JP2002254231A - Cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method with which a shape to be machined such as a deep groove is precisely formed at a desired position. SOLUTION: The cutting method is for forming on a workpiece a deep groove whose ratio F/W of a depth F and a width W is 10 or more. A cutting tool to be used is equipped with a long and cylindrical cutting part having cutting blades at a tip and side surface whose ratio L/D of an effective length L and a diameter D is 10 or more, and rotated at a high speed of more than 30000 rpm. The tip part or the cutting part is used for forming a guide groove along a cutting line where the deep groove is formed. The deep groove is formed by cutting with the tip and the side surface cutting blades on the cutting part along the guide groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cutting method, and more particularly, to a cutting method for forming a deep groove in a material using a cutting tool having an elongated cutting portion extending in a longitudinal direction.

[0002]

2. Description of the Related Art In the case of forming recesses, grooves and the like in a material such as a metal material, a so-called spindle unit is used to rotate a cutting tool such as a drill and an end mill to cut the material to obtain a desired shape such as a recess and a groove. The cutting process which forms is performed.

In the case where fine processing such as a fine concave portion or a fine groove is required, as in a molding die, processing by electric discharge machining is also performed.

[0004]

When a deep groove or the like is formed by cutting using the above-mentioned spindle unit, an elongated cutting tool is required. When trying to cut a workpiece (work) such as a metal material with an elongated cutting tool, the reaction force from the workpiece acts on the cutting tool when the tip of the cutting blade of the rotating cutting tool bites into the workpiece. In some cases, the cutting tool advances in a rotational direction from a line that the cutting tool should originally pass through (a line on which processing is to be performed), and it may not be possible to perform processing at a desired position. This tendency is particularly remarkable when a metal material is subjected to fine processing or the like or a deep groove or the like is formed. When a groove is cut using a rotary tool provided with a cutting blade extending in the length direction on the side surface, the ratio L / D between the effective length L and the diameter D of the tool is to maintain the rigidity of the tool sufficiently. It has been thought that it is necessary to make the value as small as possible. Therefore, it is considered that a groove having a large ratio F / W between the depth F and the width W, that is, a groove having a very large depth F as compared with the width W cannot be formed by mechanical cutting. Have been. Similarly, width W
However, it has been considered that a very narrow groove such as 1 mm or less cannot be formed by cutting.

On the other hand, electric discharge machining enables machining of a groove having a small width or a groove having a depth greater than the width. However, in electric discharge machining, it is necessary to prepare an electrode for electric discharge machining. It is time-consuming and expensive, and it is difficult to machine a deep groove, a machined portion located deep in a recess, or the like.

The present invention has been made in view of the above points, and has as its basic object to provide a cutting method capable of accurately forming a processing shape such as a deep groove at a desired position.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a cutting method for forming a deep groove having a ratio F / W of depth F to width W of 10 or more in a material. In this method, the cutting edge is provided at the tip and the side, and the diameter D is 1 mm.
And the ratio L / D of the effective length L to the diameter D is 10
A cutting tool having the above-described elongated cylindrical cutting portion is set at 3 per minute.
While rotating at a high speed of 0000 rotation or more, a guide groove along a cutting line in which the deep groove is to be formed is formed by using a tip portion of the cutting portion, and the guide groove of the cutting portion is formed along the guide groove. Cutting with the cutting blade on the tip and side,
The deep groove is formed.

Further, a cutting tool having an elongated cylindrical cutting portion having a diameter D of 0.5 mm or less and a ratio L / D of the effective length L to the diameter D of 15 or more is rotated at a high speed of 50,000 rpm or more. Alternatively, the guide groove may be formed.

The cutting tool is a ball end mill having a substantially hemispherical convex end, and the guide groove has a transverse cross-sectional shape extending upward from the bottom of the semicircle and the upper end of the semicircle. And a vertical wall portion having a height equal to or greater than the diameter of the semicircle.

Here, "the tip is substantially hemispherical convex" means that the tip of the cutting portion is substantially hemispherical convex in a rotating state.
That is, it means that the locus drawn by the rotating tip is substantially hemispherical convex.

The cutting tool may be a flat end mill having a flat end at the cutting portion, and the guide groove has a rectangular cross section and a depth of the guide groove not more than the width. It can be configured as follows. Further, the guide groove depth may be 50% or less of the width thereof.

The invention, in one aspect, provides a depth F and a width W.
A method of forming a deep groove having a ratio F / W of 10 or more in a material, the method comprising forming a guide groove along a cutting line in which the groove is to be formed, and cutting the tip and side surfaces. With a blade, the diameter D is 1 mm or less, and the effective length L and the diameter D
Along with the cutting groove, a cutting tool having an elongated cutting portion having a ratio L / D of 10 or more is rotated at a high speed of 30000 rpm or more, and along the guide groove, a cutting blade of a tip and a side surface of the cutting portion is used. Cutting is performed to form the deep groove.

Further, a cutting tool having an elongated cylindrical cutting portion having a diameter D of 0.5 mm or less and a ratio L / D of the effective length L to the diameter D of 15 or more is rotated at a high speed of 50,000 rpm or more. The deep groove may be formed while performing this.

The cutting tool is a ball end mill in which the tip of the cutting portion is substantially hemispherical convex, the guide groove has a V-shaped cross-sectional shape, and the width of the upper end of the guide groove is equal to that of the ball end mill. It can be configured to be wider than the diameter of the tip.

[0015] The guide groove may have a dimension such that the tip of the ball end mill is in contact with the bottom of the guide groove below a vertically intermediate position of the guide groove.

The cutting tool is a ball end mill having a substantially hemispherical convex tip, and the guide groove has a substantially rectangular cross-sectional shape. The width of the guide groove is the diameter of the tip of the ball end mill. It can be configured to be wider.

Further, the guide groove is formed by a cutting tool having a larger L / D than a cutting tool for cutting the deep groove. According to such a configuration, when forming the guide groove,
The cutting tool can be fed at a higher feed speed than when forming a deep groove.

According to another aspect of the present invention, there is provided a cutting method for cutting a work material with a rotary tool having an elongated cutting portion having a cutting blade at a tip and a side surface. In this method, a guide groove along a cutting line at which cutting by the rotary tool is to be performed is formed by using a tip portion of the cutting portion, and cutting by the cutting blade is performed along the guide groove. I do.

Also, the guide groove may be formed by moving the rotary tool a plurality of times along the cutting line.

Further, the depth of the guide groove may be set to be equal to or less than its width or equal to or less than 50% of the width.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. First, a schematic configuration of a cutting machine (machining center) that performs a cutting method according to an embodiment of the present invention will be described.

FIG. 1 is a schematic perspective view of the machining center 1. As shown in FIG. 1, the machining center 1 includes a base 2 installed on a floor, and a processing unit 4 disposed above the base 2. A processing table 8 on which a workpiece (work) 6 to be cut is placed is provided below the processing section 4. The processing table 8 is configured to be able to move vertically and horizontally by a known mechanism based on numerical data related to cutting.

A head 10 is provided above the processing table 8, and a unit mounting section 14 to which the spindle unit 12 is removably mounted is provided below the head 10. In the spindle unit 12, the cutting tool 16 attached to the tip faces the processing table 8 and the processing table 8
The upper work 6 is mounted on the unit mounting portion 12 so that the upper work 6 can be cut. The head 10 can be moved in the vertical and horizontal directions with respect to the processing table 8 by a known mechanism based on numerical data related to cutting.

The unit mounting portion 14 has a built-in chuck. By coupling a coupler (not shown) at the rear end of the spindle unit 12 to the chuck, the spindle unit 12 is removably mounted and fixed to the unit mounting portion 14. can do. This spindle unit 12
Is a cutting tool 16 attached to the tip of a rotatable spindle.
Is rotated at a maximum speed of 50,000 rpm or more by a built-in motor to cut the work 6. The rotation speed of the cutting tool 16 is variable.

Accordingly, in the machining center 1, the worktable 8 on which the work 6 is mounted and the spindle unit 12 are relatively moved on the basis of numerical data relating to the cut, so that the work 6 can be cut as desired. can do.

The machining center 1 is provided with a so-called ATC (automatic tool changer) that can automatically change the spindle unit 12. As shown in FIG. 1, a replacement spindle unit mounting portion 18 on which a replacement spindle unit is mounted
The replacement spindle unit mounting portion 18 is provided.
Is mounted with a plurality of replacement spindle units 20 to which cutting tools having different dimensions and shapes are attached.

Under the head 10, a replacement arm 2 for replacing the spindle unit 12 mounted on the unit mounting portion 14 with a replacement spindle unit 20 mounted on the replacement spindle unit mounting portion 18 is provided.
2 are provided. In this embodiment, the replacement spindle unit mounting section 18 connects the replacement spindle unit 20 to the replacement arm 22 by a drive mechanism (not shown).
Direction, and the desired replacement spindle unit 20 is gripped by the replacement arm 22.
The spindle unit 12 is configured to be exchangeable with the spindle unit 12 mounted on the spindle unit 4. Therefore, in the machine center 1, various processes can be performed on the work 6 by replacing the spindle unit 12 mounted on the unit mounting section 14.

In this embodiment, the cutting tool 16 mounted on the spindle unit 12 mounted on the unit mounting portion 14 or the cutting tool 16 mounted on a plurality of replacement spindle units 20 is provided with a built-in motor output. It is a cutting tool integrated with the main shaft connected to the shaft,
A so-called ball end mill 24 in which the tip of the cutting portion is substantially hemispherically convex.
(FIG. 2), a so-called flat end mill 26 (FIG. 3) in which the tip of the cutting portion is flat, and a mill 28 in which the tip of the cutting portion is substantially conical.
(FIG. 4). These mills 24, 26, 2
8 is the tip 24a, 26a, 28a and the side 2
4b, 26b, and 28b are provided with cutting blades. In this embodiment, the diameter D is 1 mm or less, for example, 0.4 mm, and the ratio L / D between the effective length L and the diameter D is 10 or more, for example, 20. To 40 elongated cylindrical cutting portions 24c, 26
c and 28c. The effective length L is, as shown in the drawing, a length obtained by adding the length of the shaft portion where the cutting blade is formed and the length of the shaft portion where the cutting portion is not formed. In the drawings, the cut portions 24c, 26c, and 28c are drawn thick for clarity, so that the L / D in the drawings is not accurate.

Next, a deep groove having a width of 0.4 mm and a depth of 5 mm, ie, a ratio F / W of the depth F to the width W of 12.5, is formed in the metal material (work 6) for the mold. A cutting process according to the first embodiment of the present invention will be described. As metal materials for molds,
For example, rolled steel for general structure (SS), carbon steel for machine structure (SC, SCK), carbon tool steel (SK), alloy tool steel (SKS, SKD), high speed steel (SNC), high carbon chromium, bearing Steel (SNJ), Nickel-Chromium-Molybdenum Steel (SNCM), Chromium-Molybdenum Steel (SCM), Aluminum-Chromium-Molybdenum Steel (SACM), Prehardened Steel, High Tensile Aluminum Alloy and Duralumin (A7075)
Aluminum alloy, copper alloy and the like.

The ball end mill 24 having a cutting portion having a diameter D of 0.4 mm and an effective length L of 12 mm, and therefore having an L / D of 30.
An aluminum alloy (A70) to which the spindle unit 12 with the
75) Place and fix the work 6 on the worktable 4. Then
While rotating the ball end mill 24 at, for example, 30,000 revolutions per minute by the built-in motor of the spindle unit 12, the processing table 4 on which the workpiece 6 is mounted and the spindle unit 12
Are relatively moved to process the work 6. The number of rotations of the ball end mill 24 may be 50,000 or more per minute.

FIG. 5 is a perspective view showing a step of forming a guide groove in a work, and FIG. 6 is a sectional view of the guide groove.

As shown in FIG. 5, in this embodiment, a cutting line 32 in which a deep groove 30 is to be formed is formed.
The spindle unit 12 is moved along the dashed line (dot-dash line), and the guide groove 34 is
Are formed by cutting. In the present embodiment, in forming the guide groove, the cutting depth by the ball end mill 24 is 2.5 μm, and the feed speed is 400 mm per minute.

Since the cutting portion 24c has an elongated cylindrical shape having a substantially hemispherical convex tip 24a, the cross-sectional shape of the formed guide groove 34 is, as shown in FIG. It has a bottom portion 34a and a vertical wall portion 34b upward from the upper end of the semicircle. In the present embodiment, the guide groove 34 is
The height H of the vertical wall portion 34b is formed so as to have a height equal to or larger than the diameter of the semicircle constituting the bottom. In the present embodiment, the cutting portion 24c has a cylindrical shape and the cutting portion 24
Since the tip 24a of c is substantially hemispherical convex, the diameter of the semicircle forming the bottom 34a of the guide groove 34 is substantially the same as the diameter D of the cutting portion 24c and the width W1 of the guide groove 34 and the deep groove 30. .

In this embodiment, the guide groove 34 is formed by reciprocating the ball end mill 24 along the cutting line 32 a plurality of times. However, the guide groove 34 may be cut by moving the ball end mill 24 a plurality of times in the same direction along the cutting line 32. Alternatively, the depth of the guide groove is not limited to this depth.
May be moved once along the cutting line 32 to form a guide groove.

Next, the spindle unit 12 and the workpiece are moved so that the spindle unit 12 moves along the cutting line 32 while replacing the spindle unit with the cutting groove 24c of the ball end mill 24 along the guide groove 34 without replacing the spindle unit. 6 is relatively moved, and a deep groove 30 having a depth F is formed in the work 6 using the cutting blades at the tip and side of the cutting portion 24c.
It is formed by cutting.

In this embodiment, the ball end mill 24 is reciprocated along the cutting line 32 to form a deep groove. However, the guide groove 34 may be cut by moving the ball end mill 24 a plurality of times in the same direction along the cutting line 32. In this embodiment, the depth of cut by the ball end mill 24 is 5 μm for forming the guide groove.
And the feed rate is 4000 mm per minute.

The rotary cutting tool to be used has a very thin cutting portion having a diameter of 1 mm or less, and has a ratio L / D of the effective length L to the diameter D.
Is a very large value of 10 or more. Therefore, the guide groove 3
At the time of cutting of No. 4, the cutting tool may be bent, and the tip may deviate from the cutting line 32 in the lateral direction. In order to avoid this problem, it is necessary to rotate the cutting tool at an extremely high rotation speed to stabilize the tool. Also,
The feed speed of the tool needs to be set to a relatively low speed while taking into account that the tool does not bend or break. According to this method, the width is 1 mm or less, for example, 0.2 mm.
A groove of about 0.8 mm can be formed by cutting. The rotation speed of the tool is more than 30,000 revolutions per minute,
Preferably, it is necessary to be at least 50,000 revolutions per minute, and the feed rate is, for example, from 0.2 m / min when using a mill with 0.2 mm D to when using a mill with 0.8 mm D. In the range of 4m per minute, depending on various conditions,
Is set.

In such a cutting process, when the deep groove 30 is cut, the ball end mill 24 is moved along the guide groove 34 formed in advance. It becomes difficult to shift from the processing line 32), and it becomes possible to form a deep groove at a desired position. Further, since there is no need to replace the spindle unit 12, the operation time is reduced. Further, this cutting method is also applicable to a processing machine in which replacement of the spindle unit or replacement of the cutting tool 16 cannot be performed.

Further, by using mills having different diameters of the cutting portion, various widths, for example, 1 mm, 0.8 m
m deep grooves can be formed.

In the first embodiment, the guide groove and the deep groove are formed by the same cutting tool. However, the guide groove may be formed by another cutting tool having a smaller L / D than the tool for cutting the deep groove. . Prior to cutting the deep groove under the conditions of the first embodiment, for example, the effective length L is 10 mm and the diameter D is 0.1 mm.
The guide groove may be formed by cutting with a ball end mill of 4 mm, that is, L / D of 2.5. The cutting depth at this time is, for example, 10 μm, and the feed speed is 4000 mm per minute.

Next, a cutting process according to a second embodiment of the present invention will be described. FIG. 7 is a sectional view of a guide groove according to the second embodiment. The point that the cutting tool 16 to be used is a so-called flat end mill 26 (FIG. 3) in which the tip of the cutting portion is flat is different from that of the above-described first embodiment.

In the second embodiment, since the cutting tool to be used is a so-called flat end mill 26 having a flat cutting end, the guide groove 36 has a rectangular cross-sectional shape as shown in FIG. In the present embodiment, the guide groove 36 is set such that its depth f2 is substantially equal to the width W2. Further, the depth f2 of the guide groove may be set to be smaller than the width W2, for example, 50% of the width W2 or smaller. The width W2 of the guide groove 36
Is substantially the same as the diameter D of the cutting portion 26c and the width of the formed deep groove. Also in the present embodiment, the spindle unit 12 and the work 6 are moved so that the spindle unit 12 moves along the cutting line while the cutting portion 26c of the flat end mill 26 follows the guide groove 36 without replacing the spindle unit. Are relatively moved, and a deep groove having a depth F is cut and formed in the work 6 using the cutting blades at the tip 26a and the side portion 26b of the cutting portion 26c. At this time, the deep groove may be cut by reciprocating the flat end mill 26 along the cutting line or moving the flat end mill 26 plural times in the same direction.

In such a cutting process, when the deep groove is cut, the flat end mill 26 is moved along the guide groove 36 formed in advance, so that the flat end mill 26 is supposed to pass through the line (cutting line). Line), and a deep groove can be formed at a desired position. Further, since it is not necessary to replace the spindle unit 12 after the formation of the guide groove, the operation time is reduced. In addition, this cutting method involves replacing the spindle unit,
Alternatively, the present invention can be applied to a cutting machine in which the cutting tool 16 cannot be replaced.

Next, a cutting process according to a third embodiment of the present invention will be described. FIG. 8 is a sectional view of a guide groove 38 according to the third embodiment. The conditions of the deep groove, the processing material, and the like are the same as those in the above-described embodiment, but the present embodiment is different from the above-described embodiment in that the deep groove is cut with a different type of cutting tool than the guide groove.

First, the spindle unit 12 to which the mill 28 whose cutting end 28a has a substantially triangular shape is mounted on the unit mounting portion 14, and the workpiece 6 to be cut is mounted and fixed on the processing table 4. Next, the mill 28 is driven by the built-in motor of the spindle unit 12 at, for example, 300 / min.
The worktable 4 on which the work 6 is mounted and the spindle unit 12 are relatively moved based on numerical data related to the cutting while rotating at a speed of 00 rotation or more. A guide groove 38 having a V-shaped cross section is formed. Mill rotation speed 50
It may be 000 rotations or more. Also in this embodiment, the mill 2
The guide groove 38 may be cut by reciprocating the cutter 8 along a cutting line, or by moving the guide groove 38 a plurality of times in the same direction. Depending on the depth of the guide groove, the guide groove 38 may be cut by moving the mill 28 only once along the cutting line.

As shown in FIG. 8, the guide groove 38
In order to make the width W3 of the upper end wider than the width of the tip of the ball end mill 24 used for cutting the deep groove,
The substantially hemispherical tip of the ball end mill 24 is
At a position x below the middle position M in the vertical direction of the guide groove 38 so as to be in contact with the bottom of the guide groove 38. here,
The vertical middle position M of the guide groove 38 refers to a point on the bottom surface of the guide groove 38 which is located at a height lower than the surface of the workpiece 6 by half the depth f3 of the guide groove.

Next, using the exchange arm 22,
The spindle unit 12 mounted on the spindle unit 4 is replaced with a spindle unit 12 to which a so-called ball end mill 24 having a substantially hemispherical convex end is mounted.

Next, the cutting portion 2 of the ball end mill 24
The spindle unit 12 and the work 6 are relatively moved so that the spindle unit 12 moves along the cutting line 32 while aligning the cutting edge 4c along the guide groove 38. Using this, a deep groove having a depth F is formed in the work 6 by cutting. At this time, even if the deep groove is cut by moving the ball end mill 24 only once along the cutting line,
May be reciprocated along a cutting line or moved a plurality of times in the same direction to cut a deep groove.

In such a cutting process, when cutting a deep groove, the ball end mill 24 is moved along a guide groove 38 formed in advance, so that the ball end mill 24 should pass through the line (cut Line), and a deep groove can be formed at a desired position.

In the third embodiment, a guide groove 38 having a V-shaped cross section is formed, and then a deep groove is formed along the guide groove 38 by the ball end mill 24. However, a guide groove having a semicircular bottom is formed by the ball end mill. And then forming a deep groove with a flat end mill along this guide groove, or forming a rectangular guide groove with a flat end mill and then forming a deep groove with a ball end mill along this guide groove You may. In these cases, the guide groove is formed such that its width is slightly larger than the diameter of the tip portion of the mill used for forming the deep groove.

In the above embodiment, the cutting portion of the mill has a substantially cylindrical shape, but a cutting tool having a cutting portion that tapers toward the tip may be used.

In the above embodiment, the machining center 1 in which the spindle unit can be automatically replaced is used. However, the present invention can be implemented in a cutting machine in which the spindle unit cannot be replaced or cannot be replaced automatically. is there. When the guide groove machining and the deep groove machining are performed by different cutting tools with such a cutting machine, the operator needs to operate the entire pindle unit or the cutting tool (mill).
Will be replaced manually.

Further, in the above embodiment, the cutting portion has a diameter D of 1 mm or less and a ratio L between the effective length L and the diameter D.
Although an elongated cylindrical cutting tool having a / D of 10 or more was used, the present invention is not limited to such a tool.

Further, in the above embodiment, the cutting tool is set to 3
Although the guide groove and the deep groove are formed by rotating at 0000 rotations or more, the present invention is not limited to this number of rotations.

Further, the above embodiment is a cutting process for forming a deep groove in a metal material, but the present invention can also be applied to a case of cutting a metal material of another type.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a machining center that performs cutting according to an embodiment of the present invention.

FIG. 2 is a side view of a ball end mill used for cutting according to the embodiment of the present invention.

FIG. 3 is a side view of a flat end mill used for cutting according to the embodiment of the present invention.

FIG. 4 is a side view of a mill having a substantially triangular tip at a cutting portion used for cutting according to the embodiment of the present invention.

FIG. 5 is a perspective view showing a step of forming a guide groove in a work in the first embodiment of the present invention.

FIG. 6 is a sectional view of a guide groove according to the first embodiment of the present invention.

FIG. 7 is a sectional view of a guide groove according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a guide groove according to a third embodiment of the present invention.

[Explanation of symbols]

 6: Work (workpiece) 24: Ball end mill 30: Deep groove 32: Cutting line 34: Guide groove

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Abe 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Inks Inc. (72) Inventor Takashi Inomata 3-2- Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 1 Inc. Inc. (72) Naoki Horiguchi, Inventor 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture Ink Inc. (72) Kazuyasu Suda 3-2-1, Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture Inks Inc. (72) Inventor Jun Nishijima 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa F-term in Inks Inc. (reference) 3C022 EE17 KK02 KK03

Claims (11)

[Claims] 1. A cutting method for forming a deep groove in a material having a ratio F / W of a depth F to a width W of 10 or more, wherein a cutting blade is provided at a tip and a side surface and a diameter D is 1 mm or less. A cutting process in which the deep groove is formed while a cutting tool having an elongated cylindrical cutting portion having a ratio L / D of the effective length L to the diameter D of 10 or more is rotated at a high speed of 30000 rpm or more at a high speed. A guide groove along a line is formed using a tip portion of the cutting portion, and a cutting process is performed by a cutting blade on a tip and a side surface of the cutting portion along the guide groove to form the deep groove. And cutting method. 2. The cutting method according to claim 1, wherein the cutting tool is a ball end mill having a substantially hemispherical convex end, and the guide groove has a semicircular cross section. And a vertical wall extending upward from an upper end of the semicircle, wherein the vertical wall has a height equal to or greater than the diameter of the semicircle. 3. The cutting method according to claim 1, wherein the cutting tool is a flat end mill in which a tip of the cutting portion is flat, and the guide groove has a rectangular cross section. A cutting method, wherein the depth of the groove is not more than its width. 4. A cutting method for forming a deep groove having a ratio F / W of a depth F to a width W of 10 or more in a material, the guide groove being along a cutting line in which the groove is to be formed. Forming a cutting tool having an elongated cutting portion having a cutting blade at a tip portion and a side surface and having a diameter D of 1 mm or less and a ratio L / D of an effective length L to a diameter D of 10 or more per minute. A cutting method, wherein the deep groove is formed by performing cutting with a cutting blade on a tip and a side surface of the cutting portion along the guide groove while rotating at a high speed of 30,000 or more. 5. The cutting method according to claim 4, wherein in the cutting tool, a tip of the cutting portion is a ball end mill having a substantially hemispherical convex shape, and the guide groove has a V-shaped cross-sectional shape. The width of the upper end of the guide groove is wider than the diameter of the tip of the ball end mill. 6. The cutting method according to claim 5, wherein the guide groove is configured such that a tip of the ball end mill contacts a bottom of the guide groove below a vertically intermediate position of the guide groove. A cutting method characterized by having a dimensional shape. 7. The cutting method according to claim 4, wherein the cutting tool is a ball end mill having a substantially hemispherically convex tip, and the guide groove has a substantially rectangular cross-sectional shape. A width of the tip is larger than a diameter of a tip end of the ball end mill. 8. The cutting method according to claim 4, wherein the guide groove is formed by a cutting tool having a larger L / D than a cutting tool for cutting the deep groove. A cutting method characterized by the fact that: 9. A cutting method for cutting a work material with a rotary tool having an elongated cutting portion provided with a cutting blade at a tip and a side surface, wherein a cutting line to be cut by the rotary tool is performed. A cutting groove formed along the guide groove by using a tip portion of the cutting portion, and performing cutting by the cutting blade along the guide groove. 10. The cutting method according to claim 9, wherein the guide groove is formed by moving the rotary tool a plurality of times along the cutting line. . 11. The cutting method according to claim 4, wherein a depth of the guide groove is equal to or less than a width thereof.