JPH0871830A - End mill - Google Patents

Abstract

PURPOSE: To prevent the occurrence of cracking from boundary parts and damage caused by these cracking by forming recessed grooves with roundness at a boundary part between the side wall and bottom face of an insert pocket and at the boundary part between the rear wall and bottom face of the insert pocket in order to have the action of stress dispersion and absorption. CONSTITUTION: An obliquely cut part 9 is formed at the boundary part between a rib 7 and the side wall 8 of an insert pocket 5. A longitudinal recessed groove 14 of R0.5-R1.0 (R: radius of curvature) is formed at the boundary part between the side wall 8 and bottom face 10 of the insert pocket 5. A lateral recessed groove 14 of R1.0-R2.0 is formed at the boundary part between the rear wall 13 and the bottom face 10. A flat cut part 12 of 1-2mm in width, vertical to the bottom face 10 is formed at the boundary part between the bottom face 10 of the insert pocket 5 and the side peripheral surface 11 of a tool body 1a. With the formation of the recessed grooves 14, 15, stress caused in these parts is dispersed in multiple directions and also absorbed by the cushioning action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill configured to hold a cutting insert on the tip of a tool body.

[0002]

2. Description of the Related Art Conventionally, there has been used an end mill having an insert pocket formed at a tip portion of a tool body and holding a cutting insert in the pocket.

FIGS. 4 and 5 show such an end mill 20 which has been conventionally used.
Then, a rib 23 is provided in the vicinity of the insert pocket 21 in order to compensate for the decrease in strength of the tool body due to the insert pocket 21 and the flat portion 22 around the insert pocket 21, and a crack is generated from the boundary portion between the flat portion 22 and the rib 23. In order to prevent this, there is a case where the oblique cut portion 24 is formed at this portion.

[0004]

However, the conventional end mill 20 has the following problems.

That is, depending on the shape of the end mill 20, a larger stress is applied to the boundary portion between the side wall surface and the bottom surface of the insert pocket 21 than to the boundary portion between the flat portion 22 and the rib 23, and a crack is generated from this portion. I had to do it.

In addition, the tool body 25 is used for machining a small diameter.
When the diameter of the tool body 25 is reduced, the strength of the tool body 25 becomes insufficient, and cracks are generated or broken at the boundary portion between the flat portion 22 and the rib 23, etc. However, there is a problem in that it is impossible to manufacture a practical end mill 20 corresponding to the above.

[0007]

In order to solve the above-mentioned problems of the prior art, in the present invention, a vertical groove of R0.5 to R1.0 is formed at the boundary between the side wall surface and the bottom surface in the insert pocket. A lateral groove of R1.0 to R2.0 is formed at the boundary between the wall surface and the bottom surface, and a width of 1 to 2 mm perpendicular to the bottom surface of the insert pocket and the side peripheral surface of the tool holder. The flat cut portion of

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an end mill 1 according to an embodiment of the present invention. The end mill 1 has an insert pocket 5 for holding a cutting insert 4 at a tip portion 3 located on the tip side of a shank 2 of a tool body 1a and rotation of the insert pocket 5. Chip pockets 6 and ribs 7 are formed on the direction side.

FIG. 2 is an enlarged view of the area A of the end mill 1 shown in FIG. 1. As shown in FIG. 2, an oblique cut portion 9 is formed at the boundary between the rib 7 and the side wall surface 8 of the insert pocket 5. An R-shaped vertical groove 14 is formed at the boundary between the side wall surface 8 and the bottom surface 10 of the insert pocket 5, and an R-shaped lateral groove 15 is formed at the boundary between the rear wall surface 13 and the bottom surface 10.
And the bottom surface 10 of the insert pocket 5 is formed.
And a flat cut portion 12 perpendicular to the bottom surface 10 is formed at a boundary portion of the side peripheral surface 11 of the tool body 1a.

FIG. 3 is a view of the end mill 1 of FIG. 1 as viewed from the tip side. The outer dotted line represents the machining diameter, and the inner dotted line represents the diameter of the tool body 1a when the flat cut portion 12 is not provided. ing.

The end mill 1 thus constructed has the following actions and effects.

First, by forming an R-shaped concave groove in the boundary portion between the side wall surface 8 and the bottom surface 10 of the insert pocket 5, the stress generated in this portion is dispersed in multiple directions, and the stress is generated by the cushioning action. Therefore, it is possible to prevent the occurrence of cracks or damage from this portion.

Further, by forming a flat cut portion 12 perpendicular to the bottom surface 10 of the insert pocket 5 and the side peripheral surface 11 of the tool holder, as shown in FIG. The tool body 1a has a feature that the diameter thereof can be maximized, the strength of the tool body 1a is maintained, and the machining diameter that can be cut can be made as small as possible.

The size of the vertical groove 14 is R
The range of 0.5 to R1.0 is preferable because the stress dispersibility or stress absorbability is excellent. On the other hand, R
When it is less than 0.5, the stress dispersibility or stress absorbability is insufficient and cracks may occur, while R
If it is larger than 1.0, the thickness of this portion becomes small and the strength becomes insufficient, so that cracks or damage may occur.

The size of the lateral groove 15 is R
The range of 1.0 to R2.0 is preferable because the stress dispersibility or the stress absorbability is excellent. On the other hand, R
If it is less than 1.0, the above-mentioned stress dispersibility or stress absorbability is insufficient and cracks may occur, while R
If it is larger than 2.0, the thickness of this portion becomes small and the strength becomes insufficient, so that cracks or damage may occur.

Further, the width of the flat cut portion 12 is preferably in the range of 1 to 2 mm. On the other hand, when this width is smaller than 1 mm, the flat cut portion 12
As compared with the case where there is no, the ratio that the diameter of the tool body 1a can be increased with respect to a certain machining diameter is small, and the effect hardly appears.
There is a possibility that the side peripheral surface 11 of will interfere.

Example 1 An end mill 1 of this example shown in FIGS. 1 to 3,
An end mill 1 in which the size of the vertical groove 14 is R0.5 and the size of the horizontal groove 15 is R1.0 is used, and as a comparative example, an end mill in which only the horizontal groove 15 (R1.0) is formed, and Using an end mill that does not form either, continuous cutting was performed under the following conditions, and the time until cracks were generated was measured. If the cutting endurance time is 21 minutes or longer, cracks or the like will not occur in normal cutting, and if it is shorter than 21 minutes, cracks or the like may occur in normal cutting.

(Conditions) Cutting speed 100 m / min. (Number of revolutions 1592 r.pm) Cut 6 mm long × 4.5 mm wide Feed 0.2 mm / blade (table feed 955 mm / min) Work material S50C As a result, it was 41 minutes 27 seconds with the end mill 1 of this example. On the other hand, it was 20 minutes and 37 seconds in the end mill in which only the lateral groove 15 (R1.0) was formed, and 5 minutes and 5 seconds in the end mill in which neither was formed.

Example 2 An end mill 1 of this example shown in FIGS. 1 to 3,
The same measurement as in Example 1 was performed using the end mill 1 in which the size of the lateral groove 15 was changed to R1.5 and the size of the lateral groove 15 was changed as shown in Table 1. The results are shown in Table 1.

[0020]

[Table 1]

As is clear from Table 1, the vertical groove 14 is formed.
When the size of R is in the range of R0.5 to R1.0, the stress dispersibility or stress absorbability is excellent, and the cutting durability time is 21 minutes or more. It was On the other hand, when it is less than R0.5, the stress dispersibility or stress absorbency is insufficient, the cutting durability time is shorter than 21 minutes, and cracks may occur,
On the other hand, even when R1.0 is larger than this, the thickness of this portion becomes small, resulting in insufficient strength, and the cutting durability time is also shorter than 21 minutes, and it has been found that cracks and breakage may occur.

Example 3 An end mill 1 of this example shown in FIGS. 1 to 3,
The same measurement as in Example 1 was performed using the end mill 1 in which the size of the vertical groove 14 was changed to R0.7 and the size of the horizontal groove 15 was changed as shown in Table 2. The results are shown in Table 2.

[0023]

[Table 2]

As is apparent from Table 2, the vertical groove 14
When the size of R is in the range of R1.0 to R2.0, the stress dispersibility or stress absorbability is excellent, and the cutting durability time is 21 minutes or more, so it is understood that the strength is excellent. It was On the other hand, when it is smaller than R1.0, the stress dispersibility or stress absorbability is insufficient, the cutting durability time is shorter than 21 minutes, and cracks may occur,
On the other hand, when R2.0 is exceeded, the thickness of this portion becomes small, resulting in insufficient strength, and the cutting durability time is also shorter than 21 minutes, and it has been found that cracks and breakage may occur.

[0025]

As described above, according to the end mill of the present invention, the boundary portion between the side wall surface and the bottom surface of the insert pocket and the boundary portion between the rear wall surface and the bottom surface have the effect of stress dispersion and stress absorption. In order to make it possible to form the R-shaped concave groove, and these concave grooves have the sizes of R0.5 to R1.0 and R1 to R2, respectively, a crack is generated or a breakage occurs from this portion. It is possible to prevent this from happening, and by forming a flat cut portion with a width of 1 to 2 mm perpendicular to the bottom surface of the insert pocket and the side peripheral surface of the tool holder, the diameter of the tool body relative to the machining diameter can be reduced. It has an excellent effect that it can be maximized, the strength of the tool body can be maintained, and the cutting diameter that can be cut can be made as small as possible.

[Brief description of drawings]

FIG. 1 is a perspective view of an end mill according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a region A in FIG.

3 is a view of the end mill of FIG. 1 seen from the tip side,
The outer dotted line represents the machining diameter, and the inner dotted line represents the diameter of the tool body when the flat cut portion is not provided.

FIG. 4 is a plan view of a conventional end mill.

5 is a view on arrow B of the end mill of FIG. 4. FIG.

[Explanation of symbols]

 1 End Mill 1a Tool Body 2 Shank 3 Tip 4 Cutting Insert 5 Insert Pocket 6 Chip Pocket 7 Rib 8 Side Wall 9 Oblique Cut 10 Bottom 11 Side Peripheral 12 Flat Cut 13 Rear Wall 14 Vertical Groove 15 Horizontal Groove A region

Claims (1)

[Claims] 1. An end mill having an insert pocket for holding a cutting insert formed at a tip portion of a tool body, wherein a vertical length of R0.5 to R1.0 is provided at a boundary portion between a side wall surface and a bottom surface in the insert pocket. R1.0-R2.0 lateral grooves are formed at the boundary between the rear wall surface and the bottom surface, and the groove is formed at the boundary between the bottom surface of the insert pocket and the side peripheral surface of the tool holder. An end mill having a flat cut portion having a vertical width of 1 to 2 mm.