CN109158665B

CN109158665B - Indexable drilling tool

Info

Publication number: CN109158665B
Application number: CN201810922468.4A
Authority: CN
Inventors: 王社权; 江爱胜; 李勋; 汤爱民; 项兴东; 王鹏
Original assignee: Zhuzhou Cemented Carbide Cutting Tools Co Ltd
Current assignee: Zhuzhou Cemented Carbide Cutting Tools Co Ltd
Priority date: 2018-08-14
Filing date: 2018-08-14
Publication date: 2020-02-04
Anticipated expiration: 2038-08-14
Also published as: CN109158665A

Abstract

The invention discloses an indexable drilling tool, wherein an inner blade is surrounded by a first upper surface, a first lower surface and a first side surface connecting the first upper surface and the first lower surface, the first upper surface and the first side surface are intersected to form a plurality of same inner cutting edges, during drilling, a cutting area of the inner cutting edge as a main cutting edge is positioned between a middle inner point and a middle outer point on the inner cutting edge, a cutting area of an outer cutting edge as the main cutting edge is positioned between a peripheral inner point and a peripheral outer point on the outer cutting edge, an inner convex cutting part with the maximum cutting depth on the inner cutting edge and the outer cutting edge is arranged between the middle inner point and the middle outer point in the feeding direction of the indexable drilling tool, and the depth difference of the middle inner point and the peripheral outer point relative to the inner convex cutting part is respectively H1 and H2, and the indexable drilling tool can meet the following requirements: h1 is more than or equal to 0.9H2 and less than or equal to 1.1H2, and the cutting tool has the advantages of small cutting vibration, strong radial balance capability, good quality of processed surface, high dimensional precision and the like.

Description

Indexable drilling tool

Technical Field

The invention relates to the technical field of metal cutting machining, in particular to an indexable drilling tool.

Background

The cutting edge of the indexable drilling tool is asymmetric relative to a central shaft, the cutting part of the indexable drilling tool comprises an inner blade and an outer blade, the inner blade and the outer blade respectively finish machining of different cutting areas, specifically, the inner blade finishes removing material of the central area, the outer blade finishes removing peripheral material, and the linear velocity of the cutting edge of the drilling tool is increased along with the increase of the radius, so that the linear velocity of the central area of the inner blade is close to zero, the friction of the cutting edge of the central area of the drilling tool is severe, and the removal amount of the material of the cutting edge at the position adjacent to the peripheral surface of the tool body is much larger than that of the center, in order to meet the requirements of different cutting working conditions of the inner blade and the outer blade, in the prior art, the inner blade and the outer blade are usually of different structures or have the same structures but adopt different installation sizes, although the wear, however, because the inner blade and the outer blade are mounted on the cutter body independently, when the inner blade and the outer blade participate in cutting, the radial stress of the cutter is difficult to balance, the unbalance of the cutting force is easy to generate cutting vibration, the quality of the processed surface and the size precision of a hole are reduced, and the service life of the indexable drilling cutter is greatly reduced.

In order to ensure that the radial cutting forces of the inner blade and the outer blade are balanced to a certain extent, in the prior art, the cutting forces of the inner blade and the outer blade are reasonably distributed in the radial direction by changing the cutting widths of the inner blade and the outer blade and enabling the inner blade and the outer blade to be distributed at asymmetric phase angles in the circumferential direction of a cutter body, however, in the drilling process, in order to ensure that the inner blade and the outer blade cut stably in the process of cutting into a workpiece, main cutting edges of the inner blade and the outer blade do not cut into the workpiece at the same time but are inclined to the processing surface, so that the radial balance of the inner blade and the outer blade is not only influenced by the cutting forces but also has a direct relation with the inclination degrees; more importantly, since the inner and outer blades are not worn synchronously, asynchronous changes in wear may also break the balance between the inner and outer blades. The radial balance is double radial balance of radial balance in a cutting plane and radial balance in an end plane, although the technical means can solve the problem of radial balance of the inner blade and the outer blade theoretically, due to the fact that the cutting edge shapes, the cutting-in inclination angles, the mounting angles, the rake angles and other structural dimensions of the inner blade and the outer blade are different, in the actual machining process, radial stress balance of the inner blade and the outer blade is difficult to achieve, cutting vibration is easy to generate during cutting, and accordingly the machined hole is large in diameter deviation, poor in machining surface quality and prone to collapse and defect of the inner blade and the outer blade.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the prior art and provides an indexable drilling tool with small cutting vibration, strong radial balance capability, good quality of a processed surface and high dimensional precision.

In order to solve the technical problems, the invention adopts the following technical scheme:

an indexable drilling tool comprises a tool body, an outer blade and an inner blade, wherein the tool body comprises a handle part, a cutting end part and a peripheral surface positioned between the handle part and the cutting end part, the handle part and the peripheral surface are symmetrical about a rotating central shaft of the tool body, the cutting end part is provided with a central groove and a circumferential groove which are communicated with spiral grooves on the peripheral surface, the central groove is arranged adjacent to the rotating central shaft, the circumferential groove is arranged adjacent to the peripheral surface, the outer blade is arranged in the circumferential groove and used for processing an outer ring area of a hole, the inner blade is arranged in the central groove and used for processing a central area of the hole, the inner blade is enclosed by a first upper surface, a first lower surface and a first side surface which is connected with the first upper surface and the first side surface, the first upper surface and the first side surface are intersected to form a plurality of same inner cutting edges, and the outer, The second lower surface and a second side surface connecting the second upper surface and the second lower surface are enclosed, the second upper surface and the second side surface are intersected to form a plurality of same external cutting edges, during drilling, a cutting area of the internal cutting edge serving as a main cutting edge is positioned between a middle inner point and a middle external point on the internal cutting edge, a cutting area of the external cutting edge serving as a main cutting edge is positioned between a peripheral inner point and a peripheral external point on the external cutting edge, an internal convex cutting part with the maximum cutting depth on the internal cutting edge and the external cutting edge is arranged between the middle inner point and the middle external point in the feeding direction of the indexable drilling tool, and the depth difference between the middle inner point and the peripheral external point relative to the internal convex cutting part is H1 and H2 respectively, so that the requirements that: h1 is more than or equal to 0.9H2 and less than or equal to 1.1H 2.

As a further improvement of the above technical solution:

in the feeding direction of the indexable drilling tool, an outward convex cutting part with the maximum cutting depth on an outer cutting edge is arranged between the inner circumferential point and the outer circumferential point, the distances between the inner circumferential point and the outer circumferential point and the outward convex cutting part in the axial direction of the indexable drilling tool are respectively H1 'and H2', and the requirements are met: 0.95H1 ' is less than or equal to H2 ' is less than or equal to 1.1H1 '.

The machining diameter of the indexable drilling tool is D, the cutting depth difference of the inner convex cutting part before the outer convex cutting part cuts into the workpiece in the feeding direction of the indexable drilling tool is H3, and the requirements are met: h3 is not less than 0.003D and not more than 0.01D.

The cutting width of the inner blade is Ae, the cutting width of the outer blade is Ae', and the requirements that: ae 'is more than or equal to 0.8 and is less than or equal to 0.95 Ae'.

In the radial direction of the indexable drilling tool, the distances between an inner convex cutting part on an inner cutting edge serving as a main cutting edge and a middle inner point and a middle outer point corresponding to the inner convex cutting part are d1 and d2 respectively, and the following requirements are met: d2 is more than or equal to 1mm and less than or equal to d 1.

In the radial direction of the indexable drilling tool, the distances between the convex cutting part on the outer cutting edge as the main cutting edge and the corresponding circumferential inner point and circumferential outer point of the convex cutting part are d1 'and d 2', respectively, which satisfy the following conditions: 0.3d2 ' is not less than d1 ' is not less than d2 '.

The first upper surface and the first side surface are intersected to form three or four groups of inner cutting edges, each inner cutting edge comprises two inner straight line edges and one inner corner edge, the inner convex cutting part is formed between the two inner straight line edges, and the inner straight line edges adjacent to the inner cutting edges are connected through the inner corner edges.

The first upper surface and the first side surface are intersected to form three or four groups of inner cutting edges, each inner cutting edge comprises an inner straight line edge and an inner corner edge, the inner straight line edges of the adjacent inner cutting edges are connected through the inner corner edges, and the inner convex cutting portion is formed between the inner straight line edges and the inner corner edges.

The second upper surface and the second side surface are intersected to form three groups or four groups of same external cutting edges, each external cutting edge comprises two outer straight line edges and one outer corner edge, the convex cutting part is formed between the two outer straight line edges, and the outer straight line edges of the adjacent external cutting edges are connected through the outer corner edges.

The cutting tool is characterized in that M inner convex cutting parts are arranged on a single inner cutting edge of the inner blade, N outer convex cutting parts are arranged on a single outer cutting edge of the outer blade, and the requirements for the cutting tool are as follows: m is more than or equal to 1 and less than or equal to 3, and N is more than or equal to 1 and less than or equal to 3.

The angle between the outer insert and the inner insert in the circumferential direction of the indexable drilling tool is β, which should satisfy β =180 °.

The outer cutting edge comprises an outer straight line edge and an outer corner edge, and the outer straight line edges of the adjacent outer cutting edges are connected through the outer corner edge.

The machining diameter of the indexable drilling tool is D, the inner convex cutting part cuts into a workpiece before the outer cutting edge in the feeding direction of the indexable drilling tool, the cutting depth difference is H3, and the machining diameter satisfies the following conditions: h3 is not less than 0.003D and not more than 0.01D.

Compared with the prior art, the invention has the advantages that:

(1) the indexable drilling tool of the invention is provided with an inner convex cutting part with the maximum cutting depth on an inner cutting edge and an outer cutting edge between a middle inner point and a middle outer point, the radial stress directions generated by partial cutting edges between the middle inner point and the inner convex cutting part and partial cutting edges between a peripheral outer point and the inner convex cutting part in a cutting plane are opposite, and the distances among the middle inner point, the peripheral outer point and the inner convex cutting part in the axial direction of the indexable drilling tool are respectively H1 and H2, and 0.9H2 is not less than H1 and not more than 1.1H2, so that the radial stress generated by the partial cutting edges between the middle inner point and the inner convex cutting part and the partial cutting edges between the peripheral outer point and the inner convex cutting part in the cutting plane are basically balanced, the radial balance of the inner insert and the outer insert is not influenced by the shapes of the cutting edges of the inner insert and the outer insert, and the radial balance is only dependent on the balance of the cutting force in the end plane, when the main cutting force in the end plane of the inner blade and the outer blade affects the balance of the indexable drilling tool, the influence of the cutting edge shapes of the inner blade and the outer blade on the radial balance in the main cutting plane of the tool can be ignored, so that when the mounting dimensions of the inner blade and the outer blade are considered, the influence of the parameters of the cutting edge shapes and the cutting inclination angles, the mounting angles, the rake angles and the like of the inner blade and the outer blade on the radial balance in the cutting plane does not need to be considered, and only the balance of the cutting force in the end plane is realized, so that the mounting dimensions of the inner blade and the outer blade can be obtained more simply, and the double radial balance of the cutting surface and the end plane of the indexable drilling tool can be realized, therefore, the indexable drilling tool has small cutting vibration, good machining surface quality and high dimensional accuracy.

(2) The indexable drilling tool is provided with the convex cutting part with the maximum cutting depth between the inner circumferential point and the outer circumferential point, the directions of cutting forces generated in a cutting plane by a part of cutting edges positioned between the inner circumferential point and the convex cutting part and a part of cutting edges positioned between the outer circumferential point and the convex cutting part are opposite, and the distances among the inner circumferential point, the outer circumferential point and the convex cutting part in the axial direction of the indexable drilling tool are respectively H1 'and H2', and the indexable drilling tool meets the following requirements: 0.95H1 ' ≦ H2 ' ≦ 1.1H1 ', and thus, the cutting forces generated by the part of the cutting edge between the peripheral inner point and the convex cutting portion and the part of the cutting edge between the peripheral outer point and the convex cutting portion in the cutting plane are substantially balanced, that is, the outer insert itself can achieve radial balance in the cutting plane regardless of the cutting edge shape and the parameters of the cutting-in inclination angle, the mounting angle, the rake angle, and the like of the outer insert, so that the combination of the inner insert, the outer insert, and the radial balance of the outer insert in the cutting plane are not affected by the shapes of the cutting edges of the inner insert and the outer insert, and only depend on the balance of the cutting forces in the end plane. When the inner blade, the outer blade combination and the outer blade only have main cutting force in the end plane to influence the balance of the indexable drilling tool, the influence of the cutting edge shapes of the inner blade and the outer blade on the radial balance of the tool can be ignored, the calculation of the radial balance of the indexable drilling tool is fundamentally simplified, and the radial balance installation size of the indexable drilling tool can be obtained more simply and accurately. Meanwhile, because the outer blade is radially balanced in the cutting plane, even if the inner blade and the outer blade are subjected to asynchronous abrasion due to the influence of the cutting speed, when the cutting force is asynchronously changed, the radial balance of the outer blade in the cutting plane is not influenced, the cutting stability of the outer blade is greatly improved, the service life of the outer blade is prolonged, the service life of an indexable drilling tool is prolonged, and the consistency of the quality and the dimensional accuracy of the machined surface is always ensured while the quality and the dimensional accuracy of the machined surface are improved.

Drawings

Fig. 1 is a perspective view of a first embodiment of an indexable drilling tool according to the invention.

Fig. 2 is a schematic end view of a second embodiment of an indexable drilling tool according to the invention.

Fig. 3 is a perspective view of an insert in a first embodiment of an indexable drilling tool according to the invention.

Fig. 4 is a perspective view of an insert, which is an embodiment of the indexable drilling tool according to the first embodiment of the invention.

Fig. 5 is a schematic view of the mounting of an inner insert and an outer insert of a first embodiment of an indexable drilling tool according to the invention.

Fig. 6 is a perspective view of a second embodiment of an indexable drilling tool according to the invention.

Fig. 7 is a schematic end view of a second embodiment of an indexable drilling tool according to the invention.

Fig. 8 is a schematic view of the mounting of an inner insert and an outer insert of a second embodiment of an indexable drilling tool according to the invention.

The reference numerals in the figures denote:

1. a cutter body; 11. a handle; 12. cutting the end portion; 13. a peripheral surface; 14. rotating the central shaft; 15. a helical groove; 16. a central slot; 17. a circumferential groove; 2. an outer blade; 21. a second upper surface; 22. a second lower surface; 23. a second side surface; 24. an outer cutting edge; 241. an outer straight edge; 242. an outer corner edge; 25. an intra-weekly point; 26. a point outside the perimeter; 27. an outward convex cutting portion; 3. an inner blade; 31. a first upper surface; 32. a first lower surface; 33. a first side surface; 34. an inner cutting edge; 341. an inner straight edge; 342. an inner corner edge; 35. a middle inner point; 36. a middle and outer point; 37. an inwardly convex cutting portion.

Detailed Description

The invention will be described in further detail below with reference to the drawings and specific examples.

Fig. 1 to 5 show a first embodiment of an indexable drilling tool according to the present invention, which includes a tool body 1, an outer insert 2, and an inner insert 3, the tool body 1 includes a shank 11, a cutting end 12, and a circumferential surface 13 between the shank 11 and the cutting end 12, the shank 11 and the circumferential surface 13 are symmetrical with respect to a central axis of rotation 14 of the tool body 1, the cutting end 12 is provided with a central groove 16 and a circumferential groove 17 communicating with a spiral groove 15 on the circumferential surface 13, the central groove 16 is provided adjacent to the central axis of rotation 14, the circumferential groove 17 is provided adjacent to the circumferential surface 13, the outer insert 2 is provided in the circumferential groove 17 for machining an outer annular region of a hole, the inner insert 3 is provided in the central groove 16 for machining a central region of a hole, the inner insert 3 is surrounded by a first upper surface 31, a first lower surface 32, and a first side surface 33 connecting the first upper surface 31 and the first lower surface, the first upper surface 31 and the first side surface 33 intersect to form a plurality of same inner cutting edges 34, the outer blade 2 is surrounded by a second upper surface 21, a second lower surface 22 and a second side surface 23 connecting the second upper surface 21 and the second lower surface 22, the second upper surface 21 and the second side surface 23 intersect to form a plurality of same outer cutting edges 24, during drilling, the cutting area of the inner cutting edge 34 as a main cutting edge is positioned between a middle inner point 35 and a middle outer point 36 on the inner cutting edge 34, the cutting area of the outer cutting edge 24 as a main cutting edge is positioned between a periphery inner point 25 and a periphery outer point 26 on the outer cutting edge 24, in the feeding direction of the indexable drilling tool, an inner convex cutting portion 37 having the maximum cutting depth on the inner cutting edge 34 and the outer cutting edge 24 is arranged between the middle inner point 35 and the middle outer point 36, and the depth difference of the middle inner point 35 and the periphery outer point 26 relative to the inner convex cutting portion 37 is respectively H1, H2, which should satisfy: 0.9H2 ≦ H1 ≦ 1.1H2, in this example: h1=1.05H2, an inner convex cutting portion 37 having the largest cutting depth on the inner cutting edge 34 and the outer cutting edge 24 is arranged between the middle inner point 35 and the middle outer point 36, the radial stress generated in the cutting plane by the partial cutting edges between the middle inner point 35 and the inner convex cutting portion 37 and the partial cutting edges between the outer points 26 and the inner convex cutting portion 37 are opposite, and the distances of the middle inner point 35, the outer points 26 and the inner convex cutting portion 37 in the axial direction of the drilling indexable tool are respectively H1 and H2, 0.9H2 is not less than H1 is not more than 1.1H2, so that the radial stress generated in the cutting plane by the partial cutting edges between the middle inner point 35 and the inner convex cutting portion 37 and the partial cutting edges between the outer points 26 and the inner convex cutting portion 37 is basically balanced, and the radial balance of the inner blade 3 and the outer blade 2 is not affected by the shapes of the cutting edges of the inner blade 3 and the outer blade 2, the radial balance is determined only by the balance of the cutting forces in the end plane, and when the main cutting forces in the end plane affect the balance of the indexable drilling tool, the influence of the cutting edge shapes of the inner insert 3 and the outer insert 2 on the radial balance in the main cutting plane of the tool can be ignored, and therefore, when considering the installation dimensions of the inner insert 3 and the outer insert 2, the influence of the parameters of the cutting edge shapes and the cutting inclination angles, the installation angles, and the rake angles of the inner insert 3 and the outer insert 2 on the radial balance in the cutting plane need not be considered, and only the balance of the cutting forces in the end plane needs to be achieved, so that the installation dimensions of the inner insert 3 and the outer insert 2 can be obtained more simply, and the dual radial balance in the cutting plane and the end plane of the indexable drilling tool can be achieved, and therefore, the cutting vibration of the indexable drilling tool is small, the quality of the machined surface is good, and, The dimensional accuracy is high.

In the present embodiment, in the feeding direction of the indexable drilling tool, the convex cutting portion 27 having the maximum cutting depth on the outer cutting edge 24 is provided between the inner circumferential point 25 and the outer circumferential point 26, and the distances between the inner circumferential point 25, the outer circumferential point 26, and the convex cutting portion 27 in the axial direction of the indexable drilling tool are H1 'and H2', respectively, and satisfy: 0.95H1 ' ≦ H2 ' ≦ 1.1H1 ', in this embodiment, H2 ' =1.05H1 ', a convex cutting portion 27 having a maximum cutting depth is provided between the circumferential inner point 25 and the circumferential outer point 26, cutting forces generated in the cutting plane by a portion of the cutting edge between the circumferential inner point 25 and the convex cutting portion 27 and a portion of the cutting edge between the circumferential outer point 26 and the convex cutting portion 27 are in opposite directions, and distances in the axial direction of the indexable drilling tool between the circumferential inner point 25, the circumferential outer point 26, and the convex cutting portion 27 are H1 ', H2 ', respectively, and satisfy: 0.95H1 ' ≦ H2 ' ≦ 1.1H1 ', and thus, the cutting forces generated in the cutting plane by the portion of the cutting edge located between the peripheral inner point 25 and the convex cutting portion 27 and the portion of the cutting edge located between the peripheral outer point 26 and the convex cutting portion 27 are substantially balanced, i.e., the outer insert 2 itself can achieve radial balance in the cutting plane regardless of the cutting edge shape and the parameters of the cutting-in inclination angle, the mounting angle, and the rake angle of the outer insert 2, so that the combination of the inner insert 3, the outer insert 2, and the radial balance of the outer insert 2 in the cutting plane are not affected by the shapes of the cutting edges of the inner insert 3 and the outer insert 2, and depend only on the balance of the cutting forces in the end plane. When the main cutting force in the end plane of the inner blade 3, the outer blade 2 combination and the outer blade 2 only influences the balance of the indexable drilling tool, the influence of the cutting edge shapes of the inner blade 3 and the outer blade 2 on the radial balance of the tool can be ignored, the calculation of the radial balance of the indexable drilling tool is fundamentally simplified, and the radial balance installation size of the indexable drilling tool can be obtained more simply and accurately. Meanwhile, because the outer blade 2 has obtained radial balance in the cutting plane, even if the inner blade 3 and the outer blade 2 are affected by the cutting speed and are abraded asynchronously, when the cutting force is changed asynchronously, the radial balance of the outer blade 2 in the cutting plane is not affected, the cutting stability of the outer blade is greatly improved, the service life of the outer blade 2 is prolonged, the service life of the indexable drilling tool is prolonged, and the consistency of the quality and the size precision of the machined surface is ensured all the time while the quality and the size precision of the machined surface are improved.

The machining diameter of the indexable drilling tool is D, in order to ensure that the cutting force borne by the tool body 1 is slowly increased when the inner blade 3 and the outer blade 2 of the indexable drilling tool are cut and fed, but the cutting force is kept balanced in a cutting surface, in the feeding direction of the indexable drilling tool, the difference of the cutting depth of the inner convex cutting part 37 before the outer convex cutting part 27 cuts into a workpiece is H3, and the requirements are met: 0.003D H3D 0.01D, in this example H3= 0.006D.

In order to ensure that the main cutting forces of the inner blade 3 and the outer blade 2 are balanced in the end plane, it should be ensured that the main cutting forces of the inner blade 3 and the outer blade 2 are substantially equal, but because the inner blade 3 and the outer blade 2 are influenced by the assembly dimension and the cutting speed, the main cutting forces of the inner blade 3 and the outer blade 2 are not completely dependent on the cutting width, and in order to eliminate the influence of the different cutting speeds of the inner blade 3 and the outer blade 2 on the radial balance of the main cutting forces in the end plane, the cutting width of the inner blade 3 is Ae, and the cutting width of the outer blade 2 is Ae', it should be satisfied that: ae 'is more than or equal to 0.8 and is less than or equal to 0.95 Ae'. In this example, Ae =0.9 Ae'.

In order to eliminate the influence of different cutting speeds of the cutting edges on the two sides of the inner convex cutting part 37 of the inner blade 3 on the radial balance of the inner blade 3 in the radial direction of the indexable drilling tool, the distances between the inner convex cutting part 37 on the inner cutting edge 34 as a main cutting edge and the middle and inner points 35 and the middle and outer points 36 corresponding to the inner convex cutting part 37 are d1 and d2 respectively, which should satisfy the following conditions: d2 is more than or equal to 1mm and less than or equal to d 1. In this embodiment, d2=0.6d 1.

In order to eliminate the influence of the different cutting speeds of the cutting edges on both sides of the convex cutting portion 27 of the outer insert 2 on the radial balance of the outer insert 2, the distances d1 'and d 2' between the convex cutting portion 27 on the outer cutting edge 24 as the main cutting edge and the corresponding circumferential inner point 25 and circumferential outer point 26 of the convex cutting portion 27 in the radial direction of the indexable drilling tool should satisfy: 0.3d2 ' is not less than d1 ' is not less than d2 '. In this embodiment, d1 '= 0.6d 2'.

In this embodiment, the first upper surface 31 and the first side surface 33 intersect to form four sets of inner cutting edges 34, each inner cutting edge 34 includes two inner straight edges 341 and one inner corner edge 342, the inner convex cutting portion 37 is formed between the two inner straight edges 341, and the inner straight edges 341 of adjacent inner cutting edges 34 are connected by the inner corner edges 342.

In this embodiment, the second upper surface 21 and the second side surface 23 intersect to form four sets of identical outer cutting edges 24, each outer cutting edge 24 includes two outer straight edges 241 and one outer corner edge 242, the outer convex cutting portion 27 is formed between the two outer straight edges 241, and the outer straight edges 241 of adjacent outer cutting edges 24 are connected by the outer corner edges 242.

In order to improve the stability of the inner blade 3 and the outer blade 2 in the cutting process, even if the inner blade 3 and the outer blade 2 are worn out asynchronously in the cutting process and the cutting forces of the inner blade 3 and the inner blade 3 are changed asymmetrically, the indexable drilling tool still has good vibration resistance, high dimensional accuracy and high surface quality accuracy guarantee capability, a single inner cutting edge 34 of the inner blade 3 is provided with M inner convex cutting parts 37, and a single outer cutting edge 24 of the outer blade 2 is provided with N outer convex cutting parts 27, which should satisfy the following requirements: m is more than or equal to 1 and less than or equal to 3, and N is more than or equal to 1 and less than or equal to 3. In this embodiment, M =1 and N =1.

In this embodiment, the angle between the outer insert 2 and the inner insert 3 in the circumferential direction of the indexable drilling tool is β, and when the inner insert 3 and the outer insert 2 of the indexable drilling tool are fed, since the inner insert 3 and the outer insert 2 have already obtained radial balance in the cutting plane, in order to ensure that the inner insert 3 and the outer insert 2 also obtain radial balance in the end plane, the upper surfaces of the inner insert 3 and the outer insert 2 in the end plane should be parallel, i.e., β =180 °.

Fig. 6 to 8 show a second embodiment of an indexable drilling tool according to the invention, which is substantially identical to the first embodiment, with the only difference that: the first upper surface 31 and the first side surface 33 intersect to form four sets of inner cutting edges 34, each inner cutting edge 34 comprises an inner straight edge 341 and an inner corner edge 342, the inner straight edges 341 of adjacent inner cutting edges 34 are connected through the inner corner edges 342, the inner convex cutting portion 37 is formed between the inner straight edges 341 and the inner corner edges 342, the outer cutting edge 24 comprises an outer straight edge 241 and an outer corner edge 242, and the outer straight edges 241 of adjacent outer cutting edges 24 are connected through the outer corner edges 242, so that the structure simplifies the structures of the outer insert 2 and the inner insert 3, reduces the manufacturing cost of the outer insert 2 and the inner insert 3, and improves the cost performance of the indexable drilling tool on the basis of ensuring that the radial balance of the outer insert 2 and the inner insert 3 in the cutting surface can be realized.

The machining diameter of the indexable drilling tool is D, in order to ensure that the cutting force borne by the tool body 1 is slowly increased when the inner blade 3 and the outer blade 2 of the indexable drilling tool are subjected to cutting feeding, but the cutting force is kept balanced in a cutting surface, in the feeding direction of the indexable drilling tool, the inner convex cutting part 37 is cut into a workpiece before the outer cutting edge 24, the cutting depth difference is H3, and the requirements are met: h3 is not less than 0.003D and not more than 0.01D. In this example, H3= 0.007D.

In the circumferential direction of the indexable drilling tool, the angle between the outer insert 2 and the inner insert 3 is β, and when the inner insert 3 and the outer insert 2 of the indexable drilling tool are fed in cutting, since the inner insert 3 and the outer insert 2 have already obtained radial balance in the cutting plane, in order to ensure that the inner insert 3 and the outer insert 2 also obtain radial balance in the end plane, the upper surfaces of the inserts 3 and the outer insert 2 should be parallel in the end plane, i.e. β =180 °.

In the above embodiments, β is the angle between the upper surfaces of the inner blade 3 and the outer blade 2 in the end plane, but the present invention is not limited to this, and when the upper surfaces of the inner blade 3 and the outer blade 2 are non-planar structures, β may also be the angle between the lower surfaces of the inner blade 3 and the outer blade 2 in the end plane.

In addition to the above embodiments, the number of the inner cutting edges 34 of the inner blade 3 and the outer cutting edges 24 of the outer blade 2, and the number of the inner convex cutting portions 37 and the outer convex cutting portions 27 can be set according to the actual processing requirements, so as to improve the cost performance of the blades and optimize the cutting process of the blades.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.

Claims

1. An indexable drilling tool comprises a tool body (1), an outer blade (2) and an inner blade (3), wherein the tool body (1) comprises a handle part (11), a cutting end part (12) and a peripheral surface (13) positioned between the handle part (11) and the cutting end part (12), the handle part (11) and the peripheral surface (13) are symmetrical about a rotating central shaft (14) of the tool body (1), the cutting end part (12) is provided with a central groove (16) and a circumferential groove (17) which are communicated with a spiral groove (15) on the peripheral surface (13), the central groove (16) is arranged near the rotating central shaft (14), the circumferential groove (17) is arranged near the peripheral surface (13), the outer blade (2) is arranged in the circumferential groove (17) and used for machining an outer ring area of a hole, the inner blade (3) is arranged in the central groove (16) and used for machining a central area of the hole, the inner blade (3) is surrounded by a first upper surface (31), a first lower surface (32) and a first side surface (33) connecting the first upper surface (31) and the first lower surface (32), the first upper surface (31) and the first side surface (33) are intersected to form a plurality of same inner cutting edges (34), the outer blade (2) is surrounded by a second upper surface (21), a second lower surface (22) and a second side surface (23) connecting the second upper surface (21) and the second lower surface (22), the second upper surface (21) and the second side surface (23) are intersected to form a plurality of same outer cutting edges (24), and the outer cutting edge is characterized in that: when the indexable drilling tool is used for drilling, the cutting area of the inner cutting edge (34) serving as a main cutting edge is positioned between a middle inner point (35) and a middle outer point (36) on the inner cutting edge (34), the cutting area of the outer cutting edge (24) serving as a main cutting edge is positioned between a peripheral inner point (25) and a peripheral outer point (26) on the outer cutting edge (24), an inner convex cutting part (37) with the maximum cutting depth on the inner cutting edge (34) and the outer cutting edge (24) is arranged between the middle inner point (35) and the middle outer point (36) in the feeding direction of the indexable drilling tool, the depth difference between the middle inner point (35) and the peripheral outer point (26) relative to the inner convex cutting part (17) is H1 and H2 respectively, and the requirements are met: h1 is more than or equal to 0.9H2 and less than or equal to 1.1H 2.

2. The indexable drilling tool of claim 1, wherein: in the feeding direction of the indexable drilling tool, an outward convex cutting part (27) with the maximum cutting depth on an outer cutting edge (24) is arranged between the inner circumferential point (25) and the outer circumferential point (26), the distances between the inner circumferential point (25), the outer circumferential point (26) and the outward convex cutting part (27) in the axial direction of the indexable drilling tool are respectively H1 'and H2', and the following conditions are met: 0.95H1 ' is less than or equal to H2 ' is less than or equal to 1.1H1 '.

3. The indexable drilling tool of claim 2, wherein: the machining diameter of the indexable drilling tool is D, the cutting depth difference of the inner convex cutting part (37) before the outer convex cutting part (27) cuts into the workpiece in the feeding direction of the indexable drilling tool is H3, and the machining diameter satisfies the following conditions: h3 is not less than 0.003D and not more than 0.01D.

4. The indexable drilling tool of claim 2, wherein: the cutting width of the inner blade (3) is Ae, the cutting width of the outer blade (2) is Ae', and the requirements that: ae 'is more than or equal to 0.8 and is less than or equal to 0.95 Ae'.

5. The indexable drilling tool of claim 2, wherein: in the radial direction of the indexable drilling tool, the distances between an inner convex cutting part (37) on an inner cutting edge (34) as a main cutting edge and a middle inner point (35) and a middle outer point (36) corresponding to the inner convex cutting part (37) are d1 and d2 respectively, and the following requirements are met: d2 is more than or equal to 1mm and less than or equal to d 1.

6. The indexable drilling tool of claim 2, wherein: in the radial direction of the indexable drilling tool, the distances between an outward convex cutting part (27) on an outer cutting edge (24) as a main cutting edge and a corresponding circumferential inner point (25) and a circumferential outer point (26) of the outward convex cutting part (27) are d1 'and d 2', respectively, and the following conditions are met: 0.3d2 ' is not less than d1 ' is not less than d2 '.

7. The indexable drilling tool according to any one of claims 1 to 6, wherein: the first upper surface (31) and the first side surface (33) are intersected to form three or four groups of inner cutting edges (34), each inner cutting edge (34) comprises two inner straight edges (341) and one inner corner edge (342), the inner convex cutting part (37) is formed between the two inner straight edges (341), and the inner straight edges (341) of the adjacent inner cutting edges (34) are connected through the inner corner edges (342).

8. The indexable drilling tool according to any one of claims 1 to 6, wherein: the first upper surface (31) and the first side surface (33) are intersected to form three or four groups of inner cutting edges (34), each inner cutting edge (34) comprises an inner straight edge (341) and an inner corner edge (342), the inner straight edges (341) of the adjacent inner cutting edges (34) are connected through the inner corner edges (342), and the inner convex cutting portion (37) is formed between the inner straight edges (341) and the inner corner edges (342).

9. The indexable drilling tool according to any one of claims 2 to 6, wherein: the second upper surface (21) and the second side surface (23) are intersected to form three or four groups of same external cutting edges (24), each external cutting edge (24) comprises two external straight edges (241) and one external corner edge (242), the external convex cutting part (27) is formed between the two external straight edges (241), and the external straight edges (241) of the adjacent external cutting edges (24) are connected through the external corner edges (242).

10. The indexable drilling tool of claim 2, wherein: the inner cutting edge (34) of the inner blade (3) is provided with M inner convex cutting parts (37), the outer cutting edge (24) of the outer blade (2) is provided with N outer convex cutting parts (27), and the requirements that: m is more than or equal to 1 and less than or equal to 3, and N is more than or equal to 1 and less than or equal to 3.

11. The indexable drilling tool according to claim 9, wherein the angle between the outer insert (2) and the inner insert (3) in the circumferential direction of the indexable drilling tool is β, which satisfies β -180 °.

12. The indexable drilling tool of claim 1, wherein: the outer cutting edge (24) comprises an outer straight edge (241) and an outer corner edge (242), and the outer straight edges (241) of the adjacent outer cutting edges (24) are connected through the outer corner edge (242).

13. The indexable drilling tool of claim 12, wherein: the machining diameter of the indexable drilling tool is D, the inner convex cutting portion (37) cuts into the workpiece before the outer cutting edge (24) in the feed direction of the indexable drilling tool with a cutting depth difference of H3, and the following conditions are satisfied: h3 is not less than 0.003D and not more than 0.01D.

14. The indexable drilling tool according to claim 12 or 13, characterized in that the angle between the outer insert piece (2) and the inner insert piece (3) in the circumferential direction of the indexable drilling tool is β, which satisfies β -180 °.