Internally cooled drill bit

Abstract

The present invention discloses an internally cooled drill, comprising a drill body, a drill tip at the front end of the drill body, at least two cooling holes extending axially and penetrating to both ends, each cooling hole is evenly distributed around the axis of the drill body, the cross section of the cooling hole is circular, the outlet is located on the back blade of the drill tip, the outlet of the cooling hole is equipped with a cylindrical nozzle, the inner end inlet of the nozzle forms an inlet contour, the outer end outlet forms an outlet contour, the inlet contour is circular, and the outlet contour is non-circular. The internally cooled drill has the advantages of convenient processing and manufacturing, good cooling effect, and strong adaptability, which is conducive to ensuring the symmetry of the drill and the balance of cutting force, thereby improving the drilling stability and the service life of the drill.

Description

Technical Field

[0001] The invention relates to the technical field of drill bits, and in particular to an internally cooled drill bit. Background Art

[0002] Drills are used for drilling holes on mechanical parts and are a widely used cutting tool in the field of mechanical manufacturing. During the drilling process, the tool is in a semi-enclosed state, cutting heat is not easy to dissipate, chips are not easy to discharge, and the application conditions are very harsh. In order to improve the service life of the drill bit and the hole processing quality, most drill bits are designed with cooling holes. The common shape of cooling holes is circular, including straight holes and spiral holes.

[0003] As the inlet and outlet channels for coolant, cooling holes are an important factor affecting the distribution of coolant flow field during processing. Reasonable optimization and design of cooling hole structure are crucial to improving the chip removal performance of drill bits, reducing cutting temperature, and improving drill performance. Therefore, drill cooling hole design is an important part of drill bit design and manufacturing. Patent document with announcement number CN102802853A discloses a drill bit with cooling holes. The drill bit has an inner cooling hole that is approximately triangular. It is said that the coolant supply can be increased without damaging the strength of the drill body. It can also effectively and stably open holes for difficult-to-cut materials such as stainless steel. In order to improve the cooling effect of the drill bit, a published Japanese patent mentions the design of a drill bit with droplet-shaped and elliptical inner cooling holes.

[0004] At present, almost all metal cutting drills in the field of mechanical manufacturing are made of cemented carbide. The manufacture of internally cooled drills depends on internally cooled rods, and the forming of cooling holes is a key link in the preparation of internally cooled rods. It is very difficult and has a decisive influence on the dimensional accuracy and quality of the rods. Conventional cooling holes generally extend axially from the drill tip to the shank. In order to facilitate processing, the cooling holes are generally designed to be circular, that is, the cross-section of the cooling holes is circular. The difficulty of process control in its preparation and forming is relatively small. However, the outlet profile of the circular cooling hole on the drill tip is also quasi-circular, and its cooling effect is not good. In order to improve the cooling effect, the cooling holes can be designed into other non-circular structures such as triangles, ellipses, kidneys, trapezoids, etc. Even if the cross-section of the cooling holes is triangles, ellipses, kidneys, trapezoids, etc., the dimensional accuracy and symmetry of the cooling holes of non-circular structures will be difficult to guarantee, resulting in unbalanced cutting force of the drill, unstable drilling, and poor service life. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an internally cooled drill bit which is easy to process, has good cooling effect, strong adaptability, and is beneficial to ensuring the symmetry of the drill bit and the balance of cutting force, thereby improving the drilling stability and the service life of the drill bit.

[0006] A drill with internal cooling comprises a drill body, a drill tip is arranged at the front end of the drill body, at least two cooling holes extending axially and penetrating to both ends are arranged in the drill body, the cooling holes are evenly distributed around the axis of the drill body, the cross section of the cooling hole is circular, the outlet is located on the back cutting edge of the drill tip, the outlet of the cooling hole is equipped with a cylindrical nozzle, the inner end inlet of the nozzle forms an inlet contour, and the outer end outlet forms an outlet contour, the inlet contour is circular, and the outlet contour is non-circular.

[0007] As a further improvement of the above technical solution:

[0008] The outlet profile has a symmetrical structure, and a symmetry plane of the outlet profile passes through the center of the outlet profile and the center line 66 of the nozzle.

[0009] An outlet channel connecting the inlet contour and the outlet contour is formed in the nozzle. The outlet channel forms an upper generatrix and a lower generatrix on a longitudinal section passing through a symmetry plane of the outlet contour. The angle between the upper generatrix and the centerline of the nozzle is set to α1, and the angle between the lower generatrix and the centerline of the nozzle is set to α2, satisfying α1>α2.

[0010] The outlet profile is triangular, elliptical, kidney-shaped, figure 8-shaped or trapezoidal.

[0011] The outer diameter of the nozzle is set to d0, and the diameter of the inlet profile is set to d1, satisfying 0.8×d0≤ d1≤ 0.9×d0.

[0012] The area enclosed by the inlet contour is S1, and the area enclosed by the outlet contour is S2, satisfying 0.6×S1≤ S2≤0.9×S1.

[0013] The diameter of the inlet profile is set to d1, and the maximum radial dimension L1 of the outlet profile is smaller than d1.

[0014] The drill tip is provided with a plurality of cutting edges evenly distributed around the axis of the main body, and the outlets of the cooling holes are respectively arranged on the back surfaces of the cutting edges.

[0015] The outer edge of the outer end of the nozzle forms an outer end contour, and the outlet contour is eccentrically arranged relative to the outer end contour close to the corresponding cutting edge.

[0016] The length of the nozzle is set to L, and the outer diameter is set to d0, satisfying 2×d0≤ L ≤ 5×d0.

[0017] Compared with the prior art, the advantages of the present invention are:

[0018] The internal cooling drill of the present invention, on the one hand, penetrates the front and rear ends of the drill tip in the form of a circular cooling hole, thereby maintaining the convenience and symmetry of processing; on the other hand, by installing a cylindrical nozzle at the outlet of the cooling hole and specially designing the inlet profile and the outlet profile, the shape, flow rate, direction, etc. of the cooling water outflow can be better controlled, thereby improving the cooling effect, avoiding the cooling hole penetrating the front and rear ends of the drill tip in an overall non-circular form, reducing the processing difficulty, and facilitating the dimensional accuracy and symmetry of the cooling hole; on the third hand, by combining the circular cooling hole with the cylindrical nozzle, the cooling effect is improved, and it is also conducive to ensuring the symmetry and cutting force balance of the internal cooling drill, thereby improving the drilling stability and the service life of the drill; on the fourth hand, nozzles with outlet profiles of different shapes can be designed according to different application needs. By combining the nozzle with the cooling hole, different application requirements can be met, the adaptability is improved, and different application requirements can be met by replacing different nozzles, thereby reducing the processing cost; on the fifth hand, by combining the nozzle and the cooling hole in a split manner, the processing of the inlet profile, the outlet profile, and the internal channel of the nozzle is facilitated.

[0019] In the internally cooled drill bit of the present invention, water enters the water outlet channel through the inlet contour and water exits through the outlet contour, thereby forming a good water outlet effect and achieving a good cooling effect.

[0020] In the internally cooled drill bit of the present invention, the outer diameter of the nozzle is set to d1, and the diameter of the inlet profile is set to d1, which satisfies 0.8×d0≤d1≤0.9×d0. Such a structure and parameter setting are conducive to ensuring the smoothness of the coolant flowing from the cooling hole into the nozzle, and on the other hand, it is also conducive to ensuring that the flow loss is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the main structure of the first embodiment of the internal cooling drill bit of the present invention.

[0022] Figure 2 It is a schematic diagram of the drill tip side structure of the first embodiment of the internal cooling drill bit of the present invention.

[0023] Figure 3 yes Figure 1 Schematic diagram of the cross-sectional structure of AA.

[0024] Figure 4 It is a schematic structural diagram of the nozzle of the first embodiment of the internal cooling drill bit of the present invention.

[0025] Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure of BB.

[0026] Figure 6 It is a schematic diagram of the main structure of the second embodiment of the internal cooling drill bit of the present invention.

[0027] Figure 7 It is a schematic structural diagram of the nozzle of the third embodiment of the internal cooling drill bit of the present invention.

[0028] Figure 8 It is a schematic structural diagram of the nozzle of the fourth embodiment of the internal cooling drill bit of the present invention.

[0029] Fig. 9 It is a schematic structural diagram of the nozzle of the fifth embodiment of the internal cooling drill bit of the present invention.

[0030] Fig.10 It is a schematic structural diagram of the nozzle of the sixth embodiment of the internal cooling drill bit of the present invention.

[0031] The symbols in the figure represent:

[0032] 1. Axis; 10. Main body; 2. Drill tip; 3. Shank; 4. Cooling hole; 5. Flank; 6. Nozzle; 61. Outer end profile; 62. Inlet profile; 63. Outlet profile; 64. Upper generatrix; 65. Lower generatrix; 66. Centerline; 7. Cutting edge; 8. Water outlet channel. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In the present invention, unless otherwise clearly specified and limited, the terms "assemble", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Embodiment 1:

[0038] Figures 1 to 5 An embodiment of an internally-cooled drill bit of the present invention is shown. The internally-cooled drill bit of this embodiment comprises a drill bit body 10. A drill tip 2 is provided at the front end of the drill bit body 10. At least two cooling holes 4 extending axially and penetrating to both ends are provided in the drill bit body 10. The cooling holes 4 are evenly distributed around the axis 1 of the drill bit body 10. The cross section of the cooling hole 4 is circular, and the outlet is located on the back cutting edge 5 of the drill tip 2. A cylindrical nozzle 6 is installed at the outlet of the cooling hole 4. The inlet of the inner end (the end facing the inside of the cooling hole 4) of the nozzle 6 forms an inlet contour 62, and the outlet of the outer end (the end facing the outside of the cooling hole 4) forms an outlet contour 63. The inlet contour 62 is circular, and the outlet contour 63 is non-circular.

[0039] The internally cooled drill bit, on the one hand, penetrates the front and rear ends of the drill tip 2 in the form of a circular cooling hole 4, thereby maintaining the convenience and symmetry of processing; on the other hand, by installing a cylindrical nozzle 6 at the outlet of the cooling hole 4, and by the special design of the inlet profile 62 and the outlet profile 63, the form, flow rate, direction, etc. of the cooling water outflow can be better controlled, thereby improving the cooling effect, avoiding the cooling hole 4 penetrating the front and rear ends of the drill tip 2 in the form of an overall non-circular shape, reducing the processing difficulty, and facilitating the dimensional accuracy and symmetry of the cooling hole 4; on the third hand, by combining the circular cooling hole 4 with the cylindrical The combination of the nozzle 6 not only improves the cooling effect, but also helps to ensure the symmetry and cutting force balance of the internally cooled drill bit, thereby improving the drilling stability and the service life of the drill bit; fourthly, the nozzle 6 with an outlet profile 63 of different shapes can be designed according to different application needs. Through the combination of the nozzle 6 and the cooling hole 4, different application requirements can be met, and the adaptability is improved. By replacing different nozzles 6, different application requirements can be met, reducing the processing cost; fifthly, through the split combination of the nozzle 6 and the cooling hole 4, the processing of the inlet profile 62, the outlet profile 63, and the internal channel of the nozzle 6 is facilitated.

[0040] In general, due to the limitation of the preparation process of the inner cooling hole 4 bar stock, the cross-sectional shape of the cooling hole 4 is usually designed to be circular, which can ensure the dimensional accuracy and symmetry of the cooling hole 4 during the processing of the inner cooling bar stock. However, in order to obtain a better cooling effect, the cross-sectional shape of the cooling hole 4 sometimes needs to be optimized to be non-circular, but the preparation process of the non-circular cross-sectional cooling hole 4 bar stock is difficult and costly, especially when the dimensional accuracy and symmetry of the cooling hole 4 are not high, the service life of the inner cooling drill bit will be reduced. An effective solution to this contradiction is to assemble and set a hollow cylindrical nozzle 6 inside the cooling hole 4 at the outlet end of the cooling hole 4, the inlet profile 62 of the nozzle 6 is circular, matching the inner wall of the cooling hole 4, and the outlet profile 63 is an optimized non-circular structure. According to different application requirements, the outlet profile 63 can be set to special shapes such as elliptical, triangular, kidney-shaped, 8-shaped, trapezoidal, etc., so as to achieve the purpose of optimizing the outlet shape of the cooling hole 4 without changing the main structure of the inner cooling bar stock.

[0041] Furthermore, if Figure 4 As shown, in this embodiment, the outlet profile 63 is a symmetrical structure, and the symmetry plane of the outlet profile 63 passes through the center of the outlet profile 63 (such as Figure 4 The outlet profile 63 is a point O as shown in the figure and the center line 66 of the nozzle 6. That is, the center of the outlet profile 63 and the center line 66 of the nozzle 6 are both located on the symmetry plane of the outlet profile 63, further improving the symmetry of the overall structure. Furthermore, the symmetry plane of the outlet profile 63 passes through the axis 1 of the drill body 10, that is, the axis 1 of the drill body 10 is located on the symmetry plane of the outlet profile 63.

[0042] Furthermore, if Figure 5 As shown, in this embodiment, a water outlet channel 8 connecting the inlet profile 62 and the outlet profile 63 is formed in the nozzle 6. The water outlet channel 8 forms an upper busbar 64 and a lower busbar 65 on the longitudinal section passing through the symmetry plane of the outlet profile 63. The angle between the upper busbar 64 and the center line 66 of the nozzle 6 is set to α1, and the angle between the lower busbar 65 and the center line 66 of the nozzle 6 is set to α2, satisfying α1>α2. The water outlet channel 8 of this structure, water enters through the inlet profile 62 and water exits through the outlet profile 63, can form a good water outlet effect and achieve a good cooling effect. α1>α2, indicating that the central axis of the water outlet channel 8 does not coincide with the center line 66 of the nozzle 6. Preferably, α1=6°, α2=2°.

[0043] Furthermore, in this embodiment, the outlet profile 63 is elliptical.

[0044] Furthermore, in this embodiment, the outer diameter of the nozzle 6 is set to d0, and the diameter of the inlet profile 62 is set to d1, satisfying 0.8×d0≤ d1≤ 0.9×d0. Such a structure and parameter setting, on the one hand, is conducive to ensuring the smoothness of the coolant flowing from the cooling hole 4 into the nozzle 6, and on the other hand, it is also conducive to reducing flow loss. Further, the inlet profile 62 of the nozzle 6 is designed to be circular and concentric with the cooling hole 4, and its diameter d1 is smaller than the diameter d of the cooling hole 4, but is relatively close to the size of d0. On the one hand, it makes the coolant flow from the cooling hole 4 into the nozzle 6 smoother, and on the other hand, it is more conducive to reducing flow loss. Preferably, d1=0.63mm, d0=0.7mm.

[0045] Furthermore, in this embodiment, the area enclosed by the inlet profile 62 is S1, and the area enclosed by the outlet profile 63 is S2, which satisfies 0.6×S1≤ S2≤ 0.9×S1. According to fluid mechanics theory, the flow rate of the fluid in the pipeline is Q=SV. When the cross-sectional area of ​​the water outlet channel 8 is reduced from S1 to S2, the flow rate of the coolant will increase when it is sprayed from the outlet profile 63, thereby improving the cooling effect. Preferably, S1=0.18mm 2 , S2=0.31mm 2 .

[0046] Further, in this embodiment, the diameter of the inlet profile 62 is set to d1, and the maximum radial dimension L1 of the outlet profile 63 is smaller than d1.

[0047] The maximum radial dimension L1 of the outlet profile 63 of the nozzle 6 is smaller than d1. At this time, the area enclosed by the outlet profile 63 is S2. Obviously, S2 is smaller than the area S1 enclosed by the inlet profile 62. The nozzle 6 is designed to ensure: 0.6×S1≤ S2≤ 0.9×S1. Preferably, L1=0.55mm.

[0048] Furthermore, if Figure 1 and Figure 2 As shown, in this embodiment, the drill tip 2 is provided with a plurality of cutting edges 7 evenly distributed around the axis 1 of the main body 10, and the outlets of each cooling hole 4 are respectively arranged on the flank 5 of each cutting edge 7. Preferably, two cutting edges 7 are provided, and two cooling holes 4 are provided, that is, two flanks 5 and two nozzles 6 are provided accordingly. Preferably, the outer end surface of the nozzle 6 (the end surface facing the outside of the outlet of the cooling hole 4) is flush with the flank 5.

[0049] Furthermore, if Figure 4 As shown, in this embodiment, the outer edge of the outer end of the nozzle 6 forms an outer end profile 61, and the outlet profile 63 is eccentrically arranged relative to the outer end profile 61 and close to the corresponding cutting edge 7. Figure 2As shown, when the nozzle 6 is assembled at the outlet end of the cooling hole 4, the eccentric side of the outlet profile 63 faces the cutting edge 7, so that the direction of the coolant spraying can be closer to the cutting edge 7, and a better cooling effect can be obtained during processing. The geometric center O of the outlet profile 63 of the nozzle 6 does not coincide with the outer end profile 61, and is eccentric toward the cutting edge 7.

[0050] Furthermore, in this embodiment, the length of the nozzle 6 is set to L, and the outer diameter is set to d0, satisfying 2×d0≤ L ≤ 5×d0.

[0051] The length L of the nozzle 6 should be reasonably selected, and L satisfies: 2×d0≤ L ≤ 5×d0. When the cooling hole 4 is a straight hole, L can be a larger value to facilitate repeated grinding of the drill bit; however, when the cooling hole 4 is a double helix structure, the length L of the nozzle 6 should not be too large. This is because the nozzle 6 is cylindrical (straight tube), and although the cooling hole 4 is also close to straight in a shorter length range, it is still a spiral. If the nozzle 6 is too long, it will be difficult to assemble and will also increase the assembly stress. Preferably, L=2.0mm.

[0052] Further, in this embodiment, the cooling hole 4 extends along the axial direction of the drill body 10, specifically, extends in a spiral around the axis 1 of the drill body 10. It should be noted that the cooling hole 4 extends along the axial direction of the drill body 10, which only refers to the axially forward direction, and does not specifically refer to extending in a direction parallel to the axis 1. That is, the cooling hole 4 can extend straight in a direction parallel to the axis 1, or can extend in a spiral around the axis 1 of the drill body 10. Preferably, the internally cooled drill bit is a twist drill bit, and the cooling hole 4 extends in a spiral around the axis 1 of the drill body 10.

[0053] Furthermore, in this embodiment, if Figure 5 As shown, the nozzle 6 is a hollow cylinder, and the outer diameter of the nozzle 6 (the diameter of the outer end profile 61) is equal to the diameter d of the cooling hole 4, so that the nozzle 6 and the cooling hole 4 can be assembled. During assembly, the nozzle 6 and the outlet of the cooling hole 4 are matched with a small interference fit, which can ensure that the nozzle 6 can be firmly fixed in the cooling hole 4. At the same time, the small interference fit can also avoid excessive stress when the nozzle 6 and the cooling hole 4 are assembled. Preferably, in this embodiment, the drill diameter is 6mm. In other embodiments, the nozzle 6 and the outlet of the cooling hole 4 can also be matched with adhesive tape, or interference plus adhesive tape, or other fixed connection matching methods.

[0054] Furthermore, in the present embodiment, a spiral chip removal groove (threadedly arranged around the axis 1 of the drill body 10 ) is provided at the front portion of the drill body 10 , and a shank 3 is provided at the rear portion.

[0055] Embodiment 2:

[0056] Figure 6Another embodiment of the internally cooled drill of the present invention is shown. The structure of the internally cooled drill of this embodiment is basically the same as that of the first embodiment, except that three cooling holes 4 are provided. Accordingly, three cutting edges 7 are provided, and three flank surfaces 5 and nozzles 6 are provided.

[0057] Preferably, in this embodiment, d0= 0.7mm, d1=0.63mm, L1=0.55mm, L=2.0mm, α1=6°, α2=2°, S1=0.18mm 2 , S2=0.31mm 2 .

[0058] Embodiment three:

[0059] Figure 7 The third embodiment of the internally-cooled drill bit of the present invention is shown. The structure of the internally-cooled drill bit of this embodiment is substantially the same as that of the first or second embodiment, with the only difference being that the outlet profile 63 is triangular.

[0060] Furthermore, in this embodiment, the three corners of the outlet profile 63 are all rounded.

[0061] Embodiment 4:

[0062] Figure 8 The fourth embodiment of the internally-cooled drill bit of the present invention is shown. The structure of the internally-cooled drill bit of this embodiment is basically the same as that of the first or second embodiment, with the only difference being that the outlet profile 63 is kidney-shaped, specifically an arc-shaped with rounded corners at both ends.

[0063] Embodiment five:

[0064] Fig. 9 The fifth embodiment of the internally-cooled drill bit of the present invention is shown. The structure of the internally-cooled drill bit of this embodiment is basically the same as that of the first or second embodiment, except that the outlet profile 63 is in the shape of a figure 8, that is, similar to the shape of the number 8. The figure 8 specifically includes two symmetrically arranged arcs, and the two ends of the two arcs are connected by arc lines.

[0065] Embodiment six:

[0066] Fig.10 The sixth embodiment of the internally-cooled drill bit of the present invention is shown. The structure of the internally-cooled drill bit of this embodiment is substantially the same as that of the first or second embodiment, with the only difference being that the outlet profile 63 is trapezoidal.

[0067] Furthermore, in this embodiment, the four corners of the outlet profile 63 are all rounded.

[0068] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. An internally cooled drill, comprising a drill body (10), a drill tip (2) being provided at the front end of the drill body (10), at least two cooling holes (4) extending axially and penetrating to both ends of the drill body (10), the cooling holes (4) being evenly distributed around the axis (1) of the drill body (10), the cooling holes (4) having a circular cross section and an outlet located on the back face (5) of the drill tip (2), characterized in that: The outlet of the cooling hole (4) is provided with a cylindrical nozzle (6), the inner inlet of the nozzle (6) forms an inlet profile (62), and the outer outlet forms an outlet profile (63), the inlet profile (62) is circular, and the outlet profile (63) is non-circular, the outlet profile (63) of the nozzle (6) is a symmetrical structure, the symmetry plane of the outlet profile (63) passes through the center of the outlet profile (63) and the center line (66) of the nozzle (6), the symmetry plane of the outlet profile (63) passes through the axis (1) of the drill bit body (10), a water outlet channel (8) connecting the inlet profile (62) and the outlet profile (63) is formed in the nozzle (6), the center axis of the water outlet channel (8) does not coincide with the center line (66) of the nozzle (6); the inlet profile (62) of the nozzle (6) is concentric with the cooling hole (4); the area enclosed by the inlet profile (62) is S1, and the area enclosed by the outlet profile (63) is S2, satisfying the following conditions: 0.6×S1≤ S2≤ 0.9×S1; the internally cooled drill bit is a twist drill bit, and the cooling hole (4) extends spirally around the axis (1) of the drill bit body (10).

2. The internally cooled drill bit according to claim 1, characterized in that: The water outlet channel (8) forms an upper generatrix (64) and a lower generatrix (65) on a longitudinal section passing through a symmetry plane of the outlet profile (63), wherein an angle between the upper generatrix (64) and a center line (66) of the nozzle (6) is set to α1, and an angle between the lower generatrix (65) and a center line (66) of the nozzle (6) is set to α2, satisfying α1>α2.

3. The internally cooled drill bit according to claim 1, characterized in that: The outlet profile (63) is in the shape of a triangle, an ellipse, a kidney, an 8-shape or a trapezoid.

4. The internally cooled drill bit according to claim 1, characterized in that: The area enclosed by the inlet contour (62) is S1, and the area enclosed by the outlet contour (63) is S2, satisfying 0.6×S1≤ S2≤ 0.9×S1.

5. The internally cooled drill bit according to claim 1, characterized in that: The diameter of the inlet profile (62) is set to d1, and the maximum radial dimension L1 of the outlet profile (63) is smaller than d1.

6. The internally cooled drill according to any one of claims 1 to 5, characterized in that: The drill tip (2) is provided with a plurality of cutting edges (7) evenly distributed around the axis (1) of the main body (10), and the outlets of the cooling holes (4) are respectively arranged on the back surfaces (5) of the cutting edges (7).

7. The internally cooled drill bit according to claim 6, characterized in that: The outer edge of the outer end of the nozzle (6) forms an outer end profile (61), and the outlet profile (63) is eccentrically arranged relative to the outer end profile (61) and close to the corresponding cutting edge (7).

8. The internally cooled drill according to any one of claims 1 to 5, characterized in that: The length of the nozzle (6) is set to L, and the outer diameter is set to d0, satisfying 2×d0≤ L ≤ 5×d0.

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