JP3161423U - Grinding tool - Google Patents

Abstract

An object of the present invention is to provide a grinding tool capable of performing fine grinding on an ultraprecision mold and an ultraprecision part. In a grinding tool including a base metal 12 and a polycrystalline sintered diamond layer 13 joined to the tip of the base metal 12, the polycrystalline sintered diamond layer 13 is joined to the base metal 12. The main body part 14, the projecting part 15 projecting forward from the front end of the main body part 14, the hemispherical part 16 formed hemispherically at the front end of the projecting part 15 by electric discharge machining, and the hemispherical part 16 at the time of electric discharge machining of the hemispherical part 16 And a hemispherical blade portion 20 for grinding a work material. [Effects] It is possible to grind cemented carbide and finely grind ultra-precision molds and ultra-precision parts. [Selection] Figure 2

Description

  The present invention relates to an improvement of a grinding tool.

  Conventionally, as a grinding tool, a ball end mill having a blade portion made of a cBN (cubic boron nitride) sintered body has been widely used in practice. Although this cBN sintered body is suitable for grinding a high hardness steel, there is a problem in that it is worn away immediately when the work material is a cemented carbide. However, in recent years, there has been an increasing demand for grinding cemented carbide, and a ball end mill that can meet this demand has been proposed (see, for example, Patent Document 1 (FIG. 1)).

Patent document 1 is demonstrated based on the following figure.
FIG. 11 is a diagram for explaining the basic configuration of the prior art. The ball end mill 100 is composed of a polycrystalline sintered diamond layer, and includes a pair of semicircular bottom blades 101 provided at the tip, and a spiral shape. And a pair of outer peripheral blades 102 provided to each other.

  By the way, with the miniaturization and high precision of industrial products, the demand for molds for small super precision parts is increasing. For this reason, a tool for grinding a die is required to have a fine grinding function capable of performing extremely fine grinding and obtaining a more precise finish.

  However, the ball end mill 100 is used for a mold for a general industrial product, and the finished surface roughness of the ground surface ground by the bottom blade 101 is smaller than the machining performance used for blade attachment. There is a limit because it cannot be. That is, it is difficult to finely process an ultraprecision mold or an ultraprecision component using the ball end mill 100.

  Therefore, a grinding technique capable of performing fine grinding on an ultraprecision mold and an ultraprecision part is desired.

JP 2006-88232 A

  This invention makes it a subject to provide the grinding tool which can perform fine grinding with respect to an ultraprecision metal mold | die and an ultraprecision component.

The invention according to claim 1 is a grinding tool comprising a base and a polycrystalline sintered diamond layer joined to the tip of the base,
The polycrystalline sintered diamond layer has a main body joined to the base metal,
A projecting portion projecting forward from the tip of the main body,
A hemispherical portion formed into a hemispherical shape by electric discharge machining at the tip of the protruding portion;
The hemispherical portion comprises a hemispherical blade portion which is a convex portion of diamond particles formed on the surface of the hemispherical portion during electric discharge machining and which grinds the work material.

  The invention according to claim 2 is characterized in that the protruding portion has a cylindrical shape.

  The invention according to claim 3 is characterized in that the protrusion has a conical shape.

  In the invention according to claim 1, the polycrystalline sintered diamond layer is formed in a hemispherical shape at the tip of the projecting portion by electric discharge machining, and a large number is formed on the surface of the hemispherical portion during electric discharge machining of the hemispherical portion. And a hemispherical blade that grinds the work material.

  Since the blade portion is formed by the convex portions of extremely fine diamond particles formed in a spherical shape, the workpiece can be ground more precisely using the blade portion. Further, since the blade portion is a part of the polycrystalline sintered diamond layer, the cemented carbide can be ground.

  As described above, according to the present invention, it is possible to grind cemented carbide, and it is possible to perform fine grinding on an ultraprecision mold and an ultraprecision part.

In the device according to claim 2, the projecting portion has a cylindrical shape.
Since the projecting portion has a cylindrical shape, the projecting portion is less likely to interfere with the work surface even if the tool is tilted with respect to the work surface (with respect to the normal line of the work surface). For this reason, in the hemispherical blade portion, grinding at a position away from the center of the blade portion is facilitated. At a position away from the center of the blade portion, a large contact area between the work surface and the blade portion can be ensured, so that the grinding operation can be performed quickly and the finish of the ground surface is improved.

The invention according to claim 3 is characterized in that the protruding portion has a conical shape.
The shape of the protrusion gradually thickens toward the main body, so the strength of the root of the protrusion (joining portion of the protrusion with the main body) can be increased against the resistance force received from the work material during grinding. .

1 is a perspective view of a grinding tool according to the present invention. It is a perspective view of a polycrystalline sintered diamond layer. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2. FIG. 4 is a view taken in the direction of arrow 4 in FIG. 2. FIG. 5 is an enlarged view of part 5 of FIG. It is sectional drawing of a blade part. It is a perspective view explaining the formation method of a polycrystalline diamond layer. It is principal part sectional drawing of FIG. It is a figure explaining the effect | action of a blade part. It is a figure which shows the example of a change of FIG. It is a figure explaining the conventional ball end mill.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.

An embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the grinding tool 10 is used as a ball end mill, and includes a cylindrical shank 11, a cylindrical base metal 12 joined to the tip of the shank 11, and the base metal 12. And a polycrystalline sintered diamond layer 13 bonded to the tip of the first electrode.

  For example, the overall length L of the grinding tool 10 is 20 to 60 mm, the outer diameter D of the shank 11 is 2 to 6 mm, and the outer diameter d of the base metal 12 and the polycrystalline sintered diamond layer 13 is 0.05 to 2.0 mm. It is.

  The polycrystalline sintered diamond layer 13 is obtained by mixing fine diamond particles with a binder such as Ni or Co and sintering at high temperature and high pressure, and is generally called PCD (Polycrystalline Diamond). Compared to the single crystal diamond layer, the diamond powder is less expensive, so the polycrystalline sintered diamond layer 13 can be manufactured at low cost.

  As shown in FIG. 2, the polycrystalline sintered diamond layer 13 includes a main body portion 14 joined to the base metal 12, a protrusion portion 15 protruding forward from the tip of the main body portion 14, and the protrusion portion 15. A hemispherical portion 16 formed into a hemispherical shape by electric discharge machining at the tip, and a convex portion 17 of diamond particles formed on the surface of the hemispherical portion 16 during the electric discharge machining of the hemispherical portion 16, and the work material is ground Hemispherical blade portion 20.

  The main body portion 14 is provided at the tip of the first taper portion 22 and the columnar joint portion 21 that is a joint portion with the base metal 12, the truncated cone-shaped first taper portion 22 provided at the tip of the joint portion 21. And a second tapered portion 24 that is provided at the tip of the shaft portion 23 and tapers toward the tip.

As shown in FIG. 3, the protrusion 15 has a cylindrical shape.
The blade portion 20 is provided over the entire surface of the hemispherical portion 16. In the figure, the radius of the protrusion 15 is ½ of the radius of the front end surface of the main body 14 (the circular front end surface of the second taper portion 24). The radius R1 of the hemispherical blade 20 (same as the radius of the protrusion 15 or the radius of the hemisphere 16) is, for example, 0.025 to 1.0 mm.

  As shown in FIG. 4, the main body 14 and the protrusion 15 are formed on the same central axis (the central axis 25 of the tool).

  As shown in FIG. 5, the blade portion 20 is composed of a large number of diamond particle convex portions 17. Each convex portion 17 has an irregular shape. Around the convex portion 17, there is a concave portion formed mainly by the binder being removed (removed) during electric discharge machining.

  That is, as shown in FIG. 6, as a result of forming the concave portions 26 and 26 by removing the binder by electric discharge machining, the convex portions 17 are formed by protruding remaining diamond particles. The upper surface and edge of the convex portion 17 made of diamond particles serve as a cutting blade. In addition, when the dimension of the recessed part 26 is illustrated, the depth d1 is 0.5 micrometer and the width w (inner diameter) of a hole is 0.2-20 micrometers.

Next, an example of the method for forming the polycrystalline sintered diamond layer described above will be described.
As shown in FIG. 7, first, from a cylindrical shank 11, a base metal 12 joined to the tip of the shank 11, and a polycrystalline sintered diamond layer 13 joined to the tip of the base metal 12. An intermediate product 30 is prepared. The polycrystalline sintered diamond layer 13 here is not provided with a main body part (FIG. 2, reference numeral 14), a protruding part (FIG. 2, reference numeral 15), and a hemispherical part (FIG. 2, reference numeral 16).

  This intermediate product 30 is placed on a V block 31 and lightly held by a roller 32. The number of V blocks 31 may be one. Next, the collet chuck 33 is connected to the shank 11. The collet chuck 33 is rotated by a servo motor 36 via a rotating shaft 34 and a flexible coupling 35. The flexible coupling 35 has an effect of transmitting a rotational force and has a role of preventing the vibration of the motor shaft of the servo motor 36 from being transmitted to the rotating shaft 34.

For electric discharge machining, a first discharge electrode 37A that faces the outer periphery of the polycrystalline sintered diamond layer 13 and a second discharge electrode 37B that faces the tip of the polycrystalline sintered diamond layer 13 are prepared.
Then, the first discharge electrode 37A is made to face the polycrystalline sintered diamond layer 13, and the polycrystalline sintered diamond layer 13 is subjected to electric discharge machining while being rotated by the servo motor 36. 1 taper part (FIG. 2, code | symbol 22), axial part (FIG. 2, code | symbol 23), 2nd taper part (FIG. 2, code | symbol 24), protrusion part (FIG. 2, code | symbol 15), and hemisphere part (FIG. 2, code | symbol) 16).

  Alternatively, the second discharge electrode 37B faces the tip of the polycrystalline sintered diamond layer 13 in a stationary state, and the first tapered portion (FIG. 2, reference numeral 22) and the shaft portion (FIG. 2, FIG. 2) of the polycrystalline sintered diamond layer 13 Reference numeral 23), a second taper part (FIG. 2, reference numeral 24), a protruding part (FIG. 2, reference numeral 15) and a hemispherical part (FIG. 2, reference numeral 16) are formed.

  During electric discharge machining, the blade portion (FIG. 5, reference numeral 20) is formed by a large number of convex portions (FIG. 5, reference numeral 17) formed on the hemispherical portion (FIG. 5, reference numeral 16), and is formed on the entire surface of the hemispherical portion. It is provided across. That is, by merely subjecting the tip of the polycrystalline sintered diamond layer 13 to hemispherical electric discharge machining, an extremely fine uneven cutting edge can be attached to the protruding portion (FIG. 5, reference numeral 15).

  In addition, the magnitude | size and shape of a convex part (FIG. 6, code | symbol 17) can be adjusted by changing discharge conditions. The required grinding performance of the blade portion can be obtained by adjusting the size and shape of the convex portion (FIG. 6, reference numeral 17). Further, the convex portion (FIG. 6, reference numeral 17) may be provided on the surface of the polycrystalline sintered diamond layer 13 other than the hemispherical portion or on the entire polycrystalline sintered diamond layer 13.

  By the way, the collet chuck 33 grips the shank 11 by bringing the divided pieces to the center. There is inevitably a slight misalignment between the divided pieces. As a result, the shank 11 swings during rotation. As it is, the finishing accuracy of the polycrystalline sintered diamond layer 13 is affected. The countermeasure will be described next.

  As shown in FIG. 8, since the shank 11 is positioned by the V block 31, there is no fear that the intermediate product 30 swings in the direction perpendicular to the axis. Since it is conceivable that the shank 11 is lifted from the V block 31 when the shank 11 is rotated, the roller 32 prevents the lift. Thus, the shank 11 can be rotated without shaking. As a result, each structure of the polycrystalline sintered diamond layer can be determined accurately.

The operation of the grinding tool described above will be described next.
As shown in FIG. 9, the grinding tool 10 is rotated at a high speed of several thousand to several tens of thousands of times per minute, and the direction of the arrow (1) while the blade 20 is brought into contact with the work surface 41 of the work material 40. Move to, and perform grinding.

  Since grinding is performed by cutting a very small convex portion (FIG. 6, reference numeral 17) of the blade portion 20 into the work surface 41, an extremely small cutting amount t can be obtained.

  Further, since the protrusion 15 has a cylindrical shape, the protrusion 15 does not interfere with the work surface 41 even when the grinding tool 10 is tilted. Therefore, grinding can be performed such that the central axis 25 of the tool is inclined by the inclination angle θ1 (30 degrees in the drawing) with respect to the normal line 42 of the work surface 41. Accordingly, a wide contact area between the blade portion 20 and the work surface 41 can be ensured, so that the grinding operation is quickened and the finish of the ground surface 43 is improved.

  Furthermore, since the blade portion 20 extends in a hemispherical shape, the maximum inclination angle θ2 is 90 degrees. Therefore, grinding can be performed while adjusting the inclination of the grinding tool 10 in the range of inclination angles θ1 to θ2 (maximum width of 0 to 90 degrees), so it can flexibly handle complicated curved surfaces and corners. can do.

  In addition, since the blade portion 20 is a part constituting the polycrystalline sintered diamond layer 13, it is possible to grind the cemented carbide workpiece 40.

  In this way, it is possible to grind cemented carbide and to finely grind small ultra-precision molds and ultra-precision parts.

Next, a modified example of the embodiment will be described with reference to the drawings.
FIG. 10 is a diagram showing a modification of FIG. The difference from FIG. 3 is that a conical protruding portion 15B is provided at the tip of the main body portion 14 of the polycrystalline sintered diamond layer 13. The rest of the configuration is the same as that in FIG. 3, and the detailed description is omitted by using the reference numerals in FIG. 3.

  Since the protruding portion 15B is gradually thickened toward the main body portion 14 side, the base of the protruding portion 15B (joint portion between the protruding portion 15B and the main body portion 14) 44 against the resistance force received from the work material during grinding 44 The strength of can be improved. In addition, the radius R2 of the blade part 20 is 0.025-0.5 mm, if illustrated.

  In addition, although this invention was applied to the grinding tool for grinding a cemented carbide in embodiment, it is applicable also to the grinding tool for grinding high-hardness steel, and is applied to a general fine grinding tool. There is no problem.

  The grinding tool of the present invention is suitable for a fine grinding tool for grinding cemented carbide.

  DESCRIPTION OF SYMBOLS 10 ... Grinding tool, 12 ... Base metal, 13 ... Polycrystal sintered diamond layer, 14 ... Main-body part, 15 ... Projection part, 16 ... Hemispherical part, 17 ... Convex part, 20 ... Blade part, 40 ... Work material.

Claims (3)

In a grinding tool (10) comprising a base metal (12) and a polycrystalline sintered diamond layer (13) bonded to the tip of the base metal (12),
The polycrystalline sintered diamond layer (13) includes a main body (14) joined to the base metal (12),
A protrusion (15) protruding forward from the tip of the main body (14);
A hemispherical portion (16) formed into a hemispherical shape by electric discharge machining at the tip of the protruding portion (15);
A convex portion (17) of diamond particles formed on the surface of the hemispherical portion (16) during the electric discharge machining of the hemispherical portion (16), and a hemispherical blade portion for grinding the work material (40) (20) and a grinding tool characterized by comprising:   The grinding tool according to claim 1, wherein the projecting portion has a cylindrical shape.   The grinding tool according to claim 1, wherein the protruding portion has a conical shape.

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