Round nose milling cutter

Abstract

A round nose milling cutter comprises a cutter bar and a cutter head made of cubic boron nitride materials, the cutter head is provided with a welding area, the maximum size of the welding area is smaller than the diameter of the cutter bar, and the welding area is welded to the cutter bar in a vacuum welding mode. Wherein the cutter head is provided with a protruding face which protrudes outwards towards the side away from the cutter bar, a first cutting edge coinciding with the center line of the cutter bar is formed on the protruding face, and the ratio of the width of the first cutting edge to the length of the first cutting edge is larger than or equal to 0.07 and smaller than or equal to 0.09.

Description

TECHNICAL FIELD

[0001] The utility model relates to milling cutter technical field especially relates to a round nose milling cutter. BACKGROUND

[0002] With the requirement of machining efficiency and precision of mechanical manufacturing industry is higher and higher, the requirement of cutting tool is also more and more strict, the strength and service life of cutting tool determine the error size and precision level of workpiece.

[0003] However, the cutting tool of traditional mould cavity processing generally adopts the milling cutter of hard alloy, and the milling cutter of hard alloy must be added cutting fluid in the whole process, which can cause the dirty phenomenon of working site, and the waste cutting fluid is discharged into the nature, which can cause great damage to ecological environment, and the temperature of cutting edge in the processing process is also very high, which can make the hard alloy cutting tool wear too fast and cause the service life to be generally low. SUMMARY

[0004] The utility model provides a round nose milling cutter, aims at at least solve one of prior art existing technical problems.

[0005] The utility model provides a round nose milling cutter, including the cutter bar and the cutter head made of cubic boron nitride material, the cutter head has the welding area of maximum size less than the diameter of the cutter bar, the welding area is welded on the cutter bar through the mode of vacuum welding,

[0006] Among them, the cutter head has the convex surface outwardly convexly arranged towards the side away from the cutter bar, the convex surface is formed with the first cutting edge coinciding with the center line of the cutter bar, the ratio of the width of the first cutting edge to the length of the first cutting edge is greater than or equal to 0.07 and less than or equal to 0.09.

[0007] In the round nose milling cutter of one embodiment of the utility model, the projection shape of the plane of the cutter head towards the side of the cutter bar is quadrilateral, the cutter head has the first diagonal line and the second diagonal line intersecting, and the geometric center of the intersection area of the first diagonal line and the second diagonal line coincides with the geometric center of the cutter bar.

[0008] In the round nose milling cutter of one embodiment of the utility model, the first diagonal line and the second diagonal line are orthogonally arranged, and the length of the first diagonal line is greater than the length of the second diagonal line, and the first cutting edge extends along the length direction of the first diagonal line.

[0009] In the round nose milling cutter of one embodiment of the utility model, the ratio of the length of the first diagonal line to the length of the second diagonal line is greater than or equal to 1.1 and less than or equal to 1.2.

[0010] In the round nose cutter of the utility model, the tool head is formed with a second cutting edge and a third cutting edge on opposite sides of the first diagonal line, and the first cutting edge is formed with a first circular arc angle at both ends thereof respectively with the second cutting edge and the third cutting edge.

[0011] In the round nose cutter of the utility model, the ratio of the radius of the first circular arc angle to the length of the first cutting edge is greater than or equal to 0.07 and less than or equal to 0.09.

[0012] In the round nose cutter of the utility model, the length of the second cutting edge is equal to the length of the third cutting edge, and the ratio of the length of the first cutting edge to the length of the second cutting edge or the length of the third cutting edge is greater than or equal to 1.2 and less than or equal to 1.3.

[0013] In the round nose cutter of the utility model, the length of the first cutting edge is greater than or equal to 0.5mm and less than or equal to 8mm; and / or,

[0014] the length of the second cutting edge is greater than or equal to 1mm and less than or equal to 3mm; and / or,

[0015] the radius of the first circular arc angle is greater than or equal to 0.1mm and less than or equal to 0.5mm.

[0016] In the round nose cutter of the utility model, the first cutting edge is formed with a first clearance face and a second clearance face on both sides thereof, the first clearance face is formed on both sides of the first cutting edge, and the second clearance face is connected to one side of the first clearance face away from the first cutting edge.

[0017] In the round nose cutter of the utility model, the included angle a between the first clearance face and a perpendicular line perpendicular to the tool head in the axial direction is greater than or equal to 40° and less than or equal to 45°; and / or,

[0018] the included angle β between the second clearance face and a perpendicular line perpendicular to the tool head in the axial direction is greater than or equal to 50° and less than or equal to 60°.

[0019] The technical scheme provided by the embodiment of the application can have the following beneficial effects: the application designs a round nose milling cutter, which comprises a cutter bar and a cutter head, the cutter head is made of cubic boron nitride material and is welded on the cutter bar by a vacuum welding method, so that the welding strength between the cutter head and the cutter bar can be ensured, and the influence of welding on the performance of the cutter head is reduced; moreover, the cubic boron nitride material has excellent wear resistance and high-temperature stability, so that cutting fluid does not need to be used in the machining process, the environment can be kept clean, the heat conduction performance is excellent compared with a hard alloy cutter, the damage of heat to a workpiece is reduced, the service life is longer, and the machining efficiency is higher. The first cutting edge is coincident with the center line of the cutter bar, and the ratio of the width of the first cutting edge to the length of the first cutting edge is greater than or equal to 0.07 and less than or equal to 0.09, so that the stability and precision in the cutting process can be ensured, and the strength and cutting efficiency of the cutting edge can be balanced, so that the cutting performance can be kept good while the cutting force is borne in the machining process.

[0020] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 is a structural schematic view of the round nose milling cutter in the first angle provided by an embodiment of the application;

[0023] Figure 2 is Figure 1 a structural schematic view of the round nose milling cutter in the second angle in the embodiment;

[0024] Figure 3 is Figure 1 a structural schematic view of the round nose milling cutter in the third angle in the embodiment;

[0025] Figure 4 is Figure 1 a structural schematic view of the round nose milling cutter in the fourth angle in the embodiment;

[0026] Figure 5 is Figure 1 a structural schematic view of the round nose milling cutter in the fifth angle in the embodiment;

[0027] Figure 6 is Figure 1 an exploded schematic view of the round nose milling cutter in the embodiment.

[0028] Reference numerals:

[0029] 10, tool head; 10a, first cutting edge; 10b, second cutting edge; 10c, third cutting edge; 10d, welding area; 11, first clearance face; 12, second clearance face; 13, first diagonal line; 14, second diagonal line; 15, first circular arc angle;

[0030] 20, tool bar; 21, tool neck. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0032] It should also be understood that the terms used in this present application specification are merely used for the purpose of describing specific embodiments of the present application in the description of the present application. It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship shown in the drawings, and are merely used for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are used for the purpose of description only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0033] Some embodiments of the present application will be described in detail below with reference to the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] As Figures 1 to 6As shown, the present application provides a round nose milling cutter, comprising a cutter bar 20 and a cutter head 10, the cutter head 10 is made of cubic boron nitride material and is welded on the cutter bar 20 by vacuum welding, so as to not only ensure the welding strength between the cutter head 10 and the cutter bar 20 and reduce the influence of welding on the performance of the cutter head 10, but also the cubic boron nitride material has excellent wear resistance and high temperature stability, so that cutting fluid is not needed in the machining process, which is conducive to keeping the environment clean, and the round nose milling cutter made of hard alloy has excellent heat conduction performance, reduces the damage of heat to the workpiece, has a longer service life and higher machining efficiency.

[0035] In an optional embodiment, the cutter head 10 has a welding area 10d with a maximum size smaller than the diameter of the cutter bar 20, and the welding area 10d is welded on the cutter bar 20 by vacuum welding, so as to ensure the welding strength and reduce the influence of welding on the performance of the cutter head 10. The vacuum welding is a high-precision welding method, which can be used for welding in an oxygen-free environment to avoid the influence of oxidation and impurities and ensure the high strength and stability of the welding area 10d.

[0036] In an optional embodiment, the cutter bar 20 has a main body and a cutter neck 21 serving as a connecting support, the diameter of the cutter neck 21 is smaller than that of the main body, and the welding area 10d is welded on the cutter neck 21 by vacuum welding, so as to not only reduce the weight of the round nose milling cutter, but also optimize the stress distribution of the welding area 10d and ensure the reliability of the welding connection. The main body can provide sufficient rigidity and stability for the ball nose cutter to support the stress of the entire round nose milling cutter during the machining process.

[0037] In an optional embodiment, the cutter head 10 has a convex surface outwardly protruding towards the side away from the cutter bar 20, and the convex surface is formed with a first cutting edge 10a coinciding with the center line of the cutter bar 20, so as to ensure the stability and accuracy during cutting. The ratio of the width W of the first cutting edge 10a to the length L1 of the first cutting edge 10a is greater than or equal to 0.07 and less than or equal to 0.09, so as to not only balance the strength and cutting efficiency of the first cutting edge 10a, but also ensure that the first cutting edge 10a can withstand a larger cutting force and maintain good cutting performance during the machining process, so that it can perform well in a high-load and high-precision machining environment, and is especially suitable for occasions requiring high surface quality and dimensional accuracy.

[0038] In an optional embodiment, the projection shape of the cutter head 10 on the plane towards the cutter bar 20 is a quadrilateral, the cutter head 10 has a first diagonal line 13 and a second diagonal line 14 intersecting each other, and the geometric center of the intersection area of the first diagonal line 13 and the second diagonal line 14 coincides with the geometric center of the cutter bar 20, which not only ensures the uniform mass distribution of the cutter head 10, reduces vibration during high-speed rotation, and improves machining precision and surface quality, but also ensures the dynamic balance of the cutter during high-speed rotation, reduces vibration and noise, and prolongs the service life of the cutter. Among them, the cutter head 10 is a symmetrical quadrilateral, which can uniformly distribute the cutting force of the cutter head 10 during machining, reduce local stress concentration, and improve the durability of the cutter.

[0039] After adopting the above technical scheme, since the geometric center of the intersection area of the first diagonal line 13 and the second diagonal line 14 coincides with the geometric center of the cutter bar 20, the structural stability of the cutter head 10 can be further enhanced, so that it can withstand greater cutting force during cutting, which is suitable for high-load machining; at the same time, the transmission path of the cutting force is consistent with the center of the cutter bar 20, the eccentric moment is reduced, the requirements of high surface quality and dimensional accuracy are met, and the machining precision is improved.

[0040] In an optional embodiment, the first diagonal line 13 and the second diagonal line 14 are arranged orthogonally, i.e., the first diagonal line 13 and the second diagonal line 14 are perpendicular and intersect at 90 degrees, which can enhance the structural symmetry and stability of the cutter head 10, and can uniformly distribute the cutting force, so that the cutter head 10 can better resist radial and axial cutting forces during cutting, and improve the rigidity and durability of the cutter. Among them, the length of the first diagonal line 13 is greater than the length of the second diagonal line 14, and the first cutting edge 10a extends along the length direction of the first diagonal line 13, so that the cutting force distribution of the first cutting edge 10a during machining can be optimized by the asymmetric first diagonal line 13 and the second diagonal line 14, the local stress concentration is reduced, and the service life of the cutter is prolonged; also, the length of the first cutting edge 10a is maximized, which can cover a larger cutting area and improve cutting efficiency.

[0041] In an optional embodiment, the ratio of the length of the first diagonal line 13 to the length of the second diagonal line 14 is greater than or equal to 1.1 and less than or equal to 1.2, so that the first cutting edge 10a can cover a larger cutting area, and at the same time, the second diagonal line 14 is shorter, providing necessary support and balance to ensure uniform distribution of cutting force, and further enhancing the rigidity and anti-vibration performance of the cutter head 10, which is suitable for high-load machining.

[0042] By adopting the above technical solutions, the ratio of the length of the first diagonal line 13 to the length of the second diagonal line 14 is between 1.1 and 1.2, which not only enables the tool head 10 to better resist the radial and axial cutting forces during cutting, reduces local stress concentration, and prolongs the tool life, but also enhances the symmetry and stability of the tool head 10, ensures that the transmission path of the cutting force is consistent with the center of the tool shank 20, reduces the eccentric moment, improves the machining precision, and is suitable for high-speed machining.

[0043] In an optional embodiment, the tool head 10 is formed with a second cutting edge 10b and a third cutting edge 10c on opposite sides of the first diagonal line 13, so that the tool head 10 has multiple cutting edges that can participate in cutting at the same time, improving the cutting efficiency. The first cutting edge 10a is formed with a first circular arc angle 15 at both ends thereof with respect to the second cutting edge 10b and the third cutting edge 10c, which not only enables smooth transition of the cutting force, reduces stress concentration at the connection of the cutting edges, prolongs the tool life, but also facilitates smooth discharge of the chips, avoids chip accumulation affecting the machining quality, makes the cutting process more stable, and reduces burrs and roughness on the machined surface.

[0044] In an optional embodiment, the ratio of the radius of the first circular arc angle 15 to the length L1 of the first cutting edge 10a is greater than or equal to 0.07 and less than or equal to 0.09, which not only enables smooth transition of the cutting force, reduces stress concentration, prolongs the tool life, but also reduces vibration and impact during cutting, improves the smoothness of the machined surface, facilitates smooth discharge of the chips, and avoids chip accumulation affecting the machining quality.

[0045] By adopting the above technical solutions, since the first cutting edge 10a is connected to the second cutting edge 10b and the third cutting edge 10c through the first circular arc angle 15, and the ratio of the radius of the first circular arc angle 15 to the length of the first cutting edge 10a is between 0.07 and 0.09, the stress distribution at the connection of the cutting edges is more uniform, local stress concentration is reduced, the tool durability is improved, the cutting process is more stable, the burrs and roughness on the machined surface are reduced, and the machining precision is improved. The circular arc angle can also absorb part of the cutting vibration and improve the machining stability.

[0046] In an optional embodiment, the length L2 of the second cutting edge 10b is equal to the length of the third cutting edge 10c, and the ratio of the length L1 of the first cutting edge 10a to the length L2 of the second cutting edge 10b or the length of the third cutting edge 10c is greater than or equal to 1.2 and less than or equal to 1.3. Not only can this ensure the mechanical balance of the tool head 10 during cutting, reducing vibration and eccentric torque, but also can make the cutting force distribution more uniform through the symmetrical second cutting edge 10b and third cutting edge 10c, improving the machining stability and surface quality.

[0047] After adopting the above technical scheme, the length of the first cutting edge 10a is longer, which can cover a larger cutting area and improve the cutting efficiency. Meanwhile, the lengths of the second cutting edge 10b and the third cutting edge 10c are equal, which can provide symmetrical support and balance, ensure the stability of the cutting process and the uniform distribution of the cutting force, reduce vibration, noise and local stress concentration, improve the machining precision, and prolong the tool life.

[0048] In an optional embodiment, the length L1 of the first cutting edge 10a is greater than or equal to 0.5 mm and less than or equal to 8 mm, so as to adapt to different machining requirements from small-size precision machining to medium-size high-efficiency cutting. When the length L1 of the first cutting edge 10a is in the range of 0.5 mm to 2 mm, fine cutting can be realized, the surface finish and dimensional accuracy of the machined surface can be improved, and the tool head can be suitable for machining of high-precision and small features, such as precision molds and electronic parts. When the length L1 of the first cutting edge 10a is in the range of 2 mm to 8 mm, the first cutting edge 10a can cover a larger cutting area, improve the cutting efficiency, and maintain high machining precision, and the tool head can be suitable for high-efficiency machining of medium-size parts, such as ordinary molds and mechanical parts. Therefore, by limiting the length of the first cutting edge 10a to be between 0.5 mm and 8 mm, the tool head can adapt to various machining requirements from small parts to medium-size parts, has high versatility, and can realize machining of various parts from small parts to medium-size parts.

[0049] In an optional embodiment, the length of the second cutting edge 10b and the length of the third cutting edge 10c are greater than or equal to 1 mm and less than or equal to 3 mm, so as to ensure the rigidity and stability of the tool head while ensuring the cutting efficiency, and make the tool head adapt to various machining requirements from small parts to medium-size parts, and have high versatility. The length range of the second cutting edge 10b and the third cutting edge 10c is designed in combination with the length range of the first cutting edge 10a, which ensures the uniform distribution of the cutting force, reduces local stress concentration, and prolongs the tool life.

[0050] In an optional embodiment, the radius of the first circular arc angle 15 is greater than or equal to 0.1 mm and less than or equal to 0.5 mm, so as to be able to optimize the smoothness of the cutting process and the chip removal performance while ensuring the strength of the cutting edge, so that the nose cutter can adapt to various machining requirements from small parts to medium-sized parts, and has high universality. Among them, the small radius circular arc angle can realize fine cutting, improve the smoothness and dimensional accuracy of the machined surface, and the medium radius circular arc angle can cover a larger cutting area, improve the cutting efficiency, and at the same time maintain high machining precision. The radius of the first circular arc angle 15 is set in combination with the length of the first cutting edge 10a, the second cutting edge 10b and the third cutting edge 10c, which can ensure uniform distribution of cutting force, reduce local stress concentration, and prolong tool life.

[0051] In an optional embodiment, the first cutting edge 10a is formed with a first clearance face 11 and a second clearance face 12 on both sides, the first clearance face 11 is formed on both sides of the first cutting edge 10a, and the second clearance face 12 is connected to one side of the first clearance face 11 away from the first cutting edge 10a, so as to be able to reduce the contact area between the cutting edge and the workpiece, reduce friction and heat accumulation, and improve cutting efficiency and tool life. Among them, the first clearance face 11 is formed on both sides of the first cutting edge 10a and directly connected with the cutting edge. The main purpose of this design is to reduce the friction between the cutting edge and the workpiece, improve the cutting efficiency and prolong the tool life; the second clearance face 12 is connected to one side of the first clearance face 11 away from the first cutting edge 10a. This design further reduces the contact area between the tool and the workpiece, reduces friction and heat accumulation, and improves cutting efficiency and tool life. Through the smaller first clearance face 11 and the larger second clearance face 12, the contact area between the cutting edge and the workpiece can be reduced, the friction and heat accumulation can be reduced, the cutting efficiency and tool life can be improved, the cutting process can be more stable, the vibration and impact can be reduced, and the smoothness and dimensional accuracy of the machined surface can be improved. At the same time, the larger angle of the second clearance face 12 can also enhance the chip removal performance and avoid the accumulation of chips affecting the machining quality.

[0052] In an optional embodiment, the included angle α between the first clearance face 11 and the vertical line perpendicular to the axis of the tool head 10 is greater than or equal to 40° and less than or equal to 45°, which not only can reduce the contact area between the cutting edge and the workpiece, reduce friction and heat accumulation, and improve cutting efficiency and tool life, but also can make the cutting process more stable, reduce vibration and impact, and improve the smoothness and dimensional accuracy of the machined surface.

[0053] In an optional embodiment, the included angle β between the second rear corner surface 12 and the perpendicular line of the tool head 10 in the axial direction is greater than or equal to 50° and less than or equal to 60°, which not only can reduce the contact area between the cutting edge and the workpiece, reduce the friction and heat accumulation, improve the cutting efficiency and tool life, but also can make the cutting process more stable, reduce the vibration and impact, and improve the smoothness and dimensional accuracy of the machined surface.

[0054] In an optional embodiment, the tool bar 20 is made of hard alloy, which can effectively reduce the deformation of the tool during cutting, especially in high-speed cutting and high-load machining, ensure the machining accuracy and surface quality, and prolong the service life of the round nose milling cutter.

[0055] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected. It can be mechanical connection, or electrical connection. It can be directly connected, or indirectly connected through an intermediate medium. It can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0057] The above disclosure provides many different embodiments or examples for implementing the different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described in the above. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0058] In the description of the specification, the description using terms such as "one embodiment", "some embodiments", "certain embodiments", "an example", "a specific example" or "some examples" etc. means that the particular feature, structure, material or characteristic being described is included in at least one embodiment or example of the application. The illustrative appearances of the above terms in various places in the specification are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A round nose milling cutter, characterized in that, A tool bar and a tool head made of cubic boron nitride material, the tool head having a welding area with a maximum dimension smaller than a diameter of the tool bar, the welding area being welded to the tool bar by vacuum welding; The tool head has a convex surface outwardly convex toward a side away from the tool bar, the convex surface being formed with a first cutting edge coinciding with a center line of the tool bar, a ratio of a width of the first cutting edge to a length of the first cutting edge being greater than or equal to 0.07 and less than or equal to 0.

09.

2. The ballnose cutter according to claim 1, wherein, A projection shape of the tool head toward a plane of the side of the tool bar is a quadrilateral, the tool head having a first diagonal and a second diagonal intersecting each other, a geometric center of an intersection region of the first diagonal and the second diagonal coinciding with a geometric center of the tool bar.

3. The ballnose cutter according to claim 2, wherein, The first diagonal and the second diagonal are orthogonally arranged, and a length of the first diagonal is greater than a length of the second diagonal, the first cutting edge extending along a length direction of the first diagonal.

4. The ballnose cutter according to claim 2, wherein, A ratio of the length of the first diagonal to the length of the second diagonal is greater than or equal to 1.1 and less than or equal to 1.

2.

5. The ballnose cutter according to claim 2, wherein, The tool head is formed with a second cutting edge and a third cutting edge on opposite sides of the first diagonal, and a first circular-arc corner is formed between each end of the first cutting edge and the second cutting edge or the third cutting edge.

6. The ballnose cutter according to claim 5, wherein, A ratio of a radius of the first circular-arc corner to the length of the first cutting edge is greater than or equal to 0.07 and less than or equal to 0.

09.

7. The ballnose cutter according to claim 5, wherein, A length of the second cutting edge is equal to a length of the third cutting edge, and a ratio of the length of the first cutting edge to the length of the second cutting edge or the length of the third cutting edge is greater than or equal to 1.2 and less than or equal to 1.

3.

8. The ballnose cutter according to claim 5, wherein, The length of the first cutting edge is greater than or equal to 0.5 mm and less than or equal to 8 mm; and / or, The length of the second cutting edge and the length of the third cutting edge are greater than or equal to 1 mm and less than or equal to 3 mm; and / or, The radius of the first circular-arc corner is greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

9. The bullnose cutter according to claim 1, wherein, The first cutting edge is formed with a first clearance face and a second clearance face on both sides of the first cutting edge, the first clearance face being formed on both sides of the first cutting edge, and the second clearance face being connected to the first clearance face on a side away from the first cutting edge.

10. The ballnose cutter according to claim 9, wherein, An included angle a between the first clearance face and a perpendicular line of the tool head perpendicular to an axial direction is greater than or equal to 40° and less than or equal to 45°; and / or, An included angle β between the second clearance face and the perpendicular line of the tool head perpendicular to the axial direction is greater than or equal to 50° and less than or equal to 60°.

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