JPH02106211A - Finishing end mill - Google Patents

Abstract

PURPOSE:To increase the tool rigidity and enable a highly precise working by forming the core thickness circumferential surface, peripheral cutting edge and end cutting edge of an end mill in which the land part is provided projectingly from the core thickness circumferential surface when the radial depth of cut is not less than 0.5mm into particular forms. CONSTITUTION:A core thickness circumferential surface 4 is concentric with the edge end diameter circle, and its diameter D2 is set (0.08-0.99) D1 to the edge top diameter D1 to increase the rigidity. The axial back taper of a peripheral cutting edge 9 is set 0-0.005mm per 30mm, and the radial length L of an end cutting edge 9 is set (0.02-0.10) D1 to the edge end diameter D1, to form a first spacing angle theta1 and a second spacing angle theta2, where theta1<theta2, theta1=30-2 deg., theta2=2-5 deg.. On the cutting face in grinding from the peripheral cutting edge 6 to the core thickness circumferential surface 4, a chip pocket 10 formed in such a manner as to scrap a part of the core thickness circumferential surface is provided, and its maximum depth H is set (0.01-0.11) D1 to the edge end diameter D1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is directed to the following: 11. [Regarding an end mill for cutting, the machining accuracy of the cutting wall surface is particularly improved.

(Conventional technology) Conventionally, solid end mills made of cemented carbide etc. have a cutting edge diameter of approximately φ30 mm, and are capable of cutting grooves, cutting eyebrows, etc.
It is applied to counterbore machining, etc.

For example, those found in Japanese Utility Model Publication No. 62-34652 and Japanese Utility Model Publication No. 63-7457 are disclosed. In this case, the end mill seen in the former type has several clearance angle configurations in the peripheral cutting edge to particularly prevent the cutting edge from chipping. The latter type of end mill has several configurations of clearance angles on the bottom cutting edge, making it especially applicable to drilling.

(Problems to be Solved by the Present Invention) However, in end mill processing, for example, mold processing, etc., with technological development, it has become necessary to reduce the effort of the post-process of grinding or polishing as much as possible. therefore,
There is a need to improve the accuracy of end mill processing, and for this reason,
There is an increasing demand for the development of end mills specifically designed for cutting.

On the other hand, the commercially available end mills and the end mills found in the above-mentioned publications are designed for rough cutting.
It is not essentially an end mill for finish cutting. Therefore, due to its shape and structure, the end mill itself has low rigidity, and due to the cantilever cutting style, processing accuracy, especially cutting wall surface accuracy, cannot be obtained.

In response to such demands for high machining accuracy, the present invention improves the cross-sectional shape, the configuration of the outer peripheral cutter, and the bottom cutter to improve the rigidity of the tool, such as bending rigidity and torsional rigidity. The aim is to provide end mills for

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned object, and a land portion having an outer peripheral cutting edge and a margin, respectively, is provided on the outer peripheral portion of a tool body having a substantially cylindrical shape, and a land portion is provided with a core thickness circumference. It is provided so that it protrudes from the surface, and a bottom cutter is formed at the tip of the tool body. It is formed into a specific shape.

That is, iii. The center thickness circumferential surface is concentric with the cutting edge diameter circle, and its diameter D2 is smaller than the cutting edge diameter circle D1.
2 = (0,080 to 0.9'llD).These are set in the range of 0,080 to 0.9'llD.These are the ones with increased rigidity in consideration of finishing only.

Further, the outer circumferential cutter has an axial pack taper of 30 mm.
It is set within the range of 0 to 0.005 mm, and ri? The bottom blade marked i has a radial length set within the range of L=(0.02 to 0.10)D with respect to the cutting edge diameter D+, and the first helix angle θ3 and the second helix angle θ3.
Form the fillet angle θ, and define the angular relationship between them as θ1〈θ
2, θ, = 30' to 26, and θ2 = 2° to 5°.

Furthermore, in the invention of claim 2, the rake surface of the cutting H extending from the outer peripheral blade to the core thickness circumferential surface is provided with a chip pocket formed by hollowing out the - part of the core thickness circumferential surface. This is what I did. In this chip pocket, the maximum depth 11 from the outer peripheral edge to the chip pocket is the cutting edge diameter D1.
In contrast, H is set within the range of (0, old to 0.11)D.

(Function) The end mill for cutting 1 and 2 according to the present invention has an effective cutting action in the finishing area where the diametrical depth of cut is 0.5 mm or less.

Moreover, the end mill for finishing according to the present invention works to improve machining accuracy, especially on the cutting wall surface.

(Example) Hereinafter, an example of an end mill of the present invention will be described with reference to the drawings.

In Figures 1 to 3, (1) is a Shigegawa end mill made of cemented carbide, for example, and the tool body (2)
and a shank portion (3).

1i11 I-The tool main body (2) has a core thickness circumferential surface (4) and a land portion (5) formed on its outer periphery, and this land portion (5) is twisted in the axial direction. Associated peripheral edges (6) and margins (7) are provided, respectively.

In this case, the peripheral edge (6) is formed as an intersecting edge of the rake (8) and the margin (7).

For the margin (7), in addition to the straight-line sloped 1,000-circular relief surface shown in Figure 4 or the straight-line sloped relief surface shown in Figure 5, any suitable material such as an eccentric relief surface can be applied. be.

Therefore, the center thickness circumferential surface (4) marked with 111j is the outer peripheral edge (6
) is concentric with the cutting edge diameter circle. This is a consideration to increase the cross-sectional area of the end mill by forming concentric circles, thereby increasing tool rigidity such as bending rigidity and torsional rigidity. For example, in the finishing end mill of the present invention, the bending rigidity and torsional rigidity with respect to a perfect circle exceed 90%. The diameter D2 of the core thickness circumferential surface (4) is on = (Q, 0
It is set within the range of 80 to (1,'191 D).

If D2 is less than 0.80D, tool rigidity will be insufficient, and if it exceeds 0.99DI, chip evacuation will be poor and it will not be possible. In addition, the cross-sectional area Δ2 including the core-thickness circumferential surface (4) and the land portion (5), which depends on the diameter D2 of the core-thickness circumferential surface (4), is the virtual cross-sectional area A1 of the cutting edge diameter circle DI.
On the other hand, it is preferable that A 2 = (0,85 to 0.98)Δ1.

In addition, the cross-sectional area A2 of the commonly seen turbo flute-shaped cross-sectional shape is approximately 0.65A.

The +3i peripheral blade (6) is twisted by 30° in the illustrated case, but the back taper in the axial direction is set within the range of 0 to 0.005 mm around 30 mm. this is.

It has a smaller value than the conventional back taper, -
This consideration was made to compensate for the collapse of the L tool body (2) due to the cutting force.

Further, as shown in FIG. 3, the bottom blade (9) has a radial length L with respect to the cutting edge diameter D1.
0.10) Set within the range of DI. The idea behind this setting is to increase the cross-sectional shape as IYi mentioned,
The length of the bottom blade (9) is shortened because the strength of the cutting edge is increased due to the reduction of the back taper. In other words, the reason for shortening the length of the bottom blade (9) is that when the bottom blade (9) wears out, the frictional resistance increases accordingly, and as a result, the deflection hl of the tool body (2) increases. Because it will be. If the deflection of the tool body (2) is large, the machining accuracy will decrease, so the bottom edge (
9) is made as small as possible.

Furthermore, this bottom blade (9) has a first clearance angle θ1 and a second clearance angle θ2. In this case, the relationship between the first watermark fQθ1 and the second watermark angle θ2 is θ, θ2, θ, = 30'~2°, θ2°, θ2
= set within the range of 2° to 5°. This is a consideration in order to maintain the strength of the cutting edge and to substantially reduce the length of the bottom blade (9). Therefore, Jikko 63
Unlike the one used for drilling as seen in the -7457 publication, the angular range is small.

In addition, the one shown in Fig. 5 has the diameter D of the core thickness circumferential surface (4) somewhat larger and the chip pocket (lO) formed on the rake face (8) side also larger. . That is, the chip pocket (10
), the maximum depth 11 from the peripheral edge (6) is the cutting edge diameter [)
, H=(01 to 0.11) DI is set within the range. Also, in this case, the chip pocket (
The rising inclination angle β of 10) is generally set to a maximum of 45° from the viewpoint of chip evacuation. For example, the cross-sectional shape shown in Table 1 can be adopted in the end mill of Shigegawa based on FIG. 5. In this case, in Table 1, the clearance angle a of the flank surface is set to 15°, and the nJ=inclination angle β of the chip blur (1-+In) is set to 30°.

Margin below Table Margin Below The conventional turbo flute type product shown in Figure 6 is
In terms of cross-sectional area ratio, this corresponds to about 65%, and it can be seen that the cross-sectional area ratio of the product of the present invention is considerably large. This is as mentioned in 1);1.

This is because consideration was given to cutting depth of 0.5 mm or less in the radial direction.

(Cutting Example) An example of cutting in the end mill for finishing according to the present invention will be described below.

For the L shell shape, the cutting edge diameter D1 is l), = φ10mm
It has a four-piece configuration with an axial cutting edge length of 40 mm, and when installed on a milling machine (5.5 kW), the protrusion length from the chuck is 46 mm.
And so. In this case, the invention product 1 A has the cross-sectional shape shown in FIG. 4, and the invention product 13 has the cross-sectional shape shown in FIG. Note that the core thickness inner circumferential surface of product A of the present invention (
Regarding the diameter D2 of 4), I)2=9mm, and the diameter of the arc-shaped part of the flank is 1? For, R = 5.075
It was set to mm. Moreover, the present invention product B is as follows.

N006 in Table 1 was used.

The cutting results are shown in Table 2,
Both the invention product Δ and the invention product B exhibited good cutting conditions. In this case, cutting was 5 wet cutting, which was performed by down cutting.

Note that conventional products as shown in FIG. 6 were also cut under the same conditions, but the perpendicularity of all of them exceeded 30 μm, which was a problem in terms of machining accuracy.

(Effects of the Invention) As explained below, the present invention provides an end mill for finishing with a modified cross-sectional shape and a cutting edge + l In order to become
It has the effect of being applicable as an end mill for L-V.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of an end mill for beards according to the present invention, Fig. 2 is a bottom view thereof, and Fig. 3 is a
A partially enlarged front view of the bottom blade portion, FIG. 4 is an enlarged cross-sectional view, and FIG. 5 is an enlarged cross-sectional view showing a modified example.
FIG. 6 is an enlarged cross-sectional view showing a conventional example. (1)...Fishigawa end mill (2)...-[
Tool body (4)... core thickness inner peripheral surface (5)...
・Land part (6)...Outer peripheral blade (7
)...Margin (8)...Rake face
(9)...Bottom blade 0)...Chip blur

Claims (2)

[Claims] (1) On the outer periphery of the approximately cylindrical tool body (2), a land portion (5) having an outer cutting edge (6) and a margin (7) protrudes from the core thickness circumferential surface (4). In a finishing end mill in which a bottom blade (9) is formed at the tip of the tool body (2), the core thickness circumferential surface (4) is the diameter of the cutting edge. If it is concentric with the circle, and its diameter D_2 is the cutting edge diameter circle D_1, D_2=
(0.080 to 0.99) D_1, and the outer peripheral blade (6) has an axial back taper of 30 mm.
The length L in the radial direction of the bottom blade (9) is set within the range of L = (0.02 to 0.10)D_1 with respect to the cutting edge diameter D_1. , and the first mark angle θ_1 and the second mark angle θ_
2 is θ_1<θ_2, so θ_1=30'~2°, θ
A finishing end mill characterized in that _2 is set within a range of 2° to 5°. (2) A chip pocket (10) formed by hollowing out a part of the core thickness circumferential surface (4) is formed on the rake surface (8).
The maximum depth H from the peripheral cutting edge (6) to the chip pocket (10) is the cutting edge diameter D_1.
The finishing end mill according to claim 1, wherein H=(0.01 to 0.11)D_1.