A milling drill bit

Abstract

The present invention discloses a milling drill bit comprising a cutting portion having a drill tip at the front end and a shank at the rear end. The cutting portion is provided with at least two spiral chip flutes extending from the drill tip to the shank. A blade is formed between adjacent spiral chip flutes on the cutting portion. A plurality of first and second spiral microgrooves are provided on the outer circumferential surface of the blade facing the drill tip. The first spiral microgrooves and the spiral chip flutes have the same spiral direction, while the second spiral microgrooves have an opposite spiral direction. The first and second spiral microgrooves intersect to form a plurality of milling microteeth arranged in a reticular pattern. This milling drill bit has the advantages of improving the suppression of burrs, delamination, and tearing damage at the hole entrance and exit, thereby improving processing quality, efficiency, and service life.

Description

Technical Field

[0001] The invention relates to the technical field of drilling tools, in particular to a milling drill bit. Background Art

[0002] In the machining industry, conventional drill bits used to drill composite materials often exhibit severe burrs, delamination, and tearing at the entrance and exit, particularly at the exit, resulting in hole quality that does not meet production requirements. To address this problem, drill bit structure optimization typically involves grinding chip grooves into the bit's cutting edge, creating a counter-shearing edge on the bit's land to minimize burrs and delamination.

[0003] Chinese patent document with application number 202221697932.2 discloses a twist drill with a micro-tooth structure, which specifically discloses grinding right-handed micro-tooth grooves on the twist drill blade, forming a micro-tooth structure between adjacent micro-tooth grooves, and reducing processing damage in composite material processing through the micro-tooth structure. The main principle of the twist drill with a micro-tooth structure is that the burrs generated during the hole making process can rebound into the micro-tooth structure by designing a micro-tooth structure on the secondary cutting edge and be sheared off by the cutting edge of the micro-tooth, thereby effectively removing the burrs at the exit and entrance and reducing damage to the composite material hole. However, on the one hand, the twist drill with a micro-tooth structure has limited inhibitory effect on burrs, delamination and tearing damage at the exit and entrance of the hole, and the processing quality needs to be improved; on the other hand, the axial force it is subjected to during the processing is large, which not only affects the processing quality and efficiency, but also affects the service life. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a milling drill bit that can improve the suppression of burrs, delamination and tearing damage at the hole entrance and exit, thereby improving processing quality, efficiency and service life.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A milling drill bit includes a cutting portion, wherein the front end of the cutting portion has a drill tip and the rear end is provided with a shank, the cutting portion is provided with at least two spiral chip grooves extending from the drill tip to the shank, the cutting portion forms a blade between adjacent spiral chip grooves, and the outer peripheral surface of the blade facing the drill tip end is provided with a plurality of first spiral microgrooves and second spiral microgrooves, the first spiral microgrooves and the spiral chip grooves have the same spiral direction, the second spiral microgrooves and the spiral chip grooves have an opposite spiral direction, and the first spiral microgrooves and the second spiral microgrooves intersect with each other to form a plurality of milling micro-teeth arranged in a reticular pattern.

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

[0008] The helix angle of the first spiral microgroove is set to β1, and the helix angle of the second spiral microgroove is set to β2, β1 and β2 satisfy: 10°≤|β1|≤40°, 0°<|β2|≤60°, and β1×β2 < 0, β1 and β2 are positive for right-handed rotation and negative for left-handed rotation.

[0009] The maximum depths of the first spiral microgroove and the second spiral microgroove are set to Ld1 and Ld2 respectively, and the diameter of the cutting portion is set to D, which satisfies the following conditions: 0.02D<Ld1<0.15D, 0.02D<Ld2<0.15D.

[0010] The width of the first spiral microgroove is set to Lw1, and the width of the second spiral microgroove is set to Lw2, satisfying: 0.2 mm < Lw1 < 0.8 mm, 0.2 mm < Lw2 < 0.8 mm.

[0011] The milling micro-teeth are arranged in an array along the spiral direction of the first spiral micro-groove and the second spiral micro-groove.

[0012] The length of the milled micro-tooth is set to wl and the width is set to wd, which satisfy the following conditions: 0.02mm<wl<0.7mm, 0.02mm<wd<0.4mm.

[0013] The top surface of the milling micro-tooth intersects with the front side surface of the milling micro-tooth in the spiral direction of the second spiral micro-groove to form a co-rotating blade with the same spiral direction as the first spiral micro-groove, and the top surface of the milling micro-tooth intersects with the front side surface of the milling micro-tooth in the spiral direction of the first spiral micro-groove to form a counter-rotating blade with the same spiral direction as the second spiral micro-groove, the front angle of the co-rotating blade is set to γ1, and the front angle of the counter-rotating blade is set to γ2, satisfying: 3°<γ1<20°, 3°<γ2<20°.

[0014] A cutting edge is provided on the front edge of the blade, and the width of the cutting edge is set to wt, satisfying the following: 0.05D≤wt≤0.15D.

[0015] The helix angle of the spiral chip removal groove 4 is set to β, which satisfies: 0°<|β|≤40°, and |β| ≤ |β1|.

[0016] The first spiral microgroove extends to the drill tip, and the second spiral microgroove extends to the front edge of the land.

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

[0018] The milling drill bit of the present invention has a plurality of milling micro-teeth arranged in an orderly, reticular pattern on the blade. When processing composite materials, after the drill tip cuts into the workpiece, the milling micro-teeth distributed on the outer peripheral surface of the front end of the blade can mill the hole. First, the milling micro-teeth are formed by the intersection of the first spiral micro-groove and the second spiral micro-groove, and can be formed by grinding the first spiral micro-groove and the second spiral micro-groove, making processing convenient. Second, because the first spiral micro-groove and the spiral chip removal groove have the same spiral direction, and the second spiral micro-groove and the spiral chip removal groove have an opposite spiral direction, chip removal is facilitated. Simultaneously, the milling action of the reticular pattern of the milling micro-teeth improves the suppression of burrs, delamination, and tearing damage at the hole entrance and exit, thereby improving processing quality. Third, the grinding action of the milling micro-teeth and the good chip removal action of the first and second spiral micro-grooves reduce the axial force experienced during processing, thereby improving not only processing quality and efficiency but also service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the main structure of the milling drill bit of the present invention.

[0020] Figure 2 It is a schematic diagram of the outer peripheral surface of the milling drill bit of the present invention.

[0021] Figure 3 yes Figure 2 Schematic diagram of the enlarged structure at point A in the middle.

[0022] Figure 4 yes Figure 3 Schematic diagram of the cross-sectional structure of the middle BB, with the BB parallel to the front edge of the blade.

[0023] Figure 5 yes Figure 3 Schematic diagram of the cross-sectional structure of the CC, where the CC is perpendicular to the anterior edge of the blade.

[0024] Figure 6 yes Figure 2 Schematic diagram of the cross-sectional structure of the EE, where the EE is parallel to the front edge of the blade.

[0025] Figure 7 yes Figure 2 Schematic diagram of the cross-sectional structure of the FF, where the FF is perpendicular to the front edge of the blade.

[0026] Figure 8 The hole exit quality comparison between this embodiment and conventional twist drill at V=60m / min is shown in FIG. Figure 8 (a) Figure 8 (b) Figure 8 (c) Figure 8(d) is the embodiment of this invention, and the feed per revolution is fr=0.02mm, fr=0.05mm, fr=0.08mm, fr=0.11mm respectively. Figure 8 (e) Figure 8 (f) Figure 8 (g) Figure 8 (h) is a conventional twist drill with feed per revolution of fr=0.02mm, fr=0.05mm, fr=0.08mm, and fr=0.11mm respectively.

[0027] Figure 9 The hole exit quality comparison between this embodiment and conventional twist drill at V=90m / min is shown in FIG. Figure 9 (a) Figure 9 (b) Figure 9 (c) Figure 9 (d) is the embodiment of this invention, and the feed per revolution is fr=0.02mm, fr=0.05mm, fr=0.08mm, fr=0.11mm respectively. Figure 9 (e) Figure 9 (f) Figure 9 (g) Figure 9 (h) is a conventional twist drill with feed per revolution of fr=0.02mm, fr=0.05mm, fr=0.08mm, and fr=0.11mm respectively.

[0028] Figure 10 The hole exit quality comparison between this embodiment and conventional twist drill at V=120m / min is shown in FIG. Figure 10 (a) Figure 10 (b) Figure 10 (c) Figure 10 (d) is the embodiment of this invention, and the feed per revolution is fr=0.02mm, fr=0.05mm, fr=0.08mm, fr=0.11mm respectively. Figure 10 (e) Figure 10 (f) Figure 10 (g) Figure 10 (h) is a conventional twist drill with feed per revolution of fr=0.02mm, fr=0.05mm, fr=0.08mm, and fr=0.11mm respectively.

[0029] The numbers in the figure represent:

[0030] 1. Cutting part; 2. Drill tip; 3. Shank; 4. Spiral chip groove; 5. Blade; 6. First spiral micro groove; 7. Second spiral micro groove; 8. Milling micro teeth; 81. Co-rotating blade; 82. Counter-rotating blade; 9. Margin. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] 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", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship 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 cannot be understood as limiting the present invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0034] In the present invention, unless otherwise expressly specified or limited, terms such as "assemble," "connect," "connect," and "fix" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0035] Figures 1 to 7 An embodiment of the milling drill bit of the present invention is shown. The milling drill bit of this embodiment includes a cutting part 1, the front end of the cutting part 1 is provided with a drill tip 2, and the rear end is provided with a shank 3. The cutting part 1 is provided with at least two spiral chip grooves 4 extending from the drill tip 2 to the shank 3. The cutting part 1 forms a blade 5 between adjacent spiral chip grooves 4. A plurality of first spiral microgrooves 6 and second spiral microgrooves 7 are provided on the outer peripheral surface of the blade 5 facing the end of the drill tip 2. The first spiral microgrooves 6 and the spiral chip grooves 4 have the same spiral direction, and the second spiral microgrooves 7 and the spiral chip grooves 4 have an opposite spiral direction. The first spiral microgrooves 6 and the second spiral microgrooves 7 intersect with each other to form a plurality of milling micro-teeth 8 arranged in a reticular pattern.

[0036] This milling drill bit has a plurality of milling micro-teeth 8 arranged in an orderly grid pattern on the blade 5. When processing composite materials, after the drill tip 2 cuts into the workpiece, the milling micro-teeth 8 distributed on the outer peripheral surface of the front end of the blade 5 (the end facing the drill tip 2) can mill the hole. On the one hand, the milling micro-teeth 8 are formed by the mutual intersection of the first spiral micro-grooves 6 and the second spiral micro-grooves 7, and can be formed by grinding the first spiral micro-grooves 6 and the second spiral micro-grooves 7, which is convenient for processing; on the other hand, since the spiral direction of the first spiral micro-grooves 6 is the same as that of the spiral chip groove 4, and the spiral direction of the second spiral micro-grooves 7 is opposite to that of the spiral chip groove 4, it is convenient for chip removal. At the same time, under the milling action of the reticulated milling micro-teeth 8, the burr, delamination and tearing damage at the hole entrance and exit are inhibited, thereby improving the processing quality; on the third hand, under the grinding action of the milling micro-teeth 8 and the good chip removal action of the first spiral micro-grooves 6 and the second spiral micro-grooves 7, the axial force suffered during the processing is reduced, which not only improves the processing quality and efficiency, but also improves the service life.

[0037] Furthermore, if Figure 2 As shown, in this embodiment, Figure 2 As shown, the helix angle of the first spiral microgroove 6 is set to β1, and the helix angle of the second spiral microgroove 7 is set to β2. β1 and β2 satisfy the following conditions: 10° ≤ |β1| ≤ 40°, 0° < |β2| ≤ 60°, and β1 × β2 < 0. Positive values ​​for β1 and β2 indicate right-handedness, while negative values ​​indicate left-handedness. While ensuring the parameters for milling micro-teeth 8, to minimize the number of first spiral microgrooves 6 ground, β1 can be set equal to the helix angle of the spiral chip flute 4. When grinding the second spiral microgroove 7, the value of β2 affects the effective length of the counter-rotating cutting edge 82 participating in the cutting process. When β2 = 90°, the counter-rotating cutting edge 82 does not participate in the cutting process. Therefore, to ensure that the counter-rotating cutting edge 82 can effectively participate in the cutting process, an appropriate value of β2 should be selected. In this embodiment, 0° < |β2| ≤ 60° ensures that the counter-rotating cutting edge 82 has an optimal effective length for participating in the cutting process, meeting the requirement that the counter-rotating cutting edge 82 can effectively participate in the cutting process. Preferably, β1=30° and β2=-30°.

[0038] The helix angle of the first spiral microgroove 6 is the angle between the spiral direction of the first spiral microgroove 6 and the central axis of the cutting portion 1. The helix angle of the second spiral microgroove 7 is the angle between the spiral direction of the second spiral microgroove 7 and the central axis of the cutting portion 1.

[0039] Furthermore, in this embodiment, if Figure 6 and Figure 7As shown, the maximum depths of the first and second spiral microgrooves 6, 7 are set to Ld1 and Ld2, respectively, and the diameter of the cutting portion 1 is set to D (nominal diameter), satisfying the following: 0.02D < Ld1 < 0.15D, and 0.02D < Ld2 < 0.15D. The greater the depths Ld1 and Ld2, the lower the strength of the milled micro-tooth 8. If Ld1 and Ld2 are too small, chip separation and evacuation are poor. Therefore, the values ​​of 0.02D < Ld1 < 0.15D and 0.02D < Ld2 < 0.15D meet the strength requirements of the milled micro-tooth 8 while ensuring excellent chip separation and evacuation for the first and second spiral microgrooves 6, 7. Furthermore, the appropriate values ​​of Ld1 and Ld2 should be selected based on the diameter D of the cutting portion 1. Preferably, D = 6 mm, Ld1 = 0.52 mm, and Ld2 = 0.39 mm.

[0040] Furthermore, in this embodiment, the width of the first spiral microgroove 6 is set to Lw1, and the width of the second spiral microgroove 7 is set to Lw2, satisfying: 0.2mm<Lw1<0.8mm, 0.2mm<Lw2<0.8mm. Preferably, Lw1=0.49mm, Lw2=0.51mm.

[0041] Furthermore, in this embodiment, the milling micro-teeth 8 are arranged in an array along the spiral direction of the first spiral micro-grooves 6 and the second spiral micro-grooves 7. It can also be understood that the first spiral micro-grooves 6 are evenly spaced along the spiral direction of the second spiral micro-grooves 7, and the second spiral micro-grooves 7 are evenly spaced along the spiral direction of the first spiral micro-grooves 6.

[0042] Furthermore, in this embodiment, if Figure 3 As shown, the length of the milling micro-tooth 8 is set to wl and the width is set to wd, satisfying the following: 0.02mm<wl<0.7mm, 0.02mm<wd<0.4mm. The length of the milling micro-tooth 8 is the length in the spiral direction of the first spiral micro-groove 6, and the width of the milling micro-tooth 8 is the length in the spiral direction of the second spiral micro-groove 7.

[0043] If wd is too large, the friction during drilling will be large, which is not conducive to drilling processing. If wd is too small, the strength of the milling micro-tooth 8 will be insufficient, and the milling micro-tooth 8 will be chipped during processing. If the wl value is too large and the sharpness is insufficient, it will be difficult for the array-arranged milling micro-tooth 8 to form a milling effect, reduce the cutting force, and suppress burrs, delamination, and tearing. If the wl value is too small, the strength of the milling micro-tooth 8 will be reduced. Therefore, when 0.02mm<wl<0.7mm and 0.02mm<wd<0.4mm, the chipping phenomenon of the milling micro-tooth 8 during processing can be avoided, and the milling micro-tooth 8 has good sharpness and strength, and has a good effect of suppressing burrs, delamination, and tearing. Preferably, wl=0.35mm and wd=0.15mm.

[0044] Further explanation is as follows: The width wd of the milling micro-tooth 8 has a great influence on the performance of processing composite materials. In order to ensure the size of the width wd, reduce the processing steps and reduce the grinding cost, one solution is to indirectly control the width wd of the milling micro-tooth 8 by reasonably setting the width Lw1 of the first spiral micro-groove 6. However, this solution will lead to insufficient strength of the milling micro-tooth 8, and when facing a workpiece with higher strength, there is a risk of chipping. Another improvement solution is to design a smaller Lw1, but add a back cutting edge with a certain back angle behind the co-rotating edge 81 of the milling micro-tooth 8, so as to achieve the control of the appropriate width wd of the milling micro-tooth 8.

[0045] Furthermore, in this embodiment, if Figure 4 and Figure 5 As shown, the top surface of the milling micro-tooth 8 intersects with the front side surface of the milling micro-tooth 8 in the spiral direction of the second spiral micro-groove 7 to form a co-rotating blade 81 with the same spiral direction as the first spiral micro-groove 6. The top surface of the milling micro-tooth 8 intersects with the front side surface of the milling micro-tooth 8 in the spiral direction of the first spiral micro-groove 6 to form a counter-rotating blade 82 with the same spiral direction as the second spiral micro-groove 7. The rake angle of the co-rotating blade 81 is set to γ1, and the rake angle of the counter-rotating blade 82 is set to γ2, satisfying the following: 3°<γ1<20°, 3°<γ2<20°. It can be understood that: the top surface of the milling micro-tooth 8 is the surface of the milling micro-tooth 8 located on the outer peripheral surface of the blade 5, the front side surface of the milling micro-tooth 8 in the spiral direction of the second spiral micro-groove 7 is the intersection surface of the milling micro-tooth 8 and the corresponding first spiral micro-groove 6, and the front side surface of the milling micro-tooth 8 in the spiral direction of the first spiral micro-groove 6 is the intersection surface of the milling micro-tooth 8 and the corresponding second spiral micro-groove 7.

[0046] During drilling, both the co-rotating cutting edge 81 and the counter-rotating cutting edge 82 of the milling micro-tooth 8 participate in the cutting process. To reduce cutting forces, the rake angles of the co-rotating cutting edge 81 and the counter-rotating cutting edge 82 should be set to be greater than zero. To ensure smooth cutting, γ1 and γ2 should satisfy the following conditions: 3° < γ1 < 20°, and 3° < γ2 < 20°. Optimally, γ1 = 5° and γ2 = 5°.

[0047] Furthermore, in this embodiment, if Figure 2 As shown, the front edge of the blade 5 is provided with a blade band 9, and the width of the blade band 9 is set to wt, satisfying the following: 0.05D≤wt≤0.15D. The blade band 9 mainly plays a guiding role. If the width wt of the blade band 9 is set to be larger, the friction force will increase. Therefore, the blade band 9 should take an appropriate value according to the actual situation. When 0.05D≤wt≤0.15D, the blade band 9 has a good guiding effect and does not cause a lot of friction. Here, D is the diameter of the cutting part 1. Preferably, wt=0.083mm and D=0.5mm.

[0048] Furthermore, in this embodiment, if Figure 1As shown, the helix angle of the spiral chip flute 4 is set to β, satisfying: 0°<|β|≤40°, and |β| ≤ |β1|. When processing composite materials, if the helix angle β is set larger, the axial force during processing is larger, which will cause burrs, delamination, and tearing damage at the entrance of the processed hole. If the helix angle β is set smaller, the sharpness of the milling micro-tooth 8 is insufficient, which is not conducive to suppressing processing burrs, delamination, and tearing damage. Therefore, β should be set to an appropriate value according to actual processing to meet processing requirements. In this embodiment, 0°<|β|≤40° can not only reduce the axial force during processing, but also improve the sharpness of the milling micro-tooth 8, avoiding burrs, delamination, and tearing damage at the entrance of the processed hole. β=30° is preferred.

[0049] Furthermore, in this embodiment, the first spiral micro groove 6 extends to the drill tip 2, and the second spiral micro groove 7 extends to the front edge of the land 9. Figure 1 Rotate in the T direction shown in .

[0050] The following are comparative experimental results using the milling drill bit of this embodiment and a conventional twist drill to produce holes in T800 carbon fiber composite materials. The two drill bits used in the experiment had identical drill tip 2 structures and design parameters. The only difference was that the milling drill bit of this embodiment had the following structure: the outer circumferential surface of the blade 5 facing the end of the drill tip 2 was provided with a plurality of first spiral microgrooves 6 and second spiral microgrooves 7. The first spiral microgrooves 6 and the spiral chip flutes 4 had the same spiral direction, while the second spiral microgrooves 7 had the opposite spiral direction. The first spiral microgrooves 6 and the second spiral microgrooves 7 intersected to form a plurality of milling microteeth 8 arranged in a reticular pattern. The comparative experiments revealed that the exit quality of the holes produced in carbon fiber composite materials using the milling drill bit of this embodiment was significantly superior to those produced using a conventional twist drill.

[0051] Table 1 Figure 8 、 Figure 9 and Figure 10 Comparison of the exit quality differences of the holes produced by the milling drill bit of this embodiment and the conventional twist drill in processing composite materials under different processing parameters. Figure 8 、 Figure 9 and Figure 10 It can be seen that when the online speeds are V=60m / min, V=90m / min, and V=120m / min, and the feed per revolution is fr=0.02mm, fr=0.05mm, fr=0.08mm, and fr=0.11mm, respectively, the burrs, delamination, and fiber tearing at the outlet of the holes processed by the milling drill bit of the present embodiment are very slight, and the hole quality is significantly better than that of the holes processed by the conventional twist drill, which proves that the milling drill bit of the present embodiment has a significant advantage in inhibiting burrs, delamination, and tearing damage at the hole outlet when processing carbon fiber composite materials.

[0052] Table 1 Comparison of hole exit quality between this embodiment and conventional twist drill under different parameter conditions

[0053]

[0054] Although the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, utilize the technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A milling drill bit, comprising a cutting portion (1), wherein the front end of the cutting portion (1) has a drill tip (2) and the rear end is provided with a shank (3), the cutting portion (1) is provided with at least two spiral chip flutes (4) extending from the drill tip (2) to the shank (3), the cutting portion (1) forming a cutting edge (5) between adjacent spiral chip flutes (4), and characterized in that: A plurality of first spiral microgrooves (6) and second spiral microgrooves (7) are provided on the outer peripheral surface of the blade (5) facing one end of the drill tip (2), wherein the spiral direction of the first spiral microgrooves (6) is the same as that of the spiral chip removal groove (4), and the spiral direction of the second spiral microgrooves (7) is opposite to that of the spiral chip removal groove (4), and the first spiral microgrooves (6) and the second spiral microgrooves (7) intersect with each other to form a plurality of milling microteeth (8) arranged in a reticular pattern; the spiral angle of the first spiral microgrooves (6) is set to β1, and the spiral angle of the second spiral microgrooves (7) is set to β2, and β1 and β2 satisfy the following conditions: 10°≤|β1|≤40°, 0°<|β2|≤60°, and β1×β2< 0, β1 and β2 are positive for right-handed rotation and negative for left-handed rotation; the top surface of the milling micro-tooth (8) intersects with the front side surface of the milling micro-tooth (8) in the spiral direction of the second spiral micro-groove (7) to form a same-handed cutting edge (81) in the same spiral direction as the first spiral micro-groove (6); the top surface of the milling micro-tooth (8) intersects with the front side surface of the milling micro-tooth (8) in the spiral direction of the first spiral micro-groove (6) to form a counter-handed cutting edge (82) in the same spiral direction as the second spiral micro-groove (7).

2. The milling drill bit according to claim 1, characterized in that: The maximum depths of the first spiral microgroove (6) and the second spiral microgroove (7) are set to Ld1 and Ld2 respectively, and the diameter of the cutting portion (1) is set to D, satisfying the following: 0.02D<Ld1<0.15D, 0.02D<Ld2<0.15D.

3. The milling drill bit according to claim 1, characterized in that: The width of the first spiral microgroove (6) is set to Lw1, and the width of the second spiral microgroove (7) is set to Lw2, satisfying the following conditions: 0.2 mm < Lw1 < 0.8 mm, 0.2 mm < Lw2 < 0.8 mm.

4. The milling drill bit according to claim 1, characterized in that: The milling micro-teeth (8) are arranged in an array along the spiral direction of the first spiral micro-groove (6) and the second spiral micro-groove (7).

5. The milling drill bit according to any one of claims 1 to 4, characterized in that: The length of the milled micro-tooth (8) is set to wl, and the width is set to wd, satisfying the following: 0.02mm<wl<0.7mm, 0.02mm<wd<0.4mm.

6. The milling drill bit according to any one of claims 1 to 4, characterized in that: The front angle of the same-rotation blade (81) is set to γ1, and the front angle of the counter-rotation blade (82) is set to γ2, satisfying: 3°<γ1<20°, 3°<γ2<20°.

7. The milling drill bit according to any one of claims 1 to 4, characterized in that: A cutting edge (9) is provided on the front edge of the cutting edge (5), and the width of the cutting edge (9) is set to wt, satisfying the following: 0.05D≤wt≤0.15D.

8. The milling drill bit according to any one of claims 1 to 4, characterized in that: The helix angle of the spiral chip removal groove (4) is set to β, which satisfies: 0°<|β|≤40°, and |β| ≤ |β1|.

9. The milling drill bit according to any one of claims 1 to 4, characterized in that: The first spiral microgroove (6) extends to the drill tip (2), and the second spiral microgroove (7) extends to the front edge of the edge band (9).

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