Milling tool

Abstract

The present disclosure provides a milling tool for milling a material, the milling tool comprising: a tool shank having an axis of rotation; and a tool head at one end thereof; wherein the tool head comprises a single layer body comprising a plurality of slots extending circumferentially around the tool head, and wherein the slots comprise a superhard material; wherein the superhard material comprises a chemical vapor deposition diamond coated on a substrate.

Description

Technical Field

[0001] The present disclosure relates to a milling tool for milling materials (e.g., brittle materials). In particular, the present disclosure relates to a tool for milling glass. More particularly, the present disclosure relates to a micro-end milling tool, the micro-end milling tool comprising a superhard material, such as chemical vapor deposited diamond, polycrystalline cubic boron nitride, or polycrystalline chemical vapor deposited diamond coated on a substrate. Background Art

[0002] Milling is a cutting process that removes material from the surface of a workpiece by rotating a tool with multiple cutting surfaces. Such tools, also called cutters, come in various shapes and sizes depending on the design of the workpiece. The tool has an elongated shank or handle adjacent to a tool head, which has shaped cutting surfaces. The shank is mounted in a milling tool holder, which is then mounted in the machine's tool spindle and rotated.

[0003] End mills are the most common form of milling tool, and they come in a wide variety of heights, diameters, and types. End mills are used to machine the faces and sides of a workpiece. During a typical milling operation, the tool moves perpendicular to its axis of rotation, allowing the tool to remove material from the workpiece at the periphery of the tool. End mills are used for grooving, profiling, contouring, counterboring, and reaming. The spiral cutting edges on the sides of an end mill are called "flutes," and they provide a clear path for chips to escape as the end mill rotates in the workpiece.

[0004] End mills are typically made from high-speed steel (i.e., a cobalt-steel alloy) or from tungsten carbide in a cobalt lattice. Carbides are significantly harder, more rigid, and more wear-resistant than high-speed steel. However, carbides are brittle and tend to chip rather than wear. The choice of material depends on the material to be cut and the maximum spindle speed of the machine.

[0005] The use of coatings increases the surface hardness of the tool. This allows for longer tool life and greater cutting speeds. Standard coatings include titanium nitride (TiN), titanium carbonitride (TiCN) and aluminum titanium nitride (AlTiN).

[0006] For workpieces made of harder materials, diamond electroplated tool heads are often used. In electroplated tools, hundreds of individual diamond grits are embedded in a binder on the surface of the tool head to provide a large amount of cutting surface and cutting edges. However, a problem with electroplated milling tools is that the diamond grits tend to pull out of the binder, making the workpiece susceptible to undesirable scratching by the bad grits. Another problem is that diamond electroplated tools have a limited tool life, requiring regular tool replacement and increasing the production cost of each tool required.

[0007] The utility model aims to solve the problems of abrasive particle extraction and tool life.

[0008] In a micro end mill, the outer diameter of the tool head is usually no more than 15 mm and is typically in the range of 6 mm to 10 mm. Micro end mills are used for milling operations during the construction of, for example, mobile phone handset housings. The handset housings are typically made of aluminum, polycarbonate or ceramic. One of the prior art is a diamond plated micro end mill.

[0009] A further object of the present invention is to provide a micro end milling tool suitable for milling mobile phone handset housings made of ceramics, such as glass and the like. Utility Model Content

[0010] According to a first aspect, the present disclosure provides a milling tool for milling material, the milling tool comprising: a tool shank having a rotation axis; and a tool head at one end of the tool shank; wherein the tool head comprises a layer body, the layer body comprises a plurality of grooves extending circumferentially around the tool head, and wherein the grooves comprise a superhard material.

[0011] As an option, the superhard material comprises chemical vapor deposited diamond and / or polycrystalline cubic boron nitride.

[0012] As an option, the superhard material comprises polycrystalline chemical vapor deposited diamond coated on a substrate.

[0013] As an option, the substrate is a ceramic substrate.

[0014] As an option, the ceramic substrate is any one of cemented carbide, silicon nitride or silicon carbide.

[0015] As an option, the cemented carbide is tungsten carbide.

[0016] As an option, the superhard material comprises polycrystalline chemical vapor deposited diamond coated on a cemented carbide substrate.

[0017] The material to be milled may optionally include any of glass, ceramic, polymer, composite material, metallic material and metal-ceramic composite material.

[0018] As an option, the tool head comprises a single layer body.

[0019] The tool head is optionally cylindrical and non-tubular.

[0020] Optionally, the layer body is configured for an operation selected from any one of rough machining, semi-finishing and milling.

[0021] The overall height of the tool head optionally does not exceed 12 mm.

[0022] The overall height of the tool head is optionally not less than 0.5 mm.

[0023] The milling tool may optionally be a micro end milling tool, and the outer diameter of the micro end milling tool is selected from any one of not more than 15 mm, not more than 10 mm, and not less than 6 mm.

[0024] The milling tool may optionally be a micro end milling tool having an outer diameter of no more than 15 mm or no more than 10 mm.

[0025] As an option, the tool shank comprises a cemented carbide, such as cemented tungsten carbide.

[0026] As an option, the tool shank comprises silicon carbide or silicon nitride.

[0027] The tool handle may optionally further include a conduit for delivering compressed air to the tool head to expel spent milling media.

[0028] As an option, the number of grooves is in the range of 1 to 200, preferably 16 to 200.

[0029] According to a second aspect, there is provided a method of manufacturing a milling tool head, the method comprising the following steps:

[0030] a. Providing a disc-shaped blank comprising a superhard material;

[0031] b. machining at least one precursor tool head from said disc;

[0032] c. Using a laser to form a layer body including a plurality of grooves in the precursor tool head, wherein the layer body includes a plurality of grooves extending circumferentially around the tool head.

[0033] As an option, the superhard material comprises chemical vapor deposited diamond and / or polycrystalline cubic boron nitride.

[0034] According to a third aspect, there is provided a method of manufacturing a milling tool head, the method comprising the following steps:

[0035] a. Provide disc-shaped blanks;

[0036] b. machining at least one precursor tool head from said disc;

[0037] c. forming a layer comprising a plurality of grooves in the precursor tool head using a laser, wherein the layer comprises a plurality of grooves extending circumferentially around the tool head; and

[0038] d. Depositing polycrystalline diamond on the plurality of grooves using chemical vapor deposition.

[0039] As an option, the chemical vapor deposition of polycrystalline diamond comprises hot-filament chemical vapor deposition.

[0040] According to a fourth aspect, there is provided a method for manufacturing a milling tool, the method comprising the following steps:

[0041] a. Provide disc-shaped blanks;

[0042] b. machining at least one precursor tool head from said disc;

[0043] c. depositing polycrystalline diamond on at least a portion of the precursor tool head using chemical vapor deposition; and

[0044] d. Using a laser to form a layer body comprising a plurality of grooves in the precursor tool head, wherein the layer body comprises a plurality of grooves extending circumferentially around the tool head, and the plurality of grooves comprises polycrystalline diamond.

[0045] As an option, the chemical vapor deposition of polycrystalline diamond comprises hot-filament chemical vapor deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:

[0047] Figure 1 is a front view of a tool according to the utility model, the tool having a first embodiment of a tool head;

[0048] Figure 2 yes Figure 1 An enlarged view of the X portion;

[0049] Figure 3 is a front view of a second embodiment of a tool head;

[0050] Figure 4 yes Figure 3 Annotated version of the tool header;

[0051] Figure 5 yes Figure 3 Another annotated version of the toolheader;

[0052] Figure 6 is a schematic diagram indicating a lateral cross-section of a slot in a tool head; and

[0053] Figure 7 is a schematic diagram indicating the cutting action of the groove during use.

[0054] In the embodiments, like parts are denoted by the same reference numerals, and further description is omitted for the sake of brevity. DETAILED DESCRIPTION

[0055] The following description relates to a tool head comprising a superhard material. In the examples, polycrystalline chemical vapor deposited diamond coated on a cemented carbide substrate is involved, but this is by way of example only. Other substrates may also be used, such as silicon carbide or silicon nitride. For milling ferrous materials, polycrystalline cubic boron nitride is preferred.

[0056] Furthermore, the following description relates to milling glass by way of example, but it should be understood that the same tool configuration can be used to mill other types of materials. A non-limiting list of materials that can be milled includes glass, ceramics, polymers, composites, metallic materials, and metal-ceramic composites.

[0057] First reference Figure 1 and Figure 2 , a milling tool is generally indicated at 10. The tool comprises a tool shank 12 having a longitudinal axis of rotation 14, and further comprises a tool head 16 at one end of the shank 12. The tool head 16 comprises a layer 18 (i.e., a platform or plane) comprising a plurality of grooves 20 extending circumferentially around the tool head 16. In the layer 18, all the grooves are in a band, i.e., the grooves are axially aligned with each other.

[0058] In this example, the tool head 16 comprises polycrystalline chemical vapor deposited diamond coated on a cemented carbide substrate. However, in other embodiments, the substrate may be silicon nitride or silicon carbide, for example.

[0059] Figure 2 A first embodiment of a tool head 16 is shown. The tool head 16 includes a layer body 18. The layer body 18 includes a plurality of grooves 20. The grooves 20 include a superhard material, in this example polycrystalline chemical vapor deposited diamond. The grooves 20 are disposed in an outer surface of the tool head. The grooves 20 extend around the entire circumference of the tool head 16. The grooves 20 are created in the outer surface using a laser that initially ablates unwanted material, thereby creating recesses between the precursor grooves 20, and then shapes the precursor grooves into a final groove 20 configuration according to a desired profile. More details about the grooves 20 will be provided later.

[0060] The notch element 22 is configured to cut a correspondingly shaped notch in a workpiece, such as a microphone aperture in a mobile phone handset housing. By way of example only, the notch element 22 may have a diameter of at most 1 mm and a height of at most 1 mm. The notch element 22 is entirely optional and may be omitted.

[0061] exist Figure 3 In FIG. 2 , an exemplary tool head 24 is shown without the notch element 22. In this example, only a single layer 18 is provided.

[0062] The layer body 18 may be configured for a finishing operation. However, the layer body may also be configured for a roughing operation, or alternatively, the layer body may be configured for a semi-finishing operation.

[0063] The tool shank 12 may comprise a metal carbide such as tungsten carbide, although other suitable materials are contemplated, such as silicon carbide and silicon nitride. Optionally, the tool shank 12 includes a conduit (not shown) for delivering compressed air to the tool head to expel spent milling media from the slot.

[0064] The tool head 16 may be cylindrical and non-tubular.

[0065] refer to Figure 4 , if the carbide backing layer 34 is included, the total height of the tool head 16 is the sum of the height 38 of the layer body 18 and the height 40 of the carbide portion 34 (otherwise, the total height is only the height 38 of the layer body 18). Optionally, the height 36 of the tool head 16 is 0.5 mm to 12 mm. Optionally, the height 36 of the tool head 16 is 1 mm to 10 mm. Optionally, the height 36 of the tool head 16 is 6 mm. The height 38 of the layer body 18 can be in the range of 0.5 mm to 6 mm, such as 2.5 mm. It is contemplated that the height of the tool head can be nanometer-scale (i.e., <100 nm), such as a total height of 50 nm to 95 nm or less. Optionally, the height 36 of the tool head 16 does not exceed 12 mm.

[0066] The outer diameter of the tool 10 is indicated at 42 and is the largest, outermost diameter of the layer body 18 and the shank 12 .

[0067] The outer diameter of the milling tool may be in the range of 1 mm to 15 mm, for example 2 mm to 15 mm, for example 3 mm to 15 mm, for example 4 mm to 15 mm, for example 4 mm to 10 mm, for example 6 mm to 8 mm. The outer diameter of the milling tool may be at least 1 mm, 2 mm, 3 mm, 4 mm, 5 mm or 6 mm. The outer diameter of the milling tool may be at most 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm or 15 mm.

[0068] Preferably, the tool 10, 24 is a micro end milling tool having an outer diameter of no more than 15 mm. Optionally, the outer diameter 42 of the tool is 10 mm. In one example of a micro end milling tool, the total height of the tool including the tool shank 12 and the tool head 16 may be around 200 mm.

[0069] The height 38 of the layer 18 is measured axially, the same as the previous height measurements.

[0070] refer to Figure 5 , Figure 6 and Figure 7, each groove 20 has a triangular lateral cross-section. Various groove parameters affect certain factors. The helix angle α and the groove depth d affect the amount of chip jams generated between grooves during milling, and therefore affect the cleaning of the tool head 16. The helix angle α also affects tool stability. The groove angle β, the rake (cutting) angle θ, and the number of grooves N have a direct impact on surface finish, subsurface damage, tool performance (cutting forces), and tool life. Figure 7 It is schematically indicated how each flute may cut the workpiece 46 during use as the tool is advanced laterally in the direction of the arrows.

[0071] The number of grooves on the milling tool may be in the range of 1 to 200, such as 16 to 200. The number of grooves on the milling tool may be in the range of 1 to 200, such as 2 to 200, such as 3 to 200, such as 4 to 200, such as 5 to 200, such as 6 to 200, such as 7 to 200, such as 8 to 200, such as 9 to 200, such as 10 to 200, such as 11 to 200, such as 12 to 200, such as 13 to 200, such as 14 to 200, such as 15 to 200, such as 16 to 200. The number of grooves may be at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16. The number of slots may be at most 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200.

[0072] Depending on whether the purpose of the milling operation is roughing, semi-finishing or finishing in the case of milling glass or other similar brittle materials, the above parameters (helix angle α, groove angle β, front (cutting) angle θ, number of grooves N and groove depth d) in the layer body are optimized. Roughing milling operations are generally intended to prepare the surface of the workpiece before the finishing operation. The purpose is to make the size reach a "rough" size of the final size. How this looks may not be important, because the main purpose is to quickly remove a relatively large amount of material. Roughing will likely require a larger groove angle β than other operations in order to provide a stronger groove body to cope with higher forces. This will reduce the number of grooves that can be fitted into a limited space, and therefore reduce the number of grooves in the layer body. Semi-finishing milling operations are typically the next stage after roughing. The purpose is to obtain a size closer to the final size. The finishing milling operation is the final stage of machining a workpiece. The minimum amount of workpiece material is removed, the workpiece is machined to a certain size, the final size is obtained, and sometimes the surface is further refined.

[0073] An exemplary method of manufacturing one of the tool heads is as follows: a typical round blank shaped like a disk is provided, the round blank comprising a superhard material, such as PCBN. At least one precursor tool head is machined from the disk. The number of available precursor tool heads depends on the diameter of the blank, the available area without defects, and the outer diameter of the tool. The blank can be backed with a carbide backing layer, or alternatively unbacked, or "freestanding". The depth of the blank determines the depth of the tool head 16. A laser is then used to form a plurality of grooves in the precursor tool head. The grooves are arranged in a layer body. The tool head thus formed includes a layer body, wherein the layer body includes a plurality of grooves extending circumferentially around the tool head.

[0074] An alternative method of manufacturing one of the tool heads is as follows: a carbide disk-shaped blank is provided and a precursor tool head is machined from the disk. A layer comprising a plurality of grooves extending circumferentially around the tool head is formed in the precursor tool head using a laser. Finally, polycrystalline diamond is deposited on the plurality of grooves using chemical vapor deposition. Typically, hot-filament CVD is used, but other forms of CVD, such as microwave plasma CVD, may also be used. A final finishing operation may be required on the deposited diamond layer on the grooves.

[0075] Another alternative method of manufacturing the tool head is as follows: a carbide disc-shaped blank is provided and a precursor tool head is machined from the disc. Polycrystalline diamond is deposited on the plurality of grooves using chemical vapor deposition. Typically, hot-filament CVD is used, but other forms of CVD, such as microwave plasma CVD, may also be used. A layer comprising a plurality of grooves extending circumferentially around the tool head is formed in the polycrystalline diamond deposited on the precursor tool head using a laser. A final finishing operation of the grooves may be required.

[0076] In summary, the inventors have designed a milling tool that maximizes tool life and improves cost / benefit performance. This is achieved by using superhard materials such as CVD diamond or PCBN.

[0077] While the invention has been particularly shown and described with reference to the embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A milling tool for milling a material, the milling tool comprising: a tool shank having an axis of rotation; as well as a tool head at one end thereof; wherein the tool head comprises a single layer body, the single layer body comprising a plurality of grooves extending circumferentially around the tool head, and wherein the groove comprises a superhard material; Wherein, the superhard material includes chemical vapor deposited diamond coated on a substrate.

2. The milling tool according to claim 1, wherein: The substrate is a ceramic substrate.

3. The milling tool according to claim 2, wherein: The ceramic substrate is any one of cemented carbide, silicon nitride or silicon carbide.

4. The milling tool according to claim 3, wherein: The cemented carbide is tungsten carbide.

5. A milling tool according to any one of the preceding claims, wherein: The material to be milled includes any of glass, ceramics, polymers, composite materials, metallic materials, and metal-ceramic composites.

6. The milling tool according to claim 1, wherein: The tool head comprises a single layer body.

7. The milling tool according to claim 1, wherein: The tool head is cylindrical and non-tubular.

8. The milling tool according to claim 1, wherein: The layer body is configured for an operation selected from any one of rough machining, semi-finishing and milling.

9. The milling tool according to claim 1, wherein: The total height of the tool head does not exceed 12 mm.

10. The milling tool according to claim 1, wherein: The total height of the tool head is not less than 0.5 mm.

11. The milling tool according to claim 1, characterized in that: The milling tool is a micro end milling tool, and the outer diameter of the micro end milling tool is selected from any one of not more than 15 mm, not more than 10 mm, and not less than 6 mm.

12. The milling tool according to claim 1, wherein: The tool shank comprises cemented carbide.

13. The milling tool according to claim 12, wherein: The tool shank comprises cemented tungsten carbide.

14. The milling tool according to claim 1, wherein: The tool handle further includes a conduit for delivering compressed air to the tool head to expel spent milling media.

15. The milling tool according to claim 1, wherein: The number of the slots is in the range of 1 to 200.

16. The milling tool according to claim 15, wherein: The number of slots is in the range of 16 to 200.

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