JP2002283121A - End mill and cutting method using this end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill which can perform high accuracy work and can obtain high work efficiency, while the breakage of an edge can be suppressed. SOLUTION: A shank part 11 and an edge part 12 are integrally formed. The external periphery of the edge part 12 is provided with two spiral protrusive streaks 13. The lower end front edge of the spiral protrusive streak 13 is provided with an end cutting edge 16 extended in the radial direction from the center of the edge part 12. By the end cutting edge 16, a workpiece W can be cut. The end cutting edge 16 is formed in a swollen circular arc shape. The radius r1 of a circular arc of the end cutting edge 16 is set to a value exceeding a radius r2 within a range 10 times or less the radius r2 relative to the radius r2 of the edge part 12. A reaction force γ, acting in the normal direction of the end cutting edge 16 relative to it, is made to an inclined state vertically approaching toward the axial line of the end mill. Accordingly, a component force β acting in the radial direction of the edge part 12 is small, and the breakage or the like is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill in which a shank portion and a blade portion are integrally formed, and a blade edge bulged and formed in an arc shape is provided at the tip of the blade portion. The present invention also relates to a cutting method using the end mill.

[0002]

2. Description of the Related Art A ball end mill is generally used for cutting a surface of a work having a curved surface or a step surface such as a molding surface of a mold.

[0003] In a conventional ball end mill, as shown in FIG. 4, a blade edge 6 at the tip of a blade portion 2 is formed so as to bulge in a semicircular shape having a radius equal to the radius of the blade portion 2. Therefore, in this ball end mill, the cutting edge 6 draws a hemispherical locus during cutting rotation.

[0004]

However, as described above, the fact that the cutting edge 6 has a semicircular shape having the same radius as the radius of the cutting portion 2 means that the cutting edge 6 has a large curvature. become.

[0005] On the other hand, during cutting, since the volume to be cut is larger on the outer peripheral side in the radial direction of the blade portion 2, the cutting resistance is larger on the outer peripheral side. This cutting force appears as a reaction force in the direction normal to the arc of the cutting edge 6. That is, as apparent from FIG. 4, a reaction force γ in the normal direction of the cutting edge 6 acts on the cutting edge 6 due to the cutting resistance. The reaction force γ in the normal direction is the component force α in the end mill axial direction.
And a component force β in the end mill radial direction. In this case, as described above, since the cutting resistance is larger on the outer peripheral side of the cutting edge 6, the reaction force γ is also large.

Further, as is apparent from FIG. 4, in the conventional end mill, since the diameter of the arc of the cutting edge 6 is small, the component force α in the axial direction of the end mill is small. The horizontal component which is the radial component β of γ is large. Therefore, especially on the outer peripheral side of the blade portion of the blade edge 6,
Breakage or the like may frequently occur.

Further, the component force β in the radial direction of the end mill is a force in a direction in which the end mill is bent. Therefore, if the component force β is large, it causes severe vibration during machining. Then, when the vibration becomes severe, the processing accuracy is naturally greatly reduced.

In order to prevent this, conventionally, the feed amount per rotation of the end mill has been reduced to reduce the cutting resistance. Therefore, the cutting efficiency is poor, and it has been difficult to execute an efficient machining operation. in addition,
When the vibration is generated as described above, the cutting efficiency is further reduced. Furthermore, since the component force β in the radial direction of the end mill is a force in the direction of separating the cutting edge 6 from the workpiece W, the cutting efficiency is spurred.

The present invention has been made to solve such a problem. An object of the present invention is to provide an end mill that suppresses the risk of breakage of a blade edge and the like, enables high-precision machining, and improves cutting efficiency so that an efficient machining operation can be performed. It is in.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a shank portion and a blade portion are integrally formed, and a bottom front edge of a spiral ridge having a land. In the end mill, the cutting edge is formed so as to bulge in an arc shape toward the axial direction, and the cutting edge draws a spherical locus during cutting, the swelling radius of the cutting edge, the It is characterized in that the value exceeds the radius and is equal to or less than 10 times the radius of the blade portion.

Therefore, as compared with a conventional end mill, the swelling radius of the cutting edge can be increased, and the curvature thereof can be increased.
The reaction force acting on the cutting edge based on the cutting resistance can be inclined upright so as to approach the end mill axis. For this reason, the component force in the radial direction of the end mill can be reduced, breakage of the cutting edge can be suppressed, a long life can be achieved, and high-efficiency, high-precision cutting can be performed.

According to a second aspect of the present invention, in the first aspect, the swelling radius of the cutting edge is set to a value of 1.5 to 5 times the radius of the cutting portion. Therefore, the cutting edge can be bulged and formed to have a sufficient curvature.

According to a third aspect of the present invention, in the first aspect, the radius of the cutting edge is set to 2.5 to 4 times the radius of the cutting portion.
It is characterized by being doubled. Also in this case, the cutting edge can be formed so as to protrude so as to have a more sufficient curvature.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a minute arc is formed at an outer end of the cutting edge. Therefore, the concentration of the stress acting on the cutting edge at the outer periphery of the cutting portion can be reduced by the minute arc. Therefore, it is possible to contribute to long life of the cutting edge and high-speed and high-precision cutting.

According to a fifth aspect of the present invention, in the fourth aspect, the minute arc has a radius of 0.5 mm or more,
It is characterized in that the value is equal to or less than half the radius of the blade portion. Therefore, sufficient stress relaxation can be obtained.

According to a sixth aspect of the present invention, in the fourth aspect, the minute arc has a radius of 0.5 mm or more,
mm or less. Therefore, further stress relaxation can be obtained.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, a relief portion not involved in cutting is formed at the center of the tip of the blade portion. Accordingly, the chips are smoothly discharged from the flute grooves via the escape portions, so that higher-speed cutting can be performed.

According to an eighth aspect of the present invention, in the seventh aspect, the escape portion is formed by a concave portion. Therefore, the chips are reliably discharged through the recesses, which can contribute to high-speed cutting.

According to a ninth aspect of the present invention, in any one of the seventh and eighth aspects, the radius of the relief portion is not more than half and not less than one tenth of the radius of the blade portion. . Therefore, the chips can be reliably discharged, which contributes to high-speed cutting.

According to a tenth aspect of the present invention, in the cutting method using the end mill according to any one of the first to ninth aspects, the length of the blade in the axial direction from the tip of the blade is one-third. It is characterized in that cutting is performed within 1 or less.

Therefore, a cutting method capable of achieving the above-mentioned effects can be realized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of an end mill embodying the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 to 3, in the end mill of this embodiment, a shank portion 11 and a blade portion 12 are continuous in the length direction of the end mill, and they are integrally formed. A plurality of (in this embodiment, 2
), A land 13a is formed at the front edge of the outer peripheral surface, and a front face in the rotational direction is a rake face 14. A flute groove 15 for discharging chips is formed between the spiral ridges 13.

The tips of the spiral projections 13 (FIGS. 1 and 2)
At the front edge, a bottom blade 16 is formed as a cutting edge extending radially from the center of the blade portion 12. The work W can be cut by the bottom blade 16.

The bottom blade 16 is formed to protrude in an arc shape in the axial direction (downward in FIGS. 1 and 2). Figure 1
As shown in FIG. 2A and FIG. 2, the radius of the arc of the bottom blade 16 (hereinafter simply referred to as the bottom blade radius) r1 is the maximum radius of the blade 12 (hereinafter simply referred to as the blade radius) r2 (r2 = d2
/ 2) exceeds the blade radius r2 and the blade radius r
It is set to a value within the range of 10 times or less of 2. Here, d2 represents the diameter of the blade portion 12. A desirable range is a value in which the bottom edge radius r1 is 1.5 to 5 times the edge radius r2. As a more desirable range, a value in a range where the bottom blade radius r1 is 2.5 to 4 times the blade portion radius r2 may be set.

As shown in FIG. 6, a minute arc 18 is formed at the outer end of the bottom blade 16 on the outer periphery of the blade portion 12. This minute arc has a radius of 0.5 mm or more, and the blade portion 12
Is set within a range of one half of the radius r2 of. A desirable range is a radius of 0.5 mm or more and 2 mm
The following values.

The end mill according to this embodiment is made of high-speed steel, cemented carbide, cermet, or the like.
A protective coating (not shown) made of any of N, TiCN, and the like is applied.

The end mill configured as described above is used in the same manner as the above-described conventional end mill. In addition, the form of cutting is dry cut processing using no lubricating oil, semi-dry processing using mist-like lubricating oil,
Any of wet processing using lubricating oil or coolant may be used. In this case, when cutting the flat portion of the work W, that is, the surface of the work perpendicular to the end mill axis, one third of the length of the blade portion 12 in the length direction from the tip of the blade portion 12 which is the center of the blade portion 12. Blade 1 in the area within
6 performs cutting. Therefore, no excessive cutting force acts on the bottom blade 16. In the case of cutting a workpiece surface that is inclined or curved with respect to the axis of the end mill, or in the case of cutting a stepped portion, an area wider or narrower than the one-third area is cut.

In the end mill of this embodiment configured as described above, the bottom edge radius r1 is larger than that of the conventional ball end mill. For this reason, as is clear from FIG. 5, the reaction force γ acting in the normal direction to the bottom blade 16 based on the cutting force becomes inclined toward the axis of the end mill, and the conventional ball Upright than the end mill. Therefore, the component force β acting in the radial direction of the blade portion 12 is small, and cutting is continued in this state. When the radius r1 of the bottom blade exceeds 10 times the radius r2 of the blade portion, the bottom blade becomes close to a normal end mill extending in a direction perpendicular to the axis of the end mill, and is suitable for cutting a work surface having a curved surface or the like. Disappears.

Therefore, in this embodiment, the following operations and effects are exhibited.・ Since the component force β in the radial direction of the end mill due to the cutting force decreases and the component force α in the axial direction increases, breakage of the bottom blade 16 can be suppressed, and a long-life end mill is realized. it can.

Similarly, the component force β in the radial direction of the end mill
Is small, the force in the bending direction of the end mill is small, and vibration during processing can be suppressed. For this reason, high-efficiency cutting becomes possible and high-precision machining becomes possible.

As described above, since the breakage of the bottom blade 16 can be suppressed and the vibration can be suppressed, the rotation of the end mill can be increased and the feed amount per unit time can be increased. Therefore, processing efficiency can be improved.

Since the minute arc 18 is formed at the outer end of the bottom blade 16, concentrated stress on this portion is reduced, and breakage of this portion can be suppressed. Therefore, it is possible to contribute to the long service life, high efficiency, and high precision cutting described above.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention. In the second embodiment, a concave portion 17 is formed at the center of the tip (lower end in FIG. 7) of the blade portion 12 as a relief portion. Therefore, the bottom blade 16 is not provided at the center of the tip of the blade portion 12.

For this reason, in the second embodiment, the center of the blade portion 12 does not participate in cutting. Therefore, in the second embodiment, the following operations and effects are exhibited in addition to the operations and effects of the first embodiment.

Since the peripheral portion of the blade portion 12 has a low peripheral speed and is not significantly involved in cutting, a concave portion 17 is provided in this portion.
There is hardly any decrease in cutting ability due to the provision of. Rather, the chips are smoothly discharged from the flute grooves 15 via the recesses 17, so that a higher-speed cutting can be performed.

(Another Embodiment) The present invention is not limited to the first and second embodiments, but is included in the present invention even when embodied in the following modes.

In the first and second embodiments, two spiral ridges 13 and flute grooves 15 are provided, but three or more spiral ridges 13 and flute grooves 15 are provided. -Omit the minute arc 18 at the outer end of the bottom blade 16.

A lubricating oil supply hole is provided at the center of the blade portion 12 and the shank portion 11. With this configuration,
Since lubricating oil can be supplied to the cutting portion from the lubricating oil supply hole, it is convenient in wet processing. Further, when the lubricating oil is not supplied from the lubricating oil supply hole, the opening on the blade edge side of the lubricating oil supply hole performs the same chip discharging action as the concave portion 17 of the second embodiment, so that high-speed cutting is possible. become.

In place of the concave portion 17 as the escape portion, a plane that is perpendicular to the mere end mill axis direction is provided.

[0041]

As described above, according to the present invention, according to the present invention, it is possible to suppress the breakage of the cutting edge, achieve a long life, achieve high-precision machining, and obtain high working efficiency. it can.

[Brief description of the drawings]

FIG. 1A is a front view showing a first embodiment of the present invention, and FIG. 1B is an enlarged explanatory view showing a radius of a bottom blade.

FIG. 2 is a side view of an end mill embodying the present invention.

FIG. 3 is a bottom view of an end mill embodying the present invention.

FIG. 4 is an explanatory view showing the operation of a conventional end mill.

FIG. 5 is an explanatory view showing the operation of an end mill embodying the present invention.

FIG. 6 is a partially enlarged front view showing an outer end of a cutting edge.

FIG. 7 is a front view showing a second embodiment of the present invention.

[Explanation of symbols]

11 ... shank part, 12 ... blade part, 13 ... spiral ridge, 16
... Bottom blade, 17: concave portion as escape portion, 18: minute arc, r1: bottom blade radius, r2: blade portion radius.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masamitsu Suzuki 1 Ochiai Ogaai, Kasuga-machi, Nishi-Kasugai-gun, Aichi Prefecture Toyota Gosei Co., Ltd. Toyoda Gosei Co., Ltd. F-term (reference) 3C022 AA10 KK01 KK06 KK23 KK25 KK26

Claims (10)

[Claims] 1. A shank portion and a blade portion are integrally formed, and a bottom front edge of a spiral ridge having a land is used as a cutting edge, and the cutting edge is formed to protrude in an arcuate shape in an axial direction to cut. In the processing, in the end mill, wherein the cutting edge draws a spherical locus, the swelling radius of the cutting edge is set to a value not more than 10 times the radius of the cutting portion, exceeding the radius of the cutting portion. End mill. 2. The end mill according to claim 1, wherein the swelling radius of the cutting edge is 1.5 to 5 times the radius of the cutting portion. 3. The end mill according to claim 1, wherein the radius of the cutting edge is 2.5 to 4 times the radius of the cutting portion. 4. The end mill according to claim 1, wherein a minute arc is formed at an outer end of the cutting edge. 5. The end mill according to claim 4, wherein the radius of the minute arc is not less than 0.5 mm and not more than half the radius of the blade portion. 6. The end mill according to claim 4, wherein the radius of the minute arc is 0.5 mm or more and 2 mm or less. 7. The end mill according to claim 1, wherein a relief portion not involved in cutting is formed at the center of the tip of the blade portion. 8. The end mill according to claim 7, wherein the relief portion comprises a concave portion. 9. The method according to claim 7, wherein the radius of the clearance is less than half the radius of the blade, and
An end mill characterized in that the value is 1 / more or more. 10. A cutting method using the end mill according to claim 1, wherein a cutting edge at a position within one third of a length of the blade portion in an axial direction from a tip of the blade portion is used. A cutting method using an end mill, characterized in that a flat surface of the work is cut.