Stepped hole milling cutter

Abstract

The utility model belongs to the technical field of airplanes, and discloses a stepped hole milling cutter which comprises a cutter part, a neck part and a cutter handle which are sequentially connected, the cutter part is provided with a plurality of cutting edges which are arranged at intervals in the circumferential direction of the cutter part, and a spiral groove is formed between every two adjacent cutting edges. Each cutting edge comprises a first cutting part, a second cutting part and a third cutting part, the third cutting part is arranged close to the neck part, the diameter of the third cutting part is larger than that of the second cutting part, and the diameter of the second cutting part is larger than that of the first cutting part; a first groove is formed between the first cutting part and the second cutting part, a second groove is formed between the second cutting part and the third cutting part, and each of the first cutting part, the second cutting part and the third cutting part comprises an end edge, a tool nose and a spiral side edge. The stepped hole milling cutter is small in abrasion in the machining process and long in service life.

Description

Technical Field

[0001] This utility model relates to the field of aircraft manufacturing technology, and in particular to a stepped milling tool. Background Technology

[0002] Currently, fiber-reinforced composite materials are widely used in large civil aircraft, and the amount of composite materials used has become an important indicator for measuring aircraft performance. However, composite materials need to be connected with other structures during application. Therefore, a large number of composite material connection holes of various sizes and models need to be processed in aircraft, which places extremely high demands on the precision and quality of hole making to ensure the service performance of aircraft structural components and the safety of the aircraft.

[0003] Composite materials and titanium alloys used in aircraft assembly drilling are difficult to machine. Traditional drilling processes for large-diameter holes require a complex "drilling-multi-step reaming-boring" process. The helical milling process, however, uses an end mill that rotates at high speed while feeding along a helical path, milling a hole with a diameter larger than the milling cutter itself. The hole diameter equals the cutter diameter plus the diameter of the helical feed path. This process offers significant advantages for machining larger diameter holes, greatly reducing the number of tools required, significantly increasing machining efficiency, and significantly lowering the manufacturing cost per hole.

[0004] Currently, in spiral milling, the cutting tool is subjected to both axial and radial forces. The large amount of material removed in a single pass leads to rapid tool wear, increased radial force, and more severe tool deflection, resulting in a faster reduction in the machined hole diameter. Since the number of holes machined is relatively small and the tool life is short, it is necessary to design a tool structure that reduces tool wear and significantly improves tool life. Utility Model Content

[0005] The purpose of this invention is to provide a stepped milling tool that has less wear and a longer service life.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This utility model discloses a stepped milling tool, which includes a cutting section, a neck, and a shank connected in sequence. The cutting section has multiple cutting edges spaced apart along its circumference, and a helical groove is formed between two adjacent cutting edges. Each cutting edge includes a first cutting portion, a second cutting portion, and a third cutting portion. The third cutting portion is located close to the neck, and the diameter of the third cutting portion is larger than the diameter of the second cutting portion, which is larger than the diameter of the first cutting portion. A first groove is provided between the first cutting portion and the second cutting portion, and a second groove is provided between the second cutting portion and the third cutting portion. The first cutting portion, the second cutting portion, and the third cutting portion all include an end edge, a tool tip, and a helical side edge.

[0008] In some embodiments, the diameter of the first cutting part is D1, and the diameter of the second cutting part is D2, and D1 and D2 satisfy the relationship: 1mm≤D2-D1≤1.4mm.

[0009] In some embodiments, the diameter of the second cutting part is D2, and the diameter of the third cutting part is D3, wherein D3 and D2 satisfy the relationship: 0.6mm≤D3-D2≤0.8mm.

[0010] In some embodiments, the diameter of the third cutting part is D3, and the diameter of the machined hole of the stepped milling tool is Dk. D3 and Dk satisfy the relationship: 1 / 2Dk < D3 < Dk.

[0011] In some embodiments, the first cutting portion includes a first end edge and a first helical side edge, with a first cutting tip formed at the junction of the first end edge and the first helical side edge; the second cutting portion includes a second end edge and a second helical side edge, with a second cutting tip formed at the junction of the second end edge and the second helical side edge; the third cutting portion includes a third end edge and a third helical side edge, with a third cutting tip formed at the junction of the third end edge and the third helical side edge; wherein: the radius of the first cutting tip is 0.45mm-0.55mm; and / or, the radius of the second cutting tip is 0.25mm-0.35mm; and / or, the radius of the third cutting tip is 0.095mm-0.15mm.

[0012] In some specific embodiments, the axial length of the second end blade along the cutting portion is greater than the difference between the radius of the second cutting portion and the radius of the first cutting portion.

[0013] In some specific embodiments, the axial length of the third end blade along the cutting portion is greater than the difference between the radius of the third cutting portion and the radius of the second cutting portion.

[0014] In some specific embodiments, each cutting edge further includes a rear cutting portion connected to the third helical side edge, the rear cutting portion including a rear cutting edge connected to the third helical side edge, and the junction of the rear cutting edge and the third helical side edge forming a rear cutting tip; wherein: the plane where the rear cutting edge is located is arranged parallel to the plane where the third cutting edge is located.

[0015] In some more specific embodiments, the axial length of the rear cutting edge along the cutting portion is greater than the difference between the radius of the third cutting portion and the radius of the neck.

[0016] In some embodiments, the diameter of the third cutting part is D3, and the diameter of the neck is Dj, where D3 and Dj satisfy the relationship: 0.2mm≤D3-Dj≤1mm.

[0017] The beneficial effects of this stepped milling cutter are as follows: Because a first groove is provided between the first and second cutting parts, and a second groove is provided between the second and third cutting parts, each cutting edge forms a three-step structure in the axial direction of the cutting part. This axially stepped cutting edge can distribute the force in the cutting depth direction, reduce local cutting force, and suppress defects such as delamination and splitting of composite materials at the exit. Because the diameter of the third cutting part is larger than the diameter of the second cutting part, and the diameter of the second cutting part is larger than the diameter of the first cutting part, each cutting edge forms a three-step structure in the radial direction of the cutting part. This radially stepped cutting edge distributes the material removal amount, thereby reducing the wear of the stepped milling cutter caused by concentrated cutting force, improving the problem of significant hole diameter reduction caused by excessive wear of the stepped milling cutter, and greatly improving the life of the stepped milling cutter.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the stepped milling tool according to an embodiment of the present invention;

[0020] Figure 2 This is a partial structural schematic diagram of a stepped milling tool according to an embodiment of the present invention;

[0021] Figure label:

[0022] 100. Cutting section; 110. First cutting section; 111. First end edge; 112. First cutting tip; 113. First helical side edge; 120. Second cutting section; 121. Second end edge; 122. Second cutting tip; 123. Second helical side edge; 130. Third cutting section; 131. Third end edge; 132. Third cutting tip; 133. Third helical side edge; 140. Helical groove; 150. First groove; 160. Second groove; 170. Rear end cutting section; 171. Rear end edge; 172. Rear end tip;

[0023] 200, neck; 300, handle. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0025] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" 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 based on the specific circumstances.

[0026] In the description of this embodiment, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0027] This utility model discloses a stepped milling tool, referenced Figure 1As shown, the stepped milling cutter of this utility model includes a cutting section 100, a neck 200, and a shank 300 connected in sequence. The cutting section 100 has a plurality of cutting edges spaced apart along its circumference. A helical groove 140 is formed between two adjacent cutting edges. Each cutting edge includes a first cutting part 110, a second cutting part 120, and a third cutting part 130. The third cutting part 130 is located close to the neck 200. The diameter of the third cutting part 130 is larger than the diameter of the second cutting part 120, and the diameter of the second cutting part 120 is larger than the diameter of the first cutting part 110. A first groove 150 is provided between the first cutting part 110 and the second cutting part 120, and a second groove 160 is provided between the second cutting part 120 and the third cutting part 130. The first cutting part 110, the second cutting part 120, and the third cutting part 130 all include an end edge, a tool tip, and a helical side edge. It is understandable that, due to the presence of a first groove 150 between the first cutting part 110 and the second cutting part 120, and a second groove 160 between the second cutting part 120 and the third cutting part 130, each cutting edge forms a three-step structure in the axial direction of the cutting part 100. This axially stepped cutting edge can distribute the force in the cutting depth direction, reduce local cutting force, and suppress defects such as delamination and splitting of composite materials at the exit. Since the diameter of the third cutting part 130 is larger than the diameter of the second cutting part 120, and the diameter of the second cutting part 120 is larger than the diameter of the first cutting part 110, each cutting edge forms a three-step structure in the radial direction of the cutting part 100. This radially stepped cutting edge distributes the material removal amount, thereby reducing the wear of the stepped milling tool caused by the concentration of cutting force, improving the problem of significant hole diameter reduction caused by excessive wear of the stepped milling tool, and greatly improving the life of the stepped milling tool.

[0028] Optionally, the diameter of the first cutting part 110 is D1, and the diameter of the second cutting part 120 is D2, where D1 and D2 satisfy the relationship: 1mm ≤ D2 - D1 ≤ 1.4mm. Specifically, the difference between the diameter D2 of the second cutting part 120 and the diameter D1 of the first cutting part 110 can be 1mm, 1.01mm, 1.02mm, 1.03mm, 1.04mm, 1.05mm, 1.06mm, 1.07mm, 1.08mm, 1.09mm, 1.1mm, 1.11mm, 1.12mm, 1.13mm, 1.14mm, 1.15mm, 1.16mm, or 1.17mm. The diameters are 1.18mm, 1.19mm, 1.2mm, 1.21mm, 1.22mm, 1.23mm, 1.24mm, 1.25mm, 1.26mm, 1.27mm, 1.28mm, 1.29mm, 1.3mm, 1.31mm, 1.32mm, 1.33mm, 1.34mm, 1.35mm, 1.36mm, 1.37mm, 1.38mm, 1.39mm, and 1.4mm. Of course, the difference between the diameter D2 of the second cutting part 120 and the diameter D1 of the first cutting part 110 can also be other values ​​within the range of 1mm to 1.4mm, and is not limited to the examples mentioned above. It should be noted that in actual machining, if the difference between the diameter D2 of the second cutting part 120 and the diameter D1 of the first cutting part 110 is too small or too large, it will increase the wear of the stepped milling tool during operation and increase the manufacturing difficulty of the stepped milling tool. In this embodiment, the difference between the diameter D2 of the second cutting part 120 and the diameter D1 of the first cutting part 110 is controlled within the range of 1mm-1.4mm. On the one hand, this can reduce the wear of the stepped milling tool during operation, and on the other hand, it can reduce the manufacturing difficulty of the stepped milling tool, thereby reducing the manufacturing cost of the stepped milling tool.

[0029] Optionally, the diameter of the second cutting part 120 is D2, and the diameter of the third cutting part 130 is D3, where D3 and D2 satisfy the relationship: 0.6mm ≤ D3 - D2 ≤ 0.8mm. Specifically, the difference between the diameter D3 of the third cutting part 130 and the diameter D2 of the second cutting part 120 can be 0.6mm, 0.61mm, 0.62mm, 0.63mm, 0.64mm, 0.65mm, 0.66mm, 0.67mm, 0.68mm, 0.69mm, 0.7mm, 0.71mm, 0.72mm, 0.73mm, 0.74mm, 0.75mm, 0.76mm, 0.77mm, 0.78mm, 0.79mm, or 0.8mm. Of course, the difference between the diameter D3 of the third cutting part 130 and the diameter D2 of the second cutting part 120 can also be other values ​​within the range of 1mm to 1.4mm, and is not limited to the examples above. It should be noted that in actual machining, if the difference between the diameter D3 of the third cutting part 130 and the diameter D2 of the second cutting part 120 is too small or too large, it will increase the wear of the stepped milling tool during operation and increase the manufacturing difficulty of the stepped milling tool. In this embodiment, the difference between the diameter D3 of the third cutting part 130 and the diameter D2 of the second cutting part 120 is controlled within the range of 1mm-1.4mm. On the one hand, this can reduce the wear of the stepped milling tool during operation, and on the other hand, it can reduce the manufacturing difficulty of the stepped milling tool, thereby reducing the manufacturing cost of the stepped milling tool.

[0030] Optionally, the diameter of the third cutting part 130 is D3, and the diameter of the machined hole of the stepped milling tool is Dk, where D3 and Dk satisfy the relationship: 1 / 2Dk < D3 < Dk. It can be understood that the ratio of the diameter of the third cutting part 130 (D3) to the diameter of the machined hole (Dk) can be 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, or 0.71. The values ​​are: 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99. Of course, the ratio of the diameter of the third cutting part 130 (D3) to the diameter of the machined hole (Dk) can also be selected from other values ​​within the range of 0.5-1 (excluding 0.5 and 1). It is understandable that if the ratio of the diameter of the third cutting part 130, D3, to the diameter of the machined hole, Dk, is too large or too small, it will not be conducive to the normal machining of the machined hole. In this embodiment, the ratio of the diameter of the third cutting part 130, D3, to the diameter of the machined hole, Dk, is controlled within the range of 0.5-1 (excluding 0.5 and 1), which can facilitate the normal machining of the machined hole.

[0031] Optional, see reference Figure 2 As shown, the first cutting section 110 includes a first end edge 111 and a first helical side edge 113, with a first cutting tip 112 formed at the junction of the first end edge 111 and the first helical side edge 113; the second cutting section 120 includes a second end edge 121 and a second helical side edge 123, with a second cutting tip 122 formed at the junction of the second end edge 121 and the second helical side edge 123; the third cutting section 130 includes a third end edge 131 and a third helical side edge 133, with a third cutting tip 132 formed at the junction of the third end edge 131 and the third helical side edge 133. Specifically, the cutter section 100 of this embodiment has four cutting edges spaced apart circumferentially, and the end edges of the four cutting edges are located in the same plane. That is, the four first end edges 111 are located in the same plane, the four second end edges 121 are located in the same plane, and the four third end edges 131 are located in the same plane.

[0032] Optionally, the radius of the first cutting tip 112 is 0.45mm-0.55mm. Specifically, the radius of the first cutting tip 112 can be 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, or 0.55mm. Of course, it can also be other values ​​within the range of 0.45mm-0.55mm, and is not limited to the examples above. Furthermore, in other embodiments of this utility model, the radius of the first cutting tip 112 can be selected according to actual needs.

[0033] Optionally, the radius of the second cutting tip 122 is 0.25mm-0.35mm. The radius of the second cutting tip 122 can be 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, or 0.35mm. Of course, other values ​​within the range of 0.25mm-0.35mm are also possible, and it is not limited to the examples mentioned above. Furthermore, in other embodiments of this utility model, the radius of the second cutting tip 122 can be selected according to actual needs.

[0034] Optionally, the radius of the third cutting tip 132 is 0.095mm-0.15mm. Specifically, the radius of the third cutting tip 132 can be 0.095mm, 0.096mm, 0.097mm, 0.098mm, 0.099mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, or 0.15mm. Of course, it can also be other values ​​within the range of 0.095mm-0.15mm, and is not limited to the examples above. Furthermore, in other embodiments of this utility model, the radius of the third cutting tip 132 can be selected according to actual needs.

[0035] Optionally, the axial length of the second end cutting edge 121 along the cutting portion 100 is greater than the difference between the radius of the second cutting portion 120 and the radius of the first cutting portion 110. Therefore, the first cutting portion 110 and the second cutting portion 120 can effectively provide radially and axially stepped cutting edges, thereby reducing local cutting forces and suppressing defects such as delamination and splitting at the composite material exit point. Furthermore, it reduces cutting edge wear caused by concentrated cutting forces, mitigating the problem of significant hole diameter reduction due to excessively rapid cutting edge wear.

[0036] Optionally, the axial length of the third end cutting edge 131 along the cutting portion 100 is greater than the difference between the radius of the third cutting portion 130 and the radius of the second cutting portion 120. Therefore, the second cutting portion 120 and the third cutting portion 130 can effectively provide radially and axially stepped cutting edges, thereby reducing local cutting forces and suppressing defects such as delamination and splitting at the composite material exit point. Furthermore, it reduces cutting edge wear caused by concentrated cutting forces, mitigating the problem of significant hole diameter reduction due to excessively rapid cutting edge wear.

[0037] Optionally, each cutting edge further includes a rear-end cutting portion 170 connected to the third helical side edge 133. The rear-end cutting portion 170 includes a rear-end cutting edge 171 connected to the third helical side edge 133, and a rear-end cutting tip 172 is formed at the junction of the rear-end cutting edge 171 and the third helical side edge 133. The plane containing the rear-end cutting edge 171 is parallel to the plane containing the third end edge 131. It is understood that during tool retraction, the added rear-end cutting portion 170 can perform minor removal on the machined surface, improving the inner surface quality of the machined hole.

[0038] Optionally, the axial length of the rear cutting edge 171 along the cutting portion 100 is greater than the difference between the radius of the third cutting portion 130 and the radius of the neck 200. This enhances the ability of the rear cutting portion 170 to remove minute amounts of material from the machined surface, thereby further improving the inner surface quality of the machined hole.

[0039] Optionally, the diameter of the third cutting section 130 is D3, and the diameter of the neck 200 is Dj, where D3 and Dj satisfy the relationship: 0.2mm ≤ D3 - Dj ≤ 1mm. Specifically, the difference between the diameter D3 of the third cutting section 130 and the diameter Dj of the neck 200 can be 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, or 1mm. It can also be other values ​​within the range of 0.2mm to 1mm, and is not limited to the examples mentioned above. If the difference between the diameter D3 of the third cutting part 130 and the diameter Dj of the neck 200 is too large or too small, it will increase the wear of the stepped milling tool during operation and increase the manufacturing difficulty of the stepped milling tool. In this embodiment, the diameter D3 of the third cutting part 130 and the diameter Dj of the neck 200 are controlled within the range of 0.2mm-1mm. On the one hand, this can reduce the wear of the stepped milling tool during operation, and on the other hand, it can reduce the manufacturing difficulty of the stepped milling tool, thereby reducing the manufacturing cost of the stepped milling tool.

[0040] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A stepped milling cutter, comprising a cutting section (100), a neck (200), and a shank (300) connected in sequence, wherein the cutting section (100) has a plurality of cutting edges spaced apart circumferentially thereon, and a helical groove (140) is formed between two adjacent cutting edges, characterized in that, Each of the cutting edges includes a first cutting portion (110), a second cutting portion (120), and a third cutting portion (130). The third cutting portion (130) is disposed near the neck (200). The diameter of the third cutting portion (130) is larger than the diameter of the second cutting portion (120), and the diameter of the second cutting portion (120) is larger than the diameter of the first cutting portion (110). A first groove (150) is provided between the first cutting portion (110) and the second cutting portion (120), and a second groove (160) is provided between the second cutting portion (120) and the third cutting portion (130). The first cutting portion (110), the second cutting portion (120), and the third cutting portion (130) all include an end edge, a blade tip, and a helical side edge.

2. The stepped milling tool according to claim 1, characterized in that, The diameter of the first cutting part (110) is D1, and the diameter of the second cutting part (120) is D2. D1 and D2 satisfy the relationship: 1mm≤D2-D1≤1.4mm.

3. The stepped milling tool according to claim 1, characterized in that, The diameter of the second cutting part (120) is D2, and the diameter of the third cutting part (130) is D3. D3 and D2 satisfy the relationship: 0.6mm≤D3-D2≤0.8mm.

4. The stepped milling tool according to claim 1, characterized in that, The diameter of the third cutting part (130) is D3, and the diameter of the machined hole of the stepped milling tool is Dk. D3 and Dk satisfy the relationship: 1 / 2Dk<D3<Dk.

5. The stepped milling tool according to any one of claims 1-4, characterized in that, The first cutting part (110) includes a first end cutting edge (111) and a first helical side cutting edge (113), and a first cutting tip (112) is formed at the junction of the first end cutting edge (111) and the first helical side cutting edge (113); The second cutting part (120) includes a second end cutting edge (121) and a second helical side cutting edge (123), and a second cutting tip (122) is formed at the junction of the second end cutting edge (121) and the second helical side cutting edge (123); The third cutting section (130) includes a third end cutting edge (131) and a third helical side cutting edge (133), and a third cutting tip (132) is formed at the junction of the third end cutting edge (131) and the third helical side cutting edge (133); wherein: The radius of the first cutting tip (112) is 0.45mm-0.55mm; and / or, The radius of the second cutting tip (122) is 0.25mm-0.35mm; and / or, The radius of the third cutting tip (132) is 0.095mm-0.15mm.

6. The stepped milling tool according to claim 5, characterized in that, The second end blade (121) has an axial length greater than the difference between the radius of the second cutting part (120) and the radius of the first cutting part (110) along the cutting part (100).

7. The stepped milling tool according to claim 5, characterized in that, The length of the third end blade (131) along the axial direction of the cutting portion (100) is greater than the difference between the radius of the third cutting portion (130) and the radius of the second cutting portion (120).

8. The stepped milling tool according to claim 5, characterized in that, Each of the cutting edges further includes a rear cutting portion (170) connected to the third helical side edge (133), the rear cutting portion (170) including a rear cutting edge (171) connected to the third helical side edge (133), and a rear cutting tip (172) is formed at the junction of the rear cutting edge (171) and the third helical side edge (133); wherein: The plane containing the rear end blade (171) is parallel to the plane containing the third end blade (131).

9. The stepped milling tool according to claim 8, characterized in that, The axial length of the rear cutting edge (171) along the cutting portion (100) is greater than the difference between the radius of the third cutting portion (130) and the radius of the neck (200).

10. The stepped milling tool according to any one of claims 1-4, characterized in that, The diameter of the third cutting part (130) is D3, and the diameter of the neck (200) is Dj. D3 and Dj satisfy the relationship: 0.2mm≤D3-Dj≤1mm.

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