Cutting insert and tool

Abstract

The invention belongs to the technical field of cutters, and discloses a cutting blade and a cutter, a side scrap guide surface forms wavy curved surfaces with different heights, and the wavy curved surface on one side far away from a side front cutter surface is closer to the bottom surface than the wavy curved surface on one side close to the side front cutter surface along the Z direction, so that scrap iron generated by cutting can flow to the side scrap guide surface along the side front cutter surface, and the cutting efficiency is improved. The side scrap guide face is arranged to be the wavy curved face so that scrap iron can make point contact with the side scrap guide face, the contact area between the scrap iron and the side scrap guide face is reduced, friction between the scrap iron and the side scrap guide face is reduced, the cutting temperature is reduced, the abrasion resistance of the cutting blade is improved, and therefore the service life of the cutting blade is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of cutting tools, and in particular to a cutting blade and a cutting tool. Background Art

[0002] Heavy-duty turning is also called heavy-duty turning. It is mainly used to process large shaft parts or ring parts. The parts to be processed have large allowances. In the process of processing, in order to improve processing efficiency and reduce the number of tool passes, the processing depth of cut will be increased and the feed speed will be increased. However, this will lead to uneven processing allowances, large cutting forces, high cutting temperatures, and very harsh processing conditions. Therefore, high requirements are placed on the wear resistance of the tool. Summary of the invention

[0003] The object of the present invention is to provide a cutting blade and a tool, which can improve the wear resistance of the cutting blade and extend the service life of the cutting blade.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A cutting blade, comprising a top surface and a bottom surface arranged opposite to each other, and a side surface connecting the top surface and the bottom surface, wherein the side surface and the top surface are connected to form a side cutting edge; the top surface comprises a side rake surface and a side chip guide surface, wherein the side chip guide surface is closer to the central axis than the side rake surface; one side of the side rake surface is connected to a side of the side chip guide surface close to the central axis, and the other side is connected to the side cutting edge;

[0006] Along the direction from the side cutting edge to the side rake face connected thereto, the side rake face and the side chip guide face are both inclined toward the side where the bottom face is located, and the side chip guide face is arranged in a wave shape along the extension direction of the side cutting edge.

[0007] As an implementation scheme of the above-mentioned cutting blade, the side cutting edge is a plane perpendicular to the Z direction, the edge width of the side cutting edge is D, 0.2mm≤D≤1mm, and the angle between the side rake surface and the preset plane perpendicular to the Z direction is α, 10°≤α≤30°.

[0008] As an implementation scheme of the above-mentioned cutting insert, a side negative chamfer is provided between the side cutting edge and the side surface, one side of the side negative chamfer is connected to the side cutting edge, and the other side is inclined toward the side where the bottom surface is located and connected to the side surface;

[0009] The angle between the side negative chamfer and a preset plane perpendicular to the Z direction is β, 5°≤β≤20°, and the width of the side negative chamfer is W, 0.1mm≤W≤0.5mm.

[0010] As an implementation scheme for the above-mentioned cutting blade, there are multiple side surfaces, and the multiple side surfaces are connected end to end, and the side surfaces correspond to the side cutting edges one by one. Two adjacent side cutting edges are connected by a rounded cutting edge, two adjacent side rake faces are connected by a rounded rake face, and two adjacent side chip guide faces are connected by an oblique chip guide face. Along the direction from the rounded cutting edge to the central axis, the rounded rake face and the oblique chip guide face gradually approach the bottom surface.

[0011] As an implementation scheme of the above-mentioned cutting blade, the rounded cutting edge and the side cutting edge are coplanar, the side of the side chip guide surface away from the side rake surface is connected to a side anti-chip surface, and two adjacent side anti-chip surfaces are connected through the rounded anti-chip surface;

[0012] Along the direction from the side cutting edge to the side rake face connected thereto, the side anti-chip surface gradually moves away from the bottom surface;

[0013] Along the direction from the rounded cutting edge to the central axis, the rounded anti-chip surface gradually moves away from the bottom surface.

[0014] As an implementation scheme of the above-mentioned cutting blade, the top surface in the area enclosed by the edges of the multiple side anti-chip surfaces away from the side rake surface and the edges of the multiple rounded anti-chip surfaces away from the side of the oblique chip guide surface forms a blade support surface, and the blade support surface is closer to the bottom surface along the Z direction than the side cutting edge, and the side chip guide surface is closer to the bottom surface along the Z direction than the blade support surface.

[0015] As an implementation scheme of the above-mentioned cutting blade, the distance between the blade support surface and the side cutting edge along the Z direction is H, 0mm<H≤0.5mm.

[0016] As a possible implementation scheme of the above-mentioned cutting blade, the cross section of the cutting blade perpendicular to the Z direction is a quadrilateral, and the cutting blade is symmetrically arranged about any diagonal line of the quadrilateral.

[0017] As a possible implementation scheme of the above-mentioned cutting insert, the bottom surface is a plane perpendicular to the Z direction.

[0018] In order to achieve the above-mentioned purpose, the present invention also provides a tool, including a blade mounting portion and a cutting blade provided by any of the above schemes, wherein the cutting blade is provided with a center hole passing through the top surface and the bottom surface, and the cutting blade is threadedly connected to the blade mounting portion after passing through the center hole by a locking screw.

[0019] Beneficial effects of the present invention: The cutting blade and tool provided by the present invention have a side chip guide surface that forms a wavy curved surface of varying heights, and the wavy curved surface on the side away from the side front cutting edge is closer to the bottom surface along the Z direction than the wavy curved surface on the side close to the side front cutting edge, which is beneficial for iron chips generated by cutting to flow along the side front cutting edge to the side chip guide surface. The side chip guide surface is set as a wavy curved surface so that the iron chips are in point contact with the side chip guide surface. By reducing the contact area between the iron chips and the side chip guide surface, the friction between the iron chips and the side chip guide surface is reduced, the cutting temperature is reduced, the wear resistance of the cutting blade is improved, and the service life of the cutting blade is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a cutting blade provided by an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A partial enlarged schematic diagram of the M in the middle;

[0022] Figure 3 is a schematic diagram of a cutting blade provided by an embodiment of the present invention when viewed from the top surface to the side where the bottom surface is located;

[0023] Figure 4 yes Figure 3 A local enlarged schematic diagram of the N position in the middle;

[0024] Figure 5 yes Figure 4 Middle AA section view;

[0025] Figure 6 yes Figure 4 Middle BB section view;

[0026] Figure 7 yes Figure 6 A partial enlarged schematic diagram of point E in the middle;

[0027] Figure 8 yes Figure 4 Middle CC section view.

[0028] In the figure:

[0029] 1. Top surface; 111. Side rake face; 112. Side chip guide face; 113. Side anti-chip face; 121. Rounded rake face; 122. Oblique chip guide face; 123. Rounded anti-chip face; 13. Insert support surface;

[0030] 2. Bottom;

[0031] 31. Side cutting edge; 32. Radius cutting edge;

[0032] 41. Side negative chamfer; 42. Rounded negative chamfer;

[0033] 5. Side surface; 6. Arc chamfered surface;

[0034] 10. Center hole;

[0035] 20. Preset cross section. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0037] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0040] like Figures 1 to 4 As shown, an embodiment of the present invention provides a cutting insert and a tool. The tool includes a insert mounting portion and a cutting insert. The cutting insert includes a top surface 1 and a bottom surface 2 that are arranged opposite to each other along the Z direction, and a side surface 5 connecting the top surface 1 and the bottom surface 2.

[0041] The cutting blade is provided with a center hole 10 which is set through along the Z direction, that is, the center hole 10 passes through the top surface 1 and the bottom surface 2. The cutting blade is detachably mounted on the blade mounting part by a locking screw passing through the center hole 10 and then being threadedly connected to the blade mounting part.

[0042] It should be noted that the blade mounting portion can be a blade rod or a blade disc, which is determined according to actual needs and is not specifically limited here. The central axis of the central hole 10 is the central axis of the cutting blade.

[0043] The top surface 1 and the side surface 5 are connected to form a side cutting edge 31. The top surface 1 includes a side rake surface 111 and a side chip guide surface 112. The side chip guide surface 112 is closer to the center axis of the cutting blade than the side rake surface 111. One side of the side rake surface 111 is connected to the side of the side chip guide surface 112 away from the center axis, and the other side is connected to the side cutting edge 31.

[0044] There are multiple side surfaces 5, which are connected end to end in a circumferential direction around the central axis of the cutting blade, so that the cross section of the cutting blade perpendicular to the Z direction is a polygon. Correspondingly, there are multiple side cutting edges 31, which can be used in a rotating manner to extend the service life of the cutting blade and improve economic efficiency.

[0045] Exemplarily, four side cutting edges 31 are provided, and accordingly, the cross section of the cutting insert perpendicular to the Z direction is a quadrilateral.

[0046] Along the direction from the side cutting edge 31 to the side rake face 111 connected thereto, the side rake face 111 and the side chip guide face 112 are both inclined toward the side where the bottom surface 2 is located, and the side chip guide face 112 is arranged in a wave shape along the extension direction of the side cutting edge 31 .

[0047] For ease of understanding, Figure 1 In the figure, taking a side cutting edge 31 as an example, the extending direction of the side cutting edge 31 is marked as the X direction, and the direction from the side cutting edge 31 to the side rake face 111 connected to the side cutting edge 31 is marked as the Y direction. For any side cutting edge 31, the X direction, the Y direction and the Z direction are perpendicular to each other. It should be noted that the extending directions of the two side cutting edges 31 are not necessarily perpendicular.

[0048] like Figure 5 As shown, taking a side cutting edge 31 as an example, the intersection line between the side chip guide surface 112 and the preset cross section 20 is wavy, wherein the preset cross section 20 is parallel to the extension direction of the side cutting edge 31 and parallel to the central axis.

[0049] Such an arrangement can make the side chip guide surface 112 form a wavy surface of varying heights, and the wavy surface on the side away from the side rake surface 111 is closer to the bottom surface 2 along the Z direction than the wavy surface on the side closer to the side rake surface 111, which is beneficial for the iron chips generated by cutting to flow along the side rake surface 111 to the side chip guide surface 112. The side chip guide surface 112 is set as a wavy surface so that the iron chips are in point contact with the side chip guide surface 112. By reducing the contact area between the iron chips and the side chip guide surface 112, the friction between the iron chips and the side chip guide surface 112 is reduced, the cutting temperature is reduced, and the wear resistance of the cutting blade is improved, thereby increasing the service life of the cutting blade.

[0050] In some embodiments, Figures 4 to 7 As shown, the side cutting edge 31 is a plane perpendicular to the Z direction, the width of the side cutting edge 31 is D, 0.2mm≤D≤1mm, and the angle between the side rake surface 111 and the preset plane perpendicular to the Z direction is α, 10°≤α≤30°.

[0051] By optimizing the reasonable width of the side cutting edge 31 and matching it with a suitable angle α, it is beneficial to improve the sharpness of the side cutting edge 31, reduce cutting resistance, reduce cutting temperature, and improve the wear resistance of the tool when performing heavy-load cutting. It is beneficial to avoid chipping of the cutting blade when used in conditions with a large cutting depth and a fast feed speed, thereby extending the service life of the cutting blade.

[0052] It should be noted that the width D can be any value between 0.2 mm and 1 mm, such as the width D can be any one of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1 mm. The angle α can be any angle between 10° and 30°, such as the angle α can be any angle between 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°, 29°, and 30°.

[0053] Exemplarily, the side rake surface 111 is an inclined plane. In other embodiments, the side rake surface 111 can also be a circular arc convex surface.

[0054] In some embodiments, Figures 2 to 7 As shown, a side negative chamfer 41 is arranged between the side cutting edge 31 and the side surface 5, one side of the side negative chamfer 41 is connected to the side cutting edge 31, and the other side of the side negative chamfer 41 is inclined to the side where the bottom surface 2 is located and connected to the side surface 5; the angle between the side negative chamfer 41 and the preset plane perpendicular to the Z direction is β, 5°≤β≤20°, and the width of the side negative chamfer 41 is W, 0.1mm≤W≤0.5mm.

[0055] The negative chamfer 41 is the above-mentioned back cutting edge, and the angle β is the back angle of the cutting blade. The smaller the angle β is, the sharper the cutting blade is. Combined with the above-mentioned width W, it can reduce cutting resistance, lower cutting temperature, and improve the wear resistance of the tool when used for heavy-duty black turning, large cutting depth and large feed rate processing, and intermittent turning. It is beneficial to improve the anti-breakage performance of the cutting blade and reduce the risk of tool breakage.

[0056] It should be noted that the side negative chamfer 41 has a first edge and a second edge that are arranged opposite to each other, the first edge is the intersection line of the side negative chamfer 41 and the side rake face 111, the second edge is the intersection line of the side negative chamfer 41 and the side surface 5, and the width W of the side negative chamfer 41 refers to the distance between the first edge and the second edge. The width W can be selected from any value between 0.1 mm and 0.5 mm, such as the width D can be selected from any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. The angle β can be selected from any angle between 5° and 20°, such as the angle β can be selected from any angle of 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, and 20°.

[0057] Exemplarily, the side negative chamfer 41 is an inclined plane.

[0058] In some embodiments, Figures 2 to 8 As shown, two adjacent side cutting edges 31 are connected by a rounded cutting edge 32, and the side cutting edge 31 and the rounded cutting edge 32 are located in the same plane perpendicular to the Z direction. In other words, the arc cutting edge is a plane. Two adjacent side rake faces 111 are connected by a rounded rake face 121, and two adjacent side negative chamfers 41 are connected by a rounded negative chamfer 42.

[0059] One side of the rounded cutting edge 32 is connected to the rounded rake face 121, and the other side is connected to the rounded negative chamfer 42. Exemplarily, the edge of the rounded cutting edge 32 connected to the rounded rake face 121 and the edge connected to the rounded negative chamfer 42 are both arcs, two adjacent side surfaces 5 are connected by an arc chamfer surface 6, the rounded negative chamfer 42 is a conical surface, the large diameter end of the conical surface is connected to the arc chamfer surface 6, and the rounded rake face 121 is a conical surface.

[0060] In some embodiments, Figure 4 and Figure 8 As shown, two adjacent side chip guide surfaces 112 are connected by an oblique chip guide surface 122 , and along the direction from the rounded cutting edge 32 to the center axis, the rounded rake surface 121 and the oblique chip guide surface 122 gradually approach the bottom surface 2 .

[0061] When turning a workpiece using the above-mentioned cutting blade, the iron chips generated by turning flow smoothly along the side rake face 111 to the inclined chip guide surface 122 with less resistance. At the same time, by increasing the thickness of the polygonal corner area, it is beneficial to improve the structural strength of the rounded cutting edge 32 and improve the anti-breakage performance of the cutting blade.

[0062] Taking the cross section of the cutting blade perpendicular to the X direction as a quadrilateral as an example, along the direction of the diagonal of the quadrilateral close to the central axis, the inclined chip guide surface 122 passed by the diagonal of the quadrilateral gradually approaches the bottom surface 2.

[0063] Exemplarily, the inclined chip guiding surface 122 is an inclined plane.

[0064] In some embodiments, Figure 3 As shown, the cutting blades are symmetrically arranged about any diagonal line of the quadrilateral. Such an arrangement is conducive to improving the consistency between different cutting edges.

[0065] In some embodiments, Figure 2 and Figure 5 As shown, the side of the side chip guide surface 112 away from the side rake surface 111 is connected to the side anti-chip surface 113, and the two adjacent side anti-chip surfaces 113 are connected by a rounded anti-chip surface 123; along the direction from the side cutting edge 31 to the side rake surface 111 connected thereto, the side anti-chip surface 113 gradually moves away from the bottom surface 2; along the direction from the rounded cutting edge 32 to the central axis, the rounded anti-chip surface 123 gradually moves away from the bottom surface 2.

[0066] Such arrangement is conducive to the iron chips being gradually curled and discharged under the guidance of the rounded anti-chip surface 123 and the side anti-chip surface 113, thereby improving the smoothness of chip discharge and timely discharging the iron chips and heat generated by cutting.

[0067] In some embodiments, Figure 3 and Figure 6 As shown, the top surface 1 in the area surrounded by the edge of the side anti-chip surfaces 113 away from the side rake face 111 and the edge of the side anti-chip surfaces 123 away from the oblique chip guide surface 122 forms a blade support surface 13, the blade support surface 13 is closer to the bottom surface 2 along the Z direction than the side cutting edge 31, and the side chip guide surface 112 is closer to the bottom surface 2 along the Z direction than the blade support surface 13. Such a configuration is conducive to breaking the iron chips at the junction of the blade support surface 13 and the side anti-chip surface 113 and the rounded anti-chip surface 123, forming iron chips of appropriate length, improving the chip breaking performance of the cutting blade, achieving good chip breaking performance, and reducing cutting resistance.

[0068] In some embodiments, Figure 6 As shown, the distance between the blade support surface 13 and the side cutting edge 31 along the Z direction is H, 0mm<H≤0.5mm. By selecting a reasonable H, it is beneficial to further improve the chip breaking performance of the cutting blade.

[0069] It should be noted that the spacing H can be any value less than 0.5 mm, such as the spacing H can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.

[0070] In some embodiments, Figure 6 As shown, the bottom surface 2 is a plane perpendicular to the Z direction. Such an arrangement is conducive to increasing the contact area between the bottom surface 2 and the blade mounting portion, improving the clamping stability and reliability of the cutting blade, thereby ensuring the safety performance of heavy-load turning processing.

[0071] The cutting blade provided by the present invention comprehensively improves the chip breaking performance, wear resistance and collapse resistance of the cutting blade by reasonably designing various parameters such as D, H, W, α and β. It can be suitable for working conditions of large cutting depth and large feed rate when processing large parts. It is not only suitable for conventional parts processing, but also particularly suitable for processing large parts such as wind turbine flanges, wind turbine bearings and wind turbine main shafts. The cutting blade has relatively excellent versatility.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A cutting blade, comprising a top surface (1) and a bottom surface (2) arranged opposite to each other in the Z direction, and a side surface (5) connecting the top surface (1) and the bottom surface (2), wherein the side surface (5) and the top surface (1) are connected to form a side cutting edge (31); characterized in that: The top surface (1) comprises a side rake surface (111) and a side chip guide surface (112), wherein the side chip guide surface (112) is closer to the central axis of the cutting blade than the side rake surface (111), one side of the side rake surface (111) is connected to a side of the side chip guide surface (112) away from the central axis, and the other side is connected to the side cutting edge (31); Along the direction from the side cutting edge (31) to the side rake face (111) connected thereto, the side rake face (111) and the side chip guide face (112) are both arranged to be inclined toward the side where the bottom face (2) is located, and the side chip guide face (112) is arranged in a wave shape along the extension direction of the side cutting edge (31).

2. The cutting insert according to claim 1, characterized in that The side cutting edge (31) is a plane perpendicular to the Z direction, the blade width of the side cutting edge (31) is D, 0.2mm≤D≤1mm, and the angle between the side rake surface (111) and a preset plane perpendicular to the Z direction is α, 10°≤α≤30°.

3. The cutting insert according to claim 1, characterized in that A side negative chamfer (41) is provided between the side cutting edge (31) and the side surface (5), one side of the side negative chamfer (41) is connected to the side cutting edge (31), and the other side is inclined toward the side where the bottom surface (2) is located and is connected to the side surface (5); The angle between the side negative chamfer (41) and a preset plane perpendicular to the Z direction is β, 5°≤β≤20°, and the width of the side negative chamfer (41) is W, 0.1mm≤W≤0.5mm.

4. The cutting insert according to claim 3, characterized in that A plurality of the side surfaces (5) are provided, and the plurality of side surfaces (5) are connected end to end. The side surfaces (5) correspond to the side cutting edges (31) one by one. Two adjacent side cutting edges (31) are connected via a rounded cutting edge (32). Two adjacent side rake surfaces (111) are connected via a rounded rake surface (121). Two adjacent side chip guide surfaces (112) are connected via an oblique chip guide surface (122). Along the direction from the rounded cutting edge (32) to the central axis, the rounded rake surface (121) and the oblique chip guide surface (122) gradually approach the bottom surface (2).

5. The cutting insert according to claim 4, characterized in that The rounded cutting edge (32) and the side cutting edge (31) are coplanar, the side of the side chip guide surface (112) away from the side rake surface (111) is connected to a side anti-chip surface (113), and two adjacent side anti-chip surfaces (113) are connected via a rounded anti-chip surface (123); Along the direction from the side cutting edge (31) to the side rake face (111) connected thereto, the side anti-chip surface (113) gradually moves away from the bottom surface (2); Along the direction from the rounded cutting edge (32) to the central axis, the rounded anti-chip surface (123) gradually moves away from the bottom surface (2).

6. The cutting insert according to claim 5, characterized in that The top surface (1) in an area enclosed by the edges of the plurality of side anti-chip surfaces (113) away from the side rake surface (111) and the edges of the plurality of rounded anti-chip surfaces (123) away from the side oblique chip guide surface (122) forms a blade support surface (13); the blade support surface (13) is closer to the bottom surface (2) along the Z direction than the side cutting edge (31); and the side chip guide surface (112) is closer to the bottom surface (2) along the Z direction than the blade support surface (13).

7. The cutting insert according to claim 6, characterized in that The distance between the blade support surface (13) and the side cutting edge (31) along the Z direction is H, 0mm<H≤0.5mm.

8. The cutting insert according to claim 4, characterized in that The cross section of the cutting blade perpendicular to the Z direction is a quadrilateral, and the cutting blade is symmetrically arranged about any diagonal line of the quadrilateral.

9. The cutting insert according to any one of claims 1 to 8, characterized in that The bottom surface (2) is a plane perpendicular to the Z direction.

10. A tool, characterized in that The invention comprises a blade mounting portion and a cutting blade as claimed in any one of claims 1 to 9, wherein the cutting blade is provided with a center hole (10) penetrating the top surface (1) and the bottom surface (2), and the cutting blade is threadedly connected to the blade mounting portion after a locking screw passes through the center hole (10).

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