groove passes through the center point of the large plane.

[0017] Optionally, the angle between the large plane and the annular inclined surface is 35° - 45°.

[0018] Optionally, the included angle between the chip groove and the axis of the large plane is 6 - 10°.

[0019] Optionally, the chip removal groove is an arc-shaped long groove with a cross-sectional radius of 7.5 mm.

[0020] Optionally, the diameter range of the drill bit body is 95 mm - 465 mm.

[0021] Optionally, the number of both the chip grooves and the side teeth is 6. The side teeth are evenly distributed on the outer circular inclined surface with a diameter of 95 mm, the number of the inner teeth is 6, and the center teeth are evenly distributed on the top large plane with a diameter of 70 mm.

[0022] Compared with the prior art, the present utility model has the following technical effects:

[0023] 1. In this application, the down-the-hole bit is composed of a bit body, several chip grooves, diamond flat composite teeth, two air holes, and a chip discharge groove. A large flat surface is provided at the top of the crown of the bit body. An annular inclined surface is provided on the outer peripheral edge of the large flat surface. The annular inclined surface can evenly distribute the edge teeth of several "horizontal" diamond flat composite teeth according to the bit diameter. Several chip grooves are clamped at intervals between adjacent edge teeth. The large flat surface at the top of the crown of the bit body is provided with inner teeth of double-row reverse "horizontal" diamond flat composite teeth based on the center line, that is, the center teeth and outer edge teeth located on the same radius axis and the cutting auxiliary teeth located on one side of the outer edge teeth. The inner teeth arranged in double rows in the reverse direction are arranged in opposite pairs. During the drilling operation, the edge teeth and inner teeth are carried by the bit body and the impact energy is transmitted. The edge teeth and inner teeth are used to break rocks. The large flat surface at the top first contacts the soft formation. The "horizontal" inner teeth on the large flat surface adopt a tooth arrangement method with a large elevation angle and a certain side inclination angle. It first makes point contact with the soft formation. Coupled with the impact rotation, due to the large elevation amplitude of the diamond chamfer layer, the unit contact area with the soft rock formation is smaller than that of the conventional "ball" type tooth spherical surface, the pressure is greater, and the effect of penetrating the formation is better, improving the drilling speed; when the down-the-hole bit rotates at the bottom of the well, the edge teeth of the annular inclined surface and the inner teeth of the top large flat surface under the impact force cooperate with each other. During the drilling in the soft formation, under the action of the impact force, the rock is vibrated and broken, which is conducive to the inner teeth of the top large flat surface pressing into the soft rock formation for plowing; due to the relatively large friction received by the annular inclined surface, it mainly acts on the formation within the range not affected by the impact vibration, and the main movement trajectory is the rotation after the impact. Since there is a certain inclination angle between the annular inclined surface and the top large flat surface, as the annular inclined surface with an inclination angle rotates, under the action of the flow channels of the chip grooves arranged at intervals and the flushing fluid, the chips are driven above the bit body, so that the debris does not affect the normal drilling, improving the drilling efficiency.

[0024] 2. The inner teeth of the crown adopt a "horizontal" design of high-performance diamond composite teeth with a large elevation angle and an inclined inclination angle, similar to the tooth arrangement form of a PDC bit, combining the sharp cutting effect of the composite sheet and the impact resistance of the cutting teeth of the down-the-hole bit, greatly increasing the impact rock-breaking efficiency of the soft rock formation and improving the drilling speed; the arrangement of the double-row reverse "horizontal" inner teeth at the center of the top large flat surface can achieve full-coverage cutting and efficient rock-breaking of the bit contacting the rock formation surface, further improving the rock-breaking efficiency of the bit in the soft formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0026] Figure 1 This is a schematic structural view of a down-the-hole bit in an embodiment of the present utility model;

[0027] Figure 2 This is a top-down structural view of a down-the-hole bit in an embodiment of the present utility model.

[0028] Explanation of the reference numerals in the attached drawings:

[0029] 1 - Bit body;

[0030] 11 - Large plane; 12 - Annular inclined plane;

[0031] 2 - Chip groove;

[0032] 3 - Diamond flat composite tooth;

[0033] 31 - Edge tooth; 32 - Inner tooth; 321 - Center tooth; 322 - Outer edge tooth; 323 - Cutting auxiliary tooth;

[0034] 4 - Air hole;

[0035] 5 - Chip removal groove. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

[0037] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, then such directional indications are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the attached drawings). If this specific posture changes, then such directional indications will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present utility model, then such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one such feature.

[0039] In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0040] Please refer to Figure 1-2 As shown, an embodiment of the present utility model provides a down-the-hole bit, which includes a bit body 1, a plurality of chip grooves 2, diamond flat composite teeth 3, two air holes 4 and two chip removal grooves 5, wherein:

[0041] The head end of the bit body 1 is provided with a large plane 11, and the outer periphery of the large plane 11 is provided with an annular inclined surface 12; a plurality of chip grooves 2 are evenly arranged on the outer peripheral surface of the bit body 1; the diamond flat composite teeth 3 include a plurality of edge teeth 31 evenly arranged on the annular inclined surface 12 and inner teeth 32 arranged in two rows and in opposite directions on the large plane 11; each row of inner teeth 32 includes a center tooth 321 and an outer edge tooth 322 lying on the same radius axis and a cutting auxiliary tooth 323 lying on one side of the outer edge tooth 322; two air holes 4 are symmetrically arranged on the large plane 11; two chip removal grooves 5 are symmetrically arranged on the large plane 11, one ends of the two chip removal grooves 5 are respectively corresponding to communicate with the two air holes 4, and the other ends of the two chip removal grooves 5 are respectively corresponding to communicate with any two of the plurality of chip grooves 2.

[0042] In the specific technical solution of the present utility model, the crown top of the bit body 1 is provided with a large plane 11, and the outer peripheral edge of the large plane 11 is provided with an annular inclined surface 12. The annular inclined surface 12 can evenly arrange a plurality of edge teeth 31 of the "horizontal" diamond flat composite teeth 3 according to the bit diameter, and a plurality of chip grooves 2 are interposed between adjacent edge teeth 31 at intervals. The large plane 11 at the crown top of the bit body 1 is provided with two rows of "horizontal" inner teeth 32 and cutting auxiliary teeth 323 in opposite directions based on the center line, that is, the center tooth 321, the outer edge tooth 322 and the cutting auxiliary tooth 323 located on the same radius axis, and the two rows of diamond flat composite teeth are arranged in opposite directions in pairs.

[0043] During the drilling operation, the side teeth 31, inner teeth 32 and the impact energy are carried by the drill bit body 1. The side teeth 31 and inner teeth 32 are used to break rocks. Since there is an inclination angle between the large flat surface 11 and the annular inclined surface 12, the side teeth 31 also incline outwards. Under the reciprocating impact force brought by the bypass valve etc. inside the down-the-hole drill (such as hydraulic), the down-the-hole drill bit with "horizontal" diamond flat composite teeth drills in the vertical direction. The large flat surface 11 at the top first contacts the soft formation. The inner teeth 32 on the large flat surface 11 are arranged with a large elevation angle and a certain side inclination angle. Since the diamond layer part of the diamond flat composite tooth 3 has a large degree of upswing, it first makes point contact with the soft formation. Coupled with the impact rotation, due to the large upswing amplitude of the diamond chamfer layer, the unit contact area with the soft rock formation is smaller than that of the conventional button bit spherical surface, the pressure is greater, and the effect of eating into the formation is better, thus improving the drilling speed; when the down-the-hole drill bit rotates at the bottom of the well, the side teeth 31 of the annular inclined surface 12 and the inner teeth 32 of the large flat surface 11 at the top affected by the impact force cooperate with each other. During the drilling in the soft formation, under the action of the impact force, the rock is vibrated and broken, which is conducive to the inner teeth 32 of the large flat surface 11 at the top pressing into the soft rock formation for ploughing; since the annular inclined surface 12 is subject to greater friction, it mainly acts on the formation within the range not affected by the impact vibration, and takes the rotation after the impact as the main movement track. Although the side teeth 31 at the annular inclined surface 12 do not have the structural hardness and strength of the diamond "spherical" composite teeth, the shearing effect is better in the soft formation. The side teeth 31 of the annular inclined surface 12 can flexibly adapt to the formation through different chamfer and elevation angles. Since there is a certain inclination angle between the annular inclined surface 12 and the large flat surface 11 at the top, as the annular inclined surface 12 with an inclination angle rotates, under the action of the flow channels of the spaced cuttings grooves 2 and the flushing fluid, the cuttings are driven above the drill bit body 1, so that the debris does not affect the normal drilling, and the drilling efficiency is improved.

[0044] It should be particularly noted that the air hole 4 is for the down-the-hole drill bit to drive the gas to the crown of the drill bit body 1 during the drilling process, and the generated air kinetic energy removes the cuttings on the large flat surface 11 at the top of the crown; secondly, during the high-frequency impact vibration and rotation of the down-the-hole drill bit body, the diamond flat composite teeth 3 at the crown cut and generate heat. If the heat is too high, it will affect the service life of the cutting teeth and even the entire drill bit. The air is blown through the air hole 4 to the inner teeth 32 of the diamond flat composite teeth 3 through the central channel of the drill bit shank to cool and flush the drill bit.

[0045] In addition, the "horizontal" inner teeth 32 on the large flat surface 11 cooperate with the tooth grooves. Under the design of a large elevation angle and a certain inclination angle, the diamond flat composite tooth grooves present a net-bag shape, and are fixedly connected with the diamond flat composite teeth 3 with high precision, and a welding allowance is left. The longitudinal surface and the bottom surface of the diamond flat composite teeth 3 are in contact with the side surface and the bottom surface of the tooth grooves respectively, to prevent the diamond flat composite teeth 3 from moving or falling off.

[0046] Further, please refer to Figure 2 As shown, the cutting edge directions of adjacent center teeth 321, outer edge teeth 322 and cutting auxiliary teeth 323 in the same row are the same, and the center teeth 321, outer edge teeth 322 and cutting auxiliary teeth 323 all include diamond wear-resistant layers and cemented carbide layers. The tooth pitch of the center teeth 321 does not exceed 5 mm, and the tooth pitch of the outer edge teeth 322 is 3 mm.

[0047] Specifically in this embodiment, the crown material of the drill bit body 1 belongs to the hard layer. The large flat surface 11 and the annular inclined surface 12 at the top are provided on the hard layer, and mounting tooth grooves for fixing the diamond flat composite teeth 3 are provided on the crown of the drill bit body 1. In this way, the center teeth 321, outer edge teeth 322 and cutting auxiliary teeth 323 are fixed on the drill bit body 1 through the mounting tooth grooves.

[0048] Since the specifications of the diamond flat composite teeth 3 are diverse, in this embodiment, the cutting edge directions of adjacent center teeth 321, outer edge teeth 322 and cutting auxiliary teeth 323 in the same row are the same, realizing full-coverage cutting of the drill bit contacting the rock formation and efficient rock breaking, and further improving the rock-breaking efficiency of the drill bit in soft formations.

[0049] More specifically, since diamond wear-resistant layers and high-strength cemented carbide layers are sequentially provided on the center teeth 321, outer edge teeth 322 and cutting auxiliary teeth 323 in this embodiment, by setting the diamond wear-resistant layers, the surface strength of the cutting teeth of the down-the-hole drill bit is improved, making it have both sharp formation-penetrating ability and wear resistance.

[0050] Among them, the diamond flat composite tooth body and the tooth groove are fixed by welding, and the solder is copper or silver solder. The diamond flat composite teeth 3 are flat composite teeth with large chamfers. The alloy layer is generally made of cemented carbide. Through this structure, the material cost can be reduced; the diamond layer of the "horizontal" diamond flat composite tooth body is the position where the impact force is the greatest. By adjusting the upward amplitude value and the inclination amplitude value of the diamond flat composite teeth 3, this position adopts the form of large chamfers or a combination of multiple circles and chamfers, enhancing its impact resistance while improving the formation-penetrating ability and structural strength of the diamond flat composite teeth 3.

[0051] Further, please refer to Figure 2 As shown, the distribution circle diameter of the center teeth 321 is smaller than the distribution circle diameter of the outer edge teeth 322, and the outer edge teeth 322 and the cutting auxiliary teeth 323 are on the same distribution circle. The included angle between the outer edge teeth 322 and the cutting auxiliary teeth 323 in the same row is 60°.

[0052] In the specific technical solution of the present utility model, the rock is broken by the edge teeth 31 and the inner teeth 32. And since the angle between the large plane 11 and the annular inclined plane 12 is 35°, the edge teeth 31 also incline outwards. Compared with the inner teeth 32 on the large plane 11 at the top, the edge teeth 31 mainly cut the rock on the wellbore wall by shear during the working process, and have higher requirements for the cutting stability of the drill bit.

[0053] It should be particularly noted that the diameters of the central teeth 321 and the outer edge teeth 322 can be flexibly matched according to the lithology, and they can have the same diameter or different diameters. Specifically, they can be selected according to the characteristics of soft formations.

[0054] Furthermore, please refer to Figure 2 As shown, the air holes 4 and the notches of the cuttings grooves 2 are symmetrically distributed at the central teeth 321, and the notches of the cuttings grooves 2 on the side close to the annular inclined plane 12 are evenly distributed between the edge teeth 31.

[0055] In the specific technical solution of the present utility model, the notch of the cuttings groove 2 is aligned with the central teeth 321. In this way, as the annular inclined plane 12 with an inclined angle rotates, the cuttings are driven above the drill bit body 1 under the action of the flow channels of the spaced cuttings grooves 2 and the flushing fluid, so that the debris does not affect the normal drilling and the drilling efficiency is improved.

[0056] Furthermore, please refer to Figure 2 As shown, the center line of the chip removal groove 5 passes through the center point of the large plane 11. Thus, by passing the center line of the chip removal groove 5 through the center point of the large plane 11, it is beneficial to make the cuttings generated by cutting at different places on the large plane 11 flow horizontally into the chip removal groove 5.

[0057] Furthermore, please refer to Figure 1 As shown, the angle between the large plane 11 and the annular inclined plane 12 is 35° - 45°. As a preferred mode of this embodiment, it is preferably 40 degrees between the large plane 11 and the annular inclined plane 12. In this way, when the edge teeth 31 and the inner teeth 32 are distributed at the head end of the drill bit body 1, the edge teeth 31 and the inner teeth 32 on adjacent circumferences work evenly up and down and complement each other in the rock breaking process.

[0058] Furthermore, please refer to Figure 1 As shown, the chip removal groove 5 is an arc-shaped long groove with a cross-sectional radius of 7.5 mm. The advantage of such a setting is that during the working of the drill bit, the cuttings can be discharged from the bottom of the hole in time, reducing repeated crushing and improving the drilling speed; the gas ejected from the air holes 4 can cool and clean each tooth, improving the rock breaking efficiency of the drill bit.

[0059] Furthermore, please refer to Figure 1 As shown, the diameter range of the drill bit body 1 is 95 mm - 465 mm. In this embodiment Figure 1-2As shown, it is 95 mm. There are 6 edge teeth 31 on the cuttings groove 2 and the annular inclined surface 12 respectively. The diameter of the cuttings groove 2 is 18 mm. The edge teeth 31 are evenly distributed on the outer circular inclined surface with a diameter of 95 mm. There are 6 inner teeth 32 on the large flat surface 11 of the crown. The inner teeth 32 are arranged in two rows and are staggered in pairs along their center lines. And the center tooth 321 is arranged on the top large flat surface with a diameter of 70 mm.

[0060] Further, please refer to Figure 1 、 2 As shown, the number of both the cuttings groove 2 and the edge teeth 31 is 6. The edge teeth 31 are evenly distributed on the outer circular inclined surface with a diameter of 95 mm. The number of the inner teeth 32 is 6, and the center tooth 321 is evenly distributed on the top large flat surface with a diameter of 70 mm.

[0061] As a preferred mode of this embodiment, the edge teeth 31 and the inner teeth 32 can respectively flexibly design the tooth arrangement modes with large elevation angles and certain side inclination angles to increase the ability of the cutting teeth to penetrate into the formation. The distribution circle diameter of the edge teeth 31 is larger than that of the inner teeth 32. Different specifications of down-the-hole drill bits in this example can also flexibly adjust the tooth arrangement angles and quantities to better adapt to different soft formations, thereby improving the cutting strength and comprehensive performance of each tooth.

[0062] Specific implementation working process:

[0063] The crown of the drill body 1 first contacts the rock formation and participates in rock breaking. The "horizontal" inner teeth 32 of the large flat surface 11 adopt the design mode of large elevation angle and side inclination. The diamond layer exposed on the side first has point contact with the formation. Due to the high pressure at the point contact position, it can more easily exert the sharp advantage of the diamond flat composite tooth 3 in the application of soft formations. When the diamond layer penetrates into the formation, relying on the impactor to vibrate the rock and the shearing and plowing of the diamond flat composite tooth 3, efficient rock breaking is carried out. While improving the drilling efficiency, the phenomenon of mud packing or slow drilling speed of conventional diamond spherical composite teeth is avoided in soft formations.

[0064] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A down-the-hole drill bit, characterized in that: include: A drill body (1), wherein a large flat surface (11) is provided at the head end of the drill body, and an annular inclined surface (12) is provided on the outer periphery of the large flat surface (11); A plurality of rock chip grooves (2) are evenly distributed on the outer peripheral surface of the drill bit body (1); The diamond plane composite tooth (3) comprises a plurality of side teeth (31) evenly arranged on the annular inclined surface (12) and a double row of internal teeth (32) arranged in opposite directions on the large plane (11); each row of the internal teeth (32) comprises a central tooth (321) and an outer edge tooth (322) lying on the same radial axis, and a cutting auxiliary tooth (323) lying on one side of the outer edge tooth (322); Two air holes (4) are symmetrically arranged on the large plane (11); Two chip removal grooves (5) are symmetrically arranged on the large plane (11), one end of the two chip removal grooves (5) is respectively connected to the two air holes (4), and the other end of the two chip removal grooves (5) is respectively connected to any two of the plurality of rock chip grooves (2).

2. The down-the-hole drill bit according to claim 1, characterized in that: The cutting edges of the adjacent center teeth (321), the outer edge teeth (322) and the cutting auxiliary teeth (323) in the same row have the same direction, and the center teeth (321), the outer edge teeth (322) and the cutting auxiliary teeth (323) all include a diamond wear-resistant layer and a cemented carbide layer, the tooth spacing of the center teeth (321) does not exceed 5 mm, and the tooth spacing of the outer edge teeth (322) is 3 mm.

3. The down-the-hole drill bit according to claim 1 or 2, characterized in that: The distribution circle diameter of the central teeth (321) is smaller than the distribution circle diameter of the outer edge teeth (322), and the outer edge teeth (322) and the cutting auxiliary teeth (323) are located on the same distribution circle, and the angle between the outer edge teeth (322) and the cutting auxiliary teeth (323) in the same row is 60°.

4. The down-the-hole drill bit according to claim 1, characterized in that: The air holes (4) are symmetrically distributed on the central teeth (321), and the notches of the cuttings grooves (2) close to the annular inclined surface (12) are evenly distributed between the side teeth (31).

5. The down-the-hole drill bit according to claim 1, characterized in that: The center line of the chip removal groove (5) passes through the center point of the large plane (11).

6. The down-the-hole drill bit according to claim 1, characterized in that: The angle between the large plane (11) and the annular inclined surface (12) is 35° to 45°.

7. The down-the-hole drill bit according to claim 1, characterized in that: The angle between the rock debris groove (2) and the axis of the large plane (11) is 6 to 10 degrees.

8. The down-the-hole drill bit according to claim 1, characterized in that: The chip removal groove (5) is an arc-shaped long groove with a cross-sectional radius of 7.5 mm.

9. The down-the-hole drill bit according to any one of claims 1-2 or 4-8, characterized in that: The diameter of the drill bit body (1) ranges from 95 mm to 465 mm.

10. The down-the-hole drill bit according to claim 9, characterized in that: The number of the cuttings trough (2) and the number of the side teeth (31) are both 6, the side teeth (31) are evenly distributed on an outer circular inclined surface with a diameter of 95 mm, the number of the inner teeth (32) is 6, and the center teeth (321) are evenly distributed on a top large plane with a diameter of 70 mm.

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