JP2007307673A - Diamond-coated cutting member and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and inexpensively provide a comparatively smooth chamfer without damaging a cutting edge of a diamond-coated cutting member. <P>SOLUTION: This chamfer 30 is formed by masking a polishing unnecessary part by a masking agent 52 in a (b) process after coating a diamond film 22 of microcrystal having about 1μm of a crystal particle diameter in a (a) process and polishing the diamond film 22 by irradiating ion beam in a (c) process. Ruggedness of the surface of the chamfer 30 is small because the diamond film 22 is microcrystal, the surface is smooth even when the chamfer 30 is provided by etching by ion beam, and thereby excellent cutting performance can be obtained in combination with sharpening of the cutting edge 24. The chamfer 30 can be easily and inexpensively manufactured as compared with a case where the etching by ion beam is performed after a graphite film is provided for smoothing. The possibility of damaging the cutting edge 24 is eliminated as compared with a case where polishing is performed by a grinding tool. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diamond-coated cutting member, and more particularly to a diamond-coated cutting member in which a chamfer is provided on a cutting edge to obtain excellent cutting performance, and a method for manufacturing the same.

As a cutting member such as an end mill, a tap, or a drill, or a cutting member such as a throw-away tip, a diamond-coated cutting member in which a surface of a base material such as cemented carbide is coated with a diamond coating has been proposed. The tool described in Patent Document 1 is an example, and a polycrystalline diamond film is coated on the surface by a microwave plasma CVD (chemical vapor deposition) method, and a cutting edge coated with the diamond film is formed. The chamfer is provided in the cutting edge portion by polishing with a diamond grindstone, and excellent cutting performance can be obtained by combining sharpening of the cutting edge (sharp edge) and improvement of surface roughness.
JP 2002-370106 A

  However, the operation of polishing the diamond film with the diamond grindstone as described above is troublesome and requires skill, and the productivity is poor and the blade edge may be damaged. In addition, in a rotary cutting tool that performs cutting with an outer peripheral cutting edge integrally provided on the tool base, it is difficult to polish the rake face side of the outer peripheral cutting edge with a diamond grindstone, and the cutting edge is sufficiently sharpened. There was a case that could not be. For this reason, when various other polishing methods were examined, for example, etching by ion beam irradiation as described in Patent Document 2 can be considered. However, since etching with an ion beam is affected by the uneven shape before processing, when applied to the polishing of a diamond coating, if the surface of the diamond coating is uneven, unevenness remains on the polished surface, and polishing with a grindstone In comparison, there was a problem that the surface roughness of the chamfer deteriorated and the cutting performance deteriorated.

  Although not yet known, FIG. 10 shows that the surface of the cemented carbide substrate 200 is irradiated with an ion beam on the flank 206 side portion of the cutting edge 204 of the cutting edge 204 coated with the diamond coating 202 by the microwave plasma CVD method. This is a case where the chamfer 208 is formed. 10A shows a state in which the diamond film 202 is coated, and FIG. 10B shows a state after the chamfer 208 is provided by irradiating an ion beam. Unevenness of about several μm still remains. When the polishing time is increased by increasing the etching time by the ion beam, the unevenness is reduced. However, since the film thickness of the diamond coating 202 provided on the cutting member is generally about 20 μm or less, the diamond coating 202 itself becomes too polished. It becomes thin and the desired performance cannot be obtained. The dotted line in (b) of FIG. 10 shows the state before etching by the ion beam, that is, the same surface shape as in FIG. 10 (a).

  On the other hand, as described in Patent Document 3, as a method for smoothing the diamond coating by such an ion beam, a graphite film is formed so as to fill the irregularities on the surface of the diamond coating, and the graphite is mechanically polished. It has been proposed to perform an ion beam etching process after smoothing the surface of the film.

  However, in the case where etching is performed with an ion beam after mechanically polishing the graphite film as described above, there is still room for improvement because the number of manufacturing steps and manufacturing facilities increase and the manufacturing cost increases.

The present invention has been made against the background of the above circumstances, and its object is to provide a relatively smooth chamfer easily and inexpensively without damaging the cutting edge of the diamond-coated cutting member. In addition, the chamfer can be easily polished even on the rake face side of the outer peripheral cutting edge, which is difficult to grind with a grindstone.
US Pat. No. 5,032,243 JP 2001-139318 A

  In order to achieve such an object, the first invention provides a diamond-coated cutting member such as a throwaway tip or a cutting tool in which a surface of a cutting edge is coated with a diamond coating, wherein (a) the diamond coating has a crystal grain size Is composed of microcrystalline diamond of 2 μm or less, and (b) the diamond coating is polished by ion beam etching on at least one of the rake face side and the flank face side of the cutting edge. Thus, a chamfer is provided.

  According to a second aspect of the present invention, in the diamond-coated cutting member according to the first aspect of the present invention, the chamfer is provided, whereby the tip roundness of the cutting edge represented by the radius of the inscribed circle S in contact with the tip position Q of the chamfer in the section perpendicular to the blade. The diameter R is 10 μm or less.

According to a third aspect of the present invention, in the diamond-coated cutting member according to the second aspect, the chamfer is provided by etching with the ion beam on both the flank face side and the rake face side of the cutting edge. It is characterized as follows.
When chamfers are provided on both the flank face side and the rake face side, the smaller radius of the pair of inscribed circles S in contact with the tip position Q of each chamfer is defined as the tip round diameter R.

  A fourth invention is the diamond-coated cutting member according to any one of the first to third inventions, wherein (a) the diamond-coated cutting member is driven to rotate by an outer peripheral cutting edge by being driven to rotate about an axis. In the diamond-coated rotary cutting tool, (b) the chamfer is provided on at least the flank side of the outer peripheral cutting edge, and the width dimension of the chamfer provided on the flank side in the cross section perpendicular to the blade is a tool diameter D Is 0.2 × D or less.

  A fifth invention is the diamond-coated cutting member according to any one of the first to fourth inventions, wherein (a) the diamond-coated cutting member is driven to rotate by an outer peripheral cutting edge by being driven to rotate around an axis. In the diamond-coated rotary cutting tool, (b) the outer peripheral cutting edge is provided integrally with the tool base, and (c) etching by the ion beam on both the flank side and the rake face side of the outer peripheral cutting edge. And the chamfer is provided.

  A sixth aspect of the present invention is the diamond-coated cutting member according to any one of the first to third aspects of the present invention, wherein the diamond-coated cutting member is detachably attached to a tool body configured separately and used. It is characterized by being.

  A seventh invention is a method for producing a diamond-coated cutting member having a surface of a cutting edge coated with a diamond coating, wherein (a) microcrystalline diamond having a crystal grain size of 2 μm or less is repeatedly generated by vapor phase growth. A microcrystalline diamond coating step for coating the diamond film, and (b) etching with an ion beam on at least one of a rake face side and a flank face side of the cutting edge provided with the diamond film. And an ion beam etching step of polishing the diamond film to provide a chamfer.

  In the diamond-coated cutting member according to the first to sixth inventions, since the diamond film is composed of microcrystalline diamond having a crystal grain size of 2 μm or less, the surface roughness is higher than that of a normal polycrystalline diamond film. Becomes smaller and smoother. For this reason, even when chamfers are provided on the diamond coating by ion beam etching, the surface of the chamfer is relatively smooth and polished with a conventional diamond grindstone coupled with sharpening of the blade edge (sharpening). As a result, cutting performance equivalent to that obtained can be obtained.

  In this case, in the present invention, after the diamond film is coated, the diamond film may be directly irradiated with an ion beam to perform etching. Therefore, the number of manufacturing steps is compared with the case where a graphite film is provided (Patent Document 3). Manufacturing equipment is saved, and it can be manufactured easily and inexpensively. Also, compared to the case of polishing using a diamond grindstone (Patent Document 1), there is no fear of damaging the cutting edge, and automation is possible and productivity is improved, while the tool base is provided integrally. It is also possible to easily grind the rake face side of the outer peripheral cutting edge. For example, by providing chamfers on both the flank face side and the rake face side as in the third and fifth inventions, the tip round diameter R is further increased. The cutting performance can be greatly improved by reducing the size.

  In the second aspect of the present invention, the chamfer is provided so that the rounded tip radius R is 10 μm or less, so that excellent cutting performance can be obtained by sharpening the blade edge. By providing chamfers on both the flank face side and the rake face side of the cutting edge, in the third invention in which the tip roundness radius R is 1 μm or less, further excellent cutting performance can be obtained by sharpening the cutting edge. .

  The fourth invention relates to a diamond-coated rotary cutting tool, and since a chamfer is provided on the flank side, contact between the machining surface and the chamfer increases due to the elasticity of the workpiece even when the chamfer flank angle is positive. However, since the chamfer width dimension is 0.2 × D or less with respect to the tool diameter D, coupled with the fact that the chamfer surface roughness is superior to other parts, it is related to the increased contact between the machining surface and the chamfer. The increase in cutting resistance and the deterioration of the machined surface roughness are suppressed.

  The fifth invention relates to a diamond-coated rotary cutting tool in which an outer peripheral cutting edge is provided integrally with a tool base material, and not only the flank side of the outer peripheral cutting edge but also a rake face that has been difficult with conventional grinding stone polishing. Since the chamfer is provided on the side by etching with an ion beam, the cutting edge can be further sharpened, and the cutting performance can be further improved.

  The seventh invention relates to a method of manufacturing a diamond-coated cutting member in which a chamfer is provided on a cutting edge, and a diamond film is coated by repeatedly generating microcrystalline diamond having a crystal grain size of 2 μm or less by a vapor phase growth method. After that, since the chamfer is provided by etching the cutting edge provided with the diamond coating with an ion beam, substantially the same effect as the first invention can be obtained.

  The diamond-coated cutting member of the present invention is suitably applied to various cutting members such as rotary cutting tools such as end mills, taps, and drills, cutting tools such as cutting tools, and throw-away tips. As the base material (tool base material) to be coated with the diamond film, a super hard tool material such as a cemented carbide is preferably used. In order to improve the adhesion, a predetermined pretreatment such as roughening the surface of the substrate or providing another coating as a base can be performed.

  For the coating of the microcrystalline diamond film, a CVD method such as a microwave plasma CVD method, a hot filament CVD method, or a high frequency plasma CVD method is preferably used. When cemented carbide is used as the base material, Co (cobalt) may precipitate and the adhesion (adhesion strength) of the diamond film may be impaired. It is desirable to perform a pretreatment such as removing Co or providing an intermediate layer for preventing Co precipitation.

  Microcrystalline diamond can be formed by repeating a nucleation step and a crystal growth step as described in, for example, JP-A-2002-79406. The crystal grain size is 2 μm or less, preferably 1 μm or less. The crystal grain size is preferably the maximum diameter in a direction perpendicular to the crystal growth direction, and the crystal grain size of all diamonds is preferably 2 μm or less, but at least 80% of the crystal grains on the surface or a predetermined cross section. The above may be 2 μm or less. Further, if the length dimension in the crystal growth direction is 2 μm or less, the crystal grain size in the direction perpendicular to the crystal growth direction is generally 2 μm or less. Even if the dimension in the crystal growth direction is larger than 2 μm, the crystal grain size may be 2 μm or less.

  When the film thickness of the diamond coating is less than 5 μm, for example, sufficient wear resistance and the like cannot be obtained. On the other hand, when it exceeds 25 μm, it is not preferable because it is easy to peel off. 8 to 20 μm is particularly desirable.

  Etching with an ion beam can be performed, for example, by irradiating the cutting edge with an ion beam from a predetermined angle direction using an apparatus as described in Patent Document 2. As the ion beam, ions of hydrogen gas, oxygen gas, nitrogen gas, or inert gas such as argon gas, krypton gas, xenon gas, neon gas are preferably used. The portions other than the blade edge to be etched may be masked with a mask agent such as a photoresist.

  The chamfer may be provided only on either the flank face side or the rake face side of the cutting edge, but can also be provided on both. It is also possible to partially polish using other polishing means such as grindstone polishing. The fourth and fifth inventions relate to the outer peripheral cutting edge, but can also be applied to other cutting edges such as a bottom cutting edge. The shape of the chamfer is provided, for example, so as to be substantially linear in the cross section perpendicular to the blade, but various shapes such as a concave shape and a convex shape can be adopted.

  When the straight chamfer is provided on only one of the flank side and the rake surface side, the tip roundness diameter R of the cutting edge of the second invention is two straight lines representing the chamfer and the other surface in a cross section perpendicular to the blade. This is an inscribed circle (including an extended line of the surface), and is the radius of the inscribed circle S that contacts the tip position Q of the chamfer. When straight chamfers are provided on both the flank face side and the rake face side, they are inscribed circles of two straight lines (including the chamfer extension line) representing both chamfers in the cross section perpendicular to the blade, The smaller radius of the two inscribed circles S in contact with the tip position Q of the chamfer is defined as a tip rounding diameter R.

  In the case where a linear chamfer is provided in the cross section perpendicular to the blade, the inclination angle of the chamfer with respect to a surface that is easy to escape is suitably in the range of about 1 ° to 30 °, for example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view for explaining an end mill 10 as a diamond-coated cutting member and a diamond-coated rotary cutting tool according to an embodiment of the present invention. FIG. 1 (a) is a front view seen from a direction perpendicular to the axis. ) Is an enlarged view of a cross section perpendicular to the cutting edge 16 of the outer peripheral cutting edge 16. This end mill 10 is integrally provided with a shank 12 and a blade portion 14 concentrically in the axial direction, and an outer peripheral cutting edge 16 and a bottom blade 18 are integrally provided on a tool base 20 on the outer peripheral surface of the blade portion 14. In addition, the surface of the tool base 20 at the blade portion 14 is coated with a diamond coating 22. The outer peripheral cutting edge 16 is a torsional blade that is twisted around a shaft center at a predetermined twist angle, and the bottom blade 18 is provided in a substantially straight line continuously from the outer peripheral cutting edge 16 toward the shaft center. The tool base 20 is made of a cemented carbide, and the diamond coating 22 is made of microcrystalline diamond having a crystal grain size of about 1 μm. In this embodiment, it is about 20 μm within the range of about 20 μm. A hatched portion in FIG. 1 represents a coating region of the diamond film 22.

  As apparent from FIG. 1B, the peripheral cutting edge 16 is provided with a flank 26 and a rake face 28 continuously from the cutting edge 24 without a margin, and the flank 26 and rake face 28 thereof. The blade angle represented by the crossing angle is an acute angle, and the clearance angle and the rake angle are both positive. In the state where the diamond film 22 is coated (dotted line in FIG. 1 (b)), the cutting edge 24 has a substantially arc shape, but the ion beam etching is performed on the flank face 26 side of the cutting edge 24 by diamond. By being applied to the surface layer portion of the coating 22, a substantially linear chamfer 30 is provided. The inclination angle α of the chamfer 30 with respect to the flank 26 is within a range of 1 ° to 30 °, and the flank angle is positive in the portion where the chamfer 30 is provided, and the width dimension W1 is relative to the tool diameter D. And 0.2D or less. Specifically, the inclination angle α≈7 °, the tool diameter D≈6 mm, and the width dimension W1≈1.0 mm. In addition, the ratio of the dimension of each part shown to a figure, and an angle are not necessarily exact.

  In addition, as shown in FIG. 2, an inscribed circle with respect to two straight lines representing the straight chamfer 30 and the rake face 28 (including the extension line) in the cross-section perpendicular to the blade, and is inscribed in contact with the tip position Q of the chamfer 30. The rounded tip radius R represented by the radius of the circle S is 10 μm or less, and is about 8 μm in this embodiment. As shown by the dotted line in FIG. 1 (b), the roundness R of the tip in the state in which the diamond coating 22 is still coated is the arc-shaped radius of the surface of the diamond coating 22 and is substantially the same as the film thickness d. In the example, it is about 20 μm, but it is reduced by providing the chamfer 30.

  As described above, the chamfer 30 is provided to reduce the roundness R of the tip and sharpen the cutting edge 24. The chamfer 30 has a surface roughness excellent in that the diamond coating 22 itself is microcrystalline and the surface roughness is excellent. In addition, since the etching is further improved by the ion beam etching, an excellent sharpness can be obtained and the cutting performance is improved.

  FIG. 3 is a diagram for explaining a procedure for manufacturing the end mill 10 of the present embodiment. In the microcrystalline diamond coating step (a), the tool base 20 on which the outer peripheral cutting edge 16 and the like are formed in advance by grinding or the like is shown. The diamond film 22 is coated on the blade portion 14 by growing diamond particles having a crystal grain size of about 1 μm by microwave plasma CVD. In order to improve the adhesion of the diamond coating 22, the surface of the blade portion 14 of the tool base 20 is preliminarily roughened and contained in the cemented carbide constituting the tool base 20. In order to prevent the adhesion (adhesion strength) of the diamond coating 22 from being impaired by the deposition of Co, the pretreatment for removing Co in the vicinity of the surface by acid treatment is performed prior to the coating of the diamond coating 22. As the surface roughening treatment, for example, chemical erosion such as electrolytic polishing or sand blasting with an abrasive such as SiC is suitable.

  The microcrystalline diamond coating by the microwave plasma CVD method is performed using, for example, a microwave plasma CVD apparatus 50 shown in FIG. The microwave plasma CVD apparatus 50 includes a reaction furnace 32, a microwave generator 34, a source gas supply device 36, a vacuum pump 38, and an electromagnetic coil 40. A table 42 is provided in the cylindrical reaction furnace 32, and a plurality of tool base materials 20 to be coated with the diamond coating 22 are supported by a work support tool 44, and each blade 14 is disposed so that the blade portion 14 faces upward. It has become so. The microwave generator 34 is an apparatus that generates a microwave of, for example, 2.45 GHz. The microwave base 34 is heated by introducing the microwave into the reaction furnace 32, and the microwave generator 34 is also used. The heating temperature is adjusted by controlling the electric power.

The source gas supply device 36 is for supplying source gases such as methane (CH ₄ ), hydrogen (H ₂ ), and carbon monoxide (CO) into the reaction furnace 32, and controls the gas cylinders and flow rates thereof. A flow control valve, a flow meter, and the like. The vacuum pump 38 is for sucking and depressurizing the gas in the reaction furnace 32, so that the pressure value in the reaction furnace 32 detected by the pressure gauge 46 becomes a predetermined pressure value determined in advance. The motor current of the vacuum pump 38 is feedback controlled. The electromagnetic coil 40 is arranged in an annular shape on the outer peripheral side of the reaction furnace 32 so as to surround the inside of the reaction furnace 32.

As shown in FIG. 5, the coating process of the diamond film 22 using such a microwave plasma CVD apparatus 50 includes a step R1 of the nucleus deposition process and a step R2 of the crystal growth process. In the nuclear deposition step of Step R1, the flow rate of methane and hydrogen is adjusted so that the concentration of methane is set within a range of 10% to 30%, and the surface temperature of the tool base 20 is 700 ° C. The microwave generator 34 is adjusted so that the set temperature is set in a range of ˜900 ° C., and the gas pressure in the reaction furnace 32 is in a range of 2.7 × 10 ² Pa to 2.7 × 10 ³ Pa. The vacuum pump 38 is operated so as to reach the set pressure determined in the above, and this state is continued for 0.1 to 2 hours. As a result, a nucleus layer serving as a starting point of diamond crystal growth is attached to the surface of the tool base 20 or the surfaces of a large number of diamond crystals that have been crystal-grown by the crystal growth treatment in step R2.

In the crystal growth step of Step R2, the flow rate of methane and hydrogen is adjusted so that the methane concentration becomes a set value determined within the range of 1% to 4%, and the surface temperature of the tool base 20 is 800 ° C. 900 to adjust the microwave generator 34 so as to set the temperature defined in the range of ° C., ranges gas pressure in the reaction furnace 32 is ^{1.3 × 10 3 Pa~6.7 × 10 3} Pa The vacuum pump 38 is operated so that the set pressure is set within the predetermined pressure, and the state is determined for a predetermined time, specifically, the crystal length of the diamond so that the crystal grain size of the diamond is about 1 μm. This is continued for a predetermined processing time determined in advance so that (the length dimension in the crystal growth direction) becomes 1 μm. That is, in the crystal growth process of this embodiment, if the length dimension in the crystal growth direction is 1 μm, the crystal grain size in a plane substantially perpendicular to the crystal growth direction is also about 1 μm.

  Then, in the next step R3, it is determined whether or not the film thickness d of the diamond coating 22 crystal-grown on the surface of the tool base 20 has reached a predetermined set film thickness (20 μm in this embodiment). For example, the determination is made based on the number of executions of step R2, and the above steps R1 and R2 are repeated until the set film thickness is reached. During the execution of Step R1, the crystal growth of diamond is stopped, and a new nucleus layer is formed on the crystal. In the subsequent crystal growth process (Step R2), the diamond crystal below the nucleus layer is formed. The diamond film 22 is not regrown but is newly grown from a new nucleus as a starting point, so that the diamond film 22 having a crystal grain size and a crystal length of both about 1 μm and a multi-layer structure is formed on the tool substrate. 20 surfaces are coated.

  Returning to FIG. 3, in the masking step (b), a part 28 on the cutting edge 24 side of the flank face 26, leaving a range where the chamfer 30 is to be formed, and the other flank face 26 that is easy to form, etc. Is masked with a masking agent 52 such as a photoresist. Any masking agent 52 may be used as long as it can prevent etching of the diamond coating 22 by ion beam irradiation.

  The subsequent ion beam etching step (c) is performed using, for example, an ion beam etching polishing apparatus as described in Patent Document 2, and is applied to the outer peripheral cutting edge 16 from a direction perpendicular to the chamfer 30 to be formed. On the other hand, by irradiating the ion beam, a portion other than the region masked by the masking agent 52 is polished to form the chamfer 30. FIG. 6 shows an example of such an ion beam etching polishing apparatus 70. A workpiece 72 coated with a diamond coating 22 and provided with a masking agent 52 is placed on a rotary table 74 in a vacuum vessel 90 by a chuck 76. The chamfer 30 is formed by polishing the diamond film 22 by an ion beam fixed from the ion beam gun 82a, 82b fixed to the center line C and having an ion generation source.

  In this embodiment, oxygen is used as a working gas, and an oxygen ion beam is emitted. The degree of vacuum in the vacuum vessel 90 is 0.1 Pa, and the acceleration voltage of ions is 3.0 kV. The distance from the ion beam guns 82a and 82b to the outer peripheral cutting edge 16 of the workpiece 72 is 200 mm, and a load bias (Bias) of 50 kHz and 500 V is applied to the workpiece 72 by a bias power source 92. The ion beam irradiation duration was 5 hours, for example, and the ion source current value was 500 mA. In this embodiment, since the pair of ion beam guns 82a and 82b are provided, the pair of outer peripheral cutting edges 16 symmetrically positioned on both sides of the center line C (same as the axis of the work 72) are simultaneously provided. Polishing (etching) can be performed. By changing the phase around the center line C of the work 72 by 90 ° and irradiating the ion beam again, the four outer peripheral cutting edges 16 can be polished.

  Further, since the outer peripheral cutting edge 16 is twisted in the end mill 10 of this embodiment, the irradiation position of the ion beam can be changed along the twist. That is, the rotary table 74 is rotationally driven at a predetermined rotational speed around the center line C by a rotary drive device 78 having an electric motor, a speed reducer, and the like. It is integrally rotated (spinned) around the axis. A vertical moving table 80 is disposed above the rotary table 74, and the ion beam guns 82a and 82b are disposed via biaxial irradiation angle adjusting devices 84a and 84b, respectively, and the chamfer 30 to be formed. Therefore, the posture is controlled so that the ion beam can be irradiated vertically. The vertical moving table 80 is also provided with an approach / separation device for approaching and separating the ion beam guns 82a, 82b together with the irradiation angle adjusting devices 84a, 84b according to the diameter size of the work 72 and the like.

  The vertical moving table 80 is vertically moved by an axial moving device 86 having a feed screw that is driven to rotate in both forward and reverse directions by an electric motor, that is, the axis (center line C) of the work 72 fixed to the rotary table 74. It can be moved in a straight line in the direction parallel to. Then, an electronic controller 88 having a microcomputer or the like causes the ion beam guns 82a and 82b to be relatively rotated around the axis along the outer peripheral cutting edge 16 and to be relatively moved in the axial direction. The axial movement device 86 is controlled in association with each other, and the ion beam is irradiated substantially perpendicularly to the surface of the outer peripheral cutting edge 16 over the entire length thereof. The ion beam irradiation time is appropriately determined according to the length of the outer peripheral cutting edge 16, the polishing amount of the diamond coating 22, and the like. Then, after forming the chamfer 30 by etching with an ion beam in this way, the end mill 10 is obtained by removing the masking agent 52.

  As described above, according to the end mill 10 of the present embodiment, the diamond coating 22 is composed of microcrystalline diamond having a crystal grain size of about 1 μm. Therefore, the surface roughness is higher than that of a normal polycrystalline diamond coating. Becomes smaller and smoother. For this reason, even when the chamfer 30 is provided on the diamond coating 22 by ion beam etching, the surface of the chamfer 30 is relatively smooth and coupled with the sharpening (sharp edge) of the blade edge 24, Excellent cutting performance comparable to that obtained when polishing with a diamond grindstone (Patent Document 1) can be obtained. In this embodiment, since the chamfer 30 is provided, the rounded tip radius R is set to 10 μm or less, so that excellent cutting performance can be obtained by sharpening the blade edge 24.

  In this case, in this embodiment, after the diamond film 22 is coated, the diamond film 22 may be directly irradiated with an ion beam to perform etching, which is compared with the case where a graphite film is provided (Patent Document 3). Thus, manufacturing man-hours and manufacturing facilities are reduced, and the manufacturing can be performed easily and inexpensively. Moreover, compared with the case where it grinds using a diamond grindstone (patent document 1), there is no fear of damaging the blade edge 24, and automation is possible and productivity is improved.

  Further, in the present embodiment, the chamfer 30 is provided on the flank 26 side. Therefore, even if the flank angle of the chamfer 26 is positive, the contact between the machining surface and the chamfer 26 increases due to the elasticity of the workpiece. Since the width dimension W1 of the chamfer 26 is about 1.0 mm and is 0.2 × D or less with respect to the tool diameter D (≈6 mm), the surface roughness of the chamfer 26 is superior to other parts. In combination, the increase in cutting resistance and the deterioration of the machined surface roughness are suppressed regardless of the increased contact between the machined surface and the chamfer 26. In particular, in this embodiment, since the chamfer 26 has a small inclination angle α of about 7 °, the contact between the machining surface and the chamfer 30 is reduced, and the increase in cutting resistance and the degradation of the machining surface roughness are further suppressed.

  In the above embodiment, the chamfer 30 is provided only on the flank 26 side. However, like the outer peripheral cutting edge 60 shown in FIG. 7, in addition to the chamfer 30 on the flank 26 side, the chamfer 30 side is also provided. A chamfer 62 may be provided. The outer peripheral cutting edge 60 is provided in the end mill 10 instead of the outer peripheral cutting edge 16, and the diameter dimension D and the like are the same, and the width dimensions W1 and W2 of the chamfers 30 and 62 are appropriately set. In this embodiment, W1≈0.7 mm and W2≈0.6 mm. Further, the inclination angles thereof are within a range of 1 ° to 30 °, and in this embodiment, both are about 7 °. The clearance angle and the rake angle in the chamfers 30 and 62 are both positive and the tip is rounded. The diameter R is about 0.5 μm. FIG. 7A is an enlarged view of a cross section perpendicular to the outer peripheral cutting edge 60 corresponding to FIG. 1B, and FIG. 7B is an ion beam etching process corresponding to FIG. 3C. In this case as well, the masking agent 52 is provided except for the range in which the chamfers 30 and 62 are to be formed, and the diamond film 22 is etched by irradiating the ion beam, so that the chamfers 30 and 62 can be provided.

  Thus, in this embodiment, the chamfer 62 is provided not only on the flank face 26 side of the outer peripheral cutting edge 60 but also on the rake face 28 side, which is difficult with conventional grinding stone polishing, by ion beam etching. It is possible to further sharpen the cutting edge 24 by reducing the tip rounding diameter R, and it is possible to further improve the cutting performance.

Incidentally, for a two-blade end mill with a tool diameter D = 10 mm, a diamond film 22 having a crystal grain size of about 1 μm is simply coated with a film thickness d≈20 μm (comparative product; rounded tip diameter R≈20 μm), 7 in which chamfers 30 and 62 are provided on both the flank face and the rake face by ion beam etching as in the outer peripheral cutting edge 60 in FIG. 7 (invention product 1; rounded tip diameter R≈0.5 μm), and FIG. Prepare a total of three test products, such as the one with the chamfer 30 provided only on the flank, such as the outer peripheral cutting edge 16 of the present invention (Product 2 of the present invention; tip rounded radius R≈8 μm), and cutting under the following processing conditions When the cutting resistance was examined by processing, the result shown in FIG. 8 was obtained. Cutting resistance is a factor that greatly affects sharpness, machined surface roughness, and tool durability.
"Processing conditions"
・ Tool 2 flute carbide end mill, φ10
・ Tool rotation speed 10,000min ^-1
・ Feeding speed 0.05mm / t
・ Incision Axial direction (Z direction) aa = 15 mm
Radial direction (Y direction) ar = 0.5mm
・ Coolant Water-soluble cutting fluid ・ Processing type Side (down)
・ Work material A7075 (Aluminum alloy)

  FIG. 8A is a diagram showing the direction of the cutting force to be measured in relation to the posture of the test product 68 during cutting with respect to the work material 66, where X is the feed direction, Y is the feed vertical direction, Z is the thrust direction (tool axis direction). As is apparent from the measurement result of FIG. 8B, the products 1 and 2 of the present invention have a cutting resistance smaller than that of the comparative product in any direction. Particularly remarkable in the Y-axis direction, the product 1 of the present invention is ½ or less of the comparative product, and the tilting of the tool is suppressed and the machining accuracy is improved.

  On the other hand, FIG. 9 shows an embodiment in which the present invention is applied to the throw-away end mill 100, where (a) is a front view, (b) is a bottom view, and (c) is a right side view of (a). It is composed of a cylindrical tool body 112 and a pair of throw-away tips 114a and 114b. The throwaway tips 114a and 114b correspond to diamond-coated cutting members, and the throwaway end mill 100 to which the throwaway tips 114a and 114b are attached corresponds to a diamond-coated rotary cutting tool.

  The tool body 112 is made of high-speed tool steel, and is integrally provided with a shank 116 and a groove 118 on the same axis, and is driven to rotate clockwise around the axis O when viewed from the shank 116 side. Is for right rotation in which cutting is performed. The groove portion 118 is provided with a pair of tip mounting grooves 120 and 122. The throwaway tips 114a and 114b are arranged in a posture inclined in a clockwise direction at a predetermined twist angle, and are attached and detached by a screw 124 as a clamping device. It can be attached as possible.

  The throw-away tips 114a and 114b include cutting edges 126 and 128 that function as outer peripheral cutting edges and cutting edges 130 and 132 that function as bottom edges, respectively. Although illustration is omitted, the cutting edges 126, 128, 130, etc. are formed on the surface of the tool base made of cemented carbide, as in FIG. 1 (b) or FIG. 7 (a). 132 is coated with a diamond coating, and at least one of the flank side and the rake face side of the cutting edges 126, 128, 130, 132 of these cutting edges 126, 128, 130, 132 is etched by ion beam. A chamfer is provided by polishing the coating. The diamond coating is composed of microcrystalline diamond having a crystal grain size of about 1 μm, like the diamond coating 22 of the above embodiment, and is formed by the microwave plasma CVD apparatus 50 or the like.

  In the throw-away end mill 100 to which such throw-away tips 114a and 114b or the throw-away tips 114a and 114b are attached, the diamond film is composed of microcrystalline diamond having a crystal grain size of about 1 μm. Even when a chamfer is provided by etching with a beam, the surface of the chamfer is relatively smooth, and the same operational effects as in the above embodiment can be obtained, such as excellent cutting performance can be obtained in combination with sharpening of the blade edge. .

  It is not always necessary to provide chamfers on all the cutting edges 126, 128, 130, 132. For example, chamfers may be provided only on the cutting edges 126 and 128 that function as outer peripheral cutting edges.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one embodiment to the last, and this invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the end mill (diamond covering cutting member) which is one Example of this invention, (a) is the front view seen from the direction orthogonal to an axial center, (b) is an enlarged view of the blade perpendicular cross section of an outer periphery cutting edge. It is. It is a figure explaining the front-end | tip roundness diameter R of the blade edge | tip of a cutting blade. It is a figure explaining the manufacturing process of the Example of FIG. It is a schematic block diagram explaining an example of the microwave plasma CVD apparatus suitably used when coating a microcrystal diamond film by (a) of FIG. It is a flowchart explaining the procedure at the time of coating a microcrystal diamond film using the apparatus of FIG. It is a schematic block diagram explaining an example of the ion beam etching apparatus used suitably when performing ion beam etching by (c) of FIG. In the end mill of FIG. 1, it is a figure explaining the Example at the time of providing a chamfer on both the flank side and the rake face side. It is a figure explaining the result of having investigated cutting resistance by cutting to an aluminum alloy using the product of the present invention and a comparative product. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the throwaway type end mill to which this invention was applied, (a) is a front view seen from the direction perpendicular to the shaft center, (b) is a bottom view, and (c) is a right side view of (a). It is. Cross-sectional view perpendicular to the blade explaining the surface shape when a chamfer is provided by etching with an ion beam on an ordinary polycrystalline diamond coating, (a) is a state in which the polycrystalline diamond coating is coated, and (b) is an ion beam. This is a state after the chamfer is provided by etching.

Explanation of symbols

  10, 100: End mill (diamond-coated cutting member, diamond-coated rotary cutting tool) 16, 60: Peripheral cutting edge (cutting edge) 22: Diamond coating 30, 62: Champha 114a, 114b: Throw away tip (diamond-coated cutting member) 126, 128, 130, 132: Cutting edge

Claims (7)

In a diamond-coated cutting member such as a throw-away tip or a cutting tool whose surface is coated with a diamond coating,
The diamond coating is composed of microcrystalline diamond having a crystal grain size of 2 μm or less,
A diamond-coated cutting characterized in that a chamfer is provided on at least one of the rake face side and the flank face side of the cutting edge by polishing the diamond film by ion beam etching. Element. By providing the chamfer, the tip edge roundness radius R represented by the radius of the inscribed circle S in contact with the tip position Q of the chamfer in the cross section perpendicular to the edge is 10 μm or less. Item 2. The diamond-coated cutting member according to Item 1. The tip roundness radius R is set to 1 μm or less by providing the chamfer by etching with the ion beam on both the flank face side and the rake face side of the cutting edge. Diamond coated cutting member. The diamond-coated cutting member is a diamond-coated rotary cutting tool that performs cutting with an outer peripheral cutting edge by being driven to rotate around an axis,
The chamfer is provided on at least the flank side of the outer peripheral cutting edge, and the width dimension of the chamfer provided on the flank side in the cross section perpendicular to the blade is 0.2 × D or less with respect to the tool diameter D. The diamond-coated cutting member according to any one of claims 1 to 3, wherein the diamond-coated cutting member is provided. The diamond-coated cutting member is a diamond-coated rotary cutting tool that performs cutting with an outer peripheral cutting edge by being driven to rotate around an axis,
The outer peripheral cutting edge is provided integrally with the tool base,
The diamond-coated cutting member according to any one of claims 1 to 4, wherein the chamfer is provided by etching with the ion beam on both the flank face side and the rake face side of the outer peripheral cutting edge. . The diamond-coated cutting member according to any one of claims 1 to 3, wherein the diamond-coated cutting member is a throw-away tip that is used detachably attached to a tool body configured separately. Cutting member. A method for producing a diamond-coated cutting member in which a surface of a cutting edge is coated with a diamond coating,
A microcrystalline diamond coating step of coating the diamond film by repeatedly producing microcrystalline diamond having a crystal grain size of 2 μm or less by vapor phase growth;
Ion beam etching in which at least one of the rake face side and the flank face side of the cutting edge provided with the diamond coating is etched by an ion beam to polish the diamond coating and provide a chamfer. Process,
A method for producing a diamond-coated cutting member, comprising:

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