End mill and manufacturing method thereof
By using a cubic boron nitride end mill and designing a negative chamfer structure and a second flank face, the problem of easy wear of traditional end mills is solved, achieving optimized tool strength and improved machining quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional milling cutters are prone to wear when machining small parts made of difficult-to-machine materials such as stainless steel, high-temperature alloys, and titanium alloys, leading to a decrease in machining efficiency and quality.
End mills made of cubic boron nitride (CBN) are designed with a negative chamfer structure and a second flank face to increase the cutting edge thickness, optimize tool strength, improve chip removal, and reduce wear.
Extend tool life, improve surface finish, and meet the high precision requirements of difficult-to-machine materials.
Smart Images
Figure CN121732872A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of machining tool technology, and in particular to an end mill and its manufacturing method. Background Technology
[0002] With the development of science and technology, the demand for high-precision micro parts is increasing day by day. However, the processing and manufacturing of high-precision micro parts is quite difficult. Stainless steel, high-temperature alloys, titanium alloys and other difficult-to-machine materials generally have the characteristics of high plasticity and high strength. When using these difficult-to-machine materials to make high-precision micro parts, the processing and manufacturing difficulty is further increased.
[0003] Traditional milling cutters are mostly made of high-speed steel and cemented carbide, which are prone to wear. The cutting edge of traditional milling cutters is very thin, and they are easily damaged by cutting forces during the cutting process, which can easily cause wear of the milling cutters (especially micro milling cutters), affecting machining efficiency and machining quality. Summary of the Invention
[0004] The purpose of this invention is to provide an end mill and its manufacturing method to solve the problems existing in the prior art, thereby optimizing the tool strength, extending the tool life, and improving the quality of the machined surface.
[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides an end mill, including a working section of the cutter body. The working section of the cutter body has a bottom cutting edge. The working section of the cutter body has a rake face and a flank face system on the front and rear sides of each bottom cutting edge. The flank face system includes a first flank face and a second flank face that are in contact with each other. A negative chamfer structure is provided at the tip of the cutting edge where the rake face intersects with the first flank face. The material of the working section of the cutter body is cubic boron nitride.
[0006] Preferably, the flank face system is a straight flank face.
[0007] Preferably, the width of the negative chamfer structure is 1 / 4 to 1 / 3 of the length of the corresponding bottom edge.
[0008] Preferably, the chamfer angle of each of the negative chamfer structures is 10°~15°.
[0009] Preferably, the chamfer angle of each of the negative chamfer structures is 12°.
[0010] The present invention also provides a method for manufacturing an end mill, comprising the following steps: S1. Obtain the first bar material of cubic boron nitride; S2. Machining the working section of the tool body: Machining a rake face, a first flank face, and a second flank face on the first bar, and machining a negative chamfer structure at the tip where the rake face intersects with the first flank face.
[0011] Preferably, S1 further includes: obtaining a second bar, one end of which is provided with a mounting hole; placing the first end of the first bar in the mounting hole, so that the second end of the first bar is located outside the mounting hole; and welding the first bar and the second bar to form a milling cutter blank. At least two spiral grooves are cut on the outer side wall of the second end of the first bar to form the first processed part; The rake face, the first flank face, and the second flank face are cut and machined at the second end of the first bar. The negative chamfer structure is machined at the tip where the rake face and the first flank face intersect, forming the second machined part.
[0012] Preferably, each of the spiral grooves, bottom cutting edges, and negative chamfer structures of the second processed part is ground.
[0013] Preferably, the method for obtaining the first bar includes: obtaining an initial bar and performing a diameter reduction process on the initial bar using a laser processing method to obtain the first bar.
[0014] Preferably, the spiral groove, the front face, the back face system, and the negative chamfer structure are cut using wire electrical discharge machining (EDM).
[0015] The present invention achieves the following technical effects compared to the prior art: This invention provides an end mill and its manufacturing method, including a working section of the cutter body, the working section of the cutter body having a bottom cutting edge, and the working section of the cutter body having a rake face and a flank face system on the front and rear sides of each bottom cutting edge, the flank face system including a first flank face and a second flank face that are in contact with each other, and a negative chamfer structure is provided at the tip of the cutting edge where the rake face intersects with the first flank face, and the material of the working section of the cutter body is cubic boron nitride.
[0016] Cubic boron nitride (CBN) is an ultrahard material with high hardness and wear resistance, capable of withstanding significant cutting forces. The negative chamfer structure increases the cutting edge thickness, withstands friction, reduces wear on the main cutting edge, and minimizes chipping. Furthermore, the negative chamfer structure alters the contact state between the chips and the tool, allowing chips to flow more easily along the chamfer surface, reducing chip wear on the tool edge, optimizing tool strength, extending tool life, and meeting the demands of high-quality precision machining of difficult-to-machine materials. The second flank face increases the clearance between the tool and the workpiece, protecting the machined surface and extending tool life. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the working section of the cutter body provided in Example 1; Figure 2 This is a schematic diagram of the negative chamfer structure provided in Example 1; Figure 3 A side view of the end mill provided in Example 1; Figure 4 A top view of the end mill provided in Example 1; Figure 5 This is a front view of the end mill provided in Example 1; Figure 6 for Figure 5 Sectional view of AA; Figure 7 This is a schematic diagram of the end mill provided in Example 1; Figure 8 This is a schematic diagram showing the relative positions of the tapered grinding wheel and the end mill; In the diagram: 100, end mill; 1, working section of the cutter body; 2, bottom cutting edge; 3, rake face; 4, first flank face; 5, second flank face; 6, negative chamfer structure; 7, helical groove; 8, straight flank face; 9, circumferential flank face; 10, shank section; 11, conical section; 12, grinding wheel; a, chamfer angle; b, helix angle; c, rake angle of the main cutting edge; d, bottom cutting edge clearance angle; e, circumferential cutting edge clearance angle; L, width of the negative chamfer structure. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] The purpose of this invention is to provide an end mill and its manufacturing method to solve the problems existing in the prior art, thereby optimizing the tool strength, extending the tool life, and improving the quality of the machined surface.
[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0022] Example 1 like Figures 1-8 As shown, this embodiment provides an end mill 100, including a working section 1 of the cutter body. The working section 1 of the cutter body has a bottom cutting edge 2. The working section 1 of the cutter body has a rake face 3 and a flank face system on the front and rear sides of each bottom cutting edge 2, respectively. The flank face system includes a first flank face 4 and a second flank face 5 that are in contact with each other. A negative chamfer structure 6 is provided at the tip of the cutting edge where the rake face 3 intersects with the first flank face 4. The material of the working section 1 of the cutter body is cubic boron nitride. It should be noted that the working section 1 of the cutter body is the cutting edge part of the end mill 100; the front side of the bottom cutting edge 2 is the side that first contacts the workpiece material and begins cutting when the cutter cuts the workpiece; the rear side of the bottom cutting edge 2 is the side that contacts the workpiece material last and begins cutting when the cutter cuts the workpiece. Cubic boron nitride (CBN) is an ultrahard material with high hardness and wear resistance, capable of withstanding significant cutting forces. A negative chamfer structure 6 is machined at the tip of the cutting edge where the rake face 3 intersects with the first flank face 4, increasing the cutting edge thickness. This negative chamfer structure 6 can withstand a certain amount of friction, reducing wear on the main cutting edge and minimizing chipping. Furthermore, the negative chamfer structure 6 alters the contact state between the chips and the tool, making it easier for chips to flow along its surface, reducing chip wear on the tool edge, optimizing tool strength, extending tool life, and meeting the high-quality precision machining requirements of difficult-to-machine materials. A second flank face 5 is provided to increase the clearance between the tool and the workpiece, protecting the machined surface and extending tool life.
[0023] By rationally designing the geometry and angle of the second flank face 5, the curling radius and discharge direction of the chips can be adjusted, which is more conducive to guiding the chips out of the cutting area and preventing chips from accumulating between the tool and the workpiece, thereby improving the quality of the machined surface. It can also optimize the contact and friction between the tool and the workpiece, reduce the cutting force, and reduce the heat generated during the cutting process, which is beneficial to extending the tool's service life and improving machining accuracy. Since tool wear is mainly caused by mechanical wear, thermal wear, and other factors, the second flank face 5 can improve chip discharge and reduce the cutting force, thus reducing abnormal tool wear, such as adhesive wear (wear caused by the adhesion of chips to the flank face) and abrasive wear (wear of the tool by hard particles in the workpiece material), thereby extending the effective service life of the tool.
[0024] Furthermore, the flank face system is a straight flank face 8, which refers to a form where the flank face is a plane. It has a simple and regular shape and is easy to machine.
[0025] Furthermore, the width L of the negative chamfer structure is 1 / 4 to 1 / 3 of the length of the corresponding bottom edge 2.
[0026] Furthermore, the chamfer angle α of each negative chamfer structure 6 is 10°~15°, preferably 12°.
[0027] Furthermore, the working section 1 of the cutter body is also machined with a helical groove 7, and the working section 1 of the cutter body is also provided with a circumferential cutting edge and a circumferential flank face 9. The helix angle b of the milling cutter adopts an unequal division design, that is, the helix angle b of the milling cutter cutting edge along the circumferential direction is not uniformly distributed.
[0028] Furthermore, this embodiment also includes a shank section 10 and a conical section 11, which are sequentially connected. The end mill 100 of this embodiment has a tip diameter of 0.5 mm, a shank section 10 diameter of 3 mm, and a working section 1 length of 1.0 mm. The helix angle b of the tool is 30°, the rake angle c of the main cutting edge is 3°, and the first clearance angle of the bottom cutting edge 2 is 15°. The tool also has a bottom cutting edge clearance angle d and a circumferential cutting edge clearance angle e. The definitions of the helix angle b, the rake angle c of the main cutting edge, the first clearance angle of the bottom cutting edge 2, the bottom cutting edge clearance angle d, and the circumferential cutting edge clearance angle e are existing technologies and will not be elaborated here.
[0029] Example 2 This embodiment provides a method for manufacturing an end mill 100, including the following steps: S1. Obtain the first bar material of cubic boron nitride; S2. Machining the working section 1 of the tool body: Machining the rake face 3, the first flank face 4 and the second flank face 5 on the first bar, and machining the negative chamfer structure 6 at the tip where the rake face 3 and the first flank face 4 intersect.
[0030] Furthermore, S1 also includes: obtaining a second bar, one end of which is provided with a mounting hole; placing the first end of the first bar inside the mounting hole, so that the second end of the first bar is outside the mounting hole; and welding the first bar and the second bar to form a milling cutter blank. At least two spiral grooves 7 are cut on the outer side wall of the second end of the first bar to form the first machined part; A rake face 3, a first flank face 4, and a second flank face 5 are cut and machined at the second end of the first bar. A negative chamfer structure 6 is machined at the tip where the rake face 3 and the first flank face 4 intersect, forming the second machined part.
[0031] Furthermore, grinding is performed on each spiral groove 7, each bottom edge 2, and each negative chamfer structure 6 of the second workpiece, thereby improving machining accuracy and obtaining higher cutting edge quality; at the same time, it can ensure the machining limit of the tool diameter to realize the machining of the micro end mill 100.
[0032] Furthermore, the grinding wheel 12 used in the grinding process is a resin-bonded diamond grinding wheel (2000#), and the cooling method is oil cooling. The machine tool used is a Makino six-axis CNC tool grinder CNS7d, and the specific grinding process parameters are: grinding speed of 20m / s, grinding depth of 1μm, and feed rate of 8mm / min.
[0033] Furthermore, the method for obtaining the first bar includes: obtaining an initial bar and reducing the diameter of the initial bar by laser processing to obtain the first bar. For example, the diameter of the first bar can be 0.5 mm, which has high processing efficiency.
[0034] Furthermore, a picosecond pulsed laser with a wavelength of 1064nm is used, and the laser processing parameters are: laser power of 20W, laser frequency of 800kHz, laser scanning speed of 400mm / s, and spindle speed of 1000r / min. Through laser diameter reduction processing, the initial bar diameter is reduced, for example, a first bar with a diameter of 0.5mm can be obtained.
[0035] Furthermore, the spiral groove 7, the front cutting face 3, the first flank cutting face 4, the second flank cutting face 5, and the negative chamfer structure 6 are cut using wire electrical discharge machining.
[0036] Specifically, the end mill 100 manufacturing method provided in this embodiment mainly includes three processes: welding of the end mill blank, rough machining by wire electrical discharge machining, and precision grinding.
[0037] 1. The welding process includes: Prepare a second bar stock made of cemented carbide material with a central mounting hole. The second bar stock has a diameter of 3mm, the mounting hole has a diameter of 1.1mm and a depth of 1-1.5mm, and the coaxiality between the second bar stock and the mounting hole is less than 50µm. Insert a first bar stock with a diameter of 0.5mm into the mounting hole and weld it into shape. After welding, the polycrystalline CBN tool bar stock is rough-machined using wire electrical discharge machining.
[0038] 2. Electrical discharge wire cutting processing includes: A micro-electrical discharge milling method was employed, using a cylindrical electrode made of cemented carbide. Two symmetrically distributed helical grooves 7, each 0.3 mm wide, 0.15 mm deep, and with a helix angle b of 30°, were machined into a first bar stock. The welded milling cutter blank was mounted on a rotating shaft on the worktable. During machining, the rotating shaft was completely submerged in the working fluid to reduce the thermal impact of the discharge. A three-section structure was cut, including a shank section 10, a conical section 11, and a working section. The diameter of the rough-machined working section completely exposed the polycrystalline CBN. The peak current during machining was 6 A, the peak voltage was 120 V, the pulse width was 5 μs, and the pulse frequency was 160 kHz.
[0039] 3. Precision grinding includes: chamfering grinding, spiral fluting (7) grinding, circumferential flank grinding (9) grinding, and bottom edge grinding (2), as detailed below: Spiral groove 7 grinding: For roughing, the single cutting depth is 0.02mm; the number of feeds is 3; the feed rate is 800mm / min; and the grinding wheel rotation speed is 1400m / min. For finishing, the single cutting depth is 0.004mm; the number of feeds is 1; the feed rate is 800mm / min; and the grinding wheel rotation speed is 1400m / min.
[0040] Grinding of the bottom cutting edge 2: A resin-bonded diamond grinding wheel is used for grinding at a feed rate of 800 mm / min and a wheel rotation speed of 1400 m / min. The grinding of the bottom cutting edge 2 mainly includes grooving the bottom cutting edge 2, grinding the first flank face 4 of the bottom cutting edge 2, and grinding the second flank face 5 of the bottom cutting edge 2. The grinding sequence is: grooving the bottom cutting edge 2, grinding the second flank face 5, and grinding the first flank face 4.
[0041] Grinding of the circumferential flank face 9: The circumferential flank face 9 is machined using a conical grinding wheel. The grinding of the circumferential flank face 9 is completed by the grinding wheel making a helical motion along the cutting edge of the end mill. The relative position of the conical grinding wheel and the end mill 100 is as follows: Figure 8 As shown.
[0042] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.
Claims
1. An end mill, characterized in that: The tool includes a working section with a bottom cutting edge. The working section has a front cutting edge and a rear cutting edge system on the front and rear sides of each bottom cutting edge. The rear cutting edge system includes a first rear cutting edge and a second rear cutting edge that are in contact with each other. A negative chamfer structure is provided at the tip of the cutting edge where the front cutting edge intersects with the first rear cutting edge. The working section is made of cubic boron nitride.
2. The end mill according to claim 1, characterized in that: The flank face system is a straight flank face.
3. The end mill according to claim 1, characterized in that: The width of the negative chamfer structure is 1 / 4 to 1 / 3 of the length of the corresponding bottom edge.
4. The end mill according to claim 1, characterized in that: The chamfer angle of each of the negative chamfer structures is 10°~15°.
5. The end mill according to claim 1, characterized in that: The chamfer angle of each of the aforementioned negative chamfer structures is 12°.
6. A method for manufacturing an end mill, characterized in that: Includes the following steps: S1. Obtain the first bar material of cubic boron nitride; S2. Machining the working section of the tool body: Machining a rake face, a first flank face, and a second flank face on the first bar, and machining a negative chamfer structure at the tip where the rake face intersects with the first flank face.
7. The end mill manufacturing method according to claim 6, characterized in that: S1 further includes: obtaining a second bar, one end of which is provided with a mounting hole; placing the first end of the first bar in the mounting hole, so that the second end of the first bar is located outside the mounting hole; and welding the first bar and the second bar to form a milling cutter blank. At least two spiral grooves are cut on the outer side wall of the second end of the first bar to form the first processed part; The rake face, the first flank face, and the second flank face are cut and machined at the second end of the first bar. The negative chamfer structure is machined at the tip where the rake face and the first flank face intersect, forming the second machined part.
8. The method for manufacturing an end mill according to claim 7, characterized in that: The spiral grooves, bottom cutting edges, and negative chamfer structures of the second workpiece are ground.
9. The method for manufacturing an end mill according to claim 6, characterized in that: The method for obtaining the first bar includes: obtaining an initial bar and performing a diameter reduction process on the initial bar using a laser processing method to obtain the first bar.
10. The method for manufacturing an end mill according to claim 7, characterized in that: The spiral groove, the front face, the back face system, and the negative chamfer structure are cut using wire electrical discharge machining.