Cutter and method of manufacturing the same

Abstract

The application discloses a cutter and a preparation method thereof. The cutter comprises a cutter head with a cutter tooth, the cutter head has a porous structure, a polycrystalline diamond film is arranged on the surface of the cutter tooth and the arc surface around the cutter tooth respectively, the polycrystalline diamond film comprises a transition layer extending into the porous structure and a superhard film layer on the surface of the transition layer, the transition layer comprises nanoscale polycrystalline diamond crystals, and the superhard film layer comprises microscale polycrystalline diamond crystals. The polycrystalline diamond film is formed on the surface and around the cutter tooth, the hardness, wear resistance and shock resistance of the cutter head are improved, the service life of the cutter is prolonged, the manufacturing cost is reduced, high-speed milling of the cutter is realized, and the machining efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tool machining, in particular to a tool for machining hard and brittle materials and a preparation method thereof. BACKGROUND

[0002] In the field of mechanical machining, most tools are used to machine hard materials, even super-hard materials. However, for hard and brittle materials such as glass and ceramic, traditional forming tools (such as diamond electroplated grinding heads) often cannot meet the requirements. These traditional forming tools have low hardness, poor wear resistance and short service life, and need to be frequently replaced during machining, thereby increasing the machining cost. Moreover, the shock absorption effect is poor, the quality is heavy, and the tools are not suitable for high-speed milling. When machining hard and brittle materials, the surface of the traditional forming tools is prone to collapse, and the milling precision is low, thereby making the surface quality of the machined products uneven, the machining efficiency low and the machining requirements unable to be met. SUMMARY

[0003] In view of the above, it is necessary to provide an ultra-hard tool for machining brittle materials and improving the surface quality of the machined brittle materials.

[0004] In addition, the present application also provides a preparation method of the tool.

[0005] The present application provides a tool, which comprises a tool head and a polycrystalline diamond film. The tool head comprises a body, the body has a porous structure, the body comprises a peripheral wall, a first end portion and a second end portion, the first end portion and the second end portion are coaxially arranged and respectively located at opposite ends of the body, the peripheral wall extends from the first end portion toward the second end portion, the first end portion comprises a top surface and an inner concave arc-shaped surface, the arc-shaped surface extends from the top surface to the peripheral wall, and the arc-shaped surface is arranged around the top surface, a plurality of tool teeth are arranged on the arc-shaped surface, and each tool tooth extends from the top surface to the peripheral wall. The polycrystalline diamond film is located on the surface of the arc-shaped surface and each tool tooth, the polycrystalline diamond film comprises a transition layer close to the surface of the tool head and extending into the porous structure and an ultra-hard film layer located on the surface of the transition layer away from the tool head, the transition layer comprises nanoscale polycrystalline diamond crystals, and the ultra-hard film layer comprises microscale polycrystalline diamond crystals.

[0006] In some possible embodiments, the ends of the plurality of tool teeth located at the top surface enclose a first circle, the ends of the plurality of tool teeth located at the peripheral wall enclose a second circle, and the diameter of the first circle is smaller than the diameter of the second circle.

[0007] In some possible embodiments, the transition layer comprises an embedding portion and a buffer portion, the embedding portion extends into the porous structure, and the buffer portion is located on the surface of the embedding portion, the arc-shaped surface and the tool teeth.

[0008] In some possible embodiments, the thickness of the transition layer is 1.5-2.5 μm, and the average grain size of the nanoscale polycrystalline diamond crystals contained in the transition layer is 15-25 nm.

[0009] In some possible embodiments, the average grain size of the microscale polycrystalline diamond crystals contained in the superhard film layer is 6-10 μm, the film thickness of the superhard film layer is 5-10 μm, and the microhardness of the superhard film layer is 7000-9000 HV.

[0010] In some possible embodiments, the polycrystalline diamond film also extends to the peripheral wall.

[0011] In some possible embodiments, the porosity of the porous structure is 60-80%, and the average pore size of the porous structure is 500-800 μm; the elastic modulus of the tool bit is 1.5-4 GPa, the compressive strength of the tool bit is 50-85 MPa, and the material of the tool bit is titanium alloy.

[0012] The application also provides a preparation method of a tool bit, the tool bit comprising a tool bit head, the tool bit head comprising a body, the body having a porous structure, the body comprising a peripheral wall, a first end portion and a second end portion, the first end portion and the second end portion being located at opposite ends of the body respectively, the peripheral wall extending from the first end portion toward the second end portion, the first end portion comprising a top surface and an inner concave arc-shaped surface, the arc-shaped surface extending from the top surface to the peripheral wall and being arranged around the top surface, a plurality of tool teeth being arranged on the arc-shaped surface, each tool tooth extending from the top surface to the peripheral wall, the preparation method comprising the following steps:

[0013] A polycrystalline diamond film is grown on the surface of the arc-shaped surface and each tool tooth by using a gradient temperature growth method, wherein the proportion of the flow rate of methane is 2-5%, the microwave power is 3-8 kw, and the growth is sequentially carried out at three temperature conditions of 690-710 ℃, 740-760 ℃ and 790-810 ℃ for 0.5-1 h respectively, and finally the growth is continuously carried out at 790-810 ℃ for 2-10 h, the polycrystalline diamond film comprising a transition layer close to the surface of the tool bit and extending into the porous structure and a superhard film layer located on the surface of the transition layer away from the tool bit, the transition layer comprising nanoscale polycrystalline diamond crystals, and the superhard film layer comprising microscale polycrystalline diamond crystals.

[0014] In some possible embodiments, the transition layer comprises an embedding part and a buffer part, the embedding part extends into the porous structure, the buffer part is located between the embedding part and the surface of the tool head, the thickness of the transition layer is 1.5-2.5 μm, the average grain size of the nanoscale polycrystalline diamond crystals contained in the transition layer is 15-25 nm; the average grain size of the micrometer scale polycrystalline diamond crystals contained in the superhard film layer is 6-10 μm, the film thickness of the superhard film layer is 5-10 μm, and the microhardness of the superhard film layer is 7000-9000 HV.

[0015] In some possible embodiments, the forming method of the tool head comprises the following steps:

[0016] The titanium alloy powder is added into a 3D printing device, and the tool head is printed in a vacuum atmosphere, wherein the preheating temperature in the forming chamber of the 3D printing device is 450-550 ℃, the powder laying amount is 0.02-0.06 mm per layer, the electron scanning speed is 6000-9000 m / s, the electron beam output power is 2500-3500 W, the electron gun pressure range is 50000-70000 V, and the printing time is 6-12 h.

[0017] The tool head has higher hardness, wear resistance and shock resistance, so that the tool head has excellent cutting performance and can improve the surface quality of the brittle material being processed. The superhard film formed has micrometer scale polycrystalline diamond crystals, which can reduce the roughness of the tool surface, is conducive to reducing the cutting force, and improves the surface finish and machining precision of the workpiece. Moreover, the tool has a long service life and high machining efficiency, and the machining efficiency of the tool provided by the embodiment is 3 times that of a traditional electroplated grinding head. The tool head has a porous structure, and the polycrystalline diamond film extends into the porous structure to form a transition layer. On the one hand, the existence of the transition layer improves the adhesion of the polycrystalline diamond film on the surface of the tool head; on the other hand, the transition layer can provide a good growth interface for the superhard film layer, thereby ensuring the uniformity of the grain size and the thickness of the superhard film layer, and further improving the dimensional accuracy of the tool head and the quality of the cutting edge. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a perspective view of the tool provided by an embodiment of the present application.

[0019] Figure 2 is Figure 1 a side view of the tool shown in FIG. 1.

[0020] Figure 3 is Figure 1 a schematic view of a tool tooth section formed by the intersection of the tool tooth and its normal plane.

[0021] Figure 4 is Figure 3 enlarged view of A in FIG.

[0022] Figure 5 is Figure 1 a tool surface scanning electron microscope (SEM) photo of

[0023] Explanation of main element symbols

[0024] Tool 100

[0025] Tool bar 1

[0026] Tool head 2

[0027] Body 21

[0028] First end portion 211

[0029] Top surface 2111

[0030] Arc surface 2112

[0031] Second end portion 212

[0032] Peripheral wall 213

[0033] First circle 214

[0034] Second circle 215

[0035] Tool tooth 22

[0036] End portions b, c

[0037] Tool groove 23

[0038] Porous structure 24

[0039] Reference plane 10

[0040] Tool tooth cross section 20

[0041] Central axis a

[0042] Polycrystalline diamond film 3

[0043] Transition layer 31

[0044] Embedment portion 311

[0045] Buffer portion 312

[0046] Superhard film layer 32 DETAILED DESCRIPTION

[0047] In order to make the technical features, objectives and effects of the present application clearer, the specific embodiments of the present application are described in detail. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0048] The general forming tool is not suitable for milling forming machining of hard and brittle workpieces.

[0049] In order to make the formed tool suitable for machining hard and brittle materials, the inventors of the present application have optimized the material and structure of the tool bit through repeated experiments and research, and formed a polycrystalline diamond film on the surface of the tool bit, thereby preparing a tool suitable for machining hard and brittle materials.

[0050] Please refer to Figures 1 to 4 The superhard tool 100 suitable for machining hard and brittle materials provided by the embodiments of the present application is used for milling a workpiece (not shown in the figure), which can be a superhard material such as glass, graphite, ceramic, carbon fiber, glass fiber, hard alloy, liquid metal, etc., or other hard materials or ordinary metal materials. The tool 100 includes a tool shank 1 and a tool bit 2 arranged at one end of the tool shank 1, the tool bit 2 has a porous structure 24, the surface of the tool bit 2 is provided with a polycrystalline diamond film 3, the polycrystalline diamond film 3 includes a transition layer 31 close to the surface of the tool bit 2 and extending into the porous structure 24, and a superhard film layer 32 located on the surface of the transition layer 31 away from the tool bit 2, the transition layer 31 includes nanoscale polycrystalline diamond crystals, and the superhard film layer 32 includes micrometer-scale polycrystalline diamond crystals.

[0051] The tool head 2 is generally a cylindrical body, comprising a body 21 having the porous structure 24, the body 21 comprising a peripheral wall 213, a first end 211 and a second end 212. The first end 211 and the second end 212 are coaxially arranged and located at opposite ends of the body 21 respectively. The second end 212 faces the tool bar 1. The peripheral wall 213 extends from the second end 212 towards the first end 211, the first end 211 comprising a top surface 2111 and an inner concave arc surface 2112, the arc surface 2112 extending from the top surface 2111 to the peripheral wall 213, and the arc surface 2112 being arranged around the top surface 2111. A plurality of tool teeth 22 are arranged on the arc surface 2112, each of the tool teeth 22 extending from the top surface 2111 to the peripheral wall 213, i.e. the starting point or one end of each of the tool teeth 22 starts from or is adjacent to the top surface 2111, and the ending point or the other end ends at or is adjacent to the peripheral wall 213. The plurality of tool teeth 22 are arranged radially from the top surface 2111 to the peripheral wall 213, i.e. the ends b of the plurality of tool teeth 22 located at the top surface 2111 enclose a first circle 214, the ends c of the plurality of tool teeth 22 located at the peripheral wall 213 enclose a second circle 215, the diameter of the first circle 214 is smaller than the diameter of the second circle 215, and the polycrystalline diamond film 3 is located on the surface of the arc surface 2112 and the tool teeth 22.

[0052] The plurality of tool teeth 22 are arranged radially on the arc surface 2112 with respect to the central axis a of the tool head 2. The projection of each tool tooth 22 on a plane perpendicular to the central axis a is a curve. The shape and size of the tool tooth cross section 20 (see Figure 1 and Figure 3 ) formed by the intersection of any tool tooth 22 and a normal plane 10 at any position on the tool tooth 22 are the same, and the normal plane 10 is a plane perpendicular to the tangent of the tool tooth 22. Preferably, each tool tooth 22 is arranged in a spiral shape on the arc surface 2112. The tool teeth 22 can be left-handed, right-handed or a combination of left-handed and right-handed.

[0053] A tool groove 23 is formed between two adjacent teeth 22, and the tool groove 23 is used to discharge the cutting debris generated by the teeth 22 during the milling of the workpiece. The cutting debris generated by the teeth 22 during the milling of the workpiece enters the tool groove 23 and is discharged from the tool 100 under the action of the centripetal force generated by the rotation of the tool 100. Each tool groove 23 is formed between two adjacent teeth 22, and the plurality of tool grooves 23 have equal groove depths. In the embodiment, the "groove depth" refers to the height of the teeth 22 in the direction perpendicular to the arc surface 2112, i.e., the distance between the highest point of the teeth 22 and the bottom of the tool groove 23 in the direction perpendicular to the arc surface 2112. It can be understood that the bottom surface of the tool groove 23 can be curved or flat. In the embodiment, the bottom surface of the tool groove 23 is approximately flat. The groove depth can also be understood as the tooth height of the teeth 22.

[0054] In the embodiment, the tool head 2 is a porous titanium alloy tool head.

[0055] In some embodiments, the porosity of the porous structure 24 of the tool head 2 is 60-80%, and the average pore size is 500-800 μm. Further, the porosity of the porous structure 24 is (68.0±5)%, and the average pore size is (700±50) μm. The porosity and the average pore size of the porous structure 24 in the tool head 2 affect the density and toughness of the tool head 2. When the porosity of the porous structure 24 is too low (less than 60%) and the average pore size is too small (less than 500 μm), the density of the tool head 2 is large, the toughness is poor, and the chip capacity (i.e., the ability to accommodate cutting debris during cutting) is poor. When the porosity of the porous structure 24 is too high (more than 80%) and the average pore size is too large (more than 800 μm), the density of the tool head 2 is too small, the strength is too low, the cutting performance is poor, and the tool head 2 cannot be used for cutting hard and brittle materials. Therefore, in the embodiments of the present application, the porous structure 24 has a porosity and an average pore size within the above range, which can effectively reduce the weight of the tool head 2, improve the toughness and chip capacity of the tool head 2, and provide effective elastic buffering when cutting hard and brittle materials. This is more conducive to reducing the risk of collapse, damage, and other phenomena during the cutting of hard and brittle materials, thereby improving the surface quality of the cut material.

[0056] In some embodiments, the elastic modulus of the tool head 2 is 1.5-4 GPa, and the compressive strength is 50-85 MPa. Further, the elastic modulus of the tool head 2 is (2.5±0.2) GPa, and the compressive strength is (63.0±4.7) MPa. By controlling the material of the tool head 2, the porosity and the average pore size of the porous structure 24, the elastic modulus and the compressive strength of the tool head 2 can be maintained within a suitable range, thereby enabling the tool 100 to have a high specific strength, good shock resistance, and resistance to deformation.

[0057] The density of the titanium alloy is only 60% of the high-speed steel and 40% of the tungsten steel, the cutting head 2 made of the titanium alloy has high specific strength and light weight, and the porous structure 24 can further reduce the density of the cutting head 2, so that the cutting tool 100 is more suitable for high-speed cutting, and the surface quality of the hard and brittle material is better and the efficiency is higher when the hard and brittle material is cut at high speed; in addition, the elastic modulus of the cutting head 2 is about 1 / 2 of the high-speed steel cutting head and 1 / 5 of the tungsten steel cutting head, so that the toughness of the titanium alloy cutting head 2 with the porous structure 24 is better, the elastic buffer can be provided when the hard and brittle material is cut, and the risk of collapse, damage and other phenomena of the hard and brittle material during cutting can be reduced, and the surface quality of the cut material is improved.

[0058] Please refer to Figures 1 to 4 In the embodiment of the present application, the tooth 22 and the tooth groove 23 with the above structure are first formed, and then the polycrystalline diamond film 3 is grown on the surface of the arc surface 2112 (i.e. the bottom of the tooth groove 23) and the tooth 22 by the CVD forming method. The key to growing the polycrystalline diamond film 3 is to maintain the uniformity of the film thickness without damaging the structure and size of the original tooth 22 and the tooth groove 23.

[0059] In the embodiment of the present application, the superhard film layer 32 with micron-level long crystal diamond crystals is grown on the surface of the tooth 22, the average grain size of the micron-level long crystal diamond crystals is 6-10 μm, the thickness of the superhard film layer 32 is 5-10 μm, and the microhardness is 7000-9000 HV, which is beneficial to improve the hardness, wear resistance and shock resistance of the cutting head 2, so that the cutting tool 100 has excellent cutting performance. In addition, the average grain size of the micron-level long crystal diamond crystals is uniform, the thickness of the superhard film layer 32 is uniform, the bonding force between the superhard film layer 32 and the tooth 22 is strong, the size precision of the tooth 22 with the superhard film layer 32 is high, the structure and size of the original tooth 22 are not damaged, the surface roughness of the tooth 22 and the tooth groove 23 is reduced, the edge quality is improved, and the surface roughness of the cutting tool 100 is reduced, which is beneficial to reduce the cutting force and improve the surface finish and machining accuracy of the workpiece.

[0060] In order to further improve the bonding force between the superhard film layer 32 and the cutting head 2, a transition layer 31 is formed between the cutting head 2 and the superhard film layer 32 in the embodiment, wherein the transition layer 31 includes an embedded part 311 located in the porous structure 24 and a buffer part 312 located on the surface of the arc surface 2112 and the tooth 22. By forming the embedded part 311 of nanometer-level polycrystalline diamond in the porous structure 24, the bonding force between the superhard film layer 32 and the tooth 22 and the tooth groove 23 can be further improved. In addition, by forming the buffer part 312 of nanometer-level polycrystalline diamond crystals on the surface of the arc surface 2112 and the tooth 22, a good growth interface can be provided for the micron-level superhard film layer 32, and the size uniformity of the crystal grains of the superhard film layer 32 and the thickness uniformity of the superhard film layer 32 are improved.

[0061] In some embodiments, the total thickness of the transition layer 31 is 1.5-2.5 μm, typically but not limitedly 1.5 μm, 1.8 μm, 2 μm, 2.2 μm or 2.5 μm, preferably 2 μm. The average grain size of the transition layer 31 is 15-25 nm, typically but not limitedly 15 nm, 18 nm, 20 nm, 22 nm or 25 nm, preferably 20 nm. When the thickness of the transition layer 31 is too thick (greater than 2.5 μm), the thickness of the nanoscale polycrystalline diamond crystals in the polycrystalline diamond film 3 is thick, which reduces the overall hardness, wear resistance and cutting performance of the cutting tool 100, and the thickness of the transition layer 31 is too thick, resulting in the overall thickness of the polycrystalline diamond film being too thick, and the polycrystalline diamond film is prone to falling off during cutting. When the thickness of the transition layer 31 is too thin (less than 1.5 μm), the thickness of the embedded portion 311 of the transition layer 31 extending into the porous structure 24 is small, reducing the bonding force of the polycrystalline diamond film 3 and the cutting head 2, and when the thickness of the transition layer 31 is too thin, the thickness of the buffer portion 312 is small, and the buffer portion 312 cannot even be formed, which is not conducive to the growth of the superhard film layer 32. Therefore, in the present embodiment, the thickness of the transition layer 31 is within the above range, which can effectively increase the bonding force of the polycrystalline diamond film 3 and the cutting head 2, and can provide a good growth interface for the growth of the superhard film layer 32, thereby ensuring that the superhard film layer 32 grows uniformly on the surface of the transition layer 31, the grain size is uniform, and the thickness is uniform.

[0062] In some embodiments, the polycrystalline diamond film 3 also extends onto the peripheral wall 213 of the body 21, and can also extend onto the top surface 2111 of the body 21, which can increase the adhesion area of the polycrystalline diamond film 3 on the body 21, further improve the adhesion of the polycrystalline diamond film 3 on the body 21, and reduce the risk of delamination, warping and falling off of the polycrystalline diamond film 3 from the edges close to the peripheral wall 213 and the top surface 2111 during use of the cutting tool 100.

[0063] Please refer to Figure 1 and Figure 3 Since the superhard film layer 32 grows uniformly on the surface of the cutting teeth 22 and the arc-shaped surface 2112, the grain size is uniform, and the thickness is uniform, it is ensured that the structural size of each cutting tooth 22 with the polycrystalline diamond film 3 attached meets the requirements of a milling cutter. Specifically, in the present embodiment, the helix angle θ of each cutting tooth 22 with the polycrystalline diamond film 3 attached is in the range of 0°-90°, wherein the helix angle θ is the acute angle between the tangent of the cutting tooth 22 and the central axis a. In addition, the rake angle γ (see Figure 3 ) of each cutting tooth 22 with the polycrystalline diamond film 3 attached is the same at any position.

[0064] The groove depth L of the tool groove 23 with the polycrystalline diamond film 3 attached ranges from 0.05 mm to 0.5 mm, and the groove depth L of the tool groove 23 at any position is the same. In this way, the groove depth L can ensure that the tool head 2 has good chip removal capacity and high structural strength by meeting the above numerical range. However, when the groove depth L is less than 0.05 mm, the groove depth is too small, the chip removal capacity of the tool head 2 is reduced, and the tool head 2 is affected when milling the workpiece. When the groove depth L is greater than 0.5 mm, the groove depth is too large, the tooth height of each tool tooth 22 with the polycrystalline diamond film 3 attached is too large, the structural strength of the tool head 2 is reduced, and the service life of the tool head 2 is affected. In addition, the groove width W1 of each tool groove 23 after the polycrystalline diamond film 3 is attached gradually increases from the top surface 2111 towards the tool bar 1, wherein the groove width W1 is the arc distance between any two adjacent tool teeth 22 with the polycrystalline diamond film 3 attached on any circular surface formed by the intersection of the arc surface 2112 and the surface perpendicular to the center axis a, and each groove width W1 (arc distance) on any circular surface is equal.

[0065] The polycrystalline diamond film 3 is formed on the arc surface 2112 of the tool head 2 and the surface of the tool tooth 22, the polycrystalline diamond film 3 has strong bonding force with the tool head 2, the tool head 2 has higher hardness, wear resistance and shock resistance, thereby making the tool head 2 have excellent cutting performance and improving the surface quality of the brittle material being processed. The superhard film formed has micron-level polycrystalline diamond crystals, which can reduce the surface roughness of the tool 100, is beneficial to reducing the cutting force, and improves the workpiece surface finish and machining accuracy; moreover, the tool 100 has long service life and high machining efficiency, and the machining efficiency using the tool 100 is 3 times that of using a traditional electroplated grinding head. The tool head 2 has a porous structure 24, the polycrystalline diamond film 3 extends into the porous structure 24 to form a transition layer 31, the existence of the transition layer, on the one hand, improves the adhesion of the polycrystalline diamond film 3 on the surface of the tool head 2; on the other hand, the transition layer 31 can provide a good growth interface for the superhard film layer 32, thereby ensuring the uniformity of the grain size and the thickness of the superhard film layer 32, and further improving the size accuracy of the tool tooth 22 and the quality of the cutting edge.

[0066] It should be pointed out that the superhard film is the commonly accepted definition of ordinary skilled persons in the art, and it is generally believed in the industry that the superhard film refers to a solid thin film with a hardness greater than 40 GPa (approximately 4080 HV), excellent anti-friction and wear resistance, high thermal conductivity, low friction coefficient and thermal expansion coefficient.

[0067] The embodiment of the present application also provides a preparation method of the tool 100, the tool 100 comprising the tool head 2 as described above, the tool head 2 comprising a body 21 and a plurality of tool teeth 22, the tool head 2 having a porous structure 24, the preparation method comprising the following steps:

[0068] The polycrystalline diamond film 3 is deposited on the arc surface 2112 of the tool head 2 and the surface of each of the tool teeth 22 by using the gradient temperature growth method. The polycrystalline diamond is formed by using methane as the raw material, the flow rate of the methane is 2-5%, the microwave power is 3-8kw, and the growth is performed at the gradient temperatures of 690-710℃, 740-760℃ and 790-810℃ for 0.5-1h respectively, and then the growth is continued at 790-810℃ for 2-10h. The polycrystalline diamond film 3 includes a transition layer 31 extending into the porous structure 24 and a superhard film layer 32 on the surface of the transition layer 31. The transition layer 31 includes nanoscale polycrystalline diamond crystals, and the superhard film layer 32 includes microscale polycrystalline diamond crystals.

[0069] In some embodiments, the microwave power for depositing the polycrystalline diamond film 3 is typically but not limited to 3kw, 4kw, 5kw, 6kw, 7kw or 8kw, and preferably 5kw. The three temperatures in the gradient temperature are preferably 700±5℃, 750±5℃ and 800±5℃. The above gradient temperature growth conditions are advantageous for forming polycrystalline diamond crystals of both nanoscale and microscale sizes, and the thickness of the polycrystalline diamond film 3 is more uniform.

[0070] The structure of the tool head 2 is described above. In this embodiment, the polycrystalline diamond film 3 is located on the arc surface 2112 and the surface of the tool teeth 22.

[0071] It can be understood that, in order to improve the adhesion of the polycrystalline diamond film 3 on the tool head 2 and avoid the edge of the polycrystalline diamond film 3 from being warped or falling off when the tool head 2 mills a workpiece, the polycrystalline diamond film 3 can extend to the peripheral wall 213 and the top surface 2111 of the tool head 2.

[0072] By controlling the above crystal growth conditions, the surface of the tool head 2 can form polycrystalline diamond crystals of both nanoscale and microscale sizes. When the temperature is low, the crystal growth rate is slow and the size is small, so it is easy to form nanoscale crystals. When the microwave power is 3-8kw and the temperature is 690-710℃, small crystals are grown in the porous structure 24. By controlling the growth time of the small crystals, the porous structure 24 on the surface of the tool teeth 22 and the arc surface 2112 is filled with nanoscale crystals of small size (i.e. the embedded part 311 of the transition layer 31 as shown in FIG. 3). Figure 3 When the temperature is increased to 740-760℃ and the microwave power is maintained at 3-8kw, nanoscale crystals larger than those in the porous structure 24 are grown on the surface of the tool teeth 22 and the arc surface 2112 (i.e. the superhard film layer 32 as shown in FIG. 3). Figure 3The buffer part 312 of the transition layer 31 is continued to control the growth time of the fine grains, so as to form a transition layer 31 with a total thickness of 1.5-2.5 μm. The temperature is continued to be raised to 790-810 ℃, while the microwave power is maintained at 3-8 kw, the micron-sized grains are grown on the surface of the buffer part 312, and the growth time of the fine grains is controlled, so as to form a superhard film layer 32 with an average grain size of 6-10 μm and a thickness of 5-10 μm.

[0073] With reference to Figures 1 to 4 In the embodiment, the tool head 2 is formed by 3D printing using a 3D printing device. Specifically, the 3D printing method of the tool head 2 is as follows: titanium powder is added to the 3D printing device, and the tool head 2 with the foregoing structure is printed under vacuum conditions. The preheating temperature in the forming chamber of the 3D printing device is 450-550 ℃, the powder laying amount is 0.02-0.06 mm per layer, the electron scanning speed is 6000-9000 m / s, the electron beam output power is 2500-3500 W, the electron gun pressure range is 50000-70000 V, and the printing time is 6-12 h. In the embodiment, the material of the tool head 2 is titanium alloy, and therefore the above printing parameters are set according to the performance parameters (such as the melting point) of the titanium powder and the actual performance indicators required by the tool head 2. By setting the preheating temperature, the powder laying amount, the electron scanning speed, the electron beam output power, and the electron gun pressure range within the above ranges, the porosity of the porous structure 24 in the printed tool head 2 is 60-80%, the average pore size is 500-800 μm, the elastic modulus of the tool head 2 is 1.5-4 GPa, and the compressive strength is 50-85 MPa, so as to effectively reduce the weight of the tool head 2 and improve the specific strength, toughness, shock resistance, elastic buffering capacity, deformation resistance, and chip capacity of the tool head 2.

[0074] It can be understood that the structure of the 3D printing device is basically the same as that of the currently commonly used 3D printing device for forming tools, and therefore will not be described in detail here.

[0075] In some embodiments, the elastic modulus of the printed tool head 2 is 1.5-4 GPa, and the compressive strength is 50-85 MPa. Further, the elastic modulus of the tool head 2 is (2.5±0.2) GPa, and the compressive strength is (63.0±4.7) MP.

[0076] In some embodiments, the porosity of the porous structure 24 of the printed tool head 2 is 60-80%, and the average pore size is 500-800 μm. Further, the porosity of the porous structure 24 is (68.0±5)%, and the average pore size is (700±50) μm.

[0077] Before the polycrystalline diamond film 3 is grown on the surface of the body 21 of the tool head 2 using the CVD method, the method further comprises the step of:

[0078] The tool head 2 is ultrasonically cleaned with an acetone solution for 10-30 minutes.

[0079] The tool 100 of the embodiment has a simple preparation method. The temperature gradient forming method is used to form polycrystalline diamond crystals with two size types of nanometer and micrometer on the surface of the tool head 2 with the porous structure 24. The size uniformity of the grown crystal grains is high, the thickness of the polycrystalline diamond film 3 is uniform, which is conducive to improving the bonding force between the polycrystalline diamond film 3 and the tool head 2, improving the hardness and wear resistance of the tool head 2, and improving the surface quality of the tool teeth 22 and the edge quality, thereby improving the milling performance of the tool head 2. In addition, the titanium alloy tool head 2 with the porous structure is formed by 3D printing, which can improve the size precision and surface quality of the tool head 2.

[0080] The application will be further described below through specific embodiments.

[0081] Embodiment 1

[0082] First step, 3D printing of the porous titanium alloy tool head:

[0083] Ti alloy powder is used as raw material, the powder is added to the 3D printing equipment, and the tool head is printed in a vacuum atmosphere. The preheating temperature is 450-550°C, the powder laying amount is 0.02-0.06mm per layer, the electron scanning speed is 6000-9000m / s, the electron beam output power is 2500-3500w, the electron gun pressure range is 50000-70000v, and the printing time is 6-12h.

[0084] The porosity of the porous structure of the tool head is 68.0%, the average pore size is 700μm, the elastic modulus of the tool head is 4GPa, and the compressive strength is 85MPa.

[0085] It can be understood that the tool handle can also be printed at the same time during the printing process.

[0086] Second step, surface processing:

[0087] The 3D printed titanium alloy tool head is placed in a sandblasting machine for sandblasting treatment to remove the excess powder on the surface. An optical microscope is used to observe that the excess powder is removed clean. Then the surface of the tool head is finished until the surface of the tool teeth is smooth and flat, and the roughness Ra is less than 0.8μm.

[0088] Third step, side shielding:

[0089] The aluminum foil paper of about 60mm*60mm is cut and wrapped on the top surface and side wall of the body, only exposing the teeth and arc surface. Then the cutter head is ultrasonically cleaned in acetone solution for 10-30min.

[0090] When the handle is printed at the same time, the handle also needs to be wrapped with aluminum foil paper.

[0091] Fourth step, temperature gradient method for growing polycrystalline diamond film;

[0092] The side shielded cutter head is placed in the CVD device reaction cavity, and the side with teeth is upward. The reaction gas is introduced, the methane flow ratio is 5%, the microwave power is 5kw, and the gradient temperature is 700℃, 750℃ and 800℃ respectively for 0.5h, and finally continues to grow at 800℃ for 8h to obtain a semi-finished product.

[0093] Fifth step, tooth surface treatment:

[0094] The semi-finished product obtained in the fourth step is taken out, the side shielding layer is removed, and the teeth and grooves attached with polycrystalline diamond film are trimmed and cut by laser (the laser cutting process is determined according to the actual use), to obtain the final cutter.

[0095] The average grain size of micron-level polycrystalline diamond crystals in the superhard film layer of the finally obtained polycrystalline diamond film is 6μm, the microhardness is 8500HV, the thickness of the superhard film layer is 10μm; the thickness of the transition layer is 2μm, and the average grain size of nanometer-level polycrystalline diamond crystals in the transition layer is 20nm.

[0096] Example 2

[0097] The steps of the first to third steps are the same as those of example 1, which will not be described in detail here. The porosity of the porous structure of the cutter head obtained is 69.0%, the average pore size is 720μm, the elastic modulus of the cutter head is 3.6GPa, and the compressive strength is 80MPa.

[0098] Fourth step, temperature gradient method for growing polycrystalline diamond film;

[0099] The side shielded cutter head is placed in the CVD device reaction cavity, and the side with teeth is upward. The reaction gas is introduced, the methane flow ratio is 5%, the microwave power is 5kw, and the gradient temperature is 700℃, 750℃ and 800℃ respectively for 0.5h, and finally continues to grow at 800℃ for 8h to obtain a semi-finished product.

[0100] Fifth step, tooth surface treatment:

[0101] The semi-finished product obtained in the fourth step is taken out, the shielding layer on the side surface is removed, and laser cutting treatment is performed on the blade teeth and blade grooves to which the polycrystalline diamond film is attached (the laser cutting process is determined according to actual use conditions), thereby obtaining the final cutter.

[0102] In the finally obtained polycrystalline diamond film, the average grain size of the micron-level polycrystalline diamond crystals in the superhard film layer is 6.3 μm, the microhardness is 8450 HV, the thickness of the superhard film layer is 10.5 μm; the thickness of the transition layer is 2.1 μm, and the average grain size of the nanometer-level polycrystalline diamond crystals in the transition layer is 20.5 nm.

[0103] Example 3

[0104] The steps of the first to third steps are the same as those of Example 1, which will not be described in detail here. The porosity of the porous structure of the cutter head obtained is 67.5%, the average pore size is 705 μm, the elastic modulus of the cutter head is 3.3 GPa, and the compressive strength is 81 MPa.

[0105] In the fourth step, a polycrystalline diamond film is grown by a temperature gradient method.

[0106] The cutter head with the side surface shielded is placed in a reaction cavity of a CVD device, and the side with the blade teeth faces upward. Reaction gas is introduced, the flow rate of methane accounts for 5%, the microwave power is 5 kw, and the gradient temperature is 700℃, 750℃, and 800℃ respectively for 0.5 h each time. Finally, growth is continued at 800℃ for 8 h, thereby obtaining a semi-finished product.

[0107] In the fifth step, the surface of the blade teeth is treated.

[0108] The semi-finished product obtained in the fourth step is taken out, the shielding layer on the side surface is removed, and laser cutting treatment is performed on the blade teeth and blade grooves to which the polycrystalline diamond film is attached (the laser cutting process is determined according to actual use conditions), thereby obtaining the final cutter.

[0109] In the finally obtained polycrystalline diamond film, the average grain size of the micron-level polycrystalline diamond crystals in the superhard film layer is 5.8 μm, the microhardness is 8600 HV, the thickness of the superhard film layer is 9.8 μm; the thickness of the transition layer is 1.9 μm, and the average grain size of the nanometer-level polycrystalline diamond crystals in the transition layer is 19.5 nm.

[0110] Comparative Example 1

[0111] The steps of the first to third steps are the same as those of Example 1, which will not be described in detail here. The porosity of the porous structure of the cutter head obtained is 67.8%, the average pore size is 680 μm, the elastic modulus of the cutter head is 3 GPa, and the compressive strength is 70 MPa.

[0112] In the fourth step, a polycrystalline diamond film is grown by a temperature gradient method.

[0113] Put the side shielded cutter head into the CVD device reaction cavity, and set the side with the cutter teeth upward. Introduce the reaction gas, and the methane flow accounts for 4%. Microwave power is 5kw. Grow for 0.5h under the gradient temperature of 650℃, 700℃ and 750℃ respectively. Finally, continue to grow for 8h at 750℃ to obtain the semi-finished product.

[0114] Step 5, cutter tooth surface treatment:

[0115] Take out the semi-finished product obtained in the fourth step, remove the side shielding layer, and then use laser to trim and cut the cutter teeth and cutter grooves attached with the polycrystalline diamond film (the laser cutting process is determined according to the actual use situation). Finally, the cutter is obtained.

[0116] In the finally obtained polycrystalline diamond film, the average grain size of the micron-level polycrystalline diamond crystal in the superhard film layer is 4μm, the microhardness is 7200HV, the thickness of the superhard film layer is 6.5μm; the thickness of the transition layer is 1.5μm, and the average grain size of the nanometer-level polycrystalline diamond crystal in the transition layer is 16nm.

[0117] Comparative Example 2

[0118] The steps of the first step to the third step are the same as those of Example 1, which will not be described in detail here. The porosity of the porous structure of the cutter head obtained is 67%, the average pore size is 730μm, the elastic modulus of the cutter head is 3.1GPa, and the compressive strength is 72MPa.

[0119] Step 4, temperature gradient method for growing polycrystalline diamond film;

[0120] Put the side shielded cutter head into the CVD device reaction cavity, and set the side with the cutter teeth upward. Introduce the reaction gas, and the methane flow accounts for 6%. Microwave power is 5kw. Grow for 0.5h under the gradient temperature of 750℃, 800℃ and 850℃ respectively. Finally, continue to grow for 8h at 850℃ to obtain the semi-finished product.

[0121] Step 5, cutter tooth surface treatment:

[0122] Take out the semi-finished product obtained in the fourth step, remove the side shielding layer, and then use laser to trim and cut the cutter teeth and cutter grooves attached with the polycrystalline diamond film (the laser cutting process is determined according to the actual use situation). Finally, the cutter is obtained.

[0123] In the finally obtained polycrystalline diamond film, the average grain size of the micron-level polycrystalline diamond crystal in the superhard film layer is 9μm, the microhardness is 6500HV, the thickness of the superhard film layer is 14μm; the thickness of the transition layer is 3μm, and the average grain size of the nanometer-level polycrystalline diamond crystal in the transition layer is 30nm.

[0124] As can be seen from Examples 1 to 3, the three types of cutting tools prepared by the process methods provided in this application, under the condition of using basically the same 3D forming process parameters, produce cutting heads with porous structures with stable performance parameters within a certain error range. This indicates that the cutting head preparation process provided in this application has strong repeatability. Furthermore, the performance parameters of the transition layer and the superhard film layer in the polycrystalline diamond film formed on the surface of the cutting head in Examples 1 to 3 are moderate, resulting in strong bonding between the polycrystalline diamond film and the cutting head. This leads to higher hardness, wear resistance, and vibration resistance in the cutting tool, thereby giving it excellent cutting performance. Comparative Examples 1 and 2 use basically the same 3D forming process parameters as Examples 1 to 3, and the performance parameters of the cutting heads with porous structures formed are basically the same as those in Examples 1 to 3. The difference lies in the fact that the crystal growth conditions of the polycrystalline diamond film on the surface of the cutting heads in Comparative Examples 1 and 2 are not within the range given in this application. In Comparative Example 1, the methane flow rate was low, and the temperatures in all three temperature ranges during the growth of the polycrystalline diamond film using the temperature gradient method were low. This resulted in slow grain growth, low grain growth efficiency, and a small average crystal size of the micron-sized polycrystalline diamond crystals in the formed superhard film, leading to low microhardness of the superhard film. Consequently, the tool tip exhibited poor hardness, wear resistance, vibration resistance, and cutting performance. In Comparative Example 2, the methane flow rate was high, and the temperatures in all three temperature ranges during the growth of the polycrystalline diamond film using the temperature gradient method were high. This made it difficult to control the grain growth rate, resulting in a larger and less uniform average grain size. Furthermore, the microhardness of the superhard film was low, further contributing to poor hardness, wear resistance, vibration resistance, and cutting performance of the tool tip. Therefore, the comparison shows that the performance parameters of the tools in Comparative Examples 1 and 2 are inferior to those of the tools in Examples 1 to 3. The tools prepared in Examples 1 to 3 exhibit better hardness, wear resistance, vibration resistance, and cutting performance.

[0125] Additionally, such as Figure 5 The image shown is an SEM image of the cutting head with a polycrystalline diamond film attached, obtained in Example 1. As can be seen from the image, the polycrystalline diamond film formed on the surface of the cutting head has a uniform grain size, which is beneficial to improving the surface quality and cutting ability of the cutting tool.

Claims

1. A method for manufacturing a cutting tool, the cutting tool comprising a cutting head, characterized in that, The cutter head comprises a body having a porous structure, the body comprising a peripheral wall, a first end and a second end, the first end and the second end being located at opposite ends of the body respectively, the peripheral wall extending from the first end towards the second end, the first end comprising a top surface and an inwardly recessed arc surface, the arc surface extending from the top surface to the peripheral wall and being arranged around the top surface, a plurality of cutter teeth being arranged on the arc surface, each of the cutter teeth extending from the top surface to the peripheral wall, the preparation method comprising the following steps: A polycrystalline diamond film is grown on the surface of the arc surface and each of the cutter teeth by using a gradient temperature growth method, wherein the methane flow rate accounts for 2-5%, the microwave power is 3-8 kw, and the polycrystalline diamond film is grown at three temperature conditions of 690-710 ℃, 740-760 ℃ and 790-810 ℃ for 0.5-1 h respectively, and finally grown at 790-810 ℃ for 2-10 h, the polycrystalline diamond film comprising a transition layer close to the surface of the cutter head and extending into the porous structure and a superhard film layer located on the surface of the transition layer away from the cutter head, the transition layer comprising nanoscale polycrystalline diamond crystals, and the superhard film layer comprising microscale polycrystalline diamond crystals, The thickness of the transition layer is 1.5-2.5 μm, and the average grain size of the nanoscale polycrystalline diamond crystals contained in the transition layer is 15-25 nm; The average grain size of the microscale polycrystalline diamond crystals contained in the superhard film layer is 6-10 μm, the film thickness of the superhard film layer is 5-10 μm, and the microhardness of the superhard film layer is 7000-9000 HV.

2. The method of producing a cutting tool according to claim 1, wherein The transition layer comprises an embedding part and a buffer part, the embedding part extending into the porous structure, and the buffer part being located between the embedding part and the surface of the cutter head.

3. The method of producing a cutting tool according to claim 1, wherein The cutter head is formed by using a 3D printing method: Titanium alloy powder is added to a 3D printing device to print the cutter head in a vacuum atmosphere, wherein the preheating temperature in the forming chamber of the 3D printing device is 450-550 ℃, the powder laying amount is 0.02-0.06 mm per layer, the electron scanning speed is 6000-9000 m / s, the electron beam output power is 2500-3500 W, the electron gun pressure range is 50000-70000 V, and the printing time is 6-12 h.

4. A tool produced by the production method according to claim 1, characterized in that, The cutter comprises: a cutter head comprising a body having a porous structure, the body comprising a peripheral wall, a first end and a second end, the first end and the second end being coaxially arranged and located at opposite ends of the body respectively, the peripheral wall extending from the first end towards the second end, the first end comprising a top surface and an inwardly recessed arc surface, the arc surface extending from the top surface to the peripheral wall and being arranged around the top surface, a plurality of cutter teeth being arranged on the arc surface, each of the cutter teeth extending from the top surface to the peripheral wall; and A polycrystalline diamond film is located on the surface of the arc-shaped surface and each of the teeth, the polycrystalline diamond film comprises a transition layer close to the surface of the tool head and extending into the porous structure and a superhard film layer located on the surface of the transition layer away from the tool head, the transition layer comprises nanoscale polycrystalline diamond crystals, and the superhard film layer comprises microscale polycrystalline diamond crystals, The thickness of the transition layer is 1.5-2.5 μm, and the average grain size of the nanoscale polycrystalline diamond crystals contained in the transition layer is 15-25 nm, The average grain size of the microscale polycrystalline diamond crystals contained in the superhard film layer is 6-10 μm, the film thickness of the superhard film layer is 5-10 μm, and the microhardness of the superhard film layer is 7000-9000 HV.

5. The tool of claim 4 wherein, The ends of the plurality of teeth located at the top surface enclose a first circle, and the ends of the plurality of teeth located at the peripheral wall enclose a second circle, the diameter of the first circle being smaller than the diameter of the second circle.

6. The knife of claim 4, wherein, The transition layer comprises an embedding portion and a buffer portion, the embedding portion extending into the porous structure, and the buffer portion being located on the surface of the embedding portion, the arc-shaped surface and the teeth.

7. The knife of claim 4, wherein, The polycrystalline diamond film also extends to the peripheral wall.

8. The tool according to claim 4, characterized in that The porosity of the porous structure is 60-80 %, and the average pore size of the porous structure is 500-800 μm; The elastic modulus of the tool head is 1.5-4 GPa, and the compressive strength of the tool head is 50-85 Mpa; The material of the tool head is titanium alloy.

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