JP2016034673A - Diamond-coated cutting tool and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond-coated cutting tool which can solve problems caused by irregularities on the surface of a diamond coating while maintaining high wear resistance of the diamond coating.SOLUTION: A diamond-coated cutting tool has the surface of a tool body 1 coated with a diamond coating 10. The surface of the diamond coating 10 is coated with a hard coating 11 having a lower hardness than that of the diamond coating 10. The surface of the hard coating 11 is at least partially polished to form a polished surface 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diamond-coated cutting tool in which the surface of a tool body is coated with a diamond coating and a method for manufacturing the same.

  Such a diamond-coated cutting tool can obtain high wear resistance by a hard diamond coating even under severe conditions such as dry processing of a composite material of CFPR (carbon fiber reinforced resin) and a metal material such as aluminum. On the other hand, fine irregularities due to the microprojections of the diamond crystal grown on the surface of the diamond film are likely to occur, and if such irregularities remain on the diamond film covered in the chip discharge groove of the drill, for example, chip clogging occurs. There is a risk of breakage. In addition, if unevenness remains in the diamond coating coated on the margin of the drill, friction with the inner peripheral surface of the processed hole increases, cutting resistance increases, and the inner peripheral surface is damaged, resulting in surface roughness and machining. The quality will be lost.

  Therefore, in such a diamond-coated cutting tool, the surface of the diamond coating is smoothed by removing the irregularities due to the fine protrusions of the diamond crystal after coating the diamond coating. As a method for removing the unevenness in this way, for example, Patent Document 1 proposes polishing by pressing a diamond coating against a diamond sintered body, and Patent Documents 2 and 3 are irradiated with an ion beam. It has been proposed to polish the diamond coating.

Japanese Patent Laid-Open No. 10-249625 JP 2007-307673 A JP 2012-011475 A

  However, in the method in which the diamond coating is pressed against the diamond sintered body and polished as described in Patent Document 1, if the pressing force is too strong, the diamond coating itself may be destroyed or peeled off. If the pressing force is weak, the unevenness cannot be removed sufficiently. In addition, in polishing with an ion beam, it takes time to polish a wide range, and expensive equipment for irradiating the ion beam is required. Further, it is conceivable to polish the diamond coating by polishing or the like, but it still takes a lot of time to remove the irregularities of the hard diamond coating.

  The present invention has been made under such a background, and provides a diamond-coated cutting tool capable of solving the problems caused by irregularities on the surface of the diamond coating while maintaining high wear resistance due to the diamond coating. An object of the present invention is to provide a method for producing a diamond-coated cutting tool capable of producing such a diamond-coated cutting tool in a relatively short time at a low cost.

  In order to solve the above-mentioned problems and achieve such an object, the diamond-coated cutting tool of the present invention is a diamond-coated cutting tool in which a diamond coating is coated on the surface of a tool body, and the surface of the diamond coating Is characterized in that a hard coating having a hardness lower than that of the diamond coating is coated, and at least a part of the surface of the hard coating is a polished surface.

  The method for producing a diamond-coated cutting tool of the present invention is a method for producing such a diamond-coated cutting tool, in which a surface of the tool body is coated with a diamond coating, and the surface of the diamond coating is formed from the diamond coating. Is characterized in that a hard coating having a low hardness is coated and at least a part of the surface of the hard coating is polished to form the polished surface.

  In the diamond-coated cutting tool having the above-described configuration that can be manufactured by such a manufacturing method, the surface of the diamond coating is not directly removed, but the surface of the diamond coating is coated with a hard coating. Since the polished surface is formed by polishing, the wear resistance is maintained by the diamond film coated on the lower layer, while the smooth hard film polished surface ensures chip discharge, reduces cutting resistance, and roughens the processed surface. The sheath quality can be improved. For this reason, even in the dry processing of the composite material as described above, the tool life can be extended and high-precision processing can be performed.

  In addition, since the hard coating is harder but lower in hardness than the diamond coating, even if the surface of the hard coating itself has irregularities or the irregularities on the surface of the diamond coating appear on the surface of the hard coating, polishing processing A smooth polished surface can be formed by polishing the hard coating in a short time by low-cost polishing as described above. Furthermore, since it can be avoided that the polishing reaches the lower diamond film, the diamond film does not peel or break.

  Here, when the tool body has a chip discharge groove like a drill or an end mill, the surface of the hard coating coated on the chip discharge groove is used as the polishing surface, so that the chip discharge groove It is possible to prevent a situation in which chip clogging occurs and the tool body is broken. Similarly, when the tool body has a margin portion as in the case of a drill, the surface of the hard coating coated on the margin portion is used as the polished surface, so that the surface roughness of the inner peripheral surface of the processed hole is increased. The sheath quality can be improved.

  In addition, although the whole surface of the hard coating may be polished to be a polished surface, a part of the surface of the hard coating such as the above-described chip discharge groove or a margin portion is polished to be a polished surface. In addition, since the remaining surface is a non-polished surface that has not been polished, it is possible to further reduce the time required for polishing and provide a lower cost diamond-coated cutting tool.

  As described above, according to the diamond-coated cutting tool of the present invention, the tool life is ensured by the diamond film having high wear resistance even under severe conditions such as dry processing of a composite material of CFPR and a metal material. In addition, it is possible to improve the chip discharging property, the accuracy of the machined surface and the machining quality and reduce the cutting resistance by the smooth hard film polished surface. In addition, according to the method for manufacturing a diamond-coated cutting tool of the present invention, it is possible to manufacture such a diamond-coated cutting tool at a low cost in a short time.

It is a side view of the diamond covering drill which is one embodiment of the diamond covering cutting tool of the present invention. It is a side view of the drill before the coating of the diamond film in one Embodiment of the manufacturing method of the diamond coating cutting tool of this invention which manufactures embodiment shown in FIG. It is a figure which shows the state which coat | covered the diamond film on the surface of the cutting-blade part of the drill shown in FIG. It is a side view which shows the state which coat | covered the hard film on the diamond film of the cutting-blade part surface of the drill shown in FIG.

  FIG. 1 is a side view of a diamond-coated drill as an embodiment of the diamond-coated cutting tool of the present invention, and FIGS. 2 to 4 show the diamond-coated cutting tool of the present invention when manufacturing such a diamond-coated drill. It is a side view explaining one Embodiment of the manufacturing method of (drill).

  In the present embodiment, the tool body 1 is made of a hard material such as cemented carbide, and is formed in a cylindrical shaft shape with the axis O as the center, and the rear end portion of the tool body 1 is cylindrical. The front shank portion 2 is a cutting blade portion 3. In such a drill, the shank portion 2 is gripped by the main shaft of the machine tool and rotated in the tool rotation direction T around the axis O, and is sent to the tip end side in the axis O direction, so that the cutting blade portion 3 Drilling is performed on the work material by the formed cutting blade 4.

  In the cutting edge portion 3, two chip discharge grooves 5 that are twisted so as to be directed to the opposite side of the tool rotation direction T around the axis O from the front end to the rear end side of the tool body 1 are formed symmetrically with respect to the axis O. The cutting edge 4 is formed at the ridge part on the tip side of the wall surface of the chip discharge groove 5 facing the tool rotation direction T. That is, the diamond-coated drill of this embodiment is a solid twist drill with two blades.

  On the outer peripheral surface of the cutting edge 3, on the side opposite to the tool rotation direction T of the chip discharge groove 5, a small width located on a cylindrical surface centered on the axis O having the same diameter as the outer diameter of the cutting edge 4. A bank-like margin 6 is formed. Further, on the opposite side of the margin portion 6 from the tool rotation direction T, a cylindrical outer peripheral flank 7 having an outer diameter smaller than that of the margin portion 6 is formed.

  Moreover, the front end surface of the cutting edge part 3 is made into the front end flank 8 of the said cutting blade 4, and this front end flank 8 is between the chip discharge grooves 5 toward the front end side from the rear end of the tool main body 1. A coolant hole 9 extending spirally so as to pass therethrough is opened. In the case of dry processing, compressed air is supplied to the coolant hole 9 and ejected from the tip flank 8.

  The surface of the tool body 1 is coated with a diamond coating 10 as shown by hatching in FIG. 3, and the surface of the diamond coating 10 is hatched finer than that of FIG. 3 as shown in FIG. A hard coating 11 having a hardness lower than that of the diamond coating 10 is coated, and at least a part of the surface of the hard coating 11 is a polished surface 12 that is polished as shown by shading in FIG. Yes. In the present embodiment, as shown in FIGS. 1, 3, and 4, the diamond coating 10 and the hard coating 11 are coated on the surface of the distal end portion of the cutting blade portion 3 of the tool body 1, so that the polishing surface 12 is formed. Is formed.

  The diamond coating 10 is coated on the surface of the tool body 1 as it is formed of a hard material such as a cemented carbide shown in FIG. 2 by a known vapor phase synthesis method (CVD method), and the hardness is about Hv6000. The average film thickness of the diamond coating 10 is desirably in the range of about 5 to 20 μm, and the surface roughness is in the range of 4 μm or more as the maximum height Rz in JIS B 0601: 2001.

  The hard film 11 coated on the diamond film 10 is coated with one or more of carbides and nitrides such as AlCr, TiV, TiC, TiN, TiCN, and AlTiN by the PVD method. The hard coating 11 may be a DLC coating. The hardness of the hard coating 11 is desirably in the range of Hv 2000 to 3000, which is lower than that of the diamond coating 10, the average film thickness is in the range of about 1 to 8 μm, and the surface roughness without polishing is JIS B 0601: The maximum height Rz in 2001 is preferably in the range of 4 μm or more.

  In this embodiment, the hard coating 11 thus coated on the diamond coating 10 is polished by polishing to form the polished surface 12. Polishing is performed, for example, by applying a paste containing diamond particles to a brush, polishing powder (magnetic media) mixed with iron sand and diamond particles against a magnet, or spraying mixed particles of diamond particles and plastic particles. Is done.

  Of course, such polishing is performed within the range of the film thickness on which the hard coating 11 is coated, and the polishing does not reach the diamond coating 10 below the hard coating 11. By performing polishing by polishing in this manner, the surface roughness of the polishing surface 12 is desirably in the range of 1 to 3 μm as the maximum height Rz in JIS B 0601: 2001.

  Here, in the present embodiment, the entire surface of the hard coating 11 coated on the tip portion of the cutting blade portion 3 is not polished, but a part of this surface is used as the polishing surface 12 and the remaining surface. The surface of this part is an unpolished surface that has not been polished. Specifically, in this embodiment, the inner surface of the chip discharge groove 5 and the surface of the margin portion 6 are used as the polishing surface 12, and the remaining outer peripheral flank 7 and tip flank 8 are non-polishing surfaces.

  In one embodiment of the manufacturing method of the present invention when manufacturing such a diamond-coated cutting tool (drill), the cutting edge of the tool body 1 as it is formed of a hard material such as cemented carbide shown in FIG. As shown in FIG. 3, the diamond coating 10 is coated on the surface of the tip of the portion 3, and then the hard coating 11 is coated on the diamond coating 10 as shown in FIG. 4, and then the inner surface of the chip discharge groove 5. The hard film 11 on the surface of the margin portion 6 may be polished to form the polished surface 12 as shown in FIG. When the diamond coating 10 or the hard coating 11 is coated, masking may be applied to the rear end portion of the cutting blade portion 3 that is not coated and the surface of the shank portion 2.

  In the diamond-coated cutting tool having the above-described structure manufactured by such a manufacturing method, even if fine irregularities due to minute protrusions of the grown diamond crystal are generated on the surface of the diamond coating 10, the hard coating 11 is coated on this surface. As a result, it is possible to suppress the unevenness due to the microprojections of the diamond crystal from appearing on the surface of the tool body 1. Further, even if the hard film 11 is coated so as to follow the unevenness due to the minute protrusions and the unevenness appears on the surface, or the unevenness is caused by the minute protrusions of the hard film 11 itself, the hard film 11 is polished. By forming the polished surface 12, smoothing can be achieved.

  In particular, the diamond-coated cutting tool of the present embodiment is a diamond-coated drill, and a polishing surface 12 is formed on the inner surface of the chip discharge groove 5, and the inner surface of the chip discharge groove 5 on which the chips are scraped is the polishing surface 12. By being smoothed, chip clogging can be prevented and breakage of the tool body 1 can be prevented. Similarly, in the present embodiment which is a diamond-coated drill, the surface of the margin portion 6 connected to the opposite side to the tool rotation direction T of the chip discharge groove 5 is also a polishing surface 12 and is formed by the cutting edge 4. By smoothing the margin portion 6 that is in sliding contact with the inner peripheral surface of the processed hole, it is possible to reduce cutting resistance and improve the surface roughness and processed quality of the processed hole.

  On the other hand, the wear resistance of the tool body 1 can be sufficiently secured by the diamond coating 10 coated on the tool body 1. Therefore, according to the diamond-coated cutting tool having the above-described configuration, high-precision cutting can be performed while extending the tool life even under severe cutting conditions such as dry cutting of a composite material of CFPR and a metal material such as aluminum. Can be done.

  Further, when the polished surface 12 is formed in this way, in the present embodiment, the hard film 11 coated with the diamond film 10 is polished, and the hard film 11 has a hardness as described above and is hard, for example. However, since it is softer than the diamond coating 10, the polishing surface 12 can be formed in a short time by a relatively low cost polishing process such as the polishing process described above. In addition, such a polishing process places a small load on the hard coating 11 and the underlying diamond coating 10, and the diamond coating 10 and the hard coating 11 are not peeled off or destroyed by polishing.

  In the present embodiment, as described above, a part of the surface of the hard coating 11 between the inner surface of the chip discharge groove 5 and the margin portion 6 at the tip portion of the cutting blade portion 3 is the polishing surface 12, The remaining outer peripheral flank 7 and tip flank 8 are non-polished surfaces with the hard coating 11 still coated. That is, the outer peripheral flank 7 and the tip flank 8 which are flank surfaces and rarely come into contact with the work material do not increase the resistance or deteriorate the machined surface roughness even if the surface of the hard coating 11 is uneven. By making such a portion a non-polishing surface without incurring, the time and cost required for polishing can be further reduced according to the present embodiment.

  In the present embodiment, a part of the surface of the hard coating 11 is used as the polishing surface 12 and the remaining surface is a non-polished surface that is not polished. The entire surface of the hard coating 11 may be polished to form the polished surface 12. In the present embodiment, the hard coating 11 is coated in accordance with the region coated with the diamond coating 10, but the hard coating 11 is coated over a wider range than the region coated with the diamond coating 10, or conversely, a narrow range. Then, the polishing surface 12 may be formed by polishing at least a part of the surface.

  Furthermore, although this embodiment demonstrated the case where this invention was applied to a diamond covering drill as mentioned above, this invention is similarly applied to other drilling tools, such as a reamer which has a chip discharge groove and a margin part. It is also possible to apply the present invention to a cutting tool such as an end mill that has a chip discharge groove and may have a margin portion. Furthermore, the present invention may be applied to a cutting tool such as a cutting insert.

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Shank part 3 Cutting edge part 4 Cutting edge 5 Chip discharge groove 6 Margin part 7 Outer peripheral flank 8 Tip flank 9 Coolant hole 10 Diamond coating 11 Hard coating 12 Polishing surface O Tool body 1 axis T Tool rotation direction

Claims (5)

  A diamond-coated cutting tool in which a surface of a tool body is coated with a diamond coating, wherein the surface of the diamond coating is coated with a hard coating having a hardness lower than that of the diamond coating, and at least the surface of the hard coating is A diamond coated cutting tool characterized in that a part thereof is a polished surface.   The diamond-coated cutting tool according to claim 1, wherein the tool body includes a chip discharge groove, and the surface of the hard coating coated on the chip discharge groove is the polished surface.   The diamond-coated cutting tool according to claim 1 or 2, wherein the tool main body includes a margin portion, and the surface of the hard coating coated on the margin portion is the polished surface. .   The part of the surface of the hard coating is the polishing surface, and the surface of the remaining part is a non-polishing surface that is not polished. Diamond coated cutting tool as described in any one of them.   The method for manufacturing a diamond-coated cutting tool according to any one of claims 1 to 4, wherein a surface of the tool body is coated with a diamond coating, and the surface of the diamond coating is formed from the diamond coating. A method for producing a diamond-coated cutting tool, wherein a hard coating having a low hardness is coated and at least a part of the surface of the hard coating is polished to form the polished surface.

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