Indexable blade and drill bit

Abstract

The utility model belongs to the technical field of cutters, and discloses an indexable blade and a drill bit, during drilling, cuttings are curled and shrunk into a cone, and when the edge shape of a cutting edge in the Z direction is a downwards concave arc line, the cutting generatrix of the cone is in a corresponding convex arc shape, so that the volume of the cutting vertex of the cone is increased, and the cutting efficiency is improved. And the possibility of chip extrusion at the position is reduced, chip extrusion and chip blockage are avoided, and the probability of tipping of the inner blade is reduced. The point M is closer to the outermost point of the cutting edge, in the process that the point M on the cutting edge transits to the outermost point on the cutting edge, the height of the cutting edge rises faster, cuttings have a certain shrinkage trend when transiting from the highest point of the edge projection to the circular ring at the bottom of the cone, and when the circular ring at the bottom of the cone cuttings collides with a hole wall or a cutter bar, the cutting edge is not prone to falling off. The bottom circular ring with sharp burrs directly collides with the arc-shaped side face, close to the bottom, of the edge projection to become a cutting cone with a certain shrinkage trend, and the hole wall quality can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of cutting tools, in particular to an indexable cutting blade and a drill bit. Background Art

[0002] For drilling processing, chip forming and discharge are crucial. The drill bit has an inner blade and an outer blade. The inner blade has problems such as low processing speed, high cutting force, and difficulty in chip curling. In addition, during the drilling process, the inner blade is more sensitive to chip squeezing and chip blockage. If the chip curling is not smooth, the inner blade chips are squeezed and blocked, the inner blade will easily break. Utility Model Content

[0003] The utility model aims to provide an indexable insert and a drill bit, which can improve the processing conditions of drilling the inner insert and increase the effective processing range and service life of the indexable insert.

[0004] To achieve this purpose, the utility model adopts the following technical solutions:

[0005] An indexable insert comprises an insert body provided with a center hole, the insert body comprising a top surface and a bottom surface arranged opposite to each other in the Z direction, and four circumferential side surfaces arranged opposite to each other in the X direction and the Y direction and connected end to end, the X direction, the Y direction and the Z direction are perpendicular to each other, and a cutting edge is formed at the top surface and each of the circumferential side surfaces;

[0006] The projection of the cutting edge in the first preset plane is the edge projection, and in the direction from the two end points of the edge projection to the center, the edge projection is concave toward the side where the bottom surface is located; the central axis of the center hole is located in the first preset plane, and the first preset plane is parallel to the distribution direction of the two circumferential side surfaces respectively connecting the two ends of the length direction of the cutting edge;

[0007] The point where the distance between the blade projection and the bottom surface along the Z direction is the smallest is point M, the blade projection includes a first projection and a second projection respectively located on both sides of point M, the first projection and the second projection are both arcs and smoothly connected, and the first projection is closer to the drill center than the second projection;

[0008] The first projection is closer to the central axis of the drill bit than the second projection, the curvature radius of the first projection is R1, the curvature radius of the second projection is R2, and 20mm>R1≥R2>0.

[0009] As an implementation scheme of the above-mentioned inner drilling blade, the cutting edge includes an inner cutting edge and an outer cutting edge respectively located on both sides of a second preset plane, the inner cutting edge is closer to the drill center than the outer cutting edge, the second preset plane is perpendicular to the first preset plane and the central axis of the center hole is located in the second preset plane;

[0010] Along the direction from the inner cutting edge to the first preset plane, the inner cutting edge extends toward the side where the bottom surface is located to form a rake face;

[0011] The front cutting edge is connected to the second preset plane and the circumferential edge of the center hole through a connecting surface, and the connecting surface is not higher than the front cutting edge.

[0012] As an implementation scheme of the above-mentioned inner drilling insert, the blade width of the inner cutting edge is L, 0mm<L≤0.2mm.

[0013] As an implementation scheme of the above-mentioned inner drilling insert, the angle between the inner cutting edge and the bottom surface is α, -15°≤α≤15°.

[0014] As an implementation scheme for the above-mentioned inner drilling blade, the cross-section of the front cutting surface is a straight line segment, and the angle between the straight line segment and the bottom surface is β, 10°≤β≤30°, and the cross-section of the front cutting surface is parallel to the second preset plane, or is located in the second preset plane.

[0015] As an implementation scheme of the above-mentioned inner drilling blade, the cutting edge is connected to the circumferential side surface through a flank surface, and the angle between the flank surface and the central axis of the center hole is γ, 3°≤γ≤15°.

[0016] As an implementation scheme for the above-mentioned inner drilling blade, the point where the projection of the blade is spaced the largest from the bottom surface along the Z direction is point N, and the distance between point M and point N along the direction perpendicular to the bottom surface is H, 0.1mm≤H≤2mm.

[0017] As an implementation scheme of the above-mentioned inner drilling blade, the distances between the two end points of the blade projection and the bottom surface along the Z direction are both H, and the line connecting the two end points of the blade projection is parallel to the bottom surface.

[0018] As an implementation scheme of the above-mentioned inner drilling blade, the M point is the midpoint of the cutting edge along its own extension direction, or the midpoint of the cutting edge along its own extension direction is closer to the drill center than the M point.

[0019] As a possible implementation scheme of the above-mentioned inner drilling insert, the four cutting edges are evenly distributed around the circumference of the center hole.

[0020] In order to achieve the above-mentioned purpose, the utility model also provides a drill bit, including a tool rod, and an inner blade and an outer blade installed on the same end of the tool rod, along the radial direction of the tool rod, the inner blade is closer to the central axis of the tool rod than the outer blade, and the inner blade is the above-mentioned indexable blade.

[0021] The beneficial effects of the utility model: the indexable insert and drill bit provided by the utility model, during drilling processing, the chips curl and shrink into a cone shape, and the shape of the generatrix at the outermost end of the cone is directly determined by the blade shape of the cutting edge in the Z direction. When the blade shape of the cutting edge in the Z direction is a downwardly concave arc, the generatrix of the corresponding cone chip is a corresponding convex arc shape, which increases the volume of the cone chip vertex and reduces the possibility of chip extrusion at this location, avoiding chip squeezing and chip blockage, thereby reducing the probability of chip chipping of the inner blade.

[0022] The first projection is closer to the central axis of the drill bit than the second projection. The radius of curvature of the first projection is R1, and the radius of curvature of the second projection is R2. 20mm>R1≥R2>0, which can make point M closer to the outermost point of the cutting edge. In the process of transition from point M on the cutting edge to the outermost point on the cutting edge, the height of the cutting edge rises faster, resulting in a certain shrinkage trend when the highest point of the blade projection on the corresponding chip cone transitions to the bottom ring of the cone. When the bottom ring of the conical chip collides with the hole wall or the tool rod, the bottom ring with sharp burrs directly collides with the arc-shaped side of the blade projection close to the bottom, and becomes a chip cone showing a certain shrinkage trend, which can effectively improve the quality of the hole wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a partial structural schematic diagram of a drill bit provided by an embodiment of the utility model;

[0024] Figure 2 It is a schematic diagram of the structure of the indexable insert provided by the embodiment of the utility model;

[0025] Figure 3 It is a schematic diagram of the chip removal amount of the cutting edge at different positions when the indexable insert provided by the embodiment of the utility model is cutting;

[0026] Figure 4 This is the ideal curling shape of the chips provided by the embodiment of the utility model;

[0027] Figure 5 It is a cross-sectional view of the cutting edge of the indexable insert provided in the embodiment of the utility model;

[0028] Figure 6 It is a schematic diagram showing the influence of the Z-direction cutting edge shape on the generatrix shape of the conical chip when the indexable insert provided by the embodiment of the utility model is cutting;

[0029] Figure 7 It is a side view of the indexable insert provided by the embodiment of the utility model.

[0030] In the figure:

[0031] 100, tool bar; 200, inner blade; 300, outer blade; 400, generatrix; 500, chips; 600, core drilling;

[0032] 1. insert body; 11. center hole; 12. bottom surface; 13. circumferential side surface; 14. cutting edge; 141. inner cutting edge; 142. outer cutting edge; 15. rake face; 16. flank face; 17. first surface; 18. second surface; 191. first projection; 192. second projection;

[0033] 10. First preset plane; 20. Second preset plane. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0035] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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.

[0036] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0037] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0038] like Figures 1 to 3 As shown, an embodiment of the utility model provides an indexable insert and a drill bit, the drill bit includes a tool rod 100, an inner blade 200 and an outer blade 300, the inner blade 200 and the outer blade 300 are installed at the same end of the tool rod 100, along the radial direction of the tool rod 100, the inner blade 200 is closer to the central axis of the tool rod 100 than the outer blade 300, wherein the inner blade 200 is the above-mentioned indexable insert.

[0039] The indexable insert includes an insert body 1 having a center hole 11, and the insert body 1 includes a top surface and a bottom surface 12 arranged opposite to each other along the Z direction, and four circumferential side surfaces 13 arranged opposite to each other in pairs and connected end to end. Specifically, two circumferential side surfaces 13 are arranged opposite to each other in pairs along the X direction, and the other two circumferential side surfaces 13 are arranged opposite to each other in pairs along the Y direction, and the X direction, the Y direction and the Z direction are perpendicular to each other.

[0040] The indexable insert is roughly square when viewed from the top surface to the bottom surface 12 of the indexable insert, but not strictly square. When installing the indexable insert, a screw is threadedly connected through the center hole 11 and the mounting hole on the arbor 100 to fix the indexable insert on the arbor 100.

[0041] The top surface and each circumferential side surface 13 are connected to form a cutting edge 14, that is, the indexable insert has four cutting edges 14, and any two adjacent cutting edges 14 are smoothly connected with rounded corners. The four cutting edges 14 are evenly distributed around the central axis of the center hole 11, so that the four cutting edges 14 are equivalent to each other. After one cutting edge 14 is worn, the indexable insert can be rotated 90° and then installed on the tool rod 100, and an adjacent cutting edge 14 can be used to replace the worn cutting edge 14 to improve economy.

[0042] Since the four cutting edges 14 are equivalent cutting edges, after the indexable insert is fixed to the tool holder 100, only one cutting edge 14 is effective. Figure 2 As shown, the indexable insert is specifically introduced by taking one of the two cutting edges 14 distributed along the X direction as the cutting edge 14 that performs cutting function as an example.

[0043] The cutting edge 14 has two edge ends at both ends of its extension direction, wherein the cutting edge 14 between one edge end and the second preset plane 20 is an inner cutting edge 141, and the cutting edge 14 between the other edge end and the second preset plane 20 is an outer cutting edge 142. After the indexable insert is fixed to the tool bar 100, the inner cutting edge 141 is closer to the central axis of the tool bar 100 than the outer cutting edge 142. The second preset plane 20 is parallel to the central axis of the drill bit and the central axis of the center hole 11 is located in the second preset plane 20.

[0044] Along the direction from the inner cutting edge 141 to the first preset plane 10, the inner cutting edge 141 extends to the side where the bottom surface 12 is located to form a rake face 15; the rake face 15 is connected to the second preset plane 20 and the circumferential edge of the center hole 11 through a connecting surface, and the connecting surface is not higher than the rake face 15. The second preset plane 20 is perpendicular to the first preset plane 10, and the intersection line of the second preset plane 20 and the first preset plane 10 forms the central axis of the center hole 11. The first preset plane 10 is parallel to the distribution direction of the two circumferential side surfaces 13 respectively connecting the two ends of the length direction of the cutting edge 14.

[0045] Exemplarily, the connecting surface includes a first surface 17 and a second surface 18, wherein the edge of one side of the rake face 15 away from the cutting edge 14 is smoothly connected to the edge of one side of the first surface 17 through a rounded corner, and the other side edge of the first surface 17 is smoothly connected to the second surface 18. It should be noted that the rake face 15 can be an inclined plane, a curved surface, or a plane perpendicular to the central axis of the tool bar 100; the first surface 17 can be an inclined plane, a curved surface, or a plane perpendicular to the central axis of the tool bar 100; the second surface 18 is a plane perpendicular to the central axis of the tool bar 100. During drilling, the rake face 15 guides the cutting flow, and the outflowing cutting curls and shrinks after hitting the first surface 17.

[0046] During drilling, the chips 500 of the inner blade 200 are a circle centered on the drill center 600 (eg Figure 4 ), the cutting area of ​​the cutting edge 14 at a distance from the drill center 600L is π*(L+ζ)2-π*L2=2πLζ+πζ2, where ζ is close to 0. The closer to the drill center 600, the smaller the amount of chips 500, and the farther away from the drill center 600, the larger the amount of chips 500. Under the bending of the material itself due to the inconsistent linear speed of the inside and outside of the chips 500, it finally curls into a cone (such as Figure 5 ), the apex of the cone is the drill core 600. Since the chips 500 themselves have thickness, the chips 500 at the apex of the cone are easily squeezed against each other, which makes it difficult for the chips 500 to curl and grow normally. Therefore, it is necessary to ease the curling of the chips 500 near the drill core 600, give the chips 500 avoidance space, and increase the curling curvature radius of the chips 500 near the drill core 600 as much as possible.

[0047] The front cutting face 15 is formed by extending the inner cutting edge 141 toward the side where the bottom surface 12 is located. The front cutting face 15 is connected to the second preset plane 20 and the circumferential edge of the center hole 11 through a connecting surface, and the connecting surface is not higher than the front cutting face 15, so that the surface between the inner cutting edge 141 near the drill core 600 and the center hole 11 is not higher than the cutting edge 14, and the position near the drill core 600 is given more avoidance space for the chips 500 as much as possible, thereby reducing the extrusion of the chips 500 at the drill core 600 due to collision, so that the chips 500 are curled into stable, long chips with fixed pitch under the combined effect of natural curling caused by inconsistent linear speeds inside and outside the chips 500 and curling caused by inconsistent cutting amounts at various points on the cutting edge 14, and then break under centrifugal force and the collision between the chips 500 and the tool rod 100 without causing abnormal extrusion and deformation of the chips 500, thereby avoiding chip squeezing and chip blockage of the chips 500, thereby reducing the probability of chip chipping of the inner blade 200.

[0048] In some embodiments, Figure 6 As shown, the blade width of the inner cutting edge 141 is L, 0mm<L≤0.2mm. Specifically, L is the length of the inner cutting edge 141 in a cross section parallel to the second preset plane 20 along a preset direction (X direction), and the preset direction is parallel to the first preset parallel and perpendicular to the central axis of the center hole 11. L can be selected from any one of greater than 0mm and less than or equal to 0.2mm, such as L can be selected from any one of 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, and 0.2mm.

[0049] In some embodiments, Figure 6 As shown, the angle between the inner cutting edge 141 and the bottom surface 12 is α, -15°≤α≤15°. α can be selected from any angle value greater than or equal to -15° and less than or equal to 15°, such as α can be selected from any angle value of -15°, -14°, -13°, -12°, -11°, -10°, -9°, -8°, -7°, -6°, -5°, -4°, -3°, -2°, -1°, 0°, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 13°.

[0050] In some embodiments, the cross section of the rake face 15 is a straight line segment, and the angle between the straight line segment and the bottom surface 12 is β, 10°≤β≤30°, and the cross section of the rake face 15 is parallel to the second preset plane 20, or is located on the second preset plane 20. β can select any angle value greater than or equal to 10° and less than or equal to 30°, such as α can select any angle value of 10°, 15°, 20°, 25°, and 30°.

[0051] In some embodiments, Figure 6 As shown, the cutting edge 14 is connected to the circumferential side surface 13 through the back face 16, and the angle between the back face 16 and the central axis of the central hole 11 is γ, 3°≤γ≤15°. γ can be selected from any angle value greater than or equal to 3° and less than or equal to 15°, such as γ can be selected from any angle value of 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 13°, 14°, and 15°.

[0052] In some embodiments, Figure 6 and Figure 7 As shown, the projection of the cutting edge 14 in the first preset plane 10 is the edge projection, and in the direction from the two end points of the edge projection to the center, the edge projection is concave toward the side where the bottom surface 12 is located.

[0053] Exemplarily, the point where the distance between the blade projection and the bottom surface 12 along the Z direction is the smallest is point M. The blade projection includes a first projection 191 and a second projection 192 located on both sides of point M, respectively. The first projection 191 and the second projection 192 are both arcs and smoothly connected.

[0054] During drilling, the chip 500 curls and shrinks into a cone, and the shape of the generatrix 400 at the outermost end of the cone is directly determined by the edge shape of the cutting edge 14 in the Z direction (e.g. Figure 6 ), when the cutting edge 14 in the Z direction is a downwardly concave arc, the generatrix 400 of the corresponding conical chip 500 is a corresponding convex arc shape, which increases the volume of the top of the conical chip 500 and reduces the possibility of chip 500 extrusion at this location.

[0055] In some embodiments, Figure 7 As shown, the first projection 191 is closer to the central axis of the drill bit than the second projection 192 , the curvature radius of the first projection 191 is R1 , the curvature radius of the second projection 192 is R2 , and 20 mm>R1≥R2>0.

[0056] Such an arrangement makes point M closer to the outermost point of the cutting edge 14 (the bottom ring of the chip 500 cone). In the process of transition from point M on the cutting edge 14 to the outermost point on the cutting edge 14, the height of the cutting edge 14 rises faster, resulting in a certain shrinkage trend when the highest point of the blade projection on the corresponding chip 500 cone transitions to the bottom ring of the cone. When the bottom ring of the conical chip 500 collides with the hole wall or the tool rod 100, the bottom ring with sharp burrs directly collides with the arc-shaped side of the blade projection close to the bottom, and becomes a chip 500 cone showing a certain shrinkage trend, which can effectively improve the quality of the hole wall, and the curvature radius of the bottom ring of the conical chip 500 will not be too large when the chip 500 curls.

[0057] In some embodiments, Figure 7 As shown, the point where the blade projection is the largest distance from the bottom surface 12 is point N, and the distance between point M and point N along the direction perpendicular to the bottom surface 12 is H, 0.1mm≤H≤2mm.

[0058] H can select any value greater than or equal to 0.1mm and less than or equal to 2mm, such as H can select any one of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, and 2mm.

[0059] In some embodiments, Figure 7 As shown, the distance between the two end points of the blade projection and the bottom surface 12 along the Z direction is H, and the line connecting the two end points of the blade projection is parallel to the bottom surface 12. Specifically, the end point of the first projection 191 away from the M point and the end point of the second projection 192 away from the M point are located in the same plane parallel to the bottom surface 12. That is, the blade projection has two highest points, which are the end point of the first projection 191 away from the M point and the end point of the second projection 192 away from the M point.

[0060] In some embodiments, point M is the midpoint of the cutting edge 14 along its own extension direction (Y direction). In other embodiments, point M is closer to the drill core 600 than the midpoint of the cutting edge 14 along its own extension direction.

[0061] In some embodiments, Figure 7 As shown, any two adjacent cutting edges 14 are smoothly connected by a rounded corner structure extending along the circumference of the blade body 1, and the projections of the two rounded corner structures connected to the cutting edge 14 in the corresponding first preset plane 10 are respectively the first rounded corner projection and the second rounded corner projection. Specifically, one of the highest points of the edge projection is the junction point of the first rounded corner projection and the edge projection, and the other highest point of the edge projection is the junction point of the second rounded corner projection and the edge projection.

[0062] In some embodiments, the radius R of the rounded structure is 0 mm-1 mm. It should be noted that R can be any value between 0 mm and 1 mm, such as R can be any value selected from 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1 mm.

[0063] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. An indexable insert, comprising an insert body (1) provided with a center hole (11), the insert body (1) comprising a top surface and a bottom surface (12) arranged opposite to each other along the Z direction, and four circumferential side surfaces (13) arranged opposite to each other in pairs along the X direction and the Y direction and connected end to end, the X direction, the Y direction and the Z direction are perpendicular to each other, and a cutting edge (14) is formed at the top surface and each of the circumferential side surfaces (13); It is characterized in that The projection of the cutting edge (14) in the first preset plane (10) is a blade projection, and in the direction from the two end points of the blade projection to the center, the blade projection is concave toward the side where the bottom surface (12) is located; the central axis of the center hole (11) is located in the first preset plane (10), and the first preset plane (10) is parallel to the distribution direction of the two circumferential side surfaces (13) respectively connecting the two ends of the length direction of the cutting edge (14); The point at which the distance between the blade projection and the bottom surface (12) along the Z direction is the smallest is point M, the blade projection comprises a first projection (191) and a second projection (192) respectively located on both sides of point M, the first projection (191) and the second projection (192) are both arcs and smoothly connected, and the first projection (191) is closer to the drill core (600) than the second projection (192); The first projection (191) is closer to the central axis of the drill bit than the second projection (192), the curvature radius of the first projection (191) is R1, the curvature radius of the second projection (192) is R2, and 20mm>R1≥R2>0.

2. The indexable insert according to claim 1, characterized in that: The cutting edge (14) comprises an inner cutting edge (141) and an outer cutting edge (142) respectively located on both sides of a second preset plane (20), the inner cutting edge (141) being closer to the drill core (600) than the outer cutting edge (142), the second preset plane (20) being perpendicular to the first preset plane (10), and the central axis of the central hole (11) being located in the second preset plane (20); Along the direction from the inner cutting edge (141) close to the first preset plane (10), the inner cutting edge (141) extends toward the side where the bottom surface (12) is located to form a rake face (15); The front cutting edge (15) is connected to the second preset plane (20) and the circumferential edge of the center hole (11) through a connecting surface, and the connecting surface is not higher than the front cutting edge (15).

3. The indexable insert according to claim 2, characterized in that: The blade width of the inner cutting edge (141) is L, 0mm<L≤0.2mm.

4. The indexable insert according to claim 2, characterized in that: The included angle between the inner cutting edge (141) and the bottom surface (12) is α, -15°≤α≤15°.

5. The indexable insert according to claim 2, characterized in that: The cross section of the front cutting surface (15) is a straight line segment, the angle between the straight line segment and the bottom surface (12) is β, 10°≤β≤30°, and the cross section of the front cutting surface (15) is parallel to the second preset plane (20) or is located in the second preset plane (20).

6. The indexable insert according to claim 1, characterized in that: The cutting edge (14) is connected to the circumferential side surface (13) via a flank surface (16), and the angle between the flank surface (16) and the central axis of the central hole (11) is γ, 3°≤γ≤15°.

7. The indexable insert according to any one of claims 1 to 6, characterized in that: The point at which the blade projection is spaced the largest from the bottom surface (12) in the Z direction is point N, and the distance between point M and point N in a direction perpendicular to the bottom surface (12) is H, 0.1 mm≤H≤2 mm.

8. The indexable insert according to claim 7, characterized in that: The distances between the two end points of the blade projection and the bottom surface (12) along the Z direction are both H, and the line connecting the two end points of the blade projection is parallel to the bottom surface (12).

9. The indexable insert according to any one of claims 1 to 6, characterized in that: The point M is the midpoint of the cutting edge (14) along its own extension direction, or the midpoint of the cutting edge (14) along its own extension direction is closer to the drill core (600) than the point M.

10. A drill bit, characterized in that: The invention comprises a tool rod (100), and an inner blade (200) and an outer blade (300) mounted on the same end of the tool rod (100); along the radial direction of the tool rod (100), the inner blade (200) is closer to the central axis of the tool rod (100) than the outer blade (300); and the inner blade (200) is an indexable blade as claimed in any one of claims 1 to 9.

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