drill bit

Abstract

The present application relates to the technical field of drill bit, and specifically discloses a drill needle, which comprises a handle and a blade, the blade comprises a drill body and a drill tip, the drill tip is made of diamond throughout, the hardness of the drill tip is improved, and thus the wear resistance and service life of the drill needle can be greatly improved, the needle replacement frequency is reduced, and the production efficiency and yield of the drilling product are improved. Two chip removal grooves are arranged along the axial direction of the blade, so that the drill needle forms two cutting edges, the two cutting edges alternately participate in cutting during the rotary cutting of the drill needle, and the risk of broken needle is reduced; the two chip removal grooves form two chip removal channels, and the chip removal performance is improved. The cross-sectional profile of the chip removal groove comprises a first circular arc and a second circular arc which are smoothly connected, and the curvature radius of the first circular arc is not equal to that of the second circular arc, so that the volume of the chip removal groove is increased, the transition form of the inner wall of the chip removal groove is optimized, stress concentration is reduced, and the torsional stiffness and bending stiffness of the drill needle are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of drill bit technology, and more particularly to drill bits. Background Technology

[0002] Drill bits are commonly used for drilling holes in circuit boards. Existing drill bits use a structure of "carbide substrate + diamond coating," with a coating thickness of only about 1μm, and the adhesion between the coating and the substrate is limited. Under friction from high-hardness materials, the coating is easily worn and peeled off, causing the substrate to come into direct contact with the hard material, significantly shortening the drill bit's lifespan. Frequent drill bit replacements not only severely impact production efficiency but can also lead to drill bit breakage and even circuit board scrap, resulting in a yield loss of over 20% and a significant increase in overall production costs. Furthermore, the chip removal groove volume of existing drill bits is small, leading to poor chip removal and heat dissipation during processing, easily causing chip clogging and drill bit breakage. Summary of the Invention

[0003] The purpose of this invention is to provide a drill bit that not only improves the rigidity and wear resistance of the drill bit, but also improves the chip removal capability.

[0004] In one aspect of the present invention, a drill bit is provided, including a shank and a cutting edge, the cutting edge including a drill body and a drill tip, one end of the drill body along the axial direction of the cutting edge being connected to the shank, and the other end of the drill body along the axial direction of the cutting edge being connected to the drill tip, the drill tip being made entirely of diamond; The outer periphery of the cutting edge is provided with two chip removal grooves that both extend spirally along the axial direction of the cutting edge. The cross-sectional profile of the chip removal groove includes a first arc and a second arc that are smoothly connected. The radius of curvature of the first arc is not equal to the radius of curvature of the second arc. The cross-section of the chip removal groove is perpendicular to the extension direction of the chip removal groove.

[0005] As an alternative to the drill bit, one end of the first arc is flush with the end face of the groove on one side of the chip removal groove, and the other end is connected to one end of the second arc, while the other end of the second arc is flush with the end face of the groove on the other side of the chip removal groove.

[0006] As an alternative to the drill bit, the drill tip has two first flank faces and two second flank faces at one end away from the drill body along the axial direction of the cutting edge. The two first flank faces are arranged in a centrally symmetrical manner around the central axis of the cutting edge, and the two second flank faces are arranged in a centrally symmetrical manner around the central axis of the cutting edge. The first flank face intersects with one of the second flank faces to form a center line, and intersects with the other second flank face to form a transverse cutting edge. Each first flank face intersects with the inner wall of the chip removal groove to form a main cutting edge, and each second flank face intersects with the inner wall of the chip removal groove to form a flank cutting edge. The chip removal groove includes a first groove segment and a second groove segment. The cross-sectional profile of the first groove segment is the first circular arc, and the cross-sectional profile of the second groove segment is the second circular arc. The first groove segment is correspondingly arranged with the main cutting edge. The cross-sections of the first groove segment and the second groove segment are both perpendicular to the extension direction of the chip removal groove.

[0007] As an alternative to the drill bit, the first arc includes a bottom arc segment located at the bottom of the chip removal groove.

[0008] As an alternative drill bit configuration, the ratio of the radius of curvature of the first arc to the diameter of the cutting edge ranges from 0.25 to 0.4; and / or, The radius of curvature of the second arc is greater than that of the first arc.

[0009] As an alternative to drill bit, the drill tip is welded to the drill body.

[0010] As an alternative to the drill bit, the diamond is polycrystalline diamond or CVD diamond.

[0011] As an alternative to the drill bit, the chip removal groove includes a front chip removal groove and a rear chip removal groove distributed and connected along its extension direction. The front chip removal grooves of the two chip removal grooves are centrally symmetrically arranged around the central axis of the cutting edge, and the rear chip removal grooves of the two chip removal grooves are arranged side by side and connected to each other.

[0012] As an optional drill bit configuration, the diameter of the cutting edge ranges from 0.1mm to 0.3mm; and / or, The length of the cutting edge along its axial direction ranges from 1mm to 15mm.

[0013] As an optional drill bit solution, the helix angle of the chip removal groove ranges from 20° to 55°; and / or, The apex angle of the drill tip ranges from 110° to 150°.

[0014] Compared with the prior art, the above technical solution has at least the following advantages or beneficial effects: The drill bit of this invention has a drill tip made entirely of diamond, which increases the hardness of the drill tip and thus significantly improves the wear resistance of the drill bit. Compared with traditional coated drill bits, this increases the service life of the drill bit, reduces the frequency of drill bit replacement, and helps to improve production efficiency and the yield of drilled products. At the same time, the drill tip, which is made entirely of diamond, can be processed by precision grinding, resulting in higher sharpness and thus significantly improving the accuracy of the machined holes. For example, the hole position accuracy error can be controlled within ±0.001mm.

[0015] Meanwhile, by setting two chip removal grooves that both extend axially and helically along the cutting edge, the drill bit forms two cutting edges. When the drill bit rotates and cuts, the two cutting edges participate in cutting alternately, which can effectively reduce the cutting load of a single cutting edge and reduce the risk of drill bit breakage. Furthermore, the two chip removal grooves form two chip removal channels, improving chip removal performance. By making the cross-sectional profile of the chip removal groove include a smoothly connected first arc and a second arc, with the radii of curvature of the first arc not being equal to those of the second arc, not only is the volume of the chip removal groove increased, but the transition shape of the inner wall of the chip removal groove is also optimized. For example, it avoids the chip removal groove being too deep or the inner wall being too steep, thereby reducing stress concentration and effectively improving the torsional stiffness and bending stiffness of the drill bit, achieving synergistic optimization of chip removal capacity and stiffness. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the drill bit structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the first partial structure of the blade in an embodiment of the present invention; Figure 3 This is a schematic diagram of the end structure of the drill tip in an embodiment of the present invention; Figure 4 This is a schematic diagram of the second partial structure of the blade in an embodiment of the present invention; Figure 5 This is a schematic diagram of the third partial structure of the blade in an embodiment of the present invention; Figure 6 for Figure 5 A cross-sectional view of surface AA; Figure 7 This is a schematic diagram of the fourth partial structure of the blade in an embodiment of the present invention.

[0017] In the picture: 10. Centerline; 1. Shank; 2. Cutting edge; 21. Drill body; 22. Drill tip; 221. First flank face; 222. Second flank face; 223. Chisel edge; 224. Main cutting edge; 225. Rake edge; 23. Chip evacuation groove; 23a. First groove split; 23b. Second groove split; 23c. Front chip evacuation groove; 23d. Rear chip evacuation groove; 231. First arc; 232. Second arc. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] like Figures 1 to 7 As shown, this embodiment provides a drill bit, including a shank 1 and a cutting edge 2. The cutting edge 2 includes a drill body 21 and a drill tip 22. One end of the drill body 21 along the axial direction of the cutting edge 2 is connected to the shank 1, and the other end of the drill body 21 along the axial direction of the cutting edge 2 is connected to the drill tip 22. The drill tip 22 is made entirely of diamond. The outer periphery of the cutting edge 2 is provided with two chip removal grooves 23 that both extend spirally along the axial direction of the cutting edge 2. The cross-sectional profile of the chip removal grooves 23 includes a first arc 231 and a second arc 232 that are smoothly connected. The radius of curvature of the first arc 231 is not equal to the radius of curvature of the second arc 232. The cross-section of the chip removal grooves 23 is perpendicular to the extension direction of the chip removal grooves 23.

[0026] In this embodiment, the drill bit's tip 22 is made entirely of diamond, which increases its hardness and significantly improves its wear resistance. Compared to traditional coated drill bits, this extends the drill bit's lifespan, reduces the frequency of replacement, and helps improve production efficiency and the yield of drilled products. Furthermore, the diamond-made tip 22 can be precision-ground, resulting in higher sharpness and significantly improving the accuracy of the machined holes. For example, the hole position accuracy error can be controlled within ±0.001mm.

[0027] Meanwhile, by setting two chip removal grooves 23 that both extend helically along the cutting edge 2, the drill bit forms two cutting edges. When the drill bit rotates and cuts, the two cutting edges participate in cutting alternately, which can effectively reduce the cutting load of a single cutting edge and reduce the risk of drill bit breakage. Furthermore, the two chip removal grooves 23 form two chip removal channels, improving chip removal performance. By making the cross-sectional profile of the chip removal groove 23 include a smoothly connected first arc 231 and a second arc 232, and the radius of curvature of the first arc 231 is not equal to that of the second arc 232, not only is the volume of the chip removal groove 23 increased, but the transition shape of the inner wall of the chip removal groove 23 is also optimized. For example, it avoids the chip removal groove 23 from being too deep or the inner wall being too steep, thereby reducing stress concentration and effectively improving the torsional stiffness and bending stiffness of the drill bit, achieving synergistic optimization of chip removal capacity and stiffness.

[0028] In some embodiments, the drill tip 22 is welded to the drill body 21, thereby improving the convenience and stability of the connection between the drill tip 22 and the drill body 21, which is beneficial to improving the service life of the drill bit.

[0029] In this embodiment, the drill body 21 includes a base material portion and a wear-resistant layer covering the circumferential outer side of the base material portion. Exemplarily, the base material portion is made of cemented carbide, a material in the prior art, and the wear-resistant layer is a diamond coating. That is, the drill tip 22 is entirely made of diamond, and the drill body 21 adopts a structure of cemented carbide base material + diamond coating, thereby reducing costs while improving the rigidity, wear resistance, and chip removal capability of the drill bit. Of course, in other embodiments, the drill body 21 can also be entirely made of diamond.

[0030] In some embodiments, the diamond is polycrystalline diamond or CVD diamond (Chemical Vapor Deposition Diamond, which is a synthetic diamond material prepared by chemical vapor deposition, mainly including polycrystalline and single crystal forms), thereby enabling the drill tip 22 to achieve a hardness of over 10000 HV and a thermal conductivity of 1800 W / (m·K)-2200 W / (m·K). Compared with the existing drill bits that use a "hard alloy substrate + diamond coating" structure, this fundamentally solves the defect of a sharp drop in drill bit life caused by coating peeling.

[0031] In some embodiments, such as Figures 2 to 4 As shown, one end of the first arc 231 is flush with the end face of the groove on one side of the chip removal groove 23, and the other end is connected to one end of the second arc 232. The other end of the second arc 232 is flush with the end face of the groove on the other side of the chip removal groove 23, which helps to further expand the volume of the chip removal groove 23 and improve the chip removal capacity.

[0032] In some embodiments, the drill tip 22 is provided with two first flank faces 221 and two second flank faces 222 at one end of the cutting edge 2 away from the drill body 21 along the axial direction. The two first flank faces 221 are centrally symmetrical about the central axis of the cutting edge 2, and the two second flank faces 222 are centrally symmetrical about the central axis of the cutting edge 2. The first flank face 221 intersects with one of the second flank faces 222 to form a center line 10, and intersects with the other second flank face 222 to form a chisel edge 223. Each first flank face 221 intersects with the inner wall of the chip removal groove 23 to form a main cutting edge 224, and each second flank face 222 intersects with the inner wall of the chip removal groove 23 to form a flank edge 225. This configuration not only improves the consistency of the radial mass distribution of the drill bit and reduces the yaw rate during drill bit use, but also improves the symmetry of the cutting force on the flank face that is centrally symmetrically arranged around the central axis of the cutting edge 2, which is beneficial to improving the positioning capability of the drill bit; it also ensures that the main cutting edge 224 is sharper, thereby improving the cutting efficiency of the main cutting edge 224 and the drilling quality.

[0033] Furthermore, the chip removal groove 23 includes a first groove segment 23a and a second groove segment 23b. The cross-sectional profile of the first groove segment 23a is a first circular arc 231, and the cross-sectional profile of the second groove segment 23b is a second circular arc 232. The first groove segment 23a is correspondingly arranged to the main cutting edge 224. The cross-sections of both the first groove segment 23a and the second groove segment 23b are perpendicular to the extension direction of the chip removal groove 23. This arrangement allows the cutting chips generated by the main cutting edge 224 to quickly enter the first groove segment 23a, thereby improving chip removal performance.

[0034] In some embodiments, the first arc 231 includes a bottom arc segment located at the bottom of the chip removal groove 23, thereby enabling the first groove segment 23a to provide the main chip space, and the inner wall of the second groove segment 23b to form a transition area at the groove opening. This can expand the volume of the chip removal groove 23 while optimizing the transition shape of the inner wall of the chip removal groove 23 to reduce stress concentration.

[0035] In some embodiments, the ratio of the radius of curvature of the first arc 231 to the diameter of the cutting edge 2 is in the range of 0.25-0.4, which can optimize the transition shape of the inner wall of the chip removal groove 23 while expanding the volume of the chip removal groove 23, so as to reduce stress concentration.

[0036] For example, the ratio of the radius of curvature of the first arc 231 to the diameter of the cutting edge 2 can be any value between 0.25 and 0.4. For instance, the ratio of the radius of curvature of the first arc 231 to the diameter of the cutting edge 2 can be 0.25, 0.3, 0.35, or 0.4.

[0037] Furthermore, the radius of curvature of the second arc 232 is greater than that of the first arc 231, which can optimize the transition shape of the inner wall of the chip removal groove 23 while expanding the volume of the chip removal groove 23, so as to reduce stress concentration.

[0038] In some embodiments, for any chip removal groove 23, the depth of the chip removal groove 23 gradually decreases along the extending direction from the cutting edge 2 to the shank 1. During the operation of the drill bit, the part with the greatest stress is at the end of the cutting edge 2 near the shank 1. In order to prevent the drill bit from breaking, the depth of the chip removal groove 23 is gradually reduced along the extending direction from the cutting edge 2 to the shank 1 to increase the rigidity of the drill bit.

[0039] In some embodiments, such as Figures 5 to 7As shown, the chip removal groove 23 includes a front chip removal groove 23c and a rear chip removal groove 23d distributed and connected along its extension direction. The front chip removal groove 23c of the two chip removal grooves 23 is centrally symmetrically arranged around the central axis of the cutting edge 2, and the rear chip removal grooves 23d of the two chip removal grooves 23 are arranged side by side and connected to each other. That is to say, by changing the helix angle of the two chip removal grooves 23, the ends of the two chip removal grooves 23 near the shank 1 are gradually connected, which helps to improve the rigidity of the drill bit. In other words, through the above arrangement, the structural strength of the drill bit is guaranteed, and sufficient chip removal space is provided, effectively reducing the risk of chip blockage and drill bit breakage.

[0040] It should be noted that the chip removal groove 23 also includes a connecting chip removal groove between the front chip removal groove 23c and the rear chip removal groove 23d. That is, in the same chip removal groove 23, the front chip removal groove 23c and the rear chip removal groove 23d are smoothly connected by the connecting chip removal groove.

[0041] In some embodiments, the diameter of the cutting edge 2 ranges from 0.1mm to 0.3mm, which can meet the requirements for machining small holes and improve the versatility of the drill bit. The diameter of the cutting edge 2 is the same as the drill bit diameter. That is to say, the drill bit of this embodiment can still maintain excellent cutting performance and a long service life even with an extremely small drill bit diameter of 0.1mm-0.3mm.

[0042] It should be noted that for UC type (i.e., undercut type) drill bits, the cutting edge 2 is divided into a first segment and a second segment connected sequentially along its axis. The drill tip 22 is located at the end of the first segment away from the second segment. The diameter of the first segment ranges from 0.1mm to 0.3mm, and the diameter of the second segment is slightly smaller than that of the first segment. For example, the diameter of the second segment is 0.01mm smaller than that of the first segment. Usually, the diameter of the first segment is called the drill bit diameter, and the diameter of the second segment is called the UC diameter.

[0043] In some embodiments, the length of the cutting edge 2 along its axial direction ranges from 1mm to 15mm, which can satisfy deep hole machining and improve the versatility of the drill bit. That is to say, the drill bit of this embodiment can still maintain excellent cutting performance and a long service life when machining holes with a depth of 1mm-15mm.

[0044] For example, the length of the cutting edge 2 along its axial direction can be any value between 1mm and 15mm, such as 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm, or 15mm.

[0045] In some embodiments, the helix angle of the chip removal groove 23 is in the range of 20°-55°, which can meet different chip removal requirements and improve the versatility of the drill bit.

[0046] For example, the helix angle of the chip removal groove 23 can be any value between 20° and 55°, such as 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°, 29°, 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, 51°, 52°, 53°, 54° or 55°.

[0047] In some embodiments, the apex angle of the drill tip 22 ranges from 110° to 150°. It should be noted that a smaller apex angle results in a longer main cutting edge 224, reducing the load on a single cutting edge and decreasing the axial force. This improves the axial stability of the drill bit, as well as heat dissipation and service life. However, a smaller apex angle weakens the strength of the drill tip 22, increases chip deformation, and leads to increased torque. By setting the apex angle of the drill tip 22 to a range of 110° to 150°, a synergistic optimization of drill bit heat dissipation, service life, and drill tip 22 strength can be achieved.

[0048] For example, the apex angle of the drill tip 22 can be any value between 110° and 150°, such as 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145° or 150°.

[0049] It should be noted that when processing M9 copper-clad laminate (M9 copper-clad laminate is a high-performance grade high-frequency high-speed printed circuit board (PCB) substrate that can support ultra-high-speed signal transmission), the drill bit life of this embodiment can reach more than 10,000 holes / bits, which is 50 to 100 times longer than the drill bit with the "hard alloy substrate + diamond coating" structure in the prior art.

[0050] In this embodiment, the drill tip 22 is made entirely of polycrystalline diamond, with a grain size of less than 3μm and a hardness of not less than 10000HV. The cutting edge 2 has a diameter of 0.2mm and an axial length of 5mm, while the drill shank has a diameter of 3.175mm. The helix angle of the front chip removal groove 23c and the rear chip removal groove 23d of each chip removal groove 23 is 30°. The radius of curvature of the first arc 231 is 0.08mm, and the radius of curvature of the second arc 232 is 0.12mm. The apex angle of the drill tip 22 is 130°, the first clearance angle is 8°, and the second clearance angle is 20°.

[0051] Furthermore, through experimental verification, when the drill bit of this embodiment was used for drilling M9 copper-clad laminate, under the processing conditions of spindle speed of 160krpm and feed rate of 20mm / s, after drilling 10,000 holes continuously, the drill tip 22 showed no obvious wear, and the hole wall quality met the requirements of IPC-6012 standard (i.e., rigid printed circuit board qualification and performance specification).

[0052] Of course, in other embodiments, the drill tip 22 can also be made entirely of CVD diamond, with a cutting edge 2 having a diameter of 0.15 mm and an axial length of 2.5 mm. The helix angle of the front chip removal groove 23c and the rear chip removal groove 23d of each chip removal groove 23 is 35°. The radius of curvature of the first arc 231 is 0.05 mm, and the radius of curvature of the second arc 232 is 0.08 mm. Experimental verification shows that when used for drilling M9 copper-clad laminates, the service life of a single drill bit can reach over 8000 holes.

[0053] In other embodiments, the diameter of the cutting edge 2 can be 0.3 mm, and its axial length can be 12 mm. The helix angle of the front chip removal groove 23c and the rear chip removal groove 23d of each chip removal groove 23 is 25°. The radius of curvature of the first arc 231 is 0.12 mm, and the radius of curvature of the second arc 232 is 0.18 mm. Experimental results show that in deep hole machining, chip removal is smooth, with no chip blockage or needle breakage.

[0054] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A drill bit, characterized in that, It includes a shank and a cutting edge. The cutting edge includes a drill body and a drill tip. One end of the drill body along the axial direction of the cutting edge is connected to the shank, and the other end of the drill body along the axial direction of the cutting edge is connected to the drill tip. The drill tip is made entirely of diamond. The outer periphery of the cutting edge is provided with two chip removal grooves that both extend spirally along the axial direction of the cutting edge. The cross-sectional profile of the chip removal groove includes a first circular arc and a second circular arc that are smoothly connected. The radius of curvature of the first circular arc is not equal to the radius of curvature of the second circular arc. The cross-section of the chip removal groove is perpendicular to the extension direction of the chip removal groove.

2. The drill bit according to claim 1, characterized in that, One end of the first arc is flush with the end face of the groove on one side of the chip removal groove, and the other end is connected to one end of the second arc. The other end of the second arc is flush with the end face of the groove on the other side of the chip removal groove.

3. The drill bit according to claim 1, characterized in that, The drill tip has two first flank faces and two second flank faces at one end away from the drill body along the axial direction of the cutting edge. The two first flank faces are arranged symmetrically about the central axis of the cutting edge, and the two second flank faces are arranged symmetrically about the central axis of the cutting edge. The first flank faces intersect with one of the second flank faces to form a center line, and intersect with the other second flank face to form a chisel edge. Each first flank face intersects with the inner wall of the chip removal groove to form a main cutting edge, and each second flank face intersects with the inner wall of the chip removal groove to form a flank edge. The chip removal groove includes a first groove segment and a second groove segment. The cross-sectional profile of the first groove segment is the first circular arc, and the cross-sectional profile of the second groove segment is the second circular arc. The first groove segment is correspondingly arranged with the main cutting edge. The cross-sections of the first groove segment and the second groove segment are both perpendicular to the extension direction of the chip removal groove.

4. The drill bit according to claim 3, characterized in that, The first arc includes the bottom arc segment located at the bottom of the chip removal groove.

5. The drill bit according to claim 3, characterized in that, The ratio of the radius of curvature of the first arc to the diameter of the cutting edge ranges from 0.25 to 0.4; and / or, The radius of curvature of the second arc is greater than that of the first arc.

6. The drill bit according to claim 1, characterized in that, The drill tip is welded to the drill body.

7. The drill bit according to claim 1, characterized in that, The diamond is polycrystalline diamond or CVD diamond.

8. The drill bit according to claim 1, characterized in that, The chip removal groove includes a front chip removal groove and a rear chip removal groove that are distributed and connected along its extension direction. The front chip removal grooves of the two chip removal grooves are arranged in a centrally symmetrical manner around the central axis of the cutting edge, and the rear chip removal grooves of the two chip removal grooves are arranged side by side and connected to each other.

9. The drill bit according to claim 1, characterized in that, The diameter of the cutting edge ranges from 0.1mm to 0.3mm; and / or, The length of the cutting edge along its axial direction ranges from 1mm to 15mm.

10. The drill bit according to claim 1, characterized in that, The helix angle of the chip removal groove ranges from 20° to 55°; and / or, The apex angle of the drill tip ranges from 110° to 150°.

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