JP5247259B2 - Single crystal diamond cutting tool - Google Patents

Description

  The present invention relates to a cutting tool for ultraprecision machining in which a cutting edge is formed on diamond, and more particularly, to a single crystal diamond cutting tool for performing ultraprecision machining of a micropattern such as a diffraction grating, μ-TAS, and MEMS.

  Conventionally, semiconductor manufacturing techniques such as a photolithography method and an ion beam method have been mainly used for micropattern processing necessary for μ-TAS, MEMS, and the like, and microgroove processing of a diffraction pattern of a diffraction grating. However, the manufacturing equipment is expensive and the material to be processed is limited to silicon, etc., and the cost is high. Due to the characteristics of the processing method, smooth curved surfaces and sharp edges cannot be obtained. Instead of processing, various materials have been processed by cutting with a diamond tool.

  On the other hand, with respect to diffraction gratings, there is a demand for processing a diffraction pattern with a fine groove width of 2 μm or less in order to cope with a short wavelength laser for blue-violet and blue lasers such as Blu-ray disc as a next generation DVD. In diffraction pattern processing, cutting was conventionally performed in many cases. However, the width of 5 μm is the limit due to the problem of cutting edge strength of cutting tools. (Hereinafter, a width of 5 μm or less is referred to as a “micro width” in the present application). In order to perform such processing, an expensive apparatus is required, and there is a problem that the end of the processed groove is rounded.

  In such a field, machining freedom and cost reduction are issues, and for that purpose, it is easy to use cutting technology, and various high-precision materials can be freely and precisely used using cutting technology. There is an increasing demand for processing.

  As a cutting tool for processing a fine groove of a diffraction grating, it is conceivable to use a tool as described in Patent Document 1, for example. This tool is provided with a square bar-shaped cutting edge at the tip of a single crystal diamond tip, and is used as an end mill. If this tool is used, a linear groove with a fine width can be formed. However, in this document, the width of the cutting edge is only exemplified as 20 to 40 μm. It is not mentioned until. (For example, see Patent Document 1)

JP 2004-148471 A

  In order to meet the demand for cutting a groove having a micro width as described above, particularly a width of 2 μm or less, it is conceivable to make a tool with a cutting edge width of 2 μm or less described in Patent Document 1. However, such a tool having a very fine cutting edge has problems in both use and production, and it is difficult to produce a tool with a very small cutting edge described in Patent Document 1. Even if it can be manufactured, problems in use occur.

  As a problem in use, there is a problem of insufficient strength of the cutting edge portion. In the case where the cutting edge portion is formed in a square bar shape and a cutting edge having a very small width is formed, the cutting edge portion is very easily chipped or broken due to cutting resistance. Further, as a manufacturing problem, in order to form a cutting edge having a very small width, it is necessary to improve the accuracy of the surface on which the cutting edge is formed more than before. For that purpose, it is possible to polish using loose abrasive grains and a Skyf machine, or to process using a laser beam or a focused ion beam, but because the cutting edge is fine and the strength is low, polishing is not possible. It is not easy, and high-precision processing is not easy with a laser beam. Further, although it is possible to manufacture by processing with a focused ion beam, there is a point that it is difficult to form a precise cutting edge because the edge is likely to sag. Whichever method is used, there remains a problem in use that the strength of the cutting edge is insufficient as described above.

  In order to solve the problem in use, the strength of the cutting edge is improved. As a countermeasure, it is conceivable to increase the thickness in the direction perpendicular to the rake face. When the thickness is increased in this way, the problem in use is greatly reduced, but a problem in production newly arises. This is because the rake face has a very small width and a large flank face, and the following problems tend to occur when the flank face is processed. First, when processing is performed by polishing, the polishing surface becomes wide and resistance increases. However, since the rake surface has a very small width, the cutting edge portion is easily broken during polishing processing of the flank surface. Therefore, it is extremely difficult to adjust the polishing pressure, and even if it can be done, it takes a very long time. Next, when processing is performed using a focused ion beam, the processing time and cost are significantly increased because the processing surface is wide.

  In view of the above, the present inventors have studied a tool having a shape that can satisfy the requirements in terms of both use and production, and have reached the present invention. That is, the present invention provides a single crystal diamond cutting tool having a cutting edge having a shape that is less likely to be chipped or broken during use even when it is a minute width cutting edge, and is less likely to be chipped or broken during manufacture. It is.

A first feature of the single crystal diamond cutting tool of the present invention is a single crystal diamond cutting tool for grooving having a single crystal diamond tip formed with a cutting edge having a width of 5 μm or less at the tip,
At least a portion of the rake face and the flank face on which the cutting edge is formed is a flat plate shape, and one of the planes in the thickness direction of the flat plate shape is a rake face,
The cutting edge includes a front cutting edge formed at a boundary portion between the rake face and a front flank surface, and two side cutting edges formed at a boundary portion between the rake face and the two first flank faces. ,
The ridgeline of the cutting edge is a U-shape in which the front cutting edge and the two horizontal cutting edges are continuous,
The height t of the flank (in the direction perpendicular to the rake face) is at least twice the width w of the U-shaped cutting edge.
Of the flank face of the portion where the cutting edge is formed, at least the surface roughness of the end region opposite to the rake face is 3 to 100 nm in terms of PV value.

  When forming a U-shaped cutting edge, the cutting edge is made flat and the height t of the flank is set to be twice or more the width w of the cutting edge. It becomes strong against resistance and can prevent chipping or breakage of the cutting edge. Further, by reducing the surface roughness of the end region on the side opposite to the rake face of the flank, cracks and the like are less likely to occur from the end region during cutting, and the strength of the cutting edge portion can be further improved. In the case of a fine cutting edge as in the present application, it is necessary to remove a cause that influences a decrease in strength not only around the cutting edge but also over the entire flank.

  The second feature is that a second flank surface comprising a concave curved surface smoothly connected to the first flank surface is formed on the rear end side of the first flank surface.

  By adopting such a shape, the strength for supporting the cutting edge portion in the portion on the rear end side from the cutting edge portion is improved, and the effect of preventing chipping or breakage of the cutting edge portion becomes higher.

  A third feature is that the rear flank side of the second flank has a larger flank angle than the first flank, and is formed with an angle with the rear end of the second flank. That is, the third flank is formed.

  By using such a shape, the cutting edge portion can be formed by grinding the rake face and the third flank, and only the first and second flank are processed by a focused ion beam or the like. Therefore, the processing time can be shortened and the processing cost can be reduced.

  A fourth feature is that the lower end portion of the first flank has a larger flank angle than the first flank and is flush with the third flank when the rake face is the upper surface. A flank is formed, and the unevenness of the ridgeline at the lower end of the fourth flank is 300 nm or less.

  By adopting such a shape, the fourth flank can be formed together with the third flank by polishing, and the ridge line at the lower end of the fourth flank is formed by polishing. In addition, since the clearance angle of the fourth flank is much larger than the clearance angle of the first flank, the angle of the ridgeline formed at the lower end of the fourth flank is larger, and the unevenness formed on the ridgeline It becomes easy to control the size of. Therefore, it becomes easy to reduce the unevenness of the ridgeline at the lower end portion of the fourth flank as in the present invention, and there is a risk of cracking from the lower end portion of the fourth flank when a cutting resistance is applied to the cutting edge. Since it becomes small, chipping and breakage of the cutting edge can be prevented.

  A fifth feature is that a ridge line at the lower end of the fourth flank is rounded, and the size of the round is a radius of 100 nm or less in a cross section in the vertical direction of the ridge line.

  By forming such a roundness, the possibility of cracking from the lower end portion of the fourth flank becomes smaller, so that chipping or breakage of the cutting edge portion can be prevented.

  A sixth feature is that the clearance angle of the fourth flank is not less than 15 ° and not more than 45 °.

  By setting such a clearance angle, it becomes easier to control the size of the unevenness formed on the ridgeline, and it becomes easier to reduce the unevenness of the ridgeline at the lower end. For this reason, when the cutting force is applied to the cutting edge, the possibility of cracking from the lower end portion of the fourth flank is reduced, so that chipping or breakage of the cutting edge portion can be prevented.

  In the diamond tool of the present invention, even if the width of the cutting edge is 5 μm or less, especially 2 μm or less, the diamond tool is strong against the cutting resistance applied during the cutting process, and is not easily broken or chipped. In addition, cracks and the like are difficult to enter from the ridge line portion on the side facing the rake face, and the effect of further preventing breakage or chipping of the cutting edge portion is enhanced. Furthermore, when forming the cutting edge, it is only necessary to finish a plane surface by polishing and then process only the flank portion including the curved surface with a focused ion beam. Since the cutting edge portion is not chipped or broken, and the amount processed with the focused ion beam can be reduced, the processing time and cost can be suppressed.

  A first example of the single crystal diamond cutting tool of the present invention is shown in FIG. Moreover, the enlarged view of the cutting edge periphery formed in this tool is shown in FIG.2, FIG3 and FIG.4. 1 is a perspective view of the entire insert attached to the diamond cutting tool, FIG. 2 is an enlarged perspective view of the periphery of the cutting edge when viewed from the same angle as FIG. 1, and FIG. 3 is a view of the periphery of the cutting edge from another angle. It is an expansion perspective view. FIG. 4 is a view showing the periphery of the cutting edge, where (a) is a plan view, (b) is a front view, and (c) is a left side view. FIG. 5 is an enlarged left side view in which the periphery of the cutting edge portion of FIG.

  Referring to FIG. 1, in the single crystal diamond cutting tool of the present invention, an insert 1 is attached to the tip of a tool holder (not shown). The insert 1 has a diamond 2 joined to the tip of a base metal 3 made of cemented carbide or the like, and a mounting hole 4 for mounting on the holder is provided on the rear end, and is attached to the tool holder with a screw or the like. .

  2 and 3, a flat rake face 11 is formed on the upper surface of diamond 2, and a cutting edge having a width of 5 μm or less is formed at the tip. The portion where the cutting edge is formed has a flat plate shape, and one of the flat surfaces in the thickness direction is formed as a rake surface. The cutting edge is formed in a U shape in which the front cutting edge 21 and the two horizontal cutting edges 22 are continuous, and the width of the U-shaped portion is the width w of the cutting edge, and this width w is 5 μm. It is as follows. The front cutting edge 21 is formed at the boundary between the rake face 11 and the front flank 12. Further, one side cutting edge 22 is formed at the boundary between the rake face 1 and one first flank 13a, and the other side edge is formed at the boundary between the rake face 11 and the other first flank 13b. The blade 22 is formed, and in this example, the two side cutting blades 22 are formed substantially in parallel. The rake face 11 and the first flank faces 13a and 13b form a flat cutting edge.

  On the rear end side of the first flank 13b, a second flank 14 that is smoothly connected to the first flank 13b and formed of a concave curved surface is provided. Further, on the further rear end side of the second flank 14, a third flank is formed with a flank angle larger than that of the first flank 13 b and having an angle with the rear end portion of the second flank 14. 15 is provided. The third flank 15 is a flat surface. Furthermore, when the rake face 11 is the upper surface, the fourth flank 16 has a larger flank angle than the first flank 13 b and is flush with the third flank 15 at the lower end side of the first flank 13 b. Is provided. A ridge line 23 is formed at the lower end of the fourth flank 16.

  As described above, the second flank 14, the third flank 15 and the fourth flank 16 are provided on the side where the first flank 13b is provided, but the side where the first flank 13a is provided is flat. Only the first flank 13a is provided, and no other surface is provided. Therefore, the ridge line 23 is continuously formed at the boundary between the first flank 13 a and the fourth flank 16 and the boundary between the first flank 13 a and the third flank 15.

  Referring to FIG. 4, the height t of the cutting edge portion in the height direction (direction perpendicular to the rake face) is at least twice the width w of the U-shaped cutting edge. In addition, since this magnitude | size t is not necessarily a constant magnitude | size over the whole cutting-blade part, it is so that the smallest part among cutting-blade parts may become 2 times or more of the width w of a U-shaped cutting edge. Form. Further, a clearance angle α is provided on the tip flank 12 and is retracted to the rear end side. However, this retracted portion is not included in the height t of the flank. . That is, the size t in the height direction of the flank face of the cutting edge portion is the smallest size among the sizes from the rake face 11 to the ridge line 23. The clearance angle α of the tip flank 12 is preferably 1 to 10 ° from the viewpoint of securing the strength of the cutting edge. Further, the clearance angle β of the first flank surfaces 13a and 13b is preferably set to 0 ° 30 ′ to 5 ° from the viewpoint of securing the strength of the cutting edge portion.

  Of the flank of the portion where the cutting edge is formed, that is, the first flank 13a, the first flank 13b and the fourth flank 16, at least the end region opposite to the rake surface 11, that is, the surface in the vicinity of the ridge line 23 The roughness is 3 to 100 nm in terms of PV value. By using such a surface with a very small surface roughness, the unevenness of the ridge line 23 can be reduced, and cracks and the like can be prevented from being generated from the ridge line 23 during the cutting process.

  As described in the above-mentioned 0028, the ridge line 23 is continuously formed on the boundary between the first flank 13a and the fourth flank 16 and the boundary between the first flank 13a and the third flank 15. The unevenness of the ridge line 23 is 300 nm or less. In this way, the effect of preventing cracks from occurring on the ridge line 23 is enhanced. Although FIG. 5 is described with emphasis on the unevenness of the ridge line 23 for the sake of explanation, since the uneven shape is not a fixed shape, the size h of the unevenness is the most recessed portion and the most protruding portion. The width represents the width when viewed from the direction parallel to the rake face 11, that is, the width of the unevenness in the direction of viewing the left side.

  The ridge line 23 is rounded. The roundness is formed so that the radius of the roundness is 100 nm or less when a cross section perpendicular to the ridge line 23 is viewed. By making the size round like this, the strength of the cutting edge portion formed with a cutting edge having a width of 5 μm or less can be further improved.

  The clearance angle of the fourth flank 16 is 15 to 45 °. Since the fourth flank 16 and the third flank 15 are coplanar, the flank angle of the third flank 15 is also the same. The clearance angle of the third flank 15 is an angle formed by the rake face 11 and the third flank 15 in the AA cross section shown in FIG. With such an angle, the angle of the portion forming the ridge line 23 is increased. Therefore, when the first flank 13a, the third flank 15 and the fourth flank 16 are polished to form the ridge line 23, it becomes easy to control the size of the ridge line 23 unevenness. The size can be reduced. Therefore, it is possible to prevent the ridgeline 23 from being cracked, and it is easy to form a cutting edge portion having high strength.

  A ridge line 24 is provided at the boundary between the rake face 11 and the third flank 15. The angle of the ridge line 24 is determined by the angle at which the third flank 15 is provided. If the third flank 15 is formed so that the angle δ formed by the ridge line 24 and the side cutting edge 22 is increased, the ridge line 23 at the lower end is formed. It becomes easy to increase the angle of the portion that forms the edge, and the strength of the cutting edge portion can be improved. From such a point, it is preferable that the angle δ formed by the ridge line 24 and the side cutting edge 22 is 20 to 45 °.

  A second example of the single crystal diamond cutting tool of the present invention is shown in FIG. This shape is basically the same as that of the first example, but the height t of the flank face of the cutting edge is very large with respect to the width w of the U-shaped cutting edge. It is a big one. With such a shape, the strength of the cutting edge portion is further increased, and cracks can be prevented from occurring from the ridge line 23.

  FIG. 7 shows a third example of the single crystal diamond cutting tool of the present invention. The shape of the second flank 14, the third flank 15 and the fourth flank 16 in the first example is not limited to the side where the first flank 13b is provided, but the first flank 13a It is also provided on the side where it is provided. Accordingly, the second flank 14, the third flank 15, and the fourth flank 16 are provided two each, and the ridge line is formed on the boundary between the two third flank 15 and the boundary between the two fourth flank 16. 23 is provided.

  With such a shape, the angle formed by the ridge line 24 and the ridge line 25 provided at the boundary between the rake face 11 and the two third flank faces 15 can be made larger than that of the first example. Thereby, since the angle of the part which forms the ridgeline 23 can be enlarged, when the 3rd flank 15 and the 4th flank 16 are grind | polished and the ridgeline 23 is formed, the magnitude | size of the unevenness | corrugation of the ridgeline 23 is controlled. Becomes easy and the size of the unevenness can be reduced. Therefore, it is possible to prevent the ridgeline 23 from being cracked, and it is easy to form a cutting edge portion having high strength.

It is a figure which shows the example of the insert attached to the single crystal diamond cutting tool of this invention. It is an expansion perspective view which shows the 1st example of the shape around the cutting-blade of the single crystal diamond cutting tool of this invention. It is an expansion perspective view which shows the 1st example of the shape around the cutting-blade of the single crystal diamond cutting tool of this invention. It is a figure which shows the 1st example of the shape of the cutting-blade periphery of the single crystal diamond cutting tool of this invention, (a) is a top view, (b) is a front view, (c) is a left view. It is the figure which expanded the cutting blade part periphery of FIG.4 (c). It is an expansion perspective view which shows the 2nd example of the shape around the cutting-blade of the single crystal diamond cutting tool of this invention. It is an expansion perspective view which shows the 3rd example of the shape around the cutting-blade of the single crystal diamond cutting tool of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert 2 Diamond 3 Base metal 4 Mounting hole 11 Rake face 12 Front flank 13a, 13b 1st flank 14 Second flank 15 3rd flank 16 4th flank 21 Front cutting edge 22 Side cutting edge 23 Ridge line 24 Ridge line 25 ridgeline

Claims (4)

A single crystal diamond cutting tool for grooving having a single crystal diamond having a cutting edge with a width of 5 μm or less formed at the tip,
At least a portion of the rake face and the flank face on which the cutting edge is formed is a flat plate shape, and one of the planes in the thickness direction of the flat plate shape is a rake face,
The cutting edge includes a front cutting edge formed at a boundary portion between the rake face and a front flank surface, and two side cutting edges formed at a boundary portion between the rake face and the two first flank faces. ,
The ridgeline of the cutting edge is a U-shape in which the front cutting edge and the two horizontal cutting edges are continuous,
The height t of the flank (in the direction perpendicular to the rake face) is at least twice the width w of the U-shaped cutting edge.
Of flank portions where the cutting edge is formed, the surface roughness of the end region of at least the rake face opposite to, Ri 3~100nm der in PV value,
On the rear end side of the first flank, a second flank that is smoothly connected to the first flank and is formed of a concave curved surface is formed.
On the rear end side of the second flank, a flank angle is larger than that of the first flank and is formed at a certain angle with the rear end of the second flank, thereby forming a third flank that is a flat surface. A single crystal diamond cutting tool characterized by being made .   When the rake face is the top surface, a lower flank of the first flank is formed with a fourth flank that has a larger flank angle than the first flank and is flush with the third flank, 2. The single crystal diamond cutting tool according to claim 1, wherein the unevenness of the ridgeline at the lower end of the fourth flank is 300 nm or less. The ridgeline part of the lower end part of the fourth flank is rounded, and the size of the roundness is a radius of 100 nm or less in a vertical section of the ridgeline. Crystal diamond cutting tool. The single crystal diamond cutting tool according to claim 3, wherein the clearance angle of the fourth flank is not less than 15 ° and not more than 45 °.

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