A milling insert having a double layer dressing structure

Abstract

The application discloses a milling blade with a double-layer dressing structure and belongs to the field of metal cutting processing, and comprises an upper surface, a lower bottom surface and a peripheral surface, the peripheral surface comprises two side surfaces and two end surfaces, the intersection of the upper surface and the side surface forms a main cutting edge, and the intersection of the upper surface and at least one end surface forms, in sequence along the direction away from the main cutting edge, a main dressing edge, a clearance groove, a secondary dressing edge and a secondary cutting edge. In the cutting process, when the main dressing edge is damaged or broken and the surface quality is affected, the secondary dressing edge can be used to implement secondary dressing processing on the machined surface, so that the dressing processing function of the blade body is supplemented, and the machining precision of the surface is continuously maintained. The continuous use of the milling blade prolongs the effective machining time, and the service life of the milling blade is also improved.

Description

Technical Field

[0001] This invention belongs to the field of metal cutting and machining, specifically a milling insert with a double-layer finishing structure. Background Technology

[0002] In the field of CNC metal cutting, planar milling is a common machining method. It involves removing metal material by using a high-speed rotating tool to perform regular reciprocating motions within a plane. In planar milling, surface quality is a crucial factor in determining the quality of the workpiece. Besides being related to machine tool parameters, workpiece material, and tooling precision, it is also related to the wear of the cutting edge of the insert. This means that the cutting edge plays a vital role in the entire metal removal process. A damaged cutting edge means the surface finish cannot be maintained, and the insert will no longer be used. Only when the cutting edge remains intact can the workpiece consistently achieve a relatively ideal surface quality.

[0003] Patent CN113573834A discloses a cutting insert in which the width of the first face increases from the middle position toward the front end, which can ensure the strength of the cutting tip; it decreases from the front end toward the middle position, which can suppress back clearance wear; and it increases in width from the middle position toward the rear end, which can prevent interference with the workpiece; and the two-point contact between the second face and the cutter body can improve the installation accuracy of the cutter body.

[0004] In the above scheme, ensuring the strength of the cutting insert tip and improving installation accuracy can improve the surface finish of the workpiece to a certain extent. However, the finishing edge, which is the third cutting edge of the cutting insert, still adopts a relatively traditional single-edge structure. In planar machining, the finishing edge is always in direct contact with the workpiece and participates in the finishing process, playing a role in improving and repairing surface quality. This traditional structure of the finishing edge is prone to damage due to the combined effects of cutting heat and cutting force during the cutting process. As the cutting process continues, the degree of damage will further intensify, and the effect of the finishing edge will be reduced, which will have a certain impact on the machining accuracy of the workpiece surface. Summary of the Invention

[0005] The purpose of this invention is to provide a milling insert with a double-layer finishing structure to solve the problems mentioned in the prior art.

[0006] A milling insert with a double-layer finishing structure is provided, comprising:

[0007] The blade body has at least one main cutting edge. The blade body is formed in sequence along the direction away from the main cutting edge, including a main finishing edge, a clearance groove, a secondary finishing edge, and a secondary cutting edge. The main finishing edge is connected to the adjacent main cutting edge through a main blade tip, and the secondary finishing edge is connected to the adjacent main cutting edge through a secondary blade tip.

[0008] As a further embodiment of the present invention: the main repair light blade and the secondary repair light blade are parallel to each other, the length of the main repair light blade is L1, the length of the secondary repair light blade is L2, and L1≤L2.

[0009] As a further embodiment of the present invention: the blade body includes an upper surface, a lower bottom surface and four surrounding surfaces. The four surrounding surfaces include two side surfaces and two end surfaces. The part of the end surface that is adjacent to the main polishing blade forms the main polishing back angle surface. The part of the end surface that is adjacent to the secondary polishing blade forms the secondary polishing back angle surface. The clearance groove is formed by the inward recess of the end surface located between the main polishing back angle surface and the secondary polishing back angle surface.

[0010] As a further embodiment of the present invention: the part of the end surface that is adjacent to the main repair back corner surface and the clearance groove is recessed inward relative to the main repair back corner surface to form a main repair gap surface, and the part of the end surface that is adjacent to the secondary repair back corner surface and the clearance groove is recessed inward relative to the secondary repair back corner surface to form a secondary repair gap surface.

[0011] As a further embodiment of the present invention: the plane containing the primary back corner surface and the plane containing the secondary back corner surface are parallel to each other, and there is a distance difference H1 between the primary back corner surface and the secondary back corner surface, and 0.03mm≤H1≤0.1mm.

[0012] As a further embodiment of the present invention: the blade body includes an upper surface, a lower bottom surface and four surrounding surfaces, the four surrounding surfaces include two side surfaces and two end surfaces, a screw through hole is formed inside the blade body between the upper surface and the lower bottom surface, the two side surfaces are arranged in a rotationally symmetrical manner with respect to the central axis of the screw through hole, and the two end surfaces are arranged in a rotationally symmetrical manner with respect to the central axis of the screw through hole.

[0013] As a further embodiment of the present invention: the extension lines of the two main repair blades and the extension lines of the two auxiliary repair blades are all located on the radial plane of the central axis of the same screw through hole.

[0014] As a further embodiment of the present invention: when the main cutting edge extends from the main tool tip to the secondary tool tip, the main cutting edge gradually tilts towards the bottom surface; when the secondary cutting edge extends from the secondary finishing edge to the secondary tool tip, the secondary cutting edge gradually tilts towards the bottom surface.

[0015] As a further embodiment of the present invention, it also includes a tool holder and a locking screw. The blade body includes an upper surface, a lower bottom surface, and four surrounding surfaces. The four surrounding surfaces include two side surfaces and two end surfaces. A screw through hole is formed inside the blade body between the upper surface and the lower bottom surface. A tool groove is provided in the side mounting groove of the tool holder. The tool groove includes an end support surface, a side support surface, a bottom support surface, and a screw countersunk hole. The part of the end surface that contacts the secondary cutting edge forms an end positioning surface. The part of the side surface that contacts the lower bottom surface is recessed inward to form a side positioning surface. After the screw through hole of the blade body and the screw countersunk hole of the tool holder are engaged by the locking screw, the lower bottom surface abuts against the bottom support surface, the side positioning surface abuts against the side support surface, and the end positioning surface abuts against the end support surface.

[0016] As a further embodiment of the present invention: the cutting end face of the tool holder forms an arc-shaped chip removal groove, one end of which is connected to the clearance groove, and the other end is connected to the side mounting groove of the tool holder.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. In machining, the main cutting edge and the primary cutting tip are the main components involved in the cutting process. The primary finishing edge serves to smooth the workpiece surface, improving its quality. Although the primary finishing edge does not directly participate in cutting, it is still affected by cutting resistance and heat due to manufacturing errors, making it prone to breakage. When a chip or breakage in the primary finishing edge affects the surface quality, a secondary finishing edge can perform a second finishing process on the already machined surface, supplementing the finishing function lacking in the insert itself and thus maintaining the surface finish. Continued use of milling inserts extends the effective machining time, meaning the lifespan of the milling inserts is also increased.

[0019] 2. The recessed grooves structurally isolate the primary and secondary finishing edges, preventing the adverse effects of cutting resistance and heat on the primary edge from being transmitted to the secondary edge, thus effectively protecting the structural stability of the secondary edge. During finishing operations on both the primary and secondary edges, debris generated can be discharged through the recessed grooves, preventing continuous accumulation of debris on the surfaces of the primary and secondary cutting edges and thus avoiding wear. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the blade body provided by the present invention;

[0022] Figure 2 This is a front view of the blade body provided by the present invention;

[0023] Figure 3 This is a top view of the blade body provided by the present invention;

[0024] Figure 4 yes Figure 3 Sectional view of DD;

[0025] Figure 5 This is a side view of the blade body provided by the present invention;

[0026] Figure 6 This is a magnified view of a portion of the polishing blade in this invention;

[0027] Figure 7 This is an assembly drawing of the cutting tool provided by the present invention;

[0028] Figure 8 This is a schematic diagram of the tool holder provided by the present invention;

[0029] Figure 9 This is a schematic diagram of the cutting state of the blade body provided by the present invention;

[0030] Figure 10 yes Figure 9 A magnified view of the cutting state of the cutting blade body.

[0031] In the diagram: 1. Blade body; 5. Upper surface; 6. Lower bottom surface; 7. All four sides; 8. Screw through hole; 10. End surface; 11. Side surface; 12. Main cutting edge; 16. Main tool tip; 18. Main finishing edge; 19. Main finishing clearance angle surface; 20. Clearance groove; 22. Main finishing clearance surface; 23. Secondary finishing clearance surface; 25. Secondary cutting edge; 26. Secondary tool tip; 28. Secondary finishing edge; 29. ​​Secondary finishing clearance angle surface; 30. End positioning surface; 40. End support surface; 41. Side support surface; 42. Bottom support surface; 44. Tool groove; 46. Screw countersunk hole; 50. Locking screw; 60. Tool holder; 61. Chip removal groove; 100. Cutting tool; 110. Main cutting clearance angle surface; 112. Side positioning surface; 113. Main cutting clearance surface; 200. Workpiece. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0033] Obviously, the accompanying drawings described below are merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0034] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the invention and are not intended to limit the subject matter of the claims.

[0035] Please see Figure 1 and Figure 3 As shown, the milling insert with a double-layer finishing structure in this embodiment of the invention includes an upper surface 5, a lower bottom surface 6, and four surrounding surfaces 7. The upper surface 5 and the lower bottom surface 6 are connected by the surrounding surfaces 7 to form the insert body 1. The surrounding surfaces 7 include two side surfaces 11 and two end surfaces 10. The intersection of the upper surface 5 and the side surfaces 11 forms the main cutting edge 12. The intersection of the upper surface 5 and at least one end surface 10 forms, in sequence, a main finishing edge 18, a clearance groove 20, a secondary finishing edge 28, and a secondary cutting edge 25 in a direction away from the main cutting edge 12. The main finishing edge 18 is connected to the adjacent main cutting edge 12 by a main tool tip 16, and the secondary finishing edge 28 is connected to the adjacent main cutting edge 12 by a secondary tool tip 26. A screw through hole 8 is passed through the insert body 1 between the upper surface 5 and the lower bottom surface 6.

[0036] In existing technologies, the surface being processed may be deformed by compression, resulting in burrs, scratches, and other defects that affect the surface finish. As the finishing edge of a traditional cutting tool continues to break, the likelihood of surface defects increases. Through the implementation of this invention, the secondary finishing edge 28 is positioned behind the main finishing edge 18, allowing for further finishing of the surface processed by the main finishing edge 18. This maximizes the removal of excess material from the workpiece 200 surface, compensates for surface precision loss, and further improves the quality of the processed surface.

[0037] Please see Figures 1-4 , Figures 7-9 As shown, the milling insert also includes a tool holder 60 and a locking screw 50. In this embodiment, the cutting end of the tool holder 60 has two open side mounting slots arranged symmetrically. A tool groove 44 is provided within the side mounting slots, which is used to mate with the insert body 1 to form a complete cutting tool 100. The tool groove 44 includes an end support surface 40, a side support surface 41, a bottom support surface 42, and a countersunk hole 46. The cutting tool 100 is assembled by placing the locking screw 50 in the screw through hole 8 of the insert body 1, passing it through the countersunk hole 46 to fix the insert body 1 in the tool groove 44. The cutting tool 100 can then rotate at high speed around the tool rotation center C to perform planar cutting machining on the workpiece 200.

[0038] The bottom surface 6 is a positioning base surface, which contacts the bottom support surface 42 after assembly. The bottom support surface 42 provides sufficient bottom support force for the blade body 1.

[0039] The portion of the side surface 11 that meets the lower bottom surface 6 is recessed inward to form a side positioning surface 112. The convex portion of the side surface 11 relative to the side positioning surface 112 is the main cutting clearance angle surface 110. The portion connecting the side positioning surface 112 and the main cutting clearance angle surface 110 is the main cutting clearance surface 113. The main cutting clearance surface 113 creates an oblique transition between the side positioning surface 112 and the main cutting clearance angle surface 110. The side positioning surface 112 can be a blank surface, contacting the side support surface 41 to provide lateral positioning for the insert body 1. The side support surface 41 provides lateral support force to the insert body 1. The extended structure of the main cutting clearance surface 113 protects the side positioning surface 112 from cutting wear, ensuring the positioning accuracy of the insert body 1. The main cutting clearance angle surface 110 has a certain thickness, which improves the structural strength of the main cutting edge 12, prevents wear of the main cutting edge 12, and improves its durability.

[0040] The portion of the end surface 10 that contacts the secondary cutting edge 25 forms an end positioning surface 30. The end positioning surface 30 contacts the end support surface 40 and is used to provide end face positioning for the insert body 1. The end support surface 40 provides end face support force to the insert body 1.

[0041] The portion of the end surface 10 that contacts the main finishing blade 18 forms the main finishing back angle surface 19, and the portion of the end surface 10 that contacts the secondary finishing blade 28 forms the secondary finishing back angle surface 29. The clearance groove 20 is formed by the inward indentation of the portion of the end surface 10 located between the main finishing back angle surface 19 and the secondary finishing back angle surface 29. Both the main finishing back angle surface 19 and the secondary finishing back angle surface 29 require grinding to provide a more precise finishing structure. The main finishing back angle surface 19, through its own thickness, provides structural strength support for the main finishing blade 18, improving its wear resistance. Similarly, the secondary finishing back angle surface 29, through its own thickness, provides structural strength support for the secondary finishing blade 28, improving its wear resistance.

[0042] Furthermore, the portion of the end surface 10 that is adjacent to the main finishing back angle surface 19 and the clearance groove 20 is recessed inward relative to the main finishing back angle surface 19 to form the main finishing gap surface 22. The main finishing gap surface 22 reduces the area occupied by the main finishing back angle surface 19 on the end surface 10, avoiding excessive frictional interference between the main finishing back angle surface 19 and the workpiece 200 due to its large area, thus reducing cutting resistance and cutting heat generation. In fact, the main finishing back angle surface 19 does not need to occupy the entire thickness of the end surface 10; it only needs to provide a certain thickness to support the main finishing cutting edge 18. Secondly, the clearance treatment of the main finishing gap surface 22 facilitates the rearward discharge of chips.

[0043] When the primary finishing edge 18 is damaged, the secondary finishing edge 28 participates in the secondary finishing process. The portion of the end surface 10 that is adjacent to the secondary finishing back angle surface 29 and the clearance groove 20 is recessed inward relative to the secondary finishing back angle surface 29 to form a secondary finishing gap surface 23. The secondary finishing gap surface 23 reduces the area occupied by the secondary finishing back angle surface 29 on the end surface 10, avoiding excessive frictional interference between the secondary finishing back angle surface 29 and the workpiece 200 due to its large area, thus reducing cutting resistance and cutting heat. Similarly, the secondary finishing back angle surface 29 does not need to occupy the entire thickness of the end surface 10; it only needs to provide a certain thickness to support the secondary finishing edge 28. Furthermore, the clearance treatment of the secondary finishing gap surface 23 facilitates the lateral discharge of chips.

[0044] The protruding structures of the primary polishing back angle surface 19 and the secondary polishing back angle surface 29 compared to the primary polishing gap surface 22 and the secondary polishing gap surface 23 provide a basis for secondary grinding of the primary polishing back angle surface 19 and the secondary polishing back angle surface 29, thereby improving the reusability of the blade body 1.

[0045] Please see Figure 3As shown, the primary finishing edge 18 and the secondary finishing edge 28 are parallel to each other to avoid localized stress concentration caused by edge angle deviation in the machining direction, which would exacerbate wear on the finishing edge. To ensure that the secondary finishing range of the secondary finishing edge 28 can cover the finishing range of the primary finishing edge 18, the length L1 of the primary finishing edge 18 is no greater than the length L2 of the secondary finishing edge 28, i.e., L1≤L2. This ensures that under high feed conditions, the secondary finishing edge 28 can completely cover the surface machining range of the primary finishing edge 18.

[0046] Please see Figure 1 , Figure 6 , Figure 10 As shown, the plane containing the primary finishing edge 19 and the plane containing the secondary finishing edge 29 are parallel to each other. This prevents localized stress concentration caused by plane angle offset in the machining direction, which would exacerbate wear on the finished edge. During the cutting of workpiece 200, the primary finishing edge 18 preferentially contacts the surface of workpiece 200. If the primary finishing edge 18 is not completely damaged, the secondary finishing edge 28 remains in a non-machining state, maintaining a certain distance H1 from the surface machined by the primary finishing edge 18, thus protecting itself. When the primary finishing edge 18 is damaged and the machined surface shows burrs, scratches, or other defects, the secondary finishing edge 28 participates in the finishing process to remove machining residues. Therefore, in the top view of the upper surface 5, the primary repair blade 18 and the secondary repair blade 28 are not collinear. The secondary repair blade 28 preferentially approaches the screw through hole 8 relative to the primary repair blade 18. There is a distance difference H1 between the primary repaired back angle surface 19 and the secondary repaired back angle surface 29, and 0.03mm≤H1≤0.1mm. This range ensures that the secondary repair blade 28 does not participate in secondary repair when the primary repair blade 18 is not completely damaged, thus protecting the secondary repair blade 28; while ensuring that the secondary repair blade 28 can quickly respond and participate in secondary repair when the primary repair blade 18 fails. In this embodiment, H1 is preferably 0.05mm.

[0047] In one embodiment, see Figure 1 , Figure 3 and Figure 8 As shown, the insert body 1 can have a main finishing blade 18 and a secondary finishing blade 28 on only a single end surface 10, or it can have a main finishing blade 18 and a secondary finishing blade 28 on both end surfaces 10. The two side surfaces 11 are arranged rotationally symmetrically with respect to the central axis A of the screw through hole 8, and the two end surfaces 10 are also arranged rotationally symmetrically with respect to the central axis A of the screw through hole 8. This allows the insert body 1 to be indexed for machining, replacing the machining surface of the insert body 1 within the tool groove 44, thus improving the reusability of the insert body 1.

[0048] Further, please refer to Figure 1 and Figure 5As shown, the extension lines of the two main polishing blades 18 and the two secondary polishing blades 28 are all located on the radial plane of the central axis A of the same screw through hole 8, i.e., H2 = 0. When grinding the bottom surface 6, the bottom surface 6 needs to face upwards and the main blade tip 16 needs to face downwards. The fact that the two main polishing blades 18 and the two secondary polishing blades 28 are located on the same plane can provide stable support for the blade body 1, improve the grinding accuracy of the bottom surface 6, and ensure the repositioning accuracy of the main blade tip 16 and other structures when the blade body 1 is indexed to replace the machined surface.

[0049] Please see Figure 2 As shown, when the main cutting edge 12 extends from the main cutting tip 16 to the secondary cutting tip 26, the main cutting edge 12 gradually tilts towards the lower bottom surface 6. That is, H3 > H4, so that the main cutting edge 12 tilts to form an angle α, which is used to form a clearance area to guide the chip flow and keep the chips away from the machined surface.

[0050] Please see Figure 5 As shown, when the secondary cutting edge 25 extends from the secondary finishing edge 28 towards the secondary tip 26, the secondary cutting edge 25 gradually slopes downwards towards the bottom surface 6. That is, H3 > H4. Similarly, this is used to create a clearance area to facilitate chip removal.

[0051] Please see Figure 1 , Figure 8 and Figure 9 As shown, the cutting end face of the tool holder 60 forms an arc-shaped chip removal groove 61. One end of the chip removal groove 61 communicates with the clearance groove 20, and the other end communicates with the side mounting groove of the tool holder 60. During the finishing process of the main finishing edge 18 and the secondary finishing edge 28, the chips generated can enter the clearance groove 20, pass through the chip removal groove 61, and be discharged to the side mounting groove, ultimately exiting from the side mounting groove. The arc-shaped structure avoids dead corners in chip removal, preventing chip accumulation.

[0052] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A milling insert with a double-layer finishing structure, characterized in that, include: The blade body (1) has at least one main cutting edge (12). The blade body (1) is formed in sequence along the direction away from the main cutting edge (12) by a main finishing edge (18), a clearance groove (20), a secondary finishing edge (28), and a secondary cutting edge (25). The main finishing edge (18) is connected to the adjacent main cutting edge (12) through a main blade tip (16), and the secondary cutting edge (25) is connected to the adjacent main cutting edge (12) through a secondary blade tip (26). The primary repair light blade (18) and the secondary repair light blade (28) are parallel to each other. The length of the primary repair light blade (18) is L1, and the length of the secondary repair light blade (28) is L2, and L1≤L2; The blade body (1) includes an upper surface (5), a lower bottom surface (6), and four sides (7). The four sides (7) include two side surfaces (11) and two end surfaces (10). The part of the end surface (10) that is adjacent to the main polishing blade (18) forms the main polishing back angle surface (19). The part of the end surface (10) that is adjacent to the secondary polishing blade (28) forms the secondary polishing back angle surface (29). The clearance groove (20) is formed by the inward recess of the part of the end surface (10) located between the main polishing back angle surface (19) and the secondary polishing back angle surface (29). The plane containing the primary back surface (19) and the plane containing the secondary back surface (29) are parallel to each other. There is a distance difference H1 between the primary back surface (19) and the secondary back surface (29), and 0.03mm≤H1≤0.1mm.

2. A milling insert with a double-layer finishing structure according to claim 1, characterized in that, The portion of the end surface (10) that is adjacent to the main repair back corner surface (19) and the clearance groove (20) is recessed inward relative to the main repair back corner surface (19) to form the main repair gap surface (22). The portion of the end surface (10) that is adjacent to the secondary repair back corner surface (29) and the clearance groove (20) is recessed inward relative to the secondary repair back corner surface (29) to form the secondary repair gap surface (23).

3. A milling insert with a double-layer finishing structure according to claim 1, characterized in that, The blade body (1) includes an upper surface (5), a lower bottom surface (6), and four sides (7). The four sides (7) include two side surfaces (11) and two end surfaces (10). A screw through hole (8) is passed through the blade body (1) between the upper surface (5) and the lower bottom surface (6). The two side surfaces (11) are arranged in a rotationally symmetrical manner with respect to the central axis of the screw through hole (8), and the two end surfaces (10) are arranged in a rotationally symmetrical manner with respect to the central axis of the screw through hole (8).

4. A milling insert with a double-layer finishing structure according to claim 3, characterized in that, The extension lines of the two primary polishing blades (18) and the extension lines of the two secondary polishing blades (28) are all located on the radial plane of the central axis of the same screw through hole (8).

5. A milling insert with a double-layer finishing structure according to claim 3, characterized in that, When the main cutting edge (12) extends from the main cutting tip (16) to the secondary cutting tip (26), the main cutting edge (12) gradually tilts towards the lower bottom surface (6); when the secondary cutting edge (25) extends from the secondary finishing edge (28) to the secondary cutting tip (26), the secondary cutting edge (25) gradually tilts towards the lower bottom surface (6).

6. A milling insert with a double-layer finishing structure according to claim 1, characterized in that, It also includes a tool holder (60) and a locking screw (50). The blade body (1) includes an upper surface (5), a lower bottom surface (6), and four surrounding surfaces (7). The four surrounding surfaces (7) include two side surfaces (11) and two end surfaces (10). A screw through hole (8) is provided inside the blade body (1) between the upper surface (5) and the lower bottom surface (6). A tool groove (44) is provided in the side mounting groove of the tool holder (60). The tool groove (44) includes an end support surface (40), a side support surface (41), a bottom support surface (42), and a screw countersunk hole (50). 46), the part of the end surface (10) that is adjacent to the secondary cutting edge (25) forms an end positioning surface (30), the part of the side surface (11) that is adjacent to the bottom surface (6) is recessed inward to form a side positioning surface (112), after the screw through hole (8) of the blade body (1) and the screw countersunk hole (46) of the tool bar (60) are engaged by locking screws (50), the bottom surface (6) abuts against the bottom support surface (42), the side positioning surface (112) abuts against the side support surface (41), and the end positioning surface (30) abuts against the end support surface (40).

7. A milling insert with a double-layer finishing structure according to claim 6, characterized in that, The cutting end face of the tool holder (60) forms an arc-shaped chip removal groove (61). One end of the chip removal groove (61) is connected to the clearance groove (20), and the other end is connected to the side mounting groove of the tool holder (60).

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