A shallow hole drill insert
By designing cutting edge structures and materials that adapt to the different inner and outer cutting edges in shallow hole drill inserts, the problems of low life and frequent tool changes of existing shallow hole drill inserts have been solved, achieving efficient use of inserts and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHUZHOU CEMENTED CARBIDE CUTTING TOOLS CO LTD
- Filing Date
- 2025-07-28
- Publication Date
- 2026-07-24
AI Technical Summary
Existing shallow hole drill bits have a short lifespan under working conditions with a large difference in the linear velocity between the inner and outer cutting edges, resulting in frequent tool replacements and high costs.
Design a shallow hole drill bit, dividing the cutting edge into an outer peripheral cutting edge far from the tool holder axis and an inner peripheral cutting edge close to the tool holder axis. The outer peripheral cutting edge has a high linear velocity and is mainly subjected to oxidative wear, with a larger rake angle and cutting edge width. The inner peripheral cutting edge has a low linear velocity and is mainly subjected to extrusion, with a smaller rake angle and cutting edge width. It is made of tungsten cobalt cemented carbide or tungsten cobalt titanium cemented carbide, with a Ti-Al-N, Ti-Al-Si-N, or Al-Cr-N coating on the surface.
It improves the overall lifespan of the blades, reduces the frequency of blade changes, and lowers costs.
Smart Images
Figure CN224543205U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of metal cutting technology, specifically to a shallow hole drill bit. Background Technology
[0002] Indexable shallow hole drills, also known as U-drills or high-powered drills, are commonly used hole-making tools, widely used for drilling shallow holes 3 to 5 times the diameter of the drill bit. The drill head has two identical carbide cutting inserts. One, closer to the center of the drill shank, removes material from the inner part of the hole and is called the inner cutting edge or center insert; the other, farther from the center, removes material from the periphery and is called the outer cutting edge or edge insert. The drilling is completed by overlapping the inner and outer cutting edges. Because the inner and outer cutting edges are mounted at different diameters on the drill shank, the linear velocities on their cutting edges differ significantly even at the same rotational speed (angular velocity), as shown by the formula linear velocity = angular velocity × radius. The outer cutting edge has a high linear velocity, and the insert primarily experiences oxidative wear, requiring a smooth cutting motion and minimal heat generation during drilling. The inner cutting edge has a low linear velocity, sometimes even zero at the center of the drill shank, and the insert primarily experiences extrusion and abrasive wear, requiring high edge strength, resistance to extrusion, and minimal chipping. Therefore, it can be seen that shallow hole drills have different requirements for internal and external cutting tools, and require different groove shapes on the cutting edge.
[0003] Patent CN20221174345.9 discloses a drilling insert with a W-shaped or T-shaped shape. Its main cutting unit includes two straight cutting edges of the same length. However, it does not have a specific design for the working condition where the linear speed of the inner and outer cutting edges differs greatly during shallow hole drilling. Therefore, it has problems such as low insert life, frequent tool changes, and high drilling costs. Utility Model Content
[0004] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a shallow hole drill bit that improves the overall life of the cutting tool, avoids the need for frequent tool replacement, and reduces costs.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A shallow hole drill bit includes a polygonal plate-shaped bit body. The bit body is formed by an upper surface, a lower surface, and multiple side surfaces connecting the upper and lower surfaces. Each side surface includes an outer peripheral side surface and an inner peripheral side surface. The outer peripheral side surface intersects with the upper surface to form an outer peripheral cutting edge, and the inner peripheral side surface intersects with the upper surface to form an inner peripheral cutting edge. The outer peripheral cutting edge is away from the tool holder axis S1, and the inner peripheral cutting edge is close to the tool holder axis S1. The rake angle of the outer peripheral cutting edge is α. 51 The blade width is B 51 The rake angle of the inner circumferential cutting edge is A. 52 The blade width is B 52 A should be satisfied51 ≥A 52 B 51 <B 52 .
[0006] As a further improvement to the above technical solution: The side surface also includes a transition surface, which intersects with the upper surface to form a transition edge. The transition edge connects the outer peripheral cutting edge and the inner peripheral cutting edge, and the three together form the main cutting edge.
[0007] The transition edge is a circular arc transition edge.
[0008] The main cutting edge is provided with multiple edges, which are arranged in a circular array around the axis S2 of the blade body.
[0009] Adjacent main cutting edges are connected by a tool tip arc.
[0010] The clearance angle values of the outer and inner peripheral cutting edges are equal and neither is 0.
[0011] The main cutting edge is made of tungsten-cobalt cemented carbide or tungsten-cobalt-titanium cemented carbide.
[0012] The surface of the main cutting edge is coated with a Ti-Al-N, Ti-Al-Si-N, or Al-Cr-N coating.
[0013] The 0≤A 51 ≤8°, 0.05mm≤B 51 ≤0.2mm.
[0014] The 0≤A 52 ≤5°, 0.1mm≤B 52 ≤0.3mm.
[0015] Compared with the prior art, the advantages of this utility model are: The shallow hole drill bit disclosed in this utility model divides the cutting edge into an outer peripheral cutting edge relatively far from the tool holder axis S1 and an inner peripheral cutting edge relatively close to the tool holder axis S1. The outer peripheral cutting edge is far from S1 and has a high linear velocity. During the machining process, the wear is mainly oxidative wear. The rake angle A is... 51 The design is relatively large, with a blade width of B. 51 The smaller design ensures smooth cutting and effectively reduces oxidative wear. Since the inner circumferential cutting edge is close to S1, wear during machining is primarily due to compression. Therefore, the rake angle A is... 52 The design is relatively small, with a blade width of B. 52 The larger design ensures the strength of the inner circumferential cutting edge, improves the overall lifespan of the insert, avoids frequent tool changes, and reduces costs. Attached Figure Description
[0016] Figure 1This is a three-dimensional structural diagram of the shallow hole drill bit of this utility model.
[0017] Figure 2 This is a top view of the shallow hole drill bit of this utility model.
[0018] Figure 3 yes Figure 2 A schematic diagram of the cross-sectional structure of AA.
[0019] Figure 4 yes Figure 2 A schematic diagram of the cross-sectional structure of BB.
[0020] Figure 5 This is a schematic diagram of the application structure of the shallow hole drill bit of this utility model.
[0021] The labels in the diagram represent: 1. Insert body; 2. Top surface; 3. Bottom surface; 4. Side surface; 41. Outer circumferential side surface; 42. Inner circumferential side surface; 43. Transition surface; 5. Main cutting edge; 51. Outer circumferential cutting edge; 52. Inner circumferential cutting edge; 53. Transition edge; 6. Tool holder; 7. Tool tip arc. Detailed Implementation
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0023] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0024] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0026] Figures 1 to 5 This invention illustrates an embodiment of a shallow hole drill bit. The shallow hole drill bit of this embodiment includes a polygonal plate-shaped bit body 1. The bit body 1 is formed by an upper surface 2, a lower surface 3, and multiple side surfaces 4 connecting the upper surface 2 and the lower surface 3. Each side surface 4 includes an outer peripheral side surface 41 and an inner peripheral side surface 42. The outer peripheral side surface 41 intersects with the upper surface 2 to form an outer peripheral cutting edge 51, and the inner peripheral side surface 42 intersects with the upper surface 2 to form an inner peripheral cutting edge 52. The outer peripheral cutting edge 51 is away from the axis S1 of the tool holder 6, and the inner peripheral cutting edge 52 is close to the axis S1 of the tool holder 6. The rake angle of the outer peripheral cutting edge 51 is α. 51 The blade width is B 51 The rake angle of the inner circumferential cutting edge 52 is A. 52 The blade width is B 52 A should be satisfied 51 ≥A 52 B 51 <B 52 .
[0027] This shallow hole drill bit divides the cutting edge into an outer peripheral cutting edge 51, which is relatively far from the axis S1 of the tool holder 6, and an inner peripheral cutting edge 52, which is relatively close to the axis S1 of the tool holder 6. The outer peripheral cutting edge 51 is far from S1 and has a high linear velocity. During the machining process, the wear is mainly oxidative wear. The rake angle A is... 51 The design is relatively large, with a blade width of B. 51 The smaller design ensures smooth cutting and effectively reduces oxidative wear. Since the inner circumferential cutting edge 52 is close to S1, wear during machining is primarily due to compression. Therefore, the rake angle A is... 52 The design is relatively small, with a blade width of B. 52 The larger design ensures the strength of the inner circumferential cutting edge 52, improves the overall lifespan of the insert, avoids the need for frequent tool changes, and reduces costs.
[0028] Furthermore, in this embodiment, the side surface 4 also includes a transition surface 43, which intersects with the upper surface 2 to form a transition edge 53. The transition edge 53 connects the outer peripheral cutting edge 51 and the inner peripheral cutting edge 52, and the three together form the main cutting edge 5. The transition edge 53 can increase the strength of the tool tip and reduce wear.
[0029] Furthermore, in this embodiment, the transition edge 53 is a circular arc transition edge. This ensures that the main cutting edge 5 has no sharp points, reduces stress concentration, and improves the service life of the main cutting edge 5.
[0030] Furthermore, in this embodiment, multiple main cutting edges 5 are provided, and these multiple main cutting edges 5 are arranged in a circular array around the axis S2 of the insert body 1. After one main cutting edge 5 wears out, other main cutting edges 5 can be used to continue machining, reducing insert replacement time, improving machining efficiency, and lowering costs. Specifically, three main cutting edges 5 are provided.
[0031] Furthermore, in this embodiment, adjacent main cutting edges 5 are connected by a tip arc 7. This ensures that the entire cutting portion of the insert is free of sharp points, reduces stress concentration, and improves the insert's service life.
[0032] Furthermore, in this embodiment, the clearance angles of the outer peripheral cutting edge 51 and the inner peripheral cutting edge 52 are equal and neither is 0. This improves cutting sharpness. Preferably, the clearance angles of both the outer peripheral cutting edge 51 and the inner peripheral cutting edge 52 are 7°.
[0033] Furthermore, in this embodiment, the main cutting edge 5 is made of tungsten-cobalt cemented carbide or tungsten-cobalt-titanium cemented carbide. It has high strength and good wear resistance.
[0034] Furthermore, in this embodiment, the surface of the main cutting edge 5 is coated with a Ti-Al-N, Ti-Al-Si-N, or Al-Cr-N coating. This provides high hardness and further enhances wear resistance.
[0035] Furthermore, in this embodiment, 0≤A 51 ≤8°, 0.05mm≤B 51 ≤0.2mm. Preferably, A 51 =2°, B 51 =0.1mm.
[0036] Furthermore, in this embodiment, 0≤A 52 ≤5°, 0.1mm≤B 52 ≤0.3mm. Preferably, A 52 =0, B 52 =0.15mm.
[0037] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, should fall within the protection scope of the present invention.
Claims
1. A shallow hole drill bit, comprising a polygonal plate-shaped bit body (1), the bit body (1) being formed by an upper surface (2), a lower surface (3) and a plurality of side surfaces (4) connecting the upper surface (2) and the lower surface (3), characterized in that: Each of the aforementioned side surfaces (4) includes an outer peripheral side surface (41) and an inner peripheral side surface (42). The outer peripheral side surface (41) intersects with the upper surface (2) to form an outer peripheral cutting edge (51), and the inner peripheral side surface (42) intersects with the upper surface (2) to form an inner peripheral cutting edge (52). The outer peripheral cutting edge (51) is away from the axis S1 of the tool holder (6), and the inner peripheral cutting edge (52) is close to the axis S1 of the tool holder (6). The rake angle of the outer peripheral cutting edge (51) is A. 51 The blade width is B 51 The rake angle of the inner circumferential cutting edge (52) is A. 52 The blade width is B 52 A should be satisfied 51 ≥A 52 B 51 <B 52 .
2. The shallow hole drill bit according to claim 1, characterized in that: The side surface (4) also includes a transition surface (43), which intersects with the upper surface (2) to form a transition edge (53). The transition edge (53) is connected between the outer peripheral cutting edge (51) and the inner peripheral cutting edge (52), and the three together form the main cutting edge (5).
3. The shallow hole drill bit according to claim 2, characterized in that: The transition edge (53) is a circular arc transition edge.
4. The shallow hole drill bit according to claim 2, characterized in that: The main cutting edge (5) is provided with multiple main cutting edges (5), which are arranged in a circular array around the axis S2 of the blade body (1).
5. The shallow hole drill bit according to claim 4, characterized in that: Adjacent main cutting edges (5) are connected by a tip arc (7).
6. The shallow hole drill bit according to any one of claims 1 to 5, characterized in that: The back angle values of the outer peripheral cutting edge (51) and the inner peripheral cutting edge (52) are equal and neither is 0.
7. The shallow hole drill bit according to any one of claims 2 to 5, characterized in that: The main cutting edge (5) is made of tungsten-cobalt cemented carbide or tungsten-cobalt-titanium cemented carbide.
8. The shallow hole drill bit according to claim 7, characterized in that: The surface of the main cutting edge (5) is coated with a Ti-Al-N, Ti-Al-Si-N, or Al-Cr-N coating.
9. The shallow hole drill bit according to any one of claims 1 to 5, characterized in that: The 0≤A 51 ≤8°, 0.05mm≤B 51 ≤0.2mm.
10. The shallow hole drill bit according to any one of claims 1 to 5, characterized in that: The 0≤A 52 ≤5°, 0.1mm≤B 52 ≤0.3mm.