End mill

Abstract

The invention provides an end mill which comprises a cutter handle part and a milling part, the cutter handle part and the milling part are connected into a whole, the axial end part of one end, far away from the cutter handle part, of the milling part is of an elliptical sphere structure, and the elliptical sphere structure comprises an elliptical arc surface. Complex curved surfaces, spherical surfaces, irregular cambered surfaces and the like can be machined according to the end mill, the machining efficiency is higher than that of an existing spherical end tooth profile end mill, the ratio of the residual height to the spherical surface is lower, the smaller surface residual height can be obtained under the same machining distance, the machining efficiency is obviously improved, and the machining cost is reduced. The problem that the machining efficiency of the end mill is low due to the fact that the surface residual height of an existing end mill is high is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of machine tools, and in particular to an end milling cutter. Background Art

[0002] Structural parts such as aviation and automobiles generally have complex thin-walled cavity structures, many types of curved surfaces, and require high processing accuracy, which puts high demands on the manufacturing process level. Although the ball-end milling cutter, which is widely used in the surface finishing process, has strong versatility, it is limited by its geometric shape and cannot achieve the best effect for the processing of specific surfaces. Therefore, there are common problems such as severe tool wear, low processing efficiency, and difficulty in ensuring surface quality during the processing process, which seriously restrict the processing quality and efficiency of such workpieces. Aiming at the processing conditions of small curvature flat surfaces in structural parts such as aviation and automobiles, in order to improve the cutting performance of the tool end edge, a vertical milling cutter with an elliptical structure of the end edge is proposed in combination with the geometric characteristics of the meshing of the elliptical profile and the curved surface. Ball-end milling cutters are widely used in the processing of small curvature flat surfaces, but when the processing depth is certain, the cutting linear speed of the end edge is low during the processing process. When cutting harder workpieces, the cutting side edge of the tool is severely worn, and the cutting efficiency is also reduced. When machining curved surfaces, the annular milling cutter has a large undercut and a high residual height on the surface, which makes the tool of the next process vibrate easily, causing problems with the machining accuracy of the workpiece surface. The rotary surface profiling milling cutter has certain limitations on the tool diameter for machining small curvature flat surfaces, and there are limitations such as inability to machine special structural positions and low efficiency, and vibration may be generated during the machining process.

[0003] Since the end mills in the prior art have technical problems such as high surface residual height, which leads to low processing efficiency of the end mills, the present invention studies and designs an end mill. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the end mill in the prior art that the surface residual height is high, resulting in low processing efficiency of the end mill, thereby providing an end mill.

[0005] In order to solve the above problems, the present invention provides an end mill, which comprises:

[0006] A tool handle portion and a milling portion, wherein the tool handle portion and the milling portion are connected as a whole, and an axial end portion of the milling portion away from one end of the tool handle portion is an ellipsoidal structure, and the ellipsoidal structure includes an elliptical arc surface.

[0007] In some embodiments,

[0008] The milling part includes a cutting side edge, a chip groove and an end edge. The chip groove is between two adjacent cutting side edges. The end edge is also arranged on the ellipsoidal spherical structure of the milling part away from one end of the shank part. The chip groove extends between two adjacent end edges. The end edge is formed by an orthogonal spiral edge line.

[0009] In some embodiments,

[0010] The end blade has an end blade helix angle β2, and the end blade helix angle refers to the angle formed by the tangent line along the spiral line at any point of the orthogonal spiral blade line and the center axis of the end mill in the axial projection plane of the end mill. At the same tangent contact point, the end blade helix angle β2 of the elliptical end blade profile end mill is larger than the end blade helix angle β1 of the spherical end blade profile end mill.

[0011] In some embodiments,

[0012] The reference plane is perpendicular to the center axis of the end mill at the axial frontmost section of the elliptical arc surface of the milling part, and the angle between the tangent plane at the axial frontmost section of the elliptical arc surface and the reference plane is the actual machining inclination angle θ2. At the same cutting contact point, the actual machining inclination angle θ2 of the end mill with an elliptical end blade profile is smaller than the actual machining inclination angle θ1 of the end mill with a spherical end blade profile.

[0013] In some embodiments,

[0014] The machining residual height of the elliptical end mill is h2, and: The residual height of the spherical end milling cutter is h1, and there are: And h2

[0015] In some embodiments,

[0016] The axial end of the milling portion is within the axial projection plane of the end mill, and the chip groove portion includes a connected curve segment and a straight line segment, one end of the curve segment is connected to an end edge located on the periphery, one end of the straight line segment is connected to the other end of the curve segment, and the other end of the straight line segment is connected to an end edge located on the periphery.

[0017] In some embodiments,

[0018] ​In the axial projection plane of the end mill, the outer circumference of the end cutting edge is an arc segment, and the arc segments of the outer circumference of at least two end cutting edges are located on the same outer circumference circle, and the straight line segment and the curved line segment are located radially inward of the outer circumference circle.

[0019] In some embodiments,

[0020] The connecting end of the straight line segment and the curved line segment is also located radially inward of the outer circle and is spaced from the outer circle by a distance greater than 0;

[0021] The connecting end of the curved segment and the straight segment forms a sharp angle, that is, an angle greater than 0 is formed between the tangent of the curved segment at the connecting end and the straight segment.

[0022] In some embodiments,

[0023] In the circumferential direction of the milling portion, the chip removal grooves are at least two arranged at intervals,

[0024] In the circumferential direction of the milling portion, there are at least two cutting side edges arranged at intervals.

[0025] In some embodiments,

[0026] A clearance portion is also connected between the tool handle portion and the milling portion. The tool handle portion is a cylindrical structure, and the milling portion is also a cylindrical structure. No cutting side edges are arranged on the tool handle portion and the clearance portion.

[0027] The end mill provided by the present invention has the following beneficial effects:

[0028] The present invention sets the axial end of the milling part of the end mill away from one end of the shank part as an ellipsoidal spherical structure, and the ellipsoidal spherical structure includes an elliptical arc surface. Compared with the existing spherical end tooth profile end mill, the present invention can process complex curved surfaces, spherical surfaces, irregular arc surfaces, etc., and the processing efficiency is faster than that of the existing spherical end tooth profile end mill. The residual height is only lower than that of the spherical surface, that is, a smaller surface residual height can be obtained under the same processing spacing, and the processing efficiency is significantly improved, which effectively solves the problem that the surface residual height of the existing end mill is high, resulting in low processing efficiency of the end mill; and compared with the existing spherical end tooth profile end mill, the elliptical end tooth profile end mill of the present invention has the effect of reducing the thickness of the cutting layer, so that the impact load on the cutting edge during the cutting process is smaller, which is beneficial to improving the tool life; under the condition that the milling cutter structural parameters are the same, the helix angle of the cutting part of the elliptical end tooth profile end mill is much larger than that of the ball head mill, so its blade inclination angle and main deflection angle are larger, so that the main cutting force is reduced and the cutting process will be relatively smooth. A larger helix angle will also make it easier for chips to be discharged, which will help dissipate heat and reduce cutting resistance. It can also increase the working length of the cutting edge, reducing the unit edge load, which is beneficial to improving tool life and machining accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a front structural diagram (horizontally) of the end mill of the present invention;

[0030] Figure 2 It is a front structural comparison diagram (vertical) of the elliptical end tooth end mill of the present invention and the existing spherical end tooth end mill;

[0031] Figure 3 This is a right view structural comparison of the end tooth helix of the elliptical end tooth end mill of the present invention and the existing spherical end tooth end mill ( Figure 1 Right view of the );

[0032] Figure 4 The elliptical end tooth end milling cutter of the present invention is superior to the existing spherical end tooth end milling cutter. Figure 2 A comparative enlarged view of the end portion (processing residue);

[0033] Figure 5 It is a front structural comparison diagram (horizontally) of the elliptical end tooth end mill of the present invention and the existing spherical end tooth end mill;

[0034] Figure 6 yes Figure 5 Comparison of cross sections in AA and BB directions.

[0035] The reference numerals are:

[0036] 1. Tool handle; 2. Avoidance part; 3. Milling part; 4. Cutting side edge; 5. Chip groove; 51. Curved section; 52. Straight section; 53. Outer circle; 54. Connecting end; 6. End edge. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0040] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0041] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0042] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0043] like Figure 1-6 As shown, the present invention provides an end mill, which includes:

[0044] A tool handle portion 1 and a milling portion 3, wherein the tool handle portion 1 and the milling portion 3 are connected as a whole, and an axial end of the milling portion 3 away from one end of the tool handle portion 1 is an ellipsoidal structure, and the ellipsoidal structure includes an elliptical arc surface.

[0045] In the prior art, general-purpose ball-end milling cutters are still the most common choice for curved surface machining, but there are problems in the application of ball-end milling cutters. The cutting conditions at the bottom of the end teeth are poor, the residual height is high, which affects the machining efficiency, the cutting speed and chip space are small, and the forming of the helix angle and rake angle of the end teeth are limited by the tool manufacturing method, and the same design parameters as the peripheral teeth cannot be achieved, so the cutting performance is affected.

[0046] The present invention sets the axial end of the milling part of the end mill away from one end of the shank part as an ellipsoidal spherical structure, and the ellipsoidal spherical structure includes an elliptical arc surface. Compared with the existing spherical end tooth profile end mill, the present invention can process complex curved surfaces, spherical surfaces, irregular arc surfaces, etc., and the processing efficiency is faster than that of the existing spherical end tooth profile end mill. The residual height is only lower than that of the spherical surface, that is, a smaller surface residual height can be obtained under the same processing spacing, and the processing efficiency is significantly improved, which effectively solves the problem that the surface residual height of the existing end mill is high, resulting in low processing efficiency of the end mill; and compared with the existing spherical end tooth profile end mill, the elliptical end tooth profile end mill of the present invention has the effect of reducing the thickness of the cutting layer, so that the impact load on the cutting edge during the cutting process is smaller, which is beneficial to improving the tool life; under the condition that the milling cutter structural parameters are the same, the helix angle of the cutting part of the elliptical end tooth profile end mill is much larger than that of the ball head mill, so its blade inclination angle and main deflection angle are larger, so that the main cutting force is reduced and the cutting process will be relatively smooth. A larger helix angle will also make it easier for chips to be discharged, which will help dissipate heat and reduce cutting resistance. It can also increase the working length of the cutting edge, reducing the unit edge load, which is beneficial to improving tool life and machining accuracy.

[0047] In some embodiments,

[0048] The milling part 3 includes a cutting side edge 4, a chip groove 5 and an end edge 6. The chip groove 5 is between two adjacent cutting side edges 4. The end edge 6 is also arranged on the ellipsoidal structure of the milling part 3 away from the end of the shank part 1. The chip groove 5 extends between two adjacent end edges 6. The end edge 6 is formed by an orthogonal spiral edge line.

[0049] This is a further preferred structural form of the end mill of the present invention, in which the end edge can be used to perform primary or priority processing on the workpiece, and the cutting side edge can be used to grind the workpiece or effectively process the inner wall of the hole structure, and the chip groove extends from the cutting side edge to the end edge, so that the chips processed from the end edge and the cutting side edge can be discharged through the chip groove. The present invention further adopts an orthogonal spiral edge line to form the end edge, which can make the edge line involved in cutting longer and the cutting edge sharper, further reduce the residual height, reduce the residual processing area, and further improve the processing efficiency; and the cutting in and out process will be smoother, further reduce the cutting heat and force load, and improve the service life of the tool.

[0050] Due to the innovative design of the milling edge structure, the present invention can effectively improve the machining accuracy and machining efficiency, reduce the cutting heat and force load, and increase the tool life when cutting a flat surface with a small curvature. The milling portion 3 includes two cutting side edges 4 spirally distributed in the circumferential direction, a chip groove 5 is formed between adjacent cutting side edges 4, and an end edge 6 with an elliptical profile, such as Figure 1shown.

[0051] like Figure 3 , in some embodiments,

[0052] The end blade 6 has an end blade helix angle β2, and the end blade helix angle refers to the angle formed by the tangent line along the spiral line at any point of the orthogonal spiral blade line and the center axis of the end mill in the axial projection plane of the end mill. At the same tangent contact point, the end blade helix angle β2 of the elliptical end blade profile end mill is larger than the end blade helix angle β1 of the spherical end blade profile end mill.

[0053] The present invention further sets the end edge helix angle β2 of the end edge to be larger than the end edge helix angle β1 of the spherical end edge profile end mill, so that the edge line involved in cutting of the present invention is further longer, the cutting edge is sharper, the cutting in and out process will be smoother, the cutting heat and force loads will be further reduced, and the service life of the tool will be increased.

[0054] like Figure 2 , in some embodiments,

[0055] The reference plane is perpendicular to the center axis of the end mill at the axial frontmost section of the elliptical arc surface of the milling portion 3, and the angle between the tangent plane at the axial frontmost section of the elliptical arc surface and the reference plane is the actual machining inclination angle θ2. At the same cutting contact point, the actual machining inclination angle θ2 of the end mill with an elliptical end blade profile is smaller than the actual machining inclination angle θ1 of the end mill with a spherical end blade profile.

[0056] The present invention further makes the actual machining inclination angle θ2 of the elliptical end blade profile end mill smaller than the actual machining inclination angle θ1 of the spherical end blade profile end mill at the same cutting contact point, which can further make the edge line involved in cutting longer, the cutting in and out process will be smoother, further reduce the cutting heat and force loads, and increase the service life of the tool.

[0057] like Figure 4 , in some embodiments,

[0058] The machining residual height of the elliptical end mill is h2, and: The residual height of the spherical end milling cutter is h1, and there are: And h2

[0059] ​Through the above-mentioned setting of the machining residual height, the present invention can make the workpiece surface residual height value of the elliptical end tooth profile end mill of the present invention relatively small under the same machining spacing conditions. A smaller surface residual height can be obtained by using the same machining spacing, and the machining surface quality of the workpiece is improved by 30%-50%. Therefore, under the premise of ensuring the same machining surface quality, the machining efficiency of the elliptical end tooth profile end mill can be significantly improved compared with the spherical end tooth profile end mill. Through experimental comparison, the machining efficiency can be improved by about 50%.

[0060] In some embodiments,

[0061] The axial end of the milling portion 3 is within the axial projection plane of the end mill, and the chip groove 5 includes a connected curved segment 51 and a straight segment 52, one end of the curved segment 51 is connected to an end edge 6 located on the periphery, one end of the straight segment 52 is connected to the other end of the curved segment 51, and the other end of the straight segment 52 is connected to an end edge 6 located on the periphery.

[0062] The present invention further increases the chip removal space at the straight segment by making the chip groove of the elliptical end tooth profile end mill consist of a curved segment and a straight segment, relative to the existing chip groove of the spherical end tooth profile end mill, and forms a transition zone in the space. The transition zone is more conducive to chip breaking, and the groove shape is larger and shallower, which is more conducive to improving chip removal efficiency. At the same time, the core thickness of the elliptical end tooth profile end mill is increased by about 10%, so that it has higher strength, which can improve the overall rigidity of the tool and reduce processing vibration.

[0063] In some embodiments,

[0064] In the axial projection plane of the end mill, the outer circumference of the end cutting edge 6 is an arc segment, and the arc segments of the outer circumference of at least two end cutting edges 6 are located on the same outer circumferential circle, and the straight line segment 52 and the curved segment 51 are both located radially inside the outer circumferential circle 53.

[0065] This is a further preferred structural form of the end edge and chip groove of the end mill of the present invention, that is, the straight section and the curved section of the chip groove are both located radially inward of the outer circle of the end edge, thereby forming a chip removal space in a transition zone between the outer circle and the straight section, and a chip groove is jointly formed between the outer circle and the curved section + straight section, thereby increasing the chip removal space at the straight section, and the groove shape is larger and shallower, which is more conducive to improving the chip removal efficiency.

[0066] In some embodiments,

[0067] The connecting end 54 of the straight line segment 52 and the curved line segment 51 is also located radially inward of the outer circle and is spaced from the outer circle 53 by a distance greater than 0;

[0068] The connecting end 54 (transition point) of the curved segment 51 and the straight segment 52 forms a sharp angle, that is, an angle greater than 0 is formed between the tangent of the curved segment 51 at the connecting end 54 and the straight segment 52 .

[0069] The present invention further arranges the connecting end between the straight line segment and the curved line segment at the radial inner circumference of the outer circle, and the connecting end forms a sharp angle, that is, the tangent of the curved line segment at the connecting end forms an angle greater than 0 with the straight line segment. The sharp angle structure of the connecting end can effectively cut off debris, further facilitate chip removal, and improve the processing efficiency and reliability of the milling cutter processing process.

[0070] In some embodiments,

[0071] In the circumferential direction of the milling portion 3, the chip removal grooves 5 are at least two arranged at intervals.

[0072] In the circumferential direction of the milling portion 3 , there are at least two cutting side edges 4 arranged at intervals.

[0073] The present invention preferably has at least two chip removal grooves on the milling part, which can increase the chip removal effect and chip removal amount. At least two spaced-apart cutting side edges can increase the side cutting performance and improve the machining efficiency.

[0074] In some embodiments,

[0075] A clearance portion 2 is also connected between the shank portion 1 and the milling portion 3 . The shank portion 1 is a cylindrical structure, and the milling portion 3 is also a cylindrical structure. No cutting side edges are arranged on the shank portion 1 and the clearance portion 2 .

[0076] The structure of the present invention is as follows Figure 1 As shown, the elliptical end tooth profile end mill includes a shank portion 1 and a milling portion 3 connected to the shank portion 1. A clearance portion 2 can be set between the shank portion 1 and the milling portion 3. Under the condition of ensuring the strength of the tool, the clearance portion 2 can effectively avoid interference or collision when processing complex structural parts (the clearance portion is a cylindrical entity with a diameter slightly smaller than the diameter of the milling cutter added between the shank and the milling edge; in the milling process, when encountering some materials with large height differences, the milling cutter and the material will collide, resulting in processing failure, and the clearance technology is required to ensure the accuracy and efficiency of the milling process).

[0077] Replacing the spherical end edge with an elliptical or other arc-shaped end edge can reduce cutting heat and force loads, improve tool life, processing accuracy and processing efficiency, etc.; a larger and shallower groove composed of curved segments and straight segments is conducive to chip removal and can have higher strength. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. An end mill, characterized in that: include: A tool handle portion (1) and a milling portion (3), wherein the tool handle portion (1) and the milling portion (3) are connected as a whole, and an axial end portion of the milling portion (3) away from one end of the tool handle portion (1) is an ellipsoidal structure, and the ellipsoidal structure includes an elliptical arc surface.

2. The end mill according to claim 1, characterized in that: The milling portion (3) comprises a cutting side edge (4), a chip removal groove (5) and an end edge (6); the chip removal groove (5) is located between two adjacent cutting side edges (4); the end edge (6) is also arranged on an ellipsoidal structure of the milling portion (3) at one end away from the shank portion (1); the chip removal groove (5) extends between two adjacent end edges (6); and the end edge (6) is formed by an orthogonal spiral edge line.

3. The end mill according to claim 2, characterized in that: The end blade (6) has an end blade helix angle β2, and the end blade helix angle refers to the angle formed by the tangent line along the spiral line at any point of the orthogonal spiral blade line and the central axis of the end mill in the axial projection plane of the end mill. At the same tangent contact point, the end blade helix angle β2 of the elliptical end blade profile end mill is larger than the end blade helix angle β1 of the spherical end blade profile end mill.

4. The end mill according to claim 2, characterized in that: The axial frontmost section of the elliptical arc surface of the milling portion (3) is perpendicular to the center axis of the end mill as a reference plane, and the angle between the tangent plane at the axial frontmost section of the elliptical arc surface and the reference plane is the actual machining inclination angle θ2, and at the same tangent contact point, the actual machining inclination angle θ2 of the end mill with an elliptical end blade profile is smaller than the actual machining inclination angle θ1 of the end mill with a spherical end blade profile.

5. The end mill according to claim 2, characterized in that: The machining residual height of the elliptical end mill is h2, and: The residual height of the spherical end milling cutter is h1, and there are: And h2<h1; where: A is the axial height of the end blade of the elliptical end blade profile end mill; r is the distance between the tool center point O2 of the elliptical end blade profile end mill and the axial end of the residual position; R is the tool radius of the spherical end blade profile end mill, and it is also the shank radius of the elliptical end blade profile end mill; the processing spacing of the two tools is equal, both are L.

6. The end mill according to claim 2, characterized in that: The axial end of the milling portion (3) is within the axial projection plane of the end mill, and the chip groove (5) portion includes a connected curved segment (51) and a straight segment (52), one end of the curved segment (51) is connected to an end edge (6) located on the periphery, one end of the straight segment (52) is connected to the other end of the curved segment (51), and the other end of the straight segment (52) is connected to an end edge (6) located on the periphery.

7. The end mill according to claim 6, characterized in that: In the axial projection plane of the end mill, the outer circumference of the end cutting edge (6) is an arc segment, and the arc segments of the outer circumference of at least two end cutting edges (6) are located on the same outer circumference circle (53), and the straight line segment (52) and the curved line segment (51) are located radially inward of the outer circumference circle (53).

8. The end mill according to claim 7, characterized in that: The connecting end (54) of the straight line segment (52) and the curved line segment (51) is also located radially inward of the outer circle (53) and is spaced from the outer circle (53) by a distance greater than 0; The connecting end (54) of the curved segment (51) and the straight segment (52) forms a sharp angle, that is, an angle greater than 0 is formed between the tangent of the curved segment (51) at the connecting end (54) and the straight segment (52).

9. The end mill according to any one of claims 2 to 8, characterized in that: In the circumferential direction of the milling portion (3), the chip removal grooves (5) are at least two arranged at intervals. In the circumferential direction of the milling portion (3), there are at least two cutting side edges (4) arranged at intervals.

10. The end mill according to any one of claims 2 to 9, characterized in that: A clearance portion (2) is also connected between the shank portion (1) and the milling portion (3); the shank portion (1) is a cylindrical structure, the milling portion (3) is also a cylindrical structure, and no cutting side edges are provided on the shank portion (1) or the clearance portion (2).

Images