JP2003300112A - Square end mill - Google Patents

Abstract

(57) [Problem] A square in which a plurality of twisted chip discharge grooves and an outer peripheral cutting edge are formed on the outer periphery of a rotary shaft, and a bottom blade is formed at the tip of the rotary shaft from the outer peripheral cutting edge toward the shaft center. In an end mill, the cutting edge strength and the cutting performance at the corner where the outer peripheral cutting edge and the bottom blade intersect are improved, and the chip discharge performance is improved. SOLUTION: A plurality of twisted chip discharge grooves 11 and an outer peripheral cutting edge 12 are formed on the outer periphery of a rotating shaft 10, and a bottom blade 13 is formed at the tip of the rotating shaft from the outer peripheral cutting edge toward the shaft center. In the square end mill, a flat first gash surface 14a extending from the bottom edge to the outer peripheral cutting edge on the tip side of the rotating shaft is provided, and a first gash surface 14a is provided between the first gash surface and the chip discharge groove.
A second gash surface 14b having a larger rake angle in the axial direction than the gash surface was provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill used for cutting such as metal shoulder processing and groove processing, and more particularly,
The present invention relates to a square end mill in which a plurality of twisted chip discharge grooves and an outer peripheral cutting edge are formed on the outer periphery of a rotary shaft, and a bottom blade extending from the outer peripheral cutting edge toward the shaft center is formed at the tip of the rotary shaft. is there.

[0002]

2. Description of the Related Art Conventionally, end mills have been used for cutting such as shouldering and grooving of metal. As one of such end mills, horizontal and axial cutting can be performed. Square end mills are known.

As such a square end mill, as shown in FIG. 1, a plurality of twisted chip discharge grooves 11 and outer peripheral cutting blades 12 are formed on the outer periphery of the rotary shaft 10 and the rotary shaft 10 is also formed. Generally, a tip having a bottom blade 13 extending from the outer peripheral cutting edge 12 toward the axial center is used.

Further, in such a square end mill, the edge strength at the corner portion C where the outer peripheral cutting edge 12 and the bottom blade 13 intersect each other is enhanced, and the dischargeability of the chips cut by the bottom blade 13 is enhanced. For the bottom blade 13
Gash is provided in the part.

Here, in providing the gash in the portion of the bottom blade 13 as described above, in the conventional case, as shown in FIG.
As shown in (A) and (B), from the bottom blade 13 to the rotary shaft 10
Is provided with a flat gash surface 14 so as to reach the outer peripheral cutting edge 12 on the tip side, or as shown in FIGS. 3 (A) and 3 (B),
The gash surface 14 is provided only on the bottom blade 13 so as not to reach the outer peripheral cutting edge 12.

However, as shown in FIGS. 2A and 2B, when only the flat gash surface 14 extending from the bottom blade 13 to the outer peripheral cutting edge 12 on the tip side of the rotary shaft 10 is provided,
There is a problem that the chips cut by the bottom blade 13 become wider, the chip discharge property deteriorates, and the chips are easily welded.

Further, as shown in FIGS. 3 (A) and 3 (B),
When the gash surface 14 is provided only on the portion of the bottom blade 13 so as not to reach the outer peripheral cutting edge 12, the edge strength at the corner portion C where the outer peripheral cutting edge 12 and the bottom blade 13 intersect becomes weak, and these There is a problem that the cutting edges 12 and 13 tend to be chipped.

Therefore, in recent years, Japanese Patent Laid-Open No. 6-2
As disclosed in Japanese Patent No. 18616, there is proposed an end mill in which a gash surface extending from the bottom blade to the outer peripheral cutting edge on the tip end side of the rotary shaft is formed into a plurality of flat planes or curved surfaces.

However, in the case of the end mill disclosed in this publication, the rake angle of the outer peripheral cutting edge at the corner portion becomes negative, the machinability is remarkably deteriorated, and streaks corresponding to the bent portion are generated in the work material. As a result, the precision of the finished surface is deteriorated and the bent portion is damaged.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a plurality of twisted chip discharge grooves and an outer peripheral cutting edge are formed on the outer periphery of a rotary shaft, and the outer peripheral cutting edge extends from the center of the shaft at the tip of the rotary shaft. It is an object of the present invention to solve the above-mentioned various problems in a square end mill in which a bottom blade directed to the side is formed.

That is, in the square end mill according to the present invention, the cutting edge strength is improved at the corner portion where the outer peripheral cutting edge and the bottom blade intersect, the chip discharging property is improved, and the cutting performance of the outer peripheral cutting edge at the corner portion is improved. It is an object of the present invention to stably perform cutting with a high finished surface accuracy without deteriorating.

[0012]

According to the present invention, in order to solve the above problems, a plurality of twisted chip discharge grooves 11 and an outer peripheral cutting edge 12 are formed on the outer periphery of a rotary shaft 10, and The outer peripheral cutting edge 1 is attached to the tip of the rotary shaft 10.
In a square end mill in which a bottom blade 13 extending from 2 to the shaft center is formed, a flat first gash surface 14 extending from the bottom blade 13 to the outer peripheral cutting edge 12 on the tip side of the rotary shaft 10 is provided.
A is provided, and a second gash surface 14b having a larger axial rake angle than the first gash surface 14a is provided between the first gash surface 14a and the chip discharge groove 11.

Then, in the square end mill according to the present invention, as described above, the bottom blade 13 to the rotary shaft 10 are rotated.
Since the flat first gash surface 14a is formed to reach the outer peripheral cutting edge 12 on the front end side of the blade, it is possible to prevent the cutting edge strength from decreasing in the corner portion C where the bottom blade 13 and the outer peripheral cutting edge 12 intersect. At the same time, the bottom blade 13 does not have a bent portion due to its linear shape, and it is possible to suppress the generation of lines corresponding to the bent portion in the work material, and improve the finished surface accuracy.

Further, in the square end mill according to the present invention, as described above, the first gash surface 14a is provided between the first gash surface 14a and the chip discharge groove 11.
The second gash surface 14b having a larger axial rake angle than
Since the chip pocket becomes large, the chips cut by the outer peripheral cutting edge 12a in the bottom blade 13 and the corner portion C become the boundary between the first gash surface 14a and the second gash surface 14b. Will be cut and shortened, the chip discharge property will be improved, and welding of chips will be prevented.

Here, in forming the flat first gash surface 14a extending from the bottom blade 13 to the outer peripheral cutting blade 12 on the tip side of the rotary shaft 10 as described above, the corner formed by the first gash surface 14a. If the outer peripheral cutting edge 12a in the portion C does not exist, the cutting edge strength in the corner portion C cannot be improved, while if the outer peripheral cutting edge 12a in the corner portion C becomes too long, the bottom blade 13 causes Since the dischargeability of the cut chips is deteriorated, the length of the outer peripheral cutting edge 12a in the corner portion C formed by the first gash surface 14a is
It is preferably in the range of 0.01 to 0.5 mm.

Further, the second gash surface 1 is provided between the first gash surface 14a and the chip discharge groove 11.
As long as 4b has an axial rake angle larger than that of the first gash surface 14a as described above, its shape and the like are not particularly limited, and may be linear or twisted. Also, it may have a concave shape in an arc shape.

Further, in the square end mill according to the present invention, if the corner portion C where the above-mentioned bottom blade 13 and the outer peripheral cutting edge 12 intersect is made angular, it becomes possible to perform groove processing in which the corner portion has a right angle. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A square end mill according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings,
When the square end mill according to the embodiment of the present invention is used, it is possible to improve the chip discharge property without lowering the cutting edge strength at the corner portion where the outer peripheral cutting edge and the bottom blade intersect, a comparative example is given. To clarify.

In the square end mill according to this embodiment, as shown in FIG. 4, four twisted chip discharge grooves 1 are provided on the outer circumference of a rotary shaft 10 made of fine grain cemented carbide.
1 and four outer peripheral cutting edges 12 corresponding to the four chip discharge grooves 11, and a bottom blade 13 extending from each of the outer peripheral cutting edges 12 toward the axial center at the tip of the rotary shaft 10. is doing

The flat first gash surface 1 extending from the bottom blade 13 to the outer peripheral cutting edge 12 on the tip side of the rotary shaft 10 is described.
4a is provided, and further, a second gash surface 14b having a larger axial rake angle than the first gash surface 14a is provided between the first gash surface 14a and the chip discharge groove 11.

Here, in the square end mill in this embodiment, as shown in FIGS. 4 to 7, a rotary shaft 10 having a diameter D of 12.0 mm is used, and the twist angle φ of each of the above chip discharge grooves 11 is set. 45 °, the water mark angle α of the bottom blade 13 is 3
°, the clearance angle β1 of the bottom blade 13 is 6 °, the clearance angle β2 of the bottom blade 13 is 20 °, the clearance angle γ1 of the outer peripheral cutting edge 12 is 10 °, and the clearance angle 3 of the outer peripheral cutting edge 12 is The angle γ2 is set to 25 °.

In providing the first gash surface 14a and the second gash surface 14b, first, the axial rake angle θ1 of the bottom blade 13 by the first gash surface 14a is set to 5 °. With an approach angle of 40 °,
A flat first gash surface 14a extending from the bottom blade 13 to the outer peripheral cutting edge 12 on the tip side of the rotary shaft 10 was formed. Although not shown, in the state where only the first gash surface 14a is formed, the length of the outer peripheral cutting edge 12a in the corner portion C formed by the first gash surface 14a is 0.3 mm. It was.

Next, the axial rake angle θ is set so as to reach the chip discharge groove 11 from the first gash surface 14a.
The second gash surface 14b in which 2 was 20 ° was formed. In the state where the second gash surface 14b is formed in this manner, the length δ of the outer peripheral cutting edge 12a in the corner portion C formed by the first gash surface 14a is 0.05 mm.

On the other hand, in the square end mill of the comparative example, like the conventional square end mill shown in FIGS. 2A and 2B, in the square end mill of the above embodiment, only the first gash surface 14a is formed. It was formed so that the second gash surface 14b was not formed.

Then, after coating each of the square end mills of the above-mentioned examples and comparative examples with TiAlN, a cutting speed of 100 m / min and a feed rate of 0.2 mm were applied to a workpiece made of S50C having a Shore hardness of HS30.
/ R, a cutting depth of 18 mm in the axial direction, and a cutting width of 1.2 mm in the radial direction, shoulder processing with a cutting length of 300 mm was performed, and the cutting edge at the corner portion C of each square end mill was examined. In the square end mill, welding of chips was generated in the corner portion C, whereas in the square end mill of the example, welding of chips was not generated at all in the corner portion C.

Further, as a result of performing the above-mentioned 300 mm shoulder machining 10 times under the above conditions and examining the cutting edge at the corner portion C of each square end mill, in the square end mill of the comparative example, TiAl at the corner portion C was obtained.
While the N coating was peeled off and the abrasion was increased, in the square end mill of the example, the welding of chips was not generated in the corner portion C, and T
The iAlN coating was not peeled off and the wear was small.

[0027]

As described in detail above, in the square end mill according to the present invention, a flat first gash surface extending from the bottom blade to the outer peripheral cutting edge on the tip side of the rotary shaft is formed,
Further, since the second gash surface having a larger rake angle in the axial direction than the first gash surface is provided between the first gash surface and the chip discharge groove, the bottom blade and the outer peripheral cutting are provided by the first gash surface. The edge strength at the corner where the blade intersects is increased, and the bottom blade is prevented from becoming linear and streaks are generated in the work material, and the chip pocket is enlarged by the second gash surface. At the same time, chips cut by the bottom blade and the outer peripheral cutting edge at the corners are cut at the boundary between the first gash surface and the second gash surface and shortened, resulting in improved chip discharge performance and welding of the chips. It has come to be prevented from doing.

As a result, in the square end mill according to the present invention, it is possible to stably perform the cutting work with a good finished surface accuracy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a conventional square end mill.

FIG. 2 is a schematic explanatory view of a conventional square end mill in which only a flat gash surface is provided from the bottom blade to the outer peripheral cutting edge on the tip side of the rotary shaft, and a schematic view showing the state of the tip. Is.

FIG. 3 is a schematic explanatory view of a conventional square end mill in which a gash surface is provided only on a bottom blade so as not to reach an outer peripheral cutting edge, and a schematic view showing a state of the tip thereof.

FIG. 4 is a schematic explanatory view of a square end mill according to an embodiment of the present invention.

FIG. 5 is a partially enlarged explanatory view of a corner portion where a bottom blade and an outer peripheral cutting edge intersect in the square end mill according to the above-described embodiment.

FIG. 6 is a partially enlarged explanatory view of a bottom blade portion in the square end mill according to the above embodiment.

7 is a sectional view taken along line XX in FIG. 5 described above.

[Explanation of symbols]

10 Rotating Shaft 11 Chip Discharge Groove 12 Outer Peripheral Cutting Edge 12a Outer Peripheral Cutting Edge of Corner 13 Formed by First Gash Surface 13 Bottom Blade 14a First Gash Surface 14b Second Gash Surface θ1 Axial Rake Angle θ2 of First Gash Surface Axial rake angle of the second gash surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takamitsu Iizuka             2-1-1 Kamihigashi, Hirano-ku, Osaka             Inside Jet Industrial Co., Ltd. F-term (reference) 3C022 KK03 KK06 KK23 KK25 KK28

Claims (2)

[Claims] 1. A plurality of twisted chip discharge grooves 11 and a peripheral cutting edge 12 are formed on the outer circumference of a rotary shaft 10, and a bottom of the rotary shaft 10 extends from the outer peripheral cutting edge 12 toward the center of the shaft. In the square end mill in which the blade 13 is formed, a flat first gash surface 14a extending from the bottom blade 13 to the outer peripheral cutting edge 12 on the tip side of the rotary shaft 10 is provided, and the first gash surface 14a and the chip discharge groove are provided. A square end mill having a second gash surface 14b having a larger axial rake angle than the first gash surface 14a described above. 2. The square end mill according to claim 1, wherein a corner portion C where the bottom blade 13 and the outer peripheral cutting edge 12 intersect is angular.