High-precision ball-end milling cutter

Abstract

The invention discloses a high-precision ball-end milling cutter. The high-precision ball-end milling cutter comprises a cutting blade, a cutter bar and a locking bolt, the cutting blade comprises an upper surface, a lower surface, a front peripheral surface, a rear peripheral surface, a bolt through hole, a first main cutting edge and a second main cutting edge, the upper surface comprises a first upper plane, a first upper inclined plane and a second upper plane which are connected in sequence, and the lower surface comprises a first lower plane, a second lower plane, a first lower inclined plane and a second lower inclined plane. A bolt counter bore penetrates through a cutter groove of the cutter bar, and boss structures are arranged on the two matching faces of the cutter groove respectively. The locking bolt is used for fixing the cutting blade and the cutter bar in a threaded mode. The cutting blade can improve the assembly precision and stability of the cutting blade and the cutter bar through the limiting among the second upper plane, the second lower plane, the first upper inclined plane, the first lower inclined plane and the cutter groove, and ensures that the cutting blade is mounted on the cutter bar in a correct assembly direction through the interference of the first lower plane and the second lower inclined plane.

Description

Technical Field

[0001] The invention belongs to the field of metal cutting and processing, in particular to a high-precision ball-end milling cutter. Background Art

[0002] In the field of metal processing of CNC tools, milling tools usually adopt a structural layout with more than two teeth. In theory, metal processing is a process in which each tooth of the milling tool repeatedly participates in cutting. The processing accuracy of the workpiece is proportional to the overlap of the blade profile of each tooth, which means that the higher the overlap of the blade profile, the higher the accuracy of the processed workpiece; the lower the overlap of the blade profile, the more unstable the cutting process of the tool, which is easy to cause damage to the tool and unqualified workpiece accuracy. Before the tool is used, the actual inspection is the overall accuracy of the blade installed on the tool bar. The better the overlap of the two blades, the higher the overall assembly accuracy of the tool. However, most users install the blades more casually, and the cutting blades cannot be completely and accurately installed in the tool slot, which will have a certain negative impact on the overall accuracy of the tool.

[0003] The patent with publication number CN102325620A discloses a cutting tool and a cutting tool including the same. The cutting tool is fixed to the tool holder after the asymmetric first bevel and second bevel on the rear side of the cutting tool contact the first contact surface and the second contact surface in the concave cavity at the front end of the tool holder respectively. The rear side portion of the cutting tool forms an asymmetric "V"-shaped structure to decompose the force applied to the fixing bolt, thereby preventing damage to the fixing bolt and firmly fixing the cutting tool to the tool holder.

[0004] In this scheme, the cutting tool is installed by sliding the first bevel until the second bevel contacts the second contact surface during the rotational force applied by the fixing bolt. This scheme can achieve a firm and stable joint structure, but ignores the impact of the installation process of the cutting tool's approximate radial sliding on the overall accuracy of the cutting tool. The structure in the front end cavity of the tool holder is not easy to be discovered during assembly. When the cutting tool is installed in the tool holder groove in the opposite direction (upper and lower sides are opposite), it may be mistakenly forced to be installed. Even if it is discovered and reinstalled, this will inevitably reduce the installation efficiency of the tool. Summary of the invention

[0005] The purpose of the present invention is to provide a high-precision ball-end milling cutter to solve the problems raised in the above-mentioned prior art.

[0006] A high-precision ball end milling cutter is provided, comprising:

[0007] The cutting blade comprises an upper surface, a lower surface, a front peripheral surface and a rear peripheral surface, the upper surface and the lower surface are connected and transitioned by the front peripheral surface and the rear peripheral surface, a bolt through hole runs through the upper surface and the lower surface, a first main cutting edge and a second main cutting edge are formed on both sides of the front peripheral surface respectively, the upper surface comprises a first upper plane, a first upper inclined surface and a second upper plane connected in sequence, the second upper plane is formed by being recessed inwardly relative to the first upper plane and adjacent to the second main cutting edge, the lower surface comprises a first lower plane, a second lower plane, a first lower inclined surface and a second lower inclined surface, the second lower plane is formed by being recessed inwardly relative to the first lower plane and connected and transitioned between the first lower plane and the second lower inclined surface, and the second lower plane is adjacent to the first main cutting edge;

[0008] A tool rod, one end of which has a tool groove for clamping a cutting blade, the tool groove is penetrated by a bolt countersunk hole, and two mating surfaces of the tool groove are respectively provided with boss structures mating with the second upper plane and the second lower plane;

[0009] A locking bolt is used to be threadedly connected with the bolt through hole and the bolt countersunk hole in sequence to fix the cutting blade and the tool rod.

[0010] As a further embodiment of the present invention: the intersection lines between the first lower inclined surface and the second lower inclined surface and the second lower plane respectively form an angle of 120°~150°, the intersection lines between the first lower inclined surface and the second lower inclined surface and the first lower plane respectively form an angle of 120°~150°, and the intersection line between the first upper inclined surface and the first upper plane and the intersection line between the first upper inclined surface and the second upper plane are both right angles.

[0011] As a further embodiment of the present invention: an included angle of α degrees is formed between the first upper inclined surface and the second upper plane, and the angle α is 105° to 150°.

[0012] As a further embodiment of the present invention: an angle of γ degrees is formed between the first lower inclined surface and the second lower plane, and the angle γ is 105° to 150°; an angle of θ degrees is formed between the second lower inclined surface and the second lower plane, and the angle θ is 105° to 150°.

[0013] As a further embodiment of the present invention: the angle formed between the first upper inclined surface and the second upper plane, the angle formed between the first lower inclined surface and the second lower plane, and the angle formed between the second lower inclined surface and the second lower plane are all the same.

[0014] As a further embodiment of the present invention: the first main cutting edge and the second main cutting edge extend to an end different from the rear peripheral surface and intersect to form a cutting tip, the extension line of the cutting blade passing through the cutting tip and parallel to the central axis of the shank is the central axis of the cutting blade, the central axis of the bolt through hole is perpendicular to the central axis of the cutting blade, a first intersection line is formed between the first upper inclined surface and the first upper plane, the first intersection line and the central axis of the cutting blade form two projection lines on the radial plane of the central axis of the bolt through hole, an angle of β degrees is formed between the two projection lines, and the β angle is 15°~45°.

[0015] As a further embodiment of the present invention: a second intersection line is formed between the first lower inclined surface and the first lower plane, and projection lines formed by the second intersection line and the first intersection line on the radial plane of the center axis of the bolt through hole are parallel to each other.

[0016] As a further embodiment of the present invention: a third intersection line is formed between the second lower inclined surface and the first lower plane, and the third intersection line is rotationally symmetrical with the first intersection line around the central axis of the cutting blade.

[0017] As a further embodiment of the present invention: the knife groove includes an upper clamping surface, a lower clamping surface and an end clamping surface, the upper clamping surface is provided with an upper boss that fits with the groove structure formed by the second upper plane and the first upper inclined surface, and the lower clamping surface is provided with a lower boss that fits with the groove structure formed by the second lower plane, the first lower inclined surface and the second lower inclined surface.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The clamping accuracy of the cutting blade will directly affect the overall accuracy of the ball end mill. The clamping process of the cutting blade is divided into two processes: pre-installation and locking. Since the second upper plane and the second lower plane and the first upper bevel and the first lower bevel are arranged left and right and upside down on the cutting blade, during the pre-installation process, under the limiting effect of the first upper bevel and the first lower bevel and the tool groove respectively, the cutting blade can be guided to a relatively correct installation position, and the center of rotation of the cutting blade is pushed closer to the center of rotation of the tool rod, eliminating the early influence on the pre-positioning accuracy of the cutting blade. During the locking process, the cutting blade approaches the bottom surface of the tool groove, and at the same time, it has a tendency to cause relative rotation due to the friction of the locking bolt, but the tendency of relative rotation can be offset by the resistance provided by the first upper bevel and the first lower bevel.

[0020] 2. Before the cutting blade is replaced, the general practice is to change the tool outside the machine, that is, remove the ball end mill from the machine tool, reinstall the new blade, and reinstall it on the machine tool spindle after it is tested and qualified on the instrument. Repeated installation will not only cause loss of the overall accuracy of the ball end mill, but the machine tool also needs to be re-calibrated, which adds additional time cost. In the technical solution of the present invention, the tool change is realized in the machine, and the cutting blade will have a tendency to move vertically downward due to gravity. At this time, the first upper bevel and the first lower bevel will decompose the gravity on the cutting blade, and the decomposed force perpendicular to the two bevels will press the cutting blade into the tool groove. With the cooperation of the pre-installation accuracy, the risk of the cutting blade falling during the disassembly and clamping process is reduced, the reuse rate of the blade is improved, and it is more conducive to realizing rapid tool change in the machine.

[0021] 3. The ball-end milling cutter installed in a single piece has two cutting edges, the first main cutting edge and the second main cutting edge. In order to achieve higher outer diameter accuracy, the manufacturing of the cutting blade edge type is more economical and the common practice is to use the tool bar as a machine tool fixture for integrated peripheral grinding. During actual clamping, when the orientation of the cutting blade mounting surface and the tool bar during installation is consistent with the orientation of the cutting blade and the tool bar during on-machine grinding, the rotational overlap of the two edges is good and the blade accuracy can generally be maintained; when the orientation of the cutting blade mounting surface is opposite to the orientation during on-machine grinding (the upper and lower surfaces are reversed), the possibility of deviation in the rotational overlap of the two edges will increase. In this technical solution, when the cutting blade is installed in the opposite direction, the second lower plane and the second lower bevel will interfere with the boss structure on the tool groove, preventing the cutting blade from being installed in the opposite direction, and restricting the installation of the cutting blade to be completed according to the original grinding assembly rules, so that the loss of rotational overlap accuracy of the two edges can be small. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 A is a three-dimensional diagram of a ball-end blade provided by the present invention;

[0024] Figure 2 FIG. B is a three-dimensional view of a ball-end blade provided by the present invention;

[0025] Figure 3 FIG. A is a top view of a ball-end insert provided by the present invention;

[0026] Figure 4 FIG. B is a top view of the ball-end insert provided by the present invention;

[0027] Figure 5 is a side view of the ball-end blade provided by the present invention;

[0028] Figure 6 is a front view of the ball-end blade provided by the present invention;

[0029] Figure 7 yes Figure 3 A cross-sectional view of the middle blade at position E;

[0030] Figure 8 yes Figure 4 A cross-sectional view of the middle blade at position G;

[0031] Fig. 9 yes Figure 4 A cross-sectional view of the middle blade F position;

[0032] Fig.10 It is a structural exploded diagram of the ball end milling cutter provided by the present invention;

[0033] Fig.11 is a side view of the knife bar provided by the present invention;

[0034] Fig.12 is a structural perspective view of the knife bar provided by the present invention;

[0035] Fig.13 It is a perspective view of the forward installation of the ball end milling cutter provided by the present invention;

[0036] Fig.14 It is a perspective view of the reverse installation of the ball end milling cutter provided by the present invention.

[0037] In the figure: 1, cutting blade; 2, locking bolt; 3, tool bar; 4, upper surface; 5, lower surface; 6, rear peripheral surface; 7, first main cutting edge; 8, second main cutting edge; 9, bolt through hole; 10, tool tip; 11, front peripheral surface; 12, first upper plane; 13, first upper inclined surface; 14, second upper plane; 16, upper depression; 17, first intersection line; 18, second intersection line; 19, third intersection line; 22, first lower plane; 23, first lower inclined surface; 24, second lower plane; 25, second lower inclined surface; 26, lower depression; 30, tool groove; 31, upper clamping surface; 32, lower clamping surface; 33, end clamping surface; 34, bolt countersunk hole; 41, upper boss; 42, lower boss; 51, first upper clamping inclined surface; 52, first lower clamping inclined surface; 53, second lower clamping inclined surface. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0039] Obviously, the drawings described below are only some examples or embodiments of the present invention. For ordinary technicians in this field, the present invention can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed by the present invention, some changes in design, manufacturing or production based on the technical content disclosed by the present invention are just conventional technical means, and should not be understood as insufficient content disclosed by the present invention.

[0040] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present invention and are not intended to limit the subject matter described in the claims.

[0041] See also Figure 1-Figure 14As shown, the high-precision ball end milling cutter in the embodiment of the present invention comprises a cutting insert 1, a tool bar 3 and a locking bolt 2. The cutting insert 1 comprises an upper surface 4, a lower surface 5, a front peripheral surface 11 and a rear peripheral surface 6, the upper surface 4 and the lower surface 5 are connected and transitioned through the front peripheral surface 11 and the rear peripheral surface 6, a bolt through hole 9 is penetrated between the upper surface 4 and the lower surface 5, a first main cutting edge 7 and a second main cutting edge 8 are formed on both sides of the front peripheral surface 11, the upper surface 4 comprises a first upper plane 12, a first upper inclined surface 13 and a second upper plane 14 connected in sequence, the second upper plane 14 is formed by being recessed inwardly relative to the first upper plane 12 and adjacent to the second main cutting edge 8, the lower surface 5 comprises a first lower plane 22, a second lower plane 24, a first lower inclined surface 23 and a second lower inclined surface 25, the second lower plane 24 is formed by being recessed inwardly relative to the first lower plane 22 and connected and transitioned with the first lower plane 22 through the first lower inclined surface 23 and the second lower inclined surface 25, and the second lower plane 24 is adjacent to the first main cutting edge 7. One end of the shank 3 has a shank 30 for clamping the cutting blade 1. A bolt countersunk hole 34 runs through the shank 30. Two mating surfaces of the shank 30 are respectively provided with boss structures that match the second upper plane 14 and the second lower plane 24. The locking bolt 2 is used to be threadedly connected with the bolt through hole 9 and the bolt countersunk hole 34 in sequence to fix the cutting blade 1 to the shank 3.

[0042] Among them, the cutting blade 1 is a cemented carbide product, which is made into a blank through powder metallurgy technology, and then the finished product is obtained through a deep processing process. The deep processing process is specifically to clamp the blank-shaped blade through the tool bar 3 as a machine tool fixture, and grind it on a grinding machine to process the various parts of the cutting blade 1, including the second upper plane 14 and the second lower plane 24 arranged in opposite directions up and down and on both sides. The second upper plane 14 is limited between the first upper bevel 13 and the second main cutting edge 8, and the second lower plane 24 is limited between the first lower bevel 23, the second lower bevel 25 and the first main cutting edge 7.

[0043] Specifically, see Figure 3 , Figure 4 , Fig.10 , Fig.13 , Fig.14As shown, the intersection lines of the first lower bevel 23 and the second lower bevel 25 respectively connected with the second lower plane 24 form an angle of 120° to 150°, and the intersection lines of the first lower bevel 23 and the second lower bevel 25 respectively connected with the first lower plane 22 form an angle of 120° to 150°. The intersection lines of the first upper bevel 13 and the first upper plane 12 and the intersection lines of the first upper bevel 13 and the second upper plane 14 are both straight angles. The second upper plane 14 and the second lower plane 24 have different groove structures to ensure that the assembly direction between the cutting blade 1 and the tool bar 3 when the ball end mill is used is the same as the assembly direction when the cutting blade 1 is assembled on the tool bar 3 for grinding (affected by the processing accuracy, reverse installation may cause a large offset between the rotation axis of the cutting blade 1 and the rotation axis of the tool bar 3), thereby avoiding the situation where the rotation overlap accuracy of the first main cutting edge 7 and the second main cutting edge 8 is reduced due to reverse installation.

[0044] See also Figure 10-12 As shown, the tool groove 30 includes an upper clamping surface 31, a lower clamping surface 32 and an end clamping surface 33. The upper clamping surface 31 is provided with an upper boss 41 that fits with the groove structure formed by the second upper plane 14 and the first upper inclined surface 13, and the lower clamping surface 32 is provided with a lower boss 42 that fits with the groove structure formed by the second lower plane 24, the first lower inclined surface 23 and the second lower inclined surface 25. The upper boss 41 and the lower boss 42 can limit the axial displacement, radial displacement and circumferential displacement of the cutting blade 1, and can improve the cutting stability of the ball end milling cutter and the surface processing quality of the workpiece. The end clamping surface 33 is perpendicular to the rotation center B of the tool rod 3, and is used to receive the rear peripheral surface 6 of the cutting blade 1 to provide support for the rear peripheral surface 6. The bolt countersunk hole 34 is used to place the locking bolt 2, and the bolt countersunk hole 34 passes through the tool rod 3 and is perpendicular to the upper clamping surface 31 and the lower clamping surface 32.

[0045] See also Figure 5 and Figure 6As shown, the first upper plane 12 and the first lower plane 22 are realized by surface grinding with a double-end machine tool, and are used to cooperate with the upper clamping surface 31 and the lower clamping surface 32 of the tool groove 30 to improve the normal positioning accuracy of the cutting blade 1 in the tool groove 30. The front peripheral surface 11 includes a first main cutting edge 7, a second main cutting edge 8, and a tip 10 formed by the two main cutting edges extending to an end different from the rear peripheral surface 6 and intersecting. The extension line of the cutting blade 1 passing through the tip 10 and parallel to the central axis of the tool rod 3 is the central axis A of the cutting blade 1. The first main cutting edge 7 and the second main cutting edge 8 are semicircular structures and rotationally symmetrical around the central axis A of the cutting blade 1, ensuring that the two main cutting edges have a high rotational coincidence accuracy. The rear peripheral surface 6 is a plane and is perpendicular to the first upper plane 12, the first lower plane 22 and the central axis A of the cutting blade 1. The rear peripheral surface 6 is an axial positioning surface, which is used to fit with the end clamping surface 33. The bolt through hole 9 is a straight hole disposed inside the cutting blade 1 , penetrating through and perpendicular to the first upper plane 12 and the first lower plane 22 .

[0046] See also Figure 3 and Figure 7 As shown, the first upper plane 12 and the second upper plane 14 are transitioned through the first upper inclined surface 13. In order to make the installation guiding function of the cutting blade 1 in the groove 30 more obvious and provide sufficient friction component for the cutting blade 1, the angle α formed by the first upper inclined surface 13 and the second upper plane 14 is selected to be 105°≤α≤150°, and this scheme preferably has α=135°. The first upper plane 12 and the second upper plane 14 are parallel to each other, the second upper plane 14 is lower in elevation than the first upper plane 12, the second upper plane 14 is limited by the first upper inclined surface 13, and extends to the rear peripheral surface 6 and the front peripheral surface 11, the second upper plane 14 and the first upper inclined surface 13 form an upper depression 16 relative to the first upper plane 12, the upper boss 41 is complementary to the upper depression 16, and the depth of the upper depression 16 is preferably 1 / 4 of the maximum thickness H of the cutting blade 1. A first intersection line 17 is formed between the first upper inclined surface 13 and the first upper plane 12. The first intersection line 17 and the central axis of the cutting blade 1 form two projection lines on the radial plane of the central axis of the bolt through hole 9. An angle of β degrees is formed between the two projection lines, and 15°≤β≤45° is selected. In this scheme, β=20° is preferred, and the first intersection line 17 cannot pass through the bolt through hole 9.

[0047] See also Figure 4 , Figure 8 and Fig. 9As shown, the first lower plane 22 and the second lower plane 24 transition through the first lower inclined surface 23 and the second lower inclined surface 25. Similarly, in order to make the installation guide function of the cutting blade 1 in the tool groove 30 more obvious and provide sufficient friction component for the cutting blade 1, the angle γ formed by the first lower inclined surface 23 and the second lower plane 24 is selected to be 105°≤γ≤150°, and this solution preferably has γ=135°; the angle θ formed by the second lower inclined surface 25 and the second lower plane 24 is selected to be 105°≤θ≤150°, and this solution preferably has θ=135°.

[0048] Preferably, the angle α formed between the first upper inclined surface 13 and the second upper plane 14, the angle γ formed between the first lower inclined surface 23 and the second lower plane 24, and the angle θ formed between the second lower inclined surface 25 and the second lower plane 24 are all the same to ensure balanced forces in all directions.

[0049] See also Figure 1 , Figure 5 , Fig.12 , Fig.13 As shown, the first lower plane 22 and the second lower plane 24 are parallel to each other, the second lower plane 24 is lower than the first lower plane 22, the second lower plane 24 is limited by the first lower bevel 23 and the second lower bevel 25, and extends to the rear peripheral surface 6 and the front peripheral surface 11. The second lower plane 24, the first lower bevel 23 and the second lower bevel 25 form a lower depression 26 relative to the first lower plane 22, the lower boss 42 and the lower depression 26 are complementary in structure, and the depth of the lower depression 26 is preferably 1 / 4 of the maximum thickness H of the cutting insert 1. The first lower plane 22 and the first lower bevel 23 form a second intersection line 18, and the projection lines formed by the second intersection line 18 and the first intersection line 17 on the radial plane of the central axis of the bolt through hole 9 are parallel to each other, and the second intersection line 18 cannot penetrate the bolt through hole 9, so as to achieve precise limiting and guiding effects when the cutting insert 1 is pre-installed. The first lower plane 22 and the second lower inclined surface 25 form a third intersection line 19, and the third intersection line 19 is rotationally symmetrical with the first intersection line 17 around the central axis A of the cutting blade 1, avoiding local stress between the tool groove 30 and the cutting blade 1 when a single main cutting edge of the cutting blade 1 is subjected to force, thereby achieving force balance.

[0050] Specifically, see Figure 2 , Fig.10 , Figure 12-13As shown, the upper boss 41 includes a first upper clamping bevel 51, and the lower boss 42 includes a first lower clamping bevel 52 and a second lower clamping bevel 53. The installation of the cutting blade 1 is to gradually push the cutting blade 1 into the tool groove 30 along the direction of the first intersection line 17 with the first upper bevel 13 as the guide surface. The first upper bevel 13 first and always slides in contact with the first upper clamping bevel 51, and then the first lower bevel 23 contacts and slides relatively with the first lower clamping bevel 52 until the second lower bevel 25 is completely fitted with the second lower clamping bevel 53. The pre-installation is correctly completed. The locking bolt 2 fixes the cutting blade 1 in the tool groove 30 through the bolt countersunk hole 34 to form a ball end milling cutter. The ball end milling cutter is installed on the spindle of the machine tool for cutting.

[0051] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the main purpose of the present invention, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A high-precision ball end milling cutter, characterized in that: include: A cutting blade (1) comprises an upper surface (4), a lower surface (5), a front peripheral surface (11) and a rear peripheral surface (6); the upper surface (4) and the lower surface (5) are connected and transitioned through the front peripheral surface (11) and the rear peripheral surface (6); a bolt through hole (9) penetrates between the upper surface (4) and the lower surface (5); a first main cutting edge (7) and a second main cutting edge (8) are formed on both sides of the front peripheral surface (11); the upper surface (4) comprises a first upper plane (12), a first upper inclined surface (13) and a second upper plane (14) which are connected in sequence The second upper plane (14) is formed by being recessed inwardly relative to the first upper plane (12) and is adjacent to the second main cutting edge (8); the lower surface (5) comprises a first lower plane (22), a second lower plane (24), a first lower inclined surface (23) and a second lower inclined surface (25); the second lower plane (24) is formed by being recessed inwardly relative to the first lower plane (22) and is connected to the first lower plane (22) via the first lower inclined surface (23) and the second lower inclined surface (25); the second lower plane (24) is adjacent to the first main cutting edge (7); A tool rod (3), one end of which is provided with a tool groove (30) for clamping a cutting blade (1), a bolt countersunk hole (34) passing through the tool groove (30), and two mating surfaces of the tool groove (30) are respectively provided with boss structures mating with a second upper plane (14) and a second lower plane (24); A locking bolt (3) is used to be threadedly connected with a bolt through hole (9) and a bolt countersunk hole (34) in sequence to fix the cutting blade (1) and the tool rod (3).

2. A high-precision ball end milling cutter according to claim 1, characterized in that: The intersection lines between the first lower inclined surface (23) and the second lower inclined surface (25) and the second lower plane (24) respectively form an angle of 120° to 150°, the intersection lines between the first lower inclined surface (23) and the second lower inclined surface (25) and the first lower plane (22) respectively form an angle of 120° to 150°, and the intersection line between the first upper inclined surface (13) and the first upper plane (12) and the intersection line between the first upper inclined surface (13) and the second upper plane (14) are both straight angles.

3. A high-precision ball end milling cutter according to claim 1, characterized in that: An included angle of α is formed between the first upper inclined surface (13) and the second upper plane (14), and the angle α is 105° to 150°.

4. A high-precision ball end milling cutter according to claim 1, characterized in that: An included angle of γ degrees is formed between the first lower inclined surface (23) and the second lower plane (24), and the γ angle is 105° to 150°. An included angle of θ degrees is formed between the second lower inclined surface (25) and the second lower plane (24), and the θ angle is 105° to 150°.

5. A high-precision ball end milling cutter according to claim 3 or 4, characterized in that: The angle formed between the first upper inclined surface (13) and the second upper plane (14), the angle formed between the first lower inclined surface (23) and the second lower plane (24), and the angle formed between the second lower inclined surface (25) and the second lower plane (24) are all the same.

6. A high-precision ball end milling cutter according to claim 1, characterized in that: The first main cutting edge (7) and the second main cutting edge (8) extend to an end different from the rear peripheral surface (6) and intersect to form a cutting tip (10); an extension line of the cutting blade (1) passing through the cutting tip (10) and parallel to the central axis of the shank (3) is taken as the central axis of the cutting blade (1); the central axis of the bolt through hole (9) is perpendicular to the central axis of the cutting blade (1); a first intersection line (17) is formed between the first upper inclined surface (13) and the first upper plane (12); the first intersection line (17) and the central axis of the cutting blade (1) form two projection lines on a radial plane of the central axis of the bolt through hole (9); an angle of β degrees is formed between the two projection lines, and the β angle is 15° to 45°.

7. A high-precision ball end milling cutter according to claim 6, characterized in that: A second intersection line (18) is formed between the first lower inclined surface (23) and the first lower plane (22), and projection lines formed by the second intersection line (18) and the first intersection line (17) on a radial plane of the central axis of the bolt through hole (9) are parallel to each other.

8. The high-precision ball end milling cutter according to claim 6, characterized in that: A third intersection line (19) is formed between the second lower inclined surface (25) and the first lower plane (22), and the third intersection line (19) is rotationally symmetrical with the first intersection line (17) around the central axis of the cutting blade (1).

9. The high-precision ball end milling cutter according to claim 1, characterized in that: The knife groove (30) comprises an upper clamping surface (31), a lower clamping surface (32) and an end clamping surface (33); the upper clamping surface (31) is provided with an upper boss (41) which fits with the groove structure formed by the second upper plane (14) and the first upper inclined surface (13); the lower clamping surface (32) is provided with a lower boss (42) which fits with the groove structure formed by the second lower plane (24), the first lower inclined surface (23) and the second lower inclined surface (25).

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