JP5279561B2 - Single crystal diamond tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide further excellent machining accuracy when highly accurate machining such as mirror finishing is performed by a dry method by using a single crystal diamond tool. <P>SOLUTION: A plurality of annular grooves 30 as grooves for heat radiation are provided on an outer peripheral surface of a body 12, and thereby a temperature rise of the body 12 due to heating generated in cutting edges 24 and 26 and a rake face 22, etc. during cutting and further thermal expansion of the body 12 according to the temperature rise are suppressed. As a result, position changes of cutting edges 24 and 26 of the single crystal diamond 14 caused by the thermal expansion of the body 12, that is, displacement to an axial direction distal end side is suppressed, to obtain further excellent machining accuracy, even when the highly accurate machining such as mirror finishing is performed by the dry method. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a single crystal diamond tool, and more particularly to a technique for obtaining a further excellent machining accuracy when performing a high precision machining such as a mirror finish in a dry method.

  Single crystal diamond tools, such as a single crystal diamond end mill and a single crystal diamond tool, in which single crystal diamond having a cutting edge is integrally fixed to a cemented carbide body and cutting is performed with the cutting edge have been proposed ( (See Patent Documents 1 and 2).

JP 2004-148471 A JP 2006-35359 A

  Such a single crystal diamond tool is suitably used for high precision machining such as mirror finish by being fast-fed with a small depth of cut (for example, several μm), and cutting oil is used in such high precision machining. It is often used dry. In that case, as shown in FIG. 2, the thermal conductivity of diamond is about 5, whereas the thermal conductivity of the cemented carbide constituting the body is as small as about 0.08 to 0.29. The heat generated on the surface of the single crystal diamond that is easy to cut during the cutting process is quickly transferred to the body, and is accumulated in the body to increase the temperature. The thermal expansion coefficient of cemented carbide is about 5.1 to 7.6, and even if the body expands as the temperature rises, there is almost no problem if it is normal processing. In high-precision machining, the machining accuracy may be affected by a slight change in the position of the cutting edge of the single crystal diamond due to the thermal expansion of the body.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to obtain even higher processing accuracy when performing high-precision processing such as mirror finish in a dry process using a single crystal diamond tool. There is in doing so.

  In order to achieve such an object, the first invention provides a single crystal diamond tool in which a single crystal diamond having a cutting edge is integrally fixed to a cemented carbide body, and cutting is performed by the cutting edge. A heat dissipation groove is provided on the outer peripheral surface of the slab.

  A second invention is the single crystal diamond tool according to the first invention, wherein (a) the body includes a shank that is rotationally driven around an axis O and a diamond attachment portion on which the single crystal diamond is integrally fixed. (B) The heat radiating groove is an annular groove provided on the outer peripheral surface of the shank at a right angle to the axis O on the entire circumference.

  According to a third aspect of the present invention, in the single crystal diamond tool of the second aspect, a plurality of the annular grooves are provided at predetermined intervals in the axial direction of the shank.

  4th invention is the single crystal diamond tool of 2nd invention or 3rd invention, (a) The groove depth and groove width of the said annular groove are all in the range of 0.3 mm-1.0 mm, (b The annular groove is provided within a range of 20 mm or less from the tip of the body.

  In such a single crystal diamond tool, since a heat radiating groove is provided on the outer peripheral surface of the body, the temperature of the body rises due to heat generated on a surface that is easy to cut during cutting, and further, the temperature rises. The thermal expansion of the body accompanying the is suppressed. Thereby, even when performing high precision processing such as mirror finish by dry processing, the position change of the cutting edge of the single crystal diamond due to the thermal expansion of the body is suppressed, so that further excellent processing accuracy can be obtained. In addition, when the temperature rise of the body is suppressed in this way, the temperature rise of the single crystal diamond itself is also reduced, so that the lifetime reduction due to graphitization is suppressed.

  The second invention relates to a single crystal diamond end mill, and an annular groove provided at a right angle to the axis O on the outer peripheral surface of the shank is used as a heat radiating groove, so that the shank is rotationally driven around the axis O. At the same time, the air in the annular groove is exchanged well to obtain excellent heat dissipation performance, and the temperature rise of the body is effectively suppressed.

  In the third invention, since the plurality of the annular grooves are provided at predetermined intervals in the axial direction of the shank, the heat dissipation performance is further improved and the temperature rise of the body is further effectively suppressed.

  In the fourth aspect of the invention, since the groove depth and groove width of the annular groove are both in the range of 0.3 mm to 1.0 mm, predetermined heat dissipation performance can be obtained while maintaining the rigidity and strength of the shank. That is, a single crystal diamond end mill generally has a small diameter of the cutting edge (outer peripheral edge) of about 3 mm or less, a shank diameter larger than that, and a small cutting amount so that the cutting load is small, and the annular groove If the groove depth and groove width are 1.0 mm or less, the rigidity and strength of the shank are hardly affected. In addition, since the annular groove is provided within a range of 20 mm or less from the tip of the body, the heat transferred from the single crystal diamond to the body is well dissipated by the annular groove, and the single crystal diamond caused by the thermal expansion of the body The position change of the cutting edge and the temperature rise of the single crystal diamond itself are further effectively suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the single crystal diamond end mill which is one Example of this invention, (a) is the top view seen from the axial center O, (b) is an enlarged view of the front-end | tip part in which the single crystal diamond was provided. is there. It is a figure which shows the thermal conductivity of a diamond and a cemented carbide, and a thermal expansion coefficient.

  The single crystal diamond tool of the present invention is suitably applied to a single crystal diamond end mill or a single crystal diamond tool. The single crystal diamond end mill is preferably applied to a square end mill or a radius end mill having an outer peripheral edge and a bottom edge as a cutting edge, but can also be applied to a ball end mill having a ball edge as a cutting edge.

  The single crystal diamond may be artificial diamond or natural diamond. In the case of an artificial diamond, it is basically a hexahedral shape having six {100} faces (Miller indices), that is, a cube or a rectangular parallelepiped whose adjacent faces are perpendicular to each other. The dispersion of is small, and stable quality can be obtained. The ridgeline of the cubic or rectangular parallelepiped artificial diamond can be used as a cutting edge as it is, and the {100} plane can be used as a rake face. Various modes are possible, such as a surface that is inclined at an angle or another crystal plane may be used as a rake face.

  The single crystal diamond is bonded to the body diamond mounting portion by, for example, brazing with an active metal braze or the like, but can be integrally fixed by mechanical clamping means using screws or the like. Adhesion with active metal brazing produces a film of active metal such as titanium (Ti) or chromium (Cr) on the surface by heating single crystal diamond in a deoxygenated atmosphere (metallized), and silver containing silver and copper The single crystal diamond is directly bonded to the cemented carbide body by brazing.

  Although it is desirable to provide a plurality of heat dissipation grooves, it is sufficient to provide at least one groove. The shape of the heat radiating groove is appropriately determined according to the shape of the body, and various modes are possible such as being provided in parallel to the longitudinal direction of the body or in a direction perpendicular to the longitudinal direction. The cross-sectional shape of the heat radiating groove may be various forms such as a square shape, a V shape, a semicircular arc shape, and a U shape.

  The end mill body of the second invention may be provided with a diamond attachment portion directly at the tip of the cylindrical shank, but with a diamond attachment portion provided at the tip via a taper portion or the like whose diameter is gradually reduced. Also good. The annular groove as the heat radiating groove can be provided in a cylindrical portion, or can be provided in a portion where the diameter dimension is gradually reduced, such as a tapered portion.

  The groove depth and groove width of the heat dissipating groove are preferably set within a range of, for example, about 0.3 mm to 1.0 mm. However, depending on the size of the body, the groove depth and groove width exceed 1.0 mm. It is also possible to form a heat dissipation groove. When an annular groove is provided as a heat dissipation groove in a single crystal diamond end mill, it is desirable to set the groove depth so that the groove bottom diameter is equal to or larger than the diameter of the outer peripheral edge of the single crystal diamond.

  In the fourth invention, the annular groove is provided within a range of 20 mm or less from the front end of the body. However, it is sufficient that at least one annular groove is provided within a range of 20 mm or less, and the annular groove is provided up to a position exceeding 20 mm. It is also possible. Moreover, it is desirable to provide it as close to the single crystal diamond as possible, such as 10 mm or less from the tip of the body.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams showing a single crystal diamond end mill 10 according to an embodiment of the present invention, in which FIG. 1A is a plan view seen from a direction perpendicular to an axis O, and FIG. 1B is an enlarged view of a tool tip portion. . This single crystal diamond end mill 10 includes a cemented carbide shaft-shaped body 12 and a single crystal diamond 14 integrally fixed to the tip of the body 12. The body 12 has a diamond mounting portion 18 provided concentrically and integrally at the tip of a cylindrical shank 16, and a mounting seat 20 formed by polishing and removing a part of the cylindrical diamond mounting portion 18. The single crystal diamond 14 is integrally bonded (fixed) by brazing with an active metal braze or the like. The shank 16 has a diameter (shank diameter) D of about 4 mm, and a tapered portion 16t having a smaller diameter toward the distal end is provided at the distal end, and a diamond mounting portion 18 is provided at the distal end of the tapered portion 16t. Yes.

  The single crystal diamond 14 is a rectangular parallelepiped artificial diamond provided so as to protrude from the tip of the diamond mounting portion 18 by a predetermined dimension, and the shank 16 is gripped by the spindle of the machine tool and rotated around the axis O. Thus, cutting is performed at the protruding portion. In the single crystal diamond 14, for example, one of the {100} faces constituting the outer peripheral surface is used as the rake face 22 as it is, and one side edge of the rake face 22 functions as the outer peripheral blade 24. The front edge of 22 functions as the bottom blade 26, and is used as a square end mill. An escape 28 is provided in a portion opposite to the bottom blade 26 across the axis O to avoid interference. The outer peripheral blade 24 and the bottom blade 26 are provided with relief as required. The outer peripheral edge 24 and the bottom edge 26 correspond to cutting edges, and the diameter of the outer peripheral edge 24 is a small diameter of 3 mm or less, and is about 1 mm in this embodiment. In addition, the dimension of each part in FIG. 1 is not necessarily shown in an exact ratio.

  Here, such a single crystal diamond end mill 10 is suitably used when performing high-precision processing such as mirror finish by being fast-forwarded with a small depth of cut (for example, several μm). In such high-precision processing, It is often used in a dry method that does not use cutting fluid. In this case, as shown in FIG. 2, the thermal conductivity of diamond is about 5, whereas the thermal conductivity of the cemented carbide forming the body 12 is as small as about 0.08 to 0.29. The heat generated on the cutting surfaces 24, 26 of the single crystal diamond 14 during the cutting process is quickly transferred to the body 12, and is accumulated in the body 12 to increase the temperature. Cemented carbide has a thermal expansion coefficient of about 5.1 to 7.6, and even if the body 12 expands as the temperature rises, there is almost no problem with normal processing, but high-precision processing such as mirror finishing. Then, the processing accuracy may be affected by a slight change in the position of the cutting edges 24 and 26 of the single crystal diamond 14 due to the thermal expansion of the body 12 (mainly displacement toward the tip end in the axial direction). In order to prevent this, the single crystal diamond end mill 10 of the present embodiment is provided with a large number of annular grooves 30 on the outer peripheral surface of the tip of the shank 16 as heat radiating grooves.

  The annular groove 30 is provided by grinding with a grindstone or the like at the tip portion of the cylindrical portion of the shank 16, that is, the portion immediately behind the tapered portion 16t, and the cross-sectional shape thereof is a substantially rectangular square, and the axis O Are provided at right angles to the entire circumference of the shank 16, and five are provided in the axial direction of the shank 16 with a predetermined interval w2. The groove depth d of the annular groove 30 is in the range of 0.3 mm to 1.0 mm, and is about 0.5 mm in this embodiment, and the groove bottom diameter is about 3 mm. The groove width w1 of the annular groove 30 is in the range of 0.3 mm to 1.0 mm, about 0.5 mm in this embodiment, and the interval w2 is also in the range of 0.3 mm to 1.0 mm. About 0.5 mm. The annular groove 30 on the most distal side has a dimension Lg from the tip of the body 12 of 20 mm or less, and is provided in the vicinity of the dimension Lg of about 8 mm in this embodiment, and is within a range of about 4.5 mm therefrom, that is, A total of five annular grooves 30 are provided at equal intervals within a range from the tip of the body 12 to about 12.5 mm. Such an annular groove 30 can be provided in the tapered portion 16t.

  As described above, the single crystal diamond end mill 10 of the present embodiment is provided with the annular groove 30 as the heat radiating groove on the outer peripheral surface of the body 12, so that the cutting edges 24 and 26 are easy to cut during the cutting process. The temperature rise of the body 12 due to the heat generated in the body, and the thermal expansion of the body 12 accompanying the temperature rise are suppressed. As a result, even when high precision machining such as mirror finishing is performed by dry processing, the positional change of the cutting edges 24 and 26 of the single crystal diamond 14 due to the thermal expansion of the body 12, that is, the displacement toward the tip side in the axial direction is suppressed. As a result, even better processing accuracy can be obtained. In addition, when the temperature increase of the body 12 is suppressed in this way, the temperature increase of the single crystal diamond 14 itself is also reduced, so that the lifetime reduction due to graphitization is suppressed.

  Further, in the present embodiment, the annular groove 30 provided at a right angle to the axis O on the outer peripheral surface of the shank 16 is used as a heat radiating groove. Therefore, when the shank 16 is driven to rotate around the axis O, the annular groove 30 is annular. The air in the groove 30 is satisfactorily replaced to obtain excellent heat dissipation performance, and the temperature rise of the body 12 is effectively suppressed.

  Further, in the present embodiment, since the plurality of annular grooves 30 are provided in the axial direction of the shank 16 with a predetermined interval w2, the heat dissipation performance is further improved and the temperature rise of the body 12 is further effectively suppressed. .

  In the present embodiment, the groove depth d and the groove width w1 of the annular groove 30 are both within the range of 0.3 mm to 1.0 mm and are approximately 0.5 mm in the present embodiment. In addition, a predetermined heat dissipation performance can be obtained while maintaining the strength. That is, the single crystal diamond end mill 10 of the present embodiment has a small diameter of the outer peripheral blade 24 of about 1 mm, the shank diameter D (about 4 mm in the embodiment) is sufficiently larger than that, and is used with a small depth of cut. Therefore, if the cutting load is small and the groove depth d and the groove width w1 of the annular groove 30 are 0.5 mm, the rigidity and strength of the shank 16 are hardly affected.

  Further, since the annular groove 30 is provided within a range of 20 mm or less from the front end of the body 12, in the embodiment, within a range of about 8 mm to 12.5 mm, the heat transferred from the single crystal diamond 14 to the body 12 is transmitted. Heat is dissipated satisfactorily by the annular groove 30, and the position change of the cutting edges 24 and 26 of the single crystal diamond 14 and the temperature rise of the single crystal diamond 14 itself due to the thermal expansion of the body 12 are further effectively suppressed.

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

  10: Single crystal diamond end mill (single crystal diamond tool) 12: Body 14: Single crystal diamond 16: Shank 18: Diamond mounting portion 24: Outer peripheral edge (cutting edge) 26: Bottom edge (cutting edge) 30: Annular groove (heat dissipation) Groove: O: axial center w1: groove width w2: spacing between annular grooves d: groove depth

Claims (4)

In a single crystal diamond tool in which a single crystal diamond having a cutting edge is integrally fixed to a cemented carbide body, and cutting is performed by the cutting edge,
A single crystal diamond tool, wherein a heat radiating groove is provided on an outer peripheral surface of the body. The body is for an end mill that integrally includes a shank that is rotationally driven around an axis O and a diamond mounting portion on which the single crystal diamond is integrally fixed.
2. The single crystal diamond tool according to claim 1, wherein the heat radiating groove is an annular groove provided on the outer peripheral surface of the shank at a right angle with respect to the axis O on the entire circumference. The single crystal diamond tool according to claim 2, wherein a plurality of the annular grooves are provided at predetermined intervals in the axial direction of the shank. The groove depth and groove width of the annular groove are both in the range of 0.3 mm to 1.0 mm,
The single crystal diamond tool according to claim 2 or 3, wherein the annular groove is provided within a range of 20 mm or less from the tip of the body.

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